Novel anhydrous composite membranes based on sulfonated poly (ether ketone) and aprotic ionic liquids for high temperature polymer electrolyte membranes for fuel cell applications

Novel composite membranes were prepared using imidazolium type aprotic ionic liquids and sulfonated poly (ether ketone) (SPEK) as polymer matrix by solution casting process. All the prepared membranes were characterized for their thermal stability, mechanical properties, ion exchange capacity, proton conductivity and leaching out of ionic liquids in presence of water. Ionic liquid based membranes were more flexible than neat SPEK membrane due to the plasticization effect of ionic liquids. The interactions and compatibility occurring among components were investigated by vibration spectroscopy (FTIR ATR) and scanning electron microscopy respectively. The thermal stability of composite membranes was higher than unmodified membranes. The ion conductivity of composite membranes under anhydrous conditions was found to be dependent on temperature, type and concentration of ionic liquid in SPEK matrix. Ion conductivities of composite membranes under anhydrous condition were found to be up to two orders (∼100 times) higher than neat SPEK membrane and it was found to be ∼5 mS/cm at 140 °C for SPEK/OTf-70. These composite membranes can be successfully operated at temperatures ranging from 40 °C to 140 °C under anhydrous conditions.     

Novel surface modified polymer–lipid hybrid nanoparticles as intranasal carriers for ropinirole hydrochloride: in vitro, ex vivo and in vivo pharmacodynamic evaluation

Here we report fabrication and evaluation of novel surface modified polymer–lipid hybrid nanoparticles (PLN) as robust carriers for intranasal delivery of ropinirole hydrochloride (ROPI HCl). Sustained release, avoidance of hepatic first pass metabolism, and improved therapeutic efficacy are the major objectives of this experiment. PLN were fabricated by emulsification-solvent diffusion technique and evaluated for physicochemical parameters, in vitro mucoadhesion, in vitro diffusion, ex vivo permeation, mucosal toxicity and stability studies. Box-Behnken experimental design approach has been employed to assess the influence of two independent variables, viz. surfactant (Pluronic F-68) and charge modifier (stearylamine) concentration on particle size, ζ-potential and entrapment efficiency of prepared PLN. Numerical optimization techniques were used for selecting optimized formulation sample, further confirmed by three dimensional response surface plots and regression equations. Results of ANOVA demonstrated the significance of suggested models. DSC and SEM analysis revealed the encapsulation of amorphous form of drug into PLN system, and spherical shape. PLN formulation had shown good retention with no severe signs of damage on integrity of nasal mucosa. Release pattern of drug-loaded sample was best fitted to zero order kinetic model with non-Fickian super case II diffusion mechanism. In vivo pharmacodynamic studies were executed to compare therapeutic efficacy of prepared nasal PLN formulation against marketed oral formulation of same drug. In summary, the PLN could be potentially used as safe and stable carrier for intranasal delivery of ROPI HCl, especially in treatment of Parkinson’s disease.     

Low complexity adaptation for SISO channel shortening equalizers

Since the days of Digital Subscriber Links (DSL), time domain equalizers (TEQ's) have been used to combat time dispersive channels in Multicarrier Systems. In this paper, we propose computationally inexpensive techniques to recompute TEQ weights in the presence of changes in the channel, especially over fast fading channels. The techniques use no extra information except the perturbation to the channel itself, and provide excellent approximations to the new TEQ weights. Adaptation methods for two existing Channel shortening algorithms are proposed and their performance over randomly varying, randomly perturbed channels is studied. The proposed adaptation techniques are shown to perform admirably well for small changes in channels for OFDM systems.     

New ternary Yb5Sb3-type R5T1−x{Sb,Bi}2+x phases (R = Y,Dy, Ho,T = Co,Ru, Rh,Pd) and their magnetic properties

Several novel R₅T_1?x{Sb,Bi}_2+x phases having the Yb₅Sb₃-type structure (space group Pnma) have been synthesized. The cell parameters are: a = 1.20668(9), b = 0.88396(7), c = 0.78745(7) nm for Y₅CoSb₂; a = 1.19939(7), b = 0.88364(5), c = 0.78283(5) nm for Dy₅CoSb₂; a = 1.19633(8), b = 0.89231(6), c = 0.78450(6) nm for Ho₅RhSb₂; a = 1.18650(6), b = 0.90455(4), c = 0.79260(4) nm for Ho₅PdSb₂; a = 1.2215(3), b = 0.8948(2), c = 0.7977(2) nm for Y₅CoBi₂; a = 1.1781(8), b = 0.9071(7), c = 0.7936(6) nm for Tm₅Co_0.5Bi_2.5; a = 1.1972(1), b = 0.92096(9), c = 0.80048(9) nm for Ho₅RuBi₂; a = 1.2082(1), b = 0.90346(9), c = 0.79413(8) nm for Ho₅RhBi₂ and a = 1.20374(5), b = 0.91076(4), c = 0.80135(4) nm for Ho₅PdBi₂, respectively. Magnetization measurements indicate ferromagnetic transitions for Dy₅CoBi₂, Ho₅RhSb₂, Ho₅RhBi₂, Ho₅PdSb₂ and Ho₅PdBi₂ at T_C = 34, 38, 28, 42 and 38 K, respectively. The Ho₅RhSb₂ and Ho₅PdBi₂ compounds show additional magnetic transitions at about 18 K, probably associated with a spin reorientation. The magnetocaloric effect of Dy₅CoBi₂ in terms of the isothermal entropy change, ΔS_m, is ?6.2 J/(kg/K) at 38 K and in terms of the adiabatic temperature change, ΔT_ad, is 2.2 K for a 5 T field change.     

A Novel Highly Sensitive Humidity Sensor Based on ZnO/SBA‐15 Hybrid Nanocomposite

This work deals with the study of hydrothermally synthesized zinc oxide (ZnO) loaded mesoporous SBA‐15 hybrid nanocomposite for relative humidity sensing (RH) at room temperature. The sensor exhibits an excellent ~5 orders impedance change along with excellent linearity, quick response time (17 s), rapid recovery time (18 s), negligible hysteresis (1.2%), good repeatability, and stability (1.8%) in 11%–98% RH range. In addition, complex impedance spectra of the sensor at different RHs were analyzed to understand the humidity sensing mechanism. Our study can open a new way for realizing ZnO/SBA‐15 hybrid nanocomposite for fabrication of high‐performance RH sensors.     

Private sector participation in infrastructure projects: a methodology to analyse viability of BOT

Many developing countries are now attempting to finance new infrastructure projects through private sector participation. This paper outlines a methodology based on financial and risk analyses that a government or a government utility can use to analyse the viability of private sector participation in new infrastructure projects. The water supply projects in Sri Lanka are used for the case study to outline the methodology. Financial analyses of a bulk water supply project and a water distribution project are carried out to estimate subsidy percentages that are required to make the projects viable, using a model developed for the investment analysis of all types of infrastructure project. This analysis looks at four pricing options for the bulk supply project, and sixteen procurement options for the distribution project, from the view point of the utility, for three cases of non-revenue water (35% as base case, 50% and 25% as extreme cases). The risk analysis takes into account the risk and uncertainty in non-revenue water, cost and demand estimates, rate of debt and forecasts of escalation. These analyses show that the best option for the utility is to obtain both bulk supply and distribution projects through private sector participation using BOT arrangements.     

Total project cost: a simplified model for decision makers

A simplified model for total project cost is developed in this paper to meet the numerous requests from decision makers for a model that can be used to estimate the total project cost from the estimated cash flows and, more importantly, to check the accuracy of the project cost estimates in feasibility studies that require prudent decisions. It begins with a base cost estimate in constant dollars and discrete cash flows with discrete inflation rates as practised by the construction industry. The discrete inflation rates are used to estimate the current dollar costs of the project. The effects of inflation are estimated as escalation during construction. Using the future value concept, interest during construction is estimated, in a simplified approach, to estimate the total project cost. Data from an actual feasibility study is used to highlight the strengths and weaknesses of the simplified model. The model is extended to treat discrete cash flows with continuous inflation rates.     

Elicitation of subjective probabilities for economic risk analysis: An investigation

This paper investigates three major issues regarding the elicitation of expert knowledge for economic risk analysis: (1) recognition of some of the implicit assumptions and beliefs; (2) development of an approach to elicit expert knowledge as accurate, calibrated and coherent subjective probabilities; and (3)a study to explore human ability to predict future events and the validity of the implicit assumptions and beliefs in the context of the expert judgements. The proposed elicitation approach combines the theoretical requirements for valid subjective probabilities with a practical process. The recognition that some of the implicit assumptions and beliefs in engineering risk analysis should be explored when dealing with the human ability to predict future events, and the inherent difficulties in developing experiments and methods to test such beliefs arc some of the benefits of the study. Directions for future work are suggested.     

Fabrication of protective-coated SiC reinforced tungsten matrix composites with reduced reaction phases by spark plasma sintering

SiC reinforced tungsten matrix composites were fabricated via the spark plasma sintering process. In order to prevent an interfacial reaction between the SiC and tungsten during sintering, TiOx coated SiC particles were synthesized by a solution-based process. TiOx layer coated SiC particles were treated in high temperature nitriding conditions or annealed in a high temperature vacuum to form TiN or TiC coated SiC particles, respectively. The TiC layers coated on SiC particles successfully prevented tungsten from reacting with SiC; hence the proposed process resulted in successful fabrication of the SiC/W composites. The mechanical properties such as compressive strength and flexural strength of the composites were measured. Additionally, the effect of SiC on the high temperature oxidative ablation of tungsten was also investigated. The addition of SiC resulted in an improved oxidative ablation resistance of the tungsten-based composites.