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Magnetic properties of pulsed laser deposited Co1-xZnxFe2O4 (0.10 <= x <= 0.70) thin films
No full textThe magnetic properties of pulsed laser deposited Co-Zn ferrite [Co1-xZnxFe2O4 (0.1 <= x <= 0.7)] nanocry-stalline thin films have been investigated. The films were deposited on amorphous quartz substrate. The observed magnetic properties of the films depend on the deposition temperature (T-S), the annealing temperature (T-A) and the Zn content (x). A magnetization value higher than bulk was observed in a room temperature deposited Co rich (x = 0.1) Co-Zn ferrite thin films, when the films were ex-situ annealed at T-A = 750 degrees C. On the other hand, in Zn rich (x = 0.7) Co-Zn ferrite, a magnetization value higher than bulk (x = 0.7) was obtained in a film deposited at T-S = 750 degrees C. The unusual magnetization values are explained on the basis of grain growth and the cation distribution in thin films. (C) 2017 Elsevier B.V. All rights reserved
Study of GO-Cu2O and RGO-Cu nanocomposite monolayer sheets prepared by modified Langmuir Blodgett route
No full textThe modified Langmuir-Blodgett (MLB) technique has been improvised and extended to transfer GO-Cu2O nanocomposite monolayer sheets, by introducing Cu2+ ions into the subphase at room temperature. Morphological studies of as-transferred sheets revealed the presence of closely spaced GO monolayer sheets, with slightly enhanced roughness. XPS studies of as-transferred sheets confirmed the presence of copper, either as metallic Cu or Cu2O, along with significant Cu(OH)(2) component, but TEM results confirmed the formation of Cu2O nanocrystallites of size (7 +/- 2) nm, distributed uniformly over GO sheets. After heat treatment in vacuum at 400 degrees C, the nanocomposite sheets were covered with a uniform distribution of larger size nanoparticles. Based on Raman, XPS and TEM studies it has been confirmed that heat treatment at 400 degrees C in vacuum results in the formation of agglomerated Cu nanoparticles of size (23 +/- 9) nm distributed uniformly over reduced graphene oxide (RGO) sheets. The electrical characterization of nanocomposite sheets on SiO2/Si in back-gated FET geometry revealed that the electrical conductivity of as-transferred GO-Cu2O sheets was similar to that usually observed for GO monolayer sheets. The RGO-Cu sheets also displayed electrical conductivity and field effect mobility values comparable to those reported for RGO sheets obtained by chemical/thermal reduction, and was unaffected by the presence of Cu nanoparticles
Nature and extent of solution aggregation determines the performance of P(NDI2OD-T2) thin-film transistors
No full textSynthesis and properties of BF2- & PO2-complexes of mono meso-heterocycle substituted 25-oxasmaragdyrins and derivatives
No full textBF2- and PO2-smaragdyrins containing one five membered heterocycle such as pyrrole, thiophene and furan at one of the meso-position of corresponding 25-oxasmaragdyrins were synthesized by treating the appropriate mono meso-heterocycle substituted 25-oxasmaragdyrin with BF3.OEt2 and POCl3 respectively in CH2Cl2 under mild reaction conditions. All macrocycles were thoroughly characterized by HR-MS and 1D and 2D NMR spectroscopy. The presence of a five membered heterocycle in place of a six membered aryl group significantly alters the electronic properties of the smaragdyrin macrocycle as reflected in their spectral and electrochemical properties. The meso-pyrrole BF2-smaragdyrin was subjected to a Vilsmeier-Haack reaction to prepare meso-(alpha-formyl pyrrolyl) BF2-smaragdyrin which was subsequently used to prepare meso-(alpha-dipyrromethanyl pyrrolyl) BF2-smaragdyrin. The further use of meso-heterocycle substituted BF2- and PO2-oxasmaragdyrins was demonstrated by treating meso-pyrroly1 BF2-smaragdyrin with pentafluorobenzaldehyde in CHCl3 under mild acid catalysed conditions to afford an unusual dipyrromethanyl bridged BF2-smaragdyrin dyad which exhibits excellent photo physical properties. (C) 2017 Elsevier Ltd. All rights reserved
Effects of concurrent strain induced martensite formation on tensile and texture properties of 304L stainless steel of varying grain size distribution
No full textUltrafine grained austenitic stainless steel, with two different types of grain size distributions, was studied for tensile deformation behavior. Tensile deformed specimens were analyzed by electron backscatter diffraction using scanning electron microscope. It was found from this study that uni-modal grained stainless steel (SS) having a larger fraction of submicron grains exhibited early fracture, which is attributed to the development of extensive strain localization. On the other hand, the microstructure of SS having bimodal grain size distribution showed a good combination of strength and ductility. EBSD analysis of the deformed region of these two samples revealed the presence of a distinct transition zone between undeformed or less deformed and extensively sheared regions. Multiple micro shear bands were found to be associated with the transition zone of unimodal type microstructure. The micro shear bands seen in the transition zone of unimodal SS led to the development of strain-induced martensite (SIM), which, in turn, is helpful in delaying the strain localization. However, in bimodal grained SS, the larger fraction of micron size grains undergoes a shape change, with a rotation towards [112] orientation, which results in the formation of a larger fraction of SIM having [112] orientation. The propensity for development of high SIM was found to prevent strain localization in bimodal grained SS
Thermoelastic analysis of laminated and functionally graded sandwich cylindrical shells with two refined higher order models
No full textAnalytical solutions for laminated and functionally graded sandwich open cylindrical shells under mechanical and thermal loads are presented using a refined higher order shear and normal deformation theory. Temperature variation through thickness is assumed as thickness coordinate polynomial. Present study also extends the classical thickness criteria with more reliable extension to moderately thick shells. Navier solution method is used to solve system of equations derived using principle of minimum potential energy for all edges diaphragm supported. Two kinds of sandwich panels with core or face sheets made of thickness graded material are studied. Several examples are numerically evaluated to establish the accuracy of present models
Intensification of emulsion liquid membrane extraction of uranium(VI) by replacing nitric acid with sodium nitrate solution
No full textUse of emulsion liquid membrane (ELM) extraction of uranium(VI) from lean streams containing nitric acid using tri-n-butyl phosphate (TBP) suffers from major drawback that TBP transports nitric acid to the strip phase, thereby reducing the driving force for extraction. This problem is completely eliminated by using near neutral sodium nitrate solution as the feed. The membrane phase is light liquid paraffin, containing TBP and the strip phase is aqueous sodium carbonate. Emulsion is stabilized using polymeric surfactant system, which exhibits low rate of leakage of the strip phase and no noticeable swelling of the emulsion. The key step is pH control of the continuous phase between 4.0 and 4.5 in order to neutralize sodium carbonate leaking from the emulsion phase. Effect of concentration of NaNO3 in the feed phase, Na2CO3 in the strip phase and volume ratio of the feed to the strip phase, on the rate of extraction of uranium(VI) and its enrichment, is studied. Using this process, it is possible to achieve nearly quantitative extraction of uranium(VI) with enrichment factor greater than 60. The superiority of the present process is established by comparing its performance with ELM extraction of uranium (VI) from nitric acid
High contrast mechanochromic and thermochromic luminescence switching by a deep red emitting organic crystal
No full textIn this study, we report a deep red emissive organic crystal that displays high contrast fluorescence switching under mechanical and thermal stimulation. Upon mechanical grinding, the pristine red emissive crystals of 1R ((em) = 667 nm) transformed into green emissive crystalline powder ((em) = 550 nm) with a remarkable hypsochromic shift of wavelength, = 117 nm. The melting of 1R leads to a green emissive amorphous solid ((em) = 555 nm) with a wavelength shift of = 112 nm. Upon fuming with different solvents, the amorphous melt solid transforms into different polymorphs having distinct emission characters. The structural relationship between different emissive states is investigated with the aid of X-ray diffraction and other spectroscopic studies, which clearly demonstrate the roles of ordered molecular packing and intermolecular interaction in determining their diverse optical response
Modules with pure resolutions
No full textLet R a standard graded algebra over a field k. In this paper, we give a relation in terms of graded Betti numbers, called the Herzog-Kuhl equations, for a pure R-module M to satisfy the condition dim(R)-depth(R)=dim(M)-depth(M). When R is Cohen-Macaulay, we prove an analogous result characterizing all graded Cohen-Macaulay R-modules of finite projective dimension. Finally, as an application, we show that the property of R being Cohen-Macaulay is characterized by the existence of pure Cohen-Macaulay R-modules corresponding to any degree sequence of length at most depth(R)
An approach for reliability prediction of instrumentation & control cables by artificial neural networks and Weibull theory for probabilistic safety assessment of NPPs
No full textThe polymeric materials used for insulation and sheath in instrumentation and control (I&C) cables of nuclear power plants (NPPs) are subjected to degradation due to various stressors. The prediction of long-term aging and lifetime of cables is generally determined based on accelerated life testing (ALT) experiments which are not only expensive but also time consuming. Application of artificial neural networks (ANNs) in the field of transient diagnosis and condition assessment of electrical and other equipment has been a promising technique; however the use of ANN for reliability prediction of I&C cables has not yet been studied. This paper presents an integrated approach to predict the lifetime and reliability of I&C cables by ANN from the accelerated aging data. In order to validate the proposed methodology for use in probabilistic safety assessment (PSA) of NPP to account for the cable failures, ALT data on a typical cross-linked polyethylene (XLPE) insulated I&C cable has been referred from the literature. The time dependent reliability was predicted by considering the various failure rates. Study demonstrates that by an appropriate training algorithm with suitable network architecture, it is possible to predict the reliability of I&C cables by ANN with the minimal accelerated life testing. (C) 2017 Elsevier Ltd. All rights reserved