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排序方式: 共有2439条查询结果,搜索用时 15 毫秒
931.
Prof. Dr.‐Ing. Detleff Schermer Dr.‐Ing. Udo Joachim Meyer Marjana Lutman Petra Triller 《Mauerwerk》2019,23(6):378-386
The paper presents results of a series of 6 in‐plane shear tests on storey‐height clay unit masonry panels [1] with thin‐layer mortar, carried out in addition to previous test campaigns [2], [3], and [4]. The walls were constructed with unfilled thermally insulating clay units with a thermal conductivity of λ = 0.09 W/(m · K). The current design rules for clay unit masonry according to DIN EN 1996‐1‐1/NA [5] are conservative compared to the presented test results for thermally insulating clay unit masonry. 相似文献
932.
The Karlsruhe Tritium Neutrino Experiment — The Word's Most Accurate Scale Scale The mass of the neutrino is one of the big open questions in particle physics, astrophysics and cosmology. The Karlsruhe TRItium Neutrino (KATRIN) experiment aims to measure the neutrino mass with a sensitivity of 200 meV/c2. This corresponds to an improvement by a factor of 10 compared to predecessor experiments. In order to achieve this improvement, the KATRIN experiment needs to solve technical challenges from various technical fields such as high voltage, cryogenics or vacuum technology. A considerable challenge is the operation of a large spectrometer with a volume of 1240 m3 in a pressure regime of 10?11 mbar. 相似文献
933.
Stefan Kuhn Andreas Herrmann Joachim Hein Malte C. Kaluza Christian Rüssel 《Journal of Materials Science》2013,48(22):8014-8022
This paper reports on the effect of the chemical composition on the glass structure, the coefficients of thermal expansion and the fluorescence properties of Sm3+-doped La2O3–Al2O3–SiO2-glasses. The silica concentration was varied between 50 and 70 mol% and the La2O3:Al2O3 ratio between 50:50 and 30:70. The glass formation and the densities are evaluated and FTIR reflectance spectra, coefficients of thermal expansion and fluorescence lifetimes are determined. It is shown that high SiO2 concentrations and low La2O3:Al2O3 ratios result in relatively high fluorescence lifetime (2.19 ms, 4G5/2) and low coefficients of thermal expansion (4.6 × 10?6/K). The coefficients of thermal expansion and the fluorescence lifetimes show a linear dependency on the ratio LaO3/2/(AlO3/2 + SiO2). 相似文献
934.
The use of fully synthetic polymers as a liquid artificial vitreous body replacement (LAVR) was already considered, but yet none of these polymers have proven to be successful in long term retention in the vitreous cavity due to inadequate biocompatibility and fast biodegradation. Our novel cross‐linked polyelectrolyte as a potential intraocular endotamponade shows an innovative concept of thermoresponsive behavior proposed for the first time in ophthalmologic surgery. The polyelectrolyte has been elaborated via a three‐step procedure by combining classical synthetic protocols and microwave technique. We observed that the polyelectrolyte comprising sodium 2‐acrylamido‐2‐methylpropane sulfonate and acrylic functionalized poly(N‐isopropylacrylamide) macromonomer with glycerol dimethacrylate as cross‐linker displays a noticeable thermosensitive behavior. It exhibits enhancement of shear viscosity at physiological temperatures without phase separation. First in vitro experiments on a retinal ganglion cell line (RGC‐5) present a promising biocompatibility without harmful effects. Cell viability, proliferation rate, and inflammatory cascade (COX‐2 and iNOS expression) were not affected. 相似文献
935.
Carbon‐Coated Li3VO4 Spheres as Constituents of an Advanced Anode Material for High‐Rate Long‐Life Lithium‐Ion Batteries 下载免费PDF全文
Laifa Shen Shuangqiang Chen Joachim Maier Yan Yu 《Advanced materials (Deerfield Beach, Fla.)》2017,29(33)
Lithium‐ion batteries are receiving considerable attention for large‐scale energy‐storage systems. However, to date the current cathode/anode system cannot satisfy safety, cost, and performance requirements for such applications. Here, a lithium‐ion full battery based on the combination of a Li3VO4 anode with a LiNi0.5Mn1.5O4 cathode is reported, which displays a better performance than existing systems. Carbon‐coated Li3VO4 spheres comprising nanoscale carbon‐coating primary particles are synthesized by a morphology‐inheritance route. The observed high capacity combined with excellent sample stability and high rate capability of carbon‐coated Li3VO4 spheres is superior to other insertion anode materials. A high‐performance full lithium‐ion battery is fabricated by using the carbon‐coated Li3VO4 spheres as the anode and LiNi0.5Mn1.5O4 spheres as the cathode; such a cell shows an estimated practical energy density of 205 W h kg?1 with greatly improved properties such as pronounced long‐term cyclability, and rapid charge and discharge. 相似文献
936.
Product design is a cutting-edge area of research. Over the last few years, many papers have been presented dealing with product design. The review focuses on processing of crystalline solids with a particular filed of application in mind and shows how crystallization can be used as tool to generate materials with particular properties and how to tailor these properties by crystallization. The fact that crystallization is a tool for product design will be highlighted by 4 selected examples, dealing with roughness and shelf life of fertilizer granules (case 1 and 2), with micro container as carrier system and, finally, with an alternative tablet forming technique for heat sensitive materials. 相似文献
937.
Alice Müller-Leonhardt Shannon G. Mitchell Joachim Vogt Tim Schürmann 《Accident; analysis and prevention》2014
In complex systems, such as hospitals or air traffic control operations, critical incidents (CIs) are unavoidable. These incidents can not only become critical for victims but also for professionals working at the “sharp end” who may have to deal with critical incident stress (CIS) reactions that may be severe and impede emotional, physical, cognitive and social functioning. These CIS reactions may occur not only under exceptional conditions but also during every-day work and become an important safety issue. In contrast to air traffic management (ATM) operations in Europe, which have readily adopted critical incident stress management (CISM), most hospitals have not yet implemented comprehensive peer support programs. This survey was conducted in 2010 at the only European general hospital setting which implemented CISM program since 2004. The aim of the article is to describe possible contribution of CISM in hospital settings framed from the perspective of organizational safety and individual health for healthcare professionals. Findings affirm that daily work related incidents also can become critical for healthcare professionals. Program efficiency appears to be influenced by the professional culture, as well as organizational structure and policies. Overall, findings demonstrate that the adaptation of the CISM program in general hospitals takes time but, once established, it may serve as a mechanism for changing professional culture, thereby permitting the framing of even small incidents or near misses as an opportunity to provide valuable feedback to the system. 相似文献
938.
Mechanistic and molecular investigations on stabilization of horseradish peroxidase C 总被引:2,自引:0,他引:2
Schmidt A Schumacher JT Reichelt J Hecht HJ Bilitewski U 《Analytical chemistry》2002,74(13):3037-3045
The enzyme horseradish peroxidase (HRP) shows a decreasing activity when the enzyme's substrate hydrogen peroxide is present with the degree of inactivation being dependent on the incubation time and the hydrogen peroxide concentration. Incubation times of some minutes do not inactivate the enzyme independent of the H2O2 concentration. After several hours, only 50% of the activity is found for a medium H2O2 excess, and a >100-fold excess of H2O2 completely inactivates the enzyme. Polymeric additives, in particular Gafquat, lead to higher residual activities, whereas stabilizers, such as aminopyrine, preserve the full activity. Circular dichroism (CD) measurements reveal that the enzyme structure remains more or less unchanged when hydrogen peroxide is added. Only when a 1000-fold excess of hydrogen peroxide is present are structural changes observed. UV spectra highlight that the heme group in the enzyme is affected by hydrogen peroxide in a first step. Without any prolonged incubation, a decrease of the Soret band to approximately 50% is found for low hydrogen peroxide concentrations (HRP/H2O2 from 1:1 to 1:100). Higher H2O2 concentrations lead to the formation of catalytically inactive HRP forms. Preincubation of Gafquat, which is a copolymer from vinylpyrrolidone and derivatized methyl methacrylate, with hydrogen peroxide shifts the influence of hydrogen peroxide to higher concentrations, the shift being dependent on the Gafquat concentration. This effect is not observed for other polymers, such as dextrans, but it is also found for the stabilizer aminopyrine. Extended incubation times (24 h) of HRP together with H2O2, however, lead to an at least partial recovery of the Soret band for lower H2O2 concentrations (H2O2/HRP from 1:1 to 1:100). When hydrogen peroxide is used in a >100 fold excess, the heme group is irreversibly destroyed, and even the characteristic band of cpd III is not found. Here, the presence of Gafquat only reduces the degree of destruction. Computer modeling of the interaction between the polymers and the enzyme shows no specific binding sites for the functional groups of the vinylpyrrolidone-methacrylate copolymer Gafquat or of DEAE-dextran on the enzyme, whereas for the only activating polymer, polyethylenimine clustering of binding sites is observed. 相似文献
939.
It is shown that for Bi2Sr2CaCu2O8+ the quantitative correlation between charge-carrier density, temperature, and oxygen content of the surrounding atmosphere and dopant concentration can be understood with the help of a simple defect model that relies essentially on a significant degree of defect electron trapping. This is consistent with high-temperature Hall effect measurements at different oxygen partial pressures. In addition, electrochemical experiments allow the determination of oxygen diffusion coefficients and their correlation with the defect model. The influences of anisotropy and micro structure are also discussed. The results are interpreted in the context of earlier work on YBa2Cu3O6+ and (La, Sr)2CuO4+. 相似文献
940.
Mohrdieck C Dalmas F Arzt E Tharmann R Claessens MM Bausch AR Roth A Sackmann E Schmitz CH Curtis J Roos W Schulz S Uhrig K Spatz JP 《Small (Weinheim an der Bergstrasse, Germany)》2007,3(6):1015-1022
The cytoskeleton is a complex polymer network that plays an essential role in the functionality of eukaryotic cells. It endows cells with mechanical stability, adaptability, and motility. To identify and understand the mechanisms underlying this large variety of capabilities and to possibly transfer them to engineered networks makes it necessary to have in vitro and in silico model systems of the cytoskeleton. These models must be realistic representatives of the cellular network and at the same time be controllable and reproducible. Here, an approach to design complementary experimental and numerical model systems of the actin cytoskeleton is presented and some of their properties discussed. 相似文献