New approaches for the study of the kinetics of reactions at immiscible liquid/liquid and air/liquid interfaces

This thesis describes the development of new techniques and new approaches for studying the kinetics and mechanisms of reactions which occur at the interface between two immiscible liquids. New approaches for studying the kinetics of transfer processes at the air/water interface are also described. Scanning electrochemical microscopy (SECM) is employed in the equilibrium perturbation (BP) mode for studying reversible transfer processes at liquid/liquid and air/water interfaces. In this application, an ultramicroelectrode (UME) located in an aqueous phase, at micro metre distances from the interface of interest, is employed to drive a transfer process, initially at equilibrium, in the direction of the aqueous phase by depleting the local aqueous concentration of a target species by electrolysis. The UME current flow depends on the transfer kinetics at the interface. The development of a submarine UME allows SECM to be conducted at the air/water interface, or at a liquid/liquid interface with the electrode in the more dense phase. The kinetics of the extraction/stripping reactions of aqueous copper (II) with an oxime ligand (Acorga PSO) in 1,2-dichloroethane (DCE) and heptane are first investigated. Subsequently, measurements of the kinetics of oxygen transfer across a condensed monolayer of l-octadecanol, as a function of surface area, demonstrate that the accessible free area of the interface primarily governs the rate of oxygen transfer. SECM double potential step chronoamperometry is developed to study irreversible transfer processes at interfaces. Theoretical modelling is applied and tested through experimental measurements on model interfaces. Subsequently, the rate of transfer of bromine from aqueous solutions to DCE and to air is shown to be above the upper limit measurable by the technique, however, a lower limit on the first order transfer rate constant ofO.S cm S-l is assigned. A new technique, termed microelectrochemical measurements at expanding droplets (MEMED) is developed for studying spontaneous reactions at liquid/liquid interfaces. In MEMED, the two liquids are contacted by flowing one (feeder) through a capillary submerged in the second (receptor), resulting in the growth of drops at the capillary tip. The interfacial reaction generates a product or reactant concentration profile, which extends into the receptor phase. This is probed directly using a UME positioned opposite the capillary in the solution, operated in either a potentiometric or an amperometric mode, as a local concentration probe. A numerical model for mass transport in this configuration is developed, and the technique and model are assessed by measuring both bromine transfer from aqueous sulfuric acid solutions to drops of DCE, and bimolecular electron transfer between iridium (IV) chloride in the aqueous solution and ferrocene in the organic phase, which exhibit transport-controlled transfer rates under the conditions employed. The MEMED technique is applied to measure the kinetics of the hydrolysis of triphenylmethyl chloride (TPMCl), at the DCE/water interface, through potentiometric measurement of the chloride ion concentration profile. The reaction is shown to be first-order in TPMCI, occurring interfacially, with a rate constant of 6.5 x 10-5 cm s". Subsequently, the oxidation of methylanisole (MA) (feeder) by aqueous solutions of cerium (IV) (Ce(IV» (receptor), is probed. Under the conditions of this study, the reaction at the interface dominates, with a negligible contribution from the aqueous phase reaction between dissolved MA and Ce(IV)

The Effect of Telerehabilitation on Missed Appointment Rates

The purpose of this study was to examine the effect of telerehabilitation on missed appointment rates in a rehabilitation clinic.  Clients fail to attend scheduled appointments for a variety of reasons.  Unmet appointments represent a loss of financial support as well as diminished efficiency and capacity to provide services. Speech therapy utilizing multiple appointments is most difficult to maintain during a treatment regimen. This may cause individuals to miss appointments and therefore not achieve desired results.  For this study, researchers utilized an intense speech therapy technique, the Lee Silverman Voice Treatment (LSVT®) to measure compliance with scheduled appointments. Participants were randomized to either in-person treatment or telerehabilitation treatment at a site distant from the speech-language pathologist. Participants in the telerehabilitation (TR) condition completed significantly more appointments than participants in the in-person (IP) condition. When comparing results of treatment for each condition, there were no significant differences in outcome whether treated in the IP or TR condition of the study for monologue and picture description tasks, which are closely associated with conversational speech.  There was a difference in the reading task with participants demonstrating significantly better post treatment results in the IP condition.  The reason for this disparity is unclear and warrants further study

Cellular functions of NSF: Not just SNAPs and SNAREs

AbstractN-ethylmaleimide sensitive factor (NSF) is an ATPases associated with various cellular activities protein (AAA), broadly required for intracellular membrane fusion. NSF functions as a SNAP receptor (SNARE) chaperone which binds, through soluble NSF attachment proteins (SNAPs), to SNARE complexes and utilizes the energy of ATP hydrolysis to disassemble them thus facilitating SNARE recycling. While this is a major function of NSF, it does seem to interact with other proteins, such as the AMPA receptor subunit, GluR2, and β2-AR and is thought to affect their trafficking patterns. New data suggest that NSF may be regulated by transient post-translational modifications such as phosphorylation and nitrosylation. These new aspects of NSF function as well as its role in SNARE complex dynamics will be discussed

The Historical Writing of Alfred of Beverley

Author’s note 1: Fig 1 p. 34 Item 5. Presently reads 'Grant in free alms by William Tison to Rufford Abbey (Cistercian) of land in ‘Arthes’ in Averham in East Riding of Yorkshire'. It should read 'Grant in free alms by William Tison to Rufford Abbey (Cistercian) of land in ‘Arthes’ in Averham, south west of the village of Kelham in Nottinghamshire'.Author's note 2: Fig.2 p.49. Cambridge, Trinity College, MS O.2.52. Final sentence should read- 'The text of the manuscript takes Alfred's Historia down to the accession of William I in 1066.'Author's note 3: Page 200, ‘The Death of Earl Godwine’. Whilst Geoffrey Gaimar’s Estoire des Engleis, extensively reports the public trial of Earl Godwine for complicity in the death of Alfred, brother of Edward the Confessor, he does not describe his death resulting from trial-by-bread.This thesis examines the historical writing of the twelfth-century Yorkshire historian Alfred of Beverley, compiler of a Latin chronicle covering the history of Britain from its supposed foundation by Brutus down to the time of Henry I. From the late Middle Ages until the eighteenth century Alfred enjoyed a considerable reputation amongst chroniclers, antiquaries and topographers but by the mid-nineteenth century scholarly opinion had come to consider his work highly derivative, uninformative and of little historical value. The chronicle was printed by Thomas Hearne in 1716, but was never edited in the Rolls Series and the text has remained largely neglected until today. Alfred’s sources in the chronicle have been identified and his use of them examined. The circumstances and date of compilation have been reconsidered and supported by internal evidence from the text, a date of compilation of c.1148 - c.1151 x 1154 is proposed. Alfred’s purpose and intended audience of the work has been considered and evidence for the work’s dissemination and reception from the twelfth to the seventeenth century has been gathered in order to assess the place of the work in medieval historiography. This study finds the Historia to be a text of considerable historical interest and value. It shares common features with historical narratives of the first half of the twelfth century in attempting to provide a comprehensive account of the island’s past, but does so in a more concise, less discursive literary manner. It reveals the application of the methodologies of scholastic exegesis to the writing of history, in its language, textual organization and in the interrogation of authorities that it engages in to determine the veracity of historical data.The text is an important witness for the dissemination of the important twelfth-century source texts it uses. It is the first Latin chronicle to incorporate Geoffrey of Monmouth’s British history into its narrative fabric (Henry of Huntingdon’s c.1139 abbreviation of Geoffrey’s history was inserted as a self-standing ‘Letter to Warinus’). Alfred’s critical reception of the Galfridian material is examined in the thesis. The extensive borrowings from Henry of Huntingdon, Geoffrey of Monmouth, John of Worcester and the Durham Historia Regum, provide important evidence for the dissemination of these texts, which the thesis examines. A finding of the study is that the Historia has been powerfully influenced by Henry of Huntingdon’s Historia Anglorum in its structure and thematic approach. The later reception of Alfred’s Historia by Ranulph Higden in his Universal Chronicle Polychronicon is examined and the impact that this had on Alfred’s later reception in historiography, from William Caxton to William Camden is traced and explored

Recent Decisions

Comments on recent decisions by L. D. Wichmann, Lawrence James Bradley, John F. Beggan, John A. Slevin, Robert P. Mone, and F. James Kane

In vivo quantification of embryonic and placental growth during gestation in mice using micro-ultrasound

<p>Abstract</p> <p>Background</p> <p>Non-invasive micro-ultrasound was evaluated as a method to quantify intrauterine growth phenotypes in mice. Improved methods are required to accelerate research using genetically-altered mice to investigate the interactive roles of genes and environments on embryonic and placental growth. We determined (1) feasible age ranges for measuring specific variables, (2) normative growth curves, (3) accuracy of ultrasound measurements in comparison with light microscopy, and (4) weight prediction equations using regression analysis for CD-1 mice and evaluated their accuracy when applied to other mouse strains.</p> <p>Methods</p> <p>We used 30–40 MHz ultrasound to quantify embryonic and placental morphometry in isoflurane-anesthetized pregnant CD-1 mice from embryonic day 7.5 (E7.5) to E18.5 (full-term), and for C57Bl/6J, B6CBAF1, and hIGFBP1 pregnant transgenic mice at E17.5.</p> <p>Results</p> <p>Gestational sac dimension provided the earliest measure of conceptus size. Sac dimension derived using regression analysis increased from 0.84 mm at E7.5 to 6.44 mm at E11.5 when it was discontinued. The earliest measurement of embryo size was crown-rump length (CRL) which increased from 1.88 mm at E8.5 to 16.22 mm at E16.5 after which it exceeded the field of view. From E10.5 to E18.5 (full term), progressive increases were observed in embryonic biparietal diameter (BPD) (0.79 mm to 7.55 mm at E18.5), abdominal circumference (AC) (4.91 mm to 26.56 mm), and eye lens diameter (0.20 mm to 0.93 mm). Ossified femur length was measureable from E15.5 (1.06 mm) and increased linearly to 2.23 mm at E18.5. In contrast, placental diameter (PD) and placental thickness (PT) increased from E10.5 to E14.5 then remained constant to term in accord with placental weight. Ultrasound and light microscopy measurements agreed with no significant bias and a discrepancy of less than 25%. Regression equations predicting gestational age from individual variables, and embryonic weight (BW) from CRL, BPD, and AC were obtained. The prediction equation BW = -0.757 + 0.0453 (CRL) + 0.0334 (AC) derived from CD-1 data predicted embryonic weights at E17.5 in three other strains of mice with a mean discrepancy of less than 16%.</p> <p>Conclusion</p> <p>Micro-ultrasound provides a feasible tool for in vivo morphometric quantification of embryonic and placental growth parameters in mice and for estimation of embryonic gestational age and/or body weight in utero.</p