Field induced evolution of regular and random 2D domain structures and shape of isolated domains in LiNbO₃ and LiTaO₃

The shapes of isolated domains produced by application of the uniform external electric field in different experimental conditions were investigated experimentally in single crystalline lithium niobate LiNbO3 and lithium tantalate LiTaO3. The study of the domain kinetics by computer simulation and experimentally by polarization reversal of the model structure using two-dimensional regular electrode pattern confirms applicability of the kinetic approach to explanation of the experimentally observed evolution of the domain shape and geometry of the domain structure. It has been shown that the fast domain walls strictly oriented along X directions appear after domain merging

Field Induced Evolution of Regular and Random 2D Domain Structures and Shape of Isolated Domains in LiNbO3 and LiTaO3

The shapes of isolated domains produced by application of the uniform external electric field in different experimental conditions were investigated experimentally in single crystalline lithium niobate LiNbO3 and lithium tantalate LiTaO3. The study of the domain kinetics by computer simulation and experimentally by polarization reversal of the model structure using two-dimensional regular electrode pattern confirms applicability of the kinetic approach to explanation of the experimentally observed evolution of the domain shape and geometry of the domain structure. It has been shown that the fast domain walls strictly oriented along X directions appear after domain merging.The research was made possible in part by Grant 03-51-6562 of INTAS; by Grant 04-02-16770 of RFBR; by Grant 03-02-39004 of RFBR-NNSF; by Grant 04-02-04007 of RFBR-DFG and by Grants 48859, 49130 and RNP 2.1.1.8272 of Program ”Development of the Scientific Potential of High Education,” by Grant MK-2434.2005.2 of President Program of Federal Agency of Education; by PhD Award Y1-P-05-20/4146 of the U.S. CRDF BRHE and Federal Agency of Education, by Grant RUE1-5037-EK-04 of CRDF FSTM

Experimental investigation of effectiveness of application of different polishing systems in the course of micro prosthetics of teeth with ceramic inlays

The aim of this investigation is studying of influence of polishing systems on surface characteristics of ceramic restoration. We have investigated 12 samples of teeth with ceramic inlays fixed on them. Materials and methods of investigation. Two prepared samples were polished using each and every of five polishing systems: Enhance, polishing burs SHOFU, Sof­Lex discs, polishing burs SHOFU using a brush with paste Profylaxpasta CCS, rubber cones (NTI), machine for precision polishing Logitech PM5 using polishing plate made of Aluminum oxide M28. Results: among the samples polished in clinical conditions the lowest roughness average of fixing cement had the samples polished using the Enhance system (Ra=150± 50hm), Sof-Lex discs (Ra=300± 30), rubber cones (NTI) (Ra=270± ЗОнм). Polishing burs SHOFU using a brush with paste Profylaxpasta CCS had showed higher roughness average (Ra=315± 35hm). Using only polishing burs SHOFU had showed the lowest polishing degree (Ra=490± 80hm), using machine for precision polishing Logitech PM5 using polishing plate made of Aluminum oxide M28 had showed the lowest roughness average (Ra=25± бнм). Conclusions: obtained data show that the sample consisting of ceramic inlay - fixing cement - tooth enamel, may be polished to the roughness average of mirror surfaces only in the laboratory conditions. In clinical conditions lowest roughness average 3 polishing systems showed Enhance system, Sof-Lex discs, rubber cones (NTI),Целью исследования явилось изучение влияния полировочных систем на поверхностные характеристики керамических реставраций. Нами были исследованы 12 образцов зубов с зафиксированными на них керамическими вкладками. Материалы и методы исследования. По два подготовленных образца отполировали с помощью одной из пяти систем: Enhance, полировочных боров SH0FU, дисков Sof-Lex, полировочных боров SH0FU с применением щетки с пастой Profylaxpasta CCS, резиновых конусов (NTI), станка для прецизионной шлифовки и полировки Logitech РМ5 с использованием шлифовальной площадки из оксида алюминия М28. Результаты. Наиболее низкий показатель шероховатости фиксирующего цемента был у образцов, отполированных с использованием систем Энхенс (Ra=150± 50нм), дисков SofLex (Ra=300± 30), и полировочных резиновых конусов NTI (Ra=270± З0нм). Полировочные боры SH0FU в том числе с последующей полировкой поверхности щеткой с пастой показали более высокое значение Ra (Ra=490± 80нм и Ra=315± 35нм, соответственно). Образцы отполированные на станке для прецизионной шлифовки и полировки Logitech РМ5 с использованием шлифовальной площадки из оксида алюминия М28 показали максимально низкое значение шероховатости (Ra=25± бнм). Выводы: из приведенных данных следует, что область: керамическая вкладка - фиксирующий цемент - эмаль зуба, возможно заполировать до значений близких к значениям гладкости зеркальных поверхностей, но в лабораторных условиях. В клинический условиях самые низкие показатели шероховатости показали три полировочные системы: Энхенс, диски SofLex и полировочные резиновые конусы NTI

Development and research of accelerating systems

A review is given of basic trends in accelerator-technique research at the Laboratory of Particle Physics (LPP), JINR: systems of transverse-oscillation damping of the LHC beam, free-electron lasers, cryo-physics, accelerators for radiation technologies, synchrotron radiation, and multicharged-ion sources. (45 refs)