Search

Synthetic bulk and natural pyrite from the hydrothermal mine in Schönbrunn (Saxony, Germany) are confirmed to be stoichiometric compounds with the composition FeS2 and to be stable up to ~600 K by combined chemical, spectroscopic and X-ray diffraction analyses. Natural pyrite with negligibly small amount (< 0.6 wt.%) of well-defined transition metal carbonates impurities revealed characteristics of a nondegenerate semiconductor and is considered as a model system for investigation of thermoelectric performance. In the temperature range 50-600 K both natural and synthetic high quality bulk FeS2 samples show electrical resistivity varying within (220)-(5×10-3) Ω m and Seebeck coefficients of (4)-(-450) μV K-1. The thermal conductivity is large (~40 W m-1 K-1 at 300 K) and exclusively due to phononic contribution. It reveals a well pronounced maximum centered at ~75 K for natural pyrite (grain size ≤ 5 mm), which becomes almost completely suppressed in the sintered bulk samples due to increase of the point defects concentration and additional scattering on the grain boundaries (grain size ≤ 100 μm). The thermoelectric efficiency of a pure pyrite with ZT ~ 10-6 at 600 K is indeed by a factor of ~1000 worse than those reported earlier for some minerals and synthetic samples.

Fully glazed buildings have increased in popularity throughout the world's building sector. Office buildings are often especially designed with a high glazing ratio to fulfil representative architectural tasks. However, a high glazing ratio is also likely to result in a high solar load and glare problems, which cause an unsatisfactory working environment that can reduce employee productivity severely. Furthermore, it creates high cooling loads resulting in immense maintenance costs. Solutions provide light direction to illuminate the space naturally and shading to avoid glare as well as to reduce cooling loads. Many studies have been carried out on thermal comfort, others on lighting issues, but mostly under artificial lighting conditions or under the exclusion of sunny conditions. The performance of light directing elements under sunny conditions and the resulting lighting quality so far has not been investigated. Especially under sunny conditions, however, conflict between the use of daylight, ...

The Strange Lake pluton is situated on the northern border between Québec and Labrador in northeastern Canada. The ore-body, located within a complex peralkaline granite-hosted system of pegmatites and aplites, contains elevated concentrations of both LREE and the highly coveted HREE, as well as other HFSE (high field strength elements, such as Zr, Nb, Y, Ti, and Th). The REE mineralization, however, is extremely complex and the elements of interest are variably distributed between various “exotic” minerals from different mineral classes that may also contain considerable amounts of unwanted impurities such as thorium, uranium and beryllium. Naturally occurring radioactive materials (NORM) like Th may be concentrated during beneficiation, thus constituting a serious hazard to the workers and the environment. In order to limit transportation and storage of hazardous material during production, it is of the company’s interest to separate these deleterious constituents early in or at best in advance to the extraction process. This study focuses on the characterization of the mineral phases that primarily host thorium for early recognition. Combined chemical and structural analyses indicate that there is one particular mineral phase in which Th is present in highly elevated concentrations. This mineral is best described as a metamict Th-silicate occurring in isolated, rounded grains enclosed in quartz. Further studies are required to indicate if this mineral can be separated early during minerals processing from the ore without considerable loss of valuable REE.

Etude de la distribution des genotypes de l'apolipoproteine E et des frequences des alleles chez les Indiens, Hongrois et les Papous a l'aide de l'analyse basee sur l'ADN. La frequence de l'allele de l'apolipoproteine E4 est trois fois plus elevee chez les Papous que chez les Caucasiens. Le rare allele E2 est aussi plus frequent chez les Papous que dans les autres populations

Im Erzgebirge wurde über Jahrhunderte hinweg Erzbergbau betrieben. Abhängig vom Stand der Technik wurden nicht auszubringende oder nicht verwertbare Bestandteile des geförderten Gesteins aufgehaldet. Daher existieren als Hinterlassenschaft des Erzbergbaus des vorigen Jahrhunderts auch heutzutage noch etliche große Bergehalden, Spülhalden und Waschsandhalden aus der Aufbereitung sowie Schlacke- und Flugstaubablagerungen aus der Verhüttung. Diese Halden enthalten noch für die damalige Aufbereitung zu fein verwachsenes Material bzw. Restkonzentrationen der abgebauten Erzmetalle – z. B. Zinn, Zink, Silber oder Wolfram – und Begleitelemente, wie Lithium oder Indium. Einige der Metalle, die bei der historischen Gewinnung wirtschaftlich von wenig Interesse waren, sind heute von wirtschaftsstrategischer Relevanz.

Etude de la distribution des proteines de serum C3, TF, HP, GC, BF, AMY2, PLG, GM, et KM et des polymorphismes d'enzyme erythrocite GLO, GPT, ESD, ACP, 6-PGD, ADA, AK, PGM1 et PGP dans douze populations de Hongrie (Hongrois, juifs et gitans). Les frequences geniques et les distances genetiques sont discutees en relation aux localisations geographiques actuelles de ces groupes et a l'histoire probable de leur migration

An epidemiological study on alcohol drinking habits, alcohol metabolism rate, alcohol-related acute physiological symptoms, and alcohol misuse among Palocs, an ethnic minority in Hungary, was conducted. The demographic and sociocultural correlates revealed their ethnic identity: low to moderate education, relatively low number of children per family and higher percentage of skilled workers among males. Alcohol use survey revealed that frequency of alcohol consumption among Paloc male population is considerably high. While about 41% of the Paloc males reported to drink daily between 30 ml and 90 ml pure alcohol, only 5% of the females reported to consume this amount regularly. 53% of males and less than 1% of females were classified as heavy drinkers (consuming more than 60 ml absolute alcohol per day). While all kinds of alcoholic beverage was reported to be consumed by the males, Palinka (a kind of brandy) drinking was more common among females. About 45% of the Palocs reported to experience acute reactions after drinking a moderate dose of alcohol. The physical and physiological reactions include facial flushing, higher pulse rate, tachycardia and euphoria. While there was no distinct gender difference in facial flushing response to alcohol drinking, a higher percentage of males (70%) reported symptoms such as sleepiness, euphoria and aggressiveness as compared to about only 36% females reporting such reactions. Distribution of clinical chemical markers, in particular GGT values confirmed a heavier alcohol consumption among males than among females. High GGT value also correlated with a positive alcohol-related facial flushing reaction in males.

This paper reports the results of a study on alcohol drinking habits, alcohol-related acute symptoms, and alcohol abuse among Csangos, an ethnic minority in Hungary. The demographic data revealed their social characteristics: growing old, low education, endogamous marriages, early maternal age at birth of the first baby, and a high child number per family. Alcohol use survey revealed that alcohol consumption of the Csangos is considerably high; more than half of Csango males and more than one-quarter of Csango females are heavy drinkers. While all kinds of alcohol are consumed by males, wine drinking is more common among females. Acute reactions to a moderate dose of alcohol evoked a series of physical and physiological symptoms including facial flushing, higher pulse rate, tachycardia and euphoria among at least one third of the probands. There was a distinct gender difference in response to alcohol drinking. While a higher percentage of females reported intense skin flush (34%), a greater percentage of males reported symptoms such as sleepiness, euphoria and aggressiveness. The distribution of clinical chemical markers of alcohol abuse in the sera of the individuals under study confirmed heavier alcohol consumption among males than among females. Alcohol-related mortality data indicate liver cirrhosis and liver cancer as the leading cause of deaths among Csango males. A high alcohol consumption among Csango ethnic group reflects the acceptance of alcohol use in the community as an integral part of their lifestyle. Language: en

The new subterranean blasting facility at the TU Bergakademie Freiberg allows experiments at elevated capacities of 20 kg C4-equivalent. The new installation permits the investigation of phase transitions of γ Si3N4 under dynamic loading. We studied the influence of plate thickness (shock duration) and different precursor-pressure powder (Cu, NaCl) mixtures at charge masses between 2000 and 20.000 g C4. Systematic studies showed that the Mach-reflection (so called “upstreaming jetting phenomena”) is of vital importance for the synthesis success, due to the fact that the T-p ratio will increase dramatically [Milyavskii et al., 2006]. We synthesized pure γ-Si3[O,N]4 from H-bearing precursors at pressures > 25 GPa [Schlothauer et al., 2011]. The phase transition Si2N2NH into γ-Si3[O,N]4 is completely reconstructive and requires a high temperature-pressure-ratio of 176 K/GPa at pressures up to 35 GPa. Despite the high energy density during the shock wave synthesis process it will be inevitable to prepare the samples under an inert nitrogen atmosphere.

We present an experimental and theoretical study of the quasi-onedimensional S = 1/2 Heisenberg magnet linarite PbCuSO4(OH)2, with competing ferromagnetic nearest-neighbor and antiferromagnetic nextnearest- neighbor exchange interactions. It includes magnetization and NMR studies as well as theoretical simulations for the determination of the leading exchange couplings, which are about an order of magnitude higher as determined previously [1]. Furthermore, a manifold of field-induced phases are probed, from which we draw a preliminary phase diagram. Notably, spin-lattice relaxation investigations indicate that linarite might undergo a magnetic quadrupolar spin liquid phase transition as recently predicted for such materials.

Based on principles of constructivism, an analysis is made of how practice in mathematical education might be reformed towards a professional practice. In addition to the widespread recommendations that mathematical teaching be based on interactive communication and that mathematical learning be active, we argue that conventional school mathematics be replaced by a constructivist school mathematics. A constructivist school mathematics is based on children's use of their schemes of action and operation in learning situations, and whatever accommodation the children make in these schemes as they use them. Through examples of our learning of the numerical schemes of five year old children we illustrate what we mean by a constructivist school mathematics. In our examples, we characterize the schemes of action and operation that we attribute to children as our interpretations of the children's activities. For this reason, we define a constructivist school mathematics to be the results of the observer's experiential abstractions in the context of interacting with children mathematically. A professional teacher is cast as one with the intellectual autonomy and power to produce a constructivist school mathematics, including the involved situations of learning and interactive mathematical communication.

Vorrangiges Ziel des Projekts ist die Bestimmung der rheologischen Eigenschaften von heterogenen Stoffgemischen im Bereich Gemenge / Rauschmelze. Dabei soll eine Analyse der Ergebnisse auf der Basis disperser Systeme erfolgen, die den Fließwiderstand des Gesamtsystems sowohl als Funktion seines Feststoff-, Flüssigphasen- und Gasanteils darstellt als auch die chemische Veränderung der einzelnen dispersen Phasen erfasst. Aus der Kombination dieser Ergebnisse sollen Gleichungssysteme entwickelt werden., 2076

Five distinct analytical techniques were compared for the quantification of the H2O (0·1−7·4 wt%) and D2O (up to 5·5 wt% D2O) contents in rhyolitic glasses. The hydrogen concentration in obsidians was measured using nuclear reaction analysis (NRA) and converted into H2O concentration. The bulk water content (H2O+D2O) of synthesised glasses was determined using thermal extraction in conjunction with Karl–Fischer titration (KFT). Unextracted H2O was measured by infrared (IR) spectroscopy after remelting the KFT products at high pressure. These well characterised glasses were subsequently used to calibrate secondary ion mass spectrometry (SIMS), infrared and evolved gas analysis (EGA). The calibrations of SIMS for H2O and D2O show a significant matrix effect at H2O and D2O concentrations larger than ~3 mol/l with the relative sensitivity factor (RSF) decreasing with bulk water content. Molar absorption coefficients for the OH stretching vibration band at 3570 cm−1 and the OD stretching vibration band at 2650 cm−1 in the infrared absorption spectra were reinvestigated. In the range 0·1−6 wt% the H2O content of glasses could be reproduced within analytical error using a constant linear molar absorption coefficient. However, it appears that the absorption coefficients for the 3570 cm−1 band as well as for the 2650 cm−1 band both decrease systematically with concentration of dissolved H2O and D2O (ε 3570=80 (±1) − 1·36(±0·23)CH2Ot and ε 2650=61·2(±1) − 2·52(± 0·30)CD2Ot ). EGA allows quantification of the H2O content as well as the study of dehydration kinetics. It is shown that H2O is released under vacuum already at room temperature from glasses containing >7 wt% H2O.

Central to the preparation of mathematics teachers is their preparation in mathematics. Consequently, a careful examination of the nature of teachers’ mathematical experiences is warranted. There are many factors that influence the teaching of mathematics including the historical development of mathematics with its inherent formalism. This linkage will be explored along with a review of research on teachers’ beliefs and knowledge of mathematics as beliefs and knowledge relate to teacher change. We conclude that this research suggests that teachers are not always well positioned to adopt a more reform- and process-oriented teaching style that moves beyond the usual formalism in the teaching of mathematics. Grounded in this review of the literature, three principles for teaching preservice teachers mathematics will be presented. These principles are: (a) treating mathematics as a pluralistic subject, (b) providing teachers with opportunities to understand and reflect on school mathematics, and (c) enabling teachers to experience mathematics as a process. We will discuss and illustrate these principles using a specific mathematical problem solved from a variety of perspectives.

Gemeinsamer Workshop von Universitaetsrechenzentrum und Professur Rechnernetze (Fakultaet Informatik) der TU Chemnitz. Globales Thema: Produktive und sichere Netzanwendungen

Based on the constructivist principle of active learning, we focus on children’s transformation of their cognitive play activity into what we regard as independent mathematical activity. We analyze how, in the process of this transformation, children modify their cognitive play activities. For such a modification to occur, we argue that the cognitive play activity has to involve operations of intelligence which yield situations of mathematical schemes.

The purpose of the study was to investigate and document possibilities for and manifestations of collaborative work with pairs of kindergarten students while they worked on tasks designed to promote early number development. Ten students, paired to be compatible with respect to their development of counting, were taught weekly for a period of 4 months. The students were addressed as pairs and provided with only one set of counting materials. The students generated 4 strategies to organize their counting: counting parts side by side, counting all at the same time, taking turns, and counting cooperatively. Cooperative counting was defined as a counting episode in which the counting acts of both students merged into a single activity with the partners working toward a common goal. Three themes emerged from the analysis of the cooperative solutions: (a) the relation between cooperation and the specific requirements of a counting task, (b) the relation between the ability to work cooperatively and the students' development of counting, and (c) the students' need to complement a cooperative venture with a solution of their own.

Esterase D phenotypes were determined in a population sample of Northern Germany. The gene frequencies were calculated with 0.8824 for Es D1 and 0.1176 for Es D2. Studies in twins, mother/child combinations and families confirmed an autosomal co-dominant inheritance.

With the help of a simplified and quick method, cellulose acetate electrophoresis, the phenotypes of esterase D were determined in an Assamese population. The gene frequencies of Es D(1) were 0.7263 and 0.2737 for Es D(2).

During population genetic studies in Korea a new variant in the 6-phosphogluconate (6-PGD) system preliminary called 6-PGDKorea was observed.

Congres Stiboka

Congres Stiboka

The activity of total aldolase and of the isoenzymes aldolase A and aldolase B was determined in a sample of more than 100 healthy unrelated persons as well as in pairs of 20 monozygotic and 20 dizygotic twins. In monozygotic twin pairs the specific activity is almost identical, whereas significant differences were observed in dizygotic twins. Analogous results with respect to these twin studies were obtained by estimating the phenotypes of the phosphoglucomutase locus 3, arantitrypsin, alanine transaminase, the 3rd component of complement and transferrin.