Materials Literature
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Low voltage x-ray microanalysis, defined as being performed with an incident beam energy ≤5 keV, can achieve spatial resolution, laterally and in depth, of 100 nm or less, depending on the exact selection of beam energy and the composition of the target. The shallow depth of beam penetration, with the consequent short…
There has been some speculation that the C-6 position in UMP may be unusually acidic, stabilizing a carbanion that is generated at this position during OMP decarboxylation. On the basis of the rate of OH- catalyzed deuterium exchange at elevated temperatures we estimate that the pKa value for ionization at C-6 of dime…
The optical dephasing, caused by a quadratic interaction with acoustic phonons, is studied on the basis of the nonperturbative theory. The effect of a strong weakening of the elastic springs on the electronic transition is studied. It is found that, if the weakening brings the system close to the dynamical instability…
Chalcogenide glasses such as As 2 S 3 show prominent fluidity under intense subgap illumination. The feature is summarized, and the mechanism is discussed.
Proper material characterization of woven fabric reinforcement is important for accurate modeling of thermoforming. Thermoforming of commingled thermoplastic/glass fabric relies strictly on material deformation at temperatures above the matrix melting temperature. As the temperature increases, the viscosity decreases…
A coupled magnetomechanical model for the design and control of Villarieffect magnetostrictive sensors is presented. The model quantifies the magnetization changes that a magnetostrictive material undergoes when subjected to a dc excitation field and variable stresses. The magnetic behavior is characterized by conside…
Interference lithography with multiple beams provides two-dimensional periodic patterns in a single exposure step. It is possible to obtain various symmetries and shapes such as sparse hole arrays or dots on a hexagonal grid. However, when the number of interfering beams exceeds three, the intensity pattern depends st…
OBJECT: Mitoxantrone is a drug with potent in vitro activity against malignant brain tumor cell lines; however, its effectiveness as a systemic agent has been hampered by poor central nervous system penetration and dose-limiting myelosuppression. To avoid these problems, we incorporated mitoxantrone into biodegradable…
Abstract A new series of thermo-sensitive polyethers were prepared by anionic ring-opening polymerization of glycidyl ether derivatives: glycidyl methyl ether, ethyl glycidyl ether, and ethoxyethyl glycidyl ether. The prepared polymers have controllable molecular weight with narrow molecular weight distributions. Thes…
The combined effect of alkali and alkaline-earth ions on the redox, distribution, co-ordination and environment of Fe ions in alkali–alkaline-earth–silica glasses has been studied using a multi-technique approach. Wet chemical analysis and Mössbauer, electron spin resonance (ESR), optical absorption and photoluminesce…
Single-phase perovskite-type manganese oxides La 0.8 −x Na 0.2 □ x MnO 3+δ with x = 0.01–0.04 have been prepared by the modified sol–gel method and the influence of the vacancy concentration in the A site on their structures and magnetocaloric properties has systematically been investigated. The experimental results r…
Stishovite synthesized from natural basalt showed the highest concentration of hydrogen ever reported. The water concentration obtained from the polished single crystal of stishovite in this study was up to a maximum of 5628 ± 291 atoms of hydrogen per 10 6 silicon atoms (844 ± 44 ppm water). The concentration of hydr…
K-Ar dates of illitic clays from sedimentary rocks may contain “mixed ages,” i.e., may have ages that are intermediate between the ages of end-member events. Two phenomena that may cause mixed ages are: (1) long-lasting reaction during the burial illitization of smectite; and (2) physical mixing of detrital and diagen…
Electron-excited x-ray microanalysis performed in the variable pressure and environmental scanning electron microscopes is subject to additional artifacts beyond those encountered in the conventional scanning electron microscope. Gas scattering leads to direct contributions to the spectrum from the environmental gas,…
A highly efficient synthesis of 2-formyl-5,10,15,20-tetraarylporphyrins, 1 and 2, that can be carried out on multi-gram scales is reported. The key steps in the sequence involve use of copper(II) chelation to ensure very efficient electrophilic substitution, and the demetalation of the intermediate iminium salt that r…
The mechanism of intergranular-mode fracture in hydrogen-related failure of high-strength martensitic steels has been investigated. Pronounced degradation of tensile properties appeared with increasing manganese content in a slow-elongation-rate test under concurrent hydrogen charging. The fracture mode was intergranu…
Abstract When CO 2 is dissolved into a polymer, the viscosity of the polymer is drastically reduced. In this paper, the melt viscosities of low‐density polyethylene (LDPE)/supercritical CO 2 solutions were measured with a capillary rheometer equipped at a foaming extruder, where CO 2 was injected into a middle of its…
A new marine planktonic diatom, Pseudo-nitzschia galaxiae Lundholm & Moestrup sp. nov., isolated from Mexican and Australian waters, is described using light and transmission electron microscopy, including thin-sectioning. The diatom is very small and delicate and resembles species in the section Nitzschiella of Nitzs…
Our understanding of the genetics of species of the best-studied hyperthermophilic archaea, Pyrococcus spp., is presently limited by the lack of suitable genetic tools, such as a stable cloning vector and the ability to select individual transformants on plates. Here we describe the development of a reliable host-vect…
Abstract Filler flocculation was followed for silica filled compounds containing various alkoxy silanes and non-silane type polar additives. The methodology employed in this paper permitted a quantitative characterization of filler flocculation and polymer-filler interactions after heating the compound under condition…