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Comparative studies on storage cells in tardigrades during starvation and anhydrobiosis
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作者 Andy REUNER Steffen HENGHERR +1 位作者 Franz Brümmer Ralph O.SCHILL 《Current Zoology》 SCIE CAS CSCD 北大核心 2010年第2期259-263,共5页
The impact of starvation and anhydrobiosis on the number and size of the storage cells in the tardigrade species Milnesium tardigradum, Paramacrobiotus tonollii and Macrobiotus sapiens was investigated to gain more in... The impact of starvation and anhydrobiosis on the number and size of the storage cells in the tardigrade species Milnesium tardigradum, Paramacrobiotus tonollii and Macrobiotus sapiens was investigated to gain more insight on the energetic side of anhydrobiosis. Storage cells are free floating cells within the body cavity of tardigrades and are presumed to store and release energy in form of glycogen, protein and fat to maintain a constant nutrient regime for the other tissues. The body size of the animals was not correlated with the size of the storage cells, however, M. tardigradum the largest species analysed also had the largest storage cells. A reduction in the size of the storage cells is apparent in all three species after seven days of starvation. A seven-day period of anhydrobiosis leads to a decrease in cell size in M. tardigradum but not in P. tonollii and M. sapiens. Although M. sapiens was raised on green algae, and M. tardigradum and P. tonollii were fed with rotifers and nematodes this difference in nourishment was not reflected in the response of the storage cells to anhydrobiosis 展开更多
关键词 TARDIGRADA cryptobiosis Milnesium tardigradum Paramacrobiotus tonollii Macrobiotus sapiens
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Ab initio energetic study of oxide ceramics with rare-earth elements
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作者 Matvei Zinkevich Fritz Aldinger 《Rare Metals》 SCIE EI CAS CSCD 2006年第5期549-555,共7页
Ab initio energetic calculations based on the density functional theory (DFF) and the projector augmented wave method (PAW) for determining the polymorphisms of lanthanide sesquioxides Ln2O3 (where Ln = rare-eart... Ab initio energetic calculations based on the density functional theory (DFF) and the projector augmented wave method (PAW) for determining the polymorphisms of lanthanide sesquioxides Ln2O3 (where Ln = rare-earth element, Y, and Sc), LnMO3 perovskites (where M = AI and Ga), and Ln2B207 pyrochlores (where B = Ti, Zr, and Hf) were reported. The relative lattice stabilities agreed well with the critically assessed results or the experimental results except the C-type Ln2O3 with a cubic structure, for which the calculated total energies were considerably more negative. With the increase of the Ln^3+-cation radius, the polymorphic structures showed a degenerative tendency. The tendencies and quantities of the enthalpies of formation of the ternary oxide ceramics synthesized from their constituent binary oxides reasonably agreed with the available experimental results, and valuable thermodynamic properties were afforded to the compound, for which no experimental data is available. The enthalpies of formation of both perovskites and pyrochlores tend to become more negative with the increase of the Ln^3+-cation radius. 展开更多
关键词 rare earth oxide ceramics ab initio calculation lattice stability enthalpy of formation
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Ti掺杂ZnTe体材料的优化光致发光光谱 被引量:5
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作者 邵军 《物理学报》 SCIE EI CAS CSCD 北大核心 2003年第7期1743-1747,共5页
针对光致发光光谱法研究ZnTe :Ti的困难 ,对包括激发能量、激发功率与激发光斑大小、水汽干扰和测量温度等实验条件进行了细致的优化 .发现 :(1)低于ZnTe禁带宽度的激发能量能给出相对强的光致发光光谱 ;(2 )水汽干扰既影响谱线的相对... 针对光致发光光谱法研究ZnTe :Ti的困难 ,对包括激发能量、激发功率与激发光斑大小、水汽干扰和测量温度等实验条件进行了细致的优化 .发现 :(1)低于ZnTe禁带宽度的激发能量能给出相对强的光致发光光谱 ;(2 )水汽干扰既影响谱线的相对强度又增大谱线能量的测定误差 ;(3)相对强的激光聚焦有利于获得较好的光致发光光谱 .可靠地观察到位于 390 3.5和 390 5 .9cm- 1 能量位置处的零声子光致发光谱线 .根据两谱线的能量间距和相对强度随温度的变化关系 ,并借助于晶体场理论对四面体晶体场中 3d1 和 3d2 杂质离子能级的分析 ,该零声子光致发光谱线被界定为源于Ti3+ 的深能级跃迁 ,从而获得了Ti3+ 存在于Ⅱ 展开更多
关键词 Ti掺杂 ZnTe体材料 优化 光致发光光谱 半导体材料 碲化锌 钛掺杂
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Modeling slow deformation of polygonal particles using DEM 被引量:2
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作者 Andrés A. Pea Pedro G. Lind Hans J. Herrmann 《Particuology》 SCIE EI CAS CSCD 2008年第6期506-514,共9页
We introduce two improvements in the numerical scheme to simulate collision and slow shearing of irregular particles. First, we propose an alternative approach based on simple relations to compute the frictional conta... We introduce two improvements in the numerical scheme to simulate collision and slow shearing of irregular particles. First, we propose an alternative approach based on simple relations to compute the frictional contact forces. The approach improves efficiency and accuracy of the Discrete Element Method (DEM) when modeling the dynamics of the granular packing. We determine the proper upper limit for the integration step in the standard numerical scheme using a wide range of material parameters. To this end, we study the kinetic energy decay in a stress controlled test between two particles. Second, we show that the usual way of defining the contact plane between two polygonal particles is, in general, not unique which leads to discontinuities in the direction of the contact plane while particles move. To solve this drawback, we introduce an accurate definition for the contact plane based on the shape of the overlap area between touching particles, which evolves continuously in time. 展开更多
关键词 Granular media Discrete element method Slow deformation Contact forces
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Measurement of in-plane deformations of microsystems by digital holography and speckle interferometry(Invited Paper) 被引量:1
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作者 G. Pedrini J. Gaspar +1 位作者 O. Paul W. Osten 《Chinese Optics Letters》 SCIE EI CAS CSCD 2009年第12期1109-1112,共4页
The reliability of microsystems is an important issue and for their quality inspection, it is necessary to know the displacements or deformations due to the applied mechanical, thermal, or electrostatic loads. We show... The reliability of microsystems is an important issue and for their quality inspection, it is necessary to know the displacements or deformations due to the applied mechanical, thermal, or electrostatic loads. We show how interferometrical techniques like digital holography and speckle interferometry can be used for the measurement of in plane deformations of microsystems with nanometric accuracy and we give a description of the measurement uncertainties. 展开更多
关键词 Invited Paper Measurement of in-plane deformations of microsystems by digital holography and speckle interferometry
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An introduction to molecular spintronics
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作者 GOβ Karin 《中国科学:化学》 CAS CSCD 北大核心 2012年第6期881-881,共1页
We review the progress and future possibilities in the emerging area of molecular spintronics. We first provide an overview of the different transport regimes in which electronic nanodevices can operate, then briefly ... We review the progress and future possibilities in the emerging area of molecular spintronics. We first provide an overview of the different transport regimes in which electronic nanodevices can operate, then briefly overview the important characteristics of molecular magnetic materials that can be useful for application in spintronics and we eventually present several schemes to include such systems into spintronic nanodevices. We hightlight the importance of a chemical approach to the area, and in the last section we showcase some approaches to the creation of hybrids made of carbon nanostructures and molecular magnets, which are gaining increasing attention. 展开更多
关键词 分子磁性材料 自旋电子学 纳米器件 碳纳米结构 混合动力车 分子磁体
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Resolution enhancement in digital holographic microscopy with structured illumination
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作者 马骏 袁操今 +2 位作者 司徒国海 Giancarlo Pedrini Wolfgang Osten 《Chinese Optics Letters》 SCIE EI CAS CSCD 2013年第9期28-32,共5页
We present a digital holographic microscope wherein the sample is illuminated by structured light to enable the capture of additional object spatial frequencies. Reconstructed images with increased spatial resolution ... We present a digital holographic microscope wherein the sample is illuminated by structured light to enable the capture of additional object spatial frequencies. Reconstructed images with increased spatial resolution are obtained by separating and synthesizing bandwidths of different frequency regions in the Fourier domain. The theoretical analysis and experimental results are presented. 展开更多
关键词 OPTICS PHYSICS
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