Synedra ulna var. repanda, a new variety of Synedra （Bacillariophyta） from Xinjiang, China

Synedra ulna var. repanda Q. X. Wang & Q. M. You, a new variety of Synedra (Bacillariophyta) from Xinjiang, China, is described and illustrated, and the characteristic of the variety: includes undulate-linear valves and straight pseudoraphe, differs from other species of Synedra.     

三疣梭子蟹(Portunus trituberculatus)RXR基因克隆及其在蜕皮过程中的表达分析

本研究通过转录组测序和RACE技术克隆了三疣梭子蟹类维甲酸X受体2(PtRXR2)基因cDNA全长(登录号:KF914662),并通过荧光定量PCR(qRT-PCR)技术研究了该基因在三疣梭子蟹不同组织及不同蜕皮阶段的表达情况。结果表明,(1)PtRXR2基因cDNA全长1718bp,包括5’非编码区(5’-UTR)141bp、3’-UTR 209bp和开放阅读框1368bp,编码455个氨基酸,预测分子量和等电点为49.75kDa和6.79。(2)PtRXR2推导氨基酸序列的Blastp结果显示,PtRXR2与已知甲壳动物RXR的一致性为74%—99%,系统进化树分析表明PtRXR2与其它甲壳动物RXR聚为一支。(3)qRT-PCR结果显示PtRXR2在C期三疣梭子蟹Y器官、鳃、眼柄和大颚器中表达水平较高,肝胰腺中的表达水平最低。其它6个组织中的表达水平居中。(4)不同蜕皮阶段,PtRXR2在Y器官、眼柄和胸神经中均是AB期表达水平最高,E期最低,这可能与上述器官的细胞增殖主要发生在AB期有关;肌肉中的PtRXR2表达水平在AB和C期较高,E和D期最低,与肌肉的生长和营养物质积累主要发生在这两个阶段相对应;肝胰腺中的PtRXR2表达水平在AB期最高,C期最低,这暗示PtRXR2主要参与肝胰腺中的上皮细胞增殖和分化,对于C期的营养代谢调控可能不起关键作用。     

水稻微波后向散射系数的模拟分析

海洋雷达后向散射回波主要来自短重力波的Ｂｒａｇｇ 散射,这种散射与海面风场信息、边界层涡旋等密切相关。因此,可以从雷达散射截面反演风场信息。对１９９４ 年４ 月航天飞机成像雷达（ＳＩＲＣ／ＸＳＡＲ）获取的南中国海合成孔径雷达（ＳＡＲ） 图像进行了分析研究。利用ＳＩＲＣ 数据,从ＳＡＲ 图像谱提取了风向;根据ＣＭＯＤ４ 模型,从Ｃ波段雷达后向散射系数反演风速;利用双尺度散射模型对反演的风速进行了对比分析。结果表明,从ＳＩＲＣ雷达数据可以反演海面风矢量,星载ＳＡＲ是提取海面风场信息的有效技术手段之一。     

Diamond-bearing and diamond-free metacarbonate rocks from Kumdy–Kol in the Kokchetav Massif, northern Kazakhstan

Abstract Dolomite marble from the Kumdy–Kol area of the Kokchetav Massif contains abundant microdiamond, mainly in garnet and a few in diopside. The mineral assemblage at peak metamorphic condition consists of dolomite + diopside + garnet (+ aragonite) ± diamond. Inclusions of very low MgCO₃ calcite and almost pure calcite occur in diopside and are interpreted as aragonite and/or aragonite + dolomite. Single-phase Mg–calcite in diopside with a very high MgCO₃ component (up to 21.7 mol%) was also found in diamond-free dolomitic marble, and is interpreted as a retrograde product from aragonite + dolomite to Mg–calcite. The dolomite stability constrains the maximum pressure (P) at < 7 GPa using previous experimental data, whereas the occurrence of diamond yields the minimum peak pressure–temperature (P–T) condition at 4.2 GPa and 980 °C at X co ₂ = 0.1. The highest MgCO₃ in Mg–calcite constrains the minimum P–T condition higher than 2.5 GPa and 800 °C for the exhumation stage. As these marbles were subjected to nearly identical P–T metamorphic conditions, the appearance of diamond in some carbonate rocks was explained by high X co ₂. A low X co ₂ condition refers to high oxidized conditions and diamond (and/or graphite) becomes unstable. Difference in X co ₂ for marble from the same area suggests local heterogeneity of fluid compositions during ultrahigh-pressure metamorphism.     

土壤铁锰结核中锰矿物类型鉴定的探讨

用化学选择溶提、X射线衍射 (XRD)等技术 ,对土壤铁锰结核中锰矿物类型的鉴定进行了探讨。结果表明 :根据 0 .1mol·L-1盐酸羟胺 (HAHC)处理前后土壤铁锰结核的XRD峰的变化 ,可鉴定出其所含的锂硬锰矿和钙锰矿 ;分析HAHC处理前后同一XRD谱线上不受锰矿物干扰的相邻层状硅酸盐矿物衍射峰与所含锰矿物衍射峰强度的比值变化 ,确定了水钠锰矿的存在 ;结合铁锰结核中与锰矿物类型相关的元素含量 ,可鉴定出其所含的钡硬锰矿和铅锰矿。     

多道X射线荧光方法在现代地层学研究中的初步应用

放射性同位素多道X荧光分析是一种核分析方法 ,具有快速、无损、低成本及多元素分析等优点。以华蓥山地区庙坝下三叠统嘉陵江组剖面为例 ,采用放射性同位素多道X荧光分析方法 ,测定了地层中Ca、Fe、Sr、Ba元素的照射率 ,并进行了化学地层和层序地层的初步研究 ,取得了较好的效果。     

Spectroscopy and orbital periods of the old novae V533 Herculis, V446 Herculis and X Serpentis

We report spectroscopic orbital periods of 0.147 d (=3.53 h) for V533 Her, 0.207 d (=4.97 h) for V446 Her and 1.478 d for X Ser. V533 Her (Nova Herculis 1963) shows absorption features in its He  i and Balmer lines which appear only in a limited range of orbital phase, suggesting that it is a low-inclination SW Sextantis star. V446 Her is unusual in that it has started normal dwarf nova eruptions after a nova outburst, but we find nothing else unusual about it – in particular, a distance estimate based on its dwarf nova outbursts agrees nicely with another based on the rate of decline of its nova eruption, both giving d ∼1 kpc. In X Ser, unlike in other old novae with long periods, no spectral features of the secondary star are visible. This and its outburst magnitude both suggest that it is quite distant and luminous, and at least 1 kpc from the Galactic plane.     

1E 1207.4–5209: Are the optical and X‐ray spectra blueshifted?

1E 1207.4–5209 is an X‐ray source located at the centre of the supernova remnant (SNR) PKS 1209–52 (G296.5+10.0) and is thought to be an isolated neutron star (INS) associated with the SNR. Its optical spectrum shows several absorption lines and the X‐ray spectrum exhibits three variable absorption features at what appears to be harmonically related wavelengths, the latter being interpreted as due to cyclotron resonance. However, there are several serious problems, uncertainties and difficulties in the above association (SNR/INS) and in the interpretation of the spectra. In view of these, we suggest an alternative explanation of the observed spectra in terms of blueshifts. This implies that the optical and X‐ray absorption spectra are due to the central object of the SNR in association with two separate absorption clouds ejected at successively increasing speeds. The clouds have their origins in jets resulting from the merger of two very massive compact stars. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Magnetic flares in Active Galactic Nuclei: modeling the iron Kα line

The X‐ray spectra of Active Galactic Nuclei (AGN) are complex and vary rapidly in time as seen in recent observations. Magnetic flares above the accretion disk can account for the extreme variability of AGN. They also explain the observed iron Kα fluorescence lines. We present radiative transfer modeling of the X‐ray reflection due to emission from magnetic flares close to the marginally stable orbit. The hard X‐ray primary radiation coming from the flare source illuminates the accretion disk. A Compton reflection/reprocessed component coming from the disk surface is computed for different emission directions. We assume that the density structure remains adjusted to the hydrostatic equilibrium without external illumination because the flare duration is only a quarter‐orbit. The model takes into account the variations of the incident radiation across the hot spot underneath the flare source. The integrated spectrum seen by a distant observer is computed for flares at different orbital phases close to the marginally stable orbit of a Schwarzschild black hole and of a maximally rotating Kerr black hole. The calculations include relativistic and Doppler corrections of the spectra using a ray tracing technique. We explore the practical possibilities to map out the azimuthal irradiation pattern of the inner accretion disks and conclude that the next generation of X‐ray satellites should reveal this structure from iron Kα line profiles and X‐ray lightcurves. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Power spectra from ‘spotted’ accretion discs

We are carrying out a project to calculate power spectra of variability, assuming a model of a ‘spotted’ accretion disc near a black hole. We consider relativistic effects that change photon energy and produce light‐bending and time‐delays acting on the X‐ray signal received by an observer. We assume that the life‐time and the intrinsic emissivity of individual.aring events are described in terms of a simple stochastic process. This allows us to give approximate analytical formulae and compare them with numerical computations. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)