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Application of diazo-thiourea and gold nano-particles in the design of a highly sensitive and selective DNA biosensor 被引量:4
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作者 Mohammad Hossein Mashhadizadeh Rasoul Pourtaghavi Talemi 《Chinese Chemical Letters》 SCIE CAS CSCD 2015年第1期160-166,共7页
An effective procedure for constructing a DNA biosensor is developed based on covalent immobilization of NH2 labeled,single strand DNA(NH2-ssDNA) onto a self-assembled diazo-thiourea and gold nanoparticles modified ... An effective procedure for constructing a DNA biosensor is developed based on covalent immobilization of NH2 labeled,single strand DNA(NH2-ssDNA) onto a self-assembled diazo-thiourea and gold nanoparticles modified Au electrode(diazo-thiourea/GNM/Au).Gold nano-particles expand the electrode surface area and increase the amount of immobilized thiourea and single stranded DNA(ssDNA) onto the electrode surface.Diazo-thiourea film provides a surface with high conductibility for electron transfer and a bed for the covalent coupling of NH2-ssDNA onto the electrode surface.The immobilization and hybridization of the probe DNA on the modified electrode is studied by differential pulse voltammetry(DPV) using methylene blue(MB) as a well-known electrochemical hybridization indicator.The linear range for the determination of complementary target ssDNA is from 9.5(±0.1) × 10^-13 mol/L to1.2(±0.2) x 10^-9 mol/L with a detection limit of 1.2(±0.1) 〉 10^-13 mol/L. 展开更多
关键词 DNA biosensor gold nano-particles THIOUREA Methylene blue
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Microstructure and mechanical properties of Mg-3Sn-1Ca reinforced with AlN nano-particles
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作者 Shaozhu Wang Yuanding Huang +7 位作者 Lixiang Yang Ying Zeng Yaozeng Hu Xiao Zhang Qiang Sun Shaojun Shi Guangyao Meng Norbert Hort 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2023年第1期259-269,共11页
Microstructural evolution and strengthening mechanisms of Mg-3Sn-1Ca based alloys with additions of different amounts of Al N nanoparticles were investigated.It was found that with increasing the amount of AlN nano-pa... Microstructural evolution and strengthening mechanisms of Mg-3Sn-1Ca based alloys with additions of different amounts of Al N nanoparticles were investigated.It was found that with increasing the amount of AlN nano-particles the grain size decreases obviously.The existence of AlN nano-particles could refine the primary crystal phases CaMgSn,which provided more heterogeneous nucleation sites for the formation of magnesium.Moreover,such nano-particles could also restrict the grain growth during solidification.After adding AlN nano-particles,both the tensile properties at room temperature and high temperature 250℃and the hardness are largely improved.The improvement of strength is attributed to grain refinement and second phase refinement. 展开更多
关键词 Mg-Sn-Ca alloy AlN nano-particles Microstructure Strengthening mechanisms Grain refinement
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Characteristics of Gold Mineralization at the Baguiomo Gold Panning Site, Koudougou Region, Burkina Faso, West Africa
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作者 Pascal Ouiya Aziz Fayçal Tarnagda Martial Eric Fozing 《Open Journal of Geology》 CAS 2024年第1期1-18,共18页
The Birimian Baguiomo formations are located in the northern part of the Boromo greenstone belt. In this belt, the volcanic rocks (tholeiitic basalt, calcalkaline basalt, andesite) hosting the gold mineralization are ... The Birimian Baguiomo formations are located in the northern part of the Boromo greenstone belt. In this belt, the volcanic rocks (tholeiitic basalt, calcalkaline basalt, andesite) hosting the gold mineralization are located in the Kwademen-Baguiomo shear zone. This mineralization, located only a few kilometers from the Kwademen gold deposit, is uncharacterized and, together with the latter, could constitute a gold potential capable of being economically exploitable. It is in this sense that this work is carried out with a view to characterizing the gold mineralization of the Baguiomo gold panning site. To carry out this work, we have made direct field measurements, combined with microstructures, and combined all this with data from geochemical rock analysis of the basalts that are the main host formations. Geochemical data show that tholeitic basalts formed from a mantle plume that was emplaced in an oceanic plateau context. Calc-alkaline basalts and andesites are comparable to Paleoproterozoic tholeitic basalts (PTH3), which are slightly enriched in light rare earths. Fertility tests show that these basalts concentrate between 3 and 6 ppb of gold at the time of accretion, which is sufficient for remobilization of this primary gold during the Eburnian orogeny to yield a deposit of around 4 - 5 Moz. Gold mineralization is associated with pyrite crystals when the latter are disseminated in the rock mass, whereas it is associated with hematite in quartz veins concordant with S1 shear deformation. It is mainly the pyrite crystals in the pressure shadows that contain the gold grains, whose development would be synchronous with micro-shear zone reactivation during the first phase of D1<sub>B</sub> deformation. The second phase of D2<sub>B</sub> deformation, which is a crenulation or fracture schistosity, does not significantly affect the shear deformation that controls mineralization. 展开更多
关键词 Kwademen-Baguiomo Shear Zone gold Panning Site gold Mineralization Eburnian Orogeny
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Assessing the Impact of Gold Mining on the Quality of Water Resources in the Commune of Meguet, Burkina Faso
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作者 Issoufou Ouedraogo Samuel Lankoande +3 位作者 Yacouba Konate Boukary Sawadogo Nicolas Kagambega Martin Lompo 《Journal of Water Resource and Protection》 CAS 2024年第4期281-292,共12页
Despite its often illegal nature, artisanal gold mining in Burkina Faso contributes to the economic and social development of the country. However, the rudimentary techniques used in gold panning have a significant im... Despite its often illegal nature, artisanal gold mining in Burkina Faso contributes to the economic and social development of the country. However, the rudimentary techniques used in gold panning have a significant impact on the environment due to inappropriate practices and the use of various chemical substances. This study aims to assess the impact of artisanal gold mining on the quality of water resources in a rural community at Méguet, Burkina Faso. To this end, surface and groundwater samples were collected and analyzed at the BUMIGEB laboratory. Field results show that the waters are slightly alkaline (6.97 < pH < 8.1), weakly mineralized and conductive (124 < EC < 543 μS/cm), with temperatures ranging from 24.6˚C to 31.6˚C. In addition, trace metals (TMEs) analyzed from surface and subsurface waters show very high levels, generally deviating from the levels recommended by WHO guidelines for Burkina Faso. Trace metals contamination of water resources in the commune of Méguet is mainly due to Fe (3.78 - 11.12 mg/kg), Hg (0.03 - 0.29 mg/kg), As (0.01- 6.31 mg/kg) and Pb (0.01 - 3.8 mg/kg). This study can serve as a basis for guiding national environmental policies to protect the water resources of the Méguet mine. 展开更多
关键词 gold Panning Water Quality Trace Metal Méguet Burkina Faso
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Origin of the Yueguang gold deposit in Xinhua, Hunan Province, South China: insights from fl uid inclusion and hydrogen–oxygen stable isotope analysis
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作者 Hongxin Fan Qiang Wang +2 位作者 Yulong Yang Yao Tang Hao Zou 《Acta Geochimica》 EI CAS CSCD 2024年第2期235-254,共20页
The Yueguang gold deposit is located in Fengjia,Xinhua County,Hunan Province,South China.It represents a recently discovered small-scale gold deposit situated in the southwestern region of the Jiangnan Orogenic Belt,w... The Yueguang gold deposit is located in Fengjia,Xinhua County,Hunan Province,South China.It represents a recently discovered small-scale gold deposit situated in the southwestern region of the Jiangnan Orogenic Belt,west of the Baimashan granitic batholith.In order to discern the characteristics of the ore-formingfluids,the underlying mineralization processes,and establish a foundation for the origin of the Yueguang gold depositfluid inclusion micro-thermometry,as well as quartz hydrogen and oxygen isotope analysis,have been carried out on samples obtained from various stages of mineralization.The hydrothermal miner-alization stages within the Yueguang gold deposit can be categorized into three stages:(i)the barren,pre-ore quartz-pyrite stage(Stage Ⅰ),the quartz-pyrite-gold stage(Stage Ⅱ),and the post-ore quartz-carbonate stage(Stage Ⅲ),with the second stage being the main mineralization stage.Thefluid inclusions identified in samples from the main min-eralization stage can predominantly be described with the NaCl–H_(2)O and CO_(2)–NaCl–H_(2)O systems.These inclusions display homogenization temperatures ranging from 158.8 to 334.9℃,and thefluid salinity ranges from 0.3%to 4.0%(wt.%NaCl equiv.).Laser Raman spectroscopy analysis of individual inclusions further reveals the presence of gas-phases such as CO_(2),CH_(4),and N_(2).Isotopic analysis indicatesδ^(18)Ofluid values ranging from 3.95 to 6.7‰ and δDH_(2)O values ranging from-71.9 to-55.7‰.These results indi-cate that the ore-formingfluid of the Yueguang gold deposit belongs to metamorphic hydrothermalfluids of middle-low temperature and low salinity.In the process of ore formation,gold is transported in the form of Au(HS)2-complexes,with gold deposition being driven byfluid immiscibility.Therefore,the Yueguang gold deposit is categorized as an orogenic gold deposit dominated by metamorphic hydrother-malfluid.It may become a new target for gold exploration in the Baimashan region,central Hunan Province. 展开更多
关键词 Hunan province Yueguang gold deposit Fluid inclusions Hydrogen–oxygen isotopes Laser Raman Fluid immiscibility Orogenic gold deposit
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Multi-Scale Approach for Gold Targeting in Côte d’Ivoire Paleoproterozoic Rocks
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作者 Martial Pohn Koffi Adingra Yao Augustin Koffi +3 位作者 N’guessan Nestor Houssou Zié Ouattara Tokpa Kakeu Lionel-Dimitri Boya Marc Ephrem Allialy 《Open Journal of Geology》 CAS 2024年第2期155-176,共22页
The aim of this study is to contribute to better targeting of gold prospecting areas using geospatial information. To this end, 3 mining sites were selected for the study. They are: the Sénoufo belt (Barrick Gold... The aim of this study is to contribute to better targeting of gold prospecting areas using geospatial information. To this end, 3 mining sites were selected for the study. They are: the Sénoufo belt (Barrick Gold mine), the Yaouré complex (Perseus Mining mine) and the South Fetêkro belt (Bonikro, Hiré and Agbaou mines). For this study, a multi-scale approach was carried out at regional, mine and microscopic levels. At the regional scale, a comparative analysis of 1:200,000 scale geological maps revealed that 3 main lithologies are regularly repeated on and around the various mining sites. These are: undifferentiated volcanics, metagranodiorites and metasiltites dominated by meta-arenites. Most of these lithologies are affected by undifferentiated faults generally oriented NE-SW, N-S, ENE-WSW and WNW-ESE. In addition, gold and manganese occurrences are present on all the sites studied. At the mine scale, radarsat-1 images processing indicate that the main mining sites are generally located near or at the intersection of lineaments-oriented NE-SW or N-S on the one hand and E-W or ENE-WSW or WNW-ESE or again NW-SE on the other. These mines are also located at the interface between zones of high and low lineament density. At the microscopic scale, petrographic studies of undifferentiated volcanic samples from the various sites indicate that they consist of andesites, meta-andesites and tuffs. 展开更多
关键词 gold Targeting Undifferentiated Volcanics Mineral Occurrences LINEAMENTS Côte d’Ivoire
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Biological Interaction and Imaging of Ultrasmall Gold Nanoparticles
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作者 Dongmiao Sang Xiaoxi Luo Jinbin Liu 《Nano-Micro Letters》 SCIE EI CSCD 2024年第3期69-98,共30页
Ultrasmall gold nanoparticles(AuNPs)typically includes atomically precise gold nanoclusters(AuNCs)and AuNPs with a core size below 3 nm.Serving as a bridge between small molecules and traditional inorganic nanoparticl... Ultrasmall gold nanoparticles(AuNPs)typically includes atomically precise gold nanoclusters(AuNCs)and AuNPs with a core size below 3 nm.Serving as a bridge between small molecules and traditional inorganic nanoparticles,the ultrasmall AuNPs show the unique advantages of both small molecules(e.g.,rapid distribution,renal clearance,low non-specific organ accumulation)and nanoparticles(e.g.,long blood circulation and enhanced permeability and retention effect).The emergence of ultrasmall AuNPs creates significant opportunities to address many challenges in the health field including disease diagnosis,monitoring and treatment.Since the nano–bio interaction dictates the overall biological applications of the ultrasmall AuNPs,this review elucidates the recent advances in the biological interactions and imaging of ultrasmall AuNPs.We begin with the introduction of the factors that influence the cellular interactions of ultrasmall AuNPs.We then discuss the organ interactions,especially focus on the interactions of the liver and kidneys.We further present the recent advances in the tumor interactions of ultrasmall AuNPs.In addition,the imaging performance of the ultrasmall AuNPs is summarized and discussed.Finally,we summarize this review and provide some perspective on the future research direction of the ultrasmall AuNPs,aiming to accelerate their clinical translation. 展开更多
关键词 Ultrasmall gold nanoparticle Cellular interaction Organ interaction Tumor interaction BIOIMAGING
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Geology and Geochemistry of K-feldspar Veins in Lamprophyre at the Zhenyuan Gold Deposit,Yunnan,Southwest China:Implications for Gold Mineralization
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作者 ZHANG Huichao CHAI Peng +2 位作者 ZHANG Hongrui ZHOU Limin HOU Zengqian 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2024年第1期104-116,共13页
Lamprophyres typically appear in hydrothermal gold deposits.The relationship between lamprophyres and gold deposits is investigated widely.Some researchers suggest that the emplacement of lamprophyres triggers gold mi... Lamprophyres typically appear in hydrothermal gold deposits.The relationship between lamprophyres and gold deposits is investigated widely.Some researchers suggest that the emplacement of lamprophyres triggers gold mineralization,whereas others hypothesize that the formation of lamprophyres increases the fertility of mantle sources and ore-forming fluids.K-feldspar veins,with ages between those of lamprophyres and gold deposits,appear in lamprophyres in Zhenyuan.Therefore,K-feldspar veins are ideal for investigating the relationship between lamprophyres and gold deposits.Phlogopite in K-feldspar veins has lower Mg#,Ni,and Cr contents and higher TiO2,Li,Ba,Sr,Sc,Zr,Nb,and Cs contents than phlogopite in lamprophyres.The in-situ Sr isotopic values of apatites(0.7063–0.7066)in K-feldspar veins are within the range for apatites(0.7064–0.7078)from lamprophyres.High large-ion lithophile element concentrations and low Nb and Ta concentrations in phlogopite from lamprophyres,in addition to high(87Sr/86Sr)i values of apatite(0.7064–0.7078),indicate that the magma parental to these phlogopite and apatite crystals is derived from an enriched mantle.Kfeldspar veins are genetically correlated with lamprophyres,whereas sulfide mineral assemblage and trace element compositions of pyrite in K-feldspar veins suggest that K-feldspar veins in lamprophyres are not directly related to gold mineralization of the Zhenyuan deposit. 展开更多
关键词 LAMPROPHYRE K-feldspar vein apatite Sr isotope gold Zhenyuan deposit YUNNAN
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Enhancing Geological Understanding and Identifying Gold Anomalies in the Ailaoshan Orogen
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作者 ZHAO Shiyu YANG Lin +5 位作者 SONG Yiwei DONG Yuntao FENG Lihao LI Huajian WU Junyu WANG Qingfei 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2024年第2期441-453,共13页
The Ailaoshan Orogen in the southeastern Tibet Plateau,situated between the Yangtze and Simao blocks,underwent a complex structural,magmatic,and metamorphic evolution resulting in different tectonic subzones with vary... The Ailaoshan Orogen in the southeastern Tibet Plateau,situated between the Yangtze and Simao blocks,underwent a complex structural,magmatic,and metamorphic evolution resulting in different tectonic subzones with varying structural lineaments and elemental concentrations.These elements can conceal or reduce anomalies due to the mutual effect between different anomaly areas.Dividing the whole zone into subzones based on tectonic settings,ore cluster areas,or sample catchment basins(Scb),geochemical and structural anomalies associated with gold(Au)mineralization have been identified utilizing mean plus twice standard deviations(Mean+2STD),factor analysis(FA),concentration-area(CA)modeling of stream sediment geochemical data,and lineament density in both the Ailaoshan Orogen and the individual subzones.The FA in the divided 98 Scbs with 6 Scbs containing Au deposits can roughly ascertain unknown rock types,identify specific element associations of known rocks and discern the porphyry or skarn-type Au mineralization.Compared with methods of Mean+2STD and C-A model of data in the whole orogen,which mistake the anomalies as background or act the background as anomalies,the combined methods of FA and C-A in the separate subzones or Scbs works well in regional metallogenic potential analysis.Mapping of lineament densities with a 10-km circle diameter is not suitable to locate Au deposits because of the delineated large areas of medium-high lineament density.In contrast,the use of circle diameters of 1.3 km or 1.7 km in the ore cluster scale delineates areas with a higher concentration of lineament density,consistent with the locations of known Au deposits.By analyzing the map of faults and Au anomalies,two potential prospecting targets,Scbs 1 and 63 with a sandstone as a potential host rock for Au,have been identified in the Ailaoshan Orogen.The use of combined methods in the divided subzones proved to be more effective in improving geological understanding and identifying mineralization anomalies associated with Au,rather than analyzing the entire large area. 展开更多
关键词 minerology GEOCHEMISTRY gold stream sediment sample catchment basin concentration-area model lineament density Ailaoshan Orogen
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Lithostructural Control of the Gold Mineralization of the Douta Permit of African Star Resources (Kédougou-Kéniéba Inlier, Southeastern Senegal)
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作者 Masse Ndour Papa Moussa Ndiaye +3 位作者 Koffi Félix Ekra Alain Ndong Malick Faye Pierre Ndour 《International Journal of Geosciences》 CAS 2024年第4期303-333,共31页
The Douta permit of African Star Resources/Thor Explorations, located in the southeast of Senegal, in the Kédougou-Kéniéba Inlier (western part of the West African Craton), is dominated to the East by m... The Douta permit of African Star Resources/Thor Explorations, located in the southeast of Senegal, in the Kédougou-Kéniéba Inlier (western part of the West African Craton), is dominated to the East by metasedimentary formations such as greywackes, shales, graphitic shales, quartzites, cherts, claystones and breccias characteristic of the Dialé-Daléma basin. To the West, the mafic formations of the Mako volcanic belt are the most common. Metasedimentary rocks are associated with metavolcanosedimentary terms found at the contact zones between the two (2) Birimian groups. These different geological formations are cut by mafic dolerite and gabbro sills and/or dykes, as well as quartz and microgranite veins. The Douta gold project is crossed from North to South by the MTZ (Main Transcurrent Zone), generally oriented NE-SW and becoming N-S towards the North. The permit is characterized by several shear corridors. The rocks are affected by brittle, brittle-ductile to ductile deformations. The gold mineralization is hosted by a NE-trending shear corridor called the Makosa corridor (Makosa shear zone), therefore sub-parallel to the MTZ. It has a subvertical dip (75˚ to 85˚ to the NW). It is associated with a hydrothermal phase characterized by quartz-sericite-epidote-fine, disseminated pyrite and arsenopyrite ± albite ± chlorite paragenesis. These minerals testify to the existence of a low degree of metamorphism (greenschist facies, epizonal domain) in the area. However, metamorphism reaches amphibolite facies in some places, particularly in the vicinity of intrusive bodies, with the presence of hornblende (amphiboles) and plagioclase. The gold mineralization is mainly hosted by two (2) metasedimentary lithological units: meta-greywackes and shales. 展开更多
关键词 Douta Kédougou-Kéniéba Inlier Senegal Metasedimentary MTZ Control gold Mineralization Makosa Corridor
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Source of metals related to gold occurrences in Cameroon, Central African Belt
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作者 Kevin Igor Azeuda Ndonfack Jinlin Zhang +2 位作者 Yuling Xie NSamiratou Yaya Emmanuel Archelaus Afanga Basua 《Acta Geochimica》 EI CAS CSCD 2024年第2期308-324,共17页
Suites of granitic and metamorphic rocks form a perfect geological environment in which to investigate the source of metals related to gold deposits.In the East Province of Cameroon,the source of metals-related gold(g... Suites of granitic and metamorphic rocks form a perfect geological environment in which to investigate the source of metals related to gold deposits.In the East Province of Cameroon,the source of metals-related gold(grade~4.6 g/t)that occurs within metamorphic and granitic rocks remains ambiguous.The host rocks were subjected to XRF and ICP-MS whole-rock geochemistry and BSE/EDS mineral analyses to investigate the source(s)of metals related to gold in the Province.Petrographically,chalcopyrite-pyrite and magnetite-ilmenite are the main sulfi des and oxides of granites,respectively.The low-grade metamorphic rocks are sulfi de-rich consisting of arsenopyrite,chalcopyrite,pyrite,and sphalerite,and oxides include magnetite,ilmenite,hematite,and rutile.Cu,Ni,Co,Sb,Sc,and Zn concentrations depleted in high-grade metamorphic rocks and granites compared to low-grade metamorphic rocks.As well,Bi,Cd,Co,Cu,Ni,Sb,V,W,and Zn concentrations decrease with increasing temperatures from low-grade rocks to high-grade rocks and granites.The suite of depleted elements in high-grade rocks and granites is almost identical to those enriched in gold occurrences.We conclude that metals(Bi,Cd,Co,Cu,Ni,Sb,and Zn)related to gold mineralization in the East Province of Cameroon likely originated from metal-rich low-grade metamorphic rocks during prograde metamorphic processes prior to partial melting. 展开更多
关键词 East Province of Cameroon Metamorphic rocks GRANITES Oxide–sulfides Metal and gold GEOCHEMISTRY
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Experimental Abrasion Study of the Evolution of Gold Morphological Criteria in Different Sediments as a Function of Time
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作者 Fary Diome 《Open Journal of Soil Science》 2024年第1期13-27,共15页
The use of gold as a tracer element for understanding the mode of emplacement of these formations requires a good knowledge of its dynamics. To this end, we have carried out experimental studies to investigate the evo... The use of gold as a tracer element for understanding the mode of emplacement of these formations requires a good knowledge of its dynamics. To this end, we have carried out experimental studies to investigate the evolution of contour states (regular, irregular), surface states (blunt, rough), shape (elongation) and dimension (size). The study of these criteria is carried out on SEM photos of particles, taken before and after the experiment, using Aphelion image processing software. Five experiments were carried out to study the influence of sediment granulometry and water dilution on particle morphological changes. The results of these experiments show that coarse sediments (>1 mm) are largely responsible for morphological changes in gold. They cause fragmentation and/or folding of the particle edges, depending on the magnitude of the impact forces. Strong impacts due to high water dilution cause staking on the particle surface. Fine sediments (<1 mm) slow down particle evolution as they cushion impacts and particles tend to flatten rather than fragment. 展开更多
关键词 Weathering Mantles Experimental Abrasion gold
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Gold Mineralisation in the Intiédougou Prospect (Diébougou District) in Southwest Burkina Faso, West African Craton
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作者 Yao Honoré Koffi Wendkouni Passecdé Pauline Zongo +1 位作者 Nanema Mathieu Urbain Wenmenga 《Journal of Minerals and Materials Characterization and Engineering》 2024年第1期63-77,共15页
The Intiédougou located in the Houndé Birimian greenstone belt has been the subject of several mining and geoscience studies that have led to the discovery of mineralized gold targets. One of these mineraliz... The Intiédougou located in the Houndé Birimian greenstone belt has been the subject of several mining and geoscience studies that have led to the discovery of mineralized gold targets. One of these mineralized targets has prompted work that raises the issue of control factors for the gold mineralization of the prospect. The methodology used in this study combines a study of core drill hole data located in the area and laboratory studies. The Intiédougou sector is based on andesito-basaltic, andesitic interstratified volcanoclastite rocks and Tarkwaïen type detrital sedimentary rocks caught in a vice in the volcano-sedimentary unit. Lithostructural analysis of the sector shows that the subvolcanic rocks bearing gold mineralization are subjected to heterogeneous ductile to brittle deformations and affected by hydrothermalism evolving at stages marked by large fissure fillings. These hydrothermal phases evolve in the zones of expansion created by the brittle deformations that have contributed to the deposits of different types of gold-enriched sulphides. These different phases of hydrothermal destabilization generally of low degree accompany the tardi to post-eburnean brittle tectonics. This deformation system is favorable to the establishment of gold mineralization in the form of vein bodies. The overimposition of deformed and altered areas suggests a genetic relationship between deformation and hydrothermal activity. In conclusion, the mineralization of Intiédougou in vein styles, set up in a volcanic arc environment with a paragenesis of gold-pyrite deposit ± chalcopyrite would be controlled by the structural aspect and accompanied by hydrothermal alteration. 展开更多
关键词 Intiédougou Prospect SHEAR HYDROTHERMAL Tarkwaïan gold Mineralization
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Characteristics of Gold and Its Mineralization Style in the Boulon Djounga Eastern Perimeter of Liptako Mining Company (Central Southwestern Niger)
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作者 Gambo Ranaou Noura Kamayé Tourba +2 位作者 Karimou Dia Hantchi Bouba Hassane Moussa Konaté 《Natural Resources》 2024年第1期28-50,共23页
The Boulon Djounga eastern perimeter is part of the Tiawa operating permit of the Société des Mines du Liptako (SML), located in the central southwestern part of Liptako (Niger). In this study, we used field... The Boulon Djounga eastern perimeter is part of the Tiawa operating permit of the Société des Mines du Liptako (SML), located in the central southwestern part of Liptako (Niger). In this study, we used field data, Reverse Circulation (RC) surveys and chemical analyzes of gold to determine the characteristics of gold and its mineralization style. The eastern perimeter of Boulon Djounga is represented by a succession of metabasalts and metasediments both intersected by intrusions of quartz and dolerite dykes, and covered by sandstone and clayey rocks. Gold is present in low contents (0.00 - 0.30 ppm) in the sedimentary cover and in medium (0.30 - 1.00 ppm) or high contents (1.00 - 4.534 ppm) in the metasediments, and in the gray quartz veins and locally in the volcanics. It exists in a disseminated state or in a concentrated state in the surrounding areas in the form of discrete grains associated with sulphurous minerals (pyrite: FeS<sub>2</sub>, chalcopyrite: CuFeS<sub>2</sub> or arsenopyrite: FeAsS). The presence of gold in the quartz veins, and the NE-SW and NW-SE orientations of the ore bodies suggest that the eastern Boulon Djounga gold mineralization would be established during a late magmatic extensive phase. 展开更多
关键词 Liptako gold Mineralization Metasediments-Volcanics Quartz Veins Sulphurous Minerals NIGER
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Simulated patient methodology as a“gold standard”in community pharmacy practice:Response to criticism
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作者 Christian Kunow Bernhard Langer 《World Journal of Methodology》 2024年第2期172-174,共3页
The simulated patient methodology(SPM)is considered the“gold standard”as covert participatory observation.SPM is attracting increasing interest for the investigation of community pharmacy practice;however,there is c... The simulated patient methodology(SPM)is considered the“gold standard”as covert participatory observation.SPM is attracting increasing interest for the investigation of community pharmacy practice;however,there is criticism that SPM can only show a small picture of everyday pharmacy practice and therefore has limited external validity.On the one hand,a certain design and application of the SPM goes hand in hand with an increase in external validity.Even if,on the other hand,this occurs at the expense of internal validity due to the trade-off situation,the justified criticism of the SPM for investigating community pharmacy practice can be countered. 展开更多
关键词 Simulated patient methodology Community pharmacy gold standard Covert participatory observation Internal validity External validity
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关于2023年版GOLD的若干思考
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作者 何权瀛 《中国医药导刊》 2023年第2期127-131,共5页
慢性阻塞性肺病(COPD)是全球主要的公共卫生问题之一,其患病率和死亡率全世界(包括亚太地区)日渐增多。为遏制COPD全球增加趋势,早在2001年,COPD全球倡议(GOLD)专家小组发布了首版GOLD,即COPD的诊断、治疗和预防的全球策略。2011年版GOL... 慢性阻塞性肺病(COPD)是全球主要的公共卫生问题之一,其患病率和死亡率全世界(包括亚太地区)日渐增多。为遏制COPD全球增加趋势,早在2001年,COPD全球倡议(GOLD)专家小组发布了首版GOLD,即COPD的诊断、治疗和预防的全球策略。2011年版GOLD针对2001年版GOLD中的COPD治疗策略进行大范围修改。2017年后,每年进行更新[1-6],以期更加全面地反映世界范围内COPD的临床科研进展,涵盖的内容日臻丰富和新颖,世界范围内广受好评。2022年12月发布的2023年版GOLD[7],全文共192页,内容全面细致新颖,参考文献达1594篇。鉴于此,本研究梳理了2023年版GOLD更新要点,针对COPD相关疾病和问题展开探讨和分析,以期为临床治疗该病提供理论参考。 展开更多
关键词 专家小组 gold 全球策略 科研进展 公共卫生问题 治疗策略 COPD 患病率
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Microstructure and Oxidation Behaviors of Nano-particles Strengthened NiCoCrAlY Cladded Coatings on Superalloys 被引量:12
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作者 WANG Hongyu ZUO Dunwen +2 位作者 CHEN Xinfeng YU Shouxin GU Yuanzhi 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2010年第3期297-304,共8页
Nano-particles which can largely improve the microstructure and oxidation resistance of materials are often used as a strengthening component in metal matrix composites. However, few studies were reported on its appli... Nano-particles which can largely improve the microstructure and oxidation resistance of materials are often used as a strengthening component in metal matrix composites. However, few studies were reported on its application in the bond coat of duplex structure thermal barrier coating(TBC). Three kinds of NiCoCrAlY coatings strengthened by different nano-particles with the same addition (1%, mass fraction) were prepared by the laser cladding technique on Ni-based superalloy substrates, aiming to study the effects of the nano-particles on microstructure and oxidation resistance of NiCoCrAlY coatings (the bond coat of the duplex structure thermal barrier coatings). Scanning electron microscope (SEM), X-ray diffractometer(XRD) and thermogravimetry were employed to investigate their morphologies, phases and cyclic oxidation behaviors in atmosphere at 1 050℃, compared with the coating without nano-particles. With the addition of nano-particles, the growth pattern of the grains at the interface changed from epitaxial growth to non-epitaxial growth or part-epitaxial growth; slender dendrites were broken and cellularized; cracks and pores were restrained; and the oxidation weight-gain and the stripping resistance of the oxide scale were improved as well. Among the three kinds of nano-particles, the SiC nano-particles showed the most improvement on microstructure, while the CeO2 nano-particles were insufficient, but its effects on the oxidation resistance are the same as those of the SiC nano-particles. Based on the discussions of the influence mechanism, it is believed that CeO2 nano-particles would show better improvement than SiC nano-particles if the proper amount is added and the proper preparation technique of micro-nanometer composite powders is adopted, with the synergistic action of nanometer effect and reactive element effect. 展开更多
关键词 high-temperature protective coating nano-particlE MICROSTRUCTURE cyclic oxidation laser cladding
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Surface tension of lithium bromide aqueous solution/ammonia with additives and nano-particles 被引量:2
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作者 蔡伟华 孔伟伟 +2 位作者 王悦 朱蒙生 王新雷 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第5期1979-1985,共7页
In order to investigate the effect of additives and nano-particle on the surface tensions of lithium bromide(Li Br) aqueous solution/ammonia, many experiments were carried out based on Wilhelmy plate method. Firstly, ... In order to investigate the effect of additives and nano-particle on the surface tensions of lithium bromide(Li Br) aqueous solution/ammonia, many experiments were carried out based on Wilhelmy plate method. Firstly, the surface tension of Li Br aqueous solution with 1-octanol was measured and then the comparison between the measured results and previous experimental results was given to verify the measuring accuracy. Some new additives, such as cationic surfactants cetyltrimethyl ammonium chloride(CTAC), and cetyltrimethyl ammonium bromide(CTAB) were chosen in the experiments. The experimental results show that CTAC and CTAB can obviously reduce the surface tension of Li Br aqueous solution/ammonia. In addition, it is found that nano-particles cannot remarkably decrease the surface tension of Li Br aqueous solution/ammonia. However, the mixed addition of additives and nano-particles can remarkably affect the surface tension of Li Br aqueous solution/ammonia. That is to say, additives play more important role in reducing the surface tension of Li Br aqueous solution/ammonia. But nano-particles may enhance the heat transfer in the absorption refrigeration process. 展开更多
关键词 lithium bromide AMMONIA ADDITIVES nano-particles surface tension
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Conditions for laser-induced plasma to effectively remove nano-particles on silicon surfaces 被引量:1
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作者 韩敬华 罗莉 +2 位作者 张玉波 胡锐峰 冯国英 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第9期423-428,共6页
Particles can be removed from a silicon surface by means of irradiation and a laser plasma shock wave.The particles and silicon are heated by the irradiation and they will expand differently due to their different exp... Particles can be removed from a silicon surface by means of irradiation and a laser plasma shock wave.The particles and silicon are heated by the irradiation and they will expand differently due to their different expansion coefficients,making the particles easier to be removed.Laser plasma can ionize and even vaporize particles more significantly than an incident laser and,therefore,it can remove the particles more efficiently.The laser plasma shock wave plays a dominant role in removing particles,which is attributed to its strong burst force.The pressure of the laser plasma shock wave is determined by the laser pulse energy and the gap between the focus of laser and substrate surface.In order to obtain the working conditions for particle removal,the removal mechanism,as well as the temporal and spatial characteristics of velocity,propagation distance and pressure of shock wave have been researched.On the basis of our results,the conditions for nano-particle removal are achieved. 展开更多
关键词 laser-induced plasma shock wave nano-particles surface cleaning
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激光诱导击穿光谱的Gold去卷积算法自动寻峰
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作者 王永祥 姚明印 陈万钧 《量子电子学报》 CAS CSCD 北大核心 2023年第6期816-826,共11页
为提高激光诱导击穿光谱(LIBS)寻峰中重叠谱的分辨能力并抑制随机噪声的干扰,提出用Gold去卷积算法结合平滑处理的自动寻峰方法。对于标准样品NIST 1256b和NIST 1762的LIBS光谱,先进行平滑处理,然后采用高斯形系统函数去卷积,最后用五... 为提高激光诱导击穿光谱(LIBS)寻峰中重叠谱的分辨能力并抑制随机噪声的干扰,提出用Gold去卷积算法结合平滑处理的自动寻峰方法。对于标准样品NIST 1256b和NIST 1762的LIBS光谱,先进行平滑处理,然后采用高斯形系统函数去卷积,最后用五点法对去卷积结果进行自动寻峰。实验研究了平滑处理结合不同半峰全宽(FWHM)的系统函数对重叠峰分辨能力和抗随机噪声干扰能力的影响。结果表明,采用0.140 nm(比弱峰的FWHM稍大)作为Gold去卷积系统函数的FWHM,结合平滑处理能取得高达0.039 nm的重叠谱分辨能力,且寻峰峰位、峰值、曲线拟合与NIST数据库的数据都能较好地吻合。研究初步表明基于Gold去卷积算法的自动寻峰可应用于LIBS数据处理。 展开更多
关键词 光谱学 光谱自动寻峰 激光诱导击穿光谱 gold去卷积算法 重叠峰分辨
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