33results about How to "Improved size distribution" patented technology

A large number of properties of nanostructures depend on their size, shape and many other parameters. As the size of a nanostructure decreases, there is a rapid change in many properties. When the nanostructure is completely destroyed, those properties essentially disappear. Systems based on changes in properties of nanostructures due to the destruction of nanostructures are proposed. The systems can be used for monitoring the total exposure to organic, inorganic, organometallic and biological compounds and agents using analytical methods.

A catalyst composition that includes a support material having an improved particle-size distribution is provided. Processes for producing polyolefin composition also are provided. Polymers and films also are provided. An example of a catalyst composition is a supported multi-transition-metal catalyst composition that includes: (a) at least two catalyst components selected from the group consisting of: a nonmetallocene catalyst component and a metallocene catalyst component; (b) a support material that has a D₅₀ of less than about 30 microns and a particle size distribution having a D₉₀/D₁₀ ratio of less than about 6; and (c) an activator.

An improved process for synthesising discrete high definition silver nanoparticles in large batch volumes. The method enables the reproducible production of silver nanoparticles having a predetermined size, shape and surface chemistry. The process comprises the steps of forming silver seeds from a reagent comprising, a silver source and a reducing agent; and growing the thus formed silver seeds into silver nanoparticles wherein the step forming silver seeds and/or growing the silver seeds into silver nanoparticles is performed using micro fluidic flow chemistry.

The invention provides a preparation method of polyimide foam plastic. The method comprises the steps as follows: firstly, after dianhydride is mixed with low-level aliphatic alcohol, an esterification reaction is performed, and a diacid diester solution is obtained; then the obtained diacid diester solution is mixed with polymerized monomer amine and polyamic acid powder to obtain a mixed solution; and finally, the obtained mixed solution is sequentially subjected to foaming and thermal imidization after concentration to obtain the polyimide foam plastic. The invention further provides the polyimide foam plastic and the preparation method thereof, and the method comprises the step that polyamic acid powder is added when dianhydride and isocyanate are used for preparing the polyimide foam plastic. According to the invention, the polyamide acid powder serves as a nucleating agent, so that a cell of an objected formed by foaming of polyimide is fine and smooth, that is, the size distribution of the cell is improved, the cell uniformity is better, then the flexibility performance and the like of the polyimide foam plastic are improved; meanwhile, the heat resistance is not influenced; and besides, the preparation method of the polyimide foam plastic is concise in processing, and low in energy consumption and production cost.

The invention especially relates to a method for preparing nano-crystals containing tellurium, selenium or sulfur, wherein the method uses stable phosphine-containing organic compounds (such as dioctylphosphine oxide and the like) having similar structures as a novel solvent of tellurium powder, selenium powder or sulfur powder and uses a novel tellurium, selenium or sulfur solution as a precursor to prepare a plurality of nano-crystals containing tellurium, selenium or sulfur. The method avoids high cost and high risk caused by a case that tributylphosphine (TBP) or trioctylphosphine (TOP) is commonly and internationally used at present to dissolve tellurium, selenium or sulfur in order to generate the tellurium, selenium or sulfur precursor. The synthetic method has the advantages of safe operation, easy operation, and good repeatability, and medicines used in the method are routine and stable and have low toxicities. The nano-crystals containing tellurium, selenium or sulfur reaches even exceeds nano-crystals containing tellurium, selenium or sulfur synthesized through using flammable and explosive compounds comprising TOP/TBP and the like in quality. The method has very high application values in the laboratory field and the industrial production field.

The invention relates to a preparation method for a multi-level structured molybdenum disulfide microsphere negative electrode material of a lithium battery. The method comprises the following steps of firstly, dissolving sodium molybdate dehydrate and urea in deionized water, and stirring the mixed solution for 15-60 minutes; secondly, dropwise adding hydrochloric acid to adjust a pH value to be 0-1, transferring the mixed solution in a reaction kettle taking polytetrafluoroethene as a substrate, preserving the mixed solution at 150-250 DEG C for 1 to 40 hours, naturally cooling the mixed solution to a room temperature, taking out the mixed solution after reaction, washing sediments after centrifugal separation, placing the mixed solution in an electrothermal blowing dry box for drying, taking out the mixed solution and placing the mixed solution in a mortar to grind into fine powder; and finally preparing the multi-level structured molybdenum disulfide microsphere negative electrode material of the lithium battery. With the adoption of a simple test method and process steps, the multi-level structured molybdenum disulfide microspheres with relatively small grain sizes (200-250 nanometers) and which are uniformly distributed are prepared, and the negative electrode material has excellent electrochemical performance.

The invention provides a high-performance methanol synthesis catalyst and a preparation method thereof and belongs to the technical field of methanol catalysts. The catalyst comprises 50-80 parts by mass of copper-zinc-aluminum active component oxide and 25-40 parts by mass of a carrier compound, wherein the copper-zinc-aluminum active component oxide comprises 40-70 parts by mass of copper oxide,10-40 parts by mass of zinc oxide and 0-20 parts by mass of aluminum oxide; and the carrier compound comprises 80-100 parts by mass of zinc metaaluminate, 0-20 parts by mass of magnesium metaaluminate, 0-8 parts by mass of manganese metaaluminate, 0-7 parts by mass of calcium metaaluminate, 0-5 parts by mass of strontium metaaluminate and 0-5 parts by mass of barium metaaluminate. The invention further provides the preparation method of the methanol catalyst. The high-performance methanol synthesis catalyst and the preparation method thereof, provided by the invention, have the beneficial effects that as the catalyst preparation process and a carrier compound adding mode are optimized, the high-performance methanol synthesis catalyst is a high-performance catalyst suitable for industriallarge-scale methanol synthesis; the prepared catalyst by the preparation method provided by the invention has better high and low temperature activity, heat resistance and aging resistance and has higher physical strength distribution, methanol space-time yield, methanol selectivity and stability.

The invention provides a traditional Chinese medicinal material bio-based carbon nanodot. The bio-based carbon nanodot is a ginseng total saponin carbon nanodot. The carbon dot surface of the total ginsenoside is rich in alcohol/phenolic hydroxyl, amino, carboxyl and other structures, the surface groups are rich, subsequent modification and compounding are facilitated, and the total ginsenoside has good time, pH value and salt stability; various cell fluorescence imaging experiments prove that the total ginsenoside carbon dots can be used as a biological fluorescence probe; meanwhile, the obtained total ginsenoside carbon dots have a specific inhibition effect on rat adrenal pheochromocytoma cells (PC12 cells), and have no obvious proliferation or inhibition effect on other cells (HeLa cells, BRL3A cells and LO2 cells); meanwhile, the total ginsenoside carbon dots can be used as fluorescent probes and can be taken by various cells (BRL3A cells, LO2 cells and QGY7703 cells).

The invention relates to a method for manufacturing magnetic polymethyl methacryate microsphere, which comprises two steps: first, preparing polymethyl methacryate microsphere; second, preparing magnetic polymethyl methacryate microsphere. Compared with existing technology of one step, the invention divides process into two steps. The first step controls particle size and purity of microsphere, while the second step embeds ferrous powder into polymethyl methacryate microsphere. The invention can get magnetic polymethyl methacryate microsphere with adaptive particle size, good monodisperse, mechanic stability and so on.

The invention discloses a method for controlling PbS or PbSe quantum dot size distribution. The method comprises the following steps that: (1) first, CdSe (or CdS) quantum dots with larger sizes are injected into a precursor of lead, and PbSe (or PbS) quantum dots with larger sizes are obtained through a cation exchange reaction at the moment; (2) then, CdSe (or CdS) quantum dots with smaller sizes are continuously injected, and the PbSe (or PbS) quantum dots with smaller sizes are obtained through the cation exchange reaction at the moment; (3) finally, the size distribution of the PbSe (or PbS) quantum dots becomes narrower and narrower under the action of Ostwald ripening effect, so that the size distribution of the PbSe (or PbS) quantum dots is controlled. Through the method, various sizes of the PbSe (or PbS) quantum dots with extremely good size distribution can be obtained; moreover, the PbSe (or PbS) quantum dots are specifically stable in air; the method is low in cost, easy to operate, and not strict in environment requirement.

The invention belongs to energy chemical technical field, especially relates to a fluidized bed reactor and a method for preparation of polyoxymethylene dimethyl ethers from dimethoxymethane and paraformaldehyde. The fluidized bed reactor comprises a gas inlet, a gas distributor, a catalyst inlet, a gas outlet, a fluid inlet, a catalyst outlet, a bottom component and an interstage component, a bottom component related gas upward channel, an interstage component related gas upward channel, a fluid outlet, a bottom downcorner and an interstage downcorner. A process for preparation of polyoxymethylene dimethyl ethers comprises the steps of: fluidizing gas is introduced into a bottom bed from the gas inlet via the bottom component related gas upward channel through the gas distributor; the fluidizing gas goes upwards and flows out of the reactor via the gas outlet; paraformaldehyde and dimethoxymethane are introduced into a bed through the fluid inlet; the fluid goes downwards and leaves the reactor via the fluid outlet. Compared with a conventional cannula reactor, the fluidized bed reactor improves the dispersion uniformity of catalyst and conversion of formaldehyde.

The present invention relates to a process for the production of the largest possible spherical, monodisperse polyvinylpyrrolidone (PVP) seed particles in the micron range by dispersion polymerisation. The particles obtained in this way represent novel starting materials for the production of macroporous polymer particles, which can in turn be employed in preparative and analytical chromatography for protein preparation. They can also be employed as base material for further reactions.

The novel process for the polymerisation of N-vinylpyrrolidone, which is inexpensive to carry out, gives particles having optimised quantities, such as monodispersity, sphericity and particle diameter, which can be employed in further reactions and have advantageous, in particular improved, properties for use in chromatographic separation methods.

The invention discloses a ceramic material with a low dielectric constant. The ceramic material is prepared from the following materials in parts by weight: kaolin, anorthite, akermanite, sodium carboxymethyl cellulose, calcium titanate, polyvinyl alcohol, nanometer bismuth trioxide, boron oxide, zinc nitrate, magnesium cordierite, fluorite, tremolite, clinochlore, pyrophyllite and yttrium aluminum garnet. Zinc ions in zinc nitrate can substitute magnesium in akermanite; the akermanite having magnesium substituted with the zinc ions can be matched with boron oxide to reduce a sintering temperature, and can be matched with calcium titanate to adjust the temperature stability, thereby avoiding heating fragmentation and reducing the dielectric constant; yttrium ions in the yttrium aluminum garnet can improve particle size distribution and reduce porosity; a special octahedral six-membered rings of magnesium cordierite crystals enable the structure and performance to have adjustability; and the yttrium aluminum garnet can be matched with the magnesium cordierite to further reduce the dielectric constant and increase the stability.

A method of processing a powdered feedstock to form a fabricated component is provided. The fabricated component includes a plurality of grains having a nominal grain size. The method includes providing the powdered feedstock material having a population of phase particulates with a first nominal size distribution disposed within a host matrix material. The method includes building a consolidated component from the powdered feedstock material in an additive manufacturing process, and fabricating the fabricated component from the consolidated component. The first nominal size distribution of the population of phase particulates is sized such that at least a portion of the population of phase particulates persists throughout the additive manufacturing process and is present as a processed population of phase particulates in the consolidated component. In addition, the processed population of phase particulates has a second nominal size distribution effective to produce the nominal grain size of the fabricated component.