N-Alkanes in Air Particulates of the Eastern Province of Saudi Arabia

Abstract

Oil hydrocarbons represent a great proportion of organic compounds in the atmosphere. Information about these compounds in the atmosphere of the Eastern Province of Saudi Arabia is lacking. In this study, n-alkanes and polynuclear aromatic hydrocarbons in air particulates were determined. The highest median concentration levels of n-alkanes in three urban areas and three areas near oil production centers were 121 ng/m³ and 42.9 ng/m³, respectively. Polynuclear aromatic hydrocarbons were also detected, although they are present in too low concentration for reliable quantitative measurement by GC and GC/MS techniques. A positive correlation was found between the concentration levels of n-alkanes in air particulates and the total suspended particulates measured at most locations. The carbon preference index (CPI) and the presence of the unresolved complex envelope suggested an anthropogenic origin for the n-alkanes.     

Reactions of 2-Cyano-2-nitrosomethylbenzthiazole: One-Pot Synthesis of New Polyfunctional Pyrazine Derivatives

2-Cyano-2-nitrosomethylbenzthiazole reacts with some active methylene and nucleophile derivatives to yield new fused and isolated polyfunctional pyrazine, -[1,2,4]triazine, -[1,4,5]benzoxadiazepin, -[1,4,5]benzothiadiazepine, [1,4,5]benzotriazepine, -triazole and -triazolo[3,2-c]triazine derivatives in one-pot reaction. The structures were based on IR, MS, and 1 H NMR spectra and elemental data.     

Facile Synthesis of Thiophene- and 1,3,4-Thiadiazole-Based Heterocycles

Treatment of 3-cyanoacetylpyrazole derivative 1 with phenyl isothiocyanate in potassium hydroxide at room temperature followed by α-haloketones 4a–d and hydrazonoyl halides 10a–e gave the corresponding pyrazolylthiophene 6a–d and pyrazolyl-1,3,4-thiadiazole 12a–e derivatives, respectively.     

Multifunctional graphene/platinum/Nafion hybrids via ice templating

We report the synthesis of multifunctional hybrids in both films and bulk form, combining electrical and ionic conductivity with porosity and catalytic activity. The hybrids are synthesized by a two-step process: (a) ice templation of an aqueous suspension comprised of Nafion, graphite oxide, and chloroplatinic acid to form a microcellular porous network and (b) mild reduction in hydrazine or monosodium citrate which leads to graphene-supported Pt nanoparticles on a Nafion scaffold.     

Preconcentration of milk proteins using octadecylated monolithic silica microchip

Sample preparation is a bottleneck in systems for chemical analysis and it is a required step in order to remove interference and preconcentrate the target analytes. Much research in recent years has focused on porous monolithic materials since they are highly permeable to liquid flow and show high mass transfer compared with common packed beds. This study has focused on the use of a glass microchip containing an inorganic silica-based monolithic material modified with octadecyl groups for preconcentration of milk proteins from skimmed cows’ milk that vary in molecular weight, hydrophobicity, and abundance. Comparison between the fabricated device and a commercial cartridge for the preconcentration of proteins in skimmed cows’ milk showed the ability of the device to successfully enrich protein mixtures from the sample. The three replicate experiments showed that the RSD of the mass to charge ratio of milk proteins ranged from 0.01 to 0.46%. In addition, it was found that there were no significant differences between the observed and reported masses of the milk proteins and the relative percentage error of the molecular masses ranged between 0.03 and 0.90%. The fact that the small amounts of sample required and short sample preparation time suggest that this new microfluidic device may be a viable alternative to existing procedures for protein extraction from real samples.     

Microwave-assisted synthesis,antimicrobial, antiquorum-sensing and cytotoxic activities of a new series of isatin-β-thiocarbohydrazones

Abstract

New isatin-β-thiocarbohydrazone hybrids 4-17 were designed relied on isatin scaffold to generate various analogs with expected antimicrobial activity. The new hybrids were estimated for antibacterial effectiveness over S. aureus, B. cereus and E. coli, and antifungal efficacy over C. albicans and A. fumigatus. Compound 14 evinced the highest efficacy over A. fumigatus and C. albicans. In addition, 5 and 12 showed eminent efficacy toward A. fumigatus, where compounds 4, 7, 9, 11, 13, 15 and 16 exhibited moderate activity over the same fungus. Moreover, 6 and 9 displayed moderate activity over C. albicans. The new compounds were also estimated for antiquorum-sensing effectiveness against C. violacium, where compound 17 showed interesting activity. In vitro cytotoxicity assay of the new analogs was done over Hela and COS-7 cancer cell lines. All analogs have IC₅₀ values >50?μM toward both cell lines.     

Ferroelectric phase transition in Ga2Te3 single crystals

Measurements of the electrical conductivity and Hall effect were carried out in a wide temperature range (200-500 K) for Ga₂Te₃ crystals. The crystals were grown in single crystalline form by making a modification of the travelling heater method technique. The measurements revealed unusual observations in the electric conductivity and Hall mobility indicating the presence of some type of phase transitions at about 430 K. So, ferroelectric behavior was examined for confirming the presence of second-order (ferroelectric) phase transition. An energy gap of 1.21 eV and depth of the impurity center of 0.11 eV were found.     

Second-class currents in 0−→0+ and unique nuclear β transitions

The induced pseudotensor contribution to 0^? → 0⁺ and uniqueβ transitions has been analyzed starting from two possible forms of the nonrelativistic Hamiltonian. The role of mesonic corrections and mesonic second-class currents has been discussed     

Development of a differential pulse voltammetric method for the determination of Silymarin/Vitamin E acetate mixture in pharmaceuticals

Differential pulse voltammetric method was developed for determination of Silymarin (SMR)/Vitamin E acetate (VEA) mixture in pharmaceuticals. SMR and VE gave well-resolved diffusion-controlled anodic peaks at +756 and +444mV, respectively (versus Ag/AgCl) in Britton-Robinson buffer at pH 2.8. The solution conditions and instrumental parameters were optimized for their quantitative determination. The linear response was obtained in the range 0.1-4.0mgL(-1) with a detection limit of 0.03mgL(-1) for SMR and 0.05-4.0mgL(-1) with a detection limit of 0.01mgL(-1)for VEA.     

Development of a Novel Automatic Potentiometric System for Determination of Selenium and Its Application in Pharmaceutical Formulations and Anodic Slime

Poly(vinyl chloride) polymeric membrane sensors containing Sn(IV) phthalocyanine dichloride (SnPC) and Co(II) phthalocyanine (CoPC) as novel electroactive materials dispersed in o‐nitrophenyl octylether (o‐NPOE) as a plasticizer are examined potentiometrically with respect to their response toward selenite (SeO₃^2?) ions. Fast Nernstian response for SeO₃^2? ions over the concentration ranges 7.0×10^?6–1.0×10^?3 and 8.0×10^?6–1.0×10^?3 mol L^?l at pH 3.5–8.5 with lower detection limit of 5.0×10^?6 and 8.0×10^?6 mol L^?1 and calibration slopes of ?25.4 and ?29.7 mV decade^?1 are obtained with SnPC and CoPC based membrane sensors, respectively. The proposed sensors reveals by the modified separate solution method (MSSM) a good selectivity over different anions which differ significantly from the classical Hofmeister series. A segmented sandwich membrane method is used to determine complex formation constants of the ionophores in situe in the solvent polymeric sensing membranes. Membrane incorporating CoPC in a tubular flow detector is used in a two channels flow injection set up for continuous monitoring of selenite at a frequency of ca. 50 samples h^?1. Direct determination of selenium in pharmaceutical formulations and anodic slime gives results in good agreement with data obtained using standard ICP method.