Die Matrix der Fische XVI Zweidimensionale papierchromatographische Analyse von Fischschuppenhydrolysaten und Hydrolysaten einiger weiterer Fischorgane     

Ulrich A. Corti  L. Keller 《Aquatic Sciences - Research Across Boundaries》1952,14(2):336-337

Summary The aminoacids in hydrolysates (HCl) of the scales of six different fish-species have been determined by partition paper chromatography (Consden andDent). The scales contain considerable amounts of protein besides hydroxyl apatit and guanin, but none or only minute quantities of carbohydrates. Some of the aminoacids in the liver, air-bladder, kidney and the body muscles of two fish species were investigated.   相似文献   

Hyperpycnal plumes and plume fronts over the Huanghe (Yellow River) delta front   总被引：6，自引：0，他引：6  

L. D. Wright  Z. -S. Yang  B. D. Bornhold  G. H. Keller  D. B. Prior  W. J. Wiseman Jr. 《Geo-Marine Letters》1986,6(2):97-105

The Huanghe (Yellow River) discharges extremely high suspended sediment concentrations (25 to 220 g/l) which favor sustained hyperpycnal plumes (underflows). Observations of weakly hyperpycnal unchannelized plumes and indirect evidence of strongly hyperpycnal channelized underflows over the delta front indicate the importance of these modes of sediment dispersal. The weakly hyperpycnal plumes occupy the entire water column over the shallow (<5 m) delta top. From a pronounced front near the break in slope at about 5 m depth, they descend over the delta-front slope as wide-spread underflows. Evidence of strongly hyperpycnal underflows was shown from subaqueous valleys partly filled with low-density mud.  相似文献   

Sedimentary framework of the modern Huanghe (Yellow River) delta   总被引：12，自引：0，他引：12  

B. D. Bornhold  Z. -S. Yang  G. H. Keller  D. B. Prior  W. J. Wiseman Jr.  Q. Wang  L. D. Wright  W. D. Xu  Z. Y. Zhuang 《Geo-Marine Letters》1986,6(2):77-83

The geometry, stratigraphy, and structure of recently deposited Huanghe (Yellow River) Delta sediments were examined by high resolution subbottom profiles and medium-penetration boomer profiles. The results indicate that the active (post-1976) subaqueous delta advances as a single thin localized lobe with a maximum thickness of only 15 m. Calculations of sediment volumes indicate that 90% or more of the sediment supplied by the Huanghe remains within 30 km of the mouth. Sediment on the delta platform near the mouth is fine sand; elsewhere silts and clays prevail.[/p]  相似文献   

现行黄河口水下三角洲海底形貌及不稳定性   总被引：4，自引：0，他引：4  

杨作升  G.H.Keller  陆念祖  D.B.Prior  林天充  B.D.Bornhold  许卫东  L.D.Wright  J.Suhayda  曹立华  W.J.Wisenman 《中国海洋大学学报(自然科学版)》1990,(1)

高分辨力的声学仪器调查表明,现行黄河口水下三角洲海底的形貌十分复杂,由于高浓度巨量黄河泥沙快速沉积的结果,使河口底坡出现了大量的不稳定性现象,如塌陷冲沟,高密度沉积物重力流,切割—充填结构海底,V形水下河谷、滑塌等。根据海底扰动程度作了分区,划分了地形单元,并对不同的海底形态的成因作了分析。比较了1985和1986年两个航次考查结果的变动,分析了原因。  相似文献   

The assessment of the age of scleractinian coral species (Anthozoa: Scleractinia) based on the temperature ranges of their habitat     

N. S. Os’kina  N. B. Keller  S. D. Nikolaev 《Oceanology》2010,50(6):975-983

Until now, the age of deep-water scleractinians was determined based only on rare finds of these corals in terrestrial sequences, which constitute <10% of their known diversity. Inasmuch as most of the non-zooxanthellate coral species dwell in the ocean beyond the shelf zone (up to the abyssal depths) and their fossil remains are missing from terrestrial sections, we propose a new approach to the assessment of their age based on paleoecological features: the seawater temperatures in the geological past and the habitat temperature ranges established for 53 coral species. The study confirmed our previous assumption concerning the very young age of the deep-water fauna.  相似文献   

Dawn Mission to Vesta and Ceres     

C. T. Russell  F. Capaccioni  A. Coradini  M. C. De Sanctis  W. C. Feldman  R. Jaumann  H. U. Keller  T. B. McCord  L. A. McFadden  S. Mottola  C. M. Pieters  T. H. Prettyman  C. A. Raymond  M. V. Sykes  D. E. Smith  M. T. Zuber 《Earth, Moon, and Planets》2007,101(1-2):65-91

The initial exploration of any planetary object requires a careful mission design guided by our knowledge of that object as gained by terrestrial observers. This process is very evident in the development of the Dawn mission to the minor planets 1 Ceres and 4 Vesta. This mission was designed to verify the basaltic nature of Vesta inferred both from its reflectance spectrum and from the composition of the howardite, eucrite and diogenite meteorites believed to have originated on Vesta. Hubble Space Telescope observations have determined Vesta’s size and shape, which, together with masses inferred from gravitational perturbations, have provided estimates of its density. These investigations have enabled the Dawn team to choose the appropriate instrumentation and to design its orbital operations at Vesta. Until recently Ceres has remained more of an enigma. Adaptive-optics and HST observations now have provided data from which we can begin to confidently plan the mission. These observations reveal a rotationally symmetric body with little surface relief, an ultraviolet bright point that can be used as a control point for determining the pole and anchoring a geographic coordinate system. They also reveal albedo and color variations that provide tantalizing hints of surface processes.  相似文献   

Sensitivity of nitrate concentration-discharge patterns to soil nitrate distribution and drainage properties in the vertical dimension     

Xiaoli Chen  Christina L. Tague  John M. Melack  Arturo A. Keller 《水文研究》2020,34(11):2477-2493

We propose a conceptual model that examines the ‘variable source area’ (VSA) and ‘nitrate flushing’ hypothesis in the vertical direction, and use this approach to explain nitrate concentration–discharge relationships in a semi-arid watershed. We use an eco-hydrology simulation model (RHESSys) to show that small changes in the vertical distribution of nitrate mass and their interaction with soil hydraulic conductivity can result in abrupt changes in the nitrate concentration–discharge relationship. We show that the estimated concentration–discharge relationship is sensitive to the parameters governing soil vertical nitrate distribution and soil hydraulic conductivity, at both patch scale and watershed scale, where lateral redistribution of water and nitrate is also accounted for. Given heterogeneity in nitrogen inputs, uptake processes, soil drainage and storage processes, substantial variation in parameters that describe rate of changes in vertical distribution of soil nitrate and hydraulic properties is likely both within and between watersheds. Thus, we argue that vertical ‘variable source area’ processes may be as important as lateral VSA in determining concentration discharge relationships.  相似文献   

An experimental study of the formation of cubanite (CuFe2S3) in primitive meteorites          下载免费PDF全文

Eve L. Berger  Lindsay P. Keller  Dante S. Lauretta 《Meteoritics & planetary science》2015,50(1):1-14

The low‐temperature form of CuFe₂S₃, cubanite, has been identified in the CI chondrite and NASA Stardust mission collections. The presence of this mineral constrains the maximum temperature to 210 °C since the time of its formation. However, until now, the conditions under which cubanite forms were less well constrained. In order to refine the history of the time‐varying, low‐temperature fluids which existed on the CI‐chondrite parent body and Comet 81P/Wild 2 (Wild 2), we synthesized cubanite. The experimental synthesis of this mineral was achieved, for the first time, under low‐temperature aqueous conditions relevant to the CI‐chondrite parent body. Using a variant of in situ hydrothermal recrystallization, cubanite formed in aqueous experiments starting with temperatures of 150 and 200 °C, pH approximately 9, and oxygen fugacities corresponding to the iron‐magnetite buffer. The composition and structure of the cubanite were determined using electron microprobe and transmission electron microscopy techniques, respectively. The combined compositional, crystallographic, and experimental data allow us to place limits on the conditions under which the formation of cubanite is feasible, which in turn constrains the nature of the fluid phase on the CI‐chondrite parent body and Wild 2 when cubanite was forming.  相似文献   

Microstructural evidence for a disequilibrium condensation origin for hibonite‐spinel inclusions in the ALHA77307 CO3.0 chondrite          下载免费PDF全文

Jangmi Han  Adrian J. Brearley  Lindsay P. Keller 《Meteoritics & planetary science》2015,50(12):2121-2136

Two hibonite‐spinel inclusions (CAIs 03 and 08) in the ALHA77307 CO3.0 chondrite have been characterized in detail using the focused ion beam sample preparation technique combined with transmission electron microscopy. These hibonite‐spinel inclusions are irregularly shaped and porous objects and consist of randomly oriented hibonite laths enclosed by aggregates of spinel with fine‐grained perovskite inclusions finally surrounded by a partial rim of diopside. Melilite is an extremely rare phase in this type of CAI and occurs only in one inclusion (CAI 03) as interstitial grains between hibonite laths and on the exterior of the inclusion. The overall petrologic and mineralogical observations suggest that the hibonite‐spinel inclusions represent high‐temperature condensates from a cooling nebular gas. The textural relationships indicate that hibonite is the first phase to condense, followed by perovskite, spinel, and diopside. Texturally, melilite condensation appears to have occurred after spinel, suggesting that the condensation conditions were far from equilibrium. The crystallographic orientation relationships between hibonite and spinel provide evidence of epitaxial nucleation and growth of spinel on hibonite surfaces, which may have lowered the activation energy for spinel nucleation compared with that of melilite and consequently inhibited melilite condensation. Hibonite contains abundant stacking defects along the (001) plane consisting of different ratios of the spinel and Ca‐containing blocks within the ideal hexagonal hibonite structure. This modification of the stacking sequence is likely the result of accommodation of excess Al in the gas into hibonite due to incomplete condensation of corundum from a cooling gas under disequilibrium conditions. We therefore conclude that these two hibonite‐spinel inclusions in ALHA77307 formed by high‐temperature condensation under disequilibrium conditions.  相似文献   

Observations of Comet 9P/Tempel 1 around the Deep Impact event by the OSIRIS cameras onboard Rosetta     

Horst Uwe Keller  Sonia Fornasier  Stubbe F. Hviid  Jörg Knollenberg  Miriam Rengel  Gabriele Cremonese  Detlef Koschny  Ekkehard Kührt  Holger Sierks  Cesare Barbieri  Hans Rickman  Michael F. A'Hearn  Maria-Antonella Barucci  Vania da Deppo  Björn J.R. Davidsson  Stefano Debei  Fritz Gliem  José J. Lopez Moreno  Giampiero Naletto  Angel Sanz Andrés 《Icarus》2007,187(1):87-103

The OSIRIS cameras on the Rosetta spacecraft observed Comet 9P/Tempel 1 from 5 days before to 10 days after it was hit by the Deep Impact projectile. The Narrow Angle Camera (NAC) monitored the cometary dust in 5 different filters. The Wide Angle Camera (WAC) observed through filters sensitive to emissions from OH, CN, Na, and OI together with the associated continuum. Before and after the impact the comet showed regular variations in intensity. The period of the brightness changes is consistent with the rotation period of Tempel 1. The overall brightness of Tempel 1 decreased by about 10% during the OSIRIS observations. The analysis of the impact ejecta shows that no new permanent coma structures were created by the impact. Most of the material moved with . Much of it left the comet in the form of icy grains which sublimated and fragmented within the first hour after the impact. The light curve of the comet after the impact and the amount of material leaving the comet ( of water ice and a presumably larger amount of dust) suggest that the impact ejecta were quickly accelerated by collisions with gas molecules. Therefore, the motion of the bulk of the ejecta cannot be described by ballistic trajectories, and the validity of determinations of the density and tensile strength of the nucleus of Tempel 1 with models using ballistic ejection of particles is uncertain.  相似文献