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BACKGROUND: Polyvinylidene fluoride (PVDF) with piezoelectric properties, good biocompatibility and nontoxicity make it a suitable candidate for periosteal repair. OBJECTIVE: To evaluate the cytotoxicity of PVDF bionic periosteum by electrospinning with zinc and magnesium ions in vitro. METHODS: Pure PVDF, zinc-doped PVDF, magnesium-doped PVDF and Zinc-magnesium ion PVDF piezoelectric bionic periosteum were prepared by electrospinning technology, respectively. They were named PVDF, PVDF-Zn, PVDF-Mg and PVDF-Zn-Mg, in which the mass fraction of zinc and magnesium ions were all 1%. Osteoblasts and vascular endothelial cells were co-cultured with four groups of bionic periosteum. Cell compatibility of bionic periosteum was determined by alkaline phosphatase staining, CD31 immunofluorescence staining, and scanning electron microscopy. RESULTS AND CONCLUSION: (1) Osteoblasts: Alkaline phosphatase staining after 7 days of culture showed that the PVDF-Zn group secreted more alkaline phosphatase than the other three groups. Under a scanning electron microscopy, after 1 day of culture, the cells had a certain spread on the surface of PVDF-Mg and PVDF-Zn-Mg bionic periosteum, and the pseudopod extended to all sides. On day 3, the cell edge of each group extended pseudopods to the material. By days 5 and 7, the cells were fully spread, well grown and firmly covered the surface of the fibers, and the cellular pseudopods extended around and into the interstitial space of the fibers. CCK-8 assay showed that the cell proliferation on the bionic periosteum of each group showed an increasing trend over time and the relative proliferation rate of cells at 1, 3, 5, and 7 days was ≥75%, and the cytotoxicity was ≤ grade 1. (2) Vascular endothelial cells: CD31 immunofluorescence staining for 3 days showed that the cells adhered and spread well on the bionic periosteum of each group and connected with each other, and the number of cells in the PVDF-Zn-Mg group was more than that in the other three groups. Under scanning electron microscope, the cells began to adhere to the surface of each group of fibers after 1 and 3 days of culture. On day 5, the cells were well spread on the surface of the fibers and extended obvious pseudopods. On day 7, the cells on the PVDF-Mg and PVDF-Zn-Mg bionic periosteum grew in multiple layers and extended the pseudopod into the fibrous void. CCK-8 assay showed that the cell proliferation on the bionic periosteum of each group showed a downward trend over time, and the relative proliferation rate of cells at 1, 3, 5 and 7 days was ≥125%, and the cytotoxicity was grade 0. (3) The results showed that Zn-Mg electrospun PVDF piezoelectric bionic periosteum had good cytocompatibility. [ABSTRACT FROM AUTHOR]

With the increasing consumption of easily sorted copper sulfide, the development of copper oxide is particularly important. To solve the problem of insufficient collecting ability of the collector by direct flotation method, BPHA was synthesized from dimethyl phthalate and hydroxylamine hydrochloride, and BPHA was applied to the flotation recovery of malachite. The micro flotation test results show that the maximum flotation recovery of chrysocolla can reach 75. 2% under the flotation condition of pH 9. 0 and BPHA dosage 120 mg/L. Through the analysis! of contact angle and adsorption capacity, t is concluded that BPHA can improve the contact angle and hydrophobic of the surface of chrysocolla. Through infrared spectroscopy (FT-IR), X-ray electron spectroscopy (XPS)and scanning electron microscope energy spectrometer(SEM-EDS)analysis 1 is found that the agent adsorbed on the mineral surface, changed the chemical properties of the mineral surface, and formed hydrophobic BPHA:Cu species on the mineral surface after the interaction of BPHA with chrysocolla. Thus, the floatability of malachite is increased. [ABSTRACT FROM AUTHOR]

BACKGROUND: Cartilage decellularized extracellular matrix (dECM) is an ideal biomaterial for the preparation of cartilage tissue engineering scaffolds, which can be used to repair cartilage defects. OBJECTIVE: To use polyvinyl alcohol (PVA) as the loading material of dECM and poly3-hydroxybutyrate 4-hydroxybutyrate (P34HB) as the frame material to prepare P34HB-PVA-dECM composite nanofiber scaffolds by two-needle electrospinning, and preliminarily explore the bioactivity of the scaffolds in vitro. METHODS: The cellular components in the cartilage tissue were removed by a combination of enzyme, chemical, and ultrasonic concussion cleaning methods to prepare cartilage dECM. P34HB, P34HB-PVA, and P34HB-PVA-dECM scaffolds were prepared by two-neezle electrospinning. The fiber morphology, composition, hydrophilicity, and mechanical properties of the scaffolds were characterized. Human bone marrow mesenchymal stem cells were co-cultured with the three kinds of scaffolds. The viability of cells on scaffolds was evaluated by the Live/Dead staining. The adhesion morphology of the cells on the scaffolds was observed by scanning electron microscopy. The proliferation performance of the cells on the scaffolds was detected by the alamar blue kit. The chondrogenic differentiation of human bone marrow stem cells on the scaffolds was evaluated by type II collagen immunofluorescence. RESULTS AND CONCLUSION: (1) Scanning electron microscopy results showed that the scaffold fibers in each group were randomly distributed and the interconnections between the fibers showed a porous structure. The fiber diameter of P34HB-PVA-dECM scaffolds was the smallest. The P34HB-PVA-dECM scaffolds had the smallest water contact angle (P < 0.05) and the highest water absorption rate compared with the P34HB and P34HB-PVA scaffolds (P < 0.05). The elastic modulus of the P34HB-PVA-dECM scaffolds was higher than that of the P34HB and P34HB-PVA scaffolds (P < 0.05). (2) Live/Dead staining showed that most cells survived well on the three groups of scaffolds. The scanning electron microscope observation showed that the bone marrow mesenchymal stem cells on P34HB-PVA-dECM scaffolds extended pseudopod more fully and fused better with the scaffolds. Alamar blue staining exhibited that the proliferation rate of bone marrow mesenchymal stem cells on the P34HB-PVA-dECM scaffolds was faster than that on the P34HB and P34HB-PVA scaffolds (P < 0.05). The immunofluorescence staining results showed that more type II collagen produced after chondrogenic induction on the P34HB-PVA-dECM scaffolds was more than that on the P34HB and P34HB-PVA scaffolds (P < 0.05). (3) To sum up, the P34HB-PVA-dECM composite nanofiber scaffolds have smaller fiber structure, more optimized hydrophilicity and mechanical properties, which is more favorable for the adhesion, proliferation, and differentiation into chondrocytes of bone marrow mesenchymal stem cells. [ABSTRACT FROM AUTHOR]

BACKGROUND: It has been found that the mechanical properties of nano-hydroxyapatite can be improved by doping zinc ions in nano-hydroxyapatite. OBJECTIVE: To investigate the biological properties of nano-hydroxyapatite ceramic scaffold mixed with different concentrations of zinc oxide, and to study the effects of the scaffold on the biological behavior of MC3T3-E1 osteoblasts. METHODS: Nano-hydroxyapatite ceramic scaffolds containing different mass fractions (0%, 0.5%, 1.5%, 2.5%, 3.5%) of zinc oxide were prepared by a chitin gel system to characterize the physical properties of scaffolds. The five groups of nano-hydroxyapatite-zinc oxide composite scaffolds were co-cultured with MC3T3-E1 osteoblasts. Calcein AM/PI staining, CCK-8 assay, CellTiter LumiTM Luminescent assay, alkaline phosphatase activity detection, alizarin red staining, and quantitative analysis of calcium ions were detected. RESULTS AND CONCLUSION: (1) Under a scanning electron microscope, the surface of the nano-hydroxyapatite-zinc oxide composite scaffolds had three dimensional perforated pores. The pore size of the composite scaffolds was uniform, ranging from 300 to 400 μm, and the porosity was above 70%. With the increase of the mass fraction of zinc oxide, the compressive strength of the composite scaffold increased gradually. (2) Calcein-AM/PI staining showed no obvious cytotoxicity in the five groups, and the survival rate of cells in the 2.5% group was higher than that in the 0% group (P < 0.05). CCK-8 assay and CellTiter-LumiTM luminescent assay showed that cell proliferation and activity of each group were in the order from strong to weak: 2.5% group >1.5% group > 0.5% group > 0% group > 3.5% group. The order of alkaline phosphatase activity from high to low was 2.5% group > 1.5% group > 3.5% group > 0.5% group > 0% group. Alizarin red staining and quantitative analysis of calcium ions showed that the formation ability of cell mineralized nodules was in the order of 2.5% group > 1.5% group > 0.5% group > 3.5% group > 0% group from strong to weak. (3) The results showed that zinc oxide doping improved the mechanical properties of nano-hydroxyapatite scaffolds and promoted the proliferation and differentiation of osteoblasts, among which the composite scaffolds doped with 2.5% zinc oxide had the best proliferation and differentiation ability of osteoblasts. [ABSTRACT FROM AUTHOR]

Ag2SO3/AgBr composite was prepared by precipitation-in situ chemical deposition method and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). Furthermore, the catalytic degradation of a methylene blue solution under visible light irradiation was investigated. This experiment showcases clear phenomena and offers a high level of operability, making it easily accessible for students to acquire a comprehensive understanding of photocatalytic experimental techniques. Moreover, the experiment is closely linked to both cutting-edge research and the fundamental chemistry concepts related to precipitation and dissolution equilibrium, fostering students' intrinsic motivation to learn and establish a strong connection between college-level chemistry and basic chemistry education. Furthermore, by encouraging students to improve and innovate the experiment from various perspectives, this experiment nurtures their innovative thinking and application abilities, providing valuable training for future chemists in normal universities. [ABSTRACT FROM AUTHOR]

The surface of PMN-PT relaxor ferroelectric single crystal was coated with medium and high temperature Ag paste by screen printing process. Ag electrodes were prepared by rapid sintering process at 650 and 850 °C, respectively. The microstructure of Ag electrode surface and metal-crystal interface was observed by scanning electron microscope. The distribution of elements at the interface was analyzed by energy spectrum. The Ag electrode has a thickness of tens of microns, a porous structure, and a good combination with crystals. After sintering, atoms such as Pb, Nb and Ti in the crystal migrate to the Ag electrode, and a transition layer of several microns thickness is formed at the interface after sintering of the high temperature Ag paste, which greatly reduces the migration of atoms in the crystal to the electrode. PMN-PT wafers with different crystal orientation have a strong crystal face effect during the diffusion process to the Ag electrode at high temperature, and the diffusion degree of Pb, Nb and Ti atoms in the [110] direction crystal is smaller than that in the [100] direction crystal. [ABSTRACT FROM AUTHOR]

The experiment aimed to use wood rot fungi co-culture to pretreat biomass to improve lignin enzyme yield, lignin degradation and biomass resource utilization. Three kinds of wood-decay fungusi were co-cultured to pretreat corn stalks, and their ligninolytic enzymes yield and degradation efficiency were compared. The results showed that on the 20th day, the manganese peroxidase activity of corn stalks pretreated by three kinds of wood-decay fungus was significantly higher than that of single wood-decay fungus (P<0.05). The manganese peroxidase activity of corn straws co-cultured by Irpex lacteus and Fomitopsis pinicola was 933.82 U/L, which was 3.11 times that of pretreated by Fomitopsis pinicola alone. The co-culture of Cerrena unicolor and Irpex lacteus, as well as the co-culture of Irpex lacteus and Fomitopsis pinicola showed inhibitory effect on the production of laccase. Infrared spectrum analysis, lignin content determination and scanning electron microscope photos showed that the characteristic peaks of Cerrena unicolor and Fomitopsis pinicola co-cultured for 40 d were the most obvious, the lignin degradation rate was the highest, reaching 45.75%, and the surface damage of corn straw was serious. The experiment indicates that compared with the monoculture, corn straw pretreated by co-culture of different wood-decay fungus can significantly increase the yield of manganese peroxidase or the degradation rate of lignin in a certain culture time, but the activity of ligninase is not completely consistent with the degradation rate of lignin. [ABSTRACT FROM AUTHOR]

The microstructure, damprng behavior and mechanical properties of direciionally solidiiied MnCu-based alloys with different chemical compoiiioon gradients were studied via uimg dynamic thermomechanical analyzer, Opiical Microscope, X-Ray Diffractometer and Scanning Electron Microscope. The results show that duiing direciional solidieicaeion,the dendiite spaing gradually decreaseslthe degree of component segregaiion increases,and the phase consiituent becomes a ingle parent phase with the addieion of alloying llemente. The compoeieion supercooing caused by entropy increase makes the dendiites prone to fracture. The addiiion of nickll and iron Increases the internal fiiciion value of the low-temperature twin, after adding Zn,the Internal fiiciion value of the MnCuNiFeZn alloy at 673 K iises to 0. 023. With the increase of mixed entropy,the teniile strength and elongaiion of the three alloys increase lineaely,and the llope of the stable holing seciion of the alloy strain hardening rate is poeieively comlated with the entropy of mixing. [ABSTRACT FROM AUTHOR]

The fern genus Microlepia is a natural fern group, while large morphological differences of this genus lead to some classification controversies. The leaf epidermal micromorphology of 18 species( include 3 varieties )of Microlepia was observed and compared under light microscope( LM )and scanning electron microscope( SEM ). Hairs were on the veins of the upper and lower epidermis. The form of epidermal cells was irregular, with the anticlinal walls sinuous or sinuate. The stomatal apparatus of all species were restricted to abaxial epidermises and generally could be described as polocytic and axillocytic type, and copolocytic, coaxillocytic, aisocytic and anomotetracytic type only appears in a few species. The similarity of the micromorphological characteristics of leaf epidermis support that the genus Microlepia is a monophyletic group in Dentaedtiaceae. The hairs characteristics between veins of the leaves support that M. calvescens, M. marginata var. villosa and M. marginata var. bipinnata should be treated as a variety of M. marginata. Under SEM, the cuticle of the upper epidermis was mostly ridged, and most of them had filiform ornamentation. The characteristics of leaf cuticle ornamentation were correlated with pinnate compound leaves. The inner margin of the outer stomatal rim was often smooth, sinuous or odontoid. “T” sharp, upright outer stomatal rims occurred in most species, and outer stomatal ledge was mostly depressed. The differences among the leaf micromorphology of these species were shown, which provides references for the classification, evolution and system location of Microlepia. [ABSTRACT FROM AUTHOR]

BACKGROUND: It is difficult for a single biomaterial to reach the standard of an ideal scaffold material for bone tissue engineering. It is an effective way to construct an ideal scaffold by compounding and complementing the advantages of multiple biomaterials. OBJECTIVE: To construct a new type of mandibular scaffold, and test the key physicochemical properties of the scaffold. METHODS: Antimicrobial peptide-loaded carboxymethyl chitosan/bone powder/cellulose nanocrystals scaffold was prepared by freeze-drying method. The microstructure of the scaffold was observed and analyzed, and the tensile strength and elongation at break of the scaffold were measured. The water absorption, degradation rate in vitro, thermal stability and release of antimicrobial peptide of the scaffold were evaluated. RESULTS AND CONCLUSION: (1) Scanning electron microscope showed that the scaffolds had a uniform porous network structure with an average pore size of 114. 9 μm. The water absorption rate of the scaffold was 698.8±53.8%. The fracture elongation of the scaffold was 8%-10%. The tensile strength was 0.7-0.9 MPa, and the stress-strain relationship was similar to that of natural cartilage tissue. (2) Thermogravimetric curve displayed that the weight loss of the stent was very slight below 200 °C, obvious between 200-400 °C, and severe above 600 °C. (3) The results of drug release in vitro showed that (58.40±1.79)% of antibacterial peptide was released from the scaffold within the first 12 hours, and the drug release rate decreased after 12 hours, and nearly 20% of antibacterial peptide was not released after 6 days, which was beneficial to the sustained and stable drug effect. (4) The scaffolds were separately soaked in PBS and PBS containing lysozyme. At 28 days, the degradation rates of scaffolds without lysozyme and with lysozyme were 70% and 85%, respectively. (5) These results exhibited that the carboxymethyl chitosan/bone powder/cellulose nanocrystals scaffold had good water absorption performance, thermal stability, degradation performance and mechanical property. [ABSTRACT FROM AUTHOR]

BACKGROUND: Natural biopolymers have excellent biodegradability. Their structures are similar to natural extracellular matrix, which is conducive to tissue repair. Natural biopolymers have a great potential in developing new absorbable membranes. OBJECTIVE: To develop a new absorbable membrane for guided bone regeneration by incorporating 58S bioglass powders into alginate/chitosan composites and study the physical, chemical and biological properties. METHODS: Alginate/chitosan/bioglass composite membranes were prepared according to the concentration gradient of 0, 5, 7.5 and 10 g/L 58S bioglass. The groups were recorded as 0BG, 0.5BG, 0.75BG and 1BG composite membranes according to the concentration gradient. The morphology of each group of composite membranes was characterized by metallurgical microscope and scanning electron microscope. The physiochemical properties of the resultant polymers were assessed via Fourier transform infrared spectroscopy and swelling ratio in each group. The biological properties of the composite membranes were compared by in vitro degradation experiments, protein adsorption experiments, cell adhesion experiments, cell proliferation experiments and alkaline phosphatase activity tests in each group. RESULTS AND CONCLUSION: (1) Metallurgical microscope and scanning electron microscope showed that samples of each group had the typical porous structure of hydrogel, and the bioglass particles were embedded in the pores of the composite membrane. The porosity of all composite membranes was greater than 90%. The sequence was: 0BG > 0.5BG > 0.75BG > 1BG. (2) Fourier transform infrared spectroscopy exhibited the characteristic peaks of the polymer formed by alginate and chitosan and the evidence of the existence of bioglass in the polymer. The composite membranes with 58S bioglass powders showed certain advantages in swelling ratio, in vitro degradation and biological activity, and this advantage was more obvious with the increase of bioglass content. In particular, 0.75BG and 1BG composite membranes could exhibit a high level of osteogenic differentiation over a long period of time. (3) These results suggested that in the experimental research range, when the mass concentration of 58S bioglass was 7.5 and 10 g/L, the alginate/chitosan/bioglass composite membranes can achieve relatively excellent biological activity, and it has the potential to be applied in the study of guided bone regeneration. [ABSTRACT FROM AUTHOR]

BACKGROUND: Aspirin is a classic non-steroidal anti-inflammatory drug. Appropriate doses of aspirin can regulate immunity and promote osteogenesis. The preparation of bone tissue engineering materials, which can release aspirin, regulate the immune microenvironment of the bone defect area and accelerate the repair of the bone defect, and is a current research focus. OBJECTIVE: To prepare a novel hydrogel scaffold that can modulate the immune microenvironment and quickly repair the bone defect area. METHODS: Hydrogel scaffolds containing 0%, 10% and 20% of nano-hydroxyapatite/aspirin/polyvinyl alcohol/gelatin/sodium alginate were prepared. The microstructure, porosity, chemical composition, crystal structure, drug release properties, mechanical properties, swelling properties and degradation properties of the hydrogel scaffolds were characterized. The biocompatibility of the hydrogel scaffolds was evaluated by cell proliferation and cytotoxicity experiments. RESULTS AND CONCLUSION: (1) Scanning electron microscope and porosity results showed that hydrogel scaffolds in the 0% nano-hydroxyapatite group and 10% nano-hydroxyapatite group had better biomimetic hierarchical porous structure, pore connectivity, and porosity. (2) The results of Fourier transform infrared spectroscopy and X-ray diffraction showed that the raw materials in the hydrogel scaffold were combined by physical and chemical double crosslinking, and the crystal phase structure of nano-hydroxyapatite was not be destroyed. (3) The results of mechanical properties showed that the 10% nanohydroxyapatite group had the best compressive modulus and compressive strength. (4) The results of drug release properties showed that the cumulative release rate of aspirin decreased with the increase of nano-hydroxyapatite, but the drug burst release rate decreased and the sustained release time prolonged. (5) The results of swelling properties and degradation properties showed that with the increase of nano-hydroxyapatite, the swelling rate and degradation rate of hydrogel scaffolds of each group decreased. (6) Using the hydrogel scaffold extract to culture mouse pre-osteoblasts, the results of cell proliferation and cytotoxicity experiments showed that the hydrogel scaffold extract could promote cell proliferation, without cytotoxicity. (7) It is concluded that 10% nanohydroxyapatite hydrogel scaffolds have better bionic characterization and biocompatibility, and are expected to be used as bone tissue engineering scaffolds for further studies of osteogenesis and immunomodulatory potential. [ABSTRACT FROM AUTHOR]

BACKGROUND: Nano hydroxyapatite is an excellent bioactive material, which has a certain protective effect on demineralized enamel and dentin, but the effect and mechanism of its solution on remineralization of demineralized dentin are not clear. OBJECTIVE: To explore the feasibility of nano hydroxyapatite in the prevention and treatment of dentin sensitivity and dentin caries. METHODS: Abandoned human bicuspid specimens were collected, and 72 dentin slice samples were prepared from isolated bicuspids. The samples were randomly divided into 6 groups, with 12 samples per group: After demineralization, each group was immersed in 10% nano hydroxyapatite solution (group A), 6% bioactive glass solution (group B), 10% nano hydroxyapatite and 6% bioactive glass composite solution (group C), 0.05% sodium fluoride (group D), artificial saliva (group E), and deionized water (group F). After 14 days of treatment, working surfaces of samples were observed by scanning electron microscope. The surface composition was detected with energy spectrum analyzer. Dentin Rhodamine B staining was detected under a confocal laser microscope. RESULTS AND CONCLUSION: (1) Scanning electron microscopy: The dentinal tubules orifice in group A was completely sealed, and the surface of the dentin was uniformly covered by a layer of tightly connected granular material. The dentinal tubules in group C were partially sealed. A small amount of scattered particles were found on the dentin surface and in the dentinal tubules of group B, group D and group E, and the dentinal tubules were open. In group F, there was no particulate matter deposition on the dentin surface or in the dentinal tubules, and the dentinal tubules were open. (2) X-ray energy dispersive spectrocopy results: The Ca/P ratio of group A was 1.61, which was closest to the theoretical value of healthy dentin; the Ca/P ratio was higher in group A than that in the groups B, E, and F (P < 0.05). There was no significant difference in Ca/P ratio between group A and group C (P > 0.05). (3) Laser confocal microscopy test results showed that the fluorescence intensity and fluorescence area of group A were the smallest, and the mean fluorescence intensity was smaller in group A than that in other five groups (P < 0.05). The mean fluorescence intensity of group C was lower than that of groups B, D, E and F (P < 0.05). (4) It is indicated that nano hydroxyapatite has a good remineralization effect on demineralized dentin. The combination of nano hydroxyapatite and bioactive glass can also deposit on the dentin surface, but there is no synergistic effect. The sealing effect is not as good as that of nano hydroxyapatite alone. [ABSTRACT FROM AUTHOR]

In order to explore the influence of coal gangue on the performance of concrete, C30 concrete was prepared with different contents of coal gangue powder (CGP) and different substitution rates of coal gangue coarse aggregate (CGA). The flexural properties and chloride ion penetration resistance of coal gangue concrete were studied. The influence law and improvement mechanism were further analyzed by mercury intrusion method and scanning electron microscope. The results showed that with the increase of dosage, the flexural strength of coal gangue concrete increased first and then decreased, and 15 % CGP was the optimal dosage of flexural strength. The resistance to chloride ion penetration increased with the increase of CGP content. When the substitution rate of coal gangue coarse aggregate was 100 %, the incorporation of CGP had a more significant optimization of its flexural strength. The addition of CGP increased the harmless pores such as gel pores and transition pores, and decreased the harmful pores such as capillary pores and macropores, thus optimizing the particle size distribution of concrete and improving the structural compactness. On the one hand, CGP produced a large amount of C-S-H gel in the secondary hydration, which made the microstructure of coal gangue concrete more dense. On the other hand, the unreacted CGP can be filled into the pores and cracks of coal gangue concrete to improve the strength of the interfacial transition zone, and then improve the flexural strength and chloride ion penetration resistance of coal gangue concrete. [ABSTRACT FROM AUTHOR]

In order to promote the resource utilization of steel slag, based on the stability evaluation of steel slag, using lime as alkali activator, the unconfined compressive strength test, X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to study the effects of different alkali-activated slag mix ratios and alkali-activated slag content on the compressive strength of slag-stabilized steel slag mixture. The hydration products and strength enhancement mechanism of slag-stabilized steel slag mixture was discussed. The research showed that the strength of the mixture increased first and then decreased with the increase of lime content, and the optimal mix ratio of lime and mineral powder was 1 ∶4. 2. Under this mix ratio, the 7 d strength of the mixture with 4. 5% alkali activated mineral powder content reached 6. 27 MPa, which met the technical requirements of high-grade pavement. With the increase of alkali-activated slag content, the compressive strength of the mixture increased, the elastic section of the load-deformation curve increased gradually, the plastic section and the descending section decreased, and the plastic deformation capacity decreased. Lime can better stimulate the potential activity of the slag-steel slag system. The hydration products included hydrated calcium silicate, hydrated calcium aluminate and Jennite. The internal honeycomb and fibrous cementitious structure made the internal structure of the mixture denser and improved the macroscopic strength and volume stability of the mixture. [ABSTRACT FROM AUTHOR]

In view ol the problems ol incomplete penetration and poor perlormance in the traditional method ol welding thick plate Inconel625 alloy, plasma welding technology was used to weld 8 mm thick Inconel625 alloy, and ERNiCrMo-3 welding wire was used as the lilling material to ensure molding. The microstructure and properties ol the welded joints were analyzed via Optical Microscope (OM), Scanning Electron Microscope (SEM), universal testing machine and microhardness testing machine. The results show that the welded joint has the optimal lorming and mechanical properties under the welding current ol 230 A, welding speed ol 240 mm/min, wire feeding speed ol 1 400 mm/min and plasma gas flow ol 4 L/min. The welded joints show a c Y;-shaped morphology with a wide top and a narrow bottom. The base metal area is austenite equiaxed crystal, the weld zone is mainly composed ol line cellular crystals, and the fusion line area is coarse cellular crystals grown perpendicular to the fusion line, MC carbide and Laves phase will precipitate during the welding process. The tensile strength of the joint is the highest, which can reach 811. 36 MPa, and the Iracture ol the welded joint is ductile Iracture, The hardness ol the weld zone is the highest under all parameters. As the welding heat input increases, the overall hardness of the welded joint increases. When the current reaches 240 A and 250 A, the hardness dillerence of the welded joint is small・ [ABSTRACT FROM AUTHOR]

BACKGROUND: Process integration of decellularization, antigen removal, viral inactivation and sterilization is essential for producing regenerative biomaterials that meet clinical requirements. OBJECTIVE: To systematically compare the effects of two combined processes of decellularization, antigen removal, virus inactivation and sterilization on the physicochemical properties of porcine dermal matrix. METHODS: Fresh porcine dermis was obtained and processed by two processes into acellular matrices. (1) Method A: 1% Triton X-100, DNase and RNase, and 1% tributyl phosphate were applied for decellularization, 1% peracetic acid and 25% ethanol for viral inactivation, and gamma-irradiation for terminal sterilization. (2) Method B: Dispase II, 0.5% Triton X-100 and DNase were used for decellularization, α-galactosidase for the antigen removal, 0.1% peracetic acid for viral inactivation and gamma-irradiation terminal sterilization. Porcine dermal matrices prepared by two methods were characterized. RESULTS AND CONCLUSION: (1) The collagen content of group A was lower than that of group B. The contents of elastin and sugar of group A were higher than those of group B. The material hardness value of group A was higher than that of group B. The drapability of the matrix material in group A was poor and the flexibility of the matrix material in group B was better. (2) The decellularization of group A did not affect the thermal stability of the matrix material. In group B, decellularization slightly reduced the thermal stability of the matrix material. After gamma ray sterilization, the thermal stability of the matrix material in group A decreased greatly and the thermal stability of the matrix material in group B decreased very little. (3) Compared with group B, the tensile strength and elasticity of the matrix material in group A were smaller. In vitro enzymatic degradation experiments showed that the matrix materials in group A had strong resistance to collagenase degradation, were sensitive to trypsin and were easily degraded; the matrix materials in group B were the opposite. (4) Scanning electron microscope showed that after sterilization by gamma rays, the three-dimensional structure of collagen could not be seen in the matrix material of group A; the collagen fibers were densely arranged, and there was a non-fibrous structural gel-like substance between the collagen fibers. In group B, the structure of collagen fibers in the matrix material was clear, and there was no non-fibrous structural glue-like substance between the collagen fibers. Hematoxylin-eosin staining and trichrome staining showed that after sterilization by gamma rays, a few nuclei were visible in the matrix material of group A; the collagen fibers were closely arranged, and the material was dense. The matrix material in group B had no nucleus and retained a good three-dimensional spatial structure of collagen fibers. (5) The results suggest that different processes have great influences on the physical and chemical properties of derived acellular matrices. Method B is effective in decellularizing and de-antigening and retains intact natural tissue matrix. Method A is more destructive to the material and results in lower collagen content, scratchability, thermal stability and poorer biomechanical properties compared with the Method B. [ABSTRACT FROM AUTHOR]

BACKGROUND: Biological coral artificial bone is a good alternative material for repairing long bone defects. However, the degradation and absorption rate of biological coral artificial bone in the human body does not match the growth rate of new bone, which leads to the limitation of its clinical application. OBJECTIVE: To explore the effect of osteoclast TRPV5 on the degradation of biological coral artificial bone. METHODS: Monocyte macrophage strain RAW264.7 from mouse was inoculated on biological coral artificial bone slices, which were co-cultured with osteoclasts. After the appearance of osteoclasts was observed, the osteoclast-induced differentiation medium containing 0, 50, 500, 5 000 µmol/L ruthenium red (TRPV5 channel inhibitor) was added separately. After culturing for a certain period of time, the expression of TRPV5 channel protein was observed under a laser confocal microscope. The absorption lacuna on the biological coral artificial bone slice was observed under a scanning electron microscope. The expression of TRPV5 channel protein in cells was detected by western blot assay. RESULTS AND CONCLUSION: (1) Laser scanning confocal microscope: TRPV5 could be expressed on the cytoplasm and membrane of osteoclasts. With the increase of ruthenium red concentration, the expression of TRPV5 on osteoclasts decreased. (2) Scanning electron microscope: Large continuous bone resorption lacuna was seen on the bone slices in the 0 nmol/L ruthenium red group. The bone resorption lacuna on the bone slices in other concentrations of ruthenium red decreased and was scattered, and with the increase of the concentration of ruthenium red, the area of the bone lacuna gradually decreased. (3) Western blot assay: Compared with 0 nmol/L ruthenium red group, the expression of TRPV5 channel protein in other concentrations of ruthenium red groups was significantly decreased (P < 0.05 or P < 0.01). (4) The results confirm that osteoclasts grow well on biological coral artificial bone, and TRPV5 can be used as a target to regulate the degradation rate of biological coral artificial bone. [ABSTRACT FROM AUTHOR]

BACKGROUND: Recently, decellularized dermal matrix hydrogel has broad application prospects in tissue filling and repair because of its injectable and filling irregular space. Cytocompatibility and biocompatibility are the key to tissue repair. It is significant to explore the compatibility of decellularized dermal matrix hydrogel. OBJECTIVE: To construct a decellularized dermal matrix hydrogel scaffold for tissue filling and repair. METHODS: An injectable decellularized dermal matrix hydrogel was prepared, and its microscopic morphology was observed under a scanning electron microscope. The decellularized dermal matrix hydrogels with a concentration of 8 and 10 g/L were co-cultured with bone marrow mesenchymal stem cells, separately, and the cell proliferation and cytocompatibility were tested. The decellularized dermal matrix hydrogels with a protein concentration of 0.25 and 0.5 g/L were injected into different subcutaneous parts of the back of the same SD rat separately, and the degradation of the hydrogels was observed 2 and 4 weeks after the operation. Decellularized dermal matrix hydrogels with protein concentrations of 1, 1.5, and 2 g/L were injected into different subcutaneous parts of the back of the same SD rat separately. At 8 and 16 weeks after the operation, the degradation of the hydrogel was observed and histological analysis was performed. RESULTS AND CONCLUSION: (1) Scanning electron microscopy analysis showed that the decellularized dermal matrix hydrogel exhibited an irregular and randomly oriented porous fibrous structure with different pore sizes. (2) After 1, 3, and 5 days of co-culture, the hydrogels with the two concentrations had no effect on the proliferation of bone marrow mesenchymal stem cells. Live/Dead staining after 1, 2, and 3 days of co-culture showed that the hydrogels with the two concentrations had no effect on the proliferation of bone marrow mesenchymal stem cells, but the cell morphology on the hydrogel changed to some extent. (3) The hydrogel with a protein concentration of 0.25 g/L was degraded after subcutaneous injection for 2 weeks; the hydrogel with a protein concentration of 0.5 g/L was degraded after subcutaneous injection for 4 weeks; the hydrogels with a protein concentration of 1, 1.5, and 2 g/L did not degrade after subcutaneous injection for 16 weeks, and possibly even longer. Hematoxylin-eosin staining showed that after subcutaneous injection for 8 weeks, the hydrogel tissue of the three protein mass concentrations was relatively dense, with a small amount of inflammatory infiltration, and the 2 g/L group had microangiogenesis. After 16 weeks, the hydrogel tissue became loose, and the 1 g/L group was more obvious, and the inflammatory infiltration was alleviated. Immunohistochemical staining showed that the number of microvessels in the hydrogel increased with the increase of injection time. The number of microvessels in the hydrogel increased with the increase of protein concentration. (4) The results confirmed that the injectable decellularized dermal matrix hydrogel had good cytocompatibility and biocompatibility. [ABSTRACT FROM AUTHOR]

In order to improve the utilization rate of iron tailings and reduce the cost of grouting materials, the method of replacing river sand and fly ash with iron tailings sand and partially replacing cement with activated iron tailings powder was selected for the test. Using orthogonal test method, factors such as water cement ratio, cement sand ratio, tailings powder, and fly ash content were studied. Research showed that the influence of four factors on the strength of grouting materials was ranked in descending order: water cement ratio, tailings powder, fly ash, and cement sand ratio. Through range analysis, the optimal factor level combination for 28 days was determined to be a water cement ratio of 0. 36, a cement sand ratio of 1 ∶ 0. 6, a tailings powder content of 10%, and a fly ash content of 6%. Through contrast tests, the feasibility of completely replacing river sand and fly ash with iron tailings sand and partially replacing cement with activated iron tailings powder was clarified. Through X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis, it was found that under the test conditions, the performance of grouting materials was improved by the production of tricalcium silicate, ettringite and other hydration products during the hydration and hardening process of grouting materials. Incomplete crack and hydration reaction would reduce the strength of grouting material. [ABSTRACT FROM AUTHOR]

Objective: To prepare the strontium and nitrogen co-doped titanium dioxide (Sr-N-TiO2)/ nano hydroxyapatite (n-HA) composite resins, to evaluate its basic properties, antibacterial properties, remineralization abilities, and biosafeties, and to clarify the antibacterial mechanism of the new type of composite resins. Methods: Sr-N-TiO2 and n-HA were mixed as the reinforcing fillers. The composite resins were prepared and were divided into control group and three experimental groups. According to the mass fractions of reinforcing fillers, the experimental groups were divided into 2. 5% reinforcing filler group, 5. 0% reinforcing filler group, and 7. 5% reinforcing filler group. The infrared spectrogram of composite resins in various groups were detected by the Fourier-transform infrared absorption spectrogram and the double bond conversion rates were calculated before and after light curing for 60 s. The curing depths of composite resin specimens in various groups after light curing for 20 s were calculated by cylindrical mould (height=10. 0 mm, diameter=4. 0 mm). Three composite resin specimens in various groups were prepared and co-cultured with the dilute Streptococcus mutans solution. The plate colony counting method was used to determine the counts of attached bacteria on surface of the specimens and the antibacterial rates were calculated; live/dead bacteria staining method was used to observe the ratio of live bacteria/dead bacteria and morphology of composite resin speciments in various groups. The composite resin specimens were immersed in the artificial saliva for 1, 3, 5, and 7 d, and the mineralizations of surface of the composite resins were observed under scanning electron microscope (SEM). The mouse fibroblast cells (L-929 cells) were incubated with the resin extract solution, and CCK-8 method was used to detect the relative growth rates (RGR) of the cells on the 1st, 2nd, and 3rd days and the cytotoxicity levels were evaluated. Results: With the increasing of reinforcing filler proportion of the composite resins, the double bond conversion rates and curing depths of new type of the composite resins showed a decreasing trend, but all reached the clinical standard. Compared with control group, the double bond conversion rates of new type of the composite resins in 2. 5% reinforcing filler group and 5. 0% reinforcing filler group had no significant differences (P>0. 05), and the above index in 7. 5% reinforcing filler group was decreased (P< 0. 05). Compared with control group, the curing depths of the composite resins in experimental groups were increased (P<0. 05 or P<0. 01), the counts of attached bacteria on surface of the speciments in experimental groups were significant increased (P<0. 01). When the proportion of reinforcing fillers reached 5. 0%, the antibacterical rates of new type of the composite resins were higher than 90%. Compared with control group, the counts of live bacteria on surface of the composite resins in experimental groups were decreased with the increasing of proportion of the reinforcing fillers. The SEM results show that the mineralized nodules on surface of the composite resins in experimental groups could be observed, and the number of mineralized nodules was increased with the prolongation of time and the increasing of reinforcing fillers proportion. After treated for 7 d, the surface of the composite resins in 5. 0% reinforcing filler group and 7. 5% reinforcing filler group were almostly covered by mineralized nodules. The biosafety experiment results showed that the RGR of cells in various groups was above 75%, and the cytotoxicity level ≤1 grade. Conclusion: The modified new type of composite resins meet the clinical standards, and it has antibacterial and remineralization properties, as well as high biosafety. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of Nd, Gd composite modification and heat treatment process on the microstructure of Mg-8Al alloy, we analyzed the evolution behavior of Mg17Al12 closely related to mechanical properties of Mg alloys and rare earth phase. The microstructure of the specimens was characterized by metallographic microscope(OM), X-ray diffraction(XRD), scanning electron microscope(SEM)and transmission electron microscope(TEM), and the morphology and distribution of β-Mg17Al12 and Al2RE in Mg-8Al-1Nd-1Gd alloy during solution treatment at 420 ℃ and aging precipitation at 210 ℃ were observed. The experimental results show that the eutectic of Mg alloy after modification with Nd and Gd, β-Mg17Al12 transforms from a continuous network to a fine discontinuous island and Al2RE phase with good thermal stability is produced at the grain boundary. The phase decomposition process of eutectic β-Mg17Al12 in solution treatment is continuous network-discontinuous island-spherical particles. Finally, a supersaturated α-Mg solid solution is formed, while Al2RE phase do not change before and after heat treatment. Lamellar and acicular aging precipitation β-Mg17Al12 is distributed at the grain boundary and in the grain, respectively and the precipitated β-Mg17Al12 presents fine and dispersed distribution characteristics under the modification of Nd and Gd. [ABSTRACT FROM AUTHOR]

Polyaniline-silver chloride nanocomposites were prepared by in-situ chemical oxidation polymerization with polyaniline with good conductivity as substrate and photosensitive semiconductor material silver chloride as initiator, and their electrical and optical properties were systematically studied. The morphology, structure, optical properties, and conductivity of polyaniline monomer and polyaniline or silver chloride nanocomposites were characterized and compared by scanning the electron microscope, quaternary probe conductivity tester, and simulating sunlight illumination. The results show that polyaniline silver chloride nanocomposites have good thermal stability; nano-silver chloride particles are uniformly dispersed in polyaniline; the doping of silver chloride will have a positive effect on the conductivity of the composites. At the same time, silver chloride with surface metal plasma oscillation effect is doped in the composite material, which makes the composite material have excellent light absorption and catalytic performance. [ABSTRACT FROM AUTHOR]

The high-efficient utilization of mineral resources is the leading research aspect of global mining development. Traditional optical and scanning electron microscopy have limitations in identifying the occurrence of elements in many low-grade ores and usually cannot provide quantitative mineralogy information, hindering the improvement of mineral processing of these ores. In recent years, automated mineral quantitative analysis systems based on scanning electron microscope and X-ray energy spectrometer have been increasingly applied to study complex ore formation and process mineralogy. OBJECTIVES: To enrich and expand the application of an automated quantitative mineral analysis system in process mineralogy. METHODS: The low-grade copper slag from a copper mine in China is analyzed using the TESCAN Integrated Mineral Analyzier (TIMA). RESULTS: The results show that the content of the copper element (0.08%) in the copper slag is very low, and it is mainly distributed in chalcopyrite, which accounts for 0.21%. Gangue minerals include quartz (47.6%), muscovite (10.10%), and calcite (9.88%). Chalcopyrite usually occurs in irregular granular form and shows complex associations with the above gangue minerals. The particle size is small and variable, and the particles of 10-76μm occupy a large proportion. The mass of chalcopyrite with a liberation degree below 30% accounts for 85% of the total mass, and the overall liberation degree is low, so further grinding is needed to improve chalcopyrite recovery. CONCLUSIONS: Research shows that for the ore samples with low content of useful minerals, small particle size, and complex mineralogical associations, the automated mineral analysis system, including TIMA, can provide rapid, quantitative, comprehensive, and accurate process mineralogy parameter information, which is conducive to optimizing the ore extraction and smelting process, and has an extensive application prospect in improving the comprehensive utilization of mineral resources. [ABSTRACT FROM AUTHOR]

BACKGROUND: Bone tissue engineering scaffolds with modified growth factors have promising applications in bone repair materials, but the rapid release of growth factors leads to composite scaffolds that can promote bone repair only at an early stage, and the coating process provides a new idea to solve this problem. OBJECTIVE: To prepare Mg-F membrane/icaritin/β-tricalcium phosphate scaffold to characterize the biological properties of the new scaffold. METHODS: The β-tricalcium phosphate scaffold was prepared by applying 3D printing technology, and the icaritin/β-tricalcium phosphate scaffold was prepared by low energy electron beam deposition technology. Mg-F membrane/icaritin/β-tricalcium phosphate scaffolds were fabricated by pulsed laser deposition technology. The microstructure, pore diameter, porosity, wire diameter, compressive strength, and elemental composition of the scaffolds were examined, and the icaritin binding force and slow-release properties were analyzed. Rabbit bone marrow mesenchymal stem cells were co-cultured with β-tricalcium phosphate scaffold, icariin/β-tricalcium phosphate scaffold and Mg-F membrane/icariin membrane/β-tricalcium phosphate scaffold extract. Cell proliferation was measured by CCK8 assay. Rabbit bone marrow mesenchymal stem cells were co-cultured with the above three scaffolds, separately, and osteogenic induction medium was added, and the osteogenic differentiation ability was observed by alizarin red staining. RESULTS AND CONCLUSION: (1) Scanning electron microscope showed that the structure of β-tricalcium phosphate scaffold was relatively regular and the pore connectivity rate was good; the surface of the icariin membrane/β-tricalcium phosphate scaffold had relatively dense icariin membrane covering the original microscopic pores; Mg-F membrane was deposited on the surface of the icariin membrane, leaving a relatively rough and loose surface with microscopic pores. The differences in pore diameter, porosity, wire diameter, and compressive strength of three kinds of scaffolds were not statistically significant (P > 0.05). (2) The icariin binding force of Mg-F membrane /icariin membrane /β-tricalcium phosphate scaffold was better than that of icariin membrane /β-tricalcium phosphate scaffold (P < 0.05), and slow release of icariin lasted longer. (3) The results of CCK8 assay showed that the three kinds of scaffold extracts did not affect the growth of bone marrow mesenchymal stem cells. Alizarin red staining showed that at 21 days of osteogenic induction, the number of calcium nodules and the maturity of calcium nodules in the Mg-F membrane/icariin membrane/β-tricalcium phosphate scaffold group and the icariin membrane/ β-tricalcium phosphate scaffold group were better than those in the β-tricalcium phosphate scaffold group. (4) The results show that the Mg-F membrane/ icariin membrane / β-tricalcium phosphate scaffold has good cytocompatibility, osteogenic ability, drug binding and sustained release properties. [ABSTRACT FROM AUTHOR]

BACKGROUND: Synthetic calcium phosphate ceramic materials are similar to the inorganic components of natural bone tissue. Functional design through surface morphology and chemical composition can endow them with excellent osteoconductive and osteoinductive properties. The development of calcium phosphate ceramic materials with osteoinductive properties is the current research hotspot. OBJECTIVE: To endow the submicron topology tricalcium phosphate ceramics with osteoinductive properties through material morphology regulation and functional design, and test their physicochemical properties and osteoinductive properties. METHODS: Novel tricalcium phosphate ceramics were prepared by high temperature sintering method. Clinical available Bio-oss bone meal was set as the control group. The sample surface morphology, the protein adsorption capacity, and the in vitro mineralizability of the two materials were characterized. Human periodontal membrane stem cells at passage 3 were co-cultured with the extracts of the two materials. Cell proliferation was detected by CCK-8 assay. Alizarin red staining was used to detect cell mineralization performance. The human periodontal ligament stem cells at passage 3 were seeded on the surfaces of the two materials. Early osteogenesis was detected by alkaline phosphatase staining. The expression of osteogenesis-related factors was detected by qRT-PCR. RESULTS AND CONCLUSION: (1) Scanning electron microscope exhibited that both materials had microporous surfaces with granular texture. Bio-Oss particles were significantly smaller than that of tricalcium phosphate ceramics. The total porosity, macroporosity, and microporosity were similar for both materials. Tricalcium phosphate ceramics were mainly submicron pores, with a grain size of 100 nm-1.0 μm. Bio-Oss bone meal was mainly nano-scale pores. In vitro mineralization experiments displayed that the ability of the surface of tricalcium phosphate ceramics to induce bone apatite deposition was stronger than that of Bio-Oss bone meal. Compared with Bio-Oss bone meal, tricalcium phosphate ceramics could adsorb more proteins from fetal bovine serum and bovine serum albumin solution (P < 0.05). (2) CCK-8 assay demonstrated that both materials promoted cell proliferation, and there was no significant difference between the two groups (P > 0.05). (3) The alkaline phosphatase activity in the tricalcium phosphate ceramic group was higher than that in the Bio-Oss group at 4 and 7 days of culture (P < 0.05), and the number of mineralized nodules at 21 days of culture was more than that in the Bio-Oss group; the mRNA expression levels of alkaline phosphatase, osteocalcin, osteopontin and Runx-2 were higher than those in the Bio-Oss group on 7 and 14 days of culture (P < 0.05). (4) The results showed that the new calcium phosphate ceramics have superior in vitro osteoinductive properties. [ABSTRACT FROM AUTHOR]

To overcome poor strength and low utilization efficiency of solidified silt, a curing agent, G, is formed with the addition of cement, fly ash, lime, triethanolamine, calcium sulfate and sodium silicate to improve the solidification effect of solidified silt in Sanjiang. The mechanism of strength growth of solidified silt with different water contents and different dosage was studied by unconfined compressive strength, mercury injection test, and scanning electron microscope. The test results show that, with the addition of the curing agent, the optimal moisture content of the solidified silt increases and the maximum dry density decreases slightly, with its strength increasing linearly with the amount of curing agent added and the moisture content. In addition, the porosity of the solidified silt is positively proportional to the moisture content and the large pore size porosity is inversely proportional to the amount of curing agent added. Microscopic analysis shows that, the compaction of solidified silt decreases with the increase of the water content and its strength mainly comes from the crumb structure formed by silt and hydration products, which plays the role of filling, cementing and skeleton support in loose soil particles. [ABSTRACT FROM AUTHOR]

To understand the effect of acid solution treatment on poly 1, 4-cyclohexylen dimethylene terephthalate(PCT) fiber, the surface morphology, mechanical properties, aging reaction activation energy and infrared spectrum of PCT fibers before and after sulfuric acid and nitric acid treatment were tested and analyzed by scanning electron microscope(SEM), single fiber strength machine, synchronous thermal analyzer(STA) and Fourier transform infrared spectrometer(FTIR). The results show that the acid immersion treatment can cause the shrinkage of PCT fiber, leading to the surface corrosion of the fibers and the occurrence of dents and cracks; The entering of water molecules into the fiber macromolecule gap of PCT fiber causes a simultaneous decrease in breaking strength and elongation at break; The breaking strength of PCT fiber decreased with the increase of acid solution concentration, treatment time and treatment temperature; Unless at a lower concentration and temperature, the sulfuric acid resistance of PCT fiber is better than that of nitric acid; The sulfuric acid resistance of PCT fiber is weaker than that of the polyphenylene sulfide(PPS) and the polytetrafluoroethylene(PTFE) fiber, and better than that of the polyimide(PI) and the Aramid 1313 fiber; Acid solution treatment can lead to a decrease in the activation energy of the aging reaction and molecular stability of PCT fiber. [ABSTRACT FROM AUTHOR]

Aiming at the disadvantage that nano ZnO is easy to agglutinate in the process of preparation and use, which will affect its antibacterial performance, experiments are designed to make nano ZnO compound with porous SiO2 in the sol-gel process. Through scanning electron microscope (SEM) and transmission electron microscopy (TEM), it can be found that ZnO is well combined on the porous SiO2 skeleton and dispersed evenly. The BET and PL tests show that the specific surface area of composites is improved and the optical properties are enhanced. The difference of antibacterial properties between composites and singlecomponent nano ZnO, and the change of antibacterial properties caused by the change of nano ZnO content in composites are investigated by the colony counting method. Conclusion is proved that the antibacterial properties of nano ZnO and porous SiO2 are greatly improved with the antibacterial rate of more than 99%. [ABSTRACT FROM AUTHOR]

With the aid of an electronic universal testing machine and a scanning electron microscope, uniaxial compression tests and microscopic examinations of cemented tailings backfill with mixed fibers were carried out in order to investigate the impact of mixing steel fiber (SF) and polypropylene fiber (PF) on the static mechanical properties and failure mode. The findings demonstrate that; the inclusion of hybrid fiber has a substantial impact on the failure mode of the backfill; the CTB is mostly damaged by single bevel shear, displaying an evident brittle failure;the SP-FRB is primarily damaged by relatively minor secondary cracks due to the bridging and crack-resisting action of internal fibers; and the specimen is fractured as a whole,demonstrating an obvious ductile deformation; The addition of hybrid fiber can increase the filler s uniaxial compressive strength,but there is a maximum amount that should be used. The stress-strain curves of both CTB and SP-FRB contain four stages: pore compaction, linear elastic deformation, plastic yield,and post-failure. The results of the microscopic tests indicate that the initial pore size and number inside the filler are significant factors in its failure. Steel fiber and polypropylene fiber can both maintain high integrity inside the filler and prevent crack expansion through adhesion with the matrix and their own fatigue fracture, respectively. [ABSTRACT FROM AUTHOR]

Textured fibril soy protein (TFSP) is one of the most important high-density plant proteins with a fiber structure similar to meat using screw extrusion. It is often used to process simulated meat products after rehydration treatment. In this study, the rehydration dynamics model was constructed to predict the rehydration process using different ultrasonic power and NaHCO3 concentration at 40℃. A systematic investigation was implemented to explore the effects of different rehydration modes on the physical and chemical properties, as well as the microstructure of TFSP. The rehydration quality of TFSP was evaluated to compare with the control group, Results showed that the final moisture content increased by 27.14 %, when TFSP rehydrates to 120 min, whereas, the rehydration time was shortened by 20 min in the 500 W ultrasound group, compared with the pure water group. The final moisture content also increased by 23.41 % in the 2.000 % NaHCO3 group, without any significant change in the rehydration time. A Weibull model was better fitted for the TFSP rehydration in the control (R ²≥ 0.993 3), ultrasound (R 2≥0.990 5), and NaHCO3 group (R 2≥0.986 7). Both ultrasound and NaHCO3 treatments slightly reduced the color of the re-hydrated TFSP, whereas, there was a great increase in the water holding capacity and immobilized water content. There was some variation in the hardness, chewiness, and degree of texturization of re-hydrated TFSP, without the outstanding difference in the springiness. The 400 W ultrasound group was the highest degree of texturization, 41.80 % higher than the control. Meanwhile, the 0.250 % NaHCO3 group reached the smallest hardness, which was 54.17% smaller than the control. Scanning electron microscope (SEM) observation showed that the microstructure of rehydrated TFSP was changed by the ultrasound and NaHCO3 . Specifically, the pore size was enhanced to accelerate the water transport rate and the water holding capacity. Therefore, the ultrasound should be chosen to assist the TFSP rehydration, if the maximum degree of texturization was taken as the main evaluation index. By contrast, the NaHCO3 -assisted rehydration effect should be selected, if the minimum hardness was taken as the main evaluation index. This finding can provide a theoretical basis and reference to develop TFSP products with excellent qualities under different rehydration modes. [ABSTRACT FROM AUTHOR]

Biomass energy has the advantages of recyclability and environmental friendliness. Poplar grows rapidly and has a relatively high cellulose content, making it an excellent raw material for the production of biomass energy. However, the cellulose, hemicellulose and lignin of poplar are intertwined to form a dense structure, making it difficult to be hydrolyzed in normal cases. In this work, poplar was pretreated by CrCl3 as catalyst, the effect of different temperatures was compared, and the optimal pretreatment temperature was determined. Results showed that under the conditions of 0.05 mol/L CrCl3, solidliquid ratio of 1/10, pretreatment time of 20min, stirring speed of 300 r/min and pretreatment temperature of 160°C, the components of poplar were effectively separated after pretreatment with CrCl3, while 10.4% lignin and 90.0% hemicellulose removal， and cellulose content increased by 35.6%， hemicellulose and lignin content decreased by 85.5% and 29.9%, respectively. The yield of glucose increased by 568.1% after 72h. In addition, the structure and physical properties of the raw and pretreated poplar were characterized by scanning electron microscope (SEM)、diffraction of X-rays (XRD) and Fourier transform infrared spectrometer (FT-IR). Experimental results indicated that the structure of poplar became loose after CrCl3 pretreatment, improving the contact surface of cellulose. The crystallinity (CrI) of poplar raw material was 63.84%, then increased to 71.07% after CrCl3 pretreatment, which was due to the removal of amorphous hemicellulose during pretreatment. In the FT-IR test, the characteristic absorption peak of acetyl groups in hemicellulose was significantly weakened after CrCl3 pretreatment compared with the raw material, a strong benzene ring characteristic absorption peak was retained at 1510 cm−1, and the characteristic peak of β-glycosidic bonds still appeared around 898 cm−1. It is further demonstrated that CrCl3 pretreatment removed most of hemicellulose and retained the majority of cellulose, which promoted the subsequent enzymatic hydrolysis process，but had less effect on lignin. The enzymatic hydrolysis of pretreated poplar was conducted under the conditions of pH value is 4.8, enzymatic hydrolysis temperature of 50 °C, shaker speed of 150 r/min, enzyme addition of 20 FPU/g substrate, surfactant dosage of 150mg/g substrate, exploring the promotion effect of surfactant type, dosage and enzyme addition on enzymatic hydrolysis. It was found that the glucose yield of 69.7% was obtained after 24 h with calcium lignosulfonate, which was higher than that after 72 h without additive. Further extending the hydrolysis time to 72 h, the glucose yield reached 85.5%. When the cellulase loading was 5 FPU/g substrate, the glucose yield with calcium lignosulfonate (68.0%) was constant with that when the enzyme dosage was 20 FPU/g substrate without additive. that the addition of calcium lignosulfonate could reduce the hydrolysis time, decrease the dosage of cellulase, and enhance the efficiency of enzymatic hydrolysis. Consequently, the CrCl3 pretreatment effectively removed the lignin and hemicellulose, while remained cellulose to promote hydrolysis efficiency. Furthermore, the addition of calcium lignosulfonate as a surfactant in the enzymatic hydrolysis also improve hydrolysis efficiency. This study provides some theoretical support for the improvement of pretreatment and the reduction of enzymatic hydrolysis cost. [ABSTRACT FROM AUTHOR]

In order to study the effect of different oxidation modification methods of activated carbon on the preparation of silver loaded bactericidal activated carbon, coconut shell activated carbon (AC) was modified with HNO3 and H2O2, and then immersed in AgNO3 solution. Silver loaded activated carbon (Ag / AC) was prepared by using polypropylene pyrrolidone (PVP) as protective agent and NaBH4 as reducing agent. The surface morphology of AC were observed by scanning electron microscope (SEM), the pore structure of AC was determined by nitrogen adsorption at low temperature, the crystal structure of AC was analyzed by X-ray diffraction. The antibacterial properties and silver loss of Ag / AC under different preparation conditions were studied. The results showed that silver ions were reduced to silver nanoparticles with particle size of 10-40 nm and uniformly distributed on the AC surface. With the increase of Ag loading, the specific surface area of Ag / AC decreased, and the bactericidal and anti silver loss properties were improved. Comparing the results of two kinds of oxidation modification, it can be seen that the Ag / AC-H2O2 modified by H2O2 had the highest silver loading (0. 64%), the best bacteriostatic performance (the bacteriostatic broadband was 4.01 mm), and the silver loss after 15 days of shaking at 25 ℃ was 0.035%. Ag / AC-H2O2 achieved silver controlled release on the premise of maintaining high antibacterial performance. [ABSTRACT FROM AUTHOR]

Using zinc nitrate hexahydrate and 2-methylimidazole as raw materials and absolute ethanol as solvent, the precursor ZIF-8 was prepared by the mechanical stirring method, and zinc oxide nanorods at different temperatures were prepared by thermal deposition of the precursor, respectively.ZnO-X（X=700,800,900）.The X-ray diffractometer（XRD） patterns showed that the ZnO nanotubes at different temperatures had complete crystallization and high purity.It can be seen from the scanning electron microscope（SEM） that the size distribution of the precursor is 0.5～2 μm; as the thermal deposition temperature increases, the diameter gradually increases from 150 nm to 2 μm, and the length increases from 1 μm to 30 μm.The photocatalytic degradation experiments showed that the degradation efficiencies of ZnO-700,ZnO-800,and ZnO-900 to rhodamine（RhB） were 63.1%,62.1%,and 62.8%,respectively, after 150 min of illumination.The obtained ZnO nanorods have an obvious photocatalytic degradation effect on RhB. [ABSTRACT FROM AUTHOR]

BACKGROUND: Polyetheretherketone materials have the advantages of stable physical, chemical and mechanical properties, radiation transparency and elastic modulus similar to human bones, but there is a biological inertia problem, which limits its clinical application. OBJECTIVE: To evaluate the biocompatibility of polyetheretherketone/hydroxyapatite composites prepared by fused deposition molding 3D printing. METHODS: Polyetheretherketone and polyetheretherketone/hydroxyapatite composite materials (hydroxyapatite mass fraction 10%) were prepared by fused deposition molding 3D printing technology, which were denoted as polyetheretherketone group (control group) and polyetheretherketone/hydroxyapatite group (experimental group). Passage 3 mouse preosteoblasts (MC3T3-E1) were co-cultured with the extracts of the two groups of materials, separately. Cells cultured alone were used as positive controls. The survival and proliferation of MC3T3-E1 were detected by Live/Dead fluorescence staining and CCK-8 assay. The adhesion growth and proliferation of MC3T3-E1 on the surface of the materials were observed by scanning electron microscopy. RESULTS AND CONCLUSION: (1) Live/Dead fluorescence staining exhibited that the MC3T3-E1 cells in two kinds of extracts grew well and presented good viability. The cell survival rate was higher than 90%. The two materials had no obvious cytotoxicity. The cells proliferated well with the extension of culture time. (2) The results of CCK-8 assay showed that the cytotoxicity of the two kinds of materials was qualified. The proliferation absorbance value of cells in the experimental group was higher than that of positive control group and control group at 3, 5 and 7 days of culture (P < 0.05). (3) Scanning electron microscope observation showed the good adhesion and cell spreading. Matrix secretion of MC3T3-E1 cells was numerous in the experimental group at 1 day of inoculation. The number of cells adhering to the surface of the two groups of materials increased, and more matrixes were secreted at the same time, among which the number of cells adhering to the surface of the experimental group and the secretion of matrix were more at 3 days of inoculation. The overlapping growth of cells appeared on the surface of the two groups of materials, and the cells in the experimental group were more efficient in spreading growth and secreting matrix at 7 days of inoculation. (4) These findings verify that the polyetheretherketone/hydroxyapatite composite prepared by 3D printing has good biocompatibility. [ABSTRACT FROM AUTHOR]

BACKGROUND: At present, China has not made clear guidance on the in vitro dissolution of subcutaneous preparations. Because the release cycle of slowrelease and controlled-release preparations with poly(lactic-co-glycolic acid) copolymer as carrier is generally long, it is very important to develop an in vitro release method that can better simulate in vivo absorption. OBJECTIVE: To prepare leuprorelin acetate subcutaneous implant, develop an in vitro release method with good correlation with in vivo, establish an in vitro accelerated release model, investigate the correlation between drug release kinetics and thermodynamics, and elaborate the release mechanism. METHODS: Poly(lactic-co-glycolic acid) was used as a carrier. Leuprolide acetate implants were synthesized by hot-melt extrusion technology, and its physicochemical properties were characterized during the molding process. According to the developed in vitro drug release method, the in vitro drug release test was carried out. Taking the release degree as the index, the formulation with a release cycle of 1 month was screened. Adult male SD rats were used as animal models and subcutaneously implanted with leuprolide acetate implants with a release cycle of 1 month. Blood was obtained from the orbit at the set time point. The concentration of leuprorelin in plasma was determined by liquid chromatography-tandem mass spectrometry to analyze the correlation between in vivo and in vitro drug release. The leuprolide acetate implant was taken with a release cycle of 1 month. The in vitro accelerated test was carried out with temperature as a single variable to fit the release kinetic equation. Simultaneously, the microscopic morphology of the implants was observed under scanning electron microscope. RESULTS AND CONCLUSION: (1) The experiment set up five kinds of implants. The in vitro drug release experiment demonstrated that the release cycle of the 5th formula implant (the feeding ratio of leuprolide acetate was 25%; the feeding ratio of the carrier was 75%; and the mass ratio of poly(lactic-co-glycolic acid) copolymer with molecular mass of 10 kD and 30 kD in the carrier was 1:1) was 30 days, which met the requirements and was used for subsequent experiments. (2) The established in vitro release method had good correlation with drug release in vivo (y=0.945x-5.586 18, R2=0.945 4). (3) The cumulative release curve in vitro accorded with the S-type three-phase model: sudden release period, hysteresis period, and zero order rapid release period. In the process of heating up, based on the zero order drug release rate of 312.15 K, the thermodynamic and drug release kinetic rates accorded with the equation r=7.768 25E-30×e(4.787 45)+ 0.883 03. (4) The results show that the developed in vitro release method can better describe the dynamic information of drug release in vivo. The in vitro release curve is S-shaped. The release mechanism is the combination of diffusion and dissolution, and the drug release kinetics and thermodynamics in the zero order rapid release period are exponential. [ABSTRACT FROM AUTHOR]

BACKGROUND: Bone repair materials with biological functions have always been a research focus in biomedical engineering. OBJECTIVE: To develop bionic bone matrix material with bionic space structure and bionic function based on the requirements of molecular structure biomimetic and biological function biomimetic. METHODS: Using amino-terminated polyethylene glycol and pyromellitic anhydride as reactants, four kinds of polyethylene glycol derivative hydrogels were obtained by adjusting the amount of butanediamine added (15, 30, 45, 60 μL). Bioactive substances based on polylactic acid and force growth factor (MGFCt24E- MPLA-EG-g-HAP) were added to the four hydrogels separately. The solvent method was used to prepare bioactive biomimetic bone matrix material (PAPI-BDA/MGF-Ct24E-MPLA-EG-g-HAP). The bioactive material loading rate, porosity, surface morphology, hydrophilic/hydrophobic properties, water absorption and microscopic morphology of the bioactive bionic bone matrix materials were characterized. RESULTS AND CONCLUSION: (1) In the production process of the bionic bone matrix material, in PBS with pH=5.8, with the increased amount of butanediamine added, the loading of bioactive substances in the bionic bone matrix material first increased and then decreased. The loading of bioactive substances was the highest when the amount was 30 μL; in PBS with pH=3.5-7.4, the loading of bioactive substances in the biomimetic bone matrix material (the addition amount of butanediamine was 30 μL) showed a decreasing trend. When the pH value increased to 9.8, the loading of bioactive substances in the bionic bone matrix material remained basically stable. (2) In PBS with the same pH value, the porosity of the bionic bone matrix material decreased with the increase of the addition amount of butanediamine. When the addition amount of butanediamine was the same, with the increase of the pH value of PBS, the porosity of the bionic bone matrix material first decreased and then increased. (3) In PBS with pH=5.8, with the increase of the addition of butanediamine, the static contact angle of the bionic bone matrix material decreased and the water absorption increased. (4) It can be seen under the scanning electron microscope, the bionic bone matrix material has a continuous open pore structure, the pores are interconnected, the pore size distribution is 230-690 nm, and the pore size is inversely related to the amount of butanediamine added. The bionic bone matrix material prepared by adding butanediamine in an amount of 30 μL is similar to the structure of natural bone matrix. [ABSTRACT FROM AUTHOR]

Objective: To analyze the influencing factors of of sc nickel-titanium instruments separation. Methods: The cases undergoing root canal therapy in the hospital were collected between January 2020 and April 2022. According to the research purpose and content, the general questionnaires were designed to collect clinical data. The root canal curvature was measured by Schneider method. The nickel-titanium instruments were scanned by scanning electron microscope. Results: In the 10,047 cases(22,306 root canals), there were 236 cases(247 nickel-titanium instruments) with instruments separation, and the separation rate was 2.35%. Among them, there were 205 cases with nickel-titanium instruments separation in molars, and the separation rate was 4.29%. there were 106 cases with nickel-titanium instrument separation in mandible, and the separation rate was 1.83%. There were 130 cases with nickel-titanium instrument separation in the maxilla, and the separation rate was 3.06%. The differences were statistically significant(x²=77.128, P＜0.001).The separation rate of nickel-titanium instruments in mild bending group, moderate bending group, severe bending group and extremely severe bending group were 0.32%, 1.04%, 3.46% and 5.82%, respectively. With the increase of root canal curvature, separation rate of nickel-titanium instruments was significantly increased(z=291.883, P＜0.001). Conclusion: The separation rate of sc nickel-titanium instruments is 2.35%. In root canal preparation of mandibular molar, the incidence of instrument separation is the highest. The curvature of root canals had certain effects on the occurrence of instruments separation. [ABSTRACT FROM AUTHOR]

Electrospun polycaprolactone (PCL) nanofibers are often used as biomedical materials for drug release systems and tissue engineering scaffolds due to their biodegradability, but the hydrophobicity and mechanical defects limit the wider applications. Here, polybutyrolactam (PBL), a biodegradable polyamide with excellent mechanical properties and high moisture regain, was blended with PCL in co-solvent to electrospin fiber membranes with improved mechanical properties and the hydrophilicity. Scanning electron microscope (SEM), water contact angle measuring instrument, atomic force microscope (AFM), energy dispersive spectroscopy (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD), thermogravimetric analyzer (TGA), differential scanning calorimetry (DSC), electronic universal tension machine were used to investigate the morphology, diameter and distribution of fibers, the hydrophilicity, crystallinity, thermal and mechanical properties of the fiber membranes. It was found that increasing the PBL content increased the fiber diameter, narrowed the diameter distribution, and significantly improved the hydrophilicity of the fiber membrane. PBL had been shown to be compatible with PCL, and the crystallinity of PCL/PBL electrospun fiber membranes with increasing PBL content was higher than that of monocomponent fiber membranes. Increasing the PBL content also slightly raised the melting point of the PCL component in the fiber membranes, while that of PBL remained unchanged. The crystallization temperatures of PBL and PCL, as well as the thermal stability of the fiber membranes decreased with increasing PBL content. The addition of PBL significantly improved the mechanical properties of electrospun fiber membranes. The greater PBL content was, the better the mechanical properties of the fiber membrane were. [ABSTRACT FROM AUTHOR]

Monodisperse SiO2 microspheres with particle size in the range of 208—368 nm were prepared by the Stöber method and used to construct structural color films via fast lifting method. The as-prepared structural color films were then embedded in polydimethylsiloxane (PDMS), on which polydopamine (PDA)-doped PDMS (PDMS-PDA) was coated to obtain stretchable color-changing PDMS/SiO2/PDMS-PDA photonic elastomer films. Both the structural color films and photonic elastomer films were explored with techniques including scanning electron microscope, nanoscale laser particle size analyzer, spectrophotometer, fiber optic spectrometer, tensile testing machine and digital camera to elucidate the microstructure and optical properties of the former and the strain response and mechanical properties of the latter. Results show that the structural color films belong to amorphous photonic crystals consisting of long-range disordered and short-range ordered arrangements of SiO2 microspheres, and their structural colors are angle-independent under diffuse light. But interestingly, the structural colors are angle-dependent under sunlight due to the surface of SiO2 microspheres arranged flatly As for the photonic crystal elastomer films surface-coated with a black PDMS-PDA layer, the saturation of the structural color of the films during stretching is greatly improved. When the tensile strain reaches 20%, the films start to show apparently structural color, which undergo a continuous blue-shift with increasing strain, and the color returns to the initial state when the strain is restored. Moreover, the film has good mechanical properties with an elongation at the break of 140%, and can be applied to the field of visualized flexible sensing, smart wearable devices and other fields. [ABSTRACT FROM AUTHOR]

BACKGROUND: Zirconium implants are used in the field of oral implants due to good biocompatibility. Because of its biological inertness, the surface of the implant needs to be modified to improve its bioactivity. Hydroxyapatite coating is a widely used modification technique for implant surfaces. OBJECTIVE: The phase-transition lysozyme was modified on the zirconia surface, based on which a hydroxyapatite coating was constructed to confer its bioactivity and improve the success rate of implants. METHODS: The phase-transition lysozyme solution was dropped onto the surface of the smooth zirconia specimen for 2 hours. The phase-transition lysozymemodified zirconia specimen was incubated in the simulated body fluid for 10 days to induce the hydroxyapatite coating. The contact angle, roughness and mechanical properties of unmodified zirconia specimens, phase-transition lysozyme-modified zirconia specimens and hydroxyapatite-coated zirconia specimens were tested. The three kinds of zirconia specimens were co-cultured with MC3T3-E1 cells, separately. The cell proliferation and alkaline phosphatase activity were detected. Unmodified zirconia specimens and hydroxyapatite-coated zirconia specimens were co-cultured with MC3T3-E1 cells, separately, and cell adhesion was observed under a scanning electron microscope. RESULTS AND CONCLUSION: (1) The contact angle of the hydroxyapatite coating group was smaller than that of the unmodified group (P < 0.05), and the roughness was greater than that of the unmodified group (P < 0.05). There was no significant difference in the Vickers hardness and fracture strength of the three groups of specimens (P > 0.05). (2) CCK-8 assay showed that the absorbance values of cell proliferation in the hydroxyapatite coating group on 3, 5, and 7 days of culture were higher than those in the phase-transition lysozyme group and the unmodified group (P < 0.05). The alkaline phosphatase activity of the hydroxyapatite coating group was higher than that of the phase-transition lysozyme group and the unmodified group at 7 and 14 days of culture (P < 0.05). (3) Scanning electron microscope showed that MC3T3-E1 cells adhered closely to the surfaces of the two kinds of zirconia materials after 12 hours of culture. After 3 days of culture, the number of cells on the surfaces of the two materials increased, and the number of cells in the hydroxyapatite coating group was high and cell junctions appeared. (4) The results show that for zirconia all-ceramic materials, the preparation of hydroxyapatite coating on the basis of phase-transition lysozyme modification can improve its hydrophilicity and cytocompatibility without affecting the mechanical properties of the material. [ABSTRACT FROM AUTHOR]

Vitex negundo has ecological, ornamental, medicinal, and practical values. However, in the establishment of the rapid propagation system of Vitex negundo, it was found that the contamination rate of seeds in the process of sterile germination was extremely high, reaching 50%-75%. In this study, in order to reduce its contamination rate in the process of sterile germination of Vitex negundo seeds, by identifying its main contaminating strains, and screening out effective fungistatic agents, tissue separation method was used to isolate and purify the contaminating fungi. Simultaneously, the cytological observation of the conidia of the contaminating fungi was carried out by light microscope and scanning electron microscope. Then the universal primers of the Internal Transcribed Spacer(ITS) sequence of the fungal rDNA gene were used for molecular identification. Finally, four fungicides, including chlorothalonil, mancozeb, carbendazim, and Flumorph-Mn-Zn were added to the PDA medium for analysis of antifungial effect. The results showed that the main contaminating fungi were the fungi located on the surface of the seeds. The colonies were yellowish-green concentric circles in velvety shape. The mycelia were septum brown branching bacteria, and the conidia were olive brown, septum and clostridial form. Cytological and molecular biological identifications indicated that the contaminating fungus was Alternaria alternata. The antifungial study showed that 60% of Flumorph-Mn-Zn had the best inhibitory effect on Alternaria alternata. and the colony diameter was the smallest. The contamination rate was significantly reduced to 5.5%, when 60% of Flumorph-Mn-Zn was diluted 1 400 times and added to the sterile germination medium(water agar medium) of Vitex negundo seeds. In conclusion, the main contaminating fungus in the sterile germination of Vitex negundo seeds was Alternaria altemate, 60% of Flumorph-Mn-Zn had the best inhibitory effect on it. [ABSTRACT FROM AUTHOR]

The structure of water-soluble imidazoline amide molecule was optimized by using GaussView 6 and Gaussian 16 software， and the energy difference was obtained through orbital energy calculation. According to the energy difference， the corrosion inhibition mechanism was revealed, and the corrosion inhibition mechanism of water-soluble imidazoline amide on A3 steel was further revealed. At the same time, the corrosion inhibition performance of water-soluble imidazoline amide on A3 steel in hydrochloric acid medium was studied by rotating coupon test, electrochemical method and scanning electron microscope. The results show that the optimum amount of water-soluble imidazoline amide is 15 mg/L in dilute hydrochloric acid solution with corrosion medium of 1 mol/L and at 45 ± 1 ℃, and the corrosion inhibition rate is as high as 96.8%; The polarization curve of electrochemical test is consistent with the results of rotating coupon test. It can be seen by scanning electron microscope that water-soluble imidazoline amide has significant corrosion inhibition effect on A3 steel. [ABSTRACT FROM AUTHOR]

Modified sludge adsorbent was prepared from fly ash and domestic sludge through physical activation and physical-chemical activation. The properties of sludge adsorbent were studied by specific surface area tester （BET), scanning electron microscope （SEM), X-ray diffractometer, Fourier infrared spectrometer （FT-IR) and zeta potentiometer. The removal efficiency and adsorption mechanism of modified sludge adsorbent for Cd（Ⅱ) and Cu（Ⅱ) were analyzed. The results show that the surface structure of raw sludge adsorbent （RSA) is dense, and the specific surface area of BTE is 12.604 m²/g. the surface of modified sludge adsorbent （MSA) is rough, and the hole is obviously larger, and the specific surface area of BTE is 52.573 m²/g. The adsorption of Cd（Ⅱ) and Cu（Ⅱ) by RSA and MSA reached equilibrium after 360 min. The removal rates of Cd（Ⅱ) and Cu（Ⅱ) by MSA increased by 30.83% and 61.81% respectively compared with RSA. With the increase of pH value （2 ≤ pH ≤ 6), the removal rate of Cu（Ⅱ) by RSA increased from 16.83% to 74.32%, and the removal rate of Cd（Ⅱ) increased from 3.17% to 36.33%; The removal rate of Cu（Ⅱ) by MSA increased from 51.50% to 95.77%, and the removal rate of Cd（Ⅱ) increased from 25.00% to 48.17%. The adsorption capacity of MSA for Cd（Ⅱ) and Cu（Ⅱ) increased from 7.23 mg/g and 15.48 mg/g at 298 K to 9.54 mg/g and 16.206 mg/g at 318 K, respectively. The maximum theoretical adsorption capacity of Cd（Ⅱ) and Cu（Ⅱ) by MSA is 18.69 mg/g and 20.92 mg/g respectively, the Langmuir adsorption isothermal model R² is 0.9980 and 0.9965 respectively, and the quasi second-order kinetic model R2 is more than 0.99, indicating that the adsorption process of MSA for Cd （Ⅱ) and Cu (Ⅱ) is dominated by the chemical reaction of hydroxyl and carboxyl groups, supplemented by the physical effect of monolayer adsorption. The adsorption of Cd（Ⅱ) and Cu（Ⅱ) by MSA is an endothermic process, and the adsorption of Cu（Ⅱ) is spontaneous. Therefore, modified sludge can be used as a potential adsorption material to treat wastewater containing heavy metals. [ABSTRACT FROM AUTHOR]

BACKGROUND: With the increasing number of traffic accidents, fall injuries, and sports injuries, traumatic spinal cord injury has become the primary disease that threatens spinal cord health. OBJECTIVE: To investigate the efficacy of collagen/silk fibroin scaffold combined with neural stem cells in the treatment of traumatic spinal cord injury. METHODS: (1) Collagen and silk fibroin raw materials were extracted separately and mixed in a mass ratio of 2:4. Collagen/silk fibroin scaffold was prepared by vacuum freeze-drying. Passage 3 GFP mouse neural stem cells were seeded on collagen/silk fibroin scaffolds. Neural stem cell growth was observed under light microscope and scanning electron microscope. (2) Totally 40 adult SD rats were randomly divided into five groups (n=8 per group). The normal group did not receive any treatment. In the model group, a T10 segment spinal cord defect model was established. In the stem cell group, neural stem cells were injected into the spinal cord defect. Collagen/silk fibroin scaffolds were implanted at the spinal cord defect site in the scaffold group. Collagen/silk fibroin scaffolds seeded with neural stem cells were implanted at the spinal cord defect site of the combination group. Open field test BBB score and slope test were performed every week after operation. Evoked potential detection, hematoxylin-eosin staining and immunofluorescence staining were conducted to evaluate the recovery of traumatic spinal cord injury rats. RESULTS AND CONCLUSION: (1) Optical microscopy and scanning electron microscopy showed that the collagen/silk fibroin scaffolds were favorable for the adhesion, extension and differentiation of neural stem cells. (2) Open field test BBB score and slope test results demonstrated that the motor function of the rats in each spinal cord injury group recovered to different degrees with the prolongation of time. The speed and degree of motor function recovery of the rats in each treatment group were better than those in the model group, and the motor function recovery of the rats in the combination group was the best. At 8 weeks after operation, the detection results of latency and amplitude of motor evoked potentials and somatosensory evoked potentials of rats in each treatment group were better than those in the model group after spinal cord injury (P < 0.05). The detection results of the combination group were better than those of the stem cell group and the scaffold group (P < 0.05). At 8 weeks after operation, hematoxylin-eosin staining demonstrated that the repair effect of the injured spinal cord in the model group was the worst and the repair effect of the combination group was the best. Immunofluorescence staining exhibited that the number of neurofilament protein-positive cells at the spinal cord injury site of the rats in the model group was the least, and the number of neurofilament protein-positive cells in each treatment group was more than that in the model group, among which the number of the combination group was the most. (3) Collagen/silk fibroin scaffold combined with neural stem cells has a certain effect on the improvement of the function of both lower limbs and the repair of spinal cord tissue in rats with traumatic spinal cord injury. [ABSTRACT FROM AUTHOR]

BACKGROUND: During stem cell transplantation, the generation of a large number of free radicals damages the cells in situ, and then reducing the cell survival. In the past decade, the emergence of nanozymes provides a new method for scavenging excess free radicals. Among them, manganese oxide (Mn3O4) is one of the promising nanomaterials, because it could provide Mn trace elements in human body as well as its well antioxidative stress properties and biodegradability. Mn3O4 can be used as a new type of nanomaterial to protect the extension function of stem cells. OBJECTIVE: To produce Mn3O4 nanoparticles for detecting its effect on scavenging and spreading function of bone marrow mesenchymal stem cells during oxidative stress. METHODS: Mn3O4 nanoparticles were prepared by hydrothermal method. Scanning electron microscope and X-ray diffraction were used to characterize the morphology and structure of Mn3O4, respectively. The particle size and zetapotential data of the nanoparticle in human-simulated environment were detected by the dynamic light scattering. The antioxidant capacity of Mn3O4 was tested in neutral environment. The CCK-8 and live-dead staining assays were utilized to verify the biological toxicity of Mn3O4 to bone marrow mesenchymal stem cells. H2O2 was used to induce oxidative stress of bone marrow mesenchymal stem cells. The effect of Mn3O4 on antioxidant ability and spreading ability of bone marrow mesenchymal stem cells was detected under oxidative stress. RESULTS AND CONCLUSION: (1) The results of scanning electron microscope and X-ray diffraction exhibited that the material was Mn3O4 with average particle size about 70-80 nm. The dynamic light scattering showed that the particle size of the nanoparticles in PBS solution was about 100 nm, and the Zeta potential was about +20 mV. Antioxidant performance experiments showed that Mn3O4 had a certain antioxidant capacity. (2) The CCK-8 assay, live-death staining and reactive oxygen scavenging experiment demonstrated that Mn3O4 did not show biotoxicity and exhibited a certain level of reactive oxygen scavenging ability under 40 mg/L. (3) The cell spreading analysis showed that H2O2 had a significant inhibitory effect on the spreading function of bone marrow mesenchymal stem cells. After adding Mn3O4 into the cell culture microenvironment, the cell spreading area had no significant difference compared with the control group (P > 0.05). Moreover, the single use of Mn3O4 did not inhibit the spreading function of bone marrow mesenchymal stem cells (P > 0.05). (4) The results have shown that the addition of Mn3O4 nanoparticles in the cell microenvironment can resist oxidative stress and have a certain protective effect on the spreading function of bone marrow mesenchymal stem cells. [ABSTRACT FROM AUTHOR]

LiMgPO4 and LiMgPO4∶ Dy were synthesized by high-temperature solid-state method and sol-gel method. The effects of different synthesis methods on crystal structure, morphology and luminescence properties of LiMgPO4∶ Dy were studied using thermogravimetry-differential thermal analyzor, X-ray diffractometer, Fourier transform infrared spectrometer, scanning electron microscope, ultraviolet-visible spectrophotometer and fluorospectro-photometer. The results show that the lowest synthesis temperature by sol-gel method is 750 ℃ and no other crystal phases are found in the crystal, while a small amount of Mg3 (PO4) 2 crystal phases are found in the sample synthesized by high-temperature solid-state method at 950 ℃. The morphology of the samples synthesized by sol-gel method is better than that synthesized by high-temperature solid-state method. Samples synthesized by both methods show low absorbance in the visible region. In the ultraviolet region, the absorbance of the sample synthesized by high-temperature solid-state method is higher than that synthesized by sol-gel method. The optical band gap range of LiMgPO4∶ Dy synthesized by high-temperature solid-state method is 3. 76 ~ 3. 93 eV, and that of LiMgPO4∶ Dy synthesized by sol-gel method is 3.85 ~ 3.94 eV. The synthesis method has little effect on the optical band gap of the sample. The optimal excitation wavelength of LiMgPO4∶ Dy is 350 nm, and the strongest emission wavelength is 579 nm. The luminescence intensity of the samples synthesized by sol-gel method is better than that synthesized by high-temperature solid-state method. [ABSTRACT FROM AUTHOR]

β-(AlxGa1-x)2O3 presents great applications in modern power devices and deep ultraviolet photoelectric detection for their excellent anti-breakdown and tunable band gap. However, the complexity and difficulty of the traditional fabrication processes limit their further development. In this work, a relatively simple high temperature diffusion process was used to successfully prepare β-(AlxGa1-x)2O3 nano films on c-sapphire substrates. The films were investigated by X-ray diffraction, atomic force microscope, scanning electron microscope, and ultraviolet visible spectrophotometer. Since Al atoms in sapphire substrates will diffuse into the Ga2O3 layer at high temperatures, β-Ga2O3 thin films will be converted into β-(AlxGa1-x)2O3 thin films with different ratios of Al to Ga atoms. It illustrates that with the increase of annealing temperature from 1 010 ℃ to 1 250 ℃, the average content of Al in the films increases from 0. 033 to 0. 371. Meanwhile, the thickness of films increase from 186 nm to 297 nm, accompanied by the roughness increase from 2. 31 nm to 15. 10 nm with the increase of the annealing temperature from 950 ℃ to 1 250 ℃ . While increasing the annealing temperature from 950 ℃ to 1 190 ℃, the band gap of films increases from 4. 79 eV to 5. 96 eV. The results suggest that the high temperature diffusion process can effectively adjust the optical band gap of β-(AlxGa1-x)2O3 thin films, providing an experimental basis for novel β-(AlxGa1-x)2O3 -based optoelectronic devices. [ABSTRACT FROM AUTHOR]

BACKGROUND: Titanium as a bone substitute material has been widely used in the field of oral implant devices, but its bioinert would affect the stable combination with bone tissue at the early stage of implantation. Therefore, exploring to improve the osteogenic properties of titanium through surface modification is necessary. OBJECTIVE: To investigate the effect of composite coating of aspirin loaded chitosan nanoparticles and polydopamine on the viability of osteoblasts in vitro. METHODS: The titanium sheets modified by polydopamine coating as well as aspirin loaded chitosan nanoparticles and polydopamine composite coating were constructed. The surface morphology and microstructure of the coatings were characterized by scanning electron microscopy. In vitro sustained-release properties of aspirin nanosphere coatings on pure titanium were detected. Rat bone marrow mesenchymal stem cells were seeded and cultured on the pure titanium sheet and the two kinds of modified titanium sheets. The spreading morphology of rat bone marrow mesenchymal stem cells on the surface of titanium sheets was observed by cytoskeleton staining. Cell proliferation was determined by CCK-8 assay. The osteogenic differentiation of rat bone marrow mesenchymal stem cells on titanium sheets was measured using alkaline phosphatase staining and immunofluorescence staining. RESULTS AND CONCLUSION: (1) Scanning electron microscope images showed that the pure titanium surface was relatively smooth, and deposits as well as grain appeared after the dopamine polymerization. Aspirin microspheres were spherical with uniform size distribution. The hydrophilicity of the nanoparticles immobilized titanium surfaces and the polydopamine coating modified titanium surfaces were better than that of the pure titanium sheets (P < 0.05). The aspirin appeared to be slow and sustained under the encapsulation of chitosan nanoparticles. (2) As observed by cytoskeleton staining, the cells showed insufficient cell expansion on the surface of the pure titanium sheets and formed a few filopodia on the dopamine modified titanium sheets. The cells on nanoparticles modified sheets showed perfect expansion. (3) CCK-8 assay showed that the titanium sheets had no obvious cytotoxicity, and the cell proliferation rate of the nanoparticles modified titanium sheets displayed higher rates of proliferation than that of the dopamine coated and pure titanium sheets with increasing cell culture time (P < 0.05). (4) Alkaline phosphatase activity was highest on the surfaces of nanoparticles modified sheets. Immunofluorescence showed that the fluorescence intensity of alkaline phosphatase was strongest. (5) The results showed that the sustained-release coating of aspirin loaded chitosan nanoparticles on the titanium surfaces could enhance the proliferation and adhesion of rat bone marrow mesenchymal stem cells and promote osteogenic differentiation. [ABSTRACT FROM AUTHOR]

BACKGROUND: The effect of composite culture of scaffold materials and biological factors on chondrocyte function in different conditions is a hot topic in the research of tissue-engineered materials. OBJECTIVE: To investigate the effect of hyaluronic acid combined with domestic porous tantalum on the function of rat chondrocytes under the dynamic environment. METHODS: Knee chondrocytes of SD rats were extracted and cultured. Five groups of experiments were established as static culture group (group A), tantalum static group (group B), tantalum hyaluronic acid static group (group C), tantalum dynamic group (in the dynamic bottle rotation, two-way alternating forward and reverse rotation; the rotation angle is 40°, 40 r/h; group D), and tantalum hyaluronic acid dynamic group (in the dynamic bottle rotation, two-way alternating forward and reverse rotation; the rotation angle is 40°, 40 r/h; group E). The samples were continuously cultured for 7 days in the five groups. Cell morphology on materials was observed under a scanning electron microscope. The secretion of proteoglycan, type II collagen and SOX9 was detected by ELISA. The expression levels of proteoglycan, type II collagen and SOX9 protein were detected by western blot assay. RESULTS AND CONCLUSION: (1) Scanning electron microscope observation showed that with the prolongation of static culture time, the number of chondrocytes in group C gradually increased, and gradually covered the surface of tantalum material. (2) On the 5th day of culture, the secretion of proteoglycan and type II collagen in group C was higher than that in groups A and B (P < 0.05). The secretion of SOX9 in group D was lower than that in group E (P < 0.05). The secretion of proteoglycan and type II collagen in group B was lower than that in group D (P < 0.05). The secretion of proteoglycan and type II collagen in group C was lower than that in group E (P < 0.05). (3) On the 5th day of culture, the expression of type II collagen in group C was higher than that in group B (P < 0.05), and the expression of proteoglycan and type II collagen in group D was higher than that in group B (P < 0.05). The expression levels of proteoglycan and type II collagen in group E were higher than those in group C (P < 0.05). (4) These findings suggest that the combination of domestic porous tantalum and hyaluronic acid can promote the secretion and protein expression of proteoglycan and type II collagen in chondrocytes. Under dynamic environment culture, the secretion and protein expression of proteoglycan and type II collagen are better than in static culture. SOX9 secretion and protein expression are not affected by the dynamic and static culture environments. [ABSTRACT FROM AUTHOR]