A mesh-free numerical method for solution of the family of Kuramoto-Sivashinsky equations

In this paper, radial basis function (RBFs) based mesh-free method is implemented to find numerical solution of the Kuramoto-Sivashinsky equations. This approach has an edge over traditional methods such as finite-difference and finite element methods because it does not require a mesh to discretize the problem domain, and a set of scattered nodes in the domain of influence provided by initial data is required for the realization of the method. The accuracy of the method is assessed in terms of the error norms L₂,L_∞, number of nodes in the domain of influence, free parameter, dependent parameter RBFs and time step length. Numerical experiments demonstrate accuracy and robustness of the method for solving a class of nonlinear partial differential equations.     

A quick and green ionic liquid-mediated approach for the synthesis of high-performance, organosoluble and thermally stable polyimides

Three diamine monomers with different derivatives of imidazole heterocyclic ring and meta-linked aryl ethers were synthesized and used in polycodensation reaction with various commercial dianhydrides for preparation of a series of novel poly(ether-imide) (PEI)s. The polycodensation reactions were carried out by using conventional method and in a green medium of ionic liquid (IL) without using NMP-pyridine-acetic anhydride. The PEIs were obtained in good yields (80% 96%) with moderate viscosity (0.48 0.66 dL/g) in a shorter reaction time (10 h) in IL as compared with the conventional method (36 h). All of the polymers were amorphous in nature, showed excellent solubility in amide-type polar aprotic solvents with ability to form tough and flexible films, and excellent thermal stability with Tgs in the range of 212 340 ℃ and 10% weight loss temperature (T10) up to 570℃ in N 2 and 528 ℃ in air.     

Comparative sensitivity of microvascular endothelial cells, fibroblasts and tumor cells after in vitro photodynamic therapy with meso-tetra-hydroxyphenyl-chlorin

The phototoxic effect of meso-tetra-hydroxyphenyl-chlorin (mTHPC)-mediated photodynamic therapy (PDT) on human microvascular endothelial cells (hMVEC) was compared with that on human fibroblasts (BCT-27) and two human tumor cell lines (HMESO-1 and HNXOE). To examine the relationship between intrinsic phototoxicity and intracellular mTHPC content, we expressed cell survival as a function of cellular fluorescence. On the basis of total cell fluorescence, HNXOE tumor cells were the most sensitive and BCT-27 fibroblasts the most resistant, but these differences disappeared after correcting for cell volume. Endothelial cells were not intrinsically more sensitive to mTHPC-PDT than tumor cells or fibroblasts. Uptake of mTHPC in hMVEC increased linearly to at least 48 h, whereas drug uptake in the other cell lines reached a maximum by 24 h. No difference in drug uptake was seen between the cell lines during the first 24 h, but by 48 h hMVEC had a 1.8- to 2.8-fold higher uptake than other cell lines. Endothelial cells showed a rapid apoptotic response after mTHPC-mediated PDT, whereas similar protocols gave a delayed apoptotic or necrotic like response in HNXOE. We conclude that endothelial cells are not intrinsically more sensitive than other cell types to mTHPC-mediated PDT but that continued drug uptake beyond 24 h may lead to higher intracellular drug levels and increased photosensitivity under certain conditions.     

Extended structure design with simple molybdenum oxide building blocks and urea as a directing agent

We report here a simple one-pot directed synthesis of an oxomolybdate urea composite in which elementary molybdenum oxide building blocks are linked together with the aid of urea. This type of directed material design resulted in large rod-like crystals of an inorganic-organic hybrid extended structure of {MoO 3(NH 2-CO-NH 2)} infinity consisting of right- and left-handed helical units. In the crystal structure urea acts both as a glue that links the inorganic molybdenum units into a helix and as a supramolecular linker for the stabilization of the crystal structure as a whole. This type of molecular topology resulted in an unexpectedly high thermal stability.     

Development of a novel,fast, simple,nonderivative HPLC method with direct UV measurement for quantification of memantine hydrochloride in tablets

Fast, simple, accurate, and reproducible reverse phase‐high‐performance liquid chromatography method with direct ultraviolet measurement of memantine hydrochloride in tablets was developed, without any chemical derivatization pretreatment. Three main problems appear during chromatographic analysis of memantine: detection, achieving appropriate column retention, and limited choice of mobile phase components, as a result of memantine molecular structure. Among more than 35 tested columns, the best retention and peak symmetry yielded two C8 and three C18 columns with different characteristics, at a temperature of 30°C, mobile phase composed of 1%, v/v, acetonitrile and 99%, v/v, of 0.05–0.1% phosphoric acid or 2.5–5 mmol phosphate buffer, at flow rate of 1 mL/min and injection volume of 5 µL. The retention time of memantine was between 2.6 and 4 min. Both mobile phase concepts showed perfect linearity, precision, and accuracy. This is the first successful and reproducible direct reverse phase‐high‐performance liquid chromatography–ultraviolet quantification method for memantine.     

Chemical composition and antibacterial activity of essential oils from leaves, stems and flowers of Salvia reuterana Boiss. grown in Iran

The essential oils obtained by hydrodistillation of the leaves, stems and flowers of Salvia reuterana (Lamiaceae) were analysed by GC and GC/MS. Germacrene D and beta-caryophyllene were the major constituents in all the three oils: (28.5, 27.7 and 32.5%) and (15.5, 11.4 and 16.6%), respectively. Bicyclogermacrene (10.2 and 13.2%) was also prodominated in the stem and flower oils. The composition of the oils was mostly quantitativel rather than qualitatively different. All the oils consisted mainly of sesquiterpenes and a small percentage of non-terpenoid compounds. In all the three oils, monoterpenes were in a concentration less than 0.5%. Antibacterial activity was determined by the measurement of growth inhibitory zones.     

Proteomic maps-toxicity relationship of halocarbons studied with similarity index and genetic algorithm

In this work we analyzed proteomic maps obtained from hepatocytes, which were treated with 14 halocarbons. A similarity index was introduced as a robust measure of similarity between two maps or between two selections of spots within the maps. A searching algorithm was used to identify the spots that may play an important role in toxicity mechanism. The highest correlation coefficients obtained between the similarity index and biological parameter were larger than 0.9.     

Catalytic reduction of 4-nitrophenol by means of nanostructured polymeric Schiff base complexes

Polymeric Schiff base ligands were synthesized using 2-hydroxybenzaldehyde (L²), 4-hydroxy-3-methoxybenzaldehyde (L⁴), and 5-aminoisophthalic acid. The nanostructured complexes were then synthesized using Ni²⁺, Cu²⁺, and Mn³⁺. The ligands and complexes thus synthesized were characterized using Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis (TGA), and field-emission scanning electron microscopy. The thermal stability of the complexes was confirmed using TGA. The synthesized complexes were used as catalysts in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol in an aqueous phase in the presence of sodium borohydride. In this work, the catalytic reactivity of nanostructured complexes was compared using the rate constant (k) of the reaction. The reaction time for the reduction of 4-NP was 5–14 min for different complexes. The catalytic system based on Ni²⁺/2-hydroxybenzaldehyde was the most active and displayed reusability in the reduction of 4-NP.     

Development of magnetic dispersive microsolid-phase extraction using lanthanum phosphate nanoparticles doped on magnetic graphene oxide as a highly selective adsorbent for pesticide residues analysis in water and fruit samples

Magnetic graphene oxide/lanthanum phosphate nanocomposite (MGO@LaP) was synthesized and used as an efficient adsorbent for magnetic dispersive microsolid-phase extraction (MD-µ-SPE) of pesticides before gas chromatography–electron capture detector (GC–ECD) analysis. The adsorbent was thoroughly characterized with scanning electron microscopy, vibrating sample magnetometer, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. Optimized extraction conditions were investigated concerning extraction time, adsorbent amount, sample pH, and salt amount as well as desorption conditions (type and volume of desorption solvent and desorption time). Under the optimal conditions, the method demonstrated good linearity (3–1500 µg L^?1) with satisfactory determination coefficients of >?0.997 and low detection limits for both chlorpyrifos (0.67 µg L^?1) and hexaconazole (0.89 µg L^?1). Finally, the method showed high analyte relative recoveries in the range of 78–120% for the determination of the selected pesticides in water and fruit juice samples.