Synthesis and electroluminescence properties of zinc(2,2′ bipyridine)8-hydroxyquinoline

New electroluminescent material, namely zinc(2,2′ bipyridine)8-hydroxyquinoline [Zn(Bpy)q] has been synthesized and characterized. A solution of Zn(Bpy)q showed absorption maxima at 382 nm and 342 nm in toluene solution attributed to π − π transition. The photoluminescence spectrum in toluene solution showed peak at 545 nm. The material was stable up to 350 °C. Organic light emitting diode (OLED) fabricated with the structure ITO/α-NPD/Zn(Bpy)q/Alq₃/LiF/Al exhibits a broad electroluminescence peak at 548 nm. The maximum current efficiency of OLED was 1.34 cd/A at 5 V and the maximum power efficiency 0.84 lm/W at 5 V.     

Surfactant chain length effects on the light emission of tris(2,2'-bipyridyl)ruthenium(II)/ tripropylamine electrogenerated chemiluminescence

The effects of nonionic surfactant chain length on the properties of tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)3(2+) where bpy = 2,2'-bipyridine) electrochemiluminescence (ECL) have been investigated. The electrochemistry, photophysics, and ECL of Ru(bpy)3(2+) in the presence of a series of nonionic surfactants are reported (Triton X-100, 114, 165, 405, 305, and 705-70). These surfactants differ in the number of poly(ethylene oxide) units incorporated into the surfactant molecule. The anodic oxidation of Ru(bpy)3(2+) produces ECL in the presence of tri-n-propylamine (TPrA) in aqueous surfactant solution. Increases in ECL efficiency (> or = 5-fold) and TPrA oxidation current (> or = 2-fold) have been observed in surfactant media. Slight decreases in ECL intensity are observed as the chain length of the nonionic surfactant increases. The data supports adsorption of surfactant on the electrode surface, thus facilitating TPrA and Ru(bpy)3(2+) oxidation and leading to higher ECL efficiencies.     

Photoswitching of electron transfer property of diarylethene–viologen linked molecular layer constructed on a hydrogen-terminated Si(111) Surface

An organic monolayer with diarylethene and viologen moieties as a photochromic and an electroactive group, respectively, was constructed on a hydrogen-terminated Si(111) surface by sequential surface reactions. Photoswitching behaviour of electron transfer from the Si electrode to viologen moiety, larger and smaller current after UV and visible irradiation, respectively, was observed. This photoswitching behaviour can be explained by a change in molecular conductivity of diarylethene moiety, which separates Si surface and viologen moiety, as a result of ring closing and opening induced by UV and visible irradiation, respectively.     

The inhibition of 4-(2′-amino-5′-methylphenylazo) antipyrine on corrosion of mild steel in HCl solution

The effect of 4-(2′-amino-5′-methylphenylazo) antipyrine (AMPA) on the corrosion of mild steel in a 2 M HCl solution was studied using weight loss and potentiodynamic polarization techniques. All of the data reveal that AMPA acts as an inhibitor in the acid environment; furthermore, polarization data show that the compound behaves as a mixed-type inhibitor. It was found that the inhibition efficiency increases with an increase in AMPA concentration but decreases with an increase in temperature. Flory–Huggins adsorption isotherm and El Awady thermodynamic–kinetic model fit the experimental data of the studied compound. Thermodynamic parameters for corrosion and adsorption processes were obtained from experimental data of the temperature studies.     

Effects of Modified Atmosphere Packaging with Various Carbon Dioxide Composition on Biogenic Amines Formation in Indian Mackerel (Rastrelliger kanagurta) stored at 5 ± 1°C

The profile of major biogenic amines was investigated in Indian mackerel packed in modified atmosphere for up to 12 days at 5 ± 1°C. Beheaded and gutted Indian mackerel was packed under different carbon dioxide compositions to study the effects on biogenic amines formation. The treatments were control air (C), vacuum packaging (VP), 30% CO₂/65% N₂/5% O₂ (M30C), 60% CO₂/35% N₂/5% O₂ (M60C), 80% CO₂/15% N₂/5% O₂ (M80C) and 100% CO₂ (M100C). Each amine responded differently to different CO₂ levels. After 12 days of storage, concentrations of histamine were reduced by 6.4%, 8.5%, 70.3%, 78.8% and 90.2% in fish packed under VP, M30C, M60C, M80C and M100C, respectively as compared with control air. Changes in putrescine and cadaverine showed a similar pattern. Gas mix of M30C and VP stimulated the formation of tyramine reaching 203 and 172 ppm, respectively. Higher composition of CO₂ had a significant inhibitory effect on tyramine concentration (p < 0.05). There were parallel increases of putrescine and spermidine in C, VP and M30C. No significant effect of CO₂ was observed on spermine (p > 0.05). After 9 days of storage, more than 300 ppm of histamine was detected in mackerel packed in VP and M30C; therefore, these atmospheres pose a histamine intoxication risk. Copyright © 2013 John Wiley & Sons, Ltd.     

Electropolymerization of Cu-(N,N′-bis(3-methoxysalicylidene)-2-aminobenzylamine) on platinum electrode: Application to the electrocatalytic reduction of hydrogen peroxide

The complex of copper (II) with N,N′-bis(3-methoxysalicylidene)-2-aminobenzylamine (H₂L) was synthesized and characterized by elemental analysis, magnetic susceptibility, UV–vis. and FT-IR spectroscopy. The results showed that the tetradentate ligand coordinated to the Cu(II) ion through the azomethine nitrogen and phenolic oxygen atoms. The prepared complex [CuL] was electropolymerized on platinum electrode surface in a 0.1 mol dm⁻³ solution of lithium perchlorate in acetonitrile by cyclic voltammetry between 0 and 1.6 V vs. Ag/Ag⁺. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), conductance measurements, FT-IR and SEM were used to characterize polymer film of Cu(II) complex. The reduction of hydrogen peroxide on poly[CuL] has been investigated mainly in phosphate buffer medium (pH 7.2), between 0 and −0.8 V versus Ag/Ag⁺ at a scan rate 0.1 V s⁻¹.     

Effects of rigid structures containing (meth)acrylate monomers and crosslinking agents with different chain length on the morphology and electro-optical properties of polymer-dispersed liquid crystal films

ABSTRACT

This contribution investigates the preparation of polymer-dispersed liquid crystal (PDLC) films based on meth(acrylate) monomers containing rigid structures. The current study specifically focuses on comparison of the monomers on the basis of meth(acrylate) side group, flexible/rigid structures and rigidity. We find that methacrylate monomers exhibit more preferable electro-optic properties than that of the acrylate monomers. Furthermore, through the systematic variation of rigidity, composition of the monomers and chain length of crosslinking agents, both the morphologies and electro-optic properties of these films are found to be adjustable. A composite film is demonstrated by employing moderately rigid monomer (tetrahydrofurfuryl methacrylate) with low driving voltage (21.0?V) and high contrast ratio (87.5). Therefore, the studies here provide a new approach to optimize the electro-optical properties of the PDLC films by introducing monomers with rigid structures.     

Effects of substitution of X (X=rhenium,chromium and zirconium) on the properties of Co7Mo6 μ phase: A first‐principles study

The effects of three typical refractory elements (rhenium, chromium and zirconium) substituting the molybdenum atom in Co₇Mo₆ μ phase were investigated using first‐principles calculations based on the density functional theory (DFT). Energy (including binding energy and defect energy) and electronic structures (including density of states and charge density) of Co₇Mo₅X (X=rhenium, chromium and zirconium) were calculated. The optimized lattice structure of Co₇Mo₆ agrees well with the experimental data. The calculated results show the bonding between doped rhenium atom and its nearest neighbor molybdenum and cobalt atoms gets visibly stronger, contributing to the good stability of the unit cell. Neverthless, the bonding between chromium and its nearest neighbor molybdenum and cobalt is weaker, and the zirconium‐molybdenum and zirconium‐cobalt bonds are much weaker. The results reveal rhenium tends to participate in the formation of μ phase, but zirconium and chromium atoms are not prone to concentrate in μ phase.     

A cell‐based smoothed discrete shear gap method (CS‐FEM‐DSG3) based on the C0‐type higher‐order shear deformation theory for dynamic responses of Mindlin plates on viscoelastic foundations subjected to a moving sprung vehicle

A cell‐based smoothed discrete shear gap method (CS‐FEM‐DSG3) based on the first‐order shear deformation theory (FSDT) was recently proposed for static and dynamic analyses of Mindlin plates. In this paper, the CS‐FEM‐DSG3 is extended to the C⁰‐type higher‐order shear deformation plate theory (C⁰‐HSDT) and is incorporated with damping–spring systems for dynamic responses of Mindlin plates on viscoelastic foundations subjected to a moving sprung vehicle. At each time step of dynamic analysis, one four‐step procedure is performed including the following: (1) transformation of the weight of a four‐wheel vehicle into the sprung masses at wheels; (2) dynamic analysis of the sprung mass of wheels to determine the contact forces; (3) transformation of the contact forces into loads at nodes of plate elements; and (4) dynamic analysis of the plate elements on viscoelastic foundations. The accuracy and reliability of the proposed method are verified by comparing its numerical solutions with those of other available numerical results. Copyright © 2014 John Wiley & Sons, Ltd.     

Effects of Nd and B contents on the thermal stability of nanocomposite (Nd,Zr)2Fe14B/α-Fe magnets

The effects of Nd and B contents on the microstructure and thermal stability of nanocomposite (Nd,Zr)₂Fe₁₄B/α-Fe magnets have been investigated. It is shown that for Nd_xFe_93−xZr₁B₆ (x = 9–11) alloys, the volume fraction of Nd₂Fe₁₄B increases with increasing Nd content, and the sample with x = 10 exhibits the optimal microstructure and thermal stability. Though the room-temperature _iH_c of Nd₁₁Fe₈₂Zr₁B₆ sample is the highest, it decreases more rapidly than that of Nd₁₀Fe₈₃Zr₁B₆ as temperature increases, indicating the deterioration of the temperature coefficient β. For Nd₁₀Fe_89−yZr₁B_y (y = 5–8) alloys, the remanence and the temperature coefficient α deteriorate with increasing B content. The coercivity and the temperature coefficient β first improve with increasing B content, reaching the optimal values at y = 7, then deteriorate with further increasing B. Coarse grains and the Fe₃B phase are observed in the Nd₁₀Fe₈₁Zr₁B₈ alloy.     

Effects of growth conditions on the domain structure and dielectric properties of (1 − x)Pb(Sc1/2Nb1/2)O3–xPbTiO3 single crystals

The studies of the (1 − x)Pb(Sc_1/2Nb_1/2)O₃–xPbTiO₃ (PSN–PT) single crystals reveal that the chemical and physical properties of the materials are affected by the growth conditions. By the measurements of the dielectric constant as a function of temperature upon cooling, it is found that crystals grown from the same charged stoichiometric composition (x = 0.425), but under different flux environments (i.e. the composition of flux and the flux to PSN–PT ratios are varied), show anomalies (i.e. phase transitions) at different temperatures. This phenomenon is attributed to the complex local chemical structure of the PSN–PT solid solution single crystals with B-site random occupancy of three different cations (Sc³⁺, Nb⁵⁺ and Ti⁴⁺). The dielectric and domain structure of the PSN–PT crystals with composition near the morphotropic phase boundary (MPB) are investigated, showing much more complex situations compared with Pb(Sc_1/2Nb_1/2)O₃.