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Transfer Properties (transfer + property)
Kinds of Transfer Properties Selected AbstractsEffect of SWNT Defects on the Electron Transfer Properties in P3HT/SWNT Hybrid Materials,ADVANCED FUNCTIONAL MATERIALS, Issue 18 2008Jianxin Geng Abstract Poly(3-hexylthiophene) (P3HT) hybrids with single-walled carbon nanotubes (SWNTs) were prepared using a series of SWNTs with various defect contents on their surfaces. The hybrids were synthesized by exploiting the ,,, interaction between P3HT and the SWNTs, resulting in efficient dispersion of the carbon nanotubes in the P3HT solution. UV-visible and photoluminescence (PL) spectra showed that the carbon nanotubes quench the PL of P3HT in the hybrids, indicating that electron transfer occurs from photo-excited P3HT to the SWNTs. This electron transfer from P3HT to carbon nanotubes was disrupted by the presence of defects on the SWNT surfaces. However, the PL lifetime of P3HT in the hybrids was found to be the same as that of pure P3HT in solution, indicating the formation of a ground-state non-fluorescent complex of P3HT/SWNTs. [source] Effect of Suspended Liposomes on Hydrodynamic and Oxygen Transfer Properties in a Mini-Scale External Loop Airlift Bubble ColumnCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 9 2006M. Yoshimoto Abstract The circulating liquid velocity, gas holdup, bubble size distribution, and liquid phase oxygen transfer coefficient were measured in a mini-scale external loop airlift bubble column (MELBC) with the liquid volume suspending enzyme-free liposomes of varying diameters. These values were compared to those for liposome-free MELBC, normal bubble column (NBC), and a larger scale airlift column. The liposomes suspended in the MELBC are incorporated into the liquid film around the bubbles, leading to the development of a foam layer, where the incorporated liposomes exert negligible effect on the oxygen transfer in the film. [source] An investigation on thermal-recycling of recycled plastic resin (spherically symmetric analysis of abrupt heating processes of a micro plastic-resin particle)HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 4 2006Ryuji Yamakita Abstract A fundamental understanding of the physical properties of a micro plastic-resin particle subjected suddenly to hot combustion gas, such as the temperature history in the micro particle and its lifetime, is necessary for effectively realizing thermal recycling of recycled plastic resin. However, micro plastic particles have such small diameters, ranging from 100 µm to 200 µm, that the measurement of temperature histories within them is extremely difficult. In this paper, therefore, a spherically symmetric one-dimensional analysis is applied to the abrupt heating process of a micro plastic resin particle in a high temperature inert atmosphere. Variations of the temperature history and the lifetime with the ambient gas temperature and the initial particle diameter are numerically analyzed, by dividing the entire heating process into four independent periods; the solid heating period, the melting period, the liquid heating period, and the vaporization period. Effects of the Nusselt number on the particle lifetime are also discussed. It is found that, by suitably taking account of the influences of heat transfer properties, the proposed simplified analysis is useful for estimating the fundamental and overall temperature characteristics of a micro plastic resin particle under abrupt heating. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(4): 279,293, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20113 [source] Performance and exergetic analysis of vapor compression refrigeration system with an internal heat exchanger using a hydrocarbon, isobutane (R600a)INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2008Ahmet Kabul Abstract Hydrocarbons (HCs) are excellent refrigerants in many ways such as energy efficiency, critical point, solubility, transport and heat transfer properties, but they are also flammable, which causes the need for changes in standards, production and product. There are increasing number of scientists and engineers who believe that an alternative solution, which has been overlooked, may be provided by using HCs. The main objective of this study is to perform energy and exergy analyses for a vapor compression refrigeration system with an internal heat exchanger using a HC, isobutene (R600a). For a refrigeration capacity of 1 kW and cold chamber temperature of 0°C, energy and exergy balances are taken into account to determine the performance of the refrigeration system. Energy and exergy fluxes are determined, and irreversibility rates are calculated for every component of the system. It is seen that the compressor has the highest irreversibility rate, and the heat exchanger has the lowest. Also from the result of the analysis, it is found that condenser and evaporator temperatures have strong effects on energetic and exergetic performances of the system such as coefficient of performance (COP), efficiency ratio (,), exergetic efficiency (,) and irreversibility rate. Copyright © 2008 John Wiley & Sons, Ltd. [source] A novel process for continuous thermal embossing of large-area nanopatterns onto polymer filmsADVANCES IN POLYMER TECHNOLOGY, Issue 4 2009Matthew D. Fagan Abstract Hot embossing and nanoimprinting processes are being widely practiced in industry. Fast and reliable production of micro/nanofeatured patterns on large-area polymer films is of a great importance. In this study, a novel roll-to-roll thermal imprinting process was developed, capable of providing a mold-heating rate of 125°C/s with sufficient temperature control to produce large-area patterns continuously at a rapid production rate. With this new process, selected micro/nano patterns were produced on a polyethylene terephthalate film at a production rate exceeding 1 m/min. The roller mold temperature played a profound role in affecting the replication quality. To achieve good feature transfer properties, an elevated roller mold temperature approaching the melting temperature of the polymer was found to be critical. Microcavity filling time calculation further revealed that the elevated roller mold temperature is also necessary for achieving a rapid film feed rate as desired in the continuous roll-to-roll process. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 28:246,256, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20167 [source] DIFFUSION OF BEET DYE DURING ELECTRICAL AND CONVENTIONAL HEATING AT STEADY-STATE TEMPERATURE,JOURNAL OF FOOD PROCESS ENGINEERING, Issue 5 2001MARYBETH LIMA ABSTRACT Ohmic heating has been shown to alter mass transfer properties of fruit and vegetable tissue. Diffusion of beet dye from beetroot tissue into a fluid was studied during conventional and ohmic heating as a function of steady-state temperature. The volume of beet dye diffusing into solution during ohmic heating was enhanced with respect to conventional heating at 42C and 58C, but not at 72C. This can be explained by examining the differences in electrical conductivity of beet tissue at these temperatures during conventional and ohmic heating. At 42 and 58C, the electrical conductivity of beet tissue heated ohmically is higher than the electrical conductivity of beet tissue heated conventionally. At 72C, the electrical conductivities of beet tissue during conventional and ohmic heating are equal. The extent of diffusion in the ohmic case is also positively correlated with applied voltage. These results suggest that food processes involving mass transfer can be enhanced by choosing conditions in which the electrical conductivity of a sample under ohmic conditions is maximized. [source] Direct laser desorption/ionization time-of-flight mass spectrometry of conjugated polymersJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 1 2007Zhun Ma Abstract Two conjugated polymers (CPs), poly(9,9-dioctylfluorene) (PF) and poly(3-octylthiophene) (PT) were analyzed by direct laser desorption/ionization time-of-flight mass spectrometry (LDI-ToF MS). Because of their strong absorption near the wavelength of the laser (337 nm), easy and transient energy transfer properties and sufficient thermal stability, CPs can be desorbed and ionized directly without a matrix. For comparison, these two polymers were also analyzed using matrix-assisted laser desorption/ionization (MALDI)-ToF MS in the positive reflectron mode. The results revealed that they are very similar in terms of quality and resolution. All results demonstrate that LDI-ToF MS is an alternative method for the mass characterization of some conjugated systems, thereby simplifying the process of sample preparation and result analysis. Copyright © 2006 John Wiley & Sons, Ltd. [source] Effect of high-pressure food processing on the mass transfer properties of selected packaging materialsPACKAGING TECHNOLOGY AND SCIENCE, Issue 5 2010Maria Jose Galotto Abstract The effect of high-pressure processing (HPP) on the total migration into distilled water and olive oil and on the barrier properties of four complex packaging materials were evaluated. The films were polyethylene/ethylene-vinyl-alcohol/polyethylene (PE/EVOH/PE), metallized polyester/polyethylene, polyester/polyethylene (PET/PE), and polypropylene-SiOx (PPSiOx). Pouches made from these films were filled with food simulants, sealed and then processed at a pressure of 400,MPa for 30,min, at 20 or 60°C. Pouches kept at atmospheric pressure were used as controls. Prior to and after treatment, all films were evaluated for their barrier properties (oxygen transmission rate and water vapour transmission rate) and ,Total' migration into the two food simulants. In the case of water as the food stimulant, a low ,Total' migration was observed and even a lower one after the HPP treatment. In the case of oil as the food simulant, a higher ,Total' migration was found compared to the control as a result of damage to the structures during the HPP treatment. The gas permeability of the films increased after the HPP, compared to the control, due to damages in the structure caused during the treatment. The PET/PE film presented minimum changes in properties after HPP. Copyright © 2010 John Wiley & Sons, Ltd. [source] High-pressure processing effects on the mechanical, barrier and mass transfer properties of food packaging flexible structures: a critical reviewPACKAGING TECHNOLOGY AND SCIENCE, Issue 1 2004Cengiz Caner Abstract Food products can be high-pressure processed (HPP) either in bulk or prepackaged in flexible or semi-rigid packaging materials. In the latter case the packaging material is subjected, together with the food, to high-pressure treatment. A number of studies have been performed to quantify the effects of high-pressure processing on the physical and barrier properties of the packaging material, since the integrity of the package during and after processing is of paramount importance to the safety and quality of the food product. This article reviews the results of published research concerning the effect of HPP on packaging materials. Copyright © 2004 John Wiley & Sons, Ltd. [source] Hydrodynamic investigation of bubble-column reactors: effect of column configurationASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2010Abid Akhtar Abstract Bubble-column reactors are quite popular in the chemical, biochemical and petrochemical industries due to their relatively simple construction, favourable heat and mass transfer properties and low operating cost. Among the various design parameters, column geometry (configuration) has a significant impact on the overall throughput. In this study, an experimental investigation of the bubble-column configuration on its hydrodynamics has been conducted with three different sizes of the column (ID = 10,45 cm). A comparison in terms of the overall gas holdup as well as localised bubble properties is performed using the four-point optical technique and hydrodynamic similarities/dissimilarities are discussed. The study showed that the overall gas holdup was a function of the gas flow rate. For the range of gas velocity investigated (9.5,22.3 cm3/ min), the smaller column had 50,60% more holdup than the bigger column. Localised bubble properties exhibited similar behaviour (i.e. higher values for the smaller column). A comparative study of L/D illustrated an invariant behaviour at a high value of L/D (>5.5). A low L/D (,1.5), however, showed a prominent influence on hydrodynamics. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Numerical Simulation of Absorbing CO2 with Ionic LiquidsCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 10 2010X. Wang Abstract Although separating CO2 from flue gas with ionic liquids has been regarded as a new and effective method, the mass transfer properties of CO2 absorption in these solvents have not been researched. In this paper, a coupled computational fluid dynamic (CFD) model and population balance model (PBM) was applied to study the mass transfer properties for capturing CO2 with ionic liquids solvents. The numerical simulation was performed using the Fluent code. Considering the unique properties of ionic liquids, the Eulerian-Eulerian two-flow model with a new drag coefficient correlation was employed for the gas-liquid fluid dynamic simulation. The gas holdup, interfacial area, and bubble size distribution in the bubble column reactor were predicted. The mass transfer coefficients were estimated with Higbie's penetration model. Furthermore, the velocity field and pressure field in the reactor were also predicted in this paper. [source] The Influence of Differences Between Microchannels on Micro Reactor PerformanceCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 3 2005E. R. Delsman Abstract Microstructured reactors most often contain a large number of micrometer-sized, parallel channels, instead of a large undivided reaction volume. Individual microchannels behave as plug-flow reactors without significant axial dispersion and with excellent heat and mass transfer properties. However, since the reaction takes place in a large number of parallel channels, it is important that all channels provide equal residence time and amount of catalyst volume. These issues depend not only on the flow distributor design, but also, for example, on the manufacturing tolerances. Correlations are derived to express the conversion of a multichannel microreactor explicitly as a function of the variance of a number of reactor parameters, viz. the channel flow rate, the channel diameter, the amount of catalyst in a channel, and the channel temperature. It is shown that the influence of flow maldistribution on the overall reactor conversion is relatively small, while the influences of variations in the channel diameter and the amount of catalyst coating are more pronounced. The model outcomes are also compared to experimental results of two microreactors with different catalyst distributions, which show that the presented method is able to provide a quick, though rough estimation of the influence of differences between channels on microreactor performance. [source] Topological and Electron-Transfer Properties of Yeast Cytochrome c Adsorbed on Bare Gold ElectrodesCHEMPHYSCHEM, Issue 11 2003Beatrice Bonanni Dr. Abstract The redox metalloprotein yeast cytochrome c was directly self-chemisorbed on "bare" gold electrodes through the free sulfur-containing group Cys102. Topological, spectroscopic, and electron transfer properties of the immobilised molecules were investigated by in situ scanning probe microscopy and cyclic voltammetry. Atomic force and scanning tunnelling microscopy revealed individual protein molecules adsorbed on the gold substrate, with no evidence of aggregates. The adsorbed proteins appear to be firmly bound to gold and display dimensions in good agreement with crystallographic data. Cyclic voltammetric analysis showed that up to 84,% of the electrode surface is functionalised with electroactive proteins whose measured redox midpoint potential is in good agreement with the formal potential. Our results clearly indicate that this variant of cytochrome c is adsorbed on bare gold electrodes with preservation of morphological properties and redox functionality. [source] | |||||||||||||