Wet oxidative method for removal of 2,4,6-trichlorophenol in water using Fe(III), Co(II), Ni(II) supported MCM41 catalysts

Chlorophenols in water are resistant to biological oxidation and they have to be destroyed by chemical oxidation. In the present work, Fe(III), Co(II) and Ni(II) incorporated MCM41 mesoporous solids were used as catalysts for oxidation of 2,4,6-trichlorophenol in water with or without the oxidant, H₂O₂. The catalysts were prepared by impregnation and were characterized by XRD and FTIR measurements. The parent MCM41, Fe(III), Co(II) and Ni(II) impregnated MCM41 had cation exchange capacity of 20.5, 25.5, 24.2, 26.0 mequiv./100 g, respectively. The catalysts were used after calcination at 773–873 K for 5 h. The reactions were carried out in a high pressure stirred reactor at 0.2 MPa (autogenous) and 353 K under various reaction conditions. The conversion achieved with Fe(III), Co(II) and Ni(II) incorporated MCM41 in 5 h is respectively 59.4, 50.0 and 65.6% with 2,4,6-TCP:H₂O₂ molar ratio of 1:1, and 60.2, 60.9 and 68.8% in absence of H₂O₂. The oxidation has a first order rate coefficient of (1.2–4.8) × 10⁻³ min⁻¹. The results show that introduction of Fe(III), Co(II) and Ni(II) into MCM-41 through impregnation produces very effective catalysts for wet oxidation of 2,4,6-trichlorophenol.     

Enhanced dissolution of ibuprofen using solid dispersion with polyethylene glycol 20000

To improve its dissolution, ibuprofen solid dispersions (SDs) were prepared in a relatively easy and simple manner, characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), and evaluated for solubility and in vitro drug release. Loss of individual surface properties during melting and re-solidification as revealed by SEM micrographs indicated the formation of effective SDs. Absence or shifting toward the lower melting temperature of the drug peak in SDs in DSC study indicated the possibilities of drug-polymer interactions. FTIR spectra showed the presence of drug crystalline in SDs. The effect of improved dissolution on the oral absorption of ibuprofen in rats was also studied. Quicker release of ibuprofen from SDs in rat intestine resulted in a significant increase in AUC and C(max), and a significant decrease in T(max) over pure ibuprofen. Preliminary results from this study suggested that the preparation of fast dissolving ibuprofen SDs by low-temperature melting method using polyethylene glycol 20000 as a meltable hydrophilic polymer carrier could be a promising approach to improve solubility, dissolution, and absorption rate of ibuprofen.     

Controlled Synthesis of the Henry Reaction Products: Nitroalcohol Versus Nitrostyrene by a Simple Change of Amino-Groups of Aminofunctionalized Nanoporous Catalysts

A synthetic method for controlling the Henry reaction products from nitrostyrene to nitroalcohol in heterogeneous catalysis by a simple change of the catalytic sites in organoamine-functionalized mesoporous catalysts is reported. The synthesis resulted in either β-nitrostyrene or β-nitroalcohol by simple change of the types of amine functional groups in the amine-functionalized mesoporous catalysts from primary amines into secondary or tertiary.     

Removal of lead(II) by adsorption using treated granular activated carbon: batch and column studies

In the present study, a deeper understanding of adsorption behavior of Pb(II) from aqueous systems onto activated carbon and treated activated carbon has been attempted via static and column mode studies under various conditions. It probes mainly two adsorbents that is, activated carbon (AC) and modified activated carbon (AC-S). Characterization of both the adsorbents was one of the key focal areas of the present study. This has shown a clear change or demarcation in the various physical and chemical properties of the modified adsorbent from its precursor activated carbon. Both the adsorbents are subjected to static mode adsorption studies and then after a comparison based on isotherm analysis; more efficient adsorbent is screened for column mode adsorption studies. The lead removal increased for sample of treated carbon. The extent of Pb(II) removal was found to be higher in the treated activated carbon. The aim of carrying out the continuous-flow studies was to assess the effect of various process variables, viz., of bed height, hydraulic loading rate and initial feed concentration on breakthrough time and adsorption capacity. This has helped in ascertaining the practical applicability of the adsorbent. Breakthrough curves were plotted for the adsorption of lead on the adsorbent using continuous-flow column operation by varying different operating parameters like hydraulic loading rate (3.0-10.5 m3/(hm2)), bed height (0.3-0.5 m) and feed concentrations (2.0-6.0 mg/l). At the end, an attempt has also been made to model the data generated from column studies using the empirical relationship based on Bohart-Adams model. This model has provided an objective framework to the subjective interpretation of the adsorption system and the model constant obtained here can be used to achieve the ultimate objective of our study that is, up scaling and designing of adsorption process at the pilot plant scale level. AC-S column regeneration using 0.5 and 1.0M concentration of HNO3 has been investigated. It has shown a regeneration efficiency of 52.0% with 0.5 M HNO3.     

Polyurethanes as potential substrates for sub-retinal retinal pigment epithelial cell transplantation

Transplantation of cultured retinal pigment epithelial (RPE) cells under the failing macular is a potential treatment for age related macular degeneration. An important step in the development of this procedure is the identification of a suitable membrane on which to grow and transplant the cells. This paper evaluates the potential of using polyurethanes in this application since they possess several of the required properties, such as, flexibility, robustness, biostability and good biocompatiblilty although their hydrophobicity can limit cell adhesion. Three commercially available polyether urethanes (Pellethane, Tecoflex and Zytar) were evaluated in terms of their wettability using dynamic contact angle analysis and their ability to support a monolayer of functioning RPE cells (ARPE-19) . Furthermore Pellethane and Tecoflex were treated with a simple air plasma treatment and analysed as above. In the "as received condition" only a few RPE cells attached to the Pellethane and Tecoflex and remained clumped. RPE cells grew to confluence on the Zytar substrate by 7 days without further surface modification. Air gas plasma treatment of both Pellethane and Tecoflex increased the wettability of the surfaces and this resulted in the growth of a monolayer of well-spread RPE cells on both materials. Morphologically these cells grew with a normal 'cobblestone' phenotype. These results demonstrate the potential of these polyurethanes for this application.     

A note on the optimum design of four bar crank-rocker mechanismsNote sur le calcul optimum des mécanismes a quatre barres avec une manivelle

In this paper, the classical transmission angle problem is discussed from a general approximation point of view. It is shown that the least square and Chebyshev optimizations are two closely related approaches to this problem. A least square optimum solution to this problem is investigated by means of a parametric representation for the link lengths, and results are compared with those available in literature. It is found that the computations for the least square method can be easily performed by using a pocket calculator.     

Learning with a mutualistic teacher

The concept of a “mutualistic teacher” is introduced for unsupervised learning of the mean vectors of the components of a mixture of multivariate normal densities, when the number of classes is also unknown. The unsupervised learning problem is formulated here as a multi-stage quasi-supervised problem incorporating a cluster approach. The mutualistic teacher creates a quasi-supervised environment at each stage by picking out “mutual pairs” of samples and assigning identical (but unknown) labels to the individuals of each mutual pair. The number of classes, if not specified, can be determined at an intermediate stage. The risk in assigning identical labels to the individuals of mutual pairs is estimated. Results of some simulation studies are presented.     

Effect of mastication on molecular weight and molecular weight distribution of EPDM polymer and SBR

EPDM and SBR were masticated on an open mill. The temperature range of mastication for EPDM was 68–480°F. SBR was milled at 170–200°F. The gel-permeation chromatography analyses were made on the masticated samples. For EPDM at 68°F, molecular weight decreases and molecular weight distribution narrows with mastication time; the degradation process is nonrandom. At constant mastication time between 182 and 315°F, there is little change in molecular weight. Mastication for 18 min at 480°F broadens the molecular weight distribution; the degradation is random. For SBR at 170–200°F, molecular weight decreases and molecular weight distribution narrows with mastication time; the degradation process is also nonrandom. Nonrandom degradation for both EPDM and SBR results in a narrowing of the molecular weight distribution, without build-up of low molecular weight molecules, and without a shift in the peak molecular weight. This is contrary to nonrandom degradation of natural rubber where a shift in the peak molecular weight occurs with mastication time.