Plasma-assisted synthesis of porous bismuth nanosheets for electrocatalytic CO_(2)-to-formate reduction

The electrochemical carbon dioxide reduction(eCO_(2)RR)to formate,driven by clean energy,is a promising approach for producing renewable chemicals and high-value fuels.Despite its potential,further development faces challenges due to limitations in electrocatalytic activity and durability,especially for nonnoble metal-based catalysts.Here,naturally abundant bismuth-based nanosheets that can effectively drive CO_(2)-to-formate electrocatalytic reduction are prepared using the plasma-activated Bi_(2)Se_(3) followed by a reduction process.Thus-obtained plasma-activated Bi nanosheets(P-BiNS)feature ultrathin structures and high surface areas.Such nanostructures ensure the P-BiNS with outstanding eCO_(2)RR catalytic performance,highlighted by the current density of over 80 mA cm^(-2) and a formate Faradic efficiency of>90%.Furthermore,P-BiNS catalysts demonstrate excellent durability and stability without deactivation following over 50h of operation.The selectivity for formate production is also studied by density functional theory(DFT)calculations,validating the importance and efficacy of the stabilization of intermediates(^(*)OCHO)on the P-BiNS surfaces.This study provides a facile plasma-assisted approach for developing high-performance and low-cost electrocatalysts.

Mutation in a non-force-bearing region of protein L influences force-dependent unfolding behavior

Single-molecule magnetic tweezers(MTs) have revealed multiple transition barriers along the unfolding pathway of several two-state proteins, such as GB1 and Csp. In this study, we utilized MTs to measure the force-dependent folding and unfolding rates of both protein L(PLWT) and its Y47W mutant(PLY47W) where the mutation point is not at the force-bearing β-strands. The measurements were conducted within a force range of 3–120 pN. Notably, the unfolding rates of both PLWT and PWY47W exhibit distinct force sensitivities below 50 pN and above 60 pN, implying a two-barrier free energy landscape. Both PLWT and PLY47W share the same force-dependent folding rate and the same transition barriers,but the unfolding rate of PLY47W is faster than that of PLWT. Our finding demonstrates that the residue outside of the force-bearing region will also affect the force-induced unfolding dynamics.

A Rational Design of Metal–Organic Framework Nanozyme with High‑Performance Copper Active Centers for Alleviating Chemical Corneal Burns

Metal–organic frameworks(MOFs)have attracted significant research interest in biomimetic catalysis.However,the modulation of the activity of MOFs by precisely tuning the coordination of metal nodes is still a significant challenge.Inspired by metalloenzymes with well-defined coordination structures,a series of MOFs containing halogen-coordinated copper nodes(Cu-X MOFs,X=Cl,Br,I)are employed to elucidate their structure–activity relationship.Intriguingly,experimental and theoretical results strongly support that precisely tuning the coordination of halogen atoms directly regulates the enzyme-like activities of Cu-X MOFs by influencing the spatial configuration and electronic structure of the Cu active center.The optimal Cu–Cl MOF exhibits excellent superoxide dismutase-like activity with a specific activity one order of magnitude higher than the reported Cu-based nanozymes.More importantly,by performing enzyme-mimicking catalysis,the Cu–Cl MOF nanozyme can significantly scavenge reactive oxygen species and alleviate oxidative stress,thus effectively relieving ocular chemical burns.Mechanistically,the antioxidant and antiapoptotic properties of Cu–Cl MOF are achieved by regulating the NRF2 and JNK or P38 MAPK pathways.Our work provides a novel way to refine MOF nanozymes by directly engineering the coordination microenvironment and,more significantly,demonstrating their potential therapeutic effect in ophthalmic disease.

Adhesion strength of tetrahydrofuran hydrates is dictated by substrate stiffness

Understanding the hydrate adhesion is important to tackling hydrate accretion in petro-pipelines.Herein,the relationship between the Tetrahydrofuran(THF)hydrate adhesion strength(AS)and surface stiffness on elastic coatings is systemically examined by experimental shear force measurements and theoretical methods.The mechanical factor-elastic modulus of the coatings greatly dictates the hydrate AS,which is explained by the adhesion mechanics theory,beyond the usual factors such as wettability and structural roughness.Moreover,the hydrate AS increases with reducing the thickness of the elastic coatings,resulted from the decrease of the apparent surface elastic modulus.The effect of critical thickness for the elastic materials with variable elastic modulus on the hydrate AS is also revealed.This study provides deep perspectives on the regulation of the hydrate AS by the elastic modulus of elastic materials,which is of significance to design anti-hydrate surfaces for mitigation of hydrate accretion in petro-pipelines.

Tailoring the Meso-Structure of Gold Nanoparticles in Keratin-Based Activated Carbon Toward High-Performance Flexible Sensor

Flexible biosensors with high accuracy and reliable operation in detecting pH and uric acid levels in body fluids are fabricated using well-engineered metaldoped porous carbon as electrode material.The gold nanoparticles@N-doped carbon in situ are prepared using wool keratin as both a novel carbon precursor and a stabilizer.The conducting electrode material is fabricated at 500℃ under customized parameters,which mimics A-B type(two different repeating units) polymeric material and displays excellent deprotonation performance(pH sensitivity).The obtained pH sensor exhibits high pH sensitivity of 57 mV/pH unit and insignificant relative standard deviation of 0.088%.Conversely,the composite carbon material with sp^2 structure prepared at 700℃ is doped with nitrogen and gold nanoparticles,which exhibits good conductivity and electrocatalytic activity for uric acid oxidation.The uric acid sensor has linear response over a range of 1-150 μM and a limit of detection 0.1 μM.These results will provide new avenues where biological material will be the best start,which can be useful to target contradictory applications through molecular engineering at mesoscale.

A robust Janus bilayer with tailored ionic conductivity and interface stability for stable Li metal anodes

The formation and growth of Li-dendrites caused by inhomogeneous Li deposition severely hinder the commercial applications of Li metal batteries due to the consequence of short-circuiting.Herein,we propose a Janus bilayer composed of black phosphorus(BP)and graphene oxide(GO)as an artificial interface with chemical/mechanical stability and well-regulated Li-ion flux distribution for Li metal anode protection.Owing to the synergy between the fast Li-ion transport of BP in the inner layer and the high mechanical and chemical stability of GO in the outer layer,the GO/BP with good electrolyte wettability acts as a Li-ion regulator that can induce homogeneous growth of Li to suppress the Li dendrites growth.Accordingly,long-term stability(500 h at 1 mA cm^(-2))with a low overpotential of 30 mV is achieved in the symmetric cell with GO/BP-Li anode.Furthermore,the Li–S cell with GO/BP-Li exhibits enhanced cycling performance with a high capacity retention rate of 76.2%over 500 cycles at 1 C.

Different potential of mean force of two-state protein GB1 and downhill protein gpW revealed by molecular dynamics simulation

Two-state folding and down-hill folding are two kinds of protein folding dynamics for small single domain proteins.Here we apply molecular dynamics(MD)simulation to the two-state protein GB1 and down-hill folding protein gpW to reveal the relationship of their free energy landscape and folding/unfolding dynamics.Results from the steered MD simulations show that gpW is much less mechanical resistant than GB1,and the unfolding process of gpW has more variability than that of GB1 according to their force-extension curves.The potential of mean force(PMF)of GB1 and gpW obtained by the umbrella sampling simulations shows apparent difference:PMF of GB1 along the coordinate of extension exhibits a kink transition point where the slope of PMF drops suddenly,while PMF of gpW increases with extension smoothly,which are consistent with two-state folding dynamics of GB1 and downhill folding dynamics of gpW,respectively.Our results provide insight to understand the fundamental mechanism of different folding dynamics of twostate proteins and downhill folding proteins.

Derivation of persistent time for anisotropic migration of cells

Cell migration plays an essential role in a wide variety of physiological and pathological processes. In this paper we numerically discuss the properties of an anisotropic persistent random walk （APRW） model, in which two different and independent persistent times are assumed for cell migrations in the x-and y-axis directions. An intrinsic orthogonal coordinates with the primary and non-primary directions can be defined for each migration trajectory based on the singular vector decomposition method. Our simulation results show that the decay time of single exponential distribution of velocity auto-correlation function （VACF） in the primary direction is actually the large persistent time of the APRW model, and the small decay time of double exponential VACF in the non-primary direction equals the small persistent time of the APRW model. Thus, we propose that the two persistent times of anisotropic migration of cells can be properly estimated by discussing the VACFs of trajectory projected to the primary and non-primary directions.

Advanced surface engineering of titanium materials for biomedical applications:From static modification to dynamic responsive regulation

Titanium(Ti)and its alloys have been widely used as orthopedic implants,because of their favorable mechanical properties,corrosion resistance and biocompatibility.Despite their significant success in various clinical applications,the probability of failure,degradation and revision is undesirably high,especially for the patients with low bone density,insufficient quantity of bone or osteoporosis,which renders the studies on surface modification of Ti still active to further improve clinical results.It is discerned that surface physicochemical properties directly influence and even control the dynamic interaction that subsequently determines the success or rejection of orthopedic implants.Therefore,it is crucial to endow bulk materials with specific surface properties of high bioactivity that can be performed by surface modification to realize the osseointegration.This article first reviews surface characteristics of Ti materials and various conventional surface modification techniques involving mechanical,physical and chemical treatments based on the formation mechanism of the modified coatings.Such conventional methods are able to improve bioactivity of Ti implants,but the surfaces with static state cannot respond to the dynamic biological cascades from the living cells and tissues.Hence,beyond traditional static design,dynamic responsive avenues are then emerging.The dynamic stimuli sources for surface functionalization can originate from environmental triggers or physiological triggers.In short,this review surveys recent developments in the surface engineering of Ti materials,with a specific emphasis on advances in static to dynamic functionality,which provides perspectives for improving bioactivity and biocompatibility of Ti implants.

Bioinspired nanofluidic iontronics for brain-like computing

The human brain performs computations via a highly interconnected network of neurons.Taking inspiration from the information delivery and processing mechanism of the human brain in central nervous systems,bioinspired nanofluidic iontronics has been proposed and gradually engineered to overcome the limitations of the conventional electron-based von Neumann architecture,which shows the promising potential to enable efficient brain-like computing.Anomalous and tunable nanofluidic ion transport behaviors and spatial confinement show promising controllability of charge carriers,and a wide range of structural and chemical modification paves new ways for realizing brain-like functions.Herein,a comprehensive framework of mechanisms and design strategy is summarized to enable the rational design of nanofluidic systems and facilitate the further development of bioinspired nanofluidic iontronics.This review provides recent advances and prospects of the bioinspired nanofluidic iontronics,including ion-based brain computing,comprehension of intrinsic mechanisms,design of artificial nanochannels,and the latest artificial neuromorphic functions devices.Furthermore,the challenges and opportunities of bioinspired nanofluidic iontronics in the pioneering and interdisciplinary research fields are proposed,including brain–computer interfaces and artificial neurons.

Improving physical properties of poly(vinyl alcohol)/montmorillonite nanocomposite hydrogels via the Hofmeister effect

Hydrogel is a kind of three-dimensional crosslinked polymer material with high moisture content.However,due to the network defects of polymer gels,traditional hydrogels are usually brittle and fragile,which limits their practical applications.Herein,we present a Hofmeister effect-aided facile strategy to prepare high-performance poly(vinyl alcohol)/montmorillonite nanocomposite hydrogels.Layered montmorillonite nanosheets can not only serve as crosslinking agents to enhance the mechanical properties of the hydrogel but also promote the ion conduction.More importantly,based on the Hofmeister effect,the presence of(NH_(4))_(2)SO_(4)can endow nanocomposite hydrogels with excellent mechanical properties by affecting PVA chains'aggregation state and crystallinity.As a result,the as-prepared nanocomposite hydrogels possess unique physical properties,including robust mechanical and electrical properties.The as-prepared hydrogels can be further assembled into a high-performance flexible sensor,which can sensitively detect large-scale and small-scale human activities.The simple design concept of this work is believed to provide a new prospect for developing robust nanocomposite hydrogels and flexible devices in the future.

Pressure-driven membrane inflation through nanopores on the cell wall

Walled cells,such as in plants and fungi,compose an important part of the model systems in biology.The cell wall primarily prevents the cell from over-expansion when exposed to water,and is a porous material distributed with nanosized pores on it.In this paper,we study the deformation of a membrane patch by an osmotic pressure through a nanopore on the cell wall.We find that there exists a critical pore size or a critical pressure beyond which the membrane cannot stand against the pressure and would inflate out through the pore and further expand.The critical pore size scales linearly with the membrane tension and quadratically with the spontaneous curvature.The critical pressure is inversely proportional to the pore radius.Our results also show that the fluid membrane expansion by pressure is mechanically different from the solid balloon expansion,and predict that the bending rigidity of the membrane in walled cells should be much larger than that of the mammalian cells so as to prevent membrane inflation through the pores on the cell wall.

Mechanical enhancement and weakening in Mo_(6)S_(6)nanowire by twisting

The torsional,bending and tensile mechanical properties of Mo_(6)S_(6)nanowire are examined by molecular dynamics(MD)simulations with a first-principles-based reactive force field(ReaxFF).It is found that Mo_(6)S_(6)nanowire shows unique mechanical properties such as high torsional and bending flexibility,high Young's modulus and strength,and negative Poisson's ratio.The Mo_(6)S_(6)nanowire can be strengthened or weakened via twisting,depending on the twist angle.The Mo_(6)S_(6)nanowire with a slight twist angle shows brittle failure,whereas it with a large twist angle exhibits ductile failure and necking behavior.Twisted Mo_(6)S_(6)nanowires show a crossover in the negative Poisson's ratio at critical strains,that is,Poisson's ratio first decreases but then increases,with a minimum value down to around-0.8 at the strain of 0.01 as the twist angle is 21.0°/nm.The negative Poisson's ratio and the crossover are explained by the bond transform that makes zero angles to the wire cross-section.

Hydrogen diffusion in C′_(1) phase clathrate hydrate

Recently,a new phase C'_(1) H_(2) hydrate was experimentally identified.In this work,the diffusive behaviors of H_(2) in C'_(1)phase clathrate hydrate are explored using classic molecular dynamics(MD)simulations.It reveals that the cage occupancy by H_(2) molecule negligibly influences the C'_(1) phase clathrate structure but greatly dictates the diffusion coefficient of H_(2)molecule.Due to the small cage size and small windows connecting the neighboring cages in C'_(1) phase clathrate,nonoccupancy of the neighboring cages is demanded to enable the diffusion of H_(2) molecule that is primarily dominated by hopping mechanism.Moreover,the analysis of diffusive free energy landscape reveals lower energy barrier of H_(2) molecule in C'_(1) phase clathrate hydrate than that of other gases in conventional clathrate hydrates,and that H_(2) molecule travels through the windows between neighboring cages with preferential molecular orientation.This study provides critical physical insights into the diffusion behaviors of H_(2) in the C'_(1) phase clathrate hydrate,and implies that the C'_(1) clathrate hydrate is a promising solid structure for the next-generation H_(2) storage.

Temperature-regulation liquid gating membrane with controllable gas/liquid separation

Membrane separation technology with the ability to regulate gas/liquid transport and separation is critical for environmental fields, such as sewerage treatment, multiphase separation, and desalination. Although numerous membranes can dynamically control liquid-phase fluids transport via external stimuli, the transport and separation of gas-phase fluids remains a challenge. Here, we show a temperature-regulation liquid gating membrane that allows in-situ dynamically controllable gas/liquid transfer and multiphase separation by integrating a thermo-wettability responsive porous membrane with functional gating liquid. Experiments and theoretical analysis have demonstrated the temperature-regulation mechanism of this liquid gating system, which is based on thermo-responsive changes of porous membrane surface polarity, leading to changes in affinity between the porous membrane and the gating liquid. In addition, the sandwich configuration with dense Au-coated surfaces and heterogeneous internal components by a bistable interface design enables the liquid gating system to enhance response sensitivity and maintain working stability. This temperature-regulation gas/liquid transfer strategy expands the application range of liquid gating membranes,which are promising in environmental governance, water treatment and multiphase separation.

Thermally responsive ionic transport system reinforced by aligned functional carbon nanotubes backbone

Ion transport plays an important role in energy conversion, biosensors, and a variety of biological processes. Carbon nanotubes, especially for the carbon nanotubes arrays with controlled vertically aligned structures, have displayed great potential as a promising material for regulating ion transport behaviors in the applications of the nanofluidic devices and osmotic energy conversion. Herein, we demonstrate the thermo-controlled ion transport system through the vertically aligned multiwall carbon nanotubes arrays membrane modified by the thermo-responsive hydrogel in a simple and reliable way. The functional carbon nanotubes backbone with the inherent surface charge and interstitial channels structure renders the system improved ion transport behaviors and well controlled switching property by thermo. Based on the integrated properties, the energy output from osmotic power in this system could be regulated by the reversible temperature switches. Moreover, it can realize a higher osmotic energy conversion property regulated by the thermos, which may extend the practical application in the future. The system that combines intelligent response with controlled ion transport behaviors and potential osmotic energy utilizations presents a valuable paradigm for the use of carbon nanotubes and hydrogel composite materials and provides a promising way for applications of nanofluidic devices.

Dynamic asymmetric mechanical responsive carbon nanotube fiber for ionic logic gate

Inspired by biological ion channels,numerous artificial asymmetric ion channels have been synthesized to facilitate the fabrication of ionic circuits.Nevertheless,the creation of biomimetic asymmetric ion channels necessitates expensive scientific apparatus and intricate material processing procedures,which constrains its advancement within the realm of ionic devices.In this study,we have devised dynamic asymmetric ion channels with mechanical responsiveness by combining polymers of varying elastic modulus along the longitudinal axis of carbon nanotube fiber(CNTF).The ion rectification can be modulated via the disparate response of CNTF-based ion channels to mechanical stress.We have effectively employed these asymmetric ion channels with mechanical sensitivity in the design of a logic gate device,achieving logic operations such as“AND”and“OR”.The conception of these dynamic asymmetric ion channels with mechanical sensitivity offers a straightforward,cost-effective,and versatile approach for generating ion channels,highlighting their potential application in intricate,highly integrated ionic circuits.

Reduced Ti-MOFs encapsulated black phosphorus with high stability and enhanced photocatalytic activity

The generation of green hydrogen(H_2) energy is of great significance to solve worldwide energy and environmental issues. Reduced Ti based photocatalyst has recently attracted intensive attention due to its excellent photocatalytic activity, while the synthesis of reduced Ti based photocatalysts with high stability is still a great challenge. Here, we report a facile method for synthesis of reduced Ti metal organic frameworks(small amounts of Pt incorporated) encapsulated BP(BP/R-Ti-MOFs/Pt) hybrid nanomaterial with enhanced photocatalytic activity. The strong interaction between Ti and P reduces the valence state of the binding Ti^(4+)on the BP surface, forming abundant reduced Ti^(4+)within R-Ti-MOFs/BP. Such reduced Ti^(4+)render R-Ti-MOFs/BP efficient charge transfer and excellent light absorption capability, thus promote the photocatalytic H_2 production efficiency. Furthermore, the Ti-P interaction stabilizes both reduced Ti^(4+)and BP during the photocatalytic reaction, which greatly enhanced the stability of the obtained BP/R-TiMOFs/Pt photocatalyst.

Equilibrium folding and unfolding dynamics to reveal detailed free energy landscape of src SH3 protein by magnetic tweezers

Src SH3 protein domain is a typical two-state protein which has been confirmed by research of denaturant-induced unfolding dynamics.Force spectroscopy experiments by optical tweezers and atomic force microscopy have measured the force-dependent unfolding rates with different kinds of pulling geometry.However,the equilibrium folding and unfolding dynamics at constant forces has not been reported.Here,using stable magnetic tweezers,we performed equilibrium folding and unfolding dynamic measurement and force-jump measurement of src SH3 domain with tethering points at its N-and C-termini.From the obtained force-dependent transition rates,a detailed two-state free energy landscape of src SH3 protein is constructed with quantitative information of folding free energy,transition state barrier height and position,which exemplifies the capability of magnetic tweezers to study protein folding and unfolding dynamics.

Dual mechanisms of Bcl-2 regulation in IP_(3)-receptor-mediated Ca^(2+)release:A computational study

Inositol 1,4,5-trisphosphate receptors(IP_(3)R)-mediated calcium ion(Ca^(2+))release plays a central role in the regulation of cell survival and death.Bcl-2 limits the Ca^(2+)release function of the IP3R through a direct or indirect mechanism.However,the two mechanisms are overwhelmingly complex and not completely understood.Here,we convert the mechanisms into a set of ordinary differential equations.We firstly simulate the time evolution of Ca^(2+)concentration under two different levels of Bcl-2 for the direct and indirect mechanism models and compare them with experimental results available in the literature.Secondly,we employ one-and two-parameter bifurcation analysis to demonstrate that Bcl-2 can suppress Ca^(2+)signal from a global point of view both in the direct and indirect mechanism models.We then use mathematical analysis to clarify that the indirect mechanism is more efficient than the direct mechanism in repressing Ca^(2+)signal.Lastly,we predict that the two mechanisms restrict Ca^(2+)signal synergistically.Together,our study provides theoretical insights into Bcl-2 regulation in IP_(3)R-mediated Ca^(2+)release,which may be instrumental for the successful development of therapies to target Bcl-2 for cancer treatment.