Ultrafast electronic processes in an insulator The Be and O sites in BeO

The short time dynamics of amorphous beryllium oxide a BeO has been investigated for electronic excitation ionization by fast incident electrons, as well as by Ar7 , Ar15 , Xe15 , and Xe31 ions at velocities of 6 10 the speed of light. Site specific Auger electron spectra induced by fast heavy ions are the central point of this investigation. Electron induced Auger spectra serve as a reference and electron energy loss EELS spectroscopy as well as resonant inelastic X ray scattering RIXS are invoked for quantitative understanding. For the heavy ion case, we observe strong variations in the corresponding spectral distributions of Be K and O K Auger lines. These are related to local changes of the electron density, of the electron temperature and even of the electronic band structure of BeO on a femtosecond time scale after the passage of highly charged heavy ions

Discontinuous gas exchange cycles and active ventilation in pupae of the bumblebee Bombus terrestris

Discontinuous release of CO2 (bursts) or discontinuous gas exchange cycles (DGC), metabolic rate (MR) and ventilation movements were simultaneously recorded from the pupae of the bumblebee Bombus terrestris by means of an electrolytic respirometer and an infrared gas analyser (IRGA) combined with an infrared actograph (IRA). After recovering from stress, the early stage pupae showed irregular continuous respiration, mid-stage pupae displayed regular DGC. The bursts of CO2 release tended to coincide with abdominal contractions. In late stage pupae all bursts of CO2 were associated with active ventilation. During interburst periods, spikes appeared on the respirograms interpreted as micro-cycles of passive suction ventilation (PSV). After removal from their cocoons, the pupae exhibited frequent periods of muscular activity due to stress. Water loss of pupae inside cocoons was significantly less than that from pupae without cocoons

Strong and chemically inert sinter crystallised glass ceramics based on Estonian oil shale ash

In heat and power production, oil shale combustion forms substantial amounts of solid waste, including fly ash. The present paper is dedicated to the manufacturing of frit derived glass ceramics from melting high amounts of this waste (65\u201367 wt-%) combined with inexpensive minerals, such as rhyolite (33\u201335 wt-%). Owing to a surface mechanism of crystallisation, fine powders led to glass ceramics with high strength and reliability, even for rapid treatments (fast heating, at a rate of 40uC min21, followed by 30 min holding stage). To minimise the presence of pressing and demoulding induced defects, the tiles were prepared by incorporating binders, i.e. polyethylene glycol or kaolin, to the frit mixtures. Finally, the stabilising effect of recycled borosilicate glass powders, mixed with waste derived glass powders, was also investigated with promising results for the production of a chemically stable material

Intrinsic UV-VUV luminescence and X-ray emission spectroscopy of BeO and multicomponent oxide dielectrics

The experimental study of intrinsic UV-VUV luminescence and X-ray emission at the selective excitations near fundamental absorption edge as well as at the inner-shell excita-tions for binary BeO crystal and multicomponent oxide crystals Be₂SiO₄, Y₂SiO₅ and La₂Be₂O₅ has been performed. The results show that relaxation during the time-scale of decay of short-living anion and cation excitations leads to creation of self-trapped excitons at the same low-symmetry local structural units of crystalline lattice. The applied experimental method gives an opportunity to clarify a participation of different crystalline units of complex oxides in the self-trapping of excitons.Виконано експериментальне дослідження власної УФ-ВУФ люмінесценції і рентгенівської емісії для бінарного BeO і комплексних Be₂SiO₄, Y₂SiO₅ й La₂Be₂O₅ кристалів при селективному збудженні поблизу краю фундаментального поглинання і в області поглинання остовних рівнів. Результати дослідження показують, що релаксаційні процеси, що відбуваються протягом часу життя короткоживучих як аніонних, так і катіон-них збуджень приводять до утворення автолокалізованих екситонів у тих самих низьких-симетричних локальних структурних фрагментах кристалічної гратки. Використаний експериментальний метод дозволяє встановити ступінь участі різних фрагментів кристалічної гратки у процесах автолокалізації екситонів у комплексних оксидах.Выполнено экспериментальное исследование собственной УФ-ВУФ люминесценции и рентгеновской эмиссии для бинарного ВеО и комплексных Be₂SiO₄, Y₂SiO₅ и La₂Be₂O₅ кристаллов при селективном возбуждении вблизи края фундаментального поглощения и в области поглощения остовных уровней. Результаты исследования показывают, что релаксационные процессы, происходящие в течение времени жизни короткоживущих как анионных, так и катионных возбуждений приводят к образованию автолокализованных экситонов в одних и тех же низко-симметричных локальных структурных фрагментах кристаллической решетки. Использованный экспериментальный метод позволяет установить степень участия различных фрагментов кристаллической решетки в процессах автолокализации экситонов в комплексных оксидах