ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 1417-1422 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The average value of the magnetocrystalline anisotropy field, Hk, is an important parameter for the characterization of magnetic recording media but is difficult to measure accurately due in part to the effect of interactions between the grains. In order to evaluate Hk we have studied two model CoCrPtTa magnetic films using a number of complementary techniques: high field ferromagnetic resonance (FMR) (35.0–45.0 kOe), low field (〈20 kOe) vector vibrating-sample magnetometry and torque magnetometry. The FMR measurements were performed at a number of discrete frequencies in the range 75–93 GHz using a new quasi-optical spectrometer developed at the University of St. Andrews. The values of Hk derived by FMR (10.8 kOe) are approximately 10% greater than those obtained from conventional magnetometry (9.6 kOe). This difference is believed to be due to the presence of intergranular exchange coupling which reduces the measured value of anisotropy when the applied field is not sufficiently large to completely align the magnetic moments. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Publication Date: 2002-02-01
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Publication Date: 2003-11-15
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Publication Date: 2015-10-27
    Description: A microorganism of the Marinobacter genus capable of Fe-oxidation at near-neutral pH, both in the presence and absence of oxygen, was found at a depth of 1.4 km in proximity to a Cu-Zn Volcanogenic Massive Sulphide (VMS) deposit, within the Triple 7 mine, Flin Flon, Manitoba, Canada. The microorganism was isolated from saline groundwater emanating from boreholes at that depth, which contained a small microbial community consisting of only two organisms. To examine biogeochemical trace metal cycling in this deep subsurface setting, incubation experiments were carried out with the Marinobacter isolate and mineralized (metal-containing ore) material in batch and column flow-through settings. The activity of the Marinobacter isolate resulted in an increase in the mobilization of major elements (Fe, S) and trace metals (Cu, Zn) from the solid ore material. These results indicate that Fe-oxidation may be an important biogeochemical process in the deep subsurface, which affects the mobilization of Fe and trace elements from buried mineralization.
    Print ISSN: 1467-7873
    Electronic ISSN: 1467-7873
    Topics: Chemistry and Pharmacology , Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Publication Date: 2015-02-04
    Description: Geochemistry is a key tool in identifying sources of elements for both mineral exploration and environmental purposes. This study evaluates the first systematic regional hydrogeochemical survey for environmental assessments of the classic Andean copper mineral province and the Andina–Los Bronces mining district of Central Chile. One hundred and forty-five water samples were collected systematically in the Valparaíso and Metropolitana Regions of Central Chile, including the capital, Santiago. The concentrations of more than 70 elements and compounds were determined using inductively coupled plasma mass spectrometry (ICP-MS) and ion chromatography (IC) along with the stable isotopes (D, 18 O, 34 S, 18 O SO4 , 15 N and 18 O NO3 ) and used to define the geochemical baselines in the area and distinguish between different sources. The geochemistry demonstrates the potential to distinguish between natural (bedrock, hydrothermal alteration and mineralization) and anthropogenic (agriculture, sewage and urban) sources of elements. The distribution patterns of many chemicals show a strong correlation with the presence of evaporitic components (Ca, SO 4 2- , Sr, K, Rb, total dissolved solids (TDS)), hydrothermal alteration and sulphide mineralization (Cu, Zn, Ni, Cd, Co and REEs). High concentrations of nitrate, phosphate and alkalinity occur downstream of agricultural areas and reflect pollution from fertilizers. Overall, the catchment areas affected by mining activities are relatively small and highly localized compared to those affected by agriculture and urban centres. Supplementary material: A list of anomalously high element concentrations and specific isotopic compositions associated by source is available at: http://www.geolsoc.org.uk/SUP18799
    Print ISSN: 1467-7873
    Electronic ISSN: 1467-7873
    Topics: Chemistry and Pharmacology , Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Publication Date: 2015-02-04
    Description: Eleven partial extraction methods were assessed for their exploration utility on 15 soil samples from a one-kilometre transect over the Palaeoproterozoic Talbot VMS occurrence that is hosted by metamorphic sequences of the Flin Flon-Snow Lake terrane and overlain by 100 m of Palaeozoic dolomites and up to 2 m of Quaternary glacial sediments. Student’s t- test statistics and t- distribution probabilities (P t ) were calculated to evaluate the magnitude and spatial accuracy of anomalies in each dataset. In the surface soil that was analysed, Zn anomalies have the greatest contrast by most methods, followed by P and Cd, albeit mostly restricted to a strong anomaly at a fault zone that is laterally offset c. 100 m from the projection of mineralization. Extraction methods with significant anomaly contrast in decreasing order of exploration utility are Enzyme Leach, deionized water, sodium pyrophosphate, MMI, and ammonium acetate at pH 7. Weaker leaches generate anomalies with greater contrast than stronger acid digests of the soils, which tend to dissolve the sample matrix and overwhelm the secondary signal from adsorbed species of ore indicator elements. Aqua regia digestions on the clay fraction extracted from the soil also have greater contrast than most soil digestions for ore-indicator elements. Continuous-leach ICP-MS analysis of the Talbot soil provides detailed phase relationships that indicate the presence of labile Zn present as organic complexes in anomalous soil over the fault, and the absence of such secondary Zn species in background soil, in which most Zn is released from carbonate dissolution.
    Print ISSN: 1467-7873
    Electronic ISSN: 1467-7873
    Topics: Chemistry and Pharmacology , Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Publication Date: 2013-02-14
    Description: A simple and fast method, using solid sampling electrothermal vapourization inductively coupled plasma optical emission spectrometry (ETV-ICP-OES), was developed to determine the distribution of elements in clay separates and soil samples from across the Talbot Lake VMS Cu-Zn prospect, in the Flin Flon-Snow Lake terrane, Manitoba, Canada in order to locate the undercover ore deposit, which is buried under Palaeozoic dolomites and Quaternary till. In the development of the method, the mass of sample, the mass of carrier agent (polytetrafluoroethylene, PTFE) or flow rate of reactant gas (dichlorodifluoromethane (R12)), the carrier and bypass gas flow rates and the temperature program were optimised. Under optimal conditions and with a four-step ETV temperature program, the distribution of the pathfinder elements (Zn, P, S and I) in clay separates and soils showed clear anomalies at 400 and 650 m. The results for Zn and P are in very good agreement with results obtained, following aqua regia (AR) digestion, by ICP mass spectrometry (ICP-MS) by Anglo American Exploration Division (AA-ED). Moreover, the distributions of S and I could be precisely determined (these elements were not reported in the AA-ED study). Using 0–4 mg of AA-ED S5 standard mixed with 2 mg PTFE or with 4.1 ml/min R12 as reactant gas, and using internal standardisation with an argon emission line, calibration curves were obtained that, when applied to Talbot clay separates and soil samples, yielded Zn, S and P concentrations in agreement with AR-ICP-MS results previously obtained by AA-ED. Hence, ETV-ICP-OES completely eliminates the need for clay separation and for extraction or digestion of samples prior to analysis, which significantly simplifies the analysis of geochemical exploration samples.
    Print ISSN: 1467-7873
    Electronic ISSN: 1467-7873
    Topics: Chemistry and Pharmacology , Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Publication Date: 2013-02-14
    Description: Two size fractions of till, 〈250 μm and 〈2 μm, humus, moss and black spruce bark, as well as sulphides, host rocks and Palaeozoic cover dolostone from drill cores were sampled at the Talbot Lake volcanogenic massive sulphide (VMS) prospect in the Flin Flon-Snow Lake terrane, Manitoba, Canada. Lead isotope-ratios in organic surface media indicate significant input of anthropogenic Pb from the Flin Flon smelter at 160 km distance to the northwest, with 206 Pb/ 204 Pb between 16.5 and 18.2, whereas background till and upper dolostone range between 21.6 and 23.1. At deeper levels, the influx of Pb from Proterozoic mineralization from greater than 100 m depth is recognized. Strontium isotope ratios in these media indicate enhanced vertical fluid flow in the till cover at a fault zone, coincident with the Pb isotope anomaly, as well as relative contributions of Sr from carbonates, silicates and vegetation to the till profile. In humus, sphagnum moss and black spruce bark, the Pb isotope ratios are progressively more similar to that of the feed of the Flin Flon smelter. Measurements of Pb and Sr isotope ratios reveal that Pb from Proterozoic mineralization situated beneath 100 m of Palaeozoic dolostone can be distinguished from Pb contributed by anthropogenic and other geogenic sources.
    Print ISSN: 1467-7873
    Electronic ISSN: 1467-7873
    Topics: Chemistry and Pharmacology , Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 2012-09-08
    Description: Motivation: Network inference approaches are widely used to shed light on regulatory interplay between molecular players such as genes and proteins. Biochemical processes underlying networks of interest (e.g. gene regulatory or protein signalling networks) are generally nonlinear. In many settings, knowledge is available concerning relevant chemical kinetics. However, existing network inference methods for continuous, steady-state data are typically rooted in statistical formulations, which do not exploit chemical kinetics to guide inference. Results: Herein, we present an approach to network inference for steady-state data that is rooted in non-linear descriptions of biochemical mechanism. We use equilibrium analysis of chemical kinetics to obtain functional forms that are in turn used to infer networks using steady-state data. The approach we propose is directly applicable to conventional steady-state gene expression or proteomic data and does not require knowledge of either network topology or any kinetic parameters. We illustrate the approach in the context of protein phosphorylation networks, using data simulated from a recent mechanistic model and proteomic data from cancer cell lines. In the former, the true network is known and used for assessment, whereas in the latter, results are compared against known biochemistry. We find that the proposed methodology is more effective at estimating network topology than methods based on linear models. Availability: mukherjeelab.nki.nl/CODE/GK_Kinetics.zip Contact: c.j.oates@warwick.ac.uk ; s.mukherjee@nki.nl Supplementary Information: Supplementary data are available at Bioinformatics online.
    Print ISSN: 1367-4803
    Electronic ISSN: 1460-2059
    Topics: Biology , Computer Science , Medicine
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Publication Date: 2014-08-27
    Description: Motivation: Networks are widely used as structural summaries of biochemical systems. Statistical estimation of networks is usually based on linear or discrete models. However, the dynamics of biochemical systems are generally non-linear, suggesting that suitable non-linear formulations may offer gains with respect to causal network inference and aid in associated prediction problems. Results: We present a general framework for network inference and dynamical prediction using time course data that is rooted in non-linear biochemical kinetics. This is achieved by considering a dynamical system based on a chemical reaction graph with associated kinetic parameters. Both the graph and kinetic parameters are treated as unknown; inference is carried out within a Bayesian framework. This allows prediction of dynamical behavior even when the underlying reaction graph itself is unknown or uncertain. Results, based on (i) data simulated from a mechanistic model of mitogen-activated protein kinase signaling and (ii) phosphoproteomic data from cancer cell lines, demonstrate that non-linear formulations can yield gains in causal network inference and permit dynamical prediction and uncertainty quantification in the challenging setting where the reaction graph is unknown. Availability and implementation: MATLAB R2014a software is available to download from warwick.ac.uk/chrisoates. Contact: c.oates@warwick.ac.uk or sach@mrc-bsu.cam.ac.uk Supplementary information: Supplementary data are available at Bioinformatics online.
    Print ISSN: 1367-4803
    Electronic ISSN: 1460-2059
    Topics: Biology , Computer Science , Medicine
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...