Search results for "efficient"
showing 10 items of 1603 documents
Chemical Reactivity in AOT Microemulsions: Kinetics of Water Replacement in a Square-Planar Palladium(II) Aquo Complex by Monoalkylthioureas
1998
The kinetics of water replacement in the cationic palladium(II) aquo complex [Pd(Et4dien)(H2O)]2+, where Et4dien = Et2N(CH2)2NH(CH2)2NEt2, by thiourea, methylthiourea, and ethylthiourea have been studied at 25.0 °C in heptane−AOT−water microemulsion over a wide range of the molar ratio R (=[H2O]/[AOT]) at the constant surfactant concentration of 0.13 mol dm-3. The reaction rates are significantly higher in microemulsions than in bulk water and decrease rapidly as the parameter R increases. The kinetic data, interpreted quantitatively by applying the pseudophase model to the microemulsion, indicate that there is a weak partitioning of the nucleophiles between the water core and the AOT inter…
Calculations on solvents and co-solvents of single-wall carbon nanotubes:cyclopyranoses
2005
The (10, 10) single-wall carbon nanotube (SWNT) presents consistency between relatively small solubility, and large partition coefficients and kinetic stability. The solubility of SWNTs is investigated in a variety of solvents, finding a class of non-hydrogen-bonding Lewis bases that provides good solubility. The organic solvent–water partition and hydrophobic moment of lysozyme show that the main contribution to the water-accessible surface area of helices is the hydrophobic term, while the hydrophilic part dominates in the sheet, which is related to the 1-octanol–, cyclohexane– and chloroform–water partition coefficients Po−ch−cf of helices, which are greater than those of the sheet. The …
Extraction of the fluoride-, chloride- and bromide complexes of the elements Nb, Ta, Pa, and 105 into aliphatic amines
1998
Abstract Previous studies of the halide complex formation of element 105 in HCl–HF mixtures and extractions into triisooctyl amine (TIOA) have been performed with the Automated Rapid Chemistry Apparatus, ARCA II. Element 105 was shown to be absorbed on the column from 12 M HCl–0.02 M HF together with its lighter homologues Nb, Ta and the pseudohomologue Pa. In elutions with 10 M HCl–0.025 M HF, 4 M HCl–0.02 M HF, and 0.5 M HCl–0.01 M HF, the extraction sequence Ta>Nb>105>Pa was observed and element 105 behaved very differently from its closest homologue Ta. As it is not possible within reasonable effort to model the many presumably mixed fluoride–chloride complexes involved in these studies…
Anisotropy of the refractive index and absorption coefficient in the layer plane of gallium telluride single crystals
1995
Refractive index and absorption coefficient of GaTe for light polarized in the optical axis directions in the layer plane are determined from transmission measurements. The refractive index is determined in the wavelength range from 0.7 to 25 μm and the absorption coefficient in the range of energies from 1.6 to 2 eV at room temperature and at 30 K. The optical constants are found to be anisotropic in the layer plane. The refractive index dispersion is interpreted through a Phillips-Van Vechten model and the Penn gaps for each direction are found to be E pg (⊥b) = 3.37 eV and E pg (∥b) = 3.58 eV. In the long-wavelength region a polar phonon contribution is also taken into account. The absor…
Spray Atomization Models in Engine Applications, from Correlations to Direct Numerical Simulations
2011
Sprays are among the very main factors of mixture formation and combustion quality in almost every (IC) engine. They are of great importance in pollutant formation and energy efficiency although adequate modeling is still on development. For many applications, validation and calibration of models are still an open question. Therefore, we present an overview of existing models and propose some trends of improvement. Models are classified in zero dimensional and dimensional classes ranging from simple formulations aimed at close-to-real-time applications to complete detailed description of early atomization stages.
Characterization of cooling loads in the wine industry and novel seasonal indicator for reliable assessment of energy saving through retrofit of chil…
2020
Abstract The food sector is a major consumer of energy and growing efforts are being made in the search for solutions that will guarantee the efficient and sustainable use of energy resources. Among the different sectors, wineries are attracting particular interest due to the continuous growth of the global market and production. Surveys conducted in the winemaking sector have highlighted the importance of performing accurate energy audits and have identified the installation of efficient refrigeration systems as a promising solution in a variety of cases. Unfortunately, the savings achievable by efficient cooling technologies are often estimated using simplified approaches which do not tak…
Exergoeconomic analysis as support in decision-making for the design and operation of multiple chiller systems in air conditioning applications
2020
Abstract Multiple-chillers systems represent viable solutions for medium/large-scale air conditioning applications characterized by variable cooling demand. The energy efficiency of such systems is influenced by the number of chillers, the combination of cooling capacities, and the load-sharing among the units. Large efforts have been devoted to developing efficient operation strategies for these systems, but rules of thumb are usually adopted for selecting cooling capacities thus leaving room for energy and economic savings. In this paper, exergoeconomic analysis is proposed as a promising method to identify near-optimal design and operation strategies, due to the capability of exergoecono…
Calculation of organic solvent–water partition coefficients of iron–sulfur protein models
2002
Abstract A method is presented that permits semiquantitative estimation of the partitioning of many solutes between many pairs of media. As an example, the organic solvent–water partition coefficients P are calculated. The only needed parameters are the dielectric constant and molecular volume of the organic solvent. Fe 4 S 4 Cys n models of high-potential FeS proteins are studied. The Gibbs free energies of solvation and partition coefficients for Fe 4 S 4 Cys n are calculated. The organic solvent–water partition coefficients for 1-octanol P o , cyclohexane P ch and chloroform P cf decrease 4.41, 6.22 and 4.60 log units per cysteine (Cys) ligand, respectively. P o results are compared with…
Iron as a source of color in river waters.
2015
Organic chromophores of total organic carbon (TOC) and those of iron (Fe) contribute to the color of water, but the relative contributions of colored organic carbon (COC%) and Fe (Fe%) are poorly known. In this study, we unraveled Fe% and COC% in 6128 unfiltered water samples collected from 94 Finnish river sites of contrasting catchment properties. According to regression analysis focusing on TOC alone, on average 84% of the mean TOC consisted of COC, while 16% was non-colored or below the color-detection limit. COC and Fe were much more important sources of color than phytoplankton (chlorophyll a as a proxy) or non-algal particles (suspended solids as a proxy). When COC and Fe were consid…
Chlorophyll Concentration Retrieval by Training Convolutional Neural Network for Stochastic Model of Leaf Optical Properties (SLOP) Inversion
2020
Miniaturized hyperspectral imaging techniques have developed rapidly in recent years and have become widely available for different applications. Combining calibrated hyperspectral imagery with inverse physically based reflectance models is an interesting approach for estimating chlorophyll concentrations that are good indicators of vegetation health. The objective of this study was to develop a novel approach for retrieving chlorophyll a and b values from remotely sensed data by inverting the stochastic model of leaf optical properties using a one-dimensional convolutional neural network. The inversion results and retrieved values are validated in two ways: A classical machine learning val…