Total Synthesis of the Proposed Structure of (+)-Tolyporphin A O,O-Diacetate

Four monocyclic precursors were assembled in the total synthesis of the proposed structure 1 - A of (+)-tolyporphin A O,O-diacetate (X=Ac). Comparison of the spectroscopic data demonstrated that synthetic tolyporphin O,O-diacetate did not match the O,O-diacetate prepared from natural (+)-tolyporphin A (X=H), calling for a structural revision of this class of natural products. On the basis of a series of NMR experiments including synthetic intermediates, the structure of tolyporphin A is concluded to be 1 - B , in which the configurations of quaternary centers C7 and C17 are opposite to those in the originally proposed structure.     

Association Between Social Network and Physical Function in Community-Dwelling Older Adults in Japan

Objective: A poor social network and the decline of physical function are known to be critical risk factors for functional decline in older adults. The aim of this study was to investigate the relationships between social network and physical function in Japanese community-dwelling older adults. Methods: Participants were 339 adults aged 65 years or older (mean age : 73.0 years, women :70.2%), living independently in their communities. A self-reported questionnaire was used to assess social network on two different scales―the 6-item Lubben Social Network Scale (6LSNS) and frequency of contact with other people. Handgrip strength, knee extension strength, gait speed, Timed Up and Go Test (TUG) results, and 5-repetition chair stand test (CST) scores were used to determine physical function. A multiple regression analysis that adjusted for confounding factors was used to analyze the relationship between the social network scales and each physical function test. Results: According to the results of a multiple regression analysis, a high 6LSNS score was significantly associated with greater handgrip strength (B = 0.63, p = 0.03), faster CST (B = −0.23, p = 0.01), and faster TUG (B = −0.12, p = 0.03), and high frequency of contact was significantly associated with greater handgrip strength (B = 1.08, p = 0.01). Conclusions: Social network was associated with muscle strength and physical performance. Consequently, older adults with poor social networks require an assessment of physical function, since their physical functions have possibly deteriorated.     

A metallocene catalyst system for olefin polymerization using a heteropolyacid as the counter-anion

Polymerization of ethylene and propene were conducted with bis(cyclopentadienylzirconium dichloride) (Cp₂ZrCl₂) and ethylenebis(1-indenyl)zirconium dichloride (Et(Ind)₂ZrCl₂) combined with trialkylaluminium compounds using heteropolyacids as the counter-anions, giving linear polyethylene and isotactic polypropene, respectively. No polymer was obtained when using Cp₂Zr(CH₃)₂ instead of Cp₂ZrCl₂. The mechanism of the formation of active species is briefly discussed on the basis of these results.     

Boundedness of bilinear pseudo-differential operators with BS0,0m$BS^{m}_{0,0}$ symbols on Sobolev spaces

In this paper, bilinear pseudo-differential operators with symbols in the bilinear Hörmander class $B{S}_{0,0}^m$ are considered. In particular, the boundedness of these operators on Sobolev spaces is established. Our main result is proved by using symbolic calculus and the boundedness of those operators with certain S_{0, 0}-type symbols on Lebesgue spaces.