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81.
Lars Pleth Nielsen Morten Schønning Steffen V. Christensen Søren V. Hoffmann Zheshen Li Philip Hofmann Flemming Besenbacher Bjerne S. Clausen 《Catalysis Letters》2001,73(2-4):85-90
The sulfiding of Mo/Al2O3 in H2S/Ar versus in H2S/H2 has been studied by temperature-programmed sulfiding (TPS), X-ray photon electron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS), and temperature-programmed desorption of NO (NO-TPD). All the applied techniques agree on the sulfur content in the sulfided catalysts and the findings are in accord with a model for the H2S production reaction. The nucleation and growth of well-ordered MoS2 clusters are probed by XPS during sulfiding with and without the presence of hydrogen. The resulting dispersion of the MoS2 phase is evaluated on the basis of XPS, EXAFS, and NO-TPD, and is found to be highest when the sulfiding occurs in the presence of hydrogen. 相似文献
82.
Cellular Antisense Activity of PNA–Oligo(bicycloguanidinium) Conjugates Forming Self‐Assembled Nanoaggregates 下载免费PDF全文
Dr. Julián Valero Dr. Takehiko Shiraishi Prof. Javier de Mendoza Prof. Peter E. Nielsen 《Chembiochem : a European journal of chemical biology》2015,16(11):1593-1600
A series of peptide nucleic acid–oligo(bicycloguanidinium) (PNA–BGn) conjugates were synthesized and characterized in terms of cellular antisense activity by using the pLuc750HeLa cell splice correction assay. PNA–BG4 conjugates exhibited low micromolar antisense activity, and their cellular activity required the presence of a hydrophobic silyl terminal protecting group on the oligo(BG) ligand and a minimum of four guanidinium units. Surprisingly, a nonlinear dose–response with an activity threshold around 3–4 μM , indicative of large cooperativity, was observed. Supported by light scattering and electron microscopy analyses, we propose that the activity, and thus cellular delivery, of these lipo‐PNA–BG4 conjugates is dependent on self‐assembled nanoaggregates. Finally, cellular activity was enhanced by the presence of serum. Therefore we conclude that the lipo‐BG‐PNA conjugates exhibit an unexpected mechanism for cell delivery and are of interest for further in vivo studies. 相似文献
83.
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85.
F. S. Henna Lu Nina S. Nielsen Charlotte Jacobsen 《European Journal of Lipid Science and Technology》2013,115(2):246-251
The dynamic headspace (DHS) thermal desorption principle using Tenax GR tube, as well as the solid phase micro‐extraction (SPME) tool with carboxen/polydimethylsiloxane 50/30 µm CAR/PDMS SPME fiber, both coupled to GC/MS were implemented for the isolation and identification of both lipid and Strecker derived volatiles in marine phospholipids (PL) emulsions. Comparison of volatile extraction efficiency was made between the methods. For marine PL emulsions with a highly complex composition of volatiles headspace, a fiber saturation problem was encountered when using CAR/PDMS‐SPME for volatiles analysis. However, the CAR/PDMS‐SPME technique was efficient for lipid oxidation analysis in emulsions of less complex headspace. The SPME method extracted volatiles of lower molecular weights more efficient than the DHS method. On the other hand, DHS Tenax GR appeared to be more efficient in extracting volatiles of higher molecular weights and it provided a broader volatile spectrum for marine PL emulsion than the CAR/PDMS‐SPME method. 相似文献
86.
Hadi Noori Mukesh Jain Kent Nielsen Frank Brandys 《Journal of Adhesion Science and Technology》2013,27(13):1403-1413
The peel resistance of adhesively bonded polymer films to a stainless steel sheet substrate (SSSS) with different engineered surface characteristics was examined in two different loading directions and for two different peel speeds. The SSSS was laminated with two thin polymeric adherends using two different pressure-sensitive adhesives. The SSSS surface was altered by grinding and knurling techniques before lamination and the effects of surface alterations on peel resistance were compared with peel resistance of the adherend from as-received SSSS with a bright annealed surface condition. For ground surface, an increase in adherend peel resistance was observed and the increase was attributed to increase in contact area between the adhesive and SSSS surface. For knurled surfaces which involved deeper and less frequent grooves, however, a decrease in peel resistance was observed. This was attributed to a more complex stress state at the peel front in the SSSS groove region during peeling. An increase in peel speed enhanced the peel resistance from both ground and knurled surfaces. 相似文献
87.
Maike Timm‐Heinrich Xuebing Xu Nina Skall Nielsen Charlotte Jacobsen 《European Journal of Lipid Science and Technology》2003,105(8):436-448
Traditional sunflower oil (SO), randomized lipid (RL) and specific structured lipid (SL), both produced from SO and tricaprylin/caprylic acid, respectively, were stored for up to 12 wk to compare their oxidative stabilities by chemical and sensory analyses. Furthermore, the effect of adding a commercial antioxidant blend Grindox 117 (propyl gallate/ citric acid/ascorbyl palmitate) or gallic acid to the SL was investigated. The lipid type affected the oxidative stability: SL was less stable than SO and RL. The reduced stability was most likely caused by both the structure of the lipid and differences in production/ purification, which caused lower tocopherol content and higher initial levels of primary and secondary oxidation products in SL compared with RL and SO. Grindox 117 and gallic acid did not exert a distinct antioxidative effect in the SL oil samples during storage. 相似文献
88.
Maike Timm‐Heinrich Xuebing Xu Nina Skall Nielsen Charlotte Jacobsen 《European Journal of Lipid Science and Technology》2003,105(8):459-470
Milk drinks containing 5% traditional sunflower oil (SO), randomized lipid (RL) or specific structured lipid (SL) (both produced from SO and tricaprylin/caprylic acid) were compared with respect to their particle size, viscosity and oxidative stability during storage. Furthermore, the effect of adding potential antioxidants EDTA or gallic acid to the milk drink based on SL was investigated. The lipid type significantly affected the oxidative stability of the milk drinks: Milk drink based on SL oxidized faster than milk drink based on RL or SO. The reduced oxidative stability in the SL milk drink could not be ascribed to a single factor, but was most likely influenced by the structure of the lipid and differences in the process applied to produce and purify the lipids. EDTA was a strong antioxidant, while gallic acid did not exert a distinct antioxidative effect in the milk drink based on SL. 相似文献
89.
Morten
rregaard Nielsen 《时间序列分析杂志》2005,26(2):279-304
Abstract. We consider semiparametric estimation in time‐series regression in the presence of long‐range dependence in both the errors and the stochastic regressors. A central limit theorem is established for a class of semiparametric frequency domain‐weighted least squares estimates, which includes both narrow‐band ordinary least squares and narrow‐band generalized least squares as special cases. The estimates are semiparametric in the sense that focus is on the neighbourhood of the origin, and only periodogram ordinates in a degenerating band around the origin are used. This setting differs from earlier studies on time‐series regression with long‐range dependence, where a fully parametric approach has been employed. The generalized least squares estimate is infeasible when the degree of long‐range dependence is unknown and must be estimated in an initial step. In that case, we show that a feasible estimate which has the same asymptotic properties as the infeasible estimate, exists. By Monte Carlo simulation, we evaluate the finite‐sample performance of the generalized least squares estimate and the feasible estimate. 相似文献
90.
L. H. Lang D. C. Kang S. H. Zhang Z. R. Wang S. J. Yuan K. B. Nielsen J. Dancket ) Department of Materials Engineering Harbin Institute of Technology Harbin China ) Aalberg University Denmark 《金属学报(英文版)》2000,13(2):476-480
1.~nonHydridapawhcdeepdrawing(HDD)belongstothefieldofsheetmetalfoeingandcanbeaPPliedinthefieldofautomotive,aerospace,drilitaryindustryetc.Ithasbeenrecognizedwidelyintheworld["'j.Fig.Ishowsitsprinciple:TheliqUidthatisfilledinthe~ngdiecavitywillbepressedwhenthepunchgoesdownsothattheeffectoffrictionkeepingandoverflowlubricatingcanbeformed,astherestilt,thefoeinglicitofsheetmetalwillbeimprovedareailvandthegualitVofthefinishedpartswillbeup~ed.BecauseofmanyadvantagesofHDDprocees,ithasbeenwidelys… 相似文献