Effect of the kind of heat tent of tools on friction in plastic deformation of automobile sheet

In sheet stamping, friction appears between the tool and the deformed preform. It is of interest to evaluate the difference in the friction coefficient in stamping by tools subjected to different kinds of heat treatment and chemical heat treatment.     

Modelling the dynamics of multicomponent ion exchange with dissimilar diffusivities of components

The dynamics of multi-ion exchange is investigated with consideration for electric fields arising in sorbents when the ions with distinct diffusivities are exchanged. A new model for this process is developed. Simulation shows that the electric field can affect the dynamic break-through curves. The proposed model can be used for the creation of a new process of sorbents regeneration and microcomponents concentration.     

Stress-strain state of a drill string and marine riser under their interaction in the open SEA

We consider the problem of interaction of a marine riser with a drill string inside it under the conditions of their joint bending in a strong sea current. We derive three-dimensional equations for the statics of the string and the riser which take into account the contact interaction and friction occurring under the displacements of the drill string inside the marine riser. A method is proposed for the numerical calculation of the stress-strain state of the drill string and marine riser. As an example, for the data of well drilling in the Straits of Gibraltar, we have calculated the regions of safe displacement of the offshore drilling rig that correspond to given safety factors. ^aCentral Research Institute for Prospecting for Nonferrous and Noble Metals, Moscow.^b“Energokosmos” Scientific Technical Center, Moscow, Russia. Translated from Problemy Prochnosti, No. 1, pp. 128 – 135, January – February, 1998.     

Change in the structure of alloy VT22 with the combined action of ultrasonic radiation and thermal cycling treatment

A study is made of the structure of alloy VT22 with thermal cycling treatment (TCT) and also with TCT and prior ultrasonic irradiation (USI) by the methods of metallography, electron microscopy, and hardness measurements. It is shown that TCT for annealed specimens promotes recrystallization, fragmentation, and spheroidization of and phases.It is established that TCT of specimens quenched to phase previously treated with ultrasonic radiation leads to formation of -phase platelets of considerably smaller dimensions and more strongly fragmented compared with -phase platelets after TCT for unirradiated specimens.Translated from Problemy Prochnosti, No. 10, pp. 47–49, October, 1990.     

Telomere Length in Metaphase Chromosomes of Human Triploid Zygotes

The human lifespan is strongly influenced by telomere length (TL) which is defined in a zygote—when two highly specialised haploid cells form a new diploid organism. Although TL is a variable parameter, it fluctuates in a limited range. We aimed to establish the determining factors of TL in chromosomes of maternal and paternal origin in human triploid zygotes. Using Q-FISH, we examined TL in the metaphase chromosomes of 28 human triploid zygotes obtained from 22 couples. The chromosomes’ parental origin was identified immunocytochemically through weak DNA methylation and strong hydroxymethylation in the sperm-derived (paternal) chromosomes versus strong DNA methylation and weak hydroxymethylation in the oocyte-derived (maternal) ones. In 24 zygotes, one maternal and two paternal chromosome sets were identified, while the four remaining zygotes contained one paternal and two maternal sets. For each zygote, we compared mean relative TLs between parental chromosomes, identifying a significant difference in favour of the paternal chromosomes, which attests to a certain “imprinting” of these regions. Mean relative TLs in paternal or maternal chromosomes did not correlate with the respective parent’s age. Similarly, no correlation was observed between the mean relative TL and sperm quality parameters: concentration, progressive motility and normal morphology. Based on the comparison of TLs in chromosomes inherited from a single individual’s gametes with those in chromosomes inherited from different individuals’ gametes, we compared intraindividual (intercellular) and interindividual variability, obtaining significance in favour of the latter and thus validating the role of heredity in determining TL in zygotes. A comparison of the interchromatid TL differences across the chromosomes from sets of different parental origin with those from PHA-stimulated lymphocytes showed an absence of a significant difference between the maternal and paternal sets but a significant excess over the lymphocytes. Therefore, interchromatid TL differences are more pronounced in zygotes than in lymphocytes. To summarise, TL in human zygotes is determined both by heredity and parental origin; the input of other factors is possible within the individual’s reaction norm.     

Behavior of Water and Oxygen Molecules on the Surface of Tin Dioxide Films

Polycrystalline films of compositions SnO₂, SnO_1.93F_0.07, 0.93SnO₂ · 0.07Sb₂O₃, and 0.97SnO₂ · 0.03CuO, which are of interest for use in gas-sensitive sensors, are prepared by the hydropyrolytic method from metal chlorides on a 22-XC ceramic substrate. The films prepared are studied using mass spectrometry, differential thermal analysis (DTA), and thermogravimetric analysis (TGA) at different temperatures. The results of mass spectrometric investigations demonstrate that, except for water (18 amu), no compounds in the mass range 10–70 amu are desorbed from all the films. The differential thermal and thermogravimetric analyses have revealed that desorption of water molecules from the film surface occurs in the temperature range 50–125°C and the oxidation processes associated with the oxygen chemisorption proceed beginning from a temperature of 125°C.     

Dielectric Properties and Phase Transition in the PbSe + PbSeO<Subscript>3</Subscript> Composite Material

Electrochemical cells in the form of pressed pellets and polycrystalline films prepared from the PbSe + PbSeO₃ two-phase composite are investigated by impedance spectroscopy. The dispersion analysis of the frequencies of the real and imaginary parts of the complex impedance made it possible to reveal a unified equivalent electric circuit for these cells and to calculate its parameters. The optical (ε_hf) and static (ε_lf) permittivities of the PbSe and PbSeO₃ phases are determined. The permittivities ε_hf = 20–45 and ε_lf = 200–280 obtained for the PbSe phase are in reasonable agreement with the data available in the literature. The temperature dependences of the ac and dc resistances indicate that the PbSe + PbSeO₃ composite undergoes a phase transition at a temperature T _c ? 363 K.     

Investigation into the Mechanism of Oxidation on the Surface of Lead Selenide Semiconductor Structures

The oxidation of lead selenide samples prepared in the form of ground powders, pressed pellets, polycrystalline films, and faceted crystals is investigated. All samples are produced from a lead selenide batch heat treated under dynamic vacuum. The bulk and surface structural and phase compositions of the samples upon oxidation in dry air at temperatures of 298–773 K are studied using electron microscopy, X-ray diffractometry, and Auger electron probe microanalysis. The dependence of the resistivity of polycrystalline films and pressed pellets is analyzed in the temperature range 298–498 K in dry air and argon. It is demonstrated that the specific features in the temperature dependences of the resistivity of oxidized PbSe samples can be associated with their microstructure and environmental conditions. It is revealed that the PbSeO₃ phase is formed on the surface of all the PbSe samples starting from room temperature, whereas no phase transformations are observed in the bulk of samples.     

Analysis of the human immune response to vaccinia by use of a novel protein microarray suggests that antibodies recognize less than 10% of the total viral proteome

Control of smallpox by mass vaccination was one of the most effective public health measures ever employed for eradicating a devastating infectious disease. However, new methods are needed for monitoring smallpox immunity within current vulnerable populations, and for the development of replacement vaccines for use by immunocompromized or low-responding individuals. As a measure for achieving this goal, we developed a protein microarray of the vaccinia virus proteome by using high-throughput baculovirus expression and purification of individual elements. The array was validated with therapeutic-grade, human hyperimmune sera, and these data were compared to results obtained from individuals vaccinated against smallpox using Dryvax. A high level of reproducibility with a very low background were apparent in repetitive assays that confirmed previously reported antigens and identified new proteins that may be important for neutralizing viral infection. Our results suggest that proteins recognized by antibodies from all vaccinees constituted <10% of the total vaccinia proteome.     

Ceramics and Thick Films Based on Bi2 – x(Pb, Sb)xSr2Ca2Cu3Oy Compounds as High-Tc Superconductors and Electrode Materials

Complex cuprates of the compositions Bi_1.6Pb_0.4Sr_1.8Ca₂Cu₃O _y and Bi_1.7Pb_0.2Sb_0.1Sr₂Ca₂Cu₃O _y are synthesized. The electrical properties of the superconductors prepared are investigated. Thin films based on the bismuth cuprates studied are produced. It is demonstrated that the thin films prepared can be used as electrodes being in contact with a solid electrolyte for designing oxygen partial pressure gauges.