Materials Literature
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La corrosion d'alliages Ni-Cr dans le verre fondu a ete etudie par les methodes electrochimiques classiques. Apres la determination des proprietes electrochimiques du verre sur electrode de platine, des mesures de potentiel de corrosion, de polarisation anodique et cathodique et de resistance de polarisation ont ete e…
All articles of this category The synthesis of new primary hydroxy- and aminotetrathiafulvalenes is described. The hydroxy derivatives 3a and 3b were synthesized from protected TTF thiolates while the amino derivatives 14a, 14b and 17 were prepared from the corresponding hydroxyTTFs using Gabriel synthesis or azide re…
Abstract The new mineral gordaite [14] from the Sierra Gorda, Chile, has chemical composition NaZn 4 (SO 4 )(OH) 6 Cl · 6H 2 O and crystallizes trigonal with space group P [unk]. The lattice parameters are a = 8.3556(3) Å and c = 13.025(1) Å. The structure was determined using direct methods and difference Fourier map…
For Lactobacillus pentosus D-lactate dehydrogenase, the binding of 2-ketoacids is markedly stabilized through interactions between the protonated imidazole of His-296, an acid/base catalyst of the enzyme, and the carbonyl oxygen of 2-ketoacids. The replacement of Arg-235 with Gln destabilized the inhibitory binding of…
The reduction of nickel (Ni 2+ ) and copper (Cu 2+ ) to their metallic forms is reported for Ni−Al and Cu−Al layered double hydroxides (LDHs). Ethylene glycol is used as the reducing agent (the so-called polyol process). The degree of reduction of both cations was found to be dependent on the time and temperature of t…
La corrosion du chrome a 1173K en atmospheres oxydantes, oxydantes-carburantes, oxydantes-nitrurantes, et oxydantes-carburantes-sulfurantes a ete etudiee a l'aide des melanges appropries de C, CO 2 , SO 2 et N 2 , ou H 2 O, H 2 et N 2 . Dans tous les melanges gazeux utilises la phase Cr 2 O 3 est toujours thermodynami…
PURPOSE: To evaluate the intratumoral distribution of liposome-encapsulated doxorubicin. MATERIALS AND METHODS: Tumor-bearing livers of 24 mice were studied with in vivo fluorescence and electron microscopy after injection of liposomal doxorubicin in the hepatic artery, portal vein, or tail vein. Distribution and upta…
The adsorption and thermal stability of vinyltriethoxysilane (VTES) was studied on a γ-Al 2 O 3 surface. Adsorption occurs near room temperature with the production of ethanol from the reaction with isolated surface Al OH groups, producing the surface species Al O Si(OC 2 H 5 ) 2 CH CH 2 . As the surface is heated, de…
The effect of thermo-oxidative aging on physical properties viz. modulus, tensile strength, elongation at break, tear strength and hardness of rice husk ash (RHA) and commercial fillers in ENR compounds have been studied. While the modulus and hardness increased with aging, other properties, i.e., tensile strength, el…
A correlation between the strength of the boson peak, R1(Tg), and the “fragility” of glass-forming liquids proposed earlier is reanalyzed more exactly for polymers. New experimental data are included, making the correlation more evident for the family of polymers. An additional correlation between R1(Tg) and the shape…
Single crystals of Cs 3 Bi 2 I 9 have been grown. Polarized-optical, dielectric, and calorimetric studies have been performed, along with measurements of birefringence, and the coefficients of elasticity c 44 , and linear expansion a over a wide temperature range. It is found that an intrinsic (pseudo-intrinsic) secon…
A spontaneous Raman scattering from the surface phonon modes (SPMs) of amorphous silica (SiO2) nanoparticles which is small compared with the excitation wavelength (514.5 nm) and aggregated in micron size clusters (globules) is utilized to determine the shape of particles. The excitation dynamics for these modes were…
A novel heterocyclic diamine monomer, 2-(4-aminophenyl)-6-amino-4(3 H )-quinazolinone was synthesized from readily available compounds in three steps in high yield. A series of novel polyimides containing the quinazolinone moiety were synthesized either by a one-step solution polymerization reaction or by a two-step p…
This article contains (i) an experimental EPR study on [4Fe−4S] 3+ and [4Fe−4S] + centers in single crystals of a model compound having an asymmetrical cubane-type cluster and (ii) a theoretical model for the interpretation of g -tensors of such states found in synthetic compounds and protein active sites. In the firs…
Samples of highly syndiotactic polypropylene (s-PP), when quench precipitated from solution, have an X-ray diffraction spectrum close to that calculated for the limit-ordered C 222 1 form II of s-PP. The solid state 13 C NMR CP MAS spectrum shows, however, evidences of the presence of a significant amount (≈20%) of lo…
Abstract The structure of Li- and Cs-montmorillonites was studied using infrared (IR) reflectance spectroscopy. The spectra of heat-treated clays between 80 and 220 °C were analyzed by Kramers-Krönig inversion in order to obtain the optical and dielectric properties of the clays. The analysis revealed the transverse-o…
Magnetic properties of two nitronyl nitroxide (4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl 3-oxide) radicals which show nearly isotropic S=½ alternating linear chains are investigated down to 0.5 K and up to 9 T. Pentafluorophenyl nitronyl nitroxide at low temperatures shows an antiferromagnetic chain with alte…
Vacuum drying and especially discontinuous vacuum drying is a very attractive process for such a wood as oak, because of a reduced drying time and a high quality of the final product. In this paper, a model describing heat, mass and momentum transfer in a capillary porous and hygroscopic medium under vacuum drying wit…
Bien que beaucoup de questions soient resolues en ce qui concerne l'oxydation acceleree des super alliages par les depots de sels corrosifs, il reste encore quelques questions sans reponses. La composition chimique du sel de mer qui entre dans les moteurs est differente de celle des sels qui adherent aux composants de…
A study of plastic instability in tension, which occurs well before the Considère criterion is met, is reported for face-centred cubic single crystals. The observations show that the instability is caused by a sudden effective decrease in work hardening resulting from the operation of a new dominant shear system. The…