Materials Literature
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Supramolecular arrays in which a free-base (or zinc) porphyrin is connected by axial coordination of its meso-pyridyl groups to one or more ruthenium porphyrin units have been studied by steady-state and time-resolved techniques. Besides their attractive structures—“open-box” or “flying saucer”—these arrays exhibit in…
The paper describes a new selective detection method for water trees developed in consideration of the electrophysical concept of the water treeing phenomenon. As most of the liquid water is not chemically bound in the water trees it can move out or in, depending on the actual physical conditions such as the solubilit…
Nature abhors a vacuum. Attempts to self-assemble nanoporous crystals (clathrates) with trimesic acid and its analogues reveal a striking variability in carboxylic acid motifs that often allow close-packing without clathrate formation. The common R22(8) carboxylic acid dimer is found in tributyl trimesic acid, which f…
In insulation materials several chemical and physical deterioration processes arise, such as thermal and electrical ageing, and moistening, due to operational and environmental stresses. As well as electrical strength, these deterioration processes influence the dielectric processes, the conduction and the polarisatio…
Wet oxidation kinetics of aqueous solutions of formic, acetic, oxalic, and glyoxalic acids was studied in a titanium autoclave at a temperature range of 150−320 °C and oxygen partial pressures between 8 and 60 bar. Oxidation reactions obeyed a first-order kinetics with respect to concentration of all substrates. On th…
Long-range ferromagnetic ordering at 3 K is observed for the title compound, which may be considered as a fully localized mixed-valence species (Mo3+ and Mo4+) as well as a mixed-spin species (low-spin and high-spin Mn2+ ions). Its two-dimensional structure consists of heart-shaped 48-membered rings, and each ring con…
Addition of aliphatic polyols to aqueous silicate solutions is shown to yield high concentrations of stable polyolate complexes containing five- or six-coordinated silicon. Coordinating polyols require at least four hydroxy groups, two of which must be in threo configuration, and coordinate to silicon via hydroxy oxyg…
We have developped a novel lift-off process for fabrication of high quality superconducting submicron niobium structures. The process makes use of a thermostable polymer with a high transition temperature T_{g}= 235 C and an excellent chemical stability. The superconducting critical temperature of 100 nm wide niobium…
In the asymptotic limit, the interlayer exchange coupling decays as $D^{-2}$, where $D$ is the spacer thickness. A systematic procedure for calculating the preasymptotic corrections, i.e., the terms of order $D^{-n}$ with $n \ge 3$, is presented. The temperature dependence of the preasymptotic corrections is calculate…
The adsorption behavior of bovine serum albumin (BSA) on high-purity austenitic low-carbon stainless steel and its effect on the state of the electrode surface have been studied over the temperature range 299−343 K under open-circuit-potential conditions, using electrochemical impedance spectroscopy (EIS). The impedan…
A drastic change in the solubility and gelation properties of 1-O-methyl-4,6-O-benzylidene derivatives of monosaccharides (see figure) results from the change in the configuration of only one carbon atom.
Reversible switching of quadratic NLO responses can be achieved in organic and metallo-organic molecular compounds by application of various external stimuli. Strategies for the molecular engineering of switchable NLO materials are outlined (an example is depicted), and practical demonstrations of the switching of NLO…
After forever changing the drug discovery process in the pharmaceutical industry, combinatorial chemistry methodologies are increasingly being applied to the discovery and optimization of more efficient catalysts and materials (see picture). With the advent of new combinatorial synthesis and screening technologies, co…
Scanning tunneling spectroscopy was used to investigate single crystals and thin films of La(1-x)Ca(x)MnO(3) (with x of about 0.3), which exhibit colossal magnetoresistance. The different spectroscopic signatures of the insulating (paramagnetic) and metallic (ferromagnetic) phases enable their spatial extent to be ima…
Calcium tracer diffusion coefficients in (La,Ca)CrO3 were determined by a nitric acid solution application method using 44Ca(NO3)2. The diffusion profiles of 44Ca in the air-sintered (La,Ca)CrO3 were measured by secondary ion mass spectrometry (SIMS) with a bombardment of primary O2+ ion. From the SIMS depth concentra…
The phase transformation between diamond and graphite in preparation of diamond by pulsed-laser-induced liquid - solid interface reaction (PLIIR) was studied by calculating the probability of phase transition of the carbon atoms over a potential barrier in the pressure-temperature ( P - T ) phase diagram of carbon. It…
Simple statistical agglomeration models can provide a universal link between the local structure and the glass transition temperature in network glasses. We first stress the physical features of the models and the hypothesis made, and then show how to define the glass transition temperature. The models are applied to…
We report a study of polycrystalline samples of the family La1-xCdxMnO3+dwith different percentage of Mn4+ ions. X-rays diffraction, Iodometric titration, Raman, Magnetic and Electrical Resistivity measurements provide a general characterisation of the physical properties. Results are qualitatively similar to the ones…
The structure and magnetic properties of Ho 2 (Co 1- x Fe x ) 17 compounds with x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.6, 0.8 or 1.0 have been investigated by x-ray diffraction (XRD) and magnetization measurements. XRD patterns demonstrate that all samples are single phase with the hexagonal Th 2 Ni 17 -type structure. The su…
The symmetry and disorder of the Eu 3+ site was investigated in some phosphate and borate glasses by means of 151 Eu Mössbauer spectroscopy. The quadrupole interaction parameter, which is due to the distortion of the Eu site compared to a cubic symmetry, has been measured together with the asymmetry parameter, which p…