Chr4, a Schizosaccharomyces pombe homologue of the Saccharomyces cerevisiae Chs4p/Skt5p protein, is related to septum formation and is required for the proper localization of Chs2

In Saccharomyces cerevisiae, Chs4p directly interacts with chitin synthase III (Chs3p) to act as a post-translational regulator of the Chs3p complex. We identified four Chs4p homologous proteins in Schizosaccharomyces pombe which we named Chr1, Chr2, Chr3 and Chr4 (putative chitin synthase regulatory factor). We assessed the functions of these proteins and found that while overproduction of Chr1, Chr2 or Chr3 did not affect the cellular morphology of wild-type Sz. pombe cells, overproduction of Chr4 caused the cells to form multi-septa and delayed their growth. All multiple disruptants of chr1, chr2, chr3 and chr4 grew normally under a variety of growth conditions. However, while chitin synthase II (Chs2) normally localizes exclusively at the septum, in many chr4-disrupted cells it was found in the cytoplasm and the septa. Chs2 did localize at the abnormal septa caused by the overproduction of chr4+. Chr4-13Myc expression was unaffected by the different media or growth conditions in both wild-type and the chs2 disruptant. Chs2 expression was also unaltered by the absence of Chr4. Moreover, Chr4-13Myc localized mostly at the tips and the septum during vegetative growth in chs2, chr1, chr2 and chr3 disruptants as well as in wild-type. Thus, chr4+ is involved in septum formation and is required for the proper localization of Chs2 at the septum in Sz. pombe.     

Isolation of a novel alkaline-induced laccase from Flammulina velutipes and its application for hair coloring

Laccase is a member of the multi-copper oxidase family and a promising for hair coloring. In this study, we isolated a novel alkaline-induced laccase from the white-rot fungus Flammulina velutipes and studied the possibility to apply the enzyme for hair coloring. Laccase activity detected in the culture supernatant of F. velutipes was found to significantly increase when exchanging the medium to laccase inducing one whose pH was adjusted to 9.0. Three isozymes were detected by activity staining on non-denaturing SDS-PAGE. The major isozyme, Flac1, was purified from the culture supernatant after being induced at pH 9.0 by ion-exchange column chromatography. The N-terminal peptide sequence of Flac1 was determined, revealing clear homology with laccases from other white-rot fungi. Optimum pH of oxidation was found to be around pH 5.0-6.5 regardless of several different substrates used. Oxidation activities of Flac1 to several hair dye agents as substrate showed the higher activity at pH 6.5 than that at pH 9.0. Oxidation activity was also detected at pH 9.0 which was suitable for hair coloring. When the purified Flac1 was applied for hair coloring system without using hydrogen peroxide, effective coloring was observed at the protein amount of 0.25mg/1g of hair used. These results indicated that this alkaline-induced novel laccase isolated from the culture supernatant of F. velutipes might be a useful enzyme for hair color.     

Microstructural development and radiation hardening of neutron irradiated Mo-Re alloys

Stress-relieved specimens and recrystallized specimens of pure Mo and Mo-Re alloys with Re contents of 2, 4, 5, 10, 13 and 41 wt% were neutron irradiated up to 20 dpa at temperatures from 681 to 1072 K. On microstructural observation, sigma phase and chi phase precipitates were found in all irradiated Mo-Re alloys. Voids were observed in all irradiated specimens, and dislocation loops and dislocations were observed in the specimens that were irradiated at lower temperatures. On Vickers hardness testing, all of the irradiated specimens showed hardening. Especially Mo-41Re were drastically embrittled after irradiation at 874 K or below. From these results, the authors discuss about the relation between microstructure development and radiation hardening and embrittlement, and propose the optimum Re content and thermal treatment for Mo-Re alloys to be used under irradiation conditions.     

A new evaluation method of surface energy of ultra-thin film

A new method is proposed for evaluating the dispersive component of the effective surface energy of an ultra-thin film. The dispersive component is obtained by introducing a cut-off distance and integrating the corrected van der Waals pressure equation for a symmetric multilayer system. The cut-off distance is calculated using the experimentally determined surface energy of the substrate without an ultra-thin film. A stearic-acid Langmuir–Blodgett film on a glass plate was used as an ultra-thin film sample on a solid substrate. The dependences of the surface energy on the ultra-thin film thickness were investigated experimentally and theoretically, and the effectiveness of this method is discussed.     

Microstructures formed by secondary growth of fired ZSM-5 seed crystals

Oriented ZSM-5 seed crystals on an α-Al₂O₃ porous substrate were hydrothermally treated in a raw sol. The ZSM-5 membranes were fabricated via secondary growth of the seed crystals. For some samples, the seed-applied substrate was fired at 300 or 600 °C before the secondary growth in order to enhance adhesion between the substrate and the seed crystals. The influence of the firing on the subsequent secondary growth of the seed crystals was examined by XRD, SEM, and TEM. The TEM images of the sample fired at 300 °C showed that the resulting membrane was continuous, and in the membrane, large ZSM-5 particles were distributed in a porous matrix. The ZSM-5 particles were slightly smaller than the used seed crystals. HR-TEM observations showed that the porous matrix is comprised of ZSM-5 micro-crystals, and the part adjacent to the large ZSM-5 crystals has the same crystallographic orientation as the large crystals. The TEM images of the sample fired at 600 °C showed that the resulting layer is comprised of particles with a core-shell structure. The core consisted of ZSM-5 micro-crystals, whereas the shell was composed of large ZSM-5 rod-like crystals. It is inferred that the formation of these interesting microstructures is related to the degradation of the template agent, NPr₄OH, in the seed crystals by firing at 300 and 600 °C. The part including no template is dissolved by a hydrothermal treatment, and the dissolved species is re-crystallized via reaction with a template agent in the used raw sol, resulting in the formation of interesting microstructures.     

Senescence of spatial chromatic contrast sensitivity. II. Matching under natural viewing conditions

Age-related changes in the spatial chromatic contrast sensitivity function of detection, measured along S and L - M cone axes, were demonstrated in a companion paper [Hardy et al., J. Opt. Soc. Am. A 22, 49 (2005)]. Here senescent changes in chromatic contrast appearance were assessed by contrast-matching functions (CMFs). Luminance and chromatic CMFs (S and L - M axes) were compared for younger (age 18-31 yr) and older (age 65-75 yr) trichromatic subjects by using stimuli that were perceptually anchored to the same physical standard contrasts. Subjects matched the contrast of test gratings of various spatial frequencies (0.5-8 cycles per degree) to the standard stimuli under natural viewing conditions. Because of changes in the visual system with age, the standard stimuli were closer to threshold for older subjects; however, in general, the shapes of the CMFs were similar for both groups. The results suggest that the perception of relative contrasts across spatial frequencies is stable with age.     

Trapezoidal Modulating Signal for Three-Phase PWM Inverter

Trapezoidal wave is suitable for the modulating signal of the microcomputer-based pulsewidth modulation (PWM) inverter for the use of motor drives because the switching patterns can be generated by means of on-line computation. The waveform is changed from a rectangular to a triangular wave.