293results about How to "High absorption strength" patented technology

The invention provides 'core-shell-shell' rare earth upconversion nanoparticles (UCNPs) using Nd as a sensitizing agent. The rare earth UCNPs are characterized in that the shell layer of the rare earth UCNPs contains Nd<3+> and each layer contains Yb<3+>. The special microscopic nanostructure solves the problem about the quenching effect on upconversion fluorescence in an Nd doping process, so bright upconversion fluorescence can be obtained. Compared with the traditional Yb-sensitized UCNPs, the Nd-sensitized UCNPs have higher infrared absorption intensity so as to greatly improve upconversion efficiency and fluorescence. The Nd-sensitized UCNPs adopt 800-nanometer instead of 980-nanometer laser as an exciting light source, so the Nd-sensitized UCNPs have smaller overheating effect and stronger biological tissue penetrating power. Therefore, the novel rare earth upconversion material is expected to be widely applied in the field of biomedicines.

The invention discloses a flexible electromagnetic wave shielding and absorbing cloth and a production method thereof. The flexible electromagnetic wave shielding and absorbing cloth comprises a four-layer structure which sequentially comprises a chemical fiber fabric layer, an electromagnetic wave shielding layer, an electromagnetic wave absorbing layer and a flame-retardant and waterproof layer from bottom to top. The production method of the flexible electromagnetic wave shielding and absorbing cloth comprises the following steps: 1, drying the chemical fiber fabric; 2, preprocessing the chemical fiber fabric obtained in step 1; 3, plating the chemical fiber fabric obtained in step 2 with a layer of meta; 4, coating the metal layer plated chemical fiber fabric obtained in step 3 with a layer of a wave absorbing coating; and 5, coating the wave absorbing layer coated chemical fiber fabric obtained in step 4 with a layer of a flame-retardant and waterproof coating. The electromagnetic wave shielding and absorbing cloth has the advantages of wide wave absorption frequency band, high absorption intensity, flame retardation and waterproofing property, good flexibility, light weight and thin thickness, and can be applied to electromagnetic interference and electron strike prevention in the fields of electronic products and military devices.

The invention provides a draft tube-typed jet reactor and a method for preparing isocyanate with the reactor by a gas phase phosgenation process. A draft tube is arranged inside an inner feed tube of the draft tube-typed jet reactor to form a rotary stream which is reinforced into vortex flow, thus amine vapor and phosgene are quickly mixed and react to reduce the generation of by-products. In addition, by adopting a jet and absorption device, high-temperature gas discharged from the reactor is quickly cooled to a temperature at which the product is stable; meanwhile, negative pressure is provided for the system reaction process, thus avoiding a huge vacuum system.

The invention discloses a graphene aerogel and a preparation method and an application thereof, wherein the aerogel is prepared from the following method: (1) pre-reduction treatment: adding a reducing agent to a graphene oxide solution, mixing, carrying out ultrasonic dispersion, and carrying out pre-reduction treatment, to obtain a semi-reduction graphene hydrogel; (2) final reduction treatment:adding a reducing agent, carrying out ultrasonic treatment, and then carrying out final reduction treatment, to obtain a graphene hydrogel; and (3) acid / alkali soaking: placing the graphene hydrogelin an acid or alkali aqueous solution, soaking, washing the hydrogel to be neutral, sucking out the excess liquid, and carrying out freeze drying, to obtain the graphene aerogel. The graphene aerogelis applied to electromagnetic wave absorption materials. The graphene aerogel obtained by the method has small density and good integrality, and has a certain mechanical strength and resillency; the prepared wave absorbing material has good electromagnetic wave absorption performance, and the wave absorbing performance can be adjusted; and the method has the advantages of simple process, short production cycle, low cost and good benefits, and is suitable for industrialized production.

The invention relates to a preparation method of a chromium-doped ferrous alloy wave-absorbing material. The preparation method comprises the following steps: mixing raw materials: Fe, Nd and Cr according to a certain atom ratio, melting the metals in an arc furnace; then sealing the alloy sample in a vacuum quartz glass tube, then placing the sealed quartz glass tube in a high-temperature environment to carry out a further homogenization treatment, quenching, taking out the alloy sample, mechanically and primarily grinding the alloy sample in a mortar, then transferring the alloy powder to a stainless steel ball-milling tank, carrying out high-energy ball milling under the protection of gasoline, after a while, pouring out the gasoline, taking out the alloy sample powder, drying the powder in the air so as to obtain the alloy micropowder wave-absorbing material.

The invention relates to the technical field of microwave absorption and particularly relates to a graphene compounded wave absorbing material and a preparation method thereof. The graphene compounded wave absorbing material is prepared through uniformly compounding carbonyl iron and graphene. The preparation method comprises the steps: firstly, preparing graphite oxide by using an improved Hummers method, and then, uniformly dispersing the graphite oxide into a carbonyl iron dispersion solution; then, reducing the graphite oxide to graphene by using an ultrasonic reduction method, thereby preparing the graphene compounded wave absorbing material. Compared with the pure carbonyl iron and the pure graphene, the compounded wave absorbing material provided by the invention has the advantages that the wave absorbing performance is superior, the wave absorbing strength is high, the frequency band of wave absorbing is wide, and the density is relatively low; the compounded wave absorbing material has adjustability, high absorption at different frequencies is achieved through adjusting the mass ratio of the graphene to the carbonyl iron and the thickness of the compounded material.

The invention provides an alloy microwave absorbing material added with vanadium and a preparation method. The preparation method comprises the following steps: taking proper amounts of metal Fe, Nd and V of which the purities are higher than 99.5% respectively for dosage according to the atomic ratio of Fe17Nd2-xVx, wherein X is more than or equal to 0.1 and is less than or equal to 0.8; smelting into an alloy ingot by using a vacuum electric-arc furnace; performing vacuum sealing by using a quartz glass tube; inspecting the airtightness by soaking the glass tube in water; performing operations such as homogenization, quenching and mechanical preliminary pulverization; pouring the sample into a ball-milling jar, and performing ball-milling by using a planetary ball mill under the gasoline environment protection condition; pouring out the gasoline after the ball-milling is finished; taking out sample powder and drying, thus obtaining an alloy micro powder wave absorbing material.

The invention discloses switchable glass based on a subtractive color mixing method. The switchable glass comprises two opposite light transmission substrates, the space between the two light transmission substrates is packaged to form an adjustment region filled with liquid crystal mixtures, and the liquid crystal mixtures include photopolymerizable liquid crystal monomers, dichroic dyes, common dyes, photo-initiators and negative liquid crystals. When voltage is not applied, the negative liquid crystals are perpendicular to the light transmission substrates and arranged in a single-domain manner, and molecules of the dichroic dyes are similarly perpendicular to the light transmission substrates. As absorbed light of the dichroic dyes is the weakest and the dichroic dyes are colorless, light transmission rate is the highest at the moment. When the voltage is applied, the negative liquid crystals are turned to the direction parallel to the light transmission substrates, the dichroic dyes are driven to rotate in the turning process, the negative liquid crystals are parallel to the light transmission substrates and arranged in a multi-domain manner after turning as polymer networks are irregularly distributed, and the switchable glass is transformed from a light transmission state into a light scattering state and is in a colored fuzzy state according to the subtractive color mixing method.

The invention relates to the technical field of microwave absorption, in particular to a graphene-based ternary composite wave-absorbing material and a preparation method thereof. The preparation method comprises the steps of firstly, preparing silicon dioxide-coated carbonyl iron core-shell composite particles by using a sol-gel method, then preparing graphite oxide by using an improved Hummers method, evenly dispersing the graphite oxide into dispersion liquid of the silicon dioxide-coated carbonyl iron core-shell composite particles, and finally, using an ultrasonic reduction method to enable graphite oxide to be reduced into graphene so as to prepare the graphene-based ternary composite wave-absorbing material. The preparation method provided by the invention is simple and efficient; the prepared composite wave-absorbing material is more excellent in wave absorbing performance, high in wave absorbing strength, wide in wave absorbing bandwidth and smaller in density compared with a pure carbonyl iron binary composite wave-absorbing material and a pure graphene and carbonyl iron or graphene binary composite wave-absorbing material; the graphene-based ternary composite wave-absorbing material also has regulation performance, and can realize strong wave absorption under different frequencies by adjusting the thickness of a coating layer SiO2, the mass ratio of graphene to the coated core-shell composite particles and the thickness of the ternary composite material.

The invention belongs to the technical field of wave-absorbing materials, and discloses a light broadband multi-frequency-band strong-absorption double-layer structure honeycomb wave-absorbing plate and a preparation method thereof. The light broadband multi-frequency-band strong-absorption double-layer structure honeycomb wave-absorbing plate is sequentially provided with an upper-layer skin, a surface-layer wave-absorbing honeycomb core, a bonding layer, a bottom-layer wave-absorbing honeycomb core, a bottom-layer skin and a reflecting layer from top to bottom, wherein various layers are adhered, the surface of the surface-layer wave-absorbing honeycomb core is dipped with a first wave-absorbing coating material, the surface of the bottom-layer wave-absorbing honeycomb core is sprayed with a second wave-absorbing coating material, and the outer side of the second wave-absorbing coating material is dipped with the first wave-absorbing coating material. According to the invention, honeycomb is sprayed and dipped with the wave-absorbing coating material, and the impedance matching design is carried out on the upper-layer skin, the surface-layer wave-absorbing honeycomb, the bottom-layer wave-absorbing honeycomb, the bottom-layer skin and the reflecting layer, so that the wave-absorbing strength is further improved and the wave-absorbing frequency band is widened under the condition of meeting the environmental use requirements so as to widen the frequency band of the honeycomb wave-absorbing plate and improve the absorption peak strength of the honeycomb wave-absorbing plate.

Belonging to the field of packaging materials, the invention relates to an LED packaging material, its preparation method and application. The material is composed of the following components by weight: 100 parts of epoxy resin, 60 parts of a crosslinking agent, 2 parts of a crosslinking accelerant, 0.1-5 parts of an antioxidant, 0.05-0.25 part of an ultraviolet stabilizer, and 0.05-0.50 part of an ultraviolet absorber. In the invention, a sulfur-containing benzotriazole compound is adopted as the ultraviolet absorber, which has excellent performance and can reach a good synergistic effect with the antioxidant and the ultraviolet stabilizer, and can be used as the ultraviolet absorber of the LED packaging material. Compared with original ultraviolet absorbers, the ultraviolet absorber effectively enlarges the ultraviolet absorption wavelength and the absorption strength, thereby reducing the dosage of the ultraviolet absorber, lowering the cost, and improving the yellowing resistance of an adhesive film. The prepared LED adhesive film product has good stability, and has wide application prospects in industrial production.

The invention relates to praseodym or praseodym-europim doped strontium lithium silicate yellow-red fluorescent powder and a preparation method thereof. The fluorescent powder utilizes strontium lithium silicate as a medium, can be effectively triggered by blue light with the wavelength of 400-500nm by codope of the praseodym and europium, and has a doublet broadband transmission characteristic (the main peaks are respectively 580nm and 610nm); and the fluorescent powder can be triggered by blue light with the wavelength of 440-490nm to transmit strong red fluorescence (the main peak is a narrow band of 610nm) by single dope of praseodym. The chemical composition of the fluorescent powder has a general formula as Li2Sr1-x-ySiO4:xEu2+, yPr3+, wherein x is no less than 0 and no more than 0.02, so is y. The excitation spectrum of the fluorescent powder has good matching with a blue light LED chip, so the fluorescent powder can be used in assembly of a white light LED with a high color rendering index; and the preparation process is easy to control, and the basic equipment of the current fluorescent powder plants can be used for realizing industrialized production, thus the fluorescent powder is novel and has application potential.

The invention relates to a method for photocatalytic degradation of pesticide residues. The method is characterized by: taking butyl titanate, zinc acetate, urea and the like as raw materials, conducting co-precipitation to synthesize a ZnO / TiO2 composite nano-material with photocatalytic activity, spraying the composite nano-material on plants, and making use of sunlight irradiation to degrade pesticide residues. The material has high absorption strength and strong photocatalytic activity in both ultraviolet and visible ranges, and has the characteristics of obvious degradation effects, simple operation and low cost when used in pesticide residue degradation, thus having wide application and popularization value.

The invention discloses an efficient and absorbable honeysuckle chewing gum and a preparation method thereof. Honeysuckle powder is added to the universal chewing gum formula. The honeysuckle chewing gum also comprises oral cavity absorption enhancers accounting for 1-3% of the total mass of the formula. The oral cavity absorption enhancer comprises the following components by mass: 1-3% of chitosan, 2-6% of mint, 1-3% of vitamin B2, 20-60% of SiO2 and 30-70% of Carbomer. The ultramicro honeysuckle powder and the oral cavity absorption enhancers are added to the chewing gum, thus the honeysuckle chewing gum not only maintains the functions of the general chewing gums, but also adds the medicinal value of the chewing gum and has the functions of eliminating heat and purging fire and sterilizing and resisting inflammation. The active components of the honeysuckle are immediately fully absorbed in the oral cavity and simultaneously the bioavailability of the honeysuckle is improved.

The invention relates to the technical field of wave-absorbing materials, in particular to a preparation method of a silicon carbide / carbon hollow porous microsphere wave-absorbing material. The invention aims to solve the technical problems of large particle size and easy agglomeration of silicon carbide particles in the silicon carbide / carbon composite material prepared by the existing method. The method includes: mixing deionized water, anhydrous ethanol and ammonia water, adding a surfactant, resorcinol, a silicon source and a formaldehyde solution, stirring the substances uniformly at room temperature, then adding melamine, performing stirring, transferring the mixture into a high-temperature and high-pressure reactor for reaction, and conducting high temperature calcination; and thenperforming mixing with magnesium powder, conducting high temperature calcination in a nitrogen atmosphere, washing off redundant magnesium powder with hydrochloric acid, and carrying out washing anddrying. The silicon carbide / carbon hollow porous microsphere obtained by the method has good chemical homogeneity and large specific surface area, and can effectively avoid agglomeration and sinteringof silicon carbide particles. The material prepared by the method provided by the invention is used for making light and efficient wave-absorbing coatings.

The invention discloses a new application of kaempferol extractive and a sunscreen cosmetic containing kaempferol extractive, belonging to the technical field of Chinese traditional medicine and cosmetic, wherein kaempferol extractive has strong ultraviolet absorption in UV-B range, has strong absorption strength, can effectively absorb ultraviolet of sunlight so as to prevent human skin from sun red, sunburn and tanning, can heal photosensitive dermatitis, and can be used as sun screening component of sunscreen cosmetic to be combined with variable sun screening agents to prepare sunscreen skin-care cosmetic. The produced cosmetic has high sunscreen index and is safer than chemical sun screening agent, and has small possibility of allergy effectively. Kaempferol is special medicinal and edible plant at south area, having wide source and plantation in Guangdong, Guangxi and Yunnan.

The invention discloses a hierarchical structure hollow CNTs / Co / C fiber wave-absorbing material and a preparation method thereof, and belongs to the technical field of radar wave-absorbing materials.The method takes cotton fibers and Co-containing zeolite imidazole structure metal organic framework ZIF-67 nanoparticles as raw materials. ZIF-67 nanoparticles with a regular dodecahedron microstructure grow and coat the surfaces of the cotton fibers in situ, cotton fibers are carbonized into hollow carbon fibers through a high-temperature carbonization process in a reductive H2 / Ar mixed atmosphere, the pyrolysis of the ZIF-67 metal organic framework nanoparticles and the catalytic growth of the carbon nanotubes are realized so that the hollow CNTs / Co / C fiber wave-absorbing material with themicron carbon fiber-nanotube hierarchical structure is obtained, and under the conditions that the density is 0.02 g / cm<3> and the thickness is 2 mm, the maximum absorption intensity of electromagnetic waves at 14 GHz reaches -59.5 dB, and the effective absorption frequency band width reaches 6.2 GHz (11.8-18 GHz). The technical problems that a traditional wave-absorbing material is high in density, low in absorption strength and narrow in frequency band are solved.

The present invention provides a material with characteristics of fire retardation, thermal insulation and wave absorption. The material comprises a base layer, wherein the base layer is mesh fabric, both sides of the mesh fabric are coated with an adhesive coating layer, and the adhesive coating layer is a polyvinylchloride adhesive coating layer. The adhesive coating layer comprises a wave absorption agent, wherein the wave absorption agent comprises nickel-plated glass beads, and a mass ratio of the wave absorption agent powder to the adhesive is 0.17-1.85:1. The present invention further provides a preparation method for the material. According to the material with characteristics of fire retardation, thermal insulation and wave absorption in the present invention, the polyvinylchloride adhesive is added with the wave absorption agent, such that functions of fire retardation, thermal insulation and wave absorption can be concurrently provided; the material of the present invention can concurrently has functions of fire retardation and thermal insulation, and characteristics of high wave absorption strength, wide wave absorption frequency band, and small surface density; and the material of the present invention can be used for wave absorption defilading, electromagnetic shielding, and the like.

The present invention discloses a porous carbon-based electromagnetic absorbing agent. The porous carbon-based electromagnetic absorbing agent comprises a plurality of dispersive two-dimensional sheetstructures, each dispersive two-dimensional sheet structure is formed by formless porous carbon frame and a graphitization carton layer inlaid into the carbon framework, and the graphitization cartonlayer is a hollow ball housing shape. The present invention further discloses a preparation method of a porous carbon-based electromagnetic absorbing agent. The porous carbon-based electromagnetic absorbing agent is high in absorption intensity in an ultra low filling degree and low thickness compared with traditional absorbing materials and metal organic framework derivative electromagnetic absorbing materials, can effectively absorb bandwidth, and has an excellent absorbing property; and moreover, the preparation method is simple in technology and low in cost, does not need complex synthesis devices, does not need usage of virulent chemical reagents and is suitable for industrial large-scale production.

The invention relates to a graphene composite aerogel wave-absorbing material and a preparation method and application thereof. The material consists of graphene oxide, modifier and Fe3O4@C nanoparticles and has a three-dimensional network structure. The preparation method includes the following steps: (1) preparing a Fe3O4 by a solvothermal method, (2) agitating the Fe3O4 with a polymer monomer to obtain a Fe3O4 coated polymer, (3) carbonizing in an inert atmosphere to obtain Fe3O4@C, dispersing Fe3O4@C in an ethanol dispersion of graphene oxide, and performing a one-step alcohol thermal method to obtain the material. The material has no volume shrinkage, has high absorption intensity, effective absorption bandwidth, and excellent wave-absorbing performance at K-band, and has broad application potential and market prospect in the field of electromagnetic shielding and electromagnetic safety protection of communication equipment.

The invention relates to a method for synthesizing high molecular retanning dyeing auxiliary agents through enzyme catalysis, which comprises the following steps: dissolving p-aminobenzene sulfonic acid and 2, 3-dihydroxy naphthalene-6-sodium sulfonate into de-ionized water, using a sodium bicarbonate solution for regulating the pH value of the system, and finally, obtaining the retanning dyeing auxiliary agents through co-polymerization reaction carried out under the horse radish peroxidase (HRP) catalysis. The invention uses HRP as catalysts of the polymerization reaction, and the HRP has the advantages of high efficiency, high selectivity and environment protection when being used for catalyzing the polymerization. The invention has the advantages that phenols or arylamines can carry out polymerization in ortho positions or para positions of hydroxide groups and amino groups for forming a polymer with directly connected C-C structures and large pi conjugated systems, the formaldehyde pollution in the traditional synthesized retanning agents is avoided, and at the same time, the products with the conjugated systems contain a large number of auxochromic groups such as -NH2, -OH and -SO3H and the like. Retanning leather is full and soft, and the dye absorption rate is higher than 99 percent, and in addition, the retanning dyeing auxiliary agents have obvious dyeing aid effect.

The invention discloses a processing method of a wideband electromagnetic wave absorption suede fabric. The processing method comprises the following steps: weaving a dual-layer fabric by selecting and using conductive fiber blended yarns; diluting and uniformly mixing a wave absorbent with a flexible adhesive to prepare a wave absorption adhesive with good adhesion performance; soaking plush of a prepared one-sided suede fabric in the prepared wave absorption adhesive; performing pad-roll on the obtained suede fabric by a proper pressure and removing the excess wave absorption adhesive by extruding; baking the obtained suede fabric in a baking oven to prepare the special wideband electromagnetic wave absorption suede fabric. The wideband electromagnetic wave absorption suede fabric has the absorbed electromagnetic wave frequency range of 300 MHz to 40 GHz, can serve as an important biological health protection or facility safety protection product, and radically eliminates the harm caused by electromagnetic radiation.

The invention provides a nitrogen-doped and carbon-coated magnetic nanoparticle composite microspheres and a preparation method thereof, and belongs to the technical field of materials with an electromagnetic function. According to the method, a glycerin metal complex and a nitrogenous organic compound are taken as main raw materials. A monodispersed glycerin metal complex precursor is prepared according to a self-template method at first; then the surface of the precursor is coated to form a shell by virtue of in-situ polymerization for nitrogenous organic monomers, and a carbon source and anitrogen source are introduced; and finally, calcining is carried out under an inert gas, and a core is subjected to thermal decomposition to form magnetic nanoparticles while the shell is carbonizedto form nitrogen-doped carbon. The nitrogen-doped and carbon-coated magnetic nanoparticle composite microspheres are green and environment-friendly, and efficient and time-saving in preparation process, and suitable for being prepared in a large scale; the electromagnetic parameters of the composite microspheres and the sizes of the magnetic nanoparticles can be regulated and controlled by changing the mass ratio of metal salt to the nitrogenous organic monomers, and an annealing temperature, so that impedance matching and attenuation characteristic are achieved; and the prepared composite microspheres are high in absorption intensity for electromagnetic wave, wide in effective absorption frequency band, easy to prepare in a large scale, and capable of meeting many use needs.

The invention belongs to the technical field of preparation of composite materials and discloses a ferric oxide / bismuth oxybromide composite material and a preparation method and application thereof. The ferric oxide / bismuth oxybromide composite material is formed by ferric oxide nano-clusters depositing on the surfaces of bismuth oxybromide nano-sheets. The preparation method comprises the steps of adding an alkali solution into a ferric nitrate solution to obtain a ferric hydroxide colloidal solution, adding a KBr solution into a bismuth nitrate solution, performing mixing to obtain a mixed solution, dropwise adding the ferric hydroxide colloidal solution into the mixed solution and performing hydrothermal reaction to obtain the ferric oxide / bismuth oxybromide composite material. The preparation method has the advantages of being simple in preparation process and low in cost, having very good environmental protection benefits and the like, the prepared composite material has excellent photocatalytic performance and is widely applied to the field of photocatalytic degradation of dye wastewater, and the higher catalytic efficiency can be obtained.

The invention belongs to the field of electromagnetic wave absorbing materials, and particularly relates to a dodecylbenzene sulfonic acid doped PANI / MXene composite wave absorbing material and a preparation method thereof. The composite wave absorbing material is prepared by doping a polyaniline / MXene nano composite material with dodecylbenzene sulfonic acid. The method has the advantages of mildprocess conditions, low production cost, simple process and stable product quality, and is beneficial to industrial production.

A three-dimensional graphene sponge / Fe2O3 composite wave absorbing material and a preparation method thereof are disclosed and belong to the technical field of wave absorbing materials. Firstly, three-dimensional graphene is prepared through a template process and is then added into deionized water, the mixture is subjected to ultrasonic treatment to obtain a uniformly dispersed three-dimensionalgraphene sponge suspension, then an aqueous Fe<3+> solution is added into the suspension dropwise, and a reaction occurs at 70-95 DEG C after the pH value is adjusted with ammonia water. The structureand wave absorbing performance of the composite wave absorbing material are adjusted through controlling the using amount of FeCl3, the pH value, the reaction temperature and the reaction time. A graphene matrix of the composite wave absorbing material in which the graphene sponge is loaded with magnetic nanometer Fe2O3 particles has a mesoporous sponge structure, and the Fe2O3 particles are uniformly anchored and grow on the graphene sponge. The prepared composite wave absorbing material has characteristics of high wave absorbing intensity, effective absorption frequency bandwidth, low density, low thickness, and the like, and has important application value in the field of developing efficient and light-weight electromagnetic wave absorbing materials.

The invention discloses a ZnO / Fe / Fe3C / C (zinc oxide / iron / iron carbide / carbon) composite electromagnetic wave absorbent, and also discloses a preparation method of the ZnO / Fe / Fe3C / C composite electromagnetic wave absorbent. The preparation method comprises the following steps of preparing FeIII-MOF-5 by a reflux method: adding reaction materials of ferric acetylacetonate, zinc nitrate, terephthalic acid and PVP (polyvinyl pyrrolidone) into a mixed solvent of N,N-dimethylformamide and ethyl alcohol, completely dissolving, and refluxing at certain temperature; centrifuging, washing and drying a product after reaction, so as to obtain a precursor FeIII-MOF-5; calcining the precursor product under the inertia environment at the temperature of 550 to 750 DEG C, so as to obtain a final product. The porous composite electromagnetic wave absorbent has the characteristics that the absorbing strength is high at low thickness, and the frequency band of effective absorbing is broad; the excellent wave absorbing property is realized. The preparation method has the advantages that the technology is simple, the cost is low, the complicated synthesizing equipment is not needed, and the hypertoxic organic solvent is not needed.

The invention discloses a leveling and deepening fixing agent and a preparation method thereof. The leather leveling and deepening fixing agent is a dyeing assistant with the functions of leveling, deepening and fixing colors, and an assistant molecule comprises the groups of -NR2, -NH2, -NHR, -COONa, and the like and is a compound with an amphoteric structure. Under an alkaline condition, the molecule carries negative charge and has a leveling function for dyeing acid dye, the auxochromic groups of -NR2, -NH2, -NHR, and the like on the assistant molecule act on the dye to deepen the color andplay a deepening function. Under an acidic condition, the groups of -NR2, -NH2, -NHR, and the like have positive charge and play a fixing function for the acid dye. The assistant is a multifunctionalproduct, can play the functions of leveling, deepening and fixing colors for dying leather and can simplify a leather preparing technology.

The invention provides a dual-mode imaging probe with pH response. The chemical structural formula of the dual-mode imaging probe is as shown in the formula (I). In the formula (I), X represents -C(CH3)2-, -O-, -S- or -Se-; Y represents F, Cl, Br or I; R1 and R2 are independently selected from H atom, C1-18 alkyl or -SO3R5; R5 represents C1-18 alkyl or benzyl; R3 and R4 are independently selected from C1-18 alkyl or benzyl. When a pH of the probe is 3.5-10.0, the fluorescence intensity ratio of emission light at 760nm and 670nm is gradually enhanced along with the reduction of the pH; the absorption intensity ratio at 760nm and 680nm is gradually enhanced along with the reduction of the pH; 760nm / 680nm photo-acoustic signals are gradually enhanced along with the reduction of pH; the obvious pH-depended photo-acoustic signal variability is shown; pKa is 6.2. The dual-mode imaging probe is very applicable to detection of tumor pH I in both a fluorescence mode and a photo-acoustic mode. The invention also provides a preparation method and application of the probe.