Effect of Strain Rate on Discontinuous Flow and Mechanical Characteristics of High-Nitrogenous Steel

Experimental study on the effect of strain rate on discontinuous flow and mechanical characteristics of the high-nitrogenous steel Kh23AG19F has been performed. Within the range of strain rates from 4.62 · 10^-5 to 1.85 · 10 ^-4 s^-1, discontinuous flow, reflected by serration on the tensile diagram, is chiefly determined by intergranular deformation mechanisms. Under strain rates over 1.85 · 10^-2 s^-1, combined deformation modes prevail, which cause a change in the character of discontinuous flow and transform a serrated tensile diagram into a wavy graph, with the yield stress of steel increased significantly.     

Change in the structure and mechanical properties of complex glass fibres during dyring

Stekloplastik—Sertifikat Corporation Moscow. Translated from Khimicheskie Volokna, No. 2, pp. 58–59, March–April, 1994.     

Statistics of mesoplasma channel formation upon thermal breakdown stabilization in thin semiconductor films

A phenomenological model of the development of thermal breakdown in semiconductor films is considered, and it is shown that the average number of mesoplasma channels experimentally observed in the regime of thermal breakdown stabilization can substantially vary. The probability distribution function for the number of such luminous channels arising as a result of thermal fluctuations in a thin semiconductor film is calculated within the framework of a simple approximation.     

Formation of sediment in used industrial oil. Effect of temperature and solvent

Precipitation of sediment caused by external factors — temperature and solvent — is due to the spin nature of the contaminants formed during use of the oil. These paramagnetic contaminants also lead to aging of oils. Their total elimination restores the properties of used oil to the level of the base oil, but requires sufficient energy effects. __________ Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 1, pp. 29–31, January–February, 2006.     

On security arguments of the second round SHA-3 candidates

In 2007, the US National Institute for Standards and Technology (NIST) announced a call for the design of a new cryptographic hash algorithm in response to vulnerabilities like differential attacks identified in existing hash functions, such as MD5 and SHA-1. NIST received many submissions, 51 of which got accepted to the first round. 14 candidates were left in the second round, out of which five candidates have been recently chosen for the final round. An important criterion in the selection process is the SHA-3 hash function security. We identify two important classes of security arguments for the new designs: (1) the possible reductions of the hash function security to the security of its underlying building blocks and (2) arguments against differential attack on building blocks. In this paper, we compare the state of the art provable security reductions for the second round candidates and review arguments and bounds against classes of differential attacks. We discuss all the SHA-3 candidates at a high functional level, analyze, and summarize the security reduction results and bounds against differential attacks. Additionally, we generalize the well-known proof of collision resistance preservation, such that all SHA-3 candidates with a suffix-free padding are covered.     

Molecular Mechanisms of the Deregulation of Muscle Contraction Induced by the R90P Mutation in Tpm3.12 and the Weakening of This Effect by BDM and W7

Point mutations in the genes encoding the skeletal muscle isoforms of tropomyosin can cause a range of muscle diseases. The amino acid substitution of Arg for Pro residue in the 90th position (R90P) in γ-tropomyosin (Tpm3.12) is associated with congenital fiber type disproportion and muscle weakness. The molecular mechanisms underlying muscle dysfunction in this disease remain unclear. Here, we observed that this mutation causes an abnormally high Ca²⁺-sensitivity of myofilaments in vitro and in muscle fibers. To determine the critical conformational changes that myosin, actin, and tropomyosin undergo during the ATPase cycle and the alterations in these changes caused by R90P replacement in Tpm3.12, we used polarized fluorimetry. It was shown that the R90P mutation inhibits the ability of tropomyosin to shift towards the outer domains of actin, which is accompanied by the almost complete depression of troponin’s ability to switch actin monomers off and to reduce the amount of the myosin heads weakly bound to F-actin at a low Ca²⁺. These changes in the behavior of tropomyosin and the troponin–tropomyosin complex, as well as in the balance of strongly and weakly bound myosin heads in the ATPase cycle may underlie the occurrence of both abnormally high Ca²⁺-sensitivity and muscle weakness. BDM, an inhibitor of myosin ATPase activity, and W7, a troponin C antagonist, restore the ability of tropomyosin for Ca²⁺-dependent movement and the ability of the troponin–tropomyosin complex to switch actin monomers off, demonstrating a weakening of the damaging effect of the R90P mutation on muscle contractility.     

Gold supported on ceria and ceria–alumina promoted by molybdena for complete benzene oxidation

New gold–molybdena catalysts supported on ceria and ceria–alumina in reaction of complete benzene oxidation were studied. The catalysts were characterized by means of XRD, TPR, XPS and Raman spectroscopy. High and stable catalytic activity was established in the temperature region 200–240 °C. The presence of gold causes a modification in ceria structure leading to an increase of Ce³⁺ and oxygen vacancies formation. The loading of Al³⁺ increases additionally the oxygen vacancies, while a tendency of decrease of Ce³⁺ amount was observed. The presence of alumina results also in a larger share of active oxygen species proved by analysis of O 1s XPS spectra. The differences in the activities within the starting temperature range (150–180 °C) and in the region of 100% conversion (200–240 °C) could be explained by supposing that in the LT region the electron transfer between nanosized gold and ceria particles via oxygen vacancies has a crucial role. In the HT region the oxygen mobility, provoked by the defective structure of ceria due to the presence of Al³⁺, becomes of prevailing importance. It was also concluded that alumina prevents the gold and ceria agglomeration, which is the main factor to avoid deactivation under extreme reaction conditions.     

On the Coadsorption of Mephenaminate and Phenylundecanoate Anions at Passive Iron

Adsorption of sodium mephenaminate (SMEP), sodium phenylundecanoate (SPU), and their mixtures by oxidized iron from a borate buffer (pH 7.4) at the constant potential E = 0.2 V was studied by ellipsometry. Like the adsorption of the previously studied SMEP, that of SPU obeys the Frumkin equation with the higher Gibbs energy of adsorption (− ΔG _A ⁰ = 33.1 kJ/mol). The Frumkin equation fails for the adsorption of an equimolar SPU + SMEP mixture (inhibitor IFKhAN-31), which is described by the Bockris equation. The calculations showed that −Δ G _A ⁰ = 41.7 ± 0.2 kJ/mol and the number of water molecules displaced by an adsorbed inhibitor species from the metal-solution interface is n = 4. It was found that SMEP anions preadsorbed at oxidized iron do not affect the shape of the SPU adsorption isotherm, yet altering its constants. In the case of preadsorbed SPU, the SMEP adsorption isotherm changes its shape and cannot be described by any known adsorption equation. In addition, SMEP begins to adsorb at the electrode in lower concentrations; i.e., PU anions stimulate the adsorption of SMEP. __________ Translated from Zashchita Metallov, Vol. 41, No. 6, 2005, pp. 573–578. Original Russian Text Copyright ? 2005 by Kuznetsov, Andreeva.     

Thermal Characteristics of High-Efficiency Photovoltaic Converters of High-Power Laser Light

The influence exerted by the heat removal conditions on the extent of overheating of photovoltaic converters of high-power (>10³ W/cm²) laser light has been studied. The temperature of the p–n junction of photovoltaic cells was measured by recording the instantaneous values of the open-circuit voltage generated by laser light. The effect of cooling in high-efficiency photovoltaic cells (efficiency = 55%) via removal of a substantial part of absorbed optical power by the photocurrent into the external load was demonstrated. It was shown that, at laser radiation power of 2.5 W, the overheating of a photocell with an area of 1.7 × 10^–3 cm² relative to the copper heatsink temperature is 48°C in the no-load conditions and 30°C in operation with the optimal load.