Spark Plasma Sintering of Boron Carbide Powder

The results presented in this article demonstrate that boron carbide ceramics of a perfect microstructure, of a high density (up to 99.8%) and microhardness (36.1 GPa) can be made from the industrial micron fraction powder thanks to spark plasma sintering, that opens prospects for wide SPS application in economical production of high-quality boron carbide ceramic products. Optimal ceramics production mode is based on B4C (technical powder), which makes the best combination of physical and mechanical properties and uniformmicrostructure. The experimentally set mode of spark-plasma sintering of highdensity B4C ceramics allows to lower the sintering temperature by 300 ∘C and to shorten the process time by 20 minutes relative to the corresponding values when traditional hot pressing. Keywords: spark - plasma sintering, boron carbide, densit

Hospital surgical clinic

The article reviews main stages of establishment and development of the Department of Hospital Surgery in different periods. We showed the role of heads and stuff of the department in the development of multipartial complex which aims at the unity of three components - to teach, to treat and to study. The first head of the department and of the clinic of hospital surgery (1921-1931) was N.A. Sinakevich. It was a period of establishment of the department, its staffing, formation of clinical site and training calendar. V.G. Shipachyov was the head of the department from 1931 to 1952. During the Great Patriotic War, the work of the department was aimed at the needs of war time related to the problems of reconstruction surgery and treatment of traumatic injuries. After the war, the work of the department was dedicated to the problems of hypothyroidism, obliterating endarteritis, gastrointestinal and urgent surgery. In 1953, Z.T. Senchillo-Yaverbaum became the head of the department. The work of the department was dedicated to gastrointestinal and pancreatic surgery, herniology, thyrophymas. Also the department included course of traumatology. In 1972, V.I. Astafiev became the head of the department. In this period, many young hopefuls started to work on the department. Also the research, treatment and educational complex was created on the base of the department, Regional Clinical Hospital and Siberian Branch of Academy of Medical Sciences USSR. While keeping the traditions of the department, V.I. Astafiev created new research and practice directions and special referral units - of cardiac, vascular, thoracic, purulent and urgent surgery, operative coloproctology, plastic surgery, diagnostic picture and X-ray surgery. Also the system of individual and collective training of surgical clerk. In 1988-1993 Y.I. Morozov was the head of the department. The new direction of the work was the development of complex treatment of purulent soft tissue involvement in patients with diabetes. From 1993, E.G. Grigoryev is the head of the department of hospital surgery and the Institute of Surgery

CHRONIC SUPPURANT PULMONARY DISEASES (LECTURE)

Lecture reviews etiology, pathogenesis, epidemiology, classification, diagnostics and treatment of chronic suppurant pulmonary diseases. Clinical examples that prove optimal tactics of diagnostics and treatment of chronic suppurant pulmonary diseases are presented

A Mouse Amidase Specific for N-terminal Asparagine: the gene, the enzyme, and their function in the N-end rule pathway

The N-end rule relates the in vivo half-life of a protein to the identity of its N-terminal residue. In both fungi and mammals, the tertiary destabilizing N-terminal residues asparagine and glutamine function through their conversion, by enzymatic deamidation, into the secondary destabilizing residues aspartate and glutamate, whose destabilizing activity requires their enzymatic conjugation to arginine, one of the primary destabilizing residues. We report the isolation and analysis of a mouse cDNA and the corresponding gene (termed Ntan1) that encode a 310-residue amidohydrolase (termed NtN-amidase) specific for N-terminal asparagine. The ~17-kilobase pair Ntan1 gene is located in the proximal region of mouse chromosome 16 and contains 10 exons ranging from 54 to 177 base pairs in length. The ~1.4-kilobase pair Ntan1 mRNA is expressed in all of the tested mouse tissues and cell lines and is down-regulated upon the conversion of myoblasts into myotubes. The Ntan1 promoter is located ~500 base pairs upstream of the Ntan1 start codon. The deduced amino acid sequence of mouse NtN-amidase is 88% identical to the sequence of its porcine counterpart, but bears no significant similarity to the sequence of the NTA1-encoded N-terminal amidohydrolase of the yeast Saccharomyces cerevisiae, which can deamidate either N-terminal asparagine or glutamine. The expression of mouse NtN-amidase in S. cerevisiae nta1Delta was used to verify that NtN-amidase retains its asparagine selectivity in vivo and can implement the asparagine-specific subset of the N-end rule. Further dissection of mouse Ntan1, including its null phenotype analysis, should illuminate the functions of the N-end rule, most of which are still unknown

Enzymatic Synthesis of Nucleoside Triphosphates. Does It Involve An Ion-Radical Path ?

Accumulation and release of energy in the nucleoside triphosphate enzymatic synthesis and hydrolysis does not limited to a routine energy consuming nucleophilic mechanism. These processes require an overcoming the large energy barrier exceeding a total value of accumulated or released energy level by at least 3 – 4 times (~10 kcal/mol). This energy is supposed to be taken from the mechanical compression of the catalytic site and used to form P–O chemical bond by a direct nucleophilic addition of phosphate to nucleoside diphosphate (ADP as an example). A new, energetically “cheapâ€, ion-radical mechanism of the ATP biosynthesis has been proposed due to the observation of magnetic isotope and magnetic field effects on the ATP synthesis. This mechanism is about to generate  a compression energy to “spend†on a partial dehydratation of magnesium ion inside the nucleotidyl transferase catalyric site (energy cost of this process is 3-5 kcal/mol, i.e. by 2-3 times less than a total accumulated or released energy). Dehydration of this ion is to increase its electron affinity and hence to stimulate an electron transfer from ADP3- to Mg2+. This reaction is a starting point of the ion-radical mechanism considering the molecular mechanics of enzymatic machines and its quantum chemistry background as well. To the contrast of a hardly controllable nucleophilic path, the ion-radical mechanism might be turned on/off  by a targeted delivery of  paramagnetic magnesium ions, 25Mg2+, towards the phosphate transferring enzyme catalytic site. The magnesium isotope substitution is easily reachable by the endo-osmotic pressure techniques, which makes it attractive for further biotechnological and/or pharmacological application(s)