Solid-state 2H NMR structure of retinal in metarhodopsin I

The structural and photochemical changes in rhodopsin due to absorption of light are crucial for understanding the process of visual signaling. We investigated the structure of trans-retinal in the metarhodopsin I photointermediate (MI), where the retinylidene cofactor functions as an antagonist. Rhodopsin was regenerated using retinal that was (2)H-labeled at the C5, C9, or C13 methyl groups and was reconstituted with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine. Membranes were aligned by isopotential centrifugation, and rhodopsin in the supported bilayers was then bleached and cryotrapped in the MI state. Solid-state (2)H NMR spectra of oriented rhodopsin in the low-temperature lipid gel state were analyzed in terms of a static uniaxial distribution (Nevzorov, A. A.; Moltke, S.; Heyn, M. P.; Brown, M. F. J. Am. Chem. Soc. 1999, 121, 7636-7643). The line shape analysis allowed us to obtain the methyl bond orientations relative to the membrane normal in the presence of substantial alignment disorder (mosaic spread). Relative orientations of the methyl groups were used to calculate effective torsional angles between the three different planes that represent the polyene chain and the beta-ionone ring of retinal. Assuming a three-plane model, a less distorted structure was found for retinal in MI compared to the dark state. Our results are pertinent to how photonic energy is channeled within the protein to allow the strained retinal conformation to relax, thereby forming the activated state of the receptor.     

Theoretical investigation of the stability of highly charged C60 molecules produced with intense near-infrared laser pulses

We theoretically investigated the stability of highly charged C(60) (z+) cations produced from C(60) with an ultrashort intense laser pulse of lambda approximately 1800 nm. We first calculated the equilibrium structures and vibrational frequencies of C(60) (z+) as well as C(60). We then calculated key energies relevant to dissociation of C(60) (z+), such as the excess vibrational energy acquired upon sudden tunnel ionization from C(60). By comparing the magnitudes of the calculated energies, we found that C(60) (z+) cations up to z approximately 12 can be produced as a stable or quasistable (microsecond-order lifetime) intact parent cation, in agreement with the recent experimental report by V. R. Bhardwaj et al. [Phys. Rev. Lett. 93, 043001 (2004)] that almost only intact parent C(60) (z+) cations up to z=12 are detected by a mass spectrometer. The results of Rice-Ramsperger-Kassel-Marcus calculation suggest that the lifetime of C(60) (z+) drastically decreases by ten orders of magnitude as z increases from z=11 to z=13. Using the time-dependent adiabatic state approach, we also investigated the vibrational excitation of C(60) and C(60) (z+) by an intense near-infrared pulse. The results indicate that large-amplitude vibration with energy of >10 eV is induced in the delocalized h(g)(1)-like mode of C(60) (z+).     

Coaxial holographic data storage without recording the dc components

A technique of recovering the data pages from Fourier holograms recorded without the dc components is demonstrated theoretically and experimentally by use of a coaxial holographic storage system. A reconstructed image is obtained by adding a phase-modulated dc component of the signal beam on reading. The bit error rate of the reconstructed image is comparable with that for the hologram recorded with the dc component as well. Since high intensities of the dc components are not recorded in this technique, the dynamic range of the recording media can be saved, which potentially contributes to increasing the number of multiplexed holograms.     

A practical preparation of highly versatile N-acylpyrroles from 2,4,4-trimethoxybutan-1-amine

A novel method for the preparation of N-acylpyrrole is described. The method involves condensation of carboxylic acids with 2,4,4-trimethoxybutan-1-amine, followed by acid-mediated cyclization to form the pyrrole ring. The preparative procedure is highly tolerant of a variety of functional groups.     

Recent progress in environmental catalytic technology

Recent progress and trends in environmental catalytic technology in Japan are described with emphasis on the catalysts having hybridized functions. In addition to automobile exhaust cleaning, use of environmental catalysts such as titanium oxide photocatalysts is rapidly growing for the control of residential environments, e.g., antimicrobial activity and odor control, as life styles change gradually and the living environment is deteriorating considerably. Many new catalysts are evolving through hybridization of functions. The market of environmental catalyst products in 2005 is estimated 2,000 billion yen/year (photocatalyst: 1,100 billion yen/year).     

并二苯环纳米分子桥的电子传导特性

An two-electrode molecular bridge model that consists of two benzene rings was presented. The characteristics of electronic transport through the nano-molecular bridge was investigated theoretically by using the tight binding approach based on the Green’s function with only one π orbital per carbon atom at the site. Electronic transport probabilities through the molecular bridge from the input to the output terminal were obtained. The electronic current distributions inside the molecular bridge were calculated and shown in graphical analogy by the current density method based on Fisher-Lee formula at the energy points E=±0.68 and E=±1.38 where the peaks of transport probabilities appeared, and the maximum bond electronic current was also presented. The reason why the loop current in the benzene ring is induced by the phase difference within the molecular orbits is explained.     

Modified offensive earned-run average with steal effect for baseball

This short article introduces and studies a modified offensive earned-run average (MOERA) index which is based on a stationary Markov chain and evaluates the contribution of a player in baseball. An original offensive earned-run average (OERA) index does not consider the effect of stealing. The MOERA index proposed here includes the effect. Some examples are presented for Japanese professional baseball players.     

Mechanochromic Delayed Fluorescence Switching in Propeller-Shaped Carbazole–Isophthalonitrile Luminogens with Stimuli-Responsive Intramolecular Charge-Transfer Excited States

Herein, the universal design of high-efficiency stimuli-responsive luminous materials endowed with mechanochromic luminescence (MCL) and thermally activated delayed fluorescence (TADF) functions is reported. The origin of the unique stimuli-triggered TADF switching for a series of carbazole–isophthalonitrile-based donor–acceptor (D–A) luminogens is demonstrated based on systematic photophysical and X-ray analysis, coupled with theoretical calculations. It was revealed that a tiny alteration of the intramolecular D–A twisting in the excited-state structures governed by the solid morphologies is responsible for this dynamic TADF switching behavior. This concept is applicable to the fabrication of bicolor emissive organic light-emitting diodes using a single TADF emitter.     

Hydrogen-induced magnetic and structural transformations of GdCu

The magnetization of GdCu induced by hydrogen uptake was measured within the temperature range of 4.2 to 300 K, occurring phase changes were followed by X-ray diffraction measurements at ambient temperature. The prepared GdCu powder of CsCl-type structure readily absorbed hydrogen at ambient temperature, where hydrogen pressure was below 100 kPa. Hydrogenation changed the magnetism of GdCu in a complex manner from an antiferromagnetic-like type to a paramagnetic-like one. The changes in magnetic properties of GdCu by hydrogenation are governed by hydrogen-induced disproportionation. Within the composition range 0<[H]/[GdCu]<1, GdCu disproportionated according to 2GdCu+H₂→GdH₂+GdCu₂ . The magnetization was evaluated by the expression χ_total=(1-x)χ_GdCu+(x/2)(χ_GdH2+χ_GdCu2). GdCu hydride was not observed. Hydrogenation beyond [H]/[GdCu]>1 gave rise to the disproportionation of GdCu₂ causing the change in magnetization.     

Furopyridines. XXIII. Synthesis and reactions of chloropyridine derivatives of furo[2,3-b]-, -[2,3-c]- and -[3,2-c]pyridine

Chlorination of the N-oxides of furo[2,3-b]- 1a , -[2,3-c]- 1b and -[3,2-c]pyridine 1c with phosphorus oxychloride afforded compounds substituted normally at the α- or λ-position to the ring nitrogen, 2a, 2′a, 2b, 2c, 2′c and 2′c , and in addition, in the case of 1b , compounds substituted on the furan ring, 2′b and 2″b . The structures of these compounds were confirmed from their ir, nmr and mass spectra. The major chlorinated products 2a, 2b and 2c were converted to methoxy- 5a, 5b and 5c , N-pyrrolidyl- 7a, 7b and 7c , and phenylthiofuropyridines 8a, 8b , and 8c .