Performance of superstrate multijunction amorphous silicon-based solar cells using optical layers for current management

The performance of multijunction amorphous silicon-based thin film solar cells has been reported using thin layers of TiO₂ and SiO_x acting as refractive index matching optical layers for different interfaces of the superstrate device structure. Improvement of short-circuit current from the sub-cells of a-Si/μc-Si cells is demonstrated with TiO₂ as anti-reflection layer at TCO/Si interface and SiO_x as intermediate-reflector layer between two sub-cells. An initial efficiency of 11.8% is achieved by applying both the TiO₂ and SiO_x optical layers in a-Si/μc-Si solar cell.     

Determination of antioxidative capacities using an enhanced total oxidant scavenging capacity (TOSC) assay

The antioxidant capacities of nine standard compounds (ascorbic acid, benzoic acid, (+)-catechin, cyanidin-3-glucoside, cyanidin-3-rutinoside, (-)-epicatechin, protocatechuic acid, Trolox and uric acid) towards the three reactive oxygen species (ROS) peroxyl radicals, hydroxyl radicals and peroxynitrite were tested with the total oxidant scavenging capacity (TOSC) assay. The time course of ethylene formation from the reaction of the ROS with !-keto-%-methiolbutyric acid (KMBA) was monitored by automated headspace GC. By this automation and by optimisation of the preparation and storage of the assay solutions, the time- and labour-consumption of the method could be minimised. Based on the experimental data, the relation between concentration and inhibition rate was pointed out by calculating concentrations that corresponded to TOSC values of 20%, 50% and 80%, respectively. Furthermore, the compounds were classified by their reaction mode as fast-acting antioxidants, retardants or pro-oxidants.     

Unit cell structure of crystal polytypes in InAs and InSb nanowires

The atomic distances in hexagonal polytypes of III-V compound semiconductors differ from the values expected from simply a change of the stacking sequence of (111) lattice planes. While these changes were difficult to quantify so far, we accurately determine the lattice parameters of zinc blende, wurtzite, and 4H polytypes for InAs and InSb nanowires, using X-ray diffraction and transmission electron microscopy. The results are compared to density functional theory calculations. Experiment and theory show that the occurrence of hexagonal bilayers tends to stretch the distances of atomic layers parallel to the c axis and to reduce the in-plane distances compared to those in zinc blende. The change of the lattice parameters scales linearly with the hexagonality of the polytype, defined as the fraction of bilayers with hexagonal character within one unit cell.     

Automatisierte, photometrische Methode zur Bestimmung des Gehaltes an Niacin und Niacinamid in Getreide und Getreideerzeugnissen

Zusammenfassung Eine automatisierte Methode zur Bestimmung des Gesamtniacingehaltes von Getreide und Getreidenährmitteln wird mitgeteilt. Die meist als Kupplungsreagens verwendete Sulfanilsäure wird durch 1,1-Dimethylbarbitursäure ersetzt; CNCl wird direkt im Durchflußsystem aus KCN und Chloramin T gebildet. Die Reagentienzusammensetzung, die Arbeitsvorschrift und das Schlauchsystem werden angegeben; die Analysenfrequenz beträgt 30 Analysen pro Std. Die Reproduzierbarkeit des automatisierten Bestimmungsverfahrens ist gut. Bei einem Bestimmungsbereich von 0,5–4,0 g/mll Niacin bzw. einem Gesamtniacingehalt von 10–135 mg/kg TS wurde ein durchschnittlicher Variationskoeffizient von _k = 0,74% (n=10) ermittelt; unter Einschluß der Inhomogenität des Untersuchungsmaterials und der Streuung bei der alkalischen Hydrolyse erhöhte sich der Wert auf _k = 2,43 % im gleichen Bestimmungsbereich. Der Gesamtniacingehalt der verschiedensten Getreidearten und verschiedener verzehrfertiger Getreidenährmittel wurde bestimmt.

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Automated photometric method for the determination of niacin and niacinamid in grain and cereal food

Summary The subject of this report is an automated photometric method for the determination of the content of total niacin in grain and cereal food. The customary coupling reagent sulfanilic acid has been replaced by 1,3-dimethylbarbituric acid; CNCl is produced in the flow through system directly from KCN and chloramine T. The composition of reagents, the procedure and the analytical manifold are specified. 30 analyses/h can be performed. The accuray and reproducibility of the automated method is good. In a range of 0.5–4.0 g/ml niacin and a total content of 10–135 mg niacin/kg dry matter an average variation coefficient of _k = 0.74% (n =10) was obtained. When lack of homogenity of samples and variation in alkaline hydrolysis are included average _k to ±2.43% at the same range of niacin. The content of total niacin in various kinds of grain and in enriched ready to eat cereal foods was determined.

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Inhaltlich verkürztes Referat, vorgetragen vor der Fachgruppe VIII Pflanzenqualität des VDLUFA anläßlich des Jahreskongresses 1983 in Kiel     

Various cytosine/adenine permease homologues are involved in the toxicity of 5-fluorocytosine in Saccharomyces cerevisiae

5-Fluorocytosine (5-FC), a medically applied antifungal agent (Ancotil), is also active against the model organism Saccharomyces cerevisiae. 5-FC uptake in S. cerevisiae was considered to be mediated by the FCY2-encoded cytosine/adenine permease. By applying a highly sensitive assay, a low-level but dose-dependent toxicity of 5-FC in fcy2 mutants was detected, whereas cells deficient in the cytosine deaminase (encoded by FCY1), which is essential for intracellular conversion of 5-FC to 5-fluorouracil, display strong dose-independent resistance. Thus, an alternative, Fcy2-independent access pathway for 5-FC exists in S. cerevisiae. A genome-wide search for cytosine permease homologues identified two uncharacterized candidate genes, designated FCY21 and FCY22, both of which exhibit highest similarity to FCY2. Disruption of either FCY21 or FCY22 resulted in strains displaying low-level resistance, indicating the functional involvement of both gene products in 5-FC toxicity. When mutations in FCY21 or FCY22 were combined with the FCY2 disruption, both double mutants displayed stronger resistance when compared to the FCY2 mutant alone. Disruptions in all three permease genes consequently conferred the highest degree of resistance, not only towards 5-FC but also to the toxic adenine analogon 8-azaadenine. As residual 5-FC sensitivity was, however, even detectable in the fcy2 fcy21 fcy22 mutant, we analysed the relevance of other FCY2 homologues, i.e. TPN1, FUR4, DAL4, FUI1 and yOR071c, for 5-FC toxicity. Among these, Tpn1, Fur4 and the one encoded by yOR071c were found to contribute significantly to 5-FC toxicity, thus revealing alternative entry routes for 5-FC via other cytosine/adenine permease homologues.     

Sterol Carrier Protein-2/Sterol Carrier Protein-x/Fatty Acid Binding Protein-1 Ablation Impacts Response of Brain Endocannabinoid to High-Fat Diet

Brain endocannabinoids (EC) such as arachidonoylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG) primarily originate from serum arachidonic acid (ARA), whose level is regulated in part by a cytosolic ARA-binding protein, that is, liver fatty acid binding protein-1 (FABP1), not expressed in the brain. Ablation of the Fabp1 gene (LKO) increases brain AEA and 2-AG by decreasing hepatic uptake of ARA to increase serum ARA, thereby increasing ARA availability for uptake by the brain. The brain also expresses sterol carrier protein-2 (SCP-2), which is also a cytosolic ARA-binding protein. To further resolve the role of SCP-2 independent of FABP1, mice ablated in the Scp-2/Scp-x gene (DKO) were crossed with mice ablated in the Fabp1 gene (LKO) mice to generate triple knock out (TKO) mice. TKO impaired the ability of LKO to increase brain AEA and 2-AG. While a high-fat diet (HFD) alone increased brain AEA, TKO impaired this effect. Overall, these TKO-induced blocks were not attributable to altered expression of brain proteins in ARA uptake, AEA/2-AG synthesis, or AEA/2-AG degrading enzymes. Instead, TKO reduced serum levels of free ARA and/or total ARA and thereby decreased ARA availability for uptake to the brain and downstream synthesis of AEA and 2-AG therein. In summary, Scp-2/Scp-x gene ablation in Fabp1 null (LKO) mice antagonized the impact of LKO and HFD on brain ARA and, subsequently, EC levels. Thus, both FABP1 and SCP-2 participate in regulating the EC system in the brain.     

CEPROL: A cellular programming language

Realized cellular automata may be operated by universal computer systems as programmable special-purpose processors for parallelizable problems. Because of their architecture (local neighbourhood, small storage size per cell, they are well suited for processing systolic algorithms. A cellular programming language — named CEPROL — is presented which offers means for programming and controlling cellular automata processing such algorithms.     

Electron-Nuclear Multiple Resonance on Stable and Transient Radicals

The physical principles underlying steady-state electron-nuclear double resonance (ENDOR) and electron-nuclear-nuclear triple resonance (TRIPLE) experiments on radicals in solution are discussed. The gain in spectral resolution achievable by these techniques, as compared with standard ESR, allows hyperfine coupling constants to be measured even for large and low-symmetry radicals. ENDOR/TRIPLE is applied to cation radicals related to bacterial photosynthesis. The measured hyperfine couplings are interpreted by means of the all-valence electron MO method RHF-INDO/SP. Information about the spatial structure of chromophores in the reaction centers of photosynthetic bacteria, Rb. sphaeroides and Rps. viridis, is obtained from an analysis of the spin density distribution and from minimization of the total energy. The results are compared with recently available structural data of the primary donor obtained from X-ray diffraction experiments. The spin density distribution in the primary donor cation radical P⁺₉₆₀, which consists of two bacteriochlorophyll b molecules, is discussed in terms of symmetry and perturbations from the protein environment.     

Untersuchungen zur Beleimung von Spangemischen

Zusammenfassung Das technisch und wirtschaftlich für die Spanplatten-industrie lebenswichtige Problem der Beleimung von Spangemischen wurde in seiner Bedeutung allgemein umrissen. Die angestellten Untersuchungen machen die Beziehungen klar, die zwischen Viskosit?t und Benetzungsf?higkeit des Bindemittels, Verteilung auf der Spanoberfl?che, Bindemittelart und Bindemittelgehalt und der Güte der ausgebrachten. Spanplatte bestehen. Ferner zeigte es sich, da? die Einflu?flaktoren, auf die Güte der Spanplatte von au?erordenflich komplexer Natur und nur schwierig nebeneinander zu beherrschen sind. Die Entwicklung auf dem Gebeit der Beleimung von Spangemischen bleibt daher weiter im Flu?. Der vorliegende Beitrag ist ein Auszug aus den im Jahre 1953 am Lehrstuhl für Holztechnologie und Holztechnik an der Universit?t Hamburg angefertigten Diplomarbeiten des zweiten und dritten Verfassers.