比较分析黔产虫茶矿质元素及氨基酸含量

测定贵州不同产地虫茶的微量元素和游离氨基酸含量,了解其变化规律;矿质元素采用原子吸收光谱和分光光度法测定,氨基酸采用氨基酸自动分析仪测定。黔产虫茶C a元素含量最高,为5687m g/kg,Cu含量最低,为13m g/kg,丝氨酸含量最高,为516m g/100g,蛋氨酸含量最低,为46m g/100g,不同产地虫茶矿质元素和游离氨基酸含量变化差异大,相对标准偏差在0.1691—0.6903之间。黔产虫茶矿质元素和游离氨基酸含量体现较好品质,但含量差异大。     

纯硒中杂质元素的ICP-AES测定

电感耦合等离子体-原子发射光谱同时测定纯硒中的碲、铅、铋、锑、铜、铁、镍、铝、锡、砷和硼12种元素的含量,优化出各元素的分析波长和分析条件;用基体匹配补偿基体效应,方法简单,快速可靠,样品回收率为94%-107%.     

Structure and electrical properties of HfO<Subscript>2</Subscript> high-<Emphasis Type="Italic">k</Emphasis> films prepared by pulsed laser deposition on Si (100)

High-k gate dielectric hafnium dioxide films were grown on Si (100) substrate by pulsed laser deposition at room temperature. The as-deposited films were amorphous and that were monoclinic and orthorhombic after annealed at 500°C in air and N₂ atmosphere, respectively. After annealed, the accumulation capacitance values increase rapidly and the flat-band voltage shifts from −1.34 V to 0.449 V due to the generation of negative charges via post-annealing. The dielectric constant is in the range of 8–40 depending on the microstructure. The I–V curve indicates that the films possess of a promising low leakage current density of 4.2×10⁻⁸ A/cm² at the applied voltage of −1.5 V.     

First measurements with the neutron decay spectrometer a SPECT

The neutron decay spectrometera SPECT has been built to perform a precise measurement of the proton spectrum shape in the decay of free neutrons. Such a measurement allows a determination of the neutrino electron angular-correlation coefficienta . The present best experiments have an uncertainty of Δa/a = 5% and since the seventies there is no substantial improvement. Witha SPECT, we aim for an uncertainty which is lower by more than an order of magnitude, thus enabling us to perform several precise tests of the Standard Model. In our first beam time at the particle physics beam MEPHISTO at the Forschungsneutronenquelle Heinz Maier-Leibnitz, we studied the properties of the spectrometer. The most serious problem turned out to be the situation- and time-dependent behavior of the background. From the data sets from this beam time in which a background problem was not obvious, we could extract a value ofa = - 0.1151±0.0040^stat , but we could not quantify the background uncertainty. We show ways to deal with the background and other problems for future beam times.     

Beta-decay branching ratios of 62Ga

Beta-decay branching ratios of ⁶²Ga have been measured at the IGISOL facility of the Accelerator Laboratory of the University of Jyv?skyl?. ⁶²Ga is one of the heavier T _z = 0 , 0⁺ → 0⁺ β -emitting nuclides used to determine the vector coupling constant of the weak interaction and the V_ud quark-mixing matrix element. For part of the experimental studies presented here, the JYFLTRAP facility has been employed to prepare isotopically pure beams of ⁶²Ga . The branching ratio obtained, BR = 99.893(24) %, for the super-allowed branch is in agreement with previous measurements and allows to determine the ft value and the universal Ft value for the super-allowed β -decay of ⁶²Ga .     

Built-in electric field effect on the linear and nonlinear intersubband optical absorptions in InGaN strained single quantum wells

Considering the strong built-in electric field (BEF) induced by the spontaneous and piezoelectric polarizations and the intrasubband relaxation, we investigate the linear and nonlinear intersubband optical absorptions in In_xGa_1-xN/Al_yGa_1-yN strained single quantum wells (QWs) by means of the density matrix formalism. Our numerical results show that the strong BEF is on the order of MV/cm, which can be modulated effectively by the In composition in the QW. This electric field greatly increases the electron energy difference between the ground and the first excited states. The electron wave functions are also significantly localized in the QW due to the BEF. The intersubband optical absorption peak sensitively depends on the compositions of In in the well layer and Al in the barrier layers. The intersubband absorption coefficient can be remarkably modified by the electron concentration and the incident optical intensity. The group-III nitride semiconductor QWs are suitable candidate for infrared photodetectors and near-infrared laser amplifiers.     

微波消解ICP-AES测定黄瓜果实膨大生长过程中的矿质元素

采用微波消解电感耦合等离子体-原子发射光谱法对黄瓜果实膨大生长过程中的矿质元素B、Ca、Cu、Fe、K、Mg、Mn、Zn含量进行了测定,分析结果的相对标准偏差为0.22%—6.02%。该方法简单、快速、可靠、灵敏度高,且多元素可以同时测定,能满足实际样品分析需要。实验表明,在黄瓜果实膨大生长过程中,矿质元素的含量发生了显著变化,但整体上都呈下降趋势。在整个果实膨大过程中,Ca、K、Mg含量最高,Cu、Mn含量最低。该研究结果为今后深入研究矿质元素与果实膨大生长的相关性提供了理论依据。     

肉豆蔻与肉豆蔻衣的微量元素比较研究

对肉豆蔻和肉豆蔻衣中10种微量元素进行了含量测定,并进行对比。采用干法灰化处理样品,用电感耦合等离子体-原子发射光谱法(ICP-AES)同时测定了2种样品中的10种微量元素的含量。该法的加标回收率为90.0%—105.2%,相对标准偏差为0.31%—4.77%,具有良好的准确度和精密度。2种药材的微量元素含量有着明显的差异。     

微波消解ICP-AES测定苋菜的矿质元素

采用微波消解电感耦合等离子体-原子发射光谱法测定了苋菜中的矿质元素Ca、Cd、Cr、Cu、K、Fe、Mg、Mn、Na和Zn的含量,分析结果的相对标准偏差为0.12%—5.72%。该方法简单、快速、可靠、灵敏度高,且多元素可以同时测定,能满足实际样品分析需要。实验表明,苋菜中含有丰富的矿质元素,尤其是Ca、K、Mg含量较高,显示了苋菜较高的营养价值。     

微波消解-FAAS测定秦艽中8种微量元素的含量

利用微波消解-火焰原子吸收光谱法测定秦艽药材中8种微量元素钙、铜、铁、锰、锌、镁、铅、镉的含量。秦艽药材中含有较丰富的镁、钙、铁。该方法灵敏度高、快速、准确,所测数据可为秦艽药材的合理利用提供可靠依据。