Pressure-induced activation and pressure-tolerance of mutated thermolysin at 119

Abstract

The pressure activation of thermolysin substitution at the 119th site was studied for four mutants and the wild type (Q119Q. Q119N, Q119R, Q119E and Q119D). The highest activation recorded over 30 fold and the activation volumes (ΔV?) were about -75ml/mol for Q119Q, Q119N and Q119R, while Q119E and Q119D showed only a10 fold activation and ΔV? of around -6Oml/mol. The pressure-tolerance of these enzymes were investigated through the in situ observation of their intrinsic fluorescence. Q119E and Q119D showed smaller ΔG _app and ΔG _app of transition than the wild type.     

Ultrahigh heat transfer enhancement using nano-porous layer

Heat transfer enhancement is one of the key issues of saving energies and compact designs for mechanical and chemical devices and plants. We discover an ultrahigh convective heat transfer performance compared to the well-known heat transfer correlations caused by a nano-particle porous surface: the maximum increase of heat transfer coefficient was around 180%. This nano-particle porous layer can be formed on the substrate surface by an etching with some acids or alkalis including around 100 nm size nano-particles made from copper oxide, carbon nano-tube and aluminium oxide. Moreover, we have done some experiments using a co-current flow heat exchanger consisting of hot and cold water-channels and obtained an ultrahigh heat transfer performance: over 200% increase compared to the conventional correlation. On the other hand, in order to theoretically investigate effects of nano-particle porous layer structures on the surface energy transfer, the energy transfer from fluid to the heat transfer surface is calculated by a classical molecular dynamics method. Energy transfer to the surface from the fluid strongly depends on the surface structures in nanometre scale that affect the static structure and dynamic behaviours of fluid molecules in the vicinity of the surface.     

Effects of pressure on the behavior of (hydroxypropyl)cellulose in aqueous solution

The effects of pressure and temperature on the phase behavior of aqueous solutions of (hydroxypropyl)cellulose (HPC) were in¶vestigated at low and high concentrations. In dilute solutions, the transition temperature (T _t) as measured by apparent light scattering increased with an increase in pressure at lower pressures, but decreased with increasing pressure above 100?MPa. At lower temperatures, the transition pressure (P _t) increased slightly with increasing temperature, but decreased with at temperatures above 10–15?°C. Both T _t and P _t showed a moderate polymer-concentration dependence and they also showed strong concentration dependence on salt; T _t and P _t decreased with increasing concentrations of KCl and K₂SO₄, whereas the addition of KI or KSCN increased T _t and P _t. The apparent absorbance of concentrated solutions (62.5%) of HPC, in a cholesteric (chiral nematic) mesophase, was also measured. The spectrum shifted to a longer wavelength under high pressure. These results could be explained by assuming that the helicoidal pitch was increased under elevated pressure, probably due to a decrease in the angle between the two semiflexible and twisted HPC molecules in adjacent planes under high pressure.     

2,7-Diphenyl[1]benzothieno[3,2-b]benzothiophene, a new organic semiconductor for air-stable organic field-effect transistors with mobilities up to 2.0 cm2 V(-1) s(-1)

Vapor-deposited thin films of a newly developed sulfur-containing heteroarene, 2,7-diphenyl[1]benzothieno[3,2-b][1]benzothiophene (DPh-BTBT), were used as an active layer of OFETs, which showed excellent FET characteristics in ambient conditions with mobilities of approximately 2.0 cm2 V-1 s-1 and Ion/Ioff of 107.     

Synthesis of silicon‐bridged polythiophene derivatives and their applications to EL device materials

Palladium‐catalyzed oxidative homo‐coupling of 2,6‐bis(tributylstannyl)dithienosiloles with CuCl₂ afforded poly(dithienosilole‐2,6‐diyl)s as novel polythiophene derivatives with intra‐chain silicon bridges, which exhibited red‐shifted UV absorption maxima by about 100 nm from those of the corresponding silole‐free polythiophenes. Alternate copolymers also were prepared by palladium‐catalyzed cross‐coupling reactions of 2,6‐dibromodithienosiloles with distannylthiophene or bithophene. These polymer films were applied to single and double‐layered organic electroluminescence devices. It was found that some of the resulting polymers exhibited electroluminescence properties and emitted red light in EL devices with the structure of ITO/polymer/Mg‐Ag. Introducing an electron‐transporting Alq3 layer between the polymer film and the Mg‐Ag cathode led to a remarkable improvement in the devices performance. An application of the copolymer to a field effect transistor was also studied. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4588–4596, 2007     

Elastic properties of Se and As2Se3 glasses under pressure and temperature

The sound velocities and their pressure and temperature variations of Se and As₂Se₃ glasses have been determined by means of a pulse superpositions method, and other elastic constants and their pressure and temperature derivatives were calculated from these data. The bulk modulus was found to be 94·6 kbar for Se glass and 143·7 kbar As₂Se₃ glass, both of which are higher than the values calculated from the previous compression data. No anomaly was observed in any of the pressure and temperature dependence of elastic behavior of these glassses. Furthermore, the comparison of the pressure and temperature derivatives of the bulk modulus indicates that the thermodynamic self-consistency is satisfied on these materials. The bulk moduli of these glasses and crystalline As and Se were used to obtain an empirical bulk modulus-volume relationship for compounds in the As?Se system. The acoustic Grüneisen parameter was calculated and compared with the thermal Grüneisen parameter.     

Adsorption-induced bending of polypyrrole films and its application to a chemomechanical rotor

We have discovered that polypyrrole films undergo rapid and intensive bending in the solid state. Bending was induced by the reversible and anisotropic adsorption of various substances in the vapor state. The speed and direction of bending largely depended on the adsorbate used. By using this phenomenon, we have devised an experimental “chemomechanical rotor” capable of transducing a chemical free energy change directly into a continuous rotation. © 1996 John Wiley & Sons, Inc.     

Abnormalities of cerebral blood flow in multiple sclerosis: A pseudocontinuous arterial spin labeling MRI study

Arterial spin labeling (ASL) is a noninvasive technique that can measure cerebral blood flow (CBF). To our knowledge, there is no study that examined regional CBF of multiple sclerosis (MS) patients by using this technique. The present study assessed the relationship between clinical presentations and functional imaging data in MS using pseudocontinuous arterial spin labeling (pCASL). Twenty-seven patients with MS and 24 healthy volunteers underwent magnetic resonance imaging and pCASL to assess CBF. Differences in CBF between the two groups and the relationships of CBF values with the T2-hyperintense volume were evaluated. Compared to the healthy volunteers, reduced CBF was found in the bilateral thalami and right frontal region of the MS patients. The volume of the T2-hyperintense lesion was negatively correlated with regional CBF in some areas, such as both thalami. Our results suggest that demyelinated lesions in MS mainly have a remote effect on the thalamus and that the measurement of CBF using ASL could be an objective marker for monitoring disease activity in MS.