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排序方式: 共有313条查询结果,搜索用时 15 毫秒
111.
Lasse Bay Keld West Bjrn Winther-Jensen Torben Jacobsen 《Solar Energy Materials & Solar Cells》2006,90(3):341-351
The electrochemical reaction rate of the redox couple iodide/tri-iodide in acetonitrile is characterised by impedance spectroscopy. Different electrode materials relevant for the function of dye-sensitised solar cells (DSSC) are investigated. Preferably, the reaction with the iodide/tri-iodide couple should be fast at the counter electrode, i.e. this electrode must have a high catalytic activity towards the redox couple, and the same reaction must be slow on the photo electrode.The catalytic activity is investigated for platinum, poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole (PPy), and polyaniline (PANI)—all deposited onto fluorine-doped tin oxide (FTO) glass. Both Pt and PEDOT are found to have sufficiently high catalytic activities for practical use as counter electrodes in DSSC. The reaction resistance on FTO and anatase confirmed the beneficial effect of a compact anatase layer on top of the FTO glass in lowering the tri-iodide reduction rate. 相似文献
112.
Hormone-sensitive lipase: structure, function, evolution and overproduction in insect cells using the baculovirus expression system 总被引:1,自引:0,他引:1
Holm Cecilia; Belfrage Per; Osterlund Torben; Davis Richard C.; Schotz Michael C.; Langin Dominique 《Protein engineering, design & selection : PEDS》1994,7(4):537-541
Hormone-sensitive lipase (HSL) catalyses the rate-limiting stepin the hydrolysis of stored triacylglycerols and is therebya key enzyme in lipid metabolism and overall energy homeostasis.The gene organization of human HSL indicates that each putativefunctional region is encoded by a different exon, raising thepossibility that HSL is a mosaic protein. The catalytic serine(Ser423), as shown by site-directed mutagenesis, is encodedby exon 6. The phosphorylation site for cAMP-mediated activitycontrol and a second site, which is presumably phosphorylatedby 5' AMP-activated kinase, are encoded by exon 8, and a putativelipid-binding region is encoded by the ninth and last exon.Besides the catalytic site serine motif (GXSXG), found in virtuallyall Upases, a sequence similarity between the region surroundingthe catalytic site of HSL and that of five prokaryotic enzymeshas been found, but the functional basis of this is not yetunderstood. To resolve the 3-D structure of HSL, an expressionsystem utilizing recombinant baculovirus and insect cells hasbeen established. The expressed protein, 80 mg/l culture, hasbeen purified to homogeneity and a partial characterizationindicates that it has the same properties as HSL purified fromrat adipose tissue. 相似文献
113.
Finn Arup Nielsen Mark Schram Christensen Kristoffer H Madsen Torben E Lund Lars Kai Hansen 《IEEE engineering in medicine and biology magazine》2006,25(2):112-119
Functional magnetic resonance imaging (fMRI) generates vast amounts of data. The handling, processing, and analysis of fMRI data would be inconceivable without computer-based methods. fMRI neuroinformatics is concerned with research, development, and operation of these methods. Reconstruction, rudimentary analysis, and visualization tools are implemented in software controlling modern MRI scanners. Research in advanced methods for analysis of subtle activation patterns, realistic physiological modeling, or integration of data from multiple subjects is the basis for a lively research field and has led to the development of a large number of tools. 相似文献
114.
115.
The aim of the study was to test the hypothesis that a low-ventilation rate in homes is associated with an increased prevalence of asthma and allergic symptoms among children. A total of 198 cases (with at least two of three symptoms: wheezing, rhinitis, eczema) and 202 healthy controls, living in 390 homes, were examined by physicians. Ventilation rates were measured by a passive tracer gas method, and inspections were carried out in the homes. About 60% of the multi-family houses and about 80% of the single-family houses did not fulfill the minimum requirement regarding ventilation rate in the Swedish building code (0.5 air changes per hour, ach). Cases had significantly lower ventilation rates than controls and a dose-response relationship was indicated. PRACTICAL IMPLICATIONS: A low-ventilation rate of homes may be a risk factor for allergies among children. Families with allergic children should be given the advice to have good ventilation in the home. In investigations, of associations between environmental factors and allergies, the air change rate in homes has to be considered. 相似文献
116.
Rapee Gosalawit-Utke Chiara Milanese Payam Javadian Julian Jepsen Daniel Laipple Fahim Karmi Julián Puszkiel Torben R. Jensen Amedeo Marini Thomas Klassen Martin Dornheim 《International Journal of Hydrogen Energy》2013
Nanoconfinement of 2LiBH4–MgH2–TiCl3 in resorcinol–formaldehyde carbon aerogel scaffold (RF–CAS) for reversible hydrogen storage applications is proposed. RF–CAS is encapsulated with approximately 1.6 wt. % TiCl3 by solution impregnation technique, and it is further nanoconfined with bulk 2LiBH4–MgH2 via melt infiltration. Faster dehydrogenation kinetics is obtained after TiCl3 impregnation, for example, nanoconfined 2LiBH4–MgH2–TiCl3 requires ∼1 and 4.5 h, respectively, to release 95% of the total hydrogen content during the 1st and 2nd cycles, while nanoconfined 2LiBH4–MgH2 (∼2.5 and 7 h, respectively) and bulk material (∼23 and 22 h, respectively) take considerably longer. Moreover, 95–98.6% of the theoretical H2 storage capacity (3.6–3.75 wt. % H2) is reproduced after four hydrogen release and uptake cycles of the nanoconfined 2LiBH4–MgH2–TiCl3. The reversibility of this hydrogen storage material is confirmed by the formation of LiBH4 and MgH2 after rehydrogenation using FTIR and SR-PXD techniques, respectively. 相似文献
117.
Larsen T 《Food chemistry》2012,135(3):1261-1267
The present paper describes an enzymatic-fluorometric method for the determination of cholesterol in milk and other opaque matrices. The initial step of the method is to liberate chemically and physically bound cholesterol from the milk fat globule membrane by enzymatic action. The method is able to discriminate between esterified and free cholesterol in milk. The analysis is cost effective and is developed to work directly on whole, fresh milk thereby eliminating time consuming and tedious pre-treatment procedures of the sample. More than 1000 milk samples were analysed on the day of sampling. The total concentration of milk cholesterol ranged from 80 to 756μM (n=1068; mean 351μM). Milk cholesterol was significantly correlated to milk fat concentration as analysed by mid-infra red spectrometry (r=0.630; n=853) and by an enzymatic-fluorometric method (triacylglycerol) (r=0.611; n=842). 相似文献
118.
This study shows the hydrogen desorption kinetics and reversible hydrogen storage properties of 0.55LiBH4–0.45Mg(BH4)2 melt-infiltrated in different nanoporous carbon aerogels with different BET surface areas of 689 or 2660 m2/g and pore volumes of 1.21 or 3.13 mL/g. These investigations clearly show a significantly improved hydrogen storage capacity after four cycles of hydrogen release and uptake for bulk 0.55LiBH4–0.45Mg(BH4)2 and infiltrated in carbon aerogel and the high surface area scaffold, where 22, 36 and 58% of the initial hydrogen content remain after four cycles of hydrogen release and uptake, respectively. Nanoconfinement in high surface area carbon aerogel appears to facilitate hydrogen release illustrated by release of 13.3 wt% H2 (93%) and only 8.4 wt% H2 (58%) from bulk hydride in the first cycle using the same physical condition. Notably, nanoconfinement also appear to have a beneficial effect on hydrogen uptake, since 8.3 wt% H2 (58%) is released from the high surface area scaffold and only 3.1 wt% H2 (22%) from the bulk sample during the fourth hydrogen release. 相似文献
119.
Steve Flechsig Torben Borgolte Yaroslav Utchenko Johanna Sohr Markus Schubert Uwe Hampel Eugeny Y. Kenig 《化学,工程师,技术》2019,91(1-2):125-138
The efficiency of columns for fluid separation can be increased by the application of sandwich packings. During the operation, different load‐dependent regimes with peculiar separation performance arise. In order to account for the effects of the individual flow regimes in a single model, both separation performance measurements and tomographic imaging are applied. A rate‐based model is presented, which takes the heterogeneous regimes in sandwich packings into account by means of appropriate correlations. The model is tested with experimental data for CO2 absorption. 相似文献
120.
Dmytro Korablov Flemming Besenbacher Torben R. Jensen 《International Journal of Hydrogen Energy》2018,43(34):16804-16814
0.75Mg?0.25TM?H (TM = Ti, Nb or V) samples were mechano-chemically synthesized by reactive ball milling. The detailed reaction mechanism during hydrogen release and uptake was investigated by in-situ synchrotron radiation powder X-ray diffraction (SR-PXD) experiments. The thermodynamic and kinetic properties have been studied by Sievert's method. On the base of calculated values of the Gibbs free energy for reaction of hydrogen absorption (ΔG < 0) it reveals that hydrogenation reaction could thermodynamically proceed at room temperature, which is experimentally confirmed for all of the studied composites. It is clearly shown that β-MgH2 forms at RT under conditions of experiment. Comparative analysis of the MgTi, MgV and MgNb systems makes it possible to establish that the most effective additive facilitating hydrogen uptake, particularly at RT, is vanadium. It provides the degree of conversion into hydride phase α = 0.86 for the first minute of hydrogenation. In contrast, additives of Nb and Ti provide only α = 0.62 and 0.36, respectively, following the 30 min of exposure. However, this study reveals that for the dehydrogenation process, titanium is the best among the examined additives, which is evidenced by lowest value of activation energy Ea = 53.6 kJ/mol of the hydrogen desorption. 相似文献