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Primary beneficiation of tantalite using magnetic separation and acid leaching

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International Journal of Minerals,Metallurgy and Materials 2014年第12期21卷 1153-1159页

作者： M.Nete F.Koko t.theron w.Purcell J.t.Nel Department of Chemistry University of the Free State the South African Nuclear Energy Corporation SOC Ltd.(Necsa) P.O.Box 582Pretoria 0001 South Africa

Primary beneficiation was successfully performed prior to dissolution of manganotantalite （sample A） and ferrotantalite （sample C） samples obtained from two different mines in the Naquissupa area, Mozambique. Magnetic separation removed the majority of iron and titanium, whereas H2SO4 leaching removed a large portion of thorium and uranium in these samples. Analytical results indicated that 64.14wt% and 72.04wt% of the total Fe and ti, respectively, and -2wt% each of Nb205 and ta205 were removed from sample C （ferrotantalite） using the magnetic separation method, whereas only 9.64wt% and 8.66wt% of total Fe203 and tiO2, respectively, and -2wt% each of NbEOs and ta2O5 were removed from sample A （manganotantalite）. A temperature of 50℃ and a leaching time of 3 h in the presence of concentrated HESOa were observed to be the most appropriate leaching conditions for removal of radioactive elements from the tantalite ores. the results obtained for sample A under these conditions indicated that 64.14wt% U3O8 and 60.77wt% thO2 were leached into the acidic solution, along with 4.45wt% and 0.99wt% of Nb2O5 and ta2O5, respectively.

关键词： tantalite beneficiation magnetic separation acid leaching

Long-term trends in Extreme temperatures in Hong Kong and Southern China

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Advances in Atmospheric Sciences 2011年第1期28卷 147-157页

作者： t.C.LEE E.w.L.GINN Hong Kong Observatory

the observed long-term trends in extreme temperatures in Hong Kong were studied based on the meteorological data recorded at the Hong Kong Observatory Headquarters from 1885-2008. Results show that, over the past 124 years, the extreme daily minimum and maximum temperatures, as well as the length of the warm spell in Hong Kong, exhibit statistically significant long-term rising trends, while the length of the cold spell shows a statistically significant decreasing trend. the time-dependent return period analysis also indicated that the return period for daily minimum temperature at 4°C or lower lengthened considerably from 6 years in 1900 to over 150 years in 2000, while the return periods for daily maximum temperature reaching 35°C or above shortened drastically from 32 years in 1900 to 4.5 years in 2000. Past trends in extreme temperatures from selected weather stations in southern China from 1951-2004 were also assessed. Over 70% of the stations studied yielded a statistically significant rising trend in extreme daily minimum temperature, while the trend for extreme maximum temperatures was found to vary, with no significant trend established for the majority of stations.

关键词： extreme temperature long-term trend Hong Kong southern China

Lysozyme as an alternative to growth promoting antibiotics in swine production

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Journal of Animal Science and Biotechnology 2016年第1期7卷 34-40页

作者： w. t. Oliver J.E.wells USDA ARS U.S. Meat Animal Research Center P. O. Box 166 Clay Center NE68933-0166 USA

Lysozyme is a naturally occurring enzyme found in bodily secretions such as tears, saliva, and milk. It functions as an antimicrobial agent by cleaving the peptidoglycan component of bacterial cell walls, which leads to cell death. Antibiotics are also antimicrobials and have been fed at subtherapeutic levels to swine as growth promoters. these compounds benefit swine producers by minimizing production losses by increasing feed efficiency and decreasing susceptibility to bacterial infection and disease. this manuscript reviews the knowledge of the effects of lysozyme, as compared to traditional subtherapeutic antibiotics in swine feed, on pig performance and health. It is clear from decades of studies that antibiotic use in feeds increases pig performance, particularly in the nursery. Similarly, lysozyme, as a feed additive, increases growth and feed efficiency. while the mechanism by which antibiotics and lysozyme improve performance is not clearly understood, both of these feed additives improve gastrointestinal health, improve the metabolic profile, and alter the gastrointestinal bacteria ecology of swine. therefore, lysozyme is a suitable alternative to growth-promoting subtherapeutic antibiotic use in swine feed.

关键词： Antibiotics Gastrointestinal Lysozyme Microbiota Review Swine

Modified Multi-Resolution telescopic Search Algorithm for Block-Matching Motion Estimation

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Journal of Systems Engineering and Electronics 2001年第3期12卷 90-96页

作者： Zhang, w. Zhou, R. Kondo, t. Institute of Microelectronics Tsinghua University Beijing 100084 China

this paper presents a modified multi-resolution telescopic search algorithm (MRtlcSA) for the block-matching motion estimation. A novel inverse telescopic search is substituted for the conventional telescopic search, that reduces the on-chip memory size and memory bandwidth for VLSI implementation. In addition, strategies of motion track and adaptive search window are applied to reduce the computational complexity of motion estimation. Simulation results show that, compared with the MRtleSA, the proposed algorithm reduces the computational load to only 30% while preserving almost the same image quality. Comparisons on hardware cost and power consumption of the VLSI implementations using the two algorithms are also presented in the paper.

关键词： Algorithms Bandwidth Computational complexity Computer simulation Image quality Microprocessor chips Optical resolving power Optical telescopes Pattern matching VLSI circuits

Angiosperm phylogeny inferred from sequences of four mitochondrial genes

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Journal of Systematics and Evolution 2010年第6期48卷 391-425页

作者： tory A.HENDRY Joseph w.BROwN Geordan t.HUDSON Department of Ecology and Evolutionary Biology University of Michigan

An angiosperm phylogeny was reconstructed in a maximum likelihood analysis of sequences of four mitochondrial genes,atp1,matR,nad5,and rps3,from 380 species that represent 376 genera and 296 families of seed *** is largely congruent with the phylogeny of angiosperms reconstructed from chloroplast genes atpB,matK,and rbcL,and nuclear 18S *** basalmost lineage consists of Amborella and Nymphaeales(including Hydatellaceae).Austrobaileyales follow this clade and are sister to the mesangiosperms,which include Chloranthaceae,Ceratophyllum,magnoliids,monocots,and *** the exception of Chloranthaceae being sister to Ceratophyllum,relationships among these five lineages are not well *** eudicots,Ranunculales,Sabiales,Proteales,trochodendrales,Buxales,Gunnerales,Saxifragales,Vitales,Berberidopsidales,and Dilleniales form a basal grade of lines that diverged before the diversification of rosids and *** rosids,the COM(Celastrales-Oxalidales-Malpighiales) clade is sister to malvids(or rosid II),instead of to the nitrogen-fixing clade as found in all previous large-scale molecular analyses of *** and Caryophyllales are members of an expanded asterid *** study shows that the mitochondrial genes are informative markers for resolving relationships among genera,families,or higher rank taxa across *** low substitution rates and low homoplasy levels of the mitochondrial genes relative to the chloroplast genes,as found in this study,make them particularly useful for reconstructing ancient phylogenetic relationships.A mitochondrial gene-based angiosperm phylogeny provides an independent and essential reference for comparison with hypotheses of angiosperm phylogeny based on chloroplast genes,nuclear genes,and non-molecular data to reconstruct the underlying organismal phylogeny.

关键词： angiosperm homoplasy mitochondrial gene molecular evolutionary rate phylogeny rosids.

Forced Convective Heat transfer and Pressure Drop of Air Flowing in a Rectangle Duct with Cross-Ribs on the Opposite walls

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Journal of thermal Science 2002年第3期11卷 259-270页

作者： B.Deng t.t.wong w.Q.tao School of Power and Energy Xi’an Jiaotong University Xi’an China Department of Mechanical Engineering The Hong Kong Polytechnic University Hong Kong

Experiments were conducted to investigate the forced convective heat transfer and flow friction of turbulent airflow in a rectangular duct with cross-ribs attached at the two principal walls in the Reynolds number range from 5000 to 40000. the effect of the rib cross angle (45° 60° 75° and the height (4 mm, 5 mm) of the cross-ribs on the forced convection and flow friction were tested. Non-dimensional correlations for the duct average Nusselt number and friction factor of cross-ribs duct were developed from the test data. Experiments were also conducted for the corresponding parallel ribs to compare their relative performance. the experimental results show that both of the convective heat transfer coefficient and friction factor were increased with cross-ribs, with 45°cross-ribs being the best. Compared with parallel ribs normal to the flow direction under identical flow rate and identical pumping power constraints, the cross-ribs can enhance heat transfer in the lower Reynolds number region, while

关键词： cross-ribs forced convection heat transfer enhancement.

Vlultifunctional immune responses of HMBPP-specific Jy2Vδ2 t cells in M. tuberculosis and other infections

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Cellular & Molecular Immunology 2013年第1期10卷 58-64页

作者： Zheng w Chen Department of Microbiology and Immunology Center for Primate Biomedical Research University of Illinois College of Medicine Chicago chicago IE 60612: USA

Vy2Vδ2 t （also known as Vy9Vδ2 t） cells exist only in primates, and in humans represent a major yδ t-cell sub-population in the total population of circulating yδ t cells. Results from recent studies suggest that while （E）-4-hydroxy-3-methyl-but-2-enyl pyrophosphate （HMBPP） phosphoantigen from Mycobacterium tuberculosis （Mtb） and other microbes activates and expands primate Vy2Vδ2 t cells, the Vy2Vδ2 t-cell receptor （tCR） recognizes and binds to HMBPP on antigen-presenting cells （APC）. In response to HMBPP stimulus, Vy2V82 tCRs array to form signaling-related nanoclusters or nanodomains during the activation of Vy2V82 t cells. Primary infections with H MBPP-producing pathogens drive the evolution of multieffector functional responses in Vy2Vδ2 t cells, although Vy2V82 t cells display different patterns of responses during the acute and chronic phases of Mtb infection and in other infections. Expanded Vy2Vδ2 t cells in primary Mtb infection can exhibit a broader tCR repertoire and a greater clonal response than previously assumed, with different distribution patterns of Vδ,2Vδ2 t-cell clones in lymphoid and non-lymphoid compartments. Emerging in vivo data suggest that HMBPP activation of Vy2w2 t cells appears to impact other immune cells during infection.

关键词： (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate yδ t cell HMBPP human infection phosphoantigen t cell receptor t-cell response tuberculosis

Compton profiles of NiO and tiO_2 obtained from first principles GwA spectral function

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Chinese Physics B 2016年第6期25卷 407-415页

作者： S M Khidzir M F M Halid w A t wan Abdullah Department of Physics Universiti of Malaya

In this work,we first use momentum density studies to understand strongly correlated electron behavior,which is typically seen in transition metal *** observe that correlated electron behavior as seen in bulk NiO is due to the Fermi break located in the middle of overlapping spectral functions obtained from a Gw（G is Green’s function and w is the screened Coulomb interaction） approximation（GwA） calculation while in the case of tiO2 we can see that the origin of the constant momentum distribution in lower momenta is due to a pile up of spectra before the Fermi *** observations are then used to compare our calculated Compton profiles with previous experimental studies of Fukamachi and *** calculations for NiO are observed to follow the same trend as the experimental profile but it is seen to have a wide difference in the case of tiO2 before the Fermi *** ground state momentum densities differ significantly from the quasiparticle momentum density,thus stressing the importance of the quasiparticle wave function as the input for the study of charge density and the electron localization *** we perform a calculation of the quasiparticle renormalization function,giving a quantitative description of the discontinuity of the GwA momentum density.

关键词： elastic and Compton scattering density functional theory local density approximation gradient and other corrections elements oxides nitrides borides carbides chalcogenides

Biosorption of copper and zinc by immobilised and free algal biomass,and the effects of metal biosorption on the growth and cellular structure of Chlorella *** Chlamydomonas *** from rivers in Penang,Malaysia

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Journal of Environmental Sciences 2012年第8期24卷 1386-1393页

作者： w.O.wan Maznah A.t.Al-Fawwaz Misni Surif School of Biological Sciences Universiti Sains Malaysia11800 PenangMalaysia Centre for Marine and Coastal Studies(CEMACS) Universiti Sains Malaysia11800 PenangMalaysia Centre for Distance Education Universiti Sains Malaysia11800 PenangMalaysia

In this study, the biosorption of copper and zinc ions by Chlorella sp. and Chlamydomonas sp. isolated from local environments in Malaysia was investigated in a batch system and by microscopic analyses. Under optimal biosorption conditions, the biosorption capacity of Chlorella sp. for copper and zinc ions was 33.4 and 28.5 mg/g, respectively, after 6 hr of biosorption in an immobilised system. Batch experiments showed that the biosorption capacity of algal biomass immobilised in the form of sodium alginate beads was higher than that of the free biomass. Scanning electron microscopy and energy-dispersive X-ray spectroscopy analyses revealed that copper and zinc were mainly sorbed at the cell surface during biosorption. Exposure to 5 mg/L of copper and zinc affected both the chlorophyll content and cell count of the algal cells after the first 12 hr of contact time.

关键词： green algae biosorption copper zinc immobilisation