Observation of Upsilon(4S) decays to pi(+)pi(-)Upsilon(1S) and pi(+)pi(-)Upsilon(2S)

Observation of Upsilon(4S) decays to pi(+)pi(-)C and pi(+)pi(-)Upsilon(2S)We present the first measurement of Upsilon(4S) decays to pi(+)pi(-)Upsilon(1S) based on a sample of 230 x 106(4S) mesons collected with the BABAR detector. We measure the product branching fractions Beta(Upsilon(4S) --> pi(+)pi(-)Upsilon(1S)) x BetaUpsilon(1S) --> mu(+)mu(-) = (2.23 +/- 0.25(stat) +/- 0.27(syst))x 10(-6) and Beta(Upsilon(4S) --> pi(+)pi(-)Upsilon(2S) x Beta(Upsilon(2S) --> mu(+)mu(-))=(1.69 +/-0.26(stat) +/- 0.20(syst)) x 10(-)6, from which we derive the partial widths Gamma(Upsilon(4S) --> pi(+)pi(-)Upsilon(1S))=(1.8 +/-0.4) keV and Gamma(Upsilon(4S) --> pi(+)pi(-)Upsilon(2S))=(2.7 +/- 0.8) keV.     

Copolymerization of ethylene with 1,1‐disubstituted olefins catalyzed by ansa‐(fluorenyl)(cyclododecylamido)dimethyltitanium complexes

A series of titanium complexes with ansa‐(fluorenyl)(cyclododecylamido) ligands, Me₂Si(η³‐R)(N‐c‐C₁₂H₂₃)TiMe₂ [R = fluorenyl ( 5 ), 2,7‐^tBu₂fluorenyl ( 6 ), 3,6‐^tBu₂fluorenyl ( 7 )], was synthesized. The crystal structure of complex 6 revealed η³‐coordination of the fluorenyl moiety to the metal. Upon activation with trialkylaluminum‐free modified methylaluminoxane, complexes 5 – 7 as well as the corresponding ^tBu amide complexes, Me₂Si(η³‐R)(N^tBu)TiMe₂ [R = fluorenyl ( 2 ), 2,7‐^tBu₂fluorenyl ( 3 ), 3,6‐^tBu₂fluorenyl ( 4 )], were adopted as the catalysts for the copolymerization of ethylene (E) and isobutylene (IB). Among these complexes, complex 6 was found to achieve the highest IB incorporation to produce alternating E‐IB copolymers. Complex 6 system also achieved copolymerization of E and limonene. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Development of a New Distyrylbenzene-Derivative Amyloid-β-aggregation and Fibril Formation Inhibitor

Several new amyloid-β (Aβ) aggregation inhibitors were synthesized according to our theory that a hydrophilic moiety could be attached to the Aβ-recognition unit for the purpose of preventing amyloid plaque formation. A distyrylbenzene-derivative, DSB(EEX)(3), which consider the Aβ recognition unit (DSB, 1,4-distyrylbenzene) and expected to bind to amyloid fibrils (β-sheet structure), was combined with the hydrophilic aggregation disrupting element (EEX) (E, Glu; X, 2-(2-(2-aminoethoxy)ethoxy)acetic acid). This DSB(EEX)(3) compound, compared to several others synthesized similarly, was found to be the most active for reducing Aβ toxicity toward IMR-32 human neuroblastoma cells. Moreover, its inhibition of Aβ-aggregation or fibril formation was directly confirmed by transmission electron microscopy and atomic force microscopy. These results suggest that the Aβ aggregation inhibitor DSB(EEX)(3) disrupts clumps of Aβ protein and is a likely candidate for drug development to treat Alzheimer's disease.     

Cyclopropane-based stereochemical diversity-oriented conformational restriction strategy: histamine H3 and/or H4 receptor ligands with the 2,3-methanobutane backbone

The stereochemical diversity-oriented conformational restriction strategy can be an efficient method for developing specific ligands for drug target proteins. To develop potent histamine H(3) and/or H(4) receptor ligands, a series of conformationally restricted analogs of histamine with a chiral trans- or cis-4-amino-2,3-methano-1-(1H-imidazol-4-yl)butane structure was designed based on this strategy. These stereochemically diverse compounds were synthesized from previously developed versatile chiral cyclopropane units. Among these analogs, a trans-cyclopropane-type compound, (2S,3R)-4-(4-chlorobenzylamino)-2,3-methano-1-(1H-imidazol-4-yl)butane (5b), has remarkable antagonistic activity to both the H(3) (K(i) = 4.4 nM) and H(4) (K(i) = 5.5 nM) receptors, and a cis-cyclopropane-type compound, (2R,3R)-4-amino-2,3-methano-1-(1H-imidazol-4-yl)butane (6a), is a potent and selective H(3) receptor partial agonist (K(i) = 5.4 nM). Although (2S,3R)-4-amino-2,3-methano-1-(1H-imidazol-4-yl)butane (5a) does not have a hydrophobic group which the usual H(3) receptor antagonists have, it was found to be a potent H(3) receptor antagonist (K(i) = 20.1 nM). Thus, a variety of compounds with different pharmacological properties depending on the cyclopropane backbones and also on the side-chain functional groups were identified. In addition to the previously used 1,2-methanobutane backbone, the 2,3-methanobutane backbone also worked effectively as a cyclopropane-based conformational restriction structure. Therefore, the combination of these two cyclopropane backbones increases the stereochemical and three-dimensional diversity of compounds in this strategy, which can provide a variety of useful compounds with different pharmacological properties.     

Full-range, complex spatial light modulator for real-time holography

We demonstrate a full-range complex and transmissive spatial light modulator (SLM) for simultaneous and independent amplitude and phase modulation of an input wave field. Arbitrary scalar complex optical fields are generated by stacking a pixelated liquid crystal display operating in phase-only (2π) modulation with passive polarization-sensitive components. The principle is based on optical combining the light fields of two neighboring phase-only modulating pixels, which were made orthogonally polarized by a structured half-wave plate, then passing through a birefringent plate to laterally shift one of the beams collinear to the other, and finally bringing to interference by a linear polarizer. Complex modulation by the proposed SLM is experimentally verified in monochrome green operation.     

Search for the rare decay B0-->tau+tau- at BABAR

We present the results of a search for the decay B0-->tau+tau- in a data sample of (232+/-3)x10(6) Upsilon(4S)-->BB decays using the BABAR detector. Certain extensions of the standard model predict measurable levels of this otherwise rare decay. We reconstruct fully one neutral B meson and seek evidence for the signal decay in the rest of the event. We find no evidence for signal events and obtain Beta(B0->tau+tau-)<4.1x10(-3) at the 90% confidence level.     

Determinations of from inclusive semileptonic decays with reduced model dependence

We report two novel determinations of /|Vub/ with reduced model dependence, based on measurements of the mass distribution of the hadronic system in semileptonic B decays. Events are selected by fully reconstructing the decay of one B meson and identifying a charged lepton from the decay of the other B meson from Upsilon(4S)-->BB events. In one approach, we combine the inclusive B-->Xulambdav rate, integrated up to a maximum hadronic mass mX<1.67 GeV/c2, with a measurement of the inclusive B-->Xsgamma photon energy spectrum. We obtain /Vub/=(4.43+/-0.38stat+/-0.25syst+/-0.29theo) x 10-3. In another approach we measure the total B-->Xulambdav rate over the full phase space and find /Vub/=(3.84+/-0.70stat+/-0.30syst+/-0.10theo) x 10-3.     

NBO‐based CI/MP through‐space/bond interaction analysis and its application to stereoelectronic effects in SN2 reactions

NBO‐based CI/MP through‐space/bond interaction analysis was developed to analyze specific orbital interactions under consideration of the effects of electron correlation. This treatment was applied to the analysis of stereoelectronic effects in S_N2 reactions of allyl bromide in which the effects of electron correlation play an important role (ammonia was used as the nucleophilic reagent). The S_N2 activation energy in allyl bromide is lower than that in propyl bromide, because both the σ–π* and π–σ* interactions in allyl bromide contribute equally to the stabilization of the transition state. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Theoretical study on static (hyper)polarizabilities for polyimide by the elongation finite-field method

The elongation finite-field method is applied to calculate (hyper)polarizabilities of polyimides PMDA/DMDB, PMDA/ODA, and PMDA/TFDB. The nonlinear optical (NLO) properties of planar structures of three polyimides are compared to those of their twist structures. It is found that all α and γ values of the planar structures are larger than the corresponding values of the twist structures, which may be attributed to the fact that π-conjugation of twist structures is decreased compared with the planar structures. All β values of planar and twist structures oscillate regularly along with elongating the chain. Moreover, effect of two side-groups –CH₃ and –CF₃ on the NLO properties of PMDA/DMDB and PMDA/TFDB is investigated.     

Observation of e(+)e(-) annihilation into the C = +1 hadronic final states rho(0)rho(0) and phirho(0)

We report the first observation of e(+)e(-) annihilation into states of positive C parity, namely, rho(0)rho(0) and phirho(0). The two states are observed in the pi(+)pi(-)pi(+)pi(-) and K(+)K(-)pi(+)pi(-) final states, respectively, in a data sample of 225 fb(-1) collected by the BABAR experiment at the Positron-Electron Project II e(+)e(-) storage rings at energies near sqrt[s]=10.58 GeV. The distributions of costheta(*), where theta(*) is the center-of-mass polar angle of the phi meson or the forward rho(0) meson, suggest production by two-virtual-photon annihilation. We measure cross sections within the range |costheta(*)|<0.8 of sigma(e(+)e(-)-->rho(0)rho(0))=20.7+/-0.7(stat)+/-2.7(syst) fb and sigma(e(+)e(-)-->phirho(0))=5.7+/-0.5(stat)+/-0.8(syst) fb.