Total and subcellular distribution of trace elements in the liver of a mother-fetus pair of Dall's porpoises (Phocoenoides dalli)

Total and subcellular hepatic Zn, Cu, Se, Mn, V, Hg, Cd, and Ag were determined in a mother-fetus pair of Dall's porpoises (Phocoenoides dalli). Except for higher fetal Cu concentration, all maternal elements were higher. Elements existed mostly in the cytosol of both animals except in the case of maternal Ag in the microsome and fetal Cu and Ag in the nuclei and mitochondria. In the maternal cytosol, Zn, Mn, Hg, and Ag were present in the high-molecular-weight substances (HMW); Se and V were present in the low-molecular-weight substances (LMW); Cu and Cd were mostly sequestered by metallothionein (MT). In the fetal cytosol, Zn, Se, Mn, Hg, Cd, and Ag were present in the HMW and V in the LMW, while Cu and Ag were mostly associated with MT. MT isoforms were characterized using the HPLC/ICP-MS. Two and four obvious peaks appeared in the maternal and fetal MT fractions, respectively. The highest elemental ion intensities were at a retention time of 7.8 min for the mother, and for the fetus the peak elemental ion intensities occurred at a retention time of 4.3 min, suggesting that different MT isoforms may be involved in elemental accumulation in maternal and fetal hepatocytosols. (C) 2003 Elsevier Ltd. All rights reserved.

New observations on the pressure dependence of luminescence from Eu2+-doped MF2 (M = Ca, Sr, Ba) fluorides

The luminescence from Eu2+ ions in MF2 (M = Ca, Sr, Ba) fluorides has been investigated under the pressure range of 0-8 GPa. The emission band originating from the 4f(6)5d(1) -> 4f(7) transition of Eu2+ ions in CaF2 and SrF2 shows the red-shift as increasing pressure with pressure coefficients of -17 meV/GPa for CaF2 and -18 meV/GPa for SrF2. At atmospheric pressure, the emission spectrum of BaF2:Eu2+ comprises two peaks at 2.20 and 2.75 eV from the impurity trapped exciton (ITE) and the self-trapped exciton (STE), respectively. As the pressure is increased, both emission peaks shift to higher energies, and the shifting rate is slowed by the phase transition from the cubic to orthorhombic phase at 4 GPa. Due to the phase transition at 4-5 GPa pressure, the ITE emission disappears gradually, and the STE emission is gradually replaced by the 4f(6)5d(1) -> 4f(7) transition of Eu2+. Above 5 GPa, the pressure behavior of the 4f(6)5d(1) -> 4f(7) transition of EU2+ in BaF2: EU2+ is the same as the normal emission of Eu2+ in CaF2 and SrF2 phosphors.

Highly coherent solid-state quantum bit from a pair of quantum dots

In this letter, we propose a scheme to buildup a highly coherent solid-state quantum bit (qubit) from two coupled quantum dots. Quantum information is stored in the state of the electron-hole pair with the electron and hole located in different dots, and universal quantum gates involving any pair of qubits are realized by effective coupling interaction via virtually exchanging cavity photons. (C) 2002 American Institute of Physics.

Crystallographic and magnetic properties of nitride R3Fe29-xCrxN4 (R = Y, Ca, Nd, Sm, Gd, Tb, and Dy)

A systematic investigation of crystallographic and magnetic properties of nitride R3Fe29-xCrxN4 (R=Y, Ce, Nd, Sm, Gd, Tb, and Dy) has been performed. The lattice constants and unit cell volume decrease with increasing rare earth atomic number from Nd to Dy, reflecting the lanthanide contraction. After nitrogenation the relative volume expansion of each nitride is around between 5% and 7%. The nitrogenation results in a good improvement in the Curie temperature, the saturation magnetization and anisotropy fields at 4.2 K, and room temperature for R3Fe29-xCrxN4. Magnetohistory effects of R3Fe29-xCrxN4 and R3Fe29-xCrx (R=Nd and Sm) are observed in a low field of 0.04 T. First order magnetization process occurs in Sm3Fe24.0Cr5.0N4 in magnetic fields of 2.8 T at 4.2 K. After nitrogenation, the easy magnetization direction of Sm3Fe24.0Cr5.0 is changed from the easy-cone structure to the uniaxial. The good intrinsic magnetic properties of Sm3Fe24.0Cr5.0N4 make this compound a hopeful candidate for new high-performance hard magnets. (C) 1998 American Institute of Physics.

一种入侵容忍的CA���案

CA(certificate authority)是PKI中的关键设施.CA���私有密钥一旦泄露,该CA���发的所有证书就只能全部作废.保护在线服务CA���私钥也就成为一个非常重要的课题.不是从保护系统或检测入侵出发来保证CA���安全,而是确保当少数部件被攻击或占领后,CA���统的机密信息并没有暴露.通过将私钥分发给不同的部件,并保证任何一个在线的部件无法恢复CA���私钥,从而保护了CA���钥的保密性.

一种针对弹性CA���分布式密钥产生方案

弹性CA���一种使用入侵容忍技术保护CA���钥的CA���统，它采用了新的私钥分割方法加强了系统的安全性，但其使用的密钥分发中心却不利于CA���钥安全．分布式密钥产生方案就是在传统的弹性CA���案的基础上取消了密钥分发中心，使用分布式的密钥产生和分割机制，从而保证了在CA���始化和整个运行过程中，任意t-1（t为门限值）台服务器都不可能窃得CA���钥，大大加强了CA���统安全．

Novel moving-corner-cube-pair interferometer

A novel type of moving-corner-cube-pair interferometer is presented, and its principle and properties are studied. It consists of two moving corner cubes fixed together back to back as a single moving part (the moving-corner-cube-pair), four fixed plane mirrors and one beamsplitter. The optical path difference (OPD) is created by the straight reciprocating motion of the moving-corner-cube-pair, and the OPD value is eight times the physical shift value of the moving-corner-cube-pair. This novel type of interferometer has no tilt and shearing problems. It is almost ideal for the very-high-resolution infrared spectrometers.

Principle of the moving-mirror-pair interferometer and the tilt tolerance of the double moving mirror

A novel type of interferometer, the moving-mirror-pair interferometer, is presented, and its principle and properties are studied. The new interferometer is built with three flat mirrors, which include two flat moving mirrors fixed as a single moving part by a rigid structure and one flat fixed mirror. The optical path difference (OPD) is obtained by the straight reciprocating motion of the double moving mirror, and the OPD value is four times the physical shift value of the double moving mirror. The tilt tolerance of the double moving mirror of the novel interferometer is systematically analyzed by means of modulation depth and phase error. Where the square aperture is concerned, the formulas of the tilt tolerance were derived. Due to the novel interferometer's large OPD value and low cost, it is very applicable to the high-spectral-resolution Fourier-transform spectrometers for any wavenumber region from the far infrared to the ultraviolet. (C) 2008 Optical Society of America.

Construction of 2-D directional filter bank by cascading checkerboard-shaped filter pair and CMFB

In this paper, we propose a new approach to construct a 2-dimensional (2-D) directional filter bank (DFB) by cascading a 2-D nonseparable checkerboard-shaped filter pair and 2-D separable cosine modulated filter bank (CMFB). Similar to diagonal subbands in 2-D separable wavelets, most of the subbands in 2-D separable CMFBs, tensor products of two 1-D CMFBs, are poor in directional selectivity due to the fact that the frequency supports of most of the subband filters are concentrated along two different directions. To improve the directional selectivity, we propose a new DFB to realize the subband decomposition. First, a checkerboard-shaped filter pair is used to decompose an input image into two images containing different directional information of the original image. Next, a 2-D separable CMFB is applied to each of the two images for directional decomposition. The new DFB is easy in design and has merits: low redundancy ratio and fine directional-frequency tiling. As its application, the BLS-GSM algorithm for image denoising is extended to use the new DFBs. Experimental results show that the proposed DFB achieves better denoising performance than the methods using other DFBs for images of abundant textures. (C) 2008 Elsevier B.V. All rights reserved.

Cyanex302及CA-12萃取稀土动力学的研究

随着萃取技术的不断发展，人们日益要求更加深入的了解萃取过程的机制及其动力学特性。以便有效地控制和强化萃取过程，提高萃取效率，或者利用萃取动力学的差异来实现某些分离嘴过程。尽管许多萃取过程进行得很快，但是人们也发现不少的金属鳌合物萃取体系，其萃取过程相当缓慢。因而这类体系的萃取机制和萃取动力学问题已日益引人注目。除此而外，在设计，放大或改进萃取设备时，研究和掌握有关萃取过程的动力学规律也有十分重要意义。在本文中主要对稀土萃取动力学进行了研究，得到主要结果如下：1．研究了硫代有机磷酸Cyan.ex302萃取饵的动力学。通过测定各种萃取条件对萃取速率的影响，获得了萃取速率方程，并讨论了萃取的控制过程。实验发现萃取剂中的杂质对萃取具有较大的加速作用，这对工业生产具有一定的实际意义。2.用两相滴定法测定了两种新合成的J梭酸萃取剂CA-12和CA-100的某些重要的物理常数。这将有助于深入研究它们的萃取性质及机理。3．用层流恒界面池研究了CA-12萃取La, Gd,Er, Yb和Y的动力学。考察了各种因素对萃取速率的影响，获得了它们的萃取速率方程，实验发现了它们的萃取控速步骤并推测了其萃取机理。4．研究了HEHEHP对CA-12萃取Yb和Y的动力学的影响。实验发现在CA���12中加入少量的HEHEHP后，萃取活化能显著降低，萃取速率明显加快。由于加入HEHEHP后，萃取Yb的活化能的降低要比萃取Y的活化能降低的程度大'，所以使Yb和Y的萃取分离因素加大。5．用两相滴定法研究了HEHEHP萃取铭的机理，CA-12萃取稀土及其相关离子的机理。并计算了它们相应的平衡常数。