Fragmentation of the large subunit of ribulose-1,5-bisphosphate carboxylase by reactive oxygen species occurs near Gly-329

The large subunit (LSU) of ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) in the illuminated lysates of wheat (Triticum aestivum L.) chloroplasts is broken down by reactive oxygen radicals into 37- and 16-kDa polypeptides. Analysis of the terminal amino acid residues of both fragments revealed that the C terminus of the 37-kDa fragment was Ser-328 and the N terminus of the 16-kDa fragment was Thr-330. Gly-329, which links the two fragments, was missing, suggesting that the fragmentation of the LSU in the lysates driven by oxygen-free radicals occurs at Gly-329. Purified rubisco, exposed to a hydroxyl radical-generating system, was also cleaved at the same site of the LSU. The cleavage site was positioned at the N-terminal end of the flexible loop (loop 6) within the beta/alpha-barrel domain, constituting the catalytic site of rubisco. The binding of a reaction intermediate analogue, 2-carboxyarabinitol 1,5-bisphosphate, to the active form of rubisco completely protected the enzyme from the fragmentation. The fragmentation was differentially affected by CO2, Mg2+, ribulose 1, 5-bisphosphate, or 2-carboxyarabinitol 1,5-bisphosphate. All these results indicate that the conformation of the catalytic site of the enzyme is involved as an important factor determining the breakdown of rubisco by reactive oxygen species. Reactive oxygen species generated at its catalytic site by a Fenton-type reaction may trigger the site-specific degradation of the LSU in the lysates of chloroplasts in the light.     

An investigation into the temperature sensitivity of strained andunstrained multiple quantum-well, long wavelength lasers: new insightand methods of characterization

The magnitude of the temperature rate of change of the threshold current density (J_th) is examined with respect to J_th , for a variety of unstrained and strained, long wavelength multiple quantum-well (MQW) lasers. A strong correlation is found between these parameters, and a new relationship describing the J_th -T relationship for these lasers is arrived at in terms of two new essentially temperature and length independent constants. A third constant, T_max, also appears which estimates the theoretical maximum operating temperature of the laser. It is proposed that these constants may prove to be more useful in characterizing the temperature sensitivity of semiconductor lasers than the conventional parameters T ₀ and I₀ which exhibit both a length and temperature dependence. Furthermore, an expression is found which relates the magnitude of T_max to adjustable device structural and material parameters, such as: the cavity length, L; facet reflectivity, R; transparency current density, J_tr; and, the modal gain coefficient, β. It is revealed that a close examination of this relationship may provide new insight into the physics of semiconductor lasers as well as a means for optimizing device design to obtain a high maximum operating temperature in order to eliminate the need for thermoelectric coolers in device packaging. Finally, the measured T_max, versus L characteristics of six different strained and unstrained MQW laser structures are presented     

Protective layer for high‐efficiency PDPs driven at low voltage

Abstract— The sustain pulse voltage of a panel for 66‐kPa Ne + Xe (5–30%) with an (SrCa)O protective layer is 20–40% lower than that with an MgO protective layer. The luminous efficiency of the panel with a Ne + Xe (30%) (SrCa)O protective layer is 1.5 times that of the conventional panel with a Ne + Xe (10%) MgO protective layer; the sustain pulse voltages of these panels are almost the same. The power loss caused by panel capacitance is proportional to the second power of the sustain pulse voltage. Using the (SrCa)O protective layer for Xe (5–30%), the power loss is reduced by 35–60% compared with the MgO protective layer. It follows that, using the (SrCa)O protective layer, we can increase the Xe content with little power loss and thus achieve high‐efficiency PDPs. As for MgO and CaO with Xe ions, electrons are probably ejected from only the defect states. On the other hand, as for the SrO with Xe ions, it is likely that electrons can be ejected from not only defect states but also the valance band. This seems to be the reason why the driving voltage is lower with the (SrCa)O protective layer than with the MgO protective layer.     

Therapeutic effects of prostacyclin analog on crescentic glomerulonephritis of rat

Prostacyclin (PGI2) is known to have a relaxative action on vascular smooth muscle, an inhibitory action against platelet activation and neutrophil function. Previous studies showed the preventive effects of PGI2 on lupus nephritis and Thy-1 nephritis, although the mechanism has not been clarified. Glomerular endothelial expression of intercellular adhesion molecule-1 (ICAM-1) is up-regulated in experimental and human glomerular diseases, and is known to facilitate leukocyte infiltration into the glomeruli, which ultimately induces the various glomerular injuries. In the present study, we evaluated the therapeutic effects of PGI2 on a rat model for crescentic glomerulonephritis and investigated its putative mechanism in relation to ICAM-1-mediated leukocyte recruitment. Wistar-Kyoto (WKY) rats were injected with nephrotoxic serum and received continuous intraperitoneal infusion of PGI2. PGI2 dramatically decreased proteinuria (123.0 +/- 18.8 vs. 31.6 +/- 4.5), crescent formation and deposition of fibrinogen in the glomeruli, while the deposition of rabbit IgG, rat IgG and rat C3 along the capillary walls was not changed. Furthermore, intraglomerular expression of ICAM-1 and infiltration of macrophages were significantly suppressed by administration with PGI2. In contrast, influx of CD4 or CD8 positive cells was not altered. The present results suggest that PGI2 shows the preventive effects on experimental crescentic glomerulonephritis by inhibiting intraglomerular coagulation and ICAM-1-mediated macrophage-glomerular endothelial cell adhesive pathway.     

Theory of powdered metal formation in electrochemistry—morphological instability in galvanostatic crystal growth under diffusion control

Following the presentation of the theory of powder formation in steady state electrocrystallization, some equations based on the linear instability theory in non-steady state deposition under diffusion control were derived; the galvanostatic case was then analysed using the theoretical equations obtained here.As a result, the dependences of powder growth and particle size on various physical parameters, such as current density, bulk concentration and temperature, were made quantitatively clear. Furthermore, a reliable basis was given to the induction time of powder formation which had formerly been liable to amibiguous discussion.     

Resistivity changes of heavily-boron-doped CVD-prepared polycrystalline silicon caused by thermal annealing

Heavily-boron-doped polycrystalline Si films were deposited at 600°C on thermally grown SiO₂ by the thermal decomposition of SiH₄-BCl₃-H₂ mixture. Resistivity changes with isochronal or sequential annealing were systematically examined. Temperature dependence of equilibrium saturation carrier concentration was determined at 800 ～ 1100°C. Since as-deposited polycrystalline Si is in the super-saturated state, carrier concentration decreases from the super-saturated to equilibrium saturation value by annealings over 700°C for poly Si doped with over 2 × 10²⁰ cm^?3 resulting in anomalous resistivity change. Carrier concentration changes reversibly between saturation values with sequential annealing and is determined by the last annealing temperature when the annealing time is long enough. Mobility increases with annealing temperature, however, less increase is found for heavily doped poly Si, which is attributed to the suppression of grain growth caused by electrically inactive Si-B compounds.     

Determination of magnetic anisotropy constants for bubble garnet epitaxial films using field orientation dependence in ferromagnetic resonances

Cubic magnetocrystalline anisotropy constant K₁ as well as uniaxial anisotropy constant K_u and gyromagnetic ratio γ are precisely determined for (111) magnetic garnet epitaxial films from measurements on FMR field orientation dependence. Strict FMR conditions are derived from total free energy expressions, where the differences between magnetization direction and applied field direction are taken into consideration. By applying magnetic field in (110) plane, FMR is measured to obtain the three best fitting parameters of K₁, K_u and γ. Present analysis is compared with Cronemeyer et al's analysis. Influence of sample misalignment on measurement accuracy is also presented. Similarly, for (110) garnet films with orthorhombic magnetic anisotropy, measurements are carried out for two crystallographic planes of (001) and (110), and the four best fitting parameters of K₁, K_u, δ and γ are determined.     

Discrimination of psychoactive fungi (commonly called "magic mushrooms") based on the DNA sequence of the internal transcribed spacer region

'Magic mushrooms' (MMs) are psychoactive fungi containing the hallucinogenic compounds, psilocin (1) and psilocybin (2). Since June 6, 2002, these fungi have been regulated by the Narcotics and Psychotropics Control Law in Japan. Because there are many kinds of MMs and they are sold even as dry powders in local markets, it is very difficult to identify the original species of the MMs by morphological observation. Therefore, we investigated the internal transcribed spacer (ITS) region in the ribosomal RNA gene of MMs obtained in Japanese markets to classify them by a genetic approach. Based on the size and nucleotide sequence of the ITS region amplified by PCR, tested MMs were classified into 6 groups. Furthermore, a comparison of the DNA sequences of the MMs with those of authentic samples or with those found in the databases (GenBank, EMBL and DDBJ) made it possible to identify the species of tested MMs. Analysis by LC revealed that psilocin (1) was contained at the highest level in Panaeolus cyanescens among the MMs, but was absent in the Amanita species.     

A real-time intelligent gas sensor system using a nonlinear dynamic response

We developed an intelligent gas sensor system for discrimination and quantification of gases by a single semiconductor gas sensor in real-time. This system is based on the information embedded in a nonlinear dynamic response. By applying a sinusoidal voltage to a heater attached to a sensing material, a characteristic time-dependent trace of the sensor resistance is obtained as a response to environmental gases. In order to evaluate the characteristic response in a quantitative manner, fast Fourier transformation (FFT) was performed for the dynamic response. Higher harmonics, obtained by performing FFT, were processed by using a discrimination method and a multiple regression. It is possible for the system to respond in the time order of several seconds. The physico-chemical meaning of the response was also discussed.