用不同能量γ光子全能峰相对效率曲线和KCl测定24Na活度方法的研究

研究了利用NaI(φ76 mm×76 mm)探测器不同能量γ光子的全能峰相对效率曲线和分析纯KCl测量水溶液中24Na活度的方法.所谓相对效率是指不同能量对某一能量全能峰计数效率的归一值.这种方法不需要用活度精确已知的任何核素的标准溶液进行刻度.相对效率曲线的建立是将不同能量γ光子的相对效率与能量E的关系用最小二乘法拟合成一个函数f(E)=A+BE+CE2+DE3+UE4.这些γ能量(以MeV为单位)包括56Mn的0.8468、1.8108、2.113,27Mg的0.8438、1.0144,82Br的1.0439、1.3175、1.4748,以及38Cl的1.6422和2.1676.放射性核素都是利用一个约为130μg的252Cf中子源活化产生.本方法的原理可用于非24Na其他放射性核素溶液的活度测量,并且更适合于Ge探测器.当用Ge探测器时,仅用82Br的各种γ光子能量就能确定全能峰相对效率曲线.     

Na125I在碳纳米管中的填充

碳纳米管(CNTs)在经纯化、开口处理后，用Na^125I示踪，研究NaI溶液对CNTs的填充、洗涤以及它们从碳纳米管中的释放情况；用HREM、SEM、EDS对CNTs的填充情况进行了表征。结果显示CNTs管腔内有NaI填充并且在溶液中会缓慢释放出来。因此放射性核素示踪技术可以应用于CNTs的填充、释放等行为的研究。     

S U S Y 2

This package deals with supersymmetric functions and with the algebra of supersymmetric operators in extended N = 2 as well as in nonextended N = 1 supersymmetry. It allows us to make a realization of the SuSy algebra of differential operators, compute the gradients of given SuSy Hamiltonians and to obtain the SuSy version of soliton equations using the SuSy Lax approach. There are also many additional procedures included that are also encountered in the SuSy soliton approach, as for example the conjugation of a given SuSy operator, the computation of a general form of SuSy Hamiltonians (up to SuSy divergence equivalence), and the checking of the validity of the Jacobi identity for some SuSy Hamiltonian operators.     

铸造针孔和钠变质对ZL101铸铝合金组织和性能的影响

采用宏观检查和金相检验的方法，研究了铸造针孔和钠变质对ZL101铸铝合金组织和性能的影响。试验结果表明，在浇铸ZL101铸铝合金时，提高冷却速度，增加凝固压力，降低浇铸温度，同时进行钠变质处理，有利于铸造针孔的减少和组织的细化及力学性能的提高。     

Na2WO4-ZnO-WO3体系的粘度特性研究

Na2WO4-ZnO-WO3熔盐体系是熔盐镀钨所用的重要体系，研究了该体系摩尔组成在Na2WO4：40％～100％，ZnO：0％～37．5％。WO3:0％～60％范围内的粘度。结果表明：体系在温度约850℃时发生结构上的变化，导致体系粘度随WO3含量变化的规律或ZnO含量变化的规律在约850℃发生改变。     

Na2SO4对低硫水泥及其混凝土性能的影响

本文探讨了单掺Na2SO4对低硫水泥及其混凝土性能的影响。结果表明:少量的Na2SO4缩短了水泥凝结时间,有利于提高混凝土的坍落度、改善混凝土坍落度损失,而且在低温时可以明显改善混凝土的早期强度。     

Significantly reduced hysteresis in (Fe1/2Nb1/2)4+-modified 0.75Na1/2Bi1/2TiO3-0.25SrTiO3 lead-free piezoceramics with large strain

Aiming to get the NBT-based lead-free ceramic with high strain and low strain hysteresis for practical actuator applications, a solid solution of complex-ion (Fe_1/2Nb_1/2)⁴⁺doped 0.75Na_1/2Bi_1/2TiO₃-0.25SrTiO₃ ((Na_1/2Bi_1/2)_0.75Sr_0.25Ti_1-x(Fe_1/2Nb_1/2)_xO₃, abbreviated as NBST-100xFN) was designed and prepared, and its phase structure, micromorphology, ferroelectric, strain, dielectric and piezoelectric performances were systematically investigated. It was found that the incorporation of (Fe_1/2Nb_1/2)⁴⁺ causes a structure transition from the ferroelectric/relaxor (FE/RE) mixed phases to relaxor (RE) phase, increasing to a promising strain performance at x = 0.04 featured by not only a moderate strain value of 0.26%, corresponding normalized strain d₃₃* of 371 pm/V, but also a very small strain hysteresis of 22%. In addition, the NBST-4FN ceramic sample also exhibits an unexceptionable frequency-dependence of unipolar strain. This study provides a new understanding and design idea for the practical actuator application of high strain NBT-based lead-free ceramics with ultra-low hysteresis.     

Hydrogen solubility in liquid lithium–sodium alloys (90, 50, and 20 at% Li)

Hydrogen solubility in liquid Li–Na alloys (20, 50, and 90 at% Li) at 673, 773, and 873 K was investigated by adding and extracting hydrogen through the wall of a capsule made of pure iron. Hydrogen solubility in the Li₉₀Na₁₀ alloy was almost similar to that in pure Li while for Li₅₀Na₅₀ and Li₂₀Na₈₀, it was one and two orders of magnitude smaller, respectively. No obvious difference in temperature dependence was observed, similar to the case for pure Li. Li–Na alloy can thus be a potential liquid breeding material with almost all of the advantages of the Li blanket system and free of most of its drawbacks.     

Reversible Flat to Rippling Phase Transition in Fe Containing Layered Battery Electrode Materials

Layered sodium transition metal oxides of NaTMO₂ (TM = 3d transition metal) show unique capability to mix different compositions of Fe to the TM layer, a phenomenon that does not exist in LiTMO₂. Here, a novel spontaneous TM layer rippling in the sodium ion battery cathode materials is reported, revealed by in situ X‐ray diffraction, Cs‐corrected scanning transmission electron microscopy, and density functional theory simulation, where the softening and distortion of FeO₆ octahedra collectively drives the flat TM planes into rippled ones with inhomogeneous interlayer distance at high voltage. In such a rippling phase, charge and discharge of Na ions take different evolution pathways, resulting in an unusual hysteresis voltage loop. Importantly, upon discharge beyond a certain Na composition, the rippling TM layer will go back to flat, giving the reversibility of such structural evolution in the following cycles.     

Flexible sodium‐ion supercapacitor based on polypyrrole/carbon electrode by use of harmless aqueous electrolyte for wearable devices

With the emergence of various wearable devices, supercapacitors have gained immense attention because of their fast response rates. However, most supercapacitors use hazardous electrolyte materials, such as H₂SO₄, KOH, and acetonitrile. Leakage of these types of electrolytes during use would be very harmful to human skin. Therefore, a supercapacitor that does not employ hazardous materials is an attractive option for use in the energy‐storage components of wearable devices. Herein, we successfully demonstrate a Na‐ion supercapacitor (NISC) with a polypyrrole/carbon‐coated heat‐treated carbon felt electrode and an aqueous 0.4 M NaCl electrolyte, which is not harmful. Furthermore, our NISC with polypyrrole/carbon‐coated heat‐treated carbon felt exhibits a high specific capacitance (31.09 F g^?1) and a fast response rate (chargeable at 0.5‐s intervals). The proposed NISC with no harmful materials in the electrolyte has an excellent response rate. It will establish useful guidelines for the energy‐storage components in wearable devices Copyright © 2017 John Wiley & Sons, Ltd.