Thermotropic and Barotropic Phase Behavior of Phosphatidylcholine Bilayers

Bilayers formed by phospholipids are frequently used as model biological membranes in various life science studies. A characteristic feature of phospholipid bilayers is to undergo a structural change called a phase transition in response to environmental changes of their surroundings. In this review, we focus our attention on phase transitions of some major phospholipids contained in biological membranes, phosphatidylcholines (PCs), depending on temperature and pressure. Bilayers of dipalmitoylphosphatidylcholine (DPPC), which is the most representative lipid in model membrane studies, will first be explained. Then, the bilayer phase behavior of various kinds of PCs with different molecular structures is revealed from the temperature–pressure phase diagrams, and the difference in phase stability among these PC bilayers is discussed in connection with the molecular structure of the PC molecules. Furthermore, the solvent effect on the phase behavior is also described briefly.     

Fabrication and electrical properties of SrTiO3/diamond junctions

Strontium titanate (STO) films were directly deposited on Ib (100) single crystal diamond by r.f. magnetron sputtering. The as-deposited STO film was in amorphous state. On the other hand, the crystalline STO film was obtained under the optimized condition of a deposition temperature of 250 °C and a post-annealing temperature of 650 °C. STO/diamond junctions were fabricated on boron-doped homoepitaxial layers grown on p⁺-type single crystal diamond substrates. Electrical properties of the STO/diamond junction were investigated by changing the surface terminations of diamond with hydrogen or oxygen and the crystallinity of the STO film. It was found that the amorphous STO acted like a semi-insulator on H-diamond surface and that the amorphous STO/O-diamond junction behaved like a Schottky diode. The crystalline STO/O-diamond showed a complex rectifying behavior. The crystalline STO film possessed a higher dielectric constant as compared to that of the amorphous one.     

Slug to annular flow transition during boiloff in a rod bundle under high-pressure conditions

High-pressure boiloff experiments in a wide range of bundle powers by using the Two-Phase Flow Test Facility (TPTF) were conducted. Two kinds of boiloff patterns were observed in these experiments. One is the boiloff pattern in a low bundle power, in which the dryout points of rods locate at a certain elevation in the bundle because the mixture level controls the dryout points. The other is the boiloff pattern in a high bundle power, in which the clear mixture level can not be observed and the dryout points of rods locate in a wide range of vertical directions. The vertical scatter of the dryout points is considered to be due to the break of the thin water film on the heater rods under the annular flow pattern.A simple model to predict the slug to annular flow transition in the rod bundle is proposed. In the model, the slug to annular flow transition takes place when the interferences of the water films on the neighboring rods cease. The model appeares to give good predictions of the previous flow transition experiment conducted in a rod bundle. The slug-annular transition below the dryout points was predicted with the present model in the high power boiloff experiments of TPTF. No slug-annular transition below the dryout points is predicted with the present model in the low power boiloff experiments.     

Identification and field evaluation ofAnomala octiescostata (Coleoptera: Scarabaeidae) sex pheromone

Using GC-EAD, the sex pheromone of the scarab beetleAnomala octiescostata was identified to be a 8:2 binary mixture of (R,Z)-5-(–)-(oct-1-enyl)oxacyclopentan-2-one and (R,Z)-5-(–)-(dec-1-enyl)oxacyclopentan-2-one. These semiochemicals have been also reported as sex pheromone constituents of otherAnomala species, either geographically or seasonally isolated fromA. octiescostata. Synthetic sex pheromone was highly attractive in the field; 0.1 mg captured significantly more males than two virgin females. Buried traps were significantly more attractive than those positioned at 30, 90, and 150 cm above the ground. In a dose-response test (0.1–100 mg), no saturation due to overdose of pheromone was observed, but in most cases, two dosages differing by 10-fold were not significantly different. Response of males to traps baited with different ratios of the two components was tested in two experiments with randomized blocks and Latin-square designs. Deviation from the natural ratio (8:2) of sex pheromone did not significantly diminish the response of males. Peak flight activity of beetle was recorded at 9:00–10:00 AM JST on sunny days in the end of April 1993.Presented in part at the 10th Annual ISCE Meeting, July 31–August 4, 1993, Clearwater Beach, Florida.     

Segregation Effects at Grain Boundaries in Fluorite-Structured Ceramics

The atomic-scale structure, composition, and chemistry of grain boundaries in two fluorite-structured ceramic materials were characterized by a combination of Z -contrast imaging and electron energy-loss spectroscopy (EELS). In the case of a symmetric 24° [001] tilt bicrystal of yttria-stabilized-zirconia (YSZ), a shift in the zirconium M -edge onset and a change in the yttrium and zirconium M -edge ratios at the boundary indicate an increase in the number of electrons in the boundary plane. A detailed study of the structure and composition indicates that this is caused by an increase in the number of oxygen vacancies in the grain boundary core that is partially compensated by yttrium segregation. Studies of grain boundaries in an industrial Gd-doped ceria ceramic reveals similar changes in vacancy/dopant profiles indicating that these effects may be generic to grain boundaries in fluorite-structured materials.     

Characterization of plasma membrane proton-ATPase from salt-tolerant yeast Zygosaccharomyces rouxii cells

Plasma membrane was isolated from the salt-tolerant yeast Zygosaccharomyces rouxii and from Saccharomyces cerevisiae. The ATPase in the plasma membrane of Z. rouxii cells was a typical proton-ATPase as judged by testing with various ATPase inhibitors. There were slight differences in the pH optima of activities and in the sensitivity to sodium chloride (NaCl) and potassium chloride (KCl) of the ATPase from Z. rouxii and S. cerevisiae. The specific ATPase activity from Z. rouxii was higher in cells grown in a medium containing 2 _M-NaCl than in those not containing NaCl. No in vivo activation by incubation with glucose was observed in Z. rouxii cells and the specific ATPase activity was independent of the growth phase, unlike S. cerevisiae cells.     

Determination of optimal sending voltage profile in distribution systems with distributed generators

Sending voltage profile of distribution feeder is controlled by changing a tap of distribution transformer. In a distribution network with distributed generators, for reasons of effect of reversed flows from them and existence of a great number of sending voltage profile candidates, it is not easy to control sending voltage profile within the acceptable voltage limit. In this paper, in order to determine the optical sending voltage profile of distribution transformer in a distribution network with distributed generators, the authors propose a new method to determine the optimal sending voltage profile so as to minimize the total number of tap position's change per day under constraints of acceptable voltage limit. In the proposed method, after calculating acceptable range of three‐phase voltage of distribution feeder, the optimal profile of tap position within the calculated acceptable voltage range is determined among these candidates by using reduced ordered binary decision diagram (ROBDD) which is an efficient enumeration algorithm. In order to check the validity of the proposed method, numerical simulations are carried out for a distribution network model with a distributed generator. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(2): 16–24, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20393     

The influence of mash pre-aging on the development of the flavour-active compound, 4-hydroxy-2(or5)-ethyl-5(or2)-methyl-3(2H)-furanone (HEMF), during soy sauce fermentation

Inoculation of Zygosaccharomyces rouxii into a soy sauce mash free from lactic acid bacteria at 10⁶ cells mL⁻¹ resulted in the formation of the flavour-active compound HEMF over a number of days at 30°C. Delays in inoculation up to 14 days after production of the mash greatly increased the amount of HEMF formed and under some conditions concentrations in the commercial range were achieved without addition of any other microorganisms.     

Effects of boron doping in low- and high-surface-area carbon powders

Two distinctive carbon materials (Saran char and SP-1 graphite) were doped with B at different loading to clarify the intrinsic effect of substitutional B on carbon reactivity. The carbon precursors would be affected in different style by substitutional B due to different important properties (crystallinity and surface area). The B retentivity depended on the nature of B dopant and carbon substrate; a less ordered carbon has higher B loading than its counterpart. Graphitization was enhanced by substitutional B, as expected. Furthermore, the B incorporation was still beneficial for SP-1 although it already had high crystallinity. An interesting behavior was noticed; the increase in L_a was greater than L_c. The intrinsic effect of substitutional B in carbon oxidation was proved to be a catalytic one. Unlike highly ordered SP-1 graphite, Saran char showed both a catalytic effect at low B loading and low conversion, and an inhibiting effect at high B loading and high conversion. The inductive effect was proposed to explain this catalytic effect on different crystallite size. Different sizes of carbon clusters were calculated by Gaussian 98W; the extent of the effect of substitutional B did get smaller to the carbon in bigger size of carbon cluster.     

Reactive carbon black having isocyanate or acyl azide group

Summary Introduction of isocyanate (NCO) group onto carbon black surface was achieved by the treatment of carbon black with toluene-2,4-diisocyanate. In addition, carbon black having acyl azide (CON₃) group, a precursor of NCO group, was prepared by the reaction of COCl or COOCOOC₂H₅ group on carbon black with NaN₃. The CON₃ group on carbon black was relatively stable at below 20°C but readily decomposed to NCO group by heating (Curtius rearrangement). By the reation of NCO group on carbon black with hydroxyl group of polymers, such as polypropylene glycol, polyethylene glycol, and polyvinyl alcohol, these polymers were found to be grafted onto carbon black.