Materials Literature
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Abstract The colored form of photochromic 1,2-bis(5-hydroxymethyl-2-methyl-3-thienyl)hexafluorocyclopentene was resolved into enantiomers by HPLC. The absolute stereochemistry of an enantiomer was determined on its bis(4-chlorobenzoate). The CD spectra and optical rotation of the resolved colored form were measured.
Ultrasonic enhanced chemical reactors have been used for decades. Cavitation, which results in dramatic increases in temperature and pressure, is responsible for the chemical and physical effects of ultrasound. Presented is a new model, which enables the calculation of linear three-dimensional pressure fields in any s…
We used small angle x-ray scattering to study interparticle structural properties of polyamidoamine starburst dendrimers (PAMAM, with an ethylenediamine central core) in methanol solutions. We have explored the intensity profiles for solutions of starbursts of different generations $(g=2,3.5,4)$ at various concentrati…
Extrusion foaming by injection of inert gases (carbon dioxide, nitrogen, argon) in the polymer melt is increasingly finding applications for a wide variety of resins, competing with chemical blowing agents, volatile organic compounds or microcellular foaming. The molecular weight and molecular weight distribution of t…
Electron crystallography is a powerful tool for the quantitative structural characterization of substances that preferentially form thin microcrystals. Because multiple-beam dynamical scattering may cause observed diffraction intensities to deviate significantly from their kinematical values, it is necessary to demons…
The electrochemical behavior of carbon steel in diglycolamine (DGA) solutions saturated with carbon dioxide (CO2) under 4.5 MPa pressure was investigated using potentiodynamic polarization and impedance measurements at room temperature (RT) and at 100°C. Electrode equivalent circuits were proposed for interpreting the…
Brownian dynamics, (BD), simulation has been used to follow the phase separation of Lennard-Jones-type particles quenched from a supercritical state point into the vapor–liquid or vapor–solid co-existence parts of their phase diagrams. Calculations were performed with spherical particles interacting via 12:6, 24:12, a…
Crystal structures have been obtained for the sodide (IUPAC, natride) salts, K+(12–crown–4)2–Na− (I), Na+(cryptand[2.2.1])Na−(II), Rb+(18–crown–6)Na−·CH3NH2 (III), K+(18–crown–6) Na−·2(CH3NH2)·3(18–crown–6)(IV), Cs+(cryptand[3.2.2])Na−(V), and (Li+)2(TMPAND)2–(Na−)2·(CH3NH2)(VI), in which TMPAND is 5,12,17–trimethyl–1…
SrTiO 3 thin films have been prepared on titanium substrates using strontium acetate solutions in newly constructed flow‐system equipment by the hydrothermal‐electrochemical method. The synthesis parameters (temperature of 120°‐200°C and flow rate of 1‐40 mL/min) allow fabrication of dense, single‐phase films with gra…
The chemical and structural surface-aging effects brought about by the presence of water in emeraldine base (EB) polyaniline (PANI) doped with Pd or Pt protonic acids were studied. IR spectroscopy, XRD, XPS and heterogeneous catalytic hydrogenation (alkyne→alkene→alkane) were applied to characterise the PANI–Pd and PA…
The phase transition mm21′←m′m2′observed in some boracites is regarded as a ferrotoroic phase transition, i.e., the toroidal moment is treated as the transition order parameter. This makes it possible to explain the observed narrow peak in the temperature dependence of the magnetoelectric tensor component α32.
Multilayer γ-ray exposure buildup factors of up to 40 mfp were calculated using an electron-photon cascade Monte Carlo code, EGS4, as a point isotropic source. A kind of splitting technique was used in the EGS4 calculations in order to obtain reasonable results at very deep penetration problems, such as 40 mfp.The dou…
Secondary electron (SE) emission from spacecraft surfaces as a result of energetic electron bombardment is a key process in the electrical charging of spacecraft. It has been suggested that incorporating more complete knowledge of the energy- and angular-distributions of secondary electrons is necessary to fully model…
In this paper, the fatigue cracking possibility in different kinds of copper bicrystals with large‐angle grain boundaries (GBs) and copper multicrystals containing some low‐angle GBs are compared. The results showed that the fatigue cracks, in the copper bicrystals, always nucleated firstly along GBs no matter whether…
Directional solidification under uniaxial stress is analyzed. In the absence of stress, it is well known that the moving planar front undergoes a morphological Mullins-Sekerka (MS) instability. Under uniaxial stress, even an interface at rest develops an instability known by the names of Asaro, Tiller, and Grinfeld (A…
The laser beam weldability of AZ31B magnesium alloy was examined with high power CW CO2 and pulsed Nd:YAG lasers. The low viscosity and surface tension of the melt pool make magnesium more difficult to weld than steel. Welding parameters necessary to obtain good welds were determined for both CW CO2 and pulsed Nd:YAG…
In this study, we present a novel approach to simulate and characterize the behavior of fibers during processing using a modified version of the familiar rotor ring system. With this modification, we attempt to create an area approximately resembling the carding zone and measure the energy required to shear the fibers…
The effects on goats of Calotropis procera latex given by different routes of administration were investigated. The administration of latex at 1 ml/Kg body weight via the oral route or at 0.005 ml/Kg body weight/day via the intravenous or intraperitoneal route caused death of the goats between 20 minutes and 4 days. W…
The largest application field for complex perovskite Pb(B′B′′)O3 relaxor based products has been multilayer ceramic capacitors (MLC). The other promising field for relaxor applications is piezoelectric transducers. One of the big advantages of relaxors-lead titanate PbTiO3 (PT) systems compared with PZT ceramics is th…
A eukaryotic fumarase is for the first time unequivocally shown to contain two distinct substrate-binding sites. Pig heart fumarase is a tetrameric enzyme consisting of four identical subunits of 50 kDa each. Besides the true substrates L-malate and fumarate, the active sites (sites A) also bind their analogs D-malate…