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61.
A. Al-Kahtani Ahmed J. Jayaraju B. S. Sherigara H. S. Naik Bhojya J. Keshavayya 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(12):1055-1063
The miscibility of dextran (Dex)/poly(vinyl pyrrolidone) (PVP) in solution has been investigated in different percentages of the blend components by employing viscosity, density, refractive index and ultrasonic velocity methods at 30 and 50°C, respectively. Ultrasonic velocity and adiabatic compressibility against blend compositions were plotted and found to be linear. The interaction parameters μ and α have been obtained by using the viscosity data. The results indicated that the Dex/PVP blends are miscible in the entire composition range and it was further confirmed by ultrasonic velocity, density, refractive index studies. In addition, the results revealed that the change in temperature has no significant effect on the miscibility of Dex/PVP polymer blend. 相似文献
62.
Phthalocyanines have been used as photodynamic therapy (PDT) agents because of their uniquely favorable optical properties and high photostability. They have been shown to be highly successful for the treatment of cancer through efficient singlet‐oxygen (1O2) production. However, due to their hydrophobic properties, the considerations of solubility and cellular location have made understanding their photophysics in vitro and in vivo difficult. Indeed, many quantitative assessments of PDT reagents are undertaken in purely organic solvents, presenting challenges for interpreting observations during practical application in vivo. With steady‐state and time‐resolved laser spectroscopy, we show that for axial ligated silicon phthalocyanines in aqueous media, both the water:lipophile ratio and the pH have drastic effects on their photophysics, and ultimately dictate their functionality as PDT drugs. We suggest that considering the presented photophysics for PDT drugs in aqueous solutions leads to guidelines for a next generation of even more potent PDT agents. 相似文献
63.
64.
Rafal Kowerdziej Marek Olifierczuk Bartlomiej Salski Janusz Parka 《Liquid crystals》2013,40(7):827-831
We analysed the response of a tunable liquid crystal metamaterial transducer in the terahertz frequency range. Tunability of scattering parameters is achieving by an in-plane switching (IPS) effect. The metamaterial structure is based on Ω-shape resonators. A full-wave analysis technique based on the finite-difference time-domain (FDTD) method was performed using the QuickWave 3D electromagnetic solver. Terahertz transmission properties of the metamaterial structure can be controlled by the director of the liquid crystal layer. The effective refractive index for operation frequency varies from negative to positive values. A novel approach to switching of metamaterial transducer by IPS mode is presented. 相似文献
65.
Darrell J. Spells Christopher Lindsey Larry R. Dalton Shin-Tson Wu 《Liquid crystals》2013,40(12):1529-1532
Methods for synthesizing substituted alkyl and fluoro stilbene-tolane (PTPDP) liquid crystal materials are presented. These compounds show a slightly higher birefringence than the analogous bistolanes, but higher melting points and heats of fusion. Potential applications of these compounds for optical communications and displays are discussed. 相似文献
66.
67.
James E. Castle 《Surface and interface analysis : SIA》2022,54(4):455-464
The Auger parameter (AP) is a value extracted from the X-ray photoelectron spectrum (XPS) by addition of the binding energy of a photoelectron, for a given element in the spectrum, to the kinetic energy of the Auger electron emitted as the resulting hole in the electronic structure is filled by an electron from one of the outer orbitals. The value of the AP is sensitive to the polarization of electrons in the orbitals of neighbouring ions towards the photo-ionized atom and is thus related to other opto-electronic properties of the material. A correlation had been shown between the refractive index and the AP of aluminosilicates and thus the ability to compare, on a single chart, the AP's of the Al and Si ions gave important structural information. This comparison was made possible by normalising the individual APs to a common zero-point. In this contribution, the methodology employed is extended to a wider range of elements. The resulting ability, to compare and contrast the normalised AP, thus generated, greatly enhances the information available from XPS and thus relates it directly to the polarizability of the material's structure. 相似文献
68.
物质的偏振特性与其复折射率、表面粗糙度以及观测几何条件有关,为了应用偏振探测技术实现对目标的定量反演,本文首先对两种典型目标(绿漆涂层和石英玻璃)的偏振特性进行了实验测定,并对偏振度与探测天顶角的关系进行了分析。利用实验数据并基于描述目标偏振特性的PG模型首次在考虑了粗糙度的影响下,对目标的折射率、消光系数进行了定量反演,最后将反演结果与参考结果进行比较。结果表明,石英玻璃的折射率相对误差为4.944 9%,绿漆涂层的折射率与消光系数的相对误差分别为11%和21.558 9%。该方法在考虑表面粗糙度的条件下能够更精确地测定物质的复折射率,同时也为偏振技术应用于目标定量反演提供了依据。 相似文献
69.
Substituent effects of fused six, and five‐membered aromatic rings are investigated on the stability, aromaticity, charge distribution, nucleophilic (N), and electrophilic (ω) characters of 20 singlet (s) and triplet (t) Hammick carbenes, at B3LYP/AUG‐cc‐pVTZ and M06‐2X/AUG‐cc‐pVTZ. Results display: (a) The higher thermodynamic and kinetic stability is revealed by carbenes situated between two nitrogen and/or two oxygen heteroatoms of two substituted rings, in a “W” arrangement toward the carbenic center; (b) Regardless of the arrangement, the order of thermodynamical and kinetic stabilization for fused rings is pyrrole > furan > thiophene > phosphole. (c) The substituted Hammick carbenes with two fused heterocyclics, in a given arrangement, show more stability than unsubstituted Hammick carbene; (d) While two five‐membered heterocyclic rings stabilize their corresponding substituted carbenes, two benzene rings destabilize Hammick carbene; (e) In all structures, s species emerges as ground state, exhibiting more stability than its t state; (f) The scrutinized s carbenes show higher N and lower ω than their corresponding t states. 相似文献
70.
Alexander K. Mengele Dominik Weixler Avinash Chettri Maite Maurer Fabian Lukas Huber Prof. Gerd M. Seibold Prof. Benjamin Dietzek Prof. Bernhard J. Eikmanns Prof. Sven Rau 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(68):16840-16845
A series of three Ru(II) polypyridine complexes was investigated for the selective photocatalytic oxidation of NAD(P)H to NAD(P)+ in water. A combination of (time-resolved) spectroscopic studies and photocatalysis experiments revealed that ligand design can be used to control the mechanism of the photooxidation: For prototypical Ru(II) complexes a 1O2 pathway was found. Rudppz ([(tbbpy)2Ru(dppz)]Cl2, tbbpy=4,4'-di-tert-butyl-2,2'-bipyridine, dppz=dipyrido[3,2-a:2′,3′-c]phenazine), instead, initiated the cofactor oxidation by electron transfer from NAD(P)H enabled by supramolecular binding between substrate and catalyst. Expulsion of the photoproduct NAD(P)+ from the supramolecular binding site in Rudppz allowed very efficient turnover. Therefore, Rudppz permits repetitive selective assembly and oxidative conversion of reduced naturally occurring nicotinamides by recognizing the redox state of the cofactor under formation of H2O2 as additional product. This photocatalytic process can fuel discontinuous photobiocatalysis. 相似文献