Jinghuai Zhang

Carbon nanotube–hydroxyapatite nanocomposite: A novel platform for glucose/O2 biofuel cell

This study demonstrates a novel carbon nanotubes-hydroxyapatite (CNTs-HA) nanocomposite-based compartment-less glucose/O(2) biofuel cell (BFC) with the glucose oxidase (GOD) as the anodic biocatalysts and the laccase as the cathodic biocatalysts. CNTs-HA nanocomposite prepared by the self-assembly method via an aqueous solution reaction has been used as the co-immobilization matrix to incorporate biocatalysts, i.e. GOD and laccase successfully. Moreover, the three-dimensional configuration of the CNTs-HA films electrode would be advantageous to the glucose oxidation on the bioanode and O(2) electroreduction on the biocathode of BFC. The maximum power density delivered by the assembled glucose/O(2) BFC could reach 15.8 muWcm(-2) at a cell voltage of 0.28 V with 10 mM glucose. The results indicate that the CNTs-HA nanocomposite is believed to be very useful for the development of novel BFC device.

A novel amperometric hydrogen peroxide biosensor based on immobilized Hb in Pluronic P123-nanographene platelets composite

In this paper, an amperometric biosensor of hydrogen peroxide (H(2)O(2)) was fabricated by immobilization of Hemoglobin (Hb) on a Pluronic P123-nanographene platelet (NGP) composite. Direct electron transfer in the Hb-immobilized P123-NGP composite film was greatly facilitated. The surface concentration (Γ*) and apparent heterogeneous electron transfer rate constant (k(s)) were calculated to be (1.60±0.17)×10(-10) mol cm(-2) and 48.51 s(-1), respectively. In addition, the Hb/Pluronic P123-NGP composite showed excellent bioelectrocatalytic activity toward the reduction of H(2)O(2). The biosensor of H(2)O(2) exhibited a linear response to H(2)O(2) in the range of 10-150 μM and a detection limit of 8.24 μM (S/N=3) was obtained. The apparent Michaelis-Menten constant (K(m)(app)) was 45.35 μM. The resulting biosensor showed fast amperometric response, with very high sensitivity, reliability and effectiveness.

Influence of biocorrosion on microstructure and mechanical properties of deformed Mg-Y-Er-Zn biomaterial containing 18R-LPSO phase.

The microstructure and mechanical properties of as-extruded Mg-8Y-1Er-2Zn (wt%) alloy containing long period stacking ordered (LPSO) phase are comparatively investigated before and after corrosion in a simulated body fluid (SBF) at 37°C. The as-extruded alloy consists of a long strip-like 18R-LPSO phase and some fine lamellae grains formed by primary recrystallization during the extrusion process. The hydrogen evolution volume per day fluctuates between 0.21 and 0.32ml/cm(2) in the immersion test for 240h, and the corresponding corrosion rate is calculated as 0.568mm/y. The corrosion product is determined as Mg(OH)2, whilst a Ca(H2PO4)2 compound is also observed on the surface of the samples. The corrosion site preferentially occurs at the interface between LPSO phase and Mg matrix. Before immersing, the tensile yield strength (TYS), ultimate tensile strength (UTS) and elongation of the alloy are 275MPa, 359MPa, and 19%, respectively. More attractively, these mechanical properties can be maintained even after immersing in SBF for 240h (TYS, UTS and elongation are 216MPa, 286MPa and 6.8%, respectively) because of the existence of high anti-corrosion LPSO phase.

A novel amperometric hydrogen peroxide biosensor based on electrospun Hb–collagen composite

In this paper, the hemoglobin (Hb)-collagen microbelt modified electrode with three-dimensional configuration was fabricated via the electrospinning method. Direct electron transfer of the Hb immobilized into the electrospun collagen microbelts was greatly facilitated. The apparent heterogeneous electron transfer rate constant (k(s)) was calculated to be 270.6s⁻¹. The electrospun Hb-collagen microbelt modified electrode showed an excellent bioelectrocatalytic activity toward the reduction of H₂O₂. The amperometric response of the biosensor varied linearly with the H₂O₂ concentration ranging from 5 × 10⁻⁶molL⁻¹ to 30×10⁻⁶molL⁻¹, with a detection limit of 0.37 × 10⁻⁶molL⁻¹ (signal-to-noise ratio of 3). The apparent Michaelis-Menten constant (K(m)(app)) was 77.7 μmolL⁻¹. The established biosensor exhibited fast amperometric response, high sensitivity, good reproducibility and stability.

New horizon for high performance Mg-based biomaterial with uniform degradation behavior: Formation of stacking faults.

Designing the new microstructure is an effective way to accelerate the biomedical application of magnesium (Mg) alloys. In this study, a novel Mg–8Er–1Zn alloy with profuse nano-spaced basal plane stacking faults (SFs) was prepared by combined processes of direct-chill semi-continuous casting, heat-treatment and hot-extrusion. The formation of SFs made the alloy possess outstanding comprehensive performance as the biodegradable implant material. The ultimate tensile strength (UTS: 318 MPa), tensile yield strength (TYS: 207 MPa) and elongation (21%) of the alloy with SFs were superior to those of most reported degradable Mg-based alloys. This new alloy showed acceptable biotoxicity and degradation rate (0.34 mm/year), and the latter could be further slowed down through optimizing the microstructure. Most amazing of all, the uniquely uniform in vitro/vivo corrosion behavior was obtained due to the formation of SFs. Accordingly we proposed an original corrosion mechanism for the novel Mg alloy with SFs. The present study opens a new horizon for developing new Mg-based biomaterials with highly desirable performances.

Effective inhibition of the early copper ion burst release with ultra-fine grained copper and single crystal copper for intrauterine device application

To solve the main problems of existing coarse grained copper (CG Cu) intrauterine devices (IUD)-namely burst release and a low transfer efficiency of the cupric ions during usage-ultra-fine grained copper (UFG Cu) and single crystal copper (SC Cu) have been investigated as potential substitutes. Their corrosion properties with CG Cu as a control have been studied in simulated uterine fluid (SUF) under different conditions using electrochemical measurement methods. Long-term immersion of UFG Cu, SC Cu and CG Cu samples in SUF at 37 °C have been studied for 300 days. A lower copper ion burst release and a higher efficiency release of cupric ions were observed for UFG Cu and SC Cu compared with CG Cu in the first month of immersion and 2 months later. The respective corrosion mechanisms for UFG Cu, SC Cu and CG Cu in SUF are proposed. In vitro biocompatibility tests show a better cellular response to UFG Cu and SC Cu than CG Cu. In terms of instantaneous corrosion behavior, long-term corrosion performance and in vitro biocompatibility, the three pure copper materials follow the order: UFG Cu>SC Cu>CG Cu, which indicates that UFG Cu could be the most suitable candidate material for intrauterine devices.

Structure stability and mechanical properties of high-pressure die-cast Mg-Al-Ce-Y-based alloy

With the aim to further improve the mechanical properties of Mg-Al-RE-based alloy, Mg-3.0Al-1.8Ce-0.3Y-0.2Mn alloy was prepared by high-pressure die-casting technique. The microstructure, thermal stability of intermetallic phases and mechanical properties were investigated. The results show that the alloy is composed of fine primary alpha-Mg dendrites and eutectic in the interdendritic regions. The intermetallic phases in eutectic are Al-11(Ce,Y)(3) and Al-2(Ce,Y) with the former being the dominant one. The thermal stability of Al-11(Ce,Y)(3) is conditioned. It is basically stable at temperature up to 200 degrees C within 800 h, while most of the Al-11(Ce,Y)(3) intermetallics transform to Al-2(Ce,Y) at higher temperature of 450 degrees C for 800 h. The alloy exhibits remarkably improved strength both at room temperature and 200 degrees C, which is mainly attributed to the reinforcement of dendrite boundaries with Al-11(Ce,Y)(3) intermetallics, small dendritic arm spacing effect as well as the solid solution strengthening with Y element.

A new cell line from Spodoptera exigua (Lepidoptera: Noctuidae) and its differentially expressed genes

A new cell line, designated IOZCAS‐Spex XI, was established from the pupal ovaries of Spodoptera exigua (Lepidoptera: Noctuidae) in TNM‐FH medium containing 10% foetal bovine serum. The spherical cells were predominant among the various cell types. The population‐doubling time during the logarithmic phase of growth was 81.7 h. It was confirmed that the cell line originated from S. exigua by DAF‐PCR technique. Analysis of susceptibility to baculovirus showed that the new cell line was susceptible to S. exigua nucleopolyhedrovirus (SeNPV), Autographa californica multiple NPV (AcMNPV) and slightly susceptible to S. litura NPV (SpltNPV), while not permissive to Helicoverpa armigera NPV and Hyphantria cunea NPV (HcNPV). Real‐Time PCR analysis was carried out to compare some differentially expressed genes between the cell line and the primary culture. The result showed that marked significant differences were observed in the expression of the genes of SUMO‐1 activating enzyme, BCCIP‐like protein, 10 kDa HSP, CypA, receptor for activated PKC, PDI‐like protein ERp57, ALDH, DEAD box ATP‐dependent RNA helicase‐like protein (P < 0.01), while a significant difference was obtained in the expression of GST gene between the cell line and the primary culture (P < 0.05).

Twin intersection in a deformed TiAl alloy

Twin intersection in a deformed TiAl alloy was studied. Whether type I twin intersection or type II twin intersection appears is related to the fact that which kind of twinning dislocation will be activated. If the Shockley partial of Burgers vector gammaD in matrix is activated, the type I twin intersection often appears. Otherwise the type II twin intersection appears. The appearance ratio of the type I twin intersection to the type II twin intersection is 1:2. The straight penetration in the type II twin intersection is observed. This kind of intersection can be accomplished by a shear plus reshuffle process

Microstructural characteristics of Ti-48Al-2Cr alloy

The microstructural characteristics of two-phase α2+γ titanium aluminide before and after deformation are investigated by transmission electron microscopy (TEM). The orientation relationships associated with the γ-γ combinations can be divided into three types: true twin, order domain, and pseudo-twin. Of the three orientation relationships, true twin accounts for more than 50%, which is most likely due to a minimization of interfacial energy related to misfit and interaction energy of interface atoms. During deformation, lamellar boundaries cause different resistance to the propagation of intersecting twin. Experimental observations and theoretical analysis consistently show that the resistance has the following sequence: F120°