Insights on advanced substrates for controllable fabrication of photoanodes toward efficient and stable photoelectrochemical water splitting

Conversion of solar energy into H_(2) by photoelectrochemical(PEC)water splitting is recognized as an ideal way to address the growing energy crisis and environmental issues.In a typical PEC cell,the construction of photoanodes is crucial to guarantee the high efficiency and stability of PEC reactions,which fundamentally rely on rationally designed semiconductors(as the active materials)and substrates(as the current collectors).In this review work,we start with a brief introduction of the roles of substrates in the PEC process.Then,we provide a systematic overview of representative strategies for the controlled fabrication of photoanodes on rationally designed substrates,including conductive glass,metal,sapphire,silicon,silicon carbide,and flexible substrates.Finally,some prospects concerning the challenges and research directions in this area are proposed.

Co/CoO heterojunction rich in oxygen vacancies introduced by O_(2) plasma embedded in mesoporous walls of carbon nanoboxes covered with carbon nanotubes for rechargeable zinc-air battery

Herein,Co/CoO heterojunction nanoparticles(NPs)rich in oxygen vacancies embedded in mesoporous walls of nitrogen-doped hollow carbon nanoboxes coupled with nitrogen-doped carbon nanotubes(P-Co/CoOV@NHCNB@NCNT)are well designed through zeolite-imidazole framework(ZIF-67)carbonization,chemical vapor deposition,and O_(2) plasma treatment.As a result,the threedimensional NHCNBs coupled with NCNTs and unique heterojunction with rich oxygen vacancies reduce the charge transport resistance and accelerate the catalytic reaction rate of the P-Co/CoOV@NHCNB@NCNT,and they display exceedingly good electrocatalytic performance for oxygen reduction reaction(ORR,halfwave potential[EORR,1/2=0.855 V vs.reversible hydrogen electrode])and oxygen evolution reaction(OER,overpotential(η_(OER,10)=377mV@10mA cm^(−2)),which exceeds that of the commercial Pt/C+RuO_(2) and most of the formerly reported electrocatalysts.Impressively,both the aqueous and flexible foldable all-solid-state rechargeable zinc-air batteries(ZABs)assembled with the P-Co/CoOV@NHCNB@NCNT catalyst reveal a large maximum power density and outstanding long-term cycling stability.First-principles density functional theory calculations show that the formation of heterojunctions and oxygen vacancies enhances conductivity,reduces reaction energy barriers,and accelerates reaction kinetics rates.This work opens up a new avenue for the facile construction of highly active,structurally stable,and cost-effective bifunctional catalysts for ZABs.

Ambient-Condition Strategy for Production of Hollow Ga_(2)O_(3)@rGO Crystalline Nanostructures Toward Efficient Lithium Storage

Crystallineγ-Ga_(2)O_(3)@rGO core-shell nanostructures are synthesized in gram scale,which are accomplished by a facile sonochemical strategy under ambient condition.They are composed of uniformγ-Ga_(2)O_(3)nanospheres encapsulated by reduced graphene oxide(rGO)nanolayers,and their formation is mainly attributed to the existed opposite zeta potential between the Ga_(2)O_(3)and rGO.The as-constructed lithium-ion batteries(LIBs)based on as-fabricatedγ-Ga_(2)O_(3)@rGO nanostructures deliver an initial discharge capacity of 1000 mAh g^(-1)at 100 mA g^(-1)and reversible capacity of 600 mAh g^(-1)under 500 mA g^(-1)after 1000 cycles,respectively,which are remarkably higher than those of pristineγ-Ga_(2)O_(3)with a much reduced lifetime of 100 cycles and much lower capacity.Ex situ XRD and XPS analyses demonstrate that the reversible LIBs storage is dominant by a conversion reaction and alloying mechanism,where the discharged product of liquid metal Ga exhibits self-healing ability,thus preventing the destroy of electrodes.Additionally,the rGO shell could act robustly as conductive network of the electrode for significantly improved conductivity,endowing the efficient Li storage behaviors.This work might provide some insight on mass production of advanced electrode materials under mild condition for energy storage and conversion applications.

Application of computer vision technology on raising sow and procreating of processing

This paper expounds the application of machine vision theory, composition and technology in the sow breeding process monitoring, auxiliary judgment, and growth of young monitoring. It also points out the problems and deficiency in the application of machine vision technology, and discusses the development trends and prospects of the machine vision technology in agricultural engineering. The application of machine vision is a process in which dynamic original image from the sows estrus is collected with a CCD camera, and then black and white ash three binarization image in adjournments of the threshold value is made by using image acquisition card, through the median filtering and gray processing. The practitioners can extract respective image information from the sow estrus, pregnancy and birth delivery. Applying the computer vision system in the sow farm effectively enhances the practitioners’ objectivity and precision in their efforts to assess the whole process of sow birth delivery.

Solid-state synthesis and ion transport characteristics of the β-KSbF_(4) for all-solid-state fluoride-ion batteries

All-solid-state fluoride ion batteries(FIBs)have been recently considered as a post-lithium-ion battery system due to their high safety and high energy density.Just like all solid-state lithium batteries,the key to the development of FIBs lies in room-temperature electrolytes with high ionic conductivity.β-KSbF_(4) is a kind of promising solid-state electrolyte for FIBs owing to its rational ionic conductivity and relatively wide electrochemical stability window at room temperature.However,the previous synthesis routes ofβ-KSbF_(4) required the use of highly toxic hydrofluoric acid and the ionic conductivity of as-prepared product needs to be further improved.Herein,the β-KSbF_(4) sample with an ionic conductivity of 1.04×10^(-4)s cm^(-1)(30°C)is synthesized through the simple solid-state route.In order to account for the high ionic conductivity of the as-synthesizedβ-KSbF_(4),X-ray diffraction(XRD),scanning electron microscopy(SEM),and energy dispersive X-ray spectroscopy(EDS)are used to characterize the physic-ochemical properties.The results show that the as-synthesizedβ-KSbF_(4) exhibits higher carrier concentra-tion of 1.0×10^(-6)S cm-Hz^(-1)K and hopping frequency of 1.31×10^(6)Hz at 30°C due to the formation of the fluorine vacancies.Meanwhile,the hopping frequency shows the same trend as the changes of ionic conductivity with the changes of temperature,while the carrier concentration is found to be almost con-stant.The two different trends indicate the hopping frequency is mainly responsible for the ionic conduc-tion behavior withinβ-KSbF_(4).Furthermore,the all-solid-state FIBs,in which Ag and Pb+PbF_(2) are adopted as cathode and anode,andβ-KSbF_(4) as fluoride ion conductor,are capable of reversible charge and discharge.The assembled FIBs show a discharge capacity of 108.4 mA h g^(-1) at 1st cycle and 74.2 mA h g^(-1) at 50th cycle.Based on an examination of the capacity decay mechanism,it has been found that deterioration of the electrolyte/electrode interface is an important reason for hindering the commer-cial application of FIBs.Hence,the in-depth comprehension of the ion transport characteristics inβ-KSbF_(4) and the interpretation of the capacity fading mechanism will be conducive to promoting development of high-performanceFIBs.

Improvement of ionic conductivity of solid polymer electrolyte based on Cu-Al bimetallic metal-organic framework fabricated through molecular grafting

A composite solid electrolyte comprising a Cu-Al bimetallic metal-organic framework(CAB),lithium salt(LiTFSI)and polyethylene oxide(PEO)was fabricated through molecular grafting to enhance the ionic conductivity of the PEO-based electrolytes.Experimental and molecular dynamics simulation results indicated that the electrolyte with 10 wt.%CAB(PL-CAB-10%)exhibits high ionic conductivity(8.42×10~(-4)S/cm at 60℃),high Li+transference number(0.46),wide electrochemical window(4.91 V),good thermal stability,and outstanding mechanical properties.Furthermore,PL-CAB-10%exhibits excellent cycle stability in both Li-Li symmetric battery and Li/PL-CAB-10%/LiFePO4 asymmetric battery setups.These enhanced performances are primarily attributable to the introduction of the versatile CAB.The abundant metal sites in CAB can react with TFSI~-and PEO through Lewis acid-base interactions,promoting LiTFSI dissociation and improving ionic conductivity.Additionally,regular pores in CAB provide uniformly distributed sites for cation plating during cycling.

Experimental Investigation of Wave-Current Loads on a Bridge Shuttle-Shaped Cap–Pile Foundation

To scrutinize the characteristics of wave-current loads on a bridge shuttle-shaped cap–pile foundation,a 1:125 test model was considered in a laboratory flume.The inline,transverse and vertical wave–current forces acting on the shuttle-shaped cap-pile group model were measured considering both random waves and a combination of random waves with a current.The experimental results have shown that the wave-current forces can be well correlated with the wave height,the wavelength,the current velocity,the incident direction and the water level in the marine environment.An increase in the current velocity can lead to a sharp increase in the inline and transverse wave-current forces,while the vertical wave-current force decreases.Moreover,the wave-current forces are particularly strong when a combination of high tide,strong wave and strong current is considered.

A critical review on direct catalytic hydrogasification of coal into CH_(4):catalysis process configurations,evaluations,and prospects

Coal catalytic hydrogasification(CCHG)is a straightforward approach for producing CH_(4),which shows advantages over the mature coal-to-CH_(4) technologies from the perspectives of CH_(4) yield,thermal efficiency,and CO_(2) emission.The core of CCHG is to make carbon in coal convert into CH_(4) efficiently with a catalyst.In the past decades,intensive research has been devoted to catalytic hydrogasification of model carbon(pitch coke,activated carbon,coal char).However,the chemical process of CCHG is still not well understood because the coal structure is more complicated,and CCHG is a combination of coal catalytic hydropyrolysis and coal char catalytic hydrogasification.This review seeks to shed light on the catalytic process of raw coal during CCHG.The configuration of suitable catalysts,operating conditions,and feedstocks for tailoring CH_(4) formation were identified,and the underlying mechanisms were elucidated.Based on these results,the CCHG process was evaluated,emphasizing pollutant emissions,energy efficiency,and reactor design.Furthermore,the opportunities and strategic approaches for CCHG under the restraint of carbon neutrality were highlighted by considering the penetration of“green”H2,biomass,and CO_(2) into CCHG.Preliminary investigations from our laboratories demonstrated that the integrated CCHG and biomass/CO_(2) hydrogenation process could perform as an emerging pathway for boosting CH_(4) production by consuming fewer fossil fuels,fulfilling the context of green manufacturing.This work not only provides systematic knowledge of CCHG but also helps to guide the efficient hydrogenation of other carbonaceous resources such as biomass,CO_(2),and coal-derived wastes.

Integrated Experimental and Simulation Investigation of Breakdown Voltage Characteristics Across Electrode Configurations in SF_(6) Circuit Breakers

This study investigates the breakdown voltage characteristics in sulfur hexafluoride(SF6)circuit breakers,employing a novel approach that integrates both experimental investigations and finite element simulations.Utilizing a sphere-sphere electrode configuration,we meticulously measured the relationship between breakdown voltage and electrode gap distances ranging from 1 cm to 4.5 cm.Subsequent simulations,conducted using COMSOL Multiphysics,mirrored the experimental setup to validate the model’s accuracy through a comparison of the breakdown voltage-electrode gap distance curves.The simulation results not only aligned closely with the experimental data but also allowed the extraction of detailed electric field strength,electric potential contours,and electric current flow curves at the breakdown voltage for gap distances extending from 1 to 4.5 cm.Extending the analysis,the study explored the electric field and potential distribution at a constant voltage of 72.5 kV for gap distances between 1 to 10 cm,identifying the maximum electric field strength.A comprehensive comparison of five different electrode configurations(sphere-sphere,sphere-rod,sphere-plane,rod-plane,rod-rod)at 72.5 kV and a gap distance of 1.84 cm underscored the significant influence of electrode geometry on the breakdown process.Moreover,the research contrasts the breakdown voltage in SF6 with that in air,emphasizing SF6’s superior insulating properties.This investigation not only elucidates the intricate dynamics of electrical breakdown in SF6 circuit breakers but also contributes valuable insights into the optimal electrode configurations and the potential for alternative insulating gases,steering future advancements in high-voltage circuit breaker technology.

Mechanism of Chrome-free Tanning with Tetra-hydroxymethyl Phosphonium Chloride

Tetra-hydroxymethyl phosphonium chloride （THPC） has been considered as an important chrome-free tanning agent. To understand the THPC tanning mechanism, the structure, charge distribution, activity and tanning ability of each phosphorous compound in THPC tanning system were studied, by ^31p NMR, FT-IR spectroscopy, differential scanning calorimetry （DSC） and computational chemistry method, etc. When pH raised to 6.0, the decomposition of THPC would take place, which results in a production of free formaldehyde, tri-hydroxymethyl phosphonium （TrHP） and tri-hydroxymethyl phosphine oxide （TrHPO）. At pH 9.0, THPC will be converted completely to TrHP and most TrHP is further oxidized into TrHPO. It is possible that, in reaction of phosphorous compounds and collagens, both P-C and C-O bonds would break simultaneously or individually. From molecular charge distribution and bond polar properties, it is deduced that, if P-C bonds break, the activity is in order of TrHPO 〉 THPC 〉 TrHE whereas if C--O bonds break, the order is TrHP 〉 THPC 〉 TrHPO. It is more possible that P--C bonds will break in reaction with collagen, and TrHPO may be more active in the THPC tanning system. The results of tanning and DSC also prove the above conclusion. Furthermore, the fact that the shrinkage temperature of THPC tanned leather was below 70℃ when basified to pH 5.0 or lower suggests that the hydroxymethyl groups of THPC and TrHP are less possible to combine directly with amino groups of collagen.

Microstructure and mechanical properties of high strength Mg−15Gd−1Zn−0.4Zr alloy additive-manufactured by selective laser melting process

In order to verify the feasibility of producing Mg−rare earth(RE)alloy by selective laser melting(SLM)process,the microstructure and mechanical properties of Mg−15Gd−1Zn−0.4Zr(wt.%)(GZ151K)alloy were investigated.The results show that fine grains(~2μm),fine secondary phases and weak texture,were observed in the as-fabricated(SLMed)GZ151K Mg alloy.At room temperature,the SLMed GZ151K alloy has a yield strength(YS)of 345 MPa,ultimate tensile strength(UTS)of 368 MPa and elongation of 3.0%.After subsequent aging(200℃,64 h,T5 treatment),the YS,UTS and elongation of the SLMed-T5 alloy are 410 MPa,428 MPa and 3.4%,respectively,which are higher than those of the conventional cast-T6 alloy,especially with the YS increased by 122 MPa.The main strengthening mechanisms of the SLMed GZ151K alloy are fine grains,fine secondary phases and residual stress,while after T5 treatment,the YS of the alloy is further enhanced by precipitates.

Differences and Similarities of Photocatalysis and Electrocatalysis in Two-Dimensional Nanomaterials:Strategies,Traps,Applications and Challenges

Photocatalysis and electrocatalysis have been essential parts of electrochemical processes for over half a century.Recent progress in the controllable synthesis of 2D nanomaterials has exhibited enhanced catalytic performance compared to bulk materials.This has led to significant interest in the exploitation of 2D nanomaterials for catalysis.There have been a variety of excellent reviews on 2D nanomaterials for catalysis,but related issues of differences and similarities between photocatalysis and electrocatalysis in 2D nanomaterials are still vacant.Here,we provide a comprehensive overview on the differences and similarities of photocatalysis and electrocatalysis in the latest 2D nanomaterials.Strategies and traps for performance enhancement of 2D nanocatalysts are highlighted,which point out the differences and similarities of series issues for photocatalysis and electrocatalysis.In addition,2D nanocatalysts and their catalytic applications are discussed.Finally,opportunities,challenges and development directions for 2D nanocatalysts are described.The intention of this review is to inspire and direct interest in this research realm for the creation of future 2D nanomaterials for photocatalysis and electrocatalysis.

Synthesis and Crystal Structure of the Diiron Azadithiolate Complex [(μ-SCH_2)_2NPh]Fe_2(CO)5(Ph_2PCH_2PPh_2)

Reaction of [（μ-SCH2）2NPh]Fe2（CO）6 with Ph2PCH2PPh2 in the presence of Me3NO·2H2O gave the title complex [（μ-SCH2）2NPh]Fe2（CO）5（Ph2PCH2PPh2）（1）in 78% yield.The new complex 1 was characterized by elemental analysis,spectroscopy and X-ray crys-tallography.It crystallizes in triclinic,space group P1 with a = 10.832（2）,b = 12.003（2）,c = 15.579（3）,V = 1785.6（6）3,Z = 2,C32H26Fe2NO5PS2,Mr = 819.40,Dc = 1.524 g/cm3,μ（MoKα）= 1.064 mm-1,F（000）= 840,T = 113（2）K,the final R = 0.0543 and wR = 0.1218 for 6203 observed reflections（I 2σ（I））.The Ph2PCH2PPh2 ligand resides in an axial position of the square-pyramidal coordination sphere of the Fe atom and trans to the benzene ring in order to reduce the steric repulsion between Ph2PCH2PPh2 and the benzene ring.

Controllable Construction of Bifunctional CoxP@N,P-Doped Carbon Electrocatalysts for Rechargeable Zinc–Air Batteries

The exploration of cheap,efficient,and durable bifunctional electrocatalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is highly desired to push forward the commercialization of rechargeable metal–air batteries.Here,bifunctional ORR/OER electrocatalysts based on CoxP(0<x<2,i.e.,Co_(2)P,Co_(2)P/CoP mixture,and CoP)nanoparticles(NPs)anchored on N,P-doped carbon framework(Co_(x)P@NPC)are developed via one-step carbonization of the mixture of as-synthesized ZIF-67 and melamine–phytic acid supermolecular aggregate(MPSA).The stoichiometric ratio of resultant Co_(x)P NPs can be rationally designed by adjusting the introduced ratio of ZIF-67 to MPSA,enabling their fabrication in a controlled manner.It is found that the as-synthesized Co_(2)P@NPC exhibits the best bifunctional ORR/OER activity among the Co_(x)P@NPC analogues,with a reversible oxygen electrode index(ΔE=E_(j10)−E_(1/2))down to~0.75 V.The constructed Zn–air battery based on Co_(2)P@NPC delivers a peak power density of 157 mW cm^(−2) and an excellent charge-discharge stability with negligible voltage decay for 140 h at 10 mA cm^(−2),superior to those based on Pt/C+RuO_(2) and most Co_(x)P-based electrodes ever reported.

Kinetics of Burning Side Reaction in the Liquid-phase Oxidation of p-Xylene

During the liquid-phase oxidation of p-xylene,over-oxidation of reactant,intermediates and solvent to carbon dioxide and carbon monoxide is generally known as the burning side reaction.Batch and semi-continuous experiments were carried out,and the experimental data of the burning side reaction were analyzed and reported in this paper.The results showed that the rates of burning side reactions were proportional to the rates of the main reaction,but decreased with the increasing concentrations of reactant and intermediates.The inter-stimulative and competitive relationship between the burning side reaction and the main reaction was confirmed,and the rates of the burning side reaction could be described with some key indexes of the main reaction.According to the mechanism of the side reactions and the kinetics model of main reaction which were proposed and tested in the previous papers,a kinetic model of the burning side reactions involving some key indexes of the main reaction was developed,and the parameters were determined by data fitting of the COx rate curves.The obtained kinetic model could describe the burning side reactions adequately.

Approximate merging of B-spline curves and surfaces

Applying the distance function between two B-spline curves with respect to the L2 norm as the approximate error, we investigate the problem of approximate merging of two adjacent B-spline curves into one B-spline curve. Then this method can be easily extended to the approximate merging problem of multiple B-spline curves and of two adjacent surfaces. After minimizing the approximate error between curves or surfaces, the approximate merging problem can be transformed into equations solving. We express both the new control points and the precise error of approximation explicitly in matrix form. Based on homogeneous coordinates and quadratic programming, we also introduce a new framework for approximate merging of two adjacent NURBS curves. Finally, several numerical examples demonstrate the effectiveness and validity of the algorithm.

Boosting solar water oxidation activity of BiVO_(4) photoanode through an efficient in-situ selective surface cation exchange strategy

The sluggish kinetics for water oxidation is recognized as one of the major problems for the unsatisfied photoelectrochemical(PEC) performance. Herein, we developed a feasible strategy based on in-situ selective surface cation exchange, for activating surface water oxidation reactivity toward boosted PEC water oxidation of BiVO_(4) photoanodes with fundamentally improved surface charge transfer. The asconstructed Co/BiVO_(4) photoanodes exhibit 2.6 times increase in photocurrent density with superior stability, in comparison to those of pristine counterpart. Moreover, the faradaic efficiency of as-fabricated photoanode can be up to ~ 95% at 1.23 V(vs. RHE). The unique selective replacement of Bi by Co on the surface could modify the electronic structure of BiVO_(4) with reduced energy barrier of the deprotonation of OH^(+) to O, thus favoring the overall excellent PEC performance of Co/BiVO_(4) photoanode.

Detection of diabetic retinopathy in its early stages using textural features of optical coherence tomography angiography

The aim of this study is to detect whether the quantitative textural features of optical coherencetomography angiography (OCTA) images can be used to detect the eyes in the early stage ofdiabetic retinopathy (DR) from eyes with diabetes and no DR (NDR). Textural features includingfractal dimension, contrast, correlation, entropy, energy, and homogeneity were calculatedfrom the OCTA images. The Student's t-test was performed to identify the textural featuresthat can be able to detect DR in the early stage. The area under the receiver operating characteristic(AUROC) curves, sensitivity, and specicity were calculated between the study groups.Our results indicated that the fractal dimension in ICP and SVP and the correlation in SVCshowed the statistical signicance between mild NPDR patients and NDR patients. The ROCanalysis results showed that the AUROC of the fractal dimension in ICP was 0.736 with 0.773sensitivity and 0.700 specicity. The cuto® point in ICP was 2.616. The OCTA-based fractaldimension was able to discriminate diabetic eyes with early retinopathy from healthy and NDRwith higher sensitivity and specicity. The OCTA-based correlation showed the power to differentiatethe mild NPDR eyes from the normal healthy and diabetic eyes. These results suggestthat texture-based features of OCTA have the potential to assist in the assessment of therapeuticinterventions to prevent early DR in diabetic subjects.

Synthesis,Structure and Electric Property of a 3D Supramolecular Co^ⅡCoordination Complex

The title compound, [Co(C16H10N2S4)2(H2O)4](C14H9N2O4)2(1,C16H10N2S4=4-pyridine-tetrathiafulvalene-4-pyridine and C14 H9 N2 O4 = 4-(4-carboxyphenyl)diazenyl)benzoate),has been successfully synthesized under hydrothermal conditions. The structure was determined by elemental analyses and single-crystal X-ray diffraction analysis. Moreover, the conductivity property of compound 1 was investigated. Compound 1 crystallizes in triclinic system, space group P1 with a = 6.4006(3), b = 7.1818(4), c = 33.0932(14) ?, α = 89.261(4), β = 86.530(3), γ = 66.642(4)°, V =1393.90(12) ?3, Z = 1, C60 H46 N8 O12 S8 Co, M3 r = 1386.46, Dc = 1.652 g/cm, μ = 0.684 mm-1 and F(000) = 713. The final R = 0.0411 and wR = 0.0810 for 3936 observed reflections with I > 2σ(I).Compound 1 contains one-half of the complex cation with the CoI I ion located on an inversion center,and one 4-(4-carboxyphenyl)diazenyl)benzoate counter anion. The Co atom has a N2 O4 octahedral coordination. Complex 1 forms a three-dimensional supramolecular network and a semiconducting behavior is observed with srt= 0.04 S·cm-1.

Improved source assessment of Si,Al and related mineral components to PM_(10) based on a daily sampling procedure

Samples obtained from an industrialized valley in the East Alpine region were collected daily for a half year and analyzed using X-ray fluorescence to examine the elements Si, Al, Fe, Ca, Mg, Na, K, Zn, P, S and Cl. Some factors affecting the changes of these elements were considered, including time, elemental correlations, weekday, weekend and seasonal changes. Diagnostic analysis provided an insight into a decoupling behavior that occursin siliceous and carbonates minerals. A decrease in Si and Al and an increase in carbonates, Na, K, Zn and P were observed during the cold season. However, a consistently high correlation of Si and Al was observed in all seasons. It was established that such high levels originated from street surface abrasion. The increase in variability and absolute levels of carbonates during the cold season was demonstrated by adding carbonates to the street surface as gritting material to increase the grip on snowy surfaces. A marked increase in Na and Cl was observed in winter which may have been caused by thaw salt that is widely used in winter in Austria. This was associated with a significant increase in K, Zn, and P in the cold season that was the result of domestic space heating with wood. PM10 levels in December were 12 μ/m^3 and were higher than levels detected in July. It was established that such high levels originated from mineral oxides, wood smoke, and inorganic ionic material（s）.