Materials Literature
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The interactions of nucleic acids with water-soluble porphyrins and metalloporphyrins have been investigated by stopped-flow and temperature-jump techniques. Both natural DNA (calf thymus) and synthetic homopolymers [poly(dG-dC) and poly(dA-dT)] have been employed. The porphyrins studied belong to the tetrakis(4-N-met…
Abstract The linear electrooptical tensor [ r ijk ] and the tensor of the adiabatic linear electrostriction [ d ijk S ] of lead tetraborate (PbB 4 O 7 , point group mm 2) have been determined: r 113 = +2.35(8), r 223 = +2.40(8), r 333 = +2.83(9), r 131 = +2.39(7), r 232 = +0.95(7); d 311 S = +2.8(2), d 322 S = +2.6(2)…
Abstract The high temperature form of melanophlogite, 46 SiO 2 · 6M 14 · 2M 12 (M 12 = CH 4 , N 2 ; M 14 = CO 2 , N 2 ), is cubic with space group Pm 3 n and a = 13.436(3) Å at 200°C. The mineral is isostructural with the cubic gas hydrates of type I. Structure refinement with 667 independent reflections led to a weig…
Forward Swept Wings have a number of advantages over Aft Swept Wings which have been appreciated for a number of years. In the past, however, their use has been restricted to limited degrees of sweep because of the severe weight penalty necessary to prevent aerolastic divergence. Recently, it has been shown that the o…
A comparative study was conducted to assess the potency of three ‘dusts’—PVC, α-quartz and titanium dioxide—in producing fibrosis at the site of deposition when administered to rats by the intrapleural and intraperitoneal routes. PVC and TiO 2 produced little reaction; this consisted mainly of macrophage accumulation…
Electron diffraction study of regenerated celluloses like viscose, cuprammonium. and polynosic rayons revealed the presence of cellulose I as an extraneous lattice in addition to the basic cellulose II lattice, hitherto shown by x-ray diffraction studies. This paper also investigates the possible causes for the highly…
Thin film permalloy magnetoresistors are frequently used in read heads and magnetometers. This paper presents a numerical model of a magnetoresistor, taking into account the shape anisotropy and the anisotropy dispersion. The results of computations for such complex model and a simpler one are compared with experiment…
The gelatinization process of potato starch was isothermally investigated at 52.5∽65.3°C. The degree of gelatinization was measured by an enzymic digestion method using glucoamylase. When the starch–water suspension was incubated at a definite temperature the gelatinization reached a limit at each temperature after 30…
On présente dans cet article les résultats d'une première série de recherches sur la dépollution des gaz d'échappement des moteurs diesel au moyen de pots catalytiques. L'efficacité des catalyseurs à base de platine pour l'oxydation du monoxyde de carbone et des hydrocarbures imbrûlés a pu être établie par des essais…
Reactions of chitosan (degree of deacetylation 67%, weight-average molecular weight 850,000) with formaldehyde were performed in a dilute aqueous acetic acid solution at a molar ratio of amino groups of the polymer to HCHO of 0.06:O.1 mol/L and at different temperatures (45, 60, and 75°C). In each case the pH of the r…
The Epstein-square is used as an internationally accepted standard for the measurement of the iron loss and permeability of electrical steels. In this investigation the power loss of nonoriented electrical steels was measured using the Epstein-square and also a single-strip tester. Single-strip testing showed importan…
Abstract The thermal transformation of anhydrous alumina obtained by the decomposition of the lactate, citrate and tartrate of aluminium has been examined by thermal analysis(TGA and DTA), infrared spectrophotometry and X‐ray diffraction study. It is found that under an atmosphere of air the thermal decomposition of a…
Abstract [Tetrakis(4-methylpyridyl)porphyrinato]manganese(III) (MnIII(tmpp)) undergoes reversible one-electron transfer reactions in aqueous solutions. The half-wave potential of MnIII/II(tmpp) redox couple is −0.21V (vs. 3.33 M KCl, AgCl/Ag) between pH 4 and 12. On the other hand, the half-wave potential of MnIV/III(…
Abstract The vulcanization of butyl and natural rubbers by p -dinitrosobenzene (DNB), p -quinone dioxime (GMF) and p -quinone dioxime dibenzoate (dibenzo GMF) oxidized by various oxidants was investigated. Good curing efficiency ( E=1.2 ) was achieved for a butyl system containing GMF or dibenzo GMF oxidized by red le…
Abstract Experimental results evidenced the chemical structure of phosphonium salts to be essential in the process of corrosion inhibition for zinc and iron metals in the presence of Ph 4−y P + Ry, X − compounds (0 ≤ y ≤ 4) in an acid medium. Several steps are involved in a complex mechanism, each of which being enhan…
Fast fracture strength data on slip‐cast reaction‐bonded Si 3 N 4 determined by uniaxial MOR, biaxial ball‐on‐ring tests, and speed of rotational failure measurements were correlated using Weibull statistics and finite‐element techniques. The agreement between predicted and observed values demonstrated the applicabili…
Abstract A simple theoretical model which examines the effect of structural disorder on the mobility of diffusing particles in amorphous materials is suggested. So, following Anderson's ideas, it is assumed that structural disarray results in a probability distribution of energy barrier heights for diffusion around so…
Grain oriented glass-ceramics of fresnoite (Ba2TiSi2O8) and its modifications Sr2TiSi2O8 and Ba2TiGe2O8 have been prepared by recrystallizing glasses in a temperature gradient. Piezoelectric voltage coefficients g33 and hydrostatic voltage coefficient gh of these glass-ceramics are comparable to those of PVF2 and an o…
The $2{p}_{\frac{1}{2},\frac{3}{2}}$ levels in ${\mathrm{As}}_{4}$ and the $2{p}_{\frac{3}{2}}$ level in ${\mathrm{Se}}_{5,6}$ have been measured by x-ray photoelectron spectroscopy with the use of 1486.6-eV ($\mathrm{Al}K\ensuremath{\alpha}$) radiation. The $2{p}_{\frac{1}{2}}$ binding energies have been calculated f…
Twin‐roller quenching was attempted for 15 pseudobinary systems combining two chosen from the lithium ortho‐oxosalts, i.e. Li 3 BO 3 , Li 4 SiO 4 , Li 4 GeO 4 , Li 3 PO 4 , Li 2 SO 4 , and Li 2 WO 4 . Glassy flakes were obtained in almost all systems. Glass formation was easier in systems containing large amounts of L…