Triacetic acid lactone as a bioprivileged molecule in organic synthesis

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New double negative and positive temperature coefficients of conductive EPDM rubber TiC ceramic composites

In this paper, we have successfully prepared ethylene-propylene-diene monomer (EPDM)/TiC composites as thermistors, with new double negative and positive temperature coefficients of conductivity (NTCC/PTCC). EPDM composites loaded with 50 phr HAF carbon black and different concentrations of TiC were prepared. This study focuses on the effect of TiC content on the vulcanization process, the network structure and the electrical and thermal properties of EPDM/TiC composites. The effect of TiC on the network structure was evaluated e.g. the curing process, the characteristic time constant during vulcanization, the volume fraction of rubber, gel fraction, interparticle distance between conductive particles, the extent of TiC reinforcement in the rubber matrix and molecular weight between cross-linking through experimental and affine-phantom models. The effects of TiC content on the percolation theory, electrical conductivity, conducting mechanism of conductivity, conducting hysteresis and I-V characteristics were also studied, as well as its TiC on the (NTCC/PTCC), thermoelectric power, dielectric constant and thermal conductivity. Stability and reproducibility of the thermal cycles for heating element applications was tested. Specific heat and the amount of heat transfer by radiation and convection as a function of TiC content was calculated using both the calorimetric technique and a theoretical model. It was proved that TiC improves the network structure, electrical and thermal properties of EPDM composites for practical applications.     

Spectroscopic and Quantum Mechanical Studies of Substituted Anilines and their Charge-Transfer Complexes with Iodine in Different Solvents

Summary. Equilibrium constants and molar extinction coefficients for 1:1 charge-transfer complexes between 2-hydroxyaniline (HA), 5-chloro-2-hydroxyaniline (CHA), and 4-bromo-2,6-dimethylaniline (BMA) as donors and iodine, as a typical σ-acceptor were determined spectrophotometrically in chloroform, dichloromethane, and carbontetrachloride solutions. Spectral characteristics and formation constants are discussed in terms of donor molecular structure and solvent polarity. The stoichiometry of the complexes was established to be 1:1. For this purpose, optical data were subjected to the form of the Rose-Drago equation for 1:1 equilibria. Electronic absorption spectra of the studied anilines were measured in different solvents. Spectral data were reported and band maxima were assigned to the appropriate molecular orbital transitions (π–π^* and n–π^* electronic transition). Solvent effects on the electronic transitions were discussed. Optimized geometry of the studied anilines was obtained at B3LYP/6-31 + G(d). The effect of the electronic factors of the substituents on the geometrical parameters of the ring has been explored. Geometrical values of the ring deviate from the regular hexagonal ring. Intramolecular H-bonds in HA and CHA have been computed at B3LYP/6-31 + G(d) and MP2/6-31 + G(d) levels. The H-bonding distance was calculated to be 2.105 ? in HA and 2.127 ? in CHA. Abstracted from her M.Sc. thesis     

Reactions of carbamoylated amino enones with 3-substituted chromones for the preparation of 2-pyridones and chromeno[4,3-b]pyridine-2,5-diones

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Musa sp. Leaves Extract Ameliorates the Hepato-Renal Toxicities Induced by Cadmium in Mice

Heavy metals intoxication causes several health problems that necessitate finding new protective and therapeutic approaches. This study aimed to evaluate the impact of Musa sp. leaves extract (MLE) on hepato-renal toxicities induced by cadmium (Cd) in male mice. The phytochemical screening, metal chelating activity (MCA), and the median lethal dose (LD₅₀) of MLE were determined. Fifty CD-1 male mice were used and intraperitoneally (i.p.) injected with MLE (1000 to 5000 mg/kg b.wt) for MLE LD₅₀ determination. Another 50 mice were used for evaluating the effect of MLE on Cd toxicity. Blood samples were collected for hematological, liver, and kidney functions assessments. Liver tissue homogenates were used for determination of oxidant/antioxidant parameters. Liver and kidney tissues were harvested for histopathological and molecular investigations. MLE showed potent in vitro antioxidant activities. The MCA and LD₅₀ of the MLE were 75 µg/mL and 3000 mg/kg b.wt, respectively. MLE showed beneficial therapeutic activity against hepato-renal toxicities in Cd-intoxicated mice, evidenced by improving the hematological, biochemical, histopathological, and molecular alterations.     

A new approach for modelling the damped Helmholtz oscillator:applications to plasma physics and electronic circuits

In this paper,a new approach is devoted to find novel analytical and approximate solutions to the damped quadratic nonlinear Helmholtz equation(HE)in terms of the Weiersrtrass elliptic function.The exact solution for undamped HE(integrable case)and approximate/semi-analytical solution to the damped HE(non-integrable case)are given for any arbitrary initial conditions.As a special case,the necessary and sufficient condition for the integrability of the damped HE using an elementary approach is reported.In general,a new ansatz is suggested to find a semi-analytical solution to the non-integrable case in the form of Weierstrass elliptic function.In addition,the relation between the Weierstrass and Jacobian elliptic functions solutions to the integrable case will be derived in details.Also,we will make a comparison between the semi-analytical solution and the approximate numerical solutions via using Runge-Kutta fourth-order method,finite difference method,and homotopy perturbation method for the first-two approximations.Furthermore,the maximum distance errors between the approximate/semi-analytical solution and the approximate numerical solutions will be estimated.As real applications,the obtained solutions will be devoted to describe the characteristics behavior of the oscillations in RLC series circuits and in various plasma models such as electronegative complex plasma model.     

Plasma with two-negative ions and immobile dust particles: planar and non-planar ion-acoustic wave propagation

By using the hydrodynamic equations of positive and two negative ions, Boltzmann electron density distribution, and Poisson equation with immobile positive/negative dust particles, a cylindrical Korteweg-de Vries (CKdV) equation is derived for small but finite amplitude ion-acoustic waves. At the critical total negative ion concentration and/or the critical density rate of the second-negative ions, the pulses collapse at this limit as nonlinearity fails to balance dispersion. Then the CKdV equation is not appropriate to describe the system. Therefore, the modified CKdV (MCKdV) and extended CKdV (ECKdV) equations are derived at the critical plasma compositions and in the vicinity of the critical plasma compositions, respectively. The physical parameters of two plasma environments (e.g., Xe⁺–F^-–SF₆^-_{6}^{-} and Ar⁺–F^-–SF₆^-_{6}^{-} plasmas) are examined on the wave phase velocity and the nonlinear localized pulse profile. The latter should satisfy necessary condition to exist. The localized pulse of Ar⁺–F^-–SF₆^-_{6}^{-} plasma is much spiky than Xe⁺–F^-–SF₆^-_{6}^{-} plasma. Thus, the mass ratio of the negative-to-positive ions is focused upon and it emphasizes to play an important role on the pulse profile. Dependence of the geometrical divergence on the pulse profile is also investigated, which indicates that the localized pulse damps with time. The implications of our results agrees with the experimental observations.     

Optical properties of nanostructure boron doped NiO thin films

Boron doped NiO films were prepared by sol–gel method. The effects of B content on the morphological and optical properties of NiO films were studied with atomic force microscopy, and optical characterization method. The average transmittance at the visible region is reached to 75 % for lower doped films (0.1 and 0.2 % B), whereas, the recorded average value of transmittance was about 62 % for doped film with 1 % B throughout the region. The optical energy gap value for pure NiO film was found to be 3.73 eV. These values were affected by B doping with non-monotonic variation and reached to 3.64 eV for 0.1 % B doped NiO. Also, the refractive index dispersion and dielectric constants of the NiO films were studied throughout the investigated range of wavelengths. The obtained results indicate that the optical parameters of the NiO film are controlled with boron doping.     

Adsorptive characteristics of some metal ions on chitosan/zirconium phosphate/silica decorated graphene oxide

Journal of Radioanalytical and Nuclear Chemistry - Graphene oxide/chitosan/zirconiumphosphate/silicate (GO/CS/ZrP/Si) as a novel nano-composite has highly adsorption of 134Cs, 60Co, 152, 154Eu and...     

Synthesis,Nanoformulations, and In Vitro Anticancer Activity of N-Substituted Side Chain Neocryptolepine Scaffolds

The naturally occurring neocryptolepine (5-Methylindolo [2,3-b]quinoline) and its analogs exhibited prominent anticancer and antimalarial activity. However, the main problem of this class of compounds is their poor aqueous solubility, hampering their bioavailability and preventing their clinical development. To overcome the problem of insolubility and to improve the physicochemical and the pharmacological properties of 5-Methylindolo [2,3-b]quinoline compounds, this work was designed to encapsulate such efficient medical compounds into mesoporous silica oxide nanoemulsion (SiO₂NPs). Thus, in this study, SiO₂NPs was loaded with three different concentrations (0.2 g, 0.3, and 0.6 g) of 7b (denoted as NPA). The findings illustrated that the nanoparticles were formed with a spherical shape and exhibited small size (less than 500 nm) using a high concentration of the synthesized chemical compound (NPA, 0.6 g) and good stabilization against agglomeration (more than −30 mv). In addition, NPA-loaded SiO₂NPs had no phase separation as observed by our naked eyes even after 30 days. The findings also revealed that the fabricated SiO₂NPs could sustain the release of NPA at two different pH levels, 4.5 and 7.4. Additionally, the cell viability of the produced nanoemulsion system loaded with different concentrations of NPA was greater than SiO₂NPs without loading, affirming that NPA had a positive impact on increasing the safety and cell viability of the whole nanoemulsion. Based on these obtained promising data, it can be considered that the prepared NPA-loaded SiO₂NPs seem to have the potential for use as an effective anticancer drug nanosystem.