Effect of a magnetic field on Lorentz collisions in acetylene-air flames

The damping constants (α-parameter) for Li, Na, K, Mg, and Ca were determined from curves of growth prepared from emission measurements at 0, 1.3, 2.2, and 3 kG. The collisional (Lorentz) half-intensity width Δλ_L, the absolute atom concentrations N in the flame, and the effective collisional cross sections Q_L have been calculated. They show appreciable increases with magnetic field strength. From the line profiles, it is found that the half-intensity width $\text{Δλ}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ did not change, while the width at the extreme wings Δλ_w has broadened slightly. The kind of perturbers which are thought to play an important role in collisions and the preponderant type of interaction are discussed.     

Spectral line broadening and shift by collisions in an air-acetylene flame

Collisional broadenings and shifts of profiles have been investigated for the following emission lines: 5889.95 A Na, 4047.20 A K, 4226.73 A Ca, 3273.96 A Cu, and 4030.76 A Mn in an air-acetylene flame. The Lorentz widths δλ_L at half-maximum intensity, the shifts δλ_s, and the ratio η ≡δλ_L/δλ_s were determined experimentally. The values of C₆ in the Lennard-Jones (LJ) potential were calculated from a Coulomb approximation. For the LJ-potential, δλ_c,δλ_s and the repulsive constants C₁₂ were calculated from η_exp, C₆ and compared with experiments. A method is proposed for η<2.78 to obtain suitable values of the broadening parameters. We recommend calculation of the total potential function because the LJ-potential may not be suitable for all systems, particularly when η<2.78. The natural (δλ_N) and quenching (δλ_q) widths were calculated and used as correction factors.     

Synthesis of new transition metal complexes of 1H-perimidine derivatives having antimicrobial and anti-inflammatory activities

New series of 1H-perimidine-2-thiol derivatives and (2-substituted-1H-perimidin-1-yl)ethane-1,2-dione derivatives and their ligands (C₂₄H₁₄N₄S₂O₂) H₂L¹ and (C₂₆H₁₈N₄S₂O₂) H₂L² have been synthesized with transition metal ions, e.g., Copper (II), Silver (I), Cobalt (II) and Ruthenium (III) were prepared and evaluated for their antimicrobial, analgesic and anti-inflammatory activities. The synthesized compounds and their complexes were characterized by elemental analysis, ¹H NMR, IR, MS, molar conductance, thermal gravimetric analysis and electronic spectra. All results revealed that compounds 3 and 13 exhibited high inhibitory effects against some bacterial strains by the disc diffusion method. On the other hand, compounds 2, 3, 7 and 12 displayed potent anti-inflammatory activity.     

Microstructure changes and steady state creep characteristics in Pb-Sn alloys during transformation

The steady state creep of Pb-10 wt.% Sn and Pb-61·9 wt.% Sn alloys have been investigated under different constant stresses near the transformation temperature. The temperature dependence of steady creep rate has shown two different transition points; at 423 K for Pb-10 wt.% Sn alloy and at 403 K for Pb-61·9 wt.% Sn (the eutectic composition). The strain rate sensitivity parameter (m) has been found to increase by raising the working temperature and to reach 0·45 and 0·85 for the first and second alloy, respectively. The activation energies of steady state creep of Pb-10 wt. % Sn have been found to be 46·2 kJ/mole and 88·2 kJ/mole in the low and high temperature regions (below and above 423 K) referring to dislocation and self diffusion mechanisms. While activation energies of steady creep in Pb-61·9 wt.% Sn have been found to be 42 kJ/mole and 63 kJ/mole in the low and high temperature region (below and above 403 K), characterizing grain boundary diffusion in Sn and Pb respectively. X-ray analysis and microscopic investigations of the test alloys have confirmed the above mentioned mechanisms.     

New microstructured chromium doped poly(p‐toluidine) as a new acid–base indicator and precursor for chromic oxide nanostructured

New chromium doped poly(p‐toluidine) (Cr‐PPT) was synthesized via chemical oxidative polymerization of p‐toluidine with potassium dichromate as an initiator in acidic aqueous medium. The spectrophotometric behavior of Cr‐PPT in acetone and chloroform as different solvents was investigated. Cr‐PPT exhibits bathochromically red shift at 46‐nm value with the increasing of solvent polarity. The intermolecular charge transfer band peak for Cr‐PPT shifted from 422 nm in low‐polar solvent (chloroform) to high‐polar solvent (acetone) to 468 nm. Optical absorption measurements are used to obtain the energy gap of prepared Cr‐PPT. Cr‐PPT has an optical band gap (E_g = 1.90 to 2.05 eV) that is located in the semiconductor range. Pink color was observed using Cr‐PPT solution in acidic media while it changes sharply to yellow in basic medium. Based on intermolecular charge transfer, the Cr‐PPT was used as acid–base indicator. Cr‐PPT and phenolphthalein (phph) indicator were used for determination of normality of HCl using standard 0.1 N NaOH, the two indicators gave equal end point values. Using Cr‐PPT as a new molecular precursor for the production chromium oxide in nanoscale by thermal decomposition route was studied, and the average size of synthesized Cr₂O₃ was found in the range of 54–61 nm. Copyright © 2017 John Wiley & Sons, Ltd.     

Pharmacological evaluation of benzimidazole derivatives with potential antiviral and antitumor activity

In recent years the synthesis of benzimidazole and its derivatives has attracted the attention of many organic chemists because of the compounds’ interesting biological activity and the crucial importance of the benzimidazole unit in the function of these biologically important molecules. Benzimidazole-based polyheterocyclic compounds have several interesting biological properties. Simple synthetic strategies leading to benzimidazole-based fused polyheterocyclic systems and the antiviral and anticancer biological activity of the compounds are surveyed in this review article.     

Evolution of microwave irradiation and its application in green chemistry and biosciences

Microwave-assisted organic reactions have been applied as an effective technique in organic synthesis. Microwave irradiation often leads to shorter reaction times, increased yields, easier workup, matches with green chemistry protocols, and can enhance the region and stereo selectivity of reactions. In fact, the high usefulness of microwave-assisted synthesis encouraged us to increase the efficiency of several organic transformations and synthesis. High-speed microwave-assisted chemistry has attracted a considerable amount of attention in recent years and has been applied successfully in various fields of synthetic organic chemistry, proteins, peptides, drug discovery, and green chemistry. The various roles of microwave-assisted organic chemistry in green and sustainable chemistry are discussed, beginning with the strategies, technologies, and methods that were employed routinely at the time of the first reports of microwave applications. Microwave processing has several advantages over conventional sintering/heating, such as the reduction in cycle time, energy efficiency, eco-friendliness, and providing finer microstructures, leading to improved mechanical properties. Herein, we also describe the evolution of the microwave and some early applications of microwave assistance in the biomolecular sciences and treatment of solid malignant tumors.     

Polymerization of aniline derivatives by K2Cr2O7 and production of Cr2O3 nanoparticles

Oxidative polymerization of aniline, anthranilic acid, and aniline‐co‐anthranilic acid by potassium dichromate Cr(VI) as an oxidant in acidic medium was investigated. In this study, the polymerization process of aniline, o‐anthranilic acid as well as aniline/o‐anthranlic acid using K₂Cr₂O₇ produced, coordinated Cr(III)/polyaniline (PANI), Cr(III)/polyanthranilic acid (PAA) and Cr(III)/poly aniline‐co‐anthranilic acid (PANAA). The mechanism of polymerization reaction in the presence of dichromate was hypothesized. The precursor chromium doped polymers were characterized by TGA, FT‐IR, UV‐visible, XRD analyses. Cr₂O₃ nanoparticles size were determined using TEM analysis. The calcinations process of synthesized chromium doped PANI, PAA and PANAA yields Cr₂O₃ nanoparticles 26%, 31%, and 34% wt. respectively. Rhombohedral phase of Cr₂O₃ particles in the range from 33 to 61 nm was produced from chromium/polyanthranilic acid (PAA) and chromium/poly(aniline‐co‐anthranilic acid) PANAA. UV‐ visible analysis showed that optical band gaps (E_g) of doped poly aniline and its derivatives are in the range from1.55 to 1.80 using Tacu's law. The band gap values reveal that the doped chromium emeraldine base can be used as semiconductor materials. Copyright © 2016 John Wiley & Sons, Ltd.     

Poly(o-phenylenediamine) thin film for organic solar cell applications

Poly(ortho phenylenediamine) (PoPDA) microrods with ladder-type structure are synthesized in acidic medium (pH?=?0.5) at room temperature based on a developed and facile method. The molecular structure, thermal stability, and surface morphology of the microrods-shaped PoPDA were described by different characterization techniques comprising FTIR, TGA, ¹HNMR, and SEM. Optimized thin films of PoPDA were successfully fabricated by thermal deposition method. The thin film was characterized by XRD and AFM. Au/PoPDA/p-Si/Al heterojunction diodes have been successfully fabricated. Dark current–voltage and capacitance–voltage characteristics were applied to get the particular parameters of the devices. Photovoltaic features of Au/PoPDA/p-Si/Al heterojunction at various intensities of white light illumination are studied. Under optimized conditions, the fabricated planar heterojunction solar cells utilizing a 95?±?10 nm of PoPDA film exhibited a power conversion efficiency (PCE) of ~?5.64% (J_SC?=?41.78 A/m², V_OC?=?0.36 V, and FF?=?28.11%). The relatively small FF (at room temperature with IP) and R_s of the devices designate that by increasing of the absolute temperature, the photovoltaic performance of the solar cells can be improved.