Three Square

The social issue that Three Square addresses is food insecurity. Food insecurity occurs when people aren\u27t able to secure enough food for a healthy diet and active lifestyle, at some point during the year.https://digitalscholarship.unlv.edu/educ_sys_202/1083/thumbnail.jp

Degradation aspects of water formation and transport in Proton Exchange Membrane Fuel Cell: A review

This review paper summarises the key aspects of Proton Exchange Membrane Fuel Cell (PEMFC) degradation that are associated with water formation, retention, accumulation, and transport mechanisms within the cell. Issues related to loss of active surface area of the catalyst, ionomer dissolution, membrane swelling, ice formation, corrosion, and contamination are also addressed and discussed. The impact of each of these water mechanisms on cell performance and durability was found to be different and to vary according to the design of the cell and its operating conditions. For example, the presence of liquid water within Membrane Electrode Assembly (MEA), as a result of water accumulation, can be detrimental if the operating temperature of the cell drops to sub-freezing. The volume expansion of liquid water due to ice formation can damage the morphology of different parts of the cell and may shorten its life-time. This can be more serious, for example, during the water transport mechanism where migration of Pt particles from the catalyst may take place after detachment from the carbon support. Furthermore, the effect of transport mechanism could be augmented if humid reactant gases containing impurities poison the membrane, leading to the same outcome as water retention or accumulation. Overall, the impact of water mechanisms can be classified as aging or catastrophic. Aging has a long-term impact over the duration of the PEMFC life-time whereas in the catastrophic mechanism the impact is immediate. The conversion of cell residual water into ice at sub-freezing temperatures by the water retention/ accumulation mechanism and the access of poisoning contaminants through the water transport mechanism are considered to fall into the catastrophic category. The effect of water mechanisms on PEMFC degradation can be reduced or even eliminated by (a) using advanced materials for improving the electrical, chemical and mechanical stability of the cell components against deterioration, and (b) implementing effective strategies for water management in the cell

Synthesis, studies and fuel cell performance of “core–shell” electrocatalysts for oxygen reduction reaction based on a PtNix carbon nitride “shell” and a pyrolyzed polyketone nanoball “core”

This report describes a new class of "core-shell" electrocatalysts for oxygen reduction reaction (ORR) processes for application in Proton Exchange Membrane Fuel Cells (PEMFCs). The electrocatalysts are obtained by supporting a "shell" consisting of PtNix alloy nanoparticles embedded into a carbon nitride matrix (indicated as PtNix-CN) on a "core" of pyrolyzed polyketone nanoballs, labeled 'STp'. ST(p)s are obtained by the sulfonation and pyrolysis of a precursor consisting of XC-72R carbon nanoparticles wrapped by polyketone (PK) fibers. The ST(p)s are extensively characterized in terms of the chemical composition, thermal stability, degree of graphitization and morphology. The "core-shell" ORR electrocatalysts are prepared by the pyrolysis of precursors obtained impregnating the STp "cores" with a zeolitic inorganic-organic polymer electrolyte (Z-IOPE) plastic material. The electrochemical performance of the electrocatalysts in the ORR is tested "in situ" by single fuel cell tests. The interplay between the chemical composition, the degree of graphitization of both PtNix-CN "shell" and STpS "cores", the morphology of the electrocatalysts and the fuel cell performance is elucidated. The most crucial preparation parameters for the optimization of the various features affecting the fuel cell performance of this promising class of ORR electrocatalysts are identified

A szegénység újratermelődik

régi képzésSzociális munka szak levelezőB

Roma tanulók beilleszkedési nehézségei

A dolgozat a roma gyerekek nevelésével, oktatásával, beilleszkedési nehézségeivel kapcsolatos problémák hátterét vizsgálja. Fő témája az iskolai szegregáció illetve integráció. Az elméleti részében a szakirodalom feldolgozása bemutatja a romák foglalkoztatási esélyének és iskolai végzettségének összefüggéseit, a roma gyerekek iskolai sikertelenségének okait, valamint rámutat néhány sikeresen alkalmazott, modell értékű oktatási programra. A kirekesztés különböző formáit érintve, kiemelten foglalkozik az iskolai szegregáció és integráció kérdésével. A dolgozat második részében az empirikus kutatás eredményeit ismertetem. Az oktatás az elmúlt években a modern társadalom egyik legfontosabb alrendszerévé vált. Szerepe ma már nem csak a kultúra, a tudás és az értékek átadásában nyilvánul meg, hanem fontos szerepet játszik a gazdaság fejlődésében és a társadalmi integráció megteremtésében is. Kiderült, hogy a szegregált oktatás nem járható út, az integrált oktatás gyakorlati megvalósulásáig viszont hosszú és nehéz utat kell még megtenni, mely során a modern pedagógia eredményeit adaptálni kell a közoktatásban. Hogy ez megvalósuljon, változtatni kell a rendszeren és változni kell a pedagógusoknak is. A társadalom számára a roma népesség aluliskolázottsága súlyos problémákat hordoz. A cigány lakosság társadalmi integrációjához vezető egyik legfontosabb út az iskoláztatás. Az oktatás azonban csak széles körű társadalmi összefogással hozhat eredményeket.BscSzociális munk

Evaluation of Factors Addressed by NFPA 101, Life Safety Code, that Impact Travel Time in Reaching an Exit

Egress factors addressed by NFPA 101, Life Safety Code, were investigated to determine which has the greatest impact on occupant travel time in reaching an exit on a floor. Literature searches, application of NFPA 101, observations of occupant movement, calculation techniques and Pathfinder, a computer-based egress simulation program, were implemented. Factors were evaluated for various building configurations within the maximum allowable NFPA 101 limits. Egress factors were quantified and ranked, and recommendations on factors not articulated in NFPA were addressed