Ru-Salen Catalyzed Asymmetric Epoxidation: Photoactivation of Catalytic Activity
All articles of this category asymmetric epoxidation - (ON + )-(salen)ruthenium(II) complexes - conjugated olefins - Ru-salen complex - photoactivation
Materials Literature
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Investigations of Electronic Energy Transfer Dynamics in Multiporphyrin Arrays
A study of the dynamics of electronic energy transfer (EET) in arrays containing three, four, and six tetraphenylporphine units connected with phenylethynyl spacers is reported. For arrays containing the same chromophores, the EET rate constant was determined from the reorientational dynamics of the transition dipole…
Nitrogen Incorporation into Tetrahedral Hydrogenated Amorphous Carbon
Structural changes induced by the incorporation of nitrogen into ta-C:H films have been studied by Electron Energy Loss Spectroscopy, X-Ray Photoelectron Spectroscopy, Fourier Transformed Infrared Spectroscopy and Ultraviolet-Visible Spectroscopy. ta-C:H films have been synthesised using a low pressure Electron Cyclot…
Improving low carbon steel chip breakability by cryogenic chip cooling
This paper presents a cryogenic machining approach to improve the chip breakability for cutting AISI1008 low carbon steel, a typical ductile material. A cryogen delivery system supplies liquid nitrogen (LN2) coolant specifically to chip faces in a properly scaled jet instead of flooding the general cutting zone. The c…
Identification of a New Gene Family Expressed during the Onset of Sexual Reproduction in the Centric Diatom Thalassiosira weissflogii
An intriguing feature of the diatom life cycle is that sexual reproduction and the generation of genetic diversity are coupled to the control of cell size. A PCR-based cDNA subtraction technique was used to identify genes that are expressed as small cells of the centric diatom Thalassiosira weissflogii initiate gameto…
Plant Riboflavin Biosynthesis
Lumazine synthase, which catalyzes the penultimate step of riboflavin biosynthesis, has been cloned from three higher plants (spinach, tobacco, and arabidopsis) through functional complementation of an Escherichia coli auxotroph. Whereas the three plant proteins exhibit some structural similarities to known microbial…
Dynamic Indentation Hardness and Rate Sensitivity in Metals
An experimental technique for determining the dynamic indentation hardness of materials is described. Unlike the traditional static hardness measurements, the dynamic hardness measurements can capture the inherent rate dependent material response that is germane to high strain rate processes such as high speed machini…
Strain characterization of polycrystalline diamond and silicon systems
The phonon deformation potentials of polycrystalline diamond and silicon, derived through the Voigt–Reuss–Hill averaging technique, are used to establish the systematics of strain characterization of polycrystalline films, considering all possible stress configurations. The results are compared to Raman data from the…
Cracks and Atoms
Atomic features are essential for understanding some materials properties. The example of brittle fracture is reviewed here, concentrating on molecular dynamics simulations of silicon. The Figure shows a visualization of an unstable crack at 8.97 % strain along (111). The choice of the potential, the implementation of…
Burning characteristics of selected substances: production of heat, smoke and chemical species
The cone calorimeter technique was employed to investigate the burning characteristics and composition of fire effluents of selected chemicals, including pesticides, compounds used in the chemical industry, liquid solvents and polymers. A controlled-atmosphere apparatus was utilized, allowing variation of the ventilat…
On the relationship between microhardness and glass transition temperature of some amorphous polymers
On the basis of microhardness (H) data measured at room temperature only for a number of polymers in the glassy state, a linear correlation between H and the glass transition temperature Tg has been found (H = 1.97Tg − 571). By means of this relationship, the deviation of the H values from the additivity law for some…
Electronic States of Boron and Phosphorus in Diamond
The electronic states of boron and phosphorus in diamond have been studied by infrared absorption and photo-thermal ionisation spectroscopies. High quality boron doped synthetic diamond (p-type conductive) and phosphorus-doped CVD diamond film (n-type conductive) were used for this study. In the case of boron-doped di…
Water Vapor Permeability of Whey Protein Emulsion Films as Affected by pH
ABSTRACT The water vapor permeability (WVP) of whey protein isolate‐beeswax emulsion films was investigated as related to pH. Lower WVP was observed for films cast from solutions at pH 7.0. When pH of the film‐forming solution was lowered, resulting film WVP increased. At the isoelectric point, WVP was the highest. As…
Ion-Implantation-Induced Defects in Diamond and Their Annealing: Experiment and Simulation
The nature of damage induced by ion-impact and its annealing are studied both experimentally and theoretically. The experimental methods employed include measurements of the changes in electrical conductivity, in material density and in Raman spectra. These are measured for natural type IIa diamonds containing differe…
Carburizing: Microstructures and Properties
Detailed discussions and over 250 graphs and charts describe the effects of microstructure on the properties of carburized stees. In-depth coverage clarifies the causes, interpretation, prevention, and consequences of various microstructural variations and defects in carburized parts. Also covered are the effects of p…
Grain-boundary magnetoresistance in manganites: Spin-polarized inelastic tunneling through a spin-glass-like barrier
The grain-boundary magnetoresistance of various ${\mathrm{La}}_{0.7}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_{3}$ samples was investigated by resistance, magnetoresistance, and dynamic conductance measurements. Data on five samples, namely an epitaxial film, a polycrystalline film, a step-edge array, a mechanically induced g…
Stability of transparent conducting oxide films for use at high temperatures
The stability of a number of transparent conducting oxide (TCO) films prepared by magnetron sputtering has been tested in various atmospheres at high temperatures up to 1000 °C: binary compounds such as ZnO, In2O3, and SnO2; ternary compounds such as Zn2In2O5, In4Sn3O12, GaInO3, ZnSnO3, and MgIn2O4; and multicomponent…
Smectic-A*–smectic-C*transition in a ferroelectric liquid crystal without smectic layer shrinkage
The smectic layer spacing of a nonfluorinated ferroelectric liquid crystal (FLC) compound with almost no shrinkage and only minor tendency to form zigzag defects was characterized by small angle x-ray diffraction. The material lacks a nematic phase. The smectic-A*-smectic-C* phase transition was studied by measuring t…
Safety and Pharmacokinetic Profile of Gadobenate Dimeglumine in Subjects With Renal Impairment
RATIONALE AND OBJECTIVES: To determine the safety and pharmacokinetics of gadobenate dimeglumine in a group of subjects with moderate or severe renal impairment. METHODS: The safety and pharmacokinetic profile of gadobenate dimeglumine, a gadolinium (Gd3+) chelate complex in development as a contrast agent for MRI, we…
The Raman coupling function in amorphous silica and the nature of the long-wavelength excitations in disordered systems
New Raman and incoherent neutron scattering data at various temperatures and molecular-dynamic simulations in amorphous silica are compared to obtain the Raman coupling coefficient C (ω) and, in particular, its low-frequency limit. This study indicates that in the ω → 0 limit C (ω) extrapolates to a nonvanishing value…