Selective penetration of liquid-phase organic probe molecules into SAM of 2-mercapto-3-n-octylthiophene

An inherently disorganized self-assembled monolayer (SAM) of 2-mercapto-3-n-octylthiophene (MOT) has been formed on a gold bead electrode from its dilute ethanolic solution. The disorganization of the monolayer is attributed to the loose packing of the aliphatic chains of the MOT adsorbates, which results from a large difference in dimension/or cross-sectional area between the head (thiophene thiolate) and the tail (alkane chain) groups. Electrochemical measurements including ac impedance spectroscopy and metal underpotential deposition have shown that the monolayer is almost pinhole free. However, the MOT SAM can be penetrated by an organic probe molecule with affinity for the alkane chain part of the monolayer. Some typical probe molecules with different size and hydrophilicity have been employed to assess the permselectivity of the monolayer. Measurement results demonstrate that the ability of the employed probe molecules to penetrate into the monoalyer is mainly dominated by their hydrophilicity/or hydrophobicity. The results presented here suggest the potential application of MOT monoalyer to effectively modify the electrode surface for several research areas such as electrochemical sensors, electrocatalysis, electroanalysis, and supported hybrid bilayer membranes.

Determination of surface pK(a) of SAM using an electrochemical titration method

A self-assembled monolayer (SAM) of 3-mercaptopropionic acid (HSCH2CH2COOH) was formed on a gold electrode. The effect of the charge of the end group on the electrochemical response of Fe(CN)(6)(3-) at the SAM modified electrode was studied by using cyclic voltammetry. At high pH, when the -COOH groups are dissociated, Fe(CN)(6)(3-) current is suppressed; as the solution pH is lowered, Fe(CN)(6)(3-) current increases. The electrochemical titration curve was obtained by correlating the currents to the different electrolyte pH values, from which the surface pK(a) was obtained to be 5.2+/-0.1. Furthermore, a calculation equation was presented to simulate the electrochemical titration. As comparison, the surface pK(a) was also measured by contact angle titration as 5.6+/-0.1. The surface pK(a) values determined by the two methods in our work are consistent and accurate.

The 1863 Melbourne Shakespeare War: Barry Sullivan, Charles and Ellen Kean, and the Play of Cultural Usurpation on the Australian Stage

This essay investigates an intricate drama of cultural identity in performances of Shakespeare on the nineteenth-century Melbourne stage. It considers the rivalry between Charles and Ellen Kean and their competitor, Barry Sullivan, for the two-month period in 1863 during which their Australian tours overlapped. This Melbourne Shakespeare war was anticipated,augmented, and richly documented in Melbourne’s papers: The Age, The Argus and Melbourne Punch. This essay pursues two seams of inquiry. The first is an investigation of the discourses of cultural and aesthetic value laced through the language of reviews of their Shakespearean roles.The essay identifies how reviewers register affective engagement with the performers in these roles, and suggests how the roles themselves reflected, by accident or design, the terms of the dispute. The second is concerned with the national identity of the actors. Kean, although born in Waterford, Ireland, had held the post of Queen Victoria’s Master of the Revels and identified himself as English. Sullivan, although born in Birmingham, was of Cork parentage and was identified as Irish by both his supporters and his detractors. This essay tracks the development of the actors’ national and artistic identities established prior to Melbourne and ask how they played out on in the context of the particularities of Australian reception. It shows that, in this instance, these actors were implicated in complex debates over national authority and cultural ownership.

Teaching the physiology of adaptation to hypoxic stress with the aid of a classic paper on high altitude by Houston and Riley

Many pathological conditions exist where tissues exhibit hypoxia or low oxygen tension. Hypoxic hypoxia arises when there is a reduction in the amount of oxygen entering the blood and occurs in healthy people at high altitude. In 1946, research sponsored by the United States Navy led to the collection and subsequent publication of masses of data demonstrating the physiological consequences and adaptations of ascent to high altitude. This article describes how a figure from a 1947 paper from the American Physiological Society Legacy collection (Houston CS, Riley RL. Respiratory and circulatory changes during acclimatization to high altitude. Am J Physiol 149: 565-588) may be used to allow students to review their understanding of some of the generalized effects of hypoxia on the body. In particular, this figure summarizes some of the adaptive responses that take place in the oxygen transport system as a consequence of prolonged hypoxia.