2.5μm-Thick Ultrastrong Asymmetric Separator for Stable Lithium Metal Batteries

Lithium metal batteries(LMBs)are considered the ideal choice for high volumetric energy density lithium-ion batteries,but uncontrolled lithium deposition poses a significant challenge to the stability of such devices.In this paper,we introduce a 2.5μm-thick asymmetric and ultrastrong separator,which can induce tissue-like lithium deposits.The asymmetric separator,denoted by utPE@Cu_(2)O,was prepared by selective synthesis of Cu_(2)O nanoparticles on one of the outer surfaces of a nanofibrous(diameter~10 nm)ultrastrong ultrahigh molecular weight polyethylene(UHMWPE)membrane.Microscopic analysis shows that the lithium deposits have tissue-like morphology,resulting in the symmetric lithium cells assembled using utPE@Cu_(2)O with symmetric Cu_(2)O coating exhibiting stable performance for over 2000 h of cycling.This work demonstrates the feasibility of a facile approach ultrathin separators for the deployment of lithium metal batteries,providing a pathway towards enhanced battery performance and safety.

Confined cobalt single-atom catalysts with strong electronic metal-support interactions based on a biomimetic self-assembly strategy

Designing high-performance and low-cost electrocatalysts for oxygen evolu-tion reaction(OER)is critical for the conversion and storage of sustainable energy technologies.Inspired by the biomineralization process,we utilized the phosphorylation sites of collagen molecules to combine with cobalt-based mononuclear precursors at the molecular level and built a three-dimensional(3D)porous hierarchical material through a bottom-up biomimetic self-assembly strategy to obtain single-atom catalysts confined on carbonized biomimetic self-assembled carriers(Co SACs/cBSC)after subsequent high-temperature annealing.In this strategy,the biomolecule improved the anchoring efficiency of the metal precursor through precise functional groups;meanwhile,the binding-then-assembling strategy also effectively suppressed the nonspecific adsorption of metal ions,ultimately preventing atomic agglomeration and achieving strong electronic metal-support interactions(EMSIs).Experimental characterizations confirm that binding forms between cobalt metal and carbonized self-assembled substrate(Co–O_(4)–P).Theoretical calculations disclose that the local environment changes significantly tailored the Co d-band center,and optimized the binding energy of oxygenated intermediates and the energy barrier of oxygen release.As a result,the obtained Co SACs/cBSC catalyst can achieve remarkable OER activity and 24 h durability in 1 M KOH(η10 at 288 mV;Tafel slope of 44 mV dec-1),better than other transition metal-based catalysts and commercial IrO_(2).Overall,we presented a self-assembly strategy to prepare transition metal SACs with strong EMSIs,providing a new avenue for the preparation of efficient catalysts with fine atomic structures.

Deep seabed mining:Frontiers in engineering geology and environment

Ocean mining activities have been ongoing for nearly 70 years,making great contributions to industrialization.Given the increasing demand for energy,along with the restructuring of the energy supply catalyzed by efforts to achieve a low-carbon economy,deep seabed mining will play an important role in addressing energy-and resource-related problems in the future.However,deep seabed mining remains in the exploratory stage,with many challenges presented by the high-pressure,low-temperature,and complex geologic and hydrodynamic environments in deep-sea mining areas,which are inaccessible to human activities.Thus,considerable efforts are required to ensure sustainable,economic,reliable,and safe deep seabed mining.This study reviews the latest advances in marine engineering geology and the environment related to deep-sea min-ing activities,presents a bibliometric analysis of the development of ocean mineral resources since the 1950s,summarizes the development,theory,and issues related to techniques for the three stages of ocean mining(i.e.,exploration,extraction,and closure),and discusses the engineering geology environment,geological disasters,in-situ monitoring techniques,envi-ronmental protection requirements,and environmental effects in detail.Finally,this paper gives some key conclusions and future perspectives to provide insights for subsequent studies and commercial mining operations.

Study on Mechanical Properties and Action Mechanism of Leather Industrial Sludge Aggregate Baking-Free Bricks

Taking an industrial sludge and its preparation of sludge wrap shell aggregates(WSAs)instead of sand to prepare baking-free brick as the research object,the development law of mechanical properties and the influence mechanism of macro and micro characteristic parameters of the bricks under different sludge and WSAs replacement rates were studied through the macroscopic mechanical properties test,with the help of nuclear magnetic resonance(NMR),transmission electron microscopy-energy spectrum and other testing technology and pores and cracks analysis system(PCAS)software.The results showed that the compressive strength of each sample decreased with the increase of sludge content.When the sludge content was less than 30%,it was mainly affected by the water-binder ratio.When the sludge content was more than 30%,it was mainly affected by the sludge content.At the age of 7 days,with the increase in replacement rate of WSAs,the compressive strength of the S10 and S30 groups was higher than that of the control group.The compressive strength of the S50 experimental group was 30.38 MPa,and the loss of compressive strength was slight compared with the control group.The water absorption rate of the 28 days S100 experimental group increased by 10.71%compared with the control group.When the content of WSAs was less than 50%,the holes above 0.1μm in the brick can be reduced and transformed into smaller holes,with a decreasing trend of the plane porosity of the brick.The microscopic results of the baking-free brick showed that the three-phase system of WSAs-interface transition area-mortar was poorly bonded and delaminated compared with the gravel aggregate-interface transition area-mortar system,and damage was more likely to occur in the WSAs and interface transition area.The above results show that it is feasible to use sludge and WSAs instead of sand for the preparation of baking-free bricks.This technology not only solves the problem of sludge disposal,but also protects the over-exploitation of mineral resources,and the technology has a broad application prospect and market value.

近十年来美国新闻学博士学位论文研究主题量化分析

美国新闻学博士学位论文研究主题是研判美国新闻学研究现状的重要视角。文章对2010—2019年收录在PQDT数据库中的599篇美国新闻学博士学位论文研究主题展开量化分析后发现,"网络研究""报纸""社交媒体"的研究热度最高,"教育"话题备受关注。美国新闻学博士学位论文主题往往关联多个领域,学科交叉现象普遍。总体来看,美国新闻学博士生在研究的过程中倾向于深耕中小群体,紧贴普通民众日常工作与生活。在媒介与社会互动的考察上,博士生较为关心女性问题、认同问题和文化问题。在新闻教育研究方面,个体的健康教育、媒介素养教育热度不减。当前的研究前沿是社会学和健康与环境科学,其中博士生对后者的考察方兴未艾,以特定媒体为切口进行问题发掘的研究视角是新闻学博士生研究的一大特色。综合来看,美国新闻学博士生研究存在"内卷化"和批判性研究较为缺乏的问题,但其注重以人为研究主体的研究理念和"开小口,挖深井"的研究思路对中国的新闻研究具有一定参考意义。

Review on Wind Power Development and Relevant Policies between China and Japan

China has abundant wind energy resources and huge development potential among developing countries.Japan is a developed country that planned to increase the use of renewable energy,especially wind energy.This research is aimed at reviewing the development of wind power and relevant policies between China and Japan.Firstly,we introduced the current status of global wind power development,such as the global installed capacity of wind power.The annual development of wind power generation in China and Japan is compared,and the distribution characteristics of wind resources are compared.Furthermore,the market share in China and Japan is introduced.Finally,according to the comparison of the government policies between China and Japan,we pointed out the existing problems in the wind power industry.In addition,we gave some suggestions on the development of wind power for China and Japan.These suggestions should be taken into account when designing national climate policies and have an important reference value for the future development of China’s wind energy industry.

Optimal Configuration of an Off-Grid Hybrid Wind-Hydrogen Energy System: Comparison of Two Systems

Due to the uncertainty of renewable energy power generation and the non-linearity of load demand,it becomes complicated to determine the capacity of each device in hybrid renewable energy power generation systems.This work aims to optimize the capacity of two types of the off-grid hybrid wind-hydrogen energy system.We considered the maximum profit of the system and the minimum loss of power supply probability as optimization goals.Firstly,we established steady-state models of the wind turbine,alkaline electrolyzer,lead-acid battery,and proton exchange membrane fuel cell in matrix laboratory software to optimize the capacity.Secondly,we analyzed the operating mode of the system and determined two system structures(system contains batteries whether or not).Finally,according to the wind speed and load in the sample area,we compared the economics of the two systems and selected the optimal configuration for the area.In the same calculation example data,the non-dominated sorting genetic algorithm-II(NSGA-II)is used to optimize the capacity of each device in the two systems.The results showed that the profit of the without battery-equipped system is 32.38%higher than another system.But the power supply reliability is the opposite.To avoid the contingency of the calculation results,we used the traditional genetic algorithm(GA)and ant colony optimization(ACO)to calculate the same example.The results showed that NSGA-II is significantly better than GA and ACO in terms of iteration steps and calculation results.The required architecture for the System-I composes of 3 numbers of 10 kW wind turbines,61 sets of 12 V·240 Ah leadacid batteries,8 kW electrolytic cell,and 6 kW PEMFC.The net profit and LPSP are ¥44,315 and 0.01254 respectively.The required architecture for the System-II composes of 2 numbers of 10 kW wind turbines,24 kW electrolytic cells,and 18 kW PEMFC.Net profit and LPSP are ¥58,663 and 0.03244,respectively.This paper provided two schemes for the optimal configuration of the hybrid wind-hydrogen energy system in islanding mode,which provided a theoretical basis for practical engineering applications.

A Review of Research Status and Scientific Problems of Floating Offshore Wind Turbines

With the continuous utilization of offshore wind resources,the installation depth and capacity of offshore wind turbines are increasing.In order to meet construction requirements of renewable energy,offshore wind farms are bound to develop further and deeper into the sea.As a result,a novel kind of power generation equipment,Floating Offshore Wind Turbines(FOWT),emerges as the times require.Consequently,this paper provides an objective comment on some key scientific difficulties.Firstly,The statistics and forecast of the market demand and installed capacity of offshore wind energy show a steady growth.After that,the advantages of constructing FOWT and most floating projects in various countries are summarized.And then,the reconstruction design of blades is reviewed under“Reynolds number”and“Froude number”similarity criterion,which is a prerequisite for achieving specific aerodynamic performance.So far,this paper focuses on aerodynamic researches,including aerodynamic forces and flow fields.On this basis,pitch angle control strategies are proposed to reduce aerodynamic forces on the premise of ensuring power generations.Finally,some other joint science problems to be solved are listed.Whether theoretical analysis,numerical simulations,ocean engineering basin tests,wind tunnel experiments or prototype sea measurements,FOWT is expected to break through various obstacles and finally achieve efficient and stable commercial operations.

Review on Research about Wake Effects of Offshore Wind Turbines

In recent years,the construction of offshore wind farms is developing rapidly.As the wake effect of the upstream wind turbines seriously affect the performance of the downstream wind turbines,the wake effect of offshore wind turbines has become one of the research hotspots.First,this article reviews the research methods of wake effects,including CFD numerical simulation method,wind turbine wake model based on roughness and engineering wake models.However,there is no general model that can be used directly.Then it puts forward some factors that affect the wake of offshore wind turbines.The turbulence intensity in offshore wind fields is lower than that in onshore wind fields.This makes the wake recovery length of offshore wind turbines longer than that of onshore wind turbines.Floating offshore wind turbines are simultaneously disturbed by wind loads and wave loads.Unsteady movement of the platform caused by wave loads.It affects the development and changes of the wake of wind turbines.In this regard,the focus of research on the wake effects of offshore wind farms will be the proposal of accurate prediction models for the wake effects of sea wind farms.

A highoutput PDMS-MXene/gelatin triboelectric nanogenerator with the petal surface-microstructure

Triboelectric nanogenerator(TENG)has a promising future in the field of energy harvesting and self-powered sensing due to their simplicity in structure,low cost,and efficient energy harvesting from the surrounding environment.The output electrical performance of TENG can be improved by doping the friction material with functional materials and modifying the surface of the friction material.However,the current method of adding functional materials to friction materials is costly and wasteful,and the method of modifying the surface structure of friction materials is cumbersome and not easy to operate.In this work,we present a polydimethylsiloxane(PDMS)-MXene/gelatin triboelectric nanogenerator(PMMG-TENG)based on petal surface-microstructures,which has the advantages of low cost,simple preparation,high output performance,and ecological friendliness.By doping 0.03 wt.%of MXene in PDMS,the output electrical performance of TENG can be significantly improved,with an output current increase of up to 139.7%.Four different petals are used as natural molds to prepare PMMG-TENG.The results show that PMMG-TENG with peony petal surface microstructure has the best electrical performance,and the output current increase of up to 228.17%compared with PMMG-TENG without structure.The PMMG-TENG with peony petal surface-microstructure exhibits excellent electrical performance,demonstrating a maximum open-circuit voltage of 417.39 V and a maximum short-circuit current of 12.01μA at a size of 3 cm×3 cm,and a maximum power density of 170μW/cm^(2) at a load resistance of 107Ω.The PMMG-TENG’s output performance after 10,000 cycles is consistent with the initial state,highlighting excellent output stability.The PMMG-TENG can easily light up at least 100 light emitting diodes(LEDs).(operating voltage 3V.)Gelatin film exhibits excellent degradation performance,with complete degradation time of only 150 s in water at a constant temperature of 75℃.PMMG-TENG not only shows excellent performance in the field of energy harvesting,but also has a broad application prospect in the field of self-powered sensing.This work provides a simple,low cost,natural and green method to significantly improve the output electrical performance of TENG.

Dysbiosis of oral and gut microbiota and its association with metabolites in patients with different degrees of coronary artery stenosis

To the Editor:Coronary atherosclerotic heart disease(CAD)arises from coronary atherosclerosis(CAS)plaque buildup,resulting in coronary stenosis(CS)and occlusion,ultimately causing myocardial ischemia,hypoxia,or necrosis.Studies showed that the high-grade CS may be an important predictor of ST segment elevation myocardial infarction in subsequent months.

Accurate closed-form eigensolutions of three-dimensional panel flutter with arbitrary homogeneous boundary conditions

Highly accurate closed-form eigensolutions for flutter of three-dimensional(3D)panel with arbitrary combinations of simply supported(S),glide(G),clamped(C)and free(F)boundary conditions(BCs),such as cantilever panels,are achieved according to the linear thin plate theory and the first-order piston theory as well as the complex modal analysis,and all solutions are in a simple and explicit form.The iterative Separation-of-Variable(iSOV)method proposed by the pre-sent authors is employed to obtain the highly accurate eigensolutions.The flutter mechanism is studied with the benefit of eigenvalue properties from mathematical senses.The effects of boundary conditions,chord-thickness ratios,aerodynamic damping,aspect ratios and in-plane loads on flut-ter properties are examined.The results are compared with those of Kantorovich method and Galerkin method,and also coincide well with analytical solutions in literature,verifying the accu-racy of the present closed-form results.It is revealed that,(A)the flutter characteristics are domi-nated by the cross section properties of panels in the direction of stream flow;(B)two types of flutter,called coupled-mode flutter and zero-frequency flutter which includes zero-frequency single-mode flutter and buckling,are observed;(C)boundary conditions and in-plane loads can affect both flutter boundary and flutter type;(D)the flutter behavior of 3D panel is similar to that of the two-dimensional(2D)panel if the aspect ratio is up to a certain value;(E)four to six modes should be used in the Galerkin method for accurate eigensolutions,and the results converge to that of Kantorovich method which uses the same mode functions in the direction perpendicular to the stream flow.The present analysis method can be used as a reference for other stability issues characterized by complex eigenvalues,and the highly closed-form solutions are useful in parameter designs and can also be taken as benchmarks for the validation of numerical methods.

Formation and evolution mechanism of metal whiskers in extreme aerospace environments:A review

The spontaneous growth and evolution mechanism of metal whiskers have long been scientific problems.With the development of the integration of electronic and electrical productions,short circuits and system failures are raised by metal whiskers continuously.In the meantime,the related theories and mechanisms of whiskering problem are still vague,leading to a deficiency in the studies of environmental factors influencing the whisker phenomenon.Besides,the extreme environments such as aerospace,have been proven the accelerators to the formation of metal whiskers,resulting in a severe threaten to equipment and devices working in such environments including satellite and military equipment.To establish a comprehensive understanding to the whiskering process associated with their applicable control strategies,this study analyzes the growth phenomenon,influencing factors,formation process and evolution mechanism of metal whiskers in extreme service environments,puts forward the corresponding controlling strategies,offers a reference for the establishment of Chinese extreme aerospace strategic environment,and improves the reliability of aerospace systems.

Supercapacitors as redox mediators for decoupled water splitting

With the help of the redox mediator, decoupled water-splitting allows O_(2)and H_(2)to be produced at different times, at different rates, and even in different cells, which promotes both the operation safety and the utilization of renewable power sources. However, the current densities and stabilities of these redox mediators are commonly low, which require further improvements for practical applications. Here, we propose to use supercapacitors as solid state redox mediators for decoupled water splitting. For demonstration, Na_(0.5)MnO_(2)(pseudocapacitor) and active carbon(double layer capacitor), are both used as the redox mediator. These supercapacitors show superior current density(1 A/cm^(2)) and ultralong cycle-life(8000 cycles) compared with commonly investigated battery-based mediators(NiOOH/Ni(OH)_(2)). Our research proves supercapacitors can be used as redox relay with high current density and stability, which may bring new insights in the design of decoupled water splitting systems.

Mechanism Research of Electroacupuncture Stimulation at Baihui and Zusanli in Cerebral Ischemia-reperfusion Injury Using RNA-Sequencing

Background:Electroacupuncture(EA)therapy,as a combination of electric stimulation and traditional acupunc-ture technology,is currently an important mean for treatment of ischemic stroke and post-stroke rehabilitation in China.Because of its remarkable therapeutic effect,it has been widely used in hospitals and clinic,however,the detailed mechanism remains unclear.Objective:This research aims to comprehensively and systematically elucidate the mechanisms of EA treatment at the acupoints of Zusanli(ST36)and Baihui(GV20)on ischemic stroke.Methods:In this study,EA was performed twice at onset of reperfusion and 20 h after reperfusion following cerebral ischemia-reperfusion(I/R)in middle cerebral artery occlusion(MCAO)rats,and transcriptomic changes of various molecules in ischemic hippocampal neurons of rats in Sham,I/R and EA groups were detected by RNA-Sequencing(RNA-Seq).Results:Thus,we detected 18 significantly different genes related to atherosclerosis(AS),with their functions associated with lipid metabolism,thrombosis,monocytes and vascular smooth muscle cells.And,we detected 10 significantly different genes related to oxidative stress and apoptosis and 10 significantly different genes related to calcium overload and excitatory amino acids release.Also,we detected 19 significantly different genes related to blood-brain barrier(BBB)and 22 significantly different genes related to inflammatory response.Conclusion:In conclusion,EA can play a role in treating ischemic stroke through a variety of mechanisms,affecting atherosclerosis,oxidative stress,apoptosis,calcium overload,excitatory amino acids release,blood-brain barrier(BBB)and inflammatory response.

Synthesis of Alumina-Coated Natural Graphite for Highly Cycling Stability and Safety of Li-Ion Batteries

The natural graphite(NG)urdformly coated with alumina ceramics(Al2O3)was successfully synthesized through sol-gel method.The aluminum plastic film soft-packed battery prepared using Al2O3-coated NG as anode material exhibits excellent cycle performance and safety performance.The cycling retention of AN-1 is 84.95% after 200 cycles at a rate of 1 C in a potential window ranging from 3.0 to 4.35 V,which is much greater than 75.07% of NG under the same test conditions.The result of the nail penetration tests shows that the successful nail penetration rate of the NG used as anode is 0%,while that of Al2O3 coated samples AN-1 is 100%.The test results show that the Al2O3 coating could act as a solid electrolyte to suppress side reactions,improve cycle stability,and prevent a thermal runaway under mechanical abuse.

Electrolyte additive maintains high performance for dendrite-free lithium metal anode

Because of their high capacity and low potential,lithium metal anodes are considered to be promising candidates for next generation electrode materials.However,the safety concerns and limited cycling life associated with uncontrollable dendrite growth hamper practical applications.In this work,the acidified cellulose ester,which is a mixed fiber microporous membrane film,was used as a novel electrolyte additive that effectively improves the cycle stability of the lithium metal anode and inhibits dendrite growth.The focus of this paper is on inhibiting the formation and growth of lithium dendrites.The coulombic efficiency of a Li|Cu battery with this acidified cellulose ester additive remains stable at 99%after 500 cycles under a current density of 1 mA/cm^2.Symmetric batteries also remain stable after 500 cycles(1000 h)under a current density of 1 mA/cm^2.These superior properties can be ascribed to the induced nucleation and the uniform distribution of lithium ion flux.This study uncovers an approach for effectively enabling stable cycling of dendrite-free lithium metal anodes.

Formation of defects in selective laser melted Inconel 718 and its correlation with mechanical properties through dimensionless numbers

This paper presents a profound study on the formation of three typical types of defects(i.e.,lack of fusion,keyholes,and gas pores)observed in selective laser melting(SLM)printed Inconel 718 samples,along with their correlations with mechanical properties of the samples.Computed tomography,scanning electron microscopy,and mechanical property tests revealed that the three types of defects fall into three stages of porosity evolution classified by recently-proposed dimensionless numbersηm(melting efficiency)andηv(vaporization efficiency).Meanwhile,experimental tests verified that the mechanical properties of products,such as strength and elongation,are remarkably sensitive to lack of fusion.However,these properties are slightly affected by the keyholes and gas pores.An optimal process window characterized by dimensionless numbers is realized by adjusting the processing parameters and employing different powders.This process window allows products to have relatively low defects and high mechanical performances.A quantitative relation between processing parameters,dimensionless numbers,defects,and mechanical properties is established based on these observations.This relation,along with the optimal process window,is believed to enhance the quality of SLM products of Inconel 718 alloy and can be further extended to SLM with other metal materials.

Exploring the Bridge Cases’Role in the Transmission of the SARSCoV-2 Delta Variant—Ruili City,Yunnan Province,China,July–September 2021

Summary What is already known about this topic?The severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)Delta variant has proved to have increased transmissibility,and mutations that can cause partial immune escape,which makes its transmission more insidious.What is added by this report?This study showed that probable cases who had negative results in nucleic acid testing but had positive IgM test result and/or IgG test value of over 20 S/CO in antibodies testing.

Aromatic Amide Polymers that Form Two Helical Conformations with Twist Sense Bias in Water

Two benzene/2,2＇-bipyridine-alternately incorporated amide polymers have been prepared, which are driven by hydrophobicity to form two different helical conformations. Both helices exhibit twist sense bias in water induced by chiral valine side chains and the coordination of the 2,2＇-bipyridine unit to the Ni2＋ ions.