Bestimmung von Kobalt in kleinen Gewebe- und Organproben der Regenbogenforelle (Salmo gairdneri) durch flammenlose Atom-Absorptions-Spektroskopie

Zusammenfassung Gewebe und innere Organe von Regenbogenforellen wurden auf ihren Gehalt an Kobalt untersucht, um unsere Kenntnisse über das Verteilungsmuster dieses Spurenelementes bei Fischen zu erweitern. Die Kobaltbestimmungen wurden durch flammenlose Atom-Absorptions-Spektroskopie unter Anwendung der Graphitrohrküvette vorgenommen. Das organische Material wurde mit konzentrierter Salpetersäure in einem Druckbehälter aufgeschlossen (Druckaufschluß). Um Kobaltspuren anzureichern und von den Hauptmatrixbestandteilen abzutrennen, wurde ein Mikro-Solvent-Extraktionsverfahren mit Ammoniumpyrrolidindithiocarbamat als Schwermetallkomplexbildner und Toluol als Solvens entwickelt. Wie sich mit Hilfe der Radioindikatormethode (Radiotracerversuche mit Co-57) nachweisen ließ, verlief das Extraktionsverfahren mit einer Wiederfindungsrate von über 95%.Die Ergebnisse (bezogen auf Frischsubstanz) ließen erkennen, daß das untersuchte Element vorrangig in der Niere (0,195–0,449 g/g) angereichert wird. Kleinere Mengen fanden sich im Blut (0,038–0,090 g/g), in der Milz (0,015–0,078 g/g) und in der Leber (0,015–0,068 g/g). — Die einzelnen Werte für Skelett-und Muskelgewebe waren niedrig und schwankten zwischen 0,007 und 0,014 g/g bzw. 0,002 und 0,007 g/g.

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Determination of cobalt in small samples of tissues and organs of the rainbow trout (Salmo gairdneri) by flameless atomic-absorption-spectroscopy

Summary In order to increase our knowledge about the distribution pattern of the trace mineral cobalt in fish, cobalt contents of tissues and inner organs of rainbow trout were analysed. Cobalt determinations were performed by flameless atomic-absorption-spectroscopy with a heated graphite analyzer after digestion of the organic material with concentrated nitric acid in a closed system under pressure (pressure decomposition).In order to concentrate and separate the trace cobalt quantities from the main matrix constituents a micro-solvent-extraction system with ammonium pyrrolidinedithiocarbamate (APDC) as heavy metal chelating reagent and toluene as extraction solvent was developed. The extraction procedure yielded a recovery of more than 95% as determined the use of an isotope method (radiotracer experiments with Co-57).Results (calculated on wet weight basis) showed that the element under study was mainly accumulated in the kidney (0.195–0.449 g/g). Smaller amounts were found in blood (0.038–0.090 g/g), spleen (0.015–0.078 g/g), and liver (0.015–0.06 8 g/g).The values for skeletal and muscle tissue were low and ranged from 0.007 to 0.014 g/g and 0.002 to 0.007 g/g respectively.

     

Merging Top‐Down and Bottom‐Up Approaches to Fabricate Artificial Photonic Nanomaterials with a Deterministic Electric and Magnetic Response

Artificial photonic nanomaterials made from densely packed scatterers are frequently realized either by top‐down or bottom‐up techniques. While top‐down techniques offer unprecedented control over achievable geometries for the scatterers, by trend they suffer from being limited to planar and periodic structures. In contrast, materials fabricated with bottom‐up techniques do not suffer from such disadvantages but, unfortunately, they offer only little control on achievable geometries for the scatterers. To overcome these limitations, a nanofabrication strategy is introduced that merges both approaches. A large number of scatterers are fabricated with a tailored optical response by fast character projection electron‐beam lithography and are embedded into a membrane. By peeling‐off this membrane from the substrate, scrambling, and densifying it, a bulk material comprising densely packed and randomly arranged scatterers is obtained. The fabrication of an isotropic material from these scatterers with a strong electric and magnetic response is demonstrated. The approach of this study unlocks novel opportunities to fabricate nanomaterials with a complex optical response in the bulk but also on top of arbitrarily shaped surfaces.     

Discovery of Nanoscale Electric Field-Induced Phase Transitions in ZrO2

The emergence of ferroelectric and antiferroelectric properties in the semiconductor industry's most prominent high-k dielectrics, HfO₂ and ZrO₂, is leading to technology developments unanticipated a decade ago. Yet the failure to clearly distinguish ferroelectric from antiferroelectric behavior is impeding progress. Band-excitation piezoresponse force microscopy and molecular dynamics are used to elucidate the nanoscale electric field-induced phase transitions present in ZrO₂-based antiferroelectrics. Antiferroelectric ZrO₂ is clearly distinguished from a closely resembling pinched La-doped HfO₂ ferroelectric. Crystalline grains in the range of 3 – 20 nm are imaged independently undergoing reversible electric field induced phase transitions. The electrically accessible nanoscale phase transitions discovered in this study open up an unprecedented paradigm for the development of new nanoelectronic devices.     

高亮度LED调光技术

高亮度发光二极管(HB LED)在各种领域应用普及.并要求HB LED具备有调光功能.在现有的几种调光技术中,从简单的可变电阻负载到复杂的脉冲宽度调制(PWM)开关,每一种方法均有其利弊.PWM调光的效率最高,电流控制也最精准.论述了HB LED在调光时的特性,介绍了LM3405评估板及其功能.包括其布局、原理图和元件清单.     

Primary odorants of chicken broth

Summary Aroma extract dilution analysis (AEDA) of the volatiles obtained by the simultaneous distillation/extraction of a chicken broth resulted in 16 primary odour compounds with FD factor values between 64 and 2048. Fourteen of these compounds were identified as: 2-methyl-3-furanthiol, 2-furfurylthiol, methional, 2,4,5-trimethylthiazole, nonanal, 2(E)-nonenal, 2-formyl-5-methylthiophene,p-cresol, 2(E),4(E)-nonadienal, 2(E),4(E)-decadienal, 2-undecenal,-ionone, -decalactone and -dodecalactone. The primary odorants of chicken broth were compared with those resulting from the AEDA of broths from cow and ox meat. The major differences were that 2(E),4(E)-decadienal (fatty) and -dodecalactone (tallowy, fruity) prevailed in the chicken broth, whereas the sulphur compounds, bis(2-methyl-3-furyl)disulphide (meat-like-aroma) and methional (aroma like cooked potatoes), predominated in broths prepared from cow and ox meats. The odour thresholds (in air) of important meat aroma compounds are reported.

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Primäre Geruchsstoffe bei Hühnerbrühe Eine vergleichende Untersuchung mit Brühen aus Kuh- und Ochsenfleisch

Zusammenfassung Durch Aromaextraktverdünnungsanalyse (AEVA) der flüchtigen Verbindungen, isoliert durch simultane Destillation/Extraktion aus Hühnerbrühe, wurden 16 primäre Aromastoffe mit FD-Faktoren im Bereich 64 bis 2048 wahrgenommen. Von diesen Verbindungen wurden 14 identifiziert: 2-Methyl-3-furanthiol, 2-Furfurylthiol, Methional, 2,4,5-Trimethylthiazol, Nonanal, 2(E)-Nonenal, 2-Formyl-5-methylthiophen,p-Kresol, 2(E),4(E)-Nonadienal, 2(E),4(E)-Decadienal, 2-Undecenal,-Ionon, -Decalacton, -Dodecalacton. Die primären Geruchsstoffe der Hühnerbrühe wurden mit denen verglichen, die aus einer AEVA von Kuh- und Ochsenfleischbrühe stammten. Hauptunterschiede waren: 2(E),4(E)-Decadienal (fettig) und -Dodecalacton (talgig, fruchtig) überwogen in Hühnerbrühe, während die Schwefelverbindungen Bis(2-methyl-3-furyl)disulfid (fleischartig) und Methional (gekochte Kartoffeln) in den Brühen aus Rindfleisch dominierten. Die Geruchsschwellen (in Luft) wichtiger Fleischaromastoffe wurden bestimmt.

     

Laser ablation of SiO2 for locally contacted Si solar cells with ultra‐short pulses

We apply ultra‐short pulse laser ablation to create local contact openings in thermally grown passivating SiO₂ layers. This technique can be used for locally contacting oxide passivated Si solar cells. We use an industrially feasible laser with a pulse duration of τ_pulse ∼ 10 ps. The specific contact resistance that we reach with evaporated aluminium on a 100 Ω/sq and P‐diffused emitter is in the range of 0·3–1 mΩ cm². Ultra‐short pulse laser ablation is sufficiently damage free to abandon wet chemical etching after ablation. We measure an emitter saturation current density of J_0e = (6·2 ± 1·6) × 10⁻¹³ A/cm² on the laser‐treated areas after a selective emitter diffusion with R_sheet ∼ 20 Ω/sq into the ablated area; a value that is as low as that of reference samples that have the SiO₂ layer removed by HF‐etching. Thus, laser ablation of dielectrics with pulse durations of about 10 ps is well suited to fabricate high‐efficiency Si solar cells. Copyright © 2007 John Wiley & Sons, Ltd.     

Neurotransmitters and neuropeptides in the brain of the locust.

As part of continuous research on the neurobiology of the locust, the distribution and functions of neurotransmitter candidates in the nervous system have been analyzed particularly well. In the locust brain, acetylcholine, glutamate, gamma-aminobutyric acid (GABA), and the biogenic amines serotonin, dopamine, octopamine, and histamine most likely serve a transmitter function. Increasing evidence, furthermore, supports a signalling function for the gaseous molecule nitric oxide, but a role for neuroptides is so far suggested only by immunocytochemistry. Acetylcholine, glutamate, and GABA appear to be present in large numbers of interneurons. As in other insects, antennal sensory afferents might be cholinergic, while glutamate is the transmitter candidate of antennal motoneurons. GABA is regarded as the principle inhibitory transmitter of the brain, which is supported by physiological studies in the antennal lobe. The cellular distribution of biogenic amines has been analyzed particularly well, in some cases down to physiologically characterized neurons. Amines are present in small numbers of interneurons, often with large branching patterns, suggesting neuromodulatory roles. Histamine, furthermore, is the transmitter of photoreceptor neurons. In addition to these "classical transmitter substances," more than 60 neuropeptides were identified in the locust. Many antisera against locust neuropeptides label characteristic patterns of neurosecretory neurons and interneurons, suggesting that these peptides have neuroactive functions in addition to hormonal roles. Physiological studies supporting a neuroactive role, however, are still lacking. Nitric oxide, the latest addition to the list of neurotransmitter candidates, appears to be involved in early stages of sensory processing in the visual and olfactory systems.     

Characterization and simulation of a-Si:H/μc-Si:H tandem solar cells

We simulated device characteristics of a-Si:H single junction, μc-Si:H single junction and a-Si:H/μc-Si:H tandem solar cells with the numerical device simulator Advanced Semiconductor Analysis (ASA). For this purpose we measured and adjusted electrical and optical input parameters by comparing measured and simulated external quantum efficiency, current−voltage characteristic and reflectivity spectra. Consistent reproducibility of experimental data by numerical simulation was achieved for all types of cells investigated in this work. We also show good correspondence between the experimental and simulated characteristics for a-Si:H/μc-Si:H tandem solar cells with various absorber thicknesses on both Asahi U-type SnO₂:F and sputtered/etched (Jülich) ZnO:Al substrates. Based on this good correlation between experiment and theory, we provide insight into device properties that are not directly measurable like the spatially resolved absorptance and the voltage-dependent carrier collection. These data reveal that the difference between tandem solar cells grown on Asahi U-type and Jülich ZnO substrates primarily arises from their optical properties. In addition, we find out that the doped layers do not contribute to the photocurrent except for the front p-layer. We also calculated the initial efficiencies of a-Si:H/μc-Si:H tandem solar cells with different combinations of a-Si:H and μc-Si:H absorber layer thicknesses. The maximum efficiency is found at 260 nm/1500 nm for tandem solar cells on Asahi U-type substrates and at 360 nm/850 nm for tandem solar cells on Jülich ZnO substrates.     

Global land-use implications of first and second generation biofuel targets

Recently, an active debate has emerged around greenhouse gas emissions due to indirect land use change (iLUC) of expanding agricultural areas dedicated to biofuel production. In this paper we provide a detailed analysis of the iLUC effect, and further address the issues of deforestation, irrigation water use, and crop price increases due to expanding biofuel acreage. We use GLOBIOM – an economic partial equilibrium model of the global forest, agriculture, and biomass sectors with a bottom-up representation of agricultural and forestry management practices. The results indicate that second generation biofuel production fed by wood from sustainably managed existing forests would lead to a negative iLUC factor, meaning that overall emissions are 27% lower compared to the “No biofuel” scenario by 2030. The iLUC factor of first generation biofuels global expansion is generally positive, requiring some 25 years to be paid back by the GHG savings from the substitution of biofuels for conventional fuels. Second generation biofuels perform better also with respect to the other investigated criteria; on the condition that they are not sourced from dedicated plantations directly competing for agricultural land. If so, then efficient first generation systems are preferable. Since no clear technology champion for all situations exists, we would recommend targeting policy instruments directly at the positive and negative effects of biofuel production rather than at the production itself.