Enhancing I^(0)/I^(-)Conversion Efficiency by Starch Confinement in Zinc-lodine Battery

The redox couple of I^(0)/I^(-)in aqueous rechargeable iodine–zinc(I^(2)-Zn)batteries is a promising energy storage resource since it is safe and cost-effective,and provides steady output voltage.However,the cycle life and efficiency of these batteries remain unsatisfactory due to the uncontrolled shuttling of polyiodide(I_(3)^(-)and I_(5)^(-))and side reactions on the Zn anode.Starch is a very low-cost and widely sourced food used daily around the world.“Starch turns blue when it encounters iodine”is a classic chemical reaction,which results from the unique structure of the helix starch molecule–iodine complex.Inspired by this,we employ starch to confine the shuttling of polyiodide,and thus,the I^(0)/I^(-)conversion efficiency of an I^(2)-Zn battery is clearly enhanced.According to the detailed characterizations and theoretical DFT calculation results,the enhancement of I^(0)/I^(-)conversion efficiency is mainly originated from the strong bonding between the charged products of I_(3)^(-)and I_(5)^(-)and the rich hydroxyl groups in starch.This work provides inspiration for the rational design of high-performance and low-cost I^(2)-Zn in AZIBs.

Reshaping Li–Mg hybrid batteries:Epitaxial electrodeposition and spatial confinement on MgMOF substrates via the lattice‐matching strategy

The emergence of Li–Mg hybrid batteries has been receiving attention,owing to their enhanced electrochemical kinetics and reduced overpotential.Nevertheless,the persistent challenge of uneven Mg electrodeposition remains a significant impediment to their practical integration.Herein,we developed an ingenious approach that centered around epitaxial electrocrystallization and meticulously controlled growth of magnesium crystals on a specialized MgMOF substrate.The chosen MgMOF substrate demonstrated a robust affinity for magnesium and showed minimal lattice misfit with Mg,establishing the crucial prerequisites for successful heteroepitaxial electrocrystallization.Moreover,the incorporation of periodic electric fields and successive nanochannels within the MgMOF structure created a spatially confined environment that considerably promoted uniform magnesium nucleation at the molecular scale.Taking inspiration from the“blockchain”concept prevalent in the realm of big data,we seamlessly integrated a conductive polypyrrole framework,acting as a connecting“chain,”to interlink the“blocks”comprising the MgMOF cavities.This innovative design significantly amplified charge‐transfer efficiency,thereby increasing overall electrochemical kinetics.The resulting architecture(MgMOF@PPy@CC)served as an exceptional host for heteroepitaxial Mg electrodeposition,showcasing remarkable electrostripping/plating kinetics and excellent cycling performance.Surprisingly,a symmetrical cell incorporating the MgMOF@PPy@CC electrode demonstrated impressive stability even under ultrahigh current density conditions(10mAcm^(–2)),maintaining operation for an extended 1200 h,surpassing previously reported benchmarks.Significantly,on coupling the MgMOF@PPy@CC anode with a Mo_(6)S_(8) cathode,the assembled battery showed an extended lifespan of 10,000 cycles at 70 C,with an outstanding capacity retention of 96.23%.This study provides a fresh perspective on the rational design of epitaxial electrocrystallization driven by metal–organic framework(MOF)substrates,paving the way toward the advancement of cuttingedge batteries.

Multiscale confinement nitridation in molybdenum carbide for efficient hydrogen production

The molybdenum carbide(Mo_(2)C)has been regarded as one of the most cost-efficient and stable electrocatalyst for the hydrogen evolution reaction(HER)by the virtue of its Pt-like electronic structures.However,the inherent limitation of high density of empty valence band significantly reduces its catalytic reactivity by reason of strong hydrogen desorption resistance.Herein,we propose a multiscale confinement synthesis method to design the nitrogen-rich Mo_(2)C for modulating the band structure via decomposing the pre-coordination bonded polymer in a pressure-tight tube sealing system.Pre-bonded c/N-Mo in the coordination precursor constructs a micro-confinement space,enabling the homogeneous nitrogenization in-situ happened during the formation of Mo_(2)C.Simultaneously,the evolved gases from the precursor decomposition in tube sealing system establish a macro-confinement environment,preventing the lattice N escape and further endowing a continuous nitridation.Combining the multiscale confinement effects,the nitrogen-rich Mo2C displays as high as 25%N-Mo concentration in carbide lattice,leading to a satisfactory band structure.Accordingly,the constructed nitrogen-rich Mo_(2)C reveals an adorable catalytic activity for HER in both alkaline and acid solution.It is anticipated that the multiscale confinement synthesis strategy presents guideline for the rational design of electrocatalysts and beyond.

Quantum confinement of carriers in the type-I quantum wells structure

Quantum confinement is recognized to be an inherent property in low-dimensional structures.Traditionally,it is believed that the carriers trapped within the well cannot escape due to the discrete energy levels.However,our previous research has revealed efficient carrier escape in low-dimensional structures,contradicting this conventional understanding.In this study,we review the energy band structure of quantum wells along the growth direction considering it as a superposition of the bulk material dispersion and quantization energy dispersion resulting from the quantum confinement across the whole Brillouin zone.By accounting for all wave vectors,we obtain a certain distribution of carrier energy at each quantized energy level,giving rise to the energy subbands.These results enable carriers to escape from the well under the influence of an electric field.Additionally,we have compiled a comprehensive summary of various energy band scenarios in quantum well structures relevant to carrier transport.Such a new interpretation holds significant value in deepening our comprehension of low-dimensional energy bands,discovering new physical phenomena,and designing novel devices with superior performance.

Measurements of Carrier Confinement at β-FeSi_2-Si Heterojunction by Electroluminescence

A Si p-π-n diode with β-FeSi 2 particles embedded in the unintentionally doped Si (p--type) was designed for determining the band offset at β-FeSi 2-Si heterojunction.When the diode is under forward bias,the electrons injected via the Si n-p- junction diffuse to and are confined in the β-FeSi 2 particles due to the band offset.The storage charge at the β-FeSi 2-Si heterojunction inversely hamper the further diffusion of electrons,giving rise to the localization of electrons in the p--Si near the Si junction,which prevents them from nonradiative recombination channels.This results in electroluminescence (EL) intensity from both Si and β-FeSi 2 quenching slowly up to room temperature.The temperature dependent ratio of EL intensity of β-FeSi 2 to Si indicates the loss of electron confinement following thermal excitation model.The conduction band offset between Si and β-FeSi 2 is determined to be about 0 2eV.

双壁波纹钢管混凝土构件短柱轴压力学性能

为改善空心钢筋混凝土柱(HRC)的使用与受力性能,提出一种双壁波纹钢管混凝土(CFDCST)构件。本文共进行了4个大尺寸双壁波纹钢管混凝土短柱与2个空心钢筋混凝土短柱的轴压试验,关键试验参数为试件类型与波纹钢管类型。分析构件的破坏模式,对比不同参数下构件的承载力、峰值应变、延性系数等关键力学指标,获得荷载-波纹钢管应变关系曲线以揭示试件的约束机理并验证外波纹钢管类型的影响。试验结果表明:外波纹钢管可为夹层混凝土提供约束作用,且螺旋角越小,外波纹钢管的约束作用越强;内波纹钢管则主要为夹层混凝土内壁提供有效支撑,以保持截面的完整性。名义约束效应系数与空心率相近时,由于咬口滑移影响,大螺旋角双壁波纹钢管混凝土比小螺旋角双壁波纹钢管混凝土的峰值应力、峰值应变与延性系数分别降低15.5%、21.8%与16.7%。在总用钢量相近的情况下,小螺旋角双壁波纹钢管混凝土柱的承载力、峰值应变与延性系数分别比空心钢筋混凝土柱提高10.6%、36.2%与50.0%。基于试验结果,检验了3种典型承载力公式的适用性,并提出了相应设计建议。

A 1.3μm Low-Threshold Edge-Emitting Laser with AlInAs-Oxide Confinement Layers

A 1.3μm low-threshold edge-emitting AlGaInAs multiple-quantum-well(MQW) laser with AlInAs-oxide confinement layers is fabricated.The Al-contained waveguide layers upper and low the active layers are oxidized as current-confined layers using wet-oxidation technique.This structure provides excellent current and optical confinement,resulting in 12.9mA of a low continuous wave threshold current and 0.47W/A of a high slope efficiency of per facet at room temperature for a 5-μm-wide current aperture.Compared with the ridge waveguide laser with the same-width ridge,the threshold current of the AlInAs-oxide confinement laser has decreased by 31.7% and the slope efficiency has increased a little.Both low threshold and high slope efficiency indicate that lateral current confinement can be realized by oxidizing AlInAs waveguide layers.The full width of half maximum angles of the Al-InAs-oxide confinement laser are 21.6° for the horizontal and 36.1° for the vertical,which demonstrate the ability of the AlInAs oxide in preventing the optical field from spreading laterally.

Numerical analysis of confinement effect on crack propagation mechanism from a flaw in a pre-cracked rock under compression

In many situations rocks are subjected to biaxial loading and the failure process is controlled by the lateral confinement stresses. The importance of confinement stresses has been recognized in the literature by many researchers, in particular, its influence on strength and on the angle of fracture, but still there is not a clear description for the influence of confining stress on the crack propagation mechanism of rocks. This paper presents a numerical pro- cedure for the analysis of crack propagation in rock-like ma- terials under compressive biaxial loads. Several numerical simulations of biaxial tests on the rock specimen have been carried out by a bonded particle model （BPM） and the influ- ence of confinement on the mechanism of crack propagation from a single flaw in rock specimens is studied. For this purpose, several biaxial compressive tests on rectangular spec- imens under different confinement stresses were modeled in （2 dimensional particle flow code） PFC2D. The results show that wing cracks initiate perpendicular to the flaw and trend toward the direction of major stress, however, when the lat- eral stresses increase, this initiation angle gets wider. Also it is concluded that in addition to the material type, the initiation direction of the secondary cracks depends on confine- ment stresses, too. Besides, it is understood that secondary cracks may be produced from both tensile and shear mechanisms.

Recent progress on confinement of polysulfides through physical andchemical methods

With high theoretical energy density and the natural abundance of S, lithium-sulfur （Li-S） batteries areconsidered to be the promising next generation high-energy rechargeable energy storage devices. How-ever, issues including electronical insulation of S, the lithium polysulfides （LiPSs） dissolution and the shortcycle lifespan have prevented Li-S batteries from being practical applied. Feasible settlements of confiningLiPSs to reduce the loss of active substances and improve the cycle stability include wrapping sulfur withcompact layers, designing matrix with porous or hollow structures, adding adsorbents owning stronginteraction with sulfur and inserting polysulfide barriers between cathodes and separators. This reviewcategorizes them into physical and chemical confinements according to the influencing mechanism. Withfurther discussion of their merits and flaws, synergy of the physical and chemical confinement is believedto be the feasible avenue that can guide Li-S batteries to the practical application.

Dielectric Confinement Effect on Calculating the Band Gap of PbSe Quantum Dots

Considering the dielectric confinement effect on excitonics of PbSe quantum dots （QDs）, a correction factor in the wave function was introduced to propose a new band gap calculation model for QDs. The modified model showed great consistency with the experimental data, especially in small size range. According to the variation of confined barrier, the band gap calculation model of PbSe QDs was analyzed in different solvents. The calculating results showed that the modified model was almost solvent-independent, which was consistent with our experimental results and related reports.

Effects of confinement on rock mass modulus:A synthetic rock mass modelling(SRM) study

The main objective of this paper is to examine the influence of the applied confining stress on the rock mass modulus of moderately jointed rocks（well interlocked undisturbed rock mass with blocks formed by three or less intersecting joints）. A synthetic rock mass modelling（SRM） approach is employed to determine the mechanical properties of the rock mass. In this approach, the intact body of rock is represented by the discrete element method（DEM）-Voronoi grains with the ability of simulating the initiation and propagation of microcracks within the intact part of the model. The geometry of the preexisting joints is generated by employing discrete fracture network（DFN） modelling based on field joint data collected from the Brockville Tunnel using LiDAR scanning. The geometrical characteristics of the simulated joints at a representative sample size are first validated against the field data, and then used to measure the rock quality designation（RQD）, joint spacing, areal fracture intensity（P21）, and block volumes. These geometrical quantities are used to quantitatively determine a representative range of the geological strength index（GSI）. The results show that estimating the GSI using the RQD tends to make a closer estimate of the degree of blockiness that leads to GSI values corresponding to those obtained from direct visual observations of the rock mass conditions in the field. The use of joint spacing and block volume in order to quantify the GSI value range for the studied rock mass suggests a lower range compared to that evaluated in situ. Based on numerical modelling results and laboratory data of rock testing reported in the literature, a semi-empirical equation is proposed that relates the rock mass modulus to confinement as a function of the areal fracture intensity and joint stiffness.

Sandwiching Sulfur into the Dents Between N,O Co-Doped Graphene Layered Blocks with Strong Physicochemical Confinements for Stable and High-Rate Li-S Batteries

The development of lithium-sulfur batteries(LSBs)is restricted by their poor cycle stability and rate performance due to the low conductivity of sulfur and severe shuttle effect.Herein,an N,O co-doped graphene layered block(NOGB)with many dents on the graphene sheets is designed as effective sulfur host for high-performance LSB s.The sulfur platelets are physically confined into the dents and closely contacted with the graphene scaffold,ensuring structural stability and high conductivity.The highly doped N and O atoms can prevent the shuttle effect of sulfur species by strong chemical adsorption.Moreover,the micropores on the graphene sheets enable fast Li^+transport through the blocks.As a result,the obtained NOGB/S composite with 76 wt%sulfur content shows a high capacity of 1413 mAh g^-1 at 0.1 C,good rate performance of 433 mAh g^-1 at 10 C,and remarkable stability with 526 mAh g^-1 at after 1000 cycles at 1 C(average decay rate:0.038%per cycle).Our design provides a comprehensive route for simultaneously improving the conductivity,ion transport kinetics,and preventing the shuttle effect in LSBs.

Experimental investigations on mechanical performance of rocks under fatigue loads and biaxial confinements

In this research,a series of biaxial compression and biaxial fatigue tests were conducted to investigate the mechanical behaviors of marble and sandstone under biaxial confinements.Experimental results demonstrate that the biaxial compressive strength of rocks under biaxial compression increases firstly,and subsequently decreases with increase of the intermediate principal stress.The fatigue failure characteristics of the rocks in biaxial fatigue tests are functions of the peak value of fatigue loads,the intermediate principal stress and the rock lithology.With the increase of the peak values of fatigue loads,the fatigue lives of rocks decrease.The intermediate principal stress strengthens the resistance ability of rocks to fatigue loads except considering the strength increasing under biaxial confinements.The fatigue lives of rocks increase with the increase of the intermediate principal stress under the same ratio of the fatigue load and their biaxial compressive strength.The acoustic emission(AE)and fragments studies showed that the sandstone has higher ability to resist the fatigue loads compared to the marble,and the marble generated a greater number of smaller fragments after fatigue failure compared to the sandstone.So,it can be inferred that the rock breaking efficiency and rock burst is higher or severer induced by fatigue loading than that induced by monotonous quasi-static loading,especially for hard rocks.

Heavy Metal Detection in Soils by Laser Induced Breakdown Spectroscopy Using Hemispherical Spatial Confinement

Spatial confinement has great potential for Laser Induced Breakdown Spectroscopy （LIBS） instruments after it has been proven that it has the ability to enhance the LIBS signal strength and repeatability. In order to achieve in-situ measurement of heavy metals in farmland soils by LIBS, a hemispherical spatial confinement device is designed and used to collect plasma spectra, in which the optical fibers directly collect the breakdown spectroscopy of the soil samples. This device could effectively increase the stability of the spectrum intensity of soil. It also has other advantages, such as ease of installation, and its small and compact size. The relationship between the spectrum intensity and the laser pulse energy is studied for this device. It is found that the breakdown threshold is 160 cm-2, and when the laser fluence increases to 250 J/cm2, the spectrum intensity reaches its maximum. Four different kinds of laser pulse energy were set up and in each case the limits of detection of Cd, Cu, Ni, Pb and Zn were calculated. The results show that when the laser pulse fluence was 2.12 GW/cm2, we obtained the smallest limits of detection of these heavy metals, which are all under 10 mg/kg. This device can satisfy the needs of heavy metal in-situ detection, and in the next step it will be integrated into a portable LIBS instrument.

Confinement effect of carbon nanotubes on the product distribution of selective hydrogenation of cinnamaldehyde

The catalytic activity of metal catalysts can be modulated by confinement within the channels of carbon nanotubes(CNTs).Here,we show that the product distribution of cinnamaldehyde hydrogenation can be modified by confinement of Ru nanoparticles in CNTs.A catalyst composed of Ru nanoparticles dispersed on the exterior walls of CNTs gave hydrocinnamaldehyde as product.In contrast,confinement of the Ru nanoparticles within CNT channels facilitated hydrogenation of C=O bonds and complete hydrogenation,and both cinnamyl alcohol and hydrocinnamyl alcohol formed in addition to hydrocinnamaldehyde.High‐resolution transmission electron microscopy,Raman spectroscopy,hydrogen temperature‐programmed reduction,and hydrogen temperature‐programmed desorption were used to investigate the characteristics of the catalysts.The results indicate that the different interactions between the confined Ru nanoparticles and the exterior and interior walls of the CNTs,as well as spatial restriction and enrichment within the narrow channels likely play important roles in modulation of the product distribution.

Novel confinement combustion method of nanosized WC/C for efficient electrocatalytic oxygen reduction

Nanosized tungsten carbide(WC)/carbon(C)catalyst was synthesized via a novel ultra-rapid confinement combustion synthesis method.The amount of activated carbon(AC)plays an important role in the morphology and structure,controlling both the precursor and final powder.The WC particles synthesized inside the pores of the AC had been 10-20 nm because of the confinement of the pore structure and the large specific surface area of AC.When used for oxygen reduction performance,the half-wave potential was−0.24 V,and the electron transfer number was 3.45,indicating the main reaction process was the transfer of four electrons.The detailed electrocatalytic performance and underlying mechanism were investigated in this work.Our study provides a novel approach for the design of catalysts with new compositions and new structures,which are significant for promoting the commercialization of fuel cells.

Effect of cylindrical cavity height on laserinduced breakdown spectroscopy with spatial confinement

In this paper, we present a study on the spatial confinement effect of laser-induced plasma with a cylindrical cavity in laser-induced breakdown spectroscopy （LIBS）. The emission intensity with the spatial confinement is dependent on the height of the confinement cavity. It is found that, by selecting the appropriate height of cylindrical cavity, the signal enhancement can be significantly increased. At the cylindrical cavity （diameter = 2 mm） with a height of 6 mm, the enhancement ratio has the maximum value （approximately 8.3）, and the value of the relative standard deviation （RSD） （7.6%） is at a minimum, the repeatability of LIBS signal is best. The results indicate that the height of confinement cavity is very important for LIBS technique to reduce the limit of detection and improve the precision.

The Matrix Stiffness and Physical Confinement of Hydrogel Microchannel Jointly Induce the Mesenchymal-Amoeboid Transition for Cancer Cell Migration

The migration mode transition of cancer cell enhances its invasive capability and the drug resistance,where physical confinement of cell microenvironment has been revealed to induce the mesenchymal-amoeboid transition(MAT).However,most existing studies are performed in PDMS microchannels,of which the stiffness is much higher than that of most mammalian tissues.Therefore,the amoeboid migration transition observed in these studies is actually induced by the synergistic effect of matrix stiffness and confinement.Since the stiffness of cell microenvironment has been reported to influence the cell migration in 2D substrate,the decoupling of stiffness and confinement effects is thus in need for elucidating the underlying mechanism of MAT.However,it is technically challenging to construct microchannels with physiologically relevant stiffness and channel size,where existing microchannel platforms with physiological relevance stiffness are all with>10μm channel width.Such size is too wide to mimic the physical confinement that migrating cancer cells confront in vivo,and also larger than the width of PDMS channel,in which the MAT of cancer cell was observed.Therefore,an in vitro cell migration platform,which could mimic both stiffness and confinement of the native physical microenvironment during cancer metastasis,could profoundly contribute to researches on cancer cell migration and cellular mechanotransduction.In this paper,we overcome the limitations of engineering soft materials in microscale by combining the collagen-alginate hydrogel with photolithography.This enables us to improve the accuracy of molded microchannel,and thus successfully construct a 3D microchannel platform,which matches the stiffness and width ranges of native environmental confinement that migrating cancer cells confront in vivo.The stiffness(0.3~20 kPa),confinement(channel width:3.5~14μm)and the adhesion ligand density of the microchannel can be tuned independently.Interestingly,using this platform,we observed that the migration speed of cancer cell is influenced by the synergistic effect of channel stiffness and width,and the increasing stiffness reverses the effect of channel width on the migration speed of cancer cells.In addition,MAT has a strong correlation with the channel stiffness.These findings make us reconsider the widely accepted hypothesis:physical confinement can induce MAT.Actually,this transition can only occur in stiff confined microenvironment not in soft one.For soft microchannels,the compliance of the channel walls could cause little cell/nucleus deformation,and the MAT could not be induced.To further investigate the mechanism of MAT,we developed a computational model to simulate the effect of nucleus deformation on MAT.With the model,we found that deforming the cell nuclear by decreasing the nucleus stiffness will reduce the cellmigration speed.This implies that nuclear stiffness plays an important role in the regulation of cancer migration speed and thus MAT in microchannels.The effect of channel stiffness on MAT and migration speed as observed in our experiment could partially explain previous findings reported in the literature,where the increasing matrix stiffness of tumor microenvironment promotes cancer metastasis.Our observations thus highlight the critical role of cell nuclear deformation not only in MAT,but also in regulating cellular mechanotransduction and cell-ECM interactions.This developed platform is capable of mimicking the native physical microenvironment during metastasis,providing a powerful tool for high-throughput screening applications and investigating the interaction between cancer migration and biophysical microenvironment.

Effect of confinement on the three-phase equilibrium of water-oil-CO_(2)mixtures in nanopores

Accurate characterization of fluid phase behavior is an important aspect of CO_(2) enhanced shale oil recovery.So far,however,there has been little discussion about the nanopore confinement effect,including adsorption and capillarity on the phase equilibrium of water-oil-CO_(2) mixtures.In this study,an improved three-phase flash algorithm is proposed for calculating the phase behavior of water-oil-gas mixture on the basis of an extended Young-Laplace equation and a newly developed fugacity calculation model.The fugacity model can consider the effect of water-oil-gas adsorption on phase equilibrium.A water-Bakken oil-CO_(2) mixture is utilized to verify the accuracy of the flash algorithm and investigate the confinement effect.Results show that the confinement effect promotes the transfer of all components in the vapor phase to other phases,while the transfer of water,CO_(2),and lighter hydrocarbons is more significant.This leads to a large decrease,a large increase,and a small increase in the mole fraction of the vapor,oleic,and aqueous phases,respectively.When the confinement effect is considered,the density difference of vaporoleic phases decreases,and the interfacial tension of vapor-oleic phases decreases;however,the density difference of vapor-aqueous phases increases,the interfacial tension of vapor-aqueous phases still decreases.

Revisiting the Role of Physical Confinement and Chemical Regulation of 3D Hosts for Dendrite-Free Li Metal Anode

Lithium metal anode has been demonstrated as the most promising anode for lithium batteries because of its high theoretical capacity,but infinite volume change and dendritic growth during Li electrodeposition have prevented its practical applications.Both physical morphology confinement and chemical adsorption/diffusion regulation are two crucial approaches to designing lithiophilic materials to alleviate dendrite of Li metal anode.However,their roles in suppressing dendrite growth for long-life Li anode are not fully understood yet.Herein,three different Ni-based nanosheet arrays(NiO-NS,Ni_(3)N-NS,and Ni_(5)P_(4)-NS)on carbon cloth as proof-of-concept lithiophilic frame-works are proposed for Li metal anodes.The two-dimensional nanoarray is more promising to facilitate uniform Li^(+)flow and electric field.Compared with the NiO-NS and the Ni_(5)P_(4)-NS,the Ni_(3)N-NS on carbon cloth after reacting with molten Li(Li-Ni/Li_(3)N-NS@CC)can afford the strongest adsorption to Li+and the most rapid Li+diffusion path.Therefore,the Li-Ni/Li_(3)N-NS@CC electrode realizes the lowest overpotential and the most excellent electrochemical performance(60 mA cm^(−2)and 60 mAh cm^(−2)for 1000 h).Furthermore,a remarkable full battery(LiFePO_(4)||Li-Ni/Li_(3)N-NS@CC)reaches 300 cycles at 2C.This research provides valuable insight into designing dendrite-free alkali metal batteries.