1H(17F,α)14O反应截面测量

14O （α,p）17F是天体X射线暴中重要的突破反应。本工作通过厚靶方法测量其逆反应1H （17F,α）14O的反应截面来研究这一关键反应。本实验工作是在日本东京大学原子核科学研究中心（CNS）的低能次级束流线（CRIB）上完成的,后续的扣除本底实验是在兰州放射性束流线（RIBLL1）上完成的。CRIB实验是通过2H （16O,n）17F转移反应产生17F次级束,经过CRIB分离提纯之后,利用该次级束轰击氢气靶。在氢气靶后布置了三套望远镜探测器系统,用以探测不同实验角度的反冲α粒子,在数据处理的过程中经过动力学重构后得到了1H （17F,α）14O反应在质心系能区E_c.m.=2.7~3.4 MeV的反应截面。实验结果在3 MeV以上的高能区与前人的薄靶实验数据是一致的,在低能区本工作获得了新的实验数据,倾向于支持干涉相消的理论预言结果。The 14O(α, p)17F reaction is one of the important breakout reactions in type I X-ray burst. This work reported a new cross section measurement of its reverse reaction of 1H(17F,α)14O. The experiment was performed using the CNS radioactive ion beam separator (CRIB), located at the Center for Nuclear Study (CNS), the University of Tokyo. The sequent background measurement was carried out at Radioactive Beam Line in Lanzhou (RIBLL1). 17F beam was produced via the transfer reaction of 2H(16O, n)17F, subsequently separated and purified by CRIB and bombarded a thick hydrogen H₂ gas target. The recoiling α particles were measured by three △E-E silicon telescopes at three different angles. The total cross sections of 1H(17F,α)14O have been derived at E_c.m.=2.7~3.4 MeV based on an isotropic angular distribution assumption. Our results are consistent with the previous ones in the energy region of E_c.m.>3 MeV, and we also obtained some new data in the low energy region, which partly support the destructive interference between the direct and resonant reaction mechanism predicted by the theory.     

Dimeric azaphilones from the xylariaceous ascomycete Hypoxylon rutilum

Fractionation of the methanolic extract of the stromata of Hypoxylon rutilum (Xylariaceae, Ascomycetes) resulted in the isolation of two novel dimeric azaphilones named rutilins A and B, together with the known compounds, entonaemin A, and rubiginosins A and B. Their structures were elucidated by 2D NMR, HR-MS, IR and UV spectroscopy. Rutilins A and B are presumably synthesized via specific biogenic aldol condensations of mitorubrinol acetate moieties with rubiginosins A and B, respectively. The resulting dimeric azaphilone scaffold of the rutilins is unprecedented in nature.     

Solid solution of triptycenequinone and triptycenehydroquinone as a non-stoichiometric quinhydrone. Bathochromic changes in color caused by local intermolecular interaction between p-benzoquinone and hydroquinone moieties

Binary crystal formed by 9,10-dihydro-9,10-[o]benzenoanthracene-1,4-dione (triptycenequinone, TPQ, yellow) and 9,10-dihydro-9,10-[o]benzenoanthracene-1,4-diol (triptycenehydroquinone, TPHQ, colorless) was found to be a substitutional solid solution of TPQ doped by TPHQ with concentration of TPHQ<ca. 0.2. The characteristic color (brown) of the solid solution may be ascribed to local intermolecular CT interaction between the p-benzoquinone and hydroquinone moieties of TPQ and TPHQ, respectively, enabled by a disorder in the binary crystal. It seemed appropriate to regard the solid solution as non-stoichiometric quinhydrone. Crystal structure of pure TPHQ is also reported. A common molecular arrangement in the crystals of pure TPQ and pure TPHQ, as well as the resemblance in the molecular structure, seems to be favorable for the formation of the solid solution.     

Iridium-catalyzed [2+2+2] cycloaddition of α,ω-diynes with alkynyl ketones and alkynyl esters

We found that the combination of [Ir(cod)Cl]₂ and rac-BINAP served as an efficient catalyst for the [2+2+2] cycloaddition of 2,7-nonadiyne derivatives and related compounds with alkynyl ketones and alkynyl esters. The corresponding products were obtained in high yields under mild reaction conditions.     

Enantioselective Michael addition of beta-keto esters to methyl vinyl ketone employing a chiral N,N'-dioxide-scandium trifluoromethanesulfonate complex as a catalyst

An enantioselective Michael addition of beta-keto esters to methyl vinyl ketone exploiting a chiral N,N'-dioxide-scandium trifluoromethanesulfonate complex as a catalyst affords the corresponding Michael adducts in high yields and with enantioselectivities of up to 80% ee.