用量气法测定CO_3~=和HCO_3~-的含量

CO_3~=和HCO_3~-混合物的分析一般可用经典的酸滴定法,耶维斯基(Г.Н.Евецкий)等在这方面也做了很多工作。但是,上述的这些方法都必须用指示剂进行酸碱滴定,故不适用于有色溶液或有缓冲剂存在的溶液中CO_3~=和HCO_3~-的分析。本文中提出的量气分析法克服了上述的缺点。对Na_2CO_33-NaHCO_3,(NH_4)_2CO_3-NH_4HCO_3和NH_4~ -Na~ -CO_3~=-HCO_3~-体系中CO_3~=和HCO_3~-的测定方法进行了研究,得到比较满意的结果。     

Backflow Transformation for A=3 Nuclei with Artificial Neural Networks

A novel variational wave function defined as a Jastrow factor multiplying a backflow transformed Slater determinant was developed for A=3 nuclei.The Jastrow factor and backflow transformation were represented by artificial neural networks.With this newly developed wave function,variational Monte Carlo calculations were carried out for ³H and ³He nuclei starting from a nuclear Hamiltonian based on the leadingorder pionless effective field theory.The obtained ground-state ene...     

Tensile properties of K-doped W–3%Re

In this work, the tensile properties of K-doped W–3%Re were investigated. This material was fabricated by powder metallurgy and hot rolling on an industrial scale. It is expected that there would be improvement of the high-temperature strength, an increase of the recrystallization temperature, and a decrease in the ductile–brittle transition temperature (DBTT) of pure tungsten due to the dispersion of K bubbles and the addition of 3% Re. In addition, suppression of the formation of irradiation-induced defect clusters is also expected. Tensile tests in the temperature range from room temperature to 1800 °C were conducted. After the tensile tests, fracture surface observations were carried out using a scanning electron microscope (SEM). The tensile strength decreased with increasing test temperature. Elongation of K-doped W–3%Re was observed above 500 °C. The results of fracture surface observation showed that delamination of the layered structure occurred at 500, 700, and 900 °C and cracking along the grain boundaries occurred at 1500 and 1800 °C.     

Thermal conductivity of Na2O–B2O3–SiO2 melts

Borosilicate glasses are candidate materials for the immobilization of high-level radioactive waste. The values of thermal conductivity of different borosilicate melts are thus indispensable information when optimizing the temperature distribution in a glass melting furnace. In this study, the thermal effusivity of Na₂O–B₂O₃–SiO₂ melts was measured using a front heating–front detection laser-flash method. The thermal conductivity, which can be obtained by combining the measured thermal effusivity with the specific heat capacity and density, was calculated using the least-squares method; the values for the Na₂O–B₂O₃–SiO₂ melts either slightly decreased linearly with increasing temperature or remained almost constant over the investigated temperature range. The values of thermal conductivity of the Na₂O–B₂O₃–SiO₂ melts were higher than those of B₂O₃–SiO₂ melts and lower than those of CaO–B₂O₃–SiO₂ melts. Furthermore, the thermal conductivity of the Na₂O–B₂O₃–SiO₂ melts was compared with those of the B₂O₃–SiO₂ and CaO–B₂O₃–SiO₂ samples.     

Predictions for production of superheavy nuclei with Z=105–112 in hot fusion reactions

Abstract The effects of mass asymmetry on the production of superheavy nuclei(SHN),within the dinuclear system model,are investigated in this study.It is observed that the fusion probability decreases with decreasing mass asymmetry.A total of 192 possible combinations of projectiles from O to Ti and targets with half-lives longer than30 days for producing SHN~(264)Db,~(265)Db,~(267)Sg,~(268)Bh,268Sg,~(269)Bh,~(271)Hs,~(271)Mt,~(272)Hs,~(272)Mt,~(273)Mt,~(274)Ds,275Ds,~(275)Rg,~(276)Ds,~(276)Rg,~(277)Rg,~(278)Cn,~(279)Cn,and~(280)Cn are examined.Further,the optimal combinations and incident energies for synthesizing these nuclei are predicted.Most of the cross sections for production of SHNare larger than 10 pb;therefore,the process can be carried out with the available experimental equipment.     

La2/3Ca1/3Mn1-xCrxO3（x=0.0，0.1）晶体结构的中子衍射研究

采用传统高温固相反应法合成钙钛矿型多晶样品。在室温下分别测量了La_2/3Ca_1/3Mn_1-xCr_xO₃(x=0.0,0.1)的中子粉末衍射谱,采用Rietveld峰形精修方法对衍射数据进行拟合,得到样品晶胞参数和原子坐标,根据原子坐标计算了与稀土锰氧化物宏观磁性能密切相关的锰氧键的键长和键角。     

Numerical investigation of Ar–NH_3 mixture in homogenous DBDs

In this paper, a study of homogenous dielectric barrier discharge Ar–NH_3 was made in order to investigate the electrical and the physical characteristics of homogenous discharge at atmospheric pressure. The discharge model includes the electrical module and the chemical kinetic module. The results obtained by the present model were compared with experimental work. The evolution of the plasmas voltage, the species densities, and the concentration of charged species are analyzed and discussed.     

类镁离子磁四极3s~2 ~1S_0-3s3p ~3P_2(Z=20~103)禁戒跃迁

采用全相对论多组态Dirac-Fock方法,对高离化类镁离子的磁四极3s2 1 S0-3s3p 3 P2(Z=20~103)自旋禁戒跃迁的能级间隔、跃迁波长、跃迁概率和振子强度等光谱跃迁参数进行了系统计算,计算中考虑了重要核的有限体积效应、Breit修正和QED修正,所得结果和最近已有的实验数据进行了比较。结果表明,高原子序数的高电荷离子(Z≥70)磁四极自旋禁戒跃迁几乎可与中性原子的光学允许跃迁相比拟,不仅在天体等离子体中,在ICF和MCF高温激光等离子体中,磁四极自旋禁戒跃迁和其他自旋禁戒跃迁(磁偶极、电四极)一样不容忽视,在双电子复合、不透明度、自由程等理论计算中应考虑其影响。     

Energy levels of Mg-like ions calculated in the model-potential relativistic perturbation theory: Z = 25–84

Energy levels of Mg-like ions are calculated by the relativistic perturbation theory (PT) using a model-potential (MP) zero-order approximation. The system consists of the 1s²2s²2p⁶ core and two valence electrons. The energy levels are obtained by diagonalization of the energy matrix calculated between all the 3l₁3l₂ states of the same parity and of the same total angular momentum J. The lowest order of the PT is treated exactly, whereas higher orders are included through an effective interaction. The contribution of the core polarization is accounted for by introducing an additional interaction V_pol(r₁r₂) between talence electrons. The introduction of V_pol(r₁r₂) in effect reduces the multielectron problem to a two-electron one with accuracy up to the second order of the PT. The calculation has been made for ions with nuclear charges Z = 25–84.     

Calculated wavelengths and oscillator strengths of n = 2-2 and 2–3 transitions for ions in the oxygen-like isoelectronic sequence between Mg V and Ni XXI

Wavelengths and weighted oscillator strengths are calculated for the 2s²2p⁴-2s2p⁵, 2s2p⁵-2p⁶, 2s²2p⁴-2s²2p³3s, and 2s²2p⁴-2s²2p³3d transition arrays for O-like ions in the isoelectronic sequence from Mg V to Ni XXI. The computational method involved the optimization of Slater parameters (radial energy integrals) based on empirical data. These parameters were first computed ab initio with a Hartree-Fock-Relativistic (HFR) program package which includes configuration-interaction and applies the Blume-Watson method for spin-orbit integrals. Ab initio HFR, SUPERSTRUCTURE, and multiconfiguration Dirac-Fock (MCDF) data are compared for Fe XIX and MCDF with HFR for Al VI. New and revised line classifications are tabulated for S IX to Fe XIX including those from the analysis of the solar flare Fe XIX spectrum.     

44 La2／3Ca1／3Mn1-xCrxO3（x=O.0，0.1）的中子衍射研究

自1993年发现混价锰氧化物La1-xAxMnO3中存在巨磁电阻（CMR）效应以来，由于其对基础研究和实际应用的重要意义，如：巨磁电阻材料在磁头、磁敏感元件、磁记录材料等方面有广阔的应用前景，因此引起了人们的广泛关注。     

As–Al recoil implantation through Si3N4 barrier layer

Al recoil implantation have been shown to be a possible alternative to direct Al ion implantation to avoid usual problems linked with Al sources. Poor efficiency of the recoil + annealing process is observed if no barrier or an oxyde screen layers are used. This problem can be solved using a Si₃N₄ screen layer. Then, P–N and N⁺/P/N structures can be obtained with deep low doped P-well with reduced thermal budget.     

3D Wave Propagation and an Ultra–Low-Frequency Instability in Magnetopause

A model set of equations for the low-frequency electromagnetic perturbations in a magnetized nonuniform plasma is presented. A more convenient and systematic procedure is suggested to treat the fluid equations in order to deduce electrostatic and electromagnetic limits. A general dispersion relation is derived for the waves propagating in 3D under local approximation in nonuniform plasmas, which includes almost all the known modes of cold ion magnetized plasmas in the limit < _i (where _i is the ion cyclotron frequency). Both the limits 1 and O(1) have been discussed briefly. The shear Alfvén waves and electromagnetic ion acoustic waves near ultra low frequency (ULF) range are found unstable in the high plasma of magnetopause. The results are in complete agreement with the satellite observations.     

Tensile and Charpy impact properties of an ODS ferritic/martensitic steel 9Cr–1.8W–0.5Ti–0.35Y2O3

A 9Cr-ODS ferritic/martensitic steel with a composition of 9Cr–1.8W–0.5Ti–0.35Y₂O₃ was fabricated by mechanical alloying and hot isostatic pressing, followed by hot rolling. Tensile properties were measured at room temperature (23 °C) and 700 °C in the rolling direction (LT) and the transverse direction (TL). The ultimate tensile strength (UTS) of the as-rolled samples in both directions reached 990 MPa at 23 °C, and still maintained at 260 MPa at 700 °C. The tensile strength and elongation of the rolling direction was greater than that of the transverse direction. The Charpy impact was tested from −100 to 100 °C in the LT direction. The lower shelf energy (LSE) was more than 65% of the upper shelf energy (USE). The total absorbed energy was separated into the energies for crack initiation and propagation. The propagation energy was always higher than the initiation energy in the range of temperatures tested. The ductile-to-brittle transition temperature (DBTT) of the rolled 9Cr ODS evaluated by an absorbed energy curve was about 0 °C. However, the high LSE and the fracture surface that still contained dimples at lower shelf indicated good toughness of the as-rolled 9Cr ODS steels at temperature of −60 °C.     

Development of thermodynamic databases in the system U–Zr–Ce–Cs–Fe–B–C–I–O–H for application to simulating phase equilibria in severe nuclear accidents

In case of severe nuclear accidents involving melt down of nuclear fuels at high temperatures, it is of considerable importance to accurately evaluate the highly-volatizing behavior of fission products (FPs) over multicomponent debris. Particularly, cesium (Cs)- and iodine (I)- bearing chemical species are regarded as notable FPs. In the present work, the authors have generated original thermodynamic databases for the system U–Zr–Ce–Cs–Fe–B–C–I–O–H featuring Cs- as well as I-bearing subsystems, which are contained in oxide, iodide, and metal (including borides and carbides) sub-databases. It has been confirmed that the phase diagrams calculated by the present set of the databases reproduce the corresponding literature data well in various kinds of subsystems of the above multicomponent system. The present set of databases has subsequently been applied to simulate phase equilibria and volatizing behavior of Cs- and I-including species, respectively, in multicomponent debris under specific temperature and atmospheric conditions corresponding to severe nuclear accidents.     

La_(2/3)Ca_(1/3)Mn_(1-x)Cr_xO_3(x=0.0,0.1)的中子衍射研究

自1993年发现混价锰氧化物La1-xAxMnO3中存在巨磁电阻(CMR)效应以来,由于其对基础研究和实际应用的重要意义,如:巨磁电阻材料在磁头、磁敏感元件、磁记录材料等方面有广阔的应用前景,因此引起了人们的广泛关注。本工作采用传统的固相反应法制备多晶样品La2/3Ca1/3Mn1-xCrxO3(x=     

Bremsstrahlung energy spectra from electrons with kinetic energy 1 keV–10 GeV incident on screened nuclei and orbital electrons of neutral atoms with Z = 1–100

A comprehensive set of bremsstrahlung cross sections (differential in the energy of the emitted photons) is tabulated. The set includes results for electrons with energies from 1 keV to 10 GeV incident on neutral atoms with atomic numbers Z = 1 to 100. For bremsstrahlung in the Coulomb field of the atomic nucleus, use was made of (a) results of Pratt, Tseng, and collaborators based on numerical phase-shift calculations for the screened Coulomb potential at energies below 2 MeV; and (b) the analytical high-energy theory (with Coulomb corrections) of Davies, Bethe, Maximon, and Olsen at energies above 50 MeV, supplemented by the Elwert Coulomb correction factor and the theory of the high-frequency limit given by Jabbur and Pratt. In the high-energy region, the effect of screening was included by the use of Hartree-Fock atomic form factors. A numerical interpolation scheme, applied to suitably scaled cross sections, was used to bridge the gap between the low-energy and high-energy theoretical results, and thus to obtain improved cross sections in the intermediate-energy region 2 to 50 MeV. Bremsstrahlung in the field of the atomic electrons was calculated according to the theory of Haug, combined with screening corrections derived from Hartree-Fock incoherent scattering factors.     

β-decay Study of T_z=-3/2Proton-rich Nucleus ~(29)S

<正>The exotic decay of nuclei far from the stability has recently become a hot topic of nuclear structure research.The nuclide ~(29)S is not well investigated in the A=4n+1,T_z=-3/2series of strong+β-delayed proton precursors.The decay schemes of these nuclei are characterized by     

T_z=-3/2的丰质子核~(29)Sβ衰变研究

正远离稳定线的丰质子区域一直以来都是核结构研究的焦点。29S是在一系列的A=4n+1,Tz=-3/2的β+缓发质子先驱核中,被研究得相对较少的核。从这一系列核的衰变纲图中可看到,大约有12%～100%的衰变道能够衰变到能出射质子的母核的非束缚态。通过精确的测量这些缓发质子的能量和强度,可以确定母核的激发态能量,并且进一步确定布居在这些质子上的β衰变跃迁强度。本课题组于2017年11月在中国科学院近代物理研究所兰州放射性束流线(Radioactive Ion Beam Line in Lanzhou,RIBLL)开展了丰质子核