Metallurgical performance evaluation of space-weathered Chang’e-5 lunar soil

Space metallurgy is an interdisciplinary field that combines planetary space science and metallurgical engineering.It involves systematic and theoretical engineering technology for utilizing planetary resources in situ.However,space metallurgy on the Moon is challenging because the lunar surface has experienced space weathering due to the lack of atmosphere and magnetic field,making the mi-crostructure of lunar soil differ from that of minerals on the Earth.In this study,scanning electron microscopy and transmission electron microscopy analyses were performed on Chang’e-5 powder lunar soil samples.The microstructural characteristics of the lunar soil may drastically change its metallurgical performance.The main special structure of lunar soil minerals include the nanophase iron formed by the impact of micrometeorites,the amorphous layer caused by solar wind injection,and radiation tracks modified by high-energy particle rays inside mineral crystals.The nanophase iron presents a wide distribution,which may have a great impact on the electromagnetic prop-erties of lunar soil.Hydrogen ions injected by solar wind may promote the hydrogen reduction process.The widely distributed amorph-ous layer and impact glass can promote the melting and diffusion process of lunar soil.Therefore,although high-energy events on the lun-ar surface transform the lunar soil,they also increase the chemical activity of the lunar soil.This is a property that earth samples and tradi-tional simulated lunar soil lack.The application of space metallurgy requires comprehensive consideration of the unique physical and chemical properties of lunar soil.

Insights into Nano-and Micro-Structured Scaffolds for Advanced Electrochemical Energy Storage

Adopting a nano-and micro-structuring approach to fully unleashing the genuine potential of electrode active material benefits in-depth understandings and research progress toward higher energy density electrochemical energy stor-age devices at all technology readiness levels.Due to various challenging issues,especially limited stability,nano-and micro-structured(NMS)electrodes undergo fast electrochemical performance degradation.The emerging NMS scaffold design is a pivotal aspect of many electrodes as it endows them with both robustness and electrochemical performance enhancement,even though it only occupies comple-mentary and facilitating components for the main mechanism.However,extensive efforts are urgently needed toward optimizing the stereoscopic geometrical design of NMS scaffolds to minimize the volume ratio and maximize their functionality to fulfill the ever-increasing dependency and desire for energy power source supplies.This review will aim at highlighting these NMS scaffold design strategies,summariz-ing their corresponding strengths and challenges,and thereby outlining the potential solutions to resolve these challenges,design principles,and key perspectives for future research in this field.Therefore,this review will be one of the earliest reviews from this viewpoint.

Numerical simulation of granular silicon growth and silicon fines formation process in polysilicon fluidized bed

Operating conditions strongly affect the yield and quality of polysilicon in a polysilicon fluidized bed.In this study,a new model of polysilicon fluidized bed was established using the Euler-Euler model coupled with population balance model(PBM),which was combined with fluid flow,heat,and mass transfer models,while considering the scavenging effect of silicon fines.The effects of different operating conditions on the deposition and formation rates of silicon fines were investigated.Results show that the model can correctly describe the particle growth process in the fluidized bed of polysilicon.The silicon fines and the interphase velocity difference show"N"-and"M"-shaped distributions along the axial direction,respectively.The particle temperature and concentration near the wall are higher than those in the central region.The decomposition of silane in the bottom region of the bed is dominated by het-erogeneous deposition.The scavenging of silicon fines occurs in the dilute-phase region.The effects of operating conditions,i.e.inlet gas temperature,silane composition,and gas velocity,on the reactor performance were also explored comprehensively.Increasing the inlet gas composition and velocity enhances the formation rates of solid silicon and fines.Increasing the inlet gas temperature promotes the growth of solid silicon and inhibits the formation of silicon fines.High fluidization ratio,low inlet silane concentration,and high inlet gas temperature enhance the selectivity of silicon growth.

LiBH4 for hydrogen storage-New perspectives

Hydrogen energy has been recognized as“Ultimate Power Source”in the 21st century.It is a boon in these days of energy crunches and concerns about climate change because of the characterized advantages,such as high energy density,large calorific value,abundant resource,zero pollution,zero carbon emission,storable and renewable.State-of-the-art perspectives on tuning the stable thermodynamics and sluggish kinetics of dehydrogenation and re-hydrogenation of LiBH4,which has been regarded as a promising hydrogen storage alternative for onboard energy carrier applications have been discussed.Five major technological approaches are involved,including nanoengineering,catalyst modification,ions substitution,reactant destabilization and a novel process termed as high-energy ball milling with in-situ aerosol spraying(BMAS).It is worth noting that BMAS has the potential to help overcome the kinetic barriers for thermodynamically favorable systems like LiBH4 t MgH2 mixture and provide thermodynamic driving force to enhance hydrogen release at a lower temperature.

Nanocellulose/nitrogen and fluorine co-doped graphene composite hydrogels for high-performance supercapacitors

Three-dimensional graphene materials have been studied as typical supercapacitors electrode materials by virtue of their ultrahigh specific surface area and good ion transport capacity.However,improvement of the poor volumetric electrochemical performance of these graphene materials has been required although they have high gravimetric energy density.In this work,nanocellulose/nitrogen and fluorine co-doped graphene composite hydrogels(NC-NFGHs)were prepared through a convenient hydrothermal approach utilizing ammonium fluoride as the heteroatom source.Nanocellulose(NC)and high concentration of graphene oxide(GO)were utilized to adjust the structure of NC-NFGHs and increase their packing density.Subsequently,the aqueous symmetric supercapacitor based on NC-NFGH-80 exhibits remarkable gravimetric(286.6 F·g^(-1))and volumetric(421.3 F·cm^(-3))specific capacitance at 0.3 A·g^(-1),good rate performance,and remarkable cycle stability up to 10,000 cycles.Besides,the all-solid-state flexible symmetric supercapacitors(ASSC)fabricated by NC-NFGH-80 also delivered a large specific capacitance of 117.1 F·g^(-1)at 0.3 A·g^(-1)and long service life over 10,000 cycles at 10 A·g^(-1).This compact porous structure and heteroatom co-doped graphene material supply a favorable strategy for high-performance supercapacitors.

A novel strategy to extract lunar mare KREEP-rich metal resources using a silicon collector

The lunar mare potassium(K)-,rare-earth elements(REEs)-and phosphorous(P)-rich(KREEP-rich) region is a unique late-stage product of magma crystallization,in which ilmenite and incompatible elements have high grades,thus forming a giant natural reservoir.The extraction and purification of the high-value metal resources in the KREEP-rich region not only meet the construction needs of the lunar base but also solve the problem of resource scarcity on Earth.In this study,photovoltaic elemental silicon(Si) was used as a collector to extract ilmenite resources,REEs,and nuclear energy elements from basalt in the lunar mare KREEP-rich region at 1873 K.Based on experimentation,the metals titanium(Ti)and iron(Fe) in the lunar mare ilmenite are found to be enriched and solidified in the form of Si-based alloys.The contents of valuable incompatible elements in the KREEP-rich area are also found to be enriched and contained in the incompatible trace elements(ITEs) phase of the alloy.Among them,REEs(e.g.,cerium(Ce) and thulium(Tm)) and nuclear elements(e.g.,thorium(Th) and uranium(U)) are found to account for 82.61 wt% of the ITEs phase.This process provides a simple and feasible scheme for the insitu resource utilization(ISRU) of the lunar surface and is suitable for the extraction and enrichment of lunar metal resources.

Optimal design of gas distributor in fluidized bed for synthesis of silicone monomer

The structure of the gas distributor is closely related to the production efficiency of organosilicon monomers.To improve the production efficiency of organosilicon monomers,this study uses Eulerian-Eulerian two fluid model and proposes a design formula for the gas distributor to optimize the gas distributor.It is proposed that the pressure drop of the gas distributor,the velocity nonuniformity coefficient,the relative standard deviation of the solid holdup,and the solid particle dispersion coefficient are used to evaluate the performance of the gas distributor.The results show that the performance of the gas distributor is significantly improved when the opening ratioΦ=0.53%is optimized toΦ=0.18%,in which the relative standard deviation of the solid holdup is reduced by 22%,and the solid particle dispersion coefficient is reduced by 40%.On this basis,this article studies the influence of different arrangements of vent holes on gas-solid fluidization characteristics.The results show that the circular arrangement of vent holes is helpful to the mixing of gas and solid.

Recent progress in upgrading metallurgical-grade silicon to solar-grade silicon via pyrometallurgical routes

Si-based photovoltaic solar power has been rapidly developed as a renewable and green energy source.The widespread use of Sibased solar cells requires large amounts of solar-grade Si(SoG-Si)to manufacture Si wafers.Chemical routes,mainly the modified Siemens process,have dominated the preparation of polycrystalline SoG-Si;however,traditional chemical techniques employ a series of complex chemical reactions involving various corrosive and hazardous reagents.In addition,large amounts of complex waste solar cells and Si kerf slurry waste gradually accumulate and are difficult to recycle using these approaches.New methods are required to meet the demand for SoGSi preparation and Si waste recycling.The metallurgical route shows promise but is hindered by the problem of eliminating B and P from metallurgical-grade Si(MG-Si).Various pyrometallurgical treatments have been proposed to enhance the removal of B and P from MG-Si.This article reviews Si refining with slag treatment,chlorination,vacuum evaporation,and solvent refining,and summarizes and discusses the basic principles and recent representative studies of the four methods.Among these,solvent refining is the most promising and environmentally friendly approach for obtaining low-cost SoG-Si and is a popular research topic.Finally,a simple and green approach,i.e.,a combination of solvent refining,slag treatment,or vacuum directional solidification,is proposed for low-cost SoG-Si preparation using MG-Si or Si wastes as raw materials.

Numerical simulation of carbon arc discharge for graphene synthesis without catalyst

In this study, graphene sheets are prepared under a hydrogen atmosphere without a catalyst, and the growth mechanism of graphene by direct current arc discharge is investigated experimentally and numerically. The size and layer numbers of graphene sheets increase with the arc current.Distributions of temperature, velocity, and mass fraction of carbon are obtained through numerical simulations. A high current corresponds to a high saturation temperature, evaporation rate, and mass density of carbon clusters. When the carbon vapor is saturated, the saturation temperatures are 3274.9, 3313.9, and 3363.6 K, and the mass densities are 6.4×1022,8.42×1022, and 1.23×1023 m-3 under currents of 150, 200, and 250 A, respectively. A hydrogen-induced marginal growth model is used to explain the growth mechanism. Under a high current, the condensation coefficient and van der Waals force increase owing to the higher saturation temperature and mass density of carbon clusters, which is consistent with experimental results.

The complete mitochondrial genome of the hybrid grouper Epinephelus moara(♀)×Epinephelus tukula(♂), and phylogenetic analysis in subfamily Epinephelinae

The mitochondrial genome(mitogenome)of hybrid grouper Epinephelus moara(♀)×Epinephelus tukula(♂),a new hybrid progeny,can provide valuable information for analyzing phylogeny and molecular evolution.In this study,the mitogenome was analyzed using PCR amplification and sequenced,then the phylogenetic relationship of E.moara(♀)×E.tukula(♂)and 35 other species were constructed using Maximum Likelihood and NeighborJoining methods with the nucleotide sequences of 13 conserved protein-coding genes(PCGs).The complete mitogenome of E.moara(♀)×E.tukula(♂)was 16695 bp in length,which contained 13 PCGs,2 rRNA genes,22 tRNA genes,a replication origin and a control region.The composition and order of these genes were consistent with most other vertebrates.Of the 13 PCGs,12 PCGs were encoded on the heavy strand,and ND6 was encoded on the light strand.The mitogenome of the E.moara(♀)×E.tukula(♂)had a higher AT nucleotide content,a positive AT-skew and a negative GC-skew.All protein initiation codons were ATG,except for COX and ND4(GTG),ATP6(CTG),and ND3(ATA).ND2,COXII,ND3,ND4 and Cytb had T as the terminating codon,COXIII’s termination codon was TA,and the remaining PCGs of that were TAA.All tRNA genes,except for the lacking DHU-arm of tRNASer(AGN),were predicted to form a typical cloverleaf secondary structure.In addition,sequence similarity analysis(99%identity)and phylogenetic analysis(100%bootstrap value)indicated that the mitochondrial genome was maternally inherited.This study provides mitogenome data for studying genetic,phylogenetic relationships and breeding of grouper.

Breeding of New Processing Apricot Cultivar ‘Jinxiu'

‘Jinxiu' is a processing apricot(Armeniaca vulgaris L.) cultivar derived from the cross of ‘Chuanzhihong'בJintaiyang'.The fruit is oval-shaped with the ground color of orange and 1/4-1/2 sheet red in the surface. The average fruit weight is65.5 g, and the maximum value is 106 g. The flesh is orange, fine with very less fiber, toughness, less juice and freestone, and tastes sour and sweet. The soluble solid content is 12.5%. The edible rate is 95.8%. The fruit skin hardness is 12.9 kg/cm2 and storable. The preserved apricots have orange color and are tasty. The preserved yield is 40%. The fruit development period is 72 d. The fruit has high yield, and the fruit yield in full fruit period can reach 37 000 kg/hm2. ‘Jinxiu' was examined and approved by Hebei Examination and Approval Committee of Forest Tree Variety in 2013.

Synthesis of Cu/Ni-La_(0.7)Sr_(0.3)Cr_(0.5)Mn_(0.5)O_(3-δ) and its catalytic performance on dry methane reforming

In this study,Cu/Ni-La_(0.7)Sr_(0.3)Cr_(0.5)Mn_(0.5)O_(3-δ)(LSCM) catalysts were synthesized via the citric acid-nitrate process(CNP) and chemical co-precipitation. The catalytic performance of Cu/Ni-LSCM catalysts on dry methane reforming was evaluated in a fixed-bed reactor at 550/650 ℃ and atmosphere pressure. Cu/Ni loading was investigated as an influencing factor, which led to 5 cases of samples according to the different Cu/Ni mass ratios. The catalysts were characterized by X-ray diffraction(XRD), field emissionscanning electron microscope(FE-SEM), Brunauer-Emmett-Teller(BET) measurement, X-ray photoelectron spectroscopy(XPS), hydrogen-based temperature-programmed reduction(H_2-TPR) and thermos gravimetric analyzer(TGA). The results show that the methane conversion increases, the resistance against metal sintering increases and the carbon deposition drops after the copper is introduced. This optimum performance can be obtained under Case 3(Cu:Ni:LSCM = 1:3:6 in mass ratio).

A novel approach to synthesize porous graphene by the transformation and deoxidation of oxygen-containing functional groups

In this study,impurity-free porous graphene(PG) with intrinsic pore structure was synthesized through a facile acid-alkali etching-assisted sonication approach.The pore structure appears on the surface of graphene sheets due to intrinsic defects of graphene.The PG possessed an extremely high specific surface area of 2184 m^2/g,the size of^5 μm and layer numbers of 3-8.Additionally,PG contained micropores and mesopores simultaneously,with an average pore diameter of approximately 3 nm.The effects of acid,alkali,and ultrasound treatment on PG preparation were elucidated by transmission electron microscopy and fourier transform infrared spectroscopy.First,in an acidic solution,oxygen-containing functional groups(hydroxyls,carboxyl,and epoxides) were formed due to the hydrolysis of sulfate and continuous transformations of these functional groups on graphene oxide.Second,under the synergistic effects of alkali and ultrasound treatment,PG was obtained due to the loss of carboxyl and epoxide groups.A new route for preparing PG was provided by the proposed method.

晶硅切割废硅粉熔渣精炼制备低磷再生硅

晶硅切割废硅粉是重要的新能源固废,切片过程电镀金刚线上磷的污染导致普通熔炼得到的再生硅磷含量高、品质差,无法满足有机硅行业对高品质原料的需求。本工作采用熔渣精炼一步去除晶硅切割废料的表面氧化层和非金属杂质磷元素,成功制备了有机用硅。首先使用石英砂模拟了硅粉表面氧化层的高温熔解行为,对比了CaO-Al_(2)O_(3)-SiO_(2)和CaO-SiO_(2)-CaF_(2)两种渣系对二氧化硅的熔解效果,并考察了精炼时间(2~6 min)、精炼温度(1400,1450和1500℃)下二氧化硅的熔解率。然后以晶硅切割废硅粉为原料,对比了两种精炼渣系对废硅粉的除磷效果,对氧化层和除磷结果进行了机理解析。结果表明,二氧化硅的熔解主要受精炼渣系的黏度影响,降低精炼渣的黏度能加快二氧化硅的熔解速率。相同条件下,二氧化硅在CaO-SiO_(2)-CaF_(2)渣系的熔解速率更快。精炼实验表明,提高CaO-Al_(2)O_(3)-SiO_(2)和CaO-SiO_(2)-CaF_(2)精炼渣系的碱度有利于废硅粉中磷的去除,两种精炼渣的最大磷去除率分别为53.81%和62.04%。

Improving open-circuit voltage and short-circuit current of high-efficiency silicon-based planar heterojunction solar cells by combining V_(2)O_(5)with PEDOT:PSS

In recent years,a novel PEDOT:PSS/n-Si planar heterojunction solar cell has been extensively studied in the photovoltaic field.Different V_(2)O_(5)-IPA concentrations mixed in PEDOT:PSS samples as hole transport layer were prepared by means of spin coating technique and mechanical mixing of organic and inorganic materials.V_(2)O_(5)was studied for its effects on the surface morphology,chemical composition,and optical transmittance of PEDOT:PSS films.The findings of the study show that the addition of V_(2)O_(5)particles changes the surface morphology of PEDOT:PSS films and promotes its superior ohmic contact with the Si interface.Furthermore,PEDOT:PSS incorporated with V_(2)O_(5)particles that have outstanding optical and semiconductor properties reduces the rate of carrier recombination at the device interface and blocks electron transport to the anode in the fabricated Si-based solar cells.When compared to conventional PEDOT:PSS/Si planar heterojunction solar cells,the fill factor,photoelectric conversion efficiency,open-circuit voltage,and short-circuit current density of the devices prepared in this study can be significantly improved,reaching up to 70.98%,15.17%,652 mV and 32.8 mA/cm^(2),respectively.This research provides a promising and effective method for improving the photoelectric conversion performance of PEDOT:PSS/Si heterojunction solar cells,which enables the application of V_(2)O_(5)in Si solar cells.

色噪声驱动的非自治非经典扩散方程的拉回随机吸引子

本文研究无界区域上带色噪声的非自治非经典扩散方程解的渐近性.为了克服Sobolev嵌入在无界区域上的非紧性,利用Ball能量方程的思想,本文证明与问题相关的多值随机动力系统在H^(1)(R^(n))中拉回随机吸引子的存在性.

钠基固体电解质及其在能源上的应用

由于以钠基固体电解质为核心的新型钠电池体系具有低成本和高安全性,在能源领域应用潜力巨大。高离子电导率和稳定性是钠基固体电解质应用于新型钠电池体系的前提。近年来,人们通过对制备方法改进和掺杂改性等方面的研究显著提高了钠基固体电解质的离子电导率和稳定性。此外,新型钠电池体系亟需解决固体电解质与电极间的界面接触性差和界面稳定性差等问题。本文首先总结了β″-Al_2O_3、NASICON型、硫化物类和聚合物类钠基固体电解质的研究进展,然后介绍了钠基固体电解质在以钠-硫电池,有机/水混合系钠-空气电池和全固态钠离子电池为代表的新型钠电池体系中的应用情况,并对界面问题和采取的解决策略进行系统论述。基于固体电解质的新型钠电池体系在能源上的大规模应用还需要电池材料、界面和电池设计等多方面的研究同时突破。

电磁分离高硅铝硅合金制备低硅铝硅合金

在不考虑杂质元素的情况下研究了含铝45wt%的铝硅合金熔体电磁分离过程中电流频率、下拉速度、保温温度及坩埚材质对初晶硅相分离效果的影响.结果表明,在电流频率3 kHz、保温温度1000℃、下拉速度10mm/s的条件下,以石墨坩埚为容器,可使合金的硅铝质量比降至0.0939.保温温度对合金中硅的去除影响最大,相同条件下1500℃时合金硅铝质量比为0.11439;低频交变电流能强化电磁搅拌从而加强传质,降低下拉速度对降低合金中硅含量有一定作用,且可使分离界面更平坦.

冶金法生产太阳能级硅的除硼方法、技术及工艺

太阳能作为一种绿色可再生能源受到了广泛关注,而杂质去除是从冶金级硅中获得太阳能级硅所需的纯化过程,对硅基太阳能电池的制备至关重要。冶金法制备太阳能级多晶硅新工艺技术由于其能耗低、成本低和污染少等优点,成为研究开发的热点,但如何有效地去除硼是我们面临的最严峻的挑战之一。本文综述了硼的热力学和动力学性质(溶解度、扩散率、扩散系数、传质系数和活度系数)以及近年来除硼的相关课题研究(吹气、炉渣处理、等离子体处理、酸浸和溶剂精炼)。研究发现,溶剂精炼是一种很有前途的获取高纯硅的方法,硅的富集率以及硼的去除率均可达到90%以上,而添加剂能够加强硼化物的形成和析出来改进除硼工艺,且后续几乎可被完全消除,不会对精炼硅造成污染,这将更加有效除硼并增加工艺实用性。最后本文对几种除硼工艺进行了比较分析,并对冶金法的应用前景进行了展望。

离心场强化晶硅切割废料Si/SiC分离过程油水分相

对切割料中Si和Si C的高效分离进行了研究,利用晶硅切割废料中Si和Si C表面性质的差异,向浆料中加入柴油并充分乳化,使SiC吸附在油滴上实现Si/SiC分离,对乳化后的浆料施加离心力强化油水分相,调节浆料pH值改变颗粒表面Zeta电位,调控乳化后的油滴大小,研究了Si/Si C分离效果、分相时间与浆料pH的关系及附有Si C的油滴表观密度与油滴直径的关系,对乳化后的浆料分别施加超重力系数为10, 50, 100, 150和200的离心力,考察了离心时间2 min时的分相效果和Si/SiC分离效果。结果表明,常重力场中,油滴尺寸越小,分相时间越长,但Si C去除效果变好,pH=7时,水相Si C含量为4.23wt%。油滴直径小于64?m时,油滴在浆料中不可上浮。离心场中,超重力系数为100, p H=7时,水相中Si C含量为5.47wt%,分相时间由460 min缩短为2 min。通过对离心场中Si C的受力分析解析了离心场中Si C在油滴表面的赋存状态,证实离心场作用下,Si C沿油滴表面向离心力方向移动使油滴对Si C的吸附力减小。