Materials Literature
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This review is concerned with quantum confinement effects in low-dimensional semiconductor systems. The emphasis is on the optical properties, including luminescence, of nanometre-sized microcrystallites, also referred to as zerodimensional systems. There is some discussion on certain of the two-dimensional systems, s…
Abstract The Rietveld method is a powerful and relatively new method for extracting detailed crystal structural information from X-ray and neutron powder diffraction data. Since such structural details dictate much of the physical and chemical attributes of materials, knowledge of them is crucial to our understanding…
A one-dimensional constitutive model for the thermomechanical behavior of shape memory alloys is developed based on previous work by Liang and Tanaka. An internal variable ap proach is used to derive a comprehensive constitutive law for shape memory alloy materials from first principles without the assumption of const…
The PROCHECK suite of programs provides a detailed check on the stereochemistry of a protein structure. Its outputs comprise a number of plots in PostScript format and a comprehensive residue-by-residue listing. These give an assessment of the overall quality of the structure as compared with well refined structures o…
Abstract A polyimide made from 4,4′‐diaminodiphenyl ether (ODA) and 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA) was synthesized in polyphosphoric acid. Although the polymerization proceeded heterogeneously, a polyimide with an inherent viscosity of 0.90 was obtained, and a tough and flexible film was made fro…
Abstract It is shown that many simple glass‐forming liquids exhibit a phenomenon known in the area of polymer science as the liquid–liquid transition. The phenomenon manifests itself as a third‐order transition in the equilibrium liquid‐specific heat data around approximately 1.2 T g and also as a bifurcation of the l…
Abstract Measurement of imidization by IR spectroscopy has frequently been reported to give results that are either insensitive to changes in the latter part of the cure or in conflict with observations by other methods. However, an analysis of imide formation using the 1370 cm −1 band (CN stretch) in conjunction wit…
Abstract Permeability measurements for oxygen and nitrogen were carried out on a series of structurally similar polyimides in order to define structure/permeability relationships. The polyimides were prepared from 5,5′‐[2,2,2‐trifluoro‐1‐(trifluoromethyl) ethylidene] bis‐1,3‐isobenzofuranedione (6FDA) and a variety of…
Abstract Poly(ether sulfone)s containing pendant sodium sulfonate groups were prepared by the aromatic nucleophilic substitution reaction of 4,4′‐dichlorodiphenylsulfone ( 1 ) and sodium 5,5′‐sulfonylbis (2‐chlorobenzenesulfonate) ( 2 ) with bisphenols ( 3 ) in the presence of potassium carbonate in N,N ‐dimethylaceta…
Abstract Ozone‐induced graft polymerization was carried out to improve polymer surfaces. The polymers were exposed to ozone and the surface density of peroxides formed was determined by three methods; iodide, DPPH, and peroxidase method. The peroxide production could be readily controlled by the ozone concentration an…
Abstract It was found that montmorillonite was intercalated with ϵ‐caprolactam. X‐ray diffraction revealed that the chain axes of the ϵ‐caprolactam were parallel to the montmorillonite plates. The intercalated montmorillonite was swollen by molten ϵ‐caprolactam at 200°C. ϵ‐Caprolactam and 6‐aminocaproic acid (accelera…
The classical in vitro denaturation-renaturation studies by Anson, Anfinsen, Neurath, Pauling and others clearly suggested that the primary structure of proteins determines all higher levels of protein structure. Protein folding in the cell is inaccessible to a detailed analysis of its kinetic mechanism. There are obv…
The valence and core level spectra of chemically prepared, ideally H-terminated Si(111) surfaces are characterized by remarkably sharp features. The valence band levels and their dispersion are well described by first-principles calculations using a quasiparticle self-energy approach within the GW approximation. From…
The zero-field splitting (ZFS) parameters D, E and F for an Mn 2+ centre in a BiVO 4 single crystal are calculated using the point-charge electrostatic model and the superposition model. The calculated ZFS parameters at the Bi and V sites are compared with the experimental values for Mn 2+ . The calculated second-orde…
Raman spectra of polyimide films were studied before and after being irradiated with 308 nm excimer laser pulses in order to understand the conductivity increase induced by ultraviolet irradiation. Changes in the chemical structure of polyimide were observed. A possible mechanism responsible for the ultraviolet induce…
The ability to control the electrical resistivity of semiconducting tetrahedral amorphous carbon (ta-C) films is reported. Phosphorus is incorporated during film growth from a plasma formed with a cathodic vacuum arc by using a phosphorus-containing carbon cathode. By changing the P content in the cathode from 0-1% ma…
Abstract Eight different 2,2′‐bipyridine derivatives, i.e . 2, 5, 8, 10, 12, 13, 15 , and 19 ( Schemes 1 and 2 ), were prepared to study the influence of the chelating groups on the luminescence properties of their Eu III and Tb III chelates. According to our luminescence results, 2,2′‐(methylenenitrilo)bis(acetic aci…
Abstract A Mixture of (3 S ,6 R )‐ and (3 R ,6 R )‐3‐methyl‐6‐(1‐methylethenyl)dec‐9‐enyl acetate ( 1a and 1b , respectively)– 1a being a pheromone of the California red scale – is synthesized in 14 steps from (+)‐( R )‐limonene ( 4 ). The key step is the reductive vitamin‐ B 12 ‐catalyzed coupling of ( R )‐5‐(2‐iodoe…
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” opt…
In the photodynamic therapy of cancer, research has focused on the influence of lipoproteins (particularly the low-density lipoprotein, LDL) on the fate and transport of the porphyrin mixture. We have studied the interaction between LDL and a series of well-defined tetraphenylporphinesulfonates, TPPS-1, TPPS-2A, and T…