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Impact of crystalline and amorphous iron-and aluminum hydroxides on mechanisms of phosphate adsorption and desorption

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Journal of Environmental Sciences 2018年第8期30卷 175-189页

作者： Stella Gypser Florian Hirsch Anja M.Schleicher dirk Freese Brandenburg University of Technology Cottbus-Senftenberg Faculty of Environment Process Engineering Biotechnology and Chemistry Department of Soil Protection and Recultivation Brandenburg University of Technology Cottbus-Senftenberg Faculty of Environment Process Engineering Biotechnology and Chemistry Department of Geopedology and Landscape Development German Research Centre for Geosciences Section 3.1 Inorganic and Isotope Geochchemistry

Fourier-transform infrared（FT-IR） spectroscopic experiments were carried out during phosphate adsorption on highly crystalline gibbsite, poorly crystalline 2-line-ferrihydrite and amorphous iron–aluminum–hydroxide mixtures in the molar ratio 1：0, 10：1, 5：1, 1：1, 1：5, 1：10 and 0：1. The OH stretching vibrational bands were utilized to analyze changes in structural and surface OH groups during adsorption, because the position of characteristic P／O vibrational bands can shift depending on reaction conditions, pH or adsorbed phosphate *** and desorption kinetics were studied at pH6 and different initial phosphate concentrations to achieve varying phosphate coverage on the mineral surfaces. For gibbsite the formation of AlHPO4 and Al2HPO4 can be assumed, while for ferrihydrite, a FeHPO4 or Fe2PO4 complex and the precipitation of FePO4 with longer equilibration time were ***2HPO4 or a Fe2PO4 surface complex was deduced for Fe-hydroxides, an AlH2PO4 surface complex was identified for Al-hydroxide, and both displayed either hydrogen bonds to neighboring hydroxyl groups or hydrogen bonds to outer-sphere complexes. Fe：Al-hydroxide mixtures with high Al ratios showed a low phosphate desorption rate, while ferrihydrite and the Fe：Al-hydroxide mixtures with high Fe ratios had almost negligible desorption rates. It was concluded that within the weakly associated amorphous FeO（OH） materials, FePO4 precipitated, which was bound by outer-sphere hydrogen bonds. With high Al ratios, desorption increased, which indicated weaker phosphate binding of both inner-sphere and outer-sphere complexes and hence, either no or minor quantities of precipitate. Ferrihydrite showed a more rigid structure and a lower extent of precipitation compared to amorphous Fe-hydroxide.

关键词： Phosphate Adsorption Desorption Surface complexation Precipitation FT-IR

Rates and processes affecting As speciation and mobility in lake sediments during aging

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Journal of Environmental Sciences 2018年第4期30卷 338-347页

作者： Alan Lock dirk Wallschlager Nelson Belzile Graeme Spiers Celine Gueguen Environmental and Life Sciences Graduate Program Trent University School of the Environment Department of Chemistry and Water Quality CentreTrent University Department of Chemistry Laurentian University School of the Environment Departments of Earth Sciences and BiologyLaurentian University School of the Environment and Chemistry Department Trent University

Sediments from an arsenic（As） contaminated groundwater vent site were used to investigate As（ Ⅲ） binding, transformation and redistribution in native and iron oxide amended lake sediments using aging spiked batch reactions and a sequential extraction procedure that maintains As（V） and As（ Ⅲ） speciation. In the native sediments, fractionation analysis revealed that 10% of the spiked As（ Ⅲ） remained intact after a 32-day aging experiment and was predominantly adsorbed to the strongly sorbed（NH4H2PO4 extractable） and amorphous Fe oxide bound（H3PO4 extractable） fractions. Kinetic modelling of the experimental results allowed identifying the dominant reaction path for depletion of dissolved As（ Ⅲ） to As（ Ⅲ）absorbed on to the solid phase, followed by oxidation in the solid phase. Arsenite was initially adsorbed primarily to the easily exchangeable fraction（（NH4）2SO4 extractable）, then rapidly transformed into As（V） and redistributed to the strongly sorbed and amorphous Fe oxide bound fractions. Oxidation of As（ Ⅲ） in recalcitrant fractions was less efficient. The iron oxide amendments illustrated the controls that iron oxides can have on As（ Ⅲ） binding and transformation rates. In goethite amended samples As（ Ⅲ） oxidation was faster and primarily occurred in the strongly sorbed and amorphous Fe oxide bound fractions. In these samples,19.3 μg Mn was redistributed（compared to the native sediment） from the easily exchangeable and crystalline Fe oxide bound fractions to the strongly sorbed and amorphous Fe oxide bound fractions, indicating that goethite may act as a catalyst for Mn（Ⅱ） oxidation, thereby producing sorbed Mn（ Ⅲ/Ⅳ ）, which then appears to be involved in rapidly oxidizing As（ Ⅲ）.

关键词： Arsenite Oxidation Fractionation Redistribution Modelling

Statistical landslide susceptibility assessment in a dynamic environment:A case study for Lanzhou City,Gansu Province,NW China

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Journal of Mountain Science 2018年第6期15卷 1299-1318页

作者： TORIZIN Jewgenij WANG Li-chao FUCHS Michael TONG Bin BALZER dirk WAN Li-qin KUHN dirk LI Ang CHEN Liang Federal Institute for Geosciences and Natural Resources （BGR） Hannover 30655 Germany China Institute of Geo-environment Monitoring （CIGEM） Beijing 100081 China

This study presents a statistical landslide susceptibility assessment(LSA) in a dynamic environment. The study area is located in the eastern part of Lanzhou, NW China. The Lanzhou area has exhibited rapid urbanization rates over the past decade associated with greening, continuous land use change, and geomorphic reshaping activities. To consider the dynamics of the environment in the LSA, multitemporal data for landslide inventories and the corresponding causal factors were collected. The weights of evidence(Wof E) method was used to perform the LSA. Three time stamps, i.e., 2000, 2012, and 2016, were selected to assess the state of landslide susceptibility over time. The results show a clear evolution of the landslide susceptibility patterns that was mainly governed by anthropogenic activities directed toward generating safer building grounds for civil infrastructure. The low and very low susceptibility areas increased by approximately 10% between 2000 and 2016. At the same time, areas of medium, high and very high susceptibility zones decreased proportionally. Based on the results, an approach to design the statistical LSA under dynamic conditions is proposed, the issues and limitations of this approach are also discussed. The study shows that under dynamic conditions, the requirements for data quantity and quality increase significantly. A dynamic environment requires greater effort to estimate the causal relations between the landslides and controlling factors as well as for model validation.

关键词： Landslide susceptibility assessment Dynamic environment Weights of evidence method Validation Urbanization Lanzhou City

The concentration and efflux of tree stem CO_(2) and the role of xylem sap flow

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Frontiers in Biology 2009年第1期4卷 47-54页

作者： Ping ZHAO dirk HÖLSCHER South China Institute of Botany Chinese Academy of SciencesGuangzhou 510650China 2 Department of Tropical Silviculture and Forest EcologyUniversity of Göttingen37077 GöttingenGermany

The accurate assessment of actual tree stem respiration and its relation with temperature plays a considerable role in investigating the forest carbon *** increasing number of research reports have indicated that tree stem respiration determined with the commonlyapplied chamber gas exchange measuring system does not follow expectations regarding temperature *** method is based on the nowadays widely-accepted theory that the respired CO_(2) in a tree stem would all diffuse outward into the ***,it neglects partial CO_(2) that is dissolved in the xylem sap and is carried away by the transpirational *** have started to realize that the respired CO_(2) measured with the chamber gas exchange method is only a portion of the total stem respiration(CO_(2) efflux),while the other portion,which is sometimes very substantial in quantity(thought to occupy maybe 15%-75%of the total stem respiration),is transported to the upper part of the stem and to the canopy by sap *** suggests that the CO_(2) produced by respiration is re-allocated within the ***,the change in CO_(2) efflux could be reflected in the rates of sap flow in addition to its dependence on *** methods and instruments are required to quantify the internal and external CO_(2) fluxes in the trunk and their interaction with related environmental factors.

关键词： sap flow rates respired CO_(2)in the stem retranslocation of stem respiration

FINITE ELEMENT METHOD ON NUMERICAL SIMULATION OF STRATUM CORNEUM'S PENETRATION PROPERTY

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Applied Mathematics and Mechanics(English Edition) 2006年第4期27卷 469-475页

作者：刘宇红乔爱科 dirk Feuchter Gabriel Wittum 曾衍钧 Biomechanics and Medical Information Institute Beijing University of Technology Beijing 100022P. R. China Technical Simulation Group of the Interdisciplinary Center for Scientific Computing of University Heidelberg Im neuen Heimerfeld 36869120Germany Technical Simulation Group of the Interdisciplinary Center for Scientific Computing of University Heidelberg Im neuen Heimerfeld 368 69120Germany

How the outer substance could penetrate through the skin lies in the stratum corneum, because it is the main barrier in the multi-layers of the skin. Supposing the keratin cell with a special geometry as tetrakaidecahedron, the penetration property of stratum corneum was the key problem which was numerically simulated with finite element method. At first the discretization of the stratum corneum region was given in two steps： first, the discretization of the keratin cell; second, the discretization of fattiness that surrounds the keratin. Then there was the work of numerical simulation. In this procedure, the finite element method and the multi-grid method were used. The former was to obtain the discretization of basic elements; the latter was to decrease the high frequency error. At last the visualization of the numerical simulation was shown.

关键词： stratum corneum tetrakaidecahedron discretization finite element method multi-grid method

A crucial step for molecular-scale electronics:a stable and reversible single-molecule switch

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National Science Review 2017年第5期4卷 666-667页

作者： Tingting Mei Dong Xiang dirk Mayer Key Laboratory of Optical Information Science and Technology Institute of Modern OpticsCollege of Electronic Information and Optical EngineeringNankai University

As the most fundamental element of modern logic and memory circuits in all electronic devices,molecular switches,storing digital information and route signals by changing the molecular conductance,have attracted inten... 详细信息

关键词： JUNCTIONS

New fossil evidence of the early diversification of scarabs： AIIoioscarabaeus cheni （Coleoptera： Scarabaeoidea） from the Middle Jurassic of Inner Mongolia, China

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Insect Science 2012年第2期19卷 159-171页

作者： Ming Bai dirk Ahrens Xing-Ke Yang Dong Ren Key Laboratory of Zoological Systematics and Evolution Institute of ZoologyChinese Academy of SciencesBeijingChina Zoologisches Forschungsmuseum Alexander Koenig BonnGermany College of Life Sciences Capital Normal UniversityBeijingChina

Scarabaeoidea are known from the Lower Jurassic and may have originated in the Triassic based on fossil evidence and phylogenetic research. However, the early diversification of Scarabaeoidea remains unclear due to the lack of high-quality fossil evidence. Here we describe an exceptionally well-preserved new fossil of Scarabaeoidea, Alloioscarabaeus cheni gen. et sp. nov from the Middle Jurassic Jiulongshan Formation of Inner Mongolia, China. Based on a morphometric analysis using 17 landmarks of the hind wing of Alloioscarabaeus and 10 scarabaeoid families, we found that Alloioscarabaeus cheni gen. et sp. nov clearly does not belong to any of the known scarabaeoid families and, consequently, is a new family, Alloioscarabaeidae fam. nov., was erected. The discovery of Alloioscarabaeus brought further evidence for the early diversification of major scarab lineages which could allow more detail in the palaeobiogeography of the Scarabaeoidea and Northeast of China which might be one of the originating places or an important radiation place during the evolution of Scarabaeoidea. Alloioscarabaeidae were very likely not good diggers and might have fed on decaying organic materials. Based on the evidence we have now, we tend to believe that most families and some subfamilies of Scarabaeoidea were present in the Jurassic period.

关键词： Alloioscarabaeidae Alloioscarabaeus China geometric morphometrics,Jiulongshan Formation new family

Macrophage’s little helper: vitamin A directs alternatively activated monocyte-derived macrophages to tissue-resident macrophages

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Cellular & Molecular Immunology 2017年第10期14卷 805-808页

作者： dirk Schlüter Florian H Heidel Institute of Medical Microbiology and Hospital Hygiene Otto-von-Guericke University MagdeburgMagdeburg 39120Germany Organ-Specific Immune Regulation Helmholtz-Center for Infection ResearchBraunschweig 38124Germany Innere Medizin II Hämatologie und OnkologieUniversitätsklinikum JenaJena 07745Germany Leibniz-Institute on Aging Fritz-Lipmann-InstituteJenaGermany

Tissue-resident macrophages originate from the yolk sac in a Myb-independent manner and populate all organs during *** macrophages are a heterogeneous self-renewing population that adapt to the organ-specific local environment to contribute to tissue *** on the age,organ and inflammatory conditions,macrophages that are derived from hematopoietic stem cells(HSCs)in a Myb-dependent manner may also infiltrate organs and develop into tissueresident macrophages.

关键词： organs vitamin homeostasis

Expression of Epitope-Tagged SYN3 Cohesin Proteins Can Disrupt Meiosis in Arabidopsis

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Journal of Genetics and Genomics 2014年第3期41卷 153-164页

作者： Li Yuan Xiaohui Yang dirk Auman Christopher A.Makaroff Department of Chemistry and Biochemistry Miami University

a-kleisins are core components of meiotic and mitotic cohesin complexes. Arabidopsis contains genes encoding four a-kleisins. SYN1, a REC8 ortholog, is essential for meiosis, while SYN2 and SYN4 appear to be SCCI orthologs and function in mitosis. SYN3 is enriched in the nucleolus of meiotic and mitotic cells and is essential for megagametogenesis. It was recently shown that expression of SYN3-RNAi constructs in buds cause changes in meiotic gene expression that result in meiotic alterations. In this report we show that expression of SYN3 from the 35S promoter with either a c-terminal Myc or FAST tag causes a reduction in SYN1 mRNA levels that results in al- terations in sister chromatid cohesion, homologous chromosome synapsis female meiosis. and synaptonemal complex formation during both male and

关键词： Cohesin Cohesion Kleisin Synapsis Meiosis Sterility