ABSTRACT

Purpose: To evaluate the effectiveness of xylitol wipes on caries prevention in high-risk infants.

Methods: In a double-blinded randomized controlled clinical trial, 44 mother-infant pairs were randomized into xylitol-wipe or placebo-wipe groups (n=22 per group). Guardians were instructed to use wipes on their infants 3-4 times daily and to brush the infants teeth with fluoride toothpaste twice daily. Saliva samples for mutans streptococci (MS) and lactobacilli (LB) enumeration (CFU/ml) and DMFS/dmfs scores were collected from mother-infant pairs at baseline and 1 year.

Results: Eighteen (xylitol-wipe group) and 11 (placebo-wipe group) pairs completed the study. Five dropout subjects from the placebo group returned at 1 year. The mean±SE logMS counts in infants at 1 year were 2.7±0.6 for the xylitol-wipe group, 2.8±0.8 for the placebo-wipe group, and 5.0±1.2 for the dropout group with logLB levels as 0.1±0.1, 0.1±0.1, and 1.4±0.9 respectively. Only the dropout group had significantly higher logLB at 1 year compared to the 2 wipe groups (ANOVA, p < 0.05). Children in the xylitol-wipe group had significantly fewer new decayed surfaces at 1 year (mean new ds±SE=0.06±0.06, p < 0.05) than the placebo-wipe (mean new ds±SE=0.45±0.20) and the dropout group (mean new ds±SE=0.75±0.47).

Conclusions: Although xylitol-wipe use did not significantly reduce MS and LB levels in infants, the development of new caries was significantly reduced by the use of xylitol wipes in infants daily. Wipe-use alone may help reduce cariogenic bacteria in infants. The daily use of xylitol wipes in infants in conjunction with brushing with fluoride toothpaste may be a very successful caries preventive regimen for infants.

This work focuses on the design, synthesis, characterization and integration of multiferroic composite materials via radical-enhanced atomic layer deposition (RE-ALD). Specifically, ferrimagnetic CoFe2O4 is integrated with multiferroic BiFeO3 and ferroelectric HfO2 (FE-HfO2), respectively, to create two distinct composite systems. The use of multiferroic BiFeO3 as the ferroelectric phase offers the potential of employing two interfacial coupling phenomena simultaneously. On the other hand, desirable ferroelectric property and superior Si-compatibility that FE-HfO2 can offer make it an intriguing material system for further implementation into device processing at an industrial scale.

In the CoFe2O4/BiFeO3 system, high-quality CoFe2O4 and BiFeO3 were synthesized on SrTiO3 (001) substrates via RE-ALD using TMHD-based metalorganic precursors (TMHD = 2,2,6,6-tetramethylheptane-3,5 dione) and atomic oxygen. With post-deposition thermal treatments, BiFeO3 exhibited epitaxial single-crystalline growth in its (001)pc orientation. Ferroelectric switching and measurable ferromagnetism confirmed the multiferroicity of BiFeO3. CoFe2O4 exhibited textured-polycrystalline growth with a ~10-nm epitaxial transition layer, which led to tunable ferrimagnetism with a thickness-related strain relaxation process. The CoFe2O4 thin films exhibited magnetic behavior that is comparable with the ones synthesized by other processing techniques as well as bulk crystals. Nano-laminates of CoFe2O4/BiFeO3 in 2D-2D configuration were synthesized on SrTiO3 (001) and Si (001) substrates. By fixing the nanolaminate total thickness at 55 nm and CoFe2O4-BiFeO3 ratio at a constant of CoFe2O4:BiFeO3 = 15:40 while increasing the number of alternating layers up to 5 layers, the tri-layer BiFeO3/CoFe2O4/BiFeO3 structure exhibits the most promising functional properties with an optimized polarization ~17 μC/cm2 and saturation magnetism (Ms) ~125 emu/cm3. Both strain and magnetic interactions were observed at the interface for the nano-laminates due to the multiferroic nature of BiFeO3. The tri-layer structure exhibited a converse magnetoelectric coupling coefficient (αconverse) of ~22 Oe cm/kV. By scaling the nano-laminate from ~55 nm to ~16 nm in total thickness, αconverse is further improved to ~64 Oe cm/kV, comparable with systems reported with much higher thicknesses. As the first demonstration of a fully ALD-synthesized multiferroic composite, this part of the work reveals the possibility to utilize ALD to optimize multiferroic nano-laminates for further integrations into magnetoelectric devices.

For CoFe2O4/FE-HfO2 composites, HfO2 thin films were synthesized with tetrakis(dimethylamido)hafnium(IV) (TDMAH) and atomic oxygen. In this design, CoFe2O4 served not only as the mechanical confinement layer but also as an active magnetic layer that contributed to overall magnetism. For ~6nm HfO2 annealed at ~700 �C, the CoFe2O4/FE-HfO2 composites exhibited a remnant polarization (Pr) ~5.5 μC/cm2 and an electrical coercivity (Ec) ~2000 kV/cm as well as an out-of-plane magnetic anisotropy with a saturation magnetization (Ms) of ~155 emu/cm3 and a magnetic coercivity (Hc) ranging from ~1000-3400 Oe. Magnetoelectric characterization revealed promising magnetoelectric coupling, with αconverse ranged 55-168 Oe cm/kV at room-temperature, once again is comparable with other systems reported with much higher thicknesses. It is believed that the CoFe2O4/FE-HfO2 system here opens many new avenues for developing future magnetoelectric composites and related devices.

Race-conscious admissions policies have been debated throughout the years. It has been well-documented that members of the Asian American community have differing opinions on the policy (e.g., Poon et al., 2019; Takagi, 1992). Given these differing opinions, the purpose of this study was to understand the connections between identity and racial ideology and their impact on an individual’s opinion regarding race-conscious admissions. To explore the relationship between identity, ideology, and opinion, I investigated the four components of racial consciousness defined by Sellers et al.’s (1998) multidimensional model of racial identity.

Findings indicated three forms of racial consciousness: race-avoidant, within-group, and collective liberation. Each form of consciousness is informed by different areas of literature, including literature on discrimination, racial identity, racial ideology, and attitudes regarding one’s racial group. Characteristics of race-avoidant consciousness include a sense of inferiority to white norms, a cultural connection to racial identity, color-evasive ideologies to address racial inequities, and alignment with whiteness. Key characteristics of within-group consciousness include a sense of inferiority to white norms, a cultural connection to racial identity, and a focus on Asian American-specific issues, such as data disaggregation and socioeconomic stratification. Collective liberation consciousness is defined by a political connection to racial identity, a belief that race is entwined with all other identities and ideologies, and a sense of solidarity with other communities of color.

The three forms of racial consciousness highlight the various ways Asian American college students make connections between their experiences with race and their opinion on race-conscious admissions. Without building critical racial consciousness, differing opinions within the Asian American community can unintentionally detract from important policies and have long-lasting and dangerous implications for racial justice.

Alternatives to the use of radioisotopes to measure cell proliferation in mixed lymphocyte reactions (MLR) are desirable to avoid the hazards and costs associated with radioisotope use. The versatile fluorochrome 5,6-carboxyfluorescein diacetate succinimidyl ester (CFSE) has been used to measure MLR and provides the opportunity to measure several different growth parameters. This study was aimed at determining which growth parameter is most practical and suitable for measuring murine MLR. The parameters measured were: the relative number of daughter T-cells, the relative number and frequency of reactive T-cell precursors and the relative number of mitotic events. Responder cells were CFSE-labeled unfractionated splenocytes from C57BL/6 mice. Stimulator cells included irradiated splenocytes from C57BL/6 (control), B6D2F(1) (haplo-allogeneic) or FVB/N (allogeneic) mice. Cultures were harvested daily for 1 week. Stimulator T-cells rapidly declined to less than 0.2-0.3% of the mixed population by day 2 of culture. Experimental groups had a significantly higher number of daughter T-cells and mitotic events after 2 days of culture with the number of daughter T-cells climbing exponentially after 5 days of culture. The number and frequency of reactive T-cell precursors were significantly higher in experimental groups on days 2-3, but this difference became insignificant by day 4. Among all the parameters, the relative number of daughter T-cells was the most practical for measuring MLR, after 5 days of culture, based upon the growth kinetics of responder T-cells and the survival of the stimulator cells. (C) 2003 Elsevier B.V. All rights reserved.