Electrical and Low Frequency Noise Characterization of Graphene Chemical Sensor Devices Having Different Geometries.

Chemiresistive graphene sensors are promising for chemical sensing applications due to their simple device structure, high sensitivity, potential for miniaturization, low-cost, and fast response. In this work, we investigate the effect of (1) ZnO nanoparticle functionalization and (2) engineered defects onto graphene sensing channel on device resistance and low frequency electrical noise. The engineered defects of interest include 2D patterns of squares, stars, and circles and 1D patterns of slots parallel and transverse to the applied electric potential. The goal of this work is to determine which devices are best suited for chemical sensing applications. We find that, relative to pristine graphene devices, nanoparticle functionalization leads to reduced contact resistance but increased sheet resistance. In addition, functionalization lowers 1/f current noise on all but the uniform mesa device and the two devices with graphene strips parallel to carrier transport. The strongest correlations between noise and engineering defects, where normalized noise amplitude as a function of frequency f is described by a model of AN/fγ, are that γ increases with graphene area and contact area but decreases with device total perimeter, including internal features. We did not find evidence of a correlation between the scalar amplitude, AN, and the device channel geometries. In general, for a given device area, the least noise was observed on the least-etched device. These results will lead to an understanding of what features are needed to obtain the optimal device resistance and how to reduce the 1/f noise which will lead to improved sensor performance.

Enhanced superconductivity in aluminum-based hyperbolic metamaterials.

One of the most important goals of condensed matter physics is materials by design, i.e. the ability to reliably predict and design materials with a set of desired properties. A striking example is the deterministic enhancement of the superconducting properties of materials. Recent experiments have demonstrated that the metamaterial approach is capable of achieving this goal, such as tripling the critical temperature TC in Al-Al2O3 epsilon near zero (ENZ) core-shell metamaterial superconductors. Here, we demonstrate that an Al/Al2O3 hyperbolic metamaterial geometry is capable of a similar TC enhancement, while having superior transport and magnetic properties compared to the core-shell metamaterial superconductors.

The role of moral disengagement in the execution process.

The present study tested the proposition that disengagement of moral self-sanctions enables prison personnel to carry out the death penalty. Three subgroups of personnel in penitentiaries located in three Southern states were assessed in terms of eight mechanisms of moral disengagement. The personnel included the execution teams that carry out the executions; the support teams that provide solace and emotional support to the families of the victims and the condemned inmate; and prison guards who have no involvement in the execution process. The executioners exhibited the highest level of moral, social, and economic justifications, disavowal of personal responsibility, and dehumanization. The support teams that provide the more humane services disavowed moral disengagement, as did the noninvolved guards but to a lesser degree than the support teams.

The psychological experience of security officers who work with executions.

Open-ended interviews were conducted with members of the "Execution Team" in Louisiana in order to understand the roles, experiences, and effects of carrying out the death penalty. Fifty of a potential 52 correctional officers who work with executions were interviewed and asked to complete mental health inventories. While emphasizing the importance of security and their professional responsibilities in carrying out the death penalty, the officers stress their respect and decency toward the inmates and all others involved with the process. Although expectably reporting high incidences of exposure to trauma and death, they generally are not clinically depressed. They rely upon religious beliefs, group identity, administrative support, and their capacity to dissociate and rely on diffusion of responsibility to suppress painful emotions. Nevertheless, the officers experience conflicted feelings and frequently report having a hard time carrying out society's "ultimate punishment."