Search

Utilizing exciplex as host and fluorescence emitter as dopant materials has been proved successfully to fabricate highly-efficient organic light-emitting diodes (OLEDs). Exciton evolution and energy transfer in this exciplex host-guest system are complex. Gaining insight into the electroluminescence mechanisms in exciplex-based devices is key for further optimizing device configuration. Here, we have investigated exciton dynamics in devices with exciplex as host and 4-(Dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran (DCJTB) as red fluorescence emitter. Two exciplexes, 2,6-bis(3-(9H-carbazol-9-yl)phenyl)pyridine (26DCzPPY) doped 2,4,6-tris[3-(triphenylphosphine)phenyl]-1,3,5-triazine (POT2T), and 4,4′,4″-tris[3-methylphenyl(phenyl)amino]-triphenylamine (m-MTDATA) doped Tris(8-hydroxyquinoline)aluminum(III) (Alq3), with different band energy are utilized as host materials. Combining the measurements of transient electroluminescence, transient photoluminescence and magnetic field effect(MFE), it is concluded that Dexter energy transfer, together with Förster resonance energy transfer, are confirmed in pure fluorescence doped system. Meanwhile, it is found that DCJTB works with hot excitons mechanism but not a traditional red fluorescence emitter as recognized previously. This work presents that the transient MFE is powerful for detecting excitonic dynamic processes in excipelx based host-guest electroluminescence system.

The combination between biphasic calcium phosphate (BCP) and the osteomimetic porous micro-structure obtained via freeze casting is hoped to achieve excellent bone regeneration, while the effects of HA and β-TCP ratio changes on the degradation and biological performance of the BCP scaffolds with this unique micro-structure need to be determined. Here, we prepared the osteomimetic BCP scaffolds with different HA/β-TCP ratios (HA30/β-TCP70, HA50/β-TCP50, HA70/β-TCP30) and the effects of different HA/β-TCPHA/β-TCP ratios on the degradation and biological performance were studied in vitro and vivo. These BCP scaffolds with different HA/β-TCP ratios exhibited similar microstructure, mechanical performance, and protein absorption capability, while HA70/β-TCP30 BCP scaffolds showed an advisable degradation rate. Study in vitro confirmed the bio-compatibility and promotion on the proliferation, differentiation of MG63 cells in the porous osteomimetic BCP scaffolds with a HA/β-TCP ratio at 30:70. Implantation experiments also showed that the porous osteomimetic BCP scaffolds with a HA/β-TCP ratio at 30:70 had excellent bone regeneration capacity and proper degradation rate compatible with bone growth. These results reveal that the porous osteomimetic BCP scaffold with a HA/β-TCP ratio at 30:70 is a potential candidate of biodegradable bone substitutes used for bone repair.

The porous HA/BaTiO3 ceramics have the potential to exhibit superior capabilities to promote bone in-growth. However, there are few reports on in vivo studies. Here, we fabricated bio-inspired porous HA/BaTiO3 composites for bone repair via freeze-casting. These composites had a unique microstructure composed of the central canal and radically distributed lamellae, similar to the structure of nature cortical bone unite, the Haversian system. Polarized and non-polarized bio-inspired porous HA/BaTiO3 samples were implanted into the femoral condyle of the New Zealand rabbits. It was demonstrated that the polarization of the porous HA/BaTiO3 played a favorable part in bone regeneration. Moreover, the combination between the osteoconductivity of the microstructure and augmented osteogenic cell behavior induced by charges on surfaces of polarized porous HA/BaTiO3 facilitated bone penetration through the implants. The bio-inspired porous HA/BaTiO3 composites are demonstrated to be promising scaffolds for bone repair. 多孔HA/BaTiO3陶瓷具有促进骨再生的潜在能力。本研究通过冷冻冰模法制备了一种仿生多孔HA/BaTiO3复合骨支架材料,这种仿生多孔结构由中央管和呈放射状分布的层板组成,这与天然致密骨结构单位—哈弗系统相似。在植入实验中,极化和非极化的多孔HA/BaTiO3样本被植入新西兰兔的股骨髁。结果显示:多孔HA/BaTiO3的电极化处理促进了骨再生;极化多孔HA/BaTiO3表面的电荷增强了成骨细胞的成骨活动,这与具有良好骨传导性的仿生多孔结构共同实现了骨组织对支架材料的穿透。本研究证明了仿生多孔HA/BaTiO3复合材料有希望用作骨修复支架。

For high corrosion resistance and extensively modified biodegradable Mg-based alloys and composites for bone implants, a new Mg-based matrix model prepared by powder metallurgy is discussed and developed. In this research, Mg-5 wt.%Zn alloys were selected as a case. And they were impacted by hot extrusion and aging treatments to construct microstructure with different characteristics. Their self-forming corrosion product layer in Ringer's solution, biodegradable behavior and corrosion mechanism were minutely investigated by in vitro degradation, electrochemical corrosion and cytocompatibility. The results demonstrated the extruded Mg-5 wt.%Zn alloy aged for 96 h showed high corrosion resistance, good biocompatibility for L929 and excellent ability of maintaining sample integrity during the immersion. Significantly, the alloy showed fine-grain microstructure and uniform distributed hundred nano-sized second phases, which promoted the formation of the uniform and smooth corrosion product layer at the beginning of immersion. The corrosion product layer was more stable in chloride containing aqueous solution and could be directly formed and repaired quickly, which effectively protected the matrix from further corrosion. In addition, an ideal model of Mg-based matrix for bone tissue engineering was tried to presume and propose by discussing the causal relationship between microstructure and bio-corrosion process.

Manipulating the molecular orbital properties of excited states and the subsequent relaxation processes can greatly alter the emission behaviors of luminophores. Herein we report a vivid example of this, with luminescence conversion from thermally activated delayed fluorescence (TADF) to ultralong room-temperature phosphorescence (URTP) via a facile substituent effect on a rigid benzothiazino phenothiazine tetraoxide (BTPO) core. Pristine BTPO with multiple heteroatoms shows obvious intramolecular charge transfer (ICT) excited states with small exchange energy, featuring TADF. Via delicately functionalizing the BTPO core with peripheral moieties, the excited states of the BTPO derivatives become a hybridized local and charge transfer (HLCT) state in the S1 state and a local excitation (LE) dominated HLCT state in the T1 state, with enlarged energy bandgaps. Upon dispersion in a polymer matrix, the BTPO derivatives exhibit a persistent bright green afterglow with long lifetimes of up to 822 ms and decent quantum yields of up to 11.6%., The decoration of a BTPO core results in a change in the luminescence nature from TADF to URTP. The phosphors in an amorphous PMMA matrix showed monomeric URTP with phosphorescence lifetimes of up to 822 ms and quantum yields of up to 11.6%.

The effects of surface-modified porous titanium implants with different porosities and pore sizes on osseointegration were investigated in vivo. Three porous titanium implants (A30, A40 and A50 containing volume fractions of space-holder NaCl being 30%, 40% and 50%, respectively) were manufactured by metal injection moulding (MIM). The surface-modified implants were implanted into muscles and femurs of hybrid male dogs. Interface osteogenic activity and histological bone ingrowth of porous titanium implants were evaluated at 28, 56 and 84 d. The results showed that when additive space-holder amount of NaCl increased from 30% to 50% (volume fraction), the general porosity and mass fraction of macropores of porous titanium rose from 42.4% to 62.0% and from 8.3% to 69.3%, respectively. Histologic sections and fluorescent labeling showed that the A50 implant demonstrated a significantly higher osteogenic capacity at 28 d than other implants. Bone ingrowth into the A30 implant was lower than that into other implants at 84 d. Therefore, the pore structure of A50 implant was suitable for new bone tissue to grow into porous implant.

In order to develop a biodegradable guided bone regeneration membrane with the required mechanical properties and high corrosion resistance, Zn-0.8%Li(wt), Zn-0.8%Li-0.2%Mg(wt), and Zn-0.8%Li-0.2%Ag(wt) alloys were cast and hot rolled into 0.1-mm thick sheets. The main secondary phase in Zn-0.8%Li-(Mg, Ag) alloys was the LiZn4 nanoprecipitate. Following the addition of minimal amounts of Mg, the tensile strength of the Zn-0.8%Li-0.2%Mg alloy improved, albeit with a greatly reduced elongation and corrosion resistance. The addition of minimal amounts of Ag refined the microstructure, producing fine equiaxed grains (2.3 μm) in the Zn-0.8%Li-0.2%Ag alloy, and promoted a uniform distribution of LiZn4 nanoprecipitates with increased density and refined size. Therefore, the Zn-0.8%Li-0.2%Ag alloy exhibited optimal tensile strength and the highest corrosion resistance, with its elongation reaching 97.9 ± 8.7%. The corrosion products of Zn-0.8%Li-(Mg, Ag) alloys immersed in Ringer's solution for 35 days mainly consisted of zinc oxide and zinc carbonate. In addition, the cytotoxicity test using L929 cells and the evaluation of bone marrow mesenchymal stem cell proliferation indicated that the Zn-0.8%Li-0.2%Ag alloy had good biocompatibility.

Pure Zn and Zn-0.5%Li(wt) alloys were cast and extruded into the rods in this study. The micro structure and mechanical properties of Zn, Zn-0.5%Li and its mini tube were evaluated. With the addition of Li, both the UTS and elongation of extruded Zn-0.5%Li alloy increases to 364.9 MPa and 22% compared with Zn. The mini tube made of Zn-0.5%Li alloy shows the UTS of 296.2 MPa and elongation of 33%. The main strengthening mechanism of Zn-Li alloy is attribute to the pinning effects caused by nano LiZn4 precipitates. In conclusion, Zn-Li mini tube could be considered as potential absorbable stent material.

Osseointegration between implants and bone tissue lays the foundation for the long-term stability of implants. The incorporation of a porous structure and local slow release of siRNA to silence casein kinase-2 interacting protein-1 (CKIP-1), a downregulator of bone formation, is expected to promote osseointegration. Here, porous implants with a porous outer layer and dense inner core were prepared by metal coinjection molding (MIM). Mg-doped calcium phosphate nanoparticles (CaPNPs)-grafted arginine-glycine-aspartate cell adhesion sequence (RGD) and transcribed activator (TAT) (MCPRT)/CKIP-1 siRNA complex and polylysine (PLL) were coated onto the surface of the porous implants by layer-by-layer (LBL) self-deposition. The in vitro results showed that the MCPRT-siRNA coating promoted MG63 cell adhesion and proliferation, enhanced the protein expressions (ALP and OC) and bone formation-related gene expression (OPN, OC and COL-1α) in vitro. The in vivo results demonstrated that the porous structure enhanced bone ingrowth and that the local slow release of MCPRT-siRNA accelerated new bone formation at the early stage. The porous structure coupled with local CKIP-1 siRNA delivery constitutes a promising approach to achieve faster and stronger osseointegration for dental implants.

Background: Compared to commonly-used green space indicators from downward-facing satellite imagery, street view-based green space may capture different types of green space and represent how environments are perceived and experienced by people on the ground, which is important to elucidate the underlying mechanisms linking green space and health. Objectives: This study aimed to evaluate machine learning models that can classify the type of vegetation (i.e., tree, low-lying vegetation, grass) from street view images; and to investigate the associations between street green space and socioeconomic (SES) factors, in Los Angeles County, California. Methods: SES variables were obtained from the CalEnviroScreen3.0 dataset. Microsoft Bing Maps images in conjunction with deep learning were used to measure total and types of street view green space, which were compared to normalized difference vegetation index (NDVI) as commonly-used satellite-based green space measure. Generalized linear mixed model was used to examine associations between green space and census tract SES, adjusting for population density and rural/urban status. Results: The accuracy of the deep learning model was high with 92.5% mean intersection over union. NDVI were moderately correlated with total street view-based green space and tree, and weakly correlated with low-lying vegetation and grass. Total and three types of green space showed significant negative associations with neighborhood SES. The percentage of total green space decreased by 2.62 [95% confidence interval (CI): −3.02, −2.21, p < 0.001] with each interquartile range increase in CalEnviroScreen3.0 score. Disadvantaged communities contained approximately 5% less average street green space than other communities. Conclusion: Street view imagery coupled with deep learning approach can accurately and efficiently measure eye-level street green space and distinguish vegetation types. In Los Angeles County, disadvantaged communities had substantively less street green space. Governments and urban planners need to consider the type and visibility of street green space from pedestrian's perspective.

Estimating 3D hand poses from a single RGB image is challenging because depth ambiguity leads the problem ill-posed. Training hand pose estimators with 3D hand mesh annotations and multi-view images often results in significant performance gains. However, existing multi-view datasets are relatively small with hand joints annotated by off-the-shelf trackers or automated through model predictions, both of which may be inaccurate and can introduce biases. Collecting a large-scale multi-view 3D hand pose images with accurate mesh and joint annotations is valuable but strenuous. In this paper, we design a spin match algorithm that enables a rigid mesh model matching with any target mesh ground truth. Based on the match algorithm, we propose an efficient pipeline to generate a large-scale multi-view hand mesh (MVHM) dataset with accurate 3D hand mesh and joint labels. We further present a multi-view hand pose estimation approach to verify that training a hand pose estimator with our generated dataset greatly enhances the performance. Experimental results show that our approach achieves the performance of 0.990 in $\text{AUC}_{\text{20-50}}$ on the MHP dataset compared to the previous state-of-the-art of 0.939 on this dataset. Our datasset is public available. \footnote{\url{https://github.com/Kuzphi/MVHM}} Our datasset is available at~\href{https://github.com/Kuzphi/MVHM}{\color{blue}{https://github.com/Kuzphi/MVHM}}.

Estimating 3D hand poses from RGB images is essential to a wide range of potential applications, but is challenging owing to substantial ambiguity in the inference of depth information from RGB images. State-of-the-art estimators address this problem by regularizing 3D hand pose estimation models during training to enforce the consistency between the predicted 3D poses and the ground-truth depth maps. However, these estimators rely on both RGB images and the paired depth maps during training. In this study, we propose a conditional generative adversarial network (GAN) model, called Depth-image Guided GAN (DGGAN), to generate realistic depth maps conditioned on the input RGB image, and use the synthesized depth maps to regularize the 3D hand pose estimation model, therefore eliminating the need for ground-truth depth maps. Experimental results on multiple benchmark datasets show that the synthesized depth maps produced by DGGAN are quite effective in regularizing the pose estimation model, yielding new state-of-the-art results in estimation accuracy, notably reducing the mean 3D endpoint errors (EPE) by 4.7%, 16.5%, and 6.8% on the RHD, STB and MHP datasets, respectively.

Osteosarcoma is the most common primary malignant tumor, especially in children and adolescents. Circular RNAs (circRNAs) are found to play roles in the progression of osteosarcoma. However, the exact functions of circRNAs in osteosarcoma development still need to be clarified. We obtained differentially expressed circRNAs and miRNAs from a GSE99671 data set (GEO database). The gene co-expression network of ceRNAs and osteosarcoma-related genes was analyzed using the STRING database. qRT-PCR was used to detect the expression of circ-03955 and miR-3662. Transwell assays and flow cytometry were performed to detect phenotypic changes in cell function. A xenograft tumor model was established using BALB/c nude mice. Dual luciferase activity and RNA immunoprecipitation assays were performed to assess the relationship between circ-03955, miR-3662, and metadherin (MTDH). Immunohistochemistry, immunofluorescence, and Western blotting were used to assess protein expression levels. Circ-03955 was significantly upregulated, and miR-3662 was downregulated in osteosarcoma. Circ-03955 silencing inhibited the growth and metastasis of osteosarcoma. Mechanism analysis revealed that circ-03955 could bind to miR-3662, and the latter could target MTDH, leading to its suppressed expression and facilitating epithelial-mesenchymal transition (EMT). All these findings demonstrate that the presence of circ-03955 promotes EMT in osteosarcoma by acting as miR-3662 sponge-mediated MTDH expression.

Estimating the 3D hand pose from a monocular RGB image is important but challenging. A solution is training on large-scale RGB hand images with accurate 3D hand keypoint annotations. However, it is too expensive in practice. Instead, we develop a learning-based approach to synthesize realistic, diverse, and 3D pose-preserving hand images under the guidance of 3D pose information. We propose a 3D-aware multi-modal guided hand generative network (MM-Hand), together with a novel geometry-based curriculum learning strategy. Our extensive experimental results demonstrate that the 3D-annotated images generated by MM-Hand qualitatively and quantitatively outperform existing options. Moreover, the augmented data can consistently improve the quantitative performance of the state-of-the-art 3D hand pose estimators on two benchmark datasets. The code will be available at https://github.com/ScottHoang/mm-hand.

Hot excitons have been attempted to utilize the triplet excitons in organic light-emitting diodes (OLEDs). Due to the transient and dark nature of high-lying triplet states (Tn, n ≥ 2), the normative methods to characterize the hot exciton mechanism have not been thoroughly developed. Here, a normal technique combining transient photoluminescence and magneto-electroluminescence (MEL) measurements has been proven to visualize the reverse intersystem crossing process from T2 to S1 states in 5,6,11,12-tetraphenylnaphthacene (rubrene) molecules. Rubrene is chosen as a model system since its T1 is far below S1 and T2 is resonant with S1. This hot exciton process opens an additional route, marked as Dexter energy transfer channel ([Formula: see text], DET channel), together with the well-known Förster resonance energy transfer channel ([Formula: see text]) to transfer the host energy to the guest. With proper approximates, the DET channel assisted by the hot excitons process can contribute about 46.6% excitons to rubrene S1 and 83.4% rubrene emission in rubrene-doped devices. These studies set an in situ normative characterizing frame to visualize the hot excitons process in OLEDs.

The development of an efficient, robust, and low-cost catalyst for water electrolysis is critically important for renewable energy conversion. Herein, we achieve a significant improvement in electrocatalytic activity for both the oxygen-evolution reaction (OER) and the hydrogen-evolution reaction (HER) by constructing a novel hierarchical PrBa0.5Sr0.5Co2O5+δ (PBSC)@FeOOH catalyst. The optimized PBSC@FeOOH-20 catalyst consisted of layered perovskite PBSC nanorods and 20 nm thick amorphous FeOOH nanoflakes exhibiting an excellent electrocatalytic activity for the OER and the HER in 0.1 M KOH media, delivering a current density of 10 mA cm-2 at overpotentials of 390 mV for the OER and 280 mV for the HER, respectively. The substantially enhanced performance is probably attributed to the hierarchical nanostructure, the good charge-transfer capability, and the strong electronic interactions of FeOOH and PBSC. Importantly, an alkaline electrolyzer-integrated PBSC@FeOOH-20 catalyst as both the anode and cathode shows a highly active overall water splitting with a low voltage of 1.638 V at 10 mA cm-2 and high stability during continuous operation. This study provides new insights into exploring efficient bifunctional catalysts for overall water splitting, and it suggests that the rational design of the oxyhydroxide/perovskite heterostructure shows great potential as a promising type of electrocatalysts.

Osteoblasts growing into bone substitute is an important step of bone regeneration. This study prepared porous hydroxyapatite (HA)/BaTiO3 piezoelectric composites with porosity of 40%, 50% and 60% by ice-templating method. Effects of HA/BaTiO3 composites with different porosities, with and without polarizing treatment on adhesion, proliferation and differentiation of osteoblasts were investigated in vitro. Results revealed that cell densities of the porous groups were significantly higher than those of the dense group (p0.05), so did the alkaline phosphate (ALP) and bone gla protein (BGP) activities. Porosity of 50% group exhibited higher ALP activity and BGP activity than those of the 40% and 60% groups. Scanning electron microscopy (SEM) observations revealed that osteoblasts adhered and stretched better on porous HA/BaTiO3 than on the dense one, especially HA/BaTiO3 with porosity of 50% and 60%. However, there was no significant difference in the cell morphology, cell densities, ALP and BGP activities between the polarized group and the non-polarized group (p0.05). The absence of mechanical loading on the polarized samples may account for this. The results indicated that hierarchically porous HA/BaTiO3 played a favorable part in osteoblasts proliferation, differentiation and adhesion process and is a promising bone substitute material.

Mg-6%Zn-10%Ca 3 (PO 4 ) 2 composite was prepared through powder metallurgy methods with polycaprolactone(PCL) coating on its surface. The properties of the PCL coatings on the surface of Mg-6%Zn-10%Ca 3 (PO 4 ) 2 composite, such as surface morphology, the corrosion behavior and the cytotoxicity properties were investigated. The results show that PCL coating improves the corrosion resistance of the magnesium matrix composite specimens significantly. Mg-6%Zn-10%Ca 3 (PO 4 ) 2 composite specimens with PCL coating exhibit good corrosion resistance and low pH values in SBF at 37 °C in the immersion test, as compared with uncoated specimens. The cytotoxicity tests indicate Mg-6%Zn-10%Ca 3 (PO 4 ) 2 with PCL coating is nontoxic with higher relative growth rate than that of uncoated composites against L-929 cells.

Rolled Zn-0.8Li-0.2Ag(wt%) alloy as candidates for biodegradable materials. The biodegradable behavior of Zn-0.8Li-0.2Ag alloy in different solutions (Ringer’s, DMEM, SBF and DMEMp) was investigated. The cytotoxicity of Zn-0.8Li-0.2Ag alloy and its antibacterial properties against staphylococcus aureus, enterobacter faecalis and candida albicans were evaluated. The results showed that Zn-0.8Li-0.2Ag alloy consists of zinc matrix and a LiZn4 secondary phase. The presence of Cl− causes locally corroded of Zn-0.8Li-0.2Ag alloy in Ringer’s solution, and its corrosion resistance is lower than that of the alloy which is uniformly corroded in other solutions containing CO3 2− and PO4 3−. Zn-0.8Li-0.2Ag alloy is non-toxic and exhibits better antibacterial properties than the experimental reference group without silver.

The development of an efficient, robust, and low-cost catalyst for water electrolysis is critically important for renewable energy conversion. Herein, we achieve a significant improvement in electrocatalytic activity for both the oxygen-evolution reaction (OER) and the hydrogen-evolution reaction (HER) by constructing a novel hierarchical PrBa

Porous titanium with porosity of 60% was prepared by metal injection molding (MIM), and coated with gelatin sustained-release microspheres which were made by improved emulsified cold condensation method. The effects of porous titanium coated with insulin-like growth factor-1 (IGF-1) and transforming growth factor-β1 (TGF-β1) gelatin microspheres on the function of MG63 cells were evaluated in vitro. The results show that porous titanium coated with gelatin sustained-release microspheres has no cytotoxicity. The IGF-1 and TGF-β1 loading concentrations are positively correlative with the proliferation and differentiation of MG63 after co-culturing with the concentrations of IGF-1 and TGF-β1 gelatin microspheres in the range of 0.1–10 ng/mg and 0.25–2.5 ng/mg, respectively. The MG63 cells exhibit the best proliferation and differentiation with the IGF-1 and TGF-β1 loading concentrations of 10 ng/mg and 2.5 ng/mg, respectively. The joint application of IGF-1 and TGF-β1 group, which promote adhesion, proliferation and differentiation of MG63 cells, is superior to a single application group.

Mg-6%Zn-10%β-Ca3(PO4)2 composite was prepared through powder metallurgy methods with different chitosan coatings on its surface. The properties of the chitosan coatings on the surface of Mg-6%Zn-10%β-Ca3(PO4)2 composite, such as the adhesion ability, the corrosion behavior and the cytotoxicity properties, were investigated, and the microstructure of the chitosan coating was observed by scanning electron microscope (SEM). The results show that chitosan coating improves the corrosion resistance of the magnesium composite specimens significantly. Mg-6%Zn-10%β-Ca3(PO4)2 composite specimens exhibit good corrosion resistance and low pH values in simulated body fluid (SBF) at 37 °C in the immersion test with 7-layer chitosan coating whose relative molecular mass is 30×104 Da. The cytotoxicity tests indicate that Mg-6%Zn-10%β-Ca3(PO4)2 with chitosan coating is nontoxic with a cytotoxicity grade of zero against L-929 cells, which is better than that of uncoated composites.

A Mg–6%Zn–10%Ca 3 (PO 4 ) 2 composite with a chitosan coating was prepared to study its in vivo biodegradation properties. The chitosan dissolved in a 0.2% acetic acid solution was applied on the surface of Mg–6%Zn–10%Ca 3 (PO 4 ) 2 composite specimens and solidified at 60 °C for 30 min to form the coating. The cytotoxicity evaluation of chitosan coated specimens is at level 0, which indicates that such coating is safe for cellular applications. The in vivo tests of chitosan coated composite show that the concentration of metal ions from the composite measured in the venous blood of Zelanian rabbits is less than that from the uncoated composite specimens. The chitosan coating impedes the in vivo degradation of the composite after surgery. The in vivo testing also indicates that the chitosan coated composite is harmless to important visceral organs, including the heart, kidneys and liver of the rabbits. The new bone formation surrounding the chitosan coated composite implant shows that the composite improves the concrescence of the bone tissues. And the chitosan coating is an effective corrosion resistant layer that reduces the hydrogen release of the implant composite, thereby decreasing the subcutaneous gas bubbles formed.

It was proposed that the piezoelectric effect played an important physiological role in bone growth, remodelling and fracture healing. An aligned porous piezoelectric composite scaffold was fabricated by freeze casting hydroxyapatite/barium titanate (HA/BT) suspensions. The highest compressive strength and lowest porosity of 14.5MPa and 57.4% with the best parallelism of the pore channels were achieved in the HA10/BT90 composite. HA30/BT70 and HA10/BT90 composites exhibited piezoelectric coefficient d33 of 1.2 and 2.8pC/N, respectively, both of which were higher than the piezoelectric coefficient of natural bone. Increase of the solid loading of the suspension and solidification velocity led to the improvement of piezoelectric coefficient d33. Meanwhile, double-templates resulted in the coexistence of lamellar pores and aligned macro-pores, exhibiting the ability to produce an oriented long-range ordered architecture. The manipulation flexibility of this method indicated the potential for customized needs in the application of bone substitute. An MTT assay indicated that the obtained scaffolds had no cytotoxic effects on L929 cells.

A Mg-6%Zn-15%Ca 3 (PO 4 ) 2 composite is produced through powder metallurgy method in this study to investigate it’s in vivo biocompatibility and biodegradation in Zelanian rabbits. The metal ion concentrations in the rabbit blood are detected and the muscle, heart, liver and kidneys tissues are inspected for histomorphology analysis. The composite is implanted and fastened with the rabbit's pre-broken femoral shaft to observe the biodegradation process. The results show that The Mg 2+ , Zn 2+ , Ca 2+ ions are in the normal range in the animal's blood during the whole experiment period. All the tissues are normal during the composite degradation process, which indicates the composite exhibits good biocompatibility to these visceral organs. The biodegradation of composite is benefit to stimulate the bone formation around the pre-fracture.

SUMMARY Design of prosthetic implants to ensure rapid and stable osseointegration remains a significant challenge, and continuous efforts have been directed to new implant materials, structures and morphology. This paper aims to develop and characterise a porous titanium dental implant fabricated by metallic powder injection-moulding. The surface morphology of the specimens was first examined with a scanning electron microscope (SEM), followed by microscopic computerised tomography (μ-CT) scanning to capture its 3D microscopic features non-destructively. The nature of porosity and pore sizes were determined statistically. A homogenisation technique based on the Hills-energy theorem was adopted to evaluate its directional elastic moduli, and the conservation of mass theorem was employed to quantify the oxygen diffusivity for bio-transportation feature. This porous medium was found to have pore sizes varying from 50 to 400 µm and the average porosity of 46.90 ± 1.83%. The anisotropic principal elastic moduli were found fairly close to the upper range of cortical bone, and the directional diffusivities could potentially enable radial osseous tissue ingrowth and vascularisation. This porous titanium successfully reduces the elastic modulus mismatch between implant and bone for dental and orthopaedic applications, and provides improved capacity for transporting oxygen, nutrient and waste for pre-vascular network formation. Copyright © 2016 John Wiley & Sons, Ltd.

The purpose of this study is to investigate the mechanical properties of Mg–6%Zn–Ca3(PO4)2 composite and evaluate its biodegradable behavior in Ringer's solution. The Mg–6%Zn alloy with 5%, 10% and 15% addition of Ca3(PO4)2 as reinforcements are produced through a powder-metallurgy sinter method and their corrosion properties are tested. The results show that the mechanical properties of the Mg–6%Zn–Ca3(PO4)2 composites are adjustable by the addition and particle distributions of Ca3(PO4)2. The Mg–6%Zn–5%, 10%Ca3(PO4)2 composites obtain properties including density, Young's modulus, and strength similar to natural bone. The Mg matrix, Mg7Zn3 phase, and Ca3(PO4)2 are identified in the experimental composite. Immersion and electrochemical corrosion tests reveal that 5% and 10% addition of Ca3(PO4)2 particles in the Mg–6%Zn alloy exhibit acceptable corrosion resistance in Ringer's solution.