250～450kV高能X射线空气比释动能不确定度分析

目前,国际上对X射线空气比释动能基准的研究最高只达到400 kV,对于更高能量的X射线尚未建立相应基准。本文对自建立的250~450 kV X射线空气比释动能结果的不确定度进行了分析,分别得到了物理常数、有效测量体积、定位距离、电流测量、温度、气压、修正因子的不确定度。最终得到250~450 kV X射线空气比释动能结果的相对合成标准不确定度为0.31%,扩展不确定度为0.62%(k=2),其中不确定度来源中最大的2个量为电离功和修正因子,满足X射线空气比释动能复现的要求。

Influence of CO2 on Oxygen Surface Exchange Kinetics of Mixed- Conducting Ba0.5 Sr0.5 Co0.8 Feo.2O3_δ Oxide

The poisoning effect of CO2 on the oxygen surface exchange kinetics of BSCF （Ba0.5 Sr0.5 Co0.8 Feo.2O3_δ） is investigated with a novel pulse isotopic exchange technique. The surface exchange rate of BSCF severely decreases after in situ exposure to CO2, which is ascribed to carbonate formation on the material surface. The detrimental effect of CO2 starts at a low temperature of 375 ℃ and concentration as low as 1%, and becomes more pro- nounced at higher temperatures. Degradation of the surface exchange kinetics is associated with a rapid loss of oxygen permeation performance of BSCF in CO2.

Mediated protective effect of electroacupuncture pretreatment by miR-214 on myocardial ischemia/reperfusion injury

Background Electroacupuncture pretreatment plays a protective role in myocardial ischemia/reperfusion （I/R） injury and microRNAs （miRNAs） could act on various facets of cardiac function. However, the role of miRNAs in the cardioprotection by electroacupuncture pre-treatment on myocardial I/R injury remains unknown. The purpose of the study was to examine whether miR-214 was involved in cardio-protection by electroacupuncture. Methods Using rat myocardial I/R model, we examined the role of electroacupuncture pretreatment in myocardial I/R injury and analyzed the changes in the expression of miR-214. In addition, I/R was simulated in vitro by performing oxy-gen-glucose deprivation （OGD） on H9c2 cell cultures, and the effect of electroacupuncture pretreatment on I/R injury as well as expressional level of miR-214 were examined in vitro. Furthermore, the miR-214 mimic was transfected into OGD-treated H9c2 cells, we analyzed the cell apoptosis, lactate dehydrogenase （LDH） and creatine kinase （CK） activities, intracellular free Ca2＋concentration （[Ca2＋]i） as well as the relative protein levels of sodium/calcium exchanger 1（NCX1）, BCL2-like 11 （BIM）, calmodulin-dependent protein kinase IIδ（CaMKIIδ） and Cyclophilin D （CypD）. Results The in vivo results revealed that compared with the I/R group, the electroacupuncture pretreatment group showed significant decreased myocardial infarct size, as well as the increased indices of the cardiac function, including heart rate, mean arterial pressure, left ventricular systolic pressure and maximal rate for left ventricular pressure rising and declining （±dp/dt max）. In addition, electroacupuncture pretreatment could inhibit the elevation of LDH and CK activities induced by I/R injury. The quantitative PCR （qPCR） results demonstrated electroacupuncture pretreatment could provide cardioprotection against myocardial I/R injury in rats with miR-214 up-regulation. In the meanwhile, in vitro, electroacupuncture pretreatment protected H9c2 cells from OGD-induced injury. Trans-fection of miR-214 mimic showed protective effects on OGD-induced injury to H9c2 cells by reducing apoptosis, decreasing LDH and CK activities, rescuing the OGD-induced Ca2＋and down-regulating elevated protein levels of NCX1, BIM, CaMKIIδand CypD. Conclusions Our findings firstly demonstrated that electroacupuncture pretreatment promotes the expression of miR-214 in myocardial I/R injury and miR-214 contributes to the protective effect of electroacupuncture on myocardial I/R injury.

Calculation of Dielectric Function of a Quark-Gluon Plasma

With the hard thermal loop （HTL） resummation technique, we calculate the dielectric function excited by hard gluon in quark-gluon plasma （QCP）. We find that in a section of the space-like region po/p ∈ [0.78, 0.95], there are two extremum structures on the dielectric function curve, while the dielectric function in the HTL approximation decreases monotonously without these properties. Through the analyses of the imaginary part of the dielectric function, we conclude that the character of the dielectric function in this region reflects effects of the Landau damping.

A Combinational Power Analysis Method against Cryptographic Hardware

Power analysis is a non-invaslve attack against cryptographic hardware, which effectively exploits runtime power consumption characteristics of circuits. This paper proposes a new power model which combines Hamming Distance model and the model based on the template value of power consumption in combinational logic circuit. The new model can describe the power consumption characteristics of sequential logic circuits and those of combinational logic as well. The new model can be used to improve the existing power analysis methods and detect the information leakage of power consumption. Experimental results show that, compared to CPA（Correlation Power Analysis） method, our proposed attack which adopt the combinational model is more efficient in terms of the number of required power traces.

Simulation of radiation losses using non-coronal model on HL-2A

In this paper, the radiation losses of impurity on HL-2A have been simulated by assuming the profiles electron temperature and density and solving ionization rate equation under conditions of non-coronal radiation. The time required for an impurity species to establish equilibrium is proved to be sensitively dependent on the plasma electron temperature, and it is strongly correlated with the ionization state distribution during equilibrium establishment of impurity species, It is found from simulation results that the residence parameter plays an important role in the enhancement of radiation losses of plasma.

The effect of transition metal ions (M^(2+)=Mn^(2+),Ni^(2+),Co^(2+),Cu^(2+)) on the chemical synthesis polyaniline as counter electrodes in dye-sensitized solar cells

The effect of transition metal ions(M^(2+)=Mn^(2+),Ni^(2+),Co^(2+),Cu^(2+)) on the chemical synthesis of polyaniline(PANI) used as a platinum-free counter electrode(CE) in dye-sensitized solar cells(DSSCs) was investigated.PANI was synthesized by co-polymerization of aniline in the presence of different transition metal ions by using potassium dichromate in acidic medium. It was found that the ion doping of PANI showed a certain catalytic activity for the regeneration of traditional iodide/triiodide(I^-/I_3^-) redox couples. The power conversion efficiency(η) of PANI CEs doped with Mn^(2+),Ni^(2+),Co^(2+) (4.41%, 2.36% and 2.10%, respectively) were higher than 1.94%, the value measured for PANI CE without doping. Doping with Cu^(2+)decreased the power conversion efficiency of PANI CE(PANI-Cu^(2+) η = 1.41%). The electrical properties of the PANI, PANI-Ni^(2+), PANI-Co^(2+),PANI-Mn^(2+) and PANI-Cu^(2+) were studied by cyclic voltammetry(CV), impedance(EIS), and Tafel polarization curve. The experimental results confirmed that PANI was affected by the doping of different transition metal ions(M^(2+)=Mn^(2+),Ni^(2+),Co^(2+),Cu^(2+)). These results indicate a potential application of ion doped PANI as counter electrode in cost-effective DSSCs.

CHARACTERISTICS OF MULTIFOCAL ELECTRORETINOGRAM IN THE FELLOW EYES OF PATIENTS WITH HIGH MYOPIA WITH RETINAL DETACHMENT

Objective To observe the changes on multifocal electroretinography （MfERG） in the fellow eyes of patients with high myopia without fundus lesions and rhegmatogenous retinal detachment （RRD）. Methods MfERG was performed in 66 patients （ 66 eyes） which were grouped into ： emmetropes （ n = 22 ） as the control eye ; high myopes without fundus lesions （ corrected visual acuity ≥ 1. 0, n = 15 ） ; and fellow eyes of high myopics with RRD （n = 29 ）. The first-order kernels N1, P1, N2 response density and latency were analyzed. Results When compared with the emmetropes group, the high myopes group had significantly reduced N1 , PI , and N2 wave response densities in rings 1 to 6 （ P 〈 0. 05 ）, delayed N1 wave latency in rings 3 to 6, and P1 wave latency in rings 3 to 5 （ P 〈 0. 05 ）. The fellow eyes group had significantly reduced N1, P1, and N2 wave response densities in rings 1 to 6 and significantly delayed N1 and P1 wave latencies in rings 3 to 6 （ P 〈0. 05） compared with the emmetropes group. Compared with the high myopes group, P1 wave response densities in rings 1 to 6, N1 wave response densities in rings 1,3, 4, and 6, and N2 wave response density in ring 1 were significantly decreased in the fellow eyes group （ P 〈 0. 05 ） ; whereas there were no significant differences in latencies between the two groups （P 〉0.05）. Conclusion MfERG can sensitively assess the early changes in visual function in fellow eyes in patients with RRD.

Influences of Uncaptured Electron on Energy Conversion of Photon Compton Scattering in High Power Laser-plasma

Using the single particle theory and the non-flexibility collision model of electron and photon, the influence of the uncaptured electrons on the energy conversion efficiency of multi-photon nonlinear Compton scattering in the extra stationary laser-plasma is investigated. It shows that in extra stationary laser-plasma,the uncaptured electrons make the Δω of the scattering frequency of the multi-photon Compton fall down with the increases of the incident radiation electron speed,the materials of the incident collision of electron and photon, and the number of the photons which work with the electrons at the same time. Under the modulation of the uncaptured electrons to the laser field, the energy conversion efficiency between electrons and photons will fall down with the increase of the electron incident radiation speed, using the low-power electrons for incident source, the loss can be efficiently reduced.

Theoretical Analysis of the Interaction between the High-Power Microwave and the Electronic Circuits

A simple theoretical model based on plasma physics is presented to analyze the microwave plasma effects on the electronic circuits.Results show that under certain parameter conditions the threshold for damaging the electronic circuits decreases with the decrease of the frequency of the high-power microwave.In addition,the oscillation amplitudes of the plasma electrons increase dramatically when the plasma frequency is near the high-power microwave frequency, which can easily damage the electronic circuits.

Hybrid electromagnetic-triboelectric nanogenerator for harvesting vibration energy

We report a hybrid nanogenerator that includes a triboelectric nanogenerator （TENG） and an electromagnetic generator （EMG） for scavenging mechanical energy. This nanogenerator operates in a hybrid mode using both the triboelectric and electromagnetic induction effects. Under a vibration frequency of 14 Hz, the fabricated TENG can deliver an open-circuit voltage of about 84 V, a short-circuit current of 43 μA, and a maximum power of 1.2 mW （the corresponding power per unit mass and volume are 1.82 mW/g and 3.4 W/m^3, respectively） under a loading resistance of 2 MΩ, whereas the fabricated EMG can produce an opencircuit voltage of about 9.9 V, a short-circuit current of 7 mA, and a maximum power of 17.4 mW （the corresponding power per unit mass and volume are 0.53 mW/g and 3.7 W/m^3, respectively） under a loading resistance of 2 kΩ. Impedance matching between the TENG and EMG can be achieved using a transformer to decrease the impedance of the TENG. Moreover, the energy produced by the hybrid nanogenerator can be stored in a home-made Li-ion battery. This research represents important progress toward practical applications of vibration energy generation for realizing self-charging power cells.

Self-assembled multifunctional Fe_(3)O_(4) hierarchical microspheres: high-efficiency lithium-ion battery materials and hydrogenation catalysts

Self-assembled Fe_(3)O_(4)hierarchical microspheres(HMSs) were prepared by a one-pot synchronous reduction–self-assembling (SRSA) hydrothermal method.In this simple and inexpensive synthetic process,only glycerol,water,and a single iron source (potassium ferricyanide (K3[Fe(CN)6]))were employed as reactants without additional reductants,surfactants,or additives.The iron source,K3[Fe(CN)6],and glycerol significantly affected the synthesis of Fe_(3)O_(4)HMSs.Fe_(3)O_(4)HMSs with a self-assembled spherical shape readily functioned as high-performance anode materials for lithiumion batteries with a specific capacity of>1000 mA h g^(-1)at0.5 A g^(-1)after 270 cycles.Further charging and discharging results revealed that Fe_(3)O_(4)HMSs displayed good reversible performance (>1000 mA h g^(-1)) and cycling stability (700 cycles) at 0.5 A g^(-1).Furthermore,as multifunctional materials,the as-obtained Fe_(3)O_(4)HMSs also exhibited high saturation magnetization (99.5 emu g^(-1)) at room temperature (25°C) and could be further employed as efficient and magnetically recyclable catalysts for the hydrogenation of nitro compounds.

Thermal Modeling and Cooling Analysis of High-power Lithium Ion Cells

The heat generation model and three-dimensional computational fluid dynamics model for lithium ion cells were established with boundary conditions defined.In order to provide a better insight about the behaviors of high-power lithium ion cells under realistic discharge conditions,the temperature difference of the cells and an active thermal management system with a pure air-cooling mode were analyzed and predicted with the factors affecting the unevenness of temperature field discussed.The results show a significant effect of the cooling flow rate on the temperature rise of the cells for all discharge rates.Average surface temperatures are relatively uniform at lower discharge rate that makes it easier to control the temperature of the pack.Cell temperatures are expected to rise significantly toward the end of discharge and they show non-uniformity at higher discharge rates.Adequate air flow rate of active cooling is required at high discharge rate and high ambient temperature for practical pack thermal management system.

Synthesis and characterization of oriented linked LiFePO4 nanoparticles with fast electron and ion transport for high-power lithium-ion batteries

LiFePO4 nanoparticles with different morphologies and sizes were synthesized via a solvothermal method using environmentally benign and low-cost glycerol as the surfactant. The morphology, size, and structure of the particles were found to relate closely to the concentration of glycerol. Oriented linked LiFePO4 nanorods along mostly non-[010] were obtained with the proper concentration of glycerol. The nanorods showed good electronic and ionic conductivities, resulting in superior rate capability and cycling performance. This performance was attributed to the oriented linkages along mostly non-[010], the small particle size along [010], and the occupation of Li at Fe sites. Initial discharge capacities of 162.4 mA.h.g-1 at 0.1 C and 102.1 mA.h.g-1 at 30 C were achieved, with capacity retentions after 500 cycles at 5 and 20 C of 99.5% and 93.2%, respectively. At the rate of 40 C, the solid-solution phase transition dominated during lithiation and delithiation of all samples.

On-chip isotachophoresis separation of functional DNA origami capture nanoarrays from cell lysate

Scaffolded DNA origami, a versatile method to construct high yield self- assembled DNA nanostructures, has been investigated to develop water-soluble nanoarrays for label free RNA detection, drug delivery, molecular positioning and recognition, and spatially ordered catalysis of single molecule chemical reactions. Its attributes that facilitate these applications suggest DNA origami as a candidate platform for intracellular targeting. After the interaction with targeted proteins in cell lysate, it is critical to separate and concentrate DNA origami nanoarrays from the crude cell lysate for further analysis. The recent development of microchip isotachophoresis （ITP） provides an alternative robust sample preconcentration and electrophoretic separation method. In this study, we present online ITP for stacking, separation and identification of aptamer-functionalized DNA origami and its thrombin complex in a simple cross-channel fused silica microfluidic chip. In particular, the method achieved separation of a binding complex in less than 5 min and 150-fold signal enhancement. We successfully separated and analyzed the thrombin bound origami-aptamer spiked into cell lysate using on-chip ITP. Our results demonstrate that origami/thrombin nanostructures can be effectively separated from cell lysate using this method and that the structural integrity of the concentrated binding complex is maintained as confirmed by atomic force microscopy （AFM）. An ITP-based separation module can be easily coupled to other microchip pre- and post-processing steps to provide an integrated proteomics analysis platform for diagnostic applications.

Mesocrystal Co3O4 nanoplatelets as high capacity anode materials for Li-ion batteries

Faceted crystals with exposed highly reactive planes have attracted intensive investigations for applications. Herein, we demonstrate a general synthetic method to prepare mesocrystal Co3O4 with predominantly exposed {111} reactive facets by the in situ thermal decomposition from Co（OH）2 nanoplatelets. The mesocrystal feature was identified by field emission scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, and N2 isotherm analyses. When applied as anode material in lithium-ion batteries, mesocrystal Co3O4 nanoplatelets delivered a high specific capacity and an outstanding high rate performance. The superior electrochemical performance should be ascribed to the predominantly exposed {111} active facets and highly accessible surfaces. This synthetic strategy could be extended to prepare other mesocrystal functional nanomaterials.

Enhanced thermoelectric performance of Cu_(12)Sb_4S_(13-δ) tetrahedrite via nickel doping

Cu12Sb4S13 tetrahedrite has received great attention as an earth-abundant and environmental-friendly thermoelectric material. This work aims to uncover the thermoelectric performance-enhancing effect and the mechanism of nickel doping on tetrahedrite. A series of Cu12-xNixSb4S13-δ（x = 0.5, 0.7, 1.0, 1.5 and 2.0） compounds were synthesized by mechanical alloying combined with spark plasma sintering. It is found that the thermal conductivity sharply reduces with increasing Ni content over the entire temperature range,0.9 W m^-1K^-1, accompanied with an enhanced thermoelectric power factor. The model predicted that the reduced lattice thermal conductivity is attributed to mid-frequency phonon scattering, caused by precipitates and dislocations resulting from Ni doping. Consequently, a high ZT value up to 0.95 at 723 K was achieved for Cu11NiSb4S13-δ, corresponding to a ~46% increase over non-doped Cu12Sb4S13-δ. Furthermore,the cyclic measurement showed that the Ni-doped tetrahedrites displayed high chemical stability.