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81.
Thormann A Teuscher N Pfannmöller M Rothe U Heilmann A 《Small (Weinheim an der Bergstrasse, Germany)》2007,3(6):1032-1040
Nanoporous aluminum oxide membranes with high open porosity are prepared by anodic oxidation. Conventional self-supporting as well as mechanically stabilized nanoporous membranes are produced from aluminum plates and microimprinted aluminum foils, respectively. The mechanically stabilized membranes are characterized by very thin membrane parts stabilized by surrounding thick bridges. The minimal thickness of these thin membranes with open pores on both sides is 1 microm, with a mean pore size of the parallel open pores of 185 nm. With these two kinds of membrane the flow rates for cross filtration can be tuned over a wide range. With the mechanically stabilized membranes, substantially higher flow rates are achieved and experiments that cannot be performed with thicker membranes become possible. The biofunctionalization of the pore walls with archaebacterial tetraether lipids is realized and proved using aminated semiconductor nanocrystals. The lipid layer deposited on the pore walls also changes the filtration properties. 相似文献
82.
Comellas-Aragonès M Engelkamp H Claessen VI Sommerdijk NA Rowan AE Christianen PC Maan JC Verduin BJ Cornelissen JJ Nolte RJ 《Nature nanotechnology》2007,2(10):635-639
Most enzyme studies are carried out in bulk aqueous solution, at the so-called ensemble level, but more recently studies have appeared in which enzyme activity is measured at the level of a single molecule, revealing previously unseen properties. To this end, enzymes have been chemically or physically anchored to a surface, which is often disadvantageous because it may lead to denaturation. In a natural environment, enzymes are present in a confined reaction space, which inspired us to develop a generic method to carry out single-enzyme experiments in the restricted spatial environment of a virus capsid. We report here the incorporation of individual horseradish peroxidase enzymes in the inner cavity of a virus, and describe single-molecule studies on their enzymatic behaviour. These show that the virus capsid is permeable for substrate and product and that this permeability can be altered by changing pH. 相似文献
83.
Max Braune Nico Scherf Claudia Heine Katja Sygnecka Thanigaimalai Pillaiyar Chiara Parravicini Bernd Heimrich Maria P. Abbracchio Christa E. Müller Heike Franke 《International journal of molecular sciences》2021,22(21)
Characterization of new pharmacological targets is a promising approach in research of neurorepair mechanisms. The G protein-coupled receptor 17 (GPR17) has recently been proposed as an interesting pharmacological target, e.g., in neuroregenerative processes. Using the well-established ex vivo model of organotypic slice co-cultures of the mesocortical dopaminergic system (prefrontal cortex (PFC) and substantia nigra/ventral tegmental area (SN/VTA) complex), the influence of GPR17 ligands on neurite outgrowth from SN/VTA to the PFC was investigated. The growth-promoting effects of Montelukast (MTK; GPR17- and cysteinyl-leukotriene receptor antagonist), the glial cell line-derived neurotrophic factor (GDNF) and of two potent, selective GPR17 agonists (PSB-16484 and PSB-16282) were characterized. Treatment with MTK resulted in a significant increase in mean neurite density, comparable with the effects of GDNF. The combination of MTK and GPR17 agonist PSB-16484 significantly inhibited neuronal growth. qPCR studies revealed an MTK-induced elevated mRNA-expression of genes relevant for neuronal growth. Immunofluorescence labelling showed a marked expression of GPR17 on NG2-positive glia. Western blot and RT-qPCR analysis of untreated cultures suggest a time-dependent, injury-induced stimulation of GPR17. In conclusion, MTK was identified as a stimulator of neurite fibre outgrowth, mediating its effects through GPR17, highlighting GPR17 as an interesting therapeutic target in neuronal regeneration. 相似文献
84.
Krauter Nico Eckert Sven Gundrum Thomas Stefani Frank Wondrak Thomas Frick Peter Khalilov Ruslan Teimurazov Andrei 《Metallurgical and Materials Transactions B》2018,49(4):2089-2096
Metallurgical and Materials Transactions B - The determination of the Magnesium level in a Titanium reduction retort by inductive methods is often hampered by the formation of Titanium sponge rings... 相似文献
85.
Nico Stehr Hans von Storch 《Journal für Verbraucherschutz und Lebensmittelsicherheit》2009,55(3):56-60
The voice of the social sciences in climate research and in climate policy discussions, except for interventions from economists
mainly about the costs associated with policy options driven by climate science research, has been muted if not altogether
absent. The absence of the social sciences from climate research and policy not surprisingly has coloured climate discourse
in peculiar ways. We are making the case for a greater involvement and importance of the social sciences in interdisciplinary
climate research.
It is not space but the structuring that comes from the soul that has social significance. Georg Simmel ([1908] 1992)
Soil and climate together determine the natural fertility of a country and of its people who are led either to indolence or to activity. Werner Sombart (1938)相似文献
86.
Tomaselli S Esposito V Vangone P van Nuland NA Bonvin AM Guerrini R Tancredi T Temussi PA Picone D 《Chembiochem : a European journal of chemical biology》2006,7(2):257-267
Current views of the role of beta-amyloid (Abeta) peptide fibrils range from regarding them as the cause of Alzheimer's pathology to having a protective function. In the last few years, it has also been suggested that soluble oligomers might be the most important toxic species. In all cases, the study of the conformational properties of Abeta peptides in soluble form constitutes a basic approach to the design of molecules with "antiamyloid" activity. We have experimentally investigated the conformational path that can lead the Abeta-(1-42) peptide from the native state, which is represented by an alpha helix embedded in the membrane, to the final state in the amyloid fibrils, which is characterized by beta-sheet structures. The conformational steps were monitored by using CD and NMR spectroscopy in media of varying polarities. This was achieved by changing the composition of water and hexafluoroisopropanol (HFIP). In the presence of HFIP, beta conformations can be observed in solutions that have very high water content (up to 99 % water; v/v). These can be turned back to alpha helices simply by adding the appropriate amount of HFIP. The transition of Abeta-(1-42) from alpha to beta conformations occurs when the amount of water is higher than 80 % (v/v). The NMR structure solved in HFIP/H2O with high water content showed that, on going from very apolar to polar environments, the long N-terminal helix is essentially retained, whereas the shorter C-terminal helix is lost. The complete conformational path was investigated in detail with the aid of molecular-dynamics simulations in explicit solvent, which led to the localization of residues that might seed beta conformations. The structures obtained might help to find regions that are more affected by environmental conditions in vivo. This could in turn aid the design of molecules able to inhibit fibril deposition or revert oligomerization processes. 相似文献
87.
In this study a specific taste-modulating flavor ingredient, N-lactoyl ethanolamine, was determined in two Beerenauslese wines using preparative LC, as a first isolation and concentration step, followed by LC-MS/MS on a triple quadrupole in accurate mass (AM) mode. The accurate masses of the analyte and three characteristic fragments were determined with mass accuracies between 8 and 20 ppm. N-lactoyl ethanolamine concentrations in the wines were 0.4 and 2.5 mg/L. 相似文献
88.
Photothermal self-phase-modulation technique for absorption measurements on high-reflective coatings
Steinlechner J Jensen L Krüger C Lastzka N Steinlechner S Schnabel R 《Applied optics》2012,51(8):1156-1161
We propose and demonstrate a new measurement technique for the optical absorption of high-reflection coatings. Our technique is based on photothermal self-phase modulation and exploits the deformation of cavity Airy peaks that occurs due to coating absorption of intracavity light. The mirror whose coating is under investigation needs to be the input mirror of a high-finesse cavity. Our example measurements were performed on a high-reflection SiO2-Ta2O5 coating in a three-mirror ring-cavity setup at a wavelength of 1064 nm. The optical absorption of the coating was determined to be α=(23.9±2.0)·10(-6) per coating. Our result is in excellent agreement with an independently performed laser calorimetry measurement that gave a value of α=(24.4±3.2)·10(-6) per coating. Since the self-phase modulation in our coating-absorption measurement affects mainly the propagation through the cavity input mirror, our measurement result is practically uninfluenced by the optical absorption of the other cavity mirrors. 相似文献
89.
Waanders D Janssen D Berahmani S Miller MA Mann KA Verdonschot N 《Journal of materials science. Materials in medicine》2012,23(8):2023-2035
In finite element analysis (FEA) models of cemented hip reconstructions, it is crucial to include the cement-bone interface mechanics. Recently, a micromechanical cohesive model was generated which reproduces the behavior of the cement-bone interface. The goal was to investigate whether this cohesive model was directly applicable on a macro level. From transverse sections of retrieved cemented hip reconstructions, two FEA-models were generated. The cement-bone interface was modeled with cohesive elements. A torque was applied and the cement-bone interface micromotions, global stiffness and stem translation were monitored. A sensitivity analysis was performed to investigate whether the cohesive model could be improved. All results were compared with experimental findings. That the original cohesive model resulted in a too compliant macromechanical response; the motions were too large and the global stiffness too small. When the cohesive model was modified, the match with the experimental response improved considerably. 相似文献
90.
Integrated Assessment models, widely applied in climate change mitigation research, show that renewable energy sources (RES) play an important role in the decarbonization of the electricity sector. However, the representation of relevant technologies in those models is highly stylized, thereby omitting important information about the variability of electricity demand and renewables supply. We present a power system model combining long time scales of climate change mitigation and power system investments with short-term fluctuations of RES. Investigating the influence of increasingly high temporal resolution on the optimal technology mix yields two major findings: the amount of flexible natural gas technologies for electricity generation rises while the share of wind energy only depends on climate policy constraints. Furthermore, overall power system costs increase as temporal resolution is refined in the model, while mitigation costs remain unaffected. 相似文献