Structure and Properties of Zinc-containing Copolymers Based on (Meth)Acrylate Monomers

The kinetic parameters of radical emulsion copolymerization of zinc-containing copolymers with esters of acrylic and methacrylic acids were studied. The effective relative activities of the monomers were calculated from experimental data and the properties of the metal-containing copolymers were assessed as influenced by the structure of the organic monomers.     

The MSR-investigation of antiferromagnetic phase transitions in erbium

The muon spin relaxation rate (T) in an orientated polycrystalline sample of erbium constructed of large monocrystals has been measured for temperatures 20 <T<300 K. It has been shown that the (T) for erbium is bounded from above asT T_N, whereT _N=84.4 K is the Néel temperature. This fact may be explained by assuming that atT=T_N erbium undergoes a weak phase-transition of the first order.     

Emulsion Polymerization of Styrene in the Presence of <Emphasis Type="Italic">C</Emphasis>-Phenyl-<Emphasis Type="Italic">N-tert</Emphasis>-Butylnitrone

The radical polymerization of styrene in an emulsion stabilized with an ionic surfactant, with C-phenyl-N-tert-butylnitrone as chain-terminating agent and ammonium persulfate as initiator, was studied.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 5, 2005, pp. 831–835.Original Russian Text Copyright © 2005 by Grishin, Lazarev, Semenycheva, Nikolaev.     

Thermogravimetric investigation of the dehydration thermodynamics of amorphous silica after its hydrothermal and thermovaporous treatment

After hydrothermal and thermovaporous treatment of chemically pure amorphous aqueous silicic acid in solutions of NaOH and NH₄OH and in water vapour it is possible, using complex thermal analysis, to detect the weight loss and heat effects corresponding to evaporation of various forms of combined water, and to estimate the heats of evaporation of these forms. From the obtained data, the following water forms have been identified: (1) at 200–300° capillary-condensed water formations of the cluster type evaporate;ΔH _deh is about 8 kcal/mole H₂O; (2) at 250–400°, molecules of water linked by hydrogen bonds with hydroxyl groups on the surface and in the volume of the particles;ΔH _deh. is about 5 kcal/mole H₂O; (3) at 350 600°, molecules of water coordinated to silicon atoms in the volume of the particles;ΔH _deh is approximately 1 kcal/mole H₂O. The total evaporation heat changes from 10 kcal/mole H₂O when water of form 1 predominates, to 5 kcal/mole H₂O when forms 2 and 3 predominate.     

Reducing nuclear danger through intergovernmental technical exchanges on nuclear materials safety management

The United States (U.S.) and Russia are dismantling nuclear weapons and generating hundreds of tons of excess plutonium and high-enriched uranium fissile nuclear materials that require disposition. The U.S. Department of Energy and the Ministry of the Russian Federation for Atomic Energy (Minatom) organizations are planning and implementing safe, secure storage and disposition operations for these materials in numerous facilities. This provides a new opportunity for technical exchanges between Russian and U.S. scientists that can establish an improved and sustained common safety culture for handling these materials. An initiative that develops and uses personal relationships and joint projects among Russian and U.S. participants involved in nuclear materials safety management contributes to improving nuclear materials nonproliferation and to making a safer world. Technical exchanges and workshops are being used to systematically identify opportunities in the nuclear materials facilities to improve and ensure the safety of workers, the public, and the environment.     

Stark spectroscopy of CuPc organic semiconductor with a submicron metal-electrode grating

The optical and electro-optical properties of organic copper phthalocyanine semiconductor (α- CuPc) have been investigated by Stark (electroabsorption) spectroscopy using a metal electrode grating with a submicron (0.88 μm) interelectrode distance. Differences between dipole moments (Δμ) and polarizabilities (Δα) in the excited and ground states of α-CuPc are measured for a nanoscale semiconductor film. It is concluded that the extremely high values of Δμ and Δα are in principle not parameters of individual α-CuPc molecules: they are determined by exciton effects specifically in the polycrystalline medium with a characteristic morphology of hyperfine films, which depends on the structure of the samples and their fabrication technology.     

EPR study of molecular complexes in frozen solutions

Conclusions A method was proposed for determining molecular complexes from the EPR spectra of the radical pairs that are formed during the photolysis of frozen solutions. The method has a greater range of application than the ordinary spectrophotometric method.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 625–626, March, 1979.