Microstructure of ion-implanted region in TiNi alloy

TiNi alloy samples implanted with various fluences of 3 MeV Cu²⁺ ions were characterized by transmission electron microscope (TEM) and X-ray diffractometer. Cross-sectional TEM images of the samples showed that amorphous region was seen at the fluence of 10¹⁴ ions cm^?2 in case of ion implantation at 300 K of the substrate temperature, but in case of ion implantation at 100 K it did not appear even at 10¹⁵ ions cm^?2. These results were also confirmed by X-ray diffraction profiles of the same samples. Consequently, the extent of microstructure change of TiNi alloy by ion implantation was different depending on the substrate temperature.     

Pulmonary arterial impedance analysis by the use of the oscillated assist flow

Pulmonary arterial impedance is an important and interesting characteristic that can be used to evaluate the physiological properties of the pulmonary vessel. However, power spectrum analysis of the pulmonary artery pressure and flow pattern have suggested that peak power in the relatively high frequency range (> 10 Hz) is significantly low; thus, we cannot analyze the vessel properties in the high frequency range. In this study, we used the newly developed vibrating flow pump (VFP), which can generate oscillated blood flow with a relatively high frequency (10-50 Hz) for right heart bypass, to evaluate the pulmonary arterial impedance pattern in the high frequency range. Acute animal experiments of the right heart bypass from the right atrium to the pulmonary artery using 6 healthy adult goats were performed. The flow pattern and pressure of the pulmonary artery, electrocardiograms (ECGs), and arterial and right atrial pressures were continuously monitored during the experiments. Spectral analysis of the hemodynamic parameters using the fast Fourier transform (FFT) method was performed to evaluate the spectral properties. The coherence function, transfer function, and phase patterns were calculated to analyze the impedance pattern in the relatively high frequency area. Previously, various investigators had tried to analyze the impedance patterns of the pulmonary artery; however, they could not analyze the impedance patterns over 10 Hz because the spectral patterns of the pulmonary flow do not have high power at high frequencies. These physiological analyses may be useful in designing the optimal pulmonary circulation.     

Effect of CO2 on layered Li1+zNi1−x−yCoxMyO2 (M = Al,Mn) cathode materials for lithium ion batteries

We investigated the effect of CO₂ on layered Li_1+zNi_1−x−yCo_xM_yO₂ (M = Al, Mn) cathode materials for lithium ion batteries which were prepared by solid-state reactions. Li_1+zNi_(1−x)/2Co_xMn_(1−x)/2O₂ (Ni/Mn mole ratio = 1) singularly exhibited high storage stability. On the other hand, Li_1+zNi_0.80Co_0.15Al_0.05O₂ samples were very unstable due to CO₂ absorption. XPS and XRD measurements showed the reduction of Ni³⁺ to Ni²⁺ and the formation of Li₂CO₃ for Li_1+zNi_0.80Co_0.15Al_0.05O₂ samples after CO₂ exposure. SEM images also indicated that the surfaces of CO₂-treated samples were covered with passivation films, which may contain Li₂CO₃. The relationship between CO₂-exposure time and CO₃²⁻ content suggests that there are two steps in the carbonation reactions; the first step occurs with the excess Li components, Li₂O for example, and the second with LiNi_0.80Co_0.15Al_0.05O₂ itself. It is well consistent with the fact that the discharge capacity was not decreased and the capacity retention was improved until the excess lithium is consumed and then fast deterioration occurred.     

Zinc as an essential trace element in the acceleration of matrix vesicles-mediated mineral deposition

BACKGROUND: Zinc (Zn) has a potent stimulatory effect on osteoblastic bone formation and an inhibitory effect on osteoclastic bone resorption. PURPOSE: The effect of Zn on the function of matrix vesicles (MVs) remains controversial. The purpose of this study was to investigate the effect of Zn on alkaline phosphatase (ALP) activity of osteoblasts and in the initial biological MVs‐mediated mineral deposition. STUDY DESIGN: Osteoblasts were treated with varying concentrations of Zn dissolved in culture medium. After three, five, and seven days of culture, ALP activity was assayed. For the detection of a low level of calcium concentration in MVs, X‐ray fluorescence (XRF) analyses were applied. The effect of Zn for the transformation of calcium phosphate was analyzed using a scanning electron microscope fitted with an energy dispersive X‐ray microanalysis (EDX) system. RESULTS: The ALP activity of osteoblasts in culture medium supplemented with 1 × 10^?5M of Zn was significantly increased at both five and seven days. XRF data demonstrated higher levels of calcium concentration over time in the Zn‐supplemented group. EDX data showed that mineral deposits beginning on day 3 were transformed from whitlockite to calcium phosphate near hydroxyapatite, and that Zn accelerated this transformation. CONCLUSIONS: The proper concentration of Zn increased the ALP activity of osteoblasts after five and seven days of incubation. The present XRF and EDX data suggest that the increase of mineral deposition with Zn exposure for one to five days might be mediated by the activation of ALP and calcium‐binding proteins. Microsc. Res. Tech., 2011. © 2011 Wiley Periodicals, Inc.     

Electrochemical Molecular Conversion of α-Keto Acid to Amino Acid at a Low Overpotential Using a Nanoporous Gold Catalyst

A nanoporous gold (NPG) electrode prepared through a facile anodization technique was employed in the electrochemical reductive amination of biomass-derivable α-keto acids in the presence of a nitrogen source to produce the corresponding amino acids. NPG showed a clear reductive current in the presence of α-keto acid and NH₂OH, and the electrolysis experiments confirmed the production of L-amino acid. A reductive voltammetric signal at the NPG electrode appeared at a more positive potential by 0.18–0.79 V, compared with those at the planar-gold electrode without anodization and other previously reported electrode systems, indicating the high activity of the prepared nanostructure for the electrochemical reaction. Maximum Faradaic efficiencies (FEs) of 74–93% in the reductive molecular conversion to amino acids of Ala, Asp, Glu, Gly, and Leu were obtained under the optimized conditions. The FE values were strongly dependent on the applied potential in the electrolysis, suggesting that the hydrogen evolution reaction at the electrode surface was more significant as the applied potential became more negative. The effect of potential at the NPG was lower than that at the planar-gold electrode. These results indicate that nanostructurization decreases the overpotential for the electrochemical reductive amination, resulting in high FE.     

Isolation and Identification of Potential Beer‐Spoilage Pediococcus inopinatus and Beer‐Spoilage Lactobacillus backi Strains Carrying the horA and horC Gene Clusters

Four beer‐spoilage strains, LA20, LA21, LA22 and LA23, were isolated from brewery environments. Based on the 16S rRNA gene sequence, LA20 was identified as Pediococcus inopinatus and the remaining three were identified as Lactobacillus backi. The homologs of horA and horC, the hop resistance genes originally identified in L. brevis ABBC45, were detected simultaneously in LA22 and LA23, while only a horA homolog and a horC homolog were found in LA20 and LA21 respectively. The 5.6 kb DNA regions containing the horA homolog in LA20 and LA22 were almost 99% identical with the corresponding region of ABBC45. Similarly the 8.2 kb regions containing the horC homolog in LA21 and LA22 were more than 99% identical with that of ABBC45. Interestingly the horA‐containing 5.6 kb regions in LA20 and LA22 were found to be completely identical despite the distinct genus status. Coupled with the fact that LA20 and LA22 were isolated from the same sampling site, these results, taken collectively, reinforce our hypothesis that horA and horC genes were acquired by beer‐spoilage species through horizontal gene transfer and confirm the usefulness of horA and horC as genetic markers for the species‐independent determination of beer‐spoilage ability in lactic acid bacteria.