Search results for "Stain"
showing 10 items of 5524 documents
Negative Staining and Cryo-negative Staining: Applications in Biology and Medicine
2013
Negative staining is widely applicable to isolated viruses, protein molecules, macromolecular assemblies and fibrils, subcellular membrane fractions, liposomes and artificial membranes, synthetic DNA arrays, and also to polymer solutions and a variety of nanotechnology samples. Techniques are provided for the preparation of the necessary support films (continuous carbon and holey/perforated carbon). The range of suitable negative stains is presented, with some emphasis on the benefit of using ammonium molybdate and of negative stain-trehalose combinations. Protocols are provided for the single droplet negative staining technique (on continuous and holey carbon support films), the floating a…
A qualitative examination of performance and energy yield of photovoltaic modules in southern Norway
2010
Three different, commercially available photovoltaic modules have been monitored outdoors in the town of Grimstad, Norway. The present paper describes the experimental setup that was implemented, in particular details of the low-cost electronic loads. Results compare measured performance with manufacturer's data, and temperature measurements enable a comparison with performance at standard test condition temperature. Overall, the monocrystalline module performed best both regarding maximum efficiency and overall energy production, whereas the module based on triple junction amorphous silicon technology had the worst performance considering these criteria. The gross numbers of energy yield c…
A procedure to evaluate the seven parameters of the two-diode model for photovoltaic modules
2019
Abstract The paper presents an analytical procedure to calculate the seven parameters of the two-diode model of photovoltaic (PV) panels for any value of the solar irradiance and cell temperature. Six parameters (the photocurrent, the diode reverse saturation currents, the quality factor of the first diode and the series and shunt resistances), are evaluated by solving the equations related to the properties of the main points of the current-voltage (I-V) characteristics. The further information, necessary to calculate the entire set of seven truly independent parameters, is based on two conditions that have to be simultaneously satisfied: 1) the exclusion of negative values of the model pa…
Comparison between textured SnO2:F and Mo contacts with the p-type layer in p–i–n hydrogenate amorphous silicon solar cells by forward bias impedance…
2013
Abstract In this paper we compare the performance of the textured SnO2:F and Mo contacts with the p-type layer in p–i–n hydrogenate amorphous silicon (a-Si:H) solar cells. We use standard current–voltage (I–V) electrical characterization methods coupled with forward bias small signal impedance analysis. We show the efficacy of this technique to determine the effective carrier lifetime in photovoltaic cells. We show that such effective lifetimes are indeed directly connected to the respective dark diode saturation currents. We also find that the effective lifetime is constant with the temperature in the 0–70 °C range and it is significantly better for the solar cell with Mo diode contact. Th…
An accurate one-diode model suited to represent the current-voltage characteristics of crystalline and thin-film photovoltaic modules
2020
Abstract In this paper a new one-diode model, conceived in order to be used to represent the current-voltage curves of both crystalline and thin-film photovoltaic modules, is presented. The model parameters are calculated from the information contained in the datasheets issued by manufactures by means of simple iterative procedures that do not require the assumption of simplifying hypotheses. Some innovative relations describing the dependence of the parameters from the solar irradiance and cell temperature are adopted in order to permit the model to reliably simulate the electrical behaviour of photovoltaic devices operating in real conditions. The ability of the model to calculate the cur…
Cholesterol binding to amyloid-β fibrils: A TEM study
2008
There is increasing interest in the role of brain cholesterol in Alzheimer's disease and the contribution of cholesterol to the formation of amyloid plaques. This paper presents a TEM study showing the binding of soluble approximately 10 nm diameter cholesterol-PEG 600 micelles to amyloid-beta(1-42) (Abeta(1-42)) fibrils formed either in the presence of this cholesterol derivative or to preformed fibrils generated under four different fibrillogenesis conditions. Specimens negatively stained with uranyl acetate revealed that during 24 h fibrillogenesis at 37 degrees C the cholesterol-PEG micelles bound periodically to Abeta(1-42) protofibrils and apparently also formed a thin smooth unbroken…
Polymorphism of amyloid-beta fibrils and its effects on human erythrocyte catalase binding.
2009
The Alzheimer's amyloid-beta (Abeta) peptide exists as a number of naturally occurring forms due to differential proteolytic processing of its precursor molecule. Many of the Abeta peptides of different lengths form fibrils in vitro, which often show polymorphisms in the fibril structure. This study presents a TEM based analysis of fibril formation by eighteen different Abeta peptides ranging in length from 5 to 43 amino acids. Spectrophotometric analysis of Congo red binding to the fibrillar material has been assessed and the binding of human erythrocyte catalase (HEC) to Abeta fibrils has also been investigated by TEM. The results show that a diverse range of Abeta peptides form fibrils a…
Negative staining across holes: application to fibril and tubular structures.
2007
The negative staining technique, when used with holey carbon support films, presents superior imaging conditions than is the case when samples are adsorbed to continuous carbon films. A demonstration of this negative staining approach is presented, using ammonium molybdate in combination with trehalose, applied to several fibrillar and tubular samples. Fibrils formed from the amyloid-beta peptide and the protease inhibitor pepstain A spread very well unsupported across holes and the different polymorphic fibril forms can be readily assessed. However, tubular forms of amyloid-beta have a tendency to be flattened, due to surface tension forces prior to and during specimen drying. Sub-fibril a…
Start-up and Operation of Laboratory-Scale Thermophilic Upflow Anaerobic Sludge Blanket Reactors Treating Vegetable Processing Wastewaters
1997
Thermophilic anaerobic treatment of hot vegetable processing wastewaters was studied in laboratory-scale UASB reactors at 55°C. The high-strength wastewater streams, deriving from steam peeling and blanching of carrot, potato and swede were used. The reactors were inoculated with mesophilic granular sludge. Stable thermophilic methanogenesis with about 60% COD removal was reached within 28 days. During the 134 day study period the loading rate was increased up to 24 kg COD m−3 day−1. High treatment efficiency of more than 90% COD removal and concomitant methane production of 7·3 m3 CH4 m−3 day−1 were achieved. The anaerobic process performance was not affected by the changes in the wastewat…
Experimental alteration of granitic rocks: Implications for the evolution of geothermal brines in the Upper Rhine Graben, Germany
2020
Abstract Geothermal energy exploitation in the Upper Rhine Graben (URG) chiefly has targeted faults and fractures within or connected with the crystalline basement, where hot fluids of c. 200 °C circulate at depths of c. 5 km. Formation fluids of the crystalline basement are highly saline, NaCl-dominated brines, whereas shallow crystalline basement water ( The trace element concentrations of the leachates are hereby related to the composition and stability of minerals in the rocks and can be directly linked to the proposed and observed dissolution processes at the different temperatures. In experiments with pure water at 70 °C, representing the recharge or infiltration conditions, water-roc…