			Home About us Contact

Efficiencies Greater (efficiency + greater)

Distribution by Scientific Domains

Polymers and Materials Science	60%

Selected Abstracts

Direct on-line analysis of neutral analytes by dual sweeping via complexation and organic solvent field enhancement in nonionic MEKC

ELECTROPHORESIS, Issue 8 2009
Jun Cao
Abstract Conventionally, neutral compounds cannot be separated by nonionic micelle capillary electrophoresis. In this report, the development of a novel on-line preconcentration technique combining dual sweeping based on complexation and organic solvent field enhancement is applied to the sensitive and selective analysis of three neutral glucosides: ginsenoside Rf, ginsenoside Rg1, and ginsenoside Re. Nonionic micelle detectability by CE is demonstrated through effective focusing of large sample volumes (up to 38% capillary length) using a dual sweeping mode. This results in a 50- to 130-fold improvement in the LODs relative to conventional injection method. Neutral compounds sweeping is examined in terms of analyte mobility dependence on borate complexation, solvent viscosity difference, and Brij-35 interaction. Enhanced focusing performance by this hyphenated method was demonstrated by a greater than fourfold reduction in glucoside bandwidth, as compared with common sweeping (devoid of organic solvent-mediated sweeping method in the sample matrices). Moreover, separation efficiencies greater than a million theoretical plates can be achieved by sweeping large sample volumes into narrow zones. The designated method was also tested for its ability to determine the presence of glucosides in the crude extracts obtained from plant sample. [source]

Efficient synthesis of ethanol and acetic acid from methane and carbon dioxide with a continuous, stepwise reactor

AICHE JOURNAL, Issue 5 2010
W. Huang
Abstract The synthesis of C2 -oxygenates such as ethanol and acetic acid accomplished by CH4 dissociation and subsequent CO2 insertion onto methyl radicals, named the stepwise reaction technology, has been demonstrated to be both feasible and efficient through initial experiments conducted in microreactor units. This article describes the development of this technology, highlighting the aforementioned stepwise technology using a dual-reactor system, which can ensure that two raw gases enter the reactor uninterruptedly and are not mixed after reaction. The system productivity for acetic acid and ethanol displayed efficiencies greater than 5,10 times that of previous microreactor units. The investigation of mechanism indicates that acetic acid arises from insertion of CO2 into MCHx, while ethanol is formed either by hydrogenation of acetic acid or by hydration of C2H4, which results from homo-coupling of CH4. The latter route is the preferred of the two. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source]

Dye-Sensitized Solar Cells Based on TiO2 Coatings with Dual Size-Scale Porosity

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2009
Lai Qi
Dye-sensitized solar cells (DSSC) with efficiencies greater than 4% were produced with templated "inverse opal" titania coatings. A novel one-step method produces uniform and crack-free coatings made using commercially available titania nanoparticles with high reproducibility and uniformity. In this research, a volatile solvent electrolyte was tested; however, it shows proof-of-concept that larger pore volumes can be created for increased penetration of more viscous electrolytes that can be utilized in high-efficiency cells. This dual size-scale porosity film is a promising structure for DSSC applications, especially for those solid-state or quasi-solid-state cells that require polymer electrolytes. [source]

Tuning Conversion Efficiency in Metallo Endohedral Fullerene-Based Organic Photovoltaic Devices

ADVANCED FUNCTIONAL MATERIALS, Issue 14 2009
Russel B. Ross
Abstract Here the influence that 1-(3-hexoxycarbonyl)propyl-1-phenyl-[6,6]-Lu3N@C81, Lu3N@C80,PCBH, a novel acceptor material, has on active layer morphology and the performance of organic photovoltaic (OPV) devices using this material is reported. Polymer/fullerene blend films with poly(3-hexylthiophene), P3HT, donor material and Lu3N@C80,PCBH acceptor material are studied using absorption spectroscopy, grazing incident X-ray diffraction and photocurrent spectra of photovoltaic devices. Due to a smaller molecular orbital offset the OPV devices built with Lu3N@C80,PCBH display increased open circuit voltage over empty cage fullerene acceptors. The photovoltaic performance of these metallo endohedral fullerene blend films is found to be highly impacted by the fullerene loading. The results indicate that the optimized blend ratio in a P3HT matrix differs from a molecular equivalent of an optimized P3HT/[6,6]-phenyl-C61 -butyric methyl ester, C60,PCBM, active layer, and this is related to the physical differences of the C80 fullerene. The influence that active layer annealing has on the OPV performance is further evaluated. Through properly matching the film processing and the donor/acceptor ratio, devices with power conversion efficiency greater than 4% are demonstrated. [source]

Characterization of Quantum Dot/Conducting Polymer Hybrid Films and Their Application to Light-Emitting Diodes

ADVANCED MATERIALS, Issue 48 2009
Jeonghun Kwak
Quantum dot/conducting polymer hybrid films are used to prepare light-emitting diodes (LEDs). The hybrid films (CdSe@ZnS quantum dots excellently dispersed in a conducting polymer matrix, see figure) are readily prepared by various solution-based processes and are also easily micropatterned. The LEDs exhibit a turn-on voltage of 4,V, an external quantum efficiency greater than 1.5%, and almost pure-green quantum-dot electroluminescence. [source]