Sum-rules and Goldstone modes from extended random phase approximation theories in Fermi systems with spontaneously broken symmetries

The Self-Consistent RPA (SCRPA) approach is elaborated for cases with a continuouslybroken symmetry, this being the main focus of the present article. Correlations beyondstandard RPA are summed up correcting for the quasi-boson approximation in standard RPA.Desirable properties of standard RPA such as fulfillment of energy weighted sum rule andappearance of Goldstone (zero) modes are kept. We show theoretically and, for a modelcase, numerically that, indeed, SCRPA maintains all properties of standard RPA forpractically all situations of spontaneously broken symmetries. A simpler approximate formof SCRPA, the so-called renormalised RPA, also has these properties. The SCRPA equationsare first outlined as an eigenvalue problem, but it is also shown how an equivalent manybody Green’s function approach can be formulated.     

Charge density dependence of solution and gel behaviors of maleic acid-containing polyelectrolytes

Two kinds of polyelectrolytes containing maleic acid component (MA copolymers), i.e., poly(styrene-alt-maleic acid) (PSMA) and poly(vinyl methyl ether-alt-maleic acid) (PVMEMA), were investigated on their polymer chain dimensional changes in solution, and also in gel phase for the latter, as a function of the polymer charge density or pH of the (immersing) solution. Being different from common poly(carboxylic acid)s such as poly(acrylic acid), both of the MA copolymers showed maximum in the reduced viscosity or the gel size with increasing the charge density or the solution pH. The maximum in the reduced viscosity was much more significant for PSMA than PVMEMA. To see if intramolecular hydrogen bond between a pair of dissociated and undissociated carboxyl groups in an MA residue contributes to the emergence of the peak or not, similar measurements were performed also in the presence of concentrated urea (5 M). Almost the same values were obtained up to the peak position for the reduced viscosity and the gel swelling degree with increasing pH of the (immersing) solutions, which strongly suggested that the supposed effect is negligible, if any. All the results including those for PVMEMA system were interpreted in terms of the ionomer-like conformational change (ion cluster formation) of polyelectrolytes that has been often observed when the polymer charges are in rather less polar circumstances.     

Effects of silica nanoparticle addition on polymer semiconductor wettability and carrier mobility in solution‐processable organic transistors on hydrophobic substrates

The effects of the addition of silica nanoparticles (SNPs) on wettability of regioregular poly(3‐hexylthiophene) (P3HT) organic semiconductor solutions on hydrophobic substrates and the carrier mobility in organic field‐effect transistors (OFETs) made of these films are investigated. The dewetting of films made from P3HT solutions on hydrophobic substrates modified with octadecyltrichlorosilane (ODTS) is markedly suppressed after the addition of SNPs with phenyl surfactants. This enables us to fabricate continuous P3HT/SNPs films with high crystallinity by the conventional spin‐coating technique, leading to higher mobility compared with P3HT FETs fabricated on non‐modified substrates. Moreover, the addition of SNPs with larger diameters compensates for the degradation of mobility associated with the increase in the concentration of SNPs. Solution‐processed P3HT/SNPs FETs on ODTS‐modified substrates exhibit a field‐effect mobility of 1.3 × 10^?2 cm² V^?1 s^?1, which is almost comparable to that of P3HT FETs without SNPs (2.1 × 10^?2 cm² V^?1 s^?1). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 509–516     

Inducing a high twisted conformation in the polyimide structure by bulky donor moieties for the development of non-volatile memory

Two polyimides, PI(DAT-6FDA) and PI(DAPT-6FDA), from N-(2,4-diaminophenyl)-N,N-diphenylamine (DAT) or N-(4-(2′,4′-diaminophenoxy)phenyl-N,N-diphenylamine (DAPT) and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) were prepared to clarify the structural effect on the resulting memory properties. The memory device based on PI(DAT-6FDA) showed an unstable volatile behavior, while the device based on PI(DAPT-6FDA) with a more bulky donor (D) unit exhibited a stable non-volatile FLASH type memory characteristic with a long retention time over 10⁴ s. The theoretical simulation based on the density functional theory (DFT) suggested that the greater distinct charge separation between the ground and charge transfer (CT) states led to a highly stable memory behavior. Also, it was clarified that PI(DAPT-6FDA) had a highly twisted conformation compared to PI(DAT-6FDA) in the ground state, and a more twisted dihedral angle between the D and acceptor (A) units was induced in the CT state, which led to the non-volatile memory characteristic.     

Synthesis and Biological Evaluation of the Forssman Antigen Pentasaccharide and Derivatives by a One‐Pot Glycosylation Procedure

The synthesis and biological evaluation of the Forssman antigen pentasaccharide and derivatives thereof by using a one‐pot glycosylation and polymer‐assisted deprotection is described. The Forssman antigen pentasaccharide, composed of GalNAcα(1,3)GalNAcβ(1,3)Galα(1,4)Galβ(1,4)Glc, was recently identified as a ligand of the lectin SLL‐2 isolated from an octocoral Sinularia lochmodes. The chemo‐ and α‐selective glycosylation of a thiogalactoside with a hemiacetal donor by using a mixture of Tf₂O, TTBP and Ph₂SO, followed by activation of the remaining thioglycoside, provided the trisaccharide at the reducing end in a one‐pot procedure. The pentasaccharide was prepared by the α‐selective glycosylation of the N‐Troc‐protected (Troc=2,2,2‐trichloroethoxycarbonyl) thioglycoside with a 2‐azide‐1‐hydroxyl glycosyl donor, followed by glycosidation of the resulting disaccharide at the C3 hydroxyl group of the trisaccharide acceptor in a one‐pot process. We next applied the one‐pot glycosylation method to the synthesis of pentasaccharides in which the galactosamine units were partially and fully replaced by galactose units. Among the three possible pentasaccharides, Galα(1,3)GalNAc and Galα(1,3)Gal derivatives were successfully prepared by the established method. An assay of the binding of the synthetic oligosaccharides to a fluorescent‐labeled SLL‐2 revealed that the NHAc substituents and the length of the oligosaccharide chain were both important for the binding of the oligosaccharide to SLL‐2. The inhibition effect of the oligosaccharide relative to the morphological changes of Symbiodinium by SLL‐2, was comparable to their binding affinity to SLL‐2. In addition, we fortuitously found that the synthetic Forssman antigen pentasaccharide directly promotes a morphological change in Symbiodinium. These results strongly indicate that the Forssman antigen also functions as a chemical mediator of Symbiodinium.     

Synthetic study of kosinostatin aglycone: synthesis of BCDE rings using alkoxycarbonylmethylation of diazonaphthoquinone

A synthetic study of kosinostatin aglycone is reported. Synthesis of key intermediate lactone 3, which corresponds to the BCDE ring fragment, was accomplished, and the precursor BCD ring fragment 5 was synthesized via two routes. First, 5 was synthesized from 2,5-dimethoxybenzaldehyde 16 by the combination of typical known transformations including efficient application of non-aqueous OsO₄ oxidation in the presence of PhB(OH)₂. However the synthesis required 15 long steps, and its main difficulty was ortho-alkoxycarbonylmethylation of 1-naphthol. Next we attempted to apply our recently developed alkoxycarbonylmethylation of diazonaphthoquinone for the synthesis of 5, and 5 was successfully synthesized in 9 steps from the same starting compound 16. Finally, 5 was stereoselectively converted to lactone 3 via trifluoroacetic acid-mediated cyclization of the 3,4-epoxycylohexanecarboxylic acid derivative.     

Converging-axicon-based radially polarized ytterbium fiber laser and evidence on the mode profile inside the gain fiber

The radially polarized mode is achieved from an active Yb fiber by utilizing of an intracavity converging axicon, where the axicon acts as a TM(01) mode selector based on not only its Brewster convex surface but also the distance between its vertex and plane output coupler. The polarization state of the annular laser beam is checked by using a home-made eight-hole aperture. Furthermore, an uncoated plane glass plate is inserted into the cavity, and the reflected beam points to the existence of an annular lasing mode inside the gain fiber. The issues for developing high-power radially polarized fiber lasers also are considered.