Insight into the structural evolution and thermal behavior of LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cathode under deep charge

By virtue of the crucial effect of the crystal structure and transition metal(TM)redox evolution on the performance of LiNi_(x)Co_(y)Mn_(z)O_(2)(NCM)cathode,systematical investigation is carried out to better understand the charge mechanism upon deep charging.Based on the results of X-ray diffraction and highresolution transmission electron microscope,phase transformations existing on particle surface are promoted by high potential because of the deeper lithium vacancies,accompanied by more substantial structure instability.Soft X-ray absorption spectroscopy indicates that Ni acts as the major contributor to charge compensation while Co displays a remarkable redox activity over the deep charge range.The elevated integrated intensity of pre-edge in O K-edge spectra reveals the extensive amount of holes formed in O 2 p orbitals and the enhanced hybridization of TM 3 d-O 2 p orbitals.Considering the close relationship between thermal behavior and structural evolution,the tendency of phase transitions and O_(2) release upon heating is accelerated by voltage rise,demonstrating the aggravated instability due to deeper Li utilization.Remaining Li contents in NCM are employed to estimate the amount of oxygen released in structural transformation and its detrimental effect on stability declares Li contentdependent characteristics.Furthermore,the extended Li vacancies,higher proportion of Ni4+and stronger orbital hybridization are considered as three factors impeding the thermal stability of the highlydelithiated NCM.

Tuning electrochemical transformation process of zeolitic imidazolate framework for efficient water oxidation activity

Metal-organic frameworks(MOFs)have been widely studied as efficient electrocatalysts for water oxidation due to their tunable structure and easy preparation.However,the rational design of MOFs-based electrocatalysts and fundamental understanding of their structural evolution during oxygen evolution reaction(OER)remain critical challenges.Here,we report a facile approach to tune the structural transformation process of the Co-based zeolitic imidazolate framework(ZIF)during the OER process by using water molecules as a vacancy promoter.The modified ZIF catalyst accelerates the structural transformation from MOF precursor to electrochemical active species and simultaneously enhances the vacancy density during the electrochemical activation process.The optimized electrocatalyst exhibits an extremely low overpotential 175 mV to deliver 10 mA cm^(-2) and superior durability(100 h)at 100 mA cm^(-2).The comprehensive characterization results reveal the structural transformation from the initial tetrahedral Co sites to cobalt oxyhydroxide(CoOOH)and the formation process of oxygen vacancies(CoOOH-Vo)at a high anodic potential.These findings represent a promising way to achieve highly active MOF-based electrocatalysts for water oxidation.

Design strategy and comprehensive performance assessment towards Zn anode for alkaline rechargeable batteries

Alkaline Zn-based primary batteries have been commercialized in the past decades.However,their success has not been extended to secondary batteries due to the poor cycle reversibility of Zn anodes.Although some research has been conducted on alkaline Zn anodes,their performance is still far from commercial requirements.A variety of degradation mechanisms,including passivation,dendrites,morphological changes,and hydrogen precipitation,are claimed responsible for the failure of alkaline Zn metal anodes.What’s worse,these constraints always interact with each other,which leads to a single strategy being unable to suppress all the issues.Therefore,a comprehensive evaluation of the positive and negative effects of various strategies on performance is important to promote the commercialization of alkaline Zn batteries.Herein,the recent progress and performance of improvement strategies for Zn anode in alkaline conditions are reviewed systematically.First,the principles and challenges of alkaline Zn anodes are briefly analyzed.Then,various design strategies for alkaline Zn anodes from the perspectives of ion and electron regulation are highlighted.Last,through a comprehensive summary of various performance parameters,the advantages and disadvantages of different strategies are compared and evaluated.On the basis of this assessment,we aim to provide more insights into the anode design of high-performance alkaline rechargeable Zn batteries.

Molecular exchange and passivation at interface afford high-performing perovskite solar cells with efficiency over 24%

The interface is crucial for perovskite solar cells(PSCs).However,voids at interfaces induced by the trapped hygroscopic dimethyl sulfoxide(DMSO)can reduce charge extraction and accelerate the film degradation,seriously damaging the efficiency and stability.In this work,4,4’-dinonyl-2,2’-dipyridine(DN-DP),a Lewis base with long alkyl chains is introduced to solve this problem.Theoretical calculated and experimental results confirm that the dipyridyl group on DN-DP can more strongly coordinate with Pb^(2+)than that of the S=O group on DMSO.The strong coordination effect plays a crucial role in removing the DMSO-based adduct and reducing the formation of voids.Due to the electron-donating properties of pyridine,the existence of DN-DP in the perovskite film can passivate the defects and optimize the energy level alignment of the perovskite configuration.The open-circuit voltage(VOC)of the DN-DP-based PSC is improved from 1.107 V(control device)to 1.153 V,giving rise to a power conversion efficiency(PCE)of24.02%.Furthermore,benefiting from the moisture resistance stemming from the hydrophobic nonyl group,the PCE retains 90.4%of the initial performance after 1000 h of storage in the ambient condition.

Molecule aging induced by electron attacking

Here we propose a new concept of"molecule aging":with some special treatment,a molecule could be"aged"by losing some unknown tiny particles or pieces from atoms in the molecule,Such"aging"or loss of unknown tiny particles does not change apparently its molecular structure or chemical composition,but some physicochemical properties could be changed irreversibly.We further confirm such"molecule aging"via a long-term electron attacking to age water(H_(2)O)molecules.The IR spectra show no structural difference between the fresh water and the aged one,while the NMR spectra show that the electron attacking can decrease the size of water clusters.Such facts indicate that the electron attacking indeed can"affect"the structure of water molecule slightly but without damaging to its basic molecule frame.Further exploration reveals that the hydrogen evolution reaction(HER)activity of the aged water molecule is lower than the fresh water on the same Pt/C electrocatalyst.The density functional theory calculations indicate that the shortened O-H bond in H_(2)O indeed can present lower HER activity,so the observed size decrease of water clusters from NMR probably could be attributed to the shortening of O-H bond in water molecules.Such results indicate significantly that the molecule aging can produce materials with new functions for new possible applications.

Efficient C-N coupling in electrocatalytic urea generation on copper carbonate hydroxide electrocatalysts

Urea generation through electrochemical CO_(2) and NO_(3)~-co-reduction reaction(CO_(2)NO_(3)RR)is still limited by either the low selectivity or yield rate of urea.Herein,we report copper carbonate hydroxide(Cu_2(OH)_2CO_(3))as an efficient CO_(2)NO_(3)RR electrocatalyst with an impressive urea Faradaic efficiency of45.2%±2.1%and a high yield rate of 1564.5±145.2μg h~(-1)mg_(cat)~(-1).More importantly,H_(2) evolution is fully inhibited on this electrocatalyst over a wide potential range between-0.3 and-0.8 V versus reversible hydrogen electrode.Our thermodynamic simulation reveals that the first C-N coupling follows a unique pathway on Cu_2(OH)_2CO_(3) by combining the two intermediates,~*COOH and~*NHO.This work demonstrates that high selectivity and yield rate of urea can be simultaneously achieved on simple Cu-based electrocatalysts in CO_(2)NO_(3)RR,and provide guidance for rational design of more advanced catalysts.

Effects of cerium addition on the microstructure and stress rupture properties of a new nickel-based cast superalloy

The microstructure and stress rupture properties of a new nickel-based cast superalloy were investigated with the cerium(Ce)additions of 0,19,50,96,150,and 300 ppm,respectively.The results indicated that Ce was mainly found in M C and M 23 C 6 carbides,and it was also found to exist in the form of cerium-rich phases or inclusions.According to the microstructure evidence,Ce promoted the formation of M C carbides and aggravated the inhomogeneity of M 23 C 6 carbides along grain boundaries.It was also identi-fied that the average sizes of primary and secondaryγ’phases all decreased with the rising Ce content.The acceleration of Ti,Nb,and C segregations during solidification was attributed to the influence of cerium on the variation of carbides along grain boundaries.The stress rupture life experienced a signifi-cant drop as the Ce content increased from 19 to 300 ppm.Explorations showed that the degradation was mainly attributed to the severe degradation of M C carbides and the easily forming micro-voids around them caused by the Ce addition.In addition to that,the increments in the inhomogeneous distribution of M 23 C 6 carbides at grain boundaries and the accelerated coarsening rate ofγ’phases both induced the fracture under complex stress conditions.

Texture and color enhancement imaging for detecting colorectal adenomas: Good, but not good enough

Texture and color enhancement imaging(TXI)has been developed as a novel image-enhancing endoscopy.However,the effectiveness of TXI detecting adenomas is inferior to narrow band imaging.Thus,future studies will need to focus on investigating the feasibility of such combination in clinical settings in order to provide patients with more accurate diagnoses.

Boosting electrochemical hydrogen evolution by coupling anodically oxidative dehydrogenation of benzylamine to benzonitrile

The electricity-driven water splitting acts as a promising pathway for renewable energy conversion and storage, yet anodic oxygen evolution reaction(OER) largely hinders its efficiency. Seeking the alternatives to OER exhibits the competitive advance to address this predicament. In this work, we show a more thermodynamically and kinetically favorable reaction, electrochemical oxidative dehydrogenation(EODH)of benzylamine to replace the conventional OER, catalyzed by a cobalt cyclotetraphosphate(Co_(2)P_(4)O_(12)) nanorods catalyst grown on nickel foam. This anodic reaction lowers the electricity input of 317 mV toward the desired current density of 100 mA/cm^(2), together with a highly selective benzonitrile product of more than 97%. More specifically, when coupling it with cathodic hydrogen evolution reaction(HER),the proposed HER||benzylamine-EODH configuration only requires a cell voltage of 1.47 V@100 mA/cm^(2),exhibiting an energy-saving up to 17% relative to conventional water splitting, as well as the near unit selectivity toward cathodic H_(2) and anodic benzonitrile products.

Microstructure and cavitation erosion behavior of sputtered NiCrAlTi coatings with and without N incorporations

The NiCrAlTi coatings free of N and with N incorporations were deposited on austenitic stainless steel304 L by magnetron sputtering in Ar and in gas mixture of Ar and N2,respectively.The N incorporated in the coatings existed as nitride precipitates(from^3 vol.%to^17 vol.%)after vacuum annealing.All the NiCrAlTi coatings,whatever free of N or with N incorporations,exhibited better resistance against cavitation erosion than ion plating Ti N coating and the substrate 304 L in ultrasonic cavitation tests.The NiCrAlTi coating free of N incorporation presents superior cavitation erosion resistance.However,the nitrogen incorporation within the NiCrAlTi coatings showed negative effects on the resistance against cavitation erosion.

A grain-size-dependent structure evolution in gradient-structured(GS) Ni under tension

This work outlines an experimental investigation of grain-size-dependent structure evolution under tension in nickel with a grain size gradient.Two opposite and competing processes,grain refinement and coarsening,were examined within one specimen,due to the widely ranging grain size in gradient-structured(GS)Ni.A tensioninduced minimum grain size of approximately 280 nm was determined in GS Ni,which is comparable to those obtained by severe plastic deformation processes.The minimum grain size was phenomenologically explained using a dislocation model.Below the minimum grain size,the Ni’s grain coarsening ability peaked at approximately 50 nm and progressively decreased with decreasing grain size,showing an inverse grain-size-dependent coarsening tendency.Moreover,this inverse grain coarsening behavior was related to a transition in the deformation mechanism,through which the deformation process was accommodated more by partial dislocation than by full dislocation below a critical grain size.This was confirmed by observation of the microstructure and low temperature tensile testing results.This work demonstrates a high-throughput strategy for exploring the minimum grain size and grain-size-dependent coarsening in metals.

A unified model for determining fracture strain of metal films on flexible substrates

Failure strain determination of polymer-supported thin films is a key for the design of the flexible devices.A theoretical model R/R0=(L/L0)2(R,L are the electrical resistance and the length of the stretched film,respectively.R0,L0 are the corresponding initial values.)has been widely used to determine the fracture strain of thin films on flexible substrates.However,this equation loses its function in some special cases.Here,a simple and universal theoretical model was proposed to determine the fracture strain of metal thin films on flexible substrates in more generally situations.With this model,we investigated the thicknessdependent failure strains of Cu-5 at.%Al films with thickness of 10 nm,200 nm,1000 nm,and Ti films with thickness of 50 nm,100 nm,300 nm.This model was also employed to study the published data available.The results showed that the new model provided a fairly good prediction of the failure strains of different films.

Robust copper nanocrystal/nitrogen-doped carbon monoliths as carbon monoxide-resistant electrodes for methanol oxidation reaction

Noble metal-based electrocatalysts present high activities for methanol oxidation reaction(MOR),but are limited by their high cost,low stability and poor resistance to carbon monoxide(CO) poisoning.The development of active and stable non-noble metal electrocatalysts for MOR is desired,but remains a challenge.Herein,we report a simple strategy to make copper nanocrystal/nitrogen-doped carbon(Cu/N-C)monoliths,which can serve as active and robust electrodes for MOR.Copper nanocrystals were electrochemically deposited onto a conductive polyaniline hydrogel and calcined to form Cu/N-C monolith,where the active copper nanocrystals are protected by nitrogen-doped carbon.Owing to their extremely high electrical conductivity(1.25 × 10^(5) S cm^(-1)) and mechanical robustness,these Cu/N-C monoliths can be directly used as electrodes for MOR,without using substrates or additives.The optimal Cu/N-C(FT)@500 monolith shows a high MOR activity of 189 mA cm^(-2) at 0.6 V vs.SCE in alkaline methanol solution,superior to most of reported Cu-based MOR catalysts.Cu/N-C(FT)@500 also presents a better stability than Pt/C catalyst in the long-term MOR test at high current densities.Upon carbon monoxide(CO) poisoning,Cu/N-C(FT)@500 retains 96% of its MOR activity,far exceeding the performance of Pt/C catalyst(61% retention).Owing to its facile synthesis,outstanding activity,high stability and mechanical robustness,Cu/N-C(FT)@500 monolith is promising as a low-cost,efficient and CO-resistant electrocatalyst for MOR.

The importance of H_(2) in the controlled growth of semiconducting single-wall carbon nanotubes

H_(2) is considered an indispensable component of the atmosphere for the growth of high-quality singlewall carbon nanotubes(SWCNTs)by chemical vapor deposition.However,details of the roles H_(2) playing are still unclear due to the complex conditions of SWCNT growth.In this study,we elucidate the functions of H_(2) in the selective growth of semiconducting SWCNTs(s-SWCNTs)by using monodispersed uniform Fe nanoparticles as a catalyst.High-quality s-SWCNTs were synthesized by finely tuning the concentration of H_(2) and the other growth parameters.Experimental data combined with atomistic simulations indicate that H_(2) not only adjusts the concentration of the carbon source,but also serves as a mild etchant that selectively removes small carbon caps grown by a perpendicular mode from the Fe nanoparticles.These results provide useful hints for the controlled growth of SWCNTs with a semiconducting or metallic conductivity,and even a specific chirality.

The hippo kinases MST1/2 in cardiovascular and metabolic diseases:A promising therapeutic target option for pharmacotherapy

Cardiovascular diseases(CVDs)and metabolic disorders are major components of noncommunicable diseases,causing an enormous health and economic burden worldwide.There are common risk factors and developmental mechanisms among them,indicating the far-reaching significance in exploring the corresponding therapeutic targets.MST1/2 kinases are well-established proapoptotic effectors that also bidirectionally regulate autophagic activity.Recent studies have demonstrated that MST1/2 influence the outcome of cardiovascular and metabolic diseases by regulating immune inflammation.In addition,drug development against them is in full swing.In this review,we mainly describe the roles and mechanisms of MST1/2 in apoptosis and autophagy in cardiovascular and metabolic events as well as emphasis on the existing evidence for their involvement in immune inflammation.Moreover,we summarize the latest progress of pharmacotherapy targeting MST1/2 and propose a new mode of drug combination therapy,which may be beneficial to seek more effective strategies to prevent and treat CVDs and metabolic disorders.

2D graphene oxide-L-arginine-soybean lecithin nanogenerator for synergistic photothermal and NO gas therapy

Nitric oxide(NO) gas therapy has been regarded as a promising strategy for cancer treatment. However,its therapeutic efficiency is still unsatisfying due to the limitations of monotherapy. Previous preclinical and clinical studies have shown that combination therapy could significantly enhance therapeutic efficiency. Herein, a graphene oxide(GO)-L-arginine(L-Arg, a natural NO donor) hybrid nanogenerator is developed followed by surface functionalization of soybean lecithin(SL) for synergistic enhancement of cancer treatment through photothermal and gas therapy. The resultant GO-Arg-SL nanogenerator not only exhibited good biocompatibility and excellent endocytosis ability, but also exhibited excellent photothermal conversion capability and high sensitivity to release NO within tumor microenvironment via inducible NO synthase(i NOS) catalyzation. Moreover, the produced hyperthermia and intracellular NO could synergistically kill cancer cells both in vitro and in vivo. More importantly, this nanogenerator can efficiently eliminate tumor while inhibiting the tumor recurrence because of the immunogenic cell death(ICD) elicited by NIR laser-triggered hyperthermia and the immune response activation by massive NO generation. We envision that the GO-Arg-SL nanogenerator could provide a potential strategy for synergistic photothermal and gas therapy.

Recent advances in defined hydrogels in organoid research

Organoids are in vitro model systems that mimic the complexity of organs with multicellular structures and functions, which provide great potential for biomedical and tissue engineering. However, their current formation heavily relies on using complex animal-derived extracellular matrices (ECM), such as Matrigel. These matrices are often poorly defined in chemical components and exhibit limited tunability and reproducibility. Recently, the biochemical and biophysical properties of defined hydrogels can be precisely tuned, offering broader opportunities to support the development and maturation of organoids. In this review, the fundamental properties of ECM in vivo and critical strategies to design matrices for organoid culture are summarized. Two typically defined hydrogels derived from natural and synthetic polymers for their applicability to improve organoids formation are presented. The representative applications of incorporating organoids into defined hydrogels are highlighted. Finally, some challenges and future perspectives are also discussed in developing defined hydrogels and advanced technologies toward supporting organoid research.

Ga/GaSb nanostructures:Solution-phase growth for highperformance infrared photodetection

Gallium antimonide(GaSb)-based nanostructures have been reported via various vapor-phase synthetic routes while there is not a report on the growth of GaSb nanostructures via a complete one-step solution-phase synthetic strategy.Herein we report the design and synthesis of tadpole-like Ga/GaSb nanostructures by a one-step solution-phase synthetic route typically from the precursors of commercial triphenyl antimony(Sb(Ph)_(3))and trimethylaminogallium(Ga(NMe_(2))_(3))at 260°C in 1-octadecene.The GaSb nanocrystals are grown based on a solution–liquid–solid(SLS)mechanism with zinc blende phase,and their size and shape can be controlled in the procedures via manipulating the reaction conditions.Meanwhile,the tadpole-like Ga/GaSb nanostructures can be applied for the fabrication of a GaSb/Si nanostructured heterojunction-like photodetector over silicon wafer,which demonstrates excellent photoresponse and detection performances from wavelength of 405 to 1,064 nm with high photoresponding rate.Typically,the photodetector exhibits a high responsivity of 18.9 A·W^(−1),a superior detectivity of 1.1×10^(13)Jones,and an ultrafast response speed of 44 ns.The present work provides a new strategy to group III–V antimonide-based semiconducting nanostructures that are capable for the fabrication of photodetector with broadband,high-detectivity,and high-speed photodetecting performances.

Ebola virus VP35 perturbs type I interferon signaling to facilitate viral replication

As one of the deadliest viruses,Ebola virus(EBOV)causes lethal hemorrhagic fevers in humans and nonhuman primates.The suppression of innate immunity leads to robust systemic virus replication of EBOV,leading to enhanced transmission.However,the mechanism of EBOV-host interaction is not fully understood.Here,we identified multiple dysregulated genes in early stage of EBOV infection through transcriptomic analysis,which are highly clustered to Jak-STAT signaling.EBOV VP35 and VP30 were found to inhibit type I interferon(IFN)signaling.Moreover,exogenous expression of VP35 blocks the phosphorylation of endogenous STAT1,and suppresses nuclear translocation of STAT1.Using serial truncated mutations of VP35,N-terminal 1–220amino acid residues of VP35 were identified to be essential for blocking on type I IFN signaling.Remarkably,VP35 of EBOV suppresses type I IFN signaling more efficiently than those of Bundibugyo virus(BDBV)and Marburg virus(MARV),resulting in stable replication to facilitate the pathogenesis.Altogether,this study enriches understanding on EBOV evasion of innate immune response,and provides insights into the interplay between filoviruses and host.

一种高效稳定的大电流密度产氢电催化剂

电解水制氢具有工艺简单、原料来源广泛、无污染、氢气纯度高等优点,是最具发展前景的制氢技术之一.然而电解水制氢存在的最大问题是析氢析氧过程能耗过高,需要添加催化剂降低反应能垒.目前,电催化产氢性能最好的材料依然是价格昂贵且储量有限的贵金属铂基催化剂.发展高效稳定的大电流密度制氢非贵金属催化剂,对于氢气的规模化制备和商业化应用意义重大.本工作采用三维导电泡沫镍为自支撑电极材料,引入钼源和硫源构建高活性催化析氢Mo-Ni-S体系.通过水热反应和退火处理,在泡沫镍基底上制备得到了具有高担载量、细长浓密的Mo S2/Ni3S2同轴异质结构纳米线.催化剂结构设计方面,在水热反应过程中创新性地引入表面活性剂(P123),调控催化剂形貌,增加了活性位点数目.在组分调控方面,通过后期退火处理去除低活性物相,增强了催化性能.基于以上结构和组分设计调控,该催化剂在碱性体系下具有优异的大电流密度催化产氢性能,仅需较低过电势便可获得较高的电流密度,同时具有优异的大电流密度产氢稳定性,其电催化产氢性能超过了已报道的众多催化剂.