Sc0.43(2)Rb2Mo15S19, a partially Sc‐filled variant of Rb2Mo15S19

The structure of scandium dirubidium pentadecamolybdenum nonadecasulfide, Sc_{0.43 (2)}Rb₂Mo₁₅S₁₉, constitutes a partially Sc‐filled variant of Rb₂Mo₁₅S₁₉ [Picard, Saillard, Gougeon, Noel & Potel (2000), J. Solid State Chem. 155 , 417–426]. In the two compounds, which both crystallize in the Rc space group, the structural motif is characterized by a mixture of Mo₆Sⁱ₈S^a₆ and Mo₉Sⁱ₁₁S^a₆ cluster units (`i' is inner and `a' is apical) in a 1:1 ratio. The two components are interconnected through interunit Mo—S bonds. The cluster units are centred at Wyckoff positions 6b and 6a (point‐group symmetries and 32, respectively). The Rb⁺ cations occupy large voids between the different cluster units. The Rb and the two inner S atoms lie on sites with 3. symmetry (Wyckoff site 12c), and the Mo and S atoms of the median plane of the Mo₉S₁₁S₆ cluster unit lie on sites with .2 symmetry (Wyckoff site 18e). A unique feature of the structure is a partially filled octahedral Sc site with symmetry. Extended Hückel tight‐binding calculations provide an understanding of the variation in the Mo—Mo distances within the Mo clusters induced by the increase in the cationic charge transfer due to the insertion of Sc.     

Identification of wild collected mosquito vectors of diseases using gas chromatography–mass spectrometry in Jazan Province,Saudi Arabia

Thirty‐three species of mosquitoes have been reported from the Kingdom of Saudi Arabia. Several of these mosquitoes, Anopheles gambiae Giles s.l., Anopheles stephensi Liston, Culex pipiens Linnaeus, Culex quinquefasciatus Say, Culex tritaeniorhynchus Giles, Stegomyia aegypti (Linnaeus) and Aedimorphus vexans arabiensis (Patton) are known vectors of human and animal diseases. In this study, the cuticular hydrocarbon profiles of eight mosquito species using gas chromatography–mass spectrometry were analyzed. Wild collected fourth‐instar larvae were reared, and single, newly emerged, unfed adult females were used for the analysis. A total of 146–160 peaks were detected from the cuticular extracts by gas chromatography. Repeated analysis of variance (ANOVA) and Tukey HSD Post Hoc test was used to test for quantitative differences in relative hydrocarbon quantity. In addition, a linear regression model was applied using Enter method to determine the diagnostic peaks for the eight mosquito specimens. The ANOVA test indicated that relative peaks were significant (P < 0.05) when selected pairs of peaks were compared. Also, seven compounds showed qualitative differences among the five mosquito vectors tested. The classes of constituents present were n‐alkanes, monomethylalkanes, dimethylalkanes, trimethylalkanes, alkenes, branched aromatic hydrocarbons, aldehydes and esters. These compounds have a carbon chain length ranging from 8 to 18 carbons. The most abundant compound in all adult mosquito specimens was n‐hexylacrylate [retention time (RT) 6.73 min], which was not detected in Cx. pipiens. In Cx. pipiens, the most abundant peak was benzaldehyde (RT 2.98 min). Gas chromatography–mass spectrometry is a suitable method to identify adult mosquitoes, especially from focal areas of public health concern such as Jazan Province, Saudi Arabia. This method allows a wide range of adult collected material to be identified with high accuracy. Copyright © 2013 John Wiley & Sons, Ltd.     

Determination of phthalate esters in bottled water using dispersive liquid–liquid microextraction coupled with GC–MS

Dispersive liquid–liquid microextraction method was developed for the determination of the amount of phthalate esters in bottled drinking water samples and dispersive liquid–liquid microextraction samples were analyzed by GC–MS. Various experimental conditions influencing the extraction were optimized. Under the optimized conditions, very good linearity was observed for all analytes in a range between 0.05 and 150 μg/L with coefficient of determination (R²) between 0.995 and 0.999. The LODs based on S/N = 3 were 0.005–0.22 μg/L. The reproducibility of dispersive liquid–liquid microextraction was evaluated. The RSDs were 1.3–5.2% (n = 3). The concentrations of phthalates were determined in bottled samples available in half shell. To understand the leaching profile of these phthalates from bottled water, bottles were exposed to direct sunlight during summer (temperature from 34–57°C) and sampled at different intervals. Result showed that the proposed dispersive liquid–liquid microextraction is suitable for rapid determination of phthalates in bottled water and di‐n‐butyl, butyl benzyl, and bis‐2‐ethylhexyl phthalate compounds leaching from bottles up to 36 h. Thereafter, degradation of phthalates was observed.     

Evaluation of Antimicrobial Activity of Some Newly Synthesized 4‐Thiazolidinones

The antimicrobial activity of thirteen newly synthesized 4‐thiazolidinones (TZONs) and four dithiolane derivatives was assessed against susceptible and resistant bacteria, including MRSA, as well as Candida albicans. The structure‐activity relationships revealed that 4‐Thiazolidinone derivatives harboring p‐chlorophenyl and dicarboxyethyl at the 2‐ethenyl and 5‐arylidine positions of the thiazolidinone ring display considerable antibacterial properties. No antifungal activity was recorded by all tested compounds against Candida albicans. The possible potentiative (synergistic) effect of the most active compounds to a few commercial antibiotics was also investigated.     

Evaluation of Antifungal and Antioxidant Activity of Newly Synthesized 4‐Thiazolidinones

The antifungal and antioxidant activities of thirty newly synthesized 4‐thiazolidinone (TZON) derivatives were assessed against some fungal species including Candida albicans and Aspergillus niger. The introduction of different arylidene moieties at 5‐positions of the thiazolidinone ring successfully enhanced its biological activity. The structure–activity relationships revealed that 4‐thiazolidinone derivatives harboring dicarboxyethyl (at the 2‐ethenyl) and p‐nitrophenylhydrazyl arm (at the 5‐arylidine positions of the thiazolidinone ring) display considerable antifungal and antioxidant properties.     

A Simple and Convenient One-Pot Synthesis of Benzimidazole Derivatives Using Cobalt(II) Chloride Hexahydrate as Catalyst

A simple and efficient method for the convenient synthesis of 2-arylbenzimidazole has been described on reaction with o-phenylenediamine and various aromatic aldehydes using cobalt(II) chloride hexahydrate as a catalyst. The method is cost-effective, high-yielding, clean, and selective.     

Low‐level Laser Therapy Ameliorates CCl4‐induced Liver Cirrhosis in Rats

This study investigated the effects of low‐level laser therapy (LLLT) in the liver function, structure and inflammation in a experimental model of carbon tetrachloride (CCl₄)‐induced liver cirrhosis. Wistar rats were divided into Control, LLLT, CCl₄ and CCl₄+LLLT groups. CCl₄ groups received CCl₄ (0.4 g kg^?1; i.p.), three times a week, for 12 weeks. A 830 nm LLLT was performed with a continuous wave, 35 mW, 2.5 J cm^?2 per point, applied to four points of the liver (right and left upper and lower extremities, in the four lobes of the liver) for 2 weeks. Liver structure and inflammation (cirrhotic areas, collagen deposition, inflammation, density of Kupffer and hepatic stellate cells) and function (aspartate aminotransferase, alkaline phosphatase, gamma glutamyltransferase, lactate dehydrogenase, total proteins and globulins) were evaluated. LLLT significantly reduced CCl₄‐increased aspartate aminotransferase (P < 0.001), alkaline phosphatase (P < 0.001), gamma‐glutamyl transferase (P < 0.001) and lactate dehydrogenase (P < 0.01) activity, as well as total proteins (P < 0.05) and globulins (P < 0.01). LLLT also reduced the number of cirrhotic areas, the collagen accumulation and the hepatic inflammatory infiltrate. Of note, LLLT reduced CCl₄‐increased number of Kupffer cells (P < 0.05) and hepatic stellate cells (P < 0.05). We conclude that LLLT presents beneficial effects on liver function and structure in an experimental model of CCl₄‐induced cirrhosis.     

Regiospecific Phenyl Esterification to Some Organic Acids Catalyzed by Combined Lewis Acids

A new and efficient method for the preparation of various phenyl esters has been achieved by a simple reaction of an acid with phenol in the presence of anhyd. ZnCl₂ and a catalytic amount of AlCl₃. This combined Lewis acid also catalyzes the selective phenyl esterification to different dioic acids and is very simple and high yielding.     

Water Structure Modification by Sugars and Its Consequence on Micellization Behavior of Cetyltrimethylammonium Bromide in Aqueous Solution

Water structure modification by sugars with a wide difference in stereoregular structures ranging from monosaccharide to trisaccharide and its consequence on the micellization behavior of cetyltrimethylammonium bromide (CTAB) in aqueous medium have been investigated. The characteristic variation in water absorption peaks in the presence of d(?)fructose has been studied by near-infrared spectroscopy. The analyses show that the hydrogen bonding capability of d(+)glucose, d(?)fructose, sucrose, trehalose and raffinose is mainly responsible for the variation in water-additive interactions. The critical micelle concentration determined by specific conductivity measurement and aggregation number determined by steady state fluorescence quenching method show significant variations in presence of additives for CTAB in aqueous solution. The sugars interact with the water structure to varying extents owing to differences in hydrogen bonding capability depending on the stereoregularity of the structure. This induces differences in the microenvironment for competition between the hydrophobic interaction and degree of hydration of the hydrophilic group of the surfactant to ultimately influence the micellization behavior in aqueous solution.     

Influence of oxygen flow rate on the surface chemistry and morphology of radio frequency (RF) magnetron sputtered zinc oxide thin films

Zinc oxide thin films were deposited, by radio frequency magnetron sputtering, on heated and unheated substrates. The oxygen flow rate was varied during deposition, and its effects on the structural and chemical properties of the films were investigated. The films had oriented c‐axis growth with nano‐crystallite size. Their surfaces manifested columnar microstructure, with a surface roughness that was suppressed by the introduction of oxygen. Chemical analysis showed that deposition under an oxygen atmosphere resulted in substantial reduction of oxygen vacancies, with a corresponding incorporation of chemisorbed species. Copyright © 2013 John Wiley & Sons, Ltd.