Low Normal Pressure Research Articles

Preparation and characterization of thin films of copper(II) oxide by low temperature normal pressure metalorganic chemical vapor deposition

Using a volatile precursor, namely copper(II)hexafluoroacetylacetonate, it has been possible to prepare by the process of low temperature normal pressure metalorganic chemical vapor deposition, thin films of copper(II) oxide. These polycrystalline films were characterized by X-ray powder diffraction, scanning electron microscopy, energy dispersive X-ray analysis and by thermoelectric methods.

Surface compounds of transition metals: XXVIII. Polymerization of n-1-alkenes with surface chromium(II) on silica gel support at low temperatures and normal pressure

By reaction of linear 1-alkenes (C nH 2n with n = 3, 4, 5, 6, 7, 8, and 12) with surface chromium(II) at temperatures ≦ 20 °C and atmospheric pressure, poly-1-alkenes are formed in good yields. Ethylene produces a small amount of products only. The conversion rate depends on the concentration of the monomer, on the concentration of Cr(II) in the catalyst and on the quality of the catalytic sites. The molecular weight, typically in the range of 10 4 with a broad distribution, increases with lower reaction temperature. After the polymerization, the reaction product may be isolated by extraction and a new run can be performed with the same catalyst and the same or another monomer. Mixtures of two different linear 1-alkenes obviously undergo copolymerization since the corresponding mixed oligomers can be found.

The properties of a spinel copper cobaltite prepared at low temperatures and normal pressure

The properties of a spinel copper cobaltite obtained by thermal decomposition of mixed nitrates of both metals at 350°C and normal pressure are described. It has been shown that the maximum copper content (x) in the spinel Cu xCo 3−xO 4 does not exceed 0.9. When the copper amount in the initial mixture is higher a second phase CuO is formed. The copper ions are distributed over the A- and the B-sites of the spinel lattice, i.e. the spinel is partially inverted. Such a model explains well the data obtained about the lattice parameter, IR-absorption and the magnetic susceptibility of the samples with different x.

Comparison of True and Residual Friction Angles

ABSTRACT Both original and shear-induced fabrics have a significant influence on the deformation and strength properties of clays. The shear-induced structure appears to be the prime cause for the formation of constant residual angle irrespective of the stress history or the initial structure. Initiation of shear-induced fabric is controlled by the mobilization of true angle of friction. A comparison of true and residual friction angles from field data is made. The correlations of Bjerrum for residual friction angle and Skempton-Gibson- Bjerrum for true friction angle with plasticity index have been used to get additional data for the comparison. It is found that the residual friction angle is nearly equal to true friction angle for soils with clay content greater than about 40%. Residual friction angle approaches true friction angle at low normal pressure in soils with high percent of montmonillonite.

Review of Shearing Strength of Rockfill

The steady development of large scale triaxial shear testing equipment in the United States and Mexico in the past 20 yr has permitted the laboratory testing of rockfill specimens having up to 8-in. sized particles. Specimens of smaller sized particles can be tested under confining pressures of up to 2,000 psi. A review and consolidation of published test data and reports shows that competent authorities have found rockfill friction angles varying widely with various parameters such as confining pressure, relative density, gradation, particle strength, degree of saturation, particle shape, and so on. The most basic parameter appears to be confining pressure, with the consistent indication being that for average dumped rockfill, the friction angle varies from about 55° at very low normal pressure to about 35° at very high normal pressure.

Liquid phase dehydrogenation of isopropanol: Heterogeneous catalysis experiment

The liquid phase dehydrogenation of isopropanol to acetone on a porous nickel catalyst has readily measurable rates at a low temperature and normal atmospheric pressure.