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  • Recombinant DNA  (3.203)
  • HPLC  (747)
  • Instrumentation
  • Elsevier  (3.952)
  • American Chemical Society  (1)
  • Inter-Research  (1)
  • American Chemical Society (ACS)
  • 1
    Publikationsdatum: 2017-04-04
    Beschreibung: Inter-laboratory and absolute calibrations of rock magnetic parameters are fundamental for grounding a rock magnetic database and for semi-quantitative estimates about the magnetic mineral assemblage of a natural sample. Even a dimensionless ratio, such as anhysteretic susceptibility normalized by magnetic susceptibility (Ka/K) may be biased by improper calibration of one or both of the two instruments used to measure Ka and K. In addition, the intensity of the anhysteretic remanent magnetization (ARM) of a given sample depends on the experimental process by which the remanence is imparted. We report an inter-laboratory calibration of these two key parameters, using two sets of artificial reference samples: a paramagnetic rare earth salt, Gd2O3 and a commercial "pozzolanico" cement containing oxidized magnetite with grain size of less than 0.1 m according to hysteresis properties. Using Gd2O3 the 10 Kappabridges magnetic susceptibility meters (AGICO KLY-2 or KLY-3 models) tested prove to be cross-calibrated to within 1%. On the other hand, Kappabridges provide a low-field susceptibility value that is ca. 6% lower than the tabulated value for Gd2O3, while average high-field susceptibility values measured on a range of instruments are indistinguishable from the tabulated value. Therefore, we suggest that Kappabridge values should be multiplied by 1.06 to achieve absolute calibration. Bartington Instruments magnetic susceptibility meters with MS2B sensors produce values that are 2–13% lower than Kappabridge values, with a strong dependence on sample centering within the sensor. The Ka/K ratio of ca. 11, originally obtained on discrete cement samples with a 2G Enterprises superconducting rock magnetometer and a KLY-2, is consistent with reference parameters for magnetites of grain size 〈0.1 m. On the other hand, Ka values from a 2G Enterprises magnetometer and K values from a Bartington Instruments MS2C loop sensor for u-channel and discrete cement samples, will produce average Ka/K values that are unrealistically high if not properly corrected for the nominal volume detected by the sensors for these instruments. Inter-laboratory measurements of K and Ka for standard paleomagnetic plastic cubes filled with cement indicate remarkable differences in the intensity of the newly produced ARMs (with a standard deviation of ca. 21%), that are significantly larger than the differences observed from the calibration of the different magnetometers employed in each laboratory. Differences in the alternating field decay rate are likely the major source of these variations, but cannot account for all the observed variability. With such large variations in experimental conditions, classical interpretation of a "King plot" of Ka versus K would imply significant differences in the determination of grain size of magnetite particles on the same material.
    Beschreibung: Published
    Beschreibung: 25-38
    Beschreibung: 2.2. Laboratorio di paleomagnetismo
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Rock magnetism ; Magnetic susceptibility ; Anhysteretic remanent magnetization ; Calibration ; Instrumentation ; Relative ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.08. Instruments and techniques
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © Inter-Research, 2009. This article is posted here by permission of Inter-Research for personal use, not for redistribution. The definitive version was published in Aquatic Microbial Ecology 54 (2009): 127-133, doi:10.3354/ame01261.
    Beschreibung: Quorum sensing (QS) via acylated homoserine lactones (AHLs) was discovered in the ocean, yet AHLs are expected to be very short-lived at seawater pH due to rapid abiotic degradation. Quorum quenching, the enzymatic degradation of AHLs, is also likely. To better understand the potential for QS to regulate behaviors of marine bacteria, we investigated the degradation of a variety of AHL molecules in several types of seawater media. We did this by incubating AHLs and tracking their concentration using HPLC/electrospray-ionization mass-spectrometry (HPLC/ESI-MS). AHL concentrations decreased with time, and degradation rate coefficients were calculated by applying a first-order rate law. The rate of abiotic degradation showed strong dependence on acyl chain length and the presence of 3-oxo substitutions on the acyl chain. We found that the rate of abiotic degradation of AHLs in artificial seawater was much slower than that predicted by an oft-cited equation for non-marine media that takes only pH into account. However, AHLs degraded more rapidly in natural seawater than in artificial seawater, an observation we found to be due to quorum quenching enzyme activity. By applying calculated degradation rates in a simple steady-state calculation, we suggest that despite the observed quorum quenching activity, AHLs are likely to be viable signals in organic particles and in other microbial ‘hotpsots’ in marine environments.
    Beschreibung: This work was funded by a grant from the Office of Naval Research to B.A.S.V.M. (N0014-06-1-0134), and an NSF Graduate Student Fellowship to L.H.
    Schlagwort(e): Quorum sensing ; Quorum quenching ; Marine bacteria ; Acylated homoserine lactone ; HPLC ; Mass spectrometry ; Degradation
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Publikationsdatum: 2022-10-21
    Beschreibung: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Colson, B. C., & Michel, A. P. M. Flow-through quantification of microplastics using impedance spectroscopy. ACS Sensors, 6(1), (2021): 238–244, doi:10.1021/acssensors.0c02223.
    Beschreibung: Understanding the sources, impacts, and fate of microplastics in the environment is critical for assessing the potential risks of these anthropogenic particles. However, our ability to quantify and identify microplastics in aquatic ecosystems is limited by the lack of rapid techniques that do not require visual sorting or preprocessing. Here, we demonstrate the use of impedance spectroscopy for high-throughput flow-through microplastic quantification, with the goal of rapid measurement of microplastic concentration and size. Impedance spectroscopy characterizes the electrical properties of individual particles directly in the flow of water, allowing for simultaneous sizing and material identification. To demonstrate the technique, spike and recovery experiments were conducted in tap water with 212–1000 μm polyethylene beads in six size ranges and a variety of similarly sized biological materials. Microplastics were reliably detected, sized, and differentiated from biological materials via their electrical properties at an average flow rate of 103 ± 8 mL/min. The recovery rate was ≥90% for microplastics in the 300–1000 μm size range, and the false positive rate for the misidentification of the biological material as plastic was 1%. Impedance spectroscopy allowed for the identification of microplastics directly in water without visual sorting or filtration, demonstrating its use for flow-through sensing.
    Beschreibung: The authors thank the Richard Saltonstall Charitable Foundation and the National Academies Keck Futures Initiative (NAKFI DBS13) for their funding support.
    Schlagwort(e): Microplastics ; Plastics ; Impedance spectroscopy ; Dielectric properties ; Instrumentation ; Particle detection ; Flow-through ; Environmental sensing
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Gene Structure and Expression 1088 (1991), S. 31-35 
    ISSN: 0167-4781
    Schlagwort(e): DNA-binding protein) ; Fusion gene ; Gene regulation ; Immunoblot assay ; Recombinant DNA ; Transcription
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Chemie und Pharmazie , Medizin , Physik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Gene Structure and Expression 1132 (1992), S. 233-239 
    ISSN: 0167-4781
    Schlagwort(e): Cephalosporin acylase ; Gene' structure ; Recombinant DNA ; γ-Glutamyltranspeptidase
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Chemie und Pharmazie , Medizin , Physik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    ISSN: 0003-2697
    Schlagwort(e): HPLC ; catecholamine-derived alkaloids ; electrochemical detection ; neurochemistry ; quantification in rat brain ; tetrahydropapaveroline
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Chemie und Pharmazie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Analytical Biochemistry 161 (1987), S. 16-19 
    ISSN: 0003-2697
    Schlagwort(e): 3-hydroxykynurenine ; HPLC ; electrochemical detection ; kynurenine ; kynurenine 3-hydroxylase ; serum
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Chemie und Pharmazie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Analytical Biochemistry 135 (1983), S. 312-317 
    ISSN: 0003-2697
    Schlagwort(e): HPLC ; brain ; dansylation ; nipecotic acid ; pipecolic acid
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Chemie und Pharmazie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Analytical Biochemistry 138 (1984), S. 396-403 
    ISSN: 0003-2697
    Schlagwort(e): HPLC ; fluoroditrobenzene ; hydrogen selenide ; mass spectrometry ; methyl selenol ; volatile selenium
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Chemie und Pharmazie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Analytical Biochemistry 161 (1987), S. 181-186 
    ISSN: 0003-2697
    Schlagwort(e): HPLC ; anionic oligosaccharides ; degree of polymerization ; polysialic acid
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Chemie und Pharmazie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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