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21.
Prof. Dr. B. Hock 《洁净——土壤、空气、水》1993,21(2):71-83
Enzyme immunoassays profit from the unique properties of antibodies concerning their selectivity and affinity towards ligands, e.g. pesticides. The most commonly applied types belong to the class of competitive immunoassays with phase separation such as the ELISA. The principle is explained and illustrated using an atrazine assay as a representative example. Common error sources, especially cross-reactivities and matrix effects, are discussed. Interlaboratory tests demonstrate the presently available quality of enzyme immunoassays. An outlook is given on future developments. 相似文献
22.
Frank Drewnick Johannes Schneider Silke S. Hings Nele Hock Kevin Noone Admir Targino Silke Weimer Stephan Borrmann 《Journal of Atmospheric Chemistry》2007,56(1):1-20
The Aerodyne aerosol mass spectrometer (Q-AMS) was coupled with a counterflow virtual impactor (CVI) for the first time to measure cloud droplet residuals of warm tropospheric clouds on Mt. Åreskutan in central Sweden in July 2003. Operating the CVI in different operational modes generated mass concentration and species-resolved mass distribution data for non-refractory species of the ambient, interstitial, and residual aerosol. The ambient aerosol measurements revealed that the aerosol at the site was mainly influenced by long-range transport and regional photochemical generation of nitrate and organic aerosol components. Four different major air masses were identified for the time interval of the experiment. While two air masses that approached the site from northeastern Europe via Finland showed very similar aerosol composition, the other two air masses from polar regions and the British Islands had a significantly different composition. During cloud events the larger aerosol particles were found to be activated into cloud droplets. On a mass basis the activation cut-off diameter was approximately 150 nm for nitrate and organics dominated particles and 200 nm for sulfate dominated particles. Generally nitrate and organics were found to be activated into cloud droplets with higher efficiency than sulfate. While a significant fraction of the nitrate in ambient particles was organic nitrates or nitrogen-containing organic species, the nitrate found in the cloud droplet residuals was mainly ammonium nitrate. After passage of clouds the ambient aerosol size distribution had shifted to smaller particle sizes due to the predominantly activation of larger aerosol particles without a significant change in the relative composition of the ambient aerosol. 相似文献
23.
The tendency of several pesticides to form non-extractable residues requires simple and fast screening methods. Immunochemical methods can meet this demand. They are based on selective and highly sensitive antibody binding to pesticide residues exposed on refractory organic substances (ROS). s-Triazines were used as an example to show the feasibility of this approach. It was proven that under laboratory conditions atrazine was bound to ROS. Antibody recognition pointed to the availability of free ethyl and isopropyl groups exposed at the non-extractable s-triazine residue. Therefore, it is suggested on the basis of antibody selectivities that binding of atrazine to ROS may take place by substitution of the chlorine residue. In the next step, aquatic ROS isolated from surface waters located in an agricultural area were examined for non-extractable s-triazines. ROS from a lake were found to contain bound residues, whereas none were detected in the creek samples. As an outlook the feasibility of serological characterization of ROS is discussed. The novel concept of serotyping is based on the fractionation of ROS by electrophoretic techniques followed by an immunoreaction with polyclonal antibodies directed against different ROS. When immunoelectrophoresis is used, precipitation lines can be compared and checked for identity and cross-reactivity. This approach can form the basis for classifying ROS and determine similarities with unknown ROS. 相似文献
24.
In order to compute the specific mass balance of a glacier, point measurements of mass balance need to be integrated and thus interpolated over the entire glacier. In this study kriging was applied as interpolation technique to mass balance data of Storglaciren, a 3 km2 valley glacier, focusing on the sensitivity of results to the choice of some kriging parameters. Although the spatial means varied only little in most cases, the spatial distribution of the mass balance quantities was sensitive to the assumption on kriging parameters, suggesting that the kriging parameters need to be carefully optimized for each case if the spatial distribution is of interest. 相似文献
25.
Regional and global projections of twenty-first century glacier mass changes in response to climate scenarios from global climate models 总被引：1，自引：0，他引：1
Valentina Radić Andrew Bliss A. Cody Beedlow Regine Hock Evan Miles J. Graham Cogley 《Climate Dynamics》2014,42(1-2):37-58
A large component of present-day sea-level rise is due to the melt of glaciers other than the ice sheets. Recent projections of their contribution to global sea-level rise for the twenty-first century range between 70 and 180 mm, but bear significant uncertainty due to poor glacier inventory and lack of hypsometric data. Here, we aim to update the projections and improve quantification of their uncertainties by using a recently released global inventory containing outlines of almost every glacier in the world. We model volume change for each glacier in response to transient spatially-differentiated temperature and precipitation projections from 14 global climate models with two emission scenarios (RCP4.5 and RCP8.5) prepared for the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. The multi-model mean suggests sea-level rise of 155 ± 41 mm (RCP4.5) and 216 ± 44 mm (RCP8.5) over the period 2006–2100, reducing the current global glacier volume by 29 or 41 %. The largest contributors to projected global volume loss are the glaciers in the Canadian and Russian Arctic, Alaska, and glaciers peripheral to the Antarctic and Greenland ice sheets. Although small contributors to global volume loss, glaciers in Central Europe, low-latitude South America, Caucasus, North Asia, and Western Canada and US are projected to lose more than 80 % of their volume by 2100. However, large uncertainties in the projections remain due to the choice of global climate model and emission scenario. With a series of sensitivity tests we quantify additional uncertainties due to the calibration of our model with sparsely observed glacier mass changes. This gives an upper bound for the uncertainty range of ±84 mm sea-level rise by 2100 for each projection. 相似文献
26.
Yaqiong Liu Hock Soon Seah 《International journal of geographical information science》2013,27(6):953-979
Recently, points of interest (POIs) recommendation has evolved into a hot research topic with real-world applications. In this paper, we propose a novel semantics-enhanced density-based clustering algorithm SEM-DTBJ-Cluster, to extract semantic POIs from GPS trajectories. We then take into account three different factors (popularity, temporal and geographical features) that can influence the recommendation score of a POI. We characterize the impacts caused by popularity, temporal and geographical information, by using different scoring functions based on three developed recommendation models. Finally, we combine the three scoring functions together and obtain a unified framework PTG-Recommend for recommending candidate POIs for a mobile user. To the best of our knowledge, this work is the first that considers popularity, temporal and geographical information together. Experimental results on two real-world data sets strongly demonstrate that our framework is robust and effective, and outperforms the baseline recommendation methods in terms of precision and recall. 相似文献
27.
T. N. Woods F. G. Eparvier R. Hock A. R. Jones D. Woodraska D. Judge L. Didkovsky J. Lean J. Mariska H. Warren D. McMullin P. Chamberlin G. Berthiaume S. Bailey T. Fuller-Rowell J. Sojka W. K. Tobiska R. Viereck 《Solar physics》2012,275(1-2):115-143
The highly variable solar extreme ultraviolet (EUV) radiation is the major energy input to the Earth’s upper atmosphere, strongly impacting the geospace environment, affecting satellite operations, communications, and navigation. The Extreme ultraviolet Variability Experiment (EVE) onboard the NASA Solar Dynamics Observatory (SDO) will measure the solar EUV irradiance from 0.1 to 105?nm with unprecedented spectral resolution (0.1?nm), temporal cadence (ten seconds), and accuracy (20%). EVE includes several irradiance instruments: The Multiple EUV Grating Spectrographs (MEGS)-A is a grazing-incidence spectrograph that measures the solar EUV irradiance in the 5 to 37?nm range with 0.1-nm resolution, and the MEGS-B is a normal-incidence, dual-pass spectrograph that measures the solar EUV irradiance in the 35 to 105?nm range with 0.1-nm resolution. To provide MEGS in-flight calibration, the EUV SpectroPhotometer (ESP) measures the solar EUV irradiance in broadbands between 0.1 and 39?nm, and a MEGS-Photometer measures the Sun’s bright hydrogen emission at 121.6?nm. The EVE data products include a near real-time space-weather product (Level?0C), which provides the solar EUV irradiance in specific bands and also spectra in 0.1-nm intervals with a cadence of one minute and with a time delay of less than 15?minutes. The EVE higher-level products are Level?2 with the solar EUV irradiance at higher time cadence (0.25?seconds for photometers and ten seconds for spectrographs) and Level?3 with averages of the solar irradiance over a day and over each one-hour period. The EVE team also plans to advance existing models of solar EUV irradiance and to operationally use the EVE measurements in models of Earth’s ionosphere and thermosphere. Improved understanding of the evolution of solar flares and extending the various models to incorporate solar flare events are high priorities for the EVE team. 相似文献
28.
A. BenMoussa S. Gissot U. Schühle G. Del Zanna F. Auchère S. Mekaoui A. R. Jones D. Walton C. J. Eyles G. Thuillier D. Seaton I. E. Dammasch G. Cessateur M. Meftah V. Andretta D. Berghmans D. Bewsher D. Bolsée L. Bradley D. S. Brown P. C. Chamberlin S. Dewitte L. V. Didkovsky M. Dominique F. G. Eparvier T. Foujols D. Gillotay B. Giordanengo J. P. Halain R. A. Hock A. Irbah C. Jeppesen D. L. Judge M. Kretzschmar D. R. McMullin B. Nicula W. Schmutz G. Ucker S. Wieman D. Woodraska T. N. Woods 《Solar physics》2013,288(1):389-434
We present the lessons learned about the degradation observed in several space solar missions, based on contributions at the Workshop about On-Orbit Degradation of Solar and Space Weather Instruments that took place at the Solar Terrestrial Centre of Excellence (Royal Observatory of Belgium) in Brussels on 3 May 2012. The aim of this workshop was to open discussions related to the degradation observed in Sun-observing instruments exposed to the effects of the space environment. This article summarizes the various lessons learned and offers recommendations to reduce or correct expected degradation with the goal of increasing the useful lifespan of future and ongoing space missions. 相似文献
29.
Chu Ling Heng Ong Hock Peng Paul Ponar Sinjeng Askury Ab. Kadir Kamuradin Md. Slar Sharifah Chu Ismail 《Journal of Asian Earth Sciences》1997,15(6):477
Medium- to coarse-grained leucocratic granitic bodies containing more than 60% feldspar and less than 10% mafic minerals are found to be appropriate and potential source materials of local feldspar. Out of the 72 granite quarries/outcrops studied in Peninsular Malaysia, 31 have been identified as “ideal” sources of feldspar conforming to the “preferred” feldspar specification of >18% Al2O3, >11% (Na2O+K2O) and <0.3% Fe2O3. A feldspar recovery efficiency exceeding 60% was achieved in this study. Despite the positive and encouraging indication that the extracted feldspar samples of different chemical composition are found to be suitable for the general purpose of making ceramic bodies and glaze, the chemical content of the feldspar, nevertheless, could be critical for the manufacture of specific end products. At 1250°C all extracted feldspar samples were fused; however, at the lower temperature of 1170°C feldspar samples extracted from some “Central Belt granites” remained unfused. The Eastern Province granites generally yielded feldspars which show better fusion characteristics i.e. (unblemished) than those extracted from the Main Range Province. A valuable by-product of the feldspar extraction process is silica sand. 相似文献
30.
The chromitite-bearing peridotites of the Zambales mafic-ultramafic complex form the lowermost level of the Zambales ophiolite, which exposes a complete ophiolitic sequence. The chromitites occur close to the peridotite/gabbro transition zone.The chromite orebodies are structurally classified into three major types: (1) concordant tabular deposits, (2) strings of pods and (3) pocketlike deposits.Concordant tabular deposits show a gradational transition from chromitite to host rock (modal grading) and are characterized by the parallelism of ore and host-rock structures. Primary magmatic features like inch-scale layering, size grading, glomeroporphyric chromite aggregates, skeletal chromite growth and adcumulus growth (cumulus textures) are common.The concordant chromite bodies are often tectonically disrupted and boudined forming strings of pods or fault-controlled pocketlike deposits. With increasing tectonization chromite shows pull-apart textures and lineations (plastic deformation), shearing, prismatic jointing, brecciation and mylonitization (brittle deformation). Recrystallization of cataclastic chromite occurs on a microscopic scale.Plastic deformation is caused by mantle flow and/or the volume increase of the peridotites during serpentinization. The influence of mantle flow is indicated by the orientation of the pod strings and lineations in chromitite perpendicular to the ridge axis. Brittle deformation of chromite (cataclasis) and disruption by faults is related to the emplacement of the ophiolite. 相似文献