X射线荧光无标半定量分析奶粉微量元素

采用X射线荧光光谱半定量分析方法同时检测了奶粉样品中微量元素含量,以奶粉中主要营养成分含量为依据,模拟计算其平均分子式作为平衡项处理。结果表明,采用模拟的平均分子式作为平衡项处理,测定结果与给出的标准值吻合。该法样品处理简单,分析速度快,无需建立校准曲线,方法的准确度符合分析的需要。     

X射线荧光结合分子式模拟分析圆白菜主、次量元素

采用X射线荧光光谱半定量分析软件IQ 对圆白菜样品进行主、次量元素含量分析,以圆白菜中主要营养成分含量为依据,模拟其平均分子式.同时考察平衡项分子式的影响.结果表明,采用模拟的平均分子式作为平衡项处理,测定结果与给出的参考值较吻合.     

Analysis of the excited bottom and bottom-strange states B1（5721）, B2*（5747）,Bs1（5830）, Bs2*（5840）, BJ（5840） and BJ（5970） of the B meson family

In order to make a further confirmation of the assignments of the excited bottom and bottom-strange mesons B1(5721),B2^*(5747),Bs1(5830)and Bs2^*(5840)and identify possible assignments of BJ(5840)and BJ(5970),we study the strong decay of these states with the 3P0 decay model.Our analysis supports the assignments of B1(5721)and B2*(5747)as the 1P'1 and 1^3P2 states,and Bs1(5830)and Bs2^*(5840)as the strange partners of B1(5721)and B2^*(5747).Besides,we tentatively identify the recently observed BJ(5840)and BJ(5970)as the 2^3S1 and 13D3 states.It is noted that these conclusions need further confirmation by measurements of the decay channels BJ(5840)→Bπand BJ(5970)→Bπ.     

离子化程度对硼取代富勒烯C19Bn+（n=0-3）体系储氢性能的影响

本文采用密度泛函理论方法,研究了氢气分子在硼取代富勒烯C19Bn+（n=0-3）表面的非解离吸附态、化学吸附态、及吸附态之间转换过渡态的结构和能量,得到了吸附态之间转换反应的势能面. 研究表明通过调整体系的离子化电荷可以调整吸附位点的电荷布居数,随着硼取代富勒烯离子化体系C19Bn+的吸氢活性位点电荷布居数增大,氢分子被极化的程度以及氢分子在材料表面的吸附能均逐渐增大,同时改变电荷布居数也对氢气分子在表面吸附态间转变势垒高度产生了量级为几个Kcal/mol的影响. 希望我们的研究能够对富勒烯储氢的进一步发展提供参考.     

含温有界原子模型下电子与离子碰撞激发和电离截面的理论研究

采用扭曲波玻恩交换近似方法，在自由原子模型下计算了电子与离子碰撞激发、电离截面，计算值与实验一致；在含温有界平均原子模型下，系统研究了不同温度、密度等离子体中离子的电子碰撞直接电离截面，发现由于温度、密度效应导致离子的能级漂移，引起等离子体中离子的碰撞电离截面比自由原子情形发生较大变化. 关键词： 平均原子模型 扭曲波波恩交换近似 电离截面     

渤海地区地磁短周期变化异常、上地幔高导层的分布及其与唐山地震的关系

本文分析了渤海周围25个地磁台站1973—1979年急始、湾扰等短周期事件,以及静日、抗日和磁暴的频谱成分,发现包括唐山震区在内的渤海地区存在地磁短周期变化异常。北部的昌黎、宁河、宝坻一带异常最强,垂直分量的变化△Z为正,南部的烟台附近异常最强,△Z为负,周期为5分钟至2小时的异常变化最为明显。应用三维电磁感应的数值理论,拟合了与这种短周期地磁异常变化相应的上地幔高导层电性结构,发现渤海地区有一上地幔高导层的局部隆起,唐山地震位于隆起部位的北侧边缘。与隆起构造相应的附加热应力,其量级高达千巴,很可能是唐山地震的重要动力来源。     

多波长LED阵列诱导荧光光谱在多组分分析中的应用研究

荧光光谱技术是对水中的溶解有机物、油类污染物,以及各种浮游植物生物量识别与测量的有效手段之一。构建了多波长LED阵列(450～610 nm)诱导荧光光谱测量系统,讨论了系统的原理和利用此系统进行多组分分析的方法。在实验室应用该系统获取了多组分混合荧光物质溶液的三维荧光光谱,并采用平行因子算法分析了多组分三维荧光光谱数据,结果显示得出的多组分浓度值与实际浓度的相关性大于98％。表明基于多波长LED阵列诱导荧光光谱测量系统在多组分分析中具有很好的应用前景。     

CALCULATION OF KAON ELECTROMAGNETIC FORM FACTOR

The kaon meson electromagnetic form factor is calculated in the framework of coupled Schwinger-Dyson and Bethe-Salpeter formulation in simplified impulse approximation (dressed vertex) with modified flat-bottom potential, which is a combination of the flat-bottom potential taking into consideration the infrared and ultraviolet asymptotic behaviours of the effective quark-gluon coupling. All the numerical results give a good fit to experimental values.     

Stability analysis of multi-group deterministic and stochastic epidemic models with vaccination rate

We discuss in this paper a deterministic multi-group MSIR epidemic model with a vaccination rate, the basic reproduction number R0, a key parameter in epidemiology, is a threshold which determines the persistence or extinction of the disease. By using Lyapunov function techniques, we show if R0 is greater than 1 and the deterministic model obeys some conditions, then the disease will prevail, the infective persists and the endemic state is asymptotically stable in a feasible region. If R0 is less than or equal to 1, then the infective disappear so the disease dies out. In addition, stochastic noises around the endemic equilibrium will be added to the deterministic MSIR model in order that the deterministic model is extended to a system of stochastic ordinary differential equations. In the stochastic version, we carry out a detailed analysis on the asymptotic behavior of the stochastic model. In addition, regarding the value of R0, when the stochastic system obeys some conditions and R0 is greater than 1, we deduce the stochastic system is stochastically asymptotically stable.Finally, the deterministic and stochastic model dynamics are illustrated through computer simulations.