A manganese Schiff base complex immobilized on copper–ferrite magnetic nanoparticles as an efficient and recyclable nanocatalyst for selective oxidation of alcohols

A magnetically recoverable nanocatalyst was synthesized by covalent binding of a Schiff base ligand, namely N,N′-bis(Salicylidene)-1,3-diaminopropane-2-ol (H₂salpn), onto the surface of silica-coated magnetic CuFe₂O₄ nanoparticles, followed by complexation with MnCl₂. The resulting core–shell nanoparticles were characterized by spectroscopic and microscopic methods, including FTIR, XRD, VSM, TGA elemental analysis, TEM, and SEM. The Mn content was determined by ICP analysis. The nanoparticles were investigated as a catalyst for the selective oxidation of alcohols to the corresponding carbonyl compounds with tertiary-butyl hydrogen peroxide. The catalyst can be magnetically separated for reuse, with no noticeable loss of activity in subsequent reaction cycles. FTIR, VSM, and leaching experiments after three successive cycles confirmed that the catalyst was strongly anchored to the magnetic nanoparticles. A suitable mechanism for the reaction is proposed.     

Cyclic Olefin Copolymer Interleaves for Thermally Mendable Carbon/Epoxy Laminates

Thin cyclic olefin copolymer (COC) foils were used as intrinsic thermoplastic healing agents in carbon fiber (CF)-reinforced epoxy laminates. COC films were produced by hot pressing and were interleaved in the interlaminar regions between each EP/CF lamina, during the hand layup fabrication of the laminates. Three samples were produced, i.e., the neat EP/CF laminate without COC, and two laminates containing COC layers with a thickness of 44 μm and 77 μm, respectively. It was observed that the fiber volume fraction decreased, and the porosity increased with the introduction of COC layers, and this effect was more evident when thick films were used. These two effects, combined with the sub-optimal adhesion between COC and EP, caused a decrease in the mechanical properties (i.e., the elastic modulus, flexural strength, interlaminar shear strength and interlaminar fracture toughness) of the laminates. Specimens subjected to mode I interlaminar fracture toughness test were then thermally mended under pressure by resistive heating, through the Joule effect of conductive CFs. A temperature of approximately 190 °C was reached during the healing treatment. The healing efficiency was evaluated as the ratio of critical strain energy release rate (G_IC) of the healed and virgin specimens. Healed specimens containing COC layers of 44 μm and 77 μm exhibited a healing efficiency of 164% and 100%, respectively. As expected, the healing treatment was not beneficial for the neat EP/CF laminate without COC, which experienced a healing efficiency of only 2%. This result proved the efficacy of COC layers as a healing agent for EP/CF laminates, and the effectiveness of resistive heating as a way to activate the intrinsic healing mechanism.     

Design and synthesis of 2,4-dioxochroman-pyridinium-phenylacetamide derivatives as new anti-Alzheimer agents: in vitro and in silico studies

2,4-Dioxochroman-pyridinium-phenylacetamide derivatives 7a–n were synthesized and evaluated for their in vitro cholinesterase (ChE) inhibitory activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). Obtained results demonstrated that, among the synthesized compounds, two compounds, 7j and 7k , were more potent than the standard drug donepezil against BuChE and did not show cytotoxicity and carcinogenicity. Furthermore, through molecular modeling and molecular dynamic studies. we showed that these compounds can be located deep in the gorge cavity of BuChE and that they interacted with catalytic residues, acyl, and cholin-binding pockets of this enzyme. Support information     

Regioselective synthesis of fused ring heterocyclic derivatives of ketene aminals and their biological activities

A regioselective and convenient methodology was developed to synthesize heterocyclic derivatives, bearing imidazole, piperidines, and azepines rings. The N-arylnitrones derived from 3-formylchromones were selected to react with heterocyclic ketene aminal to furnish the structurally attractive and pharmacologically important fused ring heterocycles. The N-arylnitrone moiety of 3-formylchromone was used to activate the formyl group for regioselective fused ring heterocycles synthesis, whereas, the effect of substituents at aryl functionality of nitrones were studied to improve the yield of target fused ring heterocyclic products. The synthesized compounds (10-12) were evaluated for their in vitro cytotoxic and antifungal influences. In cytotoxic (brine shrimp lethality) assay, compound 11e was found to be active with LD₅₀ = 4.1 × 10⁻⁶ μg/mL.     

A general finite plasticity model with a smooth elastic-plastic transition and isotropic hardening. A finite element formulation and numerical verification

A number of approaches for finite deformation elastoplasticity with different classes of kinematic decomposition have been published in the literature (e.g. additive split of the Lagrange strain, multiplicative split of the deformation gradient, additive split of the rate of deformation, etc.). In the present work, a general theoretical framework for modeling a smooth elastic inelastic transition for large deformations of rate independent elastic-plastic and rate dependent elastic-viscoplastic materials has been proposed. It is well known that in classical rate independent elastic-plastic models the transition from the elastic regime to the plastic regime is rather sharp, while in the present model this transition is smooth and both rate independent and rate dependent models are characterized by overstress. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Cost,revenue and profit efficiency measurement in DEA: A directional distance function approach

Estimation of efficiency of firms in a non-competitive market characterized by heterogeneous inputs and outputs along with their varying prices is questionable when factor-based technology sets are used in data envelopment analysis (DEA). In this scenario, a value-based technology becomes an appropriate reference technology against which efficiency can be assessed. In this contribution, the value-based models of Tone (2002) are extended in a directional DEA set up to develop new directional cost- and revenue-based measures of efficiency, which are then decomposed into their respective directional value-based technical and allocative efficiencies. These new directional value-based measures are more general, and include the existing value-based measures as special cases. These measures satisfy several desirable properties of an ideal efficiency measure. These new measures are advantageous over the existing ones in terms of (1) their ability to satisfy the most important property of translation invariance; (2) choices over the use of suitable direction vectors in handling negative data; and (3) flexibility in providing the decision makers with the option of specifying preferable direction vectors to incorporate their preferences. Finally, under the condition of no prior unit price information, a directional value-based measure of profit inefficiency is developed for firms whose underlying objectives are profit maximization. For an illustrative empirical application, our new measures are applied to a real-life data set of 50 US banks to draw inferences about the production correspondence of banking industry.     

Effect of Anisotropic Ion Pressure on Solitary Waves in Magnetized Dusty Plasmas

The propagation of linear and nonlinear dust ion acoustic waves (DIAWs) are studied in a collisionless magnetized plasma which consists of warm ions having anisotropic thermal pressure, nonthermal (energetic) electrons and static dust particles of positive and negative charge polarity. The anisotropic ion pressure is defined using double adiabatic Chew‐Golberger‐Low (CGL) theory. In the linear regime, the propagation properties of the two possible modes are investigated via ion pressure anisotropy, dust particle polarity and nonthermality of electrons. Using reductive method Zakharov‐Kuznetsov (ZK) equation is derived for the propagation of two dimensional electrostatic dust ion acoustic solitary waves in dusty plasmas. It is found that both compressive and rarefactive solitons are formed in presence of nonthermal electrons using Cairn's distribution [R.A. Cairns, A.A. Mamun, R. Bingham, R.O. Dendy, R. Bostrom, C.M.C. Nairn and P.K. Shukla, Geophys.Res. Lett. 22 , 2709 (1995)] in the system. The ion pressure anisotropy, nonthermality of electrons and charge polarity of the dust particles have significant effects on the amplitude and width of the dust ion acoustic solitary waves in such anisotropic nonthermal magnetized dusty plasmas. The numerical results are also presented for illustration. Our finding is applicable to space dusty plasma regimes having anisotropic ion pressure and nonthermal electrons. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Defect modes properties in periodic lossy multilayer containing negative index materials with symmetric and asymmetric geometric structures

In this paper, the characteristic matrix method is used to study the propagation of electromagnetic waves through one-dimensional lossy photonic crystals composed of negative and positive refractive index material layers with symmetric and asymmetric geometric structures with a defect layer at the center of the structure. First, the positive index material defect layer is considered, and the effects of the polarization and the angle of incidence on the defect mode in the transmission spectra of the both structures are investigated. The results show that the number of the defect modes in the transmission spectra depends on the geometry (symmetric or asymmetric) of the structure. In addition, it is shown that the defect mode frequency increases as the angle of incidence increases. This property is independent of the geometry of the structure. Then, for normal incidence, the negative index material defect layer is considered, and the properties of defect modes for both structures are investigated. The results can lead to designing new types of transmission narrow filters.     

Third-order nonlinear optical properties of silver nanoparticles mediated by chitosan

Silver nanoparticles in chitosan medium were prepared by the chemical reduction method. Silver nitrate and hydrazine were used as the precursor and reducing agent in the present of chitosan as a natural host polymer. The samples are characterized by UV–visible spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The measurements of nonlinear optical properties were defined by Z-scan technique using green CW laser beam operated at 532 nm wavelengths. Thermal effect has a dominant role in the overall material nonlinearity with CW laser. It is shown that the synthesized samples have a negative nonlinear refractive index.     

Optical solitons in birefringent fibers with spatio-temporal dispersion

This paper studies the propagation of solitons through birefringent fibers in the presence of spatio-temporal dispersion. Both Kerr and parabolic laws of nonlinearity are addressed. The exact 1-soliton solutions are obtained. There are several constraint conditions that ensure soliton solutions are derived. Three types of solitons are obtained: bright, dark and singular solitons.