Thermal stability and high-temperature wear of Ti–TiN and TiN–CrN nanomultilayer coatings under self-mated conditions

Ti–TiN and TiN–CrN nanomultilayers were thermally stable retaining uniform and sharp layer interfaces up to 24 h at 773 K, without any oxidation or phase transformation accompanying each individual layer. Decreasing the multilayer spacing resulted in an increase in the hardness in both cases. The coating hardness was found to be independent of the substrate type, when applied on HS718, Ti64 and HCHCr substrates. In scratch testing, the multilayers displayed a better resistance to the onset of failure, as compared to the monolayer TiN. The substrate plasticity played an important role in determining the coating failure mode. Self-mated wear tests revealed the CrN–TiN system to exhibit the best wear behaviour, both at room temperature and at 773 K. The Ti–TiN coatings are more accommodative with all three substrates, as compared to TiN–CrN and TiN.     

Eu（Ⅲ） Indirect Probe to Investigate Interaction of DOPA （3, 4, Di-Hydroxyphenylalanine） and Dopamine （3, 4-Dihydroxy Phenyl Ethyl Amine） Using Electrochemical Methods

Eu（ Ⅲ ） can be utilized as an indirect electrochemical probe to investigate the interaction of bio-molecules such as DOPA and Dopamine with Ca（ Ⅱ ） in vitro. The interaction of DOPA and Dopamine with Eu（ Ⅲ ）-Eu（ Ⅱ ） redox pair was investigated by electrochemical techniques. Both the neurotransmitters are structurally related and undergo interaction with Eu （Ⅲ ）. Eu （ Ⅲ ） coordinates with DOPA and Dopamine through five-member chelate tings via carboxylic oxygen and amino nitrogen. The electrode kinetic parameters viz, transfer coefficient （αna）, diffusion coefficient （D）, forward heterogeneous rate constant （ k^0 fh） were evaluated for Eu（ Ⅲ ）-DOPA/Eu（ Ⅲ ）-Dopamine. The results obtained were used to investigate the nature of interaction of Eu （Ⅲ） with muhi-donor biomolecules. The possible mechanism was also proposed.     

Samarium Ion-Doped Maghemite Nanoparticles: Synthesis,Microstructural, Optical,and Magnetic Characterizations

Journal of Superconductivity and Novel Magnetism - This paper reports the effects of rare-earth Sm3+ ion substitution on structural, optical, electronic, and magnetic responses of maghemite...     

Nonlinear thermoelastic frequency analysis of functionally graded CNT-reinforced single/doubly curved shallow shell panels by FEM

In this article, the nonlinear vibration frequencies of functionally graded carbon nanotube-reinforced composite doubly curved shell panels under elevated thermal environment are numerically investigated using finite element method. The doubly curved carbon nanotube-reinforced shell panel has been modeled mathematically using higher-order kinematics theory and Green–Lagrange geometrical nonlinear strains. The properties of the individual constituents of the graded composite are assumed to be temperature dependent. In addition, the properties of the media are obtained based on the modified rule of mixture. The carbon nanotubes are dispersed nonuniformly through the thickness direction. The large deformation kinematic effects on the structural responses are counted by including all the nonlinear higher-order terms in the formulation. The desired nonlinear responses are computed numerically using our in-house computer code in conjunction with the direct iterative scheme. The convergence and the accuracy of the present numerical model have been checked by solving various numerical examples. Nonlinear mechanical responses were affected by several other design parameters and explored numerically for the thickness ratios, volume fractions, temperature loading, type of geometries, and type of grading under the uniform thermal environment.     

Synthesis and characterization of aniline-doped mixed copolymer resins. II

Copolymer resins were synthesized by the mixed condensation of resorcinol–CH₂O, resorcinol–aniline–CH₂O, resorcinol–aniline–thiourea–CH₂O, and resorcinol–aniline–urea–thiourea–CH₂O with a view to develop synthetic resins having improved properties and performance like toughness, mechanical properties, thermal resistance, chemical inertness, and adhesion. The resins were characterized by IR and TG analyses. The thermal analysis showed that the mixed copolymer resins have significantly better thermal stability than that of the simple phenol–CH₂O, aniline–CH₂O, urea–CH₂O, and thiourea–CH₂O resins. At 600°C, only a 50% weight loss is observed, and even at 800°C, the weight loss is about 70%. The resins are insoluble in most of the organic solvents including DMSO-d₆. They too are unaffected by diluted HNO₃, but dissolve in concentrated HNO₃. © 1996 John Wiley & Sons, Inc.     

Vibroacoustic analysis of thermo-elastic laminated composite sandwich curved panel: a higher-order FEM–BEM approach

International Journal of Mechanics and Materials in Design - The present paper deals with the vibration induced acoustic responses of baffled sandwich curved shell panels constituted of laminated...     

Integrated MAED–MARKAL-based analysis of future energy scenarios of Nepal

This paper employs an integrated model for analysis of energy demand and MARKet ALlocation modelling framework for assessing different pathways for the development of energy systems of Nepal. Four energy scenarios are analysed with the time horizon from 2010 to 2030. With high electrification and energy efficiency and demand-side management, the analysis reveals that all three major goals of sustainable energy for all can be achieved by 2030, but that the total discounted systems costs required account for three times the costs of the reference scenario. In the policy scenario, net fuel import costs and greenhouse gas emissions will decline by 20% and 35%, respectively and the share of renewable energy will increase from 3% in 2010 to 22% in 2030. The analysis provides insights for selecting a better pathway for the sustainable energy development and energy security of the country.     

Experimental and detailed kinetic model for the oxidation of a Gas to Liquid (GtL) jet fuel

The kinetics of oxidation, ignition, and combustion of Gas-to-Liquid (GtL) Fischer–Tropsch Synthetic kerosene as well as of a selected GtL-surrogate were studied. New experimental results were obtained using (i) a jet-stirred reactor – species profiles (10 bar, constant mean residence time of 1 s, temperature range 550–1150 K, equivalence ratios φ = 0.5, 1, and 2), (ii) a shock tube – ignition delay time (≈16 bar, temperature range 650–1400 K, φ = 0.5 and 1), and (iii) a burner – laminar burning velocity (atmospheric pressure, preheating temperature = 473 K, 1.0 ? φ ? 1.5). The concentrations of the reactants, stable intermediates, and final products were measured as a function of temperature in the jet-stirred reactor (JSR) using probe sampling followed by on-line Fourier Transformed Infra-Red spectrometry, and gas chromatography analyses (on-line and off-line). Ignition delay times behind reflected shock waves were determined by measuring time-dependent CH^* emission at 431 nm. Laminar flame speeds were obtained in a bunsen-type burner by applying the cone angle method. Comparison with the corresponding results for Jet A-1 showed comparable combustion properties. The GtL-fuel oxidation was modeled under these conditions using a detailed chemical kinetic reaction mechanism (8217 reactions vs. 2185 species) and a 3-component model fuel mixture composed of n-decane, iso-octane (2,2,4-trimethyl pentane), and n-propylcyclohexane. The model showed good agreement with concentration profiles obtained in a JSR at 10 bar. In the high temperature regime, the model represents well the ignition delay times for the fuel air mixtures investigated; however, the calculated delays are longer than the measurements. It was observed that the ignition behavior of the surrogate fuel is mainly influenced by n-alkanes and not by the addition of iso-alkanes and cyclo-alkanes. The simulated laminar burning velocities were found in excellent agreement with the measurements. No deviation between burning velocity data for the GtL-surrogate and GtL was seen, within the uncertainty range. The presented data on ignition delay times and burning velocities agree with earlier results obtained for petrol-derived jet fuel. The suitability of both the current detailed reaction model and the selected GtL surrogate was demonstrated. Finally, our results support the use of the GtL fuel as an alternative jet fuel.