Surface Photometry of Comet Hale-Bopp Carbon Images

A very long series of photographic observations of the comet Hale-Bopp has been made during January–April 1997 at the double astrograph (400/2000) of the Main Astronomical Observatory (Kyiv, Ukraine). Some of the cometary photos were obtained with two wide-band filter combinations. One of these combinations isolates C₂ emission, another — the nearby dust continuum. The images were digitized by means of AMDPH-XY machine and then calibrated following the standard procedure. After subtraction of the dust continuum the distribution of surface brightness in the C₂ emission coma of comet Hale-Bopp was studied. We found an asymmetric brightness distribution both pre- and post-perihelion. On 21.77 April 1997 a secondary brightness peak is found at the distance of 1.03 × 10⁵ km from the nucleus. It is possible that this peak is related to the extended source of the C₂ molecules. This revised version was published online in July 2006 with corrections to the Cover Date.     

富碳拱星IRC＋10216和CIT6的CO J=1—0转动谱的观测

使用中国科学院紫金山天文台青海站13.7米射电望远镜于1996年12月至1997年1月对富碳拱星IRC 10216和CIT6的CO J=1-0跃迁(115GHz)进行了观测。在观测谱线的基础上得到了IRC 10216的视向速度和膨胀速度分别为一26.1km s~(-1)和14.8km s~(-1),CIT6的视向速度和膨胀速度分别为0.6km s~(-1)和13.8kms~(-1)。并对望远镜的射束及指向精度进行了研究。     

Belemnites from the lower middle Cenomanian of Hoppenstedt, northern Germany: significance and integrated correlation

The belemnite species Praeactinocamax primus (Arkhangelsky, 1912) and Belemnocamax boweri Crick, 1910 are described from the Cenomanian of the abandoned limestone quarry section of Hoppenstedt (Sachsen-Anhalt, northern Germany). They co-occur in the upper part of a prominent tripartite bioclastic limestone bed associated with the ammonite Acanthoceras rhotomagense, indicating the primus Event of the lower middle Cenomanian A. rhotomagense ammonite Zone. An integrated stratigraphical calibration including carbon stable isotope correlation to southern England suggests that the belemnite event horizon at Hoppenstedt occupies exactly the same chronostratigraphical position as elsewhere, highlighting the strictly isochronous character of the primus Event across northwestern Europe. Furthermore, stratigraphical gaps in the Hoppenstedt succession are evaluated.     

EPR investigation of the methyl radical,the hydrogen atom and carbon oxide radicals in Maxixe-type beryl

The EPR spectra of Maxixe-type beryl contain a large number of overlapping signals. The angular dependence of the 1:3:3:1 signal typical for the CH₃ radical shows that this radical is located at the center of the channel cavity with its symmetry axis parallel to the crystal c-axis and is rotating around this axis. Its EPR spectrum is axially symmetric with g _// = 2.00263, g _⊥ = 2.00249 and A_// = 2.288 mT, A_⊥ = 2.256 mT. These anisotropies have the opposite signs of those found for surface-adsorbed methyl radicals. Hydrogen atoms are located at position 2a at the center of the beryl cavity and the EPR parameters of the narrow doublet signal are A ₀ = 1,407 MHz and g = 2.00230. Another doublet signal, which is broader and has axial symmetry with g _// = 2.00265, g _⊥ = 2.00625 and A_// = 0.895 mT, A_⊥ = 0.885 mT, could come from a HCO₃ radical. One narrow and easily saturated signal with g _// = 2.00227 and g _⊥ = 2.00386 is interpreted to arise from a carbon monoxide radical in the beryl channel, oriented with its axis parallel to the crystal c-axis. Additional weak doublet lines, which have similar g values as the carbon monoxide radical, are created by nearby hydrogens. A powder spectrum with g _// = 2.0017 and g _⊥ = 2.0004 appears upon UV irradiation of the single crystal and is easily saturated. This spectrum is interpreted to arise from a carbon dioxide radical, which rotates around its symmetry axis.     

浙江省长兴县煤山剖面二叠—三叠系过渡地层中的黑碳记录及其地质意义

首次报道了浙江煤山二叠-三叠系界线地层中黑碳的含量及其碳同住素的变化特征。黑碳含量在26层存在一个明显的峰值,含量高达0．51％。黑碳与总有机碳比值从25层底部开始持续升高,在26层达到最高,稳定在0．40以上。黑碳的碳同位素在24层和25层之间有一个陡然的降低,降低幅度达2‰,在25和26层中则存在一个幅度达3‰的缓慢降低,总降低幅度达5‰。黑碳是动植物和化石燃料燃烧的天然记录,浙江煤山二叠-三叠系界线附近黑碳特征反映了二叠纪末期陆地生态系统发生了突然的衰退,发生了强烈的天然大火。根据事件层大火燃烧的长期性或频繁的特征,以及黑碳同位素大幅度陡然降低和缓慢降低,认为燃烧源除了陆地植被外,还有其他富含轻碳的化石燃料,即大火的燃烧源除了植被外,还可能有煤和甲烷水合物等。浙江煤山剖面的黑碳记录,反映了二叠-三叠纪之交地球陆地环境的剧烈变化,有助于理解和揭示生物大灭绝的过程和原因。     

山东近海牙鲆(Paralichthys olivaceus)自然和养殖群体10个微卫星基因座位的遗传多态性分析

采用微卫星遗传标记技术对山东近海牙鲆自然群体和养殖群体的遗传多样性进行了研究。实验所用牙鲆于2003年5月分别采自山东近海和青岛胶南养鱼场，各20尾，取全血或肌肉组织，以酚-仿抽提方法提取基因组DNA，利用筛选获得的10对微卫星引物进行PCR扩增，反应产物经8％非变性聚丙烯酰胺凝胶电泳分离、EB显色，用ImageMasterl D Elite(Version 3．01)软件分析电泳结果，并计算了相应的遗传学参数。结果表明，在自然和养殖群体中，10个基因座位的等位基因平均数(α)分别为6．7和6．1，每个基因座位有效等位基因数(αe)分别为1．8—6．8和2．5—6．7，群体平均杂合度(H)分别为0．8120和0．7310；两个群体间的遗传相似性系数、遗传距离和基因分化系数为0．8558、0．1557和0．0558；自然群体内每个座位上的多态信息含量(PIC)为0．59—0．84、个体识别率(DP)为0．54—0．86、非父排除率(PPE)为0．41—0．72，其累积个体识别率和非父排除率均达到0．9999，表明所选座位属中高识别力的遗传标记，可以将它们应用于今后牙鲆雌核发育群体的遗传变异分析以及进一步的遗传育种的研究中。     

The buckling of a corrugated carbon fibre cylinder under external hydrostatic pressure

A theoretical and an experimental investigation was carried out, where a carbon fibre corrugated circular cylinder was tested to destuction under external hydrostatic pressure. The theoretical investigation was via the finite element method, where the structure was modelled with several orthotropic axisymmetric thin-walled shell elements. The experimental observations were aided with strategically placed strain gauges. Comparison between theory and experiment showed that the experimentally observed buckling pressure was a little lower than the theoretical prediction. This may have been due to the fact that the model had slight initial geometrical imperfections in the circumferenential direction.     

Seasonal DOC accumulation in the Black Sea: a regional explanation for a general mechanism

During three cruises in the Black Sea, organised in July 1995 and April–May 1997, biological and chemical parameters that can influence the carbon budget were measured in the water column on the NW shelf, particularly in the mixing zone with Danube River waters. We observed in early spring (end of April–May) conditions an important input of freshwater organisms that enhanced the microbial activity in the low salinity range. High bacterial activity regenerates nitrogen in the form of nitrates, but is also responsible for an important consumption of ammonium and phosphate, leading to a high N/P ratio and a strong deficit in phosphorus. The consequence is a limitation of phytoplankton development but also a production of carbohydrates that accumulate all along the salinity gradient. These mechanisms are responsible for a seasonal accumulation of dissolved organic carbon (DOC) that increases from 210 μM in winter to about 280 μM in summer. All this excess DOC disappears during winter, probably degraded by bacterial activity. The degradation of carbon-rich organic matter increases the phosphorus demand by bacteria bringing limitation to phytoplankton primary production.     

Size distribution of colloidal trace metals and organic carbon during a coastal bloom in the Baltic Sea

The physico-chemical speciation of organic carbon and selected metals was measured during a coastal bloom in Ekhagen Bay, Baltic Sea, using ultrafiltration.One important objective with the study was to see if any depletion of trace metals could be measured in the directly bioavailable fraction (<1000 Da, the soluble low molecular weight fraction, LMW) during a plankton bloom. Filters with five different cut-offs were used (1 kD (1000 Da), 5 kD, 10 kD, 100 kD and 0.22 μm) in order to delineate the size distribution of colloidal organic carbon (COC) and trace metals.During the bloom in May, LMW Al, Co, Cu, Mn and Ni concentrations decreased although the colloidal and particulate concentrations were relatively high. Data show that desorption of colloidal and particulate bound trace metals to the LMW fraction was slower than the process depleting the LMW fraction.Estimates of the maximum active uptake of Cu, Ni and Mn by the phytoplankton, and the loss of non-bioactive Al from the LMW fraction, indicate that processes other than active uptake by phytoplankton must contribute to the observed depletion of trace metals in the LMW fraction. Hence, in order to estimate the bioavailable pool of trace metals for plankton during bloom conditions, these other processes must be understood and quantified.Transparent Exopolymeric Particles (TEP, reflecting sugar-rich phytoplankton exudates) increased around eight times during the plankton bloom. We hypothesize that the formation of TEP is a process that might be important for the transfer of trace metals from the LMW to the particulate fraction during the phytoplankton bloom, but the significance of TEP for this depletion in Baltic Sea surface water remains to be shown.