Structural aspects of redox-mediated electron tunneling (Dedicated to the memory of professor Alexander M. Kuznetsov)

We investigated structural aspects of electron transfer (ET) in tunneling junctions (Au(1 1 1)vertical bar FcN vertical bar solution gap vertical bar Au STM tip) with four different redox-active N-thioalk(ano)ylferrocenes (FcN) embedded. The investigated molecules consist of a redox-active ferrocene (Fc) moiety connected via alkyl spacers with N = 4, 6, 8 and 11 carbon atoms to a thiol anchoring group. We found that for short FcNs (N = 4, 6,8) the redox-mediated ET response increases with the increase of the alkyl chain length, while no enhancement of the ET was observed for Fc1 1. The model of two-step ET with partial vibrational relaxation by Kuznetsov and Ulstrup was used to rationalize these results. The theoretical ET steps were assigned to two processes: (1) electron tunneling from the Fc group to the Au tip through the electrolyte layer and (2) electron transport from the Au(1 1 1) substrate to the Fc group through the organic adlayer. We argue that for the three short FcNs, the first process represents the rate-limiting step. The increase of the length of the alkyl chain leads to an approach of the Fc group to the STM tip, and consequently accelerates the first El' step. In case of the Fcl 1 junctions the rather high thickness of the organic layer leads to a decrease of the rate of the second ET step. In consequence, the contribution of the redox-mediated current enhancement to the total tunneling current appears to be insignificant. Our work demonstrates the importance of combined structural and transport approaches for the understanding of Er processes in electrochemical nanosystems. (C) 2010 Elsevier B.V. All rights reserved.

The Johann Jacob Wepfer Award 2012 of the European Stroke Conference to Professor Louis R. Caplan

No abstract available.

Effect of Participant Gender, Professor Gender, and Activity Interventions on the Understanding of Concepts in Thermodynamics

Misconceptions about heat and temperature have been seen across all educational levels, even in undergraduate engineering courses. One way these misconceptions can be remediated is through instructional methods, such as inquiry-based activities. Performance on assessments in sciences and engineering has been found to vary when gender is taken into consideration. The purpose of the current study was to investigate the effects of participant gender, professor gender, and level of inquiry-based activities on the conceptual understanding of 247 undergraduate engineering students in thermodynamics. A pre-test post-test design was used. Conceptual understanding of thermodynamics was measured by students’ scores on the Concept Inventory for Engineering Thermodynamics (CIET; Vigeant, Prince & Nottis, 2011). Inquiry-based activities were developed by the researchers and given to professors who determined if they would do all, some, or none of them as they taught. Significant differences were found among participants of different gender, different gender of the professor instructing the course, and level of inquiry-based activity. The participants who were exposed to all of the activities provided didsignificantly better on the post-test than those who were only exposed to some or none of the activities. The results from this current study indicated that differences in gender, professorgender, and level of inquiry-based activity has an effect on undergraduate engineering students’ conceptual understanding of thermodynamics. Future research should investigate more factorsthat contribute to lower representation of women in the engineering field.