The overall objective of this work is the development of a high density sensor array using singe wall carbon nanotube (SWNT) hybrid structures as the platform material for the realization of highly sensitive, selective and discriminative gas sensors for monitoring of industrial and automotive emissions in the environment. To conceive such desired sensor characteristics SWNTs were surface functionalized with metal and metal oxide active materials [i.e. ZnO, Ag, Pt, Pd, Au] to target specific analytes. Detailed analysis of ZnO electrodeposition on to SWNTs was performed to investigate structure property relations between ZnO particle size, density, material quality, catalyst type, and combination thereof, towards the sensing performance and analyte specificity.

Room temperature gas sensing performance of environmentally significant gases such NH3, SO2, H2S, NO2, CO, CO2, benzene derivatives, alkanes, and alcohols was evaluated using the metal and metal oxide hybrid structures. The ZnO-SWNT hybrid structures exhibited characteristic selectivity towards H2S, with enhanced sensitivity, response and recovery time contingent of crystal orientation; additionally as synthesized ZnO-SWNT hybrid structures displayed conductance response cognizance of xylene isomers (ortho, para, meta). Furthermore, at the hand of sequential incorporation of a metal catalysts (Au, Ag, Pt, and Pd), the ZnO-SWNT system showed distinct charge dependant pattern recognition towards less detectable analytes such as SO2 and NO2; metal-SWNT hybrid structures with Pd as the second deposited metal demonstrated enhanced sensitivity towards NO2 and NH3 due to the enhanced dissociation of the molecular adsorbate on the catalytically active Pd nanoparticle surface.

Understanding of the deposition process was then extended to the deposition of binary metals Au, Pd, Pt, followed by sequential deposition of a combination of metals. Emphases was placed on both the gas sensing aspect of the resultant hybrid structures, and also on the ability to site specifically control the deposition of the second metal. A detailed examination of these hybrid nanostructures and the nature of their responses towards different gaseous environments was studied and compared with the performance of unfunctionalized carbon nanotubes.

Background: Smokers seeking treatment to quit smoking are generally not assessed for current depression, yet depression among smokers may influence quitting outcome.

Purpose: This study aims to formally assess current major depression among smokers calling a state tobacco quitline.

Methods: A total of 844 smokers calling the California Smokers’ Helpline in 2007 were screened for depression by the mood module of the Patient Health Questionnaire (PHQ-9). The Social Functioning Questionnaire (SFQ) was also administered to these callers. Two months after the screening, follow-up evaluations were conducted to assess cessation outcome.

Results: In all, 24.2% of smokers met criteria for current major depression and 16.5% reported symptoms indicating mild depression. Callers with current major depression were more likely to be heavy smokers and on Medicaid. Moreover, 74.0% of smokers with current major depression had substantial social and occupational functioning deficits. Two months later, those with major depression at baseline were significantly less likely to have quit smoking (18.5% vs 28.4%).

Conclusions: Almost one in four smokers to the California Smokers’ Helpline met criteria for current major depression. Over 400,000 smokers call state quitlines in the U.S. for help with quitting each year, which means that as many as 100,000 smokers with serious depressive symptoms are using these services annually. The large number of depressed smokers who seek help suggests a need to develop appropriate interventions to help them quit successfully.

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