ICP-OES/ICP-MS测定葵花子中28种无机元素

建立了葵花子中微量元素组成的分析方法。采用HNO₃+H₂O₂混合酸为消解体系经微波消解葵花子样品,电感耦合等离子体发射光谱(ICP-OES)法测定葵花子中Al,B,Ca,Fe,K,Mg,Na,Si,P和S,电感耦合等离子体质谱(ICP-MS)法测定葵花子As,Ba,Cd,Co,Cr,Cu,Li,Mn,Mo,Ni,Pb,Rb,Sr,Sn,Sb,Ti,V和Zn。采用国家一级标准物质大米(GBW10045)验证了方法的准确性,结果表明,标准物质的测定结果与参考值基本一致,葵花子中Ca,K,Mg,P,S的含量较高。该方法具有良好的准确性和精密度。     

Fermi Level Unpinning and Schottky Barrier Modification by Ti, Sc and V Incorporation at NiSi2/Si Interface

A new method is proposed to modify the Schottky barrier height （SBH） for nickel silicide/Si contact. Chemical and electrical properties for NiSi2/Si interface with titanium, scandium and vanadium incorporation are investigated by first-principles calculations. The metal/semiconductor interface states within the gap region are greatly decreased, which is related to the diminutions of junction leakage when Ti-cap is experimentally used in nickel silicide/Si contact process. It leads to an unpinning metal/semiconductor interface. The SBH obeys the Schottky-Mort theory. Compared to Ti substitution, the SBH for electrons is reduced for scandium and increases for vanadium.     

X射线荧光光谱法测定不锈钢中的组分

用X射线荧光光谱法测定了不锈钢中Si、Mn、P、Cu、Ti、W、Mo、V、Ni、Cr、Nb等11种元素的含量。对磨样条件、准确度和精密度进行了实验,实验表明本方法与化学法所测结果相符。     

环带钾长石、榍石和锆石的显微结构与微区组成特征分析

南秦岭沙河湾石英二长岩中的钾长石、榍石和锆石具有明显的成分环带。利用电子探针(EPMA)波谱仪(WDS)、扫描电子显微镜(SEM)及其附带的能谱仪(EDS)和激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)对造岩矿物环带钾长石、榍石和锆石的显微结构与微区组成进行表征。结果表明：钾长石中K+被Na+,Ca2+,Ba2+,Fe2+和Ce3+不同程度替代。榍石中Ca2+被V3+,Ce3+和Ba2+等替代,Ti4+被Fe2+和Al3+等替代。锆石含Fe,Th,U,Nb,Ta,Y,Hf,Yb和Pb等稀土和微量元素。钾长石中元素浓度由高到低为Si,Al,K,Ca,Na,Mg和Ba,其中K和Na互补,较亮处Ba含量高,越靠近边缘,Si升高、K升高与Na降低趋势越明显。榍石中元素浓度由高到低为Ca,Si,Ti,Ba,V,Ce,Al和Fe,较亮处Fe含量较高。锆石中元素浓度由高到低为Zr,Si,Nd,Ce,Hf,U,Pb和Th,Hf与Zr呈明显的互补关系,核部Zr含量较边部高,核部Hf、U和Th含量较边部低。     

Determination of elemental composition of Lake Baikal sponges by wavelength dispersive X‐ray fluorescence spectrometry

Sponge endemic species inhabit the Lake Baikal from the ancient times. Because the sponges are the biological filters of the Baikal water and they contribute greatly to silicon circulation in the lake, it is crucial to analyze their composition. Only a few publications report the analytical data concerning the element composition of Lake Baikal sponges. However, the analytical data were mainly obtained by destructive methods. No data on the concentrations of some alkaline and volatile elements are available so far. This article describes the application of wavelength dispersive X‐ray fluorescence spectrometry to study the sponges of Lubomirskia baicalensis, Baikalospongia bacillifera, and Baikalospongia recta species collected at the littoral part of the Beryozovy Cape in the Southern Baikal. The concentrations of 19 elements Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, and Ba have been determined. In this article, we discuss the problem of selecting calibration samples for wavelength dispersive X‐ray fluorescence spectrometry, because appropriate reference samples are not available. The synthetic specimens, prepared by mixing plant certified reference materials and silicon dioxide in certain proportions, were proposed for calibration. The compositions of sponges cleaned from mineral particles and symbiotic organisms, as well as unwashed sponges, have been compared. Copyright © 2013 John Wiley & Sons, Ltd.     

Ti/4H-SiC肖特基势垒二极管抗辐射特性的研究

本文采用γ射线、高能电子和中子对Ti/4H-SiC肖特基势垒二极管(SBD)的抗辐射特性进行了研究.研究发现对于γ射线和1 MeV电子辐照,-30 V辐照偏压对器件的辐照效应没有明显的影响.经过1 Mrad(Si)的γ射线或者1×l0¹³ n/cm²的中子辐照后,Ti/4H-SiC肖特基接触都没有明显退化;经过3.43×10¹⁴ e/cm²的1 MeV电子辐照后Ti/4H-SiC的势垒高度比辐照前轻微下降,这是由于高能 关键词： 碳化硅 肖特基 辐照 偏压     

长期绿肥翻压对西北旱地小麦籽粒矿质元素含量的影响

绿肥对保障作物高产、土壤培肥和养分高效利用有重要影响,但长期翻压绿肥对旱地小麦籽粒矿质元素的影响尚不清楚。故依托甘肃武威25年长期定位试验,采集试验中不施肥、化肥和绿肥3个处理的小麦成熟期籽粒样品,利用电感耦合等离子体质谱仪(ICP-MS)技术分析了长期绿肥翻压对小麦籽粒矿质元素的影响。结果表明,绿肥处理下小麦籽粒大部分矿质元素含量较不施肥处理有增加趋势,其中硅、铁和铷元素含量均较不施肥和化肥处理显著增加;绿肥处理下籽粒重金属元素与不施肥处理无显著性差异,但镍含量较化肥处理表现增加。因而,长期绿肥翻压能有效提高旱地小麦部分矿质营养元素,有利于在保障小麦高产的同时提高籽粒营养品质,但也应关注绿肥翻压对重金属元素在土壤-作物系统中行为的影响。     

Silica-based composite and mixed-oxide nanoparticles from atmospheric pressure flame synthesis

Binary TiO₂/SiO₂ and SnO₂/SiO₂ nanoparticles have been synthesized by feeding evaporated precursor mixtures into an atmospheric pressure diffusion flame. Particles with controlled Si:Ti and Si:Sn ratios were produced at various flow rates of oxygen and the resulting powders were characterized by BET (Brunauer–Emmett–Teller) surface area analysis, XRD, TEM and Raman spectroscopy. In the Si–O–Ti system, mixed oxide composite particles exhibiting anatase segregation formed when the Si:Ti ratio exceeded 9.8:1, while at lower concentrations only mixed oxide single phase particles were found. Arrangement of the species and phases within the particles correspond to an intermediate equilibrium state at elevated temperature. This can be explained by rapid quenching of the particles in the flame and is in accordance with liquid phase solubility data of Ti in SiO₂. In contrast, only composite particles formed in the Sn–O–Si system, with SnO₂ nanoparticles predominantly found adhering to the surface of SiO₂ substrate nanoparticles. Differences in the arrangement of phases and constituents within the particles were observed at constant precursor mixture concentration and the size of the resultant segregated phase was influenced by varying the flow rate of the oxidant. The above effect is due to the variation of the residence time and quenching rate experienced by the binary oxide nanoparticles when varying the oxygen flow rate and shows the flexibility of diffusion flame aerosol reactors.     

High-intensity ultrasound-based process strategies for obtaining edible sunflower (Helianthus annuus L.) flour with low-phenolic and high-protein content

The sunflower Helianthus annuus L. represents the 4th largest oilseed cultivated area worldwide. Its balanced amino acid content and low content of antinutrient factors give sunflower protein a good nutritional value. However, it is underexploited as a supplement to human nutrition due to the high content of phenolic compounds that reduce the sensory quality of the product. Thus, this study aimed at obtaining a high protein and low phenolic compound sunflower flour for use in the food industry by designing separation processes with high intensity ultrasound technology. First, sunflower meal, a residue of cold-press oil extraction processing, was defatted using supercritical CO₂ technology. Subsequently, sunflower meal was subjected to different conditions for ultrasound-assisted extraction of phenolic compounds. The effects of solvent composition (water: ethanol) and pH (4 to 12) were investigated using different acoustic energies and continuous and pulsed process approaches. The employed process strategies reduced the oil content of sunflower meal by up to 90% and reduced 83% of the phenolic content. Furthermore, the protein content of sunflower flour was increased up to approximately 72% with respect to sunflower meal. The acoustic cavitation-based processes using the optimized solvent composition were efficient in breaking down the cellular structure of the plant matrix and facilitated the separation of proteins and phenolic compounds, while preserving the functional groups of the product. Therefore, a new ingredient with high protein content and potential application for human food was obtained from the residue of sunflower oil processing using green technologies.     

基于高光谱的膜下滴灌小麦氮素营养评价研究

通过小麦氮素和品种对比试验,分析不同氮素和品种处理小麦生育期氮肥偏生产力与光谱参数的相关关系,建立小麦氮肥偏生产力的光谱参数估算模型,结果表明绿度植被指数(GREENNDVI)在拔节期与小麦氮肥偏生产力呈极显著相关,相关系数0.640 4。用GREENNDVI在拔节期建立小麦氮肥偏生产力的估算模型,均方根误差0.459 7。研究表明利用光谱参数可以有效地估算小麦氮肥偏生产力。     

植物标样多元素测定的五种前处理方法比较

本文采用植物样品的五种前处理方法,即干灰化法,硝酸＋硫酸＋高氯酸法,硝酸＋硫酸＋高氯酸＋氢氟酸法、硫酸＋过氧化氢法、灰化＋碱熔法,对植物标样ＧＢＷ０７６０３作样品分解,试液用ＩＣＰ－ＡＥＳ法进行十九种常量及微量元素的测定。     

A comparison study on the electronic structures,lattice dynamics and thermoelectric properties of bulk silicon and silicon nanotubes

In order to investigate the mechanism of the electron and phonon transport in a silicon nanotube(SiNT),the electronic structures,the lattice dynamics,and the thermoelectric properties of bulk silicon(bulk Si)and a SiNT have been calculated in this work using density functional theory and Boltzmann transport theory.Our results suggest that the thermal conductivity of a SiNT is reduced by a factor of 1,while its electrical conductivity is improved significantly,although the Seebeck coefficient is increased slightly as compared to those of the bulk Si.As a consequence,the figure of merit(ZT)of a SiNT at 1200 K is enhanced by 12 times from 0.08 for bulk Si to 1.10.The large enhancement in electrical conductivity originates from the largely increased density of states at the Fermi energy level and the obviously narrowed band gap.The significant reduction in thermal conductivity is ascribed to the remarkably suppressed phonon thermal conductivity caused by a weakened covalent bonding,a decreased phonon density of states,a reduced phonon vibration frequency,as well as a shortened mean free path of phonons.The other factors influencing the thermoelectric properties have also been studied from the perspective of electronic structures and lattice dynamics.     

Energy‐dispersive XRF spectrometer for Ti determination (TITAN)

An energy‐dispersive XRF analyser was designed and constructed for determining Ti in plant and peat materials at low (ppm) concentrations. The XRF analyzer for Ti analysis (TITAN) uses monochromatic excitation obtained from a crystal diffraction monochromator and Co target x‐ray diffraction tube. In addition to precise and sensitive analyses of Ti, other minor elements (Ca, K, Cl, S, P, Ba) in powdered plant and peat samples can be measured with only a minimum of sample preparation (drying, milling). The limits of detection obtained are K 2.5, Ca 1.5, Ti 0.9, Cr 0.7 and Mn 0.5 ppm using a 600 s acquisition time. The instrument was used to determine Ti concentrations in pre‐anthropogenic peat samples up to 9000 years old. Copyright © 2004 John Wiley & Sons, Ltd.     

Multinuclear (27Al, 29Si, 47,49Ti) solid-state NMR of titanium substituted zeolite USY

Multinuclear solid-state NMR spectroscopy, employing 29Si MAS,27Al MAS/3Q-MAS and (47,49)Ti wide-line experiments, has been used for the structural characterization of titanium substituted ultra-stable zeolite Y (Ti-USY). 27Al MAS experiments show the presence of aluminum in four (Al(IV)), five (Al(V)), and six (Al(VI)) coordination, whereas the multiplicity within Al(IV) and Al(VI) is revealed by 27Al 3Q-MAS experiments. Two different tetrahedral and octahedral Al environments are resolved and their isotropic chemical shifts (delta(CS)) and second-order quadrupole interaction parameters (P(Q)) have been determined by a graphical analysis of the 3Q-MAS spectra. The emergence of signal with higher intensity at -101 ppm in the 29Si MAS spectrum of Ti-USY samples indicates the possible occurrence of Q4(3Si,1Ti) type silicon environments due to titanium substitution in the faujasite framework. High-field (11.74T) operation, using a probehead specially designed to handle a large sample volume, has enabled the acquisition of 47,49Ti static spectra and identification of the titanium environment in the zeolite. The chemical shielding and electric field gradient tensors for the titanium environment in the zeolite have been determined by a computer simulation of the quadrupolar broadened static 47,49Ti NMR spectra.     

不同核函数支持向量机和可见-近红外光谱的多种植被叶片生化组分估算

氮、磷、钾元素是植物有机质的重要生化组分,准确估算其含量对监测管理植被的新陈代谢和健康状况具有重要意义。可见-近红外光谱结合多种建模方法已被用于植被生化参数的监测,其中支持向量机回归方法被证明能够较好拟合反射光谱和植被生化参数之间的非线性关系,而选取适当的核函数是其成功的关键。以宜兴地区水稻、玉米、芝麻、大豆、茶叶、草地、乔木和灌木等八种植被叶片样本为研究对象,分析比较基于径向基核函数、多项式核函数和S形核函数的支持向量回归模型估算叶片氮、磷、钾元素含量的能力。利用一阶微分变换、标准正态变量变换和反对数变换对叶片可见-近红外光谱进行预处理,运用bootstrapping法生成1 000组校正集和验证集,分别建立基于三种核函数的支持向量回归估算模型,以决定系数（R2）和相对分析误差（RPD）的均值作为评价指标。结果显示,结合一阶微分和反对数变换光谱,采用径向基核函数模型对氮、钾元素估算精度最高（氮：平均R2=0.64,平均RPD=1.67;钾：平均R2=0.56,平均RPD=1.48）,结合一阶微分变换光谱,采用径向基核函数模型对磷元素估算精度最高（磷：平均R2=0.68,平均RPD=1.73）。研究表明,结合不同预处理的可见-近红外光谱,基于径向基核函数的支持向量回归模型具有较好的估算多种植被叶片生化组分含量的潜力。     

The effect of thermal annealing on defect structure and thermoluminescence in LiF:Mg,Cu,P

We have studied the behavior of the glow peaks in the thermoluminescence of LiF:Mg,Cu,P as a function of pre-irradiation annealing temperature in the range 80 to 170°C, and as a function of cooling rate following the 240°C/10 min anneal used for standardization in dosimetric procedures. The intensities of the major peaks in LiF:Mg,Cu,P (as well as in LiF:Mg,Ti—the current industrial standard) seem to be determined by the dynamics of clustering of (Mg²⁺−Li_vac) dipoles to dimers, trimers and a precipitate phase. The intensities of the thermal interactions, however, seem to be somewhat reduced in LiF:Mg,Cu,P compared to LiF:Mg,Ti. In addition, it seems plausible that phosphorus takes the role of titanium in LiF:Mg,Cu,P in the formation of a trapping center/recombination center spatially correlated complex.     

Mechanisms of anode power deposition in a low pressure free burningarc

Anode power deposition is a dominant power loss mechanism for arcjets and magnetoplasmadynamic (MPD) thrusters. In this study, a free burning arc experiment was operated at pressures and current densities similar to those in arcjets and MPD thrusters in an attempt to identify the physics controlling this loss mechanism. Use of a free burning arc allowed for the isolation of independent variables controlling anode power deposition and provided a convenient and flexible way to cover a broad range of currents, anode surface pressures, and applied magnetic field strengths and orientations using an argon gas. Test results showed that anode power deposition decreased with increasing anode surface pressure up to 6.7 Pa and then became insensitive to pressure. Anode power increased with increasing arc current, while the electron number density near the anode surface increased linearly. Anode power also increased with increasing applied magnetic field strength due to an increasing anode fall voltage. Applied magnetic field orientation had an effect only at high currents and low anode surface pressures, where anode power decreased when applied-field lines intercepted the anode surface. The results demonstrated that anode power deposition was dominated by the kinetic energy of the current-carrying electrons acquired over the anode fall region. Furthermore, the results showed that anode power deposition can be reduced by operating at increased anode pressures, reduced arc currents, anode current densities, and applied magnetic field strengths, and with magnetic field lines intercepting the anode     

复混肥中磷元素的激光诱导击穿光谱多元线性定量分析

复混肥成分的快速、原位检测对化肥的生产过程、产品质量控制具有重要的意义。在化肥企业生产中,实验室进行分析,检测时间长,无法实现线上检测。与复混肥成分现有检测方法相比,激光诱导击穿光谱(LIBS)检测时间只需几分钟、一次测量可完成复混肥成分检测、几乎无需样品预处理,将该技术用于复混肥成分快速、现场检测非常合适。搭建LIBS系统, 激光器(100 mJ, 1 064 nm, 1 Hz)输出的激光束经45°反射镜由水平转为垂直方向,经焦距为40 mm的透镜聚焦至旋转台上的复混肥样品表面,产生激光等离子体。激光器的调Q信号控制光纤光谱仪(Avantes, 195～500 nm)采集信号,设置光谱延迟时间为1.28 μs,采集时间为1.05 ms,最终获取复混肥样品LIBS光谱。20个复混肥样品由安徽徽隆集团提供,磷元素的参考值由企业采用国家标准方法测量。将复混肥样品粉碎过筛取3 g,采用压片机在8 MPa下压制成形。实验中,使用小型风扇吹扫复混肥样品表面,形成稳定气流,每个样品重复测量10次,每次测量平均20个脉冲,以减小样品不均匀性。其中,15个样品用于定标回归模型的建立,五个样品用于检验定标模型的适用性。复混肥是一种成分复杂的混合物,其中氮、磷、钾均以化合物存在。传统的LIBS定量方法是基于待测元素单条谱线强度,未考虑其他元素影响,降低了定量结果的准确性。将LIBS技术和多元线性回归法结合用于分析复混肥中磷元素浓度。选取磷元素的三条特征谱线即213.6,214.9和215.4 nm。磷矿中硅元素含量基本不变,且硅元素在磷的谱线附近存在多条谱线,如212.4,220.8,221.1和221.7 nm。分别采用一元、二元、三元和四元线性回归法建立校准曲线。结果表明,采用P Ⅰ: 214.9 nm谱线强度作自变量建立一元线性回归,LIBS预测值与参考浓度的相关系数仅为0.083,无法满足磷元素的定量分析要求。当采用P Ⅰ: 214.9 nm谱线强度和三条特征谱线之和(P Ⅰ: 213.6, 214.9和215.4 nm)作自变量建立二元线性回归拟合时,相关系数提高到0.856,平均绝对误差由1.32%减小到0.16%。在二元线性回归中引入Si Ⅰ: 212.4 nm谱线强度,建立三元线性回归,相关系数为0.869。为进一步提高磷元素浓度测量的准确性,建立四元线性回归方程,将Si Ⅰ: 212.4,220.8,221.1和221.7 nm谱线强度之和作为自变量加入三元线性回归,相关系数提高到0.980,且15个定标样品的相对误差范围为0.06%～1.31%,而验证样品为0.13%～1.26%,这说明采用四元线性回归定标法可提高复混肥中磷元素浓度测量的准确性。     

用不同的Mo靶溅射功率制备Mo/Si多层膜

 用磁控溅射法制备了周期厚度和周期数均相同的Mo/Si多层膜，用原子力显微镜和小角X射线衍射分别研究了Mo靶溅射功率不相同时，Mo/Si多层膜表面形貌和晶相的变化。随后在国家同步辐射实验室测量了Mo/Si多层膜的软X射线反射率。研究发现，随着Mo靶溅射功率的增大，Mo/Si多层膜的表面粗糙度增加，Mo的特征X射线衍射峰也增强，Mo/Si多层膜的软X射线峰值反射率先增大后减小。     

The impact of ozone on the (15)n incorporation and nitrogen assimilation of wheat and maize

Abstract Young wheat (C3) and maize (C4) plants were exposed to near-ambient concentrations of ozone in open-top chambers in order to investigate the possible effects of ozone on nitrogen metabolism. Nitrogen was supplied to the plants by adding (15)N-labelled tracer substances via the soil substrate. Enzyme activities (NADH nitrate reductase, nitrite reductase, glutamine synthetase and NADH glutamate dehydrogenase) and the incorporation of (15)N were determined. The findings show that nitrogen metabolism was affected by O(3), however, there were distinct differences between the two species. In plants treated with O(3), NADH nitrate reductase activity in maize leaves was reduced, while NR activity in wheat leaves only slightly declined. Only minor changes were observed with respect to the activities of nitrite reductase, glutamine synthetase and NADH glutamate dehydrogenase. Feeding experiments using (15)NO(3) (-) showed that the incorporation of nitrate nitrogen in wheat plants exposed to ozone remains virtually unchanged, whereas in maize plants reduced incorporation rates were observed for nitrate nitrogen. The incorporation of ammonium nitrogen was distinctly increased in wheat and maize by the impact of ozone. When investigating pigment contents, reduced levels of chlorophyll a and b and carotenoids were observed, whereas the pigment content of wheat leaves remained unchanged. These results indicate that young maize plants are more susceptible than wheat plants to short-term ozone exposure.