Structural,optical and electrical properties of europium picrate tetraethylene glycol complex as emissive material for OLED

A new europium complex [Eu(Pic)₂(H₂O)(EO4)](Pic)·0.75H₂O was synthesized and used as the emission material for the single layer device structure of ITO/EO4–Eu–Pic/Al, using a spin-coating technique. Study on the optical properties of the [Eu(Pic)₂(H₂O)(EO4)](Pic)·0.75H₂O complex where EO4=tetraethylene glycol and Pic=picrate anion, had to be undertaken before being applicable to the study of an organic light emitting diode (OLED). The electrical property of an OLED using current–voltage (I–V) measurement was also studied. In complex, the Eu(III) ion was coordinated with the EO4 ligand as a pentadentate mode, one water molecule, and with two Pic anions as bidentate and monodentate modes, forming a nine-coordination number. The photoluminescence (PL) spectra of the crystalline complex in the solid state and its thin film showed a hypersensitive peak at 613.5–614.9 nm that assigned to the ⁵D₀→⁷F₂ transition. A narrow band emission from the thin film EO4–Eu–Pic was obtained. The typical semiconductor I–V curve of device ITO/EO4–Eu–Pic/Al showed the threshold and turn on voltages at 1.08 and 4.6 V, respectively. The energy transfer process from the ligand to the Eu(III) ion was discussed by investigating the excitation and PL characteristics. Effect of the picrate anion on the device performance was also studied.     

Spectrofluorimetric Determination of Etodolac, Moxepril HCl and Fexofenadine HCl Using Europium Sensitized Fluorescence in Bulk and Pharmaceutical Preparations

A simple, selective and sensitive luminescence method has been developed for the assay of etodolac (I), moxepril HCl (II) and fexofenadine HCl (III) in bulk drug and pharmaceutical formulations. The method is based on the luminescence sensitization of europium (Eu³⁺) by complexation with the studied drugs. The fluorescence intensities of the products were measured at 667 nm for (I) and at 615 for (II) and (III) while exciting at 276 for all the studied drugs. The fluorescence intensity was directly proportional to the concentration over the range (20–280), (40–240) and (30–80) ng/ml with limits of detection (LOD) = 0.93, 0.92 and 0.95 μg/ml for drugs I, II and III respectively. Optimum conditions for the formation of the complex in methanol were carefully studied. The proposed method was successfully applied for the assay of the studied drugs in pharmaceutical formulations with excellent recovery.     

Machining of acrylic-based Y-branch plastic optical fiber coupler with suspended waveguide taper

An acrylic-based Y-branch plastic optical fiber (POF) with a middle suspended waveguide taper has been developed. The suspended high index contrast waveguide taper structure has been designed in such a way that it is surrounded by air-cladding. Non-sequential ray tracing has been performed on the device giving an insertion loss of 4.68 dB and coupling ratio of 50: 50. The middle waveguide taper is constructed on the acrylic block itself without using any additional optical waveguiding medium injected into the engraved taper region. Fabrication of the devices is done by producing the device structures on an acrylic block using high speed computer numerical control (CNC) machining tool. Input and output POF fibers are inserted into this device structure in such a way that they are passively aligned to the middle waveguide taper structure. The device shows an insertion loss of 5.9 dB, excess loss of 2.9 dB and a splitting ratio of 50: 50.     

5-(5-Aryl-1,3,4-oxadiazole-2-carbonyl)furan-3-carboxylate and new cyclic C-glycoside analogues from carbohydrate precursors with MAO-B, antimicrobial and antifungal activities

Cyclization of acyclic C-glycoside derivatives 1a,b to 2a,b as the major isomers, and 4a,b as the minor isomers were carried out. The isopropylidene derivatives 3a,b were prepared, as well as the hydrazide derivative 6, which was condensed with a variety of aldehydes to give hydrazones 7a-e which were also prepared from the compounds 12a-e. Acetylation of 7a,d gave the corresponding acetyl derivatives 8a,d, respectively. In addition, the dicarbonyl compound 9 was prepared in the hydrate form, which reacted with a number of aroylhydrazines to give the corresponding bisaroylhydrazones 10a-d, which were cyclized into 1,3,4-oxadiazoles 11a-d. Furthermore, two of the prepared compounds were examined to show the ability to activate MAO-B. In addition a number of prepared compounds showed antibacterial and antiviral activities.     

Gamma irradiation increases the antioxidant properties of Tualang honey stored under different conditions

This study was conducted to evaluate the effects of evaporation, gamma irradiation and temperature on the total polyphenols, flavonoids and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activities of Tualang honey samples (n = 14) following storage over three, six or twelve months. The mean polyphenol concentrations of the six gamma irradiated honey samples at three, six and twelve months, respectively, were 96.13%, 98.01% and 102.03% higher than the corresponding values of the eight non-gamma irradiated samples. Similarly, the mean values for flavonoids at three, six and twelve months were 111.52%, 114.81% and 110.04% higher, respectively, for the gamma irradiated samples. The mean values for DPPH radical-scavenging activities at three, six and twelve months were also 67.09%, 65.26% and 44.65% higher, respectively, for the gamma irradiated samples. These data indicate that all gamma irradiated honey samples had higher antioxidant potential following gamma irradiation, while evaporation and temperature had minor effects on antioxidant potential.     

Classical Reactive Molecular Dynamics Implementations: State of the Art

Reactive molecular dynamics (RMD) implementations equipped with force field approaches to simulate both the time evolution as well as chemical reactions of a broad class of materials are reviewed herein. We subdivide the RMD approaches developed during the last decade as well as older ones already reviewed in 1995 by Srivastava and Garrison and in 2000 by Brenner into two classes. The methods in the first RMD class rely on the use of a reaction cutoff distance and employ a sudden transition from the educts to the products. Due to their simplicity these methods are well suited to generate equilibrated atomistic or material‐specific coarse‐grained polymer structures. In connection with generic models they offer useful qualitative insight into polymerization reactions. The methods in the second RMD class are based on empirical reactive force fields and implement a smooth and continuous transition from the educts to the products. In this RMD class, the reactive potentials are based on many‐body or bond‐order force fields as well as on empirical standard force fields, such as CHARMM, AMBER or MM3 that are modified to become reactive. The aim with the more sophisticated implementations of the second RMD class is the investigation of the reaction kinetics and mechanisms as well as the evaluation of transition state geometries. Pure or hybrid ab initio, density functional, semi‐empirical, molecular mechanics, and Monte Carlo methods for which no time evolution of the chemical systems is achieved are excluded from the present review. So are molecular dynamics techniques coupled with quantum chemical methods for the treatment of the reactive regions, such as Car–Parinello molecular dynamics.     

Online affine model identification of nonlinear processes using a new adaptive neuro-fuzzy approach

This paper presents a new online identification algorithm to drive an adaptive affine dynamic model for nonlinear and time-varying processes. The new algorithm is devised on the basis of an adaptive neuro-fuzzy modeling approach. Two adaptive neuro-fuzzy models are sequentially identified on the basis of the most recent input-output process data to realize an online affine-type model. A series of simulation test studies has been conducted to demonstrate the efficient capabilities of the proposed algorithm to automatically identify an online affine-type model for two highly nonlinear and time-varying continuous stirred tank reactor (CSTR) benchmark problems having inherent non-affine dynamic model representations. Adequacy assessments of the identified models have been explored using different evaluation measures, including comparison with an adaptive neuro-fuzzy inference system (ANFIS) as the pioneering and the most popular adaptive neuro-fuzzy system with powerful modeling features.     

A new image cipher in time and frequency domains

Recently, various encryption techniques based on chaos have been proposed. However, most existing chaotic encryption schemes still suffer from fundamental problems such as small key space, weak security function and slow performance speed. This paper introduces an efficient encryption scheme for still visual data that overcome these disadvantages. The proposed scheme is based on hybrid Linear Feedback Shift Register (LFSR) and chaotic systems in hybrid domains. The core idea is to scramble the pixel positions based on 2D chaotic systems in frequency domain. Then, the diffusion is done on the scrambled image based on cryptographic primitive operations and the incorporation of LFSR and chaotic systems as round keys. The hybrid compound of LFSR, chaotic system and cryptographic primitive operations strengthen the encryption performance and enlarge the key space required to resist the brute force attacks. Results of statistical and differential analysis show that the proposed algorithm has high security for secure digital images. Furthermore, it has key sensitivity together with a large key space and is very fast compared to other competitive algorithms.     

Topological,morphological and optical properties of Gamma irradiated Ni (II) tetraphenyl porphyrin thin films

Thermal evaporation technique was used to prepare NiTPP Thin films at room temperature. The prepared films were divided into two groups; the first group was as-deposited films, and the second group was irradiated in gamma cell type ⁶⁰Co source at room temperature with total absorbed dose of 150 kGy in air. All films were identified by X-ray diffraction (XRD), Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM) before and after exposed to gamma radiation. The spectrophotometric measurement of transmittance and reflectance were used to investigate the optical properties at normal incidence of light in the wavelength range 200–2500 nm for as-deposited and gamma-irradiated films. Optical constants (refractive index n, and absorption index k) of as-deposited and irradiated films have been obtained in the wavelength range 200–2500 nm for all the samples. The single oscillator energy (E_o), the dispersion energy (E_d), the high frequency dielectric constant (ε_∞), the lattice dielectric constant (ε_L) and the ratio of the free charge carrier concentration to the effective mass (N/m^?) were estimated for each group. The absorption analysis has been also performed to determine the type of electronic transition and the optical energy gap.     

Attributed Grammatical Evolution with Lookahead for the Multiple Knapsack Problem

This paper presents an Attribute Grammar with Lookahead (AG+LA) approach, a technique to solve heavily constrained Multiple Knapsack Problem. This approach incorporates a form of lookahead into the mapping process of Grammatical Evolution (GE) using Attribute Grammar (AG) to focus only on feasible solutions, thereby avoiding issues such as repeated remapping and introns, both of which are limitations of previous approaches based on AG. We also present AG+LAE (AG+LA with an efficiency measure to bias the search towards the most efficient, i.e., best value, objects), the successor of AG+LA where a biasing process is incorporated using problem specific knowledge to significantly improve the performance of its predecessor, both in terms of the number of evaluations required and the quality of solutions obtained. Degenerate code, as used in DNA, is code that uses redundancy, so that different codons can represent the same thing. Many developmental systems, such as GE, use a degenerate encoding to help promote neutral mutations, that is, minor genetic changes that do not result in a phenotypic change. While early work in GE suggested that some level of degeneracy was important, it does come at the cost of increasing the size of the search space. Duplicate Elimination techniques, as opposed to degenerate encoding, are employed in decoder-based Evolutionary Algorithms to ensure that the newly generated solutions are not already contained in the current population. The results and analysis show that it is crucial to incorporate duplicate elimination to improve the performance of both approaches, while the reduced level of degeneracy is crucial only for AG+LA.