Suppressing the spiking of a synchronized array of Izhikevich neurons

Nonlinear Dynamics - The aim of this research work is to investigate the synchronization and desynchronization of an array of non-identical Izhikevich neurons in a star-like configuration. Both...     

Anti-atherosclerotic activity of Betulinic acid loaded polyvinyl alcohol/methylacrylate grafted Lignin polymer in high fat diet induced atherosclerosis model rats

Betulinic acid is one such natural pentacyclic triterpenoid compound, holding various pharmacological properties but its poor bioavailability is the only limitation. One of the biological macromolecules such as Lignin is a plant-derived aromatic, eco-friendly and low-cost polymer that certainly self-assembles into nano-sized colloids. Therefore, onto the current investigation, we increased the bioavailability of betulinic acid by coating on to a nanopolymer prepared with poly vinyl alcohol, lignins and methyl acrylate. Betulinic acid loaded polyvinyl alcohol/ethylacrylate grafted Lignin polymer (PVA/Lig-g-MA) nanoformulation was characterized using FTIR, XRD, SEM and TEM analysis and also the drug entrapment, in vitro drug releasing capacity was done to examine the efficiency of the nanoformulation of a drug. The MTT assay was evaluated the cytotoxicity of synthesized nanoformulation against normal endothelial cells HUVEC and HAPEC to confirm the side effects of the drug. The anti-atherosclerotic property of the nanoformulation was ascertained in both in vitro condition (with HUVEC and HPAEC) and in vivo studies (with Wistar rats). As a result, the characterization studies and in vitro studies clearly confirmed the Betulinic acid loaded PVA/Lig-g-MA nanoformulation is an ideal nanopolymer and it doesn’t cause any cytotoxic effect in normal endothelial cells. It also decreased the lipopolysaccharides induced inflammation through the down-regulation of NFκB and MAP/JNK signaling molecule expressions. Following in vivo results confirmed the synthesized nanoformulation effectively decreased the hyperchlostremia, inflammation and vasoconstriction, which induced over high fat diet. The results of histopathological analysis of cardiac tissues also confirmed the cardioprotective role of synthesized nanoformulation. Overall, both the in vitro and in vivo studies authentically proven the Betulinic acid loaded PVA/Lig-g-MA nanoformulation would be a potent cost effective anti-atherosclerotic nanodrug.     

Efficient removal of iodine and chromium as anionic species from radioactive liquid waste using prepared iron oxide nanofibers

Journal of Radioanalytical and Nuclear Chemistry - Three synthetic hematite (SH) materials as iron oxides nanofibers were prepared and applied for the removal of 51Cr and radioiodine (131I) as...     

Aero-thermo-mechanical characteristics of imperfect shape memory alloy hybrid composite panels

A nonlinear finite element model is provided to predict the static aero-thermal deflection and the vibration behavior of geometrically imperfect shape memory alloy hybrid composite panels under the combined effect of thermal and aerodynamic loads. The nonlinear governing equations are obtained using Marguerre curved plate theory and the principle of virtual work taking into account the temperature-dependence of material properties. The effect of large deflection is included in the formulation through the von Karman nonlinear strain-displacement relations. The thermal load is assumed to be a steady-state constant-temperature distribution, whereas the aerodynamic pressure is modeled using the quasi-steady first-order piston theory. The Newton-Raphson iteration method is employed to obtain the nonlinear aero-thermal deflections, while an eigenvalue problem is solved at each temperature step and static aerodynamic load to predict the free vibration frequencies about the deflected equilibrium position. Finally, the nonlinear deflection and free vibration characteristics of a composite panel are presented, illustrating the effects of geometric imperfection, temperature rise, aerodynamic pressure, boundary conditions and shape memory alloy fiber embeddings on the panel response.     

Electrical and thermal properties of Ge40S60 films

Films of the composition Ge₄₀S₆₀ have been studied in the temperature range of 313–423 K for electrical conductivity, and 293–373 K for thermal conductivity. The dc conductivity results indicate a single value activation energy of 0.863 eV for the conductivity in the applied temperature range. The thermal conductivity coefficient increases linearly with temperature at a thickness of d=0.311 cm. It was found that the investigated samples show a memory effect. The threshold switching voltage was found to increase linearly with film thickness. Moreover, the threshold voltage decreases exponentially with temperature. The data are analysed using a thermal model for the switching process.     

Iron,copper and zinc ammonium-1-hydroxyalkylidene-diphosphonates with zero-, one- and two-dimensional covalent metal–ligand structures extended into three-dimensional supramolecular networks by charge-assisted hydrogen-bonding

Hydrothermal synthesis with MCl₂ (M = Fe, Cu, and Zn) and disodium 5-ammonium-1-hydroxypentylidene-1,1-bisphosphonate, (Na⁺)₂[⁺H₃N(CH₂)₄C(OH)(PO₃²⁻)(PO₃H⁻)] (Na₂HAC₅OHP₂) or sodium 3-ammonium-1-hydroxypropylidene-1,1-bisphosphonate hydrate, Na⁺[⁺H₃N(CH₂)₂C(OH)(PO₃H^–)(PO₃H^–)]·H₂O (NaH₂PAM·H₂O) the sodium salt of pamidronic acid, H₃PAM) yielded the one-dimensional (1D) iron, molecular copper and two-dimensional (2D) zinc compounds 1D-{[Fe(μ₃-η⁵-HAC₅OHP₂)]·H₂O}, 1, [Cu(η²-H₂AC₅OHP₂)₂], 2, 2D-{[Zn₂(μ₅-η⁷-AC₅OHP₂)Cl], 3, and 2D-{[Zn(μ₂-η³-H₂PAM)₂], 4, respectively. The bisphosphonate ligand bridges (μ_n) between 2–5 metal atoms and uses 2–7 oxygen donor atoms towards metal coordination (ηⁿ). The zwitterionic nature of the now bis- or tetrakis-deprotonated ammonium–bisphosphonate is retained in the metal complexes. From the reaction of NiCl₂ and Na₂HAC₅OHP₂ the zwitterionic 5-ammonium-1-hydroxypentylidene-1-phosphonic acid, ⁺H₃N(CH₂)₄CH(OH)PO₃H⁻, 5 was obtained as a product of the ligand P–C bond hydrolysis. Adjacent strands, molecules or layers in 1–4, respectively are organized through the Coulomb attraction between the positive ammonium group and the negative phosphonate groups, supported by hydrogen-bonding. Each protic H atom on the C–OH, NH₃⁺ and –PO₃H⁻ group is involved in charge-assisted hydrogen-bonding. The ammonium-pentylidene groups act as hydrophobic separators between the hydrophilic units with the polar M{C(OH)(PO₃)₂} and {NH₃} units. Bond valence sum calculations support the Fe(II) oxidation state in 1, which was experimentally determined from a quantitative polarographic Fe(II)/Fe(III) speciation analysis as well as a temperature variable magnetic study.     

Reaction Mechanisms of Strontium Ferrites Synthesis

The reactions between strontium and iron nitrates have been studied in an open atmosphere system using three different molar ratios, 1:1 (I), 1:2 (II) and 2:1 (III) at different temperatures as pointed out from the DTA data. The reaction mechanism was discussed based on the chemical composition characterized by means of thermal analysis, X‐ray diffraction patterns, infrared spectra and magnetic susceptibility. It was found that the reaction products depend on both temperature of reaction and the ratio between reactants. The reaction products were found to be composed of a variety of iron compounds that possess different valences: SrFeO_2.86, SrFeO_2.97, SrFe₂O₄, SrFe₁₂O₁₉, Sr₂Fe₂O₅ and Sr₇Fe₁₀O₂₂ in addition to some accessory reaction products namely α‐Fe₂O₃ and FeO(OH).     

Phytochemical investigation and hepatoprotective activity of Cupressus sempervirens L. leaves growing in Egypt

Three phenolic compounds cosmosiin, caffeic acid, and p-coumaric acid were isolated for the first time from the leaves of Cupressus sempervirens L., together with cupressuflavone, amentoflavone, rutin, quercitrin, quercetin, myricitrin. The isolated compounds were identified using (1)H- and (13)C-NMR spectra. The hepatoprotective activity of the MeOH extract was carried out in liver homogenate of normal and CCl(4)-treated rats; a significant decrease in glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, cholesterol level, and triglycerides, while a significant increase in the total protein level, was observed after the oral administration of MeOH extract. The free radical scavenging activity against stable 2,2-diphenyl-2-picrylhydrazyl (DPPH*) was measured for MeOH extract and some of the isolated phenolic compounds in comparison with alpha-tocopherol and butylated hydroxy toluene as standard antioxidants using ESR technique, showed high antioxidant activity for quercetin, rutin, caffeic acid, and p-coumaric acid.     

Rho-kinase inhibitors from adlay seeds

Rho-kinase enzymes are one of the most important targets recently identified in our bodies. Several lines of evidence indicate that these enzymes are involved in many diseases and cellular disorders. ROCK inhibitors may have clinical applications for cancer, hypertension, glaucoma, etc. Our study aims to identify the possible involvement of Rho-kinase inhibition to the multiple biological activities of adlay seeds and provide a rationale for their folkloric medicines. Hence, we evaluated Rho-kinase I and II inhibitory activity of the ethanol extract and 28 compounds derived from the seeds. A molecular docking assay was designed to estimate the binding affinity of the tested compounds with the target enzymes. The results of our study suggest a possible involvement of Rho-kinase inhibition to the multiple biological activities of the seeds. Furthermore, the results obtained with the tested compounds revealed some interesting skeletons as a scaffold for design and development of natural Rho-kinase inhibitors.     

SPE and HPLC monitoring of 17-β-estradiol in Egyptian aquatic ecosysetms

Solid-phase extraction and HPLC methods are described for monitoring of 17-β-estradiol residues in Egyptian aquatic ecosystems (water, fish, mollusks, sediment, and drinking water) at the Nile River, Suez Canal region, and northeast of Egypt. Molecular imprinted polymer was prepared and used in extraction. High performance liquid chromatography (HPLC) columns used were Supelcosil C₁₈ and Nucleosil C₁₈. The mobile phases used were different combinations of water and acetonitrile. The concentration of 17-β-estradiol in water, aquatic animals, and sediment samples were of 265.13–7988.12 µg/L, 0.503–96.167, and 0.775–11.884 µg/kg, respectively. Marine lake was contained with high levels of 17-β-estradiol (P < 0.05). Similarly, the Nile River downstream showed high levels of 17-β-estradiol. The detected concentrations in mollusks were significantly higher than those detected in fish. Tilapia fish did not show 17-β-estradiol. Contrarily, low concentrations were detected in the rivulet streams supplied by the Nile River. Besides, 17-β-estradiol was also detected in the sediments at low levels. Detection of 17-β-estradiol in the Egyptian ecosystems attracted attention toward heavy reliance on some esterogenic medicinal products in Egypt. The monitoring of 17-β-estradiol in other water bodies was recommended. Besides, the development of methodologies of bioremediation to eliminate 17-β-estradiol from the Egyptian and other water resources of the world was also suggested.