Commercial white paint as back surface reflector for thin-film solar cells

In this work, commercially available white paint is applied as a pigmented diffuse reflector (PDR) on the rear surface of thin-film crystalline silicon (c-Si) solar cells with a silicon thickness in the 1–2 μm range. We show that white paint increases the short-circuit current density of the solar cells enormously, with a boost of 41% observed for very thin planar solar cells illuminated with the global AM1.5 solar spectrum. We also show that white paint is a better back surface reflector (BSR) than aluminium, air, a transparent conductive oxide (TCO)/aluminium stack, and even a detached aluminium mirror. While previous studies have investigated the influence of PDRs on silicon solar cells with thicknesses of over 27 μm, this work closes the gap that has existed for much thinner cells.     

Liulin-type spectrometry-dosimetry instruments

The main purpose of Liulin-type spectrometry-dosimetry instruments (LSDIs) is cosmic radiation monitoring at the workplaces. An LSDI functionally is a low mass, low power consumption or battery-operated dosemeter. LSDIs were calibrated in a wide range of radiation fields, including radiation sources, proton and heavy-ion accelerators and CERN-EC high-energy reference field. Since 2000, LSDIs have been used in the scientific programmes of four manned space flights on the American Laboratory and ESA Columbus modules and on the Russian segment of the International Space Station, one Moon spacecraft and three spacecraft around the Earth, one rocket, two balloons and many aircraft flights. In addition to relative low price, LSDIs have proved their ability to qualify the radiation field on the ground and on the above-mentioned carriers.     

Identification of the binding surface on beta-lactamase for GroEL by limited proteolysis and MALDI-mass spectrometry

Escherichia coli beta-lactamase, alone or as a complex with GroEL at 48 degreesC, was partially digested with trypsin, endoproteinase Glu-C, or thermolysin. Peptides were analyzed by matrix-assisted laser desorption and ionization mass spectrometry and aligned with the known sequence. From the protease cleavage sites which become protected upon binding and those which become newly accessible, a model of the complex is proposed in which the carboxy-terminal helix has melted, two loops form the binding interface and the large beta-sheet become partially uncovered by the slight dislocation of other structural elements. This explains how hydrophobic surface on the substrate protein can become accessible while scarcely disrupting the hydrogen bond network of the native structure. An analysis of the GroEL-bound peptides bound after digestion of the beta-lactamase showed no obvious sequence motifs, indicating that binding is provided by hydrophobic patches in the three-dimensional structure.     

Sensitivity ofLemna bioassay interacts with stock-culture period

The effect of stock-culture period on the sensitivity of theLemna bioassay to four different phenolic substances was evaluated in this study. The sensitivity of the bioassay interacted with the stock-culture period of either 11, 14, or 18 days. After a seven-day testp-hydroxybenzoic acid (HBA), vanillic acid (VA),trans-cinnamic acid (CA), and ferulic acid (FA) with a concentration of 0.05 mM significantly reduced the number of fronds and the dry weight compared with the untreated control when the stock-culture period had been exactly 14 days. The sensitivity after the shorter (11 days) or longer (18 days) stock-culture period was reduced, and the differences in the dry weight to the untreated control were not significant after a stock culture period of 18 days. The two higher concentrations (0.1 and 0.25 mM) showed stronger inhibition. A comparison of the inhibition at 0.05 mM revealed that the stock-culture period affected the relative toxicity of the four phenolic substances. Since the pH increased in the stock-culture flasks during the 18-day period from 6.25 to 7.9, we hypothesize that differences in theLemna assay can be at least partly attributed to a pH effect, possibly in combination with a relative nutrient deficiency. We recommend a standardization of the stock-culture period to 14 days to improve the sensitivity of theLemna bioassay.     

The Theory of Zero-Suppressed BDDs and the Number of Knight's Tours

Zero-suppressed binary decision diagrams (ZBDDs) have been introduced by Minato [14–17] who presents applications for cube set representations, fault simulation, timing analysis and the n-queens problem. Here the structural properties of ZBDDs are worked out and a generic synthesis algorithm is presented and analyzed. It is proved that ZBDDs can be at most by a factor n + 1 smaller or larger than ordered BDDs (OBDDs) for the same function on n variables. Using ZBDDs the best known upper bound on the number of knight's tours on an 8 × 8 chessboard is improved significantly.     

Rekonstruktion von Barockspiegeln des Historischen Grünen Gewölbes im Dresdener Schloss

Reconstruction of Baroque Mirrors of the Historical Green Vault in the Dresden Royal Palace On the 1^st September 2006 the Federal Chancellor Dr. Angela Merkel inaugurated the reconstructed Historical Green Vault, the treasury museum of the Saxon electors and kings. Since its destruction on 13^th February 1945 two generations have been working scientific‐artistically in order to set the course for its reconstruction. The idea of a baroque mirror chamber has firstly been implemented on a sequence of 8 rooms in the Green Vault. The original mirrors, which were covered with tin amalgam, had a considerably lower reflexivity modern day silver mirrors. From originally 423 m² mirror surface, only 60 m² could be reused. For the restoration and reconstruction of the original mirrors extensive analytic investigations became necessary, which the state‐owned company Sächsisches Immobilien‐ und Baumanagement (SIB) commissioned the Fraunhofer Institute for Electron Beam and Plasma Technology (FEP). On basis of these results the responsible restoration commission decided to replace partly destroyed mirror surfaces using the historical tin amalgam mirror technology. The fully destroyed jewel room would be restored with mirrors including partial gold etching. Due to hygienical and temporal reasons those mirrors were coated through a mercury‐free vacuum thin film technology ‐ the magnetron sputtering. The results show that a layer system consisting of tin‐bronze‐titanium and protective lacquers represent an adequate replacement for the original tin amalgam mirrors. The procedure allows relatively uncomplicated partial silverings and a subsequent inserting of artistic gold etchings.     

Tracking, grading, and student motivation: Using group composition and status to predict self-concept and interest in ninth-grade mathematics.

Assigning students to different classes on the basis of their achievement levels (tracking, streaming, or ability grouping) is an extensively used strategy with widely debated consequences. The authors developed a model of the effects of tracking on self-concept and interest that integrates the opposing predictions of "assimilation" and "contrast" effects, which specifies teacher-assigned grades as a major mediating variable, and tested it in 2 settings in which track level is clearly associated with different status-systematic tracking as a function of school type (Study 1, N = 14,341 German 9th-grade students) and separate streams within a comprehensive school system (Study 2, N = 3,243 German 9th-grade students). The results support predictions that students' math self-concept and math interest differ as a function of the achievement of their reference group, their own achievement, and their teacher-assigned grades. No systematic association between track level and math self-concept was found once individual student achievement, school-/stream-average achievement, and teacher-assigned grades were controlled. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential effect of dexamethasone on interleukin 1beta- and cyclic AMP-triggered expression of GTP cyclohydrolase I in rat renal mesangial cells

1. Endogenous synthesis of tetrahydrobiopterin (BH4) is an essential requirement for cytokine-stimulated nitric oxide (NO) synthesis in rat mesangial cells. GTP cyclohydrolase I, the rate-limiting enzyme in BH4 synthesis, is expressed in renal mesangial cells in response to two principal classes of activating signals. These two groups of activators comprise inflammatory cytokines such as interleukin (IL)-1beta and agents that elevate cellular levels of cyclic AMP. 2. We examined the action of the potent anti-inflammatory drug dexamethasone on GTP cyclohydrolase I induction in response to IL-1beta and a membrane-permeable cyclic AMP analogue, N6, O-2'-dibutyryladenosine 3'-5'-phosphate (Bt2cyclic AMP). 3. Nanomolar concentrations of dexamethasone markedly attenuated IL-1beta-induced GTP cyclohydrolase I mRNA steady state level as well as IL-1beta-induced GTP cyclohydrolase I protein expression and enzyme activity. In contrast, dexamethasone did not inhibit Bt2cyclic AMP-triggered increase in GTP cyclohydrolase I mRNA level and protein expression, and low (1 nM) or high (1 and 10 microM) doses of dexamethasone consistently increased Bt2cyclic AMP-induced GTP cyclohydrolase activity. 4. In summary, these results suggest that glucocorticoids act at several levels, critically dependent on the stimulus used, to control GTP cyclohydrolase I expression.