A Novel TiO2 / PVC Layer for Use in a Photoelectrochemical Cell

A novel method of coating titanium dioxide on a glassy carbon electrode as a polyvinylchloride composite , is described. On illumination , there is an enhanced voltammetric current at this TiO2/PVC composite in aqueous formic acid solution. This electrode is used as the basis of a formic acid fuel cell where oxygen is reduced at a platinum cathode. The system yields 100 cm-2 for 0.01 mol dm-3 HCOOH in 0.1 mol dm-3 NaOH under illumination from a 150 W xenon lamp. The current without illumination is 0.5 cm-2

A simple microcalorimetry system to determine the adsorption behaviour of acids in large adhesive bond gaps using base-initiated solution polymerisation of ethyl-2-cyanoacrylate

This work presents the use of a simple microcalorimetry cyanoacrylate (CA) polymerisation system for investigating aspects of CA adhesive cure through gap and adsorption of adhesive acid stabiliser by a range of metal and glass substrates. It is well established that strong acid induced inhibition periods (IPs) are almost directly proportional to the acid concentration in weak base initiated polymerisations of alkyl CAs in tetrahydrofuran (THF). Ethyl cyanoacrylate (ECA) polymerisation IP measurements were used to determine the adsorption of methanesulfonic acid (MSA) in THF or ECA solutions by a range of metal, glass and polypropylene (PP) lap shears surfaces. The extent of substrate acid sorption was found to decrease in the order: Copper- zinc alloy (C23000) \u3e grit blasted mild steel \u3e aluminium alloy 2024T3 \u3e mild steel \u3e glass \u3e aluminium \u3e stainless steel alloy 304 \u3e PP. Differences in the extent of acid sorption were accounted for in terms of two effects: surface acidity/basicity and surface area (roughness). The decrease in MSA concentration following lap shear immersion in an MSA solution was related to the reactivity of the substrates for catalysing bond line polymerisations as described in a recently reported confocal Raman spectroscopic study of ECA /substrate reactivity

Use of Confocal Raman Microscopy to Characterise Ethyl Cyanoacrylate Adhesive Depth Curing

In situ spatial temporal measurement of monomer conversion during adhesive bondline curing remains a challenging area. The aim of this work was to demonstrate the effectiveness of using confocal Raman microscopy in a specially configured experimental set-up, as a versatile tool for measuring monomer concentration changes as a function of both time and adhesive bond depth during ethyl cyanoacrylate polymerisation. This also allowed monitoring of the extent of polymerisation at the adhesive substrate interface independently of the bulk bondline polymerisation region. Key kinetic parameters such as inhibition time tlag, rate of reaction Rmax and extent of reaction [at]max were obtained by fitting the experimental data to sigmoidal growth curves using simple piecewise regression models. A systematic characterisation of a polymerisation reaction was conducted using different sample substrate types (copper alloy (red brass), aluminium, aluminium alloy, stainless steel and borosilicate glass) and at various reaction temperatures. Reaction rates were found to decrease further away from the substrate interface in the bulk volume region. The fastest kinetics occurred in the vicinity of nucleophilic hydroxyl rich surfaces such as at the copper alloy (red brass). In addition to substrate surface chemistry, surface roughness was also a factor, with the highest reaction rates occurring with a grit blasted (roughened) aluminium alloy (2024 T3) surface. An approximately linear dependence of the ln Rmax vs. 1/T (Arrhenius) plot was recorded within the temperature range of 291–328 K. A better fit was obtained however through the use of two separate linear slopes, possibly indicative of a change of polymerisation reaction mechanism taking place at elevated temperatures with two distinct activation energies. Further work conducted using a larger number of temperatures would be useful to verify this finding. This work confirmed that differences in the rates of interfacial and bulk polymerisation processes could be readily measured in situ using confocal Raman microscopy which is a powerful technique for investigating such surface-confined and bulk polymerisation reaction

Analysis of copper(II) using the ascorbate/oxygen system – a valuable undergraduate resource

In deionised water, ascorbic acid (AH−), through oxidation by oxygen in the presence of copper(II), was found to degrade with zero-order kinetics. The magnitude of the reaction rate varied directly with the copper(II) concentration. At a higher pH (7.4), the same reaction was found to be pseudo-first order. Once again, the magnitude of the rate increased linearly with copper(II) concentration at a micromolar level. Dissolved oxygen levels, in excess AH− and trace copper(II), displayed similar kinetics under both conditions. Monitoring of either AH− levels or dissolved oxygen concentration was found to be a useful novel undergraduate practical laboratory for trace copper(II) determination. Students can measure the kinetics for standards and their unknown copper solution and quantitate the unknown copper

La co-conception pour engager collègues et étudiants dans les pédagogies actives en physique

Affiche présentée dans le cadre du colloque de l'ARC «Favoriser l’accès et le partage par la création d’un observatoire» lors du 86e Congrès de l'Acfas à l' Université du Québec à Chicoutimi (UQAC), les 7 et 8 mai 2018.La pédagogie active (PA) améliore nettement l’apprentissage des élèves. Cependant, plusieurs professeurs ont de la difficulté à la mettre en oeuvre efficacement. Sans persévérance ou conseils, ils se découragent et reviennent à un style d'enseignement plus traditionnel. Nous présentons comment la co-conception d'activités a permis l’engagement d’un plus grand nombre de professeurs dans la mise en oeuvre de la PA. La co-conception d'activités fait référence à la collaboration entre chercheurs en pédagogie et professeurs dans la conception de nouvelles PA. L’objectif est de maximiser l'engagement et l'apprentissage des étudiants, tout en considérant l’importance de la préparation et de la réflexion à l'apprentissage. Des activités en plusieurs étapes (avant, pendant et après le cours) ont été développées. Elles utilisent les plateformes numériques, l'enseignement par les pairs et l’approche de classe inversée. Nous avons observé 9 professeurs de physique (15 groupes d’environ 25-30 étudiants) à plusieurs reprises. Les données qualitatives démontrent l’adaptabilité des activités : les professeurs enseignant dans différentes salles de cours (traditionnelles ou interactives) ainsi que ceux qui souhaitent utiliser moins de technologies numériques peuvent tout autant accomplir les activités. Nous comparons les différentes mises en oeuvre utilisées par les professeurs lors de l’exécution de ces nouvelles activités et nous examinons l'évolution des réalisations étudiantes

Adsorption of 5-Fluorouracil on Au(111) and Cu(111) surfaces

The adsorption of 5-Fluorouracil (5FU) on Au(111) and Cu(111) surfaces as a function of molecular coverage and temperature has been studied, using x-ray photoelectron spectroscopy (XPS) and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy. The nature of 5-Fluorouracil bonding with the two substrates is remarkably different. The Cu substrate forms a chemisorbed complex with 5-FU while the Au substrate shows only physisorption. NEXAFS data at the C, N and O K-edge show a strong angular dependence, indicating that 5-FU lies nearly parallel on the inert Au(111) surface, and at a steep angle on the Cu(111) surface. 5-FU is a biomolecule used for cancer treatment and the results are relevant for those using metal surfaces to prepare 5-FU for applications such as drug delivery.The adsorption of 5-Fluorouracil (5FU) on Au(111) and Cu(111) surfaces as a function of molecular coverage and temperature has been studied, using x-ray photoelectron spectroscopy (XPS) and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy. The nature of 5-Fluorouracil bonding with the two substrates is remarkably different. The Cu substrate forms a chemisorbed complex with 5-FU while the Au substrate shows only physisorption. NEXAFS data at the C, N and O K-edge show a strong angular dependence, indicating that 5-FU lies nearly parallel on the inert Au(111) surface, and at a steep angle on the Cu(111) surface. 5-FU is a biomolecule used for cancer treatment and the results are relevant for those using metal surfaces to prepare 5-FU for applications such as drug delivery

A national-scale high-resolution runoff risk and channel network mapping workflow for diffuse pollution management

Managing diffuse pollution from agricultural land requires a spatially explicit risk assessment that can be applied over large areas. Major components of such assessments are the precise definition of both channel networks that often originate as small channels and streams, and Hydrologically Sensitive Areas (HSAs) of storm runoff that occur on land surfaces. Challenges relate to regions of complex topography and land use patterns, particularly those which have been heavily modified by arterial drainage. In this study, a national scale, transferrable workflow and analysis were developed using a specifically commissioned LiDAR survey. Research on the first half of Northern Ireland (6927 km2) is reported where field-edge drain to major river channels were mapped from 1 m (16 points per metre) digital terrain models, and in-field HSAs were defined across over 400,000 fields with a median field size of 0.86 ha. Manual drainage mapping supplemented with a novel automated drainage channel correction process resulted in an unparalleled high-resolution national drainage network with 37,320 km of channels, increasing mapped channel density from 0.9 km km−2 to 5.5 km km−2. The HSAs were based on a Soil Topographic Index (STI) system using hillslope and contributing area models combined with soil hydraulic characteristics. In all, 249 km2 of runoff risk HSAs were identified by extracting the top 95th percentile of the modelled STI as the areas with the highest propensity to generate in-field runoff. At field and individual farm scale these targeted risk maps of diffuse pollution were delivered to over 13,000 farmers and form part of the nationwide Soil Nutrient Health Scheme programme

Muddying the waters: Impacts of a bogflow on carbon transport and water quality

Landslides of peat have been recorded throughout Britain and Ireland for centuries. Whilst these events are not uncommon, land degradation can amplify their magnitude and frequency and, crucially, their immediate impacts are rarely documented. A 20,000 m3 bogflow event that occurred on land undergoing development in the Irish border area in November 2020 was monitored at high frequency in the major receiving river system (384 km2). Samples collected every seven hours over a 28 day period at a site 37 km downstream were analysed for suspended sediment (SS), particulate organic carbon (POC) and dissolved organic carbon (DOC and UV-derived fractions), synchronous with hydrometeorological data and turbidity. There was no impact of the bogflow on DOC concentrations or loads. However, concentrations of SS and POC in the first samples after the bogflow were 825 mg/L and 346 mg C/L, respectively, and fish kill was estimated at 100 %. Analysis of detrended SS and POC loads suggested the main impacts of the bogflow on water quality lasted just eight days. Over this period, an additional 1318 t of SS and 608 t of POC were transported as far as the monitoring point, equating to 325 % more SS and 925 % more POC than would have been expected otherwise under the same river flow conditions. The carbon loss and water quality impacts were short lived, but nevertheless severe, and highlight the vulnerability of peatlands and the risks when these environments are inappropriately managed

Distinguishing Tuberculosis from Nontuberculous Mycobacteria Lung Disease, Oregon, USA

To determine whether tuberculosis (TB) and nontuberculous mycobacteria (NTM) infection patients could be distinguished from one another with limited information, we compared pulmonary TB and NTM patients during 2005–2006. Our finding that age, birthplace, and presence of chronic obstructive pulmonary disease could differentiate TB and NTM disease could assist tuberculosis control efforts

Identifying the metabolomic fingerprint of high and low flavonoid consumers

High flavonoid consumption can improve vascular health. Exploring flavonoid–metabolome relationships in population-based settings is challenging, as: (i) there are numerous confounders of the flavonoid–metabolome relationship; and (ii) the set of dependent metabolite variables are inter-related, highly variable and multidimensional. The Metabolite Fingerprint Score has been developed as a means of approaching such data. This study aims to compare its performance with that of more traditional methods, in identifying the metabolomic fingerprint of high and low flavonoid consumers. This study did not aim to identify biomarkers of intake, but rather to explore how systemic metabolism differs in high and low flavonoid consumers. Using liquid chromatography–tandem MS, 174 circulating plasma metabolites were profiled in 584 men and women who had complete flavonoid intake assessment. Participants were randomised to one of two datasets: (a) training dataset, to determine the models for the discrimination variables (n 399); and (b) validation dataset, to test the capacity of the variables to differentiate higher from lower total flavonoid consumers (n 185). The stepwise and full canonical variables did not discriminate in the validation dataset. The Metabolite Fingerprint Score successfully identified a unique pattern of metabolites that discriminated high from low flavonoid consumers in the validation dataset in a multivariate-adjusted setting, and provides insight into the relationship of flavonoids with systemic lipid metabolism. Given increasing use of metabolomics data in dietary association studies, and the difficulty in validating findings using untargeted metabolomics, this paper is of timely importance to the field of nutrition. However, further validation studies are required