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Open Access Publications from the University of California

Scholarly Works (3 results)

  • Thesis
  • Peer Reviewed
UCLA Electronic Theses and Dissertations (2017)

This study used a mixed methods approach to examine children’s racial, ethnic, and national identification in middle childhood, as well as teacher’s socialization practices across two program structures. Participants were racially and ethnically diverse and included 64 3rd grade students and their 8 teachers. Children identified with a variety of racial, ethnic, and national labels – most often selecting American to describe themselves, and frequently referenced family heritage, birthplace, and cultural practices and language to explain their identification as well as other sources (e.g., food, books, and conversations with parents) that informed their identification. Teachers reported using read alouds and incorporating multiple perspectives as strategies for talking about race, ethnicity, and nationality in their classrooms. Further, results suggest more in-depth conversations and lessons about race and ethnicity in the dual language immersion classroom. Thus, middle childhood is an essential time for racial, ethnic, and national identity formation, and teachers are important socialization agents.

    Cover page: Let’s Talk about Race: Children’s Racial, Ethnic, and National Identification and Teacher’s Socialization Practices
    • Article
    • Peer Reviewed
    UC Berkeley Previously Published Works (2017)
    This study assesses the quantitative effects of incorporating high-volume fly ash (HVFA) into tricalcium silicate (C₃S) paste on the hydration, degree of silicate polymerization, and Al substitution for Si in calcium silicate hydrate (C-S-H). Thermogravimetric analysis and isothermal conduction calorimetry showed that, although the induction period of C₃S hydration was significantly extended, the degree of hydration of C₃S after the deceleration period increased due to HVFA incorporation. Synchrotron-sourced soft X-ray spectromicroscopy further showed that most of the C₃S in the C₃S-HVFA paste was fully hydrated after 28 days of hydration, while that in the pure C₃S paste was not. The chemical shifts of the Si K edge peaks in the near-edge X-ray fine structure of C-S-H in the C₃S-HVFA paste directly indicate that Al substitutes for Si in C-S-H and that the additional silicate provided by the HVFA induces an enhanced degree of silicate polymerization. This new spectromicroscopic approach, supplemented with 27Al and 29Si magic-angle spinning nuclear magnetic resonance spectroscopy and transmission electron microscopy, turned out to be a powerful characterization tool for studying a local atomic binding structure of C-S-H in C₃S-HVFA system and presented results consistent with previous literature.
      Cover page: Effects of Incorporating High-Volume Fly Ash into Tricalcium Silicate on the Degree of Silicate Polymerization and Aluminum Substitution for Silicon in Calcium Silicate Hydrate
      • Article
      • Peer Reviewed
      UC Berkeley Previously Published Works (2015)
      This paper investigates the atomic and nano-scale structures of a 50-year-old hydrated alite paste. Imaged by TEM, the outer product C-S-H fibers are composed of particles that are 1.5-2 nm thick and several tens of nanometers long. 29Si NMR shows 47.9% Q1 and 52.1% Q2, with a mean SiO4 tetrahedron chain length (MCL) of 4.18, indicating a limited degree of polymerization after 50 years' hydration. A Scanning Transmission X-ray Microscopy (STXM) study was conducted on this late-age paste and a 1.5 year old hydrated C3S solution. Near Edge X-ray Absorption Fine Structure (NEXAFS) at Ca L3,2-edge indicates that Ca2 + in C-S-H is in an irregular symmetric coordination, which agrees more with the atomic structure of tobermorite than that of jennite. At Si K-edge, multi-scattering phenomenon is sensitive to the degree of polymerization, which has the potential to unveil the structure of the SiO44 - tetrahedron chain.
        Cover page: Atomic and nano-scale characterization of a 50-year-old hydrated C3S paste
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