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OFDM (orthogonal frequency division multiplexing) system symbol timing synchronization realizing method suitable for low-signal-to-noise-ratio channel environments
ActiveCN104125190AReduce complexityReduce operational complexityMulti-frequency code systemsSynchronising arrangementComputation complexityRound complexity
The invention discloses an OFDM (orthogonal frequency division multiplexing) system symbol timing synchronization realizing method suitable for low-signal-to-noise-ratio channel environments. The OFDM system symbol timing synchronization realizing method includes: adopting two conjugated OFDM symbols based on frequency domain PN (pseudo-noise sequence) to serve as a training sequence; subjecting symbol positions of the training sequence and a receiving sequence to sliding conjugation correlation at a receiving end, obtaining a timing offset estimation function via summation and modulus computation; for every moment, taking an estimation function of one timing offset section at every moment to solve a weighted average so as to obtain a dynamic threshold for the corresponding moment; comparing the estimation function with the corresponding dynamic threshold to lock a timing position. Due to the facts that only data symbol position information is required, data are not involved in computation and normalization computation for computation results is not required, the OFDM system symbol timing synchronization realizing method has the advantages that complexity is low and performance cannot be affected by size of received signal power. In addition, the OFDM system symbol timing synchronization realizing method is accurate and stable in timing under a low-signal-to-noise-ratio environment, easy to implement and low in computation complexity.
Owner:XIDIAN UNIV
Training sequence frame timing synchronized method based on pseudo-random sequence modulation based
InactiveCN101778088AImprove featuresSharp peakMulti-frequency code systemsCarrier signalSelf correlation
The invention discloses a training sequence frame timing synchronized method based on pseudo-random sequence modulation, which can be applied in an orthogonal frequency division multiplexing system or a single carrier frequency domain equalization system, and comprises the following steps: (1) carrying out an energy detection by using the relevance of the front part and the back part of a training sequence at a receiving terminal; (2) taking the certain range around the peak position of the energy detection as a rough synchronization timing range; (3) in the rough synchronization timing range, using a local frame leading sequence generated by the receiving terminal to carry out the cross-correlation with a receiving sequence, according to the peak position of the cross-correlation, determining the position of the local frame accurate synchronization timing, wherein the first half part of the leading training sequence is gained by modulation of cascade sequence of self-correlation of a plurality of constant amplitude zero values by adopting the pseudo-random modulation sequence, and the second half part thereof is inverse operation of the first half part. The method can gain higher timing accuracy by using the pseudo-random modulation sequence to carry out the complex fine synchronization.
Owner:INST OF ACOUSTICS CHINESE ACAD OF SCI
Detecting method for multiple kinds of poly brominated diphenyl ethers in aquatic product
InactiveCN103235062AAchieve simultaneous separationEasy to separateComponent separationFood safetyMass Spectrometry-Mass Spectrometry
The invention relates to a detecting method for multiple kinds of poly brominated diphenyl ethers in an aquatic product. The detecting method comprises the steps of carrying out extracting, degreasing, silicagel column purifying and concentrating on an aquatic product sample, and analyzing and detecting the aquatic product sample through gas chromatography-negative chemical ionization mass spectrometry. By adopting the treatment measures and proper technique parameters, the method is capable of simply, quickly and accurately measuring the contents of as much as 11 kinds of poly brominated diphenyl ethers in the aquatic product at the same time, and the method has the advantages of high detecting sensitivity, good stability, accurate result, and the like, thereby providing a reliable and quick detecting method for qualitatively and quantitatively detecting the residual poly brominated diphenyl ethers in the aquatic product and monitoring food safety.
Owner:EAST CHINA UNIV OF SCI & TECH
Radar system
InactiveUS20070040728A1Increase system costEasy to detectRadio wave reradiation/reflectionFrequency spectrumRadar systems
A radar system in which a beat signal is generated by transmitting a transmission signal that is subjected to frequency modulation into a triangular wave and receiving a reflection signal from a target, the beat signal is sampled, and a window function is applied to yield a discrete frequency spectrum. When the window function is applied, a first window function having an amplitude that is gently attenuated from the center of the sampling period toward both sides thereof is applied in a lower frequency band in the frequency spectrum (at close range), and a second window function having an amplitude that is sharply attenuated from the center of the sampling period toward both sides thereof is applied in a higher frequency band in the frequency spectrum (at far range).
Owner:MURATA MFG CO LTD
A kind of optical OFDM system based on superposition training sequence and its frame synchronization method
InactiveCN102291360AGood autocorrelationSingle peakFibre transmissionMulti-frequency code systemsFrequency spectrumOptical line termination
The invention discloses an optical OFDM system based on superimposed training sequences and a frame synchronization method thereof. The system scheme includes an optical line terminal (OLT) and an optical network terminal (OUN), wherein the OLT mainly includes a training sequence generation module, a Hermitian conjugate Symmetry module, data OFDM signal generation module, training sequence and data OFDM signal superposition module, optical modulation module; OUN mainly includes optical demodulation module, OFDM signal receiving module, channel estimation module, training sequence and data symbol separation module. The frame synchronization method is obtained based on the correlation between the processed received signal and the local training sequence, which can prevent the receiving end from using a large amount of data for blind synchronization and increasing the complexity of the receiver design. At the same time, a method for constructing an autocorrelation training sequence is also disclosed. The system and the frame synchronization method involved in the invention can effectively improve the spectrum utilization rate and the power efficiency of the transmitter, and have the advantages of simple design principle, strong practicability, and low signal processing requirements.
Owner:SOUTHWEST PETROLEUM UNIV
Multi-dimentional high performance liquid chromatographic separation technique (STAR7) for quantitative determinations of 7 fractions in heavy petroleum streams boiling above 550 degrees F
ActiveUS20100218585A1Quantitative precisionSharp peakComponent separationSolid sorbent liquid separationSolventQuantitative determination
The present invention provides quantitation of seven classes of compounds (saturates, 1-4+ ring aromatics, sulfides, and polars) present in petroleum streams boiling from 550-1050° F. Operating the present invention in the preparative mode will allow us to load and collect multi-milligram amounts of material. In the present invention, all seven fractions are produced in a single run, whereas the most commonly used preparative liquid chromatographic separations requires two or more large scale separations to generate similar fractions. The present invention uses 100 times less solvent. The present invention protocol provides a quicker and cheaper alternative to most commonly used preparative liquid chromatographic separations and is flexible enough to target many refining and chemicals problems.
Owner:EXXON RES & ENG CO
Holey fiber taper with selective transmission for fiber optic sensors and method for manufacturing the same
InactiveUS20090052852A1Reduce the overall diameterIncrease the lengthGlass making apparatusCladded optical fibreRefractive indexEngineering
Large-mode-area single material holey fiber tapers with collapsed by nonadiabatic process air holes in the waist for fiber optic sensors and a method for manufacturing these tapers are claimed. The gradual collapsing of the holes is achieved by tapering the fibers with a “slow-and-hot” method. This nonadiabatic process makes the fundamental mode of the holey fiber to couple to multiple modes of the solid taper waist. Owing to the beating between the modes, the transmission spectra of the tapered single material holey fibers exhibit several interference peaks. That means the all-fiber Mach-Zehnder type interferometer is formed in a holey fiber such a way. The multiple peaks, combined with a fitting algorithm, allow high-accuracy refractometric measurements, temperature-independent strain measurements, measurements of high temperature and may be used for measuring many others parameters.
Owner:MINKOVICH VLADIMIR PETROVICH +2
Diamond crystal, diamond devices, magnetic sensor, magnetic sensor system, and method for manufacturing sensor array
ActiveUS20160334474A1Increase contrastSharp peakPolycrystalline material growthFrom chemically reactive gasesSensor arrayDiamond crystal
A diamond crystal according to the present invention has an NV region containing a complex (NV center) of nitrogen substituted with a carbon atom and a vacancy located adjacent to the nitrogen, on a surface or in the vicinity of the surface, wherein the NV region has a donor concentration equal to or higher than the concentration of the NV centers, or a crystal of the NV region is a {111} face or a face having an off-angle that is ±10 degrees or less against the {111} face, and a principal axis of the NV center is a <111> axis that is perpendicular to the {111} face. Such a diamond crystal enables almost 100% of the NV center to be a state (NV−) of having a negative electric charge, and spin states of the NV− centers to be aligned in one direction.
Owner:JAPAN SCI & TECH CORP +1
Vanadium sodium phosphate positive electrode material, sodium ion battery, preparation method therefor, and use thereof
PendingUS20210167387A1High crystallinitySharp peakFinal product manufactureSmall-sized flat cells/batteriesSodium phosphatesSodium-ion battery
A vanadium sodium phosphate positive electrode material, a sodium ion battery, and a preparation method therefor and application thereof. The preparation method of the vanadium sodium phosphate positive electrode material comprises the following steps: (1) reacting an aqueous solution containing a vanadium source with a phosphorus source, a reducing agent, a sodium source, and a carbon source, the reaction comprising first performing a reaction of an aqueous solution of the vanadium source and the phosphorus source, and then perform a reaction with the reducing agent, or first performing a reaction of the aqueous solution of the vanadium source with the reducing agent and then performing a reaction with the phosphorus source; (2) drying and calcining the reaction liquid obtained in step (1). The vanadium sodium phosphate positive electrode material has a high dispersibility, and has stable circulation performance when used in a battery.
Owner:SHANGHAI ZIJIAN CHEM TECH CO LTD
Acoustic vector array wideband direction finding method based on sparse decomposition theory
ActiveCN106093921AEasy to distinguishEasy to detectWave based measurement systemsDecompositionAmplitude noise
The invention discloses an acoustic vector array wideband direction finding method based on a sparse decomposition theory, and relates to a direction finding technique and implementation method for target broadband continuous spectrum noise in the acoustic vector sensor array detection field. The sparsification idea is introduced to an acoustic vector array direction finding system; a combined sparse constraint is established according to frequency point components in broadband continuous spectrum noise signal bandwidth; and finally, a unified airspace sparse decomposition form is obtained, thereby realizing direction finding of the broadband continuous spectrum noise. According to the method, a relatively-sharp spectrum peak and a low-amplitude noise floor can be formed; when the number of array snapshots is small, the method is stable in performance and can distinguish coherent signal sources; and when the target DOA (direction of arrival) approaches to the array axial direction, the phenomenon of noise floor fluctuations occurring under the condition of low signal-to-noise ratio of a conventional beam forming (CBF) method and a minimum variance distortionless response (MVDR) method does not exist.
Owner:NO 54 INST OF CHINA ELECTRONICS SCI & TECH GRP
Radar system with peak frequency analysis and window functions
InactiveUS7336218B2Increase system costEasy to detectRadio wave reradiation/reflectionFrequency spectrumRadar systems
Owner:MURATA MFG CO LTD
Amphiphilic aza-BODIPY fluorescent dye and preparation method thereof
ActiveCN105566941ASharp peakHigh strengthAzo dyesGroup 3/13 element organic compoundsBenzeneAza-bodipy
The invention relates to an amphiphilic aza-BODIPY fluorescent dye and a preparation method thereof. The preparation method comprises the following steps: reacting p-propynyloxy acetophenone with dodecyloxy phenylacetaldehyde to obtain chalcone; performing nitromethane nitration to obtain 4'-propynyloxy-4-dodecyloxy-2-nitromethylene-chalcone; carrying out coupling under an ammonium acetate condition, reacting the coupling product with boron trifluoride-ether to obtain an aza-BODIPY structure; and introducing different hydrophilic groups into the opposite alkynes of benzene with substituted 3rd and 5th positions of the parent structure of aza-BODIPY through click reactions so as to obtain the amphiphilic molecule. The provided synthesis method has the advantages of few steps, simple conditions, and high yield. Prominent aggregation phenomenon of amphiphilic BODIPY dye in water can be observed, the UV absorption of the dye is near 800 nm, the UV absorption peak is sharp, and the strength is extremely high.
Owner:TIANJIN UNIV
Method for detecting impurity phenylhydrazine in edaravone
InactiveCN102841170ASharp peakSymmetrical peak shapeComponent separationRetention timeColumn temperature
Owner:CHENGDU BAIYU PHARMA CO LTD
Intra-unicellular substance detecting method based on whispering gallery mode
InactiveCN108760704AHigh detection sensitivityHigh sensitivityFluorescence/phosphorescenceLaser technologyWhispering gallery
The invention relates to an intra-unicellular substance detecting method based on a whispering gallery mode, and belongs to the fields of laser technologies and biophotonics. The method comprises thefollowing steps: (1) whispering gallery mode microcavity selection is performed; (2) microcavity and cell are treated; (3) a concrete implementation method of detection on biological substances to betested is performed; (4) the detection ranges of the detecting method involve numerous specific biological substances such as nucleic acid, protein, cells and biomolecules. The detection sensitivity is high; the detection can be realized in cells. By the whispering gallery mode, fluorescence can form resonant vibration in the cavity; laser is generated; signals are greatly enhanced; the tracking detection time is prolonged.
Owner:BEIJING UNIV OF TECH
Elemental analysis determination method and device
InactiveCN103792223AReduce distractionsSlow heating ratePreparing sample for investigationAnalysis by thermal excitationSodium hydrosulfideElemental analysis
The invention discloses an elemental analysis determination method and device. The elemental analysis determination method comprises the following steps: adding an inorganic compound capable of releasing hydrogen in pyrolysis into a to-be-detected sample and mixing the inorganic compound with the sample uniformly; carrying out pyrolysis on the mixture at a certain temperature, enabling an element to form a volatile matter, and determining the volatile matter by an atom spectrogram, wherein the inorganic compound for releasing hydrogen in pyrolysis is sodium bisulfide, potassium hydrogen sulfide, ammonium sulfide, ammonia hydrogen sulfide, ammonium iodide, hydrogen sulfide or hydrogen iodide, and the weight of the added inorganic compound is 0.2-100 times the weight of the sample. According to the invention, an inorganic hydrogen release reagent and a curie point pyrolyser are used, and the advantages of low analysis cost, less interference, high element volatile matter formation speed, high sampling efficiency of to-be-detected elements and the like are realized, and the method is a rapid and accurate analysis method.
Owner:TIANJIN NORMAL UNIVERSITY
Method for measuring isothiazolinone antibacterial finishing agents in textiles
ActiveCN104991003AEfficient extractionGuaranteed reliabilityComponent separationIsothiazolinoneColumn temperature
The invention provides a method for measuring isothiazolinone antibacterial finishing agents in textiles, and relates to the field of product quality analysis, and discloses a method for separating and detecting the five isothiazolinone antibacterial finishing agents. The following liquid phase chromatographic conditions are adopted, and according to the liquid phase chromatographic conditions, a chromatographic column is XR-ODS (2.2 microns), the inner diameter is 100 mm*3.0 mm, column temperature is 40 DEG C, column flow speed is 0.4ml / min, a diode array detector is adopted, and detection wavelengths are 277 nm and 283 nm. According to the gradient elution conditions, the volume ratio of methanol to water is 40 to 60 for 0.00 min; the volume ratio of methanol to water is 90 to 10 for 1.90 min; the volume ratio of methanol to water is 90 to 10 for 6.00 min; the volume ratio of methanol to water is 40 to 60 for 6.01 min; 9.00 min. The five isothiazolinone antibacterial finishing agents are separated, a good baseline separation effect can be achieved, and peak types are sharp and symmetric.
Owner:SHENZHEN ENTRY EXIT INSPECTION & QUARANTINE BUREAU INDAL PROD INSPECTION TECH CENT
Method for measuring content of menthol in electronic cigarette liquid
The invention relates to a method for measuring the content of menthol in electronic cigarette liquid. The method is characterized by comprising the steps of preparing a sample solution to be measured by an ultrasonic extracting method, configuring a standard working solution with six concentration gradients, performing analysis by a gas chromatograph matched with hydrogen flame ionized detector, and measuring the content of menthol by an internal standard method. The result shows that when the content of menthol is 0.001mg / mL to 0.1mg / mL, the linear relation is good, the limit of detection (LOD) is 0.0028 percent, the average recover rate of three scaled levels is 100.9 percent, and the average relative standard deviation (RSD) is 1.38 percent. The method is high in sensitivity and good in repeatability and recovery rate.
Owner:CHINA NAT TOBACCO QUALITY SUPERVISION & TEST CENT
Symbol timing synchronization method of OFDM system
ActiveCN105024966AImprove performanceReal-time calculation of dynamic thresholdMulti-frequency code systemsCurrent loadSignal-to-noise ratio (imaging)
The invention discloses a symbol timing synchronization method of an OFDM system. With the method, problems that no single sharp timing offset estimation function peak value is provided in the prior art and too much time is spent in determining an ideal timing position can be solved. The method comprises the following steps: 1, generating a training sequence and inserting the training sequence in front of a load data packet; 2, calculating a timing offset estimation function value at an initial position time of a sliding window at a receiving terminal; 3, taking an average of timing offset estimation functions of M times before the time at any time; 4, determining a weighting coefficient of the timing offset estimation function average value; 5, calculating a dynamic threshold according to the obtained timing offset estimation function average value and weighting coefficient; and 6, comparing the timing offset estimation functions and the dynamic threshold until detecting an ideal timing position of the current load data packet; and carrying out the operation continuously according to the mechanism to obtain an ideal timing position of each subsequent data packet. Therefore, timing can be realized accurately in a low-signal-to-noise-ratio environment and the real-time performance is good.
Owner:XIDIAN UNIV
Detecting method of content of benzene-type compounds in food contact material
ActiveCN109991349AAvoid consumptionAvoid pollutionComponent separationFood contact materialsQuantitative determination
The invention discloses a detecting method of a content of benzene-type compounds in a food contact material. N,N-dimethylacetamide is used as a solvent dissolving test piece, extraction solutions of14 kinds of benzene-type compounds are obtained, and then a headspace-gas chromatography-tandem mass spectrometry method is adopted to perform qualitative analysis and / or quantitative analysis on theextraction solutions. According to the detecting method of the content of the benzene-type compounds in the food contact material, ion monitoring is used for qualitative confirmation and quantitativedetermination, the precision of the detecting result is ensured, and the detecting sensitivity is improved; and a headspace method is adopted, directly test piece feeding analysis is carried out, theoperation is easy and rapid, and consumption of large-quantity of solvents and environmental pollution are avoided.
Owner:SHANGHAI INST OF QUALITY INSPECTION & TECHN RES
Preparation method of perovskite quantum dot
PendingCN111410956AHigh luminous intensityExtended decay timeNanoopticsLuminescent compositionsQuantum yieldLuminous intensity
The invention relates to a preparation method of a CsPb1-xZnxBr3 perovskite quantum dot. The method comprises the following steps: 1, mixing a cesium source, a lead source and a zinc source in a three-neck flask; then injecting oleic acid (OA), oleylamine (OLA) and 1-octadecene (ODE), under the protection of nitrogen atmosphere, performing heating and magnetic stirring to fully react, after the reaction is finished, applying ice-water bath treatment, performing centrifugal washing to obtain CsPb1-xZnxBr3 perovskite quantum dots, and finally dispersing the quantum dots into n-hexane to be stored. The CsPb1-xZnxBr3 perovskite quantum dot prepared by adopting the method has the characteristics of high crystallization quality, high PL luminous intensity and high PL quantum yield up to 57%, andcan be applied to the fields of illumination, display, photovoltaics and the like.
Owner:SHANGHAI INST OF TECH
High performance liquid chromatographic detection method for 3-cyanopyridine and 4-methylpyridine in 4-cyanopyridine
The invention discloses a high performance liquid chromatographic detection method for 3-cyanopyridine and 4-methylpyridine in 4-cyanopyridine. The high performance liquid chromatographic detection method comprises the following steps: (1) preparing a system applicable solution; (2) preparing a test solution; 3) preparing a contrast solution. The system applicable solution, the test solution and the contrast solution are detected respectively by adopting high performance liquid chromatography. The detection condition is as follows: octadecylsilane chemically bonded silica is used as a filling agent of a chromatographic column; a mobile phase A is modified buffer salt, and is prepared by adding 20 mmol of potassium dihydrogen phosphate and 2.4 ml of triethylamine into 1000 ml of water and adjusting the pH value to 6.0-8.0 with phosphoric acid; a mobile phase B is an organic phase, and adopts gradient elution; the flow rate is 0.5-1.5 ml / min; the column temperature is 10-40 DEG C; the detection wave length is 200-300 nm; the injected sample volume is 10 [mu]l. The separation degree of 3-cyanopyridine, 4-cyanopyridine and 4-methylpyridine in the detection method are all 2.0 or above, the theoretical plate number is high, the symmetry is good, and the condition that the accuracy of the detection results is influenced by interference between the components is effectively avoided; meanwhile, the detection method has the advantages of being accurate and reliable in detection result, short in analysis time, simple and convenient to operate, and the like.
Owner:江苏悦兴医药技术有限公司
Method for synthesizing gold nanoparticles through microemulsion without surfactant
The invention relates to a method for synthesizing gold nanoparticles through a microemulsion without a surfactant. The method is characterized by comprising the following preparation steps of (1) uniformly mixing an oil-phase solvent, a water-phase solvent A and double solvents at the normal temperature, and stirring at the normal temperature until the mixed liquor is transparent so as to obtaina microemulsion A, wherein the stirring speed is 20 to 300r / min; (2) uniformly mixing the oil-phase solvent, a water-phase solvent B and double solvents at the normal temperature, and stirring at thenormal temperature until the mixed liquor is clarified so as to obtain a microemulsion B, wherein the stirring speed is 200 to 300r / min; and (3) under the stirring state, slowly dripping the isometricmicroemulsion B into the microemulsion A from a constant-pressure funnel, and continuously stirring for 5 to 15h at 15 DEG C, wherein the dripping speed is 50 to 70 drip / min.
Owner:QINGDAO UNIV OF SCI & TECH
Optical fiber combined array and grating lobe suppression method based on same
ActiveCN109491009ASuppress interferenceReduce in quantitySubsonic/sonic/ultrasonic wave measurementBundled fibre light guideArray elementIntegrated processing
The invention provides an optical fiber combined array and a grating lobe suppression method based on the same. The method includes the steps that 1, three sub-arrays of the optical combined array receive incident signals respectively, the optical fiber combined array comprises the three sub-arrays which are sequentially arrayed, all the sub-arrays are uniform and equal-interval linear arrays respectively, array element intervals inside all the sub-arrays are relatively prime, and the interval among the three sub-arrays is the half wave length of the received signals; 2, according to the incident signals received by all the sub-arrays, the relatively prime sub-arrays are used for conducting beam forming, and wave beam data output in each scanning direction is obtained; 3, by the utilization of the feature that the array element intervals of all the sub-arrays are relatively prime, wave beam domain information of the three sub-arrays is comprehensively processed, and a spatial spectrumafter grating lobe suppression and a target direction estimation result are obtained. Through the method, the reliability and accuracy of estimating a space target direction can be improved, and a higher resolution is obtained; compared with a traditional uniform area array, an equivalent aperture can be increased, the number of array elements can be decreased, and engineer practical value is high.
Owner:HARBIN ENG UNIV
Method for detecting organic chlorine compounds in leather
InactiveCN107132305AEasy to operateHigh precisionComponent separationIonGas chromatography–mass spectrometry
The invention provides a method for detecting organic chlorine compounds in leather. The method includes carrying out ultrasonic extraction by the aid of normal hexane-ethyl acetate mixed liquid; carrying out purification by the aid of solid-phase extraction columns; concentrating eluent to a defined volume, then separating the eluent by the aid of DB-1701 quartz capillary columns; carrying out analysis by the aid of gas chromatography-mass spectrometry combined instruments; carrying out qualitative treatment in full-scanning modes; carrying out quantification in selective ion modes. The method has the advantages that the linear ranges of the 19 organic chlorine compounds detected by the aid of the method are 10-1000 ng / mL, the correlation coefficients R2 are higher than or equal to 0.9981, the detection limit is 0.01-0.1 mg / kg, the recycling rate is 74.1%-116.4%, and the RSD (relative standard deviation) is lower than or equal to 7.3% (n=6); the method is simple, convenient, speedy, accurate, stable and reliable and is applicable to simultaneously detecting the 19 organic chlorine compounds in the leather, and detection requirements on various technical indexes can be met.
Owner:COMPREHENSIVE TECH SERVICE CENT OF QUANZHOU ENTRY EXIT INSPECTION & QUARANTINE BUREAU OF P R C +1
Method for measuring patulin in fruit jam and vegetable paste
InactiveCN101776656AQualitatively accurateAccurate quantitative analysisComponent separationSodium bicarbonateGas chromatography–mass spectrometry
The invention discloses a method for rapidly measuring patulin in fruit jam and vegetable paste, comprising the following steps: weighing 2.00g of fruit jam and vegetable paste in a centrifuge tube, adding 0.5-3mL of water, shaking, adding 5mL of ethyl acetate-normal hexane solution (95+5, v / v), shaking, simultaneously adding 0.5-2g of sea sands, 4-8g of anhydrous sodium sulfate and 0.5-2g of sodium bicarbonate, shaking vigorously for 2min, and centrifuging for 3min; and weighing 4mL of supernate until ethyl acetate activates a carbon black columella, receipting eluent by a test tube in which glacial acetic acid is added, eluting by 3-7mL of ethyl acetate, and drying; dissolving 240 mu L of acetonitrile, pipetting 150 mu L of dissolution liquid into a sample bottle, adding 50 mu L of derivatization reagent, heating by microwave for 1-7min, cooling and then measuring by gas chromatography-mass spectrometry. The method is rapid, simple, sensitive, accurate, specific and durable in confirmation and quantification, and is widely applied to the measurement filed of patulin in fruit jam and vegetable paste.
Owner:新疆出入境检验检疫局检验检疫技术中心
Preparation method of in-situ hydrophobic modified basic magnesium sulfate whisker
ActiveCN109930204AImprove performanceImprove hydrophobicityPolycrystalline material growthFrom normal temperature solutionsAlcoholEmulsion
The invention discloses a preparation method of an in-situ hydrophobic modified basic magnesium sulfate whisker. According to the preparation method, an alkaline solution is dropwise added into a magnesium sulfate solution, then fatty acid or fatty acid / alcohol is added to serve as an in-situ modifying agent to obtain emulsion, and after a hydrothermal reaction is conducted, the in-situ hydrophobic modified basic magnesium sulfate whisker is obtained. By conducting in-situ hydrophobic modification on the basic magnesium sulfate whisker, fatty acid substances such as oleic acid, stearic acid and palmitic acid are adopted to serve as the in-situ modifying agent, the basic magnesium sulfate whisker is directly modified in situ in the preparation process, thus the basic magnesium sulfate whisker has good hydrophobic performance, in the application process, the compatibility with a hydrophobic substrate can be reinforced, and the performance of a composite material is improved.
Owner:GUANGXI UNIV
Method for preparing submicron basic magnesium sulfate whisker with magnesite and prepared products
InactiveCN104073870AWide variety of sourcesReduce manufacturing costPolycrystalline material growthFrom normal temperature solutionsMagnesium Sulfate whiskersDistilled water
The invention relates to a method for preparing submicron basic magnesium sulfate whisker with magnesite and prepared products. The method is characterized by comprising steps of preparing magnesium oxide (obtained through calcining magnesite) into active magnesium oxide powder, then adding distilled water to prepare a magnesium oxide initial slurry with initial concentration of 0.25-1.25mol / kg, adding 1.0mol / dm<3> sulfuric acid aqueous solution and an additive-polyacrylamide to the initial slurry so as to obtain a base material, putting the base material into a high pressure reactor, heating up while stirring, preserving heat for 1.0-5.0 hours at constant temperature and constant pressure when the temperature in the reactor reaches 150-200DEG C, then stopping heating and stirring, air cooling to room temperature, and carrying out conventional treatment on the product to obtain the submicron basic magnesium sulfate whisker, wherein the draw ratio of the whisker is greater than 100, the average diameter is 100-300nm, and the content of single whisker is over 90%.
Owner:SHENYANG LIGONG UNIV
Chlorine ion curing agent for reinforced concrete and preparation method and applications thereof
The invention belongs to the technical field of chlorine ion curing agents, and especially relates to a chlorine ion curing agent for reinforced concrete and a preparation method and applications thereof. The curing agent is metal dihydroxide with a layered structure, has a micro-nano level granular shape, and is prepared by compounding 50 to 80 parts by weight of CaFe-NO3LDHs and 20 to 50 parts by weight of CaFeAl-NO3LDHs. The prepared chlorine ion curing agent does not damage a cement based material, and can stably and efficiently adsorb chlorine ions in a simulated concrete hole solution. In a cement paste sample, which has been soaked in a sodium chloride solution (3.5%), the corrosive performance of chlorine ions is obviously reduced, the effect is excellent, and the provided chlorineion curing agent is efficient and stable.
Owner:UNIV OF JINAN
High performance liquid chromatography (HPLC) detection method of Rivaroxaban
The invention discloses a high performance liquid chromatography (HPLC) detection method of Rivaroxaban. The method comprises the following steps: a. preparing a test solution; b. preparing a reference solution; c. respectively detecting the test solution and the reference solution by adopting HPLC, wherein the detection conditions are as follow: the stationary phase of a chromatographic column is silica gel which is coated with amylose-tri ((S)-alpha-methyl phenyl carbamate) on the surface, the mobile phase of the chromatographic column is acetonitrile-water, the flow velocity is 0.5-1.5ml / min, the column temperature is 10-40 DEG C, and the detection wave length is 200nm-300nm. After the detection method is used, the degree of separation of Rivaroxaban and Rivaroxaban R isomer is more than 3.0, and more theoretical plates are available, so that the detection result accuracy is effectively prevented from being influenced by the interference of all components; furthermore, the detection method has the advantages of being accurate and reliable in detection results, short in analysis time, low in cost, simple and convenient in operation, etc.
Owner:CHENGDU BAIYU PHARMA CO LTD
Curie-point pyrolyser of volatile matter generated by element in element determination
InactiveCN103792131ASlow heating rateSharp peak shape during measurementPreparing sample for investigationTube furnaceCrucible
The invention discloses a curie-point pyrolyser of a volatile matter generated by an element in element determination. The curie-point pyrolyser adopts a liner tube and a curie-point pyrolysis crucible or curie-point foil filled with samples, with larger volumes than that of a pyrolysis chromatograph part. The pyrolyser comprises a heating coil 1, a quartz reaction liner tube 2, a reaction cavity 3, a reaction tube seal plug and sample support integrated device 4, a carrier gas inlet 5, a carrier gas outlet 6, the sample crucible or foil 7, a support 8 for carrying the sample crucible or foil, and a bracket 9 for carrying the support of the crucible or foil, wherein the bracket 9 for carrying the support of the crucible or foil and a seal plug are connected with a rod. Compared with a conventional tubular furnace pyrolyser, the curie-point pyrolyser has the advantages that heating velocity is high, the time of generating the volatile matter by the element is short, spectrum peak is sharp in element determination, environment temperature is low, operation is safe, and the like, and is beneficial to the accurate element determination.
Owner:TIANJIN NORMAL UNIVERSITY
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