光程对黄酒金属元素近红外透射光谱分析精度的影响

应用近红外透射光谱分析技术开展了不同光程对黄酒中金属元素(钾、钙、镁、锌和铁)分析结果影响的研究。实验采用傅里叶变换近红外光谱仪(800～2 500 nm)及不同光程(1,2,5,10 mm),石英比色皿以空气为参比进行了光谱采集,并采用偏最小二乘法进行了数据分析。金属含量采用原子吸收光谱分析法测定。分析结果表明, 5 mm光程的分析结果最优,对于钾、钙、镁、锌和铁的相关系数(r2)分别为0.93,0.85,0.93,0.72,0.66,交互验证误差(RMSECV)分别为26.5,35.6,4.63,0.26,0.64 mg·L-1;而10 mm光程的光谱分析结果最差,其r2分别为0.61,0.65,0.63,0.09,0.25。通过实验说明, 光程对近红外透射光谱分析的影响,不是光程越长或越短越好,需要通过测试及对比分析确定。     

Energy expression of the chemical bond between atoms in metal oxides

The chemical bond between atoms in metal oxides is expressed in an energy scale. Total energy is partitioned into the atomic energy densities of constituent elements in the metal oxide, using energy density analysis. The atomization energies, ΔE_M for metal atom and ΔE_O for O atom, are then evaluated by subtracting the atomic energy densities from the energy of the isolated neutral atom, M and O, respectively. In this study, a ΔE_O vs. ΔE_M diagram called atomization energy diagram is first proposed and used for the understanding of the nature of chemical bond in various metal oxides. Both ΔE_M and ΔE_O values reflect the average structure as well as the local structure. For example their values vary depending on the vertex, edge or face sharing of MO₆ octahedron, and also change with the overall density of binary metal oxides. For perovskite-type oxides it is shown that the ΔE_O value tends to increase by the phase transition from cubic to tetragonal phase, regardless of the tilting-type or the 〈1 0 0〉 displacement-type transition. The bond formation in spinel-type oxides is also understood with the aid of the atomization energies. The present approach based on the atomization energy concept will provide us a new clue to the design of metal oxides.     

农用地土壤As元素与叶片光谱特征关系研究

重金属污染是土壤环境污染中亟待解决的问题之一,重金属通过土壤向植物富集,危及人体健康,对生态环境产生巨大隐患。传统的土壤污染监测以化学方法为主,不仅费时费力且监测范围有限,而基于植被高光谱技术的土壤重金属监测方法能够快速准确地获取土壤重金属含量,突破植被屏障,提高土壤重金属监测效率。近年来,国内外许多学者致力于使用盆栽实验定量研究土壤污染物对植物光谱特征影响,而野外环境下的实验研究相对缺少,因此建立合适准确的野外土壤重金属预测模型具有重要意义,为改善耕地土壤质量提供参考。以北京市优势经济果树桃树为研究对象,在研究区均匀设置了50个采样点,利用FieldSpec 4便携式地物波谱仪测量桃树叶片光谱数据,同时采集土壤样本带回实验室检测分析获得土壤重金属含量数据。通过分析不同污染下桃树叶片在重金属胁迫下的叶片光谱特征,计算不同土壤重金属与叶片光谱之间的相关关系,确定土壤As元素与光谱反射率相关性更大,因此选择土壤As元素计算其与不同植被指数之间的相关系数,并用合适的植被指数构建土壤As元素预测模型。结果表明：污染区桃叶光谱反射率总体上比背景区的光谱反射率更高,其中760~1 300 nm波长范围内对土壤重金属更加敏感,土壤重金属对叶片红、蓝、黄边位置干扰不明显,对红、蓝、黄边斜率敏感,且均呈正向相关性。光谱反射率与土壤Cr,Cu和Hg元素相关性较弱,与As,Pb和Cd元素在某些波段范围内达到0.1级显著相关,且总体相关曲线趋势相同,相关性大小依次排序为As>Pb>Cd。以相关性更强的土壤As元素与植被指数进行相关分析表明,土壤As元素与PRI1和PRI3均显著相关。使用SPSS数据分析软件以PRI1和PRI3为自变量,土壤As元素为因变量分别进行回归分析,检测结果发现,PRI3的指数预测模型(y=e43.644x-39.386, R2=0.937, RMSE=0.161)效果最好且具有更好的稳定性。     

Flame synthesis of 1-D complex metal oxide nanomaterials

One dimensional (1-D) complex metal oxide nanomaterials, such as ternary oxides, doped oxides, and hierarchical structures containing several oxides, not only benefit from large aspect ratios, but also offer exciting opportunities to design materials with desired properties by tuning their chemical compositions and tailoring their sizes and morphologies at the nanometer scale. Flame synthesis is an attractive method to grow 1-D complex metal oxide nanostructures because of its high temperature, scalability, low-cost and rapid growth rate. Here, we present three new combined flame synthesis methods: (1) simultaneous vapor–vapor growth, (2) simultaneous solid–vapor growth, and (3) sequential solid–vapor growth, to grow 1-D complex metal oxide nanostructures with well-defined compositions and morphologies. These three methods combine the previously reported flame vapor deposition and solid diffusion growth methods that were separately used to grow 1-D simple binary metal oxide nanostructures, and significantly advance the capabilities of existing flame synthesis methods for the growth of 1-D nanomaterials. The first method, simultaneous vapor–vapor growth, combines the flame vapor deposition growth of two different metal oxides by oxidizing and evaporating two different metal sources. With this we have successfully grown W-doped MoO₃ nanoplates and nanoflowers. In the second method, simultaneous solid–vapor growth, one precursor is again provided by oxidizing and evaporating metal oxide from a metal, while the other precursor diffuses out from a different growth substrate. With this we have successfully grown ternary Cu₃Mo₂O₉ nanowires. The third method, sequential solid–vapor growth, essentially uses the 1-D nanostructures firstly grown by solid diffusion as the substrates for subsequent flame vapor deposition. With this we have successfully grown hierarchical CuO/MoO₃ core/shell nanowires and MoO₃-branched CuO nanowires. We believe that these three new combined flame synthesis methods will provide a general platform for the synthesis of 1-D complex metal oxide nanostructures with tailored properties.     

溶液阴极辉光放电光谱信号的内标法定量分析研究

溶液阴极辉光放电-原子发射光谱是一种新颖的快速、高效、实时在线的元素分析方法,它可用于水体金属元素的检测。为提高其测量精确度和稳定性,将内标法应用于溶液阴极辉光放电-原子发射光谱技术。对K元素建立了标准定标曲线和以H_β为内标元素的定标曲线,内标法测得样品的相对误差和相对标准偏差分别为1.11%,2.14%,精确度和稳定性较之标准曲线法有一定的提高。实验考察了元素谱线强度在同一时段的波动情况,发现元素K和H_β的谱线强度变化趋势稍有不同,而同主族元素K和Rb,Ca和Mg的谱线强度有相同的变化趋势,提出选择与待测元素同主族且谱线强度变化趋势较为一致的元素作为内标元素能更大化校正实验波动的观点。同时探讨了K以Rb为内标元素、Ca以Mg为内标元素以及Mg以Ca为内标元素时的内标法测量的精确度和稳定性,得其相对误差分别为0.49%,0.02%和0.30%,相对标准偏差分别为1.11%,1.13%和0.87%,与标准曲线法和以H_β为内标元素的内标法相比效果更佳。测得自来水样品中Ca元素以Mg为内标的相对误差和相对标准偏差为0.58%,1.03%,Mg元素以Ca为内标的相对误差和相对标准偏差为1.57%和1.10%。研究结果表明,将溶液阴极辉光放电-原子发射光谱技术应用于水体金属元素检测时,内标法可以有效校正实验波动的影响,提高测量的精确度和稳定性。     

On the use of scanning tunneling microscopy to investigate surface structure and interface formation in transition metal oxides: SrTiO3 and TiO2

Since transition metal oxides are wide bandgap, low conductivity materials compared to conventional semiconductors, surface analysis by scanning tunneling microscopy (STM) is expected to be problematic. This paper considers the factors that affect atomic scale imaging of transition metal oxides and demonstrates how STM can be exploited to examine the geometric and electronic structures of SrTiO₃ and TiO₂ surfaces, their variations with thermochemical history, and the mechanisms of metal/oxide interface formation. The development of periodic atomic scale surface structure with variations in surface compositions are documented for both oxides. Further, the interactions of these surfaces with metal are examined by characterizing the morphologies that develop upon deposition of Cu on SrTiO₃ and Al on TiO₂.     

EBSD-XPS法分析磷石膏中杂质物相

磷石膏是湿法磷酸过程形成的固体副产物。磷石膏中含有磷、氟、硅等有害杂质组分,极大影响磷石膏制品的质量和性能,巨量磷石膏堆存严重威胁生态环境和生命安全。确定磷石膏中杂质物相的赋存状态,为磷石膏除杂净化和综合利用提供理论指导,非常重要。以低温干燥后的磷石膏为研究对象,利用X射线荧光光谱（XRF）分析确定磷石膏中杂质元素的组成,结果表明,磷石膏中的杂质元素含量较高的有P,Si,F和Al,含量较低的有Ba,Fe和Mg等。因二水硫酸钙物相强峰对杂质物相峰有较强遮蔽作用,X射线衍射光谱（XRD）分析不能确定磷石膏杂质的物相。利用扫描电子显微镜对磷石膏进行电子背散射衍射（EBSD）分析,根据被检样品衬度的区别探明磷石膏的杂质物相,利用X射线能谱分析（EDS）成分确定杂质物相组成;利用X射线光电子能谱（XPS）对硫酸钙晶体表面以及混合杂质物相作进一步分析。EBSD分析结果表明,磷石膏中杂质物相主要包括二氧化硅、氟硅酸钠、氟硅酸钾、氟磷酸钙、氟化钙、硫酸钡、硫化铁、三氧化二铝等,此外还有硅、铝、磷、氟等杂质混合组成的复盐物相,其中二氧化硅、硫酸钡、硫化铁、氟磷酸钙和三氧化二铝为独立赋存物相,氟硅酸钠和氟硅酸钾的物相则混合分布在硫酸钙晶体之间,氟化钙杂质与硅、铝、磷、氟杂质复盐物相结合赋存。XPS分析结果表明,磷石膏中还存在硅酸钙、氟化铝、氟化镁、硫酸铝、磷酸铝、磷酸钙、磷酸氢钙和磷酸二氢钙等物相,其中磷酸钙、磷酸氢钙、磷酸二氢钙和氟磷酸钙四种物相的特征峰位分布极为接近。采用EBSD-XPS组合分析方法,不仅确定了磷石膏中杂质的物相,还阐明了杂质物相与硫酸钙晶体之间的构效关系。该研究为磷石膏杂质物相分析提供新途径,为磷石膏除杂净化及其综合利用提供坚实的理论依据。     

Bismuth silicate glass containing heavy metal oxide as a promising radiation shielding material

Optical and FTIR spectroscopic measurements and electron paramagnetic resonance (EPR) properties have been utilized to investigate and characterize the given compositions of binary bismuth silicate glasses. In this work, it is aimed to study the possibility of using the prepared bismuth silicate glasses as a good shielding material for γ-rays in which adding bismuth oxide to silicate glasses causes distinguish increase in its density by an order of magnitude ranging from one to two more than mono divalent oxides. The good thermal stability and high density of the bismuth-based silicate glass encourage many studies to be undertaken to understand its radiation shielding efficiency. For this purpose a glass containing 20% bismuth oxide and 80% SiO₂ was prepared using the melting–annealing technique. In addition the effects of adding some alkali heavy metal oxides to this glass, such as PbO, BaO or SrO, were also studied. EPR measurements show that the prepared glasses have good stability when exposed to γ-irradiation. The changes in the FTIR spectra due to the presence of metal oxides were referred to the different housing positions and physical properties of the respective divalent Sr²⁺, Ba²⁺ and Pb²⁺ ions. Calculations of optical band gap energies were presented for some selected glasses from the UV data to support the probability of using these glasses as a gamma radiation shielding material. The results showed stability of both optical and magnetic spectra of the studied glasses toward gamma irradiation, which validates their irradiation shielding behavior and suitability as the radiation shielding candidate materials.     

In-Situ Monitoring of Chromium Uptake in Different Parts of the Wheat Seedling (Triticum aestivum) using Laser-Induced Breakdown Spectroscopy

The present work is a methodological study to investigate the effect of chromium (VI) stress on wheat seedlings. Point detection capability of laser-induced breakdown spectroscopy (LIBS) was utilized for the monitoring of in-situ chromium uptake in wheat (Triticum aestivum) seedlings. Chromium accumulation and its effects on other elements in wheat seedling were investigated by comparing the intensities of spectral lines of chromium and other minerals present in the LIBS spectra. In-situ LIBS spectra of the different parts of the wheat seedlings were recorded by directly focusing the laser beam on the surface of root, stem, and leaf of the seedlings grown with and without chromium-containing solutions. The spectra obtained from the different parts (root, stem, and leaf) of the wheat plant were analyzed to determine the distribution pattern/accumulation of chromium. Effect of the chromium uptake on the distribution pattern of other elements like calcium (Ca), magnesium (Mg), sodium (Na), and potassium (K) was also investigated. It was observed that chromium concentrations in plant organs decreased in the following order: roots > leaves > stems.     

The role of substitution-induced micro-structural defects on the redox behavior and catalytic activity of LaxTh1−x(VO3−δ)4 mixed oxide catalysts

The catalytic properties and reduction behavior of mixed metal oxides with nominal compositions of La_xTh_1−x(VO_3−δ)₄, where 0.0 ≤ x ≤ 1.0, have been investigated as a function of the value of x. These compositions were synthesized by ceramic route and characterized using powder X-ray diffraction, differential thermal analysis, and temperature-programmed reduction/oxidation/desorption techniques. The substituted samples were comprised of two distinct phases, one corresponding to tetragonal thorium metavanadate with partial substitution at A-sites, i.e. La_xTh_1−x(VO_3−δ)₄, and the other a new phase identified as LaV₄O_11+δ. Both these phases exhibited considerable oxygen non-stoichiometry, depending upon the extent of substitution. Nevertheless, no significant change was observed in their respective crystal symmetry. Further, the substituted samples showed more reproducible redox behavior and also an improved catalytic activity for CO oxidation reaction. A definite correlation is found to exist between the micro-structural defects generated in the above-mentioned two phases because of the oxygen ion vacancies, resultant enhancement in thermal diffusitivity of lattice oxygen, and finally the catalytic activity of the substituted mixed oxides. It is envisaged that a kind of synergism between the micro-structural defects existing in the two inter-grown phases generated simultaneously during the synthesis may control the catalytic properties of composite metal oxide systems.     

An attempt to analyze the bark disease in Havea brasiliensis using X‐ray absorption near‐edge spectroscopy

The X‐ray absorption near‐edge spectroscopy (XANES) technique has been used to determine the chemical change of elements induced by bark diseases in Havea brasiliensis (rubber latex tree). The results show the good sensitivity of in situ XANES for characterizing the chemical structure of phosphorus, sulfur, potassium and calcium in healthy and diseased Havea brasiliensis. Important information for understanding the bark disease involved in the sulfur metabolism of plants was also obtained from XANES.     

Polymorphism in Cu-substituted GaV4S8: structural and electronic properties

The hexagonal and cubic phases of Ga_1−xCu_xV₄S₈ are obtained by different methods of preparation. The reaction of elements above 900 °C gives hexagonal phases for large range of x=0.02-0.5. These are metallic and show enhanced paramagnetism. The reduction of oxides by H₂S at a lower temperature of 700 °C gives non-stoichiomertic compositions of cubic-V₄ cluster compound GaV₄S₈. The solubility of Cu-atoms in cubic phase is less than 10% and above x=0.2 the samples contain a mixture of phases, Cu_xVS₂, Ga_xVS₂ and CuGaS₂. The cubic phases are insulating and show Mott's Variable Range Hopping conduction. The non-stoichiomerty and the Cu-substitution reduce the resistivity and thermopower. For x=0.15 and 0.20, the additional peaks are observed in X-ray patterns. These compositions showed a sharp metal to insulator transition on cooling below 180 K. The transitional behaviour is very similar to that previously reported intercalated VS₂ compound Al_xVS₂. The transport and magnetic properties of these phases are discussed in terms of the clustering interactions among V-atoms and the localisation of carriers on the metallic clusters frequently found in V-chalcogenides.     

丹参等11种中药金属元素含量测定及聚类分析研究

采用原子吸收分光光度法检测了丹参、枸杞子、党参、绞股蓝、冬虫夏草、黄芪、肉桂、细辛、龙胆草、山茱萸、杜仲共11种中药中钾、钙、镁、铁、锰、铜、锌和铬元素的含量, 运用模糊分类方法研究药物金属元素与药物疗效的相关性。结果显示,相关系数r=0.50时,有7种药物聚类相似;相关系数r=0.65时,有3种药物聚类相似;r=0.75时,有2种药物聚类相似。药物中金属元素含量丰富,相关系数较大的药物,其药物疗效相似性较大,揭示中药中微量元素与药物疗效密切相关。该研究为中药的质量评价提供一种新的方法,为研制新型的药物提供了有用的科学数据。     

Dye-sensitized solar cells based on different nano-oxides on plastic PET substrate

Polyethylene-terephthalate (PET) foils and glass slides coated with thin conductive layers were used as substrates for TiO2 or ZnO based photoactive electrodes of dye-sensitized solar cells (DSSC) with organo-metallic Ru-dye, standard iodine electrolyte and Pt coated FTO/glass counterelectrode (CE). Different compositions of nanoparticle oxides in forms of alcohol pastes as well as the CE paste were applied onto the substrates by screen printing or by doctor blade techniques. Photocurrents and I–V loading characteristics were measured depending on the solar cell structure and preparation, including the oxide composition, electrode conductivity and the dye type. The influence of thin TiO2 blocking layer prepared by sol–gel technique is also discussed.     

Determination of potassium, calcium and chlorine in some vegetables by EDXRF

Total concentration of potassium, calcium and chlorine was determined in the presence of each other and irrespective of the nature of their compounds, in the leaves of Urticae dioico L. and Spinacia oleracea L. (spinach) plants by EDXRF. The enhancement of potassium K X-rays due to calcium K X-rays and enhancement of chlorine K X-rays due to potassium and calcium K X-rays present in the samples were avoided by selective secondary excitation method of the samples. Our results were compared with other experimental results.     

Morphological, structural and adsorption features of oxide composites with silica and titania matrices

Morphological, structural, electronic, and adsorption characteristics of complex oxides such as fumed silica/alumina and silica/titania, fumed silica with deposited oxides of Mg, Ti, Mn, Ni, Cu, Zn and Zr, silica gel with grafted ZrO₂, sol-gel titania doped by 3d-metals (Cr, Fe, Mn, V) were compared using adsorption, TEM, AFM, XRD, XPS, Mössbauer and Raman spectroscopy data. It was shown that surface, volume, and phase compositions of oxides, particle size distributions (5 nm-3 μm), specific surface area (S_BET ∼ 50-500 m²/g), and porosity (V_P ∼ 0.1-2 cm³/g) affected by synthesis technique and subsequent treatment determine electronic structure (bandgap, valence band and core levels structure) of the materials, adsorption of molecules and metal ions as well as other characteristics.     

用微波消解法-FAAS测定民族药腺毛菊苣根中八种金属元素的含量

腺毛菊苣是新疆维吾尔族传统习用药材,但其药物中有效微量、常量元素成分尚未进行过分析研究。试验采用HNO₃作为消解液,利用微波消解的方法处理样品,原子吸收分光光度法测定维吾尔药材菊苣根中钾(K)、镍(Ni)、钙(Ca)、镁(Mg)、铁(Fe)、锰(Mn)、铜(Cu)和锌(Zn)八种微量、常量元素的含量,精密度和回收率较好,回收率控制在92.25%～110.5%之间,相对标准偏差RSD≤3.88%。结果显示新疆菊苣中Mg, Ca, Fe, K等人体所需的必须微量元素含量十分丰富,特别是Mg和Ca含量较高,分别达到278.17和65.84 mg·g-1。其他元素中Mg和Zn含量中等;而Cu含量则较低,仅有0.016 5 mg·g-1,Ni含量为0.004 38 mg·g-1,实验结果为维吾尔医利用菊苣治疗心脑血管、骨质疏松症等疾病从微量元素的角度提供了有用的数据。     

Electron spin resonance study of the local properties of the microscopic phase separation in La<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Ca<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>MnO<Subscript>3</Subscript> single-crystal films

Electron spin resonance is studied in films of La_1?x Ca _x MnO₃ manganites with compositions in the vicinity of the calcium content x = 0.5, in which the phase separation is most clearly pronounced. It is found that the La_0.5Ca_0.5MnO₃ manganite undergoes different types of phase separation: (i) at temperatures above the Curie point, ferromagnetic regions exist in the paramagnetic phase; and (ii) at temperatures below the Néel point, antiferromagnetic microregions coexist with ferromagnetic microregions. Two types of ferromagnetic domains with different magnetization orientations are revealed In the temperature range between the Curie and Néel points.     

汉中元胡中8种金属元素含量的测定

采用微波消解-火焰原子吸收光谱法对汉中元胡中钾、钙、钠、镁、锌、锰、铜、铁8种金属元素的含量进行测试,测得结果分别为K（2033.97mg/kg）、Ca（600.87mg/kg）、Na（1395.55 mg/kg）、Mg（494.88mg/kg）、Zn（220.36mg/kg）、Mn（107.75mg/kg）、Cu（39.68mg/kg）、Fe（2462.79mg/kg）。相对标准偏差的范围为0.0356%—4.4288%,回收率的范围为96.8%—101.2%。微波消解-火焰原子吸收光谱法是一种简便而又灵敏的测定中草药中微量元素的方法。     

An ESCA investigation of some dithiooxalato complexes

A series of dithiooxalato complex ions have been investigated as their tetraphenyl-phosphonium and potassium salts. Core-electron binding energies (E_b) of S, C, and O were determined, as well as those of the metals. From the first-mentioned data, effective charge values (q) were estimated for the atoms of the ligands. For this purpose linear relations (E_b = k · q + E_bO) were used that had been previously derived within a scheme using C ls (phenyl) as the internal standard. From the data thus obtained the effective charge on the metal atoms could be estimated. The data is used to test if analogous linear relations also hold for the heavy elements; for example, we have found E_b(Pt) = 3.17 · q_pt + 71.1 eV.