Materials Literature
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Abstract Specific features of development of micro‐ and macrofibrils as well as the structure of their interfaces are considered for oriented filaments of high‐density polyethylene with different initial supermolecular structures. As evidenced by SAXS, WAXS, EPR, Raman spectroscopy and electron microscopy, the melt‐cr…
The influence of organic fertilization on the increase of cation exchange capacity in calcareous soils is studied. Two soils with illite and interstratified illite-montmorillonite clay fractions, respectively, were fertilized with sheep and chicken manures and submitted to culture conditions during 3 years. The evolut…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis of fluorinated polysiloxanes. 8. Properties at low and high temperatures of polysiloxanes with fluorinated graftsB. Boutevin and B. YoussefCite this: Macromolecules 1991, 24, 3, 629–632Publication Date (Print):February 1, 1991Publication History Published online1 M…
Abstract Isochoric thermal conductivity and thermal pressure are studied of monoclinic and rhombohedral phases of solid CCl 4 at different densities in the temperature range 210 to 300 K and up to the pressures of 200 MPa. It is found that at constant density the thermal conductivity increases with increasing temperat…
Niobium pentoxide (T form, orthorhombic system) was utilized to promote devitrification in Li 2 O · Al 2 O 3 · 6SiO 2 glasses. Two or more mole percentage of this nucleating dopant enhanced crystallization in these glasses. Glasses containing 4.0 and 8.0 mol% T‐Nb 2 O 5 exhibited a high tendency to form dispersed TT‐N…
Abstract The possibility of wood charcoal as an adsorbent, not as an energy source as in the past, was confirmed by the use of an anionic surfactant as the model adsorbate, and a trial sorption of polluting substances in an actual river by a wood charcoal column was conducted.
A new method for analyzing the cation distribution of spinel crystals by extended X‐ray absorption fine‐structure spectroscopy has been developed to overcome the disadvantage of X‐ray diffraction, which cannot readily distinguish among different transition‐metal ions. EXAFS analysis was conducted on Ni 2+ and Fe 3+ io…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChemistry of iridium carbonyl cluster complexes. Synthesis and x-ray crystal structure determination of the [NMe3(CH2Ph)]3[Ir9(.mu.-CO)7(CO)13] complex containing a cofacial bioctahedral iridium cluster. Another example of different electron counting between isoskeletal rhod…
In the B phase of a chiral epoxy compound and its mixtures with an achiral liquid crystal material, a sign reversal in the electroclinic coefficient is observed. The temperature where the coefficient vanishes has been found to be almost independent on the concentration of the chiral molecules. A simple explanation is…
In order to identify an observation area with a scanning tunneling microscope (STM) and a particular area of the specimen, we developed a holder-type STM for an ultrahigh vacuum transmission electron microscope (UHV-TEM), operating in a reflection electron microscopy mode (REM). This instrument has been improved in th…
<div class="htmlview paragraph">A program to develop an aluminum tube stock alloy for vacuum-brazed heat exchangers with improved external corrosion resistance necessitated the use of accelerated laboratory corrosion tests to rank trial materials and ultimately qualify an alloy for production and sale. Brazed ra…
A study of the solution photophysical and photoredox properties of ReCl62- and ReBr62- is reported. The solutions are phosphorescent at room temperature, with emission maxima (lifetimes) of 1340 nm (80 ns) and 1380 nm (40 ns) for (Bu4N)2[ReCl6] and (Bu4N)2[ReBr6], respectively, in CH3CN. The phosphorescences are assig…
Abstract The surfaces of polymethylmethacrylate (PMMA) intraocular lenses (IOL) modified by treatment in a plasma containing various fluorine‐containing gases were studied by surface analytical techniques. The hydrophobicity imparted to the lens surface was monitored by water contact angle measurements and the degree…
The paper presents a kinetic approach to the problem of fusion of cracks. A kinetic equation for the size distribution function of cracks is derived. By division of all cracks into three groups a set of three simple equations is obtained. From a numerical analysis of the simple model we conclude that periodic solution…
Communciation: Mesogenic disc‐like compounds possessing a high permanent electric dipole moment are of interest as they offer the possibility of orientating columnar mesophases. The structure (schematically shown in the figure) which is similar to the well‐known toy “Diabolo”, and phase behavior of only the second exa…
Abstract Photochromic spiroindolinobenzothiopyrans having a methacryloxymethyl group have been prepared and their colored forms were demonstrated to be a zwitterionic structure on the basis of the spectroscopic data.
<div class="htmlview paragraph">The isostatic strength of porous cordierite ceramic monoliths plays an important role during canning and subsequent operation of automotive catalysts. Its value depends on wall porosity, cell geometry, skin thickness and morphology, monolith size and contour, and substrate/washcoa…
Epitaxie par evaporation sous vide de tetraphenylporphyrine (H 2 TPP). Cristallisation dans le systeme monoclinique avec a=1,20, b=1,90, c=1,47 nm, β=91 o et Z=4. Mise en evidence de la croissance de cristallites rectangulaires suivant quatre directions. Suggestion d'une orientation de la molecule plane H 2 TPP presqu…
Abstract Selective dehydrogenation of 2-propanol was performed with a suspended nickel fine-particle catalyst at high activity under refluxing conditions. The isotope effects, kH⁄kD for (CH3)2CDOH and (CD3)2CDOD were found to be 2.56 and 2.69, respectively, in contrast to 1.68 for (CH3)2CHOD, suggesting that the C–H b…
The synthesis of the β and γ forms of M(Ph 2 PO 2 ) 2 where M = Co and Mn are described and the compounds are characterized by infrared spectroscopy, differential scanning calorimetry, X-ray powder diffraction, and low-temperature (2–80 K) magnetic susceptibility studies. Single crystal X-ray diffraction studies are r…