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81.
Monitoring Charge Exchange in P3HT-Nanotube Composites Using Optical and Electrical Characterisation
Ioannis Alexandrou Emmanouil Lioudakis Dimitrios Delaportas C. Z. Zhao Andreas Othonos 《Nanoscale research letters》2009,4(7):635-639
Charge exchange at the bulk heterojunctions of composites made by mixing single wall nanotubes (SWNTs) and polymers show potential
for use in optoelectronic devices such as solar cells and optical sensors. The density/total area of these heterojunctions
is expected to increase with increasing SWNT concentration but the efficiency of solar cell peaks at low SWNT concentrations.
Most researchers use current–voltage measurements to determine the evolution of the SWNT percolation network and optical absorption
measurements to monitor the spectral response of the composites. However, these methods do not provide a detailed account
of carrier transport at the concentrations of interest; i.e., near or below the percolation threshold. In this article, we
show that capacitance–voltage (C–V) response of (metal)-(oxide)-(semiconducting composite) devices can be used to fill this gap in studying bulk heterojunctions.
In an approach where we combine optical absorption methods with C–V measurements we can acquire a unified optoelectronic response from P3HT-SWNT composites. This methodology can become an important
tool for optoelectronic device optimization. 相似文献
82.
Some stability properties of two gyrator circuits, described by Riordan, are investigated. It is shown that these circuits can attain low-frequency unstable modes of operation. Two alternative gyrator circuits are derived which are shown to be free from low-frequency unstable modes. 相似文献
83.
This paper uses various tests from statistics and dynamical systems theory to support stochastic models to explain the behaviour of the federal funds rate. In particular, a fractional Brownian motion is supported by the power spectrum of the series, the structure function test and the Hurst test. A coloured noise model is supported by the signal differentiation test and the space-time separation test. Evidence against the turbulent behaviour hypothesis is also provided. 相似文献
84.
Kyriaki Kelektsoglou Evangelos T. Karageorgos Ioannis Kosmadakis 《International journal of remote sensing》2013,34(4):1214-1233
Aerosol optical depths (AODs) and single scattering albedos (SSAs) were derived from in situ aircraft measurements of scattering and absorption coefficients at 550 nm. These values were compared to the AODs and SSAs derived from the sun photometer (CIMEL) data of the Aerosol Robotic Network (AERONET) site, in Thessaloniki, Greece, between 18 and 21 July 2006. The aircraft-obtained AODs were lower than the corresponding columnar values. However, aircraft SSAs were found to be in good agreement with the columnar values retrieved from the CIMEL. Aircraft aerosol size distributions measured by means of an optical particle counter (OPC) were also in good agreement with the respective distributions derived from the AERONET site. Filter samples were collected on board the aircraft at different altitudes, to provide detailed information on the chemical composition of tropospheric aerosol. The concentrations of identified chemical species were used to calculate particle refractive indices (RIs) for comparison with the AERONET calculated values. 相似文献
85.
Nuno M. Garrido Ioannis G. Economou António J. Queimada Miguel Jorge Eugénia A. Macedo 《American Institute of Chemical Engineers》2012,58(6):1929-1938
In recent years molecular simulation has emerged as a useful tool to predict physical properties of complex chemical systems. A methodology to estimate the n‐hexane/water and 1‐octanol/water partition coefficients of environmentally relevant solutes, namely substituted alkyl‐aromatic molecules, chlorobenzenes, polychlorinated biphenyls (PCBs) and polychlorinated diphenyl ethers (PCDEs) using molecular simulation is elucidated here. The partition coefficients are calculated based on the absolute solvation Gibbs energies in each phase which are estimated from molecular dynamics simulations employing the thermodynamic integration approach. Very encouraging results, with average absolute deviations of 0.4 log P units are presented. Consequently, this molecular‐based approach with a strong physical background can provide reliable prediction of the partition coefficients in different solvent pairs without the a priori knowledge of experimental data. © 2011 American Institute of Chemical Engineers AIChE J, 58: 1929–1938, 2012 相似文献
86.
87.
Athina G. Ntzimani Vasiliki I. Giatrakou Ioannis N. Savvaidis 《Innovative Food Science and Emerging Technologies》2010,11(1):187-196
The present study examined the effect of natural antimicrobials: Ethylenediaminetetraacetate (EDTA), lysozyme, rosemary and oregano oil and their combinations, on the shelf-life of semi cooked coated chicken fillets stored under vacuum packaging (VP), at 4 ± 0.5 °C for a period of 18 days. The treatments of semi cooked coated chicken fillets examined in the present study were the following: Air-packaged (A, control samples), vacuum-packaged (VP), VP with EDTA–lysozyme solution 1.50% w/w, (VP + EL), VP with rosemary oil 0.20% v/w, (VP + R), VP with oregano oil 0.20% v/w, (VP + O), VP with EDTA–lysozyme solution and rosemary oil (VP + EL + R) and finally VP with EDTA–lysozyme and oregano oil (VP + EL + O). The shelf-life of the samples was determined using both microbiological and sensory analyses. Among the antimicrobial combinations examined in the present study, the treatments VP + EL + R and VP + EL + O were the most effective against the growth of Gram-negative, Gram-positive bacteria, and to a lesser extent on yeasts. Based on both microbiological (TVC data) and sensory (taste attribute) analyses, treatments: VP and VP + O gave a shelf life extension of 6 days, whereas treatments VP + EL + R and VP + EL + O produced a shelf-life extension of 7–8 days, as compared to the control samples.Industrial RelevanceThe present research has highlighted the use of natural antimicrobial treatment combinations, including: EDTA, lysozyme, rosemary and oregano oil and their combinations, in the extension of shelf-life of semi cooked coated chicken fillets stored under vacuum packaging at 4 °C for a period of 18 days. Establishing, the determination of the shelf-life of fresh poultry and products represents a challenge for food companies as poultry meat has a short shelf-life, which causes substantial practical problems for its distribution. Therefore, knowledge of natural preservatives, that can be used as alternatives to chemical additives, that could extend the products' shelf life can have an important economic feedback by reducing losses attributed to spoilage and by allowing the products to reach distant and new markets. This study has shown that combinations of natural antimicrobials can extend the shelf-life of the product. 相似文献
88.
Kyriaki Manoli Dimitris Goustouridis Ioannis Raptis Evangelos Valamontes Merope Sanopoulou 《应用聚合物科学杂志》2010,116(1):184-190
White light reflectance spectroscopy is applied to monitor vapor‐induced thickness changes of polymer films, supported on suitable silicon substrates. Assuming unidirectional swelling due to the constraining support, the equilibrium volume swelling of four methacrylic polymers and two siloxane‐based copolymers upon exposure to various activities of water, methanol, ethanol, and ethyl acetate vapor, at 30°C is evaluated. The deduced sorption isotherms were fitted to the Flory‐Huggins equation and interaction parameters, as well as solubility coefficients at infinite solute dilution, were deduced for each binary system. The relative sorption capacity of the different classes of polymers toward the four vapors are in line with the expected solubility interactions between solvent and solute. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
89.
Ioannis Rigopoulos Basilios Tsikouras Panagiotis Pomonis Konstantin Hatzipanagiotou 《International Journal of Rock Mechanics and Mining Sciences》2010,47(1):69-80
The influence of alteration on the physico-mechanical properties of dolerites from the Pindos and Vourinos ophiolites, northern Greece, is investigated. Quantitative petrographic analysis shows that the samples display various percentages of secondary minerals. Two new micropetrographic indices are calculated from the results of petrographic modal analysis for the engineering assessment of dolerites: the micropetrographic strength index Ips and the replacement index Irep. The samples are also tested to determine water absorption, apparent density, total porosity, sand equivalent, uniaxial compressive strength, Los Angeles abrasion value, aggregate impact value, aggregate abrasion value and polished stone value. The influence of alteration on the rock quality and especially the relationships between the proposed micropetrographic indices and the engineering parameters are determined using regression analysis and the derived equations were verified by the t-test and the F-test. The relationships between the Ips and Irep indices and the engineering properties show that alteration products generally result in mechanically weaker rocks. However, the results of the physico-mechanical tests indicate that dolerites retain their strength and durability due to the low proportions of soft minerals and microcracks, along with the preservation of their igneous textures. The polishing resistance is the only engineering parameter that is positively affected by alteration processes, as expressed by the Ips index. Particularly, the replacement of the primary mafic minerals by secondary minerals, expressed by the Irep index, can enhance the polishing resistance of dolerites when used in the wearing surface of a road. The results also indicate strong positive correlations between the chlorite content and the water absorption and total porosity values. 相似文献
90.
Stamatia Dasiopoulou Ioannis Kompatsiaris Michael G. Strintzis 《Multimedia Tools and Applications》2010,49(1):167-194
Recent advances in semantic image analysis have brought forth generic methodologies to support concept learning at large scale. The attained performance however is highly variable, reflecting effects related to similarities and variations in the visual manifestations of semantically distinct concepts, much as to the limitations issuing from considering semantics solely in the form of perceptual representations. Aiming to enhance performance and improve robustness, we investigate a fuzzy DLs-based reasoning framework, which enables the integration of scene and object classifications into a semantically consistent interpretation by capturing and utilising the underlying semantic associations. Evaluation with two sets of input classifiers, configured so as to vary with respect to the wealth of concepts’ interrelations, outlines the potential of the proposed approach in the presence of semantically rich associations, while delineating the issues and challenges involved. 相似文献