Thermal hysteresis in the photoresponsivity of a langmuir film of amphiphilic spiropyran

We have found a thermal hysteresis in the photoresponsivity of a Langmuir film for the first time. The Langmuir film of an amphiphilic spiropyran, 1',3'-dihydro-3',3'-dimethyl-6-nitro-1'-octadecyl-8-(docosanoyloxymethyl)spiro[2H-1-benzopyran-2,2'-(2H)-indole] (SP) was fabricated at 13 degrees C at 10 mN m-1, followed by heating to a given temperature. UV irradiation of this film caused only the isomerization of SP to the corresponding merocyanine (MC) up to 29 degrees C. Light-induced J-aggregation of MC occurred at 30 degrees C. On the other hand, once the film was heated to 30 degrees C, light-induced J-aggregation was observed down to 27 degrees C. The hysteresis should be related with the phase transitions that occur in the bulk of SP at similar temperatures. No significant morphological change occurred by light-induced J-aggregation in the Langmuir-Blodgett (LB) film of SP by the present method, in contrast to the case of the LB films fabricated under isothermal conditions at 30 degrees C. This feature enabled us to pattern the LB film with J-aggregate of MC by UV irradiation through a photomask of lines with a width of 5 mum each.     

Glycoinsulins: dendritic sialyloligosaccharide-displaying insulins showing a prolonged blood-sugar-lowering activity

Mono-, di-, and trisialyloligosaccharides were introduced to mutant insulins through enzymatic reactions. Sugar chains were sialylated by alpha2,6-sialyltransferase (alpha2,6-SiaT) via an accessible glutamine residue at the N-terminus of the B-chain attached by transglutaminase (TGase). Sia2,6-di-LacNAc-Ins(B-F1Q) and Sia2,6-tri-LacNAc-Ins(B-F1Q), displaying two and three sialyl-N-acetyllactosamines, respectively, were administered to hyperglycemic mice. Both branched glycoinsulins showed prolonged glucose-lowering effects compared to native or lactose-carrying insulins, showing that sialic acid is important in obtaining a prolonged effect. Sia2,6-tri-LacNAc-Ins(B-F1Q), in particular, induced a significant delay in the recovery of glucose levels.     

Enantioselective crystal growth of leucine on a self-assembled monolayer with covalently attached leucine molecules

Enantioselective crystal growth of leucine occurs on a solid surface modified with a self-assembled monolayer depending on the chirality of the enantiomer attached, as evidenced by the X-ray diffraction method.     

Evaluation of scopadulciol-related molecules for their stimulatory effect on the cytotoxicity of acyclovir and ganciclovir against Herpes simplex virus type 1 thymidine kinase gene-transfected HeLa cells

Herpes simplex virus type 1 thymidine kinase (HSV TK) is involved in both antiherpetic therapy and cancer gene therapy with acyclovir (ACV) and ganciclovir (GCV). Enhanced sensitivity to these drugs is advantageous in their clinical use. In the present study, scopadulciol (SDC) and its related compounds were evaluated for their stimulatory effect on the cytotoxicity of ACV and GCV by determination of selective toxicities against HSV TK-expressing HeLa cells. Although SDC remarkably potenciated the cytotoxicity of ACV and GCV, the other tested compounds showed only weak selectivity, except for compound 34.     

Rapid simultaneous determination of o-phenylphenol, diphenyl, thiabendazole, imazalil and its major metabolite in citrus fruits by liquid chromatography-mass spectrometry using atmospheric pressure photoionization

A simple and rapid simultaneous analytical method of four post-harvest fungicides, o-phenylphenol (OPP), diphenyl (DP), thiabendazole (TBZ), imazalil (IMZ) and its major metabolite R14821 (IMZ-M) in citrus fruits was developed. These compounds were extracted under basic conditions with diethyl ether. The organic layer was washed with water and evaporated at moderate pressure adding methanol. These compounds were determined by liquid chromatography-mass spectrometry (LC-MS) using atmospheric pressure photoionization (APPI). The recoveries of the five compounds added to citrus fruits at 1 microg/g ranged from 67 to 100%, with relative standard deviations (R.S.D.) ranging from 2 to 8%. The detection limits (S/N = 3) were 0.01 microg/g and 0.05 microg/g (DP).     

Abstract quasilinear equations of second order with Wentzell boundary conditions

We introduce a general framework to treat abstract quasilinear equations of second order with Wentzell boundary conditions. As an example we study a wave equation for a second order quasilinear differential operator on with Wentzell boundary conditions.     

New partially oxidized 1-D platinum chain complexes consisting of carboxylate-bridged cis-diammineplatinum dimer cations

The first/second examples of partially oxidized 1-D platinum chain compounds consisting of cationic dimer units have been obtained from electro-oxidation of an aqueous solution containing cis-[Pt(NH3)2(OH2)2]2+ and acetate/propionate. The analytical and crystallographic studies reveal the mixed-valency of Pt(2.2+)infinity. The XPS confirms the presence of both Pt(II) and Pt(III). The solid-state physical measurements reveal that they are diamagnetic semiconductors and display a fairly broad, low-energy absorption band in the range of 500-3200 nm.     

A new synthesis of N-alkyl 3-acetyl-4-methoxycarbonylmethyl-2-methyl-1,4-dihydropyridines utilizing sec-aminodienyl esters with acetylacetone

The reactions of sec-aminodienyl esters 3 with acetylacetone (4) afforded N-alkyl 3-acetyl-4-methoxycarbonylmethyl-2-methyl-1,4-dihydropyridines 5 and enamines 6, providing a new azaelectrocyclization reaction.     

Phase Transition Behaviors of Self‐Oscillating Polymer and Nano‐Gel Particles

Summary: Self‐oscillating polymers and nano‐gel particles consisting of N‐isopropylacrylamide and the ruthenium catalyst of the Belousov‐Zhabotinsky reaction have been prepared. In order to clarify the crosslinking effect on the self‐oscillating behavior, the phase transition behaviors were investigated by measuring the transmittance and the fluorescence intensity of the polymer solution and the gel bead suspension. Cooperative effects due to crosslinking will play an important role for the design of nanoactuators.

Chemical structure of poly(NIPAAm‐co‐Ru(bpy)₃).