The Relationship of Sulfate-methane Interface,the Methane Flux and the Underlying Gas Hydrate

The sulfate-methane interface is an important biogeochemical identification interface for the areas with high methane flux and containing gas hydrate. Above the sulfate-methane interface, the sulfate concentration in the sediment is consumed progressively for the decomposition of the organic matter and anaerobic methane oxidation. Below the sulfate-methane interface, the methane concentration increases continuously with the depth. Based on the variation characters of the sulfate and methane concentration around the sulfate-methane interface, it is feasible to estimate the intensity of the methane flux, and thereafter to infer the possible occurrence of gas hydrate. The geochemical data of the pore water taken from the northern slope of the South China Sea show the sulfate-methane interface is relatively shallow, which indicates that this area has the high methane flux. It is considered that the high methane flux is most probably caused by the occurrence of underlying gas hydrate in the northern slope of the South China Sea.

High density gas state at water/graphite interface studied by molecular dynamics simulation

In this paper molecular dynamics simulations are performed to study the accumulation behaviour of N2 and H2 at water/graphite interface under ambient temperature and pressure. It finds that both N2 and H2 molecules can accumulate at the interface and form one of two states according to the ratio of gas molecules number to square of graphite surface from our simulation results： gas films （pancake-like） for a larger ratio and nanobubbles for a smaller ratio. In addition, we discuss the stabilities of nanobubbles at different environment temperatures. Surprisingly, it is found that the density of both kinds of gas states can be greatly increased, even comparable with that of the liquid N2 and liquid H2. The present results are expected to be helpful for the understanding of the stable existence of gas film （pancake-like） and nanobubbles.

A Study on Solid/Melt Interfaces and the Formation of<100> Texture in Solidified FCC Metals

The (100) texture of solidified fcc metals, caused by the preferential (100) dendrite growth, could be closeIy related to solid/melt interfaces which behave differently along different crystallographic orientation. The stability and roughness of {111} and {100} solid/melt interfaces of fcc metals were investigated using a modified Temkin multi-layer model. It is demonstrated that {100}crystal/melt interface is more unstable and rougher than {111} interface. The effect of the stability of crystal/melt interface on the (100) texture formation in solidified fcc metals has been analysed and discussed.

Growth and aggregation micromorphology of natural gas hydrate particles near gas-liquid interface under stirring condition

To investigate the morphological evolution of the whole growth and aggregation processes of hydrate crystals near the gas–liquid interface,we used a high-pressure visual reactor with high-speed camera to capture the micromorphology of hydrate particles in a natural gas+pure water system with pressure from 2.6 to 3.6 MPa and sub-cooling from 4.7 to 6.23C.The results showed that under low sub-cooling conditions,the amount and size of particles increased first and then decreased in the range of 0–330 lm,and the small particles always dominated.These particles can be roughly classified into two categories:planar flake particles and polyhedral solid particles.Then,the concept of maximum growth dominant particle size was proposed to distinguish the morphological boundary of growth and aggregation.In addition,the micro model was established to better reflect the effects of particle formation process and evolution mechanism near the gas–liquid interface under stirring condition.The results of this study can provide a guidance for flow assurance in multiphase pipeline.

Understanding fundamentals of electrochemical reactions with tender X-rays:A new lab-based operando X-ray photoelectron spectroscopy method for probing liquid/solid and gas/solid interfaces across a variety of electrochemical systems

Electrocatalysis is key to improving energy efficiency,reducing carbon emissions,and providing a sustainable way of meeting global energy needs.Therefore,elucidating electrochemical reaction mechanisms at the electrolyte/electrode interfaces is essential for developing advanced renewable energy technologies.However,the direct probing of real-time interfacial changes,i.e.,the surface intermediates,chemical environment,and electronic structure,under operating conditions is challenging and necessitates the use of in situ methods.Herein,we present a new lab-based instrument commissioned to perform in situ chemical analysis at liquid/solid interfaces using ambient pressure X-ray photoelectron spectroscopy(APXPS).This setup takes advantage of a chromium source of tender X-rays and is designed to study liquid/solid interfaces by the“dip and pull”method.Each of the main components was carefully described,and the results of performance tests are presented.Using a three-electrode setup,the system can probe the intermediate species and potential shifts across the liquid electrolyte/solid electrode interface.In addition,we demonstrate how this system allows the study of interfacial changes at gas/solid interfaces using a case study:a sodium–oxygen model battery.However,the use of APXPS in electrochemical studies is still in the early stages,so we summarize the current challenges and some developmental frontiers.Despite the challenges,we expect that joint efforts to improve instruments and the electrochemical setup will enable us to obtain a better understanding of the composition–reactivity relationship at electrochemical interfaces under realistic reaction conditions.

High-mobility two-dimensional electron gases at oxide interfaces:Origin and opportunities

Our recent experimental work on metallic and insulating interfaces controlled by interfacial redox reactions in SrTiO3-based heterostructures is reviewed along with a more general background of two-dimensional electron gas （2DEG） at oxide interfaces. Due to the presence of oxygen vacancies at the SrTiO3 surface, metallic conduction can be created at room temperature in perovskite-type interfaces when the overlayer oxide ABO3 has Al, Ti, Zr, or Hf elements at the B sites. Furthermore, relying on interface-stabilized oxygen vacancies, we have created a new type of 2DEG at the heterointerface between SrTiO3 and a spinel γ-Al2O3 epitaxial film with compatible oxygen ion sublattices. This 2DEG exhibits an electron mobility exceeding 100000 cm2·V-1·s-1, more than one order of magnitude higher than those of hitherto investigated perovskite-type interfaces. Our findings pave the way for the design of high-mobility all-oxide electronic devices and open a route toward the studies of mesoscopic physics with complex oxides.

In-plane anisotropy in two-dimensional electron gas at LaAlO_3/SrTiO_3(110) interface

A systematic study of the two-dimensional electron gas at La AlO_3/SrTiO_3（110） interface reveals an anisotropy along two specific directions, [001] and 1ī0. The anisotropy becomes distinct for the interface prepared under high oxygen pressure with low carrier density. Angular dependence of magnetoresistance shows that the electron confinement is stronger along the 1ī0 direction. Gate-tunable magnetoresistance reveals a clear in-plane anisotropy of the spin–orbit coupling,and the spin relaxation mechanism along both directions belongs to D＇yakonov–Perel＇（DP） scenario. Moreover, in-plane anisotropic superconductivity is observed for the sample with high carrier density, the superconducting transition temperature is lower but the upper critical field is higher along the 1ī0 direction. This in-plane anisotropy could be ascribed to the anisotropic band structure along the two crystallographic directions.

Mechanism of boron removal from Si-Al melt by Ar-H_2 gas mixtures

A new method about purification of metallurgical grade silicon （MG-Si） by a combination of Si-Al solvent refining andgas blowing treatment was proposed. The morphologies and transformation of impurity phases, especially for boron and iron in Si-Al melt were investigated during Ar-H2 gas blowing treatment. The mechanism of boron removal was discussed. The resultsindicate that gas blowing can refine grain size and increase nucleation of the primary Si. Boron can be effectively removed fromMG-Si using the Ar-H2 gas blowing technique during the Si-Al solvent refining. Compared with the sample without gas blowing,the removal efficiency of boron increases from 45.83% to 74.73% after 2.5 h gas blowing. The main impurity phases containingboron are in the form of TiB2, AlB2 and VB compounds and iron-containing one is in the form of β-Al5FeSi intermetallic compound.Part of boron combines [H] to transform into gas BxHy （BH, BH2） and diffuses towards the surface of the melt and is volatilized byAr-H2 gas blowing treatment under electromagnetic stirring.

Effect of indium addition on the microstructural formation and soldered interfaces of Sn-2.5Bi-1Zn-0.3Ag lead-free solder

The microstructural formation and properties of Sn-2.5Bi-xln-lZn-0.3Ag （in wt%） alloys and the evolution of soldered interfaces on a Cu substrate were investigated. Apart from the relatively low melting point （about 195C）, which is close to that of conventional eutectic Sn-Pb solder, the investigated solder presents superior wettability, solderability, and ductility. The refined equiaxial grains enhance the me- chanical properties, and the embedded bulk intermetallic compounds （IMCs） （Cu6Sn5 and CusZns） and granular Bi particles improve the joint reliability. The addition of In reduces the solubility of Zn in the 13-Sn matrix and strongly influences the separation and growth behaviors of the IMCs. The soldered interface of Sn-2.5Bi-xln-lZn-0.3Ag/Cu consists of Cu-Zn and Cu-Sn IMC layers.

Numerical investigation on flow process of liquid metals in melt delivery nozzle during gas atomization process for fine metal powder production

Based on volume of fluid(VoF)interface capturing method and shear-stress transport(SST)k-ω turbulence model,numerical simulation was performed to reveal the flow mechanism of metal melts in melt delivery nozzle(MDN)during gas atomization(GA)process.The experimental validation indicated that the numerical models could give a reasonable prediction on the melt flow process in the MDN.With the decrease of the MDN inner-diameter,the melt flow resistance increased for both molten aluminum and iron,especially achieving an order of 10^(2) kPa in the case of the MDN inner-diameter≤1 mm.Based on the conventional GA process,the positive pressure was imposed on the viscous aluminum alloy melt to overcome its flow resistance in the MDN,thus producing powders under different MDN inner-diameters.When the MDN inner-diameter was reduced from 4 to 2 mm,the yield of fine powder(<150μm)soared from 54.7%to 94.2%.The surface quality of powders has also been improved when using a smaller inner-diameter MDN.

MASS TRANSFER TO LIQUID-LIQUID INTERFACE

Experiments have been done on mass transfer to a liquid-liquid interface on which inert gas bubbles are sparged.To simulate the pyrometallurgy system of melten slag-metal(or matte),aqueous solution-mercury(or zinc amalgam) system was used.The mass transfer coefficients of indicator ions as a function of bubble parameters have been determined.The experimental results show satisfactory agreement with the mass transfer model proposed Previously.

Research progress on solder thermal interface materials

Down to the road of miniaturization and high power density,the heat dissipation is becoming one of the critical factors restricting further development of advanced microelectronic devices.Traditional polymer-based thermal interface materials(TIMs) are not competitive for the high efficiency thermal management,mainly due to their low intrinsic thermal conductivity and high interface thermal resistance.Solder-based TIM is one of the best candidates for the next generation of thermal interface materials.This paper conducts a perspective review of the state of the art of solder TIM,including low melting alloy solder TIM,composite solder TIM and nanostructured solder TIM.The microstructure,process parameters,thermal performance and reliability of different TIMs are summarized and analyzed.The future trends of advanced TIMs are discussed.

Spatio-temporal evolution characteristics and pattern formation of a gas–liquid interfacial AC current argon discharge plasma with a deionized water electrode

A discharge ignited by an AC power source in contact with deionized water as one of the electrodes is investigated.Immediately after initiation,the discharge exhibits a unique phenomenon:the gas-phase discharge is extended into the liquid.Later,a cone-like structure is observed at the liquid surface.Synchronous monitoring of current–voltage characteristics and liquid properties versus time suggests that the discharge shapes are functions of the liquid properties.The spatio-temporal profiles indicate the potential effects of water,ambient air impurities,and metastable argon on the discharge chemistry.This becomes more obvious near the liquid surface due to increasing production of various transient reactive species such as centerdot OH and NO centerdot.Moreover,it is revealed that thermalization of the rotational population distributions of the rotational states(N′⩽6,J′⩽13/2)in the Q1 branch of the OH(A2Σ+,υ′=0→X2Π3/2,υ′′=0)band ro-vibrational system is influenced by the humid environment near the liquid surface.In addition,the transient behaviors of instantaneous concentrations of long-lived reactive species(LRS)such as H2O2,NO−2,and NO−3 are observed with lengthening the discharge time.The production of multiple transient and LRS proposes AC excited gas–liquid argon discharge as a potential applicant in industrial wastewater cleaning,clinical medicine,and agriculture.

Wear resistance of surface metal matrix composite produced by gas tungsten arc melt injection of Cr3C2 -NiCr particles into low carbon steel

Cr3 C2-NiCr particles were injected into the melted surface of Q235 low carbon steel to make a surface metal matrix composite （MMC） layer by gas tungsten are melt injection （GTAMI） process. Hardness of the surface MMC layer was tested. Wear resistance of the surface MMC was investigated with a ball-on-disk dry sliding setup. Microstrnetures of the surface MMC layer and morphology of the worn surfaces were investigated with scanning electron microscopy （SEM）. The results showed that the hardness of the MMC was as high as 1 960. 7 HV. Wear loss of the upper part of the MMC layer is onlyO. 8% of that of the substrate under the dry sliding condition given. Wear loss of the bottom part is 2. 5 % of that of the substrate.

Two-dimensional metallic behavior at polar MgO/BaTiO_3(110) interfaces

The first-principles calculations are employed to investigate the electrical properties of polar MgO/BaTiO3（110）interfaces. Both n-type and p-type polar interfaces show a two-dimensional metallic behavior. For the n-type polar interface,the interface Ti3d electrons are the origin of the metallic and magnetic properties. Varying the thickness of Ba TiO3 may induce an insulator–metal transition, and the critical thickness is 4 unit cells. For the p-type polar interface, holes preferentially occupy the interface O 2p y state, resulting in a conducting interface. The unbalance of the spin splitting of the O 2p states in the interface Mg O layer leads to a magnetic moment of about 0.25μB per O atom at the interface.These results further demonstrate that other polar interfaces, besides LaAlO3/SrTiO3, can show a two-dimensional metallic behavior. It is helpful to fully understand the role of polar discontinuity on the properties of the interface, which widens the field of polar-nonpolar interfaces.

Tuning the electrons at the LaAlO_3/SrTiO_3 interface: From growth to beyond growth

Recently, the quasi-two-dimensional electron gas （q2DEG） confined at the interface between LaAlO3 and SrTiO3 has attracted significant attention. In this paper, we briefly review experimental methods that have been used to tune the carrier density and mobility of this q2DEG. These methods can be classified into two categories： growth-related tuning （i.e. substrate, growth temperature, oxygen pressure, post-annealing, LaAlO3 thickness, stoichiometry, and capping layers） and post-growth tuning （i.e. electrostatic field gating, conductive atomic force microscopy and surface adsorbates）. Taken together, these methods enable the broad tuning of the electronic properties of this interface.

Energy Recovery from MSW Treatment by Gasification and Melting Technology

The increase of waste production, joined to the difficulties concerning both the identification of new disposal sites and the construction of big conventional incinerators, led in recent years to the development of new technologies for waste management such as gasification and melting treatments. The possibility to introduce in the Italian context the DMS （direct melting system） technology, designed and manufactured by Nippon Steel Engineering Co. Ltd., has been taken into account for the scope of proposed work. DMS technology consists in MSW gasification, slags melting and combustion of the syngas produced, with the consequent generation of electric energy through a steam cycle. The system minimizes environmental impact, thanks to an effective recycling of useful resources such as inert melted slags and metals, featuring high flexibility in terms of treatment capacity due to its modular design. The aim of this article is to consider different plant configurations in order to optimize the energy recovery downstream the DMS module. As a case study, landfill gas exploitation integrated in the DMS plant will be considered as a typical situation that could occur in the Italian scenario. The energetic input provided by the biogas allows improving the thermo-economic performances according to market incentives.

熔压温度对光纤面板抗弯强度的影响

光纤面板在微光夜视、空间探测、核诊断、医学诊疗等领域有着广泛的应用,在使用过程中对强度有一定要求,目前缺少相关研究,本文研究了熔压温度对光纤面板x、y、z三个方向抗弯强度的影响,采用三点弯曲法测试光纤面板的抗弯强度。结果表明:熔压温度为660℃时,二次复丝之间熔合不充分,存在间隙,光纤面板抗弯强度较低,x、y、z方向抗弯强度分别为107、93、114 MPa;熔压温度为670℃时,二次复丝之间间隙消除,但依然存在界面,抗弯强度有所提升,x、y、z方向抗弯强度分别为110、109、125 MPa;熔压温度为680℃时,二次复丝充分熔合,此时光纤面板抗弯强度在x、z方向满足复合材料混合定律,分别为123、127 MPa,y方向芯玻璃作为增强相对皮玻璃起到增强作用,抗弯强度为113 MPa。本文研究对提高光纤面板强度以满足装管和使用需求具有重要意义。

寒旱环境灌木根系增强春融期边坡稳定性影响

春融期边坡极易发生热融滑塌现象,为研究植被根系与边坡冻融界面呈不同夹角α条件下边坡的潜在滑移面破坏形式、位移特征以及稳定性影响。结果表明:随融化深度的增加,春融期素土及根-土复合体边坡的等效塑性应变贯通带越明显,易沿着冻融界面发生平面状滑塌;相比于素土边坡,春融期(3月份)根-土复合体边坡最大位移量减小约69.65%,春融期(4月份)根-土复合体边坡最大位移量减小约71.88%,且根-土复合体边坡位移的减少量随着α角的增大而呈增大趋势,表现出根系伸入冻融界面处时具有较强的固土能力;当根系与冻融界面夹角α由45°增大至90°时,根-土复合体边坡的安全系数呈增长趋势,且根系与边坡冻融界面垂直时,根系具有相对最大限度地增强春融期边坡固土护坡作用,可有效提高春融期边坡的稳定性。研究成果为探讨冻融界面处植物根系对春融期边坡稳定性具有理论研究价值和实际指导意义。

熔体静电纺丝直写技术在组织工程中的应用

背景:计算机辅助设计下,熔体静电纺丝直写技术可以精确构建具有特定形貌的3D组织工程支架,在组织工程领域已经引起越来越多的关注。目的:阐述熔体静电纺丝直写技术近年来在组织工程中的应用进展。方法:利用PubMed、中国知网数据库检索有关熔体静电纺丝直写技术应用于组织工程的文献,检索时间范围为2008年3月至2023年2月,以“melt electrowriting,melt electrospinning,electrospinning,tissue engineering,scaffold,regeneration”为英文检索词,“熔体直写,静电纺丝,组织工程”为中文检索词,通过阅读文题和摘要对文章进行初步筛选,最终纳入69篇文献进行综述。结果与结论:①相较于传统的静电纺丝技术,熔体静电纺丝直写技术可以实现纤维的逐层精确沉积,更好地模拟天然组织的复杂结构;相比于其他3D打印技术,熔体静电纺丝直写技术可以制备更小直径的纤维,形成高度有序的多孔结构;②通过与其他支架制备技术或材料相结合,如熔融沉积建模、溶液静电纺丝技术、水凝胶等,熔体静电纺丝直写技术在制备复杂组织工程支架方面表现出巨大的潜力,为实现复杂组织的再生提供了一定可能;③复杂组织再生往往同时涉及血管、神经和软硬组织,血管和神经再生对于实现组织的生理性重建具有重要意义,软硬组织因其不同的生物、力学性能,实现二者的协调再生具有一定的困难,熔体静电纺丝直写技术可制备多尺寸、高孔隙率、良好生物相容性的支架,在仿生支架构建领域具有一定的优势。