Features of the phase fluctuation structure of a laser beam in a turbulent medium

A method for reconstruction of the laser beam phase from shearing interferograms using separation of the amplitude and phase parts of the spatial spectrum is proposed and tested both numerically and experimentally with a laboratory model of the turbulent atmosphere, which allows purposefully varying the state of turbulence and controlling its parameters. Amplitude-phase correlation in the fluctuation structure of the laser beam that passed through turbulent medium is investigated. The recorded correlation coefficient typical of weak fluctuations varies in the range of 0.2 to 0.3.     

Effect of the conditions of isolation on the physicochemical properties of human serum albumin in the norm and with pathology

Differential scanning calorimetry and IR spectrosocopy were used to investigate the effect of the procedure of isolation of human serum albumin on its physicochemical characteristics. It is shown that fractionation of blood plasma with ethylene glycol followed by ion exchange chromatography can be used to obtain albumin of normal donors that is similar to the albumin in the nonfractionated plasma according to melting thermograms. Endotherms of human serum albumin samples that were obtained by affinity chromatography and preparative electrophoresis are bimodal, unlike the monophasic for albumin obtained by polyethylene glycol precipitation. These changes result from a higher content of nonetherified fatty acids in the albumin samples obtained by affinity chromatography and from modification of the secondary protein structure in the samples obtained by electrophoresis. Analysis of melting thermograms of serum albumin from patients with uremia, chronic hepatitis, and peritonitis shows that fractionation of blood with polyethylene glycol preserves the thermodynamic characteristics of the various pathological serum albumins to the greatest extent. The present results demonstrate the advantage of polyethylene glycol fractionation for isolation of native preparations of normal and “pathological” human serum albumin. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 32–37, January–February, 1997.     

Mössbauer characterization of tin dopant ions in the antiferromagnetic ilmenite MnTiO3

Mössbauer parameters of ¹¹⁹Sn diamagnetic dopant cations in an antiferromagnetic compound having the ilmenite structure are for the first time reported. The spectra reveal a well resolved hyperfine splitting pattern of combined magnetic and quadrupole interactions (at 5 K, δ=0.19 mm/s, H₁=52.5 kOe, eV_ZZQ_3/2=−0.80 mm/s, θ≈0°). This spectral component whose contribution (A₁=82%) represents more than four fifths of the total amount of the dopant (Sn/(Mn+Ti)=1/200) is assigned to Sn(IV) ions located in the bulk of MnTiO₃, on the Mn(II) site, and with a Mn(II) vacancy in their nearest surrounding. Two spectral components with minor contributions are also observed: one of them (H₂≈25 kOe, A₂=8%) can be assigned to Sn(IV) ions, in the MnTiO₃ lattice as well, on a site where they exhibit a weaker spin polarization (this site could be the Ti(IV) one) and the other (H₃=0 kOe, A₃=10%) to SnO₂ or/and Ti_1−xSn_xO₂ clusters. The Néel temperature of MnTiO₃ probed by the ¹¹⁹Sn dopant (T_N=69±2 K) agrees well with the values previously provided by ESR and antiferromagnetic resonance measurements. Variation of H₁ with temperature follows close the Brillouin function for S=5/2. No perturbation appears in the Mössbauer spectra around T=90 K where a broad peak, characteristic of 2D magnetic interactions, is observed on the static magnetic susceptibility curve.     

IR spectrum of cellulose

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 51, No. 2, pp. 301–306, August 1989.     

A diamagnetic Mossbauer probe method for studying a solid-gas interface and related catalytic processes

The results of recent studies involving the application of diamagnetic Mossbauer dopant cations for the investigation of heterogeneous catalytic reactions are described. Possibilities for using the information contained in Mossbauer spectra to clarify the nature of active catalytic centers are discussed. It is shown that, in some cases, the catalytic tests allow the correctness of the chemical interpretation of spectral parameters of the dopant atoms under study to be verified.     

Using the Mössbauer spectroscopy of <Superscript>121</Superscript>Sb nuclei to differentiate the effects of Cr and Sb co-dopants on the photocatalytic activity of anatase-type polycrystalline TiO<Subscript>2</Subscript> powders

The rates of the photocatalytic decolorization of methyl orange solutions in the presence of anatase powders modified by Cr³⁺ and Sb⁵⁺ co-dopants are compared with allowance for data on the actual valence state of antimony in the catalyst, obtained using ¹²¹Sb Mössbauer spectroscopy. The reported results point to the catalytic activity of the Cr⁶⁺ ions formed to compensate for the Cr³⁺ charge deficit in antimony-free samples.     

IR spectroscopic analysis of the structure of a biospecific sorbent based on a polyethylene matrix

We have used IR spectroscopy to study the structure of a biospecific sorbent based on a polyethylene matrix, modified by radiation grafting of acrylic acid with L-tryptophan methyl ester as the ligand. We show that grafted polyacrylic acid forms on polyethylene beads. We have established that chemical addition of the ligand to the modified polyethylene matrix occurs with participation of COOH groups of the polyacrylic acid and NH2 groups of the L-tryptophan methyl ester. We have observed that in the end product, strong hydrogen bonds are formed between the carbonyl groups of the ligand and the unreacted carboxyl groups of the grafted polyacrylic acid.