Materials Literature
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Abstract The chitosan derivatives containing antiradical fragments in the polymer side chain have been synthesized by interaction of the partially quaternized chitosan(QCH) with gallic acid (GA). The antioxidative activity of the chitosan derivatives — QCH‐GA was investigated by thiobarbituric method. Introduction of…
The initial stages of nucleation during liquid–liquid phase separation in mixtures of high molecular weight polymers was studied by time-resolved small angle neutron scattering. Phase separation was induced either by decreasing temperature or by increasing pressure. One of the blend components was labeled with deuteri…
The experimentally interesting ${\mathrm{Nb}}_{3}$ and ${\mathrm{Nb}}_{4}$ clusters and their cations have been studied in great detail using density-functional methodology in conjunction with relativistic effective core potentials. Close attention has been paid to full optimization along the flat potential energy sur…
Four substituted dithiobiurets (i.e., 1,5-diphenyl-2,4-dithiobiuret [DPDTB]; 1-anisidyl-5-phenyl 2,4-dithiobiuret [APDTB]; 1-tolyl-5-phenyl 2,4-dithiobiuret [TPDTB]; and 1-cholorophenyl-5-phenyl 2,4-dithiobiuret [CPDTB]) were synthesized to study their inhibiting effect on mild steel (MS) corrosion in 5 N hot hydrochl…
Within a semiclassical model, we investigate the dynamic neutralization and relaxation of slow ${(E}_{\mathrm{kin}}<100\phantom{\rule{0ex}{0ex}}\mathrm{eV})$ multiply charged ions which are reflected on metal surfaces. Special emphasis is devoted to near-surface interaction mechanisms. Our model includes a Monte Ca…
Joining is an enabling technology for the application of structural ceramics at high temperatures. Metal foil diffusion bonding is a simple process for joining silicon carbide or boron carbide by solid-state, diffusive conversion of the metal foil into carbide and silicide compounds that produce bonding. Metal diffusi…
Ethylene-propylene-diene rubber (EPDM) was reacted with thioacetic acid in the presence of 2,2′-azoisobutyronitrile (AIBN), giving rise to thioacetate-modified EPDM (EPDMTA). The extent of the incorporation was studied as a function of both thioacetic acid and AIBN concentration and reaction time. The products were an…
The variation of electrical resistance of near stoichiometric NiTi during some thermo-mechanic procedures was studied in this paper. The results show that when the R-phase does not exist in the near stoichiometric NiTi wire, the electrical resistance of NiTi wire increases linearly with the increase of strain at const…
The in situ thermal poling processes in germanosilicate fibers for positive and negative poling voltages are significantly different. Thermal poling of silica fibers consists of two processes: the faster linear process of charge migration and the subsequent single exponential process of charge ionization. Both the shi…
The performance and characteristics of a no rinse, titanium based conversion coating on an aluminium alloy have been studied using electrochemical techniques and transmission electron microscopy. Coatings were prepared from an aqueous H 2 TiF 6 solution, spin coated onto aluminium alloy 3003. The electrochemical behav…
The variation of the optical characteristics of thin films of oxidized porous silicon as a function of the preparation regime and subsequent heat treatment is investigated by ellipsometry. It is shown that the refractive index, optical thickness, and extinction coefficient of porous silicon films decrease monotonicall…
Abstract Bei der Hydroaminierung von Alkenen und Alkinen handelt es sich um Reaktionen, die auch 1999 noch nicht zum Standardwerkzeug der Organischen Chemie gehören. Viele der hier beschriebenen Verfahren sind auf einzelne Substratklassen oder sogar einzelne Substrate beschränkt, verwenden hochempfindliche und teure K…
Metastable amorphous ZrO 2 ‐Al 2 O 3 powders were hot‐pressed at low temperatures (873 and 923 K), under moderately high pressures (500 and 750 MPa), and amorphous pellets with 1%‐8% porosity were obtained. Crystallization of the amorphous pieces in the temperature range of 1173–1673 K produced a range of ultrafine mi…
Long bulky substituents do not affect the nonlinear optical properties of the octopolar system 1,3,5-trihydroxy-2,4,6-trinitrobenzene (THTNB), but lend it liquid crystal (LC) properties, as demonstrated here. The synthesis of this LC derivative (see Figure for structure) is described as are its thermal, mesomorphic, a…
Time-resolved fluorescence, particularly of millisecond lanthanide emission, is of considerable interest because of potentially increased sensitivity when short-lived autofluorescence is a problem. Lanthanides have also previously been shown to be excellent donors in resonance energy transfer measurements, where a lan…
A parallel-plate viscometer has been designed for use in an internally heated pressure vessel (IHPV) at pressures up to 350 MPa and at temperatures up to 900 ℃. The viscosity of a melt is determined by measuring the rate of deformation of a cylindrical sample as a function of an applied, constant stress at a fixed tem…
This is a study of electrode degradation mechanisms and reaction kinetics of LaNi 4.7 Sn 0.3 , La ( 1 − x ) Y x Ni 4.7 Sn 0.3 ( x = 0.1, 0.2, and 0.3) and La 0.7 Y 0.3 Ni 4.6 Sn 0.3 Co 0.1 metal hydride electrodes. Alloy characterization included X‐ray diffraction, X‐ray absorption (XAS), hydrogen absorption in a Siev…
Abstract Calcite production is understood largely as a longer—term phenomenon (e.g., seasonal whitings) that can occur in hardwater lakes, and is significant ecologically because it can slow the rate of eutrophication by reducing, through adsorption, the availability of nutrients to primary producers. In this study we…
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Using 2,6- and 2,4,6-alkyl-substituted sterically hindered primary amines, N-bonded silicon dichlorides RN(SiMe 3 )(Si(Me)Cl 2 ) (R = 2,6-Me 2 C 6 H 3 ( 1a ), R = 2,6- i -Pr-C 6 H 3 ( 1b ) and R = 2,4,6-Me 3 C 6 H 2 ( 1c ) have been prepared. Controlled hydrolysis of these dichlorides afforded the N-bonded silanediols…