Effect of cholesterol and other additives on viscosity, self-diffusion coefficient, and intramolecular movements of oleic acid

It has been empirically known that cholesterol largely increases the viscosity of oleic acid. To clarify the mechanism of the effect of cholesterol on the intermolecular and the intramolecular (segmental) movements of oleic acid in the liquid state, we measured density, viscosity, IR, 1H NMR chemical shift, self-diffusion coefficient, and 13C NMR spin-lattice relaxation time for the liquid samples of oleic acid containing a small amount of cholesterol. Furthermore, the above measurements were also carried out for the samples of oleic acid containing a small amount of cholestanol, cholestane, cholesteryl oleate, ethanol, or benzene. Cholesterol, possessing one OH group and one double bond in its molecular structure, largely increased the viscosity and reduced the self-diffusion and the intramolecular movement of oleic acid. Cholestanol, possessing one OH group but not a double bond, and cholesteryl oleate, not possessing an OH group, also reduced the self-diffusion and the intramolecular movement; cholestane, not possessing an OH group, slightly reduced the self-diffusion and the intramolecular movements. In contrast with these sterols, ethanol and benzene reduced the viscosity and increased the self-diffusion and the intramolecular movements. In addition, cholesterol and ethanol, both having one OH group, promoted the upfield shift of the 1H NMR signal of the carboxyl group of oleic acid; IR difference spectra for the cholesterol/oleic acid system quite resemble those for the ethanol/oleic acid system. These results suggest that oleic acid makes a complex with cholesterol as well as with ethanol. On the basis of the formation of the complex, we have revealed the role and the functional mechanism of cholesterol to the intermolecular and the intramolecular movements of oleic acid in the liquid state.     

Precision Evaluation in Kr Adsorption for Small BET Surface Area Measurements of Less Than 1 m2

A volumetric Kr-adsorption apparatus using a precise capacitance manometer has been developed. A specially designed adsorption cell (CVC: constant volume adsorption cell) utilizing a vacuum jacket (Joyner et al., 1949) is adopted to keep the adsorption cell volume constant regardless of the variation in liquid nitrogen level throughout the experiment. Using the CVC, the pressure change in accordance with liquid N₂ supply cycle has been minimized to less than 0.01 Pa compare to about 1 Pa for conventional cell. Time dependent change of the adsorption cell volume and repeatability in its measurements have been demonstrated in detail using helium gas. Good linearity of the BET plot of the Kr adsorption isotherm on several hundred cm² samples are demonstrated in the relative pressure range from 0.05 to 0.35.     

Compact and large depth of field image scanner for auto document feeder with compound eye system

We designed a compact and large depth of field image scanner targeted for auto document feeders (ADF) by using a compound eye system design with plural optical units in which the ray paths are folded by a reflective optics. Though we have previously proposed the principle concept, we advance the design using a free-form surface mirror to reduce the F-number for less illumination energy and to shrink its optical track width to 40 mm. We achieved large depth of field (DOF) of 1.2 mm, defined as a range exceeding 30% modulation transfer function (MTF) at 300 dpi, which is about twice as large as a conventional gradient index (GRIN) lens array contact image sensor (CIS). The aperture stop has a rectangular-shaped aperture, where one side length is as large as 4.0mm for collecting much light, and another side length is as small as 1.88mm for avoiding interference of folded ray paths.     

Mechanical denaturation of high polymers in solutions XXIX. Stress-induced crystallization of poly(vinyl alcohol) from its aqueous solution under steady-state flow

The crystallization of poly(vinyl alcohol), derived from its aqueous solution was carried out under a steady-state flow. The effect of the rate of stirring on the crystallization and details of several phenomena observed in stirred solutions during crystallization are presented. Moreover, the structure of crystallized poly(vinyl alcohol) was studied with use of an electron microscope. Evidence is presented for a crystal morphology that includes smooth fibrils and the absence of lamellar overgrowth, i.e., no shish kebabs.     

Comparative Study of Mixed Monolayers of a Calixarene with a Fatty Acid and a Non-Amphiphilic Nematic Liquid Crystal

Abstract

Many nematic liquid crystals (NLCs) lack a polar headgroup and thus are not able to form stable monolayers at the air/water (a/w) interface. A way to obtain monomolecular films of these compounds is to incorporate them into host monolayers of amphiphilic molecules. We report a comparative investigation of mixed films of Calix[4]resorcinarene O-octacarboxymethylated (CRO) with the non-amphiphilic NLC MBBA and with the amphiphilic stearic acid (SA). The comparative study is useful for a better understanding of the characteristics of the CRO-MBBA mixed films. Surface-pressure and surface-potential measurements on the monolayers at a/w interface, as well as ellipsometric and spectroscopic measurements on transferred Langmuir-Blodgett (LB) films, confirm that MBBA is additively incorporated into CRO films.     

The lowest metal-to-bipyridine charge-transfer excited state of [Cr(2,2′-bipyridine)(CO)4]

The DV-Xα molecular-orbital calculations have been carried out on [Crbpy(CO)₄](bpy,2,2′-bipyridine) and its electron attachment and detachment products. The one-electron attachment of [Crbpy(CO)₄] yields a complex of bipyridine anion radical, while the one-electron detachment results in ionization of the central metal atom. The lowest excited state of [Crbpy(CO)₄] is the metal-to-ligand charge-transfer (MLCT) excited state which consists of the bipyridine anion radical and the central metal ionized. The transition-state calculation predicts the lowest MLCT excited states at around 23～30×10³ cm^?1 and the lowest bipyridine (π,π^*) excitations at 36×10³ cm^?1 and 42～45×10³ cm^?1. The calculation also concludes that the MLCT excitation induces a counter migration of the other electrons not directly involved in the charge-transfer excitation. The configuration-interaction calculations predict the lowest MLCT excited singlet states at around 21～35×10³ cm^?1 and the lowest bipyridine (π, π^*) excited singlet states at 42～62×10³ cm^?1, while the emissive lowest MLCT triplet state is at 17×10³ cm^?1. The transition moments evaluated with the transition-state wavefunctions can reproduce qualitatively the observed absorption spectral profile. The intensity of the MLCT transitions is obtained from the allowed (π, π^*) transitions of coordinated bipyridine but is not due to the intrinsic transition moments of MLCT excitations.     

Structure of Be Hyper Isotopes

The low-lying level structure of ${^{10}_\Lambda{\rm Be}}$ and ${^{12}_\Lambda{\rm Be}}$ has been studied by using the antisymmetrized molecular dynamics for hypernuclei (HyperAMD). In these hypernuclei, it is interesting to reveal the changes of excitation spectra by adding Λ hyperon, because the ground and low-lying states with different deformation coexist in ⁹Be and ¹¹Be. Based on the HyperAMD calculation, it is found that the first excited state 1/2⁺ of ⁹Be is shifted up by about 700 keV in ${^{10}_\Lambda{\rm Be}}$ . In ${^{12}_\Lambda{\rm Be}}$ , the parity-inverted ground state of ¹¹Be is reverted by adding Λ hyperon. In this article, we discuss the reason for these structure changes related to the coexistence of ground and low-lying states with different deformation.