Detection of Free Thiols and Fluorescence Response of Phycoerythrin Chromophore after Ultraviolet-B Radiation Stress

The chemistry of thiol-chromophore linkage plays a central role in the nature of fluorescence of phycoerythrin (PE). Interaction of thiol and chromophore is crucial for the energy transfer, redox signal and inhibition of oxidative damage. In the present investigation the effects of ultraviolet-B radiation on an emission fluorescence intensity and wavelength shift in PE due to interaction between thiol and chromophore by remarkable strategy of detection technique was studied. Purification of PE was done by using a gel permeation and ion exchange chromatography that yielded a quite high purity index (6.40) in a monomeric (αβ) form. UV-B radiation accelerated the quenching efficiency (24.9 ± 1.52%) by reducing fluorescence emission intensity of thiol linked chromophore after 240 min of UV-B exposure. However, after blocking of transiently released free thiol by N-ethylmaleimide, quenching efficiency was increased (36.8 ± 2.80%) with marked emission wavelength shift towards shorter wavelengths up to 562 nm as compared to 575 nm in control. Emission fluorescence of free thiol was at maximum after 240 min that was detected specifically by monobromobimane (mBrB) molecular probe. The association/dissociation of bilin chromophore was analyzed by SDS- and Native-PAGE that also indicated a complete reduction in emission fluorescence. Our work clearly shows an early detection of free thiols and relative interaction with chromophore after UV-B radiation which might play a significant role in structural and functional integrity of terminal PE.     

Investigation of secondary flow and the related instability on an infinite yawed cylinder with Schubauer’s ellipse as section

This paper presents the principal results of a theoretical investigation of the secondary flow and the related instability performed in the laminar incompressible boundary layer on an infinite uniform yawed solid cylinder with Schubauer’s ellipse of axial ratio 2·96:1 as the section normal to the leading edge. The secondary flow profiles and the value of the instability criterion are obtained at different points of the wing section and for various angles of sweepback. It is found that in favourable pressure gradients and at pressure minimum, the secondary flow profiles have negative values. In regions of adverse pressure gradients after the pressure minimum the secondary flow changes sign from negative to positive values and have points of inflexion. The change of sign starts from the surface and extends to the edge of the boundary layer downstream. At some points in adverse pressure gradients the secondary flow profiles have double points of inflexion and values of both signs simultaneously. It is found that an adverse pressure gradient produces more powerful secondary flow than a favourable pressure gradient of the same strength. It is also found that the values of the instability criterion increase with the increasing sweepback whether the pressure gradient is favourable or adverse. At every point of the wing section, there are two values of the criterion for a given sweepback. The effect of adverse pressure gradient on the variation of the criterion is much more pronounced than that of a favourable pressure gradient. It is also seen that the flow is intermittently laminar and turbulent for low values of the chordwise free stream Reynolds number and for low values of sweepback and consists of an irregular sequence of laminar and turbulent regions.     

Synthetic Strategies in the Preparation of Phenanthridinones

Phenanthridinones are important heterocyclic frameworks present in a variety of complex natural products, pharmaceuticals and displaying wide range of pharmacological actions. Its structural importance has evoked a great deal of interest in the domains of organic synthesis and medicinal chemistry to develop new synthetic methodologies, as well as novel compounds of pharmaceutical interest. This review focuses on the synthesis of phenanthridinone scaffolds by employing aryl-aryl, N-aryl, and biaryl coupling reactions, decarboxylative amidations, and photocatalyzed reactions.     

CuCN catalyzed one pot synthesis of γ-keto diesters: domino double Michael addition followed by Nef reaction

An efficient one pot synthesis of γ-keto diesters through double Michael addition coupled with Nef reaction in the presence of CuCN catalyst and Cs₂CO₃ base is described. The reaction proceeds rapidly in DCM to give the products in good yields. A plausible mechanism is proposed.     

Effects of Alkaline Ferrocyanide on Non-faradaic Yields of Anodic Contact Glow Discharge Electrolysis: Determination of the Primary Yield of OH· Radicals

Non faradaic yields of anodic contact glow discharge electrolysis (CGDE) originate through H^· and OH^· radical generated during the process. Scavenging effects of Fe(CN) ₆ ^4? on OH^· radicals, in alkaline media have been investigated. A kinetic analysis of the competing reactions of O^? with different species in the system leads to an yield of 9.8?mol?mol?electron^?1 of OH^· and H^· radicals each in the liquid phase reaction zone of anodic CGDE in good agreement with the yield reported from a study involving H^· radical scavengers.     

Design,synthesis,characterization,cytotoxic and structure activity relationships of novel Ru(Ⅱ) complexes

Platinum containing compounds have shown antineoplastic potential, but their clinical applications have been limited by high toxicity. Ruthenium containing complexes have long been known to be well suited for biological applications, and have long been utilized as replacements to popular platinum based-drugs. Here, we report a novel series of ruthenium(II) arene compounds bearing thiosemicarbazone and isonicotinylhydrazone ligands with potent anticancer activity their structure activity relationships and apoptosis was studied. The cytotoxic activity of the new ruthenium(II) arene compounds has been evaluated in several cell lines (Molt 4/C8, L1210, CEM, HL60 and BEL7402). Among them, ten complexes were found to be excellent in vitro growth inhibitory activity against various cell lines with IC50 in the sub-micromolar range.     

Oxidation and thermal reduction of the Cu(1 0 0) surface as studied using positron annihilation induced Auger electron spectroscopy (PAES)

Changes in the surface of an oxidized Cu(1 0 0) single crystal resulting from vacuum annealing have been investigated using positron annihilation induced Auger electron spectroscopy (PAES). PAES measurements show a large increase in the intensity of the annihilation induced Cu M_2,3VV Auger peak as the sample is subjected to a series of isochronal anneals in vacuum up to annealing temperature 300 °C. The intensity then decreases monotonically as the annealing temperature is increased to ∼600 °C. Experimental probabilities of annihilation of surface-trapped positrons with Cu 3p and O 1s core-level electrons are estimated from the measured intensities of the positron annihilation induced Cu M_2,3VV and O KLL Auger transitions. Experimental PAES results are analyzed by performing calculations of positron surface states and annihilation probabilities of surface-trapped positrons with relevant core electrons taking into account the charge redistribution at the surface, surface reconstructions, and electron-positron correlations effects. The effects of oxygen adsorption on localization of positron surface state wave function and annihilation characteristics are also analyzed. Possible explanation is proposed for the observed behavior of the intensity of positron annihilation induced Cu M_2,3VV and O KLL Auger peaks and probabilities of annihilation of surface-trapped positrons with Cu 3p and O 1s core-level electrons with changes of the annealing temperature.     

Sonolytic enhancement of the bactericidal activity of irradiated titanium dioxide suspensions in water

Irradiated TiO₂ suspensions in water were used to inactivate Escherichia coli and Hansenula polymorpha. Two types of batch reactors employing static and recirculating solutions were used in this study. Sonolysis using a 20 kHz ultrasonic unit was found to enhance the microorganism inactivation in all instances, although the enhancement was more modest for the batch recirculation reactor. These data are interpreted within the framework of four possible mechanisms. The mechanism based on sonolytic creation of ·OH appears to provide the most satisfactory explanation of the data trends. The present data also implicate ·OH as the dominant bactericidal agent in irradiated TiO₂ suspensions.     

Nanoporous TiO2 and WO3 films by anodization of titanium and tungsten substrates: influence of process variables on morphology and photoelectrochemical response

The photoelectrochemical response of nanoporous films, obtained by anodization of Ti and W substrates in a variety of corrosive media and at preselected voltages in the range from 10 to 60 V, was studied. The as-deposited films were subjected to thermal anneal and characterized by scanning electron microscopy and X-ray diffraction. Along with the anodization media developed by previous authors, the effect of poly(ethylene glycol) (PEG 400) or D-mannitol as a modifier to the NH4F electrolyte and glycerol addition to the oxalic acid electrolyte was studied for TiO2 and WO3, respectively. In general, intermediate anodization voltages and film growth times yielded excellent-quality photoelectrochemical response for both TiO2 and WO3 as assessed by linear-sweep photovoltammetry and photoaction spectra. The photooxidation of water and formate species was used as reaction probes to assess the photoresponse quality of the nanoporous oxide semiconductor films. In the presence of formate as an electron donor, the incident photon to electron conversion efficiency (IPCE) ranged from approximately 130% to approximately 200% for both TiO2 and WO3 depending on the film preparation protocol. The best photoactive films were obtained from poly(ethylene glycol) (PEG 400) containing NH4F for TiO2 and from aqueous NaF for WO3.