Synthesis of a new β-naphthothiazole monomethine cyanine dye for the detection of DNA in aqueous solution

Novel monomethine cyanine dye (MC) derived from β-naphthothiazole and benzothiazole has been prepared and characterized by ¹H and ¹³C NMR, FTIR, ESIMS, elemental analyses, absorption and fluorescence spectroscopy. The dye was conveniently synthesized by the condensation of two sulfate heterocyclic quaternary salts. The interaction between calf thymus DNA (ct-DNA) in tris(hydroxymethyl)aminomethane–HCl (Tris–HCl) aqueous buffer solution and MC has been studied with spectral fluorescence method. The binding constant value has been determined by fluorescence titration of MC with ct-DNA concentrations. The result obtained is consistent with an intercalative binding interaction between MC and ct-DNA. Compared with ethidium bromide (EB), MC showed a huge fluorescence enhancement upon mixing with ct-DNA.     

Biodegradable Nanocomposites Based on the Polyester Poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) and Layered Silicate or Expanded Graphite

Novel nanocomposites based on the biodegradable polymer poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBHx) and layered fillers, specifically layered silicate (clay25A) and expanded graphite (EG), were prepared by melt intercalation. The dispersion of the fillers in the PHBHx was characterized by wide‐angle X‐ray diffraction (WAXD) and transmission electron microscopy (TEM). The effects of the fillers on the polymer structure, thermal stability and mechanical properties of the nanocomposites were also studied, by differential scanning calorimetry, thermogravimetric analysis, and strain‐stress measurements in elongation, respectively. The WAXD and TEM results showed that the clay25A and EG was exfoliated into well‐dispersed sheets in the polymer matrix, especially when the filler concentration were relatively low. This gave rise to considerable improvements in Young's modulus, and resulted in increases in the thermal degradation. It should be possible to convert the EG dispersions obtained thus far to ones yielding filler‐filler networks that show electrical conductivity.     

Determination of total and polycyclic aromatic hydrocarbons in aviation jet fuel

The aviation jet fuel widely used in turbine engine aircraft is manufactured from straight-run kerosene. The combustion quality of jet fuel is largely related to the hydrocarbon composition of the fuel itself; paraffins have better burning properties than aromatic compounds, especially naphthalenes and light polycyclic aromatic hydrocarbons (PAHs), which are characterised as soot and smoke producers. For this reason the burning quality of fuel is generally measured as smoke fermation. This evaluation is carried out with UV spectrophotometric determination of total naphthalene hydrocarbons and a chromatographic analysis to determine the total aromatic compounds. These methods can be considered insufficient to evaluate the human health impact of these compounds due to their inability to measure trace (ppm) amounts of each aromatic hyrcarbon and each PAH in accordance with limitations imposed because of their toxicological properties. In this paper two analytical methods are presented. Both are based on a gas chromatographic technique with a mass detector operating in be selected ion monitoring mode. The first method was able to determine more than 60 aromatic hydrocarbons in a fuel sample in a 35-min chromatographic run, while the second was able to carry out the analysis of more than 30 PAHs in a 40-min chromatographic run. The linearity and sensitivity of the methods in measuring these analytes at trace levels are described.     

Synthesis,spectrophotometric, voltammetric,and density functional theory studies of tetrahydro[3,2-b]indolocarbazoles for sensing small molecules

Absorption spectra of tetrahydro[3,2-b]indolocarbazoles (THICZs) with respective molecular property and alkyl substituents have been prerecorded in diverse solvents in the scope between 200 and 600 nm for very fewer times in the literary study. The photo-physical behavior of liquified THICZs belonging to the existence surroundings. The solvatochromic behaviors of THICZs and solvent substance physical phenomenon can be analyzed by implementation of linear solvating energy state conception. Compound 4 shows excellent properties for sensing small molecules. The electrochemical behavior of some THICZs was investigated at carbon paste electrode where two electrode reactions were involved, irreversible oxidation-one electron transfer and quasi-reversible redox reactions forming phenolic followed by quinolone moiety electro active species. The density functional theory which means calculated molecular orbital energies (B3LYP/6-31G) and HOMO-LUMO gap/space for some presented indolocarbazoles have been performed.     

Modulation of heme redox potential in the cytochrome c6 family

Cytochrome c6A is a unique dithio-cytochrome of green algae and plants. It has a very similar core structure to that of bacterial and algal cytochromes c6 but is unable to fulfill the same function of transferring electrons from cytochrome f to photosystem I. A key feature is that its heme midpoint potential is more than 200 mV below that of cytochrome c6 despite having His and Met as axial heme-iron ligands. To identify the molecular origins of the difference in potential, the structure of cytochrome c6 from the cyanobacterium Phormidium laminosum has been determined by X-ray crystallography and compared with the known structure of cytochrome c6A. One salient difference of the heme pockets is that a highly conserved Gln (Q51) in cytochrome c6 is replaced by Val (V52) in c6A. Using protein film voltammetry, we found that swapping these residues raised the c6A potential by +109 mV and decreased that of c6 by almost the same extent, -100 mV. X-ray crystallography of the V52Q protein showed that the Gln residue adopts the same configuration relative to the heme as in cytochrome c6 and we propose that this stereochemistry destabilizes the oxidized form of the heme. Consequently, replacement of Gln by Val was probably a key step in the evolution of cytochrome c6A from cytochrome c6, inhibiting reduction by the cytochrome b6f complex and facilitating establishment of a new function.     

Simulation of three-dimensional incompressible flows in generalized curvilinear coordinates using a high-order compact finite-difference lattice Boltzmann method

In the present study, a high-order compact finite-difference lattice Boltzmann method is applied for accurately computing 3-D incompressible flows in the generalized curvilinear coordinates to handle practical and realistic geometries with curved boundaries and nonuniform grids. The incompressible form of the 3-D nineteen discrete velocity lattice Boltzmann method is transformed into the generalized curvilinear coordinates. Herein, a fourth-order compact finite-difference scheme and a fourth-order Runge-Kutta scheme are used for the discretization of the spatial derivatives and the temporal term, respectively, in the resulting 3-D nineteen discrete velocity lattice Boltzmann equation to provide an accurate 3-D incompressible flow solver. A high-order spectral-type low-pass compact filtering technique is applied to have a stable solution. All boundary conditions are implemented based on the solution of the governing equations in the 3-D generalized curvilinear coordinates. Numerical solutions of different 3-D benchmark and practical incompressible flow problems are performed to demonstrate the accuracy and performance of the solution methodology presented. Herein, the 2-D cylindrical Couette flow, the decay of a 3-D double shear wave, the cubic lid-driven cavity flow with nonuniform grids, the flow through a square duct with 90° bend and the flow past a sphere at different flow conditions are considered for validating the present computations. Numerical results obtained show the accuracy and robustness of the present solution methodology based on the implementation of the high-order compact finite-difference lattice Boltzman method in the generalized curvilinear coordinates for solving 3-D incompressible flows over practical and realistic geometries.     

Electrochemical oxidation by square-wave potential pulses in the imitation of phenacetin to acetaminophen biotransformation

Electrochemistry in combination with mass spectrometry is emerging as a versatile analytical technique in the imitation of oxidative drug metabolism during the early stages of drug discovery and development. Here, we present electrochemical O-dealkylation of phenacetin to acetaminophen by square-wave potential pulses consisting of consecutive sub-second oxidation and reduction steps. This O-dealkylation could not be achieved by oxidation at constant potential or longer potential pulses because of the fast hydrolysis of the reactive intermediates. Electrochemical conversion by square-wave potential pulses can thus widen the scope of electrochemical synthesis of metabolites and imitation of in vivo drug metabolism.     

A Midpoint-Radius approach to regression with interval data

In this paper, a revisited interval approach for linear regression is proposed. In this context, according to the Midpoint-Radius (MR) representation, the uncertainty attached to the set-valued model can be decoupled from its trend. The estimated interval model is built from interval input-output data with the objective of covering all available data. The constrained optimization problem is addressed using a linear programming approach in which a new criterion is proposed for representing the global uncertainty of the interval model. The potential of the proposed method is illustrated by simulation examples.     

Electronic states at dislocations and metal silicide precipitates in?crystalline silicon and their role in?solar cell materials

Predominant dislocation types in solar silicon are dissociated into 30°- and 90°-partials with reconstructed cores. Besides shallow 1D-band localized in their strain field and a quasi-2D band at the stacking fault connecting the two partials, the existence of several intrinsic core defects with deep lying levels has been demonstrated by electron spin resonance. The majority of core defects occur in nonequilibrium situations and, with the exception of a small EPR-signal assigned to a reconstruction defect, vanish after careful annealing above 800°C. There is good evidence now that part of deep levels observed in dislocated silicon is associated with impurities, especially with transition metal impurities. Electron-hole-pair recombination at a dislocation mainly runs via its shallow bands and is strongly increased by impurities bound to its core or in the strain field. The concentration of these impurities can be reduced by gettering processes to such a low level that radiative recombination at dislocations yields a luminescence efficiency of 0.1% at room temperature. A quite coherent picture has emerged for metal impurity precipitation in silicon. Early stages of precipitation in defect-free silicon are characterised by kinetically selected metastable defects forming as a result of large chemical driving forces for precipitation. Such defects are associated with deep level spectra which show the properties of extended multielectron defects. The evolution of the system to energetically more favourable configurations proceeds via ordinary particle coarsening but also via internal ripening, a process reminiscent of the above-mentioned metastable defects. Electronically, the defects evolve into metal-like inclusions which in general seem to act as strong recombination centers for minority carriers. In the presence of dislocations metastable defects quickly transform into equilibrium structures in the course of precipitation or do not form at all. In the presence of several metal impurities silicide precipitates which can be described as solid solutions of the respective metal atoms are observed, which is at least qualitatively in accord with ternary phase diagrams. Like single-metal silicide precipitates, strong minority carrier recombination is also typical for those multi-metal silicide particles.     

Melting phenomenon in magneto hydro-dynamics steady flow and heat transfer over a moving surfacein the presence of thermal radiation

The Lie group method is applied to present an analysis of the magneto hydro-dynamics(MHD) steady laminar flow and the heat transfer from a warm laminar liquid flow to a melting moving surface in the presence of thermal radiation.By using the Lie group method,we have presented the transformation groups for the problem apart from the scaling group.The application of this method reduces the partial differential equations(PDEs) with their boundary conditions governing the flow and heat transfer to a system of nonlinear ordinary differential equations(ODEs) with appropriate boundary conditions.The resulting nonlinear system of ODEs is solved numerically using the implicit finite difference method(FDM).The local skin-friction coefficients and the local Nusselt numbers for different physical parameters are presented in a table.