NEW DATA ABOUT AGE AND GEODYNAMIC NATURE OF HAMSARA TERRANE

On the basis of isotopic-geochemical studies and analysis of geological evidences heterogeneity of Hamsara terrane has been determined. Formation of stationed metamorphosed layers underlying the Hamsara formation occurred not earlier than 630 Ma, probably in the oceanic island arc system. Acidic effusive rocks of Hamsara formation were formed in intraplate condition in the range of 462–464 Ma. Sediments of Hamsara formation couldn’t be the part of island arc system and belong to completely other period of geological region development. This is the time of completion of accretion-collision events in the northern part of Altai-Sayan fragment of CAFB adjacent to the Siberian platform.On the basis of isotopic-geochemical studies and analysis of geological evidences heterogeneity of Hamsara terrane has been determined. Formation of stationed metamorphosed layers underlying the Hamsara formation occurred not earlier than 630 Ma, probably in the oceanic island arc system. Acidic effusive rocks of Hamsara formation were formed in intraplate condition in the range of 462–464 Ma. Sediments of Hamsara formation couldn’t be the part of island arc system and belong to completely other period of geological region development. This is the time of completion of accretion-collision events in the northern part of Altai-Sayan fragment of CAFB adjacent to the Siberian platform

PALEOARCHEAN MAFIC ROCKS OF THE SOUTHWESTERN SIBERIAN CRATON: PRELIMINARY GEOCHRONOLOGY AND GEOCHEMICAL CHARACTERIZATION

The Siberian craton consists of Archean blocks, which were welded up into the same large unit by ca 1.9 Ga [Gladkochub et al., 2006; Rojas-Agramonte et al., 2011]. The history of the constituent Archean blocks is mosaic because of limited number of outcrops, insufficient sampling coverage because of their location in remote regions and deep forest and difficulties with analytical studies of ancient rocks, which commonly underwent metamorphic modifications and secondary alterations. In this short note, we report data on discovery of unusual for Archean mafic rocks of ultimate fresh appearance. These rocks were discovered within southwestern Siberian craton in a region near a boundary between Kitoy granulites of the Sharyzhalgai highgrade metamorphic complex and Onot green-schist belt (Fig. 1). Here we present preliminary data on geochronology of these rocks and provide their geochemical characterization.The Siberian craton consists of Archean blocks, which were welded up into the same large unit by ca 1.9 Ga [Gladkochub et al., 2006; Rojas-Agramonte et al., 2011]. The history of the constituent Archean blocks is mosaic because of limited number of outcrops, insufficient sampling coverage because of their location in remote regions and deep forest and difficulties with analytical studies of ancient rocks, which commonly underwent metamorphic modifications and secondary alterations. In this short note, we report data on discovery of unusual for Archean mafic rocks of ultimate fresh appearance. These rocks were discovered within southwestern Siberian craton in a region near a boundary between Kitoy granulites of the Sharyzhalgai highgrade metamorphic complex and Onot green-schist belt (Fig. 1). Here we present preliminary data on geochronology of these rocks and provide their geochemical characterization

ГЕНЕЗИС ГРАНАТ-ПИРОКСЕНОВЫХ СИЕНИТОВ (СВЯТОНОСИТОВ) МАЛОБЫСТРИНСКОГО МАССИВА (СЛЮДЯНСКИЙ КОМПЛЕКС, ЮЖНОЕ ПРИБАЙКАЛЬЕ): РЕЗУЛЬТАТЫ ГЕОХИМИЧЕСКИХ И ИЗОТОПНЫХ ИССЛЕДОВАНИЙ

This paper deals with the study of syenites and sviatonossites (andradite-bearing syenites) of the Malobystrinsky massif of the Slyudyanka complex (South Baikal region, Siberia), and a large monzonite dike similar in age and composition to the rocks of the massif considered. The studied rocks belong to a series of highly ferriferous and metaluminous A-type granitoids (ASI index <1). They are characterized by SiO2 45–65 wt. %, K2O+Na2O up to 12 wt. %, MgO <4 wt. %, TiO2 up to 2.5 wt. %, and Al2O3 up to 17 wt. %. CaO varies in a wide range, from 2.2 to 14.7 wt. %. The rocks are similar to each other in trace element composition and show patterns with troughs for Th-U, Nb-Ta and Ti. Low-amplitude negative Eu anomaly is observed in the distribution spectra of rare earth elements for the entire rock complex. The obtained Sm-Nd age of sviatonossites in the Malobystrinsky massif is 487.1±6.1 Ma (MSWD=0.99). Our results indicate that syenites and monzonites have εNd(t) –1.9…–2.8, at εSr(t) 21–30, and sviatonossites have εNd(t) –3.8…–4.1 at εSr(t) – 26. Model ages TNd(DM) for all rock types are Mesoproterozoic (1.3–1.4 Ga). Based on the chemical and Sr-Nd isotopic composition of the magmatic rocks studied, it can be assumed that they have been generated by partial melting of lower crustal rocks (amphibolites). Crystallization of andradite garnet in syenite magma can occur due to melt contamination with metamorphic host rocks of the Slyudyanka complex.Исследованы сиениты и святоноситы (андрадитсодержащие сиениты) Малобыстринского массива слюдянского комплекса (Южное Прибайкалье, Сибирь), а также крупная дайка монцонитов, по возрасту и составу сходная с породами рассматриваемого массива. Исследованные породы относятся к ряду существенно железистых и метаглиноземистых с индексом ASI ниже 1. Породы характеризуются содержанием SiO2 49–65 мас. % и суммой щелочей K2O+Na2O до 12 мас. %, MgO ниже 4 мас. %, высокими содержаниями TiO2 – до 2.5 мас. %, Al2O3 – до 17 мас. %. СаО варьируется в широком интервале значений – от 2.2 до 14.7 мас. %. По микроэлементному спектру породы близки между собой и характеризуются общими трогами Th-U, Nb-Ta и Ti. На спектрах распределения редкоземельных элементов для всего комплекса пород наблюдается очень слабая отрицательная аномалия Eu. Полученный Sm-Nd возраст святоноситов Малобыстринского массива 487.1±6.1 млн лет (СКВО=0.99). Диапазон скорректированных на возраст значений εNd(t) в сиените и монцоните составляет –1.9…–2.8, при εSr(t) 21–30, а в святоноситах εNd(t) –3.8…–4.1 при близких εSr(t) – 26. Модельный возраст для всех рассматриваемых пород TNd(DM) имеет мезопротерозойские значения 1.3–1.4 млрд лет. Основываясь на химическом и Sr-Nd-изотопном составе исследованных магматических пород, можно предположить, что их образование связано с плавлением коровых амфиболитов. Кристаллизация андрадитового граната в сиенитовой магме вызвана контаминацией расплава вмещающими метаморфическими породами слюдянского комплекса

Luminescence spectra and kinetics of disordered solid solutions

We have studied both theoretically and experimentally the luminescence spectra and kinetics of crystalline, disordered solid solutions after pulsed excitation. First, we present the model calculations of the steady-state luminescence band shape caused by recombination of excitons localized in the wells of random potential induced by disorder. Classification of optically active tail states of the main exciton band into two groups is proposed. The majority of the states responsible for the optical absorption corresponds to the group of extended states belonging to the percolation cluster, whereas only a relatively small group of “radiative” states forms the steady-state luminescence band. The continuum percolation theory is applied to distinguish the “radiative” localized states, which are isolated in space and have no ways for nonradiative transitions along the tail states. It is found that the analysis of the exciton-phonon interaction gives the information about the character of the localization of excitons. We have shown that the model used describes quite well the experimental cw spectra of CdS(1−c)Sec and ZnSe(1−c)Tec solid solutions. Further, the experimental results are presented for the temporal evolution of the luminescence band. It is shown that the changes of band shape with time come from the interplay of population dynamics of extended states and spatially isolated “radiative” states. Finally, the measurements of the decay of the spectrally integrated luminescence intensity at long delay times are presented. It is shown that the observed temporal behavior can be described in terms of relaxation of separated pairs followed by subsequent exciton formation and radiative recombination. Electron tunneling processes are supposed to be responsible for the luminescence in the long-time limit at excitation below the exciton mobility edge. At excitation by photons with higher energies the diffusion of electrons can account for the observed behavior of the luminescence

Segregation of In to dislocations in InGaN.

Dislocations are one-dimensional topological defects that occur frequently in functional thin film materials and that are known to degrade the performance of InxGa1-xN-based optoelectronic devices. Here, we show that large local deviations in alloy composition and atomic structure are expected to occur in and around dislocation cores in InxGa(1-x)N alloy thin films. We present energy-dispersive X-ray spectroscopy data supporting this result. The methods presented here are also widely applicable for predicting composition fluctuations associated with strain fields in other inorganic functional material thin films.This work was funded in part by the Cambridge Commonwealth trust, St. John’s College and the EPSRC. SKR is funded through the Cambridge-India Partnership Fund and Indian Institute of Technology Bombay via a scholarship. MAM acknowledges support from the Royal Society through a University Research Fellowship. Additional support was provided by the EPSRC through the UK National Facility for Aberration-Corrected STEM (SuperSTEM). The Titan 80- 200kV ChemiSTEMTM was funded through HM Government (UK) and is associated with the capabilities of the University of Manchester Nuclear Manufacturing (NUMAN) capabilities. SJH acknowledges funding from the Defence Treat Reduction Agency (DTRA) USA (grant number HDTRA1-12-1-0013).This is the accepted manuscript. The final version is available at http://pubs.acs.org/doi/abs/10.1021/nl5036513

CONTEMPORARY DIAGNOSIS AND SURGICAL TREATMENT OF COLONIC DIVERTICULITIS COMPLICATIONS

Сomplications of acute colonic diverticulitis occur more frequently nowadays in emergency surgical departments. Despite the high incidence of colonic diverticulitis, especially in elderly population, there are still many unsolved questions of its diagnosis and surgical treatment. The aim of our study is to review various means of laboratory and instrumental examination, and also various types of surgical treatment, used worldwide

NEW DATA ABOUT AGE AND GEODYNAMIC NATURE OF HAMSARA TERRANE

On the basis of isotopic-geochemical studies and analysis of geological evidences heterogeneity of Hamsara terrane has been determined. Formation of stationed metamorphosed layers underlying the Hamsara formation occurred not earlier than 630 Ma, probably in the oceanic island arc system. Acidic effusive rocks of Hamsara formation were formed in intraplate condition in the range of 462–464 Ma. Sediments of Hamsara formation couldn’t be the part of island arc system and belong to completely other period of geological region development. This is the time of completion of accretion-collision events in the northern part of Altai-Sayan fragment of CAFB adjacent to the Siberian platform

СОВРЕМЕННАЯ ДИАГНОСТИКА И ХИРУРГИЧЕСКОЕ ЛЕЧЕНИЕ ОСЛОЖНЕНИЙ ДИВЕРТИКУЛИТА ОБОДОЧНОЙ КИШКИ

Сomplications of acute colonic diverticulitis occur more frequently nowadays in emergency surgical departments. Despite the high incidence of colonic diverticulitis, especially in elderly population, there are still many unsolved questions of its diagnosis and surgical treatment. The aim of our study is to review various means of laboratory and instrumental examination, and also various types of surgical treatment, used worldwide.Осложнения острого дивертикулита ободочной кишки все чаще встречаются в практике хирур- гических стационаров экстренной медицинской помощи. Несмотря на высокую заболеваемость населения, преимущественно старшего поколения, дискуссии по поводу оптимальных методов диагностики и хирургического лечения продолжаются. Целью статьи является обзор различных методов лабораторно-инструментальной диагностики, применяемых в разных странах, а также различных методов хирургического лечения этого заболевания