Spending unsupervised time online with friends encourages delinquency and drug and alcohol use among teenagers

The rise of digital communication through smartphones and other devices in the past decade has transformed the way in which adolescents communicate with one another; friends are now essentially always present and available. In new research, Jim Clark and Ryan C. Meldrum find that this connectivity – when unstructured and unsupervised by adults – is linked to adolescent delinquency and substance abuse

Electronic Structure and Optical Properties of Silicon Nanocrystals along their Aggregation Stages

The structural control of silicon nanocrystals is an important technological problem. Typically a distribution of nanocrystal sizes and shapes emerges under the uncontrolled aggregation of smaller clusters. The aim of this computational study is to investigate the evolution of the nanocrystal electronic states and their optical properties throughout their aggregation stages. To realistically tackle such systems, an atomistic electronic structure tool is required that can accommodate about tens of thousand nanocrystal and embedding lattice atoms with very irregular shapes. For this purpose, a computationally-efficient pseudopotential-based electronic structure tool is developed that can handle realistic nanostructures based on the expansion of the wavefunction of the aggregate in terms of bulk Bloch bands of the constituent semiconductors. With this tool, the evolution of the electronic states as well as the polarization-dependent absorption spectra correlated with the oscillator strengths over their aggregation stages are traced. The low-lying aggregate nanocrystal states develop binding and anti-binding counterparts of the isolated states. Such information may become instrumental with the maturity of the controlled aggregation of these nanocrystals.Comment: 5 pages, 7 figure

Formation and structure of calcium carbonate thin films and nanofibers precipitated in the presence of poly(allylamine hydrochloride) and magnesium ions

That the cationic polyelectrolyte poly(allylamine hydrochloride) (PAH) exerts a significant influence on CaCO₃ precipitation challenges the idea that only anionic additives have this effect. Here, we show that in common with anionic polyelectrolytes such as poly(aspartic acid), PAH supports the growth of calcite thin films and abundant nanofibers. While investigating the formation of these structures, we also perform the first detailed structural analysis of the nanofibers by transmission electron microscopy (TEM) and selected area electron diffraction. The nanofibers are shown to be principally single crystal, with isolated domains of polycrystallinity, and the single crystal structure is even preserved in regions where the nanofibers dramatically change direction. The formation mechanism of the fibers, which are often hundreds of micrometers long, has been the subject of intense speculation. Our results suggest that they form by aggregation of amorphous particles, which are incorporated into the fibers uniquely at their tips, before crystallizing. Extrusion of polymer during crystallization may inhibit particle addition at the fiber walls and result in local variations in the fiber nanostructure. Finally, we investigate the influence of Mg²+ on CaCO₃ precipitation in the presence of PAH, which gives thinner and smoother films, together with fibers with more polycrystalline, granular structures

Controlled biomineralization of magnetite (Fe₃O₄) by <i>Magnetospirillum gryphiswaldense</i>

Results from a study of the chemical composition and micro-structural characteristics of bacterial magnetosomes extracted from the magnetotactic bacterial strain Magnetospirillum gryphiswaldense are presented here. Using high-resolution transmission electron microscopy combined with selected-area electron diffraction and energy dispersive X-ray microanalysis, biogenic magnetite particles isolated from mature cultures were analysed for variations in crystallinity and particle size, as well as chain character and length. The analysed crystals showed a narrow size range (∼14-67 nm) with an average diameter of 46±6.8 nm, cuboctahedral morphologies and typical Gamma type crystal size distributions. The magnetite particles exhibited a high chemical purity (exclusively Fe3O4) and the majority fall within the single-magnetic-domain range

Treatment Preferences for CAM in Children with Chronic Pain

CAM therapies have become increasingly popular in pediatric populations. Yet, little is known about children's preferences for CAM. This study examined treatment preferences in chronic pediatric pain patients offered a choice of CAM therapies for their pain. Participants were 129 children (94 girls) (mean age = 14.5 years ± 2.4; range = 8–18 years) presenting at a multidisciplinary, tertiary clinic specializing in pediatric chronic pain. Bivariate and multivariate analyses were used to examine the relationships between CAM treatment preferences and patient's sociodemographic and clinical characteristics, as well as their self-reported level of functioning. Over 60% of patients elected to try at least one CAM approach for pain. The most popular CAM therapies were biofeedback, yoga and hypnosis; the least popular were art therapy and energy healing, with craniosacral, acupuncture and massage being intermediate. Patients with a diagnosis of fibromyalgia (80%) were the most likely to try CAM versus those with other pain diagnoses. In multivariate analyses, pain duration emerged as a significant predictor of CAM preferences. For mind-based approaches (i.e. hypnosis, biofeedback and art therapy), pain duration and limitations in family activities were both significant predictors. When given a choice of CAM therapies, this sample of children with chronic pain, irrespective of pain diagnosis, preferred non-invasive approaches that enhanced relaxation and increased somatic control. Longer duration of pain and greater impairment in functioning, particularly during family activities increased the likelihood that such patients agreed to engage in CAM treatments, especially those that were categorized as mind-based modalities

Soil Survey of Iowa, Report No . 77—Washington County Soils

Washington County is located in southeastern Iowa in the second tier of counties west of the Mississippi River and in the third tier north of the Missouri state line. It lies partly in the Mississippi loess and partly in the Southern Iowa loess soil areas and hence the soils are all of loessial origin

Soil Survey of Iowa, Report No. 78—Monroe County Soils

Monroe County is located in southern Iowa in the second tier of counties north of the Missouri state line and in the fourth tier west of the Mississippi River. It is entirely within the Southern Iowa loess soil area and the soils are, therefore, practically all of loessial origin. The only drift soils found are those derived from the old Kansan till which has been exposed through the erosion or washing away of the loessial covering

Soil Survey of Iowa, Report No. 71—Sac County Soils

Sac County is located in the northwestern part of Iowa, in the fourth tier of counties south of the Minnesota state line and in the third tier east of the Missouri River. It is partly in the Wisconsin drift soil area and partly in the Missouri loess area. The soils of the county are partly of glacial and partly of loessial origin