Neuronal nitric-oxide synthase is regulated by the Hsp90-based chaperone system in vivo

It is established that the multiprotein heat shock protein 90 (hsp90)-based chaperone system acts on the ligand binding domain of the glucocorticoid receptor (GR) to form a GR.hsp90 heterocomplex and to convert the receptor ligand binding domain to the steroid-binding state. Treatment of cells with the hsp90 inhibitor geldanamycin inactivates steroid binding activity and increases the rate of GR turnover. We show here that a portion of neuronal nitric-oxide synthase (nNOS) exists as a molybdate-stabilized nNOS. hsp90 heterocomplex in the cytosolic fraction of human embryonic kidney 293 cells stably transfected with rat nNOS. Treatment of human embryonic kidney 293 cells with geldanamycin both decreases nNOS catalytic activity and increases the rate of nNOS turnover. Similarly, geldanamycin treatment of nNOS-expressing Sf9 cells partially inhibits nNOS activation by exogenous heme. Like the GR, purified heme-free apo-nNOS is activated by the DE52-retained fraction of rabbit reticulocyte lysate, which also assembles nNOS. hsp90 heterocomplexes. However, in contrast to the GR, heterocomplex assembly with hsp90 is not required for increased heme binding and nNOS activation in this cell-free system. We propose that, in vivo, where access by free heme is limited, the complete hsp90-based chaperone machinery is required for sustained opening of the heme binding cleft and nNOS activation, but in the heme-containing cell-free nNOS-activating system transient opening of the heme binding cleft without hsp90 is sufficient to facilitate heme binding.     

Fabrication of Transparent Pb(Mg1/3Nb2/3)O3–PbTiO3 Based Ceramics by Conventional Sintering

Transparent 0.9Pb(Mg_1/3Nb_2/3)O₃–0.1PbTiO₃ (PMN‐PT) based ceramics were prepared by a conventional solid‐state synthesis without using a hot‐press method. The ceramics became transparent when they were sintered in an O₂ atmosphere. The optical transmission increased with decreasing diameter of the calcined powder, which was controlled by the size of zirconia ball‐milling media. Substitution of 3 mol% La for Pb in PMN‐PT further increased the optical transmission to 68% at the wavelength of 2000 nm, which was comparable to that of hot‐pressed Pb(Mg_1/3Nb_2/3)O₃‐PbTiO₃ based transparent ceramics.     

Synthesis and polymerization of amphiphilic itaconate monomer and some properties of the polymer

A β-2-methoxyethyl α-3-[tris(trimethylsiloxy)silyl]propyl itaconate (1) was synthesized successfully as a novel amphiphilic itaconate monomer, and its radical homopolymerization and copolymerization with styrene (St) were investigated. The polymerization rate (Rp) is expressed with Rp = k[1]^2.73[AIBN]^0.51. Overall activation energy in the radical homopolymerization was determined to be 52.9 kJ/mol. The 1 copolymerized with St in bulk in a highly alternating tendency. The Q, e values of the 1 were obtained to be 1.05 and 0.69, respectively, and the 1 was found to be a conjugative and electron-accepting monomer. Membranes containing the 1 unit, prepared by the copolymerization of 1 with N-vinylpyrrolidone (NVP) and by the terpolymerization of 1, NVP, and 2-hydroxyethyl methacrylate, showed higher oxygen permeability than corresponding ones without the 1 unit, and also they have better transparency than membranes containing 3-[tris(trimethylsiloxy)silyl]propyl methacrylate unit.     

Role of Tannin-Binding Salivary Proteins and Tannase-Producing Bacteria in the Acclimation of the Japanese Wood Mouse to Acorn Tannins

We studied the defense mechanisms against the negative effects of tannins in acorns by using the Japanese wood mouse (Apodemus speciosus) and acorns of a Japanese deciduous oak Quercus crispula, which contain 9.9% tannins on a dry weight basis. For the experiment, we allocated 26 wood mice into two groups: acclimated (N = 12) and nonacclimated (N = 14). Mice in the nonacclimated group were fed only acorns for 10 d after 4 wk of receiving a tannin-free diet. In contrast, mice in the acclimated group received ca. 3 g acorns daily in addition to the tannin-free diet for the first 4 wk, then they were fed only acorns for 10 d. Body weight, food intake, and digestibility were monitored. In addition, the amount of salivary proline-rich proteins (PRPs) and abundance of tannase-producing bacteria (TPB) in the feces of mice were measured. Of the 14 mice in the nonacclimated group, 8 died, whereas only 1 of the 12 in the acclimated group died. During the first 5 d of feeding acorns only, mice in the nonacclimated group lost, on average, 17.5% of their body mass, while those in the acclimated group lost only 2.5%. Food intake, dry matter digestibility, and nitrogen digestibility were higher in the acclimated group than in the nonacclimated group. The results indicate that wood mice can mitigate the negative effects of tannins by acclimation. Path analysis revealed that increased secretion of PRPs and abundance of Lactobacillus type of TPB might explain the acclimation to tannins.     

Effects of oxygen supply condition and specific biofilm interfacial area on phenol removal rate in a three‐phase fluidized bed bioreactor

The effects of oxygen supply conditions and specific biofilm interfacial area on the phenol removal rate in a three‐phase fluidized bed bioreactor were evaluated. The experimental data were well‐explained by the semi‐theoretical equation based on the assumption that the reaction rate follows first‐order reaction kinetics with respect to oxygen and zero‐order one with respect to phenol. Two cases, biological reaction as rate‐controlling step and oxygen absorption as rate‐controlling step, were both explicable by this semi‐theoretical equation. The maximum volumetric phenol removal rate was 27.4 kg·m^?3·d^?1.     

Influence of Synthesis Temperature on the Defect Structure of Boron Carbide: Experimental and Modeling Studies

Boron carbide (B₄C) was synthesized from the elements at temperatures ranging from 1300° to 2100°C using the spark plasma synthesis method. Significant densification commenced at about 1500°C and was accompanied by a corresponding decrease in the defect structure of this carbide. Changes in the X-ray diffraction patterns were in agreement with predictions of simulation studies based on the presence of twins. Transmission electron microscopy observations were consistent with the experimental observations and the modeling predictions.     

Growth,electronic properties and applications of nanodiamond

Nanodiamond or nanocrystalline diamond is a broad term used to describe a plethora of materials. It is generally accepted that nanocrystalline diamond (NCD) consists of facets less than 100 nm in size, whereas a second term “ultrananocrystalline diamond” (UNCD) has been coined to describe material with grain sizes less than 10 nm. These differences in morphology originate in the growth process. Conventional hydrogen rich gas phases produce facetted diamond with grain size proportional to film thickness and low sp² content. If these films are thin the grains can be less than 100 nm and hence NCD. By starving the plasma of hydrogen, the reduction in etching of sp² can lead to re-nucleation. At the extreme this results in very small grain sizes of around 3–5 nm, UNCD.The electronic properties of these two materials are vastly different. NCD is basically very thin microcrystalline diamond and thus can be doped with boron. It is intrinsically transparent, with absorption increasing with doping level. UNCD is highly absorbing due to its higher sp² content, and exhibits a reduced bandgap due to disorder. By adding nitrogen to the gas phase, the density of states within the bandgap increases and ultimately metallic conductivity can be achieved. This conductivity is n-type but not doping.     

Synthesis of bulk silicon oxynitride glass through nitridation of SiO2 aerogels and determination of Tg

The development of transparent glass for use in high-temperature applications is continuing. In this study, we synthesized bulk silicon oxynitride glasses (a-Si(O,N)_x) through the nitridation of SiO₂ aerogels containing methyl (CH₃-) groups and evaluated their bulk properties, including their glass transition temperature (T_g). Tetramethyl orthosilicate and methyltrimethoxysilane were added into the precursor gels, and those gels were subjected to a supercritical CO₂ drying process. The presence of CH₃-group in the gel avoided cracking during ammonolysis at 750°C–1400°C, and the transparency of the gel was remained even after ammonolysis at 1300°C. The ammonolysis successfully introduced nitrogen into the gels even at relatively low temperatures, for example, 750°C, and the highest nitrogen content (11.7 mass%) was achieved in the gel after ammonolysis at 1300°C. As the nitrogen-related signals in electron spectroscopy indicated presence of nitride ions (N³⁻) after ammonolysis and the infrared absorption signals attributed to Si–N bonds were enhanced with the increase of nitrogen concentration, we successfully obtained oxynitride glasses. Those oxynitride glasses showed increase of T_g with their nitrogen concentration.     

Calculation of transient puffer pressure rise takes mechanical compression, nozzle ablation, and arc energy into consideration

Thermal puffer-type gas circuit breaker (GCB) has a high dielectric and current interruption capability. In order to design a good thermal puffer GCB, it is important to know the blast pressure for arc cooling. Although pressure calculation programs have been developed and used for design work, the basic characteristics, such as contribution of nozzle ablation gas to puffer pressure rise, amount of back flow gas to puffer chamber, and pressure distribution along gas passages during current interruption, are not well known. In this paper, pressure rise, mass flow, and temperature calculations were carried out using a new calculation model, which takes mechanical compression by puffer piston, nozzle ablation in the nozzle throat and arc energy into consideration. By analysis of the calculation results, we found the pressure rise mechanism is as follows. While fixed contact located in the divergent part of nozzle, all of the ablation gas generated from the nozzle wall cannot be exhausted from the nozzle and it leads to high-pressure generation in the nozzle throat. This pressure causes transfer of hot ablation gas back to the puffer chamber via gas passage. The puffer pressure increases thermally due to temperature rise by this mechanism. At a longer arcing time, as high puffer pressure was already established in the puffer chamber, the nozzle ablation gas cannot flow back to the puffer chamber. Besides as mass flow through nozzle is limited by low gas density, the puffer pressure rise is obtained by the mechanical compression of puffer piston.