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991.
Rekha?Goswami?ShresthaEmail author Suraj?Chandra?Sharma Kenichi?Sakai Hideki?Sakai Masahiko?Abe 《Colloid and polymer science》2012,290(4):339-348
Formation of wormlike micelles (WLMs) in an aqueous mixture of polyoxyethylene cholesteryl ether (ChEOn; where n = 20 and 30) and polyoxyethylene dodecyl ether (C12EOm; where m = 3 and 4) has been reported; rheological and small angle X-ray scattering (SAXS) measurements have been performed in the
micellar solutions of ChEOn as a function of C12EOm for the structural elucidation. When lipophilic cosurfactant, C12EOm is added to the micellar solutions of ChEOn, it favors the sphere-to-cylinder transition due to the penetration of C12EOm in the palisade layer of ChEOn micelle accompanying an increase in viscosity. When the concentration of C12EOm is increased, entangled network of WLMs is formed. A strong shear thinning has been observed in highly viscous samples indicating
the presence of transient networks. Such samples exhibited viscoelastic behavior and could be described by the Maxwell model
with a single stress relaxation mode. A maximum is observed in zero-shear viscosity-C12EOm plot. With further addition of C12EOm, viscosity declines and ultimately a phase separation occurs with the formation of turbid solution of vesicular dispersion.
This decline has been interpreted in terms of micellar branching induced by an increase in endcap energy, E
c (which is compensated by the formation of branch points, having a mean curvature opposite to that of endcaps). The C12EOm induced one-dimensional micellar growth has been confirmed by SAXS. 相似文献
992.
Yuichiro Abe Dr. Satoru Karasawa Dr. Noboru Koga 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(47):15038-15048
2,4‐Trifluoromethylquinoline (TFMAQ) derivatives that have amine ( 1 ), methylamine ( 2 ), phenylamine ( 3 ), and dimethylamine ( 4 ) substituents at the 7‐position of the quinoline ring were prepared and crystallized. Six crystals including the crystal polymorphs of 2 (crystal GB and YG) and 3 (crystal B and G) were obtained and characterized by X‐ray crystallography. In solution, TFMAQ derivatives emitted relatively strong fluorescence (${\lambda {{{\rm f}\hfill \atop {\rm max}\hfill}}}$ =418–469 nm and Φf(s)=0.23–0.60) depending on the solvent polarity. From Lippert–Mataga plots, Δμ values in the range of 7.8–14 D were obtained. In the crystalline state, TFMAQ derivatives emitted at longer wavelengths (${\lambda {{{\rm f}\hfill \atop {\rm max}\hfill}}}$ =464–530 nm) with lower intensity (Φf(c)=0.01–0.28) than those in n‐hexane solution. The polymorphous crystals of 2 and 3 emitted different colors: 2 , ${\lambda {{{\rm f}\hfill \atop {\rm max}\hfill}}}$ =470 and 530 nm with Φf(c)=0.04 and approximately 0.01 for crystal GB and YG, respectively; and 3 , ${\lambda {{{\rm f}\hfill \atop {\rm max}\hfill}}}$ =464 and 506 nm with Φf(c)=0.28 and approximately 0.28 for crystal B and G, respectively. In both crystal polymorphs of 2 and 3 , crystals GB and G showed emission color changes by heating/melting/cooling cycles that were representative. By following the color changes in heating at the temperature below the melting point with X‐ray diffraction measurements and X‐ray crystallography, the single‐crystal‐to‐single‐crystal transformations from crystal GB to YG for 2 and from crystal B to G for 3 were revealed. 相似文献
993.
Prof. Dr. Tsutomu Hoshino Akifumi Chiba Naomi Abe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(41):13108-13116
Lanosterol synthase catalyzes the polycyclization reaction of (3S)‐2,3‐oxidosqualene ( 1 ) into tetracyclic lanosterol 2 by folding 1 in a chair‐boat‐chair‐chair conformation. 27‐Nor‐ and 29‐noroxidosqaulenes ( 7 and 8 , respectively) were incubated with this enzyme to investigate the role of the methyl groups on 1 for the polycyclization cascade. Compound 7 afforded two enzymatic products, namely, 30‐norlanosterol ( 12 ) and 26‐normalabaricatriene ( 13 ; 12 / 13 9:1), which were produced through the normal chair‐boat‐chair‐chair conformation and an atypical chair‐chair‐boat conformation, respectively. Compound 8 gave two products 14 and 15 ( 14 / 15 4:5), which were generated by the normal and the unusual polycyclization pathways through a chair‐chair‐boat‐chair conformation, respectively. It is remarkable that the twist‐boat structure for the B‐ring formation was changed to an energetically favored chair structure for the generation of 15 . Surprisingly, 14 and 15 consisted of a novel 6,6,6,6‐fused tetracyclic ring system, thus differing from the 6,6,6,5‐fused lanosterol skeleton. Together with previous results, we conclude that the methyl‐29 group is critical to the correct folding of 1 , with lesser contributions from the other branched methyl groups, such as methyl‐26, ‐27, and ‐28. Furthermore, we demonstrate that the methyl‐29 group has a crucial role in the formation of the five‐membered D ring of the lanosterol scaffold. 相似文献
994.
Micellar inhibition effect of gangliosides on a degradation of drug was investigated, where ganglioside G(M1) (GM1), G(D1a) (GD1a) and G(T1b) (GTlb) whose sialic acid residue is one, two and three, respectively, were used. The base-catalyzed isomerization of prostaglandin A(2) (PGA(2)) to prostaglandin B(2) (PGB(2)) was chosen as a model experiment. The rate for the isomerization of PGA(2) was determined by measuring the concentration of PGA(2) (and PGB(2)) with a high-performance liquid chromatography. Gangliosides micelles inhibited the isomerization of PGA(2). The inhibition effect of GT1b micelles was larger than that of GD1a micelles. This result would be due to the larger absolute value of surface potential of GT1b micelles, which brings about a larger electrostatic repulsion between micellar surface and OH(-). The terminal sialic acid residue of ganglioside was effective to inhibit the isomerization of PGA(2). GM1 micelles without terminal sialic acid residue but with large aggregation number exhibited a superior steric shielding effect rather than an electrostatically repulsive effect. The inhibition effect of GM1 micelles was enhanced by the mixed micellization with the other ganglioside with a terminal sialic acid residue. GM1-GD1a or GM1-GT1b mixed micelles remarkably inhibited the isomerization of PGA(2). The physiological activity of PGs in the biological membranes containing gangliosides was also discussed. 相似文献
995.
Kyohei Shibano Reo Kontani Hiroshi Hirai Mikio Hasegawa Kazuyuki Aihara Hisao Taoka David McQuilkin Rikiya Abe 《The European physical journal. Special topics》2014,223(12):2611-2620
In recent years, practical research related to distributed power generation and networked distribution grids has been increasing. This research uses a relatively abstract model for the cost reduction in the Digital Grid Power Network. In the Digital Grid, the traditional wide-area synchronous grid is divided into smaller segmented grids which are connected asynchronously. In this paper, we demonstrate how to formulate the minimized cost of power generation by using linear programming methods, while considering the cost of electric transmission and distribution and using asynchronous power interchange among separate grids. 相似文献
996.
Masanobu Isshiki Porponth Sichanugrist Yusuke Abe Takuji Oyama Hidefumi Odaka Makoto Konagai 《Current Applied Physics》2014,14(12):1813-1818
High transmittance of transparent conductive oxide (TCO) substrates is one of the most important factors for achieving high efficiency in thin-film silicon solar cells. Immersion (IM) method with CH2I2 liquid is widely used for the evaluation of optical properties (transmittance, reflectance and absorption) for TCO substrates with textured surface in order to reduce the scattering at the TCO surface. However, in order to measure transmittance accurately, three problems have been found. (1) CH2I2 liquid itself absorbs the light in short wavelength region. (2) The transmittance around the absorption edge of CH2I2 liquids is very sensitive to its amount. (3) Scattering cannot be suppressed when the scattering surfaces are more than 2 surfaces (for example, TCO on reactive ion etching (RIE) processed glass). To overcome these problems, we proposed a new setup to measure optical properties of TCO substrates by holding the samples inside the integral sphere. As the results, we have confirmed that their absorption in all wavelength could be measured accurately and the transmittance measured by the new method was well consistent with the external quantum efficiency (EQE) of the fabricated cell while the transmittance measured with conventional IM method showed differently. Therefore, this new method could be a useful tool to evaluate TCO substrates for thin-film silicon solar cells. 相似文献
997.
998.
Athiyanathil Sujith Tamitake Itoh Hiroko Abe Ken-ichi Yoshida Manikantan S. Kiran Vasudevanpillai Biju Misturu Ishikawa 《Analytical and bioanalytical chemistry》2009,394(7):1803-1809
The surface of a living yeast cell (Saccharomyces cerevisiae strain W303-1A) has been labeled with silver (Ag) nanoparticles that can form nanoaggregates which have been shown to have surface-enhanced
Raman scattering (SERS) activity. The cell wall of a single living yeast cell has been imaged by use of a Raman microspectroscope.
The SERS spectra measured from different Ag nanoaggregates were found to be different. This can be explained on the basis
of detailed spectral interpretation. The SERS spectral response originates from mannoproteins which cover the outermost regions
of the yeast cell wall. Analysis of SERS spectra from the cell wall and the extracted mannoproteins from the yeast has been
performed for the clarification of variation in SERS spectra. 相似文献
999.
<正>Polyvinylidene fluoride(PVDF) hollow fiber membranes prepared from spinning solutions with different polyvinyl pyrrolidone(PVP) contents(1%and 5%) at different extrusion rates were obtained by wet/dry phase process keeping all other spinning parameters constant.In spinning these PVDF hollow fibers,dimethylacetamide(DMAc) and PVP were used as a solvent and an additive,respectively.Water was used as the inner coagulant.Dimethylformamide(DMF) and water(30/70) were used as the external coagulant.The performances of membranes were characterized in terms of water flux,solute rejection for the wet membranes.The structure and morphology of PVDF hollow fiber were examined by BET adsorption,dry/wet weight method and scanning electron microscopy(SEM).It is found that the increase in PVP content and extrusion rate of spinning solution can result in the increase of water flux and decrease of solute rejection.The improvements of interconnected porous structure and pore size are induced by shear-thinning behavior of spinning solution at high extrusion rates,which could result in the increase of water flux of hollow fiber membranes.The increase of extrusion rate also leads to the increase of membrane thickness due to the recovery effect of elastic property of polymer chains. 相似文献
1000.
We report a series of quantum-chemical calculations for the ground and some of the low-lying excited states of an isolated LiYb molecule by the spin-orbit multistate complete active space second-order perturbation theory (SO-MS-CASPT2). Potential energy curves, spectroscopic constants, and transition dipole moments (TDMs) at both spin-free and spin-orbit levels are obtained. Large spin-orbit effects especially in the TDMs of the molecular states dissociating to Yb((3)P(0,1,2)) excited states are found. To ensure the reliability of our calculations, we test five types of incremental basis sets and study their effect on the equilibrium distance and dissociation energy of the ground state. We also compare CASPT2 and CCSD(T) results for the ground state spectroscopic constants at the spin-free relativistic level. The discrepancies between the CASPT2 and CCSD(T) results are only 0.01 ? in equilibrium bond distance (R(e)) and 200 cm(-1) in dissociation energy (D(e)). Our CASPT2 calculation in the supermolecular state (R=100 a.u.) with the largest basis set reproduces experimental atomic excitation energies within 3% error. Transition dipole moments of the super molecular state (R=100 a.u.) dissociating to Li((2)P) excited states are quite close to experimental atomic TDMs as compared to the Yb((3)P) and Yb((1)P) excited states. The information obtained from this work would be useful for ultracold photoassociation experiments on LiYb. 相似文献