U(2)L×U(2)R介子手征理论中对衰变ρ→ππ的重求和研究

把U(2)_L×U(2)_R介子手征理论中对矢量介子的O(p⁴)计算用重求和方法进行了改进,并重新研究了衰变ρ→ππ.由此得到了f_ρππ(p²)直到O(p^∞)的完整表达式,并基于收敛性条件和么正性条件给出了一个重要的非微扰结论.     

Enantiomer-selective radical cyclopolymerization of rac-2,4-pentanediyl dimethacrylate using a ruthenium-mediated chiral atom transfer radical polymerization initiating system

The enantiomer-selective radical polymerization of rac-2,4-pentanediyl dimethacrylate, an equimolar mixture of (2S,4S)-2,4-pentanediyl dimethacrylate (SS- 1 ) and (2R,4R)-2,4-pentanediyl dimethacrylate (RR- 1 ), was carried out with a chiral atom transfer radical polymerization initiating system consisting of methyl 2-bromoisobutyrate ( 3 ), dichlorotris(triphenylphosphine)ruthenium [RuCl₂(PPh₃)₃], and a chiral additive in anisole at 60 °C. When (S)-1,1′-bi-2-naphthol ( a-3 ) was used as the chiral additive, the recovered monomer was enriched in SS- 1 , and the enantiomeric excess was 16.9% at a 22.6% monomer conversion. The specific rotation ([α]₄₃₅, c 0.3, CHCl₃) of the resulting polymer was +40.3° at a 22.6% monomer conversion. For the copolymerization of SS- 1 and RR- 1 with 3 /RuCl₂(PPh₃)₃/ a-3 in anisole at 60 °C, the monomer reactivity ratio for RR- 1 (r_R) was determined to be 4.94, and that for SS- 1 (r_S) was 0.27. For the homopolymerizations of SS- 1 and RR- 1 with 3 /RuCl₂(PPh₃)₃/ a-3 in anisole at 60 °C, the polymerization rate of RR- 1 was considerably faster than that of SS- 1 , and the rate constants for the homopolymerizations were determined to be k_SS = 2.0 × 10⁻³ h⁻¹ and k_RR = 8.2 × 10⁻³ h⁻¹, respectively. With the values of k_SS, k_RR, r_R, and r_S, the relative ratio k_SS/k_RR/k_SR/k_RS was determined to be 1.2:4.9:4.5:1, which indicated that both the growing end of SS- 1 and that of RR- 1 preferentially reacted with RR- 1 . © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4563–4569, 2004     

椭圆芯手征光纤的基模特性研究

对椭圆芯手征光纤进行了严格的求解，得到了模式场的解析解；推了了模式特征方程；并对基模的偶模和奇模特征方程进行数值求解，研究了手征参数对不同椭圆比下基模的色散曲线，双折射，模间色散等特性的影响。     

QUADRATIC INTEGRABILITY AND BOUNDEDNESS OF THE SOLUTIONS FOR SECOND ORDER NONLINEAR DELAY DIFFERENTIAL EQUATIONS

In this paper, by means of auxiliary functions and inequalities, we obtain some sufficient conditions of second order nonhomogeneous delay differential equation belonging to the L.S. or L.S. ∩L.C..     

New oxazoline-containing phosphoramidite ligand for palladium-catalyzed asymmetric allylic sulfonylation

New chiral oxazoline-containing phosphoramidite was synthesized and its complex formation with rhodium(i) and palladium(ii) was examined. The new ligand is a highly efficient chiral inductor (ee up to 92%) in palladium-catalyzed asymmetric sulfonylation of 1,3-diphenylallyl acetate with sodium p-toluenesulfinate.     

Enantioselective Michael additions of β-keto esters to α,β-unsaturated carbonyl compounds catalyzed by a chiral biquinoline N,N′-dioxide-scandium trifluoromethanesulfonate complex

A catalytic, enantioselective Michael addition of β-keto esters to α,β-unsaturated carbonyl compounds was achieved by using a chiral biquinoline N,N′-dioxide-scandium trifluoromethanesulfonate complex as a catalyst. The corresponding Michael adducts were obtained in high yields and with enantioselectivities up to 84% ee.     

Modular chiral polyether podands and their lanthanide complexes

A novel series of modular chiral polyether podands derived from enantiomerically pure hydrobenzoin and binaphthol has been prepared using a NaH/15-crown-5 mediated Williamson ether synthesis. These new homochiral ligands form catalytically active complexes with lanthanide triflates, two of which have been characterised by X-ray diffraction.     

Helicity induction on a poly(phenylacetylene) bearing a phosphonate residue by chiral dendrons

A series of optically active dendrons with a primary amino group at the terminal were prepared from L - or D -glutamic acid, and their helicity induction abilities for a poly(phenylacetylene) bearing a phosphonate pendant were characterized with ultraviolet–visible and circular dichroism spectroscopy. The magnitude of the Cotton effects of the polymer induced by the dendrons significantly increased upon complexation with a higher generation dendron. The effect of the chirality of the glutamate residues (L and D ) on the helicity induction was also studied. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4580–4586, 2004