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  • 1
    Publication Date: 2015-05-15
    Description: Field studies suggested that the biogeochemical settings and community structures are substantial different between the central Northern South China Sea (NSCS) and the upstream Kuroshio Current (KC). In particular, the water column of KC is characterized by substantially lower nutrients and productivity but higher Trichodesmium abundance and nitrogen fixation compared to the NSCS. The mechanism driving the difference of the two marine ecosystems, however, remains inadequately understood. Here, a one-dimensional biogeochemical model was developed to simulate the long-term variability of lower-trophic planktonic ecosystem for two pelagic stations in the NSCS and the KC near the Luzon Strait. The physical model included the vertical mixing driven by air-sea interaction and the Ekman pumping induced by wind stress curl. The biological model was constructed by modifying a nitrogen-based NPZD model with the incorporation of phosphorus cycle and diazotroph nitrogen fixation. After validation by several field datasets, the model was used to study the impact of long-term physical forcing on ecosystem variability in the two distinct stations. Our results suggested that nutrient transport above nitracline during summer was largely controlled by vertical turbulent mixing, while Ekman pumping was important for nutrient transport below the nitracline. Our results also indicated that diazotroph community structure and N 2 fixation in the NSCS and the KC could be strongly influenced by physical processes through the impacts on vertical nutrient fluxes. The disadvantage of diazotroph in the NSCS in compared to the KC during the summer could be attributed to its high nitrate fluxes from subsurface leading to outcompete of diazotrophs by faster growing non-diazotroph phytoplankton. This article is protected by copyright. All rights reserved.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 2
    Publication Date: 2015-04-30
    Description: A multistep dry fractionation method for modification of palm oil was adopted to achieve a high iodine value (IV) of the obtained palm olein, herein denoted as top olein. The effect of the composition of palm oil top olein on the IV and on the crystallization properties was analyzed in detail. Thermal properties of a series of olein and stearin fractions were evaluated by means of differential scanning calorimetry upon cooling. The composition of triacylglycerols in the products was investigated by high-performance liquid chromatography. IV analysis was carried out to measure the degree of unsaturation in these oil samples. Finally, an innovative and reliable method was developed to determine the IV of palm oils by relating the thermal properties with IV. The results agree well with those obtained by the traditional American Oil Chemists' Society method. In the palm oil industry, the iodine value is normally determined by a titration method that uses toxic solvents. An innovative method is proposed to quickly determine the iodine value of oil samples. This approach can provide statistically similar results to those given by traditional official procedures, with the advantages of being extremely rapid and environmentally friendly.
    Print ISSN: 0930-7516
    Electronic ISSN: 1521-4125
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Published by Wiley
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  • 3
    Publication Date: 2015-12-29
    Description: Four moorings were deployed near “Dragon Flag”, an active hydrothermal vent in the valley of the Southwest Indian Ridge. The goal was to examine the variability of currents and temperature, which will guide the trajectory of spreading plumes. The mean current was cross-isobath, and the circulation was characterized by a sub-mesoscale circulation. Observed currents also showed fluctuations with periods of 1-15 days. The inferred phase speed and wavelength for the wave with a period of 4.4 days are 10.4 km⋅d −1 and 45.8km, respectively, which are consistent with the topographic Rossby wave theory. The persistent warming tendency with corresponding variation of salinity based on background θ - S properties may be caused by background circulation and divergence of the water column. The warming or cooling episodes were most likely as signatures of isopycnal surface depression or uplifting induced by the moving of mesoscale eddies. Well resolved rotary spectra exhibited important nonlinear interactions between inertial and semi-diurnal tide in the velocity and temperature records. Amplification of near-inertial currents in the near bottom are also exposed. These discoveries provided new evidence for the non-linear interaction and trapped near-inertial waves by the ridge, which occurred in the deep ocean of the Southern Hemisphere. Such nonlinear interaction may represent a significant energy loss pathway for the internal waves, and part of the decay of such motion would likely result in increased mixing to maintain the abyssal stratification. Enhanced near-inertial motions can play a major role for the local advection of hydrothermal plumes. This article is protected by copyright. All rights reserved.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 4
    Publication Date: 2011-03-15
    Description: A phytochemical investigation of Toona ciliata var. ciliata afforded three new polyynes, 1 – 3 . Their structures were elucidated on the basis of spectroscopic analysis and chemical methods. Only compound 3 exhibited potent cytotoxicity against the HL-60 cell line with an IC 50 value of 6.7±0.27 μ M .
    Print ISSN: 0018-019X
    Electronic ISSN: 1522-2675
    Topics: Chemistry and Pharmacology
    Published by Wiley
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  • 5
    Publication Date: 2019
    Description: Abstract Soil organic carbon (SOC) loss caused by wind erosion can profoundly impact carbon (C) balance in arid and semiarid regions. Nevertheless, previous researches mainly focused on the direct effect of wind erosion through removing surface soil only but ignored its indirect effects associated with soil nitrogen (N) loss and subsequent reductions of plant productivity. To better understand the wind erosion effect on SOC storage, we conducted a large‐scale field experiment by manipulating wind erosion at 371 sites in arid and semiarid regions of northwest China from 2014 to 2016. We further integrated an observation‐based empirical equation of wind erosion process into a terrestrial biogeochemical model to evaluate the direct and indirect effects of wind erosion on SOC storage in northwest China. The observed results showed that direct SOC losses increased linearly with the square of wind speed but decreased nonlinearly with soil water content. Over the 34 years (1980–2013), simulated cumulative SOC losses associated with wind erosion in northwest China were 27.47 Tg C, among which the indirect effects contributed to 2.68 Tg C (9.76%). The indirect effect of wind erosion initially enhanced SOC storage by decreasing heterotrophic respiration from 1984 to 1988 but decreased SOC pool by reducing net primary productivity due to soil N loss under the long‐term wind erosion scenario. This work, for the first time, quantified the indirect impact of wind erosion on SOC storage via feedback of suppressed plant productivity, which is crucial for the convincing assessment on SOC storage in arid and semiarid regions.
    Print ISSN: 2169-8953
    Electronic ISSN: 2169-8961
    Topics: Biology , Geosciences
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 6
    Publication Date: 2014-09-29
    Description: Artificial bee colony (ABC) algorithm has attracted much attention and has been applied to many scientific and engineering applications in recent years. However, there are still some insufficiencies in ABC algorithm such as poor quality of initial solution, slow convergence, premature, and low precision, which hamper the further development and application of ABC. In order to further improve the performance of ABC, we first proposed a novel initialization method called search space division (SSD), which provided high quality of initial solutions. And then, a disruptive selection strategy was used to improve population diversity. Moreover, in order to accelerate convergence rate, we changed the definition of the scout bee phase. In addition, we designed two types of experiments to testify our proposed algorithm. On the one hand, we conducted experiments to make sure how much each modification makes contribution to improving the performance of ABC. On the other hand, comprehensive experiments were performed to prove the superiority of our proposed algorithm. The experimental results indicate that SDABC significantly outperforms other ABCs, contributing to higher solution accuracy, faster convergence speed, and stronger algorithm stability.
    Print ISSN: 1024-123X
    Electronic ISSN: 1563-5147
    Topics: Mathematics , Technology
    Published by Hindawi
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  • 7
    Publication Date: 2014-07-02
    Description: [TbNa(4-msal) 4 (phen) 2 ] n ( 1 ) (4-msal = 4-methyl salicylic acid), a new hetero-metallic lanthanide coordination polymer (CP) involving sodium was synthesized. It crystallizes in the monoclinic space group P 2 1 / n , with a = 20.4809(9) Å, b = 9.8183(2) Å, c = 26.1987(11) Å, α = 90.00°, β = 112.922(5)°, γ = 90.00°, V = 4852.2(3) Å 3 , and Z = 4. The complex was characterized by single crystal and powder X-ray diffraction, elemental analysis (EA), and Fourier transform infrared (FT-IR) and luminescence spectroscopy. The luminescence properties of a powder sample of 1 were studied at room temperature and the luminescence lifetime and total quantum yield (QY) were determined.
    Print ISSN: 0044-2313
    Electronic ISSN: 1521-3749
    Topics: Chemistry and Pharmacology
    Published by Wiley
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  • 8
    Publication Date: 2018
    Description: International Journal of Distributed Sensor Networks, Volume 14, Issue 10, October 2018. 〈br/〉
    Print ISSN: 1550-1477
    Electronic ISSN: 1550-1477
    Topics: Electrical Engineering, Measurement and Control Technology
    Published by Hindawi
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  • 9
    Publication Date: 2016-03-16
    Description: Melt–rock interaction is a common mantle process; however, it remains unclear how this process affects the composition of potassic basalt. Here, we present a case study to highlight the link between compositional variations in the potassic basalts and melt–rock interaction in cold lithosphere. Cenozoic potassic basalts in Northeast China are strongly enriched in incompatible elements and show EM1-type Sr–Nd–Pb isotopes, suggesting an enriched mantle source. These rocks show good correlations between 87 Sr/ 86 Sr and K 2 O/Na 2 O and Rb/Nb. Notably, these ratios decrease with increasing lithospheric thickness, which may reflect melt–lithosphere interaction. Phlogopite precipitated when potassic melts passed through the lithospheric mantle, and K and Rb contents of the residual melts decreased over time. The thicker the lithosphere, the greater the loss of K and Rb from the magma. Therefore, the compositions of potassic basalts were controlled by both their enriched sources and reactions with lithospheric mantle.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 10
    Publication Date: 2012-05-30
    Description: To characterize the spatial distributions of methane-sulfonic acid (MSA) as represented by measured aerosol methane sulfonate (MS) and its relationships with non-sea-salt (nss) sulfate (SO42−) in the marine atmospheric boundary layer over high-latitude regions, bulk aerosol samples were collected during eight cruises during the Chinese National Antarctic and Arctic Research Expeditions from 1998 to 2008. The concentrations of MSA (an indicator of marine biogenic sulfur production), sulfate, sodium and chloride in samples were analyzed using ion chromatography. Increases in the aerosol MSA concentrations and MSA/nss-SO42− ratios were observed as functions of latitudes in the Pacific Ocean, more abruptly near high southern latitudes as compared to those in high northern latitudes. The MSA concentrations increased from 0.011 μg m−3 near the equator to 0.26 μg m−3 at 63°S, 23°W and from 0.0013 μg m−3 at northern midlatitudes to 0.19 μg m−3 at 58°N, 175°E. However, MSA decreased in the latitudes north of 58°N in the Pacific, where air temperature was lower. MSA/nss-SO42− ratios increased from 0.024 near the equator to 0.93 at 62°S, 4°E and from 0.0031 around northern midlatitudes to 0.39 at 68°N, 169°W. The MSA concentrations were more correlated with MSA/nss-SO42− (R2 = 0.43, n = 60) in Southern Hemisphere than Northern Hemisphere (R2 = 0.091, n = 40). No significant correlation was found between MSA/nss-SO42− and air temperature at high latitudes, indicating latitudinal temperature variations were not a main factor responsible for the MSA/nss-SO42− variation in those regions. Substantial increases in the concentrations of MSA in coastal Antarctica may indicate additional sources of biogenic S besides the emissions of dimethylsulfide from the sea.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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