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As a chronic and infectious disease, dental caries has become a part of the heavy burdens of individuals and society, which is featured with tooth mineral loss and mainly caused by oral bacteria. Anti-caries agent should be safe, and capable of both high bacterial inhibition and remineralization, yet very few ones can meet these requirements simultaneously. In this study, a silver-doped amorphous calcium phosphate (Ag-EACP) is prepared by a biomimetic enzymatic reaction, with the in vivo energy storage biomolecule adenosine triphosphate disodium (Na2ATP) as the phosphorus source. Ag-EACP has an amorphous phase, with high content of ATP. The doped silver in the form of Ag+ ion is stabilized against transformation, can help adjust the size of Ag-EACP. The Ag-EACP can effectively inhibit the growth of Streptococcus mutans and Lactobacillus acidophilus, two main cariogenic pathogens, both in planktonic and free states, and suppress the formation of bio-film. Moreover, this nanocomposite generates significant remineralization and micro-hardness recovery of initial caries lesion. Ag-EACP shows great anti-caries effects on initial caries lesions and is promising for caries prevention in dentistry.

Biomineralization is a set of processes whereby living organisms generate hierarchically structured organic–inorganic materials. Studies on biomineralization not only elucidate the natural process of biomineral formation but also contribute to the development of functional biomaterials. However, the function of small molecules in the process has not been clarified. In this study, phosphoserine (PS) was used as a phosphorus source to prepare biomimetic minerals, and a new flower-like organic–inorganic complex of calcium PS (CaPS) was obtained. The CaPS samples were self-assembled plate-like crystals in the first 10 min. Then, over the next 5 h of the reaction, the plate-like crystals were broken down into fine granular nanoparticles. The chemical and thermal properties of CaPS were characterized, and the results indicated that the CaPS was or had a similar structure to Ca(C3H6NO6P)·H2O. X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure spectra (EXAFS) were obtained, which clearly revealed 6-fold-coordinated Ca-O bonds with lengths of 2.319 (±0.0147) A, 2.358 (±0.0147) A, and 2.435 (±0.0147) A. Furthermore, the results of a CCK-8 assay indicated the high biocompatibility of CaPS. When the samples were co-cultured with mouse preosteoblast cells (MC3T3-E1), CaPS exhibited good bioactivity to promote the osteoblast differentiation of cells. Owing to its excellent chemical and biological properties, the as-prepared CaPS complex is promising for various biomedical applications.

Loess deposition from wind is one of the major sources of soil development in many regions including northeastern China. The dust deposition on snow from 6 sites in Shenyang, northeastern China was collected and characterized physically and chemically to determine its origin (modern vs. re-deposited loess). The origin and characteristics of the dust deposition were evaluated through comparisons with possible sources of sand desert areas based on elemental compositions, such as the A-CN-K (Al2O3-CaO + Na2O-K2O) ternary plot and ratios of Al2O3/TiO2, Fe2O3/TiO2, and Fe2O3/Al2O3. The texture and composition results showed that the dust deposition was most recent and not re-deposited loess. The dust deposition was predominantly silt-sized grains (2–50 μm) and had greater amounts of Na2O (1.7% vs. 1.5% average), MgO (2.1% vs. 1.2%), and CaO (3.2% vs. 1.2%) when compared to the local soil. Its mineral composition was mainly quartz, feldspar, and mica. The magnetic susceptibility of the dust deposition was 30.9 × 10−8 m3/kg and lower than the local soil which was 40.4 × 10−8 m3/kg. Based on the A-CN-K ternary plot, the dust had a weaker weathering intensity than the local soil, loess-paleosol sequences, and red clay. This indicated that the dust was not a re-deposited loess. Furthermore, according to the discriminating analysis using ratios of Al2O3/TiO2, Fe2O3/TiO2, and Fe2O3/Al2O3, the source for the dust was traced from the deserts of south Mongolia, Tengger, Gulban Tungut, and Taklimakan. The two primary factors transporting the dust were the Mongolia Cyclone and westerlies. The dust was blown into the atmosphere, and transported by the atmospheric circulation from west to east and/or from northwest to southeast, which was accompanied also by a cold front cyclone moving southeast towards the study area. The origin, transportation, and deposition process of the dust deposition in this study provides further evidence about the origin of the loess and its likely role in soil development in Shenyang, northeastern China.

Water movement over and through soil is largely driven by topography and soil management across landscapes. This research tested the hypothesis that the water movement determines the potential for P and Ca redistribution and pH variance across landscapes. This hypothesis was evaluated by using digital elevation model-derived terrain attributes in fields after 55 yr of broiler litter applications on pastures in Smith County, Mississippi. Results show that soils receiving broiler litter had mean Mehlich-3 P levels of 1221.8 mg kg⁻¹ at 0- to 15-cm depth and 618.6 mg kg⁻¹ at 15- to 30-cm depth, and Ca with mean values of 768.3 and 645.0 mg kg⁻¹ at 0- to 15-cm and 15- to 30-cm soil depths, respectively. Across fields, soils in areas of predicted convergent flow contained higher P, Ca, and lower pH values in the upper 0 to 15 cm, suggesting contributions via surface overland flow from areas with higher elevation and lower slope gradient. On the other hand, soils in areas with lesser slope and higher elevation also contained high levels of P, Ca, and pH for the subsurface soil depth, suggesting that vertical flow of water on this landscape is a mechanism for movement of P and Ca deeper in the profile. The incorporation of topographic characteristics across fields offers promising results that may be incorporated into improved P indices and management, making them more robust indicators of P mobilization to waterways.

One-dimensional hydroxyapatite (HA) particularly mimics the structure of mineralized collagen fibrils and displays superior mechanical properties such as toughness. Herein, we report Se-doped HA/chitosan (Se-HA/CS) biopapers constructed with self-assembled Se-doped HA nanowires and chitosan. The Se-HA/CS biopapers with high flexibility and manufacturability can not only be further processed into arbitrary shapes by folding or using scissors but also display high performances in in vitro/vivo anti-bone tumor studies. The Se-HA/CS biopapers are more inclined to inhibit the growth of tumor cells (HCS 2/8 and SJSA cells) than that of normal human bone marrow stromal cells (hBMSCs). The potential mechanisms of this meaningful anti-tumor effect were investigated, such as reactive oxygen species accumulation and the activation of apoptosis and the underlying signal pathway involved (including caspase family, Bcl-2 family and JNK/STAT3). The results demonstrate that Se-HA/CS biopapers may inhibit the growth of HCS 2/8 and SJSA cells by synchronously inducing JNK activation and STAT3 inhibition and consequently promote the apoptosis of these cells. Furthermore, the in vivo anti-tumor studies confirm that the Se-HA/CS biopapers obviously suppress the growth of patient-derived xenograft tumor models.

Peripheral nerve injuries represent a great challenge for surgeons. The conductive neural scaffold has experienced increasing interest because of its good biocompatibility and similar electrical properties as compared to those of a normal nerve. Herein, nerve conduits made from poly(d,l-lactide)-co-poly(ethylene glycol) and polypyrrole (20%, 30%, and 50%) (PELA–PPY) were prepared by electrospinning, and used in regeneration of peripheral nerve defects. The results of an in vitro experiment indicated a high biocompatibility for the as-prepared materials, supporting the attachment and proliferation of a rat pheochromocytoma PC-12 cell. Furthermore, the PELA–PPY nerve conduit implanted in the sciatic nerve defects (10 mm) of the Spraguee–Dawley rats for 12 weeks showed similar results with the autograft, while it demonstrated a better outcome than the PELA nerve conduit in electrophysiological examination, sciatic function index, total amount of regenerated myelinated nerve fibers, axon diameter, myelin thic...

Algal organic matter (AOM) and natural organic matter (NOM) from a typical eutrophic lake were comprehensively investigated in terms of their physico-chemical property, components and disinfection byproduct formation potentials (DBPFPs). The relationships between specific chemical properties of AOM and NOM with their corresponding DBPFPs were further evaluated during chlorination. Results indicated that AOM had lower specific UV absorbance (SUVA) but richer organic nitrogen contents than NOM. Fluorescence excitation emission matrix spectroscopy further demonstrated that AOM were chiefly composed of aromatic protein-like and soluble microbial byproduct-like matters, while NOM were mainly contributed from humic acid-like and soluble microbial byproduct-like substances. Although the molecular weight (MW) distribution of AOM and NOM showed no significant difference, size-exclusion chromatography with organic carbon as well as organic nitrogen detection (LC-OCD-OND) revealed that AOM were concentrated with the fraction of building blocks and NOM had higher concentrations of biopolymers and humics (HS). Moreover, AOM displayed higher DBPFPs than NOM, especially for nitrogenous DBPFP (N-DBPFP). MW < 1 kDa fractions both in AOM and NOM contributed the largest proportion to the formation of carbonaceous disinfection byproducts (C-DBPs). In addition, Pearson correlation analysis showed that bulk parameter SUVA was significantly relevant to the formation potentials of trihalomethane both in AOM and NOM, but was ineffective for carbonaceous DBPFP (C-DBPFP) prediction. Dissolved organic nitrogen contents in biopolymer and HS characterized by LC-OCD-OND had strong correlations with N-DBPFPs from AOM and NOM, indicating that LC-OCD-OND quantitative analysis could improve the prediction accuracy of the DBP formation than bulk parameters during NOM and AOM chlorination.

Adenosine triphosphate (ATP) biomolecules play critial roles in the biomineralization process during the formation of amorphous calcium phosphate composites (ACPC), and ACPC is an important drug carrier due to its significant advantages of biocompatibility and biodegradability. Hence, studying the behavior of ACPC nanodrug carriers is crucial to investigate the structural regulation of biomimetic minerals and calcium phosphate (CaP)-based drug delivery systems. However, it is difficult to probe these interactions using traditional characterization methods. In this paper, XANES analysis together with STXM successfully provided a method to reveal the interaction of ATP and drug molecules with individual mesoporous ACPC. We found that the adenosine and phosphate groups of ATP biomolecules coordinated with Ca2+ and played critical roles in the formation of ACPC; drug molecules with the -COOH groups were linked to Ca2+via carboxylic acid groups primarily by electrostatic interactions, and the N-containing ring structures within the drug molecules also coordinated with Ca2+.

Magnesium silicate nanostructured biomaterials with good biocompatibility and high adsorption capacity for drugs and proteins are promising for applications in various biomedical fields. However, the applications of magnesium silicate nanostructured biomaterials in anticancer drug delivery and protein adsorption have rarely been reported so far. Herein, we report a facile strategy for the synthesis of magnesium silicate hollow nanospheres (MSHNSs) by a classical Stober method and a template based solvothermal process. The as-prepared MSHNSs have an ultrahigh specific surface area of 585.6 m2 g−1, ultrahigh hemoglobin (Hb) protein adsorption capacity (1262 mg g−1) and high doxorubicin (DOX) drug loading capacity (559 mg g−1). Moreover, the as-prepared MSHNS/DOX drug delivery system exhibits sustained and pH-responsive drug release performance. Compared with free DOX, the MSHNS/DOX drug delivery system exhibits higher anticancer activity in vitro, and thus it is promising for applications in anticancer treatment.

The development of multifunctional dental-restorative biomaterials with antibacterial activity and remineralization effect for damaged tooth repair is urgent since dental caries is still one of the most common tooth diseases in human beings. Herein, we report a facile strategy for the synthesis of gluey silver-calcium phosphate (GSCP) composites using the rapid microwave-assisted solvothermal method. The as-prepared GSCP composite is an organic-inorganic hybrid, and Ag+ ions display a significant influence on the formation of GSCP by interacting with adenosine triphosphate biomolecules. The as-prepared GSCP composite shows good antibacterial properties, in addition, it exhibits a great effect on sheltering dentinal canaliculi and improving the remineralization of dentine in the simulated saliva. The as-prepared GSCP composite is promising for various applications such as oral healthcare, especially, remineralization of dentine, and antibacterial applications.

Long-term weathering patterns in northeastern China are not well known due to few well-preserved terrestrial paleo-environmental archives in this area. The Chaoyang section is a typical well-preserved loess-paleosol sequence in northeast China with continuous deposition since 423 ka BP; the deposit thus represents an archive of climate change for this region. The sequence was geochemically characterized by major elemental compositions, elemental ratios, a ternary diagram of Al2O3-(CaO* + Na2O)-K2O, improved quantitative reconstruction and elemental distributions with respect to the average for the upper continental crust (AUCC). Another typical loess-paleosol sequence of Lingtai section from the central Chinese Loess Plateau was used for comparison with the loess-paleosol one. The similar AUCC-normalized major elemental distributions and strong correlation of the major elemental compositions between the loess-paleosol sequences indicate that they may have originated predominantly from a similar loess source. Based on the variability in chemical indices corresponding to soil magnetic susceptibility (SUS) and field observations, the loess-paleosol formation period of 423–77 ka BP was separated into eight sub-periods including four periods with greater chemical weathering intensity (paleosols) and four periods characterized by the relative lesser chemical weathering intensity (loess). Relatively intense desilication and fersiallitization primarily occurred in the loess-paleosol sequence from northeast China with greater losses of SiO2 (3.54% in average) and gains of Fe2O3 (0.77%) and Al2O3 (0.33%). Such processes also were reflected in an increase in the amount of K2O (0.41%). Ca and Na leaching was still predominant in the loess-paleosol sequence from the central Chinese Loess Plateau with greater losses of CaO (28.03%) and Na2O (14.03%). The sequence from northeast China records chemical weathering during 423–77 ka BP, which is comparable to the weathering cycles in the sequence from the central Chinese Loess Plateau.

The changes of soil particle size distributions (PSDs) can be used as a proxy for soil development intensity and an indicator of soil formation processes. The fragmentation fractal dimensions can describe PSDs of soils in a single parameter. The objective of this research is to use mass-based fragmentation fractal dimension models to describe PSDs and evaluate the relationship between the fragmentation fractal dimension values (DF) and pedogenesis in loess-paleosol. Based on the theory of fragmentation fractal dimension, particle size data from 837 eolian loess samples from the lower part of Chaoyang section uniform loess deposits were analyzed with mass-based models using linear regression and piecewise linear regression. A single power-law exponent can characterize the PSDs across the domain of 0.1–54.4 μm. The trend of fragmentation fractal dimension values is consistent with chemical weathering indices, magnetic susceptibility, and DF2 (close to 2). The energy dissipation for fragmenting larger particles from coarse silt (CSI) to fine silt (FSI) is identified in the volume and for fragmenting smaller particles from fine silt (FSI) to clay (CL) it is substantially on the surface. This research indicated that fragmentation fractal model is a good descriptor for the PSDs and DF can be a value quantifying the intensity of loess-paleosol pedogenesis.

Anisotropy correction is necessary during the processing of converted PSwave seismic data to achieve accurate structural imaging, reservoir prediction, and fracture detection. To effectively eliminate the adverse effects of S-wave splitting and to improve PSwave imaging quality, we tested methods for pre-stack migration imaging and anisotropic correction of PS-wave data. We based this on the propagation rules of seismic waves in a horizontal transverse isotropy medium, which is a fractured medium model that reflects likely subsurface conditions in the field. We used the radial (R) and transverse (T) components of PS-wave data to separate the fast and slow S-wave components, after which their propagation moveout was effectively extracted. Meanwhile, corrections for the energies and propagation moveouts of the R and T components were implemented using mathematical rotation. The PS-wave imaging quality was distinctly improved, and we demonstrated the reliability of our methods through numerical simulations. Applying our methods to three-dimensional and three-component seismic field data from the Xinchang-Hexingchang region of the Western Sichuan Depression in China, we obtained high-quality seismic imaging with continuous reflection wave groups, distinct structural features, and specific stratigraphic contact relationships. This study provides an effective and reliable approach for data processing that will improve the exploration of complex, hidden lithologic gas reservoirs.

Little is known about how Fe-Mn nodules vary in relation to pedogenetic horizons in soils derived from loess. In this investigation nodules were collected according to soil genetic horizons from a Fragiudalf in loess at Southeast Purdue Agricultural Center (SEPAC) in Indiana and physical, chemical, micro- and macromorphological features of nodules and their soil matrix were determined as a function of soil depth. The quantity, chemical composition, and micromorphology of the nodules varied with genetic horizons. The Ap horizon was found to contain the largest amount by weight of nodules (25.43 g/kg) and this was likely due to soil erosion. After the Ap horizon, the 2Btx1 and 2Btx2 horizons had the greatest content of Fe-Mn nodules by weight. Nodules had lower concentrations of SiO2, Al2O3, K2O, TiO2, MgO, Na2O, and CaO; in contrast Fe2O3, MnO, and P2O5 in nodules showed clearly greater concentrations than that in the corresponding soil material. The SiO2 content decreased with nodule size whereas Fe2O3 and MnO increased. The least depletion of SiO2 in nodules of 1–2 mm (N2) and 0.5–1 mm (N1) was in the Bt2 horizon, and was greatest in the 2Btx2. The Al2O3 had accumulated in the N2 and N1 nodules within the Ap horizon and in the N2 within the 2Btx2 while other horizons were depleted of Al2O3. Brown nodules had a small Mn/Fe ratio ( 1). The internal morphology of the nodules also varied with Mn/Fe ratios. The fungal hyphae or bacteria resulted in honeycomb, cell, cone, or dendritic structures. The cell and cone morphology required large Mn/Fe ratios, low pH, and high content of Ald. The scanning electron microscopy (SEM) analysis illustrated an elemental distribution trend such that the Mn was centralized in the nodule internal structure; whereas, Fe was concentrated towards the exterior. The band structure of nodules likely formed in response to seasonal wetting and drying as an accretionary process. Three basic formation stages for a well developed nodule can be inferred which correspond to different soil forming environments: 1) Fe enrichment for nucleus formation in wet soil, 2) Mn enrichment in an intense dry soil, and 3) Fe banding enrichment in a slightly dry soil. Nodule formation occurred synchronously with soil pedogenesis and can therefore be used as a proxy for understanding soil pedogenesis and the environment under which it occurred.

Iron-manganese (Fe-Mn) concentrations are common morphological indicators of soil oxidation-reduction reactions and are widely used to infer soil hydrology. The factors determining occurrence and distribution of Fe-Mn concentrations at the continental scale have been rarely studied. The objective of this study was to explore the distribution of Fe-Mn concentrations in upland loess soils and identify their favorable environment conditions in the mid-continental North America. A total of 3966 soil profiles were collected from the National Soil Information System database (NASIS). A decision tree (DT) model was used to analyze the spatial relationships between Fe-Mn concentration formation and its relevant environmental factors (climate, soil properties, and land use/land cover), and to identify key factors of Fe-Mn concentrations distribution and occurrence in upland loess soils. The DT model was evaluated with 25% validation dataset with an accuracy of 79%. Results showed that Fe-Mn concentrations were more likely to occur in mesic areas with large precipitation and low internal soil drainage rates, compared to frigid and thermic areas with low precipitation and large internal soil drainage rates. Annual precipitation and temperature were identified as the most important climatic factors influencing the occurrence of Fe-Mn concentrations and showed a complex interaction with soil properties at multiple scales. Soil properties related to potential wet to saturated soil conditions were also important for the occurrence of Fe-Mn concentrations. Results demonstrated the importance of using knowledge of pedogenesis in the selection of environmental covariates and the interpretation of DT model results. Understanding where Fe-Mn concentrations tend to form in the landscape will contribute to improving decisions about proper use of soil that may be limited by wetness and possible inferences about climate influences.

Hydroxyapatite/collagen (HAP/Col) composite porous scaffolds have been extensively investigated in the field of bone tissue engineering due to their similar chemical composition to that of natural bone and good biocompatibility. However, the relatively poor mechanical properties of the HAP/Col composite porous scaffolds limit their application in bone regeneration. In order to overcome these limitations, the hierarchical porous ultralong hydroxyapatite nanowires (UHANWs)/collagen (Col) composite scaffolds with excellent mechanical properties are synthesized by freeze-drying the suspension containing UHANWs and collagen. Compared with the HAP nanorods (HANRs), the highly flexible UHANWs can interweave with each other to construct a three-dimensional fabric-like structure in the collagen matrix of the UHANWs/Col scaffolds and significantly improve the mechanical properties of the scaffolds. The Young's modulus of the 70 wt% UHANWs/Col scaffold is about 4 times that of the pure collagen scaffold and 63 times that of the 70 wt% HANRs/Col scaffold. More importantly, in the absence of the collagen matrix, the pure UHANWs inorganic porous scaffold can be synthesized and exhibits relative good mechanical properties. However, the HANRs/Col scaffolds with HANRs weight fractions more than 70 wt% are easily cracked during the fabrication process. Furthermore, compared with the pure collagen and 70 wt% HANRs/Col scaffolds, the 70 wt% UHANWs/Col scaffold exhibits a superior biocompatibility and excellent ability to promote cell adhesion and spreading on the surface of the scaffold. In consideration of their outstanding mechanical properties and excellent cellular attachment performance, the as-prepared hierarchical porous UHANWs/Col scaffolds are promising for applications in various biomedical fields such as bone defect repair.

Hydrogels with 3-dimentional cross-linked structures are widely used in various biomedical fields such as bone repair scaffolds, drug carriers and biosensors. However, the applications of hydrogels are usually restricted because of their poor mechanical properties. Currently, nanocomposites, double network systems, hydrophobic association, macromolecules, and nanoparticles are commonly adopted as cross-linking agents to enhance mechanical properties of hydrogels. In this work, ultralong hydroxyapatite nanowires (HANWs) with lengths of several hundred microns are prepared and used to enhance the mechanical properties of sodium alginate (SA)-based hydrogels. Using divalent calcium ions as the cross-linking agent, the hybrid HANWs/SA hydrogels containing various percentages of HANWs are obtained. The as-prepared HANWs/SA hybrid hydrogels have a porous structure with pore sizes ranging from about 200 to 500μm. The mechanical properties of SA hydrogels can be significantly improved by incorporating HANWs. The maximum compressive modulus (E50%) and tensile Young's modulus of the hybrid hydrogel (HANWs/SA=2:1) are as high as 0.123MPa and 0.994MPa, which are about 162% and 614% those of the pure SA hydrogel, respectively. Due to the enhanced mechanical properties and high biocompatibility, the as-prepared HANWs/SA hybrid hydrogels have promising applications in various biomedical fields such as bone defect repair.

High-strength flexible inorganic paper with fire-resistant and adiabatic properties is highly demanded in various high-temperature applications. However, constructing inorganic paper that not only has high strength and high flexibility at room temperature but also can prevent the high-temperature-induced friability is still a great challenge. Inspired by the hierarchical structure and excellent mechanical properties of the tooth enamel, we have developed a systematic approach for the bottom-up fabrication of multi-hierarchical fire-resistant hydroxyapatite (HAP) nanowire paper with balanced tensile strength and flexibility that includes four steps: (1) the synthesis of monodisperse HAP nanowires from the molecular level to the nanoscale; (2) the self-assembly of HAP nanowires into long fibers and two-dimensional (2D) nanowire networks from the nanoscale to the mesoscale; (3) the layered assembly of 2D nanowire networks into the highly flexible high-strength fire-resistant paper from the mesoscale to the macroscale; (4) reinforcing the HAP nanowire paper with inorganic additives to enhance the tensile strength and to overcome the high-temperature-induced pulverization. By adopting this strategy, the mechanical properties of the fire-resistant HAP nanowire paper are greatly improved. The experimental results show that the tensile strength of the as-prepared HAP nanowires-based inorganic paper is greatly enhanced to ≈15 MPa, which is close to that of the commercial copying paper, and the A4-sized HAP nanowires-based inorganic paper is highly flexible and can be directly printed using a commercial printer. Owing to the synergistic effect of all components and the unique hierarchical structure, the as-prepared fire-resistant HAP nanowire paper can also preserve well its high flexibility even under high-temperature conditions.

A nano-calcium peroxide (nCaO2) powder with a purity of 89.1% was prepared using an improved traditional method. Then, the as-prepared nCaO2 was used as the source of hydrogen peroxide (H2O2) for the Fenton-like degradation of diclofenac sodium (DCF). The results showed that nCaO2 performed better for DCF removal when compared to nCaO2 prepared by a conventional method and commercial calcium peroxide (CaO2). Further experimental results indicated that 97.5% of DCF could be removed in 180 min at a nCaO2/Fe2+-EDTA/DCF molar ratio of 16/8–8/1, which was more efficient than in the H2O2/EDTA-Fe2+/DCF and nCaO2/Fe2+/DCF systems. The best removal rate of DCF was at pH 6.0, unlike previous claims that stated that the lower the pH in the buffer system, the better the degradation of DCF. In addition, the influence of water quality parameters, such as Cl−, NO3−, SO42−, HCO3−, and humic acid (HA), on DCF removal were evaluated. A free radical masking experiment revealed the existence of hydroxyl radical ( OH), superoxide radical (O2− ) and singlet oxygen (1O2), and indicated that the degradation of DCF was mainly due to oxidation caused by OH. Electron paramagnetic resonance (EPR) studies for different systems and different active oxygen species were carried out, and it was further confirmed that OH radicals have high intensity in the Fenton-like system based on nCaO2. EPR results also showed that the addition of EDTA can promote the production of OH. According to the identification of the dominant reactive species and GC–MS, the possible theoretical DCF degradation pathways were proposed.

Tephra layers can serve as ideal datable horizons to provide invaluable datums for supplementing research on loess-paleosol sequences. The objective of this research was to evaluate a typical loess profile interbedded with a macroscopic tephra in northeastern China to better understand its formation to determine the potential impact of volcanism on climate change, as evidenced by loess pedogenesis. Geochemical and physical properties of the profile were determined and compared with loess materials from other areas to address its characteristics and potential significance for understanding climate variability. Results showed the tephra layers with overlying loess horizons were uniform in parent material, as inferred from evidence such as uniform Ti/Zr ratios with depth, similar rare earth element distribution patterns, and major elemental distributions with depth. The volcanic properties in the bottom of the profile, including morphology, high phosphate adsorption capacity (PAC) and pH (NaF) values, further supported the speculation that the depositions of aeolian dust and volcanic materials were synchronous with pedogenic processes. According to the comparison of magnetic susceptibility of the typical profile with the global δ18O curve, the local paleoclimate showed an increase in temperature in warmth and wetness, which may have been affected by volcanism. Research on the loess profile interbedded with a macroscopic tephra could improve our knowledge of loess formation and deepen our understanding of the impact of volcanism on climate changes.

For the first time, ultralong hydroxyapatite (HAP) nanowires with lengths longer than 200 μm are used to fabricate highly porous HAP ceramics using palmitic acid spheres as pore formers. The effects of the aspect ratio of HAP and the addition amount of palmitic acid spheres on the formation of HAP porous ceramics are investigated and compared with commercial HAP nanoparticles. The ultralong HAP nanowires can cross-link with each other, leading to much stronger interaction among HAP nanowires than HAP nanoparticles. During the sintering process, although palmitic acid spheres are decomposed at high temperatures, ultralong HAP nanowires can be well preserved and still support the whole porous structure stably, leading to the formation of highly porous HAP ceramics with high biocompatibility. The porosity of the HAP nanowire porous ceramics can be easily tuned. The as-prepared HAP nanowire porous ceramics exhibit good biocompatibility, good performance for cell adhesion and spreading, and cell proliferation. Thus, the as-prepared HAP nanowire porous ceramics are promising for applications in various biomedical fields.

In this paper, the one-step rapid synthesis of hydroxyapatite nanoflowers (HAFs) using creatine phosphate disodium salt as an organic phosphorus source by the sonochemical method is reported. The HAFs with diameters of about 300 nm are formed by self-assembly of hydroxyapatite nanosheets with thicknesses of less than 10 nm. The as-prepared samples are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) nitrogen sorptometry, X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and inductively coupled plasma (ICP) optical emission spectroscopy. The MTT tests show that the as-prepared HAFs exhibit essentially inappreciable toxicity to MC-3T3 osteoblast cells, indicating that the HAFs have an excellent cytocompatibility. Moreover, the as-prepared HAFs show a relatively high protein adsorption ability when using hemoglobin (Hb) as a model protein. Thus, the as-prepared HAFs are promising for applications in various biomedical fields such as protein/drug delivery.

With the growing popularity of electrical communication equipment, high-performance electromagnetic interference (EMI) shielding materials are widely used to deal with radiation pollution. However, the large thickness and poor mechanical properties of many EMI shielding materials usually limit their applications. In this study, ultrathin and highly flexible Ti3C2Tx (d-Ti3C2Tx, MXene)/cellulose nanofiber (CNF) composite paper with a nacre-like lamellar structure is fabricated via a vacuum-filtration-induced self-assembly process. By the interaction between one-dimensional (1D) CNFs and two-dimensional (2D) d-Ti3C2Tx MXene, the binary strengthening and toughening of the nacre-like d-Ti3C2Tx/CNF composite paper has been successfully achieved, leading to high tensile strength (up to 135.4 MPa) and fracture strain (up to 16.7%), as well as excellent folding endurance (up to 14 260 times). Moreover, the d-Ti3C2Tx/CNF composite paper exhibits high electrical conductivity (up to 739.4 S m–1) and excellent specifi...

Hydroxyapatite nanowires exhibit a great potential in biomedical applications owing to their high specific surface area, high flexibility, excellent mechanical properties, and similarity to mineralized collagen fibrils of natural bone. In this work, zinc-containing nanoparticle-decorated ultralong hydroxyapatite nanowires (Zn-UHANWs) with a hierarchical nanostructure have been synthesized by a one-step solvothermal method. The highly flexible Zn-UHANWs exhibit a hierarchical rough surface and enhanced specific surface area as compared with ultralong hydroxyapatite nanowires (UHANWs). To evaluate the potential application of Zn-UHANWs in bone regeneration, the biomimetic Zn-UHANWs/chitosan (CS) (Zn-UHANWs/CS) composite porous scaffold with 80 wt % Zn-UHANWs was prepared by incorporating Zn-UHANWs into the chitosan matrix by the freeze-drying process. The as-prepared Zn-UHANWs/CS composite porous scaffold exhibits enhanced mechanical properties, highly porous structure, and excellent water retention capacity. In addition, the Zn-UHANWs/CS porous scaffold has a good biodegradability with the sustainable release of Zn, Ca, and P elements in aqueous solution. More importantly, the Zn-UHANWs/CS porous scaffold can promote the osteogenic differentiation of rat bone marrow derived mesenchymal stem cells and facilitate in vivo bone regeneration as compared with the pure CS porous scaffold or UHANWs/CS porous scaffold. Thus, both the Zn-UHANWs and Zn-UHANWs/CS porous scaffold developed in this work are promising for application in bone defect repair.

Hydroxyapatite (HAP) with a porous hollow structure is an ideal biomaterial owing to its excellent biocompatibility and unique architecture. In this study, HAP nanorod-assembled porous hollow polyhedra, consisting of nanorod building blocks, have been successfully prepared at room temperature or under hydrothermal circumstances using a self-sacrificing Ca(OH)2 template strategy. The hydrothermal treatment (at 180°C for 1h) can promote the HAP nanorods to be arranged with their axial direction normal to the polyhedron surface. The HAP nanorod-assembled porous hollow polyhedra have been explored for the potential application in drug/protein delivery, using ibuprofen (IBU) as a model drug and hemoglobin (Hb) as a model protein. The experimental results indicate that the HAP nanorod-assembled porous hollow polyhedra have a relatively high drug loading capacity and protein adsorption ability, and sustained drug and protein release. The HAP nanorod-assembled porous hollow polyhedra have promising applications in various biomedical fields such as the drug and protein delivery.

In this work, monodisperse single-crystalline ultralong hydroxyapatite (HAP) microtubes have been successfully synthesized using a reaction system containing CaCl2, NaOH, (NaPO3)6, oleic acid, water and ethanol by a solvothermal method. The formation mechanism of HAP microtubes and the effects of solvothermal temperature, pH value, Ca/P molar ratio, and volume ratio of solvents on the product have been investigated. Due to the unique tubular structure, the as-prepared ultralong HAP microtubes exhibit high biocompatibility and superior properties in drug loading and sustained drug release. The as-prepared HAP microtubes are promising for applications in various biomedical fields such as drug/gene delivery and bone defect repair.