Direct Growth and Photoluminescence of SiO<Subscript>x</Subscript> Nanowires and Aligned Nanocakes by Simple Carbothermal Evaporation

The growth of SiO_x nanowires and nanocakes on an Au-coated n-type-Silicon (100) substrate was achieved via carbothermal evaporation. The effects of the Au layer thickness and the rapid heating rate on the morphology of obtained SiO_x nanowires were investigated. A broad emission band from 290 to 600 nm was observed in the photoluminescence (PL) spectrum of these nanowires. There are four PL peaks: one blue emission peak 485 nm (2.56 eV) two green bands centered at 502 nm (2.47 eV) and 524 nm (2.37 eV) for nanocakes and one ultraviolet emission peak at 350 nm (3.54 eV) and a hemisphere curve over the bluish green area taken for SiO_x nanowires. These emissions may be related to the various oxygen defects and twofold coordinated silicon lone pair centers.     

Flammability behavior of fiber–fiber hybrid fabrics and composites

The effect of heat flux levels on burning behavior and heat transmission properties of hybrid fabrics and composites has been investigated using cone calorimeter and heat transmission techniques. The hybrid fabric structures woven out of E‐glass (warp) and polyether ether ketone (PEEK) (weft) and E‐glass (warp) and polyester (weft) have been studied at high heat flux levels keeping in view the flame retardant requirements of structural composites. The performance of the glass–PEEK fabric even at high heat flux levels of 75 kW/m² was comparable with the performance of glass–polyester fabric evaluated at 50 kW/m². The results further demonstrate that glass–PEEK hybrid fabrics exhibit low peak heat release rate, low heat release rate, low heat of combustion, suggesting an excellent combination of materials and fall under the low‐risk category and are comparable with the performance of carbon fiber‐epoxy‐based systems. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Physico-mechanical and degradation properties of biodegradable photografted coir fiber with acrylic monomers

Coir fibers were modified with 2-hydroxyethyl methacrylate (HEMA), methyl methacrylate (MMA) and 2-hydroxyethyl acrylate (2-HEA) solutions under UV radiation. Monomer concentration and radiation dose were optimized in terms of grafting and tensile properties. It was found that 20 % HEMA at 20th UV pass, 30 % MMA at 15th UV pass and 25 % 2-HEA at 20th UV pass of radiation produced higher tensile properties over untreated sample. Urea of different concentrations (0.5–2 %) were incorporated into optimized solutions and 1 % urea showed the best properties of the fiber. Water uptake behavior and simulating weathering degradation properties were also performed.     

Modification of Rheological Properties Under Elongational Flow by Addition of Polymeric Fine Fibers

A new technique to provide melt elasticity using flexible fine fibers prepared from a polymer with high melting point is demonstrated. A polymer composite of poly(propylene) with a small amount of fine fibers of poly(butylene terephthalate) shows marked strain‐hardening behavior in elongational viscosity, i.e., a rapid increase in the transient elongational viscosity with time or strain. The blend also shows prominent normal stress difference at steady shear. These elastic properties have not been observed for polymer composites with rigid fibers and can be applicable to the modification of rheological properties and thus the improvement of processability.

     

Farmer's view on soil organic matter depletion and its management in Bangladesh

Bangladesh is an agricultural country. About 80% of the total population live in rural areas. The contribution of agriculture to the gross domestic product is 30%. Rice is the major food crop while jute, sugarcane and tea are the main cash crops. Other important crops are wheat, tobacco, pulses, vegetables and fruits. Overall productivity in Bangladesh is stagnating or declining. The implication of yield stagnation or declining productivity is severe, since these trends have occurred despite rapid growth in the use of chemical fertilisers. Depletion of soil organic matter is the main cause of low productivity, which is considered one of the most serious threats to the sustainability of agriculture in Bangladesh. In Bangladesh, most soils have less than 17 g/kg and some soils have less than 10 g/kg organic matter. Farmers realise that there is a problem with soil fertility related to organic matter depletion. Farmers say that organic matter increases yield, reduces the production cost, improves crop growth and the economy, increases water-holding capacity and improves the soil structure. They recognise soil with higher organic matter content by darker brownish to black in colour. Some farmers are using fast-growing trees such as Flemingia macrophyla, Ipilipil (Leucaen leucophala), Glyricidia sepium, Boga Medula (Tephrosia candida), Dhol Kolmi (Ipomoea fistulosa), etc., as living fences, which can be used as fuel, fertiliser and fodder. To increase the soil organic matter, farmers use green manure crops, compost, quick compost, cow dung, azolla, etc. However, fuel for cooking purposes is limited and cow dung and crop residues are largely used as fuel. Crop residues are also used as fodder for livestock. Farmers expressed the wish to learn more about organic fertilizer management. However, sufficient food should be produced to keep pace with population growth. To alleviate the hunger and poverty is to increase the intensity of agricultural production and maintain favorable ecological conditions. Therefore, more organic matter should be used in the farmers' fields to sustain the soil fertility in an intensive farming system. This revised version was published online in June 2006 with corrections to the Cover Date.     

Prediction and sensitivity analysis of CNTs-modified asphalt’s adhesion force using a radial basis neural network model

Abstract

The expected longer service life of modified asphalt can be jeopardized by different environmental factors, such as moisture, oxidation, etc. which affect the desired properties by altering the adhesive property. An insight into knowledge of the adhesive property of the asphalt can help in providing more durable asphalt pavement. The study attempted to develop different models of adhesive properties of polymers and carbon nanotubes (CNTs) modified asphalt binders. The polymer-CNT modified asphalt is processed to prepare different types of samples, by simulating the damage due to moisture and oxidization, following the corresponding standard method. An Atomic Force Microscopy (AFM) was employed to assess the nanoscale adhesion force of the tested samples following the existing functional group in asphalt. Finally, the study has developed Radial Basis Function Neural Network (RBFNN) as a function of different parameters including; asphalt chemistry (i.e. AFM tip type and constant), type and percentages of polymers and CNTs and different environmental exposures (oxidation, moisture, etc.) to predict the nano adhesion force of asphalt. It is observed that the adhesive property of the Styrene–Butadiene modified asphalt is more consistent compared to the Styrene–Butadiene–Styrene modified asphalt, while the presence of Single-Wall Nanotubes (SWNT) is observed to affect the adhesive properties of asphalt significantly as compared to Multi-Wall Nanotubes (MWNT). The higher accuracy level of RBFNN model also indicates that the functional group (tip-type) adding with the percentages and types of polymers and CNTs significantly affect the adhesive properties of asphalt.     

Influence of Different Additives on the Interaction of Quinolone Antibiotic Drug with Surfactant: Conductivity and Cloud Point Measurement Study

Conductometric and cloud point (CP) measurement studies have been performed to investigate the interaction of tetradecyltrimethylammonium bromide (TTAB) and Triton® X-100 (TX-100) with ciprofloxacin hydrochloride (CFH) in different solvents over the temperature range of 295.15–315.15 K. CFH is used for the treatment of various bacterial infections. The observed critical micelle concentration (CMC) values of TTAB were found to be reduced in the presence of electrolytes (Na₂SO₄/Na₃PO₄), and this reduction proceeds with the elevation of salt concentration. The order of the CMC of TTAB follows the trend: > >. The observed CMC values of TTAB were found to increase with increasing temperature and decrease with increasing concentration of CFH in aqueous medium. The values of Gibbs free energy of micellization () for the TTAB/TTAB + CFH mixture were found to be negative, implying spontaneous micellization. The estimated CP of TX-100 decreases with increasing concentration of TX-100 in aqueous medium. The CP values first decrease with increasing concentration of CFH and then increase at higher concentration of CFH almost in all cases investigated. The values of free energy of clouding were found to be positive in all cases studied implying that phase separation of TX-100 was nonspontaneous. The other thermodynamic parameters associated with the micellization of TTAB and the phase separation of TX-100 were estimated and explained.