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21.
Chromatographic preconcentration coupled to capillary electrophoresis via an in-line injection valve
A preconcentration-capillary electrophoresis (CE) system using a small precolumn in combination with an in-line injection valve is presented. The advantage of the present design is the ability to perform the sample preconcentration fully independently from the CE separation and to prevent sample matrix and washing solvents from entering the CE capillary. With a micro injection valve, sample could be effectively introduced into the CE system in an in-line fashion without seriously affecting the CE separation efficiency. Breakthrough volume, desorption efficiency, and elution volume for the C18 microcolumn (5 x 0.5 mm i.d.) were established, yielding values of 750 microL, 70%, and 0.9-1.1 microL, respectively, using enkephalin peptides. The time between the start of the desorption of the analytes from the precolumn and the injection into the CE system was also studied in order to achieve optimal sensitivity and separation efficiency. The performance of the complete system was demonstrated by the preconcentration and separation of an enkephalin mixture. Using a sample volume of 250 microL and a CE injection voltage of -15 kV for 12 s, linearity was observed over 2 orders of magnitude, and detection limits (S/N = 3) were in the 5-10 ng/mL range. A 1000-fold sensitivity enhancement is obtained using this setup, as compared to a regular CE setup. For 100 ng/mL samples, repeatabilities (RSDs) of migration time and peak area were 1.2 and 11%, respectively. 相似文献
22.
Willy Jankowski 《国际钢铁研究》1977,48(12):629-632
Definition von Eigenspannungen. Verfahren zum Nachweis und zur Messung von Eigenspannungen. Vorstellung eines neuen Meßverfahrens zur Bestimmung der Höhenverteilung von Eigenspannungen. Mechanische und spannungsoptische Modellversuche. Anwendung des Meßverfahrens auf Schweißeigenspannungen. 相似文献
23.
本文针对昆明的发展特征及面临的挑战,引入了一种全覆盖的综合规划方法来从整体上协调空间的各种职能及保护自然潜力.对大昆明区采用基于GIS的区域模型模拟了这些政策和方法的潜在影响力.结果显示,污染减少、土地利用成本和基础设施的建设成本降低,同时城市的竞争力提高. 相似文献
24.
Hahn Griebel W. Schreiber Carls J. Großfeld Steinbeck Beckel Schwaibold Lehnartz Meumann Schormüller Jesser R. Strohecker Lehnartz Diemair R. Grau Lars Erlandson Patzsch Reichard Ph. Bruno Roßmann Brüning Karl Sauer Willy Lindner Kanitz O. Windhausen Schloemer Amelung M. Steiner R. Mancke K. Höll Goreczky E. Tornow Zacher Kleinhans und Bäurle 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1943,85(1):70-112
Ohne Zusammenfassung 相似文献
25.
We propose a new approach for catalyst development that combines different scientific disciplines: experimental design, surface
science, reaction kinetics and simulations with the objective of accelerating catalyst development. In this paper we present
a study of the possibilities of using small data sets in microkinetic modeling, and studies of the required precision of temperature
measurement. 相似文献
26.
Surface Cleanliness Effect on Lunar Soil Shear Strength 总被引:1,自引:0,他引:1
Lunar soil consists of dry silty sand. Observations and measurements conducted during Surveyor, Apollo, and Luna missions indicated that the lunar soil is unusually cohesive. This is attributable to the fact that thick layers of adsorbed gases, which coat and lubricate soil particles on Earth, are absent in the ultrahigh vacuum on the Moon. “Surface cleanliness” is introduced as a new parameter for describing soils in different planetary environments. It is defined as the dimensionless inverse of adsorbate thickness on solid surfaces. By this definition, the ultrahigh vacuum on the Moon is associated with high surface cleanliness, while Earth's atmosphere is associated with low surface cleanliness. A model is developed to calculate surface cleanliness and its effect on shear strength in any planetary environment. Results obtained from the model compare well with data from previous ultrahigh vacuum and variable temperature laboratory experiments on Earth soils. It is shown that surface cleanliness is an important parameter with respect to lunar soil shear strength. 相似文献
27.
Marta Carballa Wim Moerman Wim De Windt H Grootaerd Willy Verstraete 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(1):63-68
BACKGROUND: Owing to more stringent phosphate discharge requirements and the increasing prices of fertilizers, beneficial recovery and reuse of phosphate from industrial anaerobic effluents is becoming an important issue. Phosphate recovery by struvite or magnesium ammonium phosphate (MAP) permits its recycling in the fertilizer industry because struvite is a valuable slow release fertilizer. Two different approaches to MAP crystallization depending on initial levels of phosphate in the wastewaters were tested and compared. RESULTS: For low‐phosphate‐containing anaerobic effluents (<30 mg PO43?‐P L?1), a novel approach using ureolytic induced MAP formation with MgO addition appeared to be suitable. The residual phosphate concentrations in the effluent ranged from 5 to 7 mg PO43?‐P L?1 and the separated matter contained residual amounts of Mg(OH)2. High‐phosphate‐containing anaerobic effluents (100 to 120 mg PO43?‐P L?1) were treated efficiently using air stripping combined with MgCl2 and NaOH reagents, yielding residual phosphate levels of 8 to 15 mg PO43?‐P L?1 and spherical pure MAP crystals of 0.5 to 2 mm. CONCLUSION: Results show that depending on the initial phosphate concentrations in the wastewaters and the ammonium and magnesium levels, the strategy selected for struvite crystallization is a determinative factor in achieving a cost effective technology. Copyright © 2008 Society of Chemical Industry 相似文献
28.
Xiaofeng Chen Fangguo Zhang Haibo Tian Baodian Wei Willy Susilo Yi Mu Hyunrok Lee Kwangjo Kim 《Information Sciences》2008,178(21):4192-4203
The “hash–sign–switch” paradigm was firstly proposed by Shamir and Tauman with the aim to design an efficient on-line/off-line signature scheme. Nonetheless, all existing on-line/off-line signature schemes based on this paradigm suffer from the key exposure problem of chameleon hashing. To avoid this problem, the signer should pre-compute and store a plenty of different chameleon hash values and the corresponding signatures on the hash values in the off-line phase, and send the collision and the signature for a certain hash value in the on-line phase. Hence, the computation and storage cost for the off-line phase and the communication cost for the on-line phase in Shamir–Tauman’s signature scheme are still a little more overload. In this paper, we first introduce a special double-trapdoor hash family based on the discrete logarithm assumption and then incorporate it to construct a more efficient generic on-line/off-line signature scheme without key exposure. Furthermore, we also present the first key-exposure-free generic on-line/off-line threshold signature scheme without a trusted dealer. Additionally, we prove that the proposed schemes have achieved the desired security requirements. 相似文献
29.
Geert Lissens Helene Klinke Willy Verstraete Birgitte Ahring Anne Belinda Thomsen 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2004,79(8):889-895
Woody yard waste with high lignin content (22% of dry matter (DM)) was subjected to wet oxidation pre‐treatment for subsequent enzymatic conversion and fermentation. The effects of temperature (185–200 °C), oxygen pressure (3–12 bar) and addition of sodium carbonate (0–3.3 g per 100 g DM biomass) on enzymatic cellulose and hemicellulose (xylan) convertibility were studied. The enzymatic cellulose conversion was highest after wet oxidation for 15 min at 185 °C with addition of 12 bars of oxygen and 3.3 g Na2CO3 per 100 g waste. At 25 FPU (filter paper unit) cellulase g?1 DM added, 58–67% and 80–83% of the cellulose and hemicellulose contained in the waste were converted into monomeric sugars. The cellulose conversion efficiency during a simultaneous saccharification and fermentation (SSF) assay at 10% DM was 79% for the highest enzyme loading (25 FPU g?1 DM) while 69% conversion efficiency was still reached at 15 FPU g?1 DM. Total carbohydrate recoveries were high (91–100% for cellulose and 72–100% for hemicellulose) and up to 49% of the original lignin and 79% of the hemicellulose could be solubilized during wet oxidation treatment and converted into carboxylic acids mainly (total carboxylic acids = 3.1–7.4% on DM basis). Copyright © 2004 Society of Chemical Industry 相似文献
30.
Bames Karl Sauer E. Dinslage J. Großfeld Griebel Kluge Willy Lindner W. Schreiber Kanitz Schwaibold Schloemer Nelly Neuenschwander-Lemmer Lars Erlandsen W. Ludorff Pawletta Beckel Diemair Jesser Schormüller Lindner R. Strohecker G. Steinhoff Steinbeck Mohler W. Wodsak Weinig Reichard Brüning R. Grau Hans Hawelka O. Windhausen Bäurle H. Schubert K. Müller Hanak und K. Höll 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1942,84(1):45-96
Ohne Zusammenfassung 相似文献