Structural analysis of three-spin systems of photosystem II by PELDOR

The pulsed electron electron double resonance (PELDOR) pulse sequence is applied to a three-spin system consisting of three radicals (Y _D ^· , Y _Z ^· and Q _A ^? ) generated in spinach PS II. The distance between Y_Z and Q_A has been determined to be 3.4 nm with the previously derived distances of the other radical pairs, 2.9 nm for Y _D ^· -Y _Z ^· and 3.9 nm for Y _D ^· -Q _A ^? . This distance has been derived from the Y _Z ^· -Q _A ^? radical pair trapped in Y_D-less mutants ofChlamydomonas reinhardtii. Furthermore the method was applied to the Y _D ^· -Q _A ^? -Chl _Z ⁺ system to find the unknown distance between Q_A and Chl_Z. The derived distance was 3.4 nm. A triangular configuration was found in the membrane system that gives the relative positions of the electron transfer components.     

Ultrasonic imaging using air-coupled P(VDF/TrFE) transducers at 2 MHz

A reflection non-contact ultrasonic microscope system working both in amplitude and phase difference modes at 2 MHz has been developed using an air-coupled concave transducer made of piezoelectric polymer films of poly(vinylidene fluoride/trifluoroethylene) [P(VDF/TrFE)]. The transducer is composed of three 95 μm-thick P(VDF/TrFE) films stacked together, each of which is activated electrically in parallel by a driving source. The transducer has a wide aperture angle of 140° and a focal length of 10 mm. The measured two-way transducer insertion loss is 80 dB at 1.83 MHz. Despite 20 dB higher insertion loss than that estimated from Mason’s equivalent circuit, we have obtained clear amplitude acoustic images of a coin with transverse resolution of 150 μm, and clear phase difference acoustic images of the rough surface of a paper currency bill with depth resolution of sub-micrometer. Using two planar transducers of P(VDF/TrFE), we have also successfully measured in through-transmission mode the sound velocity and absorption of a 3 mm-thick silicone-rubber plate. The present study proves that, owing to its low acoustic impedance and flexibility, P(VDF/TrFE) piezoelectric film is very useful for high frequency acoustic imaging in air in the MHz range.     

Studies on micelles

Summary It is shown by the absorption intensity that the micellar volume increases continuously from the CMC in wider surfactant concentration range. Considering many experimental results reported, is presented the model of constant particle concentration above the CMC for the aqueous micellar solutions as the first approximation. The qualitative reasons to present this model are mentioned.

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Zusammenfassung Die Absorption weist darauf hin, da? das Mizellvolumen von der CMC in weitem Konzentrationsbereich grenzfl?chenaktiver Substanzen ansteigt. Aus vielen gegebenen Versuchsdaten wird ein Modell konstanter Partikelkonzentration oberhalb der CMC in gleichmizellaren L?sungen als erste N?herung gefolgert. Die qualitativen Gründe für ein solches Modell sind genannt.

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Series IV.Sata, N. andH. Sasaki, Kolloid-Z.153, 41 (1957).

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The author wishes to thank Prof.N. Sata for his encouragement and discussion and Dr.H. Okuyama for general discussion and also the author is indebted to Mr.S. Saito for the purification of octadecyl trimethyl ammonium chloride and to Mr.S. Fukushima for the discussion about stray light.     

Two new alkaloids from Crinum asiaticum var. sinicum

Two new alkaloids (1, 2) were isolated from the whole plants of Crinum asiaticum var. sinicum together with seven known alkaloids. The structures of the new alkaloids were elucidated by spectroscopic analyses and chemical conversions from known alkaloids. New alkaloid 1 was isolated for the first time as a natural product, although it has been prepared as a synthetic product.     

Synthesis of pentacene-, tetracene- and anthracene bisimides using double-cyclization reaction mediated by bismuth(III) triflate

Novel bisimide-fused acenes were synthesized via bismuth triflate mediated double-cyclization reaction of acid chlorides and isocyanates. Their optical and electrical properties revealed significantly smaller HOMO-LUMO gaps compared with those of their parent acenes. Fabricated OFET based on tetracene bisimide showed n-type OFET outputs.     

Living Cationic Polymerization Toward Macromolecular Design: Synthesis of End-Functional Multiarmed Polymers

A series of multiarmed polymers with terminal functional groups have been synthesized on the basis of living cationic polymerizations of vinyl ethers and p-alkoxystyrenes. The syntheses were performed by two methods, one via living polymerizations with new multifunctional initiating systems followed by endcapping of the resultant multifunctional living polymers, and the other using designed silyl enol ethers as multifunctional terminators (coupling agents) that combine two to four end- functionalized linear living polymers. These two methodologies thus led to telechelic and 3- or 4-arm star polymers and macromonomers with hydroxyl, acetate, methacrylate, and styryl end functionalities.     

Ion-pair formation between Cd(II), Na(I), and Ag(I) complex ions with 18-crown-6 ether derivatives and various pairing anions in water: an understanding of the ion-pair formation based on the HSAB principle

The ion-pair formation constants (K(MLX)(0)/mol(-1) dm(3)) of CdL(2+) with Br(-) or NaL(+) with N,N-diethyldithiocarbamate ion (DDTC(-)) in water were determined potentiometrically at 25°C; ionic strength (I)→0: L denotes 18-crown-6 ether (18C6) and its mono-benzo derivative for the CdBr(2)-L system and 15-crown-5 ether and 18C6 for the NaDDTC-L one. The formation constant corresponding to the simple salt, NaDDTC, in water was also determined at I→0. Using the log K(CdLX)(0) values of CdLCl(+), CdLBr(+), CdLPic(+), and CdLSO(4), then CdL(2+) and picrate ion (Pic(-)) in water have been classified with the hard and soft acids and bases principle, where the values were available in the literature, except for CdLBr(+). The same classification was examined in NaX-L systems with X(-) = DDTC(-), trifluoroacetate ion, MnO(4)(-), ReO(4)(-), Pic(-), and BPh(4)(-) and the AgPic-L one. Consequently, CdL(2+), NaL(+), and AgL(+) were classified as the hard acids, while Pic(-) and BPh(4)(-) as the hard bases. These results reflected the reactivities of the complex ions in ion-pair formation with X(-) and SO(4)(2-) in water.     

Synthesis and stereochemistry of JBIR-81, a peptide enamide derived from aspergilli

The absolute stereochemistry of an aspergilli-derived peptide enamide, JBIR-81, was determined to be 12S, 15S by the first synthesis of (12S,15S)-JBIR-81 and its epimer. The overall yield was 56% over six steps from N-methyl-l-leucine. The (Z)-enamide structure was effectively constructed with use of a copper (I) catalyzed coupling reaction between a vinyl halide and a carboxamide.