Effect of photoreactivity of polyimide on the molecular orientation of liquid crystals on photoreactive polymer/polyimide blends

We prepared blend alignment layers from polymethacrylate with coumarin side chains (PMA-g-coumarin) and polyimides for the orientation of liquid crystals (LCs) using linearly polarized ultraviolet (UV) irradiation. We used two different polyimides, namely 4,4'-(hexafluoro-isopropylidene) diphthalic anhydride-3,5-diamino-benzoic acid (6FDA-DBA) and pyromellitic dianhydride-4,4'-oxydianiline (PMDA-ODA). It was found that the molecular orientation of the LC depended on the type of polyimide in the blend alignment layer. The thermal stability of the LC orientation was enhanced regardless of the type of polyimide, while the direction of LC orientation was different for each type of polyimide. The photoreactivity of the polyimide was a very important factor in determining the molecular orientation of the LC on the blend alignment layer. This may be attributed to the different mechanisms of LC orientation on PMA-g-coumarin and polyimide induced by the polarized UV irradiation. The direction of the LC orientation could be changed by controlling the photoreaction of the polyimides using the appropriate UV filter for the polarized UV irradiation.     

A Comparative Study of Biologically and Chemically Fabricated Synthesized AgNPs’ Supplementation with Respect to Heat-Shock Proteins,Survival, and Hatching Rates of Chicken Embryos: An In Ovo Study

The present study examined the characterization and concentration of Brassica oleracea L. var. capitata f. rubra (BOL, commonly known as red cabbage) extracted AgNPs (BOL-AgNPs) and chemically (CHE) synthesized AgNPs (CHE-AgNPs) in chicken embryos through in ovo injections. We investigated the effects of both AgNPs on the survival, hatchability, body weight, and expressions of heat-shock proteins (HSPs). The BOL-AgNPs and CHE-AgNPs at (T1) amounted 100, at (T2) 1000, at (T3) 2500, and at (T4) 5000 µg/100 µl/egg, respectively through in ovo injections. At the end of the experimental period, the body and liver weights of the chicks were altered between the groups and among the concentrations. The serum levels of SGOT and SGPT were significantly increased at BOL-T3 and -T4. Survival and hatching rates were more reduced in the BOL-T3- and -T4-treated groups than at BOL-T1 and -T2. Nevertheless, they were more diminished in the CHE-AgNPs than in the BOL-AgNPs. The CHE-AgNPs revealed the presence of micronuclei and nuclear abnormalities, in contrast to BOL-T4. The mRNA and protein expressions of HSP-60 and 70 in the liver were higher in CHE-AgNPs than in BOL-AgNPs. Hence, plant-synthesized AgNPs are superior in ovo nano-nutrition carriers of nutrients without toxicity than CHE-AgNPs.     

Steric trigger as a mechanism for CB1 cannabinoid receptor activation

To determine the moiety that behaves as the steric trigger to activate the CB(1) cannabinoid receptor, conformational properties of the nonclassical cannabinoid CP55244, one of the most potent CB(1) receptor agonists, were characterized by conformational analysis, rotational barrier calculations, and molecular dynamics (MD) simulations. It was shown from the present MD simulations that the torsion angles phi1 and phi4 of the C3 side chain showed the most dramatic change when compared with the ground-state receptor-bound conformation, indicating that rotation around these torsion angles is responsible for releasing the ligand strain energy. Multiple stages would be involved in the ligand conformational change. As a molecular mechanism for the ligand-induced CB(1) receptor conformational change, we propose that the C3 side chain serves as the steric trigger, while the ACD-ring moiety of CP55244 serves as the plug. Steric clash with helices within the binding pocket would induce microconformational adaptation within the protein. This mechanism would suggest that rotational flexibility in a ligand may be as important a determinant of agonist activity as the pharmacophoric elements that can be identified.     

Photoaddition reactions of 1,4-diphenylbutadiyne with olefins

1,4-Diphenylbutadiyne(DPB) and several olefins such as 2,3-dimethyl-2-butene, 1,4-cyclohexadiene and dimethyl fumarate were irradiated with 300 nm UV light to obtain interesting cross-cycloaddition products.     

Relative DNA binding affinity of helix 3 homeodomain analogues, major groove binders, can be rapidly screened by displacement of prebound ethidium bromide. A comparative study

The binding affinity for a 12-bp dsDNA of Antennapedia helix 3 analogues, major groove binders, has been measured by displacement of prebound ethidium bromide, a fluorescent displacement assay proposed for minor groove binders by Boger et al.(J. Am. Chem. Soc., 2000, 122, 6382-6394). Relative binding affinities determined by this method were compared to those obtained by gel mobility shift and footprinting assays for the 12-bp dsDNA and a 178-bp DNA fragment. The present work demonstrates that the fluorescence displacement assay is suitable for rapid screening of major groove binders, even though about 60 to 70% of the prebound ethidium bromide is displaced by these peptides. Total (100%) displacement of ethidium bromide was serendipitously achieved by addition in the peptide sequence, at the N-terminus, of a S-3-nitro-2-pyridinesulfenyl-N-acetyl-cysteine residue. S-3-nitro-2-pyridinesulfenylcysteine was shown to (i) bind to dsDNA with a micromolar affinity and (ii) direct within DNA grooves a peptide with no affinity for dsDNA.     

IDENTIFICATION AND CHARACTERIZATION OF THE MAJOR PHOTOADDUCTS FORMED BETWEEN 1-PHENYL-1,3,5-HEPTATRIYNE AND UNDECYLENIC ACID METHYL ESTER

Abstract— The near-UV induced photoreactions of 1-phenyl-1,3,5-heptatriyne (PHT) with undecylenic(10-undecenoic) acid methyl ester (UAME) and 1-hexene have been investigated in n-hexane. Four major photoadducts have been isolated in both cases and purified by normal and reverse phase liquid chromatography. The structures of these adducts were determined by mass, UV absorption, FT-IR, ¹H-and ¹³C-NMR spectral analyses, one-and two-dimensional nuclear Overhauser effect studies, and ¹H-¹H homo-correlation spectroscopy. All the data indicate that the adducts are cyclobutenes resulting from the [2+2] photocycloaddition of PHT to UAME and 1-hexene.     

Fabrication of flexible carbon nanotube field emitter arrays by direct microwave irradiation on organic polymer substrate

Carbon nanotubes (CNTs) were directly synthesized on flexible polymer substrates without damage of polymer by microwave irradiation. Cobalt was used as the catalysts, and the synthesis was done in the atmospheric pressure with an acetylene carbon source. Only 5 s was required for the synthesis of well-graphitized CNTs. Field emission measurements revealed that this flexible CNT field emitter array has a great potential for the flexible field emission displays (FEDs).     

The reducive amination of phthalaldehyde by tetracarbonylhydridoferrate : Synthesis of 2-arylisoindoles

Phthalaldehyde reacted with primary amines in the presence of tetracarbonylhydridoferrate under mild conditions to give 2-substituted isoindoles and/or isoindolines in good to excellent yields. Aliphatic amines gave selectively the isoindolines but aromatic amines had a great tendency to the isoindoles. 2-(2-Tolyl)-, 2-(4-tolyl)-, 2-(4-methoxyphenyl)-, 2-(3-chlorophenyl)-, 2-(4-chlorophenyl)- and 2-(3,4-dichlorophenyl)-isoindole were prepared by this method.     

Surface Modification of Carbon Nanotube by Poly(ethylene glycol) for the Preparation of Poly(vinyl alcohol) Nanocomposite

Herein, PEGylated multi-walled carbon nanotube (MWNT) was prepared for the successive fabrication of poly(vinyl alcohol) PVA/MWNT nanocomposite film by solution casting. The surface modified MWNT showed a good colloidal stability in a polar solvent, i.e., water. Also, the PEGylated MWNT had an improved dispersion stability in aqueous PVA solution. The mixture of PEGylated MWNT and PVA dissolved in water was film casted and the dispersion uniformity and corresponding improvement of electrical conductivity were investigated. The electrical conductivity of PVA/modified MWNT composite film was three-fold higher than that of PVA/pristine MWNT composite film due to the much improved distribution uniformity of modified MWNT in PVA matrix.