University of Arkansas

About: University of Arkansas is a education organization based out in Fayetteville, Arkansas, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 17225 authors who have published 33329 publications receiving 941102 citations. The organization is also known as: Arkansas & UA.

Vibration of carbon nanotubes studied using nonlocal continuum mechanics

Abstract: A nonlocal continuum mechanics model is developed and applied to study the vibration of both single-walled nanotubes (SWNTs) and double-walled nanotubes (DWNTs) via elastic beam theories. The small-scale effects on vibration characteristics of carbon nanotubes are explicitly derived through a complete mechanics analysis. A qualitative validation study shows that the results based on nonlocal continuum mechanics are in agreement with the published experimental reports in this field. Numerical simulations are conducted to quantitatively show the small-scale effect on vibrations of both SWNTs and DWNTs with different lengths and diameters.

A Partition-Limited Model for the Plant Uptake of Organic Contaminants from Soil and Water

Abstract: In dealing with the passive transport of organic contaminants from soils to plants (including crops), a partition-limited model is proposed in which (i) the maximum (equilibrium) concentration of a contaminant in any location in the plant is determined by partition equilibrium with its concentration in the soil interstitial water, which in turn is determined essentially by the concentration in the soil organic matter (SOM) and (ii) the extent of approach to partition equilibrium, as measured by the ratio of the contaminant concentrations in plant water and soil interstitial water, αpt (≤ 1), depends on the transport rate of the contaminant in soil water into the plant and the volume of soil water solution that is required for the plant contaminant level to reach equilibrium with the external soil-water phase. Through reasonable estimates of plant organic-water compositions and of contaminant partition coefficients with various plant components, the model accounts for calculated values of αpt in several pu...

Mobile application usability: conceptualization and instrument development

Abstract: This paper presents a mobile application usability conceptualization and survey instrument following the 10- step procedure recommended by MacKenzie et al. (2011). Specifically, we adapted Apple's user experience guidelines to develop our conceptualization of mobile application usability that we then developed into 19 first-order constructs that formed 6 second-order constructs. To achieve our objective, we collected four datasets: content validity (n = 318), pretest (n = 440), validation (n = 408), and cross-validation (n = 412). The nomological validity of this instrument was established by examining its impact on two outcomes: continued intention to use and mobile application loyalty. We found that the constructs that represented our mobile application usability conceptualization were good predictors of both outcomes and compared favorably to an existing instrument based on Microsoft's usability guidelines. In addition to being an exemplar of the recent procedure of MacKenzie et al. to validate an instrument, this work provides a rich conceptualization of an instrument for mobile application usability that can serve as a springboard for future work to understand the impacts of mobile application usability and can be used as a guide to design effective mobile applications.

Synthesis of Cu-Doped InP Nanocrystals (d-dots) with ZnSe Diffusion Barrier as Efficient and Color-Tunable NIR Emitters

Abstract: Efficient Cu-doped InP quantum dots (Cu:InP d-dots) emitters were successfully synthesized by epitaxial growth of a ZnSe diffusion barrier for the dopants. The Cu dopant emission of the Cu:InP/ZnSe core/shell d-dots covered the important red and near-infrared (NIR) window for biomedical applicaitons, from 630 to 1100 nm, by varying the size of the InP host nanocrystals. These new d-dots emitters not only compensate for the emission wavelength of the existing noncadmium d-dots emitters, Cu- and Mn-doped ZnSe d-dots (450-610 nm), but also offer a complete series of efficient nanocrystal emitters based on InP nanocrystals. The one-pot synthetic scheme for the formation of Cu:InP/ZnSe core/shell d-dots was successfully established by systematically studying the doping process, the dopant concentration-dependent photophysical properties, and the dopant diffusion during shell epitaxy, etc. Complete elimination of InP bandgap emission and efficient pure dopant emission (with photoluminescence quantum yield as high as between 35-40%) of the core/shell d-dots were achieved by optimizing the final doping level and the diffusion barrier thickness.

Witnessing spouse abuse and experiencing physical abuse: A "double whammy"?

Abstract: Child witnesses to parental violence, both abused (N =40) and nonabused (N =44), who were temporarily residing in a battered women's shelter were compared with children from a similar economic background (N =66) on measures of anxiety, depression, and behavior problems. Mothers of the three groups of children (comparison, witness, abused/witness) across the age range from 4 to 12 years completed a behavior problem inventory; the youngsters responded to paper-and-pencil self-report measures. Results indicated that the abused/witness children were manifesting significantly more distress on the behavior problem measure than the comparison youngsters, with the witness children showing a moderate amount and the comparison children the least. However, these patterns were mediated by the age of the child. Implications of these differential findings are discussed.