在CAMD/LSU用于软X射线发射光谱学研究的可变槽间隙光栅单色仪

在美国路易斯安娜州立大学高级微结构与装置中心(CAMD/LSU),一台配有可变槽间隙平面光栅的掠入射单色仪最近已投入运行。这台高通量、中分辩率的单色仪被用来作为软X射线发散光谱仪的激励源。近几年,CAMD/LSU的研究人员利用纽约州Upton的国家同步加速器光源(NSLS),成功地测出了不同物质的软X射线发射光谱(SXE)。例如:测得并报道了晶体硅和非晶硅的L_(23)发射限光谱与光子激励之间的函数关系,观测了绝缘化合物,如MgO、SiO_2的软X射线价带发射。

放射影像学在法医学尸体检验中的应用

目的:分析法医学尸体检验中放射影像学的应用价值。方法:以9具尸体作为研究对象,死于2017年2月—2017年12月,均给予解剖检验及CT检验,观察检验结果。结果:CT检验的检验时间、骨折总数、心脏破裂、肝血肿诊断准确率显著低于解剖检验(P<0.05),但肺挫裂伤、胸腔积液、蛛网膜下腔出血诊断准确率与解剖检验无明显差异(P>0.05)。结论:法医学尸体检验中,放射影像学具有一定的应用价值,可广泛应用,但仍存在不足之处,还需要继续加大研究与实践力度,促进放射影像学作用的充分发挥。

分子发光动态测定和化学及生物发光

本文综述过去二年中分子荧光和磷光的动态测定以及化学和生物发光的重要进展,重点放在紫外和可见波段分子发光方面。一。

Damage and fracture behavior and spatio-temporal evolution of acoustic emission of sandstone before and after laser radiation

Laser technology holds significant promise for enhancing rock-breaking efficiency.Experimental investigations were carried out on sandstone subjected to laser radiation,aiming to elucidate its response mechanism to such radiation.The uniaxial compressive strength of sandstone notably decreases by 22.1%–54.7%following exposure to a 750 W laser for 30 s,indicating a substantial weakening effect.Furthermore,the elastic modulus and Poisson ratio of sandstone exhibit an average decrease of 33.7%and 25.9%,respectively.Simultaneously,laser radiation reduces the brittleness of sandstone,increases the dissipated energy proportion,and shifts the failure mode from tensile to tension-shear composite failure.Following laser radiation,both the number and energy of acoustic emission events in the sandstone register a substantial increase,with a more dispersed distribution of these events.In summary,laser radiation induces notable damage to the mechanical properties of sandstone,leading to a substantial decrease in elastic energy storage capacity.Laser rock breaking technology is expected to be applied in hard rock breaking engineering to significantly reduce the difficulty of rock breaking and improve rock breaking efficiency.

导爆管起爆器瞬态电火花温度的光谱法测定

应用双谱线原子发射光谱测温法的原理 ,建立了一套石英光导纤维传输的瞬态实时双谱线测温系统 ,它的时间分辨率最高可达 0 1μs ,所采用的两条谱线的波长分别为CuⅠ 510 5和CuⅠ 52 1 8nm。利用该套装置 ,研究了在不同电压下导爆管起爆器的放电火花温度随时间的变化 ,以及不同放电条件下的电火花持续时间。试验表明 :对给定的起爆器火花的温度 ,是在 2 10 0～ 4 2 0 0K范围内变化 。

Analysis on Venting Time of Rarefaction Wave Gun

Based on the operation principle of rarefaction wave gun,the selection and calculation methods for venting opportune moment are invastigated. Considering property of the rarefaction wave,taking the center of muzzle section as initial calculation point,supposing that at the moment projectile arrives to the muzzle,the rarefaction wave arrives to the base of projectile,the rarefaction wave velocity along the barrel can be obtained by fitting calculation of the interior ballistic data of the same closed gun and reverse deduction. And then,the optimal venting time can be found out correctly based on the rarefaction wave velocity.

Flow injection chemiluminescence determination of meloxicam using potassium permanganate and formaldehyde system

A simple, rapid and sensitive flow injection chemiluminescence （FI-CL） method has been developed for the determination of meloxicam. The method is based on the CL-emitting reaction between meloxicam and potassium permanganate in a hydrochloric acid medium, enhanced by formaldehyde （HCHO）. Under optimum conditions, calibration curve over the range of 1.0-20.0μg/mL was obtained. The proposed method was successfully applied to the determination of meloxicam in capsules with no evi- dence of interference from common excipients. The detection limit of this method was 25.6 ng/mL. The relative standard deviation was 2.1% for 10.0 μg/mL meloxicam. The sample throughput was found to be 120 samples/h.

New type gate electrode of CNT-FED fabricated by chemical corrosive method

To obtain a triode structure canbon nanotube field emission display （CNT-FED）, the glass plate which contains a glass channels matrix is designed and used as the triode part of the CNT-FED. Normally, the gate electrode can be fabricated with screen printing methods and a channels matrix can be fabricated by two- faced chemical corrosion. By adjusting the etch time and the concentration of acid in the process, different shapes of the tunnels can be obtained. The size and morphology of channels are observed by a scanning electron microscope （SEM）, and the ingredients of the corrosion solution are detected by infrared ray （IR） analysis. Voltage is added to the triode structure for obtaining the brightness image of the spot on the screen. Eventually, the electron trace pulling from cathode to anode under an electric field is obtained by simulation. It is concluded that the simulation results accord with the experimental results which realize the optimized triode structure.

微波产生氮气等离子体中拟合转动温度的展宽效应

研究了微波产生的氮气等离子体同时转动温度是通过氮分子第二正带系C3Πu-B3Πg(振动跃迁0-2)的实验光谱拟合得到。详细讨论了转动光谱精细结构并且考虑所有可能的线展宽效应从而探究符合最好的拟合。自吸收线展宽效应被发现在低温弱电离等离子体的转动精细结构的拟合中占有重要地位同时采用自吸收效应的新展宽函数来拟合转动光谱,同时发现该展宽函数不会对拟合中估算转动温度造成大的差异。

Investigation on Methane Decomposition and the Formation of C2 Hydrocarbons in DC Discharge Plasma by Emission Spectroscopy

The IR emission spectra of methane were measured under DC glow discharge conditions. The distinct difference in time between methane decomposition and C2 hydrocarbons formation was specially pointed out. Ca hydrocarbons formed at the end of methane decomposition. The optimum condition for C2 hydrocarbon formation was studied and the optimum combination between electric current density and methane input quantity was suggested. The appropriate reaction conditions for methane decomposition and Ca hydrocarbons formation are different, so high yield of Ca hydrocarbons will be probably obtained when different conditions are taken.

氮气介质阻挡放电激发态氮的数值模拟研究

本文采用流体模型模拟了不同工作气体下N2介质阻挡放电。并利N2等离子体用发射光谱进行了实验对比。该模型考虑了10种反应物和28种反应。压力在1~5 atm之间,不同能级的N2(C)分子是典型的活性物质。模拟结果表明,在等离子体中,随着压力的增加,反应物N2(C)分子的数密度呈指数级下降。平均电子密度与压强的关系是复杂的,受中性粒子数密度和电子温度的影响。电子温度随压力范围的增大而降低。仿真结果可以描述等离子体参数的详细时空分布。由光谱计算得到的等离子体的平均电子温度、电子密度和N2(C)的激发趋势与模拟结果一致。

Interventional radiology procedures in adult patients who underwent liver transplantation

Interventional radiology has acquired a key role in every liver transplantation(LT)program by treating the majority of vascular and non-vascular post-transplant complications,improving graft and patient survival and avoiding,in the majority of cases,surgical revision and/or re-transplantation.The aim of this paper is to review indications,technical consideration,results achievable and potential complications of interventional radiology procedures after deceased donor LT and living related adult LT.

Effect of heterogeneity on mechanical and acoustic emission characteristics of rock specimen

The influence of heterogeneity on mechanical and acoustic emission characteristics of rock specimen under uniaxial compress was studied with numerical simulation methods.Weibull distribution function was adopted to describe the mesoscopic heterogeneity of rocks.The failure process of heterogeneous rock specimen under uniaxial loading was simulated using FLAC 3D software.Five schemes were adopted to investigate the influence of heterogeneity.The results demonstrate that as the homogeneity increases,the peak strength and brittleness of rocks increase,and the macro elastic modulus improves as well.Heterogeneity has great influence on macro elastic modulus and strength when the homogeneity coefficient is less than 20.0.The volume expansion is not so obvious when the homogeneity increases.As the homogeneity coefficient increases the acoustic emissions modes change from swarm shock to main shock.When the homogeneity coefficient is high,the cumulative acoustic emission events-axial strain curve is gentle before the rock failure.The numerical results agree with the previously numerical results and earlier experimental measurements.

Multispectral thermometry based on neural network

In order to overcome the effect of the assumption between emissivity and wavelength on the measurement of true temperature and spectral emissivity for most engineering materials, a neural network based method is proposed for data processing while a blackbody furnace and three optical filters with known spectral transmittance curves were used to make up a true target. The experimental results show that the calculated temperatures are in good agreement with the temperature of the blackbody furnace, and the calculated spectral emissivity curves are in good agreement with the spectral transmittance curves of the filters. The method proposed has been proved to be an effective method for solving the problem of true temperature and emissivity measurement, and it can overcome the effect of the assumption between emissivity and wavelength on the measurement of true temperature and spectral emissivity for most engineering materials.

Plasmonic Field Enhancement for Vibration Spectroscopy at Metal/Water Interfaces

Electrochemical （EC） reactions play vital roles in many disciplines, and its molecular-level understanding is highly desired, in particular under reactions. The vibration spectroscopy is a powerful in situ technique for chemical analysis, yet its application to EC reactions is hindered by the strong attenuation of infrared （IR） light in both electrodes and electrolytes. Here we demonstrate that by incorporating appropriate sub-wavelength plasmonic structures at the metal electrode, the IR field at the EC interface can be greatly enhanced via the excitation of surface plasmon. This scheme facilitates in situ vibrational spectroscopic studies, especially using the surface-specific sum-frequency generation technique.

Novel sensitivity analysis method and dynamics optimization for multiple launch rocket systems

This study establishes the launch dynamics method,sensitivity analysis method,and multiobjective dynamic optimization method for the dynamic simulation analysis of the multiple launch rocket system(MLRS)based on the Riccati transfer matrix method for multibody systems(RMSTMM),direct differentiation method(DDM),and genetic algorithm(GA),respectively.Results show that simulation results of the dynamic response agree well with test results.The sensitivity analysis method is highly programming,the matrix order is low,and the calculation time is much shorter than that of the Lagrange method.With the increase of system complexity,the advantage of a high computing speed becomes more evident.Structural parameters that have the greatest influence on the dynamic response include the connection stiffness between the pitching body and the rotating body,the connection stiffness between the rotating body and the vehicle body,and the connection stiffnesses among 14^(#),16^(#),and 17^(#)wheels and the ground,which are the optimization design variables.After optimization,angular velocity variances of the pitching body in the revolving and pitching directions are reduced by 97.84%and 95.22%,respectively.

Fracture evolution and localization effect of damage in rock based on wave velocity imaging technology

By utilizing wave velocity imaging technology,the uniaxial multi-stage loading test was conducted on siltstone to attain wave velocity imagings during rock fracture.Based on the time series parameters of acoustic emissions(AE),joint response characteristics of the velocity field and AE during rock fracture were analyzed.Moreover,the localization effect of damage during rock fracture was explored by applying wave velocity imagings.The experimental result showed that the wave velocity imagings enable three-dimensional(3-D)visualization of the extent and spatial position of damage to the rock.A damaged zone has a low wave velocity and a zone where the low wave velocity is concentrated tends to correspond to a severely damaged zone.AE parameters and wave velocity imagings depict the changes in activity of cracks during rock fracture from temporal and spatial perspectives,respectively:the activity of cracks is strengthened,and the rate of AE events increases during rock fracture;correspondingly,the low-velocity zones are gradually aggregated and their area gradually increases.From the wave velocity imagings,the damaged zones in rock were divided into an initially damaged zone,a progressively damaged zone,and a fractured zone.During rock fracture,the progressively damaged zone and the fractured zone both develop around the initially damaged zone,showing a typical localization effect of the damage.By capturing the spatial development trends of the progressively damaged zone and fractured zone in wave velocity imagings,the development of microfractures can be predicted,exerting practical significance for determining the position of the main fracture.

Physical and mechanical properties of Beishan granite after different high temperature treatments

In China,Beishan granite is chosen as a potential host surrounding rock of a high-level radioactive waste(HLW)repository.For this research,Beishan granite specimens were heated up to 300℃,400℃ and 500℃,respectively.And conventional triaxial compression tests were conducted after cooling down the samples.The results show that after 300℃,400℃ and 500℃ heating treatment,the diameter of samples increases by 0.066%,0.143%and 0.409%,respectively,which is a little larger than the axial length changes.Mechanical tests show that peak strength increases slightly with increasing temperature.However,the dilatancy threshold is lower than that observed for samples which have not experienced heating treatment.Peak strain and dilatancy threshold strain show a strong temperature dependence.The higher the temperature,the greater the strain.Furthermore,increasing temperature has negative influence on threshold elastic modulus E_(c) and tangent elastic modulus E_(t).Poisson ratio decreases when temperature increases from 300℃ to 500℃,but it is still larger than that observed for samples which have not experienced heating treatment.In addition,AE monitoring shows a quiet period in the initial loading stage,which proves that the micro cracks are closed during heating and contribute to the increase of peak strength.

Cross-Polarized Single Photon Emission from Single Semiconductor Quantum Dots with V-Type Level Driven by Pulse Field

The statistic properties of photon emissions from single semiconductor quantum dots with V-type leveldriven by pulses are investigated theoretically.Based on quantum regression theorem and master equations,the dynamicequations of the second-order correlation function of the photon emissions are deduced.The calculated results reveal thatthe efficiency of single photon emissions from two orthogonal polarization eigenstates(|x〉and |y〉)reaches the maximumwhen the input pulses area is about π,and the probability of the cross-polarized single photon emission from |x〉and |y〉decreases with increasing of pulse width.

Theoretical analysis of characteristics of acoustic emission in rock failure based on statistical damage mechanics

Based on statistical damage mechanics,the constitutive model of a rock underthree-dimensional stress was established by the law that the statistical strength of rockmicro-element obeys Weibull distribution.The acoustic emission (AE) evolution model ofrock failure was put forward according to the view that rock damage and AE were consistent.Moreover,in the failure process of rock under three-dimensional stress,the change inrelationship between stress condition parameter and the characteristic parameters of AE,such as the event number and its change rate,were studied.Also,the rock AE characteristicunder uniaxial compression was analyzed in theory and verified with examples.Theresults indicate that the cumulative event number and change rate of AE in rock failure aredetermined by stress state parameter F.Along with the gradual increase of F,first the cumulativeevent number increases gradually,then rapidly,and then slowly after the stresspeak.The form of change rate of an event by increasing F is consistent with the distributionform of rock micro-element strength.The model explained the phenomenon that a relativelyquiet period of AE appears before rock rupture that is observed by many researchersin experiments.Verification examples indicate that the AE evolution model is consistentwith the test results,so the model is reasonable and correct.