Low-temperature creation of Frenkel defects via hot electron-hole recombination in highly pure NaCl single crystals

The creation spectrum of stable F centres (being part of F-H pairs of Frenkel defects) by synchrotron radiation of 7–40 eV has been measured for highly pure NaCl single crystals at 12 K using a highly sensitive luminescent method. It is shown that the efficiency of F centre creation in a closely packed NaCl is low at the decay of anion or cation excitons (7.8–8.4 and 33.4 eV, respectively) or at the recombination of relaxed conduction electrons and valence holes. Only the recombination of nonrelaxed (hot) electrons with holes provides the energy exceeding threshold value EFD, which is sufficient for the creation of Frenkel defects at low temperature

Location of the Energy Levels of the Rare-Earth Ion in BaF2 and CdF2

The location of the energy levels of rare-earth (RE) elements in the energy band diagram of BaF2 and CdF2 crystals is determined. The role of RE3+ and RE2+ ions in the capture of charge carriers, luminescence, and the formation of radiation defects is evaluated. It is shown that the substantial difference in the luminescence properties of BaF2:RE and CdF2:RE is associated with the location of the excited energy levels in the band diagram of the crystals

Пятнадцатилетний опыт радикальной цистэктомии и кишечной деривации мочи

Objective. Examination of the results of surgical treatment and analysis of the surgical technique and perioperative parameters in a series of radical cystectomy on the basis of its own 15 years of experience in the formation of orthotopic and heterotopic urinary reservoir of the ileum segment by developed and patented techniques in different versions: open radical cystectomy, laparoscopic radical cystectomy and robotassisted radical cystectomy.Materials and methods. A retrospective analysis of 310 radical cystectomy performed from 2000 to 2015, on the occasion of various pathologies of the bladder and prostate, as well as cancers of other organs (uterus, colon) with involvement in the process of bladder tumor. Plastics of the bladder was performed from the segment of the terminal ileum. Formation of orthotopic bladder was performed by the method of M.I. Vasilchenko (RF patent for invention № 2337630 “Method of orthotopic bladder plastics” by M.I. Vasilchenko). The ureters are implanted by antireflux procedure. If unable to perform orthotopic bladder plastics recovery and self-urination, patients underwent the formation of heterotopic enteral reservoir with a holding valve.Results. It assesses the functionality and viability of organic shaped orthotopic and heterotopic urinary neocystis in the early and late postoperative periods in different versions. The proposed techniques have a beneficial effect on the improvement of the functional state and stabilization of the upper urinary tract. Analysis of morbidity and mortality was determined according to the classification of surgical complications on the Clavien–Dindo. This approach allowed to identify most of the complications and prevent an underestimation of the main negative results. Estimated oncologic efficacy of minimally invasive interventions laparoscopic radical cystectomy and robot-assisted radical cystectomy not inferior open radical cystectomy.Conclusions. Formation of heterotopic and orthotopic bladder enteral neocystis (tank), on the proposed contact techniques is a viable alternative to the known intestinal plastics. The introduction of laparoscopic surgery techniques including robot-assisted laparoscopic operations to reduce the number of early and late postoperative complications. Цель исследования – изучение результатов хирургического лечения и анализ техники операций и периоперационных показателей в серии радикальной цистэктомии на основе собственного 15-летнего опыта формирования ортотопического и гетеротопического мочевого резервуара из сегмента подвздошной кишки по разработанным и запатентованным методикам в различных вариантах исполнения: открытой, лапароскопической и робот-ассистированной радикальных цистэктомий.Материалы и методы. Проведен ретроспективный анализ результатов 310 радикальных цистэктомий, выполненных в период с 2000 по 2015 г., по поводу различных патологий мочевого пузыря и предстательной железы, а также при злокачественных опухолях других органов (матки, толстого кишечника) c вовлечением в опухолевый процесс мочевого пузыря. Пластику мочевого пузыря осуществляли из сегмента терминального отдела подвздошной кишки. Формирование ортотопического мочевого пузыря выполняли по методике М.И. Васильченко (патент Российской Федерации на изобретение №2337630 «Способ ортотопической тонкокишечной пластики мочевого пузыря», автор М.И. Васильченко). Мочеточники имплантировались по антирефлюксной методике. При невозможности осуществления ортотопической пластики мочевого пузыря и восстановления самостоятельного мочеиспускания больным выполнялось формирование гетеротопического тонкокишечного резервуара с удерживающим клапаном.Результаты. Оценена функциональная и органическая состоятельность сформированного ортотопического и гетеротопического мочевого неоцистиса в ранние и отдаленные сроки после операции в различных вариантах исполнения. Предложенные методики оказывают благоприятное влияние на улучшение функционального состояния и стабилизацию верхних мочевыводящих путей. Анализ частоты развития осложнений и летальности определяли согласно классификации хирургических осложнений Clavien– Dindo. Данный подход позволил выделить большинство осложнений и предотвратить недооценку главных отрицательных результатов. Была проанализирована онкологическая эффективность малоинвазивных вмешательств – лапароскопической и роботассистированной радикальных цистэктомий, не уступающих открытой радикальной цистэктомии.Выводы. Формирование гетеротопического и ортотопического тонкокишечного мочевого неоцистиса (резервуара) по предложенным нами методикам является достойной альтернативой известным кишечным пластикам. Внедрение лапароскопических техник оперативного лечения, в том числе робот-ассистированных операций, позволяет снизить количество ранних и поздних послеоперационных осложнений.

Feshbach resonances and mesoscopic phase separation near a quantum critical point in multiband FeAs-based superconductors

High Tc superconductivity in FeAs-based multilayers (pnictides), evading temperature decoherence effects in a quantum condensate, is assigned to a Feshbach resonance (called also shape resonance) in the exchange-like interband pairing. The resonance is switched on by tuning the chemical potential at an electronic topological transition (ETT) near a band edge, where the Fermi surface topology of one of the subbands changes from 1D to 2D topology. We show that the tuning is realized by changing i) the misfit strain between the superconducting planes and the spacers ii) the charge density and iii) the disorder. The system is at the verge of a catastrophe i.e. near a structural and magnetic phase transition associated with the stripes (analogous to the 1/8 stripe phase in cuprates) order to disorder phase transition. Fine tuning of both the chemical potential and the disorder pushes the critical temperature Ts of this phase transition to zero giving a quantum critical point. Here the quantum lattice and magnetic fluctuations promote the Feshbach resonance of the exchange-like anisotropic pairing. This superconducting phase that resists to the attacks of temperature is shown to be controlled by the interplay of the hopping energy between stripes and the quantum fluctuations. The superconducting gaps in the multiple Fermi surface spots reported by the recent ARPES experiment of D. V. Evtushinsky et al. arXiv:0809.4455 are shown to support the Feshbach scenario.Comment: 31 pages, 7 figure

Radiation creation of cation defects in alkali halide crystals: Review and today’s concept

Irradiation of alkali halide crystals creates pairs of Frenkel defects both in anion and cation sublattices. How-ever, the particular nonimpact creation mechanisms (related to the decay of different electronic excitations) of cation Frenkel pairs are still unclear. At helium temperatures, there is yet no direct evidences of the creation of stable (long-lived) elemental cation defects. On the other hand, a number of complex structural defects containing cation vacancies and/or interstitials, were detected after irradiation of alkali halides at higher temperatures. Besides already proved mechanism related to the association of H and VK centers into trihalide molecules, the following possibilities of cation interstitial-vacancy pair creation are analyzed as well: (i) a direct decay of cation or anion excitons, (ii) the transformation of anion Frenkel pairs, formed at the decay of anion excitons or e-h recombination, into cation ones

Performance analysis of content management systems

Проанализированы существующие системы управления сайтом, а также средства для нагрузочного и стрессового тестирования производительности. Выполнено исследование производительности систем CMS, написанных на языке PHP: Drupal, PHP-Nuke и Joomla.Проаналізовані існуючі системи управління сайтом, а також засоби для навантаження і стресового тестування продуктивності. Виконано дослідження продуктивності систем CMS, написаних на мові PHP: Drupal, PHP-Nuke и Joomla.Existing content management systems are analyzed, and also facilities for loading and stressful testing performance. Research is executed performance systems CMS, written in language PHP: Drupal, PHP-Nuke and Joomla

Influence of complex impurity centres on radiation damage in wide-gap metal oxides

Different mechanisms of radiation damage of wide-gap metal oxides as well as a dual influence of impurity ions on the efficiency of radiation damage have been considered on the example of binary ionic MgO and complex ionic–covalent $Lu_{3}Al_{5}O_{12}$ single crystals. Particular emphasis has been placed on irradiation with $\sim$2 GeV heavy ions ($^{197}Au, ^{209}Bi, ^{238}U$, fluence of 10$^{12}$ ions/cm$^{2}$) providing extremely high density of electronic excitations within ion tracks. Besides knock-out mechanism for Frenkel pair formation, the additional mechanism through the collapse of mobile discrete breathers at certain lattice places (e.g., complex impurity centres) leads to the creation of complex defects that involve a large number of host atoms. The experimental manifestations of the radiation creation of intrinsic and impurity antisite defects (Lu|$_{Al}$ or Ce|$_{Al}$ – a heavy ion in a wrong cation site) have been detected in LuAG and $LuAG:Ce^{3+}$ single crystals. Light doping of LuAG causes a small enhancement of radiation resistance, while pair impurity centres (for instance, $Ce|_{Lu}–Ce|_{Al}$ or $Cr^{3+}–Cr^{3+}$ in MgO) are formed with a rise of impurity concentration. These complex impurity centres as well as radiation-induced intrinsic antisite defects (Lu|$_{Al}$ strongly interacting with Lu in a regular site) tentatively serve as the places for breathers collapse, thus decreasing the material resistance against dense irradiation