Development of wear-resistant coatings compounds for high-speed steel tool using a combined cathodic vacuum arc deposition

This article presents the work on wear-resistance coatings (WRC), formed on the working surfaces of HSS tools, in order to increase their efficiency. The wear-resistant complex includes nitride layer, which increases the plastic strength of the HSS tool cutting wedge and cutting tool wear resistance, as well as a three-layer nano-structured composite coating that increases tool life. The equipment for the processes of ion nitriding in the gas plasma and the formation of nano-structured multi-layer composite coatings in the filtered metal-gas plasma cathode vacuum arc discharge has been developed. Particular attention was paid to the regularities in the formation of the nitride layer and optimization of its parameters and structure, together with the study of the properties and structure of functional coating layers, depending on the parameters of the deposition process. The parameters of the combined cathodic vacuum arc processing (CCVAP), provides minimum intensity of tool wear during the cutting tests. Sample of coated tools were used to conduct a certification of the developed WRC. This allowed determining the optimal parameters WRC that provided the maximum increase in tool life for a variety of cutting conditions. The outcomes are compared with uncoated HSS tool and standard commercial coatings

Reshuffling the OPE: Delocalized Operator Expansion

A generalization of the operator product expansion for Euclidean correlators of gauge invariant QCD currents is presented. Each contribution to the modified expansion, which is based on a delocalized multipole expansion of a perturbatively determined coefficient function, sums up an infinite series of local operators. On a more formal level the delocalized operator expansion corresponds to an optimal choice of basis sets in the dual spaces which are associated with the interplay of perturbative and nonperturbative N-point correlations in a distorted vacuum. A consequence of the delocalized expansion is the running of condensates with the external momentum. Phenomenological evidence is gathered that the gluon condensate, often being the leading nonperturbative parameter in the OPE, is indeed a function of resolution. Within a model calculation of the nonperturbative corrections to the ground state energy of a heavy quarkonium system it is shown exemplarily that the convergence properties are better than those of the OPE. Potential applications of the delocalized operator expansion in view of estimates of the violation of local quark-hadron duality are discussed.Comment: Talk given at conference Continuous advances in QCD 2002 / Arkadyfest, Minneapolis; 16 pages, 4 figure

A Rigidifying Salt-Bridge Favors the Activity of Thermophilic Enzyme at High Temperatures at the Expense of Low-Temperature Activity

Although enzymes from thermophiles thriving in hot habitats are more stable than their mesophilic homologs, they are often less active at low temperatures. One theory suggests that extra stabilizing interactions found in thermophilic enzymes may increase their rigidity and decrease enzymatic activity at lower temperatures. We used acylphosphatase as a model to study how flexibility affects enzymatic activity. This enzyme has a unique structural feature in that an invariant arginine residue, which takes part in catalysis, is restrained by a salt-bridge in the thermophilic homologs but not in its mesophilic homologs. Here, we demonstrate the trade-offs between flexibility and enzymatic activity by disrupting the salt-bridge in a thermophilic acylphosphatase and introducing it in the mesophilic human homolog. Our results suggest that the salt-bridge is a structural adaptation for thermophilic acylphosphatases as it entropically favors enzymatic activity at high temperatures by restricting the flexibility of the active-site residue. However, at low temperatures the salt-bridge reduces the enzymatic activity because of a steeper temperature-dependency of activity

Lactation Defect in a Widely Used MMTV-Cre Transgenic Line of Mice

MMTV-Cre mouse lines have played important roles in our understanding about the functions of numerous genes in mouse mammary epithelial cells during mammary gland development and tumorigenesis. However, numerous studies have not included MMTV-Cre mice as controls, and many investigators have not indicated which of the different MMTV-Cre founder lines were used in their studies. Here, we describe a lactation defect that severely limits the use of one of the most commonly used MMTV-Cre founder lines.To explore the role of protein tyrosine phosphatase Shp1 in mammary gland development, mice bearing the floxed Shp1 gene were crossed with MMTV-Cre mice and mammary gland development was examined by histological and biochemical techniques, while lactation competency was assessed by monitoring pup growth. Surprisingly, both the Shp1fl/+;MMTV-Cre and MMTV-Cre female mice displayed a severe lactation defect when compared to the Shp1 fl/+ control mice. Histological and biochemical analyses reveal that female mice expressing the MMTV-Cre transgene, either alone or in combination with floxed genes, exhibit defects in lobuloalveolar expansion, presence of large cytoplasmic lipid droplets in luminal alveolar epithelial cells postpartum, and precocious induction of involution. Using a PCR-based genotyping method, the three different founder lines can be distinguished, and we determined that the MMTV-Cre line A, the most widely used MMTV-Cre founder line, exhibits a profound lactation defect that limits its use in studies on mammary gland development.The identification of a lactation defect in the MMTV-Cre line A mice indicates that investigators must use MMTV-Cre alone mice as control in studies that utilize Cre recombinase to excise genes of interest from mammary epithelial cells. Our results also suggest that previous results obtained in studies using the MMTV-Cre line A line should be re-evaluated if the controls did not include mice expressing only Cre recombinase

Острые отравления диацетилморфином (героином) (обзор)

This review presents current data on the mechanism of action, selective toxicity, toxicokinetics and toxicodynamics of diacetylmorphine (heroin). Acute diacetylmorphine poisoning is considered under taking into account the developing a critical state, in which the poisoning severity is determined by severe metabolic disorders associated with the progression of hypoxia. The main lifethreatening complications of acute diacetyl morphine poisoning are described including those associated with the nervous system, respiratory, circulatory and urinary systems. Since hypoxia is the principal damaging factor, the the mechanisms of oxygen transport disorders and the pathogenesis of activation of free radical oxidation in acute diacetylmorphine poisoning are discussed. The improvement of intensive care strategy for severe forms of acute diacetylmorphine poisoning by the inclusion of a substrate antihypoxant Reamberin into the list of routine critical care prescriptions is emphesized.В обзоре представлены современные данные о механизме действия, избирательной токсичности, токсикокинетике и токсикодинамике диацетилморфина (героина). Острые отравления диацетилморфином рассмотрены в аспекте формирования критического состояния, при котором тяжесть отравления обусловлена развитием выраженных метаболических расстройств, связанных с прогрессированием гипоксии. Описаны основные жизнеопасные осложнения, которые возникают вследствие острых отравлений диацетилморфином со стороны ЦНС, системы дыхания, кровообращения, мочевыделительной системы. Учитывая, что основным фактором поражения является гипоксия, рассмотрены механизмы нарушений транспорта кислорода, а также патогенез активации свободнорадикального окисления при острых отравлениях диацетилморфином. Дано обоснование направлений совершенствования интенсивной терапии тяжелых форм острых отравлений диацетилморфином путем использования, помимо общереаниматологических мероприятий, субстратного антигипоксанта реамберина

Constitutive Overexpression of the OsNAS Gene Family Reveals Single-Gene Strategies for Effective Iron- and Zinc-Biofortification of Rice Endosperm

BACKGROUND: Rice is the primary source of food for billions of people in developing countries, yet the commonly consumed polished grain contains insufficient levels of the key micronutrients iron (Fe), zinc (Zn) and Vitamin A to meet daily dietary requirements. Experts estimate that a rice-based diet should contain 14.5 µg g−1 Fe in endosperm, the main constituent of polished grain, but breeding programs have failed to achieve even half of that value. Transgenic efforts to increase the Fe concentration of rice endosperm include expression of ferritin genes, nicotianamine synthase genes (NAS) or ferritin in conjunction with NAS genes, with results ranging from two-fold increases via single-gene approaches to six-fold increases via multi-gene approaches, yet no approach has reported 14.5 µg g−1 Fe in endosperm. METHODOLOGY/PRINCIPAL FINDINGS: Three populations of rice were generated to constitutively overexpress OsNAS1, OsNAS2 or OsNAS3, respectively. Nicotianamine, Fe and Zn concentrations were significantly increased in unpolished grain of all three of the overexpression populations, relative to controls, with the highest concentrations in the OsNAS2 and OsNAS3 overexpression populations. Selected lines from each population had at least 10 µg g−1 Fe in polished grain and two OsNAS2 overexpression lines had 14 and 19 µg g−1 Fe in polished grain, representing up to four-fold increases in Fe concentration. Two-fold increases of Zn concentration were also observed in the OsNAS2 population. Synchrotron X-ray fluorescence spectroscopy demonstrated that OsNAS2 overexpression leads to significant enrichment of Fe and Zn in phosphorus-free regions of rice endosperm. CONCLUSIONS: The OsNAS genes, particularly OsNAS2, show enormous potential for Fe and Zn biofortification of rice endosperm. The results demonstrate that rice cultivars overexpressing single rice OsNAS genes could provide a sustainable and genetically simple solution to Fe and Zn deficiency disorders affecting billions of people throughout the world.Alexander A. T. Johnson, Bianca Kyriacou, Damien L. Callahan, Lorraine Carruthers, James Stangoulis, Enzo Lombi and Mark Teste

Perturbative QCD Calculations of Total Cross Sections and Decay Widths in Hard Inclusive Processes

A summary of the current understanding of methods of analytical higher order perturbative computations of total cross sections and decay widths in Quantum Chromodynamics is presented. As examples, the total cross section in electron positron annihilation, the hadronic decay rates of the tau lepton and Higgs boson up to O(\alpha_s^2) and O(\alpha_s^3) are considered. The evaluation of the four-loop QED \beta - function at an intermediate step of the calculation is briefly described. The problem of renormalization group ambiguity of perturbative results is considered and some of the existing prescriptions are discussed. The problem of estimation of theoretical uncertainty in perturbative calculations is briefly discussed.Comment: 83 pages, LaTeX, Reviews of Modern Physics style, 14 figures plus figural equations (not included). Hard copy available upon request at [email protected]. To be published in Reviews of Modern Physic