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排序方式: 共有713条查询结果,搜索用时 15 毫秒
21.
Saeed Ahmadi Vaselabadi David Shakarisaz Paul Ruchhoeft Joseph Strzalka Gila E. Stein 《Journal of Polymer Science.Polymer Physics》2016,54(11):1074-1086
Grazing‐incidence X‐ray scattering (GIXS) is widely used to analyze the crystallinity and nanoscale structure in thin polymer films. However, ionizing radiation will generate free radicals that initiate crosslinking and/or chain scission, and structural damage will impact the ordering kinetics, thermodynamics, and crystallinity in many polymers. We report a simple methodology to screen for beam damage that is based on lithographic principles: films are exposed to patterns of X‐ray radiation, and changes in polymer structure are revealed by immersing the film in a solvent that dissolves the shortest chains. The experiments are implemented with high throughput using the standard beam line instrumentation and a typical GIXS configuration. The extent of damage (at a fixed radiation dose) depends on a range of intrinsic material properties and experimental variables, including the polymer chemistry and molecular weight, exposure environment, film thickness, and angle of incidence. The solubility switch for common polymers is detected within 10–60 s at ambient temperature, and we verified that this first indication of damage corresponds with the onset of network formation in glassy polystyrene and a loss of crystallinity in polyalkylthiophenes. Therefore, grazing‐incidence X‐ray “patterning” offers an efficient approach to determine the appropriate data acquisition times for any GIXS experiment. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1074–1086 相似文献
22.
We give a closed formula for topological K-theory of the homogeneous space N/, where is the standard integer lattice in the simply connected Heisenberg Lie group N of dimension 2n+1, n
. The main tools in our calculations are obtained by computing diagonal forms for certain incidence matrices that arise naturally in combinatorics. 相似文献
23.
Olaf Bröcker 《Journal of Geometry》2002,75(1-2):46-60
For M?bius planes Schaeffer [9] has proved that all seven
point degenerations of Miquel's Theorem characterize miquelian M?bius
planes. For Laguerre planes we have several degenerations of Miquel's
Theorem with eight and seven points. We prove that all except one of
these degenerations characterize miquelian Laguerre planes. The
remaining degeneration characterizes elation Laguerre planes.
Received 14 September 2001; revised 1 September 2002. 相似文献
24.
报道了时间分辨的三通道软X射线光谱仪研制工作,重点介绍了研制的三通道能谱仪的工作原理以及210 eV,420 eV和900 eV三个能区的设计参数,谱仪在上海神光Ⅱ高功率激光器三倍频实验中进行了多次实时考核,取得较好实验结果,将多道平面镜、滤光片成功配接于高时间分辨X射线条纹相机上,使该谱仪在亚千电子伏能区内,可同时进行三个波段软X射线的时间和空间分辨测量,提供的实验结果也表明:X射线平面镜结合滤光片的分光技术可应用于高时间分辨的X射线条纹相机上,从而获得高达10 ps的时间分辨.
关键词:
软X射线条纹相机
平面镜
滤光片
掠入射 相似文献
25.
26.
Natália D.D. CararetoMariana C. Costa Marlus P. RolembergM.A. Krähenbühl Antonio J.A. Meirelles 《Fluid Phase Equilibria》2011,303(2):191
This study is part of a work developed in the author's research group on the solid-liquid equilibrium of fatty substances. The phase diagrams of the following fatty alcohol systems were determined by differential scanning calorimetry (DSC): 1-octanol + 1-dodecanol, 1-octanol + 1-tetradecanol, 1-decanol + 1-tetradecanol, 1-decanol + 1-hexadecanol and 1-dodecanol + 1-octadecanol. The liquidus lines of three of these systems were previously reported in the literature but the other two systems were never published. Moreover other transitions, in addition to the eutectic temperature, were also detected in all the systems. A region of solid solution at the extreme left of the phase diagrams was observed for all the binary mixtures. Polarized light microscopy was used to complement the characterization of the systems for a full grasp of the phase diagrams. The solid-liquid equilibrium was modeled using the Margules 2-suffix, Margules 3-suffix, NRTL and UNIFAC Dortmund equations. 相似文献
27.
Haydar Aygün Keith Attenborough Walter Lauriks Philip A. Rubini Christian M. Langton 《Applied Acoustics》2011,(7):458-463
Comparisons between predictions of a Biot-Allard model allowing for angle-dependent elasticity and angle-and-porosity dependent tortuosity and transmission data obtained at normal incidence on water-saturated replica bones are extended to oblique incidence. The model includes two parameters which are adjusted for best fit at normal incidence. Using the same parameter values, it is found that predictions of the variation of transmitted waveforms with angle through two types of bone replica are in reasonable agreement with data despite the fact that scattering is not included in the theory. 相似文献
28.
Achiya Dax 《Mathematical Programming》1986,36(1):72-80
Thekey problem of the Euclidean multifacility location (EMFL) problem is to decide whether a givendead point is optimal. If it is not optimal, we wish to compute a descent direction. This paper extends the optimality conditions of
Calamai and Conn and Overton to the case when the rows of the active constraints matrix are linearly dependent. We show that
linear dependence occurs wheneverG, the graph of the coinciding facilities, has a cycle. In this case the key problem is formulated as a linear least squares
problem with bounds on the Euclidean norms of certain subvectors. 相似文献
29.
P. Schmid K. Uran F. Macherey M. Ebert H.-J. Ullrich D. Sommer F. Friedel 《Analytical and bioanalytical chemistry》2009,393(8):1863-1870
The formation of Fe–Zn intermetallic compounds, as relevant in the commercial product galvannealed steel sheet, was investigated
by scanning electron microscopy and different methods of X-ray diffraction. A scanning electron microscope with high resolution
was applied to investigate the layers of the galvannealed coating and its topography. Grazing incidence X-ray diffraction
(GID) was preferred over conventional Bragg–Brentano geometry for analysing thin crystalline layers because of its lower incidence
angle α and its lower depth of information. Furthermore, in situ experiments at an environmental scanning electron microscope (ESEM)
with an internal heating plate and at an X-ray diffractometer equipped with a high-temperature chamber were carried out. Thus,
it was possible to investigate the phase evolution during heat treatment by X-ray diffraction and to display the growth of
the ζ crystals in the ESEM. 相似文献
30.
本文用现时寿命表中计算平均寿命的基本假定,讨论估计横向数据的累加死亡率问题.本公式也适用于累加发病率及任何非医学领域中某种指标的累加发生率等问题.文中使用了一个脑血管病实例. 相似文献