Frequency dependent electrical transport properties of 4,4′,4″-tris(N-3-methylphenyl-N-phenylamine)triphenylamine by impedance spectroscopy

The frequency dependent ac conduction mechanism in 4,4′,4″-tris(N-3-methylphenyl-N-phenylamine)triphenylamine (m-MTDATA) has been studied as a function of applied bias and temperature. The Cole–Cole plot shows a slightly depressed semicircle indicating Debye type relaxation. This result has been explained by an equivalent circuit of the device designed as a two parallel resistor and capacitance network in series with contact resistance. The ac conduction studies under dc bias for hole only devices shows an increase in device conductivity with the increase in bias. The variation of bulk resistance with applied bias indicates Space Charge Limited Conduction (SCLC) mechanism for hole conduction. The hole mobility of the material has also been evaluated from SCLC as 8.859 × 10^?6 cm²/V s. The temperature dependent impedance studies show two activation energies indicating two different phase of the material with a phase transition at 235 K.     

CONCENTRATION POLARIZATION OCCURRING INSIDE THE MEMBRANE DURING STEADY STATE PERVAPORATION

Experimental profiles of a single penetrant (water) across the membrane have been established at different downstream pressures during steady state pervaporation. The profiles ofacetic acid-water binary penetrant system across the membrane were also measured at different downstream pressures, temperatures and compositions during steady state pervaporation. A stack of identical pre-characterized symmetric aromatic polyamide membranes was used for the profile study. The theoretical prediction of concentration polarization from mathematical equations has been confirmed by the experimental profile data for a binary penetrant system.     

Ammonia volatilization from urea as affected by the addition of iron pyrites and method of application

Laboratory incubations were conducted to determine the ammonia (NH₃) loss from urea as affected by the addition of coarse and ground (fine) pyrites at 1:1, 1:2 and 1:5 urea: pyrite (w/w) ratios and methods of application (surfaceapplication, incorporation and placement). Coarse pyrites (>-2mm) were not effective in reducing NH₃ loss from urea when surface applied even at the highest ratio of pyrite (15.9% vs 18.7% without pyrite). Ground pyrites (0.1–0.25 mm), in 1:1 ratio, had about 5% less NH₃ loss than the urea alone treatment. Higher ratios of pyrites reduced NH₃ loss much more. Ammonia losses were the most with surface-applied urea (18.9%) and the least (13.5%) when placed (2.5 cm) below the soil surface. Addition of ground pyrite to surface-applied urea (1:1 ratio) decreased the loss to 13.2%. Urea+pyrite placed below the soil surface had the least loss (9.8%). Results indicate that combined application of urea and fine pyrite could reduce NH₃ loss.     

Electron transfer reaction and mechanism of oxidation of Inosine

Electrochemical oxidation of Inosine has been studied in the phosphate buffers of pH range 3.3-10.9 at pyrolytic graphite electrode. In the entire pH range a single well-defined oxidation peak (I_a) was observed, when the sweep was initiated in the positive direction. In the reverse sweep no cathodic peak was obtained. The peak potential of the oxidation peak was dependent on pH and shifted to less positive potential with increase in pH. The kinetics of the UV absorbing intermediate was followed spectrophotometrically and the decay occurred in a pseudo first order reaction having k values in the range 0.50-0.92 × 10⁻³ s⁻¹ in the entire pH range studied. The value of n was found to be 2.95 ± 0.3. The products of oxidation were silylated and characterized by using GC-Mass. Two tetramers having CC, CN, NN, CON and COOC linkages were identified. A plausible mechanism for the electrooxidation of Inosine has been suggested.     

Comparison of the generation of oil by the extraction and the hydropyrolysis of biomass

This paper discusses the maximisation of the yields of useful bio-oils generated from seeds and nut-shells both by extraction and by hydropyrolysis. The formation and the composition of the bio-oils are also discussed.Powdered (<0.25 mm diameter) Rapeseed, Linseed and Safflower seed and Hazel nut and Walnut shells, that is, fresh precursors of liptinite, have been characterised by their elemental analyses, infra-red and NMR spectra. Bio-oils obtained both by extraction and by slow hydropyrolysis to 520 °C at moderate pressure in the presence of ammonium dioxydithiomolybdate have been compared by the same analyses and by gas chromatography. Consistent with previous work [Hardy JA. A greener future with biodiesel. Green Chem 2001 G56-G57], extraction of the seeds with organic solvents, including Diesel oil, gave yields of up to 40% together with an uninteresting residue. However, subsequent saponification of the residues gave further yields of oil. Hydropyrolysis removed oxygen from the seeds as water and as oxides of carbon to generate bio-oil in yields of up to 75%. Whereas little oil could be extracted from the nut-shells, hydropyrolysis gave oil yields of ∼40%. Some char was also formed, suggesting that optimisation of the hydropyrolysis might give even larger yields of oil.     

Effect of water of crystallization on synthesis of nanocrystalline ceria by non-hydrolytic method

Nanocrystalline ceria has been synthesized by a non-hydrolytic method using organic solvent and precipitant. The effect of the source compound on final nanocrystalline powder was investigated. The cerium nitrate hexahydrate subjected to different vacuum/thermal treatments to get cerium source compound having different extent of water of crystallization. The nanoceria, synthesized from these compounds was characterized by TGA-MS, XRD, HR-TEM and AFM.     

Wastewater treatment sludge as a raw material for the production of Bacillus thuringiensis based biopesticides

Seven wastewater sludges of different origins and types were used as an alternate culture medium for producing Bacillus thuringiensis variety kurstaki HD-1. The sludge samples were used under three different preparations: without pre-treatment, with acid treatment (hydrolysed sludge) and the supernatant obtained after centrifugation of the hydrolysed sludge. The sludge composition varied widely with origin and the type of sludge. Growth and sporulation were evaluated by the total viable cell count and spore count of the preparations. Growth, sporulation and endotoxin production were affected by the sludge origin. Hydrolysed sludge gave the highest viable cell and spore counts while the liquid phase (supernatant) gave the lowest. Non-hydrolysed primary sludge from Valcartier was unable to sustain bacterial growth because of its low pH. Bioassays were conducted against larvae of spruce budworm to evaluate entomotoxic potential of the preparations obtained. In general, sludge hydrolysis increased the entomotoxicity yields. Similar entomotoxicity was observed in Black Lake secondary sludge (4100 IU/microL) as that obtained in the reference soya medium (3800 IU/microL). The use of the sludge supernatant (liquid phase) was not recommended due to the low entomotoxic potential obtained.     

Emission characteristic of hydrogen and gasoline blend in spark-ignited engine

Hydrogen is an energy carrier that can transform our fossil fuel-dependent economy into a hydrogen economy, which can provide an emission-free transportation fuel. Hydrogen-fuelled engines are known for several advantages, among which is the very low concentration of pollutants in the exhaust gases compared with internal combustion engines using traditional or other alternative fuels. Hydrogen-driven vehicles thus reduce both local and global emissions. It is an energy carrier that can be used in internal combustion engines or fuel cells producing virtually no greenhouse gas emissions when combusted with oxygen. The only significant emission is water vapour. The effect of blending of hydrogen with gasoline is analysed in this current paper. Both HC and NO_x concentration decrease with the increase in hydrogen fractions. The results were analysed by collecting data on different crank angles and at 5%, 10%, 15% and 20% of hydrogen introduction into combustion chamber along with gasoline as base fuel.     

Bulk and lattice thermal expansion in Ce1−xSrxO2−x (0.0≤x≤0.10)

In this communication, we report on the bulk and lattice thermal expansion studies on a number of compounds, within the homogeneity range of solid solutions, in a series with the general composition Ce_1−xSr_xO_2−x (0.0≤x≤0.10). The XRD pattern of each product was refined to determine the solid solubility of SrO into the lattice of CeO₂, and the homogeneity range. The composition with maximum solid solubility limit of SrO in CeO₂ lattice, under the slow cooled conditions, was delineated as Ce_0.91Sr_0.09O_1.91 (i.e. 9 mol.% of SrO). The bulk thermal expansion measurements from ambient to 1123 K, as investigated by a dilatometer, revealed that the _l (293 to 1123 K) values for the compositions within the homogeneity range increase from 11.58×10⁻⁶ to 12.13×10⁻⁶ K⁻¹ on increasing the Sr²⁺ content from 0 mol.% (i.e. CeO₂) to 9 mol.%, i.e. the upper solubility limit of SrO into the lattice of CeO₂. A similar trend was observed in the lattice thermal expansion coefficients _a (293 to 1473 K) as obtained by a high temperature-XRD.     

Spectroscopic studies on DLC/TM (Cr,Ag, Ti,Ni) multilayers

The hydrogen-free diamond-like carbon (DLC) films with transition metal (TM = Cr, Ag, Ti, Ni) interlayer (bilayer and multilayer) were deposited on to stainless steel and silicon substrates using pulsed laser deposition technique. Secondary ion mass spectroscopy (SIMS) confirmed that the films were hydrogen free. Incorporation of chromium inter layer reduced the stress value by about 3 GPa as determined by micro Raman spectroscopy. Incorporation of the TM inter layer enhanced the photoluminescence (PL) intensity as compared to the monolithic DLC films. The optical band gap determined by spectroscopic ellipsometry for DLC/TM films was found to be in the range of 1.56–1.67 eV.