Interlaboratory comparison of size measurements on nanoparticles using nanoparticle tracking analysis (NTA)

One of the key challenges in the field of nanoparticle (NP) analysis is in producing reliable and reproducible characterisation data for nanomaterials. This study looks at the reproducibility using a relatively new, but rapidly adopted, technique, Nanoparticle Tracking Analysis (NTA) on a range of particle sizes and materials in several different media. It describes the protocol development and presents both the data and analysis of results obtained from 12 laboratories, mostly based in Europe, who are primarily QualityNano members. QualityNano is an EU FP7 funded Research Infrastructure that integrates 28 European analytical and experimental facilities in nanotechnology, medicine and natural sciences with the goal of developing and implementing best practice and quality in all aspects of nanosafety assessment. This study looks at both the development of the protocol and how this leads to highly reproducible results amongst participants. In this study, the parameter being measured is the modal particle size

Cognitive training, conflict resolution, and exercise: Effects on young adolescents' well-being

Background: This study builds on previous studies reporting that depressive symptoms among adolescents are reduced and personal satisfactions with one's achievements and competence with peers are enhanced when students are taught strategies for engaging in more optimistic thinking (explanatory style) (Gillham, Reivich, & Freres et al., 2006) and social problem-solving (Ingoldsby, Kohl, McMahon, & Lengua, 2006). Additionally, engaging in regular exercise has also been found to be useful in reducing depressive symptoms in this age group (Bodin & Martinsen, 2004). Aim: The study investigated the effects of three interventions - explanatory style (cognitive training), conflict resolution, and exercise - known to help adolescents develop a strong sense of wellbeing. It involved 31 students aged 11 to 13 years and their parents, and six class teachers from a large, metropolitan, private boys' college in Brisbane, Australia. Methods: Twenty-five boys participated in the three interventions, while six boys acted as a comparison group. A counterbalanced, multiple baseline design was implemented so that students participated in the three interventions in a different order. Results: The results showed that students in the intervention group experienced a reduction of internalising behaviours such as withdrawal and depressive symptoms following all three interventions. Collectively, the interventions were successful in reducing depressive symptoms; individually, they also significantly reduced depressive symptoms. Conclusions: The results showed that explanatory style, conflict resolution, and exercise interventions are effective in reducing depressive symptoms in adolescents

On the Role of Specific Interactions in the Diffusion of Nanoparticles in Aqueous Polymer Solutions

Understanding nanoparticle diffusion within non-Newtonian biological and synthetic fluids is essential in designing novel formulations (e.g., nanomedicines for drug delivery, shampoos, lotions, coatings, paints, etc.), but is presently poorly defined. This study reports the diffusion of thiolated and PEGylated silica nanoparticles, characterized by small-angle neutron scattering, in solutions of various water-soluble polymers such as poly(acrylic acid) (PAA), poly(Nvinylpyrrolidone) (PVP), poly(ethylene oxide) (PEO), and hydroxyethylcellulose (HEC) probed using NanoSight nanoparticle tracking analysis. Results show that the diffusivity of nanoparticles is affected by their dimensions, medium viscosity, and, in particular, the specific interactions between nanoparticles and the macromolecules in solution; strong attractive interactions such as hydrogen bonding hamper diffusion. The water-soluble polymers retarded the diffusion of thiolated particles in the order PEO > PVP > PAA > HEC whereas for PEGylated silica particles retardation followed the order PAA > PVP = HEC > PEO. In the absence of specific interactions with the medium, PEGylated nanoparticles exhibit enhanced mobility compared to their thiolated counterparts despite some increase in their dimensions