定制电解液或隔膜实现锂离子各向异性输运从而抑制枝晶生长:相场模拟研究

电池内部不可控的枝晶生长问题严重地影响着电池的循环性能和安全性能,这对于锂金属电池的实际应用是一个严峻的挑战。尽管已有较多的实验和理论研究工作聚焦于电极间锂离子各向异性输运特性对枝晶形貌的影响,但仍有一些开放性的问题有待进一步研究,例如,如何将枝晶生长的动态演变与电解液性质、电势分布或隔膜多孔结构诱导的锂离子各向异性输运关联起来。我们通过将锂离子在电解液中的扩散系数(D_(L))表示为二阶张量的形式并进行相场模拟,发现D_(yy):D_(xx)比值的增加,以及电势诱导的电极/电解液界面锂离子快速扩散层均可以降低界面处锂离子浓度梯度和电势梯度,从而减弱枝晶生长的驱动力。我们还发现隔膜基体与y方向之间夹角的增大也会显著促进电解质中的锂离子各向异性输运特性,以利于抑制枝晶生长。籍此本文提出设计D_(yy):D_(xx)=10:1的电解液和基体倾斜角为arctan(0.5)的隔膜用于锂金属电池。该相场研究有望为设计具有抑制枝晶能力的电解质或隔膜提供指导。

Optimization for sound insulation of a sandwich plate with a corrugation and auxetic honeycomb hybrid core

A sandwich plate with a corrugation and auxetic honeycomb hybrid core is constructed,and its sound insulation and optimization are investigated.First,the motion governing equation of the sandwich plate is established by the third-order shear deformation theory(TSDT),and then combined with the fluid-structure coupling conditions,and the sound insulation is solved.The theoretical results are validated by COMSOL simulation results,and the effects of the structural parameter on the sound insulation are analyzed.Finally,the standard genetic algorithm is adopted to optimize the sound insulation of the sandwich plate.

3D printed fiber-optic nanomechanical bioprobe

Ultrasensitive nanomechanical instruments,e.g.atomic force microscopy(AFM),can be used to perform delicate biomechanical measurements and reveal the complex mechanical environment of biological processes.However,these instruments are limited because of their size and complex feedback system.In this study,we demonstrate a miniature fiber optical nanomechanical probe(FONP)that can be used to detect the mechanical properties of single cells and in vivo tissue measurements.A FONP that can operate in air and in liquids was developed by programming a microcantilever probe on the end face of a single-mode fiber using femtosecond laser two-photon polymerization nanolithography.To realize stiffness matching of the FONP and sample,a strategy of customizing the microcantilever’s spring constant according to the sample was proposed based on structure-correlated mechanics.As a proof-of concept,three FONPs with spring constants varying from 0.421 N m^(−1)to 52.6 N m^(−1)by more than two orders of magnitude were prepared.The highest microforce sensitivity was 54.5 nmμN^(−1)and the detection limit was 2.1 nN.The Young’s modulus of heterogeneous soft materials,such as polydimethylsiloxane,muscle tissue of living mice,onion cells,and MCF-7 cells,were successfully measured,which validating the broad applicability of this method.Our strategy provides a universal protocol for directly programming fiber-optic AFMs.Moreover,this method has no special requirements for the size and shape of living biological samples,which is infeasible when using commercial AFMs.FONP has made substantial progress in realizing basic biological discoveries,which may create new biomedical applications that cannot be realized by current AFMs.

Dynamic reconstructuring of CuS/SnO_(2)-S for promoting CO_(2) electroreduction to formate

As the“emission peak and carbon neutrality peak”are proceeding all over the world,CO_(2) electroreduction is studied extensively as it is a powerful way to transform CO_(2)into value-added products.The earthabundant Sn-based materials and copper sulfides as electrochemical catalysts have shown activity for generating formate from CO_(2) electroreduction.Herein,the composite of CuS and S-doped SnO_(2)(CuS/SnO_(2)-S)was synthesized by a redox reaction under room temperature.The unique structural reconstruction of CuS/SnO_(2)-S nanoparticles to Cu/Sn/Cu_(6.26)Sn_(5) nanowires decreases the energy barrier of the adsorption of CO_(2),and increases the adsorption of^(*)H,primarily suppressing the competing reaction of hydrogen evolution reaction(HER).As a result,at-0.8 V vs.RHE,it reaches an electrochemical CO_(2)-to-formate conversion with a Faradaic efficiency(FE)of 84.9%at a yield of 8860μmol h-1cm^(-2) under a partial current density of~18.8 mA cm^(-2) in an H-type reactor.This study provides significant insight into the structural evolution of the CuSn sulfides and the mechanism of formate formation.

Effect of light and nutrients on interspecific interactions between submerged macrophytes:implications for restoration of multispecies aquatic vegetation in eutrophic lakes

Constructing multispecies submerged vegetation systems and maintaining stable seasonal succession is crucial for restoring shallow eutrophic lakes.However,little is known about the interactions between successional and existing species of different growth forms,particularly under the low light and high nutrient conditions of eutrophic lakes.We measured the functional traits of mature Vallisneria natans(Lour.)Hara plants and Potamogeton crispus L.shoots in monoculture and mosaic patterns under different light and nutrient conditions.The effect of light on functional traits of the submerged macrophyte species was more significant than that of nutrients,but the reverse was true for P.crispus biomass allocation.Moreover,interspecific interactions affected only the submerged macrophytes under the low light condition and varied with species.Specifically,the interaction of P.crispus to V.natans was biased towards competition,while the interaction of V.natans to P.crispus was converted from facilitation to competition by eutrophication,particularly in the homogenous mosaic growth pattern.This study demonstrates that sufficient light is a prerequisite and patch planting is an effective means to form a multispecies submerged vegetation system.In addition,we emphasize that the coexistence of eutrophication and low light will likely result in a competition between submerged macrophytes thus simplifying the vegetation,even if their growth forms and growing seasons are different.These findings help explain the collapse of multispecies submerged vegetation and guide the restoration of aquatic plants in eutrophic lakes.

Influence of the position relationship between gas–liquid interface and laser focus on plasma evolution characteristics in jet LIBS technology

In order to understand the characteristics of breakdown process,plasma evolution and spectral emission in liquid jets laser-induced breakdown spectroscopy methods under the influence of the position variation between laser focus and gas–liquid interface,this work takes the plasma generated by laser-induced liquid jets as the object of study and discusses the changes in the spatial and temporal evolution characteristics and spectral radiation of the plasma when the position parameters between the laser focal point and the gas–liquid interface are different.The initial breakdown position is always between the front interface and the focus when the laser focus moves along the vertical direction of the interface,forming a phenomenon like’interface effect’.The relationship between laser pulse energy and breakdown probability exhibits a law similar to a‘hysteresis curve’in the study of breakdown threshold.In this work,plasma with smaller size,rounder shape,stronger radiation,higher temperature,and higher density can be produced when the focus position is in the liquid column 0.2 mm away from the front interface.Simultaneously,the spectral signal intensity and signal-to-back ratio of the characteristic peaks of target elements in water reach maximum values,and the spectral signal becomes more stable(relative standard deviation value reaches 2%).The Ca element’s ion radiation at 393.366 nm and atomic radiation at 422.673 nm are studied using narrow-band filtering imaging and time-space resolution spectroscopy.The findings demonstrate that the laws of ion and atomic radiation are not perfectly consistent in space and time.

Encrypted optical fiber tag based on encoded fiber Bragg grating array

Optical fibers are typically used in telecommunications services for data transmission,where the use of fiber tags is essential to distinguish between the different transmission fibers or channels and thus ensure the working functionality of the communication system.Traditional physical entity marking methods for fiber labeling are bulky,easily confused,and,most importantly,the label information can be accessed easily by all potential users.This work proposes an encrypted optical fiber tag based on an encoded fiber Bragg grating(FBG)array that is fabricated using a point-by-point femtosecond laser pulse chain inscription method.Gratings with different resonant wavelengths and reflectivities are realized by adjusting the grating period and the refractive index modulations.It is demonstrated that a binary data sequence carried by a fiber tag can be inscribed into the fiber core in the form of an FBG array,and the tag data can be encrypted through appropriate design of the spatial distributions of the FBGs with various reflection wavelengths and reflectivities.The proposed fiber tag technology can be used for applications in port identification,encrypted data storage,and transmission in fiber networks.

绿色设计理念在医疗建筑中的应用分析

将绿色设计理念应用于医疗建筑当中,不仅可以节约医院建设和运营中消耗的资源,保护环境,还可以促使医院的功能进一步改善。为了充分地融入设计绿色设计理念,论文在充分了解绿色建筑设计特点和原则的前提下,分析绿色建筑理念在医疗建筑设计中的实际应用,以便为相关建筑设计活动的优化提供参考。

BIM技术在建筑工程安全管理中的应用

随着城市化建设的进程逐渐加快,建设项目规模不断扩大,建筑工程安全问题受到了人们广泛的关注。BIM技术是一种新型的建筑工程应用技术,通过自身的优势可以在工程安全管理工作中发挥巨大的作用。在实际的施工过程中,BIM技术可以帮助现场管理人员和施工人员及时发现现场存在的安全隐患,履行管理人员的相关职责,从而保障施工质量以及施工期间的安全问题。

Transient Heat Transfer Study of Direct Contact Condensation of Steam in Spray Cooling Water

We conducted a transient experimental investigation of steam–water direct contact condensation in the absence of noncondensible gas in a laboratory-scale column with the inner diameter of 325 mm and the height of 1045 mm. We applied a new analysis method for the steam state equation to analyze the molar quantity change in steam over the course of the experiment and determined the transient steam variation. We also investigated the influence of flow rates and temperatures ofcooling water on the efficiency ofsteam condensation. Our experimental results show that appropriate increasing of the cooling water flow rate can significantly accelerate the steam condensation. We achieved a rapid increase in the total volumetric heat transfer coefficient by increasing the flow rate of cooling water, which indicated a higher thermal convection between the steam and the cooling water with higher flow rates. We found that the temperature ofcooling water did not play an important role on steam condensation. This method was confirmed to be effective for rapid recovering ofsteam.

Analysis of Combined Natural Convection and Radiation Heat Transfer in a Partitioned Rectangular Enclosure with Semitransparent Walls

In this paper, we present a two-dimensional numerical analysis of the conjugate natural convection and radiation heat transfer in a double-space enclosure with two semitransparent walls. Two kinds of boundary conditions are considered, the rst being the isothermal process of the opaque wall, and the other the incidence of a constant radiation ux in the left semitransparent wall. The renormalization group k ε model is adopted to simulate the turbulent ow in the enclosure. To compute the radia- tion heat transfer in a semitransparent medium, the discrete ordinates model is used. We compare the behaviors of enclosures with single and double semitransparent walls and determine the di erence in the results obtained for semitransparent and opaque partitions. The results indicate that a semitransparent partition facilitates a reduction in the heat loss or obtains a higher temperature distribution. The transmittance of a semitransparent wall has a great e ect on the thermal and ow char- acteristics in an enclosure. The change of wall temperature is found to be signi cant when the thermal conductivity values range from 0.05 to 0.5 W/(m K), and to be small when ranging from 0.5 to 10 W/(m K). These conclusions are helpful for green design and energy saving in solar buildings.

Experimental Study on a Modified Wind-Solar Hybrid System

Wind-solar hybrid systems are employed extensively due to certain advantages. However, two problems exist in their application: the PV modules operate at high temperatures, particularly during summer, and low wind power cannot be utilized. To solve these two problems, a novel hybrid system is designed based on PV/thermal systems, in which PV modules are cooled with fans driven by a wind turbine. This paper studies the practicability of the novel hybrid system. First, the electrical performance of the wind turbine is compared using a fan and battery load,respectively. Second, different types and numbers of fans are tested to obtain the largest air volume. Third, the height of the air duct on the back of the PV module is optimized and the cooling effect is studied. Results show that a 24 V DC fan is more appropriate for the novel system than a 12 V DC fan, as it provides a greater air volume, and with a switch wind speed of 3.0 m/s the power of PV module shows a maximum increase of 8.0%.

Fiber Bragg Gratings in Small-Core Ge-Doped Photonic Crystal Fibers

This paper reports fiber Bragg gratings （FBGs） inscribed in a small-core Ge-doped photonic crystal fibers with a UV laser and a Talbot interferometer. The responses of such FBGs to temper- ature, strain, bending, and transverse-loading were systematically investigated. The Bragg wavelength of the FBGs shifts toward longer wavelengths with increasing temperature, tensile strain, and transverse-loading. The bending and transverse- loading properties of the FBGs are sensitive to the fiber orientations.

Lithosaphonecrus puigdemonti sp. nov. from China(Hymenoptera: Cynipidae)

A new species of Lithosaphonecrus from China, L. puigdemonti Pujade-Villar sp. nov., is described. A key to Lithosaphonecrus species is included.

Two new species in the genus Heteribalia Sakagami(Hymenoptera: Ibaliidae) from China

The genus Heteribalia Sakagami（1949） is a member of the small parasitic wasp family Ibaliidae（Hymenoptera： Cynipoidea）, and all known species of this genus are from China and its neighbouring countries. In this paper, we report two new species, Heteribalia miltopronotum sp. nov. and Heteribalia sichuanensis sp. nov., and distribution for H. divergens Maa（1949）. These new discoveries update the known distribution of this genus in China from the known east coast areas to a much more extensive region between the eastern coast and Sichuan Province in central China. A key to all known Heteribalia species is provided.

First record of an Andricus chestnut gall wasp from the Oriental Region:a new species from China(Hymenoptera:Cynipidae:Cynipini)

A new species of gall wasps, Andricus henryi Pujade-Villar, Wang ＆ Guo sp. nov. is described on Castanea henryi from China. Additionally, the first gall wasp host of Synergus castanea is mentioned. Diagnosis, distribution, and biology of this new species are included and illustrated. A species of Andricus is mentioned for the first time in a Castanea host.

Dual Mechanism and Reform Path of the Irrigation and Water Conservancy

The operating mechanism of farmland water conservancy in China was analyzed from the perspective of anthropology, and its dual mechanism characteristics and rules were exposed. The dual mechanism took different focus at different periods, thus there were some defaults. To carry out community-based water conservancy with the support of collective economy was an effective way to cope with the severe drought in the context of degraded dual mechanism.

Descriptions of two new species in the genus Linoeucoila Lin(Hymenoptera:Figitidae)from China

The genus Linoeucoila Lin is reported for the first time from China's Mainland,together with descriptions of two new species of the genus:L.huayana sp.nov.and L.laotudingzila sp.nov.

Femtosecond laser 3D printed micro objective lens for ultrathin fiber endoscope

The most important optical component in an optical fiber endoscope is its objective lens.To achieve a high imaging performance level,the development of an ultra-compact objective lens is thus the key to an ultra-thin optical fiber endoscope.In this work,we use femtosecond laser 3D printing to develop a series of micro objective lenses with different optical designs.The imaging resolution and field-of-view performances of these printed micro objective lenses are investigated via both simulations and experiments.For the first time,multiple micro objective lenses with different fields of view are printed on the end face of a single imaging optical fiber,thus realizing the perfect integration of an optical fiber and objective lenses.This work demonstrates the considerable potential of femtosecond laser 3D printing in the fabrication of micro-optical systems and provides a reliable solution for the development of an ultrathin fiber endoscope.

Hierarchical Bi/S-modified Cu/brass mesh used as structured highly performance catalyst for CO_(2) electroreduction to formate

Electrocatalytic CO_(2) reduction reaction(ECO_(2)RR)converts CO_(2) to high-value chemical products and promotes the carbon cycle.Sulfur(S)-modified copper(Cu)and bismuth(Bi)-based catalysts have been recognized as promising catalysts for ECO_(2)RR.Both of them are highly active for selective formate generation,however,their poor stability and severe competing hydrogen evolution reaction(HER)remain challenging.Herein,S-doped Cu coated with Bi(Bi/Cu-S)is developed to improve ECO_(2)RR selectivity to formate.Bi/Cu-S/brass mesh(BM)electrode material for ECO_(2)RR was prepared by electrodepositing Bi on the surface of Cu-S/BM nanowires obtained from CuS/BM after the electroreduction.The Faradaic efficiency(FE)of the formate reaches the maximum of 94.3%at-0.9 V vs.reversible hydrogen electrode(RHE)with a partial current density as high as-50.7 mA·cm^(-2) and a yield of 30.7 mmol·h^(-1)·cm^(-2) under 0.5 M KHCO_(3) electrolyte.Meanwhile,the FE of formate is higher than 90%in the voltage range of-0.8 to-1.0 V vs.RHE.It also shows good stability at-0.9 V vs.RHE with the FE of formate remaining above 93%after a 10 h reaction.Density functional theory(DFT)calculations demonstrate that the Bi/Cu-S structure promotes the adsorption of CO_(2) and effectively inhibits HER by enhancing the adsorption of^(*)H to a great extent,improving the selective conversion of CO_(2) to formate.This work deepens the understanding of the mechanism of Cu-Bi-based catalysts and S-modified Cu-based catalysts in selective ECO_(2)RR to formate,and also provides a new strategy for catalyst design.