Precision Spectrometric Determination of Th and Pu in Solutions with Arsenazo III Using Internal Standardization

A spectrophotometric procedure with internal standardization was suggested for precision determination of the concentrations of Th and Pu in the form of colored complexes with arsenazo III in nitric acid solutions. The sensitivity of the method was significantly improved owing to the use of colored complexes. The optical density optimum (0.3-0.5) of the solutions for spectrophotometric measurements can be achieved at concentrations in solution of the element analyzed as low as (2-3) ×10^-6 M, at the arsenazo and HNO₃ concentrations of 1 ×10^-4 and 6 M, respectively. With this composition of the solution, the relative rms deviation of the results for a single run is no greater than 0.15 and 0.3% for thorium and plutonium, respectively.     

Synthesizing the components of photopolymerizing acryl composites for production of waveguides with high transparency within telecommunication spectral regions

Methods for synthesizing hydrocarbon and fluorine-containing monomers and oligomers for the creation of planar polymer waveguides were developed. Over 20 mono- and bifunctional methacrylates of hydrocarbon and fluorinated alcohols, glycols, and diols were synthesized and characterized, and their physicochemical and spectral properties were studied. Polymers with low absorption in telecommunication spectral regions, i.e., near 800 and 1500 nm, and a wide refraction index range of 1.34?C1.557 were obtained by the method of photopolymerization. The developed oligomers were used to produce planar waveguides.     

The effect of a preparation from the horns of the saiga antelope on the goal-directed drinking behavior of rats

We analyzed 79 consecutive patients with aneurysms and found a patient who lacked type III collagen. Collagen was extracted from the skin, and the lack of type III collagen was determined by means of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Only 1 of the 79 patients was found to lack type III collagen. This patient was a 55-year-old man who had sustained an abdominal aortic aneurysm and aortic dissection. He did not show any of the typical clinical symptoms of Ehlers-Danlos syndrome type IV, such as hyperextensible skin and joints. He had none of the usual risk factors nor any clear family history of the syndrome. Furthermore, his collagen fibrils demonstrated a homogeneous appearance. This case may represent a new form of type III collagen deficiency.     

A Precision Spectrophotometric Method for Determining U,Pu, Nd,and Rh,Based on the Internal Standardization Principle

The principle of spectrophotometric determination of the concentrations of elements based on internal standardization of the sample analyzed is presented. As the function of the parameter to be determined, namely, the concentration of element in solution, we suggest the ratio of two signals, one of which is the light intensity at the wavelength of an absorption band of an element being analyzed and the other is the reference signal of a sample, namely, the light intensity at a wavelength at which the solution of the element being analyzed is virtually transparent. The analysis is performed with a specially designed two-channel spectrophotometer in which fairly strict correlation between the signals is provided by measuring their intensities virtually simultaneously, with the same detector and amplification system. The signals are isolated by a monochromator and interference light filters. The spectrophotometer operation control and data processing are effected by a PC. The metrological characteristics of the method proposed were experimentally determined. The relative root-mean-square deviation of the uranium, plutonium, neodymium, and rhodium concentrations in pure solutions of their salts was within 0.1-0.25%.     

Differential-Kinetic Determination of Microamounts of Thorium in Soils

Microamounts of thorium in soils can be determined by a differential-kinetic method based on the kinetic properties of the complex of thorium with 1,2-cyclohexanediaminetetraacetic acid (ThDCTA). The thorium content was determined spectrophotometrically upon decomposition of this complex in 0.1 M HNO₃ in the presence of Arsenazo III. The method involves anion-exchange isolation of Th from solution obtained by degradation of the soil material; it allows thorium determination in the presence of a number of impurities, which poses less stringent requirements on thorium separation from these impurities.     

Photopolymerization of acryl composites for producing waveguides with high transparency within telecommunication spectral regions

The photopolymerization of hydrocarbon and fluorine-containing monomers and oligomers synthesized in this work for the creation of planar polymer waveguides has been studied. The kinetics of the copolymerization of hydrocarbon and fluorinated compounds hardly depends on the number and structure of fluorinated moieties. The overall kinetics of the photoinitiated polymerization of acryl oligomers with different chemical nature of their oligomer block, molecular masses, and local and macroscopic viscosities has been studied by IR spectroscopy. At high initiation rates, the oligomer block’s flexibility, which is governed by the number of groups with a low potential rotational barrier, e.g., carbonate groups, is the principal factor that influences the kinetics of polymerization. At low initiation rates, the viscosity of oligomers becomes an essential factor. The optimal conditions for molding optical articles from hydrocarbon and fluorinated acryl oligomer composites have been determined.     

Determination of the isotope composition and content of U and Pu in environmental samples on the ultrasmall level by isotope dilution mass spectrometry

A procedure was developed for isolation and determination of the isotope composition and content of U and Pu on the ultrasmall level in environmental samples of technogenic origin, characterized by a small mass (up to 0.l g) and complex macrocomposition. The procedure is based on isotope dilution and mass-spectrometric measurement of the isotope ratios (IDMS). Subnanogram quantities of U and Pu were isolated using a modification of resin bead technique, involving sorption on a limited number of anion exchanger beads and allowing, after desorption, analysis of the solutions containing the selectively isolated nanogram quantities of U or 10^–12–10^–15 g of Pu. The measurements were carried out on thermal ionization mass spectrometers manufactured in Ukraine and Russia with a modernized ion registration system utilizing a position-sensitive detector based on microchannel plates. Uranium was analyzed by the laser luminescence method suitable for measuring fractions of nanograms of U accurately to within 10%. This procedure, combining highly sensitive methods of isolation of ultrasmall quantities of U and Pu with the mass-spectrometric method of analysis, is applied at the Radium Institute (acting as a national laboratory of IAEA) and at the Institute of Analytical Instrument Designing, Russian Academy of Sciences, in analysis of inspection samples submitted by IAEA for monitoring the activity of nuclear facilities under the Treaty on Nonproliferation of Nuclear Weapons.Translated from Radiokhimiya, Vol. 46, No. 5, 2004, pp. 464–470.Original Russian Text Copyright © 2004 by Stepanov, Makarova, Domkin, Pevtsova, Aleksandruk, Nikolaeva, Chubinskii-Nadezhdin, Kulikov.     

Destructive Analysis Determination of Neutron Emission from Spent RBMK Fuel

Absolute calibration of the UNIT-10m setup on the basis of the results obtained by destructive analysis is examined. The calibration procedure consists in performing measurements using the SKAT laboratory test stand at the Radium Institute with a model unirradiated assembly and neutron sources with known intensity, simulating neutron emission, comparing experimental data and calculations for certain reference points. The data obtained from destructive analysis can be used to establish a relation between the neutron flux of an irradiated assembly and the parameters being determined (fuel burnup, content of the main fissioning isotopes).A relation is presented between burnup and accumulation of the main neutron-emitting isotopes in spent RBMK fuel. The data were obtained by radiochemical and - and mass-spectrometric methods. The total neutron emission is determined taking account of the neutron yield from spontaneous-fission reactions of even isotopes of plutonium and curium and from (, n) reactions.     

Improvement of precision spectrophotometric method with internal reference and its application to analysis of plutonium solutions

A spectrophotometric precision method with internal reference [1, 2] was applied to analysis of straight Pu solutions for certifying Pu reference materials and for studying the PuO₂ solubility in the framework of developing methods for accounting and control of nuclear materials. In the context of the activities mainly concerned with certification of reference materials, a two-channel spectrophotomer and the corresponding technique were further improved in order to decrease the error of the method. This allowed the random component of the relative error of the method to be decreased from 0.1 to 0.04% at the confidence level p = 0.95 and the number of degrees of freedom f = 25. The fixed component of the error of the method was studied in relation to impurities of U, Np and corrosion products of structural materials. Also, the extent of Pu oxidation during sample preparation was studied as influenced by the fluoride ion. The revealed lack of such influence within the limits of the study indicates that the method is suitable for analysis of Pu in mixed solutions.     

An attempt at the objective evaluation of systems quanta in the drinking behavior of rats

The system architectonics of "systemoquanta" of rat drinking behavior was objectively evaluated in the dynamic process of its formation by means of studying intermediate and final results. The developed experimental equipment made it possible to determine characteristic features of formation and realization of drinking "systemoquanta" and the dynamics of their internal structure. Various "strategies" of system organization of identical behavior were revealed in rats of different groups. The revealed peculiarities of the internal structure of "systemoquanta" in rats of different groups are probably determined by the innate individual differences in the processes of prediction and estimation of intermediate and final results in the framework of strategic "systemoquantum" of drinking behavior.