A theory of concordance for non-spherical 3-knots

Consider a closed connected oriented 3-manifold embedded in the -sphere, which is called a -knot in this paper. For two such knots, we say that their Seifert forms are spin concordant, if they are algebraically concordant with respect to a diffeomorphism between the 3-manifolds which preserves their spin structures. Then we show that two simple fibered 3-knots are geometrically concordant if and only if they have spin concordant Seifert forms, provided that they have torsion free first homology groups. Some related results are also obtained.

     

BF3.OEt2-mediated cycloaddition of O-tert-butyldimethylsilyloximes having olefin moieties: intramolecular cycloaddition of N-borano-nitrones

Treatment of O-tert-butyldimethylsilyloximes having olefin moieties in the molecules with BF3.OEt2 results in efficient generation of N-borano-nitrones, which undergo intramolecular cycloaddition at room temperature to afford N-nonsubstituted cycloadducts after work-up.     

Application of microgels as polymer supports for organic synthesis: preparation of a small phthalide library,a scavenger,and a borohydride reagent

Microgel polymers containing a series of functional groups have been prepared. These microgels were composed of cross-linked poly(styrene) and were prepared by radical polymerization in solution. The microgel polymers exhibit good solubility in an array of different organic solvents, and in addition, they can be efficiently precipitated by the addition of methanol and isolated by filtration. A nine-member phthalide library was synthesized using an aminomethyl-functionalized microgel 5. To further demonstrate the versatility of these microgel polymers, tris(2-aminoethyl)amino microgel 11 was examined as a scavenger reagent to remove unreacted isocyanate after a urea synthesis. Finally, a microgel-supported ammonium borohydride reagent 14 was successfully prepared and used as a reducing agent. Notable features of these microgels are that in all applications the progress of the reaction could be monitored by standard NMR techniques and their preparation is performed using common glassware and techniques found in all organic laboratories.     

Radical cascade reaction with 1,4-dienes and 1,4-enynes using 2-(iodomethyl)cyclopropane-1,1-dicarboxylate as a homoallyl radical precursor: one-step synthesis of bicyclo[3.3.0]octane derivatives

[reaction: see text] Radical cascade reaction with various 1,4-dienes and 1,4-enynes using dimethyl 2-(iodomethyl)cyclopropane-1,1-dicarboxylate as a homoallyl radical precursor smoothly proceeds through an iodine atom transfer mechanism to give functionalized bicyclo[3.3.0]octane derivatives in good yields.     

Nucleophilic addition reaction of 2-trimethylsilyloxyfuran to N-gulosyl-C-alkoxymethylnitrones: synthetic approach to polyoxin C

[reaction: see text] The stereoselectivity of nucleophilic addition of 2-trimethylsilyloxyfuran to N-gulosyl-C-alkoxymethylnitrones was investigated. It was found that the selectivity was highly dependent on the bulkiness of the C-substituent of the nitrone. The major adducts were elaborated into the key intermediate of polyoxin C.     

Atomic resolution three-dimensional electron diffraction microscopy

We report the development of a novel form of diffraction-based 3D microscopy to overcome resolution barriers inherent in high-resolution electron microscopy and tomography. By combining coherent electron diffraction with the oversampling phasing method, we show that the 3D structure of a nanocrystal can be determined ab initio at a resolution of 1 A from 29 simulated noisy diffraction patterns. This new form of microscopy can be used to image the 3D structures of nanocrystals and noncrystalline samples, with resolution limited only by the quality of sample diffraction.     

The Effects of Comprehensive Exercise Program on the Adjustments of Standing Balance in Community-Dwelling Elderly Persons

The objective of this study was to assess the effect of comprehensive exercise program widely accepted as a community-based physical intervention for the prevention of falling in the elderly persons on their controlling standing balance. Twenty-six community-dwelling elderly persons (13 males and females; 69.8 ± 2.8 years old) participated in this study. Daily exercise was comprised of walking for more than 30 min, stretching, muscle strengthening and balance exercise without exercise equipments. The intervention was continued for three months. Indicators of standing balance related to static balance, dynamic balance and postural response were measured before and after the intervention. As an effect of the intervention on static balance, the sway of center of pressure (COP) in the static stance significantly increased. In the dynamic balance, significant improvements were observed in one leg standing time, the 10-m gait time, functional reach. Additionally, the maximal movable length of COP which subjects can move voluntarily to right and left significantly increased. In the postural response, the integrated electromyography (IEMG) induced by postural response for sudden postural perturbation significantly decreased in the lower leg muscles. Since less muscular activities were sufficient to maintain posture, it was suggested that postural response was elicited more efficiently following the intervention. This study suggested that the comprehensive exercise program, which has been widely introduced as community-based interventions for the prevention of falling, have extensive effects on the control of standing balance covering static balance, dynamic balance and postural response in the elderly persons.