Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Direct-template synthesis and purification of a new phase of the triple-decker bismuth(III) phthalocyanine Bi2(Pc)3, prepared from bismuth acetate and phthalonitrile, are described. X-ray analysis shows a triple-decker molecular structure involving three phthalocyanine rings and two bismuth atoms that are 3.838(9) Å a…
Discrete and monodisperse submicron crystals of silicalite-1 with a mean size of 0.3 μ m were synthesized from clear crystallization solutions. The effects of silica content, alkalinity of batch and the nature of silica source on the product yield, crystal morphology and particle size distribution were investigated. T…
The freshwater zones of the Warri/Forcados Estuaries contain a rich and diverse flora of tropical desmids, which compare favourably and show strong affinities with desmids from other parts of Africa, tropical South America, Southeast Asia, tropical Australia and the Indian sub-continent. In this study, ninety (90) tax…
Two mesogenic homologous series, 2-[4-(4-n-alkoxybenzoyloxy)-2-methylphenylazo]-naphthalenes (I) and 2-[4-(4-n-alkoxybenzoyloxy)-3-methylphenylazo]naphthalenes (II) with a lateral methyl group have been synthesized. Both series are purely nematogenic. The mesomorphic properties of both series are compared with each ot…
Chromium-doped silica-based optical fibres emit infrared fluorescence at 77 K near 1250 nm (500 nm band-width) under 860−980 nm excitation. Visible and near-infrared absorption spectra of fibres were analysed using the Tanabe-Sugano formalism. It is shown that although the fibre core is codoped with only 1 mol% of alu…
Ground-state properties and phonon dispersion curves of a classical linear-chain model describing a crystal with an incommensurate phase are studied. This model is the DIFFOUR (discrete frustrated ${\ensuremath{\varphi}}^{4})$ model with an extra fourth-order term added to it. The incommensurability in these models ma…
The optical spectra of bis(phenethylimido)perylene (PhPTCD) are discussed. Surface-pressure area isotherms of floating Langmuir monomolecular layers have been obtained, and Langmuir-Blodgett (LB) molecular monolayers of the material have been fabricated on silver island substrates for surface-enhanced vibrational stud…
Pb2+ is a low cost activator which can provide strong absorption of UV and an efficient conversion to longer wavelengths. Considering that aluminate hosts are used in some lamp phosphors, Pb2+ luminescence in these hosts is studied. This paper reports results on the luminescence of Pb2+ in aluminates. It was found tha…
The temperature dependences of the dielectric constant ε of sodium niobate single crystals NaNbO 3 and sodium niobate-based (Na,Li)NbO 3 and (Na,K)NbO 3 solid solutions with low content of the second component have been studied. A weak anomaly observed in ε( T ) indicates a new phase transition in the vicinity of 150°…
Two different cubic phases in pure (Ia3d cubic space group) and mixed (Im3m cubic space group) thermotropic carboxylic acids are observed by optical microscopy. In unpolarized light, the presence of the cubic phases is identified unambiguously by the observation of facetted single crystals with highly symmetrical shap…
In the production of MDF, wet resinated fibre must be dried to its target moisture content, normally 9 to 11%, before compaction into a board by hot pressing. Fibre drying can be interpreted as an incorporated process involving gas-solid two phase-flow, inter-component transfer, and heat and mass transfer within the f…
The kinetics of photobleaching of zinc(II) tetra-t-butyltetrabenzoporphyrin 1, zinc(II) 13,17-diethyl-12,18-dimethyl-5-azadibenzo[b,g]porphyrin 2 and zinc(II) tetra-t-butylphthalocyanine 3 are studied. In methanol containing ca 0.1% pyridine, complex 1 undergoes photoaggregation, 2 is relatively photostable, while 3 u…
Abstract Novel liquid crystals (LCs) containing a trifluoromethoxy group connected to a cyclohexane mesogen or to an alkyl tail were prepared through an oxidative desulfurization-fluorination reaction of the corresponding dithiocarbonates. They were compared with LCs containing a methoxy group with respect to phase tr…
The effect of chondroitin sulfate (ChS) templates on the crystal growth of hydroxyapatite (HAp) was investigated. HAp particles and 60HAp/40ChS hybrid (in wt%) were synthesized by using a precipitation method with a calcium hydroxide suspension and phosphoric acid solutions without and with ChS, respectively. The size…
We propose a tensor description of surface anchoring of liquid crystals (LCs). The model allows one to consider both the homogeneous and inhomogeneous parts of LC anchoring and to calculate the cumulative effect of different treatments as a sum of corresponding tensors. For the planar alignment the tensor representati…
A generalized Rapini-Papoular-type anchoring energy formula [J. Phys. (Paris) Colloq. 30, C4-54 (1969)] with two coupling constants is established through a second-order spherical-harmonic expansion. Using this formula, we analyze the threshold and saturation properties of twisted nematic devices with unidirectional p…
A structural model of a one-component $\ensuremath{\sigma}$-phase crystal has been constructed by means of molecular dynamics simulation. The phonon dispersion curves and the vibrational density of states were computed for this model. The dependence of the vibrational properties on the thermodynamical parameters was i…
The ionic model is shown to give a good description of most inorganic materials, such as salts, ceramics, and minerals, regardless of the covalent or ionic character of their bonds. The virtue of the model is its ability to treat chemical bonding using simple electrostatic theory, all the quantum mechanical effects be…
A chiral photochromic polyisocyanate was incorporated into a solid polymer matrix of poly(methyl methacrylate) (PMMA), yielding an isotropic polymer film. Isomerization of the chiral photochromic azo side groups (cis-trans) triggers a reversible conformational change of the helical polyisocyanate backbone. Thus the ch…
The structure of an Al-Ni-Co decagonal quasicrystal (called the S1-type superstructure), which shows diffraction patterns with superlattice reflections, has been studied by atomic-scale observations of electron microscopy. The structure of the decagonal quasicrystal can be characterized as an ordered arrangement of tw…