The Elogo region has been subjected to craft industry and semi-industrial mining for gold-bearing placers, since the colonial times. It is actually undergoing an intensive exploration for a primary gold deposit. The g...The Elogo region has been subjected to craft industry and semi-industrial mining for gold-bearing placers, since the colonial times. It is actually undergoing an intensive exploration for a primary gold deposit. The goal of this study is to contribute to the exploration of the primary gold deposit in the Elogo Region (North-West of Congo Republic). The methodology consisted of characterization of placers deposits by their lithology, mineralogy and the gold grains shape, in order to constrain the source of gold with the respect to the local geology. The results obtained show that alluviums are polygenic and yields seventeen mineral species composed of zircon, olivine, magnetite, ilmenite, gold, garnet, rutile, coltan, cassiterite, monazite, apatite, amphibole, tourmaline, pyrite, limonite, chromite, and amphibole. The morphoscopy of gold grain shows single grains and grains with quartz inclusions that suggest their relationship with quartz veins. The gold grains are flattened, sub-flattened, and rounded. The northern region of Elogo characterized by a dominance of coarser quartz-included gold grains indicates a proximal proparte origin (less than 50 m), while the southern region, showing less coarse and more evolved grains with choc marks, appears to be associated with a distal pro-parte origin (more than 300 m). The multivariate statistical analysis shows seven classes of samples corresponding to the mineralogical paragenesis suggesting various sources, consisting of high-grade metamorphic, granitoids, pegmatites, basic and ultrabasic rocks, and BIFs that provided minerals to the placers. Gold mainly comes from hydrothermal quartz veins and probably from the peptization of gold from the weathering of sulfides occurring in the BIF. In the Elogo region, gold exploration for primary deposits should look for and follow the hydrothermal system developed in this region. Chemical analysis for the gold grains and associated minerals is necessary to better guide the proposed geochemical prospecting.展开更多
The stream sediments of Wadi El Reddah(North Eastern Desert,Egypt)are geochemically and mineralogically investigated.Their content of radioactive and other heavy minerals is mainly represented by thorite,uranothorite,...The stream sediments of Wadi El Reddah(North Eastern Desert,Egypt)are geochemically and mineralogically investigated.Their content of radioactive and other heavy minerals is mainly represented by thorite,uranothorite,zircon,monazite,xenotime,columbite,fergusonite,and unknown rare earth elements(REEs)bearing minerals as well as cassiterite.Special emphasis on REE content of thorite,uranothorite,zircon and xenotime has been done to correlate them with the increase of uranium contents in these sediments.The key evidence for the presence lowtemperature alteration processes includes the presence of some zircon crystals as remnants after complete dissolution of the overgrowth zircon in severe acidic environment,the sulphur content,biogenic minerals,occurrence of unusual minerals as cassiterite pore filling in zircon,variation in the REEs content from the surrounding granites to the stream sediments and the abundance of monazite in the surrounding granites.Most minerals are partially and/or completely altered,which indicated by the pseudomorphism of zircon by xenotime,thorite,and uranothorite.展开更多
Electrochemical measurements were conducted to study the electrochemical behavior of gold （Au） and its commonly associated minerals in alkaline thiourea solutions. The results indicated that without addition of any ...Electrochemical measurements were conducted to study the electrochemical behavior of gold （Au） and its commonly associated minerals in alkaline thiourea solutions. The results indicated that without addition of any stabilizer, selective dissolution of Au from stibnite and pyrite was only possible at relatively low thiourea concentrations. As Na2SiO3 was added, pyrite started to become active and an oxida- tion peak appeared; the oxidation peaks of axsenopyrite and chalcocite appeared earlier thaxl that of Au. The chalcocite peak shifted in the positive direction and the peak current increased. Stibnite did not show an oxidation peak and its current was nearly zero. Adding Na2SiO3 favored the selective dissolution of Au when its minerals were associated with chalcocite and stibinte. At pH 12, the Au anode dissolution peak current increased with stabilizer concentration. At 0.38 and 0.42 V and for Na2SiO3 concentration below 0.09 M, the current density continuously increased with Na2SiO3 concentration. The Na2SiO3 concentration had to be adequate to stabilize thiourea. When the potential was higher than 0.42 V, the surface of the Au electrode started to passivate. With an additional increase in potential, the presence of Na2SiO3 could not stop the inevitable decomposition of thiourea.展开更多
藓结皮是荒漠生物土壤结皮的重要类型,在荒漠生态系统碳固定与碳排放过程中具有重要作用。研究长期氮添加对藓结皮光合生理活性和土壤有机碳(SOC)组分的影响,有助于理解藓结皮光合生理活性特征与荒漠生态系统土壤碳固存之间的关系及其...藓结皮是荒漠生物土壤结皮的重要类型,在荒漠生态系统碳固定与碳排放过程中具有重要作用。研究长期氮添加对藓结皮光合生理活性和土壤有机碳(SOC)组分的影响,有助于理解藓结皮光合生理活性特征与荒漠生态系统土壤碳固存之间的关系及其调控因子。为此,研究依托古尔班通古特沙漠野外长期(13a)氮添加实验,以齿肋赤藓形成的藓结皮为研究对象,选取0(N0)、1.0(N1)、3.0 g N m-2a-1(N3)三种氮处理,阐明长期氮添加对藓结皮光合生理活性和SOC组分的影响。结果表明:(1)相比对照,长期氮添加对结皮层颗粒有机碳(POC)与矿物结合态有机碳(MAOC)含量无显著影响,但显著减少了0—5 cm土层POC和MAOC含量的积累;(2)N1处理显著提高了叶绿素和非结构性碳水化合物(NSC)含量,而N3处理叶绿素a、叶绿素b、总叶绿素及NSC的含量分别显著降低了50.94%、42.49%、46.71%和50.85%;(3)可溶性糖的含量在N1处理下显著增加,N3处理则显著抑制了其积累,脯氨酸的含量随氮浓度呈显著下降的趋势,长期氮添加对可溶性蛋白含量无显著影响;(4)相关性分析表明,长期氮添加、光合生理活性与POC和MAOC含量无显著相关性,酸碱度、微生物量碳氮、电导率、硝态氮和铵态氮皆显著影响POC和MAOC的含量积累。研究揭示了长期氮添加对藓结皮的光合生理活性和SOC组分的影响,且光合生理活性的响应无法有效反映SOC组分变化,为理解荒漠生态系统中氮沉降对生物土壤结皮的影响提供数据支持。展开更多
背景:观察性研究表明他汀类药物可能对骨密度具有保护作用,这使其成为潜在的骨质疏松症治疗药物之一。目的:通过孟德尔随机化方法来评估药物靶点介导的脂质表型与骨密度之间的因果关系。方法:从IEU Open GWAS数据库获取了与他汀类药物...背景:观察性研究表明他汀类药物可能对骨密度具有保护作用,这使其成为潜在的骨质疏松症治疗药物之一。目的:通过孟德尔随机化方法来评估药物靶点介导的脂质表型与骨密度之间的因果关系。方法:从IEU Open GWAS数据库获取了与他汀类药物相关的单核苷酸多态性以及骨密度相关数据。主要分析方法是逆方差加权法,同时也使用了加权中位数法、简单中位数法、加权中值方法和MR-Egger回归法。使用β值和95%CI来评估他汀类药物与骨密度之间的因果关系;另外,进行敏感性分析以验证结果的可靠性,使用Cochran’s Q检验来评估异质性,使用MR-Egger截距检验是否存在水平多效性。使用留一法分析确定是否有单个或多个单核苷酸多态性影响了结果。结果与结论:他汀类药物作用靶点——3-羟基-3-甲基戊二酰辅酶A还原酶介导的低密度脂蛋白胆固醇与足跟定量超声骨密度(β=-0.086,95%CI:-0.117至-0.055,P=5.42×10^(-8))和全身骨密度(β=-0.193,95%CI:-0.288至-0.098,P=7.35×10^(-5))呈显著相关。该研究结果支持了他汀类药物对骨密度的保护作用。这些发现不仅加深了对胆固醇相关基因和骨骼健康关系的理解,还揭示了改善骨密度的潜在治疗靶点。展开更多
背景:既往研究表明,中老年人体内组织蛋白酶K水平可通过影响骨密度来干预骨质疏松的发生和发展,但组织蛋白酶家族与其他人群骨密度之间是否存在因果关系仍未知。目的:探讨组织蛋白酶与骨密度的因果关系。方法:从IEU Open GWAS数据库提取...背景:既往研究表明,中老年人体内组织蛋白酶K水平可通过影响骨密度来干预骨质疏松的发生和发展,但组织蛋白酶家族与其他人群骨密度之间是否存在因果关系仍未知。目的:探讨组织蛋白酶与骨密度的因果关系。方法:从IEU Open GWAS数据库提取与8种组织蛋白酶相关的遗传位点作为工具变量,以5个年龄段人群的骨密度作为结局。通过双向孟德尔随机化分析,评估组织蛋白酶与骨密度的因果关系。使用Cochran’s Q检验评估遗传工具变量的异质性,使用MR-Egger截距检验评估多效性,使用留一法评估作为工具变量的单核苷酸多态性对暴露和结局因果关系影响的敏感性。结果与结论:①正向孟德尔随机化的逆方差加权法结果显示,组织蛋白酶H与>45岁且≤60岁人群的骨密度呈负相关[OR(95%CI)=0.965(0.94-0.99),P=0.04],组织蛋白酶Z与>30岁且≤45岁人群的骨密度呈负相关[OR(95%CI)=1.06(1.00-1.11),P=0.03];②敏感性分析结果显示因果关系稳定,MR-Egger截距分析未检测到潜在的水平多效性;③反向孟德尔随机化结果显示,骨密度对组织蛋白酶无显著反向作用;④上述结果证实,组织蛋白酶对部分年龄段人群骨密度会造成影响,可能会增加骨质疏松症的发病风险,应给予更多关注。展开更多
SANJING region (the region of three rivers, i.e. Jinsha-Lanchang-Nujiang rivers) is a very active Cenozoicinterplate deformation area on the east margin of Qinghai-Xizang Plateau, where the alkali-rich porphyrybodies ...SANJING region (the region of three rivers, i.e. Jinsha-Lanchang-Nujiang rivers) is a very active Cenozoicinterplate deformation area on the east margin of Qinghai-Xizang Plateau, where the alkali-rich porphyrybodies occur extensively and the porphyry-related polymetallic mineral resources are produced. Manystudies on the petrology and geochemistry of the alkali-rich porphyry have been carried out and thegenerally accepted conclusion is that the petrogenesis material source has something to do with the enriched source in the mantle. The integrated interactive factors of the mineralization related to the alkalirich porphyry consist in the favourable combination of the mantle fluid metasomatism, which is derivedfrom the deep processes, and the conducting and controlling roles of the large-scale deep faults. Alongwith the changes in physical and chemical conditions caused by the diffusion of the ore-forming展开更多
In this paper,the effect of low-temperature treatment on bacterial activity was investigated and its performance in preparing the consolidated sand was accessed.Four factors,including absorbance(OD600),p H,electric co...In this paper,the effect of low-temperature treatment on bacterial activity was investigated and its performance in preparing the consolidated sand was accessed.Four factors,including absorbance(OD600),p H,electric conductivity(EC)and urease activity(UA)were monitored to evaluate the bacterial activity.Moreover,the calcium carbonate yields under different bacterial solution and cementation solution volume ratios were determined.Finally,the compressive strength and microstructure of consolidated sand were investigated and the mechanism was explored by characterising the products among sand particles.The results showed that for both continuous and interval cultivation of bacteria,stable bacterial solution was harvested within the cultivation period of 30 h.Low-temperature treatment showed limited inhibition at early cultivation stage,while it had strong inhibition at middle cultivation stage.The interval cultivation improved the cultivation efficiency of bacteria.It was observed that the low-temperature preservation for a stable bacterial solution has little influence on UA before 4 days,while UA decreased seriously after its preservation time was extended to over 8 days.The optimal volume ratio of bacterial solution and substrate solution was 1:1,resulting in the highest calcium carbonate yield.The improved compressive strength of consolidated sand after 3 injections was attributed to the irregular-shaped calcite products,which coated and bonded the sand grains together.展开更多
THE low-temperature mineralization province is a concept relative to low-temperature hydrothermal ore deposits, which refers to a special area where low-temperature hydrothermal deposits are concentrated ingroups. In ...THE low-temperature mineralization province is a concept relative to low-temperature hydrothermal ore deposits, which refers to a special area where low-temperature hydrothermal deposits are concentrated ingroups. In Southwest China there is an area of about 90 x 10 km where there are widely developed lowtemperature hydrothermal ore deposits. This area is the so-called vast low-temperature mineralizationprovince in Southwest China. This mineralization province is so large in area, so diverse in ore type andso numerous in mineralization belt that no other one could be found in other parts of the world. In recentyears of study the following features have been obtained. (i) This mineralization province is, for the most part, located in the southwestern part of theYangtze Block and extends to the Southwest Folded Zone and part of the Sanjiang (the three-river) Foldedzone adjacent to the Yangtze Craton. (ii) The mineralization province is of double-layered structure. At the basement there are devel-展开更多
文摘The Elogo region has been subjected to craft industry and semi-industrial mining for gold-bearing placers, since the colonial times. It is actually undergoing an intensive exploration for a primary gold deposit. The goal of this study is to contribute to the exploration of the primary gold deposit in the Elogo Region (North-West of Congo Republic). The methodology consisted of characterization of placers deposits by their lithology, mineralogy and the gold grains shape, in order to constrain the source of gold with the respect to the local geology. The results obtained show that alluviums are polygenic and yields seventeen mineral species composed of zircon, olivine, magnetite, ilmenite, gold, garnet, rutile, coltan, cassiterite, monazite, apatite, amphibole, tourmaline, pyrite, limonite, chromite, and amphibole. The morphoscopy of gold grain shows single grains and grains with quartz inclusions that suggest their relationship with quartz veins. The gold grains are flattened, sub-flattened, and rounded. The northern region of Elogo characterized by a dominance of coarser quartz-included gold grains indicates a proximal proparte origin (less than 50 m), while the southern region, showing less coarse and more evolved grains with choc marks, appears to be associated with a distal pro-parte origin (more than 300 m). The multivariate statistical analysis shows seven classes of samples corresponding to the mineralogical paragenesis suggesting various sources, consisting of high-grade metamorphic, granitoids, pegmatites, basic and ultrabasic rocks, and BIFs that provided minerals to the placers. Gold mainly comes from hydrothermal quartz veins and probably from the peptization of gold from the weathering of sulfides occurring in the BIF. In the Elogo region, gold exploration for primary deposits should look for and follow the hydrothermal system developed in this region. Chemical analysis for the gold grains and associated minerals is necessary to better guide the proposed geochemical prospecting.
文摘The stream sediments of Wadi El Reddah(North Eastern Desert,Egypt)are geochemically and mineralogically investigated.Their content of radioactive and other heavy minerals is mainly represented by thorite,uranothorite,zircon,monazite,xenotime,columbite,fergusonite,and unknown rare earth elements(REEs)bearing minerals as well as cassiterite.Special emphasis on REE content of thorite,uranothorite,zircon and xenotime has been done to correlate them with the increase of uranium contents in these sediments.The key evidence for the presence lowtemperature alteration processes includes the presence of some zircon crystals as remnants after complete dissolution of the overgrowth zircon in severe acidic environment,the sulphur content,biogenic minerals,occurrence of unusual minerals as cassiterite pore filling in zircon,variation in the REEs content from the surrounding granites to the stream sediments and the abundance of monazite in the surrounding granites.Most minerals are partially and/or completely altered,which indicated by the pseudomorphism of zircon by xenotime,thorite,and uranothorite.
基金financial support from the National Natural Science Foundation of China(No.51504031)the innovation fund of the General Research Institute for Nonferrous Metals(No.53319)
文摘Electrochemical measurements were conducted to study the electrochemical behavior of gold （Au） and its commonly associated minerals in alkaline thiourea solutions. The results indicated that without addition of any stabilizer, selective dissolution of Au from stibnite and pyrite was only possible at relatively low thiourea concentrations. As Na2SiO3 was added, pyrite started to become active and an oxida- tion peak appeared; the oxidation peaks of axsenopyrite and chalcocite appeared earlier thaxl that of Au. The chalcocite peak shifted in the positive direction and the peak current increased. Stibnite did not show an oxidation peak and its current was nearly zero. Adding Na2SiO3 favored the selective dissolution of Au when its minerals were associated with chalcocite and stibinte. At pH 12, the Au anode dissolution peak current increased with stabilizer concentration. At 0.38 and 0.42 V and for Na2SiO3 concentration below 0.09 M, the current density continuously increased with Na2SiO3 concentration. The Na2SiO3 concentration had to be adequate to stabilize thiourea. When the potential was higher than 0.42 V, the surface of the Au electrode started to passivate. With an additional increase in potential, the presence of Na2SiO3 could not stop the inevitable decomposition of thiourea.
文摘藓结皮是荒漠生物土壤结皮的重要类型,在荒漠生态系统碳固定与碳排放过程中具有重要作用。研究长期氮添加对藓结皮光合生理活性和土壤有机碳(SOC)组分的影响,有助于理解藓结皮光合生理活性特征与荒漠生态系统土壤碳固存之间的关系及其调控因子。为此,研究依托古尔班通古特沙漠野外长期(13a)氮添加实验,以齿肋赤藓形成的藓结皮为研究对象,选取0(N0)、1.0(N1)、3.0 g N m-2a-1(N3)三种氮处理,阐明长期氮添加对藓结皮光合生理活性和SOC组分的影响。结果表明:(1)相比对照,长期氮添加对结皮层颗粒有机碳(POC)与矿物结合态有机碳(MAOC)含量无显著影响,但显著减少了0—5 cm土层POC和MAOC含量的积累;(2)N1处理显著提高了叶绿素和非结构性碳水化合物(NSC)含量,而N3处理叶绿素a、叶绿素b、总叶绿素及NSC的含量分别显著降低了50.94%、42.49%、46.71%和50.85%;(3)可溶性糖的含量在N1处理下显著增加,N3处理则显著抑制了其积累,脯氨酸的含量随氮浓度呈显著下降的趋势,长期氮添加对可溶性蛋白含量无显著影响;(4)相关性分析表明,长期氮添加、光合生理活性与POC和MAOC含量无显著相关性,酸碱度、微生物量碳氮、电导率、硝态氮和铵态氮皆显著影响POC和MAOC的含量积累。研究揭示了长期氮添加对藓结皮的光合生理活性和SOC组分的影响,且光合生理活性的响应无法有效反映SOC组分变化,为理解荒漠生态系统中氮沉降对生物土壤结皮的影响提供数据支持。
文摘背景:观察性研究表明他汀类药物可能对骨密度具有保护作用,这使其成为潜在的骨质疏松症治疗药物之一。目的:通过孟德尔随机化方法来评估药物靶点介导的脂质表型与骨密度之间的因果关系。方法:从IEU Open GWAS数据库获取了与他汀类药物相关的单核苷酸多态性以及骨密度相关数据。主要分析方法是逆方差加权法,同时也使用了加权中位数法、简单中位数法、加权中值方法和MR-Egger回归法。使用β值和95%CI来评估他汀类药物与骨密度之间的因果关系;另外,进行敏感性分析以验证结果的可靠性,使用Cochran’s Q检验来评估异质性,使用MR-Egger截距检验是否存在水平多效性。使用留一法分析确定是否有单个或多个单核苷酸多态性影响了结果。结果与结论:他汀类药物作用靶点——3-羟基-3-甲基戊二酰辅酶A还原酶介导的低密度脂蛋白胆固醇与足跟定量超声骨密度(β=-0.086,95%CI:-0.117至-0.055,P=5.42×10^(-8))和全身骨密度(β=-0.193,95%CI:-0.288至-0.098,P=7.35×10^(-5))呈显著相关。该研究结果支持了他汀类药物对骨密度的保护作用。这些发现不仅加深了对胆固醇相关基因和骨骼健康关系的理解,还揭示了改善骨密度的潜在治疗靶点。
文摘背景:既往研究表明,中老年人体内组织蛋白酶K水平可通过影响骨密度来干预骨质疏松的发生和发展,但组织蛋白酶家族与其他人群骨密度之间是否存在因果关系仍未知。目的:探讨组织蛋白酶与骨密度的因果关系。方法:从IEU Open GWAS数据库提取与8种组织蛋白酶相关的遗传位点作为工具变量,以5个年龄段人群的骨密度作为结局。通过双向孟德尔随机化分析,评估组织蛋白酶与骨密度的因果关系。使用Cochran’s Q检验评估遗传工具变量的异质性,使用MR-Egger截距检验评估多效性,使用留一法评估作为工具变量的单核苷酸多态性对暴露和结局因果关系影响的敏感性。结果与结论:①正向孟德尔随机化的逆方差加权法结果显示,组织蛋白酶H与>45岁且≤60岁人群的骨密度呈负相关[OR(95%CI)=0.965(0.94-0.99),P=0.04],组织蛋白酶Z与>30岁且≤45岁人群的骨密度呈负相关[OR(95%CI)=1.06(1.00-1.11),P=0.03];②敏感性分析结果显示因果关系稳定,MR-Egger截距分析未检测到潜在的水平多效性;③反向孟德尔随机化结果显示,骨密度对组织蛋白酶无显著反向作用;④上述结果证实,组织蛋白酶对部分年龄段人群骨密度会造成影响,可能会增加骨质疏松症的发病风险,应给予更多关注。
文摘SANJING region (the region of three rivers, i.e. Jinsha-Lanchang-Nujiang rivers) is a very active Cenozoicinterplate deformation area on the east margin of Qinghai-Xizang Plateau, where the alkali-rich porphyrybodies occur extensively and the porphyry-related polymetallic mineral resources are produced. Manystudies on the petrology and geochemistry of the alkali-rich porphyry have been carried out and thegenerally accepted conclusion is that the petrogenesis material source has something to do with the enriched source in the mantle. The integrated interactive factors of the mineralization related to the alkalirich porphyry consist in the favourable combination of the mantle fluid metasomatism, which is derivedfrom the deep processes, and the conducting and controlling roles of the large-scale deep faults. Alongwith the changes in physical and chemical conditions caused by the diffusion of the ore-forming
基金supported by the National Key Research and Development Program of China (Grant No. 2020YFC1806401)the Application Foundation Frontier Project of Wuhan City (Grant No.2020010601012200)
文摘In this paper,the effect of low-temperature treatment on bacterial activity was investigated and its performance in preparing the consolidated sand was accessed.Four factors,including absorbance(OD600),p H,electric conductivity(EC)and urease activity(UA)were monitored to evaluate the bacterial activity.Moreover,the calcium carbonate yields under different bacterial solution and cementation solution volume ratios were determined.Finally,the compressive strength and microstructure of consolidated sand were investigated and the mechanism was explored by characterising the products among sand particles.The results showed that for both continuous and interval cultivation of bacteria,stable bacterial solution was harvested within the cultivation period of 30 h.Low-temperature treatment showed limited inhibition at early cultivation stage,while it had strong inhibition at middle cultivation stage.The interval cultivation improved the cultivation efficiency of bacteria.It was observed that the low-temperature preservation for a stable bacterial solution has little influence on UA before 4 days,while UA decreased seriously after its preservation time was extended to over 8 days.The optimal volume ratio of bacterial solution and substrate solution was 1:1,resulting in the highest calcium carbonate yield.The improved compressive strength of consolidated sand after 3 injections was attributed to the irregular-shaped calcite products,which coated and bonded the sand grains together.
文摘THE low-temperature mineralization province is a concept relative to low-temperature hydrothermal ore deposits, which refers to a special area where low-temperature hydrothermal deposits are concentrated ingroups. In Southwest China there is an area of about 90 x 10 km where there are widely developed lowtemperature hydrothermal ore deposits. This area is the so-called vast low-temperature mineralizationprovince in Southwest China. This mineralization province is so large in area, so diverse in ore type andso numerous in mineralization belt that no other one could be found in other parts of the world. In recentyears of study the following features have been obtained. (i) This mineralization province is, for the most part, located in the southwestern part of theYangtze Block and extends to the Southwest Folded Zone and part of the Sanjiang (the three-river) Foldedzone adjacent to the Yangtze Craton. (ii) The mineralization province is of double-layered structure. At the basement there are devel-
