Fundamental Investigation Of The Electrocatalytic Activity Of Layered Mixed Metal Oxides For Low Temperature Oxygen Electrocatalysis

Li–O2 (Li–air) batteries are among the most promising energy storage technologies due to their high theoretical specific capacity and energy density. Key challenges with this technology include high overpotential losses associated with catalyzing the electrochemical reactions (i.e., oxygen reduction and evolution reactions) at the cathode of the battery. One way to address this challenge is to incorporate an active electrocatalyst, such as first-order Ruddlesden-Popper series of layered oxides. We show that the composition of the A-site in first-order Ruddlesden-Popper series of layered oxides (A2BO4) has a significant effect in the electrochemical activity of Li-O2 cathodes. Among the oxides composed of lanthanides (La, Pr, Nd) that form stable structures, La2NiO4 exhibits the best electrochemical performance when incorporated in Li-O2 cathodes. Furthermore, we find that the electrochemical performance of La2NiO4 could be further improved by doping the La site with an alkaline earth metal, such as Ba. We show that Ba0.25La1.75NiO4 exhibits the best discharge capacity and lowest OER potential when compared to undoped La2NiO4, Sr0.25La1.75NiO4 and Ca0.25La1.75NiO4. Stability of these oxide electrocatalysts is demonstrated under electrochemical conditions. We anticipate that these findings will further enhance the driving force for utilizing first-order Ruddlesden-Popper series of layered oxides as efficient non-precious metal-based cathode electrocatalysts for high-energy storage systems. In the second portion of this study, we report through the example of La2NiO4+δ that layered nickelate oxide materials with rod-shaped nanostructure exhibit promising electrochemical performance as cathode electrocatalysts for Li–O2 batteries. We demonstrate the ability to control the nanostructure of La2NiO4+δ electrocatalyst at the nanoscale level using a reverse-microemulsion synthesis approach. We show that Li–O2 batteries with cathodes containing rod-shaped La2NiO4+δ electrocatalyst exhibit lower charging potentials and higher reversible capacities when compared to batteries with carbon-only cathodes. Our studies indicate that the enhancement in the battery performance induced by the rod-shaped La2NiO4+δ electrocatalyst can be attributed to the fact that La2NiO4+δ nanorods (i) facilitate the formation of nanosized Li2O2 particles during discharge, and (ii) promote the electrocatalytic activity toward the oxygen evolution reaction during charging. These findings open up avenues for the utilization of (i) reverse-microemulsion method for controlling the nanostructure of layered oxide materials, and (ii) nanorod-structured nickelate oxides as efficient cathode electrocatalysts for Li–O2 batteries. In the third part of this thesis, we explore the potential of the aforementioned electrocatalysts as promising, non-precious metal based electrocatalysts for ORR in alkaline media. We systematically study the effect of the transition metal site composition using well-defined nanostructures of these oxides terminated by (001) surface facets. Using rotating ring disk electrode voltammetry studies, we show that doping the Ni site with Mn (La2Ni0.875Mn0.125O4+δ) leads to the best ORR activity among all the oxide compositions considered. Detailed kinetic analyses demonstrate that nanostructured Mn-doped LNO also exhibits the highest selectivity toward the desired, direct 4e- pathway for ORR. Furthermore, stability tests via cyclic voltammetry scans, show that Mn-LNO is stable over the course of cycling with minimal change in activity induced by degradation of the carbon support

Quantitative metrics for mutation testing

Program mutation is the process of generating versions of a base program by applying elementary syntactic modifications; this technique has been used in program testing in a variety of applications, most notably to assess the quality of a test data set. A good test set will discover the difference between the original program and mutant except if the mutant is semantically equivalent to the original program, despite being syntactically distinct. Equivalent mutants are a major nuisance in the practice of mutation testing, because they introduce a significant amount of bias and uncertainty in the analysis of test results; indeed, mutants are useful only to the extent that they define distinct functions from the base program. Yet, despite several decades of research, the identification of equivalent mutants remains a tedious, inefficient, ineffective and error prone process. The approach that is adopted in this dissertation is to turn away from the goal of identifying individual mutants which are semantically equivalent to the base program, in favor of an approach that merely focuses on estimating their number. To this effect, the following question is considered: what makes a base program P prone to produce equivalent mutants? The position taken in this work is that what makes a program prone to generate equivalent mutants is the same property that makes a program fault tolerant, since fault tolerance is by definition the ability to maintain correct behavior despite the presence and sensitization of faults; whether these faults stem from poor design or from mutation operators does not matter. Hence if we could only quantify the redundancy of a program, we should be able to use the redundancy metrics to estimate the ratio of equivalent mutants (REM for short) of a program. Using redundancy metrics that were previously defined to reflect the state redundancy of a program, its functional redundancy, its non injectivity and its non-determinacy, this dissertation makes the following contributions: The design and implementation of a Java compiler, using compiler generation technology, to analyze Java code and compute its redundancy metrics. An empirical study on standard mutation testing benchmarks to analyze the statistical relationships between the REM of a program and its redundancy metrics. The derivation of regression models to estimate the REM of a program from its compiler generated redundancy metrics, for a variety of mutation policies. The use of the REM to address a number of mutation related issues, including: estimating the level of redundancy between non-equivalent mutants; redefining the mutation score of a test data set to take into account the possibility that mutants may be semantically equivalent to each other; using the REM to derive a minimal set of mutants without having to analyze all the pairs of mutants for equivalence. The main conclusions of this work are the following: The REM plays a very important role in the mutation analysis of a program, as it gives many useful insights into the properties of its mutants. All the attributes that can be computed from the REM of a program are very sensitive to the exact value of the REM; Hence the REM must be estimated with great precision. Consequently, the focus of future research is to revisit the Java compiler and enhance the precision of its estimation of redundancy metrics, and to revisit the regression models accordingly

The Effect of Political Advertising on Perceived Bias and Credibility of Online News Stories

This study was an investigation of the effect of political advertising on readers’ perceived bias and credibility of an online news article based on participants’ political leanings. Media priming and the hostile media effect were the theoretical underpinnings. Participants were asked to read an unbiased news article placed alongside 3 advertisements. Participants were put into 1 of 3 conditions — right-leaning advertisements, left-leaning advertisements, or neutral advertisements. They then answered questions about the perceived bias and credibility of the article and their own political affiliation. The researchers hypothesized that left-leaning individuals would perceive the article with right-leaning advertisements as biased and less credible and the opposite would be true of right-leaning individuals. Results were not consistent with hypotheses but trended in the expected directions

THE ANALYSIS OF URBAN CONCENTRATION AND DECENTRALIZATION IN EGYPT: CASE STUDY OF PORT SAID GOVERNORATE.

The structural spatial imbalances in Egypt have received considerable attention in recent years. Discussions have been characterized by both a focus towards the importance of the exploitation of the competitive advantages of regions and the reduction of socio-economic disparities by directing development towards backward regions. Those two opinions are drawing attention towards the need for an in-depth analysis of concentration and decentralization policies and their impacts on the land use distribution. This paper analyzes the urban growth scenarios in Port Said governorate within a framework of a decentralized concentration approach for the allocation of economic activities. The purpose of this approach is to support the preparation of a spatial and socio-economic plan that could assist in closing the gap between the rural/urban inequalities and socioeconomic disparities. The analysis of urban growth in Port Said area reveals that there is a strong need to create new employment centers along new transportation corridors to create polycentric regions, each functioning as an integrated socio-economic system that is formally independent from the others, yet connected and concentrated. Meanwhile, rural development has to be promoted as independent functional units that form an agropolitan system. It is concluded that the combination of urban polycentrism and rural concentrated decentralization could present a solution to the unmanaged urban growth on arable land, rural to urban migration and the low quality of life at the urban fringes of the main urban centers

Stability of Linear Multiple‎ Different Order Caputo Fractional System ‎‏

In this paper, we introduce a new equivalent system to the higher order Caputo fractional system ‎‎(CFS) . This equivalent system has multiple order Caputo fractional derivatives ‎‎(CFDs). These CFDs are lying between zero and one.‎ As well ‎as, we find the fundamental solution for linear CFS with multiple order CFDs. Also, we introduce new criteria of studying the stability (asymptotic stability) of the ‎linear CFS with multiple order CFDs. These criteria can be applied in three cases: ‎the first, all CFDs is lying between zero and one. The second, all CFDs are lying ‎between one and two. Finally, some of CFDs are lying between zero and one, ‎and the rest of these derivatives are lying between one and two. The criteria are ‎depending on the position of eigenvalues of the matrix system in the complex plane. ‎These criteria are considered as a generalized of the classical criteria which is ‎used to study the stability of linear first ODEs. Also, these criteria are considered ‎as generalized of the criteria which used to study the stability same order CFS in ‎case when all CFDs lying between zero and one, also in case when all CFDs lying ‎between one and two. Several examples are given to show the behavior of the ‎solution near the equilibrium point.‎ Keywords: Caputo fractional derivatives; Linear Caputo fractional system ‎; Fundamental solution Stability analysis

Gas Sensors Based on Conducting Polymers

Since the discovery of conducting polymers (CPs), their unique properties and tailor-made structures on-demand have shown in the last decade a renaissance and have been widely used in fields of chemistry and materials science. The chemical and thermal stability of CPs under ambient conditions greatly enhances their utilizations as active sensitive layers deposited either by in situ chemical or by electrochemical methodologies over electrodes and electrode arrays for fabricating gas sensor devices, to respond and/or detect particular toxic gases, volatile organic compounds (VOCs), and ions trapping at ambient temperature for environmental remediation and industrial quality control of production. Due to the extent of the literature on CPs, this chapter, after a concise introduction about the development of methods and techniques in fabricating CP nanomaterials, is focused exclusively on the recent advancements in gas sensor devices employing CPs and their nanocomposites. The key issues on nanostructured CPs in the development of state-of-the-art miniaturized sensor devices are carefully discussed. A perspective on next-generation sensor technology from a material point of view is demonstrated, as well. This chapter is expected to be comprehensive and useful to the chemical community interested in CPs-based gas sensor applications

An Exact Solution for a Single Machine Scheduling Under Uncertainty

Here we have n jobs on one machine where the processing times are triangular fuzzy numbers. The jobs are available to process without interruption. The purpose is to find a best sequence of the jobs that minimizes total fuzzy completion times and maximum fuzzy tardiness. In this paper a new definition is presented called D-strongly positive fuzzy number, then an exact solution of the problem through this definition is found. This definition opens new ideas about converting scheduling problems into fuzzy cases

Synthesis of New Pyrazoline - Phenoxathiin Derivatives

Phenoxathiin was prepared by the reaction of diphenyl ether with sulfur in the presence of anhydrous aluminum chloride. This work comprised the synthesis of new phenoxathiin derivatives containing heterocyclic moieties. These heterocyclic compounds were synthesized in three groups. The first group was made up of 2-(oxoalken-1-yl) phenoxathiin derivatives (3a-3j) obtained from the reaction of 2-acetylphenoxathiin with different aromatic aldehyde in the presence of sodium hydroxide. The other two groups involved compounds produced from the reaction of (3a-3j) with hydrazine hydrate in acetic acid to get 2-(1-acetyl pyrazolin-3-yl) phenoxathiin derivatives (4a-4j), and phenyl hydrazine in the presence of piperidine to afford 2-(1-phenyl pyrazolin-3-yl) phenoxathiin derivatives (5a-5j). All these compounds of two groups above were substituted in position (5) in pyrazoline ring with different aryl groups according to aromatic aldehyde used in the preparation of the first group series compounds

Negative Ion Drift and Diffusion in a TPC near 1 Bar

Drift velocity and longitudinal diffusion measurements are reported for a Negative Ion TPC (NITPC) operating with Helium + carbon disulfide gas mixtures at total pressures from 160 to 700 torr. Longitudinal diffusion at the thermal-limit was observed for drift fields up to at least 700 V/cm in all gas mixtures tested. The results are of particular interest in connection with mechanical simplification of Dark Matter searches such as DRIFT, and for high energy physics experiments in which a low-Z, low density, gaseous tracking detector with no appreciable Lorentz drift is needed for operation in very high magnetic fields.Comment: 7 pages, 3 figure

Primary Cutaneous B-Cell Lymphomas

Primary cutaneous B-cell lymphomas (PCBCL) are a heterogeneous group of mature B-cells neoplasms that present in the skin without evidence of nodal or systemic involvement. The clinical and pathologic features of PCBCL differ significantly from the equivalent nodal lymphomas. Three main subtypes of PCBCL are recognized by the 2016 revised WHO classification. Studies have shown that PCBCLs are characterized by distinct immunophenotypic features, chromosomal aberrations and gene rearrangements which provide further support for their classification as separate entities from their nodal types