235 results about "Relaxation rate" patented technology

The invention relates to a high temperature creep life accelerated test method of a material, which comprises: a plurality of groups of short time stress relaxation tests of the material at the same temperature, acquiring a relaxation rate-stress curve based on the numerical differentiation principle, forming a relaxation creep rate-stress curve by utilizing a relaxation equation, calculating creep data to build a creep curve, and building a steady state creep rate curve and a Norton creep equation. The method starts from the physical relation between relaxation and creep, covers rather broad properties of creep strain rate by utilizing the short time relaxation process, and educes broader creep data than that educed from general creep tests by above ten times, thereby effectively reducing the amount of high temperature creep tests and time of tests and providing basic data for development of new material and engineering application.

A method for manufacturing an expanded polytetrafluoroethylene (PTFE) plate comprises the following steps: sieving PTFE dispersion resins, adding a propellant and mixing the two materials, placing the mixed materials for 24h and then carrying out aging treatment, then carrying out pre-press shaping and extruding blanks, carrying out calendaring with two rollers, removing the propellant, carrying out composite shaping after biaxial tension and carrying out reshaping and trimming to finally manufacture the expanded PTFE plate. The expanded PTFE plate is a great breakthrough in the manufacturingprocess of molded plates and turning plates. The compression resilience, the tensile strength and the low stress relaxation rate of the expanded PTFE plate are obviously increased and the expanded PTFE plate obviously improves the performance defects of the fluoroplastics, thus meeting the demand of the use functions of the sealing elements and propelling the fluoroplastics to be one of the substitutes of the asbestos materials widely used at present in the sealing material field.

The invention provides a method and device for determining horizontal surface relaxation rate. The method comprises the step of carrying out CT scanning on a rock core sample to acquire a gray level image of the rock core sample, carrying out binarization processing on the gray level image to generate a binary image and extract a hole grillage, carrying out nuclear magnetic resonance measurement on the rock core sample to determine measured horizontal relaxation signals, carrying out relaxation simulation on the rock core sample according to the extracted binary image of the hole grillage and the preset surface relaxation rate to determine simulated horizontal relaxation signals, comparing whether the simulated horizontal relaxation time signals coincide with the components at the right-most ends of the measured horizontal relaxation time signals, and choosing the preset surface relaxation rate as the determined horizontal surface relaxation rate of the rock core sample to be outputted when the simulated horizontal relaxation time signals coincide with the component of the right-most ends of the measured horizontal relaxation time signals. The method and device for determining horizontal surface relaxation rate has the advantages of being more reliable in principle, simple in calculating process, easy to achieve, strong in actual operability and the like.

The invention provides a method for determining the nuclear magnetic resonance T2 cutoff value and the fluid saturation of tight oil, and an apparatus thereof. The method comprises the following steps: determining the carbon content of a sample to be measured to generate a carbon content determination result; determining the lower limit value of the pore throat radius of the sample to be measured according to the carbon content determination result; and determining the corresponding T2 cutoff value according to the lower limit value of the pore throat radius and the core relaxation rate of the sample to be measured. The T2 cutoff value is calculated by using the lower limit value of the pore throat radius of the tight oil movable fluid of the practical sample in the above scheme, and the lower limit value of the pore throat radius of the tight oil movable fluid of the practical sample is determined by adopting a course to fine pore throat carbon content gradual approximation technology, so the T2 cutoff value obtained in the invention is true.

The invention relates to a tooth orthodontic correction material which comprises the following components based on the total weight of the correction material: (A), 50-90wt% of polyethylene glycol terephthalate-1,4-cyclohexane dimethyl alcohol ester; (B), 5-45wt% of polycarbonate; and (C), 5-45wt% of thermoplastic polyurethane, wherein the sum of the percentage contents of all components of the correction material is 100wt%. The invention also relates to a preparation method of the tooth orthodontic correction material and application of the tooth orthodontic correction material used for manufacturing a tooth orthodontic correction device. The tooth orthodontic correction material disclosed by the invention has high transparency and excellent low-stress relaxation rate and can provide long-time stress and long-lasting correction effect.

The invention relates to a high-strength and ductility durable type large-diameter 1960 MPa stage zinc-aluminum alloy coating steel wire for a bridge cable. A steel wire rod is an ultra-pure hyper-eutectoid steel high-carbon steel wire rod obtained after sorbite treatment (water bath, lead bath and salt bath), the strength of extension is larger than or equal to 1290 MPa, the area reduction rate is larger than or equal to 30%, and the elongation is larger than or equal to 10%; and the steel wire rod is drawn into a bright steel wire with the diameter ranging from 4.90 mm to 6.90 mm, then hot galvanizing zinc-aluminum alloy coating is carried out, and technological processes include lead bath degreasing, hot water washing, chlorohydric acid pickling, hot water washing, weak base washing, hot water washing, ammonium chloride and zinc chloride solvent plating assisting, hot-dip galvanizing-nitrogen smearing, zinc-aluminum alloy hot galvanizing, nitrogen smearing and wire collecting. The steel wire rod is subject to stabilization treatment, and the strength, the linearity, the relaxation rate and the steel wire axial homogeneity of the large-diameter ultrahigh-strength Zn95Al5 alloy coating steel wire are guaranteed.

The invention discloses a tumor-targeted nonionic dendritic macromolecule magnetic resonance imaging contrast agent and a preparation method thereof. The contrast agent is a spherical nano composite particle prepared by taking a PAMAM dendritic macromolecule as a nuclear, folic acid as a targeting group, polyethyleneglycols (PEG) with different molecular weights as linking arms between the targeting group and a macromolecular carrier, and diethylenetriamine pentaacetic acid (DTPA) as a Gd ligand; and the preparation method comprises the following steps: reacting H2N-PEG-FA with folic acid residue and diethylenetriamine pentaacetic acid double active ester (SuO-DTPA-SuO) to obtain SuO-DTPA-PEG-FA; and then bonding the SuO-DTPA-PEG-FA on the surface of the PAMAM to obtain PAMAM-DTPA-PEG-FA; and finally chelating the PAMAM-DTPA-PEG-FA and Gd. The imaging contrast agent prolongs the circulation time in blood, improves the relaxation rate, can be effectively distributed in tumor tissues, reduces the toxicity on normal tissues, and has the advantages of long-acting circulation in vivo, improvement of the relaxation rate, reduction of the medicament consumption and the like.

The invention synthesizes a type of liver targeted, biodegradable high molecular MRI contrast medium with alpha,beta- poly [(2-aminoethyl) - L-asparagine] as fundamental chain, galactose as target gene, diethylenetriamine pentaacetic acid or L-tyrosine methyl ester derivatives as Gd3+ ligand. The contrast agent is less toxic, biocompatible, and has good relaxation rate than low molecular business contrast medium. Animal experiments showed that in liver organizations its enhancing effect is three times better than commercial and low molecular contrast medium (gadolinium sprayed acid cyelophosphate); the residence time in liver is more than 24 hours, which is 18 hours longer than low molecular business contrast medium. The feature is that Zeta potential for the contrast medium is negative and less than -10mV. We can achieve the MRI visible, the liver targeted, core-shell nanogene vector system with it as a gene vector system shell structure.

The invention relates to a preparation method of magnetic nano ferric oxide, concretely comprising the step of synthesizing magnetic ferric oxide nanoparticles by adopting an alternating magnetic field solvent cold magnetic induced internal thermal mechanism. The preparation method is based on the traditional chemical co-precipitation principle, and the magnetic ferric oxide nanoparticles with a good crystal structure and good magnetic properties are obtained through internal thermal induction of an alternating magnetic field and external low temperature circulating cooling. Different from preparation of magnetic nanoparticles by adopting the traditional solvent thermal process, the preparation scheme utilizes the alternating magnetic field, and magnetic particles are synthesized through one solvent cold and slow nucleation growth process. Compared with the magnetic ferric oxide particles with the same size, saturation magnetization strength and relaxation rate of the product prepared by adopting the preparation method are improved by about twice, crystal defect is obviously reduced, and all the performance indexes of the product are also greatly improved.

In a method and magnetic resonance (MR) apparatus to acquire MR data from a subject, a predetermined spectral model of a multipoint Dixon technique is used that includes at least two spectral components with respective associated relaxation rates, a first phase due to field inhomogeneities; and a second phase due to eddy current effects. MR data are acquired using a bipolar multi-echo MR measurement sequence for multiple image points wherein, for each image point, the multi-echo MR measurement sequence alternately uses positive and negative readout gradient fields for the readout of MR signals of the MR data at at least three echo times. The at least two spectral components are determined based on the MR data.

The invention belongs to the field of metallurgy, and in particular relates to a high-strength steel pull rod and a method for producing the same through heat treatment. The high-strength steel pull rod comprises the following chemical components in weight percent: 0.25 to 0.50 percent of C, 0.30 to 1.8 percent of Si, 0.50 to1.8 percent of Mn, less than or equal to 0.03 percent of P and S; 0.15 to 0.55 percent of Mo, 0.25 to 1.2 percent of Cr, and one or more of V, Ti and B. The mechanical properties are as follows: the yield strength is between 650 and 1,080 N/mm<2>, the tensile strength is between 850 and 1,230 N/mm<2>, the percentage elongation after fracture is more than or equal to between 9 and 15 percent, and the relaxation rate is less than or equal to 4.0 percent or 2.5 percent. The microstructure is a tempered martensite structure. The high-strength steel pull rod adopts induction heat treatment under tensile stress state, the quenching heating temperature is between 850 and 1,050 DEG C and is then cooled to below 250 DEG C, and the tempering heating temperature is between 400 and 700 DEG C; besides, the microstructure of the finished steel pull rod is the superfine tempered martensite structure basically.

The invention relates to a preparation method of RGD-modified subminiature superparamagnetic iron oxide nanoparticles. The preparation method comprises the following steps of preparing PEI-coated subminiature superparamagnetic iron oxide nanoparticles by a mild reduction method, modifying surfaces of USPIO/PEI.NH2 nanoparticles by fluorescein isothiocyanate (FI) and a RGD compound (COOH-PEG-RGD) subjected to pegylation, and carrying out acetylation treatment on the surfaces of the nanoparticles. The preparation method has simple processes and mild reaction conditions and can be operated easily. The RGD-modified subminiature superparamagnetic iron oxide nanoparticles have small sizes, a high relaxation rate, good colloid stability and biocompatibility, and high alpha<v>beta<3> integrin high-expression tumor cell targeting, and have a latent application value in the field of in-vivo tumor targeting MR imaging diagnosis.

The invention provides a processing method of fine denier, high-strength and low-shrinkage polyester filament. The method uses the ordinary POY polyester pre-oriented silk as pre-processing raw materials which is obtained in spinning speed of 2500 - 3300m/min and in the condition of need not be increased control-cooling, improves the prior dual-heat-discs horizontal traction machine, adjusts the design of traction technology, processes consecutively through several procedures of first level drafting, one-shot relaxed heat forming and rolling to control the drafting temperature, drafting magnification and shaping relaxation rate accurately, then produces fine denier, high-strength and low-shrinkage polyester filament which denier is 30D-200D. The strength of products can reach 8.0 +- 0.5g / d (7.0 +- 0.4cN/dtex), the broken elongation is 14.0% +- 3.0% and the boiling-water shrinkage ratio is below 2.0%, it meets the requirements of producing high and middle grade polyester filament sewing thread.

The invention relates to a high-water-solubility nuclear magnetic resonance imaging contrast agent and a preparation method of the high-water-solubility nuclear magnetic resonance imaging contrast agent. The high-water-solubility nuclear magnetic resonance imaging contrast agent is gadolinium (III) complex which is based on 1, 4, 7, 10-tetraazacyclododecane-1, 4, 7-triacetic acid (DO3A) and modified by quaternary ammonium salt side chain. The nuclear magnetic resonance imaging contrast agent prepared by the gadolinium (III) complex is good in water solubility, stability and relaxation rate, and the relaxation rate of the nuclear magnetic resonance imaging contrast agent can be controllably adjusted by controlling the length of the side chain.

The invention relates to a manufacturing method of a zinc-aluminum alloy coated steel strand with a medium-high aluminum content. The method comprises the following steps that hot galvanizing aluminumalloy is carried out after wire rod pretreatment, and the hot plating process comprises the following steps of degreasing heat of alkaline washing, degreasing of lead bath, thermal-water cleaning, hydrochloric acid pickling, water cleaning ammonium chloride zinc chloride solvent assistant plating, drying hot dip galvanizing, electromagnetic wiping, hot dip galvanizing aluminum alloy, nitrogen wiping, taking-up wire in sequence; a steel wire after being subjected to hot galvanizing aluminum is subjected to over-mold precise drawing, and the compression rate is controlled at 8-10 by percentage;finally stranded wire and stabilizing treatment are carried out to obtain the hot galvanized aluminum steel stranded wire, so that the strength, the linearity, the relaxation rate and the axial uniformity of the steel stranded wire of the high-strength alloy coated steel wire are ensured. On the basis of improving the corrosion resistance, the steel stranded wire with higher strength, higher toughness and better fatigue resistance is produced.

A method for measuring a liver magnetic resonance crosswise relaxation rate R2* parameter includes the steps: (1) obtaining a magnetic resonance liver image, and drawing a full-liver region-of-interest; (2) obtaining a magnetic resonance liver image which is denoised, re-obtaining a gray level of each pixel within the full-liver region-of-interest of the magnetic resonance liver image which is denoised, enabling the gray level of each pixel and echo time to be matched on a first moment model formula (I) of a single-index model under the influences of non-central Chi noise, and then obtaining a full-liver R2* image; (3) dividing a R2* value of the full-liver region-of-interest into two types, enabling the two types to respectively correspond to liver parenchyma and blood vessels, and re-obtaining a liver parenchyma region-of-interest; and (4) a calculating gray level average value and echo time of the liver parenchyma region-of-interest of each echo image and enabling the gray level average values and the echo time to be matched on the formula (1), and then obtaining a final liver parenchyma R2* value. The method can improve precision of the crosswise relaxation rate R2* parameter and is good in repeatability.

The invention discloses a testing method of the specific surface area of a particulate matter in a suspension system. The testing method comprises the following steps: (1) carrying out nuclear magnetic resonance detection on a solvent, controlling the temperature of the solvent by virtue of a metal bath, carrying out CPMG impulse sequence testing on the solvent to obtain T2 relaxation time of the solvent, and calculating relaxation rate R2f of the solvent; (2) adding a particulate matter sample into the solvent, so as to obtain suspension liquid containing the particulate matter sample; (3) carrying out the nuclear magnetic resonance detection on the suspension liquid containing the particulate matter sample, controlling the temperature of the suspension liquid by virtue of the metal bath, carrying out the CPMG impulse sequence testing on the suspension liquid to obtain T2 relaxation time of the particulate matter sample, and calculating the average relaxation rate according to a formula: R2=PbR2b+PfR2f; and (4) calculating the specific surface area of the particulate matter according to the following formula: Sa=(R2sp*R2f)/(Psi*Kp). According to the testing method, the specific surface area of the particulate matter in a suspension state can be tested.

The invention provides a paramagnetic metal complex and a synthetic method and application thereof. The paramagnetic metal complex is an arabinogalactan-modified 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacethyl paramagnetic metal complex. A magnetic resonance imaging contrast agent prepared from the paramagnetic metal complex has high stability, water solubility and relaxation rate and is targeted to liver and kidney, so that targeted imaging is realized, and the imaging contrast and definition are improved. The paramagnetic metal complex has a good effect on raising the early diagnosis levels of diseases of liver and kidney organs, is about 2 times the relaxation rate of dotarem, has very long targeted radiography imaging time, can be easily prepared into a solution with required concentration for intravenous injection, is suitable for sterilizing and disinfecting with a hot pressing method, can be selectively identified by an asialoglycoprotein receptor on a liver parenchyma surface, and has high selectivity on livers of human beings or other mammals.

The invention discloses a manufacturing process for an asbestos-free sealing gasket. An asbestos-free beater-addition sealing paperboard is manufactured through a beater-addition process by taking aramid fibre 1414 pulp as a main material, matching cellulose fibres and mineral cotton fibres as hybrid fibres to replace asbestos fibres, selecting a mixture of butadiene-acrylonitrile latex and styrene-butadiene latex as latex, selecting kaolin, talcum powder and mica powder as filler, and determining a reasonable formula range of the compositions, wherein the asbestos-free beater-addition sealing paperboard has the ignition loss of less than or equal to 35 percent, the compression ratio of equal to 25+/- 5 percent, the rebound rate of greater than or equal to 45 percent, the tensile strength of greater than or equal to 5 MPa, and the creep relaxation rate of less than or equal to 30 percent.

The present invention provides a polishing composition that can polish an object to be polished at a high polishing speed with fewer scratches (defects). The present invention relates to a polishing composition including silica and a dispersing medium, the polishing composition having, when analyzed by pulse NMR spectroscopy, a specific relaxation rate (R_2sp) of from 1.60 to 4.20 as determined by the following Formula (1):

R_2sp=(R_(silica))/(R_(medium))−1   Formula (1):

wherein R(_silica) represents the reciprocal of the relaxation time of silica (unit:/millisecond), and R(_medium) represents the reciprocal of the relaxation time of the dispersing medium (unit:/millisecond).

The invention relates to a magnetic nanoparticle, and a preparation method and application thereof. Specifically, the magnetic nanoparticle has the characteristics that 1) the magnetic nanoparticle is ferrite; 2) the magnetic nanoparticle has a particle size of 0.1 to 30 nm; 3) the relaxation rate r1 of the magnetic nanoparticle is no less than 1.2 m/M/s; 4) a ratio of a relaxation rate r2 to the relaxation rate r1 of the magnetic nanoparticle is no more than 3.5 and no less than 1.05; and 5) the T1 weighted signal intensity of 0.5mM of the magnetic nanoparticle is no less than 70. The invention also discloses the preparation method and application of the magnetic nanoparticle. When the magnetic nanoparticle is applied to magnetic resonance imaging, a high-quality MRI contrast agent with substantial and excellent imaging performance, high magnetosensitivity and rich T1 signals can be obtained, and the MRI contrast agent is improved in discovery and detection of tumors, cardio-cerebrovascular diseases and other serious diseases, so medical detection and treatment cost can be substantially lowered.