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排序方式: 共有537条查询结果,搜索用时 15 毫秒
41.
Ramona M. Grigorescu Paul Ghioca Lorena Iancu Madalina E. Grigore Rodica-Mariana Ion Cristian-Andi Nicolae Raluca Gabor Mircea I. Filipescu Maria Rapa Roxana D. Trusca Marius Ghiurea 《应用聚合物科学杂志》2020,137(5):48329
The reuse of plastic components of waste electrical and electronic equipment (WEEE) is an important concern both for environmental issues and to preserve the material resources, with minimum energy consumption. Considering that polystyrene fraction was reported as approximate 80% of the total amount of WEEE plastic, this article aims to evaluate the recycling of this fraction, without separation by components, by melt compounding with styrene-butadiene block-copolymer (SBS) and hydrogenated and maleinized SBS, the blend of the two elastomers acting both as an impact modifier and compatibilizer. The composites are characterized by mechanical analysis, impact tests, dynamic mechanical analysis, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, energy dispersive X-ray analysis, and X-ray diffraction. The recycling conditions of the polystyrene fraction as composites without eliminating the WEEE additives for improved UV and flame resistance, with physical mechanical properties comparable to those of high-impact polystyrene resulted from the study. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48329. 相似文献
42.
Marius Eugen Ciurea Ada Maria Georgescu Stefana Oana Purcaru Stefan-Alexandru Artene Ghazaleh Hooshyar Emami Mihai Virgil Boldeanu Daniela Elise Tache Anica Dricu 《International journal of molecular sciences》2014,15(5):8169-8185
Almost all tumors are composed of a heterogeneous cell population, making them difficult to treat. A small cancer stem cell population with a low proliferation rate and a high tumorigenic potential is thought to be responsible for cancer development, metastasis and resistance to therapy. Stem cells were reported to be involved in both normal development and carcinogenesis, some molecular mechanisms being common in both processes. No less controversial, stem cells are considered to be important in treatment of malignant diseases both as targets and drug carriers. The efforts to understand the role of different signalling in cancer stem cells requires in depth knowledge about the mechanisms that control their self-renewal, differentiation and malignant potential. The aim of this paper is to discuss insights into cancer stem cells historical background and to provide a brief review of the new therapeutic strategies for targeting cancer stem cells. 相似文献
43.
Ramona Mihaela Matran Anca-Irina Galaction Alexandra Cristina Blaga Marius Turnea 《Chemical Engineering Communications》2016,203(5):666-675
The distribution of mixing in a split-cylinder gas-lift bioreactor has been investigated for suspensions of immobilized Yarrowia lipolytica cells with particles diameter varying between 3 and 4.2 mm. The results indicated important variation of mixing time on the height of riser or downcomer, as well as different behavior of suspensions flows in these two regions. Therefore, for the riser, the mixing efficiency increases from its bottom to the top, allowing the biocatalyst particles with intermediate size (3.6-mm diameter) reaching the most intense circulation of suspension. The analysis of the suspension flow in the downcomer region revealed that the intermediate positions are associated with the highest mixing mainly for the largest immobilized yeast particles (4.2-mm diameter). In both cases, the influence of aeration on turbulence extent is positive only for air superficial velocity up to 1.05–1.35 × 10?3 m/s, the magnitude of this effect being correlated with the biocatalyst size and position on the riser or downcomer. By means of the experimental data, mathematical correlations for mixing time have been proposed for each circulation region, taking into consideration both the operational parameters and the distance from the bioreactor bottom. These equations offer a good concordance with the experiment, the average deviation being of 5.82% for the riser and 6.06% for the downcomer zone. 相似文献
44.
Lukas Hoehr Felix Reichmann Marius Berndt Johannes Sackmann Norbert Kockmann Werner Karl Schomburg 《化学工程与技术》2019,42(5):971-979
Microreactors offer several advantages compared to the industrial scale when developing new chemical processes. Especially the production and investment costs are low if polymer microreactors are generated by ultrasonic processes. In order to observe the chemical reaction and the flow configuration, these microreactors need to be optically transparent, mechanically stable, and chemically inert to several reagents. The manufacturing process of a transparent polymer plate reactor with a chemically inert surface coating by ultrasonic fabrication is described. Experimental characterization of the microreactors showed that they are leak tight up to a pressure difference of at least 300 kPa and the mixing times are in the range of milliseconds. 相似文献
45.
46.
Sampling Archimedean copulas 总被引:2,自引:0,他引:2
Marius Hofert 《Computational statistics & data analysis》2008,52(12):5163-5174
The challenge of efficiently sampling exchangeable and nested Archimedean copulas is addressed. Specific focus is put on large dimensions, where methods involving generator derivatives are not applicable. Additionally, new conditions under which Archimedean copulas can be mixed to construct nested Archimedean copulas are presented. Moreover, for some Archimedean families, direct sampling algorithms are given. For other families, sampling algorithms based on numerical inversion of Laplace transforms are suggested. For this purpose, the Fixed Talbot, Gaver Stehfest, Gaver Wynn rho, and Laguerre series algorithm are compared in terms of precision and runtime. Examples are given, including both exchangeable and nested Archimedean copulas. 相似文献
47.
Prof. Dr. Michael Lorenz Dr. Philipp Storm Stephan Gierth Dr. Susanne Selle Dr. Holger von Wenckstern Prof. Dr. Marius Grundmann 《化学,工程师,技术》2023,95(11):1786-1793
The long-term stability of the optically transparent p-type semiconductor copper iodide is a current challenge. The electrical conductivity of CuI thin films depends critically on the environmental impact. Al2O3 cappings enhance the stability considerably. Systematic studies on Al2O3/CuI heterostructures in dependence of the N2/O2 growth pressure show the electrical conductivity of the CuI films being determined by the oxygen diffusion through Al2O3 und CuI. Oxygen seems to be a dominating acceptor in CuI. We traced the diffusion of atmospheric oxygen into CuI with 18O isotopes. 相似文献
48.
49.
Marius Tchonang Pokaha Dawid E. Serfontein 《Journal of Nuclear Science and Technology》2018,55(8):843-849
In a previous study using a mixture of thorium and 20 a/o% LEU at 16 gram per fuel sphere heavy metal loading and adjusting the effective fuel enrichment to produce the same amount of cumulative energy per fuel sphere as with the 10 a/o% Low Enriched Uranium (LEU), the maximum Depressurized Loss Of Forced Cooling (DLOFC) temperature was reduced from 2273 to 1925 °C and 1811 °C for a symmetric and asymmetric core, respectively using an once-through-then-out (OTTO) fuelling scheme. This article presents an additional strategy for reducing the maximum DLOFC temperature by placing an optimized distribution of neutron poisons in the central reflector. This strategy produced maximum DLOFC temperatures of 1509 and 1448 °C for the symmetric and the asymmetric cores, respectively. These results are impressive as it means that the less complicated OTTO cycle with its lower capital cost achieved the same cumulative energy produced per fuel sphere than the standard six-pass refuelling scheme and that at substantially lower maximum DLOFC temperatures. Both the addition of the neutron poisons to the central reflector and the creation of a radially asymmetric core resulted in lower burn-ups that had to be reversed by increasing the enrichment of the fuel. 相似文献
50.
Stefan Klein Josien P. W. Pluim Marius Staring Max A. Viergever 《International Journal of Computer Vision》2009,81(3):227-239
We present a stochastic gradient descent optimisation method for image registration with adaptive step size prediction. The
method is based on the theoretical work by Plakhov and Cruz (J. Math. Sci. 120(1):964–973, 2004). Our main methodological contribution is the derivation of an image-driven mechanism to select proper values for the most
important free parameters of the method. The selection mechanism employs general characteristics of the cost functions that
commonly occur in intensity-based image registration. Also, the theoretical convergence conditions of the optimisation method
are taken into account. The proposed adaptive stochastic gradient descent (ASGD) method is compared to a standard, non-adaptive
Robbins-Monro (RM) algorithm. Both ASGD and RM employ a stochastic subsampling technique to accelerate the optimisation process.
Registration experiments were performed on 3D CT and MR data of the head, lungs, and prostate, using various similarity measures
and transformation models. The results indicate that ASGD is robust to these variations in the registration framework and
is less sensitive to the settings of the user-defined parameters than RM. The main disadvantage of RM is the need for a predetermined
step size function. The ASGD method provides a solution for that issue. 相似文献