Multigrid convergence acceleration for implicit and explicit solution of Euler equations on unstructured grids

The multigrid method is one of the most efficient techniques for convergence acceleration of iterative methods. In this method, a grid coarsening algorithm is required. Here, an agglomeration scheme is introduced, which is applicable in both cell‐center and cell‐vertex 2 and 3D discretizations. A new implicit formulation is presented, which results in better computation efficiency, when added to the multigrid scheme. A few simple procedures are also proposed and applied to provide even higher convergence acceleration. The Euler equations are solved on an unstructured grid around standard transonic configurations to validate the algorithm and to assess its superiority to conventional explicit agglomeration schemes. The scheme is applied to 2 and 3D test cases using both cell‐center and cell‐vertex discretizations. Copyright © 2009 John Wiley & Sons, Ltd.     

Phthalocyanine-boronates: a synthon for the preparation of molecular assemblies

Covalently linked phthalocyanine-phthalocyanine (Pc-Pc) heterodimers and Pc-Pc triad phthalocyanines connected through phenyl-phenyl (C-C) linkages are prepared using phthalocyanine-boronate (Suzuki Pc-synthon) and palladium catalyst.     

Uranium concentration measurements in human blood for some governorates in Iraq using CR-39 track detector

The sensitive and simple technique of fission track etch has been applied to determine trace concentration of uranium in blood samples for occupational and non-occupational workers, male and female, using CR-39 track detector that is employed for registration of induced fission tracks. The results show that the highest recorded uranium concentration in human blood of workers in the ministry of Science and Technology were 1.90 ppb (male, 36 years old, 12 years' work experience, and living in Basrah governorate) and minimum concentration 0.26 ppb (female, 40 years old, 10 years' work experience, and living in Baghdad), while for non-occupational worker, the maximum uranium concentration was 1.76 ppb (female, 63 years old, and living in Al-Muthana) and minimum concentration was 0.28 ppb (female, 20 years old, and living in Baghdad). It has also been found that the uranium concentration in human blood samples of workers in the ministry of Science and Technology are higher than those of non-occupational workers, and the uranium concentrations for female workers and for non-occupational workers were higher than those for male workers and non-occupational workers.     

Supramolecular separation mechanism of pentafluorophenyl column using ibuprofen and omeprazole as markers: LC‐MS and simulation study

The pentafluorophenyl (PFP) column is emerging as a new advancement in separation science to analyze a wide range of analytes and, thus, its separation mechanism at supramolecular level is significant. We developed a mechanism for the separation of ibuprofen and omeprazole using different combinations (ranging from 50:50 to 60:40) of water–acetonitrile containing 0.1% formic acid as the mobile phase. The column used was Waters Acquity UPLC HSS PFP (75 × 2.1 mm, 1.8 μm). The reverse order of elution was observed in different combinations of the mobile phases. The docking study indicated hydrogen bonding between ibuprofen and PFP stationary phase (binding energy was −11.30 kJ/mol). Separation at PFP stationary phase is controlled by hydrogen bonding along with π–π interactions. This stationary phase may be used to analyze both aromatic and aliphatic analytes. The developed mechanism will be useful to separate various analytes by considering the possible interactions, leading to saving of energy, time and money. In addition, this work will be highly useful in preparative chromatography where separation is the major problem at a large scale. Moreover, the developed LC‐MS‐QTOF method may be used to analyze ibuprofen and omeprazole in an unknown sample owing to the low value of detection limits.