Performance Limits and Advancements in Single 2D Transition Metal Dichalcogenide Transistor

Two-dimensional(2D)transition metal dichalcogenides(TMDs)allow for atomic-scale manipulation,challenging the conventional limitations of semiconductor materials.This capability may overcome the short-channel effect,sparking significant advancements in electronic devices that utilize 2D TMDs.Exploring the dimension and performance limits of transistors based on 2D TMDs has gained substantial importance.This review provides a comprehensive investigation into these limits of the single 2D-TMD transistor.It delves into the impacts of miniaturization,including the reduction of channel length,gate length,source/drain contact length,and dielectric thickness on transistor operation and performance.In addition,this review provides a detailed analysis of performance parameters such as source/drain contact resistance,subthreshold swing,hysteresis loop,carrier mobility,on/off ratio,and the development of p-type and single logic transistors.This review details the two logical expressions of the single 2D-TMD logic transistor,including current and voltage.It also emphasizes the role of 2D TMD-based transistors as memory devices,focusing on enhancing memory operation speed,endurance,data retention,and extinction ratio,as well as reducing energy consumption in memory devices functioning as artificial synapses.This review demonstrates the two calculating methods for dynamic energy consumption of 2D synaptic devices.This review not only summarizes the current state of the art in this field but also highlights potential future research directions and applications.It underscores the anticipated challenges,opportunities,and potential solutions in navigating the dimension and performance boundaries of 2D transistors.

波纹轧制制备Cu/Al复合板的应力分析及显微组织演变

建立三维有限元模型,并通过50%压下量的轧制试验验证模型的准确性。从时间角度分析整个波纹轧制过程中金属的流动规律。金属经历的变形可以分为两个阶段:填充阶段和压下阶段。填充阶段应力变化较为复杂,而压下阶段应力变化趋势一致。通过罗德参数和应力三轴度分析特征位置的应力状态,在开始变形时为两向拉应力一向压应力。采用EBSD技术分析Cu板的显微组织演变过程。与原始板材相比,铜板各特征位置晶粒均发生细化,而Cu板波谷处晶粒在发生细化后有长大的现象,这是由剧烈塑性变形产生的绝热温升现象造成的。

Predictive value of neutrophil infiltration as a marker of Helicobacter pylori infection

AIM： To evaluate the predictive value of neutrophil in- filtration as a marker of Helicobacter pylori （H. pyloni） infection. METHODS： A total of 315 patients with dyspepsia symptoms who underwent upper gastrointestinal en- doscopy were enrolled in this study. Biopsies were evaluated using the updated Sydney system. The medication history of all patients in the preceding 4 wk was recorded. The diagnosis of H. pylori infection was based on 13C-urea breath test at least 4 wk after with- drawal of antisecretory drugs, antibiotics and related drugs. For the patients with subtotal gastrectomy, the diagnosis of H. pylori infection was based on anti-H. pylori immunoglobulin G （IgG） antibody. Serum anti-H. pylori IgG antibody was measured by enzyme-linked immunosorbent assays （Biohit, Finland）. RESULTS： The sensitivity, specificity, positive predic- tive value and negative predictive value of neutrophil infiltration in the diagnosis ofH, pylorlinfection were 92.3%, 83.5%, 77.4% and 94.7%, respectively. Neu- trophil infiltration of gastric mucosa in the histological analysis was strongly associated withH, pylorlinfection （77.4% vs 5.3% in the neutrophil infiltration negative group, P = 0.000）. Moderate neutrophil infiltration was more frequent in H. pylorl infection when compared to mild infiltration （81.8% and 75%, respectively）, but did not reach statistical significance. For those patients with negative rapid urease test, H. pylori was detected in 73.2% of patients with positive neutrophil infiltration on histology. In patients with subtotal gastrectomy, the diagnostic accuracy of neutrophil infiltration in H. pylori infection was 50%. CONCLUSION： Neutrophil infiltration is closely associ- ated withH, pylori and may be recognized as a sign of this infection.

Hot deformation behavior of Super304H austenitic heat resistant steel

The hot compression tests of Super304H austenitic heat resistant steel were carried out at 800-1200℃and 0.005-5 s^-1 using a Gleeble 3500 thermal-mechanical simulator,and its deformation behavior was analyzed.The results show that the flow stress of Super304H steel decreases with the decrease of strain rate and the increase of deformation temperature; the hot deformation activation energy of the steel is 485 kJ/mol.The hot deformation equation and the relationship between the peak stress and the deformation temperature and strain rate is obtained.The softening caused by deformation heating cannot be neglected when both the deformation temperature and strain rate are higher.

Mechanism and Inhibition of Grain Coarsening of Al-Mg-Si Alloy in Hot Forming

A high-Ti 6061 alloy was rolled with strains up to 0. 8 - 2. 0 and at 350 - 550 ℃ . Microstructures that developed during deformation and subsequent solution heat treatment (SHT) were observed by using optical and transmission electron microscopy. Microstructure evolution during SHT depends mainly on the initial rolling temperature,and it was found that the higher this temperature is,the coarser the grains are. After rolling at 400 ℃ ,well-defined cells and subgrains were formed, which induced further sites for recrystallization nucleation during subsequent SHT. The recrystallization mechanism was found to be subgrain rotation,with a final grain size smaller than 200 μm. Increasing the rolling temperature to 500 ℃ results in a low density of dislocations distributed uniformly in the deformed matrix and fewer nucleation sites during subsequent SHT. The recrystallization mechanism is grain boundary bulging,while the final grain size approaches several millimeters. Finally,a hot forming process of high-Ti 6061 alloy for inhibiting grain coarsening was proposed,and verified by experiments.

Effects of initial grain size and strain on grain boundary engineering of high-nitrogen CrMn austenitic stainless steel

18 Mn18 Cr0.5 N steel with an initial grain size of 28–177 μm was processed by 2.5%–20% cold rolling and annealing at 1000°C for 24 h,and the grain boundary character distribution was examined via electron backscatter diffraction.Low strain(2.5%) favored the formation of low-Σ boundaries.At this strain,the fraction of low-Σ boundaries was insensitive to the initial grain size.However,specimens with fine initial grains showed decreasing grain size after grain boundary engineering processing.The fraction of low-Σ boundaries and the(Σ9 + Σ27)/Σ3 value decreased with increasing strain; furthermore,the specimens with fine initial grain size were sensitive to the strain.Finally,the effects of the initial grain size and strain on the grain boundary engineering were discussed in detail.

Size effect of lattice material and minimum weight design

The size effects of microstructure of lattice materials on structural analysis and minimum weight design are studied with extented multiscale finite element method（EMsFEM） in the paper. With the same volume of base material and configuration, the structural displacement and maximum axial stress of micro-rod of lattice structures with different sizes of microstructure are analyzed and compared.It is pointed out that different from the traditional mathematical homogenization method, EMsFEM is suitable for analyzing the structures which is constituted with lattice materials and composed of quantities of finite-sized micro-rods.The minimum weight design of structures composed of lattice material is studied with downscaling calculation of EMsFEM under stress constraints of micro-rods. The optimal design results show that the weight of the structure increases with the decrease of the size of basic sub-unit cells. The paper presents a new approach for analysis and optimization of lattice materials in complex engineering constructions.

Transport properties of doped Bi2Se3 and Bi2Te3 topological insulators and heterostructures

In this review article, the recent experimental and theoretical research progress in Bi2Se3-and Bi2Te3-based topological insulators is presented, with a focus on the transport properties and modulation of the transport properties by doping with nonmagnetic and magnetic elements. The electrical transport properties are discussed for a few different types of topological insulator heterostructures, such as heterostructures formed by Bi2Se3-and Bi2Te3-based binary/ternary/quaternary compounds and superconductors, nonmagnetic and magnetic metals, or semiconductors.

Dramatic Spectral Broadening of Ultrafast Laser Pulses in Molecular Nitrogen Ions

We investigate nonlinear interaction of nitrogen molecules with a two-color laser field composed by an intense 800 nm laser pulse and a weak 400 nm laser pulse.It is demonstrated that the spectrum of 400 nm pulses is dramatically broadened when the two beams temporally overlap.In comparison,the spectral broadening in argon is less pronounced,although argon atoms and nitrogen molecules have comparable ionization potentials.We reveal that the dramatic spectral broadening originates from the greatly enhanced nonlinear optical effects in the near-resonant condition of interaction between the 400 nm pulses and the nitrogen molecular ions.

Phase and CCT Diagram of an N-Containing 8%Cr Roller Steel

The pseudo-equilibrium phase diagram and continuous cooling transformation diagram of an N-containing 8％ Cr roller steel were investigated by using thermodynamic calculation,differential scanning calorimetry,Ⅹ-ray diffraction,expansion method,and so on.Under equilibrium conditions,the main carbonitrides are MX,M7C3,and M23C6 types.The measured Ac1,Ac3,start temperature of martensitic transformation,and M7C3 transformation temperatures are 811,855,324,and 1100 ℃,respectively.Bainite appears at cooling rates ranging from 0.5 to 5 ℃/s and ferrite forms at grain boundaries at a cooling rate lower than 0.5 ℃/s.Finally,the effects of adding N and lowering the C content on workability and mechanical properties of common 8％Cr steel were discussed.

Effects of parecoxib + dexmedetomidine on systemic inflammation and oxidative stress during anesthesia recovery period of thoracoscopic surgery

Objective: To study the effects of parecoxib + dexmedetomidine on systemic inflammation and oxidative stress during anesthesia recovery period of thoracoscopic surgery. Methods:The lung cancer patients undergoing thoracoscopic surgery in Kailuan General Hospital between March 2015 and February 2018 were selected as the research subjects and randomly divided into the experimental group who received parecoxib + dexmedetomidine preemptive analgesia combined with conventional anesthesia and the control group who received conventional anesthesia. 3 and 5 d after surgery, serum was collected to measure the contents of inflammatory cytokines interferon-γ (IFN-γ), interleukin-1β (IL-1β), interleukin-18 (IL-18), intercellular adhesion molecule-1 (ICAM1) and monocyte chemoattractant protein-1 (MCP1) as well as oxidative stress mediators cortisol (COR), malondialdehyde (MDA), endothelin-1 (ET-1), superoxide dismutase (SOD) and total antioxidant capacity (T-AOC), and peripheral anticoagulant blood was collected to measure the expressions of inflammatory signaling molecules Toll-like receptor 4 (TLR4), NOD-like receptor protein 3 (NLRP3), nuclear factor-κB (NF-κB), apoptosis-associated speck-like protein containing CARD (ASC) and cysteinyl aspartate specific proteinase-1 (caspase-1) as well as oxidative stress molecules nuclear factor E2-related factor 2 (NRF2), antioxidant response element (ARE), NADPH oxidase (NOX) 2 and NOX4. Results: 3 and 5 d after surgery, serum IFN-γ, IL-1β, IL-18, ICAM1, MCP1, COR, MDA and ET-1 contents as well as peripheral blood TLR4, NLRP3, NF-κB, ASC, Caspase-1, NRF2, ARE, NOX2 and NOX4 expression intensity of the experimental group were significantly lower than those of the control group whereas serum SOD and T-AOC contents were higher than those of the control group. Conclusion: Parecoxib+ dexmedetomidine can inhibit the systemic inflammation and oxidative stress during anesthesia recovery period of thoracoscopic surgery.

Exploring Nonlinear Rheological Behaviors in Entangled Semi-flexible Polymer Melts

This study utilizes molecular dynamics simulation to investigate the complex dynamics of entangled semi-flexible polymer melts.The investigation reveals a significant stress overshoot phenomenon in the systems,demonstrating the intricate interplay between shear rates,chain orientation,and chain stretching dynamics.Additionally,the identification of metastable states,characterized by a dual-plateau phenomenon in the shear stress-strain curve at specific Rouse-Weissenberg number Wi_(R),showcases the system’s responsiveness to external perturbations and its transition to stable shear banding states.Moreover,the analysis of flow field deviations uncovers a progression of shear bands with increasing Wi_(R),displaying distinct behaviors in the system’s dynamics under different shear rates and chain lengths.These findings challenge established theoretical frameworks and advocate for refined modelling approaches in polymer rheology research.

Mechanism of high-energy pulsed current-assisted rolling of 08AL carbon steel ultra-thin strip

To improve the plastic deformation performance of a 08AL carbon steel ultra-thin strip,a pulsed electric field was integrated into the plastic processing of the ultra-thin strip,and the effects of high-energy current on its deformation ability were investigated.Current-assisted tensile tests were employed,and the results clarified that the pulsed current could reduce the activation energy of faults and promoted dislocation slip within grains and at grain boundaries,leading to a decrease in the deformation resistance of the metal and an increase in its plastic properties.Under the current density of 2.0 A/mm2,the yield strength,tensile strength,and elongation of the rolled sample reached 425 MPa,467 MPa,and 12.5%,respectively.During the rolling process,it was found that the pulsed current promoted the dynamic recrystallization of the ultra-thin strip,reduced its dislocation density and deformation resistance,and promoted the coordinated deformation of the metal.

Microstructural Evolutions and Mechanical Properties of Energetic Al_(1) (TiZrNbTaMoCr)_(15) High-Entropy Alloys

The present study focuses on investigating the microstructural evolutions and mechanical properties of energetic Al_(1)(TiZrNbTaMoCr)_(15) refractory high-entropy alloys with the different heat treatments at low Al content state. It is found that even with a reduction in the Al content, the strength of these alloys remains unaffected at room temperature and high temperature, while the plasticity improves significantly. In particular, the coherent BCC/B_(2) microstructure with needle-like B_(2) nanoprecipitates dispersed into the BCC matrix is formed in 873 K-aged Al_(1)Ti_(6)Zr_(2)Nb_(3)Ta_(3)Mo_(0.5)Cr_(0.5) alloy. Therefore, this alloy exhibits the highest compression yield strength (σ_(YS) = 1333 and 717 MPa) at room temperature and 1073 K, respectively. After 973 K-aged, the coherent BCC/B_(2) microstructure underwent destabilization, and the B_(2) phase transforms into the brittle Zr5Al3 phase which then coarsens and dominates the microstructure of S3-AlTa_(3) alloy after 1073 K-aged. Moreover, these current alloys exhibit exceptionally high theoretical exothermic enthalpy (ΔH), surpassing 11606 J·g^(−1), which highlights their significant potential as innovative high-performance energetic structural materials.

Majorana zero mode assisted spin pumping

We present a theoretical investigation of Majorana zero mode(MZM)assisted spin pumping which consists of a quantum dot(QD)and two normal leads.When the coupling between the MZM and the QD is absent,d.c.pure spin current can be excited by a rotating magnetic field where low energy spin down electrons are flipped to high energy spin up electrons by absorbing photons.However,when the coupling is turned on,the d.c.pure spin current vanishes,and an a.c.charge current emerges with its magnitude independent of the coupling strength.We reveal that this change is due to the formation of a highly localized MZM assisted topological Andreev state at the Fermi level,which allows only the injection of electron pairs with opposite spin into the QD.By absorbing or emitting photons,the electron pairs are separated to opposite spin electrons,and then return back to the lead again,generating an a.c.charge current without spin polarization.We demonstrate the switching from d.c.pure spin current to a.c.charge current based on both Kitaev model and a more realistic topological superconductor nanowire.Although this switching can also be induced by partially separated Andreev bound state(ps-ABS)in the topological trivial phase,it is extremely unstable and highly sensitive to the Zeeman field,which is different from the switching induced by MZM.Our result suggests that quantum spin pumping may be a feasible local transport method for detecting the presence of MZMs at the ends of a superconducting nanowire.

Divergent synthesis of aryl amines and dihydroquinazolinones via electrochemistry-enabled rhodium-catalyzed C–H functionalization

Electrochemistry-enabled rhodium-catalyzed C–H amination and amination cyclization of arene assisted by a weakly coordinating amide have been reported. Additionally, aryl amines and dihydroquinazolinones could be obtained selectively by controlling the electric current. Mechanistic studies suggested that the amination reaction likely involves an electrochemical oxidation-induced reductive elimination of a high valent rhodium intermediate, which led to the amination reaction even proceeding smoothly at room temperature.

平行成对电解促进的不对称催化:同时合成醛/芳基溴化物和手性醇

金属催化的不对称电还原偶联已成为有机合成的强有力工具,但是这类反应通常需要牺牲试剂或者牺牲阳极来获得电中性。同时利用阳极和阴极作为工作电极可以很好地解决该问题,然而也面临着诸多挑战:(1)完美匹配阳极氧化和阴极还原反应的电位和速率:(2)精确控制金属氧化态和对映选择性:(3)底物与底物/产物之间的副反应将降低该反应的效率:本文作者开发了一种平行成对电解(PPE)促进的不对称催化新模式,在未分隔的电解池中,利用阳极和阴极分别氧化和还原醇和酮,这两个底物最终同时以较高的产率和对映选择性转化为相应的醛和手性叔醇,除此之外,这种镍催化的不对称还原偶联可以很好地匹配(杂)芳烃的阳极氧化C-H键溴化。该方案为有机电化学的不对称合成提供了新思路。

Size and Dynamics of Ring Polymers under Different Topological Constraints

The impact of ring polymer length N and the influence of interchain and intrachain interactions on the size and dynamic behaviors of ring polymers,including the structural relaxation time τ_(R) and self-diffusion coefficient D,remain poorly understood at present due to a lack of systematic studies with relatively large N values.This work addressed this issue by applying dynamic Monte Carlo simulations with independently tuned interchain and intrachain interactions to investigate the size and dynamics of the ring melts with chain lengths over a wide range of 0.2N_(e)≤N≤80N_(e)(N_(e) is the entanglement length of corresponding linear chains)under different topological constraints,including all-crossing and intercrossing systems.We found that it was inappropriate to treat the unknotting constraint free energy of the ring chains in the melts as the free energy contributed by the excluded volume interactions of polymers in a good solvent.Scaling exponents of 2.5 and 1.5 reflecting the Ndependence of τ_(R) were obtained for long ring chains in non-crossing and intra-crossing systems,respectively,suggesting that the ring chains behaved as individual clusters and exhibited Zimm-like dynamics in intra-crossing systems.A single scaling exponent of-2 reflecting the Ndependence of D was obtained for ring chains in non-crossing and intra-crossing systems,indicating that the intrachain constraints affected only the value of D,and had little influence on the scaling relationship between D and N.Furthermore,the extended Stokes-Einstein relation broke down for the ring chains in the non-crossing and intra-crossing systems because the structural relaxation and translational diffusion were decoupled for the short ring systems,while both the translational diffusion and rotational relaxations,as well as diffusion at short and long time scales,were decoupled for long ring systems.

Polymer Translocation

The translocation of a polymer through a pore that is much smaller than its size is a fundamental and actively researched topic in polymer physics.An understanding of the principles governing polymer translocation provides important guidance for various practical applications,such as the separation and purification of polymers,nanopore-based single-molecule deoxyribonucleic acid/ribonucleic acid(DNA/RNA)sequencing,transmembrane transport of DNA or RNA,and infection of bacterial cells by bacteriophages.The past several decades have seen great progresses on the study of polymer translocation.Here we present an overview of theoretical,experimental,and simulational stduies on polymer translocation,focusing on the roles played by several important factors,including initial polymer conformations,external fields,polymer topology and architectures,and confinement degree.We highlight the physical mechanisms of different types of polymer translocations,and the main controversies about the basic rules of translocation dynamics.We compare and contrast the behaviors of force-induced versus flow-induced translocations and the effects of unknotted versus knotted polymers.Finally,we mention several opportunities and challenges in the study of polymer translocation.

The Role of Processing Solvent on Morphology Optimization for Slot-Die Printed Organic Photovoltaics

The morphology manipulation of the active layers is important for improving the performance of organic photovoltaics(OPVs).The choice of processing solvent has great impact on the crystallization and phase separation during film formation,since solvent properties,including solvent effect on molecular crystallization,boiling point,and interaction parameters,can directly change the evolution pathways associated with thermodynamics and kinetics.Therefore,revealing the underlying solvent-regulated morphology mechanism is potential to provide guiding strategies for device optimization.In this study,chloroform,chlorobenzene,and toluene are used to process PM6:Y6 blends by slot-die printing to fabricate OPV devices.The chloroform printed film forms a fibrillar network morphology with enhanced crystallization,facilitating exciton dissociation,charge transport and extraction,resulting in an optimal power conversion efficiency of 16.22%.However,the addition of the additive chloronaphthalene in chloroform solution leads to over-crystallization of Y6,and thus,increasing domain size that exceeds the exciton diffusion length,resulting in lower device efficiency.In addition,both the chlorobenzene and toluene suppress the crystallization of Y6,which drastically decreased short-circuit current and fill factor.These results demonstrate the important role of processing solvent in dictating film morphology,which critically connects with the resultant printed OPV performance.