Materials Literature
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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…
The defect centres formed in the thermoluminescent phosphor CaSO 4 :Dy on additionally doping with Na + (as a charge compensator) have been studied using the technique of electron paramagnetic resonance. The Na + ion at the Ca 2+ site is found to stabilize the observed SO 4 - radical. An important feature of the new S…
We compare the light scattering properties of polymer-dispersed liquid crystal films incorporating different nematic mixtures. We find that, when powered, the turbidity of these disparate films share a common quadratic dependence on the refractive index difference between the nematic and polymer. In contrast, when we…
Inelastic electron scattering using a two-beam channeling condition is used for the first time to create excitations having selectable even or odd symmetry relative to an atom column. The method is first established using plasmon and interband scattering in diamond. Next, for the carbon 1s absorption edge, scattering…
We present the fabrication of sub-50 nm Si pillars, ridges, and trenches with aspect ratios greater than 10 using ultrahigh resolution electron beam lithography and chlorine based reactive ion etching. These nanoscale Si features can be further reduced to 10 nm using an additional HF wet etch. No photoluminescence was…
Neutron diffraction measurements confirm the presence of long-range antiferromagnetic order in superlattices of cobalt oxide and nickel oxide. A single transition temperature between the values for bulk CoO and NiO is evident for two samples with 36 \AA{} periods as previously reported, but the separate Ni and Co orde…
Free-standing films of a smectic liquid crystal possessing the bulk phase sequence smectic A, ferroelectric smectic C, antiferroelectric smectic ${\mathit{C}}_{\mathit{A}}$ are studied. Using ellipsometric measurements, we show that the bulk phases still exist in films consisting of only four, three, and even two smec…