Precipitation of single crystalline AlN from Cu-Al-Ti solution under nitrogen atmosphere

Precipitation and growth behavior of AlN from Cu-Al-Ti-N solution under the atmospheric pressure of nitrogen has been studied. The solubility of AlN in Cu flux ranges from 5 mol% to 20 mol% at the temperatures between 1700 C and 2000 C. The addition of the proper amount of Ti drastically enhances the solubility of AlN. Acicular crystallites and platelets of AlN precipitants, which were all water white colored, were obtained by super-cooling the Cu-Al-Ti-N solution. The largest pencil type AlN reached more than 3 mm in its length and 0.2 mm in its diameter. The axis of the pencil was c-axis of wurtzite AlN and it contained no dislocation, no diffractive defects. A platelet of AlN of which diameter exceeded 1.5 mm was also obtained by regrowth technique. Thermodynamic calculation reveals the validity of using Cu-Al-Ti-N solution for the growth of AlN.     

A kinetic study of nonoxidative dissolution of galena in aqueous acid solution

This paper presents the results obtained through a kinetic study of the nonoxidative dissolution of natural galena in hydrochloric acid and perchloric acid solutions with and without the addition of sodium chloride. Under the experimental conditions employed in this study, the dissolution rates were controlled by a chemical reaction on the surface of the galena sample. The galena dissolution rate is of the first order with respect to hydrochloric ion activity in hydrochloric acid and perchloric acid solutions. The addition of sodium chloride to the acid solutions greatly enhanced the dissolution rate. The effect of sodium chloride has two possible interpretations: First, it may be the result of an increase in hydrogen ion activity. Second, the enhancement of the dissolution rate observable at high sodium chloride concentration may be due to the specific adsorption of chloride ions or the surface complexing of chloride ions on the galena surface.     

The role of ions on histamine-induced depolarization in isolated guinea pig adipocytes

Effects of ions on histamine (Hi)-induced depolarization were studied in guinea pig adipocytes. Depolarization induced by Hi in guinea pig adipocytes was decreased by removal of K+ from the medium or pretreatment with ouabain at concentrations that showed no significant effect themselves. The decrease in membrane potentials induced by Hi was also abolished potently by replacement of Na+ by choline or pretreatment with tetrodotoxin at a concentration that caused no significant action alone. Pretreatment with monensin at a concentration lower than that eliciting the action resulted in a potentiation of Hi-induced depolarization. The depolarization induced by Hi was not affected by the presence of Ca2+ in the medium or pretreatment of the cells by diltiazem.     

Comparing polyaluminum chloride and ferric chloride for antimony removal

Antimony has been one of the contaminants required to be regulated, however, only limited information has been collected to date regarding antimony removal by polyaluminium chloride (PACl) and ferric chloride (FC). Accordingly, the possible use of coagulation by PACl or FC for antimony removal was investigated. Jar tests were used to determine the effects of solution pH, coagulant dosage, and pre-chlorination on the removal of various antimony species. Although high-efficiency antimony removal by aluminum coagulation has been expected because antimony is similar to arsenic in that both antimony and arsenic are a kind of metalloid in group V of the periodic chart, this study indicated: (1) removal density (arsenic or antimony removed per mg coagulant) for antimony by PACl was about one forty-fifth as low as observed for As(V); (2) although the removal of both Sb(III) and Sb(V) by coagulation with FC was much higher than that of PACl, a high coagulant dose of 10.5mg of FeL(-1) at optimal pH of 5.0 was still not sufficient to meet the standard antimony level of 2 microg as SbL(-1) for drinking water when around 6 microg as SbL(-1) were initially present. Consequently, investigation of a more appropriate treatment process is necessary to develop economical Sb reduction; (3) although previous studies concluded that As(V) is more effectively removed than As(III), this study showed that the removal of Sb(III) by coagulation with FC was much more pronounced than that of Sb(V); (4) oxidation of Sb(III) with chlorine decreased the ability of FC to remove antimony. Accordingly, natural water containing Sb(III) under anoxic condition should be coagulated without pre-oxidation.     

Polyarginine segments in block copolypeptides drive both vesicular assembly and intracellular delivery

Polymeric vesicles are a relatively new class of nanoscale self-assembled materials that show great promise as robust encapsulants. Compared with liposomes, use of polymeric building blocks for membrane formation allows increased stability, stimuli responsiveness and chemical diversity, which may prove advantageous for drug-delivery applications . A major drawback of most polymeric vesicles is the lack of biofunctionality, which restricts their ability to interact with cells and tissues. We have prepared vesicles composed of polyarginine and polyleucine segments that are stable in media, can entrap water soluble species, and can be processed to different sizes and prepared in large quantities. The remarkable feature of these materials is that the polyarginine segments both direct structure for vesicle formation and provide functionality for efficient intracellular delivery of the vesicles. This unique synergy between nanoscale self-assembly and inherent peptide functionality provides a new approach for design of multifunctional materials for drug delivery.     

Si thin platelets as high-capacity negative electrode for Li-ion batteries

Pure Si platelets and Ni or Cu layer-laminated Si platelets with difference thickness were prepared, and their charge/discharge properties were examined in 1 M LiClO₄/EC + DEC (1:1 by volume) as alternative negative electrode materials to graphite for Li-ion batteries. The shape of thin platelets and lamination with Ni layer are significantly effective to improve the cycleability in Li-Si alloy system by relieving the stress during the alloying/de-alloying processes, reinforcing the mechanical strength and reducing the Li⁺ ion diffusion length. Moreover, the first irreversible capacity is minimized by reduction of the amount of Ketjen Black (KB) in the composite electrode because of electrolyte decomposition on the surface of KB. Consequently, the Si/Ni/Si-LP30 (30/30/30 nm) composite electrode with 5 wt% KB also exhibits over 700 mAh g⁻¹ even after 50 cycles in 1 M LiPF₆/EC + DEC (1:1).     

Electromagnetic wave radiated from an insulating spacer in gas insulated switchgear with partial discharge detection

As a means of diagnosing partial discharge (PD) signals propagate inside a Gas Insulated Switchgear (GIS), a study for the leakage of electromagnetic waves (EM-waves) emitted from the insulating spacer was implemented. The EM-waves leaking out from the solid insulator have the resonance frequencies depend on the spacing between adjacent bolts in the direction of the flange circumference, because the leakage portion is the equivalent of a slot antenna. In this paper, using an electromagnetic analysis model which has a simulated spacer on a concentrically-shaped GIS tank, the output characteristics of the EM-waves that leaked out from the slit were analyzed under various conditions such as the spacing between adjacent bolts, the width of the spacer, the dielectric constant of the spacer and the form of the flange. Also the actual measurement by the experimental equipment used to simulate the model was implemented for comparison with the analytical results. Consequently, the optimal specifications of the sensor and the measurement method used to achieve highly-sensitive detection for practical use were summarized and proposed as well as evaluating the effectiveness of the electromagnetic analysis model adopted in this paper.     

Synthesis of Polypeptide-Polyether Conjugates from an Activated Urethane Derivative of γ-Benzyl-L-glutamate as a Monomer

N-(4-Nitrophenoxycarbonyl)-γ-benzyl-L-glutamate (1) was heated at 60 °C in N,N-dimethylacetoamide (DMAc) in the presence of p-(tert-butyl)phenylmethylamine (2) to afford poly(γ-benzyl-L-glutamate) in high yield. ¹H NMR analysis of the obtained polymer revealed that the p-(tert-butyl)phenylmethyl group was successfully introduced into the polymer chain end. Under the same conditions, polycondensations of 1 in the presence of poly(ethylene glycol)s having amino terminals were performed. Both of the components were consumed quantitatively to afford the corresponding block copolymers having poly(γ-benzyl-L-glutamate) and poly(ethylene glycol) segments. The molecular weights of the copolymers were controlled by the feed ratio [1]₀/[amino group in the macroinitiator]₀. Electronic Supplementary Material  The online version of this article at contains supplementary material, which is available to authorized users.     

Association of Ligamentum Flavum Hypertrophy with Adolescent Idiopathic Scoliosis Progression—Comparative Microarray Gene Expression Analysis

The role of the ligamentum flavum (LF) in the pathogenesis of adolescent idiopathic scoliosis (AIS) is not well understood. Using magnetic resonance imaging (MRI), we investigated the degrees of LF hypertrophy in 18 patients without scoliosis and on the convex and concave sides of the apex of the curvature in 22 patients with AIS. Next, gene expression was compared among neutral vertebral LF and LF on the convex and concave sides of the apex of the curvature in patients with AIS. Histological and microarray analyses of the LF were compared among neutral vertebrae (control) and the LF on the apex of the curvatures. The mean area of LF in the without scoliosis, apical concave, and convex with scoliosis groups was 10.5, 13.5, and 20.3 mm², respectively. There were significant differences among the three groups (p < 0.05). Histological analysis showed that the ratio of fibers (Collagen/Elastic) was significantly increased on the convex side compared to the concave side (p < 0.05). Microarray analysis showed that ERC2 and MAFB showed significantly increased gene expression on the convex side compared with those of the concave side and the neutral vertebral LF cells. These genes were significantly associated with increased expression of collagen by LF cells (p < 0.05). LF hypertrophy was identified in scoliosis patients, and the convex side was significantly more hypertrophic than that of the concave side. ERC2 and MAFB genes were associated with LF hypertrophy in patients with AIS. These phenomena are likely to be associated with the progression of scoliosis.