Length distribution of single-walled carbon nanotubes in aqueous suspension measured by electrospray differential mobility analysis.

The first characterization of the length distribution of single-walled carbon nanotubes (SWCNT) dispersed in a liquid by electrospray differential mobility analysis (ES-DMA) is presented. Although an understanding of geometric properties of SWCNTs, including length, diameter, aspect ratio, and chirality, is essential for commercial applications, rapid characterization of nanotube length distributions remains challenging. Here the use of ES-DMA to obtain length distributions of DNA-wrapped SWCNTs dispersed in aqueous solutions is demonstrated. Lengths measured by ES-DMA compare favorably with those obtained from multiangle light scattering, dynamic light scattering, field flow fractionation with UV/vis detection, and atomic force microscopy, validating ES-DMA as a technique to measure SWCNTs of <250 nm in length. The nanotubes are previously purified and dispersed by wrapping with oligomeric DNA in aqueous solution and centrifuging to remove bundles and amorphous carbon. These dispersions are particularly attractive due to their amenability to bulk processing, ease of storage, high concentration, compatibility with biological and high-throughput manufacturing environments, and for their potential applications ranging from electronics and hydrogen-storage vessels to anticancer agents.

Legal, individual, and environmental predictors of court disposition in a sample of serious adolescent offenders.

Historically, the juvenile court has been expected to consider each youth's distinct rehabilitative needs in the dispositional decision-making process, rather than focusing on legal factors alone. This study examines the extent to which demographic, psychological, contextual, and legal factors, independently predict dispositional outcomes (i.e., probation vs. confinement) within two juvenile court jurisdictions (Philadelphia, Phoenix). The sample consists of 1,355 14- to 18-year-old male and female juvenile offenders adjudicated of a serious criminal offense. Results suggest that legal factors have the strongest influence on disposition in both jurisdictions. For example, a higher number of prior court referrals is associated with an increased likelihood of secure confinement in both jurisdictions. Juveniles adjudicated of violent offenses are more likely to receive secure confinement in Phoenix, but are more likely to be placed on probation in Philadelphia. Race is unrelated to dispositional outcome, but, males are consistently more likely than females to be placed in secure confinement. Importantly, individual factors (e.g., developmental maturity) generally were not powerful independent predictors of disposition. Finally, an examination of the predictors of juvenile versus adult court transfer in Phoenix indicated that males, older juveniles, and those with a violent adjudicated charge were more likely to be transferred to adult court, while juveniles scoring high on responsibility as well as those juveniles with an alcohol dependence diagnosis were more likely to be retained in juvenile court.

Predictors of posttraumatic stress in police and other first responders.

We provide an overview of previous research conducted by our group on risk and resilience factors for PTSD symptoms in police and other first responders. Based on our work, the findings of other investigators on individual differences in risk for PTSD, and drawing on preclinical studies fear conditioning and extinction, we propose a conceptual model for the development of PTSD symptoms emphasizing the role of vulnerability and resilience to peritraumatic panic reactions. We tested this conceptual model in a cross-sectional sample of police officers (n = 715). Utilizing an hierarchical linear regression model we were able to explain 39.7% of the variance in PTSD symptoms. Five variables remained significant in the final model; greater peritraumatic distress (beta = 0.240, P < .001), greater peritraumatic dissociation (beta = 0.174, P < .001), greater problem-solving coping (beta = 0.103, P < .01), greater routine work environment stress (beta = 0.182, P < .001), and lower levels of social support (beta = -0.246, P < .001). These results were largely consistent with the proposed conceptual model. Next steps in this line of research will be to test this model prospectively in a sample of 400 police academy recruits assessed during training and currently being followed for the first 2 years of police service.