Materials Literature
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29 Si NMR spectrometry has been used to determine the number molecular weight distribution of polymerization degrees of a system of oligomers formed in the sol-gel polycondensation of tetraethoxysilane (TEOS). On the basis of identification of the oligomers, monitoring of the concentration changes during the initial p…
A fine pore characterization method for less-crystalline porous solids has been applied to activated carbons. In the analysis, the microporosity of the solid was classified into effective micropores and inaccessible pores, depending upon the accessibility of the pore to an N2 molecule at 77 K. The volume fraction of e…
This paper presents the design, analysis, and application of permanent magnets in a hysteresis motor with a view to improve the overall performance of such motors. The novel rotor consists of 36% cobalt steel alloys with neodymium boron iron permanent magnets. This hybrid design combines the advantageous performance f…
A low-mass solution to electrical insulation in the lunar environment may be possible by embedding bare HV conductors within the lunar soil itself. In the paper, a 'standard' NASA soil (lunar simulant) representing chemical and physical conditions found in some lunar samples was used in laboratory experiments, and its…
The plasma polymerization of a variety of substituted perfluorocyclohexane monomers (perfluorocyclohexane, perfluoromethylcyclohexane, perfluoro-1,2-dimethylcyclohexane, perfluoro-1,3-dimethylcyclohexane, and perfluoro-1,3,5-trimethylcyclohexane) is systematically compared under identical experimental conditions. The…
The structure of the complex [(η5-Cp*)Co]2H3, a compound once believed to have an unsupported CoCo double bond, has been accurately determined with single-crystal neutron diffraction techniques. The arrangement of three hydrogen atoms in an equilateral triangle bridging the cobalt−cobalt bond, first revealed in an X-r…
A high iron content saponite from Griffith Park, CA, (griffithite variety) was pillared by aluminum polycation solutions with different Al/clay ratios. X-ray diffraction shows that the intercalation process begins when aluminum polycation solutions are added, being completed during the dialysis washing of the samples.…
Subsurface bilayers are found to exist at the air−water interface of spontaneously forming vesicular solutions of sodium bis(2-ethylhexyl)sulfosuccinate, (AOT). The bilayers produce long-range repulsive forces that increase the stability of foam and emulsion films formed from these solutions. In addition, during film…
The effects of neutron-induced damage on the tritium retention have been studied experimentally for graphite and other carbon-based materials in the damage range ⩽4 dpa and for beryllium in the range ⩽40 dpa. The results for graphite and other carbon-based materials are in qualitative agreement with previous studies w…
In the present paper, we describe the synthesis and characterization of a novel negative-type soluble photosensitive polyimide (PSPI). A group of new photosensitive polyimides has been prepared by condensation of dianhydrides bearing photoreactive ester groups and aromatic diamines in N -methylpyrrolidone (NMP), follo…
Thread interaction at the warp and weft crossing points of a tensioned fabric is an important aspect of the mechanical properties of the fabric. In this paper, a new approach to measuring changes in thread interaction at the crossing points due to fabric structure and yarn irregularity is discussed. This has been achi…
Variable-temperature 59 Co nuclear magnetic longitudinal relaxation and line width measurements have been performed on dilute aqueous solutions of 12 octahedral cobalt(III) complexes spanning a large range of isotropic chemical shifts (−1−12 570 ppm) at two fields (4.7 and 11.7 T). A variable-concentration 59 Co longi…
In the presence of catalysts, polycarboxylic acids such as meso -1,2,3,4-butanetetracarboxylic acid (BTCA) can cross-link cellulose in a process believed to involve cyclic anhydrides as intermediates. This study was undertaken to explore, in the absence of cellulose, interactions between catalysts and polycarboxylic a…
The binary phase diagram between (R) and (S) N-acetyl-α-methylbenzylaminehas been established by using differential scanning calorimetry and X-ray diffraction. Up to 337 K, the two enantiomers form an eutectic mixture without partial solid solution (i.e. conglomerate). At 337 K, the eutectoid equilibrium: conglomerate…
A highly sensitive flow injection technique involving oxidative cleavage and spectrofluorimetric detection was developed for the determination of methotrexate. Cerium(IV) trihydroxyhydroperoxide (CTH) was introduced as a packed reactor for the construction of a derivatization column which is used in a flowing system f…
Microcrystalline La2O3 outgassed at 873 K has a UV absorption edge centred at ca. 250 nm on which absorption ascribable to surface states is superimposed. This latter absorption is diminished by CO2 adsorption, which produces surface carbonate. UV reflectance and IR results with CO are correlated to show that CO adsor…
The effect of TiO2, ZrO2 and P2O5 as nucleating agents was discussed in a SiO2-Al2O3-MgO-CaO-Na2O glass system. Crystallization study of glass system containing these oxides indicated that only surface crystallization and not volume crystallization occurred. The crystals that were formed were wollastonite and a small…
The oxidation of CaS and SrS powders and thin films was studied in situ up to 1300 °C by thermoanalytical techniques (TG, DTA and high-temperature XRD) while FTIR and powder XRD were used to analyse ex situ the solid reaction intermediates and products. CaS powder starts to oxidize to CaSO4 around 500 °C but the oxida…
A self-propagated combustion technique for the synthesis of zirconia-doped barium titanate (BZT) is reported. The technique involves autocombustion of a citrate-nitrate gel at relatively low temperature (150–200 °C). The product is obtained after calcination of the resulting ash at ca. 800 °C. The method is very simpl…
Parameters of strength of isotropic high-density graphite are thought to be strongly correlated to pore structure of the graphite from experimental results on fracture toughness. Until now the pore structure has not been analyzed quantitatively, and the relation between the parameters of strength and the pore structur…