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Assessing Possibilities and Limitations for Biomarker Analyses on Outcrop Samples:A Case Study on Carbonates of the Shibantan Member (Ediacaran Period, Dengying Formation, South China)

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Acta Geologica Sinica(English Edition) 2014年第6期88卷 1696-1704页

作者： Jan-Peter DUDA volker THIEL Joachim REITNER Martin BLUMENBERG Geoscience Centre Geobiology Group Georg-August-University GttingenGoldschmidtstr.337077 Gttingen Germany Federal Institute for Geosciences and Natural Resources (BGR) Stilleweg 2 30655 Hannover Germany

The Shibantan Member（Dengying Formation, South China） represents one of only two carbonate settings with Ediacara-type organisms and offers a rare opportunity to study the biogeochemistry of these ecosystems. To evaluate possibilities and limitations for future biomarker studies on fossil-bearing outcrop samples of the Shibantan Member, we analysed the spatial distribution of hydrocarbons in extractable organic matter（i.e. bitumen） on a millimetre scale. Our study demonstrates that the sample and most likely also other rocks from the same setting are contaminated with petroleum-derived compounds that bear the potential for erroneous interpretations in palaeo-reconstructions. The contamination was revealed by distribution patterns and amounts of extractable n-alkanes and acyclic isoprenoids. The contamination is linked to the external weathering surfaces but also to cracks within the rock, and the extent most likely depends on concentration gradients between these contamination sources. Here we show that contamination can successfully be distinguished from syngenetic signals obtained from non-extractable organic matter（i.e. kerogen） using catalytic hydropyrolysis（Hy Py）. However, we observed that decalcification is necessary to achieve sufficient yields of kerogen-bound hydrocarbons and to avoid artificial alteration of the biomarker signals due to matrix effects.

关键词： Ediacaran biomarkers contamination syngeneity slice-experiments catalytic hydropyrolysis(HyPy)

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Vibrations of a laboratory-scale gas-stirred ladle with two eccentric nozzles and multiple sensors

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Journal of Iron and Steel Research International 2019年第10期26卷 1031-1040页

作者： Najib Alia Mika Pylvanainen Ville-Valtteri Visuri volker John Seppo Ollila Weierstrass Institute for Applied Analysis and Stochastics(WIAS) Berlin 10117Germany Intelligent Machines and Systems University of OuluOulu 90014Finland Process Metallurgy Research Unit University of OuluOulu 90014Finland Department of Mathematics and Computer Science Freie Universit(a)it BerlinBerlin 14195Germany SSAB Europe Oy Raahe 92101Finlan

During ladle stirring,a gas is injected into the steel bath to generate a mixing of the liquid *** optimal process control requires a reliable measurement of the stirring intensity,for which the induced ladle wall vibrations have proved to be a potential *** experimental cold water ladle with two eccentric nozzles and eight mono-axial accelerometers was thus investigated to measure the *** effect of the sensors'positions with respect to the gas plugs on the vibration intensity was analyzed,and experimental data on several points of the ladle were collected for future numerical *** is shown that the vibration root-mean-square values depend not only on process parameters,such as gas flow rate,water,and oil heights,but also on the radial and axial positions of the *** vibration intensity is clearly higher,close to the gas plumes,than in the opposite *** one of the nozzles is clogged,the vibration intensity close to the clogged nozzle drops drastically(-36 to-59%),while the vibrations close to the normal operating nozzle are hardly *** on these results,guidelines are provided for an optimized vibration-based stirring.

关键词： Ladle metallurgy Gas stirring Ladle vibration Optimal position Sensor

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Importance of performance status for treatment outcome in advanced pancreatic cancer

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World Journal of Gastroenterology 2007年第2期13卷 224-227页

作者： Stefan Boeck Axel Hinke Ralf Wilkowski volker Heinemann Department of Internal Medicine Ⅲ Klinikum Grosshadern Ludwig-Maximilians- University of Munich Marchioninistrasse 15 81377 Munich Germany WISP Research Institute Karl-Benz-Str. 1 40764 Langenfeld Germany Department of Radiooncology Klinikum Grosshadern Ludwig-Maximilians-University of Munich Marchioninistrasse 15 Munich 81377 Germany

Despite progress in the treatment of advanced and metastatic pancreatic cancer （PC）, the outcome of this disease remains dismal for the majority of patients. Given the moderate efficacy of treatment, prognostic factors may help to guide treatment decisions. Several trials identified baseline performance status as an important prognostic factor for survival. Unfit patients with a Kamofsky performance status （KPS） below 70% only have a marginal benefit from chemotherapy with gemcitabine （Gem） and may often benefit more from optimal supportive care. Once, however, the decision is taken to apply chemotherapy, KPS may be used to select either mono- or combination chemotherapy. Patients with a good performance status （KPS = 90%-100%） may have a significant and clinically relevant survival benefit from combination chemotherapy. By contrast, patients with a poor performance status （KPS ≤ 80%） have no advantage from intensified therapy and should rather receive single-agent treatment.

关键词： Chemotherapy Gemcitabine Pancreatic cancer Performance status Prognostic factor

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HCV-RNA positivity in peripheral blood mononuclear cells of patients with chronic HCV-infection: does it really mean viral replication?

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World Journal of Gastroenterology 2001年第2期7卷 228-234页

作者： volker Meier Sabine Mihm Perdita Wietzke-Braun Guliano Ramadori Georg-August-Universitat gottingen Zentrum innere medizinAbteilung Für Gastroenterologie Und EndokrinologieRobert-Koch-Straβe 4037075 GottingenGermany

AIM: To analyze the association of HCV-RNA with peripheral blood mononuclear cells (PBMC) and to answer the question whether HCV-RNA positivity in PBMC is due to viral replication. METHODS: HCV-RNA was monitored in serum and PBMC preparations from 15 patients with chronic HCV infection before, during and after an IFN-alpha therapy using a nested RT/PCR technique. In a second approach, PBMC from healthy donors were incubated in HCV positive plasma. RESULTS: In the IFN-alpha responding patients,HCV-RNA disappeared first from total RNA preparations of PBMC and then from serum. In contrast, in relapsing patients, HCV-RNA reappeared first in serum and then in PBMC. A quantitative analysis of the HCV-RNA concentration in serum was performed before and after transition from detectable to non detectable HCV-RNA in PBMC-RNA and vice versa. When HCV-RNA was detectable in PBMC preparations, the HCV concentration in serum was significantly higher than the serum HCV-RNA concentration when HCV-RNA in PBMC was not detectable. Furthermore, at no time during the observation period was HCV specific RNA observed in PBMC, if HCV-RNA in serum was under the detection limit. Incubation of PBMC from healthy donors with several dilutions of HCV positive plasma for two hours showed a concentration dependent PCR positivity for HCV-RNA in reisolated PBMC. CONCLUSION: The detectability of HCV-RNA in total RNA from PBMC seems to depend on the HCV concentration in serum. Contamination or passive adsorption by circulating virus could be the reason for detection of HCV-RNA in PBMC preparations of chronically infected patients.

关键词： Adult Aged Antiviral Agents Female Hepacivirus Hepatitis C, Chronic Humans Interferon-alpha Leukocytes, Mononuclear Male Middle Aged RNA, Viral Research Support, Non-U.S. Gov't Reverse Transcriptase Polymerase Chain Reaction Viral Load Virus Replication

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De novo exploration and self-guided learning of potentialenergy surfaces

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npj Computational Materials 2019年第1期5卷 262-270页

作者： Noam Bernstein Gábor Csányi volker L.Deringer Center for Materials Physics and Technology U.S.Naval Research LaboratoryWashingtonDC 20375USA Department of Engineering University of CambridgeCambridge CB21PZUK Department of Chemistry University of OxfordOxford OX13QRUK

Interatomic potential models based on machine learning(ML)are rapidly developing as tools for material ***,because of their flexibility,they require large fitting databases that are normally created with substantial manual selection and tuning of reference ***,we show that ML potentials can be built in a largely automated fashion,exploring and fitting potential-energy surfaces from the beginning(de novo)within one and the same *** key enabling step is the use of a configuration-averaged kernel metric that allows one to select the few most relevant and diverse structures at each *** resulting potentials are accurate and robust for the wide range of configurations that occur during structure searching,despite only requiring a relatively small number of single-point DFT calculations on small unit *** apply the method to materials with diverse chemical nature and coordination environments,marking an important step toward the more routine application of ML potentials in physics,chemistry,and materials science.

关键词： apply routine searching

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Protein Disulfide Isomerase 2 of Chlamydomonas reinhardtii Is Involved in Circadian Rhythm Regulation

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Molecular Plant 2013年第5期6卷 1503-1517页

作者： Anna Filonova Paul Haemsch Christin Gebauer Wolfram Weisheit volker Wagner Institute of General Botany and Plant Physiology Friedrich-Schiller-Universitat Jena 07743 Jena Germany

Protein disulfide isomerases （PDIs） are known to play important roles in the folding of nascent proteins and in the formation of disulfide bonds. Recently, we identified a PDI from Chlamydomonas reinhardtii （CrPDI2） by a mass spectrometry approach that is specifically enriched by heparin affinity chromatography in samples taken during the night phase. Here, we show that the recombinant CrPDI2 is a redox-active protein. It is reduced by thioredoxin reductase and catalyzes itself the reduction of insulin chains and the oxidative refolding of scrambled RNase A. By immunoblots, we confirm a high-amplitude change in abundance of the heparin-bound CrPDI2 during subjective night. Interestingly, we find that CrPDI2 is present in protein complexes of different sizes at both day and night. Among three identified interac- tion partners, one （a 2-cys peroxiredoxin） is present only during the night phase. To study a potential function of CrPDI2 within the circadian system, we have overexpressed its gene. Two transgenic lines were used to measure the rhythm of phototaxis~ In the transgenic strains, a change in the acrophase was observed. This indicates that CrPDI2 is involved in the circadian signaling pathway and, together with the night phase-specific interaction of CrPDI2 and a peroxiredoxin, these findings suggest a close coupling of redox processes and the circadian clock in C. reinhardtii.

关键词： Chlamydomonas reinhardtii protein disulfide isomerase 2 circadian clock.

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Erosion pattern of artificial gravel deposits

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International Journal of Sediment Research 2018年第1期33卷 57-67页

作者： Fabian Friedl volker Weitbrecht Robert M.Boes Laboratory of Hydraulics Hydrology and Glaciology (VAW)ETH Zurich

Sediment replenishment with artificial gravel deposits is an option to compensate for sediment deficits in rivers and to improve their ecological conditions. Predicting and quantifying the erosion rate of an artificial gravel deposit is important to successfully perform river restoration projects. Laboratory experiments have been done to investigate the influence of various parameters on the erosion pattern of artificial gravel deposits. In the present paper the effects of deposit geometry, bulk density, grain size distribution, and hydraulic load on the erosion process are described. The temporal evolution of the deposit geometry and the corresponding mean erosion rates were studied. The mean erosion rate increases with deposit height, deposit width, and decreasing grain size. Furthermore, no significant impact of the bulk density was observed. Equations to predict the mean erosion rate are proposed. This investigation helps to determine the design frequency of gravel dumping and deposit volumes for restoration projects.

关键词： Artificial gravel deposits Bed load transport Laboratory experiments Sediment replenishment

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Chinese lockdown as aerosol reduction experiment

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Advances in Climate Change Research 2021年第5期12卷 677-685页

作者： Hans VON STORCH Beate GEYER LI Yan volker MATTHIAS Burkhardt ROCKEL Institute of Coastal Systems Helmholtz-Zentrum GeesthachtGeesthacht21502Germany Ocean University of China Qingdao266100China College of Life Sciences and Oceanography Shenzhen UniversityShenzhen518061China Institute of Biogeochemistry in Coastal Seas Helmholtz-Zentrum GeesthachtGeesthacht21502Germany

The lockdown of large parts of Chinese economy beginning in late January 2020 lead to significant regional changes of aerosol loads, which suggests a reduction of backscatter and consequently a regional warming in the following months. Using local data and a numerical experiment with a limited area model, we have examined how strong this response may have been. The observed (local and reanalysis) observations point to a warming of less than 1.0 K, the simulations to a warming of the order of 0.5 K. These numbers are uncertain, because of large-scale natural variability and an ad-hoc choice of aerosol optical depth anomaly in the simulation. Thus, the result was, in short, that there was actually a weak warming of a few tenth of degrees, while noteworthy changes in circulation or in precipitation were not detected. More specifically, we found that at selected central China stations temperatures were found to be higher than in previous two years. This warming goes with a marked diurnal signal, with a maximum warming in the early afternoon (06 UTC), weakest at night (18 UTC). This may be related to a general warming of large swaths of Asia (including Siberia, which is not related to local aerosol forcing). Indeed, also the stations outside the immediate strong lockdown region are showing warming, albeit a weaker one. Thus, the difference 2020 minus 2019/2018 may overestimate the effect. The ad-hoc series of numerical experiments indicates that the simulated changes are robust and suffer little from internal dynamical variability. In particular, the overall reduction of the aerosol optical depth does not lead to phases of larger intermittent divergence among the model simulations, irrespective of the aerosol load. Instead, the simulations with reduced anthropogenic aerosol load show more a mere locally increased temperature. This may indicate that the aerosol effect is mostly thermodynamic in all local air columns in the region.

关键词： Lockdown China Aerosol Climate

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Identification of seed protein and oil related QTL in 944 RILs from a diallel of early-maturing European soybean

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The Crop Journal 2021年第1期9卷 238-247页

作者： Xintian Zhu Willmar L.Leiser volker Hahn Tobias Würschum State Plant Breeding Institute University of Hohenheim70593 StuttgartGermany

Soybean[Glycine max(L.)Merr.]is a global protein source and is currently expanding in Central and Northern *** and oil content are two important quality traits that have been studied in different germplasm,however,their genetic architecture in earlymaturing European soybean has not been investigated *** this study,we therefore performed QTL mapping for both traits using 944 recombinant inbred lines derived from eight families from a half-diallel crossing *** identified five QTL for each trait,with the QTL on chromosomes 8,15,and 20 being identified for both protein content and oil *** known major QTL on chromosome 20 was detected in four families whereas the other QTL were only found in single *** analyses revealed the QTL to have pleiotropic but inverse effects on both *** effect of the major QTL was comparable between families,illustrating that it is largely independent from the genetic ***,our results illustrate the quantitative nature of protein and oil content in early European ***-assisted selection for the QTL is possible,but the inverse effect on protein and oil content should be kept in mind.

关键词： QTL mapping Soybean Protein content Oil content

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A machine-learned interatomic potential for silica and its relation to empirical models

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npj Computational Materials 2022年第1期8卷 822-833页

作者： Linus C.Erhard Jochen Rohrer Karsten Albe volker L.Deringer Institute of Materials Science Technische Universität DarmstadtOtto-Berndt-Strasse 364287DarmstadtGermany Department of Chemistry Inorganic Chemistry LaboratoryUniversity of OxfordOxfordOX13QRUK

Silica(SiO_(2))is an abundant material with a wide range of *** much progress,the atomistic modelling of the different forms of silica has remained a *** we show that by combining density-functional theory at the SCAN functional level with machine-learning-based interatomic potential fitting,a range of condensed phases of silica can be accurately *** present a Gaussian approximation potential model that achieves high accuracy for the thermodynamic properties of the crystalline phases,and we compare its performance(and performance–cost trade-off)with that of multiple empirically fitted interatomic potentials for *** also include amorphous phases,assessing the ability of the potentials to describe structures of melt-quenched glassy silica,their energetic stability,and the high-pressure structural transition to a mainly sixfold-coordinated *** suggest that rather than standing on their own,machine-learned potentials for silica may be used in conjunction with suitable empirical models,each having a distinct role and complementing the other,by combining the advantages of the long simulation times afforded by empirical potentials and the near-quantum-mechanical accuracy of machine-learned *** way,our work is expected to advance atomistic simulations of this key material and to benefit further computational studies in the field.

关键词： potential empirical relation

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