粉末压片制样-X射线荧光光谱(XRF)法测定钛铁矿中TFe、TiO_2、SiO_2、Al_2O_3、CaO、MgO的含量

以粉末压片法制样,采用X射线荧光光谱(XRF)法测定钛铁矿中TFe、TiO_2、SiO_2、Al_2O_3、CaO、MgO的含量。对样品的矿物效应、样品粒度、分析谱线等条件进行优化。利用不同产地的质控样品制作工作曲线,验证矿物效应影响不大;通过样品粒度小于74μm,很好地解决了颗粒粒度效应的影响。精密度实验表明,待测组分的相对标准偏差均低于3.6%(RSD,n=10),能满足钛铁矿中各组分的测定要求。     

X射线荧光光谱法测定农田底泥中8种元素

建立X射线荧光光谱法测定农田底泥样品中砷、铬、铜、锰、镍、铅、锌、铁8种元素含量的分析方法.以塑料环粉末压片法制样,选用50种土壤、水系沉积物标准物质拟合校准曲线,探讨各元素的测定条件.当待测样品与建立校准曲线的标准样品粒径均小于75μm时,能够有效减少矿物效应和粒度效应的影响,从而提高检测准确度;各元素在各自的含量范...     

X射线荧光光谱法测定垃圾焚烧炉渣中主要成分

使用X射线荧光光谱仪,采用粉末直接压片制样,以研磨的方式克服粉末样品的粒度效应,理论α系数法校正基体效应,建立了垃圾焚烧炉渣样品中SiO2、Fe2O3、MgO、Al2O3、CaO、K2O、TiO2、P2O5八组分的分析方法.用标准化法进行强度漂移校正,用内控标样制做校准曲线,测定结果的精密度和准确度可以满足日常分析要求.     

熔融制样-X射线荧光光谱法测定钨精矿中主次组分

本文采用熔融制样-X射线荧光光谱法测定钨精矿中的主次组分(WO_3、Fe_2O_3、MnO_2、CaO、SiO_2)。采用熔融制样,消除样品的颗粒效应与矿物效应;以D.Jongh数学模式对谱线干扰和基体效应进行校正,得到满意的工作曲线。结果表明方法重复性和再现性良好,相对标准偏差为0.154%~1.900%,样品的测定值与认定值基本一致,回收率为92.50%~106.00%。该方法能满足日常分析工作的要求。     

X射线荧光光谱法测定平炉渣中主成分

使用3080E3型X射线荧光光谱仪,采用粉末直接压片制样,研磨克服粉末样品的粒度效应,理论d系数法校正基体效应的方法,建立了平炉渣样品中TFe、SiO2、MgO、Al2O3、CaO、MnO、TiO2、P2O5组分的快速测定方法。研究了制样条件,用内控标样作标准曲线,分析结果的相对标准偏差为0．23％～3．17％,满足日常分析的要求。     

土壤对外源钍的吸附行为表征

外源钍对土壤的污染风险和程度取决于钍在土壤中的吸附行为. 以包头稀土工业区土壤样品和土壤环境矿物组分为研究对象, 通过静态吸附方法研究外源钍在土壤样品和环境矿物组分(高岭土、蒙脱土、碳酸钙、水合氧化铁/锰和腐殖酸)上的吸附, 并对吸附行为进行了表征. 结果表明, 土壤样品对外源钍有很强的吸附能力, 对加入的外源钍(10^-4 mol/L)吸附率在97%以上; 土壤环境矿物组分对加入的外源钍(1 g/L)吸附率在28%～46%之间. 通过扫描电镜-能谱(SEM-EDS)分析可知, 外源钍进入土壤后与矿物组分发生相互作用, 可能形成了稳定化钙质钍碳酸盐和钍磷酸盐; 傅里叶变换红外光谱(FTIR)分析表明, 钍是与土壤环境矿物组分上的活性吸附位点发生相互作用而吸附并保持在土壤中, 是物理吸附和化学吸附共同作用的过程; X射线衍射分析(XRD)表明, 土壤在吸附钍前后, 其矿物组分基本相同, 而矿物晶体相态发生明显变化. 由于不同土壤矿物组分对钍的吸附方式不同, 导致吸附的钍以不同形态存在于土壤中.     

包覆效应与压片法X射线荧光光谱分析

提出了在压片法X射线荧光光谱分析中存在包覆效应。用粉末压片X射线荧光光谱法测定刚玉镁砂浇注料的成分时,氧化镁的测定结果偏高,氧化铝的测定结果偏低,且偏低量、偏高量相近。用玛瑙研钵将样品不断研磨至更小的粒径时,上述现象没有明显的改变,表明此现象不属于粒度效应。用分别研磨至0.096mm的刚玉和镁砂粉末,按氧化铝和氧化镁含量与浇注料相近的比例混合均匀后,分别用压片法和熔片法测定,发现两种制片方法测定结果相近,表明上述现象也不是矿物效应。因此,提出了包覆效应的概念。用已有的报道证实了包覆效应,并指出了粒度效应、矿物效应和包覆效应的区别。     

三组分(NiO、La2O3、SiO2)负载型加氢催化剂中La2O3的作用

用X射线衍射分析、FT-IR、小角X光散射等方法研究了浸渍法制备的NiO/SiO_2和NiO/(La_2O_3+SiO_2)样品中组分之间的相互作用。La_2O_3在SiO_2上可形成近乎密置单层的分散。在负载了La_2O_3的SiO_2上,NiO的分散程度比在SiO_2上有明显提高,也更容易被还原,而且还原后所得金属镍粒子的平均粒度降低,小粒子所占百分比提高。这些结果表明,NiO/(La_2O_3+SiO_2)比NiO/SiO_2样品具有更高的加氢还原硝基普鲁卡因为胺基普鲁卡因的活性,与Ni/(La_2O_3+SiO_2)比Ni/SiO_2活性高的情形相一致。     

中国海大陆架沉积物超细标准物质系列研制

5个中国海大陆架沉积物标准物质的原样分别取自东海和南海,样品风干后,先经球磨制备成200目的均匀粉体,再用气流磨进一步加工成超细粒度的均匀样品.采用激光粒度仪检测了样品的粒度分布,5个样品的平均粒度均小于4 μm(约800目).采用高精度的XRF检验了样品的均匀性并以高灵敏度的ICP-AES、ICP-MS相配合确定了其最小取样量(5 mg).有12个实验室参加了合作定值研究,定值组分均为60个,其中MSCS-1,2分别有50和51个组分定为标准值,MSCS-3,4,5有52个组分定为标准值.全组分百分总和分别为99.9%, 99.9%, 100.4%, 100.1%和99.7%.     

X射线荧光光谱法同时测定富锰渣中主次组分

应用X射线荧光光谱法测定富锰渣中Mn,Fe,SiO2,Al2O3,TiO2,CaO,MgO,Na2O,K2O,S,P,CuO,ZnO,NiO,BaO15种主次组分。使用混合熔剂在1050℃熔融制备样片,消除了试样的粒度效应和矿物效应,同时也解决了S元素在制样过程中容易挥发的难题。确定仪器测量的最佳参数,研究了熔样的条件、校正模式。各元素的相对标准偏差(RSD,n=10)≤10%,测定结果与化学法测定值相符。方法快速、准确、方便快捷,具有良好的精密度和准确性,可用于富锰渣产品的品质评价和成分分析。     

Nouvelle Synthese Des 2-Thioxoethylphosphonates, 2- mercaptovinylphosphonates, 2-Phosphoryl-3-thioxopropanoates, 2-Thiomethylvinylphosphonates, 2-Thioethoxycarbonylmethylvinylphosphonates

The cyanomethylphosphonates 1 and the ethyl phosphoacetates 2 were reacted with some fluorophenylisothiocyanates to give the 2-thioxoethylphosphonates 3 in tautomeric equilibrium with the corresponding 2-mercaptovinylphosphonates 3 ′ and the 2-phosphoryl-3-thioxopropanoates 4 , respectively. Reaction of the cyanomethylphosphonates 1 with fluorophenylisothiocyanates in presence of methyliodide furnished the 2- thiometylvinylphosphonates 5 . The 2-mercaptovinylphosphonates 3 ′ reacted with ethyl chloroacetate in refluxing ethanol in the presence of triethylamine to give S-substitued derivatives 6 .     

The confirmation of accurate combination of functional and basis set for transition‐metal dimers: Fe2, Co2, Ni2, Ru2, Rh2, Pd2, Os2, Ir2, and Pt2

Eight kinds of density functionals named B3LYP, PBE1PBE, B1B95, BLYP, BP86, G96PW91, mPWPW91, and SVWN along with two different valence basis sets (LANL2DZ and CEP‐121g) are employed to study the transition‐metal dimers for the elements of group VIII. By comparing the equilibrium bond distances, vibrational frequencies, and dissociation energies of the ground state of these dimers with the available experimental values and theoretical data, we show that the “pure” DFT methods (G96PW91, BLYP, and BP86) with great‐gradient approximation always give better results relative to the hybrid HF/DFT schemes (B3LYP, PBE1PBE, and B1B95). The striking case found by us is that the G96PW91 functional, which is not tested in previous systemic studies, always predicts the dissociation energy to be well. The Ru₂ and Os₂ dimers are sensitive to not only the functionals employed but also the valence basis sets adopted. The natural bond orbital population is analyzed, and the molecular orbitals of the unpaired electrons are determined. Furthermore, our results indicate that the s and d orbitals of these dimers always hybridize with each other except for Rh₂ and Pt₂ molecules. And by analyzing the electron configuration of the bonding atom, the dissociation limit of the ground state is obtained. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

Gaseous HgH2, CdH2, and ZnH2

Gaseous HgH2, CdH2, and ZnH2 molecules were synthesized by the direct gas-phase reaction of excited mercury, cadmium, and zinc atoms with molecular hydrogen. The molecules were identified by their high-resolution infrared emission spectra, and the metal-hydrogen bond lengths were determined from the rotational analysis of the antisymmetric stretching fundamental bands.     

Zur Kenntnis der Dialkalimetalldichalkogenide β-Na2S2, K2S2, α-Rb2S2, β-Rb2S2, K2Se2, Rb2Se2, α-K2Te2, β-K2Te2 und Rb2Te2

On Dialkali Metal Dichalcogenides β-Na₂S₂, K₂S₂, α-Rb₂S₂, β-Rb₂S₂, K₂Se₂, Rb₂Se₂, α-K₂Te₂, β-K₂Te₂ and Rb₂Te₂ The first presentation of pure samples of α- and β-Rb₂S₂, α- and β-K₂Te₂, and Rb₂Te₂ is described. Using single crystals of K₂S₂ and K₂Se₂, received by ammonothermal synthesis, the structure of the Na₂O₂ type and by using single crystals of β-Na₂S₂ and β-K₂Te₂ the Li₂O₂ type structure will be refined. By combined investigations with temperature-dependent Guinier-, neutron diffraction-, thermal analysis, and Raman-spectroscopy the nature of the monotropic phase transition from the Na₂O₂ type to the Li₂O₂ type will be explained by means of the examples α-/β-Na₂S₂ and α-/β-K₂Te₂. A further case of dimorphic condition as well as the monotropic phase transition of α- and β-Rb₂S₂ is presented. The existing areas of the structure fields of the dialkali metal dichalcogenides are limited by the model of the polar covalence.     

Die H-Phasen: Ti2CdC,Ti2GaC,Ti2GaN,Ti2InN,Zr2InN und Nb2GaC

Zusammenfassung Die ternären Phasen Ti₂CdC, Ti₂GaC, Ti₂GaN, Ti₂InN, Zr₂InN und Nb₂GaC werden aus Monocarbid bzw.-nitrid, Übergangsmetall und Metametall hergestellt. Die Verbindungen erweisen sich sämtlich mit Cr₂AlC (H-Phase) isotyp. Die Gitterparameter werden ermittelt.     

Synthesis of 2, 2, 5, 5-tetramethyltetrahydrothiophene

Under the conditions of the Grignard reaction, 2, 5-dimethyl-2, 5-hexanediol has been obtained from diethyl succinate. Under the action of sulfuric acid, the latter has been cyclized to 2, 2, 5, 5-tetramethyl-tetrahydrofuran which, in its turn, by treatment with phosphorus pentasulfide, has given 2, 2, 5, 5-tetramethyltetrahydrothiophene. Its reaction with methyl iodide has given 2, 2, 5, 5-tetramethyltetrahydrothiophene methiodide.     

Photolyse von 2, 2, 4, 4-Tetramethylcyclobutanon-Derivaten

The photochemical reactions of the 2, 2, 4, 4-tetramethylcyclobutanones 1–6 carrying various substituents in 3-position were investigated. The major reaction in alcoholic solution or in the presence of other protic compounds was the formation of the semicyclic acetals 7–12 . Parallel to this reaction decarbonylation occurred, leading to stable cyclopropane derivatives in some cases, depending on the substituents present. Cyclopropanes with an exocyclic double bond underwent ring opening easily or, in case of an exocyclic carbon-nitrogen double bond, added alcohol, thus forming cyclopropane O, N-ketals. Alkyl-acyl biradicals are proposed as common intermediates for both photoreactions. Based on analogy to similar photoreactions reported in the literature, the formation of the semicyclic acetals is assumed to involve a carbene intermediate.     

穴醚[2, 2, 2]和穴醚[2, 2]对镉离子萃取行为的研究

本文研究了穴醚[2,2,2]和穴醚[2,2]在硝基甲烷中对镉的萃取行为。探讨了溶剂、穴醚浓度,碱浓度,无机酸浓度,盐效应及共存离子对镉萃取的影响。实验结果表明,硝基甲烷ε=35.6,μ=3.4德拜宜作为穴醚的溶剂。当穴醚[2,2,2]——硝基甲烷的浓度为2×10~(-3)M,Me_4NOH浓度为4×10~(-2)M时对镉的萃取最为有利。无机酸的引入使穴醚质子化程度加大,盐效应对镉的萃取无明显影响。十八种共存离子对镉萃取无干扰,因而选择性高。实验结果为用穴醚[2,2,2]萃取镉提供了依据。