Recombinant expression and functional characterisation of regiospecific flavonoid glucosyltransferases from Hieracium pilosella L.

Five glucosyltransferases were cloned by RT-PCR amplification using total RNA from Hieracium pilosella L. (Asteraceae) inflorescences as template. Expression was accomplished in Escherichia coli, and three of the HIS-tagged enzymes, UGT90A7, UGT95A1, and UGT72B11 were partially purified and functionally characterised as UDP-glucose:flavonoid O-glucosyltransferases. Both UGT90A7 and UGT95A1 preferred luteolin as substrate, but possessed different regiospecificity profiles. UGT95A1 established a new subgroup within the UGT family showing high regiospecificity towards the C-3' hydroxyl group of luteolin, while UGT90A7 primarily yielded the 4'-O-glucoside, but concomitantly catalysed also the formation of the 7-O-glucoside, which could account for this flavones glucoside in H. pilosella flower heads. Semi quantitative expression profiles revealed that UGT95A1 was expressed at all stages of inflorescence development as well as in leaf and stem tissue, whereas UGT90A7 transcript abundance was nearly limited to flower tissue and started to develop with the pigmentation of closed buds. Other than these enzymes, UGT72B11 showed rather broad substrate acceptance, with highest activity towards flavones and flavonols which have not been reported from H. pilosella. As umbelliferone was also readily accepted, this enzyme could be involved in the glucosylation of coumarins and other metabolite

Spin-orbit coupled j=1/2 iridium moments on the geometrically frustrated fcc lattice

Motivated by experiments on the double perovskites La2ZnIrO6 and La2MgIrO6, we study the magnetism of spin-orbit coupled j=1/2 iridium moments on the three-dimensional, geometrically frustrated, face-centered cubic lattice. The symmetry-allowed nearest-neighbor interaction includes Heisenberg, Kitaev, and symmetric off-diagonal exchange. A Luttinger-Tisza analysis shows a rich variety of orders, including collinear A-type antiferromagnetism, stripe order with moments along the [111]-direction, and incommensurate non-coplanar spirals, and we use Monte Carlo simulations to determine their magnetic ordering temperatures. We argue that existing thermodynamic data on these iridates underscores the presence of a dominant Kitaev exchange, and also suggest a resolution to the puzzle of why La2ZnIrO6 exhibits `weak' ferromagnetism, but La2MgIrO6 does not.Comment: 5 pages, 5 figs, significantly revised to address referee comments, to appear in PRB Rapid Com

Effect of speaker age on speech recognition and perceived listening effort in older adults with hearing loss

Published online January 2012Purpose: Older adults exhibit difficulty understanding speech that has been experimentally degraded. Age-related changes to the speech mechanism lead to natural degradations in signal quality. We tested the hypothesis that older adults with hearing loss would exhibit declines in speech recognition when listening to the speech of older adults, compared with the speech of younger adults, and would report greater amounts of listening effort in this task. Methods: Nineteen individuals with age-related hearing loss completed speech recognition and listening effort scaling tasks. Both were conducted in quiet, when listening to high and low predictability phrases produced by younger and older speakers respectively. Results: No significant difference in speech recognition existed when stimuli were derived from younger or older speakers. However, perceived effort was significantly higher when listening to speech from older adults, as compared to younger adults. Conclusions: For older individuals with hearing loss, natural degradations in signal quality may require greater listening effort. However, they do not interfere with speech recognition – at least in quiet. Follow-up investigation of the effect of speaker age on speech recognition and listening effort under more challenging noise conditions appears warranted

Ultraschneller Infrarot-Konverter auf der Basis eines planaren Halbleiter-Gasentladungssystems

Es wird ein Infrarot-(IR-)Konverter auf der Basis eines planaren Halbleiter-Gasentladungssystems vorgestellt, der ultraschnell infrarote Strahlungsfelder in sichtbares Licht umsetzt. Thematisch lässt sich die Arbeit in zwei Schwerpunkte aufteilen. Der erste liegt auf der Charakterisierung und Optimierung dieses IR-Konverters, der zweite widmet sich der Erprobung des IR-Konverters in einem sehr breiten Anwendungsspektrum. Dabei umspannen die Untersuchungen zur Charakterisierung die Themenbereiche der Konversionseffizienz, der spektralen Empfindlichkeit, des zeitlichen Auflösungsvermögens und der räumlichen Auflösung. Die Applikationsbeispiele im zweiten Teil lassen sich in die Themenbereiche der Laserstrahlprofilanalyse und der Thermographie einordnen. Bei ultraschnellen Anwendungsfeldern zeigt sich, dass mit dem IR-Konverter Prozesse raumzeitlich aufgelöst werden können, die gegenwärtig mit anderen IR-Kamerasystemen gar nicht oder nur sehr eingeschränkt zugänglich sind

Разработка технологии изготовления центратора

Целью выпускной квалификационной работы является: разработка технологического процесса изготовления центратора. В результате работы был произведен технологический анализ детали, составлен маршрут обработки. Разработан технологический процесс изготовления детали - центратор, произведён размерный анализ технологического процесса. Рассчитаны режимы и силы резания обработки. Подобрано оборудование, необходимое для изготовления центратора, и инструмент, которым будет производится обработка. Также спроектирована технологическая оснастка, необходимая для базирования детали на станках.As a result of the work was made а technological analysis of the detail. A route for machining parts has been developed. The technological process of manufacturing the centralizer part has been developed. Calculated cutting parameters and cutting forces in the process of machining parts. The equipment necessary for manufacturing the centralizer and the tool that will be used for processing have been selected. The technological equipment necessary for basing the part on machines is also designed. An operating map of the technological process has been compiled

Charge Localization and Ordering in A2_2Mn8_8O16_{16} Hollandite Group Oxides: Impact of Density Functional Theory Approaches

The phases of A$_2$Mn$_8$O$_{16}$ hollandite group oxides emerge from the competition between ionic interactions, Jahn-Teller effects, charge ordering, and magnetic interactions. Their balanced treatment with feasible computational approaches can be challenging for commonly used approximations in Density Functional Theory. Three examples (A = Ag, Li and K) are studied with a sequence of different approximate exchange-correlation functionals. Starting from a generalized gradient approximation (GGA), an extension to include van der Waals interactions and a recently proposed meta-GGA are considered. Then local Coulomb interactions for the Mn $3d$ electrons are more explicitly considered with the DFT+$U$ approach. Finally selected results from a hybrid functional approach provide a reference. Results for the binding energy of the A species in the parent oxide highlight the role of van der Waals interactions. Relatively accurate results for insertion energies can be achieved with a low $U$ and a high $U$ approach. In the low $U$ case, the materials are described as band metals with a high symmetry, tetragonal crystal structure. In the high $U$ case, the electrons donated by A result in formation of local Mn$^{3+}$ centers and corresponding Jahn-Teller distortions characterized by a local order parameter. The resulting degree of monoclinic distortion depends on charge ordering and magnetic interactions in the phase formed. The reference hybrid functional results show charge localization and ordering. Comparison to low temperature experiments of related compounds suggests that charge localization is the physically correct result for the hollandite group oxides studied here. . . .Comment: 16 pages, 8 figure