Spatial distribution and risk assessment of radioactivity and heavy metal levels of sediment,surface water and fish samples from Lake Van,Turkey

In this study, radioactivity levels of 228 lake water samples, 63 upper and depth sediment samples and 12 fish samples from Lake Van were investigated from 2005 to 2008 and the distribution patterns of the radionuclides were presented. Analysis included gross alpha–beta and total radium isotopes activities and uranium concentrations of the water, and gross alpha and gross beta activities and relevant ²³⁸U, ²³²Th and ⁴⁰K activity of the sediment and fish samples of the lake. Mean gross alpha, gross beta and radium isotopes activities of lake water were found 0.74 ± 0.46, 0.02 ± 0.01 and 0.06 ± 0.04 Bq/L, respectively. Mean gross alpha and beta activities in upper and depth sediments were found to be 41 ± 6 and 1,514 ± 74 Bq/kg; 77 ± 5 and 394 ± 24 Bq/kg at a 95 % confidence level, respectively. Mean activities of ²³⁸U, ²³²Th and ⁴⁰K activity concentrations in upper and depth sediments were determined to be 225 ± 22, 70 ± 7 and 486 ± 39 Bq/kg; 174 ± 4, 63 ± 3 and 263 ± 25 Bq/kg, respectively. The mean gross alpha and beta, ²³⁸U, ²³²Th and ⁴⁰K aktivities in fish samples were established as 47 ± 18, 470 ± 12, 0.57 ± 0.220, 0.022 ± 0.006, 319 ± 11 Bq/kg, respectively. The transfer factor from lake water to fish tissues, annual intake by humans consuming fish, and annual committed effective doses were estimated and evaluated.     

Structural and vibrational investigation of 1, 2-<Emphasis Type="Italic">bis</Emphasis>(3, 4-dimethoxyphenyl) ethane-1, 2-dione (Veratril): experimental and theoretical studies

The molecular and crystal structures of 1,2-bis(3,4-dimethoxyphenyl)ethane-1,2-dione (TMBZ = tetramethoxybenzil) were determined by a single-crystal X-ray diffraction, ¹H NMR, and FT-IR spectroscopy. The compound TMBZ (C₁₈H₁₈O₆, M _r = 330.32) crystallized in the orthorhombic Fdd2 space group wherein: a = 39.145(4), b = 18.167(2), c = 4.3139(5) Å and β = 90°, Z = 8. The packing of the molecules in the crystal lattice is stabilized by intermolecular C–H?O contacts in the herringbone arrangement. The molecular geometry and harmonic frequencies of TMBZ in the ground state were calculated utilizing density functional (B3LYP) method with the 6-311++G(d, p)-basis set. The density functional theory optimized the geometric structure, and vibrational wave numbers of TMBZ in gas phase were compared with the experimental data. A complete assignment of the fundamentals was proposed based on the total energy distribution calculation.     

The effect of local structural disruption on the yield of photochemical ligation between anthracene-oligonucleotide conjugates.

The techniques of chemical ligation have attracted great attention as an alternative to enzymatic joining of DNA ends. Here we introduce the photoligation of anthracene-modified ODN conjugates through anthracene cyclodimer formation. The effect of the positions and the kinds of single base mismatch on the template was evaluated using eight templates with one-base displacements. We found out that the yield of the ligation was affected by mispairing in a position-dependent manner. Such results would be attributed to the disruption of the local structure at the ligation site.     

Theoretical studies of some sulphonamides as corrosion inhibitors for mild steel in acidic medium

Density functional theory (DFT) at the B3LYP/6‐31G (d,p) and BP86/CEP‐31G* basis set levels and ab initio calculations using the RHF/6‐31G (d,p) methods were performed on four sulfonamides (namely sulfaacetamide (SAM), sulfapyridine (SPY), sulfamerazine (SMR), and sulfathiazole (STI)) used as corrosion inhibitors for mild steel in acidic medium to determine the relationship between molecular structure and their inhibition efficiencies (%IE). The order of inhibition efficiency obtained was SMR > SPY > STI > SAM which corresponded with the order of most of the calculated quantum chemical parameters namely E_HOMO (highest occupied molecular orbital energy), E_LUMO (lowest unoccupied molecular orbital energy), the energy gap (ΔE), the Mulliken charges on the C, O, N, S atoms, hardness (η), softness (S), polarizability (α), dipole moment (μ), total energy change (ΔE_T), electrophilicity (ω), electron affinity (A), ionization potential (I), the absolute electronegativity (χ), and the fraction of electrons transferred (ΔN). Quantitative structure activity relationship (QSAR) approach has been used and a correlation of the composite index of some of the quantum chemical parameters was performed to characterize the inhibition performance of the sulfonamides studied. The results showed that the %IE of the sulfonamides was closely related to some of the quantum chemical parameters but with varying degrees/order. The calculated %IE of the sulfonamides studied was found to be close to their experimental corrosion inhibition efficiencies. The experimental data obtained fits the Langmuir adsorption isotherm. The negative sign of the E_HOMO values and other thermodynamic parameters obtained indicates that the data obtained supports physical adsorption mechanism. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Operational extended model formulations for Advanced Planning and Scheduling systems

Since the basic reasoning of Manufacturing Resources Planning (MRPII) systems is flawed, a new breed of concepts called Advanced Planning and Scheduling systems (APS) have recently emerged to overcome the problems occurring on the shop floor. In this study, we develop improved and extended mixed integer programming formulations for APS systems at the factory planning level. First, we develop a basic model which explicitly considers capacity constraints, operation sequences, processing times, and due dates in a multi-machine, multi-order, multi-item environment where an item can be processed on a given set of eligible machines. The extensions to the basic model include sequence dependent setups, and transfer times between machines. We also show that our model with a little modification could be used to quote delivery times for customer orders in case due dates are not specified. We provide numerical examples and our conclusions along with future research directions.     

Approximation of analytical functions by k-positive linear operators in the closed domain

This work treats the problem of convergence for the sequences of linear \(k\) -positive operators on a space of functions that are analytic in a closed domain. By convergence in this space, we mean a uniform convergence in a closed domain that contains the original domain strictly inside itself, while the linear \(k\) -positive operators are naturally associated with Faber polynomials related to the considered domain. Until now, this problem has been solved in the space of functions analytic in an open bounded domain with the topology of compact convergence.     

The complex step approximation to the higher order Fréchet derivatives of a matrix function

Numerical Algorithms - The k th Fréchet derivative of a matrix function f is a multilinear operator from a cartesian product of k subsets of the space $mathbb {C}^{ntimes n}$ into itself. We...     

Experimental investigation of flow and heat transfer in rectangular cross-sectioned duct with baffles mounted on the bottom surface with different inclination angles

In this study, steady-state forced convection heat transfer and pressure drop characteristics in a horizontal rectangular cross-sectioned duct, baffles mounted on the bottom surface with different inclination angles were investigated experimentally in the Reynolds number range from 1 × 10³ to 1 × 10⁴. The study was performed under turbulent flow conditions. Effects of different baffle inclination angles on flow and heat transfer were studied. Results are also presented in terms of thermal enhancement factor. It is observed that increasing in baffle inclination angle enhances the heat transfer and causes an increase in pressure drop in the duct.