Compton scattering in a large-aperture positron imaging system

Compton scattering of gamma rays within the image volume has been assessed for a large-aperture positron-emission-tomography imaging system. The Compton scattered attenuation and the Compton scattered background were both modeled and measured for point sources centered in scattering spheres up to 10 cm in diameter. Good agreement was obtained between simulations and measurements. The attenuation problem is independent of the detector system, but its correction is more difficult in a large-aperture system. The scattered coincidence background is large in this system (43% for a 10-cm-diameter scattering sphere), but the background overlap is reduced with 3D imaging.     

Polarographically active fraction of alpha 1-unstable glycoprotein in the blood serum during the malignant process

The simple method of polarographical testing of the peripheral blood serum is recommended as a part of the complex cancer diagnosis for the evaluation of the effectivity of cancer treatment and for the mass preventive examination. This method modified by I. A. Pelishenko (POISK-test) has permitted detecting a protein substance in the serum of cancer patients as well as in the serum both of the rats bearing Pliss sarcoma and in the serum of the irradiated dogs. It was proved that this protein indicates the presence of malignancy and represents polarographically active fraction of the alpha 1-unstable glycoprotein. This substance was designated as "Informative Pelishenko Protein" (IPP), and may be revealed by the polarographic indicator (IPM-01) made in Leningrad.     

Propagation of transverse bulk and surface acoustic waves in LiNbO (3) variable time-delay devices

Experimental measurements are reported on voltage-controlled acoustic time-delay lines operating at 1 GHz in the nearly pure shear-horizontal (S-H) mode in 38 degrees rotated Y-cut LiNbO(3). The high-acoustic velocity (4800 m/s) in conjunction with the large electroacoustic effect exhibited by this orientation allows high-frequency operation and optimum time-delay tuning sensitivity with a planar, single surface, device geometry. The authors demonstrate fractional time delay of 0.3x10(-6) V(-1 ) for surface electrodes that produce an in-plane E-field. However, the simultaneous excitation and propagation of both a leaky surface-acoustic wave (LSAW) and surface skimming bulk wave (SSBW), both as (nearly pure) S-H waves in these devices, seriously restricts the extent to which it is possible to maximize the time delay modulation sensitivity by reducing electrode gap spacing as done in similar SAW devices. The LSAW and surface-skimming body wave (SSBW) propagate at nearly the same velocity on a free surface, and perturbation of their velocity and relative attenuation rates by surface electrodes causes pronounced interference effects between the two modes for some device geometries.     

Commercial objectives,technology transfer,and systems analysis for fusion power development

Fusion is an essentially inexhaustible source of energy that has the potential for economically attractive commercial applications with excellent safety and environmental characteristics. The primary focus for the fusion-energy development program is the generation of centralstation electricity. Fusion has the potential, however, for many other applications. The fact that a large fraction of the energy released in a DT fusion reaction is carried by high-energy neutrons suggests potentially unique applications. These include breeding of fissile fuels, production of hydrogen and other chemical products, transmutation or burning of various nuclear or chemical wastes, radiation processing of materials, production of radioisotopes, food preservation, medical diagnosis and medical treatment, and space power and space propulsion. In addition, fusion R&D will lead to new products and new markets.Each fusion application must meet certain standards of economic and safety and environmental attractiveness. For this reason, economics on the one hand, and safety and environment and licensing on the other hand, are the two primary criteria for setting long-range commercial fusion objectives. A major function of systems analysis is to evaluate the potential of fusion against these objectives and to help guide the fusion R&D program toward practical applications. The transfer of fusion technology and skills from the national laboratories and universities to industry is the key to achieving the long-range objective of commercial fusion applications.     

Collagen and its rational content in meat products: Part 1. Analytical studies

Computer-assisted simulation has been used to study the effect of collagen content on the biological value of meat proteins. It has been shown that an increase in the collagen content from 2·5% to 15-20% of the total amount of proteins contained in minced meat tangibly enhances protein utilization for tissue synthesis. Hence, the above collagen content in meat products heightens their nutritional and biological value and renders them more suited for human metabolism.     

The minimum quantity of nitrite required to stain sliced and homogenised cooked pork

The levels of nitrite used in curing pork are in excess of those required to produce an adequate cured colour, but the minimum level for pink coloration to be visible has not been established experimentally. This paper demonstrates the effect of low nitrite levels from local surface application to pork muscle, simulating inadvertent contamination from work surfaces. An homogenate is used for comparison in which the nitrite was evenly distributed throughout the product. The results indicate that surface contact with nitrite produces essentially the same pattern of colour change as in the homogenate. Visible pink coloration was evident from 1-2 mg kg(-1) sodium nitrite absorbed.     

Vapor pressure measurements of para-hydrogen adsorbed on exfoliated graphite

Monolayer isotherms were measured for 15, 18, and 20 K for para-hydrogen adsorbed on exfoliated graphite foam, and for the second, third, and fourth layers in the temperature interval of 8 to 20 K, using the standard volumetric method. From the data, the isosteric heat of adsorption, molar entropies and internal energies were obtained as a function of coverage. The values for coverages above the third layer were compared to those at the p-H₂ bulk triple point, showing that, within our experimental uncertainty, the results are closer to the values of bulk solid para-hydrogen. Critical temperatures for the second and third layers and the triple point temperature for the second layer, were determined, yielding values of T_c2 = (10.0±0.1) K, T_c3 = (11.0±0.5) K and T_t2 = (6.5±0.1) K respectively. Features occurring along the monolayer coverages are compared to transitions which occur in the para-hydrogen phase diagrams adsorbed on graphite, obtained from heat capacity measurements by other authors. From the isotherms, compressibilities were calculated as a function of coverage for several temperatures. Whenever possible the obtained results were compared to existing data in the literature.     

Application of the monte carlo method in the processing of experimental data on dynamic deformation of materials

The article presents a method of processing the recorded diagram of deformations vs time t for the purpose of determining the time-dependent change of strain rate and acceleration. The method is based on the utilization of data of statistical tests (the Monte Carlo method) and the least squares method applied to the deviations of the functions (t) from the experimental curve at the specified number of points.Translated from Problemy Prochnosti, No. 8, pp. 20–22, August, 1992.     

Simulation of the condition of plane sections in the finite element method

An approach making it possible to simulate the condition of plane sections in solution of two-dimensional elastoplastic problems by the finite-element method is proposed.Translated from Problemy Prochnosti, No. 5, pp. 35–38, May, 1992.