冷蒸气原子吸收光谱法测定铜精矿中的汞

本文研究了一种用冷蒸气原子吸收光谱测定铜精矿中汞的方法。铜精矿用逆王水或硫酸-高锰酸钾(固)消化后用测汞仪测定其中的汞含量。测定结果的相对标准偏差小于5%;回收率在92-107%之间。     

On the specific heat of nonstoichiometric ceria

Ceria (CeO₂) can readily be reduced to form a wide range of binary compounds CeO_y, 2 ≥y ≥ 1.5. Specific heat measurements at constanty were carried out for the composition range 2≥y > 1.714 and for the temperature range 300 K <T < 1200 K. In thisy,T region the specific heat exhibits a complex form reflecting various transformations. The results and theoretical evaluations of the specific heat are presented as the temperature is varied from low values (T ≈ 400K) where two phases coexist, through several phase transformations to a high temperature α phase. Special features of the specific heat due apparently to increased internal local pressure appearing for small deviations from stoichiometry are also discussed.     

A New Route to 2-Aminoalkanephosphonic Acids

The phosphonic acids and their esters, which are more resistant to hydrolysis than phosphates, could find wide application in biochemistry as regulators for metabolic processes¹.     

X-ray and neutron diffraction studies of the hydridotriruthenium cluster complex (μ-H)Ru3(CO)7(μ-As(C6H5)CH2As(C6H5)2) ((C6H5 2AsCH2As(C6H5)·CH2Cl2: an example of dibridged metal-metal bond M(μ-H)(μ-X)M,involving a heavy bridgehead atom

The title compound is (μ-H)Ru₃(CO)₇(μ-As(C₆H₅)CH₂As(C₆H₅)₂)((C₆H₅)₂ AsCH₂As(C₆H₅)₂)·CH₂C1₂. Crystal data: monoclinic,P2₁/n, cell parameters (X-ray)a=12.82(2) Å,b=22.91(2) Å,c=17.83(2) Å, β=99.1(3)°; (neutron)a=12.94(1) Å, β=22.95(2)Å,c=17.93(3)Å,β=99.55(5)°. The structure was solved from X-ray data. FinalR indices areR(F)=0.051,R _w (F)=0.049 (X-ray);R(F)=0.064,R _w (F)=0.048,R(F ²)=0.072,R _w (F²)=0.088 (neutron). The complex is derived from Ru₃(CO)₈(dpam)₂ through reaction with hydrogen. The structure consists of a triangular array of metal atoms involving three metal-metal bonds[Ru(1)?Ru(2)=2.912(7)Å;Ru(1)?Ru(3)=2.829(3) A; Ru(2)?Ru(3)=2.845(6) Å]. The metal-metal edge Ru(1)?Ru(2) is supported by a bridging bis(diphenylarsino)methane ligand which lies in the equatorial plane. Activation of the second dpam ligand has generated the new face-bridging ligand unit μ-As(C₆H₅)CH₂As(C₆H₅)₂. In this unit, the bridgehead As atom spans over the Ru(1)?Ru(2) bond, while the second As atom is only bonded to Ru(3). The metal environment is achieved by CO ligands. The hydride ligand is bridging the Ru(1)?Ru(2) vector [Ru(1)?H=1.791(10) Å; Ru(2)?H=1.818(8) Å]. Geometric features of the dibridged Ru(μ-H)(μ-As)Ru bond are discussed.     

百焦耳KrF激光器腔体的设计和激光实验

1990年原子能科学研究院建成一台百焦耳KrF激光器,最大能量输出达106焦耳。本文介绍激光器腔体主要结构参数的选定和激光实验。     

A Mechanistic Investigation of the Visible‐Light Photocatalytic Trifluoromethylation of Heterocycles Using CF3I in Flow

Photocatalytic radical trifluoromethylation strategies have impacted the synthesis of trifluoromethyl‐containing molecules. However, mechanistic aspects concerning such transformations remain poorly understood. Here, we describe in detail the mechanism of the visible‐light photocatalytic trifluoromethylation of N‐methylpyrrole with gaseous CF₃I in flow. The use of continuous‐flow microreactor technology allowed for the determination of different important parameters with high precision (e.g., photon flux, quantum yield, reaction rate constants) and for the handling of CF₃I in a convenient manner. Our data indicates that the reaction occurs through a reductive quenching mechanism and that there is no radical chain process present.     

Electrical cross-talk in four-electrode experiments

Journal of Solid State Electrochemistry - The subject of this paper is electrical cross-talk, an interference between the current/voltage characteristics of the two working electrodes in...