The set of structural-mechanical properties of steel 40X has been optimized in preparation for the cold upsetting of long high-strength bolts. The properties were optimized by analyzing different factors that determine the quality of the sized rolled products used for the production of hardware items by cold upsetting. An effi cient method was developed to prepare steel 40X rolled products with diameters of 9.65 and 11.7 mm and a 9.8 strength rating for the production of long high-strength short-head bolts without having to quench and temper the products. The low-waste technology that is proposed for preparation of the rolled products replaces spheroidizing annealing with the isothermal process of patenting. Such a substitution reduces energy and labor costs while improving the environmental characteristics of the production process and the reliability of bolted products. It also eliminates the formation of quench cracks, obviates the need for knurling the products, reduces the danger of the formation of defects on the threads, and lowers the cost of making long bolts. These changes in turn make it possible to shorten the production process and reduce the cost of producing high-strength bolts.Among the most important goals in modern mechanical engineering are improving the quality of metal products and parts made from them, elevating their performance and reliability to world standards, ensuring that Russian-made products are competitive in the domestic and international markets, and satisfying environmental regulations while also developing new production processes [1-3]. Fasteners made from wire composed of medium-carbon, high-carbon, and alloy steels constitute one of the most widely used class of parts in machine construction here and abroad. In connection with this, the most widely used and most progressive method of making hardware items is the cold upsetting of bright-drawn rolled products.Steel 40X is now used quite frequently in hardware production. Roughly 60% of the fasteners of strength class 10.9 or higher are made of this steel, with upset bolts of steel 40X subsequently undergoing quenching and tempering. Highstrength fasteners account for only 15-18% of all of the fasteners made in Russia, but abroad this percentage is 90-95% (for fasteners of strength class 8.8 or higher). Thus, expanding the production and use of high-strength fasteners is an important concern for Russian industry.In the existing process production, the entire rolled product is rid of scale by pickling it in a concentrated solution of sulfuric acid. The technology used to make long high-strength bolts should ensure the production of bolts with a strength rating of 8.8 or higher under the government standard GOST 1759.4-87. In other words, hardware items need to be made with the use of quenching and tempering in order to obtain the necessary mechanical properties.The main method of producing high-strength fasteners composed of steel 40X is upsetting of the rolled product after drawing, when it has a microstructure of granular pea...

1H-Pyridine-2-selenenyl dibromide, C5H5NSeBr2, 1, is a product of the bromination of bis(pyridin-2-yl) diselenide in methylene chloride recrystallization from methanol. Compound 1 is essentially zwitterionic: the negative charge resides on the SeBr2 moiety and the positive charge is delocalized over the pyridinium fragment. The C—Se distance of 1.927 (3) Å is typical of a single bond. The virtually linear Br—Se—Br moiety of 178.428 (15)° has symmetrical geometry, with Se—Br bonds of 2.5761 (4) and 2.5920 (4) Å, and is twisted by 63.79 (8)° relative to the pyridinium plane. The Se atom forms an intermolecular Se...Br contact of 3.4326 (4) Å, adopting a distorted square-planar coordination. In the crystal, molecules of 1 are linked by intermolecular N—H...Br and C—H...Br hydrogen bonds, as well as by non-covalent Se...Br interactions, into a three-dimensional framework. (3aSR,(9aRS)-2,3,3a,9a-Tetrahydro-1H-cyclopenta[4,5][1,3]selenazolo[3,2-a]pyridinium-9 bromide, C10H12NSe+·Br−, 2, is a product of the cycloaddition reaction of 1 with cyclopentene. Compound 2 is a salt containing a selenazolopyridinium cation and a bromide anion. Both five-membered rings of the cation adopt envelope conformations. The dihedral angle between the basal planes of these rings is 62.45 (11)°. The Se atom of the cation forms two additional non-covalent interactions with the bromide anions at distances of 3.2715 (4) and 3.5683 (3) Å, attaining a distorted square-planar coordination. In the crystal, the cations and anions of 2 form centrosymmetric dimers by non-covalent Se...Br interactions. The dimers are linked by weak C—H...Br hydrogen bonds into double layers parallel to (001).

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The development of safe nuclear power focuses basically on the creation of reactors using natural safety principles, which meet the following goals: reduction in the role of internal risk factors and the levels of perturbation that might lead to accidents; and appropriate choice of feedback to ensure reactor stability.Reducing the level of perturbation in reactors basically entails minimizing the margins of reactivity, including the operative margin of reactivity, the burnup component, xenon contamination, and the temperature effect of reactivity.Self-protection of the reactor is ensured mainly by consistent feedback with respect to reactivity (temperature, density, and other coefficients of reactivity). The feedback must be such that any transient process due to any perturbation or combination of perturbations will not lead to rupture of the safety screens and the release of radioactivity into the coolant system. In principle, such well-matched feedback is possible by the appropriate choice of the active-zone construction and materials, the coolant, the fuel composition, and the basic working parameters of the reactor.Current designs of modular high-temperature gas reactors (HTGR) largely satisfy natural safety principles [1]: passive heat release of the residual energy liberation in losses of forced helium circulation (LOFWS-type accident) and negative power and temperature coefficients of reactivity in the working state. In addition, continuous fuel reloading means that the burnup margin of reactivity can be eliminated. However, there is a large margin of reactivity in terms of shutdown cooling (p > 10/~),*The aim of the present work is to show the possibility of self-protection of HTGR relative to any reactive accidents (of TOPWS type) by the choice of fuel reloading with the required combination of temperature coefficients of reactivity.The physical preconditions suggesting the possibility of meeting these goals are: the large range of fuel and graphite temperature variation (-1000-1500~ the temperature dependence of the effective resonant integral of the starting nuclides (uranium and thorium) in a system with double heterogeneity; the use of fissile nuclides with a resonant structure of the cross section in the thermalization region.First, we consider the criterion of optimal fuel reloading in terms of internal safety with respect to TOPWS-type accidents.For the sake of simplicity, attention is confined to the point model of an infinite reactor with spherical packing. Any permissible steady state of the reactor is assumed to be characterized by some mean temperature T of the spherical fuel element and a specified mean energy intensity P. In view of the low density and the small absorption cross section of helium, its influence on the multiplying and scattering properties of the spherical charge may be neglected. Therefore, all possible states of this reactor may be described by the coordinates P and T; at fixed fuel-element energy intensity, its mean temperature may vary in some range with variation in hel...

Cycloaddition of 2-Pyridinetellurenyl Chloride to Alkenes. -The cycloaddition reactions proceed both regio-and diastereoselectively. -(BORISOV*, A. V.; MATSULEVICH, Z. V.; OSMANOV, V. K.; BORISOVA, G. N.; NAUMOV, V. I.; MAMMADOVA, G. Z.; MAHARRAMOV, A. M.; KHRUSTALEV, V. N.; KACHALA, V. V.; Russ. Chem. Bull. 61 (2012) 1, 91-94, http://dx.doi.org/10.1007/s11172-012-0013-x ; Alekseev State Tech. Univ., Nizhnii Novgorod 603950, Russia; Eng.) -H. Haber 16-178