GFAAS中理论原子化效率与原子化温度的关系的研究

本文在有效地控制和消除基体干扰的基础上 ,探讨了Ag ,As,Au ,Bi,Cd ,Co ,Cr,Cu ,Fe ,Ga,Hg ,Mn ,Mo ,Ni,Sb ,Pb和V元素的理论原子化效率与原子化温度的关系。研究表明 :元素的理论原子化效率是原子化温度的函数 ,在一定的原子化温度范围内 ,理论原子化效率与原子化温度呈线性递增关系 ,对研究的十八个元素其线性的相关系数在 0 994 0～ 0 9993之间 ,且斜率大部分在 0 0 6～ 0 0 7之间 ,说明在一定的原子化温度范围内 ,理论原子化效率随原子化温度变化的斜率是相近的。     

ICP-AES法测定广西中药白花丹不同部位常量及微量元素

采用电感耦合等离子体发射光谱法(ICP-AES) 分析广西中药白花丹根、茎、叶3个部位的20种常量及微量元素。结果显示,白花丹中除了含人体必需的常量元素K,Ca,Na,Mg外, 还有Zn,Fe,Mn, Cr,Co等必需的微量元素和其他元素Mo, Sb,Bi,Cd, Sr,Pb,Cd,As等。各元素的含量在白花丹的根,茎,叶中分布不同, 在叶和根中的含量比较丰富,与白花丹的抗菌, 抗肿瘤及抗氧化活性的药用有效部位在根部和叶部的结果一致,如Na,K,Ca,Zn,Fe,Mn,Sr,Cu,Co等含量在叶中含量最高,根次之。在许多抗癌中药中,Zn,Mn,Fe的含量通常比较高,Cr,Sr,Cu的含量也至关重要,作为传统抗癌中药的白花丹中就含有丰富的Zn,Mn,Fe和一定量的Sr,Cr,Cu元素,测定结果为探讨中草药中常量、微量元素与生物活性之间的相互协同关系提供了有用的数据,也为更好地开发和利用白花丹药用资源提供理论依据。     

声学消息

恰好四十年前,Zwikker,Kosten的经典著作“Sound Absorbing Materials”出版(有中译本,席维克、柯斯汀《吸声材料》,科学出版社)奠定吸声材料的理论基础,Mechel的专著“Schallabsorber”是一个重大发展。书分三卷,卷一,外声场,即声场与吸声体的相互作用;卷二,内声场,即吸声体的构造,应用;卷三,计算程序,是辅助材料,现在出版的是卷一。本卷有十四章,1.引言,2.文献,3.声场基础;4.声场与吸声体相互作用,5.吸声带的吸收,6.柱形吸声体,7.吸收球,8.无穷平面吸声体,9.辐射阻抗,10.声场激发的表面辐射阻抗,11.表面波,     

稀土纳米金对银染效果的影响及其UV-Vis吸收光谱

制备了La,Ce,Nd,Sm,Eu,Gd,Dy微粒和纳米金,分别用La,Ce,Nd,Sm,Eu,Gd,Dy微粒替代部分的纳米金,研究了La-Au,Ce-Au,Nd-Au,Sm-Au,Eu-Au,Gd-Au,Dy-Au微粒分别对银染效果的影响及其紫外可见(UV-Vis)吸收光谱。与纳米金相比,La-Au,Ce-Au,Nd-Au,Sm-Au,Eu-Au,Gd-Au,Dy-Au微粒可延长银染后的斑点持续的时间,其中Nd-Au微粒的效果最好,斑点持续的时间为30 min,是纳米金的2.7倍;可大幅度加深斑点的颜色,其中Nd-Au,Sm-Au微粒的效果最好,用Nd微粒替代部分的纳米金,纳米金用量降低了80%,但还能提高银染法的灵敏度。在200～800 nm范围,La,Ce,Nd,Sm,Eu,Gd,Dy微粒和纳米金溶液的UV-Vis吸收光谱只有一个吸收峰,λ_max分别为275,277,276,276,278,277,278和521 nm;La-Au,Ce-Au,Nd-Au,Sm-Au,Eu-Au,Gd-Au,Dy-Au微粒混合液的UV-Vis吸收光谱有两个吸收峰,λ_max(RE)和λ_max(Au)分别为276和522 nm,276和522 nm,276和523 nm,276和523 nm,276和522 nm,276和522 nm,276和523 nm,纳米金和La微粒的吸收峰的波长发生了红移,Ce,Eu,Gd,Dy微粒的吸收峰的波长发生了蓝移,Nd,Sm微粒的吸收峰的波长不变,纳米金与稀土微粒可能有相互作用。     

影响南丰蜜桔品质的土壤元素ICP-MS/ICP-AES分析

南丰蜜桔是原产于江西南丰的优良品种,但是品质随着种植地区的不同差异较大。文章借助ICP-MS/ICP-AES技术对江西6个不同地区,生产南丰蜜桔品质的土壤中植物的必需元素进行了分析,以期找到影响南丰蜜桔品质的土壤因素。结果显示, 品质较好的3个地区土壤中B, P, K, Mg和Ca含量均高于品质较差地区的含量,特别是B, P和K含量差异显著,而Fe, Mn, Si, Cu和Zn含量则低于品质差的地区。上述结果表明南丰蜜桔的品质主要受B, P, K, Mg和Ca控制,尤其是B, P, K影响较大;而Fe, Mn, Si, Cu和Zn对南丰蜜桔品质影响较小。所以在种植南丰蜜桔时应当适当增加B, P, K, Mg和Ca等肥料的施用量。     

物理学咬文嚼字之二十准、赝、虚、假

物理学中表述"非真"意思的专有形容词有quasi,pseuclo,virtual,imaginary,false等,此外时常用到的还包括counterfeit,fake,fraudulent,feint,spurious,等等.用这些词构造的物理学名词随处可见,难以计数,真假难辩的境界里尤其考验学习者的分辨能力.     

手征SU(3)夸克模型研究低能Nπ散射相移

在手征,SU(3),夸克模型中,通过求解共振群方程动力学地研究了同位旋,I=1/2,和,I=3/2,道,Nπ,的,S,波和,P,波低能弹性散射相移.所用的模型参数由基态八重态和十重态重子的能量定出, 并能给出不同分波的,KN,散射相移.除了有明显共振态的道以外, 计算得到的各个分波的,Nπ,散射相移和实验值定性一致.     

从ψ′→J/ψπ+π－衰变中抽取ππ相移

ψ'→J/ψ π+π-,提供了一个抽取低于,0.59GeV,的,ππ S,波相移的新途径.基于在树图衰变振幅中忽略,D,波的近似, 给出了从,ψ'→J/ψ π+π-,的\,ππ,不变质量谱中得到,ππ S,波相移的公式.     

ICP-AES测定粉末冶金材料中钨、钼等八种元素

用硝酸、高氯酸和氢氟酸溶解样品,在0.025 mol·L-1 EDTA介质中,采用一种标准溶液,用ICP-AES光谱法测定样品溶液中Ni,Cu,V,Mn,W,Mo,Co,Cr的含量。研究了基体和共存元素对分析元素光谱的影响,选择合适的波长,测定了分析结果的精密度,方法的检出限和回收率,结果表明,分析方法有很低的检出限,样品分析结果的相对标准偏差小于1%,加入回收率在98.2%～101.6%,方法准确、可靠、简便、快速,满足生产要求。     

ICP-MS法测定食品级壳聚糖中的微量杂质元素

建立了电感耦合等离子体质谱(ICP-MS)法直接测定食品级壳聚糖中杂质元素的分析方法。壳聚糖用3%的柠檬酸溶解并加入低浓度盐酸后,采用ICP-MS法直接测定其中的Be,Na,Mg,K,Ca,Ti,V,Cr,Mn,Fe,Co,Ni,Cu,Zn,As,Cd,Sn,Sb,Hg,Pb等20种杂质元素。盐酸的使用有效地改善了元素的稳定性,尤其是Hg和Sn。选择动态反应池(DRC)技术消除了氯离子干扰以及其他质谱干扰,采用基体匹配法并通过加入Sc,Y,In,Bi内标元素混合溶液补偿了样品传输效率的差异以及有机溶剂蒸发速率的影响。在选定的工作条件下,20种元素的标准曲线方程具有良好的线性关系,线性相关系数不小于0.999 7,各元素的检出限在0.64～19.01 ng·L-1之间,加标回收率在89.50%～109.00%之间,相对标准偏差(RSD)在1.17%～4.05%之间,实际样品分析结果显示,食品级壳聚糖中杂质元素的含量较低,其中重金属元素的含量很低,食用安全。该方法能简便、灵敏、准确地测定食品级壳聚糖中的20种杂质元素。     

弱磁场中弱相互作用费米气体的有限粒子数效应(英文)

由弱磁场中弱相互作用费米气体的配分函数,导出有限粒子数条件下系统的配分函数G(β,N ).在此基础上,运用统计平均方法求解有限粒子数弱相互作用费米气体热力学量的解析表达式,给出各种温度条件下的热力学性质.研究结果表明,有限粒子数效应使各个热力学量都产生了一个修正项,除温度趋于0外,粒子数对化学势的修正项有直接影响,对内能和热容量的修正项并不产生直接影响.并且有限粒子数效应总是降低化学势,从而使化学势的0点向低温漂移,粒子数增大,会削弱这种效应,粒子间的相互排斥会加强这种效应.     

Power-law scalings in weakly-interacting Bose gases at quantum criticality

Weakly interacting quantum systems in low dimensions have been investigated for a long time, but there still remain a number of open questions and a lack of explicit expressions of physical properties of such systems. In this work, we find power-law scalings of thermodynamic observables in low-dimensional interacting Bose gases at quantum criticality. We present a physical picture for these systems with the repulsive interaction strength approaching zero; namely, the competition between the kinetic and interaction energy scales gives rise to power-law scalings with respect to the interaction strength in characteristic thermodynamic observables. This prediction is supported by exact Bethe ansatz solutions in one dimension, demonstrating a simple 1/3-power-law scaling of the critical entropy per particle. Our method also yields results in agreement with a non-perturbative renormalization-group computation in two dimensions. These results provide a new perspective for understanding many-body phenomena induced by weak interactions in quantum gases.     

强磁场中弱相互作用费米气体的热力学性质

基于赝势法和局域密度近似研究了强磁场中弱相互作用费米气体的热力学性质,得出化学势、总能和热容量的解析式,同时分析了磁场及相互作用对系统热力学性质的影响.研究表明,无论是高温情况还是低温情况下,磁场都能调节相互作用的影响.低温下,与无磁场的系统相比,磁场降低系统的化学势、总能和热容量;与无相互作用系统相比,排斥作用增加化学势而降低总能及热容量.高温下,磁场和排斥作用均可降低系统的总能而增加热容量,强磁场可以改变相互作用对总能及热容量的影响. 关键词： 强磁场 弱相互作用 费米气体 热力学性质     

Maxwell’s relations and thermal coefficients for repulsive clathrates

Prospects of nanotechnologies used for designing more effective thermomechanical devices and systems based on repulsive clathrates are outlined. Basic differences in thermodynamic properties of repulsive clathrates (that can be used for dissipation, accumulation, and transformation of large amount of energy in small volumes of working chambers) and traditional working bodies (gas/vapor) are demonstrated. Among unexpected characteristics of the systems being developed, the dependence of the adiabatic exponent on the parameters of the system is detected and negative values of the thermal elasticity coefficient are confirmed. The possibility of improving the accuracy of diagnostics of capillary-porous materials by taking into account additionally the thermal effects observed in repulsive clathrates is demonstrated.     

Dilute Bose gas revised

The well-known results concerning a dilute Bose gas with the short-range repulsive interaction should be reconsidered due to a thermodynamic inconsistency of the method being basic to much of the present understanding of this subject. The aim of our paper is to propose another way of treating the dilute Bose gas with an arbitrary strong interaction. Using the reduced density matrix of the second order and a variational procedure, this way allows us to escape the inconsistency mentioned and operate with singular potentials of the Lennard-Jones type. The derived expansion of the condensate depletion in powers of the boson density n=N/V reproduces the familiar result, while the expansion for the mean energy per particle is of the form epsilon=2 pi planck(2)an/m[1+128/(15 square root of [pi]) square root of [na(3)](1-5b/8a)+...], where a is the scattering length and b> or =0 stands for one more characteristic length depending on the shape of the interaction potential (in particular, for the hard spheres a=b). All the consideration concerns the zero temperature.     

Ground States of Lattice Gases with “Almost” Convex Repulsive Interactions

To the best of our knowledge there is only one example of a lattice system with long-range two-body interactions whose ground states have been determined exactly: the one-dimensional lattice gas with purely repulsive and strictly convex interactions. Its ground-state particle configurations do not depend on any other details of the interactions and are known as the generalized Wigner lattices or the most homogeneous particle configurations. The question of the stability of this beautiful and universal result against certain perturbations of the repulsive and convex interactions is interesting in itself. Additional motivations for studying such perturbations come from surface physics (adsorption on crystal surfaces) and theories of correlated fermion systems (recent results on ground-state particle configurations of the one-dimensional spinless Falicov–Kimball model). As a first step, we studied a one-dimensional lattice gas whose two-body interactions are repulsive and strictly convex only from distance 2 on, while its value at distance 1 can be positive or negative, but close to zero. We showed that such a modification makes the ground-state particle configurations sensitive to the tail of the interactions; if the sum of the strengths of the interactions from the distance 3 on is small with respect to the strength of the interaction at distance 2, then particles form two-particle lattice-connected aggregates that are distributed in the most homogeneous way. Consequently, despite breaking of the convexity property, the ground state exhibits the feature known as the complete devil's staircase.     

Discovery of the Griffiths phase in the itinerant magnetic semiconductor Fe1-xCoxS2

Critical points that can be suppressed to zero temperature are interesting because quantum fluctuations have been shown to dramatically alter electron gas properties. Here, the metal formed by Co doping the paramagnetic insulator FeS2, Fe1-xCoxS2 is demonstrated to order ferromagnetically at x > xc = 0.01+/-0.005, where we observe unusual transport, magnetic, and thermodynamic properties. We show that this magnetic semiconductor undergoes a percolative magnetic transition with distinct similarities to the Griffiths phase, including singular behavior at xc and zero temperature.     

Impurity-induced phase transition in the interacting Bose gas: 1. Analytical results

We derive selfconsistency equations for the density relaxation and the longitudinal dynamical conductivity of the interacting Bose gas at temperature zero moving in a random potential. The equations describe a disorder-induced transition from a superfluid phase to an insulating phase, where the density is non-ergodic. The interaction of the bosons is treated in random phase approximation and the coupling to the impurities is calculated within generalized selfconsistent current relaxation theory. Scaling laws are discussed and explicit results are presented for the repulsive Bosgas with neutral impurities and for the charged Bose gas with charged impurities.     

Thermodynamic Curvature of the Binary van der Waals Fluid

The thermodynamic Ricci curvature scalar R has been applied in a number of contexts, mostly for systems characterized by 2D thermodynamic geometries. Calculations of R in thermodynamic geometries of dimension three or greater have been very few, especially in the fluid regime. In this paper, we calculate R for two examples involving binary fluid mixtures: a binary mixture of a van der Waals (vdW) fluid with only repulsive interactions, and a binary vdW mixture with attractive interactions added. In both of these examples, we evaluate R for full 3D thermodynamic geometries. Our finding is that basic physical patterns found for R in the pure fluid are reproduced to a large extent for the binary fluid.     

Thermodynamic investigation of an insulator irradiated by a low-energy electron beam

The surface of an insulating material irradiated by a beam of low energy electrons charges positively if the yield of secondary electron is greater than unity. For such a dynamical equilibrium, the thermodynamic properties have been investigated by measuring the surface potential in response to a temperature oscillation of the material. It is shown that an oscillation amplitude of 0.4 K at 530 K induces an oscillation of the surface potential of about 0.5 volts. The frequency dependence indicates a monotonous decrease in the response with decreasing frequency, extrapolating to zero at zero frequency. We propose that this modification of the surface charge is driven by the temperature dependence of a gas of charged particles in equilibrium with the vacuum level.