Mineral Association and Mineralogical Criteria for the Formation Conditions of A B-F-Sn-Bi Skarn in Damoshan,Gejiu Tin Field,Southwest China

The Damoshan deposit is a small B-F-Sn Bi exoskarn deposit and contains a distinctive mineral assemblage comprising andradite,vesuvianite,calcite,diopside,magnetite,hematite,nordenskioldine,cassiterite,varlamoffite,schenfliesite,native bismuth,eulytite,bismite and bismuthite,in which the occurrence of eulytite is the first reported in China.Textures of the mineral paragenses show that andradite,vesuvianite and diopside were the earliest phases formed during metasomatism,i.e.,the skarn forming stage.Then nordenskioldine,magnetite and native bismuth,perhaps together with eulytite,were precipitated at the stage of retrograde alteration.The minerals varlamoffite,schoenfliesite,hematite ,bismite and bismuthite were probably the product of supergene alteration.The minerals were analyzed by means of electron microprobe.The data on the ,coexisting phases and their compositons show that during the metasomatism reduced F-and Sn-rich primary mineralizing solutions reacted with highly oxidized carbonated of the Gejie Formation,producing a high Fe^2+/Fe^3+ skarn(vesuvianite-fluorite skarn)near the contact of granite,and a low Fe^2+/Fe^3+ skarn(vesuvianite-fluorite skarn)near the contact of granite,and a low Fe^2+/Fe^3+ skarn(andradite skarn)in the outer zone of the skarn body in which andradite is extremely tin-bearing up to 5.14 wt% SnO2),In the retrograde alteration stage ,B-rich,but F-and Si-deficient mineralizing solutions replaced the tin-bearing andradite,forming an association of nordenskioldine and magnetite,No sulphides were deposited at this stage because of the oxidization ambient conditions in the andradite skarn.In the spergene oxidation zone,the nordenskioldine was dissolved into varlmoffite and calcite,the native bismuth was transformed into bismite or bismuthite ,and the magnetite was altered into hematite under the action of the CO2-rich supergene solutions.

Advances in Water Quality Monitoring of Inorganics: Current Trends

New methods of analysis for water quality monitoring to detect inorganic substances are required to meet the demands of determining concentration, particularly at low detection limits, analysing speciation and even identifying the pollution source. Such information is essential to inform public health decisions and to comply with more stringent legislation. This paper concentrates on two case studies, reviewing the development in monitoring methods, and predicting future trends. Arsenic and nitrates detection was selected as these pollutants are particularly problematic from a human health perspective. Additionally, the challenges faced in developing monitoring methods for these chemicals are relevant to a wide range of other inorganics. The current state of the art in detection approaches for these chemicals are discussed along with recommendations for future research to further improve the methods.

Relationship between attachment probability and surface energy in adhesion process of gold particles to oil-carbon agglomerates

Based on the theoretical analyses, the adhesion process of fine gold particles to oil-carbon agglomerates in a dynamic system was quantitatively investigated in terms of the relationship between the attachment probability and the surface energy. The proposed way to establish this relationship is to firstly theoretically derive the formula to （evaluate） the surface energy change of the system by analyzing the adhesion process of a gold particle on an oil-carbon agglomerate in a mathematic and thermodynamic way. The obtained formula of the maximum energy change of unit surface area is, (Δw′max=12σhw（cos θ-1）,) which involves two measurable elements: interfacial tension and contact angle. In a well-quantified system, based on the related model it is also possible to calculate the complicated concept, namely, the attachment probability by transferring other measurable indices. In this way, after some adhesion experiments and measurements of relevant parameters, the empirical relationship between the attachment probability and the surface energy change was established in an exponential function, Pa=Aexp(-ΔGsurf/k).

不同三维应力条件下硬岩巷道围岩的破坏特征及能量分布

为了研究开挖巷道围岩在不同三维应力条件下的破坏特征,采用TRW3000岩石真三轴电液伺服试验系统对含圆孔花岗岩试件进行三轴加载试验,并利用微型高清摄像系统实时记录圆孔附近的失效过程。结果表明,低应力条件下,圆孔内壁主要发生层裂破坏;高应力条件下,圆孔周边主要发生岩爆破坏。增加水平方向的应力可以抑制围岩发生岩爆。进一步数值模拟不同应力条件下圆孔周边的应变能密度(SED)演化过程。模拟结果表明,随着水平应力的增加,圆孔周边的SED分布逐渐减小;圆孔周边SED分布与实验记录的损伤分布基本一致,主要表现为蝶形、耳形和环形分布。

Assessment Method of Offshore Wind Resource Based on Multi-dimenssiional Indexes System

Traditional assessment indexes could not fully describe offshore wind resources,for the meteorological properties of offshore are more complex than onshore.As a result,the uncertainty of offshore wind power projects would be increased and final economic benefits would be affected.Therefore,a study on offshore wind resource assessment is carried out,including three processes of“studying data sources,conducting multidimensional indexes system and proposing an offshore wind resource assessment method based on analytic hierarchy process(AHP).First,measured wind data and two kinds of reanalysis data are used to analyze the characteristics and reliability of data sources.Second,indexes such as effective wind speed occurrence,affluent level occurrence,coefficient of variation,neutral state occurrence have been proposed to depict availability,richness,and stability of offshore wind resources,respectively.Combined with existing parameters(wind power density,dominant wind direction occurrence,water depth,distance to coast),a multidimensional indexes system has been built and on this basis,an offshore wind energy potential assessment method has been proposed.Furthermore,the proposed method is verified by the annual energy production of five offshore wind turbines and practical operating data of four offshore wind farms in China.This study also compares the ranking results of the AHP model to two multi-criteria decision making(MCDM)models including weighted aggregated sum product assessment(WASPAS)and multi-attribute ideal real comparative analysis(MAIRCA).Results show the proposed method gains well in practical engineering applications,where the economic score values have been considered based on the offshore reasonable utilization hours of the whole life cycle in China.

Fault-Induced Coal Burst Mechanism under Mining-Induced Static and Dynamic Stresses

Fault is a common geological structure that has been revealed in the process of underground coal excavation and mining.The nature of its discontinuous structure controls the deformation,damage,and mechanics of the coal or rock mass.The interaction between this discontinuous structure and mining activities is a key factor that dominates fault reactivation and the coal burst it can induce.This paper first summarizes investigations into the relationships between coal mining layouts and fault occurrences,along with relevant conceptual models for fault reactivation.Subsequently,it proposes mechanisms of fault reactivation and its induced coal burst based on the superposition of static and dynamic stresses,which include two kinds of fault reactivations from:mining-induced quasi-static stress(FRMSS)-dominated and seismic-based dynamic stress(FRSDS)-dominated.These two kinds of fault reactivations are then validated by the results of experimental investigations,numerical modeling,and in situ microseismic monitoring.On this basis,monitoring methods and prevention strategies for fault-induced coal burst are discussed and recommended.The results show that fault-induced coal burst is triggered by the superposition of high static stress in the fault pillar and dynamic stress from fault reactivation.High static stress comes from the interaction of the fault and the roof structure,and dynamic stress can be ascribed to FRMSS and FRSDS.The results in this paper could be of great significance in guiding the monitoring and prevention of fault-induced coal bursts.

矿柱劣化诱导矿区沉降规律研究

采空区塌陷易造成上跨公路受损而影响其安全运行。首先,探讨了矿柱失稳条件下顶板的变形坍塌特征。其次,采用离散元软件(3DEC),对矿柱的承载特征及失稳模式进行了数值分析。结果表明,矿柱表层剥落或弱面滑移均会造成承载能力的劣化。且在矿柱群-顶板系统中,单个或局部矿柱的失稳,均会引起其相邻矿柱应力及顶板剪切应力的增加,进而诱发地表沉降。然而,地表沉降的范围及坍塌程度可能差异较大,部分矿区表现为小范围缓慢沉降,有些矿区则会出现大规模坍塌并诱发矿震。

A novel synthesis strategy to improve cycle stability of LiNio.8Mno.1Co0.1O2 at high cut-off voltages through core-shell structuring

Nickel-rich cathode materials have attracted considerable interest because of their high specific capacities,voltage ranges,and low cost.However,serious capacity attenuation and poor rate performance limit their application.This study proposes a novel strategy to improve the cycle stability of the nickel-rich LiNi0.sCo0.1Mn0.1O2(NCM811)layer material by designing core-shell LiNio.sCoo.1 Mno.102(CS-NCM811).CS-NCM811 is designed by the characteristic reaction between dimethylglyoxime(C4H8N2O2)and nickel ion to form Ni(C4H7N2O2)2-The CS-NCM811 is characterized with high nickel content in its core and high manganese content on its surface,leading to a high capacity and excellent cycle stability.The capacity retention of CS-NCM811 was 72.8%,much higher than that of NCM811(47.1%)after 500 cycles at a rate of 5 C.Not only is this method a no vel strategy to desig n high capacity cathode materials but also provides some new in sights into the cycle stability of nickel-rich layered cathode materials.

A detailed study of metallic glass formation in copper-hafnium-titanium alloys

Recently we have reported a number of bulk glass forming compositions in the CuHf-Ti system,with the critical thickness for complete glass formation,dc,ranging from 2 mm to 4 mm.In order to improve the glass forming ability （GFA） getting even larger dc,the prevailing approach is to use complex multicomponent systems.This strategy has been investigated by us for the Cu-Hf-Ti bulk glass forming alloy Cu55Hf25Ti20 using 〉1 at.pct additions of B,Y,Nb,Ta,Al,Mn,Si or V but with no significant improvement in the GFA.Clearly,it is necessary,in order to utilise the full potential of the base ternary system,to identify the best glass-forming compositions as a basis for extending the search into multi-dimensional compositional space.Thus,CuxHfyTiz alloys,where x=（40-70） at.pct,y=（5-30） at.pct,and z=（10-36） at.pct,were prepared by melt spinning andcopper mould suction-casting.The composition dependence of the GFA for the Cu-Hf-Ti alloys,as measured by dc for rod and ribbon samples,is reported over the composition range given above.

Segregation-assisted spinodal and transient spinodal phase separation at grain boundaries

Segregation to grain boundaries affects their cohesion,corrosion,and embrittlement and plays a critical role in heterogeneous nucleation.In order to quantitatively study segregation and low-dimensional phase separation at grain boundaries,here,we apply a density-based phase-field model.The current model describes the grain-boundary thermodynamic properties based on available bulk thermodynamic data,while the grain-boundary-density profile is obtained using atomistic simulations.To benchmark the performance of the model,Mn grain-boundary segregation in the Fe–Mn system is studied.3D simulation results are compared against atom probe tomography measurements conducted for three alloy compositions.We show that a continuous increase in the alloy composition results in a discontinuous jump in the segregation isotherm.The jump corresponds to a spinodal phase separation at grain boundary.For alloy compositions above the jump,we reveal an interfacial transient spinodal phase separation.The transient spinodal phenomenon opens opportunities for knowledge-based microstructure design through the chemical manipulation of grain boundaries.The proposed density-based model provides a powerful tool to study thermodynamics and kinetics of segregation and phase changes at grain boundaries.

Martensitic twinning transformation mechanism in a metastable IVB element-based body-centered cubic high-entropy alloy with high strength and high work hardening rate

Realizing high work hardening and thus elevated strength–ductility synergy are prerequisites for the practical usage of body-centered-cubic high entropy alloys(BCC-HEAs).In this study,we report a novel dynamic strengthening mechanism,martensitic twinning transformation mechanism in a metastable refractory element-based BCC-HEA(TiZrHf)Ta(at.%)that can profoundly enhance the work hardening capability,leading to a large uniform ductility and high strength simultaneously.Different from conventional transformation induced plasticity(TRIP)and twinning induced plasticity(TWIP)strengthening mechanisms,the martensitic twinning transformation strengthening mechanism combines the best characteristics of both TRIP and TWIP strengthening mechanisms,which greatly alleviates the strengthductility trade-off that ubiquitously observed in BCC structural alloys.Microstructure characterization,carried out using X-ray diffraction(XRD)and electron back-scatter diffraction(EBSD)shows that,upon straining,α”(orthorhombic)martensite transformation,self-accommodation(SA)α”twinning and mechanicalα”twinning were activated sequentially.Transmission electron microscopy(TEM)analyses reveal that continuous twinning activation is inherited from nucleating mechanical{351}type I twins within SA“{351}”<■11>typeⅡtwinnedα”variants on{351}twinning plane by twinning transformation through simple shear,thereby accommodating the excessive plastic strain through the twinning shear while concurrently refining the grain structure.Consequently,consistent high work hardening rates of 2–12.5 GPa were achieved during the entire plastic deformation,leading to a high tensile strength of 1.3 GPa and uniform elongation of 24%.Alloy development guidelines for activating such martensitic twinning transformation strengthening mechanism were proposed,which could be important in developing new BCC-HEAs with optimal mechanical performance.

PRECAMBRIAN SPHEROIDAL UNICELLS SHOWING PSEUDO-ORGANELLES

The first appearance of eukaryotic cells is the most significant event in the early evolution of life, for all subsequent developments follow from it. The search in Precambrian rocks for fossil evidence of eukaryotic cells has been one of the most important and active topics of research in Precambrian micropalaeontology.

On strong-scaling and open-source tools for analyzing atom probe tomography data

The development of strong-scaling computational tools for high-throughput methods with an open-source code and transparent metadata standards has successfully transformed many computational materials science communities.While such tools are mature already in the condensed-matter physics community,the situation is still very different for many experimentalists.Atom probe tomography(APT)is one example.This microscopy and microanalysis technique has matured into a versatile nano-analytical characterization tool with applications that range from materials science to geology and possibly beyond.Here,data science tools are required for extracting chemo-structural spatial correlations from the reconstructed point cloud.For APT and other high-end analysis techniques,post-processing is mostly executed with proprietary software tools,which are opaque in their execution and have often limited performance.Software development by members of the scientific community has improved the situation but compared to the sophistication in the field of computational materials science several gaps remain.This is particularly the case for open-source tools that support scientific computing hardware,tools which enable high-throughput workflows,and open welldocumented metadata standards to align experimental research better with the fair data stewardship principles.To this end,we introduce paraprobe,an open-source tool for scientific computing and high-throughput studying of point cloud data,here exemplified with APT.We show how to quantify uncertainties while applying several computational geometry,spatial statistics,and clustering tasks for post-processing APT datasets as large as two billion ions.These tools work well in concert with Python and HDF5 to enable several orders of magnitude performance gain,automation,and reproducibility.