Anode Fabrication for Solid Oxide Fuel Cells: Electroless and Electrodeposition of Nickel and Silver into Doped Ceria Scaffolds

© 2016 The Authors.A novel fabrication method using electroless and electrodeposited Ni/Ag/GDC for SOFC anodes is presented. First a porous Ce0.9Gd0.1O2-x (GDC) scaffold was deposited on a YSZ electrolyte by screen printing and sintering. The scaffold was then metallized with silver using Tollens reaction, followed by electrodeposition of nickel from a Watts bath. The electrodes (Ni/Ag/GDC) were tested in both symmetrical and fuel cell configurations. The microstructures of the Ni/Ag/GDC anodes were analyzed using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX). Nano-particles of Ni formed in the porous GDC scaffold provided triple phase boundaries (TPB). The electronic conductivity of the Ni/Ag/GDC (3.5/24.7/71.8 vol%) electrode was good even at relatively low Ni volume fractions. The electrochemical performance was examined in different concentrations of humidified hydrogen (3% H2O) and over a range of temperatures (600-750 °C). The total area specific resistance (ASR) of the anode at 750 °C in humidified 97 vol% H2 was 1.12 Ω cm2, with low-frequency polarization (R-l) as the largest contributor. The electrodes were successfully integrated into a fuel cell and operated in both H2 and syngas

Multi G -cyclic Operators are G-cyclic

Paris proved in 2001 Herrero's conjectured "that every multi-hypercyclic (multi- supercyclic) operator on a Hilbert space is in fact hypercyclic (supercyclic)  In this paper we study this conjectured in many cases of operators between hypercyclic operators and supercyclic operators. And we proved that multi G-cyclic operator is G-cyclic operator

Development and testing of an assessment tool for integrated learning

Objective: Development of integrated questions for undergraduate medical students and assessing students’ capability to retain and apply basic concepts in an integrated way. Method: Multiple choice questions, attempting to probe understanding and application of different concepts, affiliated with different subjects and topics, were developed. As a pilot these were administered to the students of third year and final year at the end of their certifying examinations as a mock test. The following year these questions were introduced in the continuous assessments and subsequently the certifying examinations (in third year) as 33% of the whole examination. Difficult indices, item analysis and internal consistency (alpha) were calculated for all the questions. Results: The difficulty indices of integrated questions indicated that students found the integrated questions difficult. Conclusion: There was a significant change of distribution in terms of scoring for the integrated questions. Students’ power to integrate showed reliable improvement when tested in the certifying examinations (JPMA 51:384,2001)

Generalized Holographic Dark Energy Model

In this paper, the model of holographic Chaplygin gas has been extended to two general cases: first is the case of modified variable Chaplygin gas and secondly of the viscous generalized Chaplygin gas. The dynamics of the model are expressed by the use of scalar fields and the scalar potentials.Comment: 12 pages, to appear in Eur. Phys. J.

Constraints on coupling constant between dark energy and dark matter

We have investigated constraints on the coupling between dark matter and the interacting Chaplygin gas. Our results indicate that the coupling constant $c$ between these two entities can take arbitrary values, which can be either positive or negative, thus giving arbitrary freedom to the inter-conversion between Chaplygin gas and dark matter. Thus our results indicate that the restriction $0<c<1$ on the coupling constant occurs as a very special case. Our analysis also supports the existence of phantom energy under certain conditions on the coupling constant.Comment: 16 Pages, 3 figure

Teleparallel Killing Vectors of the Einstein Universe

In this short paper we establish the definition of the Lie derivative of a second rank tensor in the context of teleparallel theory of gravity and also extend it for a general tensor of rank $p+q$. This definition is then used to find Killing vectors of the Einstein universe. It turns out that Killing vectors of the Einstein universe in the teleparallel theory are the same as in General Relativity.Comment: 9 pages, accepted for publication in Mod. Phys. Lett.

Reducing Inequity in Urban Health: Have the Intra-urban Differentials in Reproductive Health Service Utilization and Child Nutritional Outcome Narrowed in Bangladesh?

Bangladesh is undergoing a rapid urbanization process. About one-third of the population of major cities in the country live in slums, which are areas that exhibit pronounced concentrations of factors that negatively affect health and nutrition. People living in slums face greater challenge to improve their health than other parts of the country, which fuels the growing intra-urban health inequities. Two rounds of the Bangladesh Urban Health Survey (UHS), conducted in 2013 and 2006, were designed to examine the reproductive health status and service utilization between slum and non-slum residents. We applied an adaptation of the difference-indifferences (DID) model to pooled data from the 2006 and 2013 UHS rounds to examine changes over time in intra-urban differences between slums and non-slums in key health outcomes and service utilization and to identify the factors associated with the reduction in intraurban gaps. In terms of change in intra-urban differentials during 2006–2013, DID regression analysis estimated that the gap between slums and non-slums for skilled birth attendant (SBA) during delivery significantly decreased. DID regression analysis also estimated that the gap between slums and non-slums for use of modern contraceptives among currently married women also narrowed significantly, and the gap reversed in favor of slums. However, the DID estimates indicate a small but not statistically significant reduction in the gap between slums and non-slums for child nutritional status. Results from extended DID regression model indicate that availability of community health workers in urban areas appears to have played a significant role in reducing the gap in SBA. The urban population in Bangladesh is expected to grow rapidly in the coming decades. Wide disparities between urban slums and non-slums can potentially push country performance off track during the post-2015 era, unless the specific health needs of the expanding slum communities are addressed. To our knowledge, this is the first systematic explanation and quantification of the role of various factors for improving intra-urban health equity in Bangladesh using nationally representative data. The findings provide a strong rationale for continuing and expanding community-based reproductive health services in urban areas by the NGOs with a focus on slum populations

Ions Traces Substitution in Stoichiometric Calcium-Hydroxyapatite: Structural Analysis by Rietveld Refinement

Impact of trace ions as Mg2+, Na+, Sr2+, SO42-, and CO32- on stoichiometric hydroxyapatite (Ca10(PO4)6(OH)2) crystal structure is investigated. The first four ions are brought by the raw material while the carbonate group is due to contamination by air. The powders were prepared, under industrial conditions, at 22°C from aqueous solutions by reaction between the calcium hydroxide and orthophosphoric acid at pH from 7 to 7.5. Two samples of hydroxyapatite powder, which differ by the content of ions trace, calcined at 1100°C have been investigated by X-ray powder patterns fitting methods. Results showed that in the absence of ion traces, the partial replacement of PO43- by CO32- groups leads to the - relaxation of the lattice by creation of vacant calcium (Ca1 and Ca2) sites, - reduction of the cell parameters, and new lattice rearrangement with lower PO4 distortion index, (Dind = 0.488) compared to the calculated theoretical value (Dind=3.079). For trace ions incorporated hydroxyapatite sample, the presence of traces cation favors the incorporation of carbonate ions. Coupled substitution on Ca2 and P position affect neither theoretical structure nor thermal stability of the hydroxyapatite but causes vacancies creation in calcium (Ca1) and oxygen (O1 and O3) sites. This structural change leads to a slight lattice distortion (Dind=3.204). Composition and microstructure of analyzed materials appear very promising for biological applications. Keywords: Biomaterials, Calcium-hydroxyapatite, Traces ions, Crystalline structure