Materials Literature
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The dissolution of metal during the passivation of Fe-Cr alloys has been studied in situ as a function of alloy composition in order to investigate the critical Cr content required for corrosion protection. This is achieved using synchrotron X-ray fluorescence microprobe analysis on a sputter-deposited Fe-Cr thin film…
The PBMR project should be seen against the background of the particular economic circumstances of Eskom, the project's dominant investor. On the one hand Eskom is one of the world's largest utilities by generation, with total capacity of almost 40 000 MWe, of which about 85% is coal-fired. South Africa's single nucle…
At relatively low electric fields the conduction of thin films (2–6 µm) of the discotic liquid crystal (HAT6–PTP9) sandwiched between ITO electrodes and homeotropically aligned is low and is consistent with space-charge limited behaviour. However when annealed at high temperatures and electric fields the films undergo…
Cyclic polarization measurements have been made on abraded Al in near neutral borate, chromate, phosphate, and sulfate solutions. In both borate and chromate solutions, the currents continued to decrease with each subsequent cycle due to oxide thickening. In contrast, a significant rate of oxide dissolution occurred t…
The decomposition behavior of titanium tetraisopropoxide [TTIP, on Si(100) has been studied using a thermal desorption technique in vacuum. TTIP is dissociated on Si(100) at temperatures below 350 K so that the silicon surface is covered with isopropoxy ligands and hydrogen, which originate from the TTIP. The isopropo…
Microwave sintering technique has been applied to sinter the Pb(Zr0.52Ti0.48)O3, PZT, ceramic materials in a significantly rapid rate. These materials can be sintered with a high density (≥96% theoretical density) by microwave sintering the samples at 1250°C (or millimeter-wave at 1200°C) for 10 min. In contrast, the…
In this work, we analyze the electrical behavior of amorphous GexSi1−xOy thin films to be used as sensitive layers in integrated bolometers. The GexSi1−xOy films were grown by reactive sputtering of a Ge0.85Si0.15 target using a mixture of argon and oxygen. The films were characterized by measuring the composition, th…
The short-range order of a set of Lu-saturated smectites, modified by hydrothermal treatment at 400 °C, which give rise to a new crystalline phase (Lu 2 Si 2 O 7 ), has been analyzed. In particular, the modifications undergone by the tetrahedral Si atoms of the lattice and the possible diffusions of O-T layer ions to…
All articles of this category A new heterogeneous ruthenium-copper-hydrotalcite catalyst for the efficient and selective conversion of a variety of aliphatic, allylic and aromatic alcohols to either aldehydes or ketones is described. Suitable co-oxidants include iodosylbenzene, tetrabutyl ammonium periodate and, depen…
Palladium-catalyzed N-arylation reactions provide acces to N-aryl-substituted and N-aryl-bridged 1,4,7,10-tetraazacyclododecanes. Yields of arylation products are low with simple haloarenes, whereas reactions with pyridine derivatives give substituted cyclens in moderate to satisfactory yields.
Leverage analysis enables identification of reflections with the greatest influence on the estimate of each refined variable, and thus may be an important tool to improve standard structure-refinement procedures, especially in the case of minerals with complex composition. In this work, leverage analysis was used to i…
To clarify the effects of the clothing pressure exerted on a trunk by a swimsuit on heart rate, skin blood flow and respiratory function, wearing tests of seven female students were conducted. When a swimsuit was worn, blood pressure increased and heart rate decreased in a standing posture, furthermore, oxygen intake…
The crystallization of sol–gel‐derived strontium barium niobate (SBN) thin films on various substrates is enhanced by a two‐step heating process. Also, SBN films with c ‐axis preferred orientation are obtained on MgO (100) substrates. The crystallized phase and the degree of orientation are dependent on crystallizatio…
In this paper we report one of the first examples of a soluble, fusible liquid crystalline polypyrrole. We describe the synthesis and characterisation of two pyrrole-based monomers substituted at the N-position with the mesogenic group 4-cyanobiphenyl. The mesogenic group is separated from the pyrrole moiety by an alk…
Abstract Ab initio quantum chemical studies at the HF/Lanl2dz level were carried out to investigate the interaction of ammonia, NO, and a mixture of the two with vanadia/titania. It was found that the replacement of Ti 6c by V 6c is the only feasible way to form highly dispersed vanadia over the titania. The VO speci…
Analytic expressions for fatigue are presented for both thin film and single crystal ferroelectric perovskite samples. The models are based on pinning of ferroelectric domain walls by oxygen vacancies oriented in planes parallel to the polarisation direction. In thin films a self-ordering effect is invoked to explain…
Power quality is becoming more and more important for electrical utilities. One of the drivers for its improvement is the reduction of the number and duration of outages due to faults on the power distribution cable lines by means of effective condition assessment techniques. Several systems have been made available o…
Nickel and cobalt hexacyanoferrate-modified gold electrodes were prepared by electrochemical synthesis. These samples were investigated by X-ray photoelectron spectroscopy (XPS) after removal of the modified electrodes from the electrochemical cell at different potentials and transfer into the ultra high vacuum of the…
Abstract A family of N ‐representability conditions are imposed on the third‐ and fourth‐order reduced density matrix elements in order to ascertain that they are within bounds. These bounds are needed in the construction of high‐order reduced density matrices as well as in the correction of the matrices which result…
This work has investigated the effects of the etching method of a Ti substrate for a catalytic oxide electrode on the electrochemical characteristics of the electrode. The HCl etching develops a finer and more homogeneous roughness on the Ti substrate than an oxalic acid etching. The etching results affect the physica…