Direct Synthesis of a-(Benzotriazol-1-yl)alkyl Ethers
a-(Benzotriazol-I-yl)alkyl ethers were prepared in synthetically useful yields by direct reaction of the corresponding ethers with Nchlorobenzotriazole in the presence of Lewis acids.
Materials Literature
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Nitrofurantoin: Particle Size and Dissolution
Tablets manufactured from micronized anhydrous nitrofurantoin exhibited unsatisfactory dissolution properties, whereas excellent results were obtained with unmilled drug material having fine particle size.
Temperature and pressure dependences of the relaxation dynamics of supercooled systems explored by dielectric spectroscopy
A wide-band (102 − 2 × 1010Hz) dielectric study of epoxy compounds was carried out under isobaric conditions (atmospheric pressure) by changing the temperature down to the supercooled and glassy phases. One of these systems (diglycidyl ether of bisphenol A (DGEBA)) was also measured under isothermal conditions at 293…
Determination of the Ioffe-Regel limit for vibrational excitations in disordered materials
A theoretical analysis nas been made, in terms of the spectral density, of plane-wave vibrational modes propagating in disordered solids. The Ioffe-Regel crossover freauency for vitreous silica has been found to be ≃1 THz for both longitudinal and transverse waves. The analytic results agree well with the results obta…
Microstructural analysis of friction welded joints in TiNi alloy
A Ti-50.7 at % Ni shape memory alloy was welded by friction welding process at several upsetting pressures. The characteristics of individual phase which relates to shape memory phenomena and mechanical properties in a weld metal was investigated and discussed.Weld metal microstructures were identified using a transmi…
Electrochemical oxidative polymerization of binuclear ‘anil’ and ‘salen’-type complexes and tetrahydro derivatives
New kinds of modified electrodes have been prepared on the basis of electroactive polymers containing bimetallic ‘anil’ and ‘salen’-type complexes. New tetrahydro ‘anil’ ligands and complexes have been synthesized, giving birth to a new family of electroactive polymers. The polymers have been prepared potentiostatical…
Synthesis of doubly functionalized bis-tridentate ligands as building blocks for extended metallo-supramolecular assemblies and polymers
Doubly functionalized 4,6-bis(6-(2,2'-bipyridyl))pyrimidine ligands based on pyridine and pyrimidine units were synthesized starting from a commercially available nicotinic acid derivative using Stille-type carbon_carbon bond-forming reactions. The resulting hydroxy-terminated ligand, functionalized at the terminal py…
Understanding interactions between corrosion inhibitors and iron carbonate films using molecular modeling
Molecular modeling techniques have been used to study the adsorption and film formation of N-containing corrosion inhibitors on hematite (Fe{sub 2}O{sub 3}) and magnetite (Fe{sub 3}O{sub 4}) surfaces. In oilfield applications as temperature and carbon dioxide partial pressure vary, different corrosion products are for…
Improving Production, Control and Properties of Bearing Steels Intended for Demanding Applications
The advances of ladle metallurgy have led to very significant developments in the internal cleanliness of low alloy steel products. This development, which started with the design of the first functioning ladle furnaces with effective stirring facilities, has now reached a level where “standard” produced steels outper…
Partial Discharge Theory and Applications to Electrical Systems
Partial discharge monitoring is an effective on-line predictive maintenance test for motors and generators at 4160 volt and above, as well as other electrical distribution equipment. The benefits of on- line testing allow for equipment analysis and diagnostics during normal production. Corrective actions can be planne…
Core-level and valence band photoemission study of perovskite oxide powders synthesized by mechanically and thermally activated solid-state reaction
High-resolution core-level and valence band x-ray photoemission spectroscopy measurements were performed on perovskite oxide powders synthesized for applications in solid-oxide fuel cells by high-temperature solid-state reaction ( x = 0.3 and 0.19) and by room-temperature mechanical activation of the precursors ( x =…
Thermal creep analysis of noble metal alloys for the ceramic-fused-to-metal technique
Distortion of metal frameworks for the ceramic fused to metal technique during firing is attributed to thermal creep of the alloys. Usually thermal creep measurements are performed at constant load and constant temperature over varying time periods. Because metal frameworks for the ceramic-fused-to-metal technique are…
Room temperature synthesis of zinc pyrovanadate Zn3(OH)2V2O7·2H2O
Zinc pyrovanadate was prepared at room temperature by using a new method, which consists of mixing zinc oxide powder, ZnO·0.3H 2 O, with a 1.5×10 –3 M solution of vanadium oxide xerogel V 2 O 5 ·2H 2 O. After a short time of stirring, the pH of the solution increases from 3.2 to 5.8 and a yellowish green precipitate w…
Evaluation of the degree of cross-linking in UV irradiated porcine valves
A porcine heart valve was irradiated by Ultraviolet (UV) rays (10 W, 254 nm) for 2, 4, 8 and 24 hours at 4 degrees C to cross-link the structural collagen matrix. The degree of cross-linking was evaluated by assaying the released amount of hydroxyproline (Hyp) from the matrix, and comparing it with the positive contro…
Theoretical studies of force fields and IR spectra of isocytosine
The optimized geometries, complete harmonic force fields, and infrared intensities of isocytosine tautomers, amino-hydroxy and amino-oxoN(1)H, were calculated at the ab initio Hartree–Fock level using the 6-31G* basis set. The theoretical force fields were scaled by empirical scale factors, which were determined by fi…
Field Tests on Silica Removal from Geothermal Brines in Sumikawa and Onuma Geothermal Areas.
In a study on prevention of silica scale formation in geothermal applications, two silica removal methods were examined using actual geothermal brine in the Sumikawa and Onuma geothermal areas: one was the addition of silica gel seeds. The other was the addition of aluminum ions.The results for silica gel seed show th…
Heats of solution/substitution in TlNO3 and RbNO3 crystals from heats of transition. The complete phase diagram of the TlNO3–RbNO3 system
From measurements of the decrease in the heat (enthalpy) of transition in the solid phase by differential scanning calorimetry, the partial molar heats of solution at infinite dilution, χ, and the heats of solution or substitution, ΔHs°, of Tl+ in RbNO3 crystal and Rb+ in TlNO3 crystal along with their recovered latti…
Kinetics of oxidation of nitrogen compounds by cerium(IV)
The kinetics of oxidation by CeIV in sulfuric acid of hydrazine, hydroxylamine, nitrous acid, hydrazoic acid and of an intermediate involved in the nitrite/hydrazine reaction has been examined under a uniform set of conditions. Reaction proceeds through the free base form of the nitrogen substrate, probably by an inne…
Structure and Dynamics of Poly(Vinyl Alcohol) Hydrogel
Molecular dynamics simulations for models of poly(Vinyl Alcohol) hydrogels and pure water have been carried out over a wide temperature range including the glass transition temperature to examine structure and dynamics of supercooled water in hydrogels. The temperature dependences of thermodynamic properties and rotat…
The Hartree Approximation in Dynamics of Polymeric Manifolds in the Melt
The Martin-Siggia-Rose (MSR) functional integral technique is applied to the dynamics of a D - dimensional manifold in a melt of similar manifolds. The integration over the collective variables of the melt can be simply implemented in the framework of the dynamical random phase approximation (RPA). The resulting effec…