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121.
Summary The rise process, steady-state and decay process of the birefringence of poly--benzyl-l-glutamate solutions under the action of a rectangular pulse have been studied at 25 °C over a wide range of field strength of 1.5×103 to 3×104V/cm. The solvent used was a dichloroethane-dimethylformamide mixture of the volume ratio 991. From the decay process the average relaxation time extrapolated to zero concentration and the corresponding rotational diffusion constant were determined. The apparent dipole moment and the optical anisotropy factor were obtained from the field strength dependence of steady-state birefringence. The rise process was analyzed according to our theory which holds for arbitrary high field strength in the initial stage. The n(t)/t versus t curves for various field strengths were found to be linear in the initial stage and pass through the origin. Thus, it was concluded that the electrical orientation of poly--benzyl-l-glutamate in solution is due primarily to the permanent dipole moment. Furthermore, the value of the apparent permanent dipole moment obtained from the rise process was compared with that obtained from the steadystate birefringence.
With 7 figures 相似文献
Zusammenfassung Der Einschaltvorgang, der stationäre Zustand und das Abklingen der Doppelbrechung bei Poly--benzyl-l-glutamat-Lösungen mit einem elektrischen Impuls von rechteckiger Form werden bei 25 °C über einem großen Feldstärkebereich von 1.5×103–3×104V/cm untersucht. Als Lösungsmittel wird die Dichloräthan/Dimethylformamid-Mischung im Volumenverhältnis 991 verwendet. Aus dem Abklingvorgang werden die zur Konzentration 0 extrapolierte mittlere Relaxationszeit und die entsprechende Rotationsdiffusionskonstante bestimmt. Das scheinbare permanente Dipolmoment und der optische Anisotropiefaktor werden aus der Feldstärkeabhängigkeit der stationären Doppelbrechung ermittelt. Der Einschaltvorgang wird nach unserer Theorie, die für beliebige hohe Feldstärken im Anfangsverlauf gültig ist, analysiert. Die n(t)/t gegen t-Kurven für verschiedene Feldstärken sind geradlinig im Anfangsverlauf und laufen durch den Ursprung. Hieraus zeigt sich, daß die elektrische Orientierung von Poly--benzyl-l-glutamat in Lösungen hauptsächlich durch das permanente Dipolmoment bedingt ist. Überdies wird der aus dem Einschaltvorgang gewonnene Wert des scheinbaren permanenten Dipolmomentes mit dem aus der stationären Doppelbrechung ermittelten Wert verglichen.
With 7 figures 相似文献
122.
Novel alpha-beta chimeric oligonucleotides bearing a propionic acid derivative of an anthraquinone-polyamine conjugate in the "linker" region sequence-specifically formed a substantially stable alternate-stranded triplex with dsDNA almost regardless of the stereochemistry of the derivative. 相似文献
123.
We propose and demonstrate a limiting procedure in which, starting from the q-lifted version (or K-theoretic five-dimensional version) of the (W)AGT conjecture to be assumed in this paper, the Virasoro/W block is generated in the r-th root of unity limit in q in the 2d side, while the same limit automatically generates the projection of the five-dimensional instanton partition function onto that on the ALE space R4/Zr. This circumvents case-by-case conjectures to be made in a wealth of examples found so far. In the 2d side, we successfully generate the super-Virasoro algebra and the proper screening charge in the q→−1, t→−1 limit, from the defining relation of the q-Virasoro algebra and the q -deformed Heisenberg algebra. The central charge obtained coincides with that of the minimal series carrying odd integers of the N=1 superconformal algebra. In the r-th root of unity limit in q in the 2d side, we give some evidence of the appearance of the parafermion-like currents. Exploiting the q-analysis literatures, q -deformed su(n) block is readily generated both at generic q,t and the r -th root of unity limit. In the 4d side, we derive the proper normalization function for general (n,r) that accomplishes the automatic projection through the limit. 相似文献
124.
Keiichi Murai Lukas Lauterbach Kazuya Teramoto Zhiyang Quan Lena Barra Tsuyoshi Yamamoto Kenichi Nonaka Kazuro Shiomi Makoto Nishiyama Tomohisa Kuzuyama Jeroen S. Dickschat 《Angewandte Chemie (International ed. in English)》2019,58(42):15046-15050
The skeletons of some classes of terpenoids are unusual in that they contain a larger number of Me groups (or their biosynthetic equivalents such as olefinic methylene groups, hydroxymethyl groups, aldehydes, or carboxylic acids and their derivatives) than provided by their oligoprenyl diphosphate precursor. This is sometimes the result of an oxidative ring‐opening reaction at a terpene‐cyclase‐derived molecule containing the regular number of Me group equivalents, as observed for picrotoxan sesquiterpenes. In this study a sesquiterpene cyclase from Trichoderma spp. is described that can convert farnesyl diphosphate (FPP) directly via a remarkable skeletal rearrangement into trichobrasilenol, a new brasilane sesquiterpene with one additional Me group equivalent compared to FPP. A mechanistic hypothesis for the formation of the brasilane skeleton is supported by extensive isotopic labelling studies. 相似文献
125.
Boron complexes surrounded with organic cages were controlled precisely by a remote atom placed at the bottom of the cage. A replacement of the bottom tether atom (carbon or silicon) changed the characteristics (kinetic and thermodynamic factors) of boron complexes by geometric effects. A theoretical study shows that the bottom atoms also control eigenvalues of MO. This cage complex will provide a systematic template for fine-tuning of metal complexes to create various properties. 相似文献
126.
127.
Hideaki Oike Yuka Yoshioka Shinji Kobayashi Megumi Nakashima Yasuyuki Tezuka Eric J. Goethals 《Macromolecular rapid communications》2000,21(17):1185-1190
Mono‐, bis‐, and tris(trifluoromethanesulfonate ester)s ((triflate ester)s) were prepared by the reaction of benzyl alcohol ( 1 ), 1,4‐bis(hydroxymethyl)benzene ( 2 ) and 1,3,5‐tris(hydroxymethyl)benzene ( 3 ) with trifluoromethanesulfonic anhydride in the presence of 2,6‐di‐tert‐butylpyridine. These benzylic triflate esters were applied in‐situ for the living polymerization of tetrahydrofuran (THF). The subsequent end‐capping reaction with a suitable nucleophile proceeded quantitatively to produce mono, bi‐ and, in particular, novel trifunctional telechelic poly(THF)s, respectively. 相似文献
128.
Emako Miyoshi Tomohisa Takaya Katsuyoshi Nishinari Peter A. Williams 《Macromolecular Symposia》1997,120(1):271-280
The interaction between gellan gum (GELL) and konjac glucomannan (KGM) with and without sodium chloride, potassium chloride, calcium chloride and magnesium chloride has been monitored using mechanical spectroscopy and differential scanning calorimetry (DSC). The rheological results indicated that the synergism occurred at sufficient low temperatures where individual helices of GELL molecules were sufficiently aggregated. With progressive addition of monovalent cations, storage shear modulus G' and loss shear modulus G” for mixtures gradually increased, and not only the helix-coil transition temperature of GELL molecules in mixtures but also the sol-gel transition temperature for mixtures shifted to higher temperatures with increasing concentration of salts. Moreover, in the presence of sufficient monovalent cations, mixtures formed an elastic gel with large thermal hysteresis. In the presence of divalent cations, the synergistic interaction was promoted up to a certain concentration, however, with more progressive addition of divalent cations, the main structure formed by aggregates of GELL helices would be smaller, so that mixtures could not form a gel in the presence of excessive divalent cations. DSC results indicated that the intermolecular binding complexes between GELL and KGM molecules would not occur, but KGM markedly influenced the disorder-order transition of GELL molecules. We have suggested that KGM was attached to the surface of large aggregates of GELL helices, and since cations promote GELL self-aggregation by a screening effect, the synergistic interaction between GELL and KGM was promoted with increasing concentration of salts. However, excessive divalent cations formed various aggregates of GELL helices with different thermal stabilities, so that the phase-separation in GELL/KGM mixtures was promoted in the presence of excessive divalent cations. 相似文献
129.
T. Kambara K. Hasegawa H. Yoshioka Y. Kamiya T. Kotani K. Tabei 《Journal of Radioanalytical and Nuclear Chemistry》1977,36(1):87-94
Variations of125Sb valency states in HCl solutions were investigated by the use of the N-benzoyl-N-phenyl-hydroxylamine (BPHA) extraction
method.125Sb(V) is completely reduced to Sb(III) by one hour refluxing in conc. HCl.125Sb(III) is gradually oxidized to Sb(V) in solutions of low HCl concentrations by the effects of their own radiations. Natural
light promotes such oxidation reactions. By utilizing such oxidation-reduction effects125Sb(V) can be easily prepared from125Sb(III) and also125Sb(III) can be prepared by the reduction of Cl
aq
−
. Their valency states were stable on keeping them in brown-colored bottles at 6M HCl concentrations. 相似文献
130.
A linear correlation between the NQR frequency of the terminal iodine atom and the corresponding I-I bond length in I3? was found in several compounds containing triiodide anions. A simple extended Huckel MO calculation suggested that such a correlation can be used to check the validity of wavefunctions of iodine. 相似文献