Materials Literature
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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…
Shear stress/shear strain curves for nickel single crystals containing 9 ppm hydrogen (0.045 at.-%) have been compared with those of hydrogen-free crystals over the range −196 to 100°C. The presence of hydrogen causes serrated yielding of the nickel and an increase in the shear stress τIII between − 125 and 0° C, but…
The electric field and potential distribution in the gap between a cylindrical rod having a hemispherical tip and an infinite plane perpendicular to the cylinder axis was determined using a charge simulation technique. This method assumes a charge at the center of the hemisphere and a finite number of semi-infinite ax…
Abstract It is shown that the application of the so‐called Drude's rule in obtaining the k ≈︁ 0 longitudinal optic mode frequencies (LO's) of multi‐resonance damped oscillators is not correct, although it may be used as an approximate method only when a few oscillators, all of appreciable strength, are present. A rigo…
Abstract The morphological character of the surface region of polyethylene has been considered with respect to adhesion and adhesive joint strength. By melting polyethylene onto a high‐energy surface (e.g., aluminum) we have provided for extensive nucleation and the formation of a transcrystalline region in the polyme…
New data are presented for single crystals of Na0.33V2O5. Conductivity along the b axis follows a dependence of the form σT = A exp( − E / kT) with E = 0.067 eV below 140°K and E = 0.057 eV above 140°K. The Seebeck coefficient changes from − 225 μV deg−1 at 70°K to − 135 μV deg −1 at 150°K; thereafter, it remains cons…
Abstract Flammability determinations have been made for epoxy resin formulations. The oxygen index, defined as the volume fraction of oxygen in an oxygen/nitrogen atmosphere that is required just to sustain steady candlelike burning of a stick of the material, has been used as the measure of flammability. The formulat…