Effect of rare earth yttrium substitution on the structural,dielectric and electrical properties of nanosized nickel aluminate

In this communication, we have systematically investigated the effect of yttrium substitution on the structural, dielectric and electrical properties of nanosized NiAl_2−2xY_2xO₄ series (where x = 0.00, 0.01, 0.02, 0.03, 0.04, 0.05, 0.07 and 0.10). All the samples were prepared by chemical coprecipitation method. Powder X-ray diffraction (XRD) confirmed the formation of single phase cubic spinel structure in all the samples. Replacement of Al³⁺ ions by Y³⁺ ions results in a slight increase of lattice parameter. It was inferred that the substitution of yttrium suppressed the crystallite size growth. Transmission electron microscopy (TEM) validated the nanocrystalline nature of the samples. The Fourier transform infrared spectroscopy (FTIR) confirmed the preference of Y³⁺ ions at the octahedral B site. Room temperature dielectric properties, namely dielectric constant (?′), dielectric loss (tan δ), ac conductivity (σ_a.c.) and electrical modulus (M″) were studied as a function of applied frequency in the range from 1 kHz to 1 MHz. These studies indicate that all the samples show usual dielectric dispersion which is due to Maxwell–Wagner type Interfacial Polarization. The ac conductivity measurement suggests that the conduction mechanism is due to small polaron hopping. The electrical modulus results clearly indicate the presence of non-Debye type of dielectric relaxation in all the samples. The dc electrical resistivity measured in the temperature range of 303–373 K was found to increase with temperature and yttrium content.     

Treatment of dairy wastewater by inorganic coagulants: Parametric and disposal studies

Present study reports treatment of simulated dairy wastewater (SDW) by inorganic coagulants such as poly aluminum chloride (PAC), ferrous sulphate (FeSO₄) and potash alum (KAl(SO₄)₂·12H₂O). Batch coagulation experiments were conducted to evaluate the influence of initial pH (pH_i: 5–10) and coagulant dosage (m: 100–5000 mg/L) on chemical oxygen demand (COD) removal from SDW. Residual COD and system pH were observed as function of time. Optimum pH_i (pH_i,op) was found to be 8.0 for all the three coagulants. Optimum m (m_op) was found to be 300, 800 and 500 mg/L for PAC, FeSO₄ and KAl(SO₄)₂·12H₂O, respectively, giving 69.2, 66.5 and 63.8% COD removal efficiency in 30 min. Heating values of the sludge generated by the coagulants PAC, FeSO₄ and KAl(SO₄)₂·12H₂O were found to be 20.7, 29.6 and 17.3 MJ/kg, respectively.     

Influences of Annealing Temperature and Doping Concentration on Microstructural and Optical Properties of CeO2:Sm3+ Nanocrystals

Nanocrystals of CeO₂ with different doping concentrations of Sm³⁺ were synthesized by a novel and cost-effective method. The crystal structure, morphology and particle size were systematically investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Effects of the annealing temperature and doping concentrations on the microstructural properties of the crystals were studied. X-ray diffraction analysis indicates that the cubic structure of the CeO₂ is not affected by the doping of Sm³⁺ up to a doping concentration of 20%. Different structural parameters such as lattice constant, surface area, bulk density and porosity of the crystal were determined and discussed. Microscopic images of the CeO₂:Sm³⁺ suggest that the thermal decomposition of oxalate precursor is a suitable synthesis pathway to produce uniform-sized microparticles and nanoparticles. The influences of annealing temperature and doping concentration of Sm³⁺ on the optical properties of the nanocrystals were also discussed. The photoluminescence excitation spectra reveal that the charge transfer band is redshifted with increasing annealing temperatures. Emission attains its maximum intensity for Sm³⁺ concentration of 1%, and higher concentrations lead to emission quenching.     

Silver-doped sol-gel borate glasses: Dose-dependent effect on Pseudomonas aeruginosa biofilms and keratinocyte function

Borate-based glasses have generated great interest for wound healing applications due to their ability to incorporate biologically therapeutic ions which can then be released at the site of repair attributable to their high dissolution rates. In this study, the anti-bacterial activity and cytocompatibility of sol-gel–derived silver-doped borate glasses (AgBGs) of the compositional range (60)B₂O₃–(36)CaO–(4–x)P₂O₅–(x)Ag₂O, where x = 0.0, 0.3, 0.5, and 1 (mol.%) were investigated, in vitro. The dose-dependent anti-bacterial activity of AgBGs was demonstrated against Pseudomonas aeruginosa under both planktonic conditions and pre-formed biofilms, with up to 99.7% reduction in bacterial cell counts. Lower concentrations of ionic dissolution products from AgBGs were non-toxic to keratinocytes, stimulating their growth and metabolic activity. Furthermore, compositions containing 0.3 and 0.5 mol.% Ag significantly accelerated the migration of keratinocytes at two different concentrations in an in vitro 2D wound healing model. In summary, these therapeutic AgBGs have demonstrated potential for accelerated wound healing.     

Electrical characterization of nanocrystalline SnSe and ZnSe thin films: effect of annealing

In this paper, experimental data on the electrical properties of as deposited and annealed nanocrystalline SnSe and ZnSe thin films are reported. The thin films of SnSe and ZnSe are deposited on glass substrate by chemical bath deposition method. The films are studied before and after thermal annealing at temperatures 473 K for 1 h. This annealing is done in vacuum of 2?×?10^?3 mbar. The various electrical parameters like dark conductivity, photoconductivity, activation energy, photosensitivity and carrier life time have been measured on these films before and after annealing.     

Chitosan from Muga silkworms (Antheraea assamensis) and its influence on thermal degradation behavior of poly(lactic acid) based biocomposite films

The research work is focused on extraction of chitin from Muga silkworms (MS) and its conversion into chitosan by chemical treatment process. The extracted amount of chitin and chitosan from MS were obtained ～8 wt % and ～7 wt %, respectively. Potentiometric titrations, conductometric titrations, elemental analysis, ¹H‐NMR and FTIR analyses were employed to calculate the degree of deacetylation of chitosan (extracted at 80 ºC after 10 h) and found as 77% ± 2, 81% ± 1.8, 82% ± 2.4, 97.77% ± 0.3, and 82% ± 1.8, respectively. The deacetylation process of chitin showed pseudo‐first order reaction kinetics and activation energy was estimated as ～15.5 kJ/mole. The extracted chitosan (at 80 ºC after 10 h) showed higher crystallinity and improved thermal stability with respect to chitosan extracted from other marine sources. Subsequently, poly(lactic acid) (PLA) and extracted chitosan dispersed biocomposite films were prepared by solution casting method. Significant dispersion of chitosan (extracted at 80 ºC after 10 h) micro‐particles were observed in biocomposite films using FESEM analysis. Due to chitosan interaction with PLA, significant reduction in thermal degradation and activation energy was observed during nonisothermal degradation scan of such films using Flynn‐Wall‐Ozawa and Kissinger‐Akahira‐Sunose models. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43710.     

Polyethylene/sepiolite clay nanocomposites: Effect of clay content,compatibilizer polarity,and molar mass on viscoelastic and dynamic mechanical properties

In this work, high‐density polyethylene (HDPE)‐based nanocomposites having different concentrations of Sepiolite (1–10 wt %) and compatibilizer, that is, PE‐graft‐maleic anhydride (PE‐g‐MA) of varying molecular weight and maleic anhydride content were prepared by melt compounding. The influence of Sepiolite amount and compatibilizer polarity and molar mass on the crystallization behavior [differential scanning calorimeter (DSC) and X‐ray diffraction (XRD)], rheological properties (oscillatory rheometer) and dimensional stability [dynamic mechanical analyzer (DMA) and heat deflection temperature (HDT)] of the nanocomposites was investigated. It was found that Sepiolite did not affect the crystallization behavior of HDPE. The rheological results show that the incorporation of Sepiolite into HDPE matrix up to 10 wt % increases the complex viscosity of polymer. Storage modulus and loss modulus both in oscillatory rheometry and in DMA were highest for nanocomposite prepared using 10 wt % Sepiolite owing to the improved mechanical restrain by the dispersed phase. In the presence of compatibilizer, the values of storage modulus and loss modulus were lower as compared to uncompatibilized nanocomposites at same loading of Sepiolite. The reduction in modulus is more pronounced in composites prepared using compatibilizer of lower molar mass as compared to those prepared using higher molar mass compatibilizer. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45197.     

Leanness evaluation using IF–THEN rules

Lean manufacturing is a manufacturing system aimed at waste elimination thereby streamlining the process. Leanness is the performance measure of lean manufacturing. The measurement of leanness necessitates fuzzy logic, due of the existence of impreciseness and vagueness. The calculation of leanness using fuzzy logic manually is a time consuming and highly repetitive job. To overcome this, fuzzy logic-based inference method has been attempted in this research study. A conceptual model consisting of three levels namely enabler, criterion, and attributes has been developed. Then the linguistic variables are assigned and the membership functions are defined. Leanness level has been computed using IF–THEN rules based interface method. This is followed by gap analysis to identify the weaker criteria. Then suitable proposals have been derived to overcome these obstacles towards leanness improvement of the organization.     

Adsorptive desulfurization by zinc-impregnated activated carbon: characterization,kinetics, isotherms,and thermodynamic modeling

Sulfur oxides emission because of burning of liquid fuels has become a global environmental challenge. Refineries need to meet ever-stringent liquid fuel standards by using newer desulfurization methods. Present paper reports the results of the studies on adsorptive removal of sulfur compounds from model fuel by zinc-impregnated granular activated carbon (GAC). Zn-loaded adsorbent (Zn-GAC) prepared by wet impregnation method was characterized for its textural, morphological, and structural characteristics by different techniques like liquid nitrogen adsorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The adsorbent was further used for the removal of dibenzothiophene (DBT), a sulfur compound, from iso-octane. Equilibrium adsorption was obtained in 6 h. The equilibrium adsorption data were well represented by the Redlich–Peterson isotherm. Thermodynamic parameters were calculated by applying the van’t Hoff and Clausius–Clapeyron equations. Values of change in enthalpy and entropy were found to be 4.89 kJ/mol and 30 J/mol K, respectively. Isosteric heat of adsorption was correlated with surface coverage and heterogeneous nature of the Zn-GAC.     

Polyimides containing s‐triazine rings

A series of new polyimides containing s‐triazine rings have been synthesized via Diels–Alder intermolecular polymerization of 2,6‐bis(2‐furanylmethylimino)‐4‐isopropoxy‐1,3,5‐triazine with various bis(maleimide)s. All the poly(imino‐s‐triazine imide)s were characterized by elemental analyses, FTIR spectral studies, number average molecular weight ( M _n) by non‐aqueous conductometric titration and thermogravimetry. Glass‐fibre reinforced composites were prepared via an in situ Diels–Alder intermolecular reaction between 2,6‐bis(2‐furanylmethylimino)‐4‐isopropoxy‐1,3,5‐triazine and various bis(maleimide)s. The composites were characterized for chemical resistivity and mechanical properties. © 2003 Society of Chemical Industry