Synthesis, characterization and electrical properties of nanostructured LaAlO3 by sol–gel auto combustion method

Semiconductive nanostructured LaAlO₃ was synthesized by sol–gel auto combustion method using inorganic reagents as La (NO₃)₃·6H₂O, Al (NO₃)₃·9H₂O and glycine as a fuel. Structural characterization of prepared sample was characterized by X-ray diffraction technique (XRD), and Fourier transforms infrared spectroscopy (FTIR). The morphology of the particle was found by scanning electron microscopy while elemental composition by energy dispersive X-ray spectroscopy and transmission electron microscopy (TEM) was used to study the nanostructure of the material. XRD pattern reveals the formation of single phase orthorhombic structure without any other phase formation. The system LaAlO₃ show porous morphology. Particle size obtained from TEM analysis was found to be ~40 nm. The FTIR spectra showed the characteristic of two strong absorption bands at 656 and 442 cm^?1 corresponding to metal–oxygen bond vibrations for the perovskite structure compound. Superhydrophilic nature of LaAlO₃ was investigated at room temperature by sessile drop technique. The electrical properties of the compound showed that LaAlO₃ exhibits conducting behavior.     

Statistical optimization and kinetic study on biodiesel production from a potential non-edible bio-oil of wild radish

The bio-oil extracted from wild radish seeds is non-edible and it still remains an unexplored area in terms of its use as a feedstock for biodiesel. It was extracted from the seeds using mechanical expeller and the oil yield was found to be 46.2?±?2?wt%. The physical and chemical properties of the extracted oil were analyzed as per AOAC official methods. In this current study, biodiesel was derived by catalytic transesterification reaction. The parameters that influence the processes like methanol to oil molar ratio, catalyst concentration, reaction temperature, and reaction time were optimized. Taguchi statistical method and Analysis of Variance (ANOVA) table were used to understand the effects of the influencing parameters and to optimize the biodiesel yield. Further, it was compared with Box-Behnken Design (BBD) using Response Surface Methodology (RSM). It shows that Taguchi method gave similar results of RSM within a limited number of runs. At optimized condition, the yield of biodiesel was 94.58?wt%. Kinetic studies were also performed for transesterification reaction and it was observed that the reaction follows pseudo-first-order kinetics. The reaction rate constants and activation energy were determined. The physical and chemical properties of the biodiesel were analyzed as per ASTM test methods and compared with ASTM D6751 standard.     

Comparative performance of an adiabatic and a nonadiabatic PSA process for bulk gas separation—a numerical simulation

A detailed numerical model of a Skarstrom‐like PSA process is used to investigate the separation performance of an adiabatic and a nonadiabatic process for removal of bulk CO₂ impurity from inert He. The complexity of the gas phase adsorbate composition, adsorbate loading, and the adsorbent temperature profiles as functions of positions inside an adsorber at the start and end of each step of the PSA process are discussed. The separation performance of a nonadiabatic PSA process is generally inferior to that of the corresponding adiabatic process. Smaller adsorbent column diameter accentuates nonadiabatic operation and hence lower separation efficiency. Furthermore, the separation efficiency decreases more rapidly at short cycle times and smaller column diameters. Insulation of PSA columns of a process development unit operated under these conditions is recommended for reliable data analysis. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4066–4078, 2017     

Copper‐Catalyzed Domino Reaction Involving Nitro as an Unexpected Leaving Group: Construction of Dibenzo‐Fused Azepinone Ring

A copper‐catalyzed new domino reaction allowed the facile and direct construction of the dibenzo‐fused azepinone ring leading to an array of novel small molecules. The co‐catalyst, ligand or additive free one‐pot method afforded a unique class of functionalized derivatives, one of which showed encouraging PDE4 inhibition in vitro and apoptosis in vivo.

     

Ionic conductivity and lithium electrode stability in Hydrin: LiBF4 elastomers

Three commercial elastomers, Hydrin C, Hydrin H and Hydrin T, which contain ethylene oxide and epichlorohydrin repeat units, have been investigated as polymer electrolytes in contact with lithium electrode. The influence of polyethylene glycol and fine particles of zeolite on ionic conductivity of Hydrin-LiBF₄ electrolytes and the exchange current density of the lithium electrode reaction has been studied by using impedance spectroscopy and cyclic voltammetry. The specific conductivity of the elastomeric electrolyte is about 10^–5 S cm^–1 at room temperature when polyethylene glycol is present. But the mechanical stability of the film is less. The addition of zeolite particles to the elastomers also improves the specific conductivity. When present in low concentrations, the zeolite particles show catalytic effect on the electrochemical reaction at lithium electrode at ambient temperature. The lithium electrode reaction is reversible and the electrolyte possesses good electrochemical stability.     

Synthesis and Biological Evaluation of (−) and (+)-Spiroleucettadine and Analogues

A second-generation enantiospecific synthesis of spiroleucettadine is described. The original reported antibacterial activity was not observed when the experiment was repeated on the synthetic samples; however, significant anti-proliferative activity was uncovered for both enantiomers of spiroleucettadine. Comparison of the optical rotational data and ORD-CD spectra of both enantiomers and the reported spectrum from the natural source have not provided a definitive answer regarding the absolute stereochemistry of naturally occurring spiroleucettadine. Efforts then focussed on alteration at the C-4 and C-5 positions of the slightly more active (−)-spiroleucettadine. Ten analogues were synthesised, with three analogues found to possess similar anti-proliferative profiles to spiroleucettadine against the H522 lung cancer cell line.     

Novel alkali-promoted hydrotalcite for selective synthesis of 2-methoxy phenyl benzoate from guaiacol and benzoic anhydride

Esters find several applications such as solvents, flavours and fragrants and intermediates in synthesis of drugs. In the present work, 2-methoxy phenyl benzoate was efficiently synthesized from guaiacol and benzoic anhydride by acylation. A variety of catalysts such as hydrotalcite and alkali-promoted hydrotalcite was synthesized. Potassium-promoted hydrotalcite (K/HT) calcined at 500 °C for 6 h was active, selective and reusable. It was characterized by different techniques. A slurry batch reactor was used to study reaction mechanism and kinetics. 2-Methoxy phenyl benzoate was efficiently obtained with 100% selectivity at guaiacol conversion of 98% over K/HT at 100 °C after 6 h. A power law model with second-order kinetics was fitted to obtain an apparent activation energy of reaction of 21.1 kcal mol^?1. The process is clean and green.     

Photoinactivation of bacteria by using Fe-doped TiO<Subscript>2</Subscript>-MWCNTs nanocomposites

In this study, nanocomposites of Fe-doped TiO₂ with multi-walled carbon nanotubes (0.1– 0.5?wt. %) were prepared by using sol–gel method. The structural and morphological analysis were carried out with using X-ray diffraction pattern and transmission electron microscopy, which confirm the presence of pure anatase phase and particle sizes in the range 15–20?nm. X-ray photoelectron spectroscopy was used to determine the surface compositions of the nanocomposites. UV–vis diffuse reflectance spectra confirm redshift in the optical absorption edge of nanocomposites with increasing amount of multi-walled carbon nanotubes. Nanocomposites show photoinactivation against gram-positive Bacillus subtilis as well as gram-negative Pseudomonas aeruginosa. Fe-TiO₂-multi-walled carbon nanotubes (0.5?wt. %) nanocomposites show higher photoinactivation capability as compared with other nanocomposites. The photoluminescence study reveals that the Fe-TiO₂-multi-walled carbon nanotubes nanocomposites are capable to generate higher rate of reactive oxygen species species than that of other nanocomposites. Our experimental results demonstrated that the Fe-TiO₂-multi-walled carbon nanotubes nanocomposites act as efficient antibacterial agents against a wide range of microorganisms to prevent and control the persistence and spreading of bacterial infections.     

Nonequilibrium synthesis of nbai3 and Nb-Ai-V

In this study, the isothermal oxidation behavior of laser-clad NbAl₃ has been investigated in the temperature range between 800 °C and 1400 °C in air. The effect on oxidation of vanadium microalloying, used to increase the ductility of the otherwise brittle NbAl₃ and discussed in Part I, [1] has also been considered. Bulk and surface oxide chemistry has been investigated using X-ray diffraction and X-ray photoelectron spectroscopy (XPS), respectively. Oxidation kinetics have been determined from weight gain data. The XPS and X-ray diffraction data show that NbAl₃ does not exclusively form a protective A1₂O₃ layer when oxidized in air. The oxidation products at 800 °C are a mixture of Nb₂O₅ and A1₂O₃, while at 1200 °C, a mixture of NbAlO₄, Nb₂O₅, and Al₂O₃ is formed. At 1400 °C, a mixture of NbAlO₄, A1₂O₃, NbO₂, NbO_2.432, and Nb₂O₅ forms. Upon addition of vanadium, the oxidation rate is found to dramatically increase and may be related to the formation of (Nb, V)₂O₅ and VO₂, which grows in favor of protective A1₂O₃. Consequently, although vanadium may be a good additive in terms of its potential for improving ductility in NbAl₃, it is not in terms of its deleterious effects on oxidation.     

Estimation of ionic conductivity of CuI through tarnishing studies of copper in iodine atmosphere

The conductivity values of isolated CuI crystal has been reported by a large number of investigators. But the conductivity be-haviour of a growing CuI film on copper has not been explored yet. An attempt has been made in this investigation to provide ionic conductivity values of growing CuI films from the kinetics studies of the film growth process. The conductivity value has been found to be proportional to the square of the partial pressure of iodine in the thinner film range while it is approximately proportional to the square root of the partial pressure in the thicker range. Estimation has been based on the fundamental parabolic equation of Wagner relating the rate constant and conductivity. An analysis of the experimental results indicate that the conductivity value of the growing CuI is of higher magnitude for thicker films than that for the thinner ones.