β-环糊精修饰区带毛细管电泳法快速测定染料木甙、染料木素、山柰酚和芦丁

A method was developed to quickly determine genistin, genistein, kaempferol and rutin in Fructus sophorae by β -CDmodified capillary zone electrophoresis. Based on the investigation of the effects of buffer pH and concentration, β -CD concentration,SDS concentration, capillary temperature, the analytical conditions were optimized. Under the optimized conditions, the three analytes were well separated in less than 6 min. A good linear relationship between the peak area and concentration was found in the 2 ～ 400g/mL,2 ～ 300g/mL 2 ～ 200g/mL and 5 ～ 500g/mL concentration range for genistin, genistein, kaempferol and rutin, respectively. The detection limits were 0.8g/mL, 0.6g/mL, 0.6g/mL and 1.4g/mL for genistin, genistein, kaempferol and rutin, respectively.     

气相色谱-质谱法检测精神药品2C—B和芬特明

2C-B and Phentermine of psychic drugs were determinated by gas chromatography mass spectrometry (GC/MS). Mass ion fragment of the 2C-B was m/z230 and m/z232, m/z77, m/z91, m/z199, m/z201, m/z215, m/z217, m/z259 and m/z261;Mass ion fragment of acetic acid anhydride derivatives of the 2C-B was m/z242 and m/z244, m/z77,m/z148, m/z199 and m/z201, m/z229, m/z301 and m/z303. Mass ion fragment of the phentermine was m/z58, m/z91, m/z134;Mass ion fragment of acetic acid anhydrid ederivatives of the phentermine was m/z58, m/z91, m/z100, m/z117 and m/z134.     

热表面电离质谱精确测定人体排泄物中锌同位素丰度比

In this work isotope mass spectrometry was adopted for the study of determination of zinc absorption by using a double label stable isotope technique. The methods of the sample digestion, separation and measurement of trace zinc by using thermal ionization mass spectrometer were established, and the isotopic ratios of zinc in the excrements and urine were measured accurately. The reliable zinc absorption was obtained from this.     

Large-scale Experimental System for Multiphase Fuel/Air Explosions

A large-scale experimental system for multiphase combustion and explosion study was developed and manufactured.The explosion tank consists of a 2 m diameter,3.5 m long tube and ellipsoidal domes on both ends.The volume of the experimental tank is 10 m3.Pressure histories of the explosion pressure can be measured at different locations in the tank.High pressure glass windows of 200～300 mm were used to have access to the visualization of the explosion process.The explosion process of methane/air mixture and methane/coal dust/air mixture initiated by a 40 J electric spark at the center of the tank was studied in the large-scale experimental system.Five pressure sensors were arranged in the tank with different distances from the ignition point.Ten dust dispersion units were equipped to eject dust into the tank.A high-speed camera system was used to visualize the flame propagation during the explosion process.The characteristics of the pressure wave and flame propagated in methane/air mixtures and methane/coal dust/air mixtures have been studied and analyzed.     

膜提取-GC／MS大体积进样检测海洛因吸食者尿液中的代谢物

The article determines the heroin metabolites in urine by using the solid phase membrane extractor and GC/MS Large-Volume injection method. The recovery, linearity, and minimum detection level of morphine and monoactylmorphine were determined. The recoveries of morphine and monoactylmorphine were more than 80%; the minimum detection levels of them were below 0.01ug/ml; good linearity for both morphine and monoactylmorphine were obtained between 0.02～50ug. One urine specimens of heroin abuse were determined successfully by using this method.     

Finger Flexion Motion Inference from sEMG Signals

This paper provides a method to infer finger flexing motions using a 4-channel surface Electromyogram(sEMG).Surface EMGs are harmless to the human body and easily done.However,they do not reflect the activity of specific nerves or muscles,unlike invasive EMGs.On the other hand,the non-invasive type is difficult to use for discriminating various motions while using only a small number of electrodes.Surface EMG data in this study were obtained from four electrodes placed around the forearm.The motions were the flexion of each 5 single fingers(thumb,index finger,middle finger,ring finger,and little fingers).One subject was trained with these motions and another left was untrained.The maximum likelihood estimation method was used to infer the finger motion.Experimental results have showed that this method could be useful for recognizing finger motions.The average accuracy was as high as 95%.     

采用GC-MS-NCI方法检测毛发中大麻及其代谢物

The detection of Cannabis and their Metabolite (THC-COOH) in human Hair using GC-MS-NCI was reported.     

Theoretical Model and Experimental Research on Friction and Torque Characteristics of Hydro-viscous Drive in Mixed Friction Stage

The hydro-viscous drive(HVD) has been widely used in fan transmission in vehicles,fans,and scraper conveyors for step-less speed regulation or soft starting.In the mixed friction stage,the contact,friction,and torque characteristics of friction pairs are very complex and change at any time.The characteristics of the frictional and hydrodynamic lubrication states were studied in order to calculate and predict the friction and torque characteristics of the friction pairs in the mixed friction stage.The fluid torque was calculated by applying the average shear stress model and the load-carrying capacity of asperity was determined on the basis of the fractal contact theory.In addition,the contact friction coefficient of the friction pairs was taken into consideration and measured by using the MM1000-Ⅲ friction and wear testing machine.The asperity friction torque and total torque in the mixed friction stage were obtained and finally,the test rig for the torque characteristics was set up.The results show that the contribution to the total torque is shared by the oil film and the asperity friction.The friction coefficient decreases sharply at first and then increases with a change in the relative rotational speed,following the Stribeck curve closely,and the contact frictional coefficient slowly decreases with increase in the pressure between the friction pairs.The torque between the friction pairs is provided by the asperity friction,and the torque due to the oil film reduces to zero.When the thickness of the oil film is small,a major contribution to the total torque is due to the asperity friction.The total torque also increases with the decrease in the film thickness ratio.Therefore,by theoretical analysis and experimental verification,the torque of the friction pairs in the mixed friction stage can be accurately calculated using the average shear stress model and asperity friction torque model.     

Prediction of Wing Aerodynamic Performance in Rain Using Neural Net

A new method for prediction of wing aerodynamic performance in rain condition was presented.Three-and four-layer artificial neural networks based on improved algorithm for error Back Propagation(BP)network were respectively built.Detailed approaches to determine the optical parameters for network model were introduced and the specific steps for applying BP network model to predict wing aerodynamic performance in rain were given.On this basis,the established optimal three-and four-layer BP network model was used for this prediction.Results indicate that both of the network models are appropriate for predicting wing aerodynamic performance in rain.The sum of square error level produced by two models is less than 0.2%,and the prediction accuracy by four-layer network model is higher than that of three-layer network.     

Analytical Behavior of Fura-2 and Its Determination of [Ca2+]i in Lymphocytes Treated with Cefotaxime

The interaction of Fura-2 with Ca2+ is studied using steady fluorescence technique.The effect of pH on the spectra behavior of Fura-2 in the presence of Ca2+ is investigated,the excitation maxima(340 nm)and the isobestic point(360 nm)for the fluorescence spectra of Fura-2 depend on pH.At different temperatures the apparent dissociation constants(Kd)of Fura-2-Ca2+ complex are examined,Kd is found to decrease with increasing temperatures(20 ℃,37 ℃,50 ℃)and ΔH is calculated to be 21.16 kJ/mol by using the Van't Hoff equation at pH 7.4 for all the temperatures tested.The determination of intracellular Ca2+ concentration([Ca2+]i)in lymphocyte is developed by using Fura-2 as a fluorescence probe in the presence of Cefotaxime at 37 ℃ and pH 7.4.     

Abrasive Wear Mechanisms of Sand Particles Intruding into ATM Roller-scraper Tribosystem

The roller-scraper tribosystem of automatic teller machine(ATM) plays an important role in reliable cash requests.However,the abrasive wear of the polymer tribosystem becomes a prominent problem when operating in sandy environment.The wear behavior of the tribosystem in a simulated sandy environment has been experimentally studied previously.However the abrasive wear mechanism of roller-scraper tribosystems is still unknown to new design.The wear rates of polymer rollers were examined comprehensively and several jumping variations were found in the full data extent.Three wear stages were classified by the magnitude of wear rates,and different dominant wear mechanisms corresponding with different particle diameter were found by examining the worn surfaces.Accordingly a presumption was proposed that wear mechanisms in different stages were correlated with sand particles of different diameter.In a verification experiment,three typical wear mechanisms including cutting,ploughing,and wedging were found corresponding with different wear stages by scanning electron microscope(SEM) examination.A theoretical analysis was carried out with a simplified sphere particle intrusion model and the transfer conditions for different wear mechanisms were studied referring to the slip-field theory.As a main result,three typical wear models versus friction coefficient of particle/roller,and particle radius were mapped with variant hardness of the polymer roller and ratio of contact shear stress to bulk shear stress.The result illuminated the abrasive wear mechanism during particle intrusion.Particularly,the critical transition conditions gave the basis for improving the wear performance of roller-scraper tribosystems in a sandy environment.     

Selecting between Sequential Zoning and Simultaneous Zoning for Picker-to-parts Order Picking System Based on Order Cluster and Genetic Algorithm

The existing research of sequential zoning system and simultaneous zoning system mainly focuses on some optimization problems such as workload balance,product assignment and simulation for each system separately.But there is little research on comparative study between sequential zoning and simultaneous zoning.In order to help the designers to choose the suitable zoning policy for picker-to-parts system reasonably and quickly,a systemic selection method is presented.Essentially,both zoning and batching are order clustering,so the customer order sheet can be divided into many unit grids.After the time formulation in one-dimensional unit was defined,the time models for each zoning policy in two-dimensional space were established using filling curves and sequence models to link the one-dimensional unit grids.In consideration of "U" shaped dual tour into consideration,the subtraction value of order picking time between sequential zoning and simultaneous zoning was defined as the objective function to select the suitable zoning policy based on time models.As it is convergent enough,genetic algorithm is adopted to find the optimal value of order picking time.In the experimental study,5 different kinds of order/stock keeping unit(SKU) matrices with different densities d and quantities q following uniform distribution were created in order to test the suitability of sequential zoning and simultaneous zoning to different kinds of orders.After parameters setting,experimental orders inputting and iterative computations,the optimal order picking time for each zoning policy was gotten.By observing whether the delta time between them is greater than 0 or not,the suitability of zoning policies for picker-to-parts system were obtained.The significant effect of batch size b,zone number z and density d on suitability was also found by experimental study.The proposed research provides a new method for selection between sequential zoning and simultaneous zoning for picker-to-parts system,and improves the rationality and efficiency of selection process in practical design.     

Dynamic Analysis and Performance Verification of a Novel Hip Prosthetic Mechanism

To assist an amputee in regaining his or her daily quality of life, based on analysis of the motion characteristics of the human hip, a 2-UPR/URR parallel mechanism with a passive limb was designed. The inverse kinematics of this mechanism was analyzed based on a closed-loop vector method. The constrained Jacobian matrix and kinematic Jacobian matrix of each limb were then analyzed, and a 6 × 6 fully Jacobian matrix was constructed. Based on this, kinematic performances were analyzed and summarized. Finally, the dynamic model of the mechanism was constructed based on the virtual work principle, and its theoretical solution was compared with the numerical results, which were obtained in a simulation environment. Results showed that the prosthetic mechanism had a larger rotating workspace and better mechanical performance, which accorded a range of motion and bearing capacity similar to that of the human hip in multiple gait modes. Moreover, the validity of the dynamic model and inverse kinematics were verified by comparing the theoretical and simulation results. Furthermore, with flexion and extension, the torque change in the hip prosthetic mechanism was similar to that of the human hip, which demonstrated the feasibility of the hip prosthetic mechanism and its good dynamic performance.     

EFFECT OF SURFACTANTS ON Ni-TiN NANOCOMPOSITE COATINGS PREPARED BY ULTRASONIC ELECTRODEPOSlTION

Ni-TiN nanocomposite coatings were prepared by ultrasonic electrodeposition, and the effects of the surfactants on the coatings were investigated and the microstructure and micro rigidity of the coatings were characterized. Samples were also submitted to corrosion tests in 3% NaCl solution. The results showed that the surfactants had great effects on Ni-TiN nanocomposite coatings. The composite coatings prepared by ultrasonic electrodeposition with the surfactants were better than that of the coatings prepared without surfactants. The favorable properties of Ni-TiN nanocomposite coatings were prepared with the mixing of the non-ion and positive ion surfactants. The concentration of the mixing was 80 mg/L, and the ratio of the non-ion and positive ion surfactants was 1： 2.     

Study on the Gas Detonation Experimental System of Human Body Electrostatic Discharge

<正>The modeling system of the gas detonation by the human body electrostatic discharge(ESD)in coal mine is developed successfully,and the body's dynamic ESD model is established.To obtain a gas concentration causes by the explosions most easily in coal mine environment.The results provide an academic and experimental evidence for the safe electrostatic production and management in coal mine.The system adopts 77E58 as control core and the circuit optimized design,to take dual protection to the gas path and circuit of the system,systematic operation is safe and reliable.The experimental results show that the system can be carried out series of experiments of the human body ESD model detonating mixed gas,the measuring accuracy of gas concentration is 0.1%.And draws a conclusion that the gas concentration which causes the explosions most easily is 8.7%,but not the higher gas concentration is,the more explosive is.     

Surface Quality Improvement in Machining an Aluminum Honeycomb by Ice Fixation

A honeycomb structure is widely used in sandwich structure components in aeronautics and astronautics; however, machining is required to reveal some of its features. In honeycomb structures, deficiencies, such as burrs, edge subsiding, and cracking, can easily appear, owing to poor specific sti ness in the radial direction. Some e ective fixation methods based on a filling principle have been applied by researchers, including approaches based on wax, polyethylene glycol, iron powder, and(especially) ice. However, few studies have addressed the optimization of the cutting parameters. This study focused on optimizing the cutting parameters to obtain a better surface roughness(calculated as a roughness average or Ra) and surface morphology in the machining of an aluminum alloy honeycomb by an ice fixation method. A Taguchi method and an analysis of variance were used to analyze the e ects and contributions of spindle speed, cutting depth, and feed rate. The optimal cutting parameters were determined using the signal-to-noise ratio combined with the surface morphology. An F-value and P-value were calculated for the value of the Ra, according to a "smaller is better" model. Additionally, the optimum cutting parameters for machining the aluminum honeycomb by ice fixation were found at different levels. The results of this study showed that the optimal parameters were a feed rate of 50 mm/min, cutting depth of 1.2 mm, and spindle speed of 4000 r/min. Feed rate was the most significant factor for minimizing Ra and improving the surface morphology, followed by spindle speed. The cutting depth had little e ect on Ra and surface morphology. After optimization, the value of Ra could reach 0.218 μm, and no surface morphology deterioration was observed in the verified experiment. Thus, this research proposes optimal parameters based on ice fixation for improving the surface quality.     

Developing Flow Pressure Drop and Friction Factor of Water in Copper Microchannels

Experiments of de-ionized water flowing in microchannels made in copper blocks were carried out to obtain pressure drop and friction factor and to investigate any possible discrepancies from conventional theory. Three channels with widths of 0.5 mm, 1.0 mm, 1.71 mm, a depth of 0.39 mm and a length of 62 mm were tested. For adiabatic tests, the temperature of the working fluid was maintained at 30 ℃, 60 ℃ and 90 ℃ without any heat fluxes supplied to the test section. The experimental conditions covered a range of Reynolds numbers from 234 to 3,430. For non-adiabatic tests, the inlet temperature and heat flux applied were 30 ℃ and 147 kW/m2 and only for the 0.635 mm channel. The friction factors obtained for the widest channel （Dh = 0.635 mm） are reported for both adiabatic and non-adiabatic experiments to assess possible temperature effects. The paper focuses on the effect of hydraulic diameter on pressure drop and friction factor over the experimental conditions. The pressure drop was found to decrease as the inlet temperature was increased, while the friction factors for the three test sections did not show significant differences. The experimental friction factors were in reasonable agreement with conventional developing flow theory. The effect of temperature on friction factor was not considerable as the friction factor with and without heat flux was almost the same.     

Experimental study on size-dependency of effective permittivity of particle-gas mixture with agglomeration

The effective medium approximation （EMA） theory is the basis of a capacitance sensor used for concentration measurementof a particulate solid flow, its measurementresultis independenton particle size. In existence ofparticle agglomeration or aggradation, however, it is found that the effective permittivity of a gas/solid mixture is de-pendent on particle size. In this paper, a parallel plate, differential capacitance sensor is utilized to investigate theinfluence of particle size on the effective permittivity of the mixture in such a case. Static experiments using threematerials including glass, limestone and quartz particles were carried out in an off-line manner. The volume fractionof particles being tested ranged from20×10^-6to 600×10^-6, while the particle size was between 3 and 100μm.Experimental results showthat the effective permittivity of a particle-gas mixture with particle agglomeration is largerthan that predicted by EMA and the smaller the particle size, the larger the effective permittivity. The experimentprocess and analysis results are discussed in detail in the paper.     

Numerical Research on Performance Prediction for Centrifugal Pumps

Performance prediction for centrifugal pumps is now mainly based on numerical calculation and most of the studies merely focus on one model. Therefore, the research results are not representative. To make an improvement of numerical calculation method and performance prediction for centrifugal pumps, performance of six centrifugal pump models at design flow rate and off design flow rates, whose specific speed are different, were simulated by using commercial code FLUENT. The standard k-ε turbulence model and SIMPLEC algorithm were chosen in FLUENT. The simulation was steady and moving reference frame was used to consider the impeller-volute interaction. Also, how to dispose the gap between impeller and volute was presented and the effect of grid number was considered. The characteristic prediction model for centrifugal pumps is established according to the simulation results. The head and efficiency of the six models at different flow rates are predicted and the prediction results are compared with the experiment results in detail. The comparison indicates that the precision of head and efficiency prediction are all less than 5%. The flow analysis indicates that flow change has an important effect on the location and area of low pressure region behind the blade inlet and the direction of velocity at impeller inlet. The study shows that using FLUENT simulation results to predict performance of centrifugal pumps is feasible and accurate. The method can be applied in engineering practice.