Optical tuning of Berry phase effect in topological insulators

We theoretically discuss the influence of driving laser field on the topological nature, one of the manifestation of the electron Berry phase effect, in two-dimensional electronic systems. Adiabatic change of the laser amplitude with circular polarization alters the “order parameter”, termed the Chern number, in topological insulator with broken time-reversal symmetry, resulting in photo-induced phase transition. The finding is an optical analog of the integer quantum Hall effect, that is triggered by the laser field instead of magnetic field. This parallelism suggests the similarity of effects to electron dynamics between circularly polarized light and magnetic field.     

Switching of the enzymatic activity synchronized with signal recognition by an artificial DNA receptor on a liposomal membrane

We constructed a supramolecular system on a liposomal membrane that is capable of activating an enzyme via DNA hybridization. The design of the system was inspired by natural signal transduction systems, in which enzymes amplify external signals to control signal transduction pathways. The liposomal membrane, providing a platform for the system, was prepared by the self-assembly of an oligonucleotide lipid, a phospholipid and a cationic synthetic lipid. The enzyme was immobilized on the liposomal surface through electrostatic interactions. Selective recognition of DNA signals was achieved by hybridizing the DNA signals with the oligonucleotide lipid embedded in the liposome. The hybridized DNA signal was sent to the enzyme by a copper ion acting as a mediator species. The enzyme then amplified the event by the catalytic reaction to generate the output signal. In addition, our system demonstrated potential for the discrimination of single nucleotide polymorphisms.     

Glycosyl sulfonium ions as storable intermediates for glycosylations

Glycosyl sulfonium ions, which serve as persistent glycosyl cation equivalents, were prepared by the addition of diorganosulfides to an electrochemically generated glycosyl triflate. Low-temperature and variable-temperature NMR studies were performed to reveal the structure, stability, and reactivity of glycosyl sulfonium ions. The glycosyl sulfonium ions could be used as storable intermediates for reactions with various glycosyl acceptors including thioglycosides to give the corresponding disaccharides.     

WKB analysis of the Schrödinger–KdV system

We consider the behavior of solutions to the water wave interaction equations in the limit ε→0⁺$\epsilon \to 0^{+}$. To justify the semiclassical approximation, we reduce the water wave interaction equation into some hyperbolic-dispersive system by using a modified Madelung transform. The reduced system causes loss of derivatives which prevents us to apply the classical energy method to prove the existence of solution. To overcome this difficulty we introduce a modified energy method and construct the solution to the reduced system.     

Synthesis of 6-O-Hexadecyl- and 6-O-Octylsucroses and Their Self-Assembling Properties Under Aqueous Conditions

This paper reports the synthesis and self-assembling properties of 6-O-hexadecyl- and 6-O-octylsucroses. Mono-etherification of 2,3,4,1′,3′,4′-hexa-O-benzylsucrose with the corresponding alkyl bromides predominantly took place at the glucose 6-position and the products were isolated by silica gel column chromatography. Benzyl groups in the isolated products were cleaved to yield the target derivatives. The SEM, TEM, XRD, and DLS results indicated that 6-O-alkylsucroses formed vesicle-type particles via formation of lamellar-like planes under aqueous conditions, which were further merged by fusion of the planes to construct larger aggregates. The self-assembling properties of the materials were different from those of the previously reported 6-O- and 6’-O-hexadecylsucroses mixture.     

Genetic dissection of testis weight in a mouse strain having an extremely large testis: major testis weight determinants are autosomal rather than Y-linked on the basis of comprehensive analyses in Y-chromosome consomic strains

I investigated the potential contribution of Y-linked genes by analyzing 16 Y-consomic strains that had been established on a DH-strain background. The results provided evidence that only the Y chromosome from the C3H/HeJ strain was different from most other inbred strains. The CBA strain has the lightest testis and the DDD strain has the heaviest testis among mouse strains; however, Y-consomic analysis revealed that there were no significant differences in testis weight among DH, DH-Chr Y(DDD), and DH-Chr Y(CBA) strains, suggesting that Y(DDD) and Y(CBA) themselves do not influence testis weight. QTL analysis in DDD x DH F(2) mice identified significant testis weight QTLs on chromosomes 9, 14, and 17, and the DDD allele at all these loci was associated with an increase in testis weight. Contribution of Y chromosome itself to testis weight was thus rather modest, and therefore, major testis weight determinants are autosomal. However, it was uncertain whether there would be any effects by interactions between Y chromosomal and autosomal genes.     

Direct polycondensation of carbon dioxide with xylylene glycols: a new method for the synthesis of polycarbonates

This communication describes the direct polycondensation of carbon dioxide with p- and m-xylylene glycols using the system trisubstituted phosphine/carbon tetrahalide/base as a condensing agent. The polymerization reaction of carbon dioxide with p-xylylene glycol was carried out in the presence of the condensing agent in N,N-dimethylformamide. The yield was at most 81.0% obtained by using the condensing agent tributylphosphine/carbon tetrabromide/N-cyclohexyl-N′,N′,N″,N″-tetramethylguanidine (CyTMG). The structure of the product was determined by means of ¹H NMR, ¹³C NMR, and IR spectroscopy to be that of a polycarbonate. The molecular weight was estimated to be ca. 1 000–2 000 by ¹H NMR analyses.     

Synthesis of linear and star-shaped phosphorus-containing telechelic polymers via living cationic ring-opening polymerization using a halobenzene/nickel(II) bromide catalyst

This paper reports a living cationic ring-opening polymerization of 2-phenyl-1,3,2-dioxaphosphorinane (a six membered cyclic phosphonite, 1) initiated by a new catalyst system of a halobenzene with NiBr₂. The polymerization proceeded in a living nature to produce a poly(phosphinate) 2. The polymerizations of seven-and five-membered cyclic phosphonites with this catalyst system are also described. The kinetic analysis of the polymerization of 1, initiated with this catalyst system, has successfully been carried out. The difference of the nature in the polymerizations of five-, six-, and seven-membered monomers is discussed. Syntheses of linear and star-shaped telechelic polymers using di-, tri-, tetra-, and hexahalobenzenes as a catalyst component are disclosed.