Search

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]

In order to ensure the safe and stable operation of the side-blown furnace adopting new process, the corrosion damage mechanism of the magnesia-chrome brick of the side wall at the slag line in a side-blown copper smelting furnace was researched using a scanning electron microscope and an energy dispersive spectrometer. The results show that: (1) the magnesia-chrome bricks located at the slag line undergo alternating corrosion and infiltration of copper matte and slag, which is hardly to form a stable slag layer, resulting in a continuous cycle of infiltration-corrosion-spalling of magnesia-chrome bricks and the severest corrosion;the corrosion of the magnesia-chrome bricks above the slag line is slight, because the infiltration of copper matte in the bricks is obviously weaken, and a stable spinel and olivine dense layer is formed on the hot surface of the bricks, serving as a barrier against further penetration and corrosion of slag and copper matte to a certain extent; (2) although copper matte only penetrates along the pores and grain boundaries in magnesia-chrome bricks without participating in the corrosion reaction, it penetrates and wraps the matrix particles or grains, disrupting the direct bonding of magnesia-chrome bricks, destroying the stable structure of the original magnesia-chrome bricks and consequently reducing their resistance to slag and copper matte; (3) the copper matte primarily penetrates along the chromite particles, and gaps between periclase crystals after the precipitation of iron-rich spinel, which is disadvantageous for the resistance of magnesia-chrome bricks to the penetration and corrosion of SiO2-FeO slag. [ABSTRACT FROM AUTHOR]

In this paper, the inactivation kinetics of potassium sorbate-assisted high pressure thermal sterilization (HPTS) on Bacillus subtilis spores were studied. First-order kinetics model, Weibull and Log-logistic kinetics models were used to fit the inactivation curve of B. subtilis spores by potassium sorbate-assisted HPTS. By analysis of precision factor (Df), bias factor (Bf), root mean square error (RMSE), coefficient of determination (R²), In the three models, Log- logistic Kinetic model fitted best the spore sterilization effect of potassium sorbate-assisted HPTS (R² =0.986). When potassium sorbate (0.2g/100mL) assisted HPTS (600 MPa, 75 25min), the inactivation effect was the best, and the spore inactivation was 6.10 lg (CFU/mL). Potassium sorbate assisted HPTS treatment was applied to the inactivation of spores in muskmelon juice, it was found that the browning degree was significantly reduced, after 28 days of storage, the absorbance of potassium sorbate (0.1g/100mL) assisted HPTS (600 MPa, 75 25 min) at 420 mn reached 0.093, The absorbance of the HPTS-treated control sample was 0.058. Scanning electron microscope was used to observe the microstructure of Bacillus subtilis spores in muskmelon juice before and after treatment, and it was found that the morphological structure of the spores changed after treatment. In conclusion, potassium sorbate assisted HPTS has significant application value. [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]

The microstructure characteristics of rocks are the internal basic properties of fine-grained rocks, which affect their physicochemical behavior. This paper takes an example as fine-grained grains in the Yanchang Formation 7 Member of Ordos Basin. First, the geometric morphology characteristics of fine-grained grains are analyzed quantitatively by field scanning electron microscope and image recognition technology. Then, we characterized the influence of the sedimentary environment on the geometric shape and orientation arrangement of fine-grained grains. Results show that the grains in the deep-semi-deep lacustrine facies take the characteristics of fine grain size (2-3 μm), flat and angular shape. The grains are directionally distributed along with a continuous interval. The intensity of the distribution shows a flat quasi-cone shape and well-directional orientation. The fine grains in shallow lake facies are medium-fine grains (2-8 μm), flat and angular type. Besides, the grains show a sharp distribution a-long with a certain interval with no obvious regularity, which has a moderate orientation arrangement. The fine grains in delta facies are fine-grained (8-12 μm) and quasi-circular type. This type of fine-grained rock has an irregular distribution. The intensity distribution of fine grains is circular or elliptical. The circumferential angularity index and flatness of grains can promote the formation of oriented arrangement structure of grains. By contrast, the anisotropy rate and grain size are unfavorable for the formation of an oriented structure. The results are helpful to understand the microstructural characteristics of fine-grained rocks and establish the relationship between microstructures and macrostructures of rocks. [ABSTRACT FROM AUTHOR]

In order to prepare fluorescent cellulose acetate fiber with higher fluorescence intensity and stability. N, N-dimethylformamide was used as the solvent, cellulose acetate was used as the raw material, europium-and dysprosium-doped strontium alkaline-earth aluminate were used as the fluorescent molecules, and deionized water were used as the solidification bath, fluorescent cellulose acetate fibers were prepared by wet spinning. The surface morphology, mechanical property, fluorescent particle distribution, and fluorescence property of the fiber prepared at different spinning solution concentrations, fluorescent particle contents and solidification bath temperatures were characterized by using trans reflectance metallurgical microscope, electronic single-fiber compactor, a scanning electron microscope and fluorescence spectrometer. The results showed that the fluorescent fibers produced by wet spinning had breaking strength of 4.2 cN/dtex, breaking elongation of 380% and fluorescence intensity of 4.8x105 when the concentration of spinning solution was 20%, the fluorescent particle mass fraction was 3%, and the solidification bath temperature was 25 °C. [ABSTRACT FROM AUTHOR]

In order to improve the property of polyacrylonitrile (PAN) nanofibrous membrane, MgO nanoparticles and Ag nanoparticles (MgONPs and AgNPs) were added into the polyacrylonitrile (PAN) solution. PAN/MgO/Ag composite nanofibrous filtration membranes with different mass fractions of MgO and Ag nanoparticles were prepared through electrospinning method. Their microstructure, crystalline structure, air permeability, moisture permeability and filtration property were tested by scanning electron microscope, X-ray diffractometer, infrared spectrometer, ultraviolet translucency analyzer and filtration property tester. Test results showed that the fiber diameter of pure PAN nanofiber was 222.9 nm while the diameter of PAN/MgO/Ag composite nanofibers were 151.5 nm~258.6 nm. Compared with pure PAN nanofibrous membrane, composite PAN/MgO/Ag nanofibrous membranes possessed excellent filter performance and ultraviolet protective property. Their UV protective factor were 38.73~55.37. The filtration efficiency were 95.36%~97.59% while the pressure drop were 46.06 Pa~58.31 Pa. When the mass fraction of MgONPs and AgNPs were both 0.75%, PAN/MgO/Ag composite nanofibrous membrane had the maximum quality factor of 0.071 4 Pa-1 and the filtration performance was the best, which belonged to the fiber filtration material with higher efficiency and lower resistance and UV protection property. [ABSTRACT FROM AUTHOR]

In order to study the influence of long-term water action on the behavior characteristics of steel slag aggregate-asphalt interface and the related mechanism, atomic force microscope, X-ray diffraction, scanning electron microscope, immersion Marshall test, rutting test and so on were used to analyze from macro and micro perspectives. The results show that long-term water erosion changes the surface chemical properties of steel slag, making the surface roughness, surface area and adhesion strength of the steel slag increase. Compared with limestone asphalt mixture, the residual stability and dynamic stability of steel slag asphalt mixture have a growth potential, but the swelling of hot-sealed steel slag and cold-sealed steel slag is different. The swelling amount of cold-sealed steel slag asphalt mixture is greater than that of hot-sealed steel slag asphalt mixture, which should be treated differently in the application process. The slow digestion rate of f-CaO in cold-sealed steel slag aggregate causes the volume expansion of the specimen in the late stage, aggravates the generation of microcracks on the surface of the specimen, and results in the poor freeze-thaw splitting strength of cold-sealed steel slag asphalt mixture in the late stage. [ABSTRACT FROM AUTHOR]

In order to study the optimum processing conditions of puffed shrimp slices,cassava starch and Penaeusvannamei were used as raw materials. The effects of cooking time, aging time, slice thickness, drying time and frying temperature on the expansion degree and sensory score of the products were studied by single factor test and response surface test. The results showed that optimal processing technology of puffed shrimp slices was determined as follows: cooking time for 33.82 min, aging at 4 °C for 24.72 h, sliced into 1~2 mm slices, air dried at 60 °C for 4.95 h, and fried at 180 °C. Under these conditions, the puffed shrimp slices were crispy and delicious, with strong salty taste, good puffing effect, high protein content and reasonable oil content. The sensory analysis of flavor profile showed that the flavor of puffed shrimp slices was evaluated well, with high scores of crispness and fat aroma, moderate sweetness, but slightly greasy, and there was still room for improvement in oil control. Scanning electron microscope analysis confirmed that before frying, the gap, pore volume and pore diameter of shrimp slices were large, so the fried products were crisp and delicious. 21 kinds of flavor compounds in potato chips before frying and 20 kinds after frying were analyzed by gas chromatography-mass spectrometry (GC-MS). The result of scanning electron microscopy showed that before frying, the relative content of terpenes, alcohols and aldehydes accounted for a large proportion of the total aroma components, while after frying, the relative content of acids, esters and aldehydes accounted for a large proportion of the total aroma components. The above results provided an experimental and theoretical basis for the industrial application of puffed shrimp slices. [ABSTRACT FROM AUTHOR]

To reduce the mechanical sensitivity and improve the comprehensive performance of hexanitrohexaazaisowurtzitane (CL-20), 3-aminopropyltriethoxysilane (APS) was used as the modifier to modify the surface of CL-20, and graphite oxide (GO) was used as the coating material, CL-20@GO core-shell composite was prepared by electrostatic self-assembly. The tissue morphology of the prepared samples was characterized by water contact angle test, scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The thermal performance was tested by differential scanning calorimeter (DSC), and the mechanical sensitivity was tested. The results show that the CL-20 modified by 5% (mass fracton) APS solution has the strongest hydrophilic, indicating the successful introduction of amino groups. The CL-20 particles are coated by GO layer completely. Compared with the raw CL-20, the activation energy of CL-20@GO composite increases by 63.0 kj/mol, the impact sensitivity (H50) increases from 13.0 cm to 23.5 cm, and the friction sensitivity decreases from 100% to 24%, showing that the coating of GO by electrostatic self-assembly can significantly reduce the sensitivity of CL-20. [ABSTRACT FROM AUTHOR]

The macroscopic mechanical test of C40 aeolian sand concrete was carried out. Combined with scanning electron microscope (SEM) and nuclear magnetic resonance (NMR) technology, the internal relationship between pore structure and mechanical properties of aeolian sand concrete was discussed, and the influence mechanism was revealed. The regression analysis was used to establish the pore structure-strength model under two factors. The results show that with the increase of aeolian sand replacement rate, the microstructure of aeolian sand concrete is compact first and then loose, the porosity and harmless pore ratio decrease first and then increase, and the compressive strength increases first and then decreases. When the replacement rate is 20%, the strength is the highest. The appropriate amount of aeolian sand improves the aggregate gradation of concrete, refines the pores, reduces the initial damage of the loading surface, and enhances the macroscopic performance. The established pore structure-strength model with harmless pore ratio and harmless porosity as dependent variables can better predict the strength of concrete. [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]

[Objective] The flowering time of Diospyros deyangensis, a new species of Diospyros (Ebenaceae), was clarified and the developmental stages of floral buds were distinguished. [Method] The developmental stages of 10 years old male and female floral buds were observed by paraffin section and scanning electron microscope. [Result] The whole developmental process of floral buds can be divided into two stages by dormancy periods. The bract primordia, sepal primordium and petal primordium formed in the floral buds at the early stage of developmental process ranging from June to July. In the later stage of differentiation from March to May of the following year, flower buds formed stamen primordium and carpel primordium. The male floral buds were 17 d earlier than the female floral buds due to earlier end of dormancy. Afterwards, the sexual cells of floral buds began to develop, and the maturation of pollens and embryo sacs completed basically at the same time. [Conclusion] There were significant morphological differences between female and male floral buds during the development period of sepal primordia and the development period of stamen and carpel primordia. [ABSTRACT FROM AUTHOR]

The envelope system of adhesive mortar, thermal insulation material, rendering mortar and decoration material is taken as the research object, and the deterioration process of the envelope system performance caused by freeze-thaw cycle in the cold region is discussed and analyzed by tensile test and scanning electron microscope. The results show that after 100 freezethaw cycles, there are different degrees of damage on the surface of the specimen, mainly concentrated in the corner of the specimen. By testing the tensile strength of the envelope materials under various freeze-thaw cycles, it is proved that freeze-thaw conditions cause varying degrees of damage to each interface of the envelope. Among them, adhesive mortar and rendering mortar are prone to bond failure. With the increase of freezing and thawing times, the first damage position of the envelope structure was transferred from the adhesive mortar to the rendering mortar. [ABSTRACT FROM AUTHOR]

By means of SEM scanning electron microscope and SPSS iterative regression analysis, the influence law and mechanism of different dosages of cement, mineral powder and silica fume on the physical mechanics and water resistance of foamed desulfurization gypsum were studied. The results show that both cement alone and mineral powder can effectively improve the mechanical and water resistance properties of gypsum foam; When mixed with 10% cement and 14% mineral powder, the overall performance of the hardened body is better, with the maximum 28 d compressive, flexural strengths and softening coefficients of 18.69 MPa, 4.92 MPa and 0.486; The larger amount of silica fume is easy to agglomerate to make the volume of the composite slurry swell, resulting in a decrease in strength and softening coefficient of the specimen, the amount of silica fume should not be more than 10%. Combined with the experimental data, the linear regression model of compressive strength versus porosity of the composites when single blended with cement and compound blended with mineral powder was obtained, the model regression effect was significant, and the regression curve was in good agreement with the experimental data. Microscopic display, the hydration products of admixtures form dense microstructures by filling and encapsulating gypsum crystals, thereby enhancing the strength and water resistance of foam desulfurized building gypsum. [ABSTRACT FROM AUTHOR]

The effects of six slag dosages of 0%, 10%, 20%, 30%, 40% and 50% (mass fraction, the same below) on the shrinkage of fly ash-based geopolymer (FAGP) concrete during thermal curing process were studied with digital image correlation (DIC) method. The compressive strength of concrete and paste after thermal curing were tested, and the microscopic mechanism was analyzed by combining simultaneous thermal analysis (TG-DSC), X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that with the increase of slag content, the total shrinkage and shrinkage rate of FAGP first decrease and then increase, the compressive strength increases first and then decreases, the hydration degree increases, and the number of microcracks increases. When the slag content is 40%, FAGP concrete has the smallest shrinkage and the highest compressive strength. When the slag content is low, the hydration degree of the geopolymer is small, and there are fewer microcracks. At this time, the main reason for the shrinkage of the geopolymer is the lower elastic modulus at the beginning of thermal curing. When the slag content is high, the hydration degree of the geopolymer is high, and there are many microcracks. At this time, the shrinkage deformation of the geopolymer is mainly caused by a large degree of chemical reaction. [ABSTRACT FROM AUTHOR]

Magnesium oxysulfate cement has the advantages of light weight, low thermal conductivity and fire resistance, so it has great market potential to be prepared as foamed concrete and applied in building exterior insulation system. The density of ultra-lightweight magnesium oxysulfate foamed concrete was regulated by incorporating high stability modified foam. The changes in pore structure were investigated through scanning electron microscope (SEM) and optical microscope (OM). Additionally, the effects of density and pore structure variations on the compressive strength and thermal conductivity of ultra-lightweight magnesium oxysulfate foamed concrete were also studied. The results indicate that with the increase of content of high stability modified foam, the number of pores increases and the average pore size significantly decreases. The density of ultra-lightweight magnesium oxysulfate foamed concrete decreases gradually, and the compressive strength gradually decreases as well. When the foam content is 250% (mass fraction), the density of ultra-lightweight magnesium oxysulfate foamed concrete reduces to 88.33 kg/m³, and the thermal conductivity reduces to 0.038 2 W/ (m·K). [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

To investigate tentatively the inhibition mechanism of eight monoalkylphenol flavor compounds (EMFC), which were listed in the positive list of Chinese food additive use standard (GB2760-2014), against Escherichia coli (EC), and to determine the relation of the inhibition effect to the structure of EMFC, spectrophotometry, electrical conductivity and scanning electron microscope were used in this present study. The results showed all of the EMFC at the concentrations from 0.195 mg/mL to 0.781 mg/mL had effects on the production curve of EC in different degrees; EMFC enhanced the permeability of cell membrane, resulting in the leakage of intracellular ions; with the increasing of EMFC concentrations, the release of cell constituents increased. The results of scanning electron microscope indicated all of the EMFC at their minimum inhibitory concentration could damage the cell membrane and cell wall of EC to a certain extent, and make EC not the normal cell morphology but bends, folds, and depressions. The inhibition effects of EMFC on EC were associated with the structure of EMFC; the efficiency of propylphenol was better than that of ethylphenol, ethylphenol better than methylphenol. When alkyl group attached to benzene ring was same, alkylphenol whose alkyl group was at the para-position of hydroxyl group had the best bacteriostatic activity. EMFC could inhibit the growth of EC by damaging the cell membrane and enhancing the cell membrane permeability. The result obtained lays a theoretical basis for developing food preservatives by using phenol flavor compounds. [ABSTRACT FROM AUTHOR]

In this study, quorum-sensing quenching activity of Lactobacillus crustorum ZHG2-1 was verified with the Chromobacterium violaceum CV026 as a indicator strain. Based on the change of biofilm, phenotypes of spoilage factors and the expression levels of related genes, the quorum sensing quenching mechanism of Lb. crustorum ZHG2-1 on P. fluoresces was detected. The results showed that the degradation rate of cell-free supernatant from strain ZHG2-1 to P. fluoresces AHLs reached 100%. The sub-inhibitory concentration (1.0, 2.0, 3.0 mg/mL) of strain ZHG2-1 crude extract could inhibit and remove the biofilm of P. fluoresces, and the inhibition rate and clearance rate reached 9.66%-31.32% and 28.62%-62.82%, respectively. In addition, the inhibition rate of strain ZHG2-1 crude extract with sub-inhibitory concentration on P. fluoresces spoilage factors (exopolysaccharides, proteases, lipases, biogenic amines) reached 7.23%- 100%. Meanwhile, the inhibition rate was mass concentration-dependent. Scanning electron microscope showed that the sub-inhibitory concentration of strain ZHG2-1 crude extract treatment significantly reduced the amount of biofilm and the bacterial colonies were in a dispersed state. The results of qRT-PCR showed that the crude extract of strain ZHG2-1 down-regulated the quorum-sensing genes rhlI and rhlR of P. fluoresces by 0.93 and 0.99, respectively, and the expression levels of aprX, algA, orm, flgA, ldcA and other biofilm and spoilage genes was significantly inhibited. The results indicated that Lb. crustorum interfered with the expression of quorum-sensing genes of P. fluoresces, thereby affecting the production of biofilm and spoilage factors. [ABSTRACT FROM AUTHOR]

The embedding immobilization technology can provide a carrier for microorganisms to improve the ability of microorganisms to remove nitrogen-containing pollutants in the biological aerated filter (BAF) of the recirculating aquaculture system. Based on polyvinyl alcohol-sodium alginate (PVA-SA) composite carrier material, 0%~2% (w/w) cyclodextrin (β-CD), diatomite (DIA) and zeolite (Z-13X) were added. The mechanical strength, physical and chemical stability, reusability, nitrification performance and internal structure of the composite carrier were investigated by orthogonal experiment, physical and chemical properties, water quality monitoring and scanning electron microscope analysis. The results showed that the optimum composite ratio of composite carrier was PVA 10%, SA 2%, β-CD 0%, DIA 2% and Z 1%. The composite carrier with this ratio had good mechanical properties. The modified composite carrier could be applied to acidic tail water, and its internal structure was porous, and the pore size was suitable for microbial growth. At the same time, an efficient nitrifying strain Halomonas sp. NH2B was screened and embedded in a composite carrier for further research. The microbial composite carrier could remove 100% NH4+-N at an initial concentration of 50 mg/L after 36 hours, and after seven cycles, the pore structure of the composite carrier remained basically unchanged, and there were microorganisms attached. The NH4+- N removal rate could still reach 76.93%. In summary, the new composite carrier material can effectively solve the problems of weak viability and strain loss after microbial inoculation, ensure the nitrification efficiency and improve the reusability. [ABSTRACT FROM AUTHOR]

SiC/Cu composites were prepared by hot-pressing powder metallurgy with Al and Mg elements, and the effect of SiC volume percentage on the properties of SiC/Cu composites was studied. X-ray diffraction, Archimedes drainage method, three-point bending method and scanning electron microscope were used to analyze the phase composition, relative density, mechanical properties and micro-morphology of the composite samples, and the thermal conductivity and thermal expansion coefficient were measured. The thermal expansion coefficient of the composite was predicted by ROM mixing law and Turner model. Experimental results show that AlCuMg phase is formed in the matrix of the sample, and the strength is greatly increased, and the mixed fracture is the main type of the sample. The SiC particles are uniformly dispersed in the matrix when the SiC content is low. The density, bending strength, thermal conductivity and thermal expansion coefficient of SiC/Cu composites are 98.81%, 478 MPa, 254.76 W/(m⋅K) and 11.84 x 10-6/K respectively when the SiC content is 35%. When the content of SiC increases, the agglomeration of SiC particles is serious, and the density, bending strength, thermal conductivity and thermal expansion coefficient of the composites decrease. Its hardness increases at first and then decreases, and reaches the maximum value of 110 HRB when the SiC content is 45%. The Turner model is the closest to the measured values of composites. [ABSTRACT FROM AUTHOR]

Poly(12-hydroxystearate) was prepared by polycondensation. Palmitic acid, 3-dimethylaminopropylamine and poly(12-hydroxystearate) were reacted to form a terminated polyhydroxystearate aliphatic amine (HTPF) hyperdispersant. The structure of the product was characterized by IR and ¹H NMR. The dispersion effect of HTPF on carbon black was analyzed by sedimentation experiment and scanning electron microscope. HTPF was added into ABS/carbon black masterbatch, and the effects of the amount of HTPF on the rheological and mechanical properties of ABS/carbon black masterbatch were studied. The results show that the loss modulus and storage modulus of the composites decrease gradually with the increase of HTPF content compared with the pure masterbatch, and the composites appear shear thinning behavior. With the increase of HTPF content, the mechanical properties of the composites gradually improved. When the content of HTPF is 40%, the tensile strength and impact strength of the composite reach the maximum of 45.9 MPa and 8.54 kJ/m²; When the content of HTPF is 50%, the flexural strength of the composites reaches 80.22 MPa. [ABSTRACT FROM AUTHOR]

To realize the resource utilization of zero-discharge production wastewater from the ready-mixed concrete mixing plant, this experiment combined the microstructure detection techniques of the mercury-pressure method, scanning electron microscope, and X-ray diffraction to investigate the role and influence law of wastewater admixture and its storage time on the mechanical properties and microstructure of concrete. The results showed that the 7-day compressive strength of mortar with 100% wastewater admixture increased by 35% and the 28-day compressive strength increased by 16% compared with that of ordinary mortar, while the compressive strength of specimens with other wastewater admixtures increased to a certain extent; the alkaline environment provided by wastewater was beneficial to promote the hydration reaction of cement. The micro-particles contained in the wastewater of ready-mixed concrete production play a filling and bonding role in the microstructure of concrete and improve the compactness of concrete. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan University of Science & Technology, Natural Science is the property of Editorial Office of Journal of Henan University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Henan University of Science & Technology, Natural Science is the property of Editorial Office of Journal of Henan University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Northwest A & F University - Natural Science Edition is the property of Editorial Department of Journal of Northwest A&F University (Natural Science Edition) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of West China Journal of Stomatology is the property of Sichuan University, West China College of Stomatology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of West China Journal of Stomatology is the property of Sichuan University, West China College of Stomatology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to improve the performance of wool fabric, the wool was grafted with e-polylysine catalyzed by glutamine aminotransferase (TGase), and the wool fabric was finished by different TGase enzymatic processes. Scanning electron microscope was used to observe the changes of surface morphology of wool fabric before and after treatment, and the dyeing depth, breaking strength, water absorption and antistatic properties of wool fabric were measured. The results show that the breaking strength of wool was significantly improved after TGase catalyzed e-polylysine grafting, and increased with the increase of e-polylysine grafting amount. When the water absorption rate of wool fabric increases, the water absorption tends to be saturated for 30 s. The adsorption rate of weak acid dyes on wool fabric was improved, and the dyeing depth at 80 °C was close to that of ungrafted wool fabric at 95 °C . The electrostatic voltage half-life of wool fabric decreased from 2. 13 s to 1.47 s, and the antistatic property was improved. [ABSTRACT FROM AUTHOR]

A highly dispersed melamine cyanuric acid (MCA) dispersion with N-methylmorpholine- N-oxide ( NMMO ) aqueous solution as the dispersion medium was prepared using a wet grinding process to address the issues of blockage, wire breakage and flame retardant precipitation in the production process of flame retardant Lyocell fibers using the blending method. The prepared MCA dispersion was used as the flame retardant to prepare flame retardant Lyocell fibers. The stability of MCA dispersion particle size and pH stability, the distribution characteristics of MCA in the spinning solution, the effects of particle size and surface additive content of MCA dispersion on fiber spinnability, thermal stability, mechanical properties and flame retardancy of flame retardant Lyocell fibers were analyzed using laser particle size analyzer, optical microscope, scanning electron microscope, fiber size analyzer, thermogravimetric analyzer, limiting oxygen index analyzer and other equipment. The results show that the particle size and pH value of MCA dispersion have no change. The dissolution degree and dissolution rate of MCA in the spinning solution significantly increase under stirring and vacuum conditions; The particle size of MCA dispersion and the content of surface additives have a significant impact on the spinnability of fibers. For example, when the particle size D90 is 0.5 µm (90% of the particles have a diameter less than 0.5 µm), and the content of surface additives accounts for 6% of the flame retardant, there are no problems such as blocking, fiber breakage, and a large amount of flame retardant precipitation in the coagulation bath during the spinning process; When the MCA content accounts for 40% of the weight of Lyocell fibers, the fibers exhibit good mechanical properties, flame retardancy, and washing resistance. The highest inechanical strength is 2.76 cN/dtex, and the limiting oxygen index (LOI) is 33. 3%. After 12 machine washes, the LOI value of the fibers remains above 30%; In addition, the initial decomposition temperature of the prepared flame retardant Lyocell fiber was significantly increased compared to ordinary Lyocell fibers, and the residual carbon content of cellulose in the fiber (about 24.03%) was higher than that of non flame retardant fibers (about 16.53%) . [ABSTRACT FROM AUTHOR]

Significant shale gas sources have been discovered in Wufeng-Longmaxi Formation in the Yiling Block of Western Hubei. This paper aims to investigate the palaeoenvironmental conditions and is shale gas geological significance of the Wufeng-Longmaxi shales from well YD1 by integrating data on total organic carbon (TOC) content, major and trace elements, and scanning electron microscope and so on. The results show that the average TOC value of the Wufeng Formation and the lower part of Long-maxi Formation are greater than 2. 00%, and thus they are organic-rich shales which are rich in Si, Ca, Vr, Co, Ni, Zn, Mo, Ba and U. The Wufeng-Longmaxi shales were deposited under highly restricted conditions, which are the main reasons for the organic matter accumulation. Due to the tectonic uplift caused by the Kwangsian Orogeny in the Upper Longmaxi Formation, the palaeoenvironment was characterized by a bottom water oxic conditions, and the insufficient nutrients caused by the weak upwelling, which is the main factor for the turnover of graptolite biozones from LM5 to LM6. The organic rich shale, especially the lower part of Longmaxi Formation, has better physical properties and higher gas content. Compared with the Jiaoshiba Block in Southeastern Sichuan, although the organic-rich shale of Wufeng-Longmaxi Formation in Yiling Block is thinner (10-20 m) and the total gas content is relatively lower, the TOC content is high and the tectonic activity is weak due to the protection by the Huanging rigid basement. It still has good shale gas exploration potential in the northeastern of study area close to the Qinling Ocean. This research has direct meaning to the development of shale gas in Yichang Area, Western Hubei. [ABSTRACT FROM AUTHOR]

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Inorganic Chemicals Industry is the property of Editorial Office of Inorganic Chemicals Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Oilfield Chemistry is the property of Sichuan University, Oilfield Chemistry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]