Enhancement of electroconductivity of polyaniline/graphene oxide nanocomposites through in situ emulsion polymerization

The present study introduces a systematic approach to disperse graphene oxide (GO) during emulsion polymerization (EP) of Polyaniline (PANI) to form nanocomposites with improved electrical conductivities. PANI/GO samples were fabricated by loading different weight percents (wt%) of GO through modified in situ EP of the aniline monomer. The polymerization process was carried out in the presence of a functionalized protonic acid such as dodecyl benzene sulfonic acid, which acts both as an emulsifier and protonating agent. The microstructure of the PANI/GO nanocomposites was studied by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV–Vis spectrometry, Fourier transform infrared, differential thermal, and thermogravimetric analyses. The formed nanocomposites exhibited superior morphology and thermal stability. Meanwhile, the electrical conductivities of the nanocomposite pellets pressed at different applied pressures were determined using the four-probe analyzer. It was observed that the addition of GO was an essential component to improving the thermal stability and electrical conductivities of the PANI/GO nanocomposites. The electrical conductivities of the nanocomposites were considerably enhanced as compared to those of the individual PANI samples pressed at the same pressures. An enhanced conductivity of 474 S/m was observed at 5 wt% GO loading and an applied pressure of 6 t. Therefore, PANI/GO composites with desirable properties for various semiconductor applications can be obtained by in situ addition of GO during the polymerization process.     

Availability of certain nutrients in cereals reconstituted with or without enzymes for chickens

BACKGROUND: The presence of various anti‐nutritional factors, poor digestibility of the protein and carbohydrates greatly affect the utilisation of cereal grains in birds. Therefore, in the present investigation, efforts were made to augment the availability of certain nutrients of cereal grains through reconstitution with or without added enzymes. RESULTS: Reconstitution of grains with enzymes increased the apparent metabolisable energy‐nitrogen corrected (AMEn) values of pearl millet, sorghum, maize and wheat by 10.81, 7.39, 1.74 and 5.11% over untreated grains, while the corresponding increase for the grains reconstituted without enzymes was 8.28, 5.45, 1.95 and 0.06%, respectively. The reconstitution of cereal grains without added enzymes improved the in vitro pepsin pancreatin digestibility (IVPPD) of pearl millet, sorghum, maize and wheat by 19, 23, 20 and 11% over their respective untreated counterparts. Reconstitution with or without enzymes reduced the available carbohydrates and acid detergent fibre contents. The phytate contents were decreased significantly (P < 0.01) due to reconstitution with or without enzymes up to 48‐60% for all the grains. CONCLUSION: It may be inferred that the reconstitution of the grains caused significant reduction in anti‐nutritional factors of the grains, which was accompanied by significant improvement in nutrient availability. Reconstitution was found to be less expensive method of feed processing and can easily be adopted under field conditions. Addition of enzymes in the process of reconstitution provided additional advantage in nutrient availability for all the cereals except maize, and the improvement was much higher in wheat. Copyright © 2008 Society of Chemical Industry     

Soil salinity of urban turf areas irrigated with saline water: I. Spatial variability

With increasing use of saline water for irrigating urban landscapes, soil salinization is becoming a concern. This study examined spatial variation in soil salinity over the length of selected fairways at five golf courses, and of large turf areas at two public parks located in west Texas and southern New Mexico. Salinity of water used for irrigation ranged from 680 to 2700 mg L⁻¹, and the sites consisted mostly of Aridisols (upland soils) or Entisols (alluvial soils). Soil salinity distribution at sites consisting of deep Aridisols was spatially independent with the coefficient of variability (CV) ranging from 24 to 42%. The sites consisting of shallow Aridisols over a calcic horizon had erratic and random soil salinity distributions with an average CV of 37%. Since soil salinity distributions in Aridisols and Alfisols appeared to be spatially independent within the distance of fairways, soil sampling adequacy can be determined by the conventional probability statistics. However, salinity distributions at Entisols sites were spatially dependant to a length of 100 m or more. In addition, the clayey Entisols used for public parks had high levels of salt accumulation (>10 dS m⁻¹ in the saturation extract) with the CV exceeding 60%. When salinity readings were stratified by soil type distribution, the CV was reduced to 28% on the average. The number of samples required to obtain the mean salinity over a typical length of fairways (250–300 m) within a deviate range of 20% averaged 6 in deep sandy Aridisols and Alfisols, and 13 each in other cases, provided that sampling of Entisols is made based on soil type distributions. These sampling requirements are greater than those for field soil moisture or saturation water contents. The spacing to collect the required number of samples over the prevailing length of fairways was between 23 and 38 m. Soil sampling for salinity appraisal is most problematic in Entisols, but can be made simple if a detailed soil map is available. In Aridisols containing a calcic horizon, it is probable to have saline spots over poorly permeable caliche.     

Efficient solar photo-electrochemical hydrogen generation using nanocrystalline CeFeO3 synthesized by a modified microwave assisted method

Pure phase of CeFeO₃ perovskite was synthesized by using a modified microwave-assisted method and was systematically studied by photo-electrochemical (PEC) investigations for water splitting reaction. Characterization studies confirm the formation of crystalline orthorhombic single phase perovskite structure with space group Pbnm and having agglomerated sponge-like morphology with nano size grains. DRS shows broad absorption in UV–Visible region, while tauc plot also inferred estimated band gap of 1.9 eV. The photo-activity of their screen printed thin film was analyzed by PEC studies, which includes photocurrent, EIS spectra, MS-plot, J-V plots. On illumination, EIS analysis of CeFeO₃ reveals improved charge transfer at interfaces of semiconductor/electrolyte. The photocurrent density difference of CeFeO₃ was increased to 6.9 mA cm^?2 at an applied bias of 1.5 V vs (Ag/AgCl). PEC H₂ evolution shows significant cumulative hydrogen rate of 12.3 μmol cm^?2 h^?1. All these results reveal that the microwave-synthesized CeFeO₃ is a potential candidate for PEC application under the visible light illumination.     

A study on nuclear analysis of the divertor region of the CFETR

This paper presents the nuclear analysis performance of the Chinese Fusion Engineering Test Reactor(CFETR)divertor region using the MCNP-5 Monte Carlo N-particles code in a 3D geometry model.We assessed the nuclear responses of the divertor region component systems and evaluated their shielding capability,which can support the development strategy of the physical and engineering design of the CFETR.Model specification based on the latest CAD model of the CFETR divertor has been integrated into the CFETR MCNP reference model with a major/minor radius R=7.2 m/a=2.2 m in the 22.5° model,and a fusion-power range of around 1-1.5 GW.The nuclear heating and radiation damage of the divertor system are enhanced compared to that of the ITER and the earlier CFETR design.The initial nuclear responses of the toroidal field coil and vacuum vessel systems showed that the shielding of the current divertor design is not sufficient and optimization work has been carried out.We also carried out calculations and analysis using a hypothetical operating scenario of over 14 years.An excellent improvement in the nuclear performance has been obtained by the improved additional shielding block in the divertor region when referring to the ITER design limit,which can support the design of the future update of the divertor region systems of the CFETR.     

Perovskite-type catalytic materials for environmental applications

Perovskites are mixed-metal oxides that are attracting much scientific and application interest owing to their low price, adaptability, and thermal stability, which often depend on bulk and surface characteristics. These materials have been extensively explored for their catalytic, electrical, magnetic, and optical properties. They are promising candidates for the photocatalytic splitting of water and have also been extensively studied for environmental catalysis applications. Oxygen and cation non-stoichiometry can be tailored in a large number of perovskite compositions to achieve the desired catalytic activity, including multifunctional catalytic properties. Despite the extensive uses, the commercial success for this class of perovskite-based catalytic materials has not been achieved for vehicle exhaust emission control or for many other environmental applications. With recent advances in synthesis techniques, including the preparation of supported perovskites, and increasing understanding of promoted substitute perovskite-type materials, there is a growing interest in applied studies of perovskite-type catalytic materials. We have studied a number of perovskites based on Co, Mn, Ru, and Fe and their substituted compositions for their catalytic activity in terms of diesel soot oxidation, three-way catalysis, N₂O decomposition, low-temperature CO oxidation, oxidation of volatile organic compounds, etc. The enhanced catalytic activity of these materials is attributed mainly to their altered redox properties, the promotional effect of co-ions, and the increased exposure of catalytically active transition metals in certain preparations. The recent lowering of sulfur content in fuel and concerns over the cost and availability of precious metals are responsible for renewed interest in perovskite-type catalysts for environmental applications.     

Evaluation of Mechanical and Thermal Performance of Polyethylene Terephthalate Recycled Ribbon and Carbon-Reinforced Compatibilized Polypropylene

Polypropylene (PP) and polyethylene terephthalate (PET) are the two most widely used plastics, which are not compatible with recycling as a blend. In this research work, two different compositions of recycled PP/PET ribbon 65/35 (v/v %) and 78/22 (v/v%) along with 5% (wt%) of polypropylene-grafted maleic anhydride (PP-g-MAH) as compatibilizer were blended, 2– 5 wt% of carbon fiber (CF) was further added for reinforcement. The compositions of these materials are mechanically mixed and extruded by a twin-screw extruder to make pellets. These pellets are then used to produce standard samples by injection molding for evaluation. The molded samples were tested under tensile, flexural and impact loads to evaluate mechanical properties. Scanning electron microscopy (SEM) was conducted on the fracture surface of the impact-tested samples to understand polymer blend morphology. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) also carried out to check the thermal properties, mainly transition temperatures (T_g) and heat flow. These test results compared, which show substantial improvement in mechanical properties by adding CF and compatibilizer, without much change in transition temperatures. POLYM. ENG. SCI., 60:575–580, 2020. © 2019 Society of Plastics Engineers     

Carbon nanotube‐based thermoplastic polyurethane‐poly(methyl methacrylate) nanocomposites for pressure sensing applications

We have synthesized unique flexible pressure‐sensitive nanocomposites by means of a solution mixing method, by adding multiwalled carbon nanotubes (MWCNTs) into a thermoplastic urethane (TPU) matrix along with poly(methyl methacrylate) (PMMA) microbeads of various sizes. The influence of the various PMMA bead sizes on the pressure sensing properties of the nanocomposites was studied over a range of pressures. The PMMA microbeads were used to achieve an early percolation threshold at low loadings of MWCNTs. We used scanning electron microscopy to study the nanocomposites' morphology, and conducted differential scanning calorimetry analyses to investigate their thermal properties. The nanocomposites' electrical and thermal conductivities were also measured under various applied pressures. The nanocomposites displayed repeatable electrical responses under various applied pressures, demonstrating their suitability for use as pressure sensing materials. The proposed material is an ideal candidate for use in the preparation of pressure‐sensitive devices. POLYM. ENG. SCI. 56:1031–1036, 2016. © 2016 Society of Plastics Engineers