802 research outputs found

    Building Successful Neighborhoods

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    Reviews the literature on direct interventions to revitalize distressed neighborhoods by improving housing, schools, and services in terms of basic policy and strategy, programmatic strategies, and building institutional infrastructure

    Solution-Phase Synthesis of Heteroatom-Substituted Carbon Scaffolds for Hydrogen Storage

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    This paper reports a bottom-up solution-phase process for the preparation of pristine and heteroatom (boron, phosphorus, or nitrogen)-substituted carbon scaffolds that show good surface areas and enhanced hydrogen adsorption capacities and binding energies. The synthesis method involves heating chlorine-containing small organic molecules with metallic sodium at reflux in high-boiling solvents. For heteroatom incorporation, heteroatomic electrophiles are added to the reaction mixture. Under the reaction conditions, micrometer-sized graphitic sheets assembled by 3−5 nm-sized domains of graphene nanoflakes are formed, and when they are heteroatom-substituted, the heteroatoms are uniformly distributed. The substituted carbon scaffolds enriched with heteroatoms (boron ~7.3%, phosphorus ~8.1%, and nitrogen ~28.1%) had surface areas as high as 900 m^2 g^(−1) and enhanced reversible hydrogen physisorption capacities relative to pristine carbon scaffolds or common carbonaceous materials. In addition, the binding energies of the substituted carbon scaffolds, as measured by adsorption isotherms, were 8.6, 8.3, and 5.6 kJ mol^(−1) for the boron-, phosphorus-, and nitrogen-enriched carbon scaffolds, respectively

    Building Environmentally Sustainable Communities: A Framework for Inclusivity

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    Reviews literature on past inequitable and unsustainable urban development and visions for linking sustainability, opportunity, and inclusion. Analyzes possible metrics for measuring sustainability and access as well as next steps for policy

    Public Housing Transformation and Crime: Making the Case for Responsible Relocation

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    The research in this article examines the effect on crime rates of public housing transformation in Atlanta and Chicago, focusing on the neighborhoods receiving households relocated with housing vouchers. Modeling the complex relationship between voucher holder locations and crime, using quarterly data, our analysis found that crime rates fell substantially in neighborhoods with public housing demolition, whereas destination neighborhoods experienced a much lesser effect than popular accounts imply. Nevertheless, on average, negative effects emerge for some neighborhoods with modest or high densities of relocated households compared with conditions in areas without relocated households. Overall, we estimate small net decreases citywide in violent crime over study periods during which crime declined significantly. These findings suggest a need for thoughtful relocation strategies that support both assisted residents and receiving communities

    Planning the Housing Opportunity and Services Together Demonstration: Challenges and Lessons Learned

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    Offers insights from designing and implementing a project to address barriers to self-sufficiency among low-income parents, such as poor health and low education levels, while integrating services for children and youth in public and mixed-income housing

    Spontaneous formation and stability of small GaP fullerenes

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    We report the spontaneous formation of a GaP fullerene cage in ab-initio Molecular Dynamics simulations starting from a bulk fragment. A systematic study of the geometric and electronic properties of neutral and ionized GaP clusters suggests the stability of hetero-fullerenes formed by a compound with zincblend bulk structure. We find that GaP fullerenes up to 28 atoms have high symmetry, closed electronic shells, large HOMO-LUMO energy gaps and do not dissociate when ionized. We compare our results for GaP with those obtained by other groups for the corresponding BN clusters.Comment: To appear on PRL, 4 pages, 1 figure, Late

    NbSe3: Effect of Uniaxial Stress on the Threshold Field and Fermiology

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    We have measured the effect of uniaxial stress on the threshold field ET for the motion of the upper CDW in NbSe3. ET exhibits a critical behavior, ET ~ (1 - e/ec)^g, wher e is the strain, and ec is about 2.6% and g ~ 1.2. This ecpression remains valid over more than two decades of ET, up to the highest fields of about 1.5keV/m. Neither g nor ec is very sensitive to the impurity concentraction. The CDW transition temperature Tp decreases linearly with e at a rate dTp/de = -10K/%, and it does not show any anomaly near ec. Shubnikov de-Haas measurements show that the extremal area of the Fermi surface decreases with increasing strain. The results suggest that there is an intimate relationship between pinning of the upper CDW and the Fermiology of NbSe3.Comment: 4 pages, 5 figure

    The Mediating Effects of Student Attitudes on the Learning Preferences and Perceived Academic Stress Towards Online Education

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    The study investigates the association of the learners' preferences of students and perceived academic stress and the mediating impact of students’ attitudes towards online education. The study participants were the students of the seven major universities and colleges in Ilocos Norte, and they were chosen using a convenience sampling technique. The study employed a quantitative research design and a casual research approach to measure the relationship between learning preferences and perceived academic stress and the mediating effect of students’ attitudes towards online education. Using linear regression, the findings revealed a low positive relationship between learning preferences and perceived academic stress. Moreover, concerning the mediating effect of the students’ attitudes towards online education, using structural equation modelling, the results were that there was an established effect. Implications, conclusions, and recommendations were also provided in the study
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