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  • 1
  • 2
    In: Water Resources Research, April 2009, Vol.45(4), pp.n/a-n/a
    Description: High‐resolution optical bench‐scale experiments were conducted in order to investigate local gas flow pattern and integral flow properties caused by point‐like gas injection into water‐saturated glass beads. The main goal of this study was to test the validity of the continuum approach for two‐fluid flow in macroscopic homogeneous media. Analyzing the steady state experimental gas flow pattern that satisfies the necessary coherence condition by image processing and calibrating the optical gas distribution by the gravimetrical gas saturation, it was found that a pulse‐like function yields the best fit for the lateral gas saturation profile. This strange behavior of a relatively sharp saturation transition is in contradiction to the widely anticipated picture of a smooth Gaussian‐like transition, which is obtained by the continuum approach. This transition is caused by the channelized flow structure, and it turns out that only a narrow range of capillary pressure is realized by the system, whereas the continuum approach assumes that within the representative elementary volume the whole spectrum of capillary pressures can be realized. It was found that the stochastical hypothesis proposed by Selker et al. (2007) that bridges pore scale and continuum scale is supported by the experiments. In order to study channelized gas flow on the pore scale, a variational treatment, which minimizes the free energy of an undulating capillary, was carried out. On the basis of thermodynamical arguments the geometric form of a microcapillary, macrochannel formation and a length‐scale‐dependent transition in gas flow pattern from coherent to incoherent flow are discussed.
    Keywords: Air Sparging ; Continuum Modeling ; Pore‐Scale Modeling ; Gas Flow Pattern ; Instability Analysis ; Image Processing
    ISSN: 0043-1397
    E-ISSN: 1944-7973
    Source: John Wiley & Sons, Inc.
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  • 3
    In: Water Resources Research, July 2006, Vol.42(7), pp.n/a-n/a
    Description: The transition from incoherent to coherent buoyancy‐driven gas flow is investigated in two‐dimensional tanks filled with glass beads using a high‐resolution optical‐gravimetrical setup. Both a grain‐size ()‐ and flow rate ()‐dependent transition are observed in the gas flow pattern. Standard quasistatic criteria do not explain the experimental results, since they do not take into account the competition between stabilizing friction forces and destabilizing capillary and gravitational forces. Conceptualizing the steady state tortuous gas flow as core‐annulus flow and applying Hagen‐Poiseuille flow for a straight capillary, we propose a flow rate and grain‐size‐dependent stability criterion that accounts for the experimental results and is used to classify the experiments in a diagram.
    Keywords: Direct Gas Injection ; Two‐Dimensional Visualization Experiments ; Gas Injection ; Incoherent Gas Flow ; Coherent Gas Flow ; Stability Criterion
    ISSN: 0043-1397
    E-ISSN: 1944-7973
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  • 4
    In: Grundwasser, 9/1/2002, Vol.7(3), pp.146-155
    Description: Die in situ -Sanierung von KW-belasteten Aquiferen durch Direktinjektion reaktiver Gase basiert auf heterogenen Lösungsreaktionen zwischen Komponenten der Gas- und Wasserphase und auf dem Vermögen des Aquifers, Gase im Porenraum zu speichern (∼ 10 % des Porenraumes). Es werden die Grundgleichungen eines neuen kinetischen Modells (variable-volume-Modell) und die Ergebnisse der Säulenexperimente mit einem Ein-Komponenten-Gas zur Auflösungskinetik einer residualen Gasphase vorgestellt. Anhand von großskaligen Gasinjektionsexperimenten wird ein konsistentes Bild über die Entwicklung des gasdurchströmten Kapillarnetzwerkes entwickelt: Der Vergleich aus gemessenem und nach dem Ein-Kugel-Modell abgeschätzten Kapillardruck zeigt, dass die Entwicklung des Kapillarnetzwerkes von Korngerüstumordnungen begleitet sein muss, da sonst die geringen Kapillardrücke nicht erklärbar sind. Die experimentell nachgewiesene Linearität zwischen Volumenstrom und dynamischem Gasvolumen bedeutet, dass eine Erhöhung des Volumenstromes eine Ausweitung des Kapillarnetzwerkes bewirkt. In situ remediation techniques like oxygen sparging, air sparging or bio sparging are based on mass transfer reactions between multi-component phases and use the ability of the aquifer to capture gas phases of significant amount (∼ 10 % of the pore space). The governing equations of a new kinetic model (variable-volume model), and the results of column experiments on dissolution kinetics of a residual gas phase (one-component gas) are presented. A consistent picture of the vertical gas flow, of the stability and extension of the capillary network used by the gas flow is derived from large-scale lab experiments on gas injection: The comparison between the measured capillary pressure and the calculated one due to the pore size distribution, which was derived from sieve analysis (single-sphere-model), shows that the formation of the capillary network is accompanied by particle rearrangement. Otherwise the small measured capillary pressure are not explainable. The linearity between the gas flux and the dynamical gas phase volume proven by experiments means that an increase in the flux leads to an extension of the capillary network.
    Keywords: Environmental Sciences ; Geography;
    ISSN: 1430483X
    E-ISSN: 14321165
    Source: Springer (via CrossRef)
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  • 5
    Language: German
    In: Grundwasser, 2002, Vol.7(3), pp.146-155
    Description: Die in situ -Sanierung von KW-belasteten Aquiferen durch Direktinjektion reaktiver Gase basiert auf heterogenen Lösungsreaktionen zwischen Komponenten der Gas- und Wasserphase und auf dem Vermögen des Aquifers, Gase im Porenraum zu speichern (∼ 10 % des Porenraumes). Es werden die Grundgleichungen eines neuen kinetischen Modells (variable-volume-Modell) und die Ergebnisse der Säulenexperimente mit einem Ein-Komponenten-Gas zur Auflösungskinetik einer residualen Gasphase vorgestellt. Anhand von großskaligen Gasinjektionsexperimenten wird ein konsistentes Bild über die Entwicklung des gasdurchströmten Kapillarnetzwerkes entwickelt: Der Vergleich aus gemessenem und nach dem Ein-Kugel-Modell abgeschätzten Kapillardruck zeigt, dass die Entwicklung des Kapillarnetzwerkes von Korngerüstumordnungen begleitet sein muss, da sonst die geringen Kapillardrücke nicht erklärbar sind. Die experimentell nachgewiesene Linearität zwischen Volumenstrom und dynamischem Gasvolumen bedeutet, dass eine Erhöhung des Volumenstromes eine Ausweitung des Kapillarnetzwerkes bewirkt. In situ remediation techniques like oxygen sparging, air sparging or bio sparging are based on mass transfer reactions between multi-component phases and use the ability of the aquifer to capture gas phases of significant amount (∼ 10 % of the pore space). The governing equations of a new kinetic model (variable-volume model), and the results of column experiments on dissolution kinetics of a residual gas phase (one-component gas) are presented. A consistent picture of the vertical gas flow, of the stability and extension of the capillary network used by the gas flow is derived from large-scale lab experiments on gas injection: The comparison between the measured capillary pressure and the calculated one due to the pore size distribution, which was derived from sieve analysis (single-sphere-model), shows that the formation of the capillary network is accompanied by particle rearrangement. Otherwise the small measured capillary pressure are not explainable. The linearity between the gas flux and the dynamical gas phase volume proven by experiments means that an increase in the flux leads to an extension of the capillary network.
    ISSN: 1430-483X
    Source: Springer Science & Business Media B.V.
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  • 6
    Language: German
    Description: Zugl.: Freiberg (Sachsen), Techn. Universiẗat, Diss., 2007.
    Keywords: Grundwasserleiter. Grundwassersanierung.
    Source: Networked Digital Library of Theses and Dissertations
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  • 7
    In: Genetics, May, 2000, Vol.155(1), p.141
    Description: mod(mdg4), also known as E(var)3-93D, is involved in a variety of processes, such as gene silencing in position effect variegation (PEV), the control of gypsy insulator sequences, regulation of homeotic gene expression, and programmed cell death. We have isolated a large number of mod(mdg4) cDNAs, representing 21 different isoforms generated by alternative splicing. The deduced proteins are characterized by a common N terminus of 402 amino acids, including the BTB/POZ-domain. Most of the variable C termini contain a new consensus sequence, including four positioned hydrophobic amino acids and a [Cys.sub.2][His.sub.2] motif. Using specific antibodies for two protein isoforms, we demonstrate different distributions of the corresponding proteins on polytene chromosomes. Mutations in the genomic region encoding exons 1-4 show enhancement of PEV and homeotic transformation and affect viability and fertility. Homeotic and PEV phenotypes are enhanced by mutations in other trx-group genes. A transgene containing the common 5 [minutes] region of mod(mdg4) that is present in all splice variants known so far partially rescues the recessive lethality of mod(mdg4) mutant alleles. Our data provide evidence that the molecular and genetic complexity of mod(mdg4) is caused by a large set of individual protein isoforms with specific functions in regulating the chromatin structure of different sets of genes throughout development.
    Keywords: Drosophila ; Drosophila ; Position-Effect Variegation ; Gene Silencing ; Homeosis ; Nucleotide Sequence ; Chromatin ; Gene Regulation ; Position-Effect Variegation ; Gene Silencing ; Homeosis ; Nucleotide Sequence ; Chromatin ; Gene Regulation ; Mod(Mdg4) Gene ; E(Var)3-93d Gene ; Transposon Gypsy ; Mod(Mdg4) Gene ; E(Var)3-93d Gene ; Transposon Gypsy ; Insects/Arachnids ; Genes & Molecular Genetics ; Cdna ; Amino Acid Sequence Prediction ; Cdna ; Amino Acid Sequence Prediction ; E(Var)3-93d Gene ; Amino Acid Sequence Prediction ; Cdna ; Mod(Mdg4) Gene ; Transposon Gypsy;
    ISSN: 0016-6731
    E-ISSN: 19432631
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  • 8
    Language: English
    In: Journal of Pharmaceutical and Biomedical Analysis, 2010, Vol.53(3), pp.497-502
    Description: A toxic plant, (ssp. ), was found to have an inhibitory effect on Hedgehog (Hh), a developmental signaling pathway that has been shown to be active during development, in adult stem cells and in numerous human tumors. Based on earlier studies it was believed that the known Hh inhibitor cyclopamine was present in (ssp. ). Here we show that instead of cyclopamine, dihydroveratramine (DHV) was found in (ssp. ). These compounds are easily mistaken for each other, as both substances share the same molecular weight, and the same main MS/MS fragments. DHV was found to be a less potent Hh inhibitor compared to cyclopamine. This is the first reported occurrence of DVH in nature.
    Keywords: Hedgehog ; Dihydroveratramine ; Cyclopamine ; Veratrum Album ; LC–MS ; NMR ; Pharmacy, Therapeutics, & Pharmacology
    ISSN: 0731-7085
    E-ISSN: 1873-264X
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  • 9
    Language: English
    In: Genes & development, 01 December 2004, Vol.18(23), pp.2973-83
    Description: Histone lysine methylation is an epigenetic mark to index chromosomal subdomains. In Drosophila, H3-K9 di- and trimethylation is mainly controlled by the heterochromatic SU(VAR)3-9 HMTase, a major regulator of position-effect variegation (PEV). In contrast, H3-K27 methylation states are independently mediated by the Pc-group enzyme E(Z). Isolation of 19 point mutants demonstrates that the silencing potential of Su(var)3-9 increases with its associated HMTase activity. A hyperactive Su(var)3-9 mutant, pitkin(D), displays extensive H3-K9 di- and trimethylation within but also outside pericentric heterochromatin. Notably, mutations in a novel Su(var) gene, Su(var)3-1, severely restrict Su(var)3-9-mediated gene silencing. Su(var)3-1 was identified as "antimorphic" mutants of the euchromatic H3-S10 kinase JIL-1. JIL-1(Su(var)3-1) mutants maintain kinase activity and do not detectably impair repressive histone lysine methylation marks. However, analyses with seven different PEV rearrangements demonstrate a general role of JIL-1(Su(var)3-1) in controlling heterochromatin compaction and expansion. Our data provide evidence for a dynamic balance between heterochromatin and euchromatin, and define two distinct mechanisms for Su(var) gene function. Whereas the majority of Su(var)s encode inherent components of heterochromatin that can establish repressive chromatin structures [intrinsic Su(var)s], Su(var)3-1 reflects gain-of-function mutants of a euchromatic component that antagonize the expansion of heterochromatic subdomains [acquired Su(var)s].
    Keywords: Drosophila -- Genetics ; Drosophila Proteins -- Genetics ; Euchromatin -- Metabolism ; Heterochromatin -- Metabolism ; Methyltransferases -- Genetics
    ISSN: 0890-9369
    E-ISSN: 15495477
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  • 10
    Language: English
    In: Tectonophysics, 2016, Vol. 689, pp. 40-55
    Description: The 2.5 km deep scientific COSC-1 borehole (ICDP 5054-1-A) was successfully drilled with nearly complete core recovery during spring and summer of 2014. Downhole and on-core measurements through the targeted Lower Seve Nappe provide a comprehensive data set. An observed gradual increase in strain below 1700 m, with mica schists and intermittent mylonites increasing in frequency and thickness, is here interpreted as the basal thrust zone of the Lower Seve Nappe. This high strain zone was not fully penetrated at the total drilled depth and is thus greater than 800 m in thickness.To allow extrapolation of the results from downhole logging, core analysis and other experiments into the surrounding rock and to link these with the regional tectonic setting and evolution, three post-drilling high-resolution seismic experiments were conducted in and around the borehole. One of these, the first 3D seismic reflection land survey to target the nappe structures of the Scandinavian Caledonides, is presented here. It provides new information on the 3D geometry of structures both within the drilled Lower Seve Nappe and underlying rocks down to at least 9 km.The observed reflectivity correlates well with results from the core analysis and downhole logging, despite challenges in processing. Reflections from the uppermost part of the Lower Seve Nappe have limited lateral extent and varying dips, possibly related to mafic lenses or boudins of variable character within felsic rock. Reflections occurring within the high strain zone, however, are laterally continuous over distances of a kilometer or more and dip 10–15° towards the southeast. Reflections from structures beneath the high strain unit and the COSC-1 borehole can be followed through most of the seismic volume down to at least 9 km and have dips of varying degree, mainly in the east–west thrust direction of the orogen.
    Keywords: 3d Reflection Seismic ; Continental Scientific Deep Drilling ; Borehole Geophysics ; Collisional Orogeny In The Scandinavian Caledonides ; Seve Nappe Complex ; Shear Zones ; Natural Sciences ; Earth And Related Environmental Sciences ; Geophysics ; Naturvetenskap ; Geovetenskap Och Miljövetenskap ; Geofysik ; Geophysics With Specialization In Solid Earth Physics ; Geofysik Med Inriktning Mot Fasta Jordens Fysik
    ISSN: 0040-1951
    E-ISSN: 18793266
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