An OFF-ON fluorescent probe for Zn2+ based on a GFP-inspired imidazolone derivative attached to a 1,10-phenanthroline moiety

A green fluorescent protein chromophore inspired chemosenor for Zn(2+) was designed and synthesized. A Zn(2+) specific fluorescence enhancement was observed due to restricted rotation between the 1,10-phenanthroline and imidazolone moieties.     

1,1-carboboration of 1-alkynes: a conceptual alternative to the hydroboration reaction

Strongly electrophilic boranes R-B(C(6)F(5))(2) react readily with a variety of 1-alkynes by means of a 1,1-carboboration reaction to yield alkenylborane products, which can subsequently be used as reagents in metal catalyzed cross-coupling reactions.     

An efficient approach for monofluorination via aqueous fluorolactonization reaction of 2,3-allenoic acids with selectfluor

We have developed a convenient method for the efficient monofluorination via the electrophilic fluorocyclization reaction of 2,3-allenoic acids with Selectfluor in MeCN in the presence of 10 equiv of H2O or even in pure water to afford beta-fluorobutenolides in moderate to high yields.     

Magnetic fields of 10mT and 120mT change cell shape and structure of F-actins of periodontal ligament cells

Dental magnetic attachments, usually applied locally to oral cavities, produce stray fields (flux leakage) spreading in adjacent tissues. It has been found that human periodontal ligament (PDL) cells change their geometry and the structure of their cytoskeleton F-actins when the cell cultures are exposed to B-field strengths of B = 10mT and 120mT, respectively, which are similar to those generated by dental magnetic attachments. Analytically, after long-time exposures to B-fields for 12h, 36 h and 60 h, respectively, cytoskeleton F-actins are labeled with a fluorescent dye and observed under a laser scanning confocal microscope. The geometrical cell parameters of cell length and cell width and the fluorescence emission of labeled F-actins, respectively, were determined and subjected to an automatic image analysis using a special software. The results on cell shrinkage and filament reorganizations were statistically analyzed by the program ANOVA (P < 0.05). It was found that only long-time (hours) exposure to high fields in the order of 0.1T may produce tissue irritations during long-time medical treatments using open- and closed-field dental magnetic attachments.     

An alternative multipolar expansion for intermolecular potential functions

We have derived a new multipolar expansion for intermolecular potential-energy functions with applications in molecular physics, theoretical chemistry, and mathematical physics. The new formulation employs a separation of radial and angular terms with a simple index structure that leads to computational efficiency and ease of physical interpretation. For the case of the Coulomb interaction, we compare the present formulation with two conventional multipole expansions: the Cartesian tensor and the irreducible spherical tensor expansions. The new formalism leads to efficient numerical algorithms that are useful for general applications beyond intermolecular potentials. In addition to the electrostatic Coulomb interaction, we illustrate the formalism with applications to special function theory and a bipolar expansion involved in potential theory.     

Azimuthal symmetry, flow dynamics, and heat transport in turbulent thermal convection in a cylinder with an aspect ratio of 0.5

We report an experimental study of flow dynamics and structure in turbulent thermal convection. Flow visualization, together with particle image velocimetry (PIV) measurement, reveal that the instantaneous flow structure consists of an elliptical circulatory roll and two smaller counterrotating rolls, and that the azimuthal motion of the quasi-2D instantaneous flow structure produces a time-averaged 3D flow pattern featuring two toroidal rings near the top and bottom plates, respectively. The apparently stochastic azimuthal motion of the flow structure, which generates a net rotation on average, is found to possess the characters of a Brownian ratchet. Using an artificially generated flow mode, we are able to produce a bimodal-Nu behavior and thus demonstrate that different flow states can indeed produce different global heat transport in a turbulent convection system.     

A crisis of a stochastic web

In a kicked rotor subjected to a piecewise-continuous force field, it is observed that a stochastic web and the chaotic diffusion on it suddenly change to transients when an adjustable parameter drives the dissipation. This phenomenon appears to be a new crisis type, which occurs in systems where conservative dynamics may be converted to a dissipative one with a contraction rate showing linear time dependence. It is analytically and numerically shown that, in the crisis, the lifetime dependence obeys universal scaling law suggested by Grebogy, Ott, and Yorke [Phys. Rev. Lett. 57, 1284 (1986)], and the scaling exponent takes a special value, 1, due to the dissipation characteristics. Additionally presented is another power law that describes, from another viewpoint, the transition of a conservative stochastic web (which is a fat fractal) to a non-attracting thin fractal (the strange repeller).Received: 13 December 2003, Published online: 9 March 2004PACS: 05.45.Ac Low-dimensional chaos     

Observation of radiative B-->phi K gamma decays

The radiative decay B-->phi K gamma is observed for the first time. The branching fraction for the charged B--->phi K- gamma decay mode is measured to be B(B--->phi K- gamma)=(3.4+/-0.9+/-0.4)x10(-6). The photon energy distribution for the B--->phi K- gamma decay is presented. The signal for the neutral B(0)-->phi K(0)gamma decay mode is not statistically significant and an upper limit, B(B(0)-->phi K(0)gamma)<8.3x10(-6) at 90% C.L., is set. The analysis is based on a data set of 90 fb(-1) collected by the Belle experiment at the e(+)e(-) asymmetric collider KEKB.     

An unprecedented fivefold interpenetrated lvt network containing the exceptional racemic motifs originated from nine interwoven helices

An unprecedented fivefold interpenetrated lvt network, containing the rare racemic motifs originated from nine interwoven helices, is reported, which represents the highest degree of interpenetration presently known for 3D nets containing only planar four-coordinate nodes.