Kinetics of solid-phase ligand-substitution reactions in diammine(1,4,8,11-Tetraazaundecane)chromium(III) bromide isomers

The kinetics of solid-phase reactions of substitution of coordinated ammonia by outer-sphere bromide ions in [CrL(NH₃)₂]₂Br₃·nH₂O, where L is 1,4,8,11- tetraazaundecane, n 2–2.5, was studied by a nonisothermal method by differential thermogravimetry, mass spectrometry, and investigations in a flow-type reactor. The kinetic stability of the isomeric salts increases in the series trans相似文献   

Sorption of Eremomycin on Carboxylic Cation Exchangers

The relationships of sorption of antibacterial antibiotic eremomycin on carboxylic cation exchangers were studied. The difference between gel-like and structurally segregated carboxylic cation exchangers were analyzed by potentiometric titration. The optimal conditions for sorption and desorption of eremomycin were found.     

Mesitylenesulfonic acid dihydrate: structure and proton conductivity

The molecular and crystal structure of single-crystalline mesitylenesulfonic acid dihydrate (1) was determined by X-ray diffraction and IR spectroscopy. According to X-ray diffraction data, water molecules in the crystal structure form H₅O₂ ⁺ cations stabilized by an intracationic hydrogen bond with a length of 2.45(1) Å. The formation of the asymmetric H₅O₂ ⁺ cation was confirmed by IR spectroscopy. The crystallographic nonequivalence of the water molecules results in a shift of the bridging proton from the midpoint of the strong hydrogen bond in the cation toward one of the water molecules. The proton conductivity of compound 1 was measured by impedance spectroscopy. Dihydrate 1 is completely dehydrated upon prolonged storage in a dry argon glove box and undergoes the transition to the dielectric state. Compound 1 is stable in the humidity range of 32–66 rel.%. The conductivity of dihydrate 1 is (2.4±0.3) · 10^?5 Ohm^?1 cm^?1 at 298 K, E _a = 0.21±0.01 eV.     

Determination of displacement of hole profile in cylindrical shells subjected to torsion using holographic interferometry

Moscow Engineering and Physics Institute. Translated from Prikladnaya Mekhanika, Vol. 24, No. 7, pp. 63–69, July, 1988.     

Estimation of the kinetic characteristics of sorption of an organic ion on a heterogeneous crosslinked polymer sorbent within the framework of a bidisperse model

For the sorption of rubomycin, an antitumor athracycline-type antibiotic, on BDM-12 carboxyl-containing heterogeneous crosslinked polymer sorbent, it was shown that the measured time dependences of the extent of process are determined by two characteristic times: τ₁ (in the range of short times) and τ₂ (at long times). A phenomenological theory of the kinetics of sorption on the heterogeneous sorbent was developed on the basis of a biporous sorbent model. The dependences of the characteristic times τ₁ and τ₂ on the sorbent grain radius were obtained. It was concluded that the theory makes predictions in good agreement with experimental data and allows calculating the most important kinetic parameters of sorption of organic ions on polymer sorbents: the time of diffusion of the sorbate into microgranules, the diffusion coefficient of the sorbate in transport pores, the effective coefficient of the sorbate diffusion into the heterogeneous sorbent, etc.     

Meson production in p + d reactions

Total and differential cross sections for the reactions p + d → ³He + m ⁰ with m=π, η and p + d → ³H+π⁺ were measured with the GEM detector at COSY for beam momenta between threshold and the maximum of the corresponding baryon resonance. For both reactions a strong forward-backward asymmetry was found. The data were compared with model calculations. The aspect of isospin symmetry breaking is studied. Representing the GEM Collaboration     

Optical second harmonic generation induced by picosecond terahertz pulses in centrosymmetric antiferromagnet NiO

Optical second harmonic generation at the photon energy of 2?ω = 2eV in the model centrosymmetric antiferromagnet NiO irradiated with picosecond terahertz pulses (0.4–2.5 THz) at room temperature is detected. The analysis of experimental results shows that induced optical second harmonic generation at the moment of the impact of a terahertz pulse arises through the electric dipole mechanism of the interaction of the electric field of a pump pulse with the electron subsystem of NiO. Temporal changes in optical second harmonic generation during 7 ps after the action of the pulse are also of an electric dipole origin and are determined by the effects of propagation of the terahertz pulse in a NiO platelet. Coherent oscillations of spins at the antiferromagnetic resonance frequency induced by the magnetic component of the terahertz pulse induce a relatively weak modulation of magnetic dipole optical second harmonic generation.     

Measurement of spin-dependent total cross-section differenceΔσ T in neutron-proton scattering at 16 MeV

A new measurement ofΔσ _T for polarized neutrons transmitted through a polarized proton target at 16.2 MeV has been made. A polarized neutron beam was produced with the³H(d, n)⁴ He reaction; proton polarization over 90% was achieved in a frozen spin target of 20 cm³ volume. The measurement yields the valueΔσ _T=(?126±21±14) mb. The result of a simple phase shift analysis for the³ S ₁?³ D ₁ mixing parameter ε₁ is presented and compared with the theoretical potential model predictions.     

A role of fringe pattern catalogue in the course of interferometrically based determination of residual stresses by the hole-drilling method

A further development of the technique for residual stresses determination in thick-walled structures, which is based on a combination of the hole-drilling method and reflection hologram interferometry, is presented. A plane specimen welded from two equal parts of dimensions 130×80 mm² in plane and thickness 12 mm is the object of investigation. Weld seam is performed along the shortest side of the specimen. Residual stress field of interest is formed by a superposition of initial welding-induced field and secondary stress field caused by plastic deformation of the specimen. A set of actual fringe patterns, which corresponds to a wide variety of residual stress components both ratio and sign, are reconstructed and presented as illustrations. A series of reference fringe patterns is simulated for the most typical cases inherent in residual stress field under study. It is shown that actual interferograms obtained belong to three main groups depending on a typical form of fringes configuration. On this base the main principles of creating the general catalogue of fringe patterns are established and the first version of this catalogue, which is related to reflection hologram interferometry, is developed. A structure of the catalogue that consists of both actual interferograms and reference fringe patterns is described. Possible ways of further catalogue completing and its direct implementing in the course of quantitative determination of residual stresses are discussed. It is shown that both experimental and numerical data aggregated into the first version of the catalogue can be effectively used for a verification of various coherent optics techniques with respect to a determination of residual stress components by means of hole drilling. An analysis of capabilities of reflection hologram interferometry in the field of residual stresses determination comparing with dual-beam speckle-interferometric techniques is presented. Superimposed residual stress field is quantitatively described in detail for both specimen sides of dimensions 260×80 mm². It is shown that fine nuances inherent in residual stress distributions over different specimen faces can be reliably derived from recorded fringe patterns of any type. This study serves as an example of residual stress components determination in real structure with a type of residual stress field to be investigated is unknown before the experiment.     

The interaction of erythromycin with polymeric sorbents adjusted to the antibiotic molecule

Cross-linked carboxylic cationites adjusted to sorption of the antibacterial antibiotic erythromycin were obtained by radical copolymerization of methacrylic acid, erythromycin methacrylate, and ethylene glycol dimethacrylate as a cross-linking agent. Studies of the sorption and desorption of erythromycin showed that adjusted sorbents had favorable equilibrium and kinetic characteristics of sorption and the ability to reversibly desorb the antibiotic. Original Russian Text ? O.A. Pisarev, N.M. Ezhova, I.S. Garkushina, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 1, pp. 142–146.