Ca 2+对叶绿体膜流动性及光系统II叶绿素蛋白质复合物的影响

通过实验我们证明Ca2+对叶绿体膜的流动性，对PS I和PS II叶绿素蛋白质复合物的相对含量，以及PS I和PS II的多肽均有影响。 Ca2+对叶绿体膜表层的流动性影响不大，但降低了叶绿体膜深层脂质分子的流动性。从另一个角度阐明了Ca2+抑制光能从PS II向PS I传递的机制。 Ca2+可使PS I的21，23，110KD的多肽转移至PS II，LHCP1和LHCP2中的CF1的两个亚基（55，60KD）转至CPa和LHCP3，从而增加了PS II的捕光截面，引起激发能在两个系统之间的分配的改变。 用免疫学方法可以证明CPIa2和LHCP2的Ab为复合抗体，CPIa1的Ab为单抗，我们可以推测向日葵的不同叶绿素蛋白质复合物具有同源性。

Transport properties of Ca-doped YBCO coated conductors

The authors have doped RABiTS coated conductor tapes with Ca in an attempt to enhance the transport properties. By diffusing Ca into the YBCO film from a CaZrO3 overlayer, the authors have been able to preferentially dope the grain boundaries of the superconductor. Hence it has been possible to obtain doped tapes which do not have a significantly degraded T-c. The authors have measured the critical currents of doped and undoped samples over a wide range of temperature, magnetic field, and magnetic field angle in order to study the effect of Ca on the grain boundaries. The authors find that doping using short anneal times produces enhanced critical currents in large magnetic fields.

Comment on "Acoustic chaos in a duct with two separate sound sources" [J. Acoust. Soc. Am. 110, 120-126 (2001)] (L)

In a paper published in this journal in 2001 by Dong [W. G. Dong, X. Y. Huang, and Q. L. Wo, J. Acoust. Soc. Am. 110, 120-126 (2001)] it was claimed that acoustic chaos was obtained experimentally by the nonlinear interaction of two acoustic waves in a duct. In this comment a simple experimental setup and an analytical model is used to show that the dynamics of such systems corresponds to a quasiperiodic motion, and not to a chaotic one. © 2008 Acoustical Society of America.

Population dynamics and management of yellowfin tuna (Thunnus albacares) of the Oman Sea

The Yellowfin tuna was caught more than all other species in the southern waters of Iran (24000 tons in 1998). In order to come up with the responsible fishing pattern, there was a need to identify some of the biological characteristics and population dynamic parameters. This thesis was the first which covered the whole Yellowfin tuna distribution in the Oman Sea, included the fishing grounds of Berris, Ramin, Chabahar, Pozm and Jask. The data during 1998-99 from different fishing grounds were polled. Based on the exponential relationship between length and weight in the size range 38-173 Cm, the relationship (W=aL^ b) was calculated as W=0.000012L ^ 3.0831). The mean fork length,head length,girth and weight were calculated respectively 84.15 Cm, 23 Cm, 53 Cm, and 11828 g. Length infinity was estimated 189 Cm with growth parameters of 0.42 per year. Growth performance index was 4.18 which was in agreement with the findngs of the other studies in the Indian and Pacific Oceans. The mortality parameters and exploitation rate were estimated as below: Z = 1.75-1.85 M=0.6 F=1.25 E=0.68 Occurence of empty stomach was high (60%) in the speciemens obtained from the Oman Sea. Purpleback flying squid (Sthenoteuthis oualaniensis) was the most dominant prey species observed in the study (57% in females and 60% in males), occurrence of teleost fishes were found to be the second (38% in males and 42% in females). Crabs also were identified in the specimens(1-2%). The study on sex ratio indicated that males were predominant at all sizes above 120 Cm fork length. 50.82% of specimens were males and 49.18% females. The monthly gonadosomatic index was deriven higher values during January to June which could be indicated as spawning period.

Ca~（＋＋）Na~＋离子对湖南产五步蛇蛇毒PLA_2酶活力的影响

Ｃａ~（＋＋）离子能极大地激活五步蛇蛇毒ＰＬＡ_２的酶活力，Ｎａ离子只能在一定程度上激活，作者推测在测定ＰＬＡ_２酶活力的底物溶液中可以不加Ｎａ~＋离子。

A Study of Fan-Distortion Interaction Within the NASA Rotor 67 Transonic Stage

The performance of a transonic fan operating within nonuniform inlet flow remains a key concern for the design and operability of a turbofan engine. This paper applies computational methods to improve the understanding of the interaction between a transonic fan and an inlet total pressure distortion. The test case studied is the NASA rotor 67 stage operating with a total pressure distortion covering a 120-deg sector of the inlet flow field. Full-annulus, unsteady, three-dimensional CFD has been used to simulate the test rig installation and the full fan assembly operating with inlet distortion. Novel post-processing methods have been applied to extract the fan performance and features of the interaction between the fan and the nonuniform inflow. The results of the unsteady computations agree well with the measurement data. The local operating condition of the fan at different positions around the annulus has been tracked and analyzed, and this is shown to be highly dependent on the swirl and mass flow redistribution that the rotor induces ahead of it due to the incoming distortion. The upstream flow effects lead to a variation in work input that determines the distortion pattern seen downstream of the fan stage. In addition, the unsteady computations also reveal more complex flow features downstream of the fan stage, which arise due to the three dimensionality of the flow and unsteadiness. © 2012 American Society of Mechanical Engineers.

外源Ca~(2+)对模拟微重力环境中鱼腥藻细胞质膜透性和光合特性的影响

以鱼腥藻为材料 ,研究了外源Ca2 +对模拟微重力环境中微藻细胞膜透性的影响。实验结果表明 :提高培养基中的Ca2 +浓度可减轻由模拟微重力造成的膜透性增大 ,有助于稳定细胞膜结构和功能。同时 ,外源Ca2 +降低了藻细胞光系统Ⅱ (PSⅡ )的光化学效率 (以荧光参数Fv/Fm表示 )下降的幅度 ,表明外源Ca2 +对模拟微重力环境下鱼腥藻细胞光合作用的损伤 ,有良好的防护效应。

Spin-cluster effect and lattice-deformation-induced Kondo effect, spin-glass freezing, and strong phonon scattering in La 0.7 Ca 0.3Mn 1-xCr xO 3

Besides the Kondo effect observed in dilute magnetic alloys, the Cr-doped perovskite manganate compounds La0.7 Ca0.3 Mn1-x Crx O3 also exhibit Kondo effect and spin-glass freezing in a certain composition range. An extensive investigation for the La0.7 Ca0.3 Mn1-x Crx O3 (x=0.01, 0.05, 0.10, 0.3, 0.6, and 1.0) system on the magnetization and ac susceptibility, the resistivity and magnetoresistance, as well as the thermal conductivity is done at low temperature. The spin-glass behavior has been confirmed for these compounds with x=0.05, 0.1, and 0.3. For temperatures above Tf (the spin-glass freezing temperature) a Curie-Weiss law is obeyed. The paramagnetic Curie temperature θ is dependent on Cr doping. Below Tf there exists a Kondo minimum in the resistivity. Colossal magnetoresistance has been observed in this system with Cr concentration up to x=0.6. We suppose that the substitution of Mn with Cr dilutes Mn ions and changes the long-range ferromagnetic order of La0.7 Ca0.3 MnO3. These behaviors demonstrate that short-range ferromagnetic correlation and fluctuation exist among Mn spins far above Tf. Furthermore, these interactions are a precursor of the cooperative freezing at Tf. The "double bumps" feature in the resistivity-temperature curve is observed in compounds with x=0.05 and 0.1. The phonon scattering is enhanced at low temperatures, where the second peak of double bumps comes out. The results indicate that the spin-cluster effect and lattice deformation induce Kondo effect, spin-glass freezing, and strong phonon scattering in mixed perovskite La0.7 Ca0.3 Mn1-x Crx O3. © 2005 American Institute of Physics.

Effects of silicon addition on the electrical and magnetic properties of copper-doped (La,Ca)MnO3 compounds

In this paper we report about the electrical properties of La 0.7Ca0.3MnO3 compounds substituted by copper on the manganese site and/or deliberately contaminated by SiO2 in the reactant mixture. Several phenomena have been observed and discussed. SiO2 addition leads to the formation of an apatite-like secondary phase that affects the electrical conduction through the percolation of the charge carriers. On the other hand, depending on the relative amounts of copper and silicon, the temperature dependence of the electrical resistivity can be noticeably modified: our results enable us to compare the effects of crystallographic vacancies on the A and B sites of the perovskite with the influence of the copper ions substituted on the manganese site. The most original result occurs for the compounds with a small ratio Si/Cu, which display double-peaked resistivity vs. temperature curves. © 2003 Elsevier B.V. All rights reserved.

利用水生植物清除水体中放射性物质的研究 (Ⅲ)水生植物对Sr~(90)、Y~(91)、Cs~(137)、Ce~(144)的积累、释放及Ca���Sr~(90)吸收的影响

5种水生植物对所用4种放射性同位素都有一定的清除能力,其清除能力的大小不仅取决于生物的种类,而且还取决于生物本身代谢率的高低。试验结果:去污率高的可达80%,积累系数最高可达1,500;水体中含Ca���的多少对生物吸收积累放射性物质的多少有一定的影响;生物在积累放射性物质之后,转移到无放射性物质的水体中将释放出原积累的一部分放射性物质。

The effect of organic matter accumulation on phosphorus release in sediment of Chinese shallow lakes

The effects of organic matter in sediment on phosphorus release were studied by field investigations in eight Chinese shallow freshwater lakes with different trophic status and a laboratory experiment. The sediment organic matter content paralleled the trophic status, ranging from 6.1 to 173.0 g kg(-1) (dry weight), with the mean value of 63.1 g kg(-1) (dry weight). It was positively proportional to Soluble reactive phosphorus concentration in the interstitial water in a form of exponential function, but inversely related to the sediment Fe/P ratio. The sediment alkaline phosphatase activity was significantly related not only to the organic matter content (r = 0.829, P < 0.01, n = 120), but also to the soluble reactive phosphorus concentration in interstitial water (r = 0.454, P < 0.01, n = 42). In the laboratory experiment, the addition of organic matter (dry materials of an aquatic macrophyte) into the sediment significantly enhanced alkaline phosphatase activity and soluble reactive phosphorus release. However, in the treatment with organic matter added and aeration, this release was generally prevented in spite of an increase in APA. Hence, sediment organic matter can effectively accelerate phosphorus release by enzymatic hydrolysis and anaerobic desorption. The latter mechanism seems to be more important.

Microcystin-RR induces physiological stress and cell death in the cyanobacterium Aphanizomenon sp DC01 isolated from Lake Dianchi, China

The phytoplankton community in Lake Dianchi (Yunnan Province, Southwestern China) is dominated in April by a bloom of Aphanizomenon, that disappears Suddenly and is displaced by a Microcystis bloom in May. The reasons for the rapid bloom disappearance phenomenon and the temporal variability in the composition of phytoplankton assemblages are poorly understood. Cell growth, ultrastructure and physiological changes were examined in cultures of Aphanizomenon sp. DC01 isolated from Lake Dianchi exposed to different closes of rnicrocystin-RR (MC-RR) produced by the Microcystis bloom. MC-RR concentrations above 100 mu g L-1 markedly inhibited the pigment (chlorophyll-a, phycocyanin) synthesis and caused an increase of soluble carbohydrate and protein contents and nitrate reductase activity of toxin-treated blue-green algae. A drastic. reduction in photochemical efficiency of PSII (Fv/Fm) was also found. Morphological examinationn showed that the Aphanizomenon filaments disintegrated and file cells lysed gradually after 48 h Of toxin exposure. Transmission electron microscopy revealed that cellular inclusions of stressed cells almost leaked out completely and the cell membranes were grossly damaged. These findings demonstrate the allelopathic activity of Microcystis aeruginosa inducing physiological stress and cell death of Aphanizomenon sp. DC01 Although the active concentrations of microcystin were rather high, we propose that microcystin may function as allelopathic Substance due to inhomogeneous toxin concentrations close to Microcystis cells. Hence, it may play a role in species Succession of Aphanizomenon and Microcystis in Lake Dianchi.

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.