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

Group analysis and renormgroup symmetries

An original regular approach to constructing special type symmetries for boundary value problems, namely renormgroup symmetries, is presented. Different methods of calculating these symmetries, based on modern group analysis are described. Application of the approach to boundary value problems is demonstrated with the help of a simple mathematical model.Comment: 17 pages, RevTeX LATeX file, to appear in Journal of Mathematical Physic

Rectal cancer (lecture)

The lecture deals with the issues of classification, etiology, diagnostics and treatment of rectal cancer

Vsevolod I. Astafyev – the Man ahead of Time

The authors describe the life and activity of a famous scientist and qualified Russian surgeon, a great man with distinguished leadership ability in medicine and higher medical education, Professor Vsevolod Ivanovich Astafyev.As a student, Vsevolod I. Astafyev was keen about emergency surgery, and worked a lot in experimental laboratory. He graduated from the Kursk medical institute with honors, completing by the time his PhD thesis. However, he gave up postgraduate study and began working as a surgeon in a district hospital. After returning to the Kursk medical institute, Vsevolod I. Astafyev worked as an assistant at the hospital surgery department and successfully defended his PhD thesis. At the age of 35, he defended his doctorate thesis and competed for a post of the head of hospital surgery department at the Irkutsk medical institute. He had continued to be actively engaged in science, pedagogy and practical surgery, and organized the Siberian branch of the All-Soviet Union Scientific Center of Surgery of the USSR Academy of Medical Sciences. The branch had a clinical base with 220 beds at the Irkutsk regional hospital. Vsevolod I. Astafyev created a school of polyvalent surgeons, lecturers, and scholars.In 1987, Vsevolod Astafyev accepted an offer to become the deputy head doctor of the Republican hospital of Yakutia. Shortly after coming to Yakutsk city, he was elected a deputy of the supreme council of the Yakut Republic. On his initiative, supported by the Republic’s governance, a modern equipped medical center was built and put into operation within a short time. The so-called “sanctuary of science” still successfully works as one of the leading clinics of Russia and abroad

Calculation of thermal parameters of SiGe microbolometers

The thermal parameters of a SiGe microbolometer were calculated using numerical modeling. The calculated thermal conduction and thermal response time are in good agreement with the values found experimentally and range between 2x10$^-7$ and 7x10$^-8$ W/K and 1.5 and 4.5 ms, respectively. High sensitivity of microbolometer is achieved due to optimization of the thermal response time and thermal conduction by fitting the geometry of supporting heat-removing legs or by selection of a suitable material providing boundary thermal resistance higher than 8x10$^-3$ cm$^2$K/W at the SiGe interface.Comment: 11 pages, 6 figure

The laser-induced electron-hole liquid in the diamond: critical lattice temperature and non-equilibrium carrier density

Integrated photoluminescence spectra of two diamond samples under laser radiation excitation at 193 and 222 nm, depending on the temperature in the range of 80-300 K and the peak intensity in the range of 7-13 MW/cm2, were investigated. At temperatures below 200 K, and the peak intensity of more than 10 MW/cm2 of laser radiation at 222 nm, the radiative recombination band of electron-hole liquid was observed in integrated photoluminescence spectra of CVD diamond sample. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only