Materials Literature
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Abstract The theory of transfer of electronic excitation energy between impurity molecules is developed without employing perturbation theory. The role of the lattice vibrations in the transfer process of the electronic excitation energy is taken into account. It is shown that the transfer time of electronic dipole ex…
SummaryThe behaviour has been examined of second-phase constituents in super-purity aluminium during etching in caustic soda, chemical brightening and anodizing in oxalic acid. Specimens containing large second- phase constituents were prepared using a carefully selected casting technique. Surfaces of specimens were m…
Adsorbed hydrogen on platinum-silica gives infra-red bands at 2040 and 2120 cm–1, and on platinum alumina at 2040 and 2110 cm–1. The 2110–2120 band is much enhanced by treatment by oxygen, and adsorption-desorption behaviour together with deuterium shift establish the band as due to weakly adsorbed hydrogen. It is pro…
The mode of action of ATP citrate lyase [EC 4.1.3.8] was investigated using a single homogeneous preparation from rat liver. First, the enzyme was incubated with labelled citrate and after incubation the protein portion was isolated through a column of Sephadex G-50. It was found that an enzyme-citrate complex is form…
By obtaining a clearer understanding of the mechanism of damping operating in manganese-copper alloys it may be possible either to improve damping properties at elevated temperatures or to select alternative systems with better ancillary properties. Electron-microscope, X-ray, and neutron-diffraction techniques have b…
Abstract Some series of solid solutions with perovskite‐type structure are synthesized and investigated, viz. the binary systems Nd 1− x , Me x MnO 3 where MeCa 2+ , Sr 2+ , Ba 2+ , and the ternary systems (Bi 1− x La x ) 0.5 Ca 0.5 MnO 3 and Bi 0.5 (Ca 1− x Me x ) 0.5 MnO 3 where MeSr 2+ , Pb 2+ , Ba 2+ . Distortio…
Blue oxophlorins are relatively strong bases and accept one proton (on nitrogen) to form green monocations; addition of a second proton (to the oxo-group) occurs in strongly acidic media to afford the dications derived from the tautomeric hydroxyporphyrins. Oxophlorins also form metal complexes derived from the hydrox…
The e.s.r. and electronic spectra and magnetic moments of Cu(NH3)2Ag(SCN)3 and [Cu(tren)NCS]SCN (tren = 2,2′,2″-triaminotriethylamine) are reported and compared with the previously reported data for trigonal bipyramidal complexes of the copper(II) ion. Theoretical expressions for the g-values for a copper(II) ion in a…
Abstract Two breaks are observed in the temperature dependence of both specific volume and logarithmic retardation time in isotactic polypropylene, indicating two glass transitions. In correspondence with two transitions, two loss peaks are found in isochronal measurement of dynamic mechanical loss at 3 Mc./sec. The l…
The results are described of some studies of a mechanism of energy dissipation due to strain-induced reorientation of tetragonality in binary manganese-copper alloys containing 60–90 wt.-% Mn. The dependence of the structure upon the progress of ageing and the temperature of observation is reported. A high damping cap…
Abstract not Available.
An aluminium-2% magnesium alloy solidified to a pronounced sub-structure shows, when tested in tension, at approximately 300°C an abrupt change in the mode of plastic deformation. Above this ‘transition’ temperature, where the flow stress maintains a steady value up to high strains, restoration is suggested to occur b…
Variable-temperature n.m.r. studies have proved the double alkoxide-bridged bi-octahedral (edge-shared) structure of the dimeric penta-alkoxides M2(OR)10, where M = Nb or Ta and R = Me, Et, or Bui. Rapid intramolecular double exchange of alkoxide groups occurs between (i) the two types of terminal group and (ii) the t…
The magnetism of the salts [Fe mephen3]X2 (X = I-, ClO4-, BF4-, PF6-; mephen = 2-methyl- 1,l0-phenanthroline) has been investigated over the temperature range c. 100-300ºK. The compounds exhibit anomalous behaviour, and this has been qualitatively interpreted as being the result of the presence of nearly equi-energeti…
Abstract The elastic constants of some single crystal specimens of nickel and f.c.c. nickel‐iron alloys have been measured at 4.2 °K and used to calculate values of the Debye temperatures. It is shown that by using these to re‐analyse some earlier specific heat measurements values of the spin‐wave contributions to the…
Phase equilibria of the vanadium‐oxygen system have been restudied in the composition range in order to establish the conditions required for stable existence of the phase. Using this knowledge, it was possible to prepare films of exhibiting transition in conductivity between semiconducting and metallic states. Films…
Abstract The synthesis of a new generation of high‐capacity oxidation‐resistant ion‐exchange resins and membranes is described which are sulfonic acid polyelectrolytes prepared from high molecular weight poly‐α,β,β‐trifluorostyrene. The difficult sulfonation of poly‐α,β,β‐trifluorostyrene is discussed in terms of the…
The occurrence of volume diffusion during anodic dissolution of Cu‐Au alloys at room temperature is shown again by x‐ray and electron diffraction, confirming the result of a previous study. After dissolution the intensity of the diffracted x‐rays is increased at Bragg angles, θ, corresponding to intermediate Cu‐Au com…
A re-determination of the crystal structure of platinum phthalocyanine has shown that there are two closely similar structures, both differing from that published by Robertson and Woodward. The basal projection of the original structure agrees with those of the two structures here described, but the space groups and t…
Abstract Star‐shaped macromolecules have been obtained by anionic block copolymerization of a monofunctional monomer and a divinyl compound with cumylpotassium or butyllithium as initiator. The polymer molecule is a crosslinked nodulus, to which n linear, solvated chains are attached. The shielding effect of these cha…