Entropy generation analysis of tangent hyperbolic fluid in quadratic Boussinesq approximation using spectral quasi-linearization method

Applied Mathematics and Mechanics - In many industrial applications, heat transfer and tangent hyperbolic fluid flow processes have been garnering increasing attention, owing to their immense...     

Trace element determination in high-purity aluminum clad samples by k 0-based internal monostandard instrumental neutron activation analysis

The k₀-based internal monostandard instrumental neutron activation analysis (IM-INAA) method was applied for quantification of trace impurities in seven high purity aluminum samples used as fuel cladding in a research reactor. Samples along with BCS CRM 182 (Si–Al alloy) were irradiated in high flux reactor neutrons for 10–15 h. In situ detection efficiency, needed in concentration calculation ratio by IM-INAA, was obtained using gamma rays of activation products produced in the samples. Elemental concentration ratios obtained with respect to Fe (used as internal monostandard) were converted to absolute concentrations by determining concentration of Fe by relative method of NAA. Concentrations of ten trace elements (Sc, Cr, Co, Zn, Ga, La, Ce, Sm, W and Hf) including major element Fe were determined in this work. The method used is non-destructive in nature and does not need multielement standards. Results of IM-INAA were compared with those obtained by relative method of INAA and inductively coupled plasma atomic emission spectrometry (ICP-AES). Details of methodologies and results obtained by all methods are discussed and compared in the paper.     

STUDY OF SH-WAVE PROPAGATION IN AN INITIALLY STRESSED TRICLINIC LAYER SANDWICHED BETWEEN TRANSVERSELY ISOTROPIC ELASTIC AND HETEROGENEOUS POROELASTIC HALF-SPACES

Journal of Applied Mechanics and Technical Physics - In this paper, SH-wave propagation in an initially stressed triclinic layer welded between two half-spaces is investigated. The upper half-space...     

Stereoselective Insertion of Benzynes into Lawsones: Synthesis of Biologically Important Benzannulated Bicyclo[3.3.0]octanes

An ideal stereoselective insertion of in situ generated benzynes into lawsones through domino formal [2+2]-cycloaddition followed by rearrangement is disclosed. The reaction allowed for the preparation of biologically important benzannulated bicyclo[3.3.0]octanes in good yields and with excellent selectivities by using simple substrates and conditions.     

Time‐dependent finite element simulations of a shear‐thinning viscoelastic fluid with application to blood flow

A new finite element method is developed to simulate time‐dependent viscoelastic shear‐thinning flows characterized by the generalized Oldroyd‐B model. The focus of the algorithm is improved stability through a free‐energy dissipative scheme by using low‐order piecewise‐constant finite element approximations for stress. The algorithm is further modified by incorporating a pressure‐projection method, a DG‐upwinding scheme, a symmetric interior penalty DG method to solve the elliptic pressure‐update equation and a geometric multigrid preconditioner. The improved stability and cost to accuracy is compared when using higher order discontinuous bilinear approximation, where in addition, we consider the influence of a slope limiter for these elements. The algorithm is applied to the 2D start‐up‐driven cavity problem, and the stability of the free energy is illustrated and compared between element choices. An application of the model to modelling blood in small arterioles and channels is considered by simulating pulsatile blood flow through a stenotic arteriole. The individual influences of viscoelasticity and shear‐thinning within the generalized Oldroyd‐B model are investigated by comparing results to the Newtonian, generalized Newtonian and Oldroyd‐B models. Copyright © 2014 John Wiley & Sons, Ltd.     

N‐bromo‐hydantoin grafted polystyrene beads: Synthesis and nano‐micro beads characteristics for achieving controlled release of active oxidative bromine and extended microbial inactivation efficiency

N‐bromo‐hydantoin and N‐bromo‐5,5′‐dimethylhydantoin conjugated polystyrene beads were synthesized from chloromethyl polystyrene beads which differ in their particles size, crosslinking, nano‐micro porosity, and tunnels size on the surface, in order to study the effect of these parameters on oxidative halogen release and resultant activity, for water purification applications. The synthesized beads were characterized using elemental analysis, FT‐IR, solid state ¹³C‐NMR, and scanning electron microscope (SEM). The conjugation yield and kinetics in different solvents and bromine loading capacity were studied. The N‐bromoamine polystyrene beads were tested for water decontamination according to NSF 231 protocol. The release of active bromine was analyzed by spectrophotometer using a DPD‐1 kit and also studied the antimicrobial activity against Escherichia coli and MS2 phages. Bead's nano‐micro characteristics were found critical for oxidative halogen release control: rate stabilization and modulation, extension and also influences antimicrobial activity. The synthesized beads exhibited extended and stable release of bromine, 6 and 4 log reduction for E. coli and MS2, respectively for 250 L of passing contaminated water. Thus, N‐halamine hydantoins conjugated polystyrenes, chemically or kinetically release modified should have applications as disinfectants in water purification systems as well as medical field. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 596–610     

Chemoselective Hydrogenation of 6-Alkynyl-3-fluoro-2-pyridinaldoximes: Access to First-in-Class 6-Alkyl-3-Fluoro-2-pyridinaldoxime Scaffolds as New Reactivators of Sarin-Inhibited Human Acetylcholinesterase with Increased Blood–Brain Barrier Permeability

Novel 6-alkyl- and 6-alkenyl-3-fluoro-2-pyridinaldoximes have been synthesised by using a mild and efficient chemoselective hydrogenation of 6-alkynyl-3-fluoro-2-pyridinaldoxime scaffolds, without altering the reducible, unprotected, sensitive oxime functionality and the C−F bond. These novel 6-alkyl-3-fluoro-2-pyridinaldoximes may find medicinal application as antidotes to organophosphate poisoning. Indeed, one low-molecular-weight compound exhibited increased affinity for sarin-inhibited acetylcholinesterase (hAChE) and greater reactivation efficiency or resurrection for sarin-inhibited hAChE, compared with those of 2-pyridinaldoxime (2-PAM) and 1-({[4-(aminocarbonyl)pyridinio]methoxy}methyl)-2-[(hydroxyimino)methyl]pyridinium chloride (HI-6), two pyridinium salts currently used as antidote by several countries. In addition, the uncharged 3-fluorinated bifunctional hybrid showed increased in vitro blood–brain barrier permeability compared with those of 2-PAM, HI-6 and obidoxime. These promising features of novel low-molecular-weight alkylfluoropyridinaldoxime open up a new era for the design, synthesis and discovery of central non-quaternary broad spectrum reactivators for organophosphate-inhibited cholinesterases.