The outpost against cancer:universal cancer only markers

Cancer is the leading cause of death worldwide.Early detection of cancer can lower the mortality of all types of cancer;however,effective early-detection biomarkers are lacking for most types of cancers.DNA methylation has always been a major target of interest because DNA methylation usually occurs before other detectable genetic changes.While investigating the common features of cancer using a novel guide positioning sequencing for DNA methylation,a series of universal cancer only markers(UCOMs)have emerged as strong candidates for effective and accurate early detection of cancer.While the clinical value of current cancer biomarkers is diminished by low sensitivity and/or low specificity,the unique characteristics of UCOMs ensure clinically meaningful results.Validation of the clinical potential of UCOMs in lung,cervical,endometrial,and urothelial cancers further supports the application of UCOMs in multiple cancer types and various clinical scenarios.In fact,the applications of UCOMs are currently under active investigation with further evaluation in the early detection of cancer,auxiliary diagnosis,treatment efficacy,and recurrence monitoring.The molecular mechanisms by which UCOMs detect cancers are the next important topics to be investigated.The application of UCOMs in real-world scenarios also requires implementation and refinement.

Accelerated prediction of Cu-based single-atom alloy catalysts for CO_(2) reduction by machine learning

Various strategies,including controls of morphology,oxidation state,defect,and doping,have been developed to improve the performance of Cu-based catalysts for CO_(2) reduction reaction(CO_(2)RR),generating a large amount of data.However,a unified understanding of underlying mechanism for further optimization is still lacking.In this work,combining first-principles calculations and machine learning(ML)techniques,we elucidate critical factors influencing the catalytic properties,taking Cu-based single atom alloys(SAAs)as examples.Our method relies on high-throughput calculations of 2669 CO adsorption configurations on 43 types of Cu-based SAAs with various surfaces.Extensive ML analyses reveal that low generalized coordination numbers and valence electron number are key features to determine catalytic performance.Applying our ML model with cross-group learning scheme,we demonstrate the model generalizes well between Cu-based SAAs with different alloying elements.Further,electronic structure calculations suggest surface negative center could enhance CO adsorption by back donating electrons to antibonding orbitals of CO.Finally,several SAAs,including PCu,AgCu,GaCu,ZnCu,SnCu,GeCu,InCu,and SiCu,are identified as promising CO_(2)RR catalysts.Our work provides a paradigm for the rational design and fast screening of SAAs for various electrocatalytic reactions.

Detection of Pesticide Metsulfuron-methyl in Drinking Water by Differential Pulse Cathodic Stripping Voltammetry

Differential pulse cathodic stripping voltammetry was used to determine pesticide metsulfuron-methyl on a suspended mercury electrode.Specific experimental parameters,such as the pH of Britton-Robinson buffer,accumulation time,accumulation potential,and initial potential were optimized.The results show that a typical reduction peak appeared when pH was 2.0-4.0 and initial potential ranged from-0.75 to-1.0 V.To obtain the stripping signal of the best reduction peak,it is determined that the best pH was 2.0.The detection limit of the method was only 0.04 mg/L,and it had good selectivity and high accuracy,so the method has high sensitivity.In the analysis of actual drinking water,the recovery rate of metsulfuron-methyl could reach 93%-101%.

Iodine-assisted ultrafast growth of high-quality monolayer MoS_(2) with sulfur-terminated edges

Two-dimensional(2D)semiconductors have attracted great attention to extend Moore’s law,which motivates the quest for fast growth of high-quality materials.However,taking MoS_(2) as an example,current methods yield 2D MoS_(2) with a low growth rate and poor quality with vacancy concentrations three to five orders of magnitude higher than silicon and other commercial semiconductors.Here,we develop a strategy of using an intermediate product of iodine as a transport agent to carry metal precursors efficiently for ultrafast growth of high-quality MoS_(2).The grown MoS_(2) has the lowest density of sulfur vacancies(~1.41×10^(12) cm^(−2))reported so far and excellent electrical properties with high on/off current ratios of 108 and carrier mobility of 175 cm^(2) V^(−1) s^(−1).Theoretical calculations show that by incorporating iodine,the nucleation barrier of MoS_(2) growth with sulfur-terminated edges reduces dramatically.The sufficient supply of precursor and low nucleation energy together boost the ultrafast growth of sub-millimeter MoS_(2) domains within seconds.This work provides an effective method for the ultrafast growth of 2D semiconductors with high quality,which will promote their applications.

Conflict in Yemen and its impacts on China’s interests in the region

The conflict in Yemen,which has been going on for 8 years,has great repercussions for Yemen and the entire region.Yemen’s strategic position has made it a key player in a crucial area that influences energy supplies,and international shipping routes,as well as a point of contact between Asia,Africa,and Europe.China,the area’s greatest economic partner and largest importer of oil,was one of those affected,particularly with the announcement of the Chinese BRI and its massive projects in the region.The pro-longed conflict in Yemen has hampered Chinese investments and the construction of several key and strategic BRI projects in Yemen,as well as jeopardising many of its mega projects in the region.It also posed a new threat to the Red Sea and the Gulf of Aden’s sea routes,as well as the establishment of new military bases in strategic areas capable of controlling international trade routes and intensifying military rivalry in the region.

Thickness-dependent patterning of MoS2 sheets with well-oriented triangular pits by heating in air

自从 MoS2 表的性质对边结构敏感，有常规边或可控制的形状的 Patterning ultrathin MoS2 层正在呼吁。在这个工作，我们介绍了一种简单、有效、控制得好的技术由简单地在空中加热样品与面向井的等边的三角形的坑蚀刻分层的 MoS2 表。各向异性的氧化蚀刻被包围温度和 MoS2 层的数字极大地影响，坑由此随包围温度和 MoS2 层的数字的增加缩放增加。第一原则的计算被执行了解释三角形的坑的形成机制。这种技术把一条其他的大街提供给设计 MoS2 表的结构。

Group VB transition metal dichalcogenides for oxygen reduction reaction and strain-enhanced activity governed by p-orbital electrons of chalcogen

Developi ng alter native oxyge n reducti on reactio n (ORR) catalysts to replace precious Pt-based metals with abundant materials is the key challe nge of commercial application of fuel cells. Owing to their various compositi ons and tun able electronic properties, transition metal dichalcogenides (TMDs) have the great potential to realize high-efficiency catalysts for ORR. Here, various 3R-phase dichalcogenides of group VB and VIB transition metals (MX2, M = Nb, Ta, Mo, W;X = S, Se, Te) are investigated for ORR catalysts by using density functional theory calculations. The computed over-potentials of group VB TMDs are much less than those of group VIB TMDs. For group VB TMDs, a volcano-type plot of ORR catalytic activity is established on the adsorption energies of *OH, and NbS2 and TaTe2 exhibit best ORR activity with an oveepotential of 0.54 V. To achieve even better activity, strain engineering is performed to tune ORR catalytic activity, and the minimum over-potential of 0.43 V can be realized. We further dem on strate that the shift of p orbital center of surface chalcoge n elements under strain is responsible for tuning the catalytic activity of TMDs.

Space-confined growth of monolayer ReSe2 under a graphene layer on Au foils

Vertical heterostructures based on two-dimensional(2D)materials have attracted widespread interest for their numerous applications in electronic and optoelectronic devices.Herein,we report the direct construct!on of an abnormal graphene/ReSe2 stack on Au foils by a two-step chemical vapor deposition(CVD)strategy.During the second growth stage,mono layer ReSe2 is found to prefere ntially evolve at the irUerface between the first-grown graphene layer and the Au substrate.The unusual stacking behavior is unraveled by in-situ"cutting open"the upper graphene from the defects to expose the lower ReSe2 using scanning tunneling microscopy(STM).From combination of these results with density functional theory calculations,the domain boundaries and edge sites of graphene are proposed to be adsorption sites for Re and Se precursors,further facilitating the growth of ReSe2 at the van der Waals gap of graphene/Au.This work hereby offers an intriguing strategy for obtaining vertical 2D heterostructures featured with an ultra-clean interface and a designed stacking geometry.

First passage Markov decision processes with constraints and varying discount factors

This paper focuses on the constrained optimality problem （COP） of first passage discrete-time Markov decision processes （DTMDPs） in denumerable state and compact Borel action spaces with multi-constraints, state-dependent discount factors, and possibly unbounded costs. By means of the properties of a so-called occupation measure of a policy, we show that the constrained optimality problem is equivalent to an （infinite-dimensional） linear programming on the set of occupation measures with some constraints, and thus prove the existence of an optimal policy under suitable conditions. Furthermore, using the equivalence between the constrained optimality problem and the linear programming, we obtain an exact form of an optimal policy for the case of finite states and actions. Finally, as an example, a controlled queueing system is given to illustrate our results.

双金属源制备具有有序阳离子空位的非层状二维金属硫化物

二维(2D)过渡金属硫族化合物(TMC)在纳米电子学和能源等领域中有广泛的应用前景.其中,非层状TMC由于表面不饱和悬挂键以及强大的层内和层间化学键使其2D生长极具挑战,限制了极限厚度下的物性探究.本文提出了一种普适的双金属源生长方法,利用金属及其氯化物的混合物作为金属前驱体,实现了非层状2D TMC的可控生长.以六方Fe_(1-x)S为例,Fe_(1-x)S纳米片的厚度薄至3 nm,横向尺寸超过100μm.与MoS_(2)这类层状TMC(阴离子空位占主导)不同的是,本研究在Fe_(1-x)S中发现了有序阳离子Fe空位.低温输运测试和理论计算结果表明,2D Fe_(1-x)S是一种稳定的窄带隙半导体,其带隙宽度约为60 meV.除Fe_(1-x)S外,该方法还可用于生长其他多种具有有序阳离子空位的非层状2D TMC,包括Fe_(1-x)Se,Co_(1-x)S,Cr_(1-x)S和V_(1-x)S.本工作为非层状材料在2D厚度极限下的生长和物性表征铺平了道路.

Tunable valley band and exciton splitting by interlayer orbital hybridization

Magnetic proximity effect has been demonstrated to be an effective routine to introduce valley splitting in two-dimensional van der Waals heterostructures.However,the control of its strength and the induced valley splitting remains challenging.In this work,taking heterobilayers combining monolayer MSe_(2)(M=Mo or W)with room-temperature ferromagnetic VSe_(2)as examples,we demonstrate that the valley splitting for both band edges and excitons can be modulated by the tuning of the interlayer orbital hybridization,achieved by inclusion of different amounts of exact Hartree exchange potential via hybrid functionals.Besides,we show such tuning of orbital hybridization could be experimentally realized by external strain and electric field.The calculations suggest that large valley band splitting about 30 meV and valley exciton splitting over 150 meV can be induced in monolayer MSe_(2).Our work reveals a way to control proximity effects and provides some guidance for the design of optoelectronic and valleytronic devices.

2D materials: Rising star for future applications

Two-dimensional(2D)materials have attracted enormous research interest due to their predominant quantum effects and fascinating materials properties,which potentially lead to various important applications.Meanwhile,the sheer openness of 2D materials makes their interactions with external stimuli particularly efficient.It is much more convenient to modulate the materials properties of 2D systems by mechanical,electronic,optical,and magnetic modulations than in 3D bulks,advantageous for device control.