Pure exciplex electroluminescence in blended film of small organic molecules

3,6-diarylcarbazole derivatives, 3,6-di-(p-cyanophenyl)-N-hexylcarbazole (CNHC) and 3,6-di-(p-acetylphenyl)-N-hexylcarbazole (ANHC) were synthesized, characterized and energy levels determined. Steady state fluorescence of these molecules showed blue emission in thin films. Blends of these molecules with N,N′-diphenyl-N,N′-(bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (TPD) showed exciplex emission as the dominant one. Single layer organic light emitting devices (OLEDs) of CNHC, ANHC and their blends with TPD were fabricated using ITO as anode and Ca as cathode. The blend film devices showed pure exciplex electroluminescence.     

Structural,electrical and electrochemical behaviours of LiNi0·4 M 0·1Mn1·5O4 (M = Al,Bi) as cathode material for Li-ion batteries

In order to improve the cycling performance of LiMn₂O₄ based cathode materials, we have synthesized a new composition, LiNi_0·4 M _0·1Mn_1·5O₄ (M = Al, Bi), by the sol–gel method. The formation of solid solutions is confirmed by structural characterization using TG/DTA, XRD, FT–IR, EPR, SEM and EPR. A.c.-impedance (Nyquist plot) showed a high frequency semicircle and a sloping line in the low-frequency region. The semicircle is ascribed to the Li-ion migration through the interface from the surface layer of the particles to the electrolyte. Cyclic voltammogram (between 3·5 and 4·9 V) for these materials using CR2032 coin-type cell shows two pairs of redox peaks corresponding to two-step reversible intercalation process, wherein Li-ions occupy two different tetragonal 8a sites in spinel Li _x Mn₂O₄ (x < 1) lattice. The galvanostatic charge/discharge curves for M = Al (77 mAh g^–1) showed reasonably good capacity retention than that of M = Bi (11 mAh g^–1) at the end of 17th cycle.     

Determining the Mechanism of In-Service Cylinder Distortion in Aluminum Engine Blocks with Cast-In Gray Iron Liners

In recent years, stringent government legislation on vehicle fuel efficiency has pushed the automotive industry to replace steel and cast iron power train components with light weight Al alloys. However, unlike their ferrous-based equivalents, Al-Si alloy engine blocks are prone to permanent dimensional distortion in critical locations such as the cylinder bore regions. Understanding the mechanisms that cause distortion will promote the use of Al alloys over ferrous alloys for power train applications and enable automotive manufacturers to meet emission standards and reduce fuel consumption. In this study, neutron diffraction was used to evaluate residual stress along the Al cylinder bridge and the gray cast iron liners of distorted and undistorted engine blocks. Microstructural analysis was carried out using OM, SEM, and TEM, while mechanical testing was accomplished via ambient and elevated temperature [~453 K (180 °C)] tensile testing. The results suggest that the distorted engine block had high tensile residual stress in the Al cylinder bridge, reaching a maximum of 170 MPa in the hoop direction, which triggered permanent dimensional distortion in the cylinders when exposed to service conditions. In addition, the middle of the cylinder had the highest magnitude of distortion since this region had a combination of high tensile residual stress (hoop stress of 150 MPa) and reduced strength compared with the bottom of the cylinder.     

FINITE ELEMENT STUDY ON THE ROLE OF CONVECTION IN LASER SURFACE MELTING

The surface-tension-driven convection in laser melting has been simulated by the Galerkin finite element method. The governing laminar, axisymmelric convection equations are solved in a sequential manner by an explicit projection method. The numerical results show a strong dependence of the flow pattern on the value of the temperature coefficient of surface tension (σ_T). Results are presented for a range of σ_T values typical in steel, -l0^?4≤σ_T + l0^?4N/mK. As the melt depth is more affected than the width, the melt aspect ratio changes due to convection. The melt pool is broad and shallow when σ_T < 0, and deep and narrow when σ_T > 0.     

Particles in High-Pressure Cylinder Gases

An improved test protocol is presented for the measurement of particle concentrations in high-pressure cylinder gases. With the screening method, particles entrained in a cylinder gas can be collected and chemically analyzed for the isolation of particle sources. Results are presented for argon, helium, and nitrogen cylinder gases. Many fine particles are formed from the trace organic vapors present in the cylinder gas by gas-to-particle conversion occurring downstream of such pressure-reducing devices as an orifice plate. It is demonstrated that these fine particles in the cylinder gas can be significantly reduced by as much as three orders of magnitude by the insertion of an appropriate purifying stage before the pressure-reducing devices.     

NITROGEN REAGENTS IN METAL ION SEPARATION. PART VIII SUBSTITUTED IMIDAZOLES AS EXTRACTANTS FOR Cu3+

ABSTRACT

A number of derivatives of imidazole have been synthesized. Their extraction behaviour towards Cu²⁺ in dilute acid medium have been investigated in both chloride and perchlorate media. The influence of electronic and stereochemical effects are discussed. Two-phase potentiometric titrations were employed to determine the two-phase protonation constants and Cu(II) complex species present in the organic phases. The N-decylimidazole derivative has a higher extraction efficiency than the other C-ring substituted imidazoles in spite of their greater protonation constants.     

An adaptable steady state Aspen Hysys model for the methane fuelled solid oxide fuel cell

An adaptable model for the methane fed internal reforming SOFC using the in built features of Aspen Hysys is presented in this paper. The model includes the electrochemistry, the diffusion phenomena and the reforming kinetics in detail. Three potential methods for representing the SOFC are investigated out of which the recycled reforming model is found to be capable of providing reasonable results over a wide range of operating conditions. The electrochemical model that gives good agreement with experimental data is also identified. From the simulations, it is concluded that the developed model is reasonably accurate over a wide operating range and can be used for steady state analysis. The computational challenges in the modelling are discussed. The model will be used for system level optimisation studies of the SOFC system especially in conjuncture with gas turbines and steam turbines.     

Solving subclasses of multi-player stochastic games via linear complementarity problem formulations—a survey and some new results

We briefly survey some results on the orderfield property of 2-player and multi-player stochastic games and their mixtures. Some of these classes of stochastic games can be solved by formulating them as a Linear Complementarity Problem (LCP) or (Generalized) Vertical Linear Complementarity Problem (VLCP). We discuss some of these results and prove that certain new subclasses and mixtures of multi-player (or n-person) stochastic games can be solved via LCP formulations. Mohan, Neogy and Parthasarathy (in Proceedings of the International Conference on Complementarity Problems, 1997) proposed an LCP formulation of ??-discounted (multi-player) polystochastic games where the transitions are controlled by one player, and proved that this LCP is processible by Lemke??s algorithm. Using this formulation repeatedly, we prove that we can solve a subclass of ??-discounted switching control polystochastic games. As our proof is constructive, we have an algorithm for solving this subclass. This algorithm only involves iteratively solving different LCPs and hence, it follows that this subclass has the orderfield property, a?question left open in the paper on orderfield property of mixtures of stochastic games by Krishnamurthy et al., (Indian J. Stat. 72:246?C275, 2010). Furthermore, we use results from Krishnamurthy et al., Indian J. Stat. 72:246?C275, (2010) to solve some mixture classes using LCP (or VLCP) formulations. We also propose two different VLCP formulations for ??-discounted zero-sum perfect information stochastic games, the underlying matrices of both formulations being R ₀. As a result, we also have an alternative proof of the orderfield property of such games.     

Single-step growth dynamics of core–shell GaN on Ga<Subscript>2</Subscript>O<Subscript>3</Subscript> freestanding nanoprotruded microbelts

Freestanding wurtzite GaN nanoprotruded microbelts with Ga₂O₃ core, with typical thickness 1–10 μm, and length of few millimeters are synthesized by thermal annealing of Ga metal and subsequent reaction with ammonia at a low flow rate. They are of distinctive rectangular shape with a typical width of 10–100 μm. Thickness of the belt is about 1/10th of the width and length up to a few millimeters. The GaN, Ga₂O₃ layers and the GaN–Ga₂O₃ interface are characterized by high-resolution transmission electron microscopy after focused ion beam sectioning of the belt. Initially, Ga₂O₃ nucleates after reaction with the O₂ available in the environment, and subsequent reaction with NH₃ results in the formation of core–shell structure in the catalyst-free vapor–solid growth process. Having a low-symmetry phase, Ga₂O₃ can grow only in certain preferred directions thus controlling the final morphology of the belt. Nanoscale protrusions ~50–100 nm found on the surface of the belts could be an ideal system for building functional devices.