A WH/GSMT-based full-wave analysis for planar transmission linesembedded in multilayered dielectric substrates

A new full-wave analysis method, referred to as the WH/GSMT, is developed to solve multilayered planar transmission line problems. First, the scattering of an obliquely incident parallel plate mode (PPM) by a PEC half plane embedded in a multilayered isotropic dielectric substrate within a PEC parallel plate region is analyzed via the Wiener-Hopf (WH) technique. The solution is then incorporated into the generalized scattering matrix technique (GSMT) to find the (complex) propagation constant and characteristic impedance of the planar transmission lines. The lateral power leakage is taken into account rigorously in the WH/GSMT. Numerical results including the microstrip line, conductor-backed slotline, coupled microstrip lines, and antipodal finlines are presented along with a discussion of the advantages/disadvantages of this method     

Mitigating greenhouse gas and nitrogen loss with improved fertilizer management in rice: quantification and economic assessment

Several technologies have been developed to improve the recovery efficiency of N (RE_N) but their impacts on greenhouse gas (GHG) emission, N loss and economic implication are rarely analysed. A decision support system (DSS) has been developed to quantify inputs, outputs and balance of N in soil; GHG emission and RE_N with the prominent N management technologies in rice. This DSS, named InfoNitro (Information on Nitrogen Management Technologies in Rice), integrated analytical and expert knowledge with databases on bio-physical, agronomic and socio-economical features to establish input–output relationships related to N management in rice. Sixteen technologies, which differed in terms of water regime, method of N application, forms of N and tools of fertilizer recommendation were analysed for their RE_N, N losses, GHG emission and economic return in Haryana, a rice growing region in India. In the current farmers’ practice, RE_N was 32.7%, which increased up to 40.8% with various technologies except in mid-season drainage and alternate flooding technologies where it decreased up to 29.3%. Loss of N through leaching, volatilization and denitrification in the farmers’ practice (67.5 kg N ha⁻¹) decreased up to 40.5 kg N ha⁻¹ except in mid-season drainage and alternate flooding technologies where it increased. The technologies also reduced global warming potential (GWP) by 1 to 9%. However, the technologies except no tillage, mid-season drying and alternate flooding reduced the net income of the farmers. When the environmental cost (cost of N loss and GWP) was included net income with various technologies was either at par or more than the farmers’ practice. The marginal abatement cost of N loss was Rs. 8 to 134 kg⁻¹ N and for GWP was Rs. 766 to 4854 Mg⁻¹ CO₂ eq. Resource conserving technology was the most cost effective strategy to reduce N loss and GHG emission whereas integrated N management cost high for mitigating GHG emission.     

Thermal decomposition kinetics of photooxidized nylon 66

The thermoanalytical method offers a convenient means for testing a starting material before the end application. Differences in the kinetic parameters between neat and irradiated nylon 66 samples were estimated in the temperature range of 25°C–800°C by thermogravimetric analysis (TGA) and in the range of 25°C–300°C by differential scanning calorimetry (DSC). Under nitrogen flux the average activation energy for decomposition was in the range of 12.2–26.9 kcal/mol for the neat sample and 15.7–33.1 kcal/mol for the irradiated sample (250 h). Activation energy is affected by the process of bond breaking at the C? N bonds, which is the rate‐determining step of the decomposition in nylon 66. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2146–2150, 2003     

Study of uranium sorption using D2EHPA‐impregnated polymeric beads

The extractant‐impregnated polymeric beads (EIPBs), containing Di(2‐ethylhexyl) phosphonic acid (D2EHPA) as an extractant and polyethersulfone as base polymer, were prepared by phase‐inversion method. These beads were characterized by fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscope (SEM) analysis to gain insight into the composition and morphology of beads. The beads exhibited good acid stability as no significant structural deformation or leaching out of the extractant was observed in 6M HNO₃ solution, up to the studied equilibration time of 15 days. The synthesized EIPBs were evaluated, for their ability to absorb uranium from aqueous solution, at different concentration and pH values. The kinetics measurement showed that about 90 min of equilibration time was enough to remove saturation amount of uranium from the solution. Kinetic modeling analysis of the extraction results was carried out using pseudo‐first‐order, pseudo‐second‐order, and intraparticle diffusion equations and the corresponding rate constants were determined. The equilibrium data were fitted into different isotherm models and were found to be represented well by the Freundlich isotherm equation. Reusability of the beads was also established by multiple sorption–desorption experiments. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3355–3364, 2013     

Comparison of Hydrometallurgical Parameters of N,N‐Dialkylamides and of Tri‐n‐Butylphosphate

Straight‐chain N,N‐dihexyloctanamide (DHOA) and branched‐chain N,N‐di(2‐ethylhexyl)isobutyramide (D2EHIBA) have been identified as promising alternatives to tri‐n‐butylphosphate (TBP) for the reprocessing of spent uranium based fuels, and selective extraction of ²³³U from irradiated thorium fuels, respectively. The present work deals with the effects of different hydrodynamic parameters such as viscosity, density, and interfacial tension (IFT) on the phase‐separation time (PST) under uranium and thorium loading conditions. The IFT values have been determined under varying experimental conditions such as the aqueous nitric acid concentration, n‐dodecane purity, ligand concentration, and thorium/uranium loading conditions. These studies have suggested that the quality of n‐dodecane affects the IFT values of different solutions. The IFT values of D2EHIBA changed marginally (23.3 ± 0.9 mNm^?1) against THOREX feed solution for the wide range of D2EHIBA concentration (0.1–1.0 M). However, IFT, viscosity, and PST values increased with uranium loading of 1.1 M DHOA. These studies suggested that a lower phase‐disengagement rate with increased uranium loading was mainly due to the increased viscosity of the loaded 1.1 M DHOA solution.     

Metal hollow sphere electrocatalysts

Metal micro-/nano hollow spheres have been widely applied in numerous fields during the last decade. This review will only focus on the synthetic strategies to synthesize hollow spherical structures in the enhancement of their electrocatalytic activity, especially the metal hollow spherical materials. We present a comprehensive overview of synthetic strategies for metal hollow spherical structures which have been approached specifically in electrochemical reactions. These synthetic methods are mainly categorized as hard templates, soft templates, sacrificial templates and without templates. The review further includes electrocatalytic approaches of hollow spherical metals in different electrochemical processes, especially the methanol electro-oxidation reaction for methanol fuel cell application and hydrogen and oxygen evolution reactions in water electrolyzer, as metal hollow spherical materials are especially applied in these specific reactions.     

A study on effect of mineral additions on the mechanical,thermal, and structural properties of poly(butylene terephthalate) (PBT) composites

Fillers play a major role in determining the properties and behavior of polymer composites. In this study a series of polybutylene terephthalate composites are fabricated using mica and talc particles as filler materials. The effects of these two different minerals on the mechanical, thermal and structural properties of composites are investigated. Comparative analysis shows that both the fillers have different effect on tensile strength and elongation at break. The experimental results when compared with theoretical predictions reveal high level of interfacial interaction in both the composite systems. The interaction parameter B derived using Pukanszky equation is found to be higher in mica filled composites which is in agreement with its better mechanical response. Microscopic observation by SEM reveals that both fillers exhibit different fracture micromechanics leading to different reinforcing effects in PBT.     

Optical properties of ZnS nanoparticles produced by mechanochemical method

Nanosized zinc sulfide (ZnS) has been synthesized by the mechanochemical route using zinc acetate and sodium sulfide as source materials in a high energy planetary ball mill (HEPBM) with 300 rpm for 2 h. The mechanochemically synthesized powders have been analyzed by X-ray diffraction (XRD) for phase analysis, Field Emission Scanning Electron Microscope (FESEM) for the morphological characterization, UV–vis–NIR spectrophotometer for determining band gap energy and Fluorescence spectroscopy for determining the emission wavelength. The crystallite size of the synthesized ZnS nanoparticles calculated by the Debye–Scherer's formula is in the range 7–9 nm. FESEM morphology shows the fibrous structure of ZnS samples. The value of optical band gap has been found to be in the range 5.2–5.3 eV. Room temperature photoluminescence (PL) spectrum of the samples exhibits a blue light emission using UV excitation wavelength of 280 nm.     

Effect of functionalized elastomer addition on mechanical and interfacial properties of poly (butylene terephthalate)/glass fiber composites

In this study the effect of incorporation of ethylene‐co‐glycidylmethacrylate (GMA)‐co‐n‐butyl acrylate (nBA) terpolymer with an epoxy functional group, on the mechanical performance of short glass fiber (SGF)/Poly (butylene terephthalate) (PBT) composites has been investigated. Tensile test showed that incorporation of rubber phase in PBT/SGF composites results in loss of strength. However impact measurement exhibited an increase in impact strength with an increase in rubber content. Tensile and impact properties are discussed in terms of interfacial shear strength and morphology of composites. Morphological observation by SEM revealed a thin layer of polymer adhering to the surface of glass fibers indicating that epoxy functional group in the modifier reacts with fiber surface and PBT matrix. This reactivity of epoxy functional group is also supported by FTIR observations. The composites are also analyzed for % crystallinity using DSC and a strong correlation is found to exist between interfacial shear strength and % crystallinity. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

Synthesis and Characterization of Porogen Based Porous Low-k Thin Films

The present work is focused towards the lowering of the k value of deposited SiO₂ thin films by varying solvent concentration i.e. ethanol in the range 4-10 ml. Porous low-k thin films were synthesized by using the sol-gel spinon technique. A non-ionic surfactant polysorbate 80 (Tween 80) was used as a porogen to generate the porosity in the film matrix. The lower values of refractive index and film density were measured to be 1.19 and 0.94 gm/cm³ respectively for 10 ml solvent concentration. Further, the lowest k value of 2.2 and highest porosity percentage of 58.5 % were obtained for the same film due to the dilution of coating solution at higher solvent concentration. The water contact angle of the film was observed to be increased to 106.3° which indicates the transformation of the deposited film surface from hydrophilic to hydrophobic. The change in chemical structure as an effect of solvent concentration is studied by using FTIR. From FTIR spectra the disappearance of Si-OH groups at higher solvent concentration reveals the increase in condensation rate. Overall in this study, the result shows the significant change in structural, chemical and optical properties of the deposited films at 10 ml solvent concentration. Such deposited porous thin films with lower k value and enhanced hydrophobicity can be used as an interlayer dielectric (ILD) for back end of line (BEOL) in CMOS technology.