ON THE BOUNDEDNESS AND THE STABILITY RESULTS FOR THE SOLUTION OF CERTAIN FOURTH ORDER DIFFERENTIAL EQUATIONS VIA THE INTRINSIC METHOD

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Plane-Couette flow between smooth and rough walls

A novel approach is utilized to acquire new experimental information on plane-Couette flow. To this end a rigid plate, functioning as the moving wall, is propelled through air by the carriage of a towing channel, and the fixed wall is a stationary bench. It is shown that, irrespective of the state of the walls, the critical Reynolds number, expressed in terms of relative wall velocity and wall spacing, is about 1,200. Findings support the notion of universality of turbulent flow structure in the wall region, but shed doubt on the conjecture of homogeneous shear-flow turbulence in the core.     

Biomimetic Approaches for Membrane Technologies

Membrane technology is the dominant process in water treatment. However, the operation cost of membranes cannot be decreased unless the amount of fouling, the “Achilles heel” of membranes, and energy consumed are cut. The high energy requirements in commercial nanofiltration, reverse osmosis and forward osmosis technologies lead researchers to develop new membrane designs having high flux values with high salt rejection values. The purpose of this review is to present the inadequacies of the membrane processes by considering studies related to fouling and energy minimization. In this respect, lipid bilayers, block copolymers, aquaporin Z proteins and aligned carbon nanotubes can be the base to build biomimetic membranes. Such studies are summarized due to their remarkable properties in fouling control. Furthermore, the review describes the membrane design strategies and points the limitations hindering commercialization. Additionally, it is hoped that this review will trigger further needed studies.     

Nanocomposites Prepared by Solution Blending: Microstructure and Mechanical Properties

Composites of poly(vinyl chloride) (PVC) filled with micron‐ and nanosized calcium carbonate (CaCO₃) particles were prepared by solution blending. The influences of particle size and CaCO₃ content on the microstructure and mechanical properties of the PVC composites were investigated by means of polarized optical microscopy and mechanical testing. The polarized optical microscope images revealed that nanosized CaCO₃ particles were more agglomerated than micron‐sized CaCO₃ particles and the amount of agglomerates increased with increasing particle content. PVC/CaCO₃‐0.22 composites (PVC nanocomposite filled with 220‐nm‐particle‐sized CaCO₃) 5 phr CaCO₃ content had the maximum tensile strength. The Young's modulus of all composites increased with increasing particle content. The energy at break of all composites showed a decreasing trend as a function of CaCO₃ content and varied with particle size.     

Hydrogen activation and metal hydride formation trigger cluster formation from supported iridium complexes

The formation of iridium clusters from supported mononuclear iridium complexes in H(2) at 300 K and 1 bar was investigated by spectroscopy and atomic-resolution scanning transmission electron microscopy. The first steps of cluster formation from zeolite-supported Ir(C(2)H(4))(2) complexes are triggered by the activation of H(2) and the formation of iridium hydride, accompanied by the breaking of iridium-support bonds. This reactivity can be controlled by the choice of ligands on the iridium, which include the support.     

A study on 3-D stress distributions in the bi-adhesively bonded T-joints

In this study, the normal (σ_x, σ_y, σ_z) and shear stress (τ_xy, τ_yz, τ_zx) distributions occurring in a bi-adhesively bonded T-joint with was investigated via a non-linear three dimensional finite element analysis. For this purpose, first of all, using 2024-T3 aluminum alloy as the adherend and the support, a two-part paste (DP 460) and a film type (SBT 9244) as adhesive, two different types of T-joint samples (single-adhesively bonded T-joint and bi-adhesively bonded T-joint) were produced for experimental studies. After experimental studies on the three different T-joint types were conducted, stress analyses in the T-joints were performed with a three-dimensional finite element analysis by considering the geometrical non-linearity and the material non-linearities of the adhesive (DP460 and SBT9244) and adherend (AA2024-T3). Finally, for a given adherend, the lower the stiffness of the adhesive used in the overlap, the lower the stress concentration, leading to potentially higher joint strength. The use of relatively low stiffness adhesives at the ends of the overlap in a bi-adhesive can decrease the stress concentration and, therefore, potentially lead to higher joint strength.     

ASSOCIATION OF KETOROLAC TROMETHAMINE IN AQUEOUS SOLUTIONS AND ITS RELATIONSHIP TO SOLUBILIZATION

Some physico-chemical properties of aqueous racemic Ketorolac Tromethamine (KT) solutions were measured as a function of concentration (0-1.0 M). These included surface tension, osmolality, partition coefficients and electrical conductivity at different temperatures (10, IS, 20, 25, 30, 40 and 50° C). These measurements indicate that KT undergoes nonmicelar self-association in water. Comparison of thesolubilitiesof spironolactone and diazepam in aqueous KT with the corresponding solubilities in known aqueous hydrotropic agents (sodium benzoate and salicylate) nonmicellar chlorpheniramine maleate (BP grade of  99 % purity) and miceilar chlorpromazine hydrochloride (BP grade of  99 % purity) indicates KT to undergo nonmicellar association, with a capacity for solubilization intermediate between hydrotropic agents and miceilar solubilizers. The solubilities of normal alkanols (C₄-C₁₀ ) were also measured against aqueous KT concentration. Compared with their solubilities in miceilar surfactants (sodium dodecylsulfate and chlorpromazine hydrochloride) aqueous KT appears to be a less efficient solubilizer. Molecular mechanical modeling of intermolecular interactions between KT species in water indicate that trimeric species have lower energies compared with those of the same number of monomeric (or monomeric plus dimeric) entities.     

Development of reactive methacrylates based on glycidyl methacrylate

Six methacrylate monomers have been synthesized for use as reactive diluents in dental composites and evaluated to investigate the relationship between molecular structure and monomer reactivity. Four were synthesized by reactions of glycidyl methacrylate (GMA) with various acids, 2‐(2‐methoxyethoxy)acetic acid ( 1 ), 2‐(2‐(2‐methoxyethoxy)ethoxy)acetic acid ( 2 ), cyanoacetic acid ( 3 ), and benzoic acid ( 4 ); others were synthesized by reactions of GMA with diethyl hydrogen phosphate ( 5 ) or methanol ( 6 ). Monomers 1 and 2 are novel, 3 seems to be novel, 4 and 6 were synthesized via a novel method, and the synthesis of 5 was described in the literature. The monomers showed high crosslinking tendencies during thermal bulk polymerizations. The photo‐, homo‐, and copolymerization behavior of the monomers with 2,2‐bis[4‐(2‐hydroxy‐3‐methacryloyloxy)phenyl]propane (Bis‐GMA) were investigated. The maximum rate of polymerizations of monomers 2 – 6 was found to be greater than triethyleneglycol dimethacrylate, Bis‐GMA, 2‐hydroxyethyl methacrylate, and glycerol dimethacrylate. For the more reactive monomers ( 2 , 3 , and 4 ), the oxygen sensitivity of polymerization was found to be low due to a hydrogen abstraction/chain transfer reaction. The computationally calculated dipole moment and lowest unoccupied molecular orbital energies indicated that there seems to be a correlation between these quantities and reactivity for ester linked monomers ( 1 – 5 ), which was also supported by ¹³C NMR data. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3787–3796, 2010     

Various polycarbonate graft copolymers via diels–alder click reaction

In this work, we used Diels–Alder click reaction for the preparation of various types of aliphatic polycarbonates (PCs). We first prepared a novel anthracene‐functionalized cyclic carbonate monomer, anthracen‐9‐ylmethyl 5‐methyl‐2‐oxo‐1,3‐dioxane‐5‐carboxylate (2), followed by ring‐opening polymerization of this monomer to prepare PC with pendant anthracene groups (PC‐anthracene) using 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU)/1‐(3,5‐bis(trifloromethyl)phenyl)‐3‐cyclohexylthiourea (TU) as the catalyst and benzyl alcohol as the initiator in CH₂Cl₂ at room temperature. Subsequently, the resulting PC‐anthracene (M_n,TDGPC = 6000 g/mol, M_w/M_n = 1.22) was grafted with a linear α‐furan protected‐maleimide terminated‐poly(methyl methacrylate) (PMMA‐MI) (M_n,GPC = 3100 g/mol, M_w/M_n = 1.31), or poly(ethylene glycol) (PEG‐MI) (M_n,GPC = 550 g/mol, M_w/M_n = 1.09), or a mixture of PMMA‐MI and PEG‐MI to yield well‐defined PC graft or hetero graft copolymers, PC‐g‐PMMA (M_n,TDGPC = 59000 g/mol, M_w/M_n = 1.22) or PC‐g‐PEG, or PC‐g‐(PMMA)‐co‐PC‐g‐(PEG) (M_n,TDGPC = 39900 g/mol, M_w/M_n = 1.16), respectively, using Diels–Alder click reaction in toluene at 110°C. The Diels–Alder grafting efficiencies were found to be over 97% using UV spectroscopy. Moreover, the structural analyses and the molecular weights of resulting graft copolymers were determined via ¹H NMR and triple detection GPC (TD‐GPC), respectively. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012