O $$(\bar \Lambda /m_c )$$ effects in tests of factorization hypothesis for heavy-hadron nonleptonic decays

In the framework of the heavy-quark effective theory, theO ( O(_QCD)) corrections are estimated in the test of factorization hypothesis forB-meson nonleptonic decays proposed by Bjorken. Similar calculations are also carried out for _b nonleptonic decays. The effects of these corrections on the estimate of theD _s -meson decay constant are discussed.     

Successive methyl migrations occurring in the acid treatment of 1-epoxyethyl-1,2,2-trimethyl-cyclopentane derivative

Acid treatment of (IR, 3S,1′S)-1-(1′,2′-Epoxyethyl)-1,2,2-trimethyl-3-acetoxymethyl-cyclopentane $\text{6}$) has been shown to yield three products ($\text{8}$, $\text{9}$, $\text{10}$), among which $\text{8}$ and $\text{9}$ are 1-oxa-bicyclo[3.3.0]octane derivatives formed $\text{via}$ successive methyl migrations followed by an oxorane ring closure.     

What is the weighing form in gravimetric determination of antimony(III) with oxine?

The gravimetric analysis of antimony(III) with oxine (8-quinolinol, Hox) was studied. The amount of antimony left in filtrate and washing solutions was corrected with the results of atomic absorption spectrometry. The weighing form, which had not been conclusive before the present study, was determined to be SbO(ox)(Hox)2. The result (purity of antimony(II) oxide: 99.84 +/- 0.05% (m/m)) of the gravimetric analysis was in good agreement with that of coulometric titration with electrogenerated iodine.     

Tetracyanoresorcin[4]arene as a pH dependent artificial acetylcholine receptor

This communication describes the facile synthesis of tetracyanoresorcin[4]arene and its high and pH dependent affinities toward biologically important acetylcholine in the physiological pH region.     

Synthesis of biantennary complex-type nonasaccharyl asn building blocks for solid-phase glycopeptide synthesis

The biantennary complex-type N-glycans bearing LacNAc and LacdiNAc as the nonreducing end motif were synthesized in a protected form suitable to use in the Fmoc solid-phase peptide synthesis studies. Two approaches for the nonasaccharide synthesis were examined by taking advantage of the highly β-selective glycosylation with GlcNTCA (N-phenyl)trifluoroacetimidate. An earlier approach, which involved the reaction of the trisaccharide donor (Gal-GlcNTCA-Man) and trisaccharide acceptor (Man-GlcNPhth(2)-N(3)), produced a mixture of nonasaccharide isomers. On the other hand, mannosylation of the trisaccharide acceptor (Man-GlcNPhth(2)-N(3)) stereoselectively afforded the known pentasaccharide (Man(3)-GlcNPhth(2)-N(3)), which was reacted with the disaccharyl glycosyl donor (Gal-GlcNTCA or GalNTCA-GlcNTCA) to produce the desired nonasaccharide as a single stereoisomer. Selective dephthaloylation followed by N-acetylation furnished the GlcNAc(2) functionality. The resulting nonasaccharyl azides were condensed with Fmoc-Asp(OPfp)-OBu(t) or Fmoc-Asp(OPfp)-OPac in the presence of Ph(CH(3))(2)P and HOOBt. Finally, the Zn reduction and cleavage of the tert-butyl ester or Zn reduction alone produced the targeted nonasaccharyl Asn building blocks.     

Search for anomalous top–gluon couplings at LHC revisited

Through top-quark pair productions at LHC, we study possible effects of nonstandard top–gluon couplings yielded by SU(3)×SU(2)×U(1) invariant dimension-6 effective operators. We calculate the total cross section and also some distributions for $pp\to t\bar{t}X$ as functions of two anomalous-coupling parameters, i.e., the chromoelectric and chromomagnetic moments of the top, which are constrained by the total cross section $\sigma(p\bar{p}\to t\bar{t}X)$ measured at Tevatron. We find that LHC might give us some chances to observe sizable effects induced by those new couplings.     

New prenylated C₆-C₃ compounds from the twigs of Illicium anisatum

Two new prenylated C?-C? compounds, cycloillicinone (1) and 4-allyl-2-methoxy-6-(2-methylbut-3-en-2-yl)phenol (2), were isolated from the twigs of Illicium anisatum, and their structures were determined by 2D-NMR methods. Cycloillicinone (1) is a unique prenylated C?-C? that is appended with an additional geranyl unit. Compound 2 was found to show moderate neurite-outgrowth promoting activity in primary cultured rat cortical neurons at a concentration of 10 μM.     

Transmembrane nanopores from porphyrin supramolecules

A porphyrin-based nanopore was constructed through a bilayer lipid membrane (BLM). The macrocyclic porphyrin (the inner diameter = ca. 2.1 nm) having six carboxylic acid groups directed up and down was synthesized by self-assembly of three trisporphyrins, metathesis linking, and subsequent hydrolysis. The porphyrin was incorporated into soybean lecithin based BLM, and the ion currents through the nanopore were observed under 500 mM KCl, LiCl, CaCl2, and tetraalkylammonium chloride solutions, indicating formation of a large pore through BLM. Blocking of the ion current was achieved by addition of the polycationic fourth-generation PAMAM dendrimer.     

Two new sesquiterpenoids and two new prenylated phenylpropanoids from Illicium fargesii, and neuroprotective activity of macranthol

Two new seco-prezizaane-type sesquiterpenoids 1, 2 and two new prenylated phenylpropanoids 4, 5 were isolated along with 15 known compounds from Illicium fargesii. The structures of 1, 2 were elucidated as 10-O-(E)- and 10-O-(Z)-cinnamoyl-2-oxo-6-deoxyneoanisatin by analysis of spectroscopic data and by comparison of their NMR data with those of previously reported 2-oxo-6-deoxyneoanisatin (3), respectively, whereas the structures of 4, 5 were identified as 4-allyl-2-(3-methylbut-2-en-1-yl)phenol and 4-allyl-2-(2-methylbut-3-en-2-yl)phenol, respectively, on the basis of spectroscopic data. Among the isolated compounds, macranthol (7) was found to have neuroprotective activity at 5--10 microM in rat cortical neurons cultured in DMEM/N2 medium.