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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.

Derivation of a segregation-mixing equation for particles in a fluid medium

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Applied Mathematics and Mechanics(English Edition) 2009年第6期30卷 765-770页

作者： donald O. Besong Department of Numerical Analysis and Computer Science (NADA) Royal Institute of TechnologyS-10044 StockholmSweden

The main purpose of this work is to show that the gravity term of the segregation-mixing equation of fine mono-disperse particles in a fluid can be derived from first-principles （i.e., elementary physics）. Our derivation of the gravity-driven flux of particles leads to the simplest case of the Richardson and Zaki correlation. Stokes velocity also naturally appears from the physical parameters of the particles and fluid by means of derivation only. This derivation from first-principle physics has never been presented before. It is applicable in small concentrations of fine particles.

关键词： gravity segregation Kynch batch flux first-principles derivation Burger-type equation

Engel Subalgebras of n-Lie Algebras

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Acta Mathematica Sinica,English Series 2008年第1期24卷 159-166页

作者： donald W.BARNES 1 Little Wonga Rd

Engel subalgebras of finite-dimensional n-Lie algebras are shown to have similar properties to those of Lie algebras. Using these, it is shown that an n-Lie algebra, all of whose maximal subalgebras are ideals, is nilpotent. A primitive 2-soluble n-Lie algebra is shown to split over its minimal ideal, and all the complements to its minimal ideal are conjugate. A subalgebra is shown to be a Cartan subalgebra if and only if it is minimal Engel, provided that the field has sufficiently many elements. Cartan subalgebras are shown to have a property analogous to intravariance.

关键词： n-Lie algebras soluble nilpotent Engel subalgebras

Friction predication on pin-to-plate interface of PTFE material and steel

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Friction 2019年第3期7卷 268-281页

作者： Zhuming BI donald W.MUELLER Depatment of Civil and Mechnical Engineering Purdue University Fort WayneFort Wayne2101EUSA School of Mechanical and Electrical Engineering GuangDong University of TechnologyGuangzhou510006China

In this paper,the friction behavior at a pin-to-plate interface is *** pin and plate are made of Polytetrafluoroethylene(PTFE) and steel,respectively,and there is a reciprocating motion at the *** mathematical models for the relations of design variables and frictions are investigated,and a general procedure is proposed to solve the developed models and predict the friction forces at the interface subjected to given test *** models have been developed to represent intrigued friction behaviors affected by various factors such as pin geometrics and finishes,lubrication conditions,and reciprocating *** test data from experiments is used to verify the effectiveness of the proposed models.

关键词： pin-to-plate friction wear coefficient of frictions PTFE sealing finite element analysis

Summary of a Life in Observational Ultraviolet/Optical Astronomy

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Research in Astronomy and Astrophysics 2024年第1期24卷 1-43页

作者： donald G.York Department of Astronomy and Astrophysics The University of Chicago5801 South Ellis Ave.Chicago 60637ILUSA

I reminisce on my early life in Section 1;on my education in Sections 2 and 3;on the years at Princeton as a research astronomer in Section 4;on the years on the faculty at Chicago in Section 5;on research on Diffuse Interstellar Bands(DIBs) in Section 6;on construction of the 3.5 m telescope at Apache Point Observatory(APO)in Section 7;on work on the Sloan Digital Sky Survey(SDSS) in Section 8;on work in public education in Chicago in Section 9;and on my travels in Section 10. My main science research is of an observational nature,concerning Galactic and intergalactic interstellar gas. Highlights for me included my work on the orbiting telescope Copernicus, including the discovery of interstellar deuterium;early observations of absorption associated with fivetimes ionized oxygen;and discoveries concerning the phases of gas in the local interstellar medium, based on previously unobservable interstellar UV spectral lines. With other instruments and collaborations, I extended interstellar UV studies to the intergalactic cool gas using quasi-stellar object QSO absorption lines redshifted to the optical part of the spectrum;provided a better definition of the emission and morphological character of the source of absorption lines in QSO spectra;and pursued the identification of the unidentified DIBs. For several of these topics, extensive collaborations with many scientists were essential over many years. The conclusions developed slowly, as I moved from being a graduate student at Chicago, to a research scientist position at Princeton and then to a faculty position at Chicago. At each stage of life, I was exposed to new technologies adaptable to my science and to subsequent projects. From high school days, I encountered several management opportunities which were formative. I have been extremely fortunate both in scientific mentors I had and in experimental opportunities I encountered.

关键词： Interstellar Medium(ISM) Nebulae (galaxies:)quasars:absorption lines ultraviolet:stars

Stable oncogenic transformation induced by microcell-mediated gene transfer

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Science China Chemistry 1995年第4期38卷 448-456页

作者：吕有勇 donald G.Blair Beijing Institute for Cancer Research Beijing 100034 China Laboratory of Molecular Oncology National Cancer Institute Frederick MD 21702-1013 USA

Oncogenes have been identified using DNA-mediated transfection, but the size of the transferable and unrearranged DNA, gene rearrangement and amplification which occur during the transfection process limit the use of the techniques. We have evaluated microcell-mediated gene transfer techniques for the transfer and analysis of dominant oncogenes. MNNG-HOS, a transformed human cell line which contained the met oncogene mapping to human chromosome 7 was infected with retroviruses carrying drug resistance markers and used to optimize microcell preparation and transfer. Stable and drug-resistant hybrids containing single human chromosomes as well as the foci of the transformed cells containing the activated met oncogene and intact hitman chromosomes were obtained. Hybridization analysis with probes (i.e. collA2, pJ3.11) mapping up to 1 Mb away from met shows that the cells from the individual focr contain different amounts of apparently unrearranged human DNA associated with the oncogene, and the microcell-generated transformants retain more distal markers than those observed in either DNA- or chromosome-mediated transfers. In conjunction with other techniques, microcell fusion should be useful for gene mapping as well as the study of gene function and expression in cell transformation and malignancy.

关键词： oncogene microcell cell transformation gene mapping met.

Adapting a Mars ISRU System to the Changing Mars Environment

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Space(Science & Technology) 2023年第1期3卷 339-347页

作者： donald Rapp Eric Hinterman 11445 Indiana Ave. South PasadenaCA 91030USA Los Angeles CA USA

This study modeled the performance of a full-scale Mars in situ resource utilization(ISRU)system to produce 30 metric tons of liquid O2,operated for 14 months at half-hourly intervals as the Mars environment changes diurnally and *** considered various control options,with particular emphasis on power requirements and required cell *** temperature and pressure data at half-hour intervals were obtained from the Mars Perseverance *** full-scale Mars ISRU system included a mechanical compressor,high-temperature electrolysis of Martian CO_(2),and a liquefier to produce liquid *** key factors were(a)maintaining cell voltage well below the Nernst potential for carbon formation from CO and(b)tracking the maximum power,as well as the range of power required,at each half-hourly junction across the 14-month run for each control *** most favorable control option involved adjusting the compressor revolutions per minute at each half-hour to produce a quasi-steady state of oxygen production in the electrolysis and the liquefaction systems,resulting in the most benign electrolysis settings,the lowest maximum power,and the narrowest range of required *** approaches where the compressor was run at a steady state and the oxygen production rate varied with time led to higher electrolysis voltage,higher maximum power,and a wider range of *** study provides guidance on the optimum operating conditions and power requirements of a Mars ISRU system to produce 30 metric tons of liquid oxygen in 14 months of operation.

关键词： compressor narrow electrolysis

Calcifying fibrous tumor of the gastrointestinal tract: A clinicopathologic review and update

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World Journal of Gastroenterology 2020年第37期26卷 5597-5605页

作者： donald Turbiville Xuchen Zhang Department of Pathology Yale University School of MedicineNew HavenCT 06510United States

Calcifying fibrous tumor(CFT)is a rare mesenchymal lesion that has been documented throughout the gastrointestinal *** CFTs may occur at virtually any age,with a predilection for adults and for *** occur most commonly in the stomach and the small and large *** are most often found incidentally,cured by local resection,and have a low risk of *** shows three characteristic features:Spindle cell proliferations within a densely hyalinized stroma,scattered calcifications,and lymphoplasmacytic *** are immunoreactive for CD34,vimentin and factor XIIIa,helping to distinguish them from other benign mesenchymal *** differential diagnosis of CFTs includes sclerosing gastrointestinal stromal tumor,leiomyoma,schwannoma,solitary fibrous tumor,inflammatory myofibroblastic tumor,plexiform fibromyxoma,fibromatosis,sclerosing mesenteritis,and reactive nodular fibrous *** pathogenesis of CFTs remains unclear,but some have hypothesized that they may be linked to IgG4-related disease,inflammatory myofibroblastic lesions,hyaline vascular type Castleman disease,sclerosing angiomatoid nodular transformation of the spleen,or trauma.

关键词： Calcifying fibrous tumor Calcifying fibrous pseudotumor Gastrointestinal tract Mesenchymal lesion Calcification Pathology

Giant Magnetoresistance and Microstructure of Melt-Spun Cu_(70)Co_(30) Ribbons

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Chinese Physics Letters 1997年第2期14卷 148-150页

作者： SONG Xiao-ping S.W.Mahon R.F.Cochrane B.J.hickey M.A.Howson School of Materials and Department of Physics University of LeedsLeeds LS29JTUK School of Materials Xi'an Jiaotong UniversityXi'an 710049

This paper reports an investigation on the giant magnetoresistance and microstructure evolution in melt-spun Cu_(70)Co_(30) *** results show that the phase separation is inevitable in the course of quenching,leading to the formation of two types of fcc magnetic Co-rich particles but these do not appear to contribute to the magnetoresistance(MR).On annealing,a very fine distribution of Co-rich precipitates forms at temperatures above 573 K which are responsible for the high MR developed in this material.

关键词： alloy. Microstructure resistance