University of Delaware

About: University of Delaware is a education organization based out in Newark, Delaware, United States. It is known for research contribution in the topics: Population & Catalysis. The organization has 22223 authors who have published 54810 publications receiving 2049136 citations. The organization is also known as: University of Delaware Emergency Care Unit & UD.

How Can We Improve School Discipline

Abstract: School discipline addresses schoolwide, classroom, and individual student needs through broad prevention, targeted intervention, and development of self-discipline. Schools often respond to disruptive students with exclusionary and punitive approaches that have limited value. This article surveys three approaches to improving school discipline practices and student behavior: ecological approaches to classroom management; schoolwide positive behavioral supports; and social and emotional learning. The article examines their epistemological and empirical roots and supporting research, suggesting ways to combine approaches.

Measured Mass‐Loss Rates of Solar‐like Stars as a Function of Age and Activity

Abstract: Collisions between the winds of solar-like stars and the local interstellar medium result in a population of hot hydrogen gas surrounding these stars. Absorption from this hot H i can be detected in high-resolution Lyspectra of these stars from the Hubble Space Telescope. The amount of absorption can be used as a diag- nostic for the stellar mass-loss rate. We present new mass-loss rate measurements derived in this fashion for four stars (� Eri, 61 Cyg A, 36 Oph AB, and 40 Eri A). Combining these measurements with others, we study how mass loss varies with stellar activity. We find that for the solar-like GK dwarfs, the mass loss per unit sur- face area is correlated with X-ray surface flux. Fitting a power law to this relation yields _ M / F 1:15� 0:20 X. The active M dwarf Proxima Cen and the very active RS CVn systemAnd appear to be inconsistent with this relation. Since activity is known to decrease with age, the above power-law relation for solar-like stars sug- gests that mass loss decreases with time. We infer a power-law relation of _ M / t � 2:00� 0:52 . This suggests that the solar wind may have been as much as 1000 times more massive in the distant past, which may have had important ramifications for the history of planetary atmospheres in our solar system, that of Mars in particular. Subject headings: hydrodynamics — stars: winds, outflows — ultraviolet: ISM — ultraviolet: stars

Ag–Sn Bimetallic Catalyst with a Core–Shell Structure for CO2 Reduction

Abstract: Converting greenhouse gas carbon dioxide (CO2) to value-added chemicals is an appealing approach to tackle CO2 emission challenges. The chemical transformation of CO2 requires suitable catalysts that can lower the activation energy barrier, thus minimizing the energy penalty associated with the CO2 reduction reaction. First-row transition metals are potential candidates as catalysts for electrochemical CO2 reduction; however, their high oxygen affinity makes them easy to be oxidized, which could, in turn, strongly affect the catalytic properties of metal-based catalysts. In this work, we propose a strategy to synthesize Ag–Sn electrocatalysts with a core–shell nanostructure that contains a bimetallic core responsible for high electronic conductivity and an ultrathin partially oxidized shell for catalytic CO2 conversion. This concept was demonstrated by a series of Ag–Sn bimetallic electrocatalysts. At an optimal SnOx shell thickness of ∼1.7 nm, the catalyst exhibited a high formate Faradaic efficiency of ...

Microscopic Evidence for Liquid-Liquid Separation in Supersaturated CaCO3 Solutions

Abstract: Recent experimental observations of the onset of calcium carbonate (CaCO3) mineralization suggest the emergence of a population of clusters that are stable rather than unstable as predicted by classical nucleation theory. This study uses molecular dynamics simulations to probe the structure, dynamics, and energetics of hydrated CaCO3 clusters and lattice gas simulations to explore the behavior of cluster populations before nucleation. Our results predict formation of a dense liquid phase through liquid-liquid separation within the concentration range in which clusters are observed. Coalescence and solidification of nanoscale droplets results in formation of a solid phase, the structure of which is consistent with amorphous CaCO3. The presence of a liquid-liquid binodal enables a diverse set of experimental observations to be reconciled within the context of established phase-separation mechanisms.