Evolution of the porous structure for phosphoric acid etching carbon as cathodes in Li–O_(2) batteries:Pyrolysis temperature-induced characteristics changes

Although biomass-derived carbon(biochar)has been widely used in the energy field,the relation between the carbonization condition and the physical/chemical property of the product remains elusive.Here,we revealed the carbonization condition's effect on the morphology,surface property,and electrochemical performance of the obtained carbon.An open slit pore structure with shower-puff-like nanoparticles can be obtained by finely tuning the carbonization temperature,and its unique pore structure and surface properties enable the Li–O_(2) battery with cycling longevity(221 cycles with 99.8%Coulombic efficiency at 0.2 mA cm^(−2) and controlled discharge–charge depths of 500 mAh g^(−1))and high capacity(16,334 mAh g^(−1) at 0.02 mA cm^(−2)).This work provides a greater understanding of the mechanism of the biochar carbonization procedure under various pyrolysis conditions,paving the way for future study of energy storage devices.

Application and Progress of Confinement Synthesis Strategy in Electrochemical Energy Storage

Designing high-performance nanostructured electrode materials is the current core of electrochemical energy storage devices.Multi-scaled nanomaterials have triggered considerable interest because they effectively combine a library of advantages of each component on different scales for energy storage.However,serious aggregation,structural degradation,and even poor stability of nanomaterials are well-known issues during electrochemically driven volume expansion/contraction processes.The confinement strategy provides a new route to construct controllable internal void spaces to avoid the intrinsic volume effects of nanomaterials during the reaction or charge/discharge process.Herein,we discuss the confinement strategies and methods for energy storage-related electrode materials with a one-dimensional channel,two-dimensional interlayer,and three-dimensional space as reaction environments.For each confinement environment,the correlation between the confinement condition/structure and the behavioral characteristics of energy storage devices in the scope of metal-ion batteries(e.g.,Li-ion,Na-ion,K-ion,and Mg-ion batteries),Li-S batteries(LSBs),Zn-air batteries(ZIBs),and supercapacitors.Finally,we discussed the challenges and perspectives on future nanomaterial confinement strategies for electrochemical energy storage devices.

Double spatial confinement on ruthenium nanoparticles inside carbon frameworks as durable catalysts for a quasi-solid-state Li–O_(2) battery

The rational design of large-area exposure,nonagglomeration,and longrange dispersion of metal nanoparticles(NPs)in the catalysts is critical for the development of energy storage and conversion systems.Little attention has been focused on modulating and developing catalyst interface contact engineering between a carbon substrate and dispersed metal.Here,a highly dispersed ultrafine ruthenium(Ru)NP strategy by double spatial confinement is proposed,that is,incorporating directed growth of metal–organic framework crystals into a bacterial cellulose templating substrate to integrate their respective merits as an excellent electrocatalytic cathode catalyst for a quasi-solid-state Li–O_(2) battery.The porous carbon matrix with highly dispersed ultrafine Ru NPs is well designed and used as cathode catalysts in a Li–O_(2) battery,demonstrating a high discharge areal capacity of 6.82 mAh cm^(–2) at 0.02 mA cm^(–2),a high-rate capability of 4.93 mAh cm^(–2) at 0.2 mA cm^(–2),and stable discharge/charge cycling for up to 500 cycles(2000 h)with low overpotentials of~1.4 V.This fundamental understanding of the structure–performance relationship demonstrates a new and promising approach to optimize highly efficient cathode catalysts for solid-state Li–O_(2) batteries.

Single-Molecule Confinement Induced Intrinsic Multi-Electron Redox-Activity to Enhance Supercapacitor Performance

Aggregation of polyoxometalates(POM)is largely responsible for the reduced performance of POM-based energy-storage systems.To address this challenge,here,the precise confinement of single Keggin-type POM molecule in a porous carbon(PC)of unimodal super-micropore(micro-PC)is realized.Such precise single-molecule confinement enables sufficient activity center exposure and maximum electron-transfer from micro-PC to POM,which well stabilizes the electron-accepting molecules and thoroughly activates its inherent multi-electron redox-activity.In particular,the redox-activities and electron-accepting properties of the confined POM molecule are revealed to be super-micropore pore size-dependent by experiment and spectroscopy as well as theoretical calculation.Meanwhile,the molecularly dispersed POM molecules confined steadily in the“cage”of micro-PC exhibit unprecedented large-negative-potential stability and multiple-peak redox-activity at an ultra-low loading of~11.4 wt%.As a result,the fabricated solid-state supercapacitor achieves a remarkable areal capacitance,ultrahigh energy and power density of 443 mF cm^(-2),0.12 mWh cm^(-2)and 21.1 mW cm^(-2),respectively.This work establishes a novel strategy for the precise confinement of single POM molecule,providing a versatile approach to inducing the intrinsic activity of POMs for advanced energy-storage systems.

A petunia transcription factor, PhOBF1, regulates flower senescence by modulating gibberellin biosynthesis

Flower senescence is commonly enhanced by the endogenous hormone ethylene and suppressed by the gibberellins(GAs)in plants.However,the detailed mechanisms for the antagonism of these hormones during f lower senescence remain elusive.In this study,we characterized one up-regulated gene PhOBF1,belonging to the basic leucine zipper transcription factor family,in senescing petals of petunia(Petunia hybrida).Exogenous treatments with ethylene and GA3 provoked a dramatic increase in PhOBF1 transcripts.Compared with wild-type plants,PhOBF1-RNAi transgenic petunia plants exhibited shortened f lower longevity,while overexpression of PhOBF1 resulted in delayed flower senescence.Transcript abundances of two senescence-related genes PhSAG12 and PhSAG29 were higher in PhOBF1-silenced plants but lower in PhOBF1-overexpressing plants.Silencing and overexpression of PhOBF1 affected expression levels of a few genes involved in the GA biosynthesis and signaling pathways,as well as accumulation levels of bioactive GAs GA1 and GA3.Application of GA3 restored the accelerated petal senescence to normal levels in PhOBF1-RNAi transgenic petunia lines,and reduced ethylene release and transcription of three ethylene biosynthetic genes PhACO1,PhACS1,and PhACS2.Moreover,PhOBF1 was observed to specifically bind to the PhGA20ox3 promoter containing a G-box motif.Transient silencing of PhGA20ox3 in petunia plants through tobacco rattle virus-based virus-induced gene silencing method led to accelerated corolla senescence.Our results suggest that PhOBF1 functions as a negative regulator of ethylene-mediated f lower senescence by modulating the GA production.

Vehicle Motion Prediction at Intersections Based on the Turning Intention and Prior Trajectories Model

Intersections are quite important and complex traffic scenarios,where the future motion of surrounding vehicles is an indispensable reference factor for the decision-making or path planning of autonomous vehicles.Considering that the motion trajectory of a vehicle at an intersection partly obeys the statistical law of historical data once its driving intention is determined,this paper proposes a long short-term memory based(LSTM-based)framework that combines intention prediction and trajectory prediction together.First,we build an intersection prior trajectories model(IPTM)by clustering and statistically analyzing a large number of prior traffic flow trajectories.The prior trajectories model with fitted probabilistic density is used to approximate the distribution of the predicted trajectory,and also serves as a reference for credibility evaluation.Second,we conduct the intention prediction through another LSTM model and regard it as a crucial cue for a trajectory forecast at the early stage.Furthermore,the predicted intention is also a key that is associated with the prior trajectories model.The proposed framework is validated on two publically released datasets,next generation simulation(NGSIM)and INTERACTION.Compared with other prediction methods,our framework is able to sample a trajectory from the estimated distribution,with its accuracy improved by about 20%.Finally,the credibility evaluation,which is based on the prior trajectories model,makes the framework more practical in the real-world applications.

On Weighted L^p-Approximation by Weighted Bernstein-Durrmeyer Operators

In the present paper, we establish direct and converse theorems for weight-ed Bernstein-Durrmeyer operators under weighted L^p-norm with Jacobi weight w（x）=x^a（1-x）β.All the results involved have no restriction a,β〈1-1/p,which indicates that the weighted Bemstein-Durrmeyer operators have some better approxi- mation properties than the usual Bernstein-Durrmeyer operators.

Exploring Generic Features in China-Africa Corporate Advertising:A Critical Genre Analysis

China-Africa corporate advertising is emerging as an example of the corporate advertising genre in response to the specific rhetorical context of China-Africa win-win cooperation.Drawing on Bhatia’s Critical Genre Analysis(2017),this study explores the text-internal and text-external generic features of China-Africa corporate advertising by analyzing 50 collected samples.The analysis of text-internal prominence shows that China-Africa corporate advertising is unique in its frequent use of win-win-oriented and sector-dependent technical lexicons to indicate the promotional intent.It is also found that move structures vary across different sub-types of ChinaAfrica corporate advertising.Text-externally,the findings reveal a mixture of different discourses within the discursive space of China-Africa corporate advertising.In addition,the results suggest that Chinese companies invest more rhetorical efforts in enhancing the China-Africa community than African counterparts who tend to perceive China-Africa cooperation as the main avenue to attract worldwide partnerships.The findings have some practical implications for discourse construction in the Belt and Road Initiative context and shed light on the evolving nature of advertising discourse,particularly in the China-Africa win-win business context.

Burning magnesium in carbon dioxide for highly effective phosphate removal

Magnesium oxide was found to have high-phosphate-affinity as an effective component to enhance the phosphate removal ability of common adsorbent materials.However,the currently prepared MgO-based hybrid adsorbents by conventional methods still suffer from the limited low loading of MgO and inferior removal performances,much far away from practical application.In this study,an ingenious carbon coated MgO nanocomposite is designed by directly burning magnesium in CO_(2),a well-known textbook reaction.X-ray diffraction analysis,scanning electron microscope and aberration-corrected high-resolution transmission electron microscope demonstrate the sample is well prepared.Consequently,the high content of nanosized MgO combined with defect-rich carbon layer brings unprecedented phosphate removal capacity of 1135.0 mg/g,removal rate of 99% and benign compatibility with coexisting anions and solution pH.Furthermore,the removal mechanism is also investigated in detail by characterizing the sample before and after adsorption.

On Weighted Approximation by Modified Bernstein Operators for Functions with Singularities

Della Vecchia et al. （see [2]） introduced a kind of modified Bernstein operators which can be used to approximate functions with singularities at endpoints on [0,1]. In the present paper, we obtain a kind of pointwise Stechkin-type inequalities for weighted approximation by the modified Bemsetin operators.

Chemical vapor deposition synthesis of intrinsic van der Waals ferroelectric SbSI nanowires

Intrinsic ferroelectric materials play a critical role in the development of high-density integrated device. Despite some two-dimensional (2D) ferroelectrics have been reported, the research on one-dimensional (1D) intrinsic ferroelectric materials remains relatively scare since 1D atomic structures limit their van der Waals (vdW) epitaxy growth. Here, we report the synthesis of 1D intrinsic vdW ferroelectric SbSI nanowires via a confined-space chemical vapor deposition. By precisely controlling the partial vapor pressure of I2 and reaction temperature, we can effectively manipulate kinetics and thermodynamics processes, and thus obtain high quality of SbSI nanowires, which is determined by Raman spectroscopy and high-resolution scanning transmission electron microscopy characterizations. The ferroelectricity in SbSI is confirmed by piezo-response force microscopy measurements and the ferroelectric transition temperature of 300 K is demonstrated by second harmonic generation. Moreover, the in-plane polarization switching can be maintained in the thin SbSI nanowires with a thickness of 20 nm. Our prepared 1D vdW ferroelectric SbSI nanowires not only enrich the vdW ferroelectric systems, but also open a new possibility for high-power energy storage nanodevices.

From surface loading to precise confinement of polyoxometalates for electrochemical energy storage

Because of abundant redox activity,broad tunability,and specific atomic structure,polyoxometalates(POMs or POM)clusters have attracted burgeoning interests in electrochemical especially energy stor-age fields.Nevertheless,due to the high solubility and fully oxidized state,they often suffer from elec-trically insulation as well as chemical and electrochemical instability.Traditional noncovalent loading or covalent grafting of POMs on conductive substrates have been successfully performed to overcome this problem.However,severe shedding or agglomeration of POMs arising from weak interactions with substrates or excessive entrapment or weak destruction in conductive supports cause significantly re-duced availability and stability.To this end,precise confinement of POMs into conductive supports has been tried to improve their dispersibility and stability.Herein,recent progress of PoMs from surface loading to precise confinement in the electrochemistry energy storage field is reviewed.Firstly,we il-lustrate the typical non-confinement methods(viz.covalent and non-covalent)for supported POMs in energy storage applications.Secondly,different strategies for precise confinement of PoMs in organic and inorganic materials for related applications are also discussed.Finally,future research directions and opportunities for confined POMs,and derived ultrafine nanostructures are also proposed.This re-view seeks to point out future research directions of supported PoMs in the electrochemistry-related fields.

Cry1Ah蛋白标准物质候选物的制备与纯化（英文）

随着转基因技术的迅猛发展,转基因产品的安全性受到了广泛关注。转基因检测用有证标准物质在确保转基因产品定性、定量检测结果的可比性和可追溯性方面发挥着重要作用。但转基因蛋白质标准物质的开发相对缓慢,其中一个难点是制备高纯度的转基因蛋白质候选物。苏云金芽胞杆菌Bacillus thuringiensis cry1Ah1基因因其对亚洲玉米螟等鳞翅目害虫有很好的杀虫活性,已用于转基因抗虫作物的研制,并获得具有较好抗虫性状的转基因株系。为了研发Cry1Ah蛋白有证标准物质,亟需建立其制备及纯化体系。文中优化了利用Bt表达系统制备Cry1Ah蛋白的体系,利用离子交换色谱法和排阻色谱法逐级纯化的方法,获得了高纯度的Cry1Ah蛋白(排阻色谱纯度:99.6%)。生物活性测定结果表明,纯化的Cry1Ah蛋白与原毒素对小菜蛾Plutella xylostella的杀虫活性没有显著差异。最后使用Edman降解法和质谱法确定了Cry1Ah蛋白活化后的氨基酸序列。综上所述,获得的Cry1Ah纯蛋白可用于蛋白质标准物质的研制。

流程图支持下的计算思维培养实践研究

当前K-12阶段的计算思维培养中缺乏一种思维加工的辅助工具,用以记录并显性化呈现学习者的思维从识别问题到形成方案的全过程。这使得教学很难深入思维发展的细节部分,做出有针对性的指导和评价,使得计算思维培养的效果存在局限。本文基于工程设计的问题解决视角,从问题识别与分解、系统抽象与方案设计优化、方案实现和问题迁移四个阶段探讨了流程图支持下的计算思维教学过程,并对来自上海某中学6年级~8年级的19名学生开展了一个学期的教学实践,结合流程图评价、能力前后测、作品评价、作品问答反馈四种方式,从认知和操作层面以及非认知层面对他们的计算思维发展进行评价。实验结果初步显示,学生的计算思维在流程图的支持下得到了有效提升,并且流程图得分高和流程图得分提升幅度大的学生其提升效果更加显著。

A Unified Dynamic Control Method for a Redundant Dual Arm Robot

Compared to single arm robot system, dual arm robot has the ability of performing human-like dexterity and cooperation. Dual arm cooperative operation has attracted more and more attention in industrial applications, such as in assembly of complex parts, manufacturing tasks and handling objects. A unified dynamic control method, which is divided into three modes, namely, independent mode, dependent mode, and half dependent mode, is proposed for a redundant dual arm robot with focus on the movement and force of the desired task being operated. Attention is devoted to develop a unified formulation of the above three modes. In addition, a closed form of inverse kinematic solution instead of numerical integration approach is proposed with the aim to guarantee position accuracy. Different from traditional dynamic controllers, where the independent redundancy resolution is obtained based on particular velocity or acceleration levels, here the two dynamic controllers are improved by combining a closed form of inverse kinematic solution with velocity and acceleration levels. Furthermore, the theoretical results of the proposed control method are validated by simulations and experiments.

Latent fingerprint enhancement on conductive substrates using electrodeposition of copper

We presented a novel method for the development of a latent fingerprint by selective electrodeposition of a copper thin film from sulfate solution onto the conductive substrate between fingerprint ridges to generate a negative image of the fingerprint deposit. After optimizing the parameters(deposition time, deposition potential, and copper concentration), the preferential electrodeposition of copper films allowed latent fingerprints on six kinds of conductive surfaces(indium/tin oxide-coated glass, silver sheet, platinum sheet, gold sheet, copper sheet, and a stainless steel coin) to be successfully developed with high resolution. In addition, this technique could also be exploited to visualize latent fingerprints on rough and dirty surfaces. The quality of the developed fingerprints was estimated visually and the morphology of the copper film was characterized by field emission scanning electron microscopy.

Effects of multi-sequence combination forces on creep characteristics of bales during wheat harvesting

During the baling operation,the wheat stalks are subjected to various mechanisms in the baler and the main form is compression.After the wheat stem is forced by a combination of the threshing cylinder,it needs to be formed under the action of straw baler and meet transport requirements.This paper mainly studies the properties of wheat stalks when baling,and proposes the application of the creep after-effect theory during the baling process.The tension-compression tester was used to perform a 50 mm stalk mechanical test,50 mm stalk static pressure test,35 mm×40 mm×50 mm stalk module static pressure test and bale static pressure test.The measured elastic modulus of the stem sample was 7.59 MPa,and the elastic modulus of the inner core of the stem was 8.24 MPa.The return curve of the single stalk and the bale is consistent with the initial creep and steady-state creep in the creep after-effect theory.A logarithmic function was used for fitting of the first stage with coefficient of determination R2=0.8364,and a linear function was used for fitting of the second stage with coefficient of determination R2=0.9921.The high water content static pressure test suggests that the load in the loading direction is the coupled load of the working load of the hydraulic cylinder and the internal stress of the bale.When harvesting wheat stalks with high moisture content,the density parameter of the bale can be appropriately increased while the load parameter of the hydraulic cylinder can be considered unchanged or even reduced.The adjustment of density and load can still ensure the forming quality of the bale.

Characterization of tub_4^(P287L), a β-tubulin mutant,revealed new aspects of microtubule regulation in shade

When sun plants, such as Arabidopsis thaliana, are under canopy shade, elongation of stems/petioles will be induced as one of the most prominent responses. Plant hormones mediate the elongation growth. However, how environmental and hormonal signals are translated into cell expansion activity that leads to the elongation growth remains elusive. Through forward genetic study, we identi-fied shade avoidance2 (sav2) mutant, which contains a P287L mutation in b-TUBULIN 4. Cortical microtubules (cMTs) play a key role in anisotropic cell growth. Hypocotyls of sav2 are wild type-like in white light, but are short and highly swollen in shade and dark. We showed that shade not only induces cMT rearrangement, but also affects cMT stability and dynamics of plus ends. Even though auxin and brassinosteroids are required for shade-induced hypocotyl elongation, they had little effect on shade-induced rearrangement of cMTs. Blocking auxin transport suppressed dark phenotypes of sav2, while overexpressing EB1b-GFP, a microtubule plus-end binding protein, rescued sav2 in both shade and dark, suggesting that tub4P287L represents a unique type of tubulin mutation that does not affect cMT function in supporting cell elongation, but may affect the ability of cMTs to respond properly to growth promoting stimuli.

Drag derived altitude aided navigation method

The navigation problem of the lifting reentry vehicles has attracted much research interest in the past decade. This paper researches the navigation in the blackout zone during the reentry phase of the aircraft, when the communication signals are attenuated and even interrupted by the blackout zone. However, when calculating altitude, a pure classic inertial navigation algorithm appears imprecise and divergent. In order to obtain a more precise aircraft altitude, this paper applies an integrated navigation method based on inertial navigation algorithms, which uses drag derived altitude to aid the inertial navigation during the blackout zone. This method can overcome the shortcomings of the inertial navigation system and improve the navigation accuracy. To further improve the navigation accuracy, the applicable condition and the main error factors, such as the atmospheric coefficient error and drag coefficient error are analyzed in detail. Then the damping circuit design of the navigation control system and the damping coefficients determination is introduced. The feasibility of the method is verified by the typical reentry trajectory simulation, and the influence of the iterative times on the accuracy is analyzed. Simulation results show that iterative three times achieves the best effect.

Sub-nanopores-containing N,O-codoped porous carbon from molecular-scale networked polymer hydrogel for solid-state supercapacitor

A template-free carbonization-activation route is developed to fabricate sub-nanopore-containing porous carbon by using a novel polypyrrole(PPy)hydrogel as a precursor.This design of PPy hydrogel precursor containing molecular-scale grids(diameter~2.0 nm)allows for homogeneous N,O-codoping into the porous carbon scaffold during the pyrolysis process.A subsequent activation step produces activated porous carbons(APCs)with tailored pore structures,which renders the APCs abundant subnanopores on their surface to increase the specific capacitance as extra capacitance sites.Coupled with large specific surface area and abundant heteroatoms,the optimized APC4/1 displays excellent specific capacitance of 379 F/g for liquid-state supercapacitor and 230 F/g for solid-state supercapacitor.The solid-state supercapacitor shows a high energy density of 22.99 Wh/kg at power density of 420 W/kg,which is higher than most reported porous carbon materials and satisfy the urgent requirements of elementary power source for electric vehicles.Moreover,this method can be easily modified to fabricate sub-nanopore-containing porous carbons with preferred structures and compositions for many applications.