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  • 1
    Publication Date: 2016-06-08
    Description: Author(s): Yusuke Wakabayashi, Daisuke Nakajima, Yuki Ishiguro, Kenta Kimura, Tsuyoshi Kimura, Satoshi Tsutsui, Alfred Q. R. Baron, Kouichi Hayashi, Naohisa Happo, Shinya Hosokawa, Kenji Ohwada, and Satoru Nakatsuji Structural fluctuation in Ba 3 CuSb 2 O 9 , which is proposed to exhibit a spin-orbital entangled state, has been studied by diffuse x-ray scattering, x-ray fluorescence holography, and inelastic x-ray scattering. Two kinds of spatial fluctuations are observed: temperature-independent and temperature-depe… [Phys. Rev. B 93, 245117] Published Tue Jun 07, 2016
    Keywords: Electronic structure and strongly correlated systems
    Print ISSN: 1098-0121
    Electronic ISSN: 1095-3795
    Topics: Physics
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  • 2
    Publication Date: 2017-06-06
    Description: Author(s): Takuya Aoyama, Yoshinao Hasegawa, Shojiro Kimura, Tsuyoshi Kimura, and Kenya Ohgushi The magnetoelectric coupling in possible Kitaev spin liquid α − RuCl 3 with the layered honeycomb structure was examined. We observed a remarkable anisotropic magnetodielectric effect in the zigzag-type antiferromagnetic phase; there is a large suppression in dielectric constant, when both electric and… [Phys. Rev. B 95, 245104] Published Mon Jun 05, 2017
    Keywords: Electronic structure and strongly correlated systems
    Print ISSN: 1098-0121
    Electronic ISSN: 1095-3795
    Topics: Physics
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  • 3
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Blockcopoly(ester-ether) mit verschiedenen ionischen Einheiten wie Sulfobetain (S-Betain), Carbobetain (C-Betain) und Ammoniumtosylat wurden hergestellt und hinsichtlich ihrer Eignung als antistatische Modifikatoren für Polyethylenterephthalat (PET)-Fasern untersucht. Die ionischen Segmente wurden aus N,N-Bis(2-hydroxyethyl)methylamin generiert und statistisch mit den Polyester- und Polyoxyethylen(PEO)-Einheiten cokondensiert. Aus den Copolymeren mit S-Betain-Einheiten wurden im Schmelzspinnverfahren dicke Filamente hergestellt und deren elektrischer Widerstand bestimmt. Abhängig von der Zusammensetzung (25-75 Gew.-% PEO, 1-2 mol-% S-Betain) wurden Widerstände zwischen 108 und 1010 Ω cm-1 gemessen. Die drei copolymerartigen Modifikatoren wurden mit PET durch Blendspinnen gemischt. Die so erhaltenen PET-Fasem zeigen nicht nur gute mechanische sondern auch verbesserte antistatische Eigenschaften. Die Fasern aus dem S-Betain enthaltenden Copolymeren weisen dabei die kürzeste Halbwertszeit des Abbaus der elektrostatischen Ladung auf, obwohl der Oberflächenwiderstand dieses Materials in der Größenordnung 1013 Ω cm-2 dem Wert der mit C-Betain und Ammoniumtosylat hergestellten Fasem ähnlich ist. Die PET-Fasern bewahren ihre guten antistatischen Eigenschften auch nach dem Fäben und wiederholtem Waschen, da sowohl die hydrophilen als auch die ionischen Gruppen an den Polyesterketten fixiert sind.
    Notes: Block copoly(ester-ether)s containing different ionic units, i.e., sulfobetaine (S-betaine), carbobetaine (C-betaine), and ammonium tosylate, were prepared and evaluated as antistatic modifiers of PET fiber. The ionic units were readily derived from N,N-bis(2-hydroxyethyl)methylamine and co-condensed randomly with the polyester and poly(oxyethylene) (PEO) units. For the copolymers containing S-betaine units, a thick filament was melt-spun to evaluate their apparent electric resistivity. Depending on the unit compositions (25-75 wt.-% of PEO and 1-2 mol-% of S-betaine), resistivities ranging from 108 to 1010 Ω cm-1 were obtained. Then, the three copolymer-type modifiers were blended with poly(ethylene terephthalate) (PET) by the ordinary blend-spinning technique. The blend PET fibers obtained showed not only good mechanical properties, but also improved antistatic properties. Particularly, the fiber blended with the copolymer containing S-betaine units had the shortest half-life time of leakage of static charge, although the surface area resistivity, being in the order of 1013 Ω cm-2, was similar to that of the fibers blended with the copolymers containing C-betaine and ammonium tosylate units. These blend PET fibers were found to retain good antistatic properties even after dyeing and repeated washings, because both the hydrophilic and ionic groups are immobilized with the polyester chains.
    Additional Material: 3 Tab.
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  • 4
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Copoly (amid-ether) rnit zwei unteschiedlichen Aminfunktionalitäten wurden als antistatische Modifikatoren für Polyethylenterephthalatfasern (PET) eingesetzt. Die tertiären Aminogruppen schmelzegesponnener Copolymerfilamente wurden rnit drei Alkylierungsmitteln umgesetzt, wobei ein Sulfobetain, ein Carbobetain bzw. Ammoniumionen gebildet wurden. Dadurch wurde der scheinbare spezifische Widerstand der Filamente auf größfienordnungsmäßfiig 106 bis 108 Ω/cm verringert. Da sich die quaternisierten Copolymeren beim Blend-Spinnen rnit PET zersetzen, wurden Blendfasern von PET mit einem Copolymeren nach dem Schmelzespinnen einer Quaternisierung oder Vernetzung rnit Alkylierungsmitteln bzw. Epoxyvernetzern unterzogen, was die antistatischen Eigenschaften der Fasern im Vergleich rnit der unbehandelten Faser verbesserte. Insbesondere die mit Epoxiden vernetzten Fasern wiesen antistatische Eigenschaften auf, wie sie mit dieser Modifizierungsmethode bislang nicht erreicht wurden. Die antistatischen Eigenschaften blieben nach dem Fkben erhalten, da sowohl die hydrophilen als auch die ionischen Gruppen auf der Faseroberflache immobilisiert waren. Da Quaternisierung bzw. Vernetzung in einem Arbeitsgang rnit dem Verspinnen und Verstrecken der Fasern innerhalb einer kurzen Reaktionszeit erfolgen, sollte diese “spin-finishing„ genannte Methode konventio- nellen Verfahren bezuglich Kosten und Produktivitat uberlegen sein.
    Notes: Copoly(amide-ethers) containing two types of tertiary amine units were made as antistatic modifiers for poly(ethylene terephthalate) (PET) fibers. The filaments of the copolymers were melt-spun and reacted with three alkylating agents in order to quaternize the tertiary amine into a sulfo-betaine, a carbobetaine, and an ammonium ion. The apparent electric resistivity of the filaments was greatly reduced by this reaction, being in the range of 106 to 108 Ω/cm. However, because these quaternized copolymers incurred decomposition during blend spinning with PET, a blend PET fiber containing one type of copoly(amide-ether) was melt-spun and subjected to quaternization of the amino groups as well as to surface crosslinking with various alkylating and epoxy agents. The quaternized blend fibers obtained showed improved antistatic properties compared with the original blend fiber. Particularly, the fibers crosslinked with epoxy compounds were found to have the best antistatic properties that had ever been attained with this type of modification. The antistatic properties were retained even after dyeing, because both hydrophilic and ionic groups had been effectively immobilized on the surface. Since this quaternization and crosslinking could be conducted on-line with spinning and drawing within a short reaction time, this modification technique is called “spin-finishing method”, which should be superior to the conventional methods in terms of cost performance and productivity.
    Additional Material: 4 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 28 (1989), S. 1235-1246 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclic octapeptides having alternating Sar and hydrophobic amino acid sequences, such as cyclo[Lys(Z)-Sar-Leu-Sar-Leu-Sar-Leu-Sar] (C8KL), cyclo[Glu(OMe)-Sar-Lys(Z)-Sar-Leu-Sar-Leu-Sar] (C8KE), and cyclo[Lys(Suc)-Sar-Leu-Sar-Leu-Sar-Leu-Sar][C8K(Suc)L, Suc represents succinic acid], were synthesized. These cyclic octapeptides formed a complex selectively with Ca2+. Upon complexation, trans peptide bonds of Sar residues were isomerized to cis peptide bonds. C8KL and C8KE showed very similar characteristics of Ca2+ binding, extraction of Ca2- from an aqueous solution to a chloroform solution, and Ca2+ transport through a liquid chloroform membrane. C8KL transported Ca2+ across the lipid bilayer membrane above the phase-transition temperature, while C8KE and C8K(Suc)L did not. Therefore, the transport of Ca2+ through the lipid bilayer membrane is very sensitive to the hydrophobicity of the carrier molecule.
    Additional Material: 10 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 217 (1994), S. 129-137 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Carboxy-terminierte Polyoxyethylene (PEO-acid) mit zahlenmittleren Molekulargewichten Mn = 8400, 3300 und 1000 wurden zur antielektrostatischen Modifizierung von Polyethylenterephthalat (PET) verwendet. Fasern aus PET-PEO-acid-Blends mit 2,0 oder 5,0 Gew.-% PEO-acid wurden bei 285°C mit einem normalen Extruder aus der Schmelze gesponnen und anschließend bei 80°C um das ca. 4,5fache verstreckt. Die Verarbeitbarkeit beim Verspinnen und Verstrecken war bei Verwendung von PEO-acid mit hohen Molekulargewichten ausgezeichnet. Die anti-elektrostatischen Eigenschaften wurden ebenfalls mit steigendem PEO-acid-Molekulargewicht besser. Da eine Umesterung beim Verspinnen nur in geringem Ausmaß stattfand, blieben die mechanischen Eigenschaften der Blend-Fasern gegenüber den PET-Fasern nahezu unverändert.
    Notes: Carboxy-terminated poly(oxyethylenes) (PEO-acid) with number-average molecular weights Mn = 8400, 3300, and 1000 were used for antielectrostatic modification of poly(ethylene terephthalate) (PET). The blend PET fibers containing 2.0 and 5.0 wt.-% of PEO-acids were melt-spun at 285°C with an ordinary extruder and then drawn about 4.5-fold at 80°C. The processabilities of spinning and drawing were excellent at higher molecular weights of PEO-acid. The anti-electrostatic properties of the blend fibers became also improved with increasing molecular weight of PEO-acid. Since little ester interchange reaction took place between PET and PEO-acid during meltspinning, the blend fibers could retain almost the same mechanical properties as the original PET fiber.
    Additional Material: 4 Tab.
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  • 7
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A strategy suitable for the synthesis of larger peptides is proposed. It involves the following four considerations: (1) all of the side-chain functional groups are protected by benzyl-type protective groups; (2) a water-soluble carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide, is used for the fragment-condensation reactions together with 1-hydroxybenzotriazole as the additive; (3) all the protective groups are cleaved simultaneously by the HF method in the final stage of the synthesis; and (4) side products formed are detected and removed by an efficient high-performance liquid chromatography procedure. The usefulness of these procedures is demonstrated taking the synthesis of human parathyroid hormone [hPTH(1-84)] as an example.
    Additional Material: 8 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 2191-2206 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclic octapeptides, cyclo(X-Pro)4, where X represents Phe, Leu, or Lys(Z), were synthesized and their conformations investigated. A C2-symmetric conformer containing two cis peptide bonds was found in all of these cyclic octapeptides. The numbers of available conformations due to the cis-trans isomerization of Pro peptide bonds depended on the nature of the solvent and X residue: they decreased in the following order: cyclo[Lys(Z)-Pro]4 〉 cyclo(Leu-Pro)4 〉 cyclo(Phe-Pro)4 in CDCl3. 13C spin-lattice relaxation times (T1) of these cyclic octapeptides were measured, and the contribution of segmental mobility to T1 was found to vary with the nature of the X residue.
    Additional Material: 12 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 23-38 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A general method is presented for computing the atomic coordinates of helices in which a dipeptide is the repeating unit. The method will generate both single- and double-stranded model helices having idealized bond lengths and angles, and any arbitrary, user-specified, pitch and number of residues per turn. The variation of inter- and intrastrand hydrogen bonds with pitch and number of residues per turn can thus be examined. An application of the method is the construction of a β-helix having pitch of 6.3 Å per turn and 4.85 residues per turn, a model which can pack nicely into the unit cell of crystals of cation-bound gramicidin A.
    Additional Material: 9 Ill.
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  • 10
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Neurotoxic peptides from venoms of scorpions and honey bees exhibit a consensus pattern in the two disulfide bridgings related to the sequence portions Cys-X-Cys and Cys-X-X-X-Cys. A revised three-dimensional structure of charybdotoxin, as determined by two-dimensional nmr spectroscopy, confirms that the consensus cystine dislocation generates in all these toxins a common structural element, i.e., the cystine-stabilized α-helical (CSH) motif, which may be correlated with their common ion channel blocking activity.
    Additional Material: 5 Ill.
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