Further steps to school readiness : 2009 evaluation of the South Carolina First Steps to School Readiness initiatives

This is the third evaluation of the First Steps initiative. This 2009 evaluation focuses on the following specific areas of the First Steps experience: four year-old kindergarten, parenting and family literacy programs, child care quality enhancement and scholarships, and the school transition program Countdown to Kindergarten

Stability and performance of in-situ formed phosphosilicate nanoparticles in phosphoric acid-doped polybenzimidazole composite membrane fuel cells at elevated temperatures

One of the effective strategies to pursue the highly durable high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) is to introduce inorganic fillers to the phosphoric acid-doped polybenzimidazole (PA/PBI) membranes. Among the inorganic fillers, phosphates such as phosphosilicate are effective in mitigating acid loss at elevated temperatures (200–300 °C). In this paper, the effect of in situ formed phosphosilicate on the performance and stability of SiO2/PA/PBI composite membranes is studied in detail. The mechanical properties and electrochemical performances of the in situ formed SiO2/PA/PBI membranes depend strongly on the content of in situ formed Si5P6O25 fillers and its distribution and microstructure in the membrane. Such in situ formed SiO2/PA/PBI composite membranes show a high conductivity of 53.5 mS cm−1 at 220 °C. The assembled single cell shows a maximum peak power density (PPD) of 530.6 mW cm−2 and excellent stability at elevated temperature of 220 °C for over 130 h. The exceptional stability at 220 °C is most likely due to the existence of predominant amorphous phosphosilicate phases in the in situ formed SiO2/PA/PBI composite membranes, which inhibits the evaporation and leaching of PA at elevated temperatures. The results indicate the practical application of in situ formed SiO2/PA/PBI composite membranes for HT-PEMFCs

Development of In Situ Formed Metal Pyrophosphates (MP2O7, Where M = Sn, Ti, and Zr)/PA/PBI Based Composite Membranes for Fuel Cells

Development of high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) at elevated temperatures is important for the enhancement of tolerance toward CO impurities and for the development of non-precious metal catalysts. The key challenge in such HT-PEMFCs is the high temperature polymer electrolyte membranes. Herein, the development of in situ formed metal pyrophosphates (MP2O7, where M = Sn, Ti, and Zr) in phosphoric acid doped polybenzimidazole (PA/PBI) composite membranes for HT-PEMFCs is reported. The formation mechanism of MP2O7, and characteristics of MP2O7/PA/PBI composite membranes are studied in detail. In contrast to the rapid decay in performance of pristine PA/PBI membrane cells, the in situ formed MP2O7/PA/PBI composite membranes show significantly higher proton conductivity, improved performance, and stability at elevated temperatures of 200–250 °C. The best results are obtained on the in situ formed SnP2O7/PA/PBI composite membrane cells, exhibiting a high peak power density of 476 mW cm−2 and proton conductivity of 51.3 mS cm−1 at 250 °C. The excellent durability of SnP2O7/PA/PBI composite membrane is due to the uniform distribution of in situ formed SnP2O7 nanoparticles in PBI membranes and the formation of a gel-like region, thin and irregular amorphous layer on the SnP2O7 with the high acid retention ability. This effectively alleviates the PA leaching at elevated temperatures of the new HT-PEMFCs

O Processo Educacional em uma Escola Pública de Barranquilla, Colômbia, na Modalidade de Alternância Escolar: Conectando aulas entre China y Colombia en tiempos de pandemia

Technology provides new learning environments in which 21st-century skills such as collaboration are involved, and English becomes the language of communication and interaction among participants. During the lockdown caused by the COVID-19 pandemic, students faced the shift from face-to-face to online classes, which made students feel demotivated and lost opportunities to use English in meaningful environments. This article reports a qualitative research process to explore students’ perceptions of an Online Collaborative Learning (OCL) project focused on story writing between China and Colombia. Accordingly, surveys and interviews were implemented to gather datafrom the 51 students and 12 English teachers that participated in the study. The 51 students were divided into six groups, and each group was assigned two coordinators: one from China and one from Colombia. This article contributes to knowledge in OCL and cross-cultural communication since it describes students’ strengths and difficulties when interacting with others whose first language is not English. Specifically, it is concluded that speakers of English as a foreign language deal withchallenges and strengths related to time zone differences, English language proficiency, intrinsic motivation,and attitudes. It is also mentioned that teamwork skills, empathetic language, and the ability to use technology mediate the collaborative writing process.La tecnología proporciona nuevos entornos de aprendizaje en los que intervienen habilidades del siglo XXI como la colaboración, y el inglés se convierte en el idioma de comunicación e interacción entre los participantes. Durante el cierre provocado por la pandemia Covid-19, los estudiantes se enfrentaron al cambio de clases presenciales a clases en línea, lo que hizo que los estudiantes se sintieran desmotivados y perdieran oportunidades de utilizar el inglés en entornos significativos. Este artículo reporta un proceso de investigación cualitativa para explorar las percepciones de los estudiantes sobre un proyecto de Aprendizaje Colaborativo en Línea (OCL, por sus siglas en inglés) enfocado en la escritura de cuentos entre China y Colombia. Para ello, se aplicaron encuestas y entrevistas para recopilar datos de los 51 estudiantes y 12 docentes en formación que participaron en el estudio. Los 51 estudiantes se dividieron en seis grupos, y a cada grupo se le asignaron dos coordinadores: uno de China y otro de Colombia. Este artículo contribuye al conocimiento en Oc l y comunicación intercultural ya que describe las fortalezas y dificultades de los estudiantes cuando interactúan con otros cuya primera lengua no es el inglés. En concreto, se concluye que los hablantes de inglés como lengua extranjera se enfrentan a retos y fortalezas relacionados con las diferencias horarias, el dominio de la lengua inglesa, la motivación intrínseca y las actitudes. También se menciona que las habilidades de trabajo en equipo, el lenguaje empático y la capacidad de utilizar la tecnología median en el proceso de escritura colaborativa.O objetivo deste artigo de pesquisa é apresentar algumas características do processo educacional em uma escola pública de Barranquilla na modalidade de alternância escolar com base no depoimento de professores e alunos. Para realizar esta pesquisa, foram utilizados paradigma interpretativo sob abordagem qualitativa, método da teoria fundamentada, utilizando como técnica a entrevista em profundidade por meio do instrumento de coleta de dados, e roteiro de entrevista com perguntas abertas. Os resultados mostram que as matrículas aumentaram nas instituições educacionais públicas, os horários e o conteúdo programático foram redefinidos, enquanto a execução de obras de infraestrutura pelas autoridades educacionais locais é lenta e ineficiente. As conclusões revelam, por um lado, que os estabelecimentos de ensino fizeram um grande esforço para se adaptar às mudanças exigidas por essa nova realidade, embora, por outro, as administrações locais devam realizar obras nas escolas com rapidez, levando em conta que os alunos logo terão de frequentar a escola presencialmente

Zeolitic imidazolate framework-derived ordered Pt–Fe intermetallic electrocatalysts for high-performance Zn-air batteries

Aiming to explore novel oxygen reduction reaction (ORR) catalysts with advanced electrochemical performance and economical and long-term stability is crucial to fuel cells or metal-air batteries. Herein, ordered Pt–Fe intermetallic with an ultralow Pt loading is facilely achieved via the thermal treatment of Pt nanocrystals anchored to the Fe, N-codoped surface-functioned carbon derived from zeolitic imidazolate frameworks. Benefiting from the ordered Pt–Fe intermetallic formed by the rationally applied calcination treatment, the optimized catalyst shows a larger mass activity and better long-term durability compared with Pt/C. Besides, when the optimized sample is applied in the configuration of a zinc-air battery system, it has a higher maximum power density, a better specific capacity as well as a longer discharge time, surpassing those of the Pt/C catalyst

A bilateral cyano molecule serving as an effective additive enables high-efficiency and stable perovskite solar cells

The existence of defects in perovskite films is a major obstacle that prevents perovskite solar cells (PSCs) from high efficiency and long-term stability. A variety of additives have been introduced into perovskite films for reducing the number of defects. Lewis base-based additive engineering has been considered as an effective way to eliminate defects, especially the defects caused by the uncoordinated Pb2+. In this work, for the first time, a bilateral cyano molecule (succinonitrile, SN) which is a commonly used plasticizer in solid electrolyte of solid-state lithium batteries was selected as an additive to modify organic–inorganic hybrid perovskite films in PSCs. SN is featured with two cyano groups (–C≡N) distributing at both terminals of the carbon chain, providing two cross-linking points to interact with perovskites crystals via coordinating with uncoordinated Pb2+ and forming hydrogen bonds with –NH2 groups in perovskite. It was found that the addition of SN into perovskite precursor solution could effectively reduce defects, particularly inhabit the appearance of Pb0 and thus suppress trap-assisted nonradiative charge carrier recombination. As a result, the efficiency of CH3NH3PbI3(Cl) (MAPbI3(Cl))-based PSCs was improved from 18.4% to 20.3% with enhanced long-term stability at N2 and humid air atmosphere. This work provides a facile and effective strategy to enhance the PCE and stability of PSCs simultaneously, facilitating the commercialization of PSCs

Recent Advances in Nanostructured Inorganic Hole-Transporting Materials for Perovskite Solar Cells

Organic-inorganic halide perovskite solar cells (PSCs) have received particular attention in the last decade because of the high-power conversion efficiencies (PCEs), facile fabrication route and low cost. However, one of the most crucial obstacles to hindering the commercialization of PSCs is the instability issue, which is mainly caused by the inferior quality of the perovskite films and the poor tolerance of organic hole-transporting layer (HTL) against heat and moisture. Inorganic HTL materials are regarded as promising alternatives to replace organic counterparts for stable PSCs due to the high chemical stability, wide band gap, high light transmittance and low cost. In particular, nanostructure construction is reported to be an effective strategy to boost the hole transfer capability of inorganic HTLs and then enhance the PCEs of PSCs. Herein, the recent advances in the design and fabrication of nanostructured inorganic materials as HTLs for PSCs are reviewed by highlighting the superiority of nanostructured inorganic HTLs over organic counterparts in terms of moisture and heat tolerance, hole transfer capability and light transmittance. Furthermore, several strategies to boost the performance of inorganic HTLs are proposed, including fabrication route design, functional/selectively doping, morphology control, nanocomposite construction, etc. Finally, the challenges and future research directions about nanostructured inorganic HTL-based PSCs are provided and discussed. This review presents helpful guidelines for the design and fabrication of high-efficiency and durable inorganic HTL-based PSCs

Aluminum Cation Doping in Ruddlesden-Popper Sr2TiO4 Enables High-Performance Photocatalytic Hydrogen Evolution

Hydrogen (H2) is regarded as a promising and renewable energy carrier to achieve a sustainable future. Among the various H2 production routes, photocatalytic water splitting has received particular interest; it strongly relies on the optical and structural properties of photocatalysts such as their sunlight absorption capabilities, carrier transport properties, and amount of oxygen vacancy. Perovskite oxides have been widely investigated as photocatalysts for photocatalytic water splitting to produce H2 because of their distinct optical properties, tunable band gaps and excellent compositional/structural flexibility. Herein, an aluminum cation (Al3+) doping strategy is developed to enhance the photocatalytic performance of Ruddlesden-Popper (RP) Sr2TiO4 perovskite oxides for photocatalytic H2 production. After optimizing the Al3+ substitution concentration, Sr2Ti0.9Al0.1O4 exhibits a superior H2 evolution rate of 331 μmol h−1 g−1, which is ~3 times better than that of Sr2TiO4 under full-range light illumination, due to its enhanced light harvesting capabilities, facilitated charge transfer, and tailored band structure. This work presents a simple and useful Al3+ cation doping strategy to boost the photocatalytic performance of RP-phase perovskites for solar water splitting

Aluminum Cation Doping in Ruddlesden-Popper Sr₂TiO₄ Enables High-Performance Photocatalytic Hydrogen Evolution

Hydrogen (H2) is regarded as a promising and renewable energy carrier to achieve a sustainable future. Among the various H2 production routes, photocatalytic water splitting has received particular interest; it strongly relies on the optical and structural properties of photocatalysts such as their sunlight absorption capabilities, carrier transport properties, and amount of oxygen vacancy. Perovskite oxides have been widely investigated as photocatalysts for photocatalytic water splitting to produce H2 because of their distinct optical properties, tunable band gaps and excellent compositional/structural flexibility. Herein, an aluminum cation (Al3+) doping strategy is developed to enhance the photocatalytic performance of Ruddlesden-Popper (RP) Sr2TiO4 perovskite oxides for photocatalytic H2 production. After optimizing the Al3+ substitution concentration, Sr2Ti0.9Al0.1O4 exhibits a superior H2 evolution rate of 331 μmol h−1 g−1, which is ~3 times better than that of Sr2TiO4 under full-range light illumination, due to its enhanced light harvesting capabilities, facilitated charge transfer, and tailored band structure. This work presents a simple and useful Al3+ cation doping strategy to boost the photocatalytic performance of RP-phase perovskites for solar water splitting