The use of carbon-based particle electrodes in three-dimensional electrode reactors for wastewater treatment

The use of three-dimensional(3D)electrodes in water treatment is competitive because of their high catalytic efficiency,low energy consumption and promising development.The use of particle electrodes is a key research focus in this technology.They are usually in the form of particles that fill the space between the cathode and anode,and the selection of materials used is important.Carbon-based materials are widely used because of their large specific surface area,good adsorption performance,high chemical stability and low cost.The principles of 3D electrode technology are introduced and recent research on its use for degrading organic pollutants using carbon-based particle electrodes is summarized.The classification of particle electrodes is introduced and the challenges for the future development of carbon-based particle electrodes in wastewater treatment are discussed.

Photo-rechargeable batteries and supercapacitors:Critical roles of carbon-based functional materials

As a clean and renewable energy source,solar energy is a competitive alternative to replace conventional fossil fuels.Nevertheless,its serious fluctuating nature usually leads to a poor alignment with the actual energy demand.To solve this problem,the direct solar-to-electrochemical energy conversion and storage have been regarded as a feasible strategy.In this context,the development of high-performance integrated devices based on solar energy conversion parts(i.e.,solar cells or photoelectrodes)and electrochemical energy storage units(i.e.,rechargeable batteries or supercapacitors[SCs])has become increasingly necessary and urgent,in which carbon and carbon-based functional materials play a fundamental role in determining their energy conversion/storage performances.Herein,we summarize the latest progress on these integrated devices for solar electricity energy conversion and storage,with special emphasis on the critical role of carbon-based functional materials.First,principles of integrated devices are introduced,especially roles of carbon-based materials in these hybrid energy devices.Then,two major types of important integrated devices,including photovoltaic and photoelectrochemicalrechargeable batteries or SCs,are discussed in detail.Finally,key challenges and opportunities in the future development are also discussed.By this review,we hope to pave an avenue toward the development of stable and efficient devices for solar energy conversion and storage.

Specializing liquid electrolytes and carbon-based materials in EDLCs for low-temperature applications

Electric double-layer capacitors(EDLCs) are emerging technologies to meet the ever-increasing demand for sustainable energy storage devices and systems in the 21 st Century owing to their advantages such as long lifetime, fast charging speed and environmentally-friendly nature, which play a critical part in satisfying the demand of electronic devices and systems. Although it is generally accepted that EDLCs are suitable for working at low temperatures down to-40℃, there is a lack of comprehensive review to summarize the quantified performance of EDLCs when they are subjected to low-temperature environments. The rapid and growing demand for high-performance EDLCs for auxiliary power systems in the aeronautic and aerospace industries has triggered the urge to extend their operating temperature range,especially at temperatures below-40℃. This article presents an overview of EDLC’s performance and their challenges at extremely low temperatures including the capability of storing a considerable amount of electrical energy and maintaining long-term stability. The selection of electrolytes and electrode materials is crucial to the performance of EDLCs operating at a desired low-temperature range. Strategies to improve EDLC’s performance at extremely low temperatures are discussed, followed by the future perspectives to motivate more future studies to be conducted in this area.

Enhancing the cycling stability of Na-ion batteries by bonding MoS2 on assembled carbon-based materials

Room temperature Na-ion batteries(SIBs) show great potential for use as renewable energy storage systems.However, the large-scale application of SIBs has been hindered by the lack of an ideal SIBs anode material. We synthesized MoS2 on carbonized graphene-chitosan(G-C) using the hydrothermal method. The strong interaction between the MoS2 and the G-C greatly improved the electron transport rate and maintained the structural stability of the electrode, which lead to both an excellent rate capability and long cycle stability. The G-C monolith was proven to enhance the electrical conductivity of the composites and served as a matrix for uniformly dispersing active MoS2 nanosheets(NSs), as well as being a buffer material to adapt to changes in volume during the cycle.Serving as an anode material for SIBs, the MoS2-G-C electrode showed good cycling stability(527.3mAh g-1 at100 m A g-1 after 200 cycles), excellent rate capability, and a long cycle life(439.1 m Ah g-1 at 1 A g-1 after 200 cycles).

A New Type of Multielements-Doped,Carbon-based Materials Characterized by High-thermoconductiv-ity,Low Chemical Sputtering,Low RES Yield and Exposure to Plasma

Low-Z materials, such as carbon-based materials and Be, are major plasma-facing material (PFM) for current, even in future fusion devices. In this paper, a new type of multielement-doped carbon-based materials developed are presented along with experimental re-sults of their properties. The results indicate a decrease in chemical sputtering yield by one order of magnitude, a decrease in both thermal shock resistance and radiation-enhanced sublimation, an evidently lower temperature desorption spectrum, and combined properties of exposing to plasma.

Adsorption and Adsorption-Photocatalytic Degradation of VOCs Based on Carbon Materials

Adsorption and the combination of adsorption and photocatalysis are prospective strategies for treating lowconcentrationvolatile organic compounds (VOCs). Behind the adsorption technology of VOC treatments are carbon-basedmaterials with large surface areas and high VOC uptake. This review summarizes the research progress in carbon-basedadsorbents and adsorbent-photocatalysts for VOC removal. Firstly, the VOC adsorption performances of various carbonmaterials, including activated carbon, activated carbon fiber, biochar, graphene and its derivatives, and carbon nanotubes,are summarized, and the adsorption mechanism of VOCs on carbon materials is analyzed. Then, the VOC adsorptionphotocatalyticproperties of composites comprised of different carbon materials and photocatalysts are presented. Finally,perspectives on the adsorption and adsorption-photocatalysis of VOCs via carbon materials are proposed. This reviewprovides an optimal reference for the research and development of adsorbents and adsorption-photocatalysts of VOCs.

Recent Advances in Carbon-Based Current Col lectors/Hosts for Alkali Metal Anodes

The urgent demand for high-energy-density storage systems evokes the research upsurge on the alkali metal batteries with high theoretical capacities.However,the utilization of alkali metal anodes,including Li,Na,and K,is significantly hindered by notorious dendrite growth,undesirable corrosion,and unstable solid electrolyte interface.In order to resolve these issues,the carbon materials for the rational design of current collector/host that can regulate the plating/stripping behavior of alkali metal have been exploited.These carbon-based current collectors/hosts are featured with many pivotal advantages,including mechanical integrity to accommodate the volume change,superior electronic/ionic conductivity,large available surface area,and rich functionalization chemistries to increase the affinity to alkali metal.In this review,the recent progress on various dimensional carbon-based current collectors/hosts with different chemical components in stabilizing the alkali metal anodes through the regulation of initial deposition and subsequent growth behavior during plating/stripping process is provided.The nanostructured carbon scaffolds with self-affinity to alkali metals,as well as the carbon frameworks with internal/external affinitive sites to alkali metals,catalogued by various dimensions,are discussed in this review.Therefore,these appealing strategies based on the carbon-based current collectors/hosts can provide a paradigm for the realization of high-energy-density alkali metal batteries.

The nonlocal solution of two parallel cracks in functionally graded materials subjected to harmonic anti-plane shear waves

In this paper, the dynamic interaction of two parallel cracks in functionally graded materials （FGMs） is investigated by means of the non-local theory. To make the analysis tractable, the shear modulus and the material density are assumed to vary exponentially with the coordinate vertical to the crack. To reduce mathematical difficulties, a one-dimensional non-local kernel is used instead of a twodimensional one for the dynamic problem to obtain stress fields near the crack tips. By use of the Fourier transform, the problem can be solved with the help of two pairs of dual integral equations, in which the unknown variables are the jumps of displacements across the crack surfaces. To solve the dual integral equations, the jumps of displacements across the crack surfaces are expanded in a series of Jacobi polynomials. Unlike the classical elasticity solutions, it is found that no stress singularity is present at the crack tips. The non-local elastic solutions yield a finite hoop stress at the crack tips. The present result provides theoretical references helpful for evaluating relevant strength and preventing material failure of FGMs with initial cracks. The magnitude of the finite stress field depends on relevant parameters, such as the crack length, the distance between two parallel cracks, the parameter describing the FGMs, the frequency of the incident waves and the lattice parameter of materials.

Estimation of Critical Temperature of Thermal Explosion for Energetic Materials Based on Non-isothermal Kinetic Equation dα/dt =A_0 exp(bT)[1+(T–T_0 )b]f(α)

Critical temperature（Tb） of thermal explosion for energetic materials is estimated from Semenov＇s thermal explosion theory and the non-isothermal kinetic equation da/dt=Aoexp（bT）[1＋（T-T0）b][（a） deduced via reasonable hypotheses, where To is the initial point of the deviation from the baseline of DSC curve. The final formula is （Tb-Te0）{ 1＋1/[1＋（ Tb-T00）b]}=1. We can easily obtain the initial temperature（T0/） and onset temperature（Tci） from the non-isothermal DSC curves, the values of Too and Tc0 from the equation TOi or ei=T00 or c0＋α1βi＋a2βi^2＋…＋aL-2L-2βiL-2, i=1,2,…L, the value of b from the equation： In[β/（Tei-T0i）]=ln[A0/G（a）]＋bTei, so as to calculate the value of Tb. The result obtained with this method coincides completely with the value of Tb obtained by Hu-Yang-Liang-Wu method.

ANALYSIS OF THE DYNAMIC BEHAVIOR OF A GRIFFITH PERMEABLE CRACK IN PIEZOELECTRIC MATERIALS WITH THE NON-LOCAL THEORY

The dynamic behavior of a Griffith permeable crack under harmonic anti-plane shear waves in the piezoelectric materials is investigated by use of the non-local theory. To overcome the mathematical difficulties, a one-dimensional non-local kernel is used instead of a two-dimensional one for the anti-plane dynamic problem to obtain the stress and the electric displacement near the crack tips. By means of Fourier transform, the problem can be solved with a pair of dual integral equations that the unknown variable is the jump of the displacement across the crack surfaces. These equations are solved with the Schmidt method and numerical examples are provided. Contrary to the previous results, it is found that no stress and electric displacement singularities are present at the crack tip. The finite hoop stress and the electric displacement depend on the crack length, the lattice parameter of the materials and the circle frequency of the incident waves. This enables us to employ the maximum stress hypothesis to deal with fracture problems in a natural way.

Non-isothermal microwave leaching kinetics and absorption characteristics of primary titanium-rich materials

The non-isothermal leaching kinetics of primary titanium-rich material by microwave heating was investigated,and the temperature-pressure curves of leaching system and microwave absorption characteristics of mixture solutions before and after leaching were measured.The research of non-isothermal kinetics was evaluated by the leaching rate of Fe and the total apparent velocity equation of the non-isothermal kinetics of leaching for primary titanium-rich material by microwave heating was obtained.It is shown from the temperature-pressure curves that the high temperature and high pressure of closed leaching system are favorable to the enhancement of the leaching rate of Fe.Microwave absorption characteristics of mixture solutions before and after leaching show that there are abrupt changes of microwave absorption characteristics for 15%HCl solution and the mixture solution after leaching by 20%HCl.

POSTBUCKLING RESPONSE OF CANTILEVER BEAMS OF NON-LINEAR ELASTIC MATERIAL SUBJECTED TO SUBTANGENTIAL FOLLOWER FORCES

This paper deals with the problem of the postbuckling response of a thin cantilever beam ofnon-linear material, subjected to subtangential follower forces. Based on the well-knownBernoulli-Euler bending moment-curvature relation, the proposed problem is reduced to a specialeigenvalue problem of non-linear differential equation. An approximate solution is achieved byusing a simple and very effective technique, which leads to reliable results even in the case of verylarge deflections. The initial postbuckling path depending on the subtangential follower forces inequilibrium is then obtained. Moreover, the individual and coupling effect of the subtangential fol-lower force, the material non-linearity and the beam slenderness ratio on the initial postbucklingpath are also discussed in detail.

A stabilized complementarity formulation for nonlinear analysis of 3D bimodular materials

Bi-modulus materials with different mechanical responses in tension and compression are often found in civil,composite, and biological engineering. Numerical analysis of bimodular materials is strongly nonlinear and convergence is usually a problem for traditional iterative schemes. This paper aims to develop a stabilized computational method for nonlinear analysis of 3D bimodular materials. Based on the parametric variational principle, a unified constitutive equation of 3D bimodular materials is proposed, which allows the eight principal stress states to be indicated by three parametric variables introduced in the principal stress directions.The original problem is transformed into a standard linear complementarity problem（LCP） by the parametric virtual work principle and a quadratic programming algorithm is developed by solving the LCP with the classic Lemke＇s algorithm. Update of elasticity and stiffness matrices is avoided and, thus, the proposed algorithm shows an excellent convergence behavior compared with traditional iterative schemes.Numerical examples show that the proposed method is valid and can accurately analyze mechanical responses of 3D bimodular materials. Also, stability of the algorithm is greatly improved.

A Novel Uniplanar Multi-Electrode Capacitive Sensor for In-Situ Weathering Damage Detection of Nonmetallic Materials

A uniplanar capacitive sensor with 5-electrodes on one plane substrate and a large reflector electrode,was designed to get the corresponding capacitance information for weathering damage detection of non-metallic materials exposed to a service environment.A 2-D finite-element method was employed to simulate the electric potential distribution and capacitance measurements for the sensor.2 marble slabs,one was healthy and the other was notched,were experimentally detected.Both the simulation and the preliminary experimental results show that the measured capacitances decrease after weathering damage occurs in nonmetallic material.The reflector can enlarge the sensitive depth.The weathering assessment of nonmetallic materials can be done by processing the measured capacitances.The proposed approach can effectively detect the weathering damage of nonmetallic material and can be practically used for in-situ weathering damage evaluation.

Non-local damage and fracture model of rock and concrete-like materials

In view of the non-local phenomena appearing in the rock and concrete-like materials, the non-local damage and fracture model of rock and concrete-like materials was established through non-local method of Gaussian weighting function. The result indicates that, the stress of one point in the material is correlated not only to its strain history, but also to the interaction of the points in its certain adjacent region of the material. Based on the established non-local model, the numerical simulation of notch containing three-point bending beam was carried out. The results show that the grid sensitivities have been avoided and the fracture direction of the material has not been influenced by the grid shape, and the model proposed can be used to better simulate the damage developing process of the rock and concrete-like materials.

Need for new materials,biofunctionalization and nonsurgical heart valve technology

Transition from non-surgical heart valve defects repair from bench to bedside is a reality.Some biological material-based designs for transcatheter aortic valve implantation are ready for use.Their drawback,however is their unknown functional as well as structural durability.Moreover,research on new non-biological materials is essential to replace classical animal-derived sources of human heart valve prostheses.

ANALYSIS OF DRAWING UNDER LUBRICATION OF NON-NEWTONIAN LUBRICATING MATERIALS

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Basic solution of two parallel non-symmetric permeable cracks in piezoelectric materials

The behavior of two parallel non-symmetric cracks in piezoelectric materials subjected to the anti-plane shear loading was studied by the Schmidt method for the permeable crack electric boundary conditions. Through the Fourier transform, the present problem can be solved with two pairs of dual integral equations in which the unknown variables are the jumps of displacements across crack surfaces. To Solve the dual integral equations, the jumps of displacements across crack surfaces were directly expanded in a series of Jacobi polynomials. Finally, the relations between electric displacement intensity factors and stress intensity factors at crack tips can be obtained. Numerical examples are provided to show the effect of the distance between two cracks upon stress and electric displacement intensity factors at crack tips. Contrary to the impermeable crack surface condition solution, it is found that electric displacement intensity factors for the permeable crack surface conditions are much smaller than those for the impermeable crack surface conditions. At the same time, it can be found that the crack shielding effect is also present in the piezoelectric materials.

Restrictions on the Material Coefficients in the Constitutive Theories for Non-Classical Viscous Fluent Continua

This paper considers conservation and balance laws and the constitutive theories for non-classical viscous fluent continua without memory, in which internal rotation rates due to the velocity gradient tensor are incorporated in the thermodynamic framework. The constitutive theories for the deviatoric part of the symmetric Cauchy stress tensor and the Cauchy moment tensor are derived based on integrity. The constitutive theories for the Cauchy moment tensor are considered when the balance of moments of moments 1) is not a balance law and 2) is a balance law. The constitutive theory for heat vector based on integrity is also considered. Restrictions on the material coefficients in the constitutive theories for the stress tensor, moment tensor, and heat vector are established using the conditions resulting from the entropy inequality, keeping in mind that the constitutive theories derived here based on integrity are in fact nonlinear constitutive theories. It is shown that in the case of the simplest linear constitutive theory for stress tensor used predominantly for compressible viscous fluids, Stokes' hypothesis or Stokes'?assumption has no thermodynamic basis, hence may be viewed incorrect. Thermodynamically consistent derivations of the restrictions on various material coefficients are presented for non-classical as well as classical theories that are applicable to nonlinear constitutive theories, which are inevitable if the constitutive theories are derived based on integrity.

DYNAMIC FRACTURE MECHANICS ANALYSIS FOR COMPOSITE MATERIAL WITH MATERIAL NON-HOMOGENEITY IN THICKNESS DIRECTION

The problem considered here is the response of a non-homogeneouscomposite material containing some cracks subjected to dynamicloading. It is assumed that the composite material is or- thotropicand all material properties depend only on the coordinate y (alongthe thickness direcion). In the analysis, the elastic region isdivided into a number of plies of infinite length. The materialproperties are taken to be constants for each ply. By utilizing theLaplace transform and Fourier transform technique, the generalsolutions for plies are derived.