Materials Literature
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In enriched sea-water cultures inoculated with a mixture of algae and other organisms, concentrations of GeO2 above 1.5 mg/l specifically suppressed the growth of diatoms. In experiments with 14 pure cultures of diatoms (10 species), 1 mg GeO2/l sufficed to reduce the growth rates significantly; 10 mg GeO2/l was even…
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Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS) - an authoritative source of high-impact, original research that broadly spans the biological, physical, and social sciences.
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Abstract A review with 79 references.
A variational approximation is obtained for the resistance (or total entropy production) of a circular orifice in a plane diaphragm at which the scattering is specular. It is found that the Ohm's law prediction must be multiplied by a correction factor of the order of unity and added to the `small orifice' Knudsen con…
Abstract The viscoelastic properties of some polyester‐urethanes are compared with the properties of other polymers. The behavior observed is anomalous in that these polyurethanes exhibit an unusually high value of modulus well above their T g , unaccounted for by either crosslinking or crystallinity. Various experime…
A new theory of work hardening in dispersion-hardened single crystals—by which we mean soft crystals containing hard non-deforming particles of a second phase—is described. It is based on the fact that, if the particles do not deform plastically, and the interface between particle and matrix does not fracture, then se…
Abstract A new, general synthetic route to poly‐ p ‐xylylene and substituted poly‐ p ‐xylylenes is described. The key intermediate in the new process is di‐ p ‐xylylene [(2,2) p ‐cyclophane]. It has been found that di‐ p ‐xylylene is quantitatively cleaved by vacuum vapor‐phase pyrolysis at 600°C. to two molecules of…
CONTENTS I. Introduction 817 II. Tautomerism of phenols 818 III. Tautomerism of nitrosophenols 823 IV. Tautomerism of azophenols 825 V. Equilibrium phenol–quinonoid transformations of p -substituted phenols 827
Abstract Endor measurements on a type 1b diamond with paramagnetic nitrogen centres were made at 4.2, 77 and 300 °K by means of a 35000 Mc/s spectrometer. The axially symmetric nitrogen hyperfine coupling and quadrupole coupling parameters at 4.2 °K are Aiso., = 92.228 ± 0.001, Aaniso. = 10.903 ± 0.002, P = – 3.974 ±…
Received 24 October 1966DOI:https://doi.org/10.1103/PhysRevLett.17.1079©1966 American Physical Society
A three-layered rhombohedral form of molybdenum diselenide has been produced by subjecting the normal two-layered hexagonal form to pressures of 40 kilobars and temperatures of 1500 degrees C. The new form is isostructural with rhombohedral molybdenum disulfide.
Abstract The heats of combustion of graphite and diamond have been redetermined in a high precision aneroid calorimeter. It is shown that the result obtained for graphite is consistent with all recently published figures with the exception of that reported by Prosen & Rossini (1944). The latter is significantly hi…
EPR studies at X-band frequencies have been carried out between 300° and 77°K on amorphous and crystalline selenium. Dominating the spectra of the amorphous material were a large number of paramagnetic centers ∼1019/cc which contribute to an unusually broad and inhomogeneous line of width, ΔHp p∼3Kg and g=2.3 to 2.8±0…
The specific heat and dimensional changes of the porous 96% silica glass – water system were measured simultaneously between −35 °C and +2 °C with coverages of 1.6, 4.0, 5.3, and 7.7 molecular layers. The specific heat of the adsorbate below the transition range was found to be higher than that of ice. No phase change…
The crystal structure of the new complex, CH3NH3NiCl3, has been determined. The compound crystallizes in the space group Cmcm with a=6.94, b=14.94, and c=5.95 Å. Each nickel ion has a distorted octahedral coordination with two chloride ions at 2.405 Å and four chloride ions at 2.351 Å. Adjacent octahedra along the c a…