Third-order optical autocorrelator for time-domain operation at telecommunication wavelengths

We report on amorphous organic thin films that exhibit efficient third-harmonic generation at telecommunication wavelengths. At 1550 nm, micrometer-thick samples generate up to 17 µW of green light with input power of 250 mW delivered by an optical parametric oscillator. This high conversion efficiency is achieved without phase matching or cascading of quadratic nonlinear effects. With these films, we demonstrate a low-cost, sensitive third-order autocorrelator that can be used in the time-frequency domain

Ultrafast-pulse diagnostic using third-order frequency-resolved optical gating in organic films

We report on the diagnostic of ultrafast pulses by frequency-resolved optical gating (FROG) based on strong third-harmonic generation (THG) in amorphous organic thin films. The high THG conversion efficiency of these films allows for the characterization of sub-nanojoule short pulses emitting at telecommunication wavelengths using a low cost portable fiber spectrometer

Evaluation of lawsonia inermis leaf extracts for their in vitro fungitoxicity against certain soilborne pathogens

Screening of Lawsonia inermis leaf extracts for their fungitoxicity was carried out in vitro against some selected soil-borne phytopathogens, Rhizoctonia solani. Pythium aphanidermatum and Macrophomina phaseolina. Of the three solvent extracts studied, cold-water extract at 10% concentration showed a maximum of 70% inhibition of the mycelial growth of R. solani. Methanol extract at 2.5% concentration completely inhibited P. aphanidermatum while the same at 10% proved effective against M. phaseolina by 60% when compared to cold water and petroleum ether extracts. Petroleum ether extract was ineffective against R. solani and M. phaseolina. The amount of total phenols was 4.5 mg/g of fresh leaf tissue. Reverse phase high performance liquid chromatographic analysis of the cold-water extracts revealed the presence of four different absorption peaks of which only two compounds could be identified i.e. tannic acid and catecho

Characterization of polyphenol oxidase in ginger (Zingiber officinale R.)

A polyphenol oxidase (PPO) isoform that showed expression at all developmental stages of rhizomes in 13 ginger (Zingiber officinale R.) accessions and the only one observed at full maturity of rhizome was characterized. The isoform is a non-covalent homo-dimeric protein of 66 kDa subunits. The native molecular mass was estimated at ~127 kDa using non- reducing SDS–PAGE (10%). Its activity after purification was confirmed by substrate staining both in native gel (7%) and non-reducing SDS gel (10%). The N-terminal amino acid sequence of the subunit of ginger rhizome polyphenol oxidase is ‘Glu-Gln-Gly-Val-Gly-Gly-Asp-Asp-Gly-Leu-.’ The enzyme showed maximum activity at pH 4.5 and 60°C. The PPO is thermo-tolerant and active in a broad pH range (pH 3.5 to 8). Heat inactivation studies showed a decrease in enzyme activity at 75°C and above. Lower concentrations of MgCl2 (1 mM) and CaCl2 (0.5 mM) activated the enzyme whereas higher concentrations (10 mM) reduced the activity. L- Cysteine HCl, L-ascorbic acid, potassium metabisulfite and NaCl inhibited PPO strongly. Western blot analysis of crude leaf extracts with polyclonal antiserum raised against purified PPO confirmed absence of its expression in leaves at different stages of development. Polyclonal anti-PPO antiserum cross reacted with Solanum tuberosum, Raphanus sativus and Dioscorea esculenta tuber extracts and Solanum melongena, Malus sylvestris and Musa paradisiaca fruit extracts but no cross reactivity was observed with Curcuma amada and Ipomoea batatas extracts. &nbsp

Characterization of polyphenol oxidase in ginger (Zingiber officinale R.)

A polyphenol oxidase (PPO) isoform that showed expression at all developmental stages of rhizomes in 13 ginger (Zingiber officinale R.) accessions and the only one observed at full maturity of rhizome was characterized. The isoform is a non-covalent homo-dimeric protein of 66 kDa subunits. The native molecular mass was estimated at ~127 kDa using non- reducing SDS–PAGE (10%). Its activity after purification was confirmed by substrate staining both in native gel (7%) and non-reducing SDS gel (10%). The N-terminal amino acid sequence of the subunit of ginger rhizome polyphenol oxidase is ‘Glu-Gln-Gly-Val-Gly-Gly-Asp-Asp-Gly-Leu-.’ The enzyme showed maximum activity at pH 4.5 and 60°C. The PPO is thermo-tolerant and active in a broad pH range (pH 3.5 to 8). Heat inactivation studies showed a decrease in enzyme activity at 75°C and above. Lower concentrations of MgCl2 (1 mM) and CaCl2 (0.5 mM) activated the enzyme whereas higher concentrations (10 mM) reduced the activity. L- Cysteine HCl, L-ascorbic acid, potassium metabisulfite and NaCl inhibited PPO strongly. Western blot analysis of crude leaf extracts with polyclonal antiserum raised against purified PPO confirmed absence of its expression in leaves at different stages of development. Polyclonal anti-PPO antiserum cross reacted with Solanum tuberosum, Raphanus sativus and Dioscorea esculenta tuber extracts and Solanum melongena, Malus sylvestris and Musa paradisiaca fruit extracts but no cross reactivity was observed with Curcuma amada and Ipomoea batatas extracts. &nbsp

Identification of <img src='/image/spc_char/alpha.gif'> amylase inhibitors from <i style="">Syzygium cumini </i>Linn seeds

677-680 The aqueous extract of S. cumini or Eugenia jambolana seeds and Psidium guajava leaves showed higher inhibition against the porcine pancreatic -amylase among the medicinal plants studied. The -amylase inhibitors from S.cumini seeds were separated from the extract by preparative thin layer chromatography into fractions with different Rf values. The fraction with Rf value between 0.285 and 0.43, which showed maximum inhibitory activity, was eluted and analyzed through LC-MS. The compounds identified from the seed extract of S. cumini were betulinic acid and 3,5,7,4`-tetrahydroxy flavanone, which were reported earlier from S. formosanum and other plants. Dixon plot showed that the inhibition was non-competitive in nature. </smarttagtype

Highly Ordered Gold Nanotubes Using Thiols at a Cleavable Block Copolymer Interface

We have prepared functionalized nanoporous thin films from a polystyrene-block-polyethylene oxide block copolymer, which was made cleavable due to the intervening disulfide bond. The cleavage reaction of the disulfide bond leaves behind free thiol groups inside the nanopores of polystyrene thin film. This nanoporous thin film can be used as a template for generating gold nanoring structures. This strategy can provide a facile method to form a highly ordered array of biopolymer or metal−polymer composite structures