Trace element determination in vitamin E using ICP-MS

Vitamin E supplements are either isolated from plants sources or prepared synthetically. Isolation from plants includes eight different tocopherol structures. Vitamin E synthesis includes seven different stereoisomers, which involves the use of several catalysts that may lead to trace element contamination in the vitamin. The use of ICP-MS is an ideal technique for detecting these trace elements. However, the oily nature of the samples requires the development of a sample preparation methodology. This study was done upon the request of synthetic vitamin E manufacturers to test the trace metal purity of their samples. In this work, the comparison of an acid microwave digestion and emulsion preparation is discussed. Cromium, nickel, tin and lead were found in the synthetic vitamin E analyzed and 200, 60, 9 and 45 ppb were the concentrations found respectively for these elements.Digesting the samples gives slightly lower detection limits compared to the emulsion preparation.     

Enantioselective approach to indolizidine and quinolizidine scaffolds. Application to the synthesis of peptide mimics

An enantioselective approach to substituted indolizidine and quinolizidine frameworks has been developed. Key steps of the synthesis are the enantioselective, palladium-catalyzed N-allylation of an imide, the nucleophilic allylation of an acyliminium ion and a ring closing metathesis. This general strategy has been applied to the synthesis of indolizidine peptide mimics, starting from a chiral imide derived from l-aspartic acid. It was observed that the preexisting stereogenic center of this substrate has a moderate influence on the stereoselectivity of the electrophilic allylation, which is mainly determined by the sense of chirality of the catalyst.     

Estimation of dynamic elastic constants from the amplitude and velocity of Rayleigh waves

In this paper a method is proposed to characterize the elasticity of isotropic linear materials from the generation and detection of an acoustic surface wave. For the calculation of the elastic constants, it is sufficient that only one of the faces of the sample be accessible. The methodology is based on both the measurement of the Rayleigh wave velocity and on the determination of the normal to longitudinal amplitude ratio calculated from the normal and longitudinal components of the displacement of a point. The detection of two consecutive surface wave pulses using a single experimental setup permits the determination of the elastic constants. The method is applied to calculate Young's modulus and Poisson's ratio of an aluminum sample as well as their systematic uncertainties. The results obtained give a relative uncertainty for Young's modulus on the order of the sixth part of that calculated for Poisson's ratio.     

Search for D0-D0 mixing in D0 --> K+ pi(-) decays and measurement of the doubly-Cabibbo-suppressed decay rate

We have searched for mixing in the D(0)-D (0) system by measuring the decay-time distribution of D(0) --> K(+) pi(-) decays. The analysis uses 90 fb(-1) of data collected by the Belle detector at the KEKB e(+) e(-) collider. We fit the decay-time distribution for the mixing parameters x' and y' and also for the parameter R(D), which is the ratio of the rate for the doubly-Cabibbo-suppressed decay D(0)--> K+ pi(-) to that for the Cabibbo-favored decay D(0)--> K-pi(+). We do these fits both assuming CP conservation and allowing for CP violation. We use a frequentist method to obtain a 95% C.L. region in the x'(2) - y' plane. Assuming no mixing, we measure R(D) = (0.381 +/- 0.017(+0.008)(-0.016))%.     

Determination of /Vub/ from measurements of the inclusive charmless semileptonic partial rates of B mesons using full reconstruction tags

We present a measurement of the Cabibbo-Kobayashi-Maskawa matrix element /Vub/, based on 253 fb(-1) of data collected by the Belle detector at the KEKB e+ e- asymmetric collider. Events are tagged by fully reconstructing one of the B mesons, produced in pairs from Gamma(4S). The signal for b --> u semileptonic decay is distinguished from the b --> c background using the hadronic mass Mx, the leptonic invariant mass squared q2 and the variable P+ [triple bond] Ex - /px/. The results are obtained for events with p(l)* > or = 1 GeV/c, in three kinematic regions (1) Mx < 1.7 GeV/c2, (2) Mx < 1.7 GeV/c2 combined with q2 > 8 GeV2/c2, and by (3) P+ < 0.66 GeV/c. The matrix element /Vub/ is found to be (4.09 +/- 0.19 +/- 0.20(+0.14) -0.15 +/- 0.18) x 10(-3), where the errors are statistical, systematic including Monte Carlo modeling, theoretical, and from shape function parameter determination, respectively.     

Search for CP violation in the decay B0-->D*+/-D-/+

We report a search for CP-violating asymmetry in B0-->D(*+/-)D-/+ decays. The analysis employs two methods of B0 reconstruction: full and partial. In the full reconstruction method all daughter particles of the B0 are required to be detected; the partial reconstruction technique requires a fully reconstructed D- and only a slow pion from the D(*+)-->D0pi(+)(slow) decay. From a fit to the distribution of the time interval corresponding to the distance between two B meson decay points we calculate the CP-violating parameters and find the significance of nonzero CP asymmetry to be 2.7 standard deviations.     

Observation of radiative B-->phi K gamma decays

The radiative decay B-->phi K gamma is observed for the first time. The branching fraction for the charged B--->phi K- gamma decay mode is measured to be B(B--->phi K- gamma)=(3.4+/-0.9+/-0.4)x10(-6). The photon energy distribution for the B--->phi K- gamma decay is presented. The signal for the neutral B(0)-->phi K(0)gamma decay mode is not statistically significant and an upper limit, B(B(0)-->phi K(0)gamma)<8.3x10(-6) at 90% C.L., is set. The analysis is based on a data set of 90 fb(-1) collected by the Belle experiment at the e(+)e(-) asymmetric collider KEKB.     

Measurement of branching fractions for B-->eta(c)K(*) decays

We report measurements of branching fractions for charged and neutral B-->eta(c)K decays where the eta(c) meson is reconstructed in the K(0)(S)K+/-pi(-/+), K+K-pi(0), K(*0)K-pi(+), and pp; decay channels. The neutral B0 channel is a CP eigenstate and can be used to measure the CP violation parameter sin(2phi(1). We also report the first observation of the B0-->eta(c)K(*0) mode. The results are based on an analysis of 29.1 fb(-1) of data collected by the Belle detector at KEKB.     

Synthesis and Characterization of New Unsymmetrically Substituted Phthalocyanines

 Unsymmetric metallophthalocyanines (M=Zn, Co, Ni) carrying alkylthio and acetyloxyethylthio groups on peripheral positions were prepared from 4,5-bis-alkylthio-phthalonitrile, 4,5-bis-(acetyloxyethylthio)-phthalonitrile, and the corresponding anhydrous metal salts Zn(CH₃COO)₂, NiCl₂, and CoCl₂. The extremely soluble compounds were characterized by their IR, ¹H NMR, and UV/Vis spectra. Their long wavelength absorption band was found to be bathochromically shifted; their solubility is superior to that of symmetrical phthalocyanines.     

Metal-Containing Phthalocyanines Substituted with One Branched Bulky Moiety and Six Alkylthio Groups

Summary.  Unsymmetrically substituted metal-phthalocyanines composed of three hexylthio groups and one 1-chloro-3,4-dicyano-6-[2-(2-pyridylmethylamino)phenylthio]benzene moiety was prepared by cyclization of the reactants in the presence of the anhydrous metal salts Zn(CH₃COO)₂, NiCl₂, and CoCl₂. The new unsymmetric phthalocyanines are very soluble in common organic solvents. The compounds were characterised by their elemental analyses, IR, ¹H NMR, MS and UV/Vis spectra. Corresponding author. E-mail: bayir@itu.edu.tr Received November 27, 2002; accepted (revised) December 2, 2002 Published online May 2, 2003