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991.
J.M. Campos‐Martin M.C. Capel‐Sanchez P. Perez‐Presas J.L.G. Fierro 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2010,85(7):879-890
Environmental concerns have introduced a need to remove sulfur‐containing compounds from light oil. As oxidative desulfurization is conducted under very mild reaction conditions, much attention has recently been devoted to this process. In this contribution, the developments in selective removal of organosulfur compounds present in liquid fuels via oxidative desulfurization, including both chemical oxidation and biodesulfurization, are reviewed. At the end of each section, a brief account of the research directions needed in this field is also included. Copyright © 2010 Society of Chemical Industry 相似文献
992.
This paper reports the results of studying various approaches in non-sacrificial boundary lubrication in which the deposition of a beneficial surface layer is the result of a chemical reaction involving one or more components in the lubricating fluid but not the metal surface itself. This is in contrast to the conventional approach which involves the rubbing surfaces as reactants with the components in the lubricant and usually promotes wear as the result of chemical change of the surfaces. The most interesting findings show that a reaction between a molybdenum complex and a mixture of zinc dialkylphosphorodithioates produced in situ deposition of MoS2 and some other unidentified crystalline material. Effective reductions in friction and wear were obtained. Electron diffraction patterns of the worn metal surface established the presence of MoS2. 相似文献
993.
By mapping the small-angle X-ray scattering (SAXS) from a looped poly-(para-phenylene terephtalamide) (aramid, PPTA) filament using a synchrotron X-ray microbeam, we investigate the effects of axially compressive and tensile strain on internal fibrillar structures. Unique observations of oscillations in the highly anisotropic SAXS patterns indicate a regular internal structure. Upon increase of the applied compressive strain, a significant decrease in oscillation frequency is observed in the scattering pattern. With an increase in imposed tensile strain an increase in oscillation frequency in the scattering pattern is observed. One model capable of describing the intensity is a model of stacked cylinders. These cylinders could be part of the fibrillar structure present in the PPTA fibres, which consist of cylinder- to tape-like objects, the presence of which is supported by SEM images. One hypothetical physical interpretation presented here for the appearance of a regular internal structure is the occurrence of fibrillar separation in regions undergoing axially compressive strain, and the appearance of strain relief/slip planes between packs of fibrils in regions undergoing tensile strain. Compaction of these packs upon increase of tensile strain could increase the repetition distance in the structure as multiple packs combine to form a single pack. 相似文献
994.
Nadja Schulz Oliver Kluth Martin Jastroch Annette Schürmann 《International journal of molecular sciences》2013,14(9):18989-18998
An appropriate insulin secretion by pancreatic beta-cells is necessary to maintain glucose homeostasis. A rise in plasma glucose leads to increased metabolism and an elevated cytoplasmic ATP/ADP ratio that finally triggers insulin granule exocytosis. In addition to this triggering pathway, one or more amplifying pathways—activated by amino acids or fatty acid—enhance secretion by promoting insulin granule recruitment to, and priming at, the plasma membrane. The aim of this study was to clarify the impact of the mitochondrial respiratory activity on fatty acid-induced insulin secretion that was assessed by an extracellular flux analyzer. Treatment of isolated mouse islets with glucose (20 mM) increased insulin secretion 18-fold and correlated with ATP-synthesizing respiration. Furthermore, oxygen consumption rate (OCR) significantly increased by 62% in response to glucose, whereas the addition of palmitate resulted only in a minor increase of OCR at both 2.8 mM (11%) and 20 mM glucose (21%). The addition of palmitate showed a pronounced increase of coupling efficiency (CE) at 2.8 mM glucose but no further insulin secretion. However, treatment with palmitate at 20 mM glucose increased insulin secretion about 32-fold accompanied by a small increase in CE. Thus, fatty acid induced respiration has a minor impact on insulin secretion. Our data clearly demonstrate that fatty acids in contrast to glucose play a minor role for respiration-mediated insulin secretion. In the presence of high glucose, fatty acids contribute partially to amplifying pathways of insulin secretion by further increasing mitochondrial activity in the islets of Langerhans. 相似文献
995.
Dr Niels Grabow David P. Martin Klaus‐Peter Schmitz Katrin Sternberg 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2010,85(6):744-751
Stents are structural implants with widespread clinical use in vascular intervention to re‐open stenotic vessels for the treatment of coronary artery disease and peripheral arterial occlusive disease. Apart from their mechanical function, current drug‐eluting stents (DES) utilize local drug delivery from a drug‐incorporated permanent polymer coating to prevent in‐stent restenosis. This delayed closure of the stented vessel is considered one of the major limitations of conventional bare metal stents (BMS). The long‐term safety of DES, however, is still under debate, with reported cases of delayed healing, late thrombosis and hypersensitivity demanding further evolution in this field. A promising approach to circumvent the limitations of first generation DES is the application of degradable polymer coatings in second generation DES, and fully absorbable polymer stents. From a materials and engineering perspective, this paper provides a mini‐review of current clinically relevant DES technology and recent advancements in the development of stents from degradable polymeric materials as an alternative to permanent BMS and DES. This review, includes work on degradable stents and coatings based on blends of polylactic acid and the microbially‐produced poly(4‐hydroxybutyrate). Copyright © 2009 Society of Chemical Industry 相似文献
996.
Christoph Brune Alex Sawatzky Martin Burger 《International Journal of Computer Vision》2011,92(2):211-229
Measurements in nanoscopic imaging suffer from blurring effects modeled with different point spread functions (PSF). Some
apparatus even have PSFs that are locally dependent on phase shifts. Additionally, raw data are affected by Poisson noise
resulting from laser sampling and “photon counts” in fluorescence microscopy. In these applications standard reconstruction
methods (EM, filtered backprojection) deliver unsatisfactory and noisy results. Starting from a statistical modeling in terms
of a MAP likelihood estimation we combine the iterative EM algorithm with total variation (TV) regularization techniques to
make an efficient use of a-priori information. Typically, TV-based methods deliver reconstructed cartoon images suffering
from contrast reduction. We propose extensions to EM-TV, based on Bregman iterations and primal and dual inverse scale space
methods, in order to obtain improved imaging results by simultaneous contrast enhancement. Besides further generalizations
of the primal and dual scale space methods in terms of general, convex variational regularization methods, we provide error
estimates and convergence rates for exact and noisy data. We illustrate the performance of our techniques on synthetic and
experimental biological data. 相似文献
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1000.
Continuous salt precipitation and separation from supercritical water. Part 2. Type 2 salts and mixtures of two salts 总被引:1,自引:0,他引:1
Martin Schubert 《The Journal of Supercritical Fluids》2010,52(1):113-11727
Using a continuously operated laboratory plant for the catalytic hydrothermal gasification of biomass featuring a supercritical water salt separator we investigated the separation performance of three different binary type 2 salt-water mixtures and three ternary salt-water mixtures that consisted either of two type 1 salts or two type 2 salts dissolved in water. It turned out that a concentrated salt brine could not be recovered at the salt separator for the binary type 2 salt-water mixtures of Na2CO3, Na2SO4, and K2SO4. These salts precipitate as solids from supercritical water and thus lead to salt deposits inside the salt separator vessel.The ternary mixtures of two type 1 salts dissolved in water (KH2PO4-K2HPO4-H2O and three different mixtures of NaNO3-K2CO3-water) exhibited a separation performance similar to the binary solutions of type 1 salts that were discussed in Part 1 of this article. However, the mixtures showed separation performances that were different from the corresponding single salt solutions.It was also possible to recover a concentrated brine when feeding solutions containing the two type 2 salts Na2CO3 and K2SO4. For these mixtures a certain amount of the type 1 salt K2CO3 might form in supercritical water leading to salt separation efficiencies up to 95% for these mixtures. 相似文献