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Adsorption of As on hydroxy-Fe-montmorillonite complexes

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Science China Earth Sciences 2005年第12期48卷 2155-2165页

作者： Donald g. fraser Department of Earth Sciences Oxford University Parks Road Oxford OX1 3PR UK

Arsenate has high affinity for soluble hydroxy-Fe species and Fe-oxyhydroxide pre-cipitates. In addition, the hydrolysis of Fe(III) and the growth of the initially precipitated Fe(III) phases are strongly influenced by the presence of montmorillonite. In this paper, the adsorption of As onto various hydroxy-Fe-montmorillonite (H-F-M) complexes was studied. Three systems of samples were prepared by mixing montmorillonite, hydroxy-Fe and arsenate in different se-quences: (1) Prior mixing of montmorillonite and hydroxy-Fe before the addition of arsenate; (2) prior mixing of hydroxy-Fe and arsenate before the addition of montmorillonite; and (3) prior mixing of montmorillonite and arsenate before the addition of hydroxy-Fe. For each system, the effects of pH, ionic strength, temperature, initial Fe and As concentrations and adsorption dura-tion on the overall uptake of As by H-F-M complexes were studied. Results showed that the up-take of As increased with increasing pH, temperature, initial Fe concentration and adsorption duration, and decreased with increasing ionic strength and initial As concentration to different extents for the three systems. The variation of the As uptake of H-F-M complexes with pH in the range of study is opposite to that reported previously for Fe-O-H systems in the absence of montmorillonite and similar to that reported for montmorillonite in the absence of hydroxy-Fe. The marked influence of ionic strength on the As uptake of H-F-M complexes indicates that outer-sphere complexation plays an important role. This is quite different from the adsorption of As on the surface of either Fe-oxyhydroxides or montmorillonite alone in which inner-sphere complexation dominates. Under all experimental conditions, the H-F-M complexes studied dis-played a very strong affinity for As, among which system 2 had the highest As adsorption capac-ity and system 1 the lowest. The authors attribute this to the differences in mixing sequence which resulted in more hy

关键词： hydroxy-Fe, montmorillonite, complex, arsenate adsorption.

Optical coherence tomography in compressive lesions of the anterior visual pathway

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Annals of Eye Science 2020年第2期5卷 44-56页

作者： Megha Kaushik Clare l.fraser Department of Ophthalmology Sydney Eye HospitalSydneyAustralia Save Sight Institute Faculty of Health and Medical ScienceUniversity of SydneySydneyAustralia

Optical coherence tomography(OCT)provides a non-invasive analysis of the retina in *** which compress the anterior visual pathway can cause anterograde and retrograde *** structural changes to the retina can be detected by *** patterns of change on OCT can guide diagnostic and treatment decisions for lesions compressing the optic nerve and chiasm to minimize loss of visual *** our review of current literature,it is clear that thinning of both the retinal nerve fiber and ganglion cell layers(gCls)can indicate *** parameters correlate with visual function loss as detected by ***,these measurements have shown to be the most reliable biomarkers to date in predicting visual recovery after treatment of these compressive lesions.

关键词： ptical coherence tomography(OCT) compression chiasm optic nerve tumor

(Re)assessing Climate-Smart Agriculture practices for sustainable food systems outcomes in sub-Saharan Africa:The case of Bono East Region,ghana

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geography and Sustainability 2023年第2期4卷 112-126页

作者： Philip Tetteh Quarshie Seidu Abdulai Evan D.g.fraser Deparment of geography Environment and Geomatics&Guelph Institute of Development StudiesCollege of Social and Applied Human ScienceUniversity of Guelph50 Stone Rd EGuelphON N1H 2W1 Canada global Agri-Business Solutions INC.54-480 grey Street BrantfordON N3S 7S5 Canada Deparment of Food Agricultural and Resource Economics Ontario Agriculture CollegeUniversity of Guelph50 Stone Rd EGuelphON N1G 2W1 Canada Department of geography Environment and Geomatics&Arrell Food InstituteUniversity of Guelph50 Stone Rd EGuelphON N1H 2W1 Canada

This research paper assesses the reality of Climate-Smart Agriculture(CSA)practices’potential to promote the outcomes of sustainable food systems(SFS)within ghana’s smallholding agriculture *** study demon-strates that rural farmers generally perceive CSA’s contribution to‘food and nutrition security’and‘economic performance’as more important than CSA’s contribution to‘social equity’and‘environmental stewardship’.From a narrow perspective,the study demonstrates that farmers perceive CSA’s potential to‘prevent pest and disease outbreaks’and‘increase human capital information’as the most important contribution of CSA to SFS *** contrast,CSA’s potential to promote environmental stewardship is perceived as the least important among ghana’s rural *** enormity of displacement of smallholders’perceptions at large is motivated by de-mographic,socioeconomic and ecological ***,the CSA for SFS outcomes narratives is driven by farmers’self-apprise,social networks and other local information dissemination ***,research findings suggest farmers’awareness of CSA practices and interventions is deficient owing to unmet training and information needs for approximately 82%of the CSA practices and *** situation elucidates the dichotomy of CSA practices’narratives as tools for attaining food,nutrition security and economic performance to the detriment of critical issues such as increasing awareness and building farmers’capacity to engage with CSA practices while also managing socio-ecological trade-offs that emerge over time due to engagement with ***(re)orientation is needed across the scale to drive CSA practices and interventions that confine cli-mate adaptation and food production practices within safe planetary boundaries without undermining social,economic,food and nutrition security needs.

关键词： Climate adaptation Climate-Smart Agriculture ghana Smallholder farmers Sustainable food systems Sub-Saharan Africa

Optical coherence tomography in optic disc drusen

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Annals of Eye Science 2020年第1期5卷 22-34页

作者： J.Alexander fraser lulu l.C.D.Bursztyn Department of Clinical Neurological Sciences Western UniversityLondonONCanada Department of Ophthalmology Western UniversityLondonONCanada

Optic disc drusen (ODD) are hyaline deposits in the optic nerve head, occurring in approximately 2% of the population. ODD may be superficial and visible, or buried and either invisible or seen only as elevation of the optic disc, mimicking optic disc edema. Advanced optic nerve imaging, including optical coherence tomography (OCT) can be used to diagnose and characterize ODD with very high resolution. Enhanced depth imaging (EDI-OCT) in particular has emerged as the optimal modality to directly visualize ODD. This modality has led to a greater ability to differentiate ODD from optic disc edema and prevent misdiagnosis or invasive testing. We review the characteristic findings of ODD on OCT, their distinguishing features, and the use of OCT as a biomarker in the neuro-ophthalmic assessment of ODD.

关键词： Drusen optic disk tomography optical coherence

Eight decades of compositional change in a managed northern hardwood landscape

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Forest Ecosystems 2023年第3期10卷 398-410页

作者： Mark J.Ducey Olivia l.fraser Mariko Yamasaki Ethan P.Belair William B.leak University of New Hampshire Department of Natural Resources and the Environment114 James HallDurhamNH03824USA U.S.D.A.Forest Service White Mountain National Forest71 White Mountain DriveCamptonNH03223USA U.S.D.A.Forest Service Northern Research Station271 Mast RoadDurhamNH03824USA The Nature Conservancy Natural Climate SolutionsAfrica Regional Portland Office45 Exchange StSuite 303PortlandME04101USA

We analyzed over 8 decades of change in forest composition(represented by species proportion of basal area)and size class from more than 400 permanent plots located on the Bartlett Experimental Forest in the White Mountains of New *** data represent one of the longest-term landscape-scale records of forest change based on permanent plots in North *** analyzed the plots based on elevation class,land type indicating assumed successional direction(grouped into coniferous and deciduous),and inventory period within managed and unmanaged portions of the *** ongoing shift from small-to large-diameter stems is clear across all species,in response to the overall aging of the forest following exploitative harvesting in the 19th *** compositional changes include a continuing decline in shade-intolerant species(paper birch and aspen),along with the mid-tolerant yellow *** increase in red maple abundance through the early 1990s has leveled off or *** shade-tolerant species,increases in beech and red spruce were largely consistent with assumed land type on unmanaged plots,but heavy marking against diseased beech on managed plots restricted increase of that *** maple declined in abundance except where silvicultural intervention helped maintain *** contrast,eastern hemlock showed a continuing expansion at all elevations below 600 *** data continue to show little or no evidence of upward migration of species,despite evidence of recent regional change in ***,the BEF is poised for substantial changes when emerald ash borer and hemlock woolly adelgid,both of which are known to infest nearby areas,do arrive.

关键词： Northern hardwoods Succession Stand dynamics Silviculture

Micro-Photoluminescence Confocal Mapping of Single V-grooved gaAs Quantum Wire

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Chinese Physics letters 2006年第12期23卷 3341-3344页

作者：黄少华陈张海柏利慧沈学础 H. H. Tan l. Fu M. fraser C. Jagadish Department of Physics and National Key laboratory for Surface Physics Fudan University Shanghai 200433 Department of Electronic Material Engineering Research School of Ph3~sical Science and Engineering Australian National University Canberra ACT 0200 Australia

We perform the micro-photoluminescence measurement at low temperatures and a scanning optical mapping with high spatial resolution of a single V-grooved gaAs quantum wire modified by the selective ion-implantation and rapid thermally annealing. While the mapping shows the luminescences respectively from the quantum wires and from quantum well areas between quantum wires in general, the micro-photoluminescence at liquid He temperatures reveals a plenty of spectral structures of the Pl band for a single quantum wire. The spectral structures are attributed to the inhomogeneity and non-uniformity of both the space structure and compositions of real wires as well as the defects nearby the interface between quantum wire and surrounding quantum well structures. All these make the excitons farther localized in quasi-zero-dimensional quantum potential boxes related to these non-uniformity and/or defects. The results also demonstrate the ability of micro-photoluminescence measurement and mapping for the characterization of both opto-electronic and structural properties of real quantum wires.

关键词： gROWTH

Recovery rates of combination antibiotic therapy using in vitro microdialysis simulating in vivo conditions

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Journal of Pharmaceutical Analysis 2018年第6期8卷 407-412页

作者： Jayesh A.Dhanani Suzanne l.Parker Jeffrey lipman Steven C.Wallis Jeremy Cohen John fraser Adrian Barnett Michelle Chew Jason A.Roberts Burns Trauma and Critical Care Research Centre The University of Queensland UQ Centre for Clinical Research Department of Intensive Care Medicine Royal Brisbane & Women's Hospital Faculty of Health Queensland University of Technology Critical Care Research group The University of Queensland Institute of Health and Biomedical Innovation & School of Public Health and Social Work Queensland University of Technology Department of Anaesthesiology and Intensive Care and Department of Medical and Health Sciences Link?ping University School of Pharmacy The University of Queensland Department of Pharmacy Royal Brisbane & Women's Hospital

Microdialysis is a technique used to measure the unbound antibiotic concentration in the interstitial spaces, the target site of action. In vitro recovery studies are essential to calibrating the microdialysis system for in vivo studies. The effect of a combination of antibiotics on recovery into microdialysate requires investigation. In vitro microdialysis recovery studies were conducted on a combination of vancomycin and tobramycin, in a simulated in vivo model. Comparison was made between recoveries for three different concentrations and three different perfusate flow rates. The overall relative recovery for vancomycin was lower than that of tobramycin. For tobramycin, a concentration of 20μg/ml and flow rate of 1.0μl/min had the best recovery. A concentration of 5.0μg/ml and flow rate of 1.0μl/min yielded maximal recovery for vancomycin. large molecular size and higher protein binding resulted in lower relative recoveries for vancomycin. Perfusate flow rates and drug concentrations affected the relative recovery when a combination of vancomycin and tobramycin was tested. low perfusate flow rates were associated with higher recovery rates. For combination antibiotic measurement which includes agents that are highly protein bound, in vitro studies performed prior to in vivo studies may ensure the reliable measurement of unbound concentrations.

关键词： Microdialysis Combination antibiotic therapy Relative recovery rate Pharmacokinetics Anti-infectives Protein binding

Correlations among large igneous provinces related to the West gondwana breakup:A geochemical database reappraisal of Early Cretaceous plumbing systems

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geoscience Frontiers 2023年第1期14卷 181-206页

作者： Antomat A.Macêdo Filho Maria Helena B.M.Hollanda Stephen fraser Alisson l.Oliveira Alanny C.C.Melo Alana R.Dantas Instituto de geociências Universidade de São Paulo05508-080São PauloBrazil W.H.Bryan Mining&geology Research Centre Sustainable Minerals InstituteThe University of QueenslandSt Lucia CampusQLD 4072Australia Programa de Pós-graduação em geodinamica e geofisica Universidade Federal do Rio Grande do NorteCampus Universitário S/NLagoa Nova59078-970 NatalRNBrazil

The opening and spreading of the Atlantic Ocean between Africa and South America evolved during the Early Cretaceous and were preceded by dramatic tholeiitic(mafic)magmatism and minor silicic and alkaline *** features are presently recognized from the equatorial regions of Brazil and Africa to the Falklands and South *** southeastern South America,continental flood basalts and related plumbing systems constitute the ParanáMagmatic Province(PMP),whose African counterpart is the Etendeka Magmatic Province(EMP).In northeastern Brazil,dike swarms and sill complexes compose the Equatorial Atlantic Magmatic Province(EQUAMP).As a common feature,these provinces are chemically represented by two prevalent magma types:(1)tholeiitic basalts and basaltic andesites with lowTi(TiO_(2)lso including transitional Ti tholeiites with TiO_(2)~2.7-1.7 wt.%,and low incompatible element *** type is predominantly found in the southern PMP and EMP,with minor occurrences in the EQUAMP.(2)Tholeiitic basalts and basaltic andesites with high Ti(TiO_(2)>~2 wt.%)and incompatible element *** Ti tholeiites are relevant in the northern PMP and EMP,and dominant in *** rocks(SiO_(2)=57-65 wt.%)interpreted as byproducts of assimilation and/or fractional crystallization(AFC)processes from high Ti tholeiitic magmas,are scarce(but present)in all three *** accurate analysis of multivariable databases collected from the literature for dikes and sills,including major and trace element and radiogenic isotope data,reveals close similarities in their geochemical *** a paleogeographic reconstruction of West gondwana,the intrusive remnants of the PMP,EMP and EQUAMP are spread over an area of nearly 10×10^(6)km^(2).forming perhaps the most extensive set of plumbing systems on Earth,with a relatively consistent chronology based on a vast collection of K-Ar and^(40)Ar/^(39)Ar data available in the *** work provides the first c

关键词： lIP-related plumbing systems Continental tholeiites Paraná-Etendeka EQUAMP Self-organizing maps

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羟基铁溶液—蒙脱石体系对砷的吸附

中国科学（D辑） 2005年第8期35卷 750-757页

作者：廖立兵 Donald g.fraser 中国地质大学(北京)材料科学与工程学院北京100083 Department of Earth Sciences Oxford UniversityParks RoadOxfordOX13PREngland

可溶的羟基铁离子和铁的沉淀物对砷有极强的亲和性,而蒙脱石对Fe(III)的水解以及Fe(III)的沉淀物相的生长有重要影响.为研究砷酸、羟基铁溶液和蒙脱石的混合顺序对羟基铁-蒙脱石体系砷吸附行为的影响,进行了3个系列的实验:(1)先混合羟... 详细信息

可溶的羟基铁离子和铁的沉淀物对砷有极强的亲和性,而蒙脱石对Fe(III)的水解以及Fe(III)的沉淀物相的生长有重要影响.为研究砷酸、羟基铁溶液和蒙脱石的混合顺序对羟基铁-蒙脱石体系砷吸附行为的影响,进行了3个系列的实验:(1)先混合羟基铁溶液和蒙脱石,后加入砷;(2)先混合羟基铁溶液和砷,后加入蒙脱石;(3)先混合蒙脱石和砷,后加入羟基铁溶液.对每个系列实验,则研究了pH、离子强度、温度、初始铁质量浓度、初始砷质量浓度和吸附时间对砷吸附率的影响.结果表明,所有3个系列的砷吸附率均随pH、温度、初始铁质量浓度、吸附时间的增加而不同程度增加,随离子强度和初始砷质量浓度的增加而不同程度降低.在研究的pH范围内,砷吸附率随pH的变化趋势与前人报道的羟基铁溶液体系不同,与蒙脱石相似.离子强度对砷吸附能力的显著影响表明外层络合可能是羟基铁-蒙脱石体系吸附砷的重要机制.在所有实验条件下,三种混合顺序的羟基铁-蒙脱石体系都表现出极强的砷吸附能力,其中系列(2)的砷吸附量最大而系列(1)最小,原因与3个系列实验的砷、羟基铁溶液和蒙脱石的混合顺序不同有关.用X射线衍射和透射电镜研究了3个系列实验沉淀物的物相组成.结果显示,除吸附于蒙脱石表面形成羟基铁-蒙脱石复合体外,羟基铁还以形成纳米级含水氧化铁颗粒及其聚合体的方式沉淀于复合体之间.系列(2)样品的纳米级铁颗粒粒径相对更小,分布更均匀.

关键词：羟基铁蒙脱石砷酸吸附羟基铁离子溶液体系吸附行为 Fe(Ⅲ) 系列实验质量浓度