Nano-SIMS analysis of Mg, Sr, Ba and U in natural calcium carbonate.

Concentrations of minor (Mg and Sr) and trace (Ba and U) elements in four natural calcium carbonate samples were first analyzed by inductively coupled plasma mass spectrometry (ICP-MS) after chemical dissolution and calibrated against a standard dolomite. Their homogeneities were checked by in situ laser ablation (LA) ICP-MS with 10-20 spots. The carbonate samples were measured by using a high lateral resolution secondary ion mass spectrometer (Nano-SIMS NS50). A approximately 4 nA O- primary beam was used to sputter a 5-6-microm diameter crater on the sample surface, and secondary positive ions were extracted for mass analysis using an accelerating voltage of 8 kV and a Mattauch-Herzog geometry. A multi-collector system was adjusted to detect 26Mg+, 43Ca+, 88Sr+, 138Ba+, 238U16O+ and 238U16O2+ ions at the same time. A resolving power of 2500-5000 at 10% peak height was attained by an entrance slit set at 40 microm, and each exit slit at 50 microm with adequate flat-topped peaks. The observed 26Mg/43Ca, 88Sr/43Ca, 138Ba/43Ca and 238U16O2/43Ca ratios agreed well with those measured by LA-ICP-MS. Foraminifera shells were analyzed at 5-6 microm scale by Nano-SIMS. There was a large variation of the Mg/Ca ratios, up to +/- 38%, even in a single fragment of the shell, suggesting that although the ratios provide a useful paleoceanographic proxy at bulk scale, they may reflect a more complex pattern at < 10 microm scale.     

Metal‐cation‐induced chiroptical switching for poly(phenylacetylene) bearing a macromolecular ionophore as a graft chain

A poly(phenylacetylene) bearing a polycarbohydrate ionophore as a graft chain (copolymer 4 ) was synthesized by the copolymerization of end‐functionalized (1→6)‐2,5‐anhydro‐3,4‐di‐O‐ethyl‐D ‐glucitol with a 4‐ethynylbenzoyl group (macromonomer 2 ) with phenylacetylene. Copolymer 4 showed a split‐type circular dichroism (CD) in the long absorption region of the conjugated polymer backbone (280–500 nm), and the CD pattern varied in response to external stimuli, such as the solvents and temperature. This suggested that 4 had a predominantly one‐handed helical conformation in the polyacetylene backbone. The CD pattern of 4 was completely inverted by the formation of a complex between the macromolecular ionophore units and the selected metal cations, that is, Ba²⁺, Pb²⁺, Sr²⁺, Na⁺, and Li⁺. This suggested that copolymer 4 underwent a helix–helix transition through the host–guest complexation with achiral inorganic metal cations. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5855–5863, 2005     

Identification of Two Palmitoyl Groups in Octopus Rhodopsin

Abstract— We determined the structure and site of fatty acid incorporated in octopus rhodopsin using a combination of fluorescence label and enzymatic cleavage methods in conjunction with fast-atom bombardment (FAB) mass spectrometry. A single peptide containing two adjacent cysteines, Cys337 and Cys338, was successfully isolated using the fluorescence from a dye conjugated to Cys345. The FAB mass spectrometric analysis of the peptide (323phe-³⁴⁰phe) revealed that two palmitoyl groups are linked to Cys337 and Cys338 via thioester bonds in octopus rhodopsin as in bovine rhodopsin.     

Isolation and structures of euonymine and neoeuonymine,alkaloids from Euonymus Sieboldiana blume

Two new alkaloids, euonymine 5 and neoeuonymine 14 were isolated from Euonymus Sieboldiana Blume. The structures of euonymine and neoeuonymine were established to be 5 and 14, respectively, by chemical and spectral means: the structural features of euonymine 5 are that it is a polyhydroxyl sesquiterpene of eudesman type (euonyminol) which is esterified with evoninic acid 3 and six moles of acetic acid. Neoeuonymine 14 was converted to euonymine 5. Direct conversion of evonine 1 to euonymine 5 was also achieved.     

Canonical quantization of the electromagnetic field with Dirac's monopoles

From a lagrangian theory of charge-monopole electrodynamics which uses strings but is free from Dirac's veto, a hamiltonian theory is derived which describes the interaction between electric and magnetic point particles and photons.     

Further studies on palytoxin. II. structure of palytoxin

The full structure of palytoxin, a potent coelenterate toxin, is reported.     

Copper(II) chloride as a new,efficient additive suppressing racemization in peptide synthesis by the carbodiimide method

Copper(II) chloride was found to be an extremely efficient additive suppressing racemization in the carbodiimide mediated couplings.     

Dielectric loss of polyethylene at very low temperatures in the frequency range from 1 kHz to 100 MHz

The dielectric loss of high-density polyethylene was measured from 1 kHz to 100 MHz with the improved calorimetric method at liquid-helium temperature for samples with different oxidation times t. Two loss peaks, centered at ca. 4 kHz and at 1 MHz, both increase in height with increasing t. On the bases of these results along with previously reported ones, the low-frequency and high-frequency losses are ascribed to the tunneling of protons of OH groups in crystalline and amorphous regions, respectively.