16O+16O molecular structure and superdeformation in 32S

The molecular structure with the ¹⁶O+¹⁶O configuration in ³²S and the superdeformed structure in ³²S are discussed from the viewpoint of the cluster model.     

Kinetics of the esterification of palmitic acid with isobutyl alcohol

Kinetics of the sulfuric acid catalyzed esterification of palmitic acid with isobutyl alcohol has been studied and reviewed critically. A theoretical rate equation is derived by the following reaction mechanism: (1) The reaction of sulfuric acid and isobutyl alcohol produces isobutyl sulfuric acid which acts as a catalyst; (2) Palmitic acid is protonated by the catalyst to form the reaction intermediate; and (3) The esterification proceeds reversibly. The experimental results are consistent with this rate equation.     

Command surfaces 12 [1]. Factors affecting in-plane photoregulation of liquid crystal alignment by surface azobenzenes on a silica substrate

In-plane alignment of nematic liquid crystals was regulated by polarized-light-irradiation of a cell assembled with a silica plate, the surface of which was modified by attaching 4-hexyl-4'-hexyloxyazobenzene at its o-position through surface silylation. The photoisomerizability of the chemisorbed azo-chromophore was affected by their surface density and the nature of photoinactive co-modifiers. The efficiency of the photoregulation of liquid crystal alignment was optimized by two-dimensional dilution of the chromophore with ethyltriethoxysilane (ETS) or 3-aminopropyltriethoxysilane (ATS). As a result, favourable procedure was to modify a silica surface with a crude azo-silylating reagent contaminated by ATS. The rate of the photoinduced reorientation of liquid crystals was followed by monitoring the alteration of the alignment direction of a dichroic dye dissolving in a mesophasic layer upon exposure to linearly polarized light. Exposure energy for the in-plane reorientation of a liquid crystal was about 100mJcm^-2 of 445 nm light at elevated temperatures close to T_NI. The effect of positional isomerism on the photoregulation was determined with the use of 4-cyano-4'-hexyloxyazobenzene as a commander molecule. It was confirmed that the photoalignment efficiency was markedly enhanced by attaching the chromophore at the ortho- or meta-position. The exposure energy for the reorientation of a liquid crystal was reduced by linking the p-cyanoazobenzene at the meta-position so that the reorientation was complete with an exposure energy of 20mJcm^-2.     

A study on correlation between physical properties and interfacial characteristics in highly loaded graphite–polymer composites

Highly loaded graphite–polymer composites for a bipolar plate of polymer electrolyte fuel cell are studied. One of the composites contains of polypropylene (PP), and graphite powder and the other contains of poly(vinylidene fluoride) (PVDF) and the graphite, respectively. The electrical and physical properties for the composites are determined. Inverse gas chromatography (IGC) measurements are carried out to characterize the surface of the graphite and the interface between the graphite and each polymer, following the Fowkes scheme. The IGC measurements show that the surface of graphite is nucleophilic and strongly attracts electrophiles by acid–base interaction. It is considered to be reasonable that the main chain carbon atoms to which electronegative fluorine atoms bond in PVDF are nucleophilic and has strong acid–base interaction with graphite. Such strong interaction causes high electric resistivity, high flexural properties, and high melt viscosity of the composite. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2568–2577, 2005     

Luminescence of high density electron-hole plasma in CdSe at elevated temperature

Luminescence of high density electron-hole plasma in CdSe is observed in the 77–300 K temperature range by picosecond pulse excitation. With increasing temperature from 77 K the stimulated emission band is replaced by the spontaneous emission band. Temperature changes of spectral features of these two bands and also their time dependence after pulse excitation are consistent with the theoretical consideration.