Anisotropy of the angular correlation in high temperature single crystal Cu

A small anisotropy in the two-γ angular correlation of annihilation radiation in a single crystal copper was detected at 925°C by the rotating specimen method. The ratio of the anisotropy of the momentum distribution of pair electrons annihilated at a vacancy site has been estimated.     

Experimental and theoretical study on gas-phase ion/molecule reactions of silver trimer cation, Ag3+, with 12-crown-4

The reaction mechanisms of silver trimer cation, Ag3+, with 12-crown-4 (12C4) were studied experimentally and theoretically. Using a cylindrical ion trap time-of-flight mass spectrometer, gas-phase ion/molecule reactions of Ag3+ with 12C4 were observed. Metal-ligand complexes of [Ag(12C4)]+, [Ag3(12C4)]+ and [Ag3(12C4)2]+, and of [Ag(12C4)2]+ and [Ag3(12C4)3]+, were observed as the reaction intermediates and terminal products, respectively. The formations of the [Ag12C4]+ and [Ag(12C4)2]+ complexes indicated that the neutral dimer (Ag2) had been eliminated from the trimer cation. From the results of ab initio calculations at the HF/LanL2DZ level of theory and the experiments, it is suggested that three 12C4 molecules can attach to Ag3+ through consecutive reactions and that neutral Ag2 can be easily eliminated from [Ag3(12C4)]+.     

Chebyshev polynomial curve-fitting technique for strain-gage applications

A curve-fitting technique is presented which is especially suited to strain-gage measurements. The location of the strain gages is inherently specified by the method, and the number of gages to be used is also prescribed. The method of Chebyshev polynomial curve fitting assures a best fit in the least-squares sense. The procedure of using the method of strain-gage measurement and subsequent curve fitting is explained. The method is suitable for hand calculation but is more easily done on a digital computer. An example problem is given to illustrate the procedure, and a discussion of errors and error techniques is included.     

Intrinsicviskosit?t von Polyelektrolyten in Salzl?sungen

Ohne Zusammenfassung     

Catalytic enantioselective Diels-Alder reactions using titanium complexes of cis-N-sulfonyl-2-amino-1-indanols

A titanium complex derived from (1R, 2S)-N-(2,4,6-trimethylbenzenesulfonyl)-2-amino-1-indanol catalyzes the Diels-Alder reaction of 2-bromoacrolein and cyclopentadiene with 96.5:3.5 enantioselectivity. A new and efficient synthesis of 2-amino-1-indanol (6) contributes to the potential of this methodology.     

Synthesis of Non-natural Xyloglucans by Polycondensation of 4,6-Dimethoxy-1,3,5-triazin-2-yl Oligosaccharide Monomers Catalyzed by Endo-β-1,4-glucanase

Summary: A cellotetraose-backboned hepta-saccharide (XXXG) (a capital X represents a glucopyranose residue that is substituted with a xylopyranose through an α-1,6 glycosidic bond, and a capital G represents a non-substituted glucopyranose residue) and a nona-saccharide (XLLG) (a capital L represents a glucopyranose residue that is substituted with a galactopyranoseβ(1-2)xylopyranose through an α-1,6 glycosidic bond) have directly been converted to the corresponding 4,6-dimethoxy-1,3,5-triazin-2-yl derivatives (DMT-β-XXXG 1 and DMT-β-XLLG 2 , respectively) by the action of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methyl morpholinium chloride (DMT-MM). The selective nucleophilic attack of the anomeric hydroxyl group to DMT-MM has been achieved in water without using any protection of the hydroxyl groups. The resulting activated oligosaccharide derivatives ( 1 and 2 ) were found to polymerize catalyzed by an endo-β-1,4-glucanase as catalyst. The polymerization took place in a complete regio- and stereo-selective manner, affording non-natural polysaccharides having a XXXG-repeating unit and a XLLG-repeating unit, respectively, in the main chain. It is extremely difficult to construct such definite repeating structures via the conventional synthetic routes including protection-deprotection procedures.