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排序方式: 共有1305条查询结果,搜索用时 31 毫秒
221.
Sven Bergmann Matthias Brenner Jennifer Susanne Strehse Tobias Hartwig Bünning Edmund Maser Philipp Grassel David Heuskin David Brandt Marco Berger Simon van der Wulp Mathew Skellhorn Polly Hill Sven Van Haelst Maarten De Rijcke Uwe Wichert 《Propellants, Explosives, Pyrotechnics》2024,49(4):e202300322
Shipwrecks and dumped munition continue to be a major hazard, both in the North Sea but also on a global scale. Research within the EU Interreg project North Sea Wrecks (NSW), in cooperation with the German Aerospace Centre, Institute for the Protection of Maritime Infrastructures (DLR), is generating new insights into the status of wrecks, the potential leakage of pollutants from remaining munitions loads and the effects of contamination on exposed marine organisms in the North Sea environment. Further, historical documents are generated from archives to describe ship's history and sinking scenario. These historical findings were compared to models and images of the visual inspections of the wrecks. Further, samples of water, sediment and organisms are being analysed for traces of explosives. Combining the results of these different fields of research allows for a better understanding of the environmental risks deriving from these wrecks. This process is shown below by focusing on the wreck of the German light cruiser SMS MAINZ, which sank in 1914. Data were compared to three additional wrecks situated also within the southern German Bight. Available data about the wrecks were preliminary assessed using a wreck risk model. Finally, wrecks were ranked according to their potential environmental risk. 相似文献
222.
Andrew J. Russell Maurizio Collu Alasdair S. McDonald Philipp R. Thies Aidan Keane Alexander R. Quayle 《风能》2024,27(4):341-362
Nacelle-mounted, forward-facing light detection and ranging (LIDAR) technology can deliver benefits to rotor speed regulation and loading reductions of floating offshore wind turbines (FOWTs) when assisting with blade pitch control in above-rated wind speed conditions. Large-scale wind turbines may be subject to significant variations in structural loads due to differences in the wind profile across the rotor-swept area. These loading fluctuations can be mitigated by individual pitch control (IPC). This paper presents a novel LIDAR-assisted feedforward IPC approach that uses each blade's rotor azimuth position to allocate an individual pitch command from a multi-beam LIDAR. In this study, the source code of OpenFAST wind turbine modelling software was modified to enable LIDAR simulation and LIDAR-assisted control. The LIDAR simulation modifications were accepted by the National Renewable Energy Laboratory (NREL) and are now present within OpenFAST releases from v3.5 onwards. Simulations of a 15 MW FOWT were performed across the above-rated wind spectrum. Under a turbulent wind field with an average wind speed of 17 ms−1, the LIDAR-assisted feedforward IPC delivered up to 54% reductions in the root mean squared errors and standard deviations of key FOWT parameters. Feedforward IPC delivered enhancements of up to 12% over feedforward collective pitch control, relative to the baseline feedback controller. The reductions to the standard deviation and range of the rotor speed may enable structural optimization of the tower, while the reductions in the variations of the loadings present an opportunity for reduced fatigue damage on turbine components and, consequently, a reduction in maintenance expenditure. 相似文献
223.
Gallic Acid Improves Health‐Associated Biochemical Parameters and Prevents Oxidative Damage of DNA in Type 2 Diabetes Patients: Results of a Placebo‐Controlled Pilot Study
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224.
Andreas FISSEL Ayan Roy CHAUDHURI Jan KRÜGENER Philipp GRIBISCH H. Jörg OSTEN 《材料科学前沿(英文版)》2015,9(2):141
The step-flow growth condition of Si on Si(111) near the (7×7)-"1×1" surface phase transition temperature TC are analyzed within the framework of Burton--Cabrera--Frank theory. In particular, coexistence of both surface phases well below TC and their specific influence on the step-flow growth behavior are considered. We presume that under dynamical condition of growth, the surface initially covered by only the (7×7) phase separates into domains surrounded by "1×1" areas. On such a surface, the overall supersaturation should be reduced drastically compared to a surface with only (7×7), resulting in much larger critical terrace width for nucleation. 相似文献
225.
Viktorija Zitkute Mindaugas Kvietkauskas Vygante Maskoliunaite Bettina Leber Diana Ramasauskaite Kestutis Strupas Philipp Stiegler Peter Schemmer 《International journal of molecular sciences》2021,22(16)
Ischemia/reperfusion injury (IRI) remains a significant problem to be solved in uterus transplantation (UTx). Melatonin and glycine have been shown to possess direct cytoprotective activities, mainly due to their antioxidative and anti-inflammatory properties. The aim of this study was to investigate the protective effects of melatonin and glycine and their combination on IRI in a rat model of warm ischemia. In this study, Sprague-Dawley rats were assigned to eight groups, including sham and IRI (n = 80). Melatonin and glycine alone or their combination were administered prior to 1 h of uterus ischemia followed by 1 h of reperfusion. Melatonin (50 mg/kg) was administered via gavage 2 h before IRI and glycine in an enriched diet for 5 days prior to intervention. Uterus IRI was estimated by histology, including immunohistochemistry, and biochemical tissue analyses. Histology revealed that uterus IRI was significantly attenuated by pretreatment with melatonin (p = 0.019) and glycine (p = 0.044) alone as well as their combination (p = 0.003). Uterus IRI led to increased myeloperoxidase expression, which was significantly reduced by melatonin (p = 0.004), glycine (p < 0.001) or their combination (p < 0.001). The decline in superoxide dismutase activity was significantly reduced in the melatonin (p = 0.027), glycine (p = 0.038) and combined treatment groups (p = 0.015) when compared to the IRI control group. In conclusion, melatonin, glycine and their combination significantly reduced oxidative stress-induced cell damage after IRI in a small animal warm ischemia model, and, therefore, clinical studies are required to evaluate the protective effects of these well-characterized substances in uterus IRI. 相似文献
226.
227.
Proton transfer reaction mass spectrometry and the unambiguous real-time detection of 2,4,6 trinitrotoluene 总被引:1,自引:0,他引:1
Sulzer P Petersson F Agarwal B Becker KH Jürschik S Märk TD Perry D Watts P Mayhew CA 《Analytical chemistry》2012,84(9):4161-4166
Fears of terrorist attacks have led to the development of various technologies for the real-time detection of explosives, but all suffer from potential ambiguities in the assignment of threat agents. Using proton transfer reaction mass spectrometry (PTR-MS), an unusual bias dependence in the detection sensitivity of 2,4,6 trinitrotoluene (TNT) on the reduced electric field (E/N) has been observed. For protonated TNT, rather than decreasing signal intensity with increasing E/N, which is the more usual sensitivity pattern observed in PTR-MS studies, an anomalous behavior is first observed, whereby the signal intensity initially rises with increasing E/N. We relate this to unexpected ion-molecule chemistry based upon comparisons of measurements taken with related nitroaromatic compounds (1,3,5 trinitrobenzene, 1,3 dinitrobenzene, and 2,4 dinitrotoluene) and electronic structure calculations. This dependence provides an easily measurable signature that can be used to provide a rapid highly selective analytical procedure to minimize false positives for the detection of TNT. This has major implications for Homeland Security and, in addition, has the potential of making instrumentation cost-effective for use in security areas. This study shows that an understanding of fundamental ion-molecule chemistry occurring in low-pressure drift tubes is needed to exploit selectivity and sensitivity for analytical purposes. 相似文献
228.
Markus Jakob Thomas Hülser Andreas Janssen Philipp Adomeit Stefan Pischinger Gerd Grünefeld 《Combustion and Flame》2012,159(7):2516-2529
Crude-oil independent liquid fuels are currently being developed for future HSDI diesel engines. Thus, it is the primary objective of the present study to characterize the combustion of selected reference fuels under realistic conditions, in particular with regard to flame lift-off and soot formation. The experiments are conducted in an optically-accessible and a comparable all-metal HSDI engine at part load, using n-decane, n-heptane, 1-decanol, and conventional diesel, respectively, as the fuel. Two image-intensified, high-speed CMOS cameras are employed simultaneously, in order to visualize the highly unsteady combustion process in terms of OH1 radicals and soot, respectively, with relatively high temporal resolution and data throughput.The results demonstrate the influence of the fuel properties, in particular cetane number and volatility, on mixture formation, ignition, combustion, soot formation, and emissions. Relatively high soot emissions for n-decane can basically be explained by its short ignition delay, small lift-off length, and lack of fuel-bound oxygen. The soot formation process seems to be more important for the relative engine-out emissions than soot oxidation under the investigated conditions. Furthermore, a very strong correlation between the ignition delay and the flame lift-off length (during injection) is found. This indicates that lift-off stabilization is essentially determined by autoignition. 相似文献
229.
Philipp M. Leufke Ajay Kumar MishraAndré Beck Di Wang Christian Kübel Robert KrukHorst Hahn 《Thin solid films》2012,520(17):5521-5527
Studies on large-distance sputtering as an effective alternative to molecular beam epitaxy, pulsed laser deposition or off-axis sputtering for the deposition of epitaxial La1 − xSrxMnO3 (LSMO) thin films, are reported. The focus of this study is on the quality of the samples and their structural and magnetic properties. The dependence of the characteristics of the LSMO films on the sputtering mode (rf, dc) and the sputtering parameters, in particular on the oxygen partial pressure is established and discussed. It is shown that large-distance sputtering can provide high quality LSMO thin films without the need for post-annealing. 相似文献
230.
Schlapak R Danzberger J Armitage D Morgan D Ebner A Hinterdorfer P Pollheimer P Gruber HJ Schäffler F Howorka S 《Small (Weinheim an der Bergstrasse, Germany)》2012,8(1):89-97
The bottom-up approach of DNA nano-biotechnology can create biomaterials with defined properties relevant for a wide range of applications. This report describes nanoscale DNA tetrahedra that are beneficial to the field of biosensing and the targeted immobilization of biochemical receptors on substrate surfaces. The DNA nanostructures act as immobilization agents that are able to present individual molecules at a defined nanoscale distance to the solvent thereby improving biomolecular recognition of analytes. The tetrahedral display devices are self-assembled from four oligonucleotides. Three of the four tetrahedron vertices are equipped with disulfide groups to enable oriented binding to gold surfaces. The fourth vertex at the top of the bound tetrahedron presents the biomolecular receptor to the solvent. In assays testing the molecular accessibility via DNA hybridization and protein capturing, tetrahedron-tethered receptors outperformed conventional immobilization approaches with regard to specificity and amount of captured polypeptide by a factor of up to seven. The bottom-up strategy of creating DNA tetrahedrons is also compatible with the top-down route of nanopatterning of inorganic substrates, as demonstrated by the specific coating of micro- to nanoscale gold squares amid surrounding blank or poly(ethylene glycol)-passivated glass surfaces. DNA tetrahedra can create biofunctionalized surfaces of rationally designed properties that are of relevance in analytical chemistry, cell biology, and single-molecule biophysics. 相似文献