Preparation of Multiphase Poly(Styrene-co-Butyl acrylate)/Wax-Clay Nanocomposites via Miniemulsion Polymerization
Abstract— In the presence of different wax-clay nanocomposites concentrations, poly(styrene-co-butyl acrylate) P(S-co-BA) copolymers were prepared via free-radical random copolymerization of styrene and butyl acrylate in miniemulsion. Wax-clay nanocomposites were obtained through ultrasonic mixing at a temperature above the melting point of the wax at different clay loadings (1, 5, 7 and 10 wt%). The main objectives of this study were to obtain a good exfoliation of the clay platelets in the paraffin wax. The obtained wax-clay nanocomposites were then used as filler in the preparation of P(S-co-BA)/wax-clay nanocomposites via miniemulsion polymerization. X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicated that the clay platelets were mostly exfoliated in the paraffin wax at low concentrations, and partially exfoliated at high concentrations. The particles morphology of the P(S-co-BA)/wax-clay nanocomposite latexes was mainly determined by TEM, and the wax-clay nanocomposites were found to be encapsulated inside the P(S-co-BA) particles and that core/shell morphology was obtained. The morphology of the P(S-co-BA)/wax-clay nanocomposites (after film formation) ranged from exfoliated to intercalated structures, depending on the percentage of wax-clay nanocomposites loading. The impact of the wax-clay loading on the thermal stability and the thermo-mechanical properties of the final polymer wax-clay nanocomposites were determined.
Keywords— paraffin wax-clay, poly(styrene-co-butyl acrylate), nanocomposites, encapsulation, miniemulsion, core/shell
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On the Rational Dynamic Equation on Discrete Time Scales
Abstract— In this paper, we study the global stability, periodicity character and some other properties of solutions of the rational dynamic equation on discrete time scales
Keywords— Rational dynamic equation, Time scales, Equilibrium point, Global attractor, Periodicity, Boundedness, Invariant interval.
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Effect of establishment methods and weed-control measures on Broad leaf weeds, yield attributes and harvest index of wheat (Triticum aestivum L.)
Abstract— A field experiment was conducted during rabi season of 2013-2014 at Pantnagar, District, Udham Singh Nagar (Uttarakhand) to assess the effect of weed-control measures on Broad leaf weeds, nutrient uptake, yield attributes and harvest index under different establishment methods. ZTW recorded significantly higher total dry matter of BLWs over CTW and RTW at 60, 90 DAS and at maturity stage. Clodinafop-propargyl @ 60 g/ha recorded the maximum dry matter which was significantly higher over weedy and two hand weedings at 90 DAS and at maturity stage.. Number of grains per spike exhibited non-significant variation owing to establishment methods. Ready mix of clodinafop-propargyl + MSM @ 64 g/ha and clodinafop-propargyl @ 60 g/ha produced maximum number of grains per spike. Highest harvest index value was obtained under CTW which was at par with ZTW.The highest harvest index value was obtained with crop given clodinafop-propargyl @ 60 g/ha.
Keywords— zero tillage, conventional tillage, roto till seed drill, wheat, broad leaf weeds, yield attributes.
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Bacterial Isolates from Contact Lenses, Frames and Their Susceptibility to Disinfectants
Abstract— Bacteriological assessments of contact lenses and frames were determined using standard bacteriological methods and the susceptibility of the bacterial isolates to Clear Care Cleaning Disinfecting Solution (CCCDS), Eye-Look Optical Lens Cleaner (ELOC) and Hydrogen peroxide (H2O2) were assayed using disc diffusion technique. Bacterial isolates from the contact lenses and frames were: Staphylococcus aureus, Streptococcus spp , Pseudomonas aeruginosa, Coagulase negative (CoN) Staphylococcus spp , Bacillus spp, Citrobacter freundii, Corynebacterium spp , Escherichia coli , Haemophilus influenzae, Micrococcus spp. and Aeromonas hydrophila . Only 33 (55.0 %) contact lenses and 41 (68.3 %) frames swabs showed positive growth and of the 41 (68.3 %) frames’ swabs with positive growth, 23 (38.3 %) showed growth of single bacterial isolate, 10 (16.7 %) showed growth of two bacterial isolates, while polybacterial growth was present in 7 (13.3 %). Only 25 (75.8 %) males’ and 16 (59.3 %) females’ frames swabs had bacteria growth, while contact lenses and frames from aged 21-30 yrs and 41-50 yrs had the highest and lowest numbers of bacteria colonization, respectively. The highest and lowest bacteria colonization of contact lenses and frames were from the farmers and civil servants, respectively. Bacillus spp BS-F13, BS-F57 and CoN-Staphylococcus spp CS-C1 were resistant to CCCDS, ELOC and H2O2. P. aeruginosa PA-C50 and A. hydrophila AH-C32 were resistant to both ELOC and H2O2. Only 2/18 (11.1%) and 5/18 (27.8%) of the Gram negative bacteria were resistant to ELOC and H2O2, respectively. The inhibitory zones obtained using CCCDS and ELOC ranged from 6.7±2.5mm to 12.8±0.5mm and 6.8±0.5mm to 11.3±0.8mm, respectively. Conclusively, this study has provided data on the bacterial isolates associated with contact lenses, frames and also showed the considerable variations in the antibacterial efficacy of contact lenses disinfection solutions.
Keywords— Bacteria, Disinfectants, Contact Lenses, Frames, Susceptibility.