Self-Catalyzed Rechargeable Lithium-Air Battery by in situ Metal Ion Doping of Discharge Products: A Combined Theoretical and Experimental Study

Lithium-air battery has emerged as a viable electrochemical energy technology;yet a substantial overpotential is typically observed,due to the insulating nature of the discharge product Li_(2)O_(2) that hinders the reaction kinetics and device performance.Furthermore,finite solid–solid/-liquid interfaces are formed between Li_(2)O_(2) and catalysts and limit the activity of the electrocatalysts in battery reactions,leading to inadequate electrolytic efficiency.Herein,in-situ doping of Li_(2)O_(2) by select metal ions is found to significantly enhance the lithium-air battery performance,and Co^(2+)stands out as the most effective dopant among the series.This is ascribed to the unique catalytic activity of the resulting Co-O_(x) sites towards oxygen electrocatalysis,rendering the lithium-air battery self-catalytically active.Theoretical studies based on density functional theory calculations show that structural compression occurs upon Co^(2+)doping,which lowers the energy barrier of Li_(2)O_(2) decomposition.Results from this study highlight the significance of in situ electrochemical doping of the discharge product in enhancing the performance of lithium-air battery.

依托“第二课堂”多维度开放实验室,拓展实验教学的深度和广度

实验教学是培养学生实践能力和创新能力的重要环节,如何突破课堂教学的时空限制有效实现实验资源的开放利用,是高校实验教学中心改革和建设的重要内容。本文以化学国家级实验教学示范中心(北京师范大学)为例,介绍本中心将有组织的“第二课堂活动”纳入实验教学体系,探索并创建了多层次、多维度的实验室开放模式;通过举办丰富的实验竞赛/实践活动,支持大学生开展创新创业、学科竞赛、科学研究和科普宣传等活动,为学生提供了多样化的、以自驱为主、崇尚创新的实践训练机会,从而切实发挥了实验教学中心在创新人才培养中的支撑作用和在基础教育领域的辐射和示范作用。上述举措得力、育人效果显著,值得推广借鉴。

In situ decoration of nanosized metal oxide on highly conductive MXene nanosheets as efficient catalyst for Li-O2 battery

Combining nanomaterials with complementary properties in a well-designed structure is an effective tactic to exploit multifunctional, high-performance materials for the energy conversion and storage. Nonprecious metal catalysts, such as cobalt oxide, with superior activity and excellent stability to other catalysts are widely desired. Nevertheless, the performance of CoO nanoparticles as an electrode material were significantly limit for its inferior conductivity, dissolution, and high cohesion. Herein, we grow ultrafine cobalt monoxide to decorate the interlayer and surface of the Ti3C2 Txnanosheets via a hydrothermal method companied by calcination. The layered MXenes act as the underlying conductive substrate,which not only increase the electron transfer rate at the interface but also greatly improve the electrochemical properties of the nanosized Co O particles by restricting the aggregation of CoO. The resulting CoO/Ti3C2 Txnanomaterial is applied as oxygen electrode for lithium-oxygen battery and achieves more than 160 cycles and first cycle capacity of 16,220 mAh g-1 at 100 mA g-1. This work paves a promising avenue for constructing a bi-functional catalyst by coupling the active component of a transition metal oxide(TMO) with the MXene materials in lithium-oxygen battery.

The protective effects of peptides from Chinese baijiu on AAPH-induced oxidative stress in HepG2 cells via Nrf2 signaling pathway

Antioxidant peptides have been widely reported.However,only a few reports have been published examining the antioxidant peptides derived from Chinese baijiu.In this study,6 novel peptides derived from Chinese baijiu were identified successfully using high-performance liquid chromatography-quadrupoletime-of-flight mass spectrometry(HPLC-QTOF-MS)with a concentration of 0.835–24.540μg/L.The underlying molecular mechanisms were investigated,and their cytoprotective effects were examined against 2,2’-azobis(2-methylpropanimidamidine)dihydrochloride(AAPH)-induced oxidative stress in Hep G2 cells.The results showed that these peptides exerted protective effects by suppressing reactive oxygen species(ROS)generation,preventing malondialdehyde(MDA)formation,and upregulating cellular antioxidant enzyme activities(SOD,CAT,and GSH-Px)in a dose-dependent manner.Further experiments proved that these peptides exerted antioxidant effects via Nrf2/ARE-mediated signaling pathway by promoting Nrf2 nuclear translocation,inhibiting ubiquitination,and enhancing transcription capacity of Nrf2 in Hep G2 cells.These findings provide the molecular basis for the effects of antioxidant peptides derived from Chinese baijiu,which is important for a deeper understanding of the relationship between human health and moderate drinking.

Ultralong cycle life enabled by in situ growth of CoMo_(1-x)P/Mo heterostructure for lithium-sulfur batteries

Lithium-sulfur batteries(Li-S batteries) are considered as promising new-generation electrochemical energy storage devices due to their extremely high theoretical energy density(2600 Wh kg-1) and theoretical specific capacity(1675 m Ah g^(-1)). However, numerous problems such as poor conductivity and the shuttle effect during discharge-charge process limit the practical application of lithium-sulfur batteries. In this work, porous tubular Co Mo_(1-x)P/Mo constructed by in situ growth of metal Mo was designed as the sulfur host for lithium-sulfur batteries. The introduction of Mo modulated the electronic structure of Co Mo P to improve the conductivity of cathode and facilitate the redox kinetics, as well as the Co Mo_(1-x)P/Mo heterostructure was beneficial to inhibit the shuttle effect through the interaction with lithium polysulfides, which improved cycling stability. As a result, Co Mo_(1-x)P/Mo/S cathode had a low-capacity decay rate of only 0.029% per cycle after 2000 cycles at 0.5 C. This work provided a new perspective for the further design of high-performance lithium-sulfur battery cathode materials.

资源主导下基层编制如何动态统筹?——基于乡镇与街道的双案例研究

编制作为中国特色组织管理制度,是重要的政治资源和执政资源,为基层政府治理提供基本保障。随着基层事务增加和属地责任增强,无限扩大的行政责任与长期固化的编制之间产生了结构、功能、资源等三大矛盾,急需探索基层编制改革。鉴于此,基于编制分析视角,论文探讨基层政府在编制刚性束缚下,如何积极探索资源整合与编制统筹的创新路径。通过双案例研究发现,基层政府以机构改革带来的编制调整为契机,通过对不同资源(行政资源、财政资源和人力资源)进行整合,促进基层编制的动态统筹,使编制功能在基层政府治理中得以发挥,这为基层编制改革提供了可行路径。基层编制改革也需要考虑经济社会发展条件以及治理体制机制的成熟程度对编制统筹的影响。

Corrigendum to"In situ decoration of nanosized metal oxide on highly conductive MXene nanosheets as efficient catalyst for Li-O2 battery"[J.Energy.Chem.47(2020)272-280]

The authors regret that the printed version of the above article contained some errors.(1)In the original edition of Fig.5(b),the black and red chargedischarge curves represent the opposite current density.The red and black curve should represent the charge-discharge profiles at current densities of 100 and 500 mA g-1,respectively.

Genome-Wide Identification,Expression Profiling and Protein-Protein Interaction Properties of the BEL-Like Homeodomain Gene Family in Apple

BEL1-like homeodomain(BLH)family proteins are homeodomain transcription factors,which are found ubiquitously in plants and play important roles in regulating meristem and flower development.Although BLH proteins have been reported in some plant species,there is very little information available for plants in the Malus genus(e.g.,apple tree:Malus domestica).In the present study,we identified 19 apple MdBLH genes.Phylogenetic analysis revealed that the MdBLH genes could be divided into five groups.Analysis of gene structure showed that MdBLH gene has four exons,and the third exon was 61 bp in length.Chromosomal location analysis suggested that the MdBLH genes are not distributed uniformly on 12 chromosomes.Eleven MdBLH genes were cloned by RT-PCR,and their expression patterns were also determined.Among them,the expression levels of MdBLH4.1 and MdBLH9.1 could be induced by sodium chloride stress,while the expression levels of MdATH1.1,MdBLH8.1,MdBLH8.3,and MdBLH11.1 were down-regulated by such stress.Transcriptional levels of MdATH1.1 and MdBLH7.2 were down-regulated by mannitol stress.The result of yeast two-hybrid experiment showed that MdBEL1.1 interacted with apple ovate family proteins 6(MdOFP6),and MdBLH3.1 interacted with the MdOFP4,MdOFP6,MdOFP13,and MdOFP16 proteins.Our results provide a strong theoretical basis and a valuable reference for analyzing of the biological functions of MdBLH proteins as transcription factors in apple growth,development,and stress and also for the construction of regulatory networks.

Isolations and Identifications of Two Psychrotrophs and Preliminary Research on Their Applications

[Objective] The research aimed to initially study degradation effect of the CODc, in sewage by two psychrotrophs. [Method] Two psychrotrophs were isolated from the activated sludge of wastewater treatment plant in Tianjin Konggang Economic Area. CODc, degradation ability of the screened psychrotroph was analyzed in simulated domestic wastewater at 6℃. [Result] K 36 was identified as Comamonas testosterone, and K 38 was identified as Serratia fonticola. CODcr degradation abilities of the two strains were different in test. COOcr removal rates of the K 36 and K 38 respectively reached up to 23% and 53%. The measured result of growth rate suggested that two psychrotrophs both had high activities at low temperature. [ Conclusion] K 36 and K 38 had potentials in wastewater treatment application.

Neighboring optimal guidance using higher-order dynamics approximation with application to orbital injection problem

Neighboring optimal guidance,a method to obtain a suboptimal guidance law by approximately solving the first-order necessary conditions based on a nominal trajectory,is widely used in the aerospace field due to its high computational efficiency and low resource usage.For more advanced scenarios,the existing methods still have a problem that the guidance accuracy and optimality will seriously degrade when the actual state largely deviates from the nominal trajectory.This is mainly caused by the approximate description of the first-order conditions in terms of total flight time and nonlinear constraints.To address this problem,a higher-order neighboring optimal guidance method is proposed.First,a novel total flight time updating strategy,together with a normalized time scale,is presented that transforms the optimal problem with free total flight time into a more tractable optimal problem with fixed total flight time.Then,using the vector partial derivative method,a higher-order approximation is adopted,instead of the first-order approximation,to accurately describe the nonlinear dynamical and terminal constraints,thus obtaining a polynomially constrained quadratic optimal problem.Finally,to numerically solve the polynomially constrained quadratic optimal problem,a Newton-type iterative algorithm based on the orthogonal decomposition is designed.Through the iterative solution within each guidance period,the corrections to control quantities and total flight time are generated.The proposed method is applied to a launch vehicle orbital injection problem,and simulation results show that it achieves high accuracy of orbital injection and optimality of performance index.

Hierarchical structured robust adaptive attitude controller design for reusable launch vehicles

Reentry attitude control for reusable launch vehicles （RLVs） is challenging due to the characters of fast nonlinear dy- namics and large flight envelop. A hierarchical structured attitude control system for an RLV is proposed and an unpowered RLV con- trol model is developed. Then, the hierarchical structured control frame consisting of attitude controller, compound control strategy and control allocation is presented. At the core of the design is a robust adaptive control （RAC） law based on dual loop time-scale separation. A radial basis function neural network （RBFNN） is implemented for compensation of uncertain model dynamics and external disturbances in the inner loop. And then the robust op- timization is applied in the outer loop to guarantee performance robustness. The overall control design frame retains the simplicity in design while simultaneously assuring the adaptive and robust performance. The hierarchical structured robust adaptive con- troller （HSRAC） incorporates flexibility into the design with regard to controller versatility to various reentry mission requirements. Simulation results show that the improved tracking performance is achieved by means of RAC.

In situ decoration of CoP/Ti_(3)C_(2)Tx composite as efficient electrocatalyst for Li-oxygen battery

Application of Li-oxygen(Li-O_(2)) battery is in urgent need of bifunctional ORR/OER electrocatalyst. A surface-functionalization CoP/Ti_(3)C_(2)Txcomposite was fabricated theoretically, with the optimized electronic structure and more active electron, which is beneficial to the electrochemical reaction. The accordion shaped Ti_(3)C_(2)Txis featured with large specific surface area and outstanding electronic conductivity, which is beneficial for the adequate exposure of active sites and the deposition of Li2O2. Transition metal phosphides provide more electrocatalytic active sites and present good electrocatalytic effect. The CoP/Ti_(3)C_(2)Txcomposite served as the electrocatalyst of Li-O_(2)battery reaches a high specific discharge capacity of 17,413 m Ah/g at 100 m A/g and the lower overpotential of 1.25 V, superior to those of the CoP and Ti_(3)C_(2)Txindividually. The composite of transition metal phosphides and MXene are applied in Li-O_(2)battery, not only demonstrating higher cycling stability of the prepared CoP/Ti_(3)C_(2)Txcomposite, but pointing out the direction for their electrochemical performance improvement.

Compensated acceleration feedback based active disturbance rejection control for launch vehicles

In this paper, the attitude tracking and load relief control problems against wind disturbances and uncertain aerodynamics as well as the engine thrust of launch vehicles are studied.Firstly, a framework of Compensated Acceleration Feedback based Active Disturbance Rejection Control(CAF-ADRC) is established to achieve both desired attitude tracking and load relief performances. In particular, the total disturbance that includes the effects caused by both aerocoefficient perturbations and disturbances is estimated by constructing an Extended State Observer(ESO) to achieve attitude tracking. Furthermore, combined with the normal acceleration due to the engine thrust, the accelerometer measurement is also compensated to enhance the load relief effect.Secondly, the quantitative analysis of ESO and the entire closed-loop system are studied. It can be concluded that the desired attitude tracking and load relief performances can be achieved simultaneously under the proposed approach. Besides, tuning laws of the proposed approach are systematically given, which are divided into ESO, Proportional Derivative(PD) and Compensated Acceleration Feedback(CAF) modules. Moreover, the performances under CAF-ADRC approach can be better than those under CAF based PD(CAF-PD) approach by tuning load relief gain.Finally, the approach presented is applied to a typical control problem of launch vehicles with wind disturbances and parameter uncertainties.

Ultrathin hexagonal boron nitride as a van der Waals,force initiator activated graphene for engineering efficient non-metal electrocatalysts of Li-CO_(2) battery

Reasonably regulating electronic coupling to promote charge transfer and exciton separation has been regarded a promising approach in catalysis.The material engineering of van der Waals heterojunction(vdWsH)based on two-dimensional(2D)materials would be a potential way to optimize the as-prepared extrinsic physicochemical characteristics.However,it was still an almost uncultivated land waiting for exploration in catalysis.Herein,we introduced the inert h-boron nitride(h-BN)in non-metal reduced graphene oxide(GN)catalysts and constructed BN-GN vdWsH.The theoretical calculation demonstrated that the h-BN can effectively modify the electronic properties of graphene.With the introduction of h-BN,the BN-GN vdWsH can obviously enhance the catalytic activity of Li-CO_(2) battery.The existence of BN-GN vdWsH can reduce the overpotential more than 700 mV compared with reduced graphene oxide during the CO_(2) reduction reaction(CO_(2)RR)and CO_(2) evolution reaction(CO_(2)ER),and it extended cyclic stability more than three times,which was one structure design made it work as a high efficient electrocatalyst,catalytic materials.

Fractional-Order Proportional-Integral-Derivative Linear Active Disturbance Rejection Control Design and Parameter Optimization for Hypersonic Vehicles with Actuator Faults

The hypersonic vehicle model is characterized by strong coupling,nonlinearity,and acute changes of aerodynamic parameters,which are challenging for control system design.This study investigates a novel compound control scheme that combines the advantages of the Fractional-Order Proportional-Integral-Derivative(FOPID)controller and Linear Active Disturbance Rejection Control(LADRC)for reentry flight control of hypersonic vehicles with actuator faults.First,given that the controller has adjustable parameters,the frequency-domain analysis-method-based parameter tuning strategy is utilized for the FOPID controller and LADRC method(FOLADRC).Then,the influences of the actuator model on the anti-disturbance capability and parameter tuning of the FOLADRC-based closed-loop control system are analyzed.Finally,the simulation results indicate that the proposed FOLADRC approach has satisfactory performance in terms of rapidity,accuracy,and robustness under the normal operating condition and actuator fault condition.

Nanostructured Ni/Ti3C2Tx MXene hybrid as cathode for lithium-oxygen battery

Ti3C2 belongs to MXenes family,which is a new two-dimensional material and has been applied in many fields.With simple method of hydrothermal and high temperature calcination,nano structured Ni/Ti3C2Tx hybrid was synthesized.The stable layer structure of Ti3C2 MXene providing high surface area as well as excellent electronic conductivity are beneficial for deposition and decomposition of discharge product Li2O2.Furthermore,possessing special catalytic activity,Ni nanoparticles with size of about 20 nm could accelerate Li2O2 breaking down.Taking advantage of two kinds of materials,Ni/Ti3C2Tx hybrid as cathode of Li-O2 battery can achieve a maximal specific capacity of 20,264 mAh/g in 100 mA/g and 10,699 mAh/g in 500 mA/g at the first cycle.This work confirms that the prepared Ni/Ti3C2Tx hybrid exhibiting better cycling stability points out a new guideline to improve the electrochemical performance of lithium-oxygen batteries.

In situ localization of BiVO_(4) onto two-dimensional MXene promoting photoelectrochemical nitrogen reduction to ammonia

The existing industrial ammonia synthesis usually adopts the Haber-Bosch process,which requires harsh conditions of high temperature and high pressure,and consumes high energy.Under this circumstance,photoelectrochemical(PEC)catalysis is regarded as a promising method for N_(2) reduction reaction(NRR),but bears problems of low efficiency and yield.Thus,exploring active catalysts remains highly desirable.In this work,BiVO_(4)@MXene hybrids have been facilely synthesized by a hydrothermal route.The heterojunctions by the in situ growth of BiVO_(4) onto two-dimensional(2D)MXene greatly increase the NRR efficiency:under photoelectric conditions,the optimized NH_(3) yield is 27.25µg h^(-1) cm^(-2),and the Faraday efficiency achieves 17.54% at−0.8 V relative to the reversible hydrogen electrode(RHE),which are higher than most state-of-the-art NRR(photo)electrocatalysts.The mechanism speculation shows the enhanced light absorption range and the heterojunction formation largely promote the separation and the transfer efficiency of photogenerated carriers,thereby improving the PEC catalytic ability.Therefore,this work provides a hybrid route to combine the advantages of photo and electric catalysis for effective artificial nitrogen fixation.

Synergistic effect of V and Fe in Ni/Fe/V ternary layered double hydroxides for efficient and durable oxygen evolution reaction

High-performance and stable electrocatalysts are vital for the oxygen evolution reaction(OER).Herein,via a one-pot hydrothermal method,Ni/Fe/V ternary layered double hydroxides(NiFeV-LDH)derived from Ni foam are fabricated to work as highly active and durable electrocatalysts for OER.By changing the feeding ratio of Fe and V salts,the prepared ternary hydroxides were optimized.At an Fe:V ratio of 0.5:0.5,NiFeV-LDH exhibits outstanding OER activity superior to that of the binary hydroxides,requiring overpotentials of 269 and 274 mV at 50 mA·cm^(−2)in the linear sweep voltammetry and sampled current voltammetry measurements,respectively.Importantly,NiFeV-LDH shows extraordinary long-term stability(≥75 h)at an extremely high current density of 200 mA·cm^(−2).In contrast,the binary hydroxides present quick decay at 200 mA·cm^(−2)or even reduced current densities(150 and 100 mA·cm^(−2)).The outstanding OER performance of NiFeV-LDH benefits from the synergistic effect of V and Fe while doping the third metal into bimetallic hydroxide layers:(a)Fe plays a crucial role as the active site;(b)electron-withdrawing V stabilizes the high valence state of Fe,thus accelerating the OER process;(c)V further offers great stabilization for the formed intermediate of FeOOH,thus achieving superior durability.

Model-free adaptive optimal design for trajectory tracking control of rocket-powered vehicle

An adaptive optimal trajectory tracking controller is presented for the Solid-RocketPowered Vehicle(SRPV)with uncertain nonlinear non-affine dynamics in the framework of adaptive dynamic programming.First,considering that the ascent model of the SRPV is non-affine,a model-free Single Network Adaptive Critic(SNAC)method is developed based on the dynamic neural network and the traditional SNAC method.This developed model-free SNAC method overcomes the limitation of the traditional SNAC method that can only be applied to affine systems.Then,a closed-form adaptive optimal controller is designed for the non-affine dynamics of SRPVs.This controller can adjust its parameters under different flight conditions and converge to the approximate optimal controller through online self-learning.Finally,the convergence to the approximate optimal controller is proved.The theoretical analysis of the uniformly ultimate boundedness of the tracking error is also presented.Simulation results demonstrate the effectiveness of the proposed controller.