High-efficiency combinatorial approach as an effective tool for accelerating metallic biomaterials research and discovery.

A high-efficiency combinatorial approach has been applied to rapidly build the database of composition-dependent elastic modulus and hardness of the Ti-Ta and Ti-Zr-Ta systems. A diffusion multiple of the Ti-Zr-Ta system was manufactured, then annealed at 1173K for 1800h, and water quenched to room temperature. Extensive interdiffusion among Ti, Zr and Ta has taken place. Combining nanoindentation and electron probe micro-analysis (EPMA), the elastic modulus, hardness as well as composition across the diffusion multiple were determined. The composition/elastic modulus/hardness relationship of the Ti-Ta and Ti-Zr-Ta alloys has been obtained. It was found that the elastic modulus and hardness depend strongly on the Ta and Zr content. The result can be used to accelerate the discovery/development of bio-titanium alloys for different components in implant prosthesis.

Circular polarization in the optical afterglow of GRB 121024A.

Gamma-ray bursts (GRBs) are most probably powered by collimated relativistic outflows (jets) from accreting black holes at cosmological distances. Bright afterglows are produced when the outflow collides with the ambient medium. Afterglow polarization directly probes the magnetic properties of the jet when measured minutes after the burst, and it probes the geometric properties of the jet and the ambient medium when measured hours to days after the burst. High values of optical polarization detected minutes after the burst of GRB 120308A indicate the presence of large-scale ordered magnetic fields originating from the central engine (the power source of the GRB). Theoretical models predict low degrees of linear polarization and no circular polarization at late times, when the energy in the original ejecta is quickly transferred to the ambient medium and propagates farther into the medium as a blast wave. Here we report the detection of circularly polarized light in the afterglow of GRB 121024A, measured 0.15 days after the burst. We show that the circular polarization is intrinsic to the afterglow and unlikely to be produced by dust scattering or plasma propagation effects. A possible explanation is to invoke anisotropic (rather than the commonly assumed isotropic) electron pitch-angle distributions, and we suggest that new models are required to produce the complex microphysics of realistic shocks in relativistic jets.

Cadmium toxicity is alleviated by AtLCD and AtDCD in Escherichia coli.

AIMS: Arabidopsis thaliana l- and d-cysteine desulfhydrases (AtLCD and AtDCD) are two important H(2) S-generating enzymes. This study determined the effects of H(2) S derived from AtLCD and AtDCD on cadmium (Cd) toxicity in Escherichia coli. METHODS AND RESULTS: AtLCD and AtDCD were cloned into pET28a vectors and transformed into wild-type E. coli strain BL21(DE3), named BL21(LCD) and BL21(DCD). In the induced BL21(LCD) and BL21(DCD) compared with wild type, significantly higher H(2) S generation rates were observed. Additionally, higher survival rates, reduced contents of malondialdehyde (MDA) and hydrogen peroxide (H(2) O(2)), decreased activities of superoxide dismutase and catalase under 220 µmol l(-1) Cd stress were noted. We obtained similar results in the wild type treated with NaHS, a H(2) S donor. The above changes were substantially counteracted by the mixture of ammonia and pyruvic acid potassium (NH(3) + C(3) H(3) KO(3)), a synthetic inhibitor of H(2) S. CONCLUSIONS: AtLCD and AtDCD catalyse the H(2) S production, generating an ameliorating effect against Cd-induced oxidative stress and resulting in E. coli resistance to Cd toxicity. SIGNIFICANCE AND IMPACT OF THE STUDY: H(2) S as a gasotransmitter is certified to have an ameliorating effect against Cd toxicity, thus providing information for further research regarding the role of H(2) S in regulating resistance to the heavy metal stress in organisms.

[An epidemiological survey on Helicobacter pylori infection in children].

In this study serum anti-urease antibodies of Helicobacter pylori was examined in order to investigate the prevalence of H. pylori infection in 394 children between age 1 and 13. The results showed that the average infection rate was 15.7% with a tendency of increase infection rate with age, and by the age of 12 the H. pylori infection rate reached 30%, which was higher than those found in developed countries. We also noticed that there was a comparatively higher serapositivity among 1 and 7 year olds. This may possibly be due to the close contact between family members and school mates. In addition, the serum positive rate of antibody to H. pylori urease in children with recurrent abdominal pain was much higher than those asymptomatic children (P < 0.05).

[A electromyographical observation on the treatment of poliomyelitis sequelae with series electroacupuncture].

We observed the changes of quadriceps femoris EMG before and after treatment on treatment 41 cases of poliomyelitis sequelae with series electroacupuncture. In 41 patients muscles strength of quadriceps femoris before treatment in 35 cases was below 0 degree and 1 degree. The changes of EMG, Most had no motor unit potential, some only a few but duration was long, and amplitude decreased markedly. A few had fibrillation or positive sharp wave. The changes in EMG accorded with the diagnosis of poliomyelitis sequelae. After 3 month treatment, tee EMG findings were decreasing or there was loss of fibrillation, appearance of motor unit potentials, increase of the amount of motor unit potentials, prolongation of duration and increasing of amplitude of motor unit potentials, appearance of polyphasic potentials etc. Through analysis of EMG, 32 among 41 cases were improved, effective rate was 78%, P less than 0.01. EMG indices indicate the efficacy of series mg electroacupuncture in treating the sequelae of poliomyelitis and confirm the clinical therapeutic effect of the treatment. The indices indicate that the pathological changes of damaged anterior horn cells of the spinal cord were decreased and partial recovery of nervous function. The EMG changes paralleled those in clinical therapeutic effect of treatment and changes of muscle strength.