Assesment of dimethyl phthalate removal from aqueous phase using barium hexaferrite containing magnetic beads

The barium hexaferrite (BaFe(12)O(19)) containing magnetic poly (ethylene glycol dimethacrylate-vinyl pyridine; mag-poly [EGDMA-VP]) beads (average diameter=53-212 μm) were synthesized and characterized. Their use as an adsorbent in the removal of dimethyl phthalate (DMP) from an aqueous solution was investigated. The mag-poly (EGDMA-VP) beads were prepared by copolymerizing of 4-vinyl pyridine (VP) with ethylene glycol dimethacrylate (EGDMA). The mag-poly (EGDMA-VP) beads were characterized by N(2) adsorption/desorption isotherms (BET), vibrating sample magnetometer (VSM), X-ray powder diffraction (XRD), elemental analysis, scanning electron microscope (SEM), and swelling studies. At a fixed solid/solution ratio, the various factors affecting the adsorption of DMP from aqueous solutions such as pH, initial concentration, contact time, and temperature were analyzed. The maximum DMP adsorption capacity of the mag-poly (EGDMA-VP) beads was determined as 96.2 mg/g at pH 3.0, 25 °C. All the isotherm data can be fitted with both the Langmuir and the Dubinin-Radushkevich isotherm models. The pseudo-first-order, pseudo-second-order, Ritch-second-order, and intraparticle diffusion models were used to describe the adsorption kinetics. The thermodynamic parameters obtained indicated the exothermic nature of the adsorption. The DMP adsorption capacity did not change after 10 batch successive reactions, demonstrating the usefulness of the magnetic beads in applications.     

Mass transport characteristics in a pulsed plasma enhanced chemicalvapor deposition reactor for thin polymer film deposition

A pulsed plasma enhanced chemical vapor deposition (PECVD) reactor is used for the preparation of thin polyacetylene films. A theoretical model based on the mass transport characteristics of the reactor is developed in order to correlate with experimentally obtained spatial deposition profiles for the acetylene plasma polymer film deposited within the cylindrical reactor. Utilizing a free radical mechanism with gas phase initiation of the polymerization reaction as the rate controlling step, a system parametric study is performed to predict the Peclet number range of operation for the pulsed PECVD reactor. This parametric study indicates radical decay by diffusion to the reactor walls to be the significant physical phenomenon in the system. It is concluded that a quasi-steady-state model is a good tool for predicting the important mass transfer phenomena occurring in the pulsed plasma reactor     

Synthesis,characterization, and antimicrobial activities of Cu(I), Ag(I), Au(I), and Co(II) complexes with [CH3N(CH2PPh2)2]

Transition metal complexes of ditertiary aminomethylphosphine ligand, (Ph₂PCH₂)NCH₃ [N,N‐bis(diphenylphospinomethyl)aminomethane], dppam, with metal ions which are Ag(I), Au(I), Cu(I), and Co(II) have been synthesized under nitrogen atmosphere by the Schlenk method. [Ag(dppam)₂]NO₃ ( 1 ), [Au(dppam)₂]Cl ( 2 ), and [Cu(dppam)₂]Cl ( 3 ) complexes have been isolated as colorless solids, whereas [CoCl₂(dppam)] ( 4 ) complex as a blue solid. All complexes have been characterized by atomic absorption, FT‐IR, NMR (¹H, ¹³C, ³¹P) spectroscopic, thermogravimetric/differantial thermal analysis (TG/DTA), and elemental analysis techniques. Antimicrobial activity of 1 , 2 , 3 , and 4 were studied in vitro on 13 bacteria and 4 yeasts. The cobalt(II) phosphine complex has shown the best antimicrobial activity in comparison with the other metal complexes. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:484–491, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20145     

Physico-chemical and Thermal Characteristics of Lime-silica Fume Pastes

Five lime-silica fume pastes were investigated using initial CaO/SiO₂ molar ratios of 0.80, 1.0, 1.30, 1.70 and 2.0. The kinetics and mechanism of hydration interaction between lime and silica fume were studied on the basis of the phase composition and the physical state of the formed hydration products. The developed strength could be related to the lime content of the lime-silica mixture and the formed hydrates. This revised version was published online in August 2006 with corrections to the Cover Date.     

Interfacial Interactions and Properties of Polyethylene‐Layered Silicate Nanocomposites

Summary: Organically modified montmorillonites (OMs), carrying alkyl chains, phenyl groups, or a combination of both, were prepared and compounded with polyethylene. The oxygen permeability coefficients and tensile properties of the nanocomposites were correlated to the exfoliation of the OMs. Partial exfoliation was achieved, although no intercalation was observed. Aromatic moieties attached to the clay surface led to a stronger interaction between the OM layers and less exfoliation.

Transmission electron micrograph of a 2.8 vol.‐% dioctadecyldimethylammonium nanocomposite. The dark lines are cross sections of aluminosilicate layers.     

Electronic structure of 4H-pyrido[1,2-a]pyrimidin-4-ones

The characteristic features of ir and uv spectra of 43 4H-pyrido[1,2-a]pyrimidin-4-one derivatives with electron donor or acceptor groups in position 3, and positions 6, 7, 8, or 9, respectively, have been systematically studied. On the basis of the spectra some conclusions have been drawn for the molecular structure. The negative solvent effect of the lowest-energy π → π* transition is investigated by the PPP method.     

Characterization of the barrier parameter of homogeneous convex cones

We characterize the smallest (best) barrier parameter of self-concordant barriers for homogeneous convex cones. In particular, we prove that this parameter is the same as the rank of the cone which is the number of steps in a recursive construction of the cone (Siegel domain construction). We also provide lower bounds on the barrier parameter in terms of the Carathéodory number of the cone. The bounds are tight for homogeneous self-dual cones. © 1998 The Mathematical Programming Society, Inc. Published by Elsevier Science B.V.Research supported in part by an operating grant from NSERC of Canada.Research supported in part by the National Science Foundation under grant DMS-9306318.     

Polymerization of monoisocyanates by the Pruitt–Baggett adduct

n-Butyl isocyanate (nBIC) was polymerized in bulk by the Pruitt–Baggett adduct (PBA) at ?23, 0.0, and 25.0°C. Polymerization was accompanied by trimerization to the cyclicisocyanurates at all temperatures. Spectroscopic evidences supported the nylon-1 structure for both trimer and polymer. The polymer/trimer ratio and the molecular weight of produced polymers were found to increase with decreasing temperature. The Pruitt–Baggett catalyst (PBC), which is the reaction product of (PBA + H₂O) system, also polymerized nBIC, but with a relatively slower rate. In aromatic and etheric solutions, nBIC was only trimerized by PBA. Copolymerization of nBIC with propylene oxide by PBA and PBC failed. Some selected monoisocyanates were also polymerized by PBA. © 1993 John Wiley & Sons, Inc.