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Magnesium (Mg) and its alloys are promising biodegradable materials for orthopedic applications. However, one of the major problems is their rapid degradation rate with quick evolution of hydrogen gas. To overcome this problem, calcium phosphate (CaP) coatings have been used to improve the degradation resistance and the biocompatibility of Mg materials. This study focuses on the comparison and correlation of the in vitro and in vivo degradation and biocompatibility behaviors of these materials. A CaP coating consisting of dicalcium phosphate dihydrate (DCPD) was deposited on an AZ60 Mg alloy by the chemical conversion method. Then, the in vitro degradation testing including electrochemical and immersion tests, and in vivo implantation of the CaP coated Mg alloy were conducted to compare the degradation behaviors. Next, the in vitro cell behavior and in vivo bone tissue response were also compared on both uncoated and CaP-coated Mg samples. Data showed that the CaP coating provided the Mg alloy with significantly better biodegradation behavior and biocompatibility. The in vitro and in vivo biocompatibility tests exhibited good consistency while not the case for biodegradation. Results showed that the in vitro electrochemical test could be a quick screening tool for the biodegradation rate, while the in vitro immersion degradation rate was often 2-4 folds faster than the in vivo degradation rate.

Poly(styrene-b-isobutylene-b-styrene) triblock copolymer (SIBS), a kind of thermoplastic elastomer with biocompatibility and biostability containing fully saturated soft segments, could be synthesized via living cationic copolymerization. A novel poly[(styrene-co-methylstyrene)-b-isobutylene-b-(styrene-co-methylstyrene)]-g-polytetrahydrofuran (M-SIBS-g-PTHF) block graft copolymer was prepared to increase the polarity and service temperature of SIBS by grafting polar PTHF segments onto SIBS. A series of the above block graft copolymers with average grafting numbers from 2 to 6 and molecular weights of PTHF branches ranging from 200 g·mol−1 to 4200 g·mol−1 were successfully synthesized via living cationic ring-opening polymerization of tetrahydrofuran (THF) coinitiated by AgClO4. The introduction of PTHF branches led to an obvious microphase separation due to thermodynamic incompatibility among the three kinds of segments of polyisobutylene (PIB), polystyrene (PS) and PTHF. Moreover, the microphase separation promotes the rearrangement of PTHF branches to form the nanocrystallization-locked physically cross-linked network after storage at room temperature for 2 months, leading to insolubility of the copolymers even in good solvents. The melting temperature and enthalpy of PTHF nanocrystallization locked in hard domains of M-SIBS-g5-PTHF-1.1k block graft copolymer increased remarkably up to 153 °C and 117.0 J·g−1 by 23 °C and 11.6 J·g−1 respectively after storage for long time. Storage modulus (G′) is higher than loss modulus (G″) of M-SIBS-g-PTHF block graft copolymer at temperatures ranging from 100 °C to 180 °C, which is much higher than those of the SIBS triblock copolymer. To the best of our knowledge, this is the first example of high performance M-SIBS-g-PTHF block graft copolymers containing segments of PIB, PS and PTHF with nanocrystallization-locked architecture.

Creep aging behavior of retrogression and re-aged (RRAed) 7150 aluminum alloy (AA7150) was systematically investigated using the creep aging experiments, mechanical properties tests, electrical conductivity tests and transmission electron microscope (TEM) observations. Creep aging results show that the steady-state creep mechanism of RRAed alloys is mainly dislocation climb (stress exponent≈5.8), which is insensitive to the grain interior and boundary precipitates. However, the total creep deformation increases over the re-aging time. In addition, the yield strength and tensile strength of the four RRAed samples are essentially the same after creep aging at 140 °C for 16 h, but the elongation decreases slightly with the re-aging time. What's more, the retrogression and re-aging treatment are beneficial to increase the hardness and electrical conductivity of the creep-aged 7150 aluminum alloy. It can be concluded that the retrogression and re-aging treatment before creep aging forming process can improve the microstructure within grain and at grain boundary, forming efficiency and comprehensive performance of mechanical properties and electrical conductivity of 7150 aluminum alloy.

In order to quantify the poroelastic mechanical signals conduction and evaluate the biomechanical effectiveness of functional units (osteocyte processes, canaliculi and lacuna) in lacunar-canalicular system (LCS), a multiscale poroelastic finite element model was established by using the Comsol Multiphysics software. The poroelastic mechanical signals (pore pressure, fluid velocity, von-Mises stress, strain) were analyzed inside the osteon-osteocyte system. The effects of osteocyte (OCY)’s shape (ellipse and circle), long axis directions (horizontal and vertical) and mechanical properties (Elastic modulus and permeability) on its poroelastic responses were examined. It is found that the OCY processes is the best mechanosensor compared with the OCY body, lacunae and canaliculi. The mechanotransduction ability of the elliptic shaped OCY is stronger than that of circular shaped. The pore pressure and flow velocity around OCYs increase as the elastic modulus and permeability of OCY increase. The established model can be used for studying the mechanism of bone mechanotransduction at the multiscale level.

Organic solar cells are used in low-cost solar energy applications. Recently, organo-lead halide perovskite solar cells have attracted considerable interest. Low-temperature spin-coating is the simplest method to fabricate the low-cost solar cells; however, forming a continuous perovskite film by spin coating a precursor solution of lead iodide (PbI2) and methylammonium iodide (CH3NH3I) is challenging. This work investigated the characteristics of perovskite thin film, prepared using dimethylformamide (DMF) and dimethyl sulfoxide (DMSO)/γ-butyrolactone (GBL) solvents in the direct mixing of PbI2 and CH3NH3I. Perovskite films prepared using the DMSO/GBL solvent had greater crystallinity and compactness than those using the DMF solvent. Cell performance was improved by a perovskite absorber using the DMSO/GBL solvent to a power conversion efficiency of 8.87%, an open-circuit voltage of 0.82 V, a current density of 17.13 mA/cm2, and a fill factor of 63.01%.

The silicone rubber mold (SRM) has large applications for the pilot runs in the mold industry because it is capable of reducing the cost and time in a new product development phase. However, the cooling performance in the cooling stage is not acceptable after the injection molding due to low thermal conductivity of this material. To improve the cooling performance, five different fillers were added into the silicone rubber (SR) to develop SRM with better cooling performance in the cooling stage after injection molding. It was found that the alcohol used to remove the polyvinyl butyral resin cooling channels is less volatile, environmentally friendly, and less harmful to the operator compared with conventional method using acetone to remove the acrylonitrile butadiene styrene cooling channels. The cooling time of the molded wax pattern can be saved by 42.7%, 53.8%, 45.7%, 50.9%, and 16.7% for SRM with 60 wt.% Al, 80 wt.% Fe, 70 wt.% Cu, 25 wt.% graphite (G), and 20 wt.% carbon black powders compared with that for SRM without any fillers. The SR filled with 20 wt.% G powder seems to be the optimal method for producing an SRM with better cooling performance based on the heat transfer coefficient, production cost, and production yield of SRM.

Thermoplastic polyurethane (TPU) elastomers based on polyoxytetramethylene glycol (PTMG) with 2000 g·mol–1 as soft segments (SSs) and isocyanates as well as their reaction with butanediol as hard segments (HSs) were synthesized. The three-dimensional supramolecular networks were constructed in TPU by the formation of physical HSs-rich domains via microphase separation, hydrogen bonding, and microcrystallization, which are dominated by the chemical structure of HSs. The robust stretchable TPU with an excellent tensile strength of 32 MPa and elongation of 1378% at break could be successfully prepared, and no crystallization happened to keep the elasticity even at a low temperature (−90 °C) when the steric semisymmetric bis(4-isocyanatocyclohexyl)methane (HMDI) was introduced into HSs-rich domains. The crystallinity and ordered hydrogen bonding content decreased in HSs-rich domains with increases in steric hindrance and asymmetry of diisocyanates. A new approach was developed to construct the high-performanc...

In this study, a novel renewable double-energy system, coupling activated biochar production and thermoelectric generation, is conducted and demonstrated. In the installed 13 thermoelectric modules...

Background Bone is a hierarchically structured composite material, and different hierarchical levels exhibit diverse material properties and functions. The stress and strain distribution and fluid flow in bone play an important role in the realization of mechanotransduction and bone remodeling. Methods To investigate the mechanotransduction and fluid behaviors in loaded bone, a multiscale method was developed. Based on poroelastic theory, we established the theoretical and FE model of a segment bone to provide basis for researching more complex bone model. The COMSOL Multiphysics software was used to establish different scales of bone models, and the properties of mechanical and fluid behaviors in each scale were investigated. Results FE results correlated very well with analytical in macroscopic scale, and the results for the mesoscopic models were about less than 2% different compared to that in the macro–mesoscale models, verifying the correctness of the modeling. In macro–mesoscale, results demonstrated that variations in fluid pressure (FP), fluid velocity (FV), von Mises stress (VMS), and maximum principal strain (MPS) in the position of endosteum, periosteum, osteon, and interstitial bone and these variations can be considerable (up to 10, 8, 4 and 3.5 times difference in maximum FP, FV, VMS, and MPS between the highest and the lowest regions, respectively). With the changing of Young’s modulus (E) in each osteon lamella, the strain and stress concentration occurred in different positions and given rise to microscale spatial variations in the fluid pressure field. The heterogeneous distribution of lacunar–canalicular permeability (klcp) in each osteon lamella had various influence on the FP and FV, but had little effect on VMS and MPS. Conclusion Based on the idealized model presented in this article, the presence of endosteum and periosteum has an important influence on the fluid flow in bone. With the hypothetical parameter values in osteon lamellae, the bone material parameters have effect on the propagation of stress and fluid flow in bone. The model can also incorporate alternative material parameters obtained from different individuals. The suggested method is expected to provide dependable biological information for better understanding the bone mechanotransduction and signal transduction.

Sodium alginate (SA) is a marine-derived biocompatible polysaccharide with huge reserves and polyisobutylene (PIB) is a saturated elastomer with gas barrier property, bio-inertness, and biocompatibility. Herein, we developed the biomass-based ASA-g-(THF5-b-PIB) graft copolymer/Ag (3–11 nm, 0.7–3.8%) nanocomposites formed in-situ via combination of transition of terminal groups in PIB chains with grafting-onto method. The above graft copolymers exhibit microphase separation by self-assembly for the difference in chemical structure from backbone and branches and annealing process as well. The crystallization morphology from backbone depends on the Mn,PIB and GN, changing from thin strip to rod-like crystal. The pH sensitivity happens in drug release behavior of ASA-g-(THF5-b-PIB) micelles, which reach 100% of drug-release within 40 h at pH = 7.4. The ASA-g-(THF5-b-PIB)/Ag composites behave good antibacterial properties to both E. coli and S. aureus and anti-protein adsorption performance. This novel graft copolymer with comprehensive properties and would have a prospect in biomedical field.

A novel robust quaternized poly(styrene-b-isobutylene-b-styrene) (QSIBS)-based anion exchange membrane (AEM) could be achieved via quaternization and cross-linking reaction of chloromethylated SIBS with amines in the presence of graphene sheets grafted with polydimethylsiloxane arc-bridges (G-g-Arc PDMS). The resulting cross-linked QSIBS/G-g-Arc PDMS composite membranes exhibit significantly high ion conductivity (σ) and dynamic mechanical properties, marked by low methanol permeability, together with improved chemical stability. The σ of composite AEM with 0.25 wt% of graphene loading reached remarkably to 1.81 × 10−2 S cm−1 at 60 °C, compared to that (1.15 × 10−2 S cm−1) of QSIBS. This membrane also behaves high storage modulus of 236 MPa even at 150 °C, while Nafion 115 lost its modulus at 150 °C. The homogeneous dispersion of G-g-Arc PDMS in QSIBS matrix leads to a great decrease in methanol permeability to 3.81 × 10−7 cm2 s−1, which is much lower than that of Nafion 115.

Material properties of a thermoelectric generator play a pivotal role in directly converting heat into electricity. To provide a comprehensive study on power generation of thermoelectric generators, four different materials with constant and temperature-dependent properties are investigated numerically. The influences of the temperature difference across the elements, the temperature at the cold side surface, and the temperature oscillation at the hot side surface on the performance of the generators are simulated numerically and analyzed systematically. The predictions indicate that the output power, temperature-difference square rule, and impedance matching of the materials with the variable properties deviate from the theoretical results with constant properties, but their behavior always obeys the self-consistency. At a given temperature difference, a decrease in the cold surface temperature may intensify or abate the performance, depending on the material properties adopted. Oscillating the hot surface temperature may increase or decrease the output power and efficiency. In summary, the practical performance of a thermoelectric generator and its deviation from the theoretical performance depend strongly on the properties adopted. Therefore, the consideration of the variable properties of materials can provide a more realistic outcome compared to the predictions with constant properties.

Thermoelectric generators (TEGs) are a promising device to harvest waste heat for power generation. Three material properties of TEGs, including the Seebeck coefficient, electrical resistivity, and thermal conductivity, are often considered as constants in the simulation. However, the performance of TEGs changes with different temperature. In this study, the performances, such as output power and efficiency of one constant property material and three temperature-dependent property materials are investigated numerically. The influences of the temperature difference, the temperature at the cold side surface, and current on the performance of the TEGs are analyzed. The predictions indicate that the output power of the TEGs deviate from the formula when their properties are temperature-dependent. In other words, the output power of the TEGs is not directly proportional to the temperature difference squared. The simulations also satisfy the result of self-consistency. In the case of the fixed temperature difference of 100 oC, when the temperature at cold side surface is lower, different performances of TEG are followed by different materials. The results also tell that one material whose ZT value increases with the rise in temperature has a similar trend in output power and efficiency to the constant-property material. However, another material that has the maximum value in the ZT curve has different trend in output power and efficiency from those of the constant-property material.

Zn-based biomaterials have emerged as promising new types of bioresorbable metallics applicable to orthopedic devices, cardiovascular stents, and other medical applications recently. Compared to other degradable metallic biomaterials (i.e., Mg- or Fe-based), Zn biomaterials have a more appropriate corrosion rate without hydrogen gas evolution. Here, we evaluated the potential of Zn-based metallics as medical implants, both in vitro and in vivo, alongside a standard benchmark Mg alloy, AZ31. The mechanical properties of the pure Zn were not strong enough but were significantly enhanced (microhardness > 70 kg/mm2, strength > 220 MPa, elongation > 15%) after alloying with Sr or Mg (1.5 at. %), surpassing the minimal design criteria for load-bearing device applications. The corrosion rate of Zn-based biomaterials was about 0.4 mm/year, significantly slower than that of AZ31. The measured cell viability and proliferation of three different human primary cells fared better for Zn-based biomaterials than AZ31 us...

In this paper, a fluorescent and antibacterial nanocomposite film based on Zinc sulphide (ZnS) quantum dots, cellulose nanocrystals (CNCs) and polyvinyl alcohol (PVA) was successfully synthesized. CNCs were first decorated in situ with ZnS quantum dots, which were then introduced into a PVA matrix to prepare nanocomposite films with good fluorescent and antibacterial properties. The X-ray diffraction and scanning electron microscope analysis indicated that ZnS nanoparticles were well-dispersed and randomly coated on the CNCs with uniform particle size. The visible emission peak in the ZnS/CNCs nanocomposites was 473 nm with an excitation wavelength of 350 nm. The CNCs loaded with ZnS quantum dots exhibited bright blue fluorescence under the ultraviolet light. Additionally, CNCs/ZnS nanocomposite films also had good antibacterial properties (bacterial inhibition rate = 78.25%).

It has been demonstrated that articular facet degeneration can cause local strain alterations and induce neck pain. This study aims to quantify the biomechanical effects of normal and degenerated C5-C6 articular facets, and evaluate the correlation of mechanical strain between healthy and degenerated spine. A 3-dimensional finite element (FE) model of the C5-C6 cervical spine was developed [Model 0 (M0)]. The asymmetric models of C5-C6 bilateral articular facet joint were established separately to mimic articular facet joint degeneration. The capsule ligament stiffness of C5-C6 unilateral facet joint was altered with minimum and maximum threshold to simulate capsule ligaments' lesion and calcification [Model 1 (M1) and Model 2 (M2), respectively]. Besides, the cervical C5-C6 unilateral articular facet joint direction was changed by 5° and 10° forward to imitate the moderate joint hyperplasia and severe osteophyte (Model 3 and Model 4 respectively). M1 increased the rotation range of ipsilateral side (left), while M2 reduced, and both had limited effect on the contralateral side (right). The angle increased in Model 3 (M3) (61°) and Model 4 (M4) (55°) comparing to M0 during the axial rotation, and the angle of M4 was larger. M3 and M4 increased the nucleus pulposus pressure with and without controlled angular displacement during axial rotation. The pressure of nucleus pulpous increased during M1 rotating to the abnormal side but decreased when rotating to the other side, but the results of M2 were opposite. The capsule ligament stiffness made an impact on segmental mobility and vertebral spatial position, and the sagittal angle of articular facet joint exerted an influence on disc pressure distribution.

Thermoplastic polyurethanes (TPUs) and other elastomers are widely used in many applications for the advantages they provide in terms of high elasticity, lightness, resistance to breakage, and impact resistance. These materials exhibit strong hysteresis in the large strain stress-strain behavior, known as cyclic softening or the Mullins effect. Despite the extensive studies on this phenomenon and the importance of Poisson’s ratio, how the Poisson’s ratio of these materials changes during cyclic uniaxial tests is still unclear. Here, we measure the nonlinear Poisson’s ratio of TPU and investigate its correlation with cyclic softening using two-dimensional digital image correlation (2D-DIC) combined with the reference sample compensation (RSC) method. This accuracy-enhanced method can effectively eliminate the measurement errors induced by the unavoidable out-of-plane displacements and lens distortion. We find that the Poisson’s ratio of TPUs also exhibits large hysteresis in the first cycle and then approaches a steady state in subsequent cycles. Specifically, it starts from a relatively low value of 0.45 ± 0.005 in the first loading, then increases to 0.48 ± 0.005 in the first unloading, and remains largely constant afterward. Such a change in the Poisson’s ratio results in a slight volume increase (≈1%) at a maximum strain of 17.5%. Our findings are useful for those who use finite element method to analyze the mechanical behavior of TPU, and shed new light on understanding the physical origin of cyclic softening.

As advanced semiconductor device features shrinking with each technology node, copper interconnect structures shows more importance effect because of the higher electrical conductivity and electro migration resistance of copper. Co /Ta/TaN novel metals are being introduced as barrier materials for advanced technology node. These types of materials enable cu filling of the narrowest structures and act as seed enhancement layers. However, it is difficult to solve the compatibility of the interconnect metals for copper chemical mechanical polishing process (CMP). Metal void and copper corrosion issues need to be controlled especially. The wet chemical environment in CMP process caused copper corrosion to be one of the critical issues for copper layer. This paper shows that by optimizing the copper CMP polish condition and cleaner condition has addressed the two types of copper corrosion, as copper chemical corrosion and galvanic corrosion. The failure analyses for how to identify the root causes and differentiate the corrosion have been discussed in details.

It has great significance to develop a convenient and efficient method for hydrogels with adjustable electric and magnetic properties, which can be used in human activity monitoring and personal healthcare diagnosis field. However, it is a big challenge to balance the relationship between the conductive and magnetic categories so that electromagnetic hydrogels could be developed by an in-situ fabrication way. In this work, we firstly proposed a sequential in-situ route to form polypyrrole (PPy) and Fe3O4 nanoparticles (Fe3O4 NPs) in sequence within polyvinyl alcohol (PVA) matrix for the hybrid hydrogels with decent mechanical, conductive, and magnetic properties simultaneously, named as Fe3O4/PPy/PVA hydrogel. The as-prepared hybrid hydrogels exhibited continuous electrons transporting path and magnetic responsive properties. Specifically, a unique combination of high electrical conductivity (up to 1.95 ± 0.17 E−4 S cm−1), saturation magnetization (5.42 emu g−1) and greatly enhanced mechanical properties (tensile strength up to 575.03 ± 28.32 kPa, elasticity modulus up to 461.19 ± 24.75 kPa). More importantly, these hybrid hydrogels demonstrated potential applications in biomedical electronic devices, such as strain sensors and magnetic navigators.

To achieve the local, as well as global, planarity of the wafer surface many innovative technologies have been developed. A robust Cu chemical mechanical polishing (CMP) process with better post CMP polishing profile, smooth copper surface, tighten metal line sheet resistance (Rs) and pattern loading control has been evaluated during the Cu CMP process at 14nm and beyond. It is well known that CMP causes pattern loading of a layer to be planarized due to uneven distribution of device structures and thus reducing the effectiveness of this technology. This paper will present how to improve pattern loading and dishing control with optimized polish methodology. Experiment results shown that there is no loading between dense line area and ISO line area, and better dishing performance.

The novel amphiphilic acylated dextran-g-polytetrahydrofuran (AcyDex-g-PTHF) graft copolymers have been successfully synthesized via combination of living cationic ring-opening polymerization of tetrahydrofuran (THF) to prepare living PTHF chains with different molecular weights (Mn, PTHF) of 800–2800 g/mol with nucleophile substitution to mediate grafting numbers (GN) of 4–25 per 1000 Dex monosaccharide. The microphase separation in the graft copolymer exists for the incompatibility of hard dextran backbone and soft PTHF branches and the confined crystallization of backbone. This copolymer behaves excellent hemocompatibility with red blood cells, good biocompatibility with HeLa cells and strong resistance to bovine serum albumin adsorption. The microspheres (~1 μm) of graft copolymers loaded with drug ibuprofen exhibit pH sensitive controlled drug release behavior. Moreover, the AcyDex-g-PTHF/Ag nanocomposites show good antibacterial property against E. coli and S. aureus. This novel hemocompatible, biocompatible and antifouling AcyDex-g-PTHF graft copolymer will have potential application in biological and medical fields.

The nucleus pulposus (NP) in the intervertebral disk (IVD) depends on diffusive fluid transport for nutrients through the cartilage endplate (CEP). Disruption in fluid exchange of the NP is considered a cause of IVD degeneration. Furthermore, CEP calcification and sclerosis are hypothesized to restrict fluid flow between the NP and CEP by decreasing permeability and porosity of the CEP matrix. We performed a finite element analysis of an L3–L4 lumbar functional spine unit with poro-elastic constitutive equations. The aim of the study was to predict changes in the solid and fluid parameters of the IVD and CEP under structural changes in CEP. A compressive load of 500 N was applied followed by a 10 Nm moment in extension, flexion, lateral bending, and axial rotation to the L3–L4 model with fully saturated IVD, CEP, and cancellous bone. A healthy case of L3–L4 physiology was then compared to two cases of CEP sclerosis: a calcified cartilage endplate and a fluid constricted sclerotic cartilage endplate. Predicted NP fluid velocity increased for the calcified CEP and decreased for the calcified + less permeable CEP. Decreased NP fluid velocity was prominent in the axial direction through the CEP due to a less permeable path available for fluid flux. Fluid pressure and maximum principal stress in the NP were predicted to increase in both cases of CEP sclerosis compared to the healthy case. The porous medium predictions of this analysis agree with the hypothesis that CEP sclerosis decreases fluid flow out of the NP, builds up fluid pressure in the NP, and increases the stress concentrations in the NP solid matrix.

As a degradable metal, zinc (Zn) has attracted an immense amount of interest as the next generation of bioresorbable implants thanks to its modest corrosion rate and its vital role in bone remodeling, yet very few studies have thoroughly investigated its functionality as a porous implant for bone tissue engineering purposes. Zn bone scaffolds with two different pore sizes of 900 μm and 2 mm were fabricated using additive manufacturing-produced templates combined with casting. The compressive properties, corrosion rates, biocompatibility, and antibacterial performance of the bioscaffolds were examined and compared to a non-porous control. The resulting textured and porous Zn scaffolds exhibit a fully interconnected pore structure with precise control over topology. As pore size and porosity increased, mechanical strength decreased, and corrosion rate accelerated. Cell adhesion and growth on scaffolds were enhanced after an ex vivo pretreatment method. In vitro cellular tests confirmed good biocompatibility of the scaffolds. As porosity increased, potent antibacterial rates were also observed. Taken together, these results demonstrate that Zn porous bone scaffolds are promising for orthopedic applications.

Polyolefin materials, such as polyethylene, polypropylene, polyisobutene, ethylene-propylene rubber and isobutene rubber, play important roles in the industry and our daily life. Polyolefin materials with high performance, various microstructure, sequence distribution and topological structure could be prepared by controlled polymerization of olefin. We summarized the recent work on ethylene/propylene coordination copolymerization and isobutene cationic polymerization to prepare ethylene-propylene rubber, isobutene rubber and polyisobutene. The design and synthesis of Ziegler-Natta vanadium catalysts, half-titanocene catalysts and single-site vanadium catalyst and their application for ethylene/propylene copolymerization were introduced. The novel initiating system for the controlled/living cationic polymerizations, transformation of polymerization character, cationic polymerization in aqueous medium with high efficiency, cationic polymerization in rotating packed bed reactor were developed. The macromolecular engineering based on the controlled polymerization of olefin was also introduced.

The purpose of this work is to introduce a new method for quantitatively analyzing water absorption capacity in wheat flour by a headspace gas chromatographic technique. This headspace gas chromatographic technique was based on measuring the water vapor released from a series of wheat flour samples with different contents of water addition. According to the different trends between the vapor and wheat flour phase before and after the water absorption capacity in wheat flour, a turning point (corresponding to water absorption capacity in wheat flour) can be obtained by fitting the data of the water gas chromatography peak area from different wheat flour samples. The data showed that the phase equilibrium in the vial can be achieved in 25 min at desired temperature (35°C). The relative standard deviation of the reaction headspace gas chromatographic technique in water absorption capacity determination was within 3.48%, the relative differences has been determined by comparing the water absorption capacity obtained from this new analytical technique with the data from the reference technique (i.e., the filtration method), which are less than 8.92%. The new headspace gas chromatographic method is automated, accurate and be a reliable tool for quantifying water absorption capacity in wheat flour in both laboratory research and mill applications.

Grafting single end-tethered polymer chains on the surface of graphene is a conventional way to modify the surface properties of graphene oxide. However, grafting arc-like macromolecular bridges on graphene surfaces has been barely reported. Herein, a novel arc-like polydimethylsiloxane (PDMS) macromolecular bridges grafted graphene sheets (GO-g-Arc PDMS) was successfully synthesized via a confined interface reaction at 90 °C. Both the hydrophilic α- and ω-amino groups of linear hydrophobic NH2-PDMS-NH2 macromolecular chains rapidly reacted with epoxy and carboxyl groups on the surfaces of graphene oxide in water suspension to form arc-like PDMS macromolecular bridges on graphene sheets. The grafting density of arc-like PDMS bridges on graphene sheets can reach up to 0.80 mmol g−1 or 1.32 arc-like bridges per nm2 by this confined interface reaction. The water contact angle (WCA) of the hybrid membrane could be increased with increasing both the grafting density and content of covalent arc-like bridges architecture. The superhydrophobic hybrid membrane with a WCA of 153.4° was prepared by grinding of the above arc-like PDMS bridges grafted graphene hybrid, dispersing in ethanol and filtrating by organic filter membrane. This superhydrophobic hybrid membrane shows good self-cleaning and complete oil-water separation properties, which provides potential applications in anticontamination coating and oil-water separation. To the best of our knowledge, this is the first report on the synthesis of functional hybrid membranes by grafting arc-like PDMS macromolecular bridges on graphene sheets via a confined interface reaction.

A two-step fabrication process combining emulsification-solvent evaporation method for encapsulation of drug in PLGA microparticles followed by supercritical gas foaming was developed to produce drug-releasing biodegradable micro-porous foams. The encapsulation and release of model hydrophobic drug (Curcumin) and of model hydrophilic drug (Gentamicin) were investigated in this work. By utilizing a two-step fabrication process, a uniform dispersion of the drug in PLGA polymer matrix can be achieved and the method can be further adapted for the encapsulation of a wide range of active ingredient (both hydrophobic and hydrophilic) in biodegradable micro-porous scaffold. The in vitro release profile of the drug-encapsulated PLGA foam was studied over a period of 2 weeks and it was observed that the drug release profile can be engineered by the selection of different PLGA polymer blend, varying lactic to glycolic ratio and molecular chain length of the polymer, and by addition of compatible biodegradable polymer such as Polyethylene Glycol (PEG) to the polymer matrix.

Effects of friction stir spot processing (FSSP) on the microstructures and microhardness of tungsten inert gas (TIG) welded TA15 titanium alloy joints were investigated. The macro/micro structural observation and microhardness evaluation of the TA15 alloy sheets and TA15 TIG welded joints were carried out using optical microscope and microhardness tests. The results show that FSSP effectively improves the microstructure and increases the microhardness of the TA15 sheets. As for the TIG welded joints, FSSP also effectively improves the microstructure of joints. And the average microhardness value in weld nugget zone is improved significantly, while a small increase of this value in heat affected zone is observed. The hardness in stirring zone is significantly higher than that in the base metal. Two peak values of hardness appear along the width direction in stirring zone. After FSSP, the average hardness of the weld zone of TA15 TIG welded joint is significantly higher than that before FSSP. Under the present process parameters, both the surface oxidation in TA15 sheets and in TIG welded joints after FSSP are not evident, while the surface forms the bright white layer, which is composed of a great multitude of fine grains.

Introducing graphene into polymer matrix is an effective way to enhance performances of anion exchange membrane (AEM). However, utilizing the advantages of graphene by physical approach is limited due to the weak interface interaction between graphene and polymer matrix. Herein, we report an effective strategy to covalently bond graphene with polymer matrix to improve the interface interaction and further to improve the properties of AEM. A series of cross-linked quaternized graphene-based hybrid AEM were fabricated by covalently bonding poly (vinylbenzyl chloride) grafted graphene (GN-g-PVBC) copolymer with chloromethyl functionalized poly (styrene-b-isobutylene-b-styrene) (SIBS) through the cross-linker (N,N,N′,N′-tetramethyl-1,6-hexanediamine) by in-situ synthetic approach. The interface interaction between graphene and QSIBS is greatly enhanced according to micromorphology characterization of the hybrid membrane. The cross-linked quaternized hybrid AEM containing 0.55 wt% of GN-g-PVBC exhibits obviously improved dynamical mechanical properties (storage modulus: 418 MPa), ion conductivity (1.81 × 102 S cm−1), methanol barrier property (5.19 × 10−7 cm2 s−1), selectivity (3.49 × 104 S s cm−3) at 60 °C and especially a comparably excellent chemical stability to that of Nafion 115 due to the enhanced interface interaction between graphene and the polymer matrix.

This work aims to explore the concentration-dependence of SPIO-Au core-shell nanoscale particles (NPs) (17.3 ± 1.2 nm in diameter) on biocompatibility and osteogenic differentiation of preosteoblast MC3T3-E1 cells. The stability of NPs was first investigated by UV-vis absorption spectra and zeta potential measurement. Then concentration effects of NPs (1-80 μg/mL) were evaluated on viability, morphology, proliferation, cellular uptake, and alkaline phosphate (ALP) activity levels. Results have shown strong stability and no acute toxicity (viability > 93%) or morphological difference at all concentration levels of NPs. The proliferation results indicated that the concentration of NPs below 40 μg/mL does not affect the cell proliferation for 7 days of incubation. Transmission electron microscopy images revealed the successful internalization of NPs into MC3T3-E1 cells and the dose-dependent accumulation of NPs inside the cytoplasm. The ALP level of MC3T3-E1 cells was improved by 49% (of control) after treated with NPs at 10 μg/mL for 10 days, indicating their positive effect on early osteogenic differentiation. This study confirmed the excellent biocompatibility of SPIO-Au NPs and their great potential for promoting osteogenic differentiation and promised the future application for these NPs in bone engineering including drug delivery, cell labeling, and activity tracking within scaffolds. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3350-3359, 2017.

Two- and three-dimensional assemblies of carbon nanomaterials such as carbon nanotubes and graphene are necessary to harness their remarkable physicochemical properties in many clean energy, electronics, and biomedical applications. Herein we report a facile, economical, and versatile method for layer-by-layer fabrication of chemically-crosslinked carbon nanomaterial assemblies by ultrasonic spray coating combined with radical-initiated crosslinking reaction. The chemical, surface, and mechanical properties of the carbon nanomaterial coatings were characterized by Raman spectroscopy, atomic force microscopy, scanning- and transmission-electron microscopy, and nano-dynamic mechanical analysis. Our results indicate that the macroscopic 2D assemblies of crosslinked carbon nanotubes or graphene nanoparticles have surface uniformity, are chemically-crosslinked, and are mechanically robust. We further provide proof-of-concept demonstration of fabricating free-standing, porous, 3D single-walled carbon nanotube structures. Taken together, the results opens avenues toward adapting our method to enable 3D printing or additive manufacturing of all-carbon nanomaterial structures.

In order to obtain high-temperature resistant thermoplastic elastomers (TPEs), we designed and synthesized a new kind of ABA triblock copolymer containing a mesogen-jacketed liquid crystalline polymer, poly(4′-(methoxy)-2-vinylbiphenyl-4-methyl ether) (PMVBP), as the hard blocks and polybutadiene (PB) as the soft block. PB was synthesized by ring-opening metathesis polymerization in the presence of a chain transfer agent, and PMVBP was synthesized by nitroxide-mediated radical polymerization. The glass transition temperature of the PMVBP block is 186–211 °C, which is much higher than that of polystyrene. More importantly, PMVBP can maintain its liquid crystallinity even when the temperature is as high as 270 °C, which can enhance the mechanical properties of TPEs based on PMVBP, especially at high temperatures. All the resulting PMVBP-PB-PMVBP triblock copolymer samples form lamellar microphase-separated structures after combined treatment of solvent annealing and thermal annealing. They are good candidates for TPEs with a high operating temperature of more than 200 °C.

Age forming is an advanced manufacture technology for forming large aluminum panels. Temperature, initial stress level and pre-strains have a great effect on the formability and performance. The stress relaxation aging behavior of AA7150-T7751 under different temperatures, initial stress levels and pre-strains was studied through stress relaxation tests, tensile tests and TEM observations. The results show that the formability can be improved with the increase of temperature, initial stress levels and pre-strains. Deformation mechanisms during stress relaxation of the material were analyzed on the basis of creep stress exponent and apparent activation energy. The aging precipitates of the studied alloy were not sensitive to the age forming conditions, but drastically coarsened at over aging temperature, which decreased the mechanical properties. In addition, the relationship between stress relaxation behavior and aging strengthening is discussed. Based on the dislocation theory and the modified Arrhenius equation, a stress relaxation constitutive equation considering the initial mobile dislocation density and temperature dependent activation energy was established. This model can predict very well the stress relaxation behavior under various temperature, stress level and pre-strain conditions, with an average error of 2%.

Metallic materials have been extensively applied in clinical practice due to their unique mechanical properties and durability. Recent years have witnessed broad interests and advances on surface functionalization of metallic implants for high-performance biofunctions. Calcium phosphates (CaPs) are the major inorganic component of bone tissues, and thus owning inherent biocompatibility and osseointegration properties. As such, they have been widely used in clinical orthopedics and dentistry. The new emergence of surface functionalization on metallic implants with CaP coatings shows promise for a combination of mechanical properties from metals and various biofunctions from CaPs. This review provides a brief summary of state-of-art of surface biofunctionalization on implantable metals by CaP coatings. We first glance over different types of CaPs with their coating methods and in vitro and in vivo performances, and then give insight into the representative biofunctions, i.e. osteointegration, corrosion resistance and biodegradation control, and antibacterial property, provided by CaP coatings for metallic implant materials., Graphical abstract Image 1, Highlights • Discussions on the various biofunctions of CaP coatings. • Summary of different types of CaPs and their recent development. • Summary of CaP coating methods and selection criteria.

Recently, artificial intelligence has driven the development of shape memory hydrogels (SMHs) with complicated environmental sensitive abilities. However, current SMHs possess fundamental limitations in terms of their responsive performance and mechanical properties, which severely limits their practical applications. Herein, a triple-network composite hydrogel with Fe3+, NIR light, and thermal responsive abilities is fabricated and developed as multi-SMHs, named as PDA/CMC-Fe3+/PVA hydrogel. In this hydrogel system, the interpenetrating triple network are formed by chemically-physically co-crosslinked polyvinyl alcohol (PVA) networks, and physically crosslinked carboxymethyl cellulose (CMC)-Fe3+ network. In addition, polydopamine (PDA), which is introduced into the hydrogel system by in-situ polymerization way, could not only serve as an energy converter to endow the hydrogel with NIR-based responsive ability, but also enhance its mechanical strength. Remarkably, the as-prepared PDA/CMC-Fe3+/PVA hydrogels with the optimized compositions exhibit relatively excellent mechanical properties (tensile strength = 163.48 ± 10.42 kPa, elastic modulus = 45.42 ± 3.96 kPa, toughness = 165.02 ± 7.01 kJ/m3) due to the synergistic effect of the triple-network and PDA doping. Moreover, the composition of the hydrogel is optimized to realize a stable temporary shape and rapid recovery to the permanent shape, which is controlled by Fe3+, NIR irradiation, and thermal stimulus. The resultant hydrogels exhibit not only multi-stimulus responsive abilities, but also programmable multi-shape memory properties. The versatile shape memory properties endow potential for the materials to be used in the field of artificial intelligence.

We performed dynamic Monte Carlo simulations of strain-induced crystallization of homopolymer and random copolymers under cyclic loading of strains. We found that since the second loading random copolymers shift down the onset strain of crystallization and raise up the crystallinity, in contrast to homopolymer. We attributed the strong memory to the remaining of sequence-length segregation raised by copolymer crystallization during the first loading of strains. The mechanism is consistent with that for the strong memory of copolymer crystallization under cyclic cooling, as revealed by previous experiments and simulations. Our results showed a new effect of chain-sequence defects on the cyclic loading performance of rubbers.

Core–shell structure nanoparticles are attracting considerable attention because of their applications in drug delivery, catalysis carrier, and nanomedicine. In this study, SiO 2 @SiO 2 core–shell structure with tunable void and shell thickness was successfully prepared for the first time using SiO 2 -poly(buty acrylate) (PBA)-poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) (SiO 2 -PBA- b -PDMAEMA) as the template and tetraethoxysilane (TEOS) as the silica source. An amphiphilic copolymer PBA- b -PDMAEMA was first grafted onto the SiO 2 nanosphere surface through activators regenerated by electron transfer for atom transfer radical polymerization. TEOS was hydrolyzed along with the PDMAEMA chain through hydrogen bonding, and the core–shell structure of SiO 2 @SiO 2 was obtained through calcination to remove the copolymer. The gradient hydrophilicity of the PBA- b -PDMAEMA copolymer template facilitated the hydrolysis of TEOS molecules along the PDMAEMA to PBA segments, thereby tuning the voids between the SiO 2 core and SiO 2 shell, as well as the SiO 2 shell thickness. The voids were about 10–15 nm and the shell thicknesses were about 4–11 nm when adding different amounts of DMAEMA monomer. SiO 2 @SiO 2 core–shell structures with tunable void and shell thickness were employed as supports for the loading and release of doxorubicin hydrochloride (DOX) in PBS (pH 4.0). The samples demonstrated good loading capacity and controlled release rate of DOX.

This paper presents an improved strategy for synthesizing short rod-shaped mesoporous SiO2@TiO2 composites containing a TiO2 shell by using short rod-shaped mesoporous SiO2–polyglycidyl methacrylate (PGMA)–polyoligo(ethylene glycol)methyl ether methacrylate (PEGMA) as a template and tetrabutyl titanate (TBT) as a titanium source. SiO2–PGMA-b-PEGMA rods were initially fabricated through grafting GMA and EGMA onto the surface of the halogen functional group of mesoporous SiO2 using activators regenerated by electron transfer-atom transfer radical polymerization. TBT was hydrolyzed with the PEGMA chain through hydrogen bonding. The rod-shaped mesoporous SiO2@TiO2 structure was finally acquired through calcination. Characterization results indicated that the amphiphilic block copolymer was grafted onto the mesoporous SiO2 surface. Moreover, the TiO2 samples existed only in the anatase phase, and the prepared SiO2@TiO2 exhibited bimodal nanoporous structures. The synthesized short rod-shaped mesoporous SiO2@TiO2 materials demonstrated higher specific surface area and absorption rate than samples prepared from non-mesoporous or unmodified rod-shaped SiO2. These characteristics effectively enhanced the photocatalytic activity of the composite. The photocatalytic activity of the fabricated composite was then tested on rhodamine B photodegradation.

To harvest waste heat from flue gas in the industry, this study develops an advanced simulation technology by integrating computational fluid dynamics (CFD) and a thermoelectric module (TEM) where the TEM is modeled as a heat sink to absorb waste heat from flue gases. The influences of Reynolds number, convection heat transfer coefficient at the cold surface, flue gas inlet temperature, dual TEM, and channel geometry on the performance of the TEM system are evaluated. The results clearly provide a measure in increasing the performance of TEM with rising the Reynolds number, flue gas inlet temperature, and convection heat transfer coefficient at the cold surface. In the dual TEM system, the performance of the leading TEM is very close to that of the single TEM, and the dual TEM can produce an additional 43% power when compared with the single TEM. However, this also implies that the output power of the trailing TEM drops 57% when compared to the leading one, stemming for its impact upon the downstream TEM. When the channel geometry is modified to raise the flue gas velocity at Re = 1,000, the output power and efficiency increase by 53.5% and 25.2%, respectively.

A cardiovascular stent is a small mesh tube that expands a narrowed or blocked coronary artery. Unfortunately, current stents, regardless metallic or polymeric, still largely fall short to the ideal clinical needs due to late restenosis, thrombosis and other clinical complications. Nonetheless, metallic stents are preferred clinically thanks to their superior mechanical property and radiopacity to their polymeric counterparts. The emergence of bioresorbable metals opens a window for better stent materials as they may have the potential to reduce or eliminate late restenosis and thrombosis. In fact, some bioresorbable magnesium (Mg)-based stents have obtained regulatory approval or under trials with mixed clinical outcomes. Some major issues with Mg include the too rapid degradation rate and late restenosis. To mitigate these problems, bioresorbable zinc (Zn)-based stent materials are being developed lately with the more suitable degradation rate and better biocompatibility. The past decades have witnessed the unprecedented evolution of metallic stent materials from first generation represented by stainless steel (SS), to second generation represented by Mg, and to third generation represented by Zn. To further elucidate their pros and cons as metallic stent materials, we systematically evaluated their performances in vitro and in vivo through direct side-by-side comparisons. Our results demonstrated that tailored Zn-based material with proper configurations could be a promising candidate for a better stent material in the future.

We investigated how the stability of aqueous argon surface nanobubbles on hydrophobic surfaces depends on gas adsorption, solid-gas interaction energy, and the bulk gas concentration using molecular dynamics simulation with the SPC/E water solvent. We observed stable surface nanobubbles without surface pinning sites for longer than 160 ns, contrary to previous findings using monoatomic Lennard-Jones solvent. In addition, the hydrophobicity of a substrate has an effect to reduce the requirement degree of oversaturation on water bulk. We found that the gas enrichment layer, gas adsorption monolayer on the hydrophobic substrate, and water hydrogen bonding near the interface are likely necessary conditions for nanobubble stability. We concluded that gas nanobubble stability does not necessarily require three-phase pinning sites.

Zinc has been described as the 'calcium of the twenty-first century'. Zinc-based degradable biomaterials have recently emerged thanks to their intrinsic physiological relevance, biocompatibility, biodegradability, and pro-regeneration properties. Zinc-based biomaterials mainly include: metallic zinc alloys, zinc ceramic nanomaterials, and zinc metal-organic frameworks (MOFs). Metallic zinc implants degrade at a desirable rate, matching the healing pace of local tissues, and stimulating remodeling and formation of new tissues. Zinc ceramic nanomaterials are also beneficial for tissue engineering and therapy thanks to their nanostructures and antibacterial properties. MOFs have large surface areas and are easily functionalized, making them ideal for drug delivery and cancer therapy. This review highlights recent developments in zinc-based biomaterials, discusses obstacles to overcome, and pinpoints directions for future research.

The elastic mechanical properties of silicon nanocantilevers are of prime importance in biotechnology and nanoelectromechanical system (NEMS) applications. In order to make these applications reliable, the exact evaluation of the effect of the undercut on the mechanical properties of silicon nanocantilevers is essential and critical. In this paper, a numerical-experimental method for determining the effect of the undercut on resonant frequencies and Young’s modulus of silicon nanocantilevers is proposed by combining finite element (FE) analysis and dynamic frequency response tests by using laser Doppler vibrometer (LDV) as well as static force-displacement curve test by using an atomic force microscope (AFM). Silicon nanocantilevers test structures are fabricated from silicon-on-insulator (SOI) wafers by using the standard complementary metal-oxide-semiconductor (CMOS) lithography process and anisotropic wet-etch release process based on the critical point drying, which inevitably generating the undercut of the nanocantilever clamping. Combining with three-dimensional FE numerical simulations incorporating the geometric undercut, the dynamic resonance tests demonstrate that the undercut obviously reduces resonant frequencies of nanocantilevers due to the fact that the undercut effectively increases the nanocantilever length by a correct value ΔL. According to a least-square fit expression including ΔL, we extract Young’s modulus from the measured resonance frequency versus the effective length dependency and find that Young’s modulus of a silicon nanocantilever with 200-nm thickness is close to that of bulk silicon. However, when we do not consider the undercut ΔL, the obtained Young's modulus is decreased 39.3%. Based on the linear force-displacement response of 12μm long and 200nm thick silicon nanocantilever obtained by using AFM, our extracted Young’s modulus of the [110] nanocantilever with and without undercut is 169.1GPa and 133.0GPa, respectively. This error reaches 21.3%. Our work reveals that the effect of the undercut on the characterization of the mechanical properties of nanocantilevers with dynamic and static test must be carefully considered.

This paper presents a novel and effective characterization method for giant piezoresistive properties of silicon nanowires by using the reference structures. This contrast detection approach investigates the influences of quantum size effect and surface defects effect on piezoresistive coefficients of silicon nanowires by direct comparison of the resistivity change ratio of silicon wires with nanoscale-to-microscale width under the same applied stress conditions. The characterization experiments based on four-point bending tensile test demonstrate that piezoresistive coefficient of small nanowidth silicon nanowire can be significantly increased to about five times higher levels than that of bulk silicon under the same impurity concentration, which indicates that the silicon nanowire can have giant piezoresistive effect. On the other hand, to solve the problem on nanowires pick-up, we proposed a nanowire piezoresistive detection approach, whose validity is confirmed by the dynamic LDV resonance test. Meanwhile, to investigate the influence of undercut arising from the wet chemical release process of the suspended silicon nanowire, a three-dimensional finite element simulation is also carried out for the fundamental resonant frequency using ANSYS software. The numerical and experimental results show that our piezoresistive detection is accurate and effective and the undercut should be carefully considered in the design of the high frequency resonator and mixer. The findings of this paper provide some useful references for the piezoresistive effect measurement and the piezoresistive pick-up in nanoelectromechanical system.

Assembly of carbon nanomaterials into three-dimensional (3D) architectures is necessary to harness their unique physiochemical properties for tissue engineering and regenerative medicine applications. Herein, we report the fabrication and comprehensive cytocompatibility assessment of 3D chemically crosslinked macrosized (5–8 mm height and 4–6 mm diameter) porous carbon nanotube (CNT) scaffolds. Scaffolds prepared via radical initiated thermal crosslinking of single- or multiwalled CNTs (SWCNTs and MWCNTs) possess high porosity (>80%), and nano-, micro-, and macroscale interconnected pores. MC3T3 preosteoblast cells on MWCNT and SWCNT scaffolds showed good cell viability comparable to poly(lactic-co-glycolic) acid (PLGA) scaffolds after 5 days. Confocal live cell and immunofluorescence imaging showed that MC3T3 cells were metabolically active and could attach, proliferate, and infiltrate MWCNT and SWCNT scaffolds. SEM imaging corroborated cell attachment and spreading and suggested that cell morphology is governed by scaffold surface roughness. MC3T3 cells were elongated on scaffolds with high surface roughness (MWCNTs) and rounded on scaffolds with low surface roughness (SWCNTs). The surface roughness of scaffolds may be exploited to control cellular morphology and, in turn, govern cell fate. These results indicate that crosslinked MWCNTs and SWCNTs scaffolds are cytocompatible, and open avenues toward development of multifunctional all-carbon scaffolds for tissue engineering applications. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 3212–3225, 2015.

Quantitative ultrasound (QUS) is capable of predicting the principal structural orientation of trabecular bone; this orientation is highly correlated with the mechanical strength of trabecular bone. Irregular shape of bone, however, would increase variation in such a prediction, especially under human in vivo measurement. This study was designed to combine transmission and reflection modes of QUS measurement to improve the prediction for the structural and mechanical properties of trabecular bone. QUS, mechanical testing, and micro computed tomography (μCT) scanning were performed on 24 trabecular bone cubes harvested from a bovine distal femur to obtain the mechanical and structural parameters. Transmission and reflection modes of QUS measurement in the transverse and frontal planes were performed in a confined 60° angle range with 5° increment. The QUS parameters, attenuation (ATT) and velocity (UV), obtained from transmission mode, were normalized to the specimen thickness acquired from reflection mode. Analysis of covariance showed that the combined transmission-reflection modes improved prediction for the structural and Young's modulus of bone in comparison to the traditional QUS measurement performed only in the medial-lateral orientation. In the transverse plane, significant improvement between QUS and μCT was found in ATT vs bone surface density (BS/BV) (p

The homogeneous neodymium-based catalyst systems containing neodymium carboxylate, isobutyl aluminum compound and chlorinating agent were successfully developed for the coordination polymerizations of butadiene, isoprene and styrene in our laboratory. The catalyst possessed high catalytic activity to butadiene polymerization in hexane, leading to an obvious decrease in the dosage of catalyst to low level, e.g Nd/Bd (molar ratio) was around 35 ppm. Simultaneously, the catalyst exhibited high stereo-selectivity to butadiene polymerization in hexane and polybutadienes with extremely high cis-1,4 configuration of around 99% could be produced under appropriate reaction conditions. Based on our interesting fundamental research works, the continuous butadiene polymerizations were conducted to produce high cis-1,4 polybutadiene in pilot scale in SINOPEC. The industrial equipments (capacity: 30 000 t/a) for production of neodymium butadiene rubber (Nd-BR) were successfully built in SINOPEC in 2012 and the innovation technology has been achieved from fundamental research to industrial application for large scale production of Nd-BR. The Nd-BR products are now commercially available with the trade names of BR Nd40, BR Nd50, BR Nd60 with ML (1+4) 100 degrees C of 45 +/- 5, 55 +/- 5, and 63 +/- 5, respectively. The excellent properties of these high cis-1,4 Nd-BR products lead to their especially suitable application in green-tire components.

Concerns over the use of autografts or allografts have necessitated the development of biomaterials for bone regeneration. Various studies have been performed to optimize the cultivation of osteogenic cells using osteoconductive porous scaffolds. The aim of this study was to evaluate the osteogenic efficiency of bone cell ingrowth, proliferation, and early differentiation in a silicon carbide (SiC) porous ceramic scaffold promoted with low-intensity pulsed ultrasound. MC3T3-E1 mouse preosteoblasts were seeded onto scaffolds and cultured for 4 and 7 days with daily of 20-min ultrasound treatment. The cells were evaluated for cell attachment, morphology, viability, ingrowth depth, volumetric proliferation, and early differentiation. After 4 and 7 days of culture and ultrasound exposure, the cell density was higher in the ultrasound-treated group compared with the sham-treated group on SiC scaffolds. The cell ingrowth depths inside the SiC scaffolds were 149.2±27.3 μm at 1 day, 310.1±12.6 μm for the ultrasound-treated group and 248.0±19.7 μm for the sham control at 4 days, and 359.6±18.5 μm for the ultrasound-treated group and 280.0±17.7 μm for the sham control at 7 days. They were significantly increased, that is, 25% (p=0.0029) and 28% (p=0.0008) increase, respectively, with ultrasound radiation force as compared with those in sham control at 4 and 7 days postseeding. The dsDNA contents were 583.5±19.1 ng/scaffold at 1 day, 2749.9±99.9 ng/scaffold for the ultrasound-treated group and 2514.9±114.7 ng/scaffold for the sham control at 4 days, and 3582.3±325.3 ng/scaffold for the ultrasound-treated group and 2825.7±134.3 ng/scaffold for the sham control at 7 days. There was a significant difference in the dsDNA content between the ultrasound- and sham-treated groups at 4 and 7 days. The ultrasound-treated group with the SiC construct showed a 9% (p=0.00029) and 27% (p=0.00017) increase in the average dsDNA content at 4 and 7 days over the sham control group, respectively. Alkaline phosphatase activity was significantly increased by the treatment of ultrasound at 4 (p=0.012) and 7 days (p=0.035). These results suggested that ultrasound treatment with low-intensity acoustic energy facilitated the cellular ingrowth and enhanced the proliferation and early differentiation of osteoblasts in SiC scaffolds.

Metallic implant materials are widely used for clinical applications but still could not achieve satisfactory functionalities for specific biomedical applications. Surface functionalizations are of particular interest to improve their surface bioactivity and provide other biofunctionalities for biomedical applications. Because of the excellent biological functions of calcium phosphate ceramics (CaPs), CaP coatings have been proposed and developed onto the surface of metallic implants to achieve improved osteointegration, corrosion resistance and antibacterial properties. This review firstly introduces the metallic biomaterials, important surface properties, and then elaborates the surface functionalization with CaP coatings for metallic biomaterials.