激光诱导Al表面等离子体温度的发射谱诊断

探测了脉冲能量0.3 J波长1064 nm的纳秒激光聚焦Al表面诱导的等离子体200-900 nm范围的发射谱.分析了线状谱的基本规律,根据谱线的强度,考虑到光谱仪与电荷耦合器件(charge coupled device,CCD)的探测效率,通过线性拟合给出了等离子体中AlⅠ、AlⅡ、NⅠ、OⅠ粒子的激发温度.根据谱线的半高宽计算了等离子体电子密度,进而计算了等离子中AlⅠ的电离温度.结果表明,在等离子体状态快速演化过程中,不同粒子的电离、激发与退激存在较大差异,AlⅡ、AlⅠ相对于NⅠ、OⅠ有较高的激发温度,并且等离子体中AlⅠ的电离温度高于所有粒子的激发温度.

Effect of sintering temperature on cycling performance and rate performance of LiNi_(0.8)Co_(0.1)Mn_(0.1)O_2

LiNi0.8Co0.1Mn0.1O2 powder was prepared by mixing LiOH·H2O and co-precipitated Ni0.8Co0.1Mn0.1（OH）2 at a molar ratio of 1：1.05, followed by sintering at different temperatures. The effects of temperature on the morphology, structure and electrochemical performance were extensively studied. SEM and XRD results demonstrate that the sintering temperature has large influence on the morphology and structure and suitable temperature is very important to obtain spherical materials and suppresses the ionic distribution. The charge-discharge tests show that the electrochemical performance of LiNi0.8Co0.1Mn0.1O2 powders becomes better with the increase of temperature from 700 ℃ to 750 ℃ and higher temperature will deteriorate the performance. Although both of materials obtained at 750 ℃ and 780 ℃ demonstrate almost identical cyclic stability at 2C rate, which delivers 71.9%retention after 200 cycles, the rate performance of powder calcined at 780 ℃ is much poorer than that at 750 ℃. The XRD results demonstrate that the poor performance is ascribed to more severe ionic distribution caused by higher temperature.

Effect of solar electron temperature on pep solar neutrino flux in the chlorine solar neutrino experiment and the gallium solar neutrino experiment

The rate of the electron-capture reaction of proton, p ＋ e^- ＋ p →2 H ＋ ve, is calculated considering the temperature of solar electron in the solar center instead of that of solar ion. When the solar electron temperature is two times higher than the solar ion temperature in the solar center, the capture rate pep solar neutrino predicted by the standard solar model （SSM） is decreased to （0.16±0.01 ） SNU from （0.22±0.01 ） SNU in the chlorine solar neutrino experiment, and decreased to 2.19 SNU from 3.0 SNU in the gallium solar neutrino experiment.

Synthesis and spark plasma sintering of Al-Mg-Zr alloys

Although casting is commonly used to process aluminum alloys, powder metallurgy remains a promising technique to develop aluminum based materials for structural and functional applications. The possibility to synthesize Al-Mg-Zr alloys through mechanical alloying and spark plasma sintering techniques was explored. Al-10Mg-5Zr and Al-5Mg-1Zr alloyed powders were synthesized through wet ball milling the appropriate amount of elemental powders. The dried milled powders were spark plasma sintered through passing constant pulsed electric current with fixed pulse duration at a pressure of 35 MPa. The samples were vacuum sintered at 450, 500, 550, 600 and 620 ℃ for 10, 15 and 20 min. The Al-10Mg-5Zr alloy displays poor densification at lower sintering temperatures of 450, 500, 550 and 600 ℃. Its sinterability is improved at a temperature of 620 ℃ whereas sintering temperatures higher than 620 ℃ leads to partial melting of the alloy. It is possible to sinter the Al-5Mg-1Zr alloy at 450, 500 and 550 ℃. The increase of sintering temperature improves its densification and increases its hardness. The Al-5Mg-IZr alloy displays better densification and hardness compared to Al-10Mg-5Zr alloys.

Time Evolution of the Multicomponent Laser Plasma Parameters

The emission of CulnSe2-based laser ablation plasma has been investigated at a distance of I mm from the target surface. The plasma was formed by radiation of the neodymium laser （5 ×10^8 W.cm^-2; 1,064 nm; 20 ns; 12 Hz）. The temporal dynamics have been obtained for the plasma parameters, such as the population of excited states of atoms, electron temperature and density. Two peaks were observed in the temporal profile of the population of excited states. The temporal dependence of electron temperature was singly peaked. During the time interval of 0-300 ns, the electron temperature varied in the range of 1.6-1.2 eV and the density of electrons varied in the range of 1.3 × 10^16 cm^-3 to 9 × 10^14 cm^-3. It has been established that at the selected conditions of plasma formation saved ratio of copper and indium, which correspond to stoichoimetric target composition.

Temperature Control of a Thermal Plasma Torch with Inductive Coupling Using the Arduino Board

Plasma torch is a device that transforms electrical energy into heat carried by a gas and its safe operation is necessary to control her temperature. This paper presents the use of the Arduino board in temperature control of a plasma torch through fuzzy control. The plasma torch of this project was built so that a flow of water can circulate through your body, allowing its cooling. The cooling system mounted consists of one radiator, one expansion vase, one water pump and one temperature sensor. The heated water coming the plasma torch is passed by the temperature sensor. This is converted in a voltage and read by an analog input port of the Arduino. This processes the information received and makes the decision to turn on/off the radiator fan and/or powered the frequency inverter water pump to control the temperature. The graph of the fuzzy control showed an oscillation between 104 °F to 122 °F around the chosen reference 113 °F. The results show that it is possible to control the temperature of a plasma torch using the Arduino board and fuzzy logic.

A Group Contribution Method for the Correlation of Static Dielectric Constant of Ionic Liquids

Static dielectric constant is a key parameter to estimate the electro-viscous effect which plays important roles in the flow and convective heat transfer of fluids with ions in microfluidic devices such as micro reactors and heat exchangers.A group contribution method based on 27 groups is developed for the correlation of static dielectric constant of ionic liquids in this paper.The ionic liquids considered include imidazolium,pyridinium,pyrrolidinium,alkylammonium,alkylsulfonium,morpholinium and piperidinium cations and various anions.The data collected cover the temperature ranges of 278.15-343.15 K and static dielectric constant ranges of 9.4-85.6.The results of the method show a satisfactory agreement with the literature data with an average absolute relative deviation of 7.41%,which is generally of the same order of the experimental data accuracy.The method proposed in this paper provides a simple but reliable approach for the prediction of static dielectric constant of ionic liquids at different temperatures.

Facile Synthesis of Coronene Dimers Having Unique Optical Properties

The authors synthesized very pure dimer phase of coroneae by simple heat-treatment and subsequent sublimation purification. It was confirmed by laser desorption/ionization mass spectroscopy measurements that pure dimer phase of coronenes can be obtained by controlling the fusing and sublimation temperatures. The crystal structure of the dimer phase was analyzed by synchrotron XRD （X-ray diffraction） experiments. It was also found that very bright red light is emitted by irradiating ultra violet light （λ = 350 nm） to the dimer phase. The external and internal quantum yields were determined to be 5.56% and 6.95%, respectively.

High-temperature treatment induced carbon anode with ultrahigh Na storage capacity at low-voltage plateau

Sodium-ion batteries （NIBs） show great prospect on the energy storage applications benefiting from thei low cost and the abundant Na resources despite the expected lower energy density compared wit lithium-ion batteries （LIBs）. To further enhance the competitive advantage, especially in energy densit3 developing the high-capacity carbon anode materials can be one of the effective approaches to realiz this goal. Herein, we report a novel carbon anode made from charcoal with a high capacity of ~400 Ah g i, wherein about 85% （〉330 mAh g^-1） of its total capacity is derived from the long plateau regio below ~0.1 V. which differs fiom those of typical hard carbon materials （~300 mAh g^-l） in NIBs but i similar to the graphite anode in LIBs. When coupled with air-stable Nao.gCuo.22Feo.3oMno.4802 oxid cathode, a high-energy density of ~240 Wh kg^-1 is achieved with good rate capability and cyclin stability. The discovery of this promising carbon anode is expected to further improve the energy densit of NIBs towards large-scale electrical energy storage.

Observational connection between local high-temperature phenomena within magnetic clouds and the Sun

Magnetic clouds(MCs) frequently show abnormal high-ionization states of heavy ions. The abnormal high-charge distributions are related to the coronal temperature of their source regions. We examined the plasma and magnetic field data of 74 MCs observed by the Advanced Composition Explorer from February 1998 to December 2008. We determined that 14 of the 74 events showed local high-temperature phenomena. We analyzed the correlation between proton temperature and O7/O6ratio(or high mean Fe charge state ?Fe?) within the local high-temperature regions in the 14 MCs. Results show that proton temperature and O7/O6 ratio(or high mean Fe charge state) had good correlations in nine MCs, but had no evident correlation in the other five MCs. The local high-temperature phenomena within the nine MCs have resulted from the Sun.

Controlling metallic Co^(0) in ZIF-67-derived N-C/Co composite catalysts for efficient photocatalytic CO_(2) reduction

An efficient photocatalytic CO_(2) reduction has been reported in ZIF-67-derived-Co nanoparticles(NPs)encapsulated in nitrogen-doped carbon layers(N-C/Co).This work demonstrates that the pyrolysis temperature is crucial in tuning the grain size and components of metallic Co^(0) of N-C/Co composite catalysts,which optimizes their photocatalytic activities.Syntheses were conducted at 600,700,and 800℃ giving the N-C/Co-600,N-C/Co-700,and N-C/Co-800 samples,respectively.N-C layers can well wrap the Co NPs obtained at a low pyrolysis temperature(600℃)owing to their smaller grains than those of other samples.A high metallic Co^(0) content in the N-C/Co-600 sample can be attributed to the effective inhibition of surface oxidation.By contrast,the surface CoOx oxides in the N-C/Co-700 and N-C/Co-800 samples cover inside Co cores,inhibiting charge separation and transfer.As a result,the N-C/Co-600 sample yields the best photocatalytic activity.The carbon monoxide and hydrogen generation rates are as high as 1.62×10^(4) and 2.01×10^(4)μmol g^(−1)h^(−1),respectively.Additionally,the Co NPs make composite catalysts magnetic,enabling rapid and facile recovery of catalysts with the assistance of an external magnetic field.This work is expected to provide an instructive guideline for designing metal-organic framework-derived carbon/metal composite catalysts.

Effect of Higher Order Axial Electron Temperature on Self-Focusing of Electromagnetic Pulsed Beam in Collisional Plasma

Effect of higher order axial electron temperature on self-focusing of electromagnetic pulsed beam in collisional plasma is investigated.It is shown that higher order axial electron temperature T p4 is not trivial than T p0 and T p2,which can modify slightly radial redistribution of electron density and increases effective dielectric constant.As a result,on one hand,slightly reduce electromagnetic beam self-focusing in the course of oscillatory convergence,on the other hand,quicken beam divergence in the course of steady divergence,i.e.,higher order axial electron temperature T p4 can decrease the influence of collisional nonlinearity in collisional plasma.