T.C. Claypole

Ultrafast near-infrared sintering of a slot-die coated nano-silver conducting ink

Drying and sintering conductive inks for plastic electronics currently limits the rate of their roll-to-roll manufacture. Near infrared radiation is demonstrated to drastically reduce this process time, achieving conduction under 0.03 Ω per □ in 2 seconds compared to conventional hot-air oven (600 seconds) and infrared methods (84 seconds).

Machine learning methods on exhaled volatile organic compounds for distinguishing COPD patients from healthy controls

Exhaled volatile organic compounds (VOCs) have shown promise in diagnosing chronic obstructive pulmonary disease (COPD) but studies have been limited by small sample size and potential confounders. An investigation was conducted in order to establish whether combinations of VOCs could identify COPD patients from age and BMI matched controls. Breath samples were collected from 119 stable COPD patients and 63 healthy controls. The samples were collected with a portable apparatus, and then assayed by gas chromatography and mass spectroscopy. Machine learning approaches were applied to the data and the automatically generated models were assessed using classification accuracy and receiver operating characteristic (ROC) curves. Cross-validation of the combinations correctly predicted the diagnosis in 79% of COPD patients and 64% of controls and an optimum area under the ROC curve of 0.82 was obtained. Comparison of current and ex smokers within the COPD group showed that smoking status was likely to affect the classification; with correct prediction of smoking status in 85% of COPD subjects. When current smokers were omitted from the analysis, prediction of COPD was similar at 78% but correct prediction of controls was increased to 74%. Applying different analytical methods to the largest group of subjects so far, suggests VOC analysis holds promise for diagnosing COPD but smoking status needs to be balanced.

An Investigation into plate deformation in flexographic printing

Abstract Deformation of the flexographic printing plate is an important factor in determining the quality of the printed image. A numerical model of the individual dots has been developed and used to examine the deformation of the plate under a range of printing conditions and image characteristics. Two mechanisms have been identified for the deformation of the image on the plate: expansion of the dot surface and dot barrelling. These results have been combined with those from an experimental study to apportion the dot gain due to ink spreading and physical deformation of the dot. The results have shown the low-coverage dots at high line rulings to be particularly affected by the effect of variation in the impression pressure. This has significant implications for the ability of the process to reproduce high-resolution images that combine both highlight and shadow regions successfully and consistently. Ink spreading has been identified as the major cause of dot gain, except at low coverages, where the deformation of the dots makes a significant contribution.

Comparison of the antibacterial activity of essential oils and extracts of medicinal and culinary herbs to investigate potential new treatments for irritable bowel syndrome

BackgroundIrritable bowel syndrome (IBS) is a common functional gastrointestinal disorder, which may result from alteration of the gastrointestinal microbiota following gastrointestinal infection, or with intestinal dysbiosis or small intestinal bacterial overgrowth. This may be treated with antibiotics, but there is concern that widespread antibiotic use might lead to antibiotic resistance. Some herbal medicines have been shown to be beneficial, but their mechanism(s) of action remain incompletely understood. To try to understand whether antibacterial properties might be involved in the efficacy of these herbal medicines, and to investigate potential new treatments for IBS, we have conducted a preliminary study in vitro to compare the antibacterial activity of the essential oils of culinary and medicinal herbs against the bacterium, Esherichia coli.MethodsEssential oils were tested for their ability to inhibit E. coli growth in disc diffusion assays and in liquid culture, and to kill E. coli in a zone of clearance assay. Extracts of coriander, lemon balm and spearmint leaves were tested for their antibacterial activity in the disc diffusion assay. Disc diffusion and zone of clearance assays were analysed by two-tailed t tests whereas ANOVA was performed for the turbidometric assays.ResultsMost of the oils exhibited antibacterial activity in all three assays, however peppermint, lemon balm and coriander seed oils were most potent, with peppermint and coriander seed oils being more potent than the antibiotic rifaximin in the disc diffusion assay. The compounds present in these oils were identified by gas chromatography mass spectrometry. Finally, extracts were made of spearmint, lemon balm and coriander leaves with various solvents and these were tested for their antibacterial activity against E. coli in the disc diffusion assay. In each case, extracts made with ethanol and methanol exhibited potent antibacterial activity.ConclusionsMany of the essential oils had antibacterial activity in the three assays, suggesting that they would be good candidates for testing in clinical trials. The observed antibacterial activity of ethanolic extracts of coriander, lemon balm and spearmint leaves suggests a mechanistic explanation for the efficacy of a mixture of coriander, lemon balm and mint extracts against IBS in a published clinical trial.

3-D Printing

3-D printing is the process by which a 3-D digital design is converted into a component by depositing material using additive processing. As a process, components are made layer by layer from a range of materials that are available in liquid resin, filament, and fine powder form. As a result, a range of different metals, plastics, and composite materials can be used to make 3-D printable objects. 3-D printing is a rapidly evolving technology consisting of many different methods for the fabrication of a new generation of advanced components and structures. The most important aspect of this technology is that due to its additive nature it is a sustainable, scalable, and a viable future manufacturing method. Currently, research focuses on making complex components from a range of innovative and functional materials. These are being used to make new machines and functioning devices.

A finite element investigation into a soft rolling contact supplied by a non-Newtonian ink

A study of numerical modelling and experiments of a soft rolling nip contact is described. A power law equation was found to be adequate in modelling the positive pressure zone in the nip, but was not capable of describing the film rupture pressure adequately. The index and exponent in the power law were noted to affect nip behaviour significantly and similarly. A shear rate cut-off model was used successfully to avoid singularity in the viscosity field at the mid-thickness and was found not to affect the behaviour in the nip significantly.

Short-Term Intra-Subject Variation in Exhaled Volatile Organic Compounds (VOCs) in COPD Patients and Healthy Controls and Its Effect on Disease Classification

Exhaled volatile organic compounds (VOCs) are of interest for their potential to diagnose disease non-invasively. However, most breath VOC studies have analyzed single breath samples from an individual and assumed them to be wholly consistent representative of the person. This provided the motivation for an investigation of the variability of breath profiles when three breath samples are taken over a short time period (two minute intervals between samples) for 118 stable patients with Chronic Obstructive Pulmonary Disease (COPD) and 63 healthy controls and analyzed by gas chromatography and mass spectroscopy (GC/MS). The extent of the variation in VOC levels differed between COPD and healthy subjects and the patterns of variation differed for isoprene versus the bulk of other VOCs. In addition, machine learning approaches were applied to the breath data to establish whether these samples differed in their ability to discriminate COPD from healthy states and whether aggregation of multiple samples, into single data sets, could offer improved discrimination. The three breath samples gave similar classification accuracy to one another when evaluated separately (66.5% to 68.3% subjects classified correctly depending on the breath repetition used). Combining multiple breath samples into single data sets gave better discrimination (73.4% subjects classified correctly). Although accuracy is not sufficient for COPD diagnosis in a clinical setting, enhanced sampling and analysis may improve accuracy further. Variability in samples, and short-term effects of practice or exertion, need to be considered in any breath testing program to improve reliability and optimize discrimination.

Patterning of antibodies using flexographic printing

Antibodies were patterned onto flexible plastic films using the flexographic printing process. An ink formulation was developed using high molecular weight polyvinyl alcohol in carbonate-bicarbonate buffer. In order to aid both antibody adhesion and the quality of definition in the printed features, a nitrocellulose coating was developed that was capable of being discretely patterned, thus increasing the signal-to-noise ratio of an antibody array. Printing antibody features such as dots, squares, text, and fine lines were reproduced effectively. Furthermore, this process could be easily adapted for printing of other biological materials, including, but not limited to, enzymes, DNA, proteins, aptamers, and cells.

The effect of exposure to inks and solvents on squeegee performance

SummariesThe squeegee in screen printing forces ink into the screen and the screen into contact with the substrate. The squeegee, which is manufactured from polyurethane, has a major influence on screen printing quality. This paper summarises an experimental programme into the durability of squeegees when exposed to inks and solvents. The softer the squeegee the more il was affected by exposure to any ink or solvent with the increases in mass of up to 14%, increases in volume of up to 12%, and reductions in elastic modulus of up to 80%. The low boiling point cleaner and solvent ink had the greatest effect of all the liquids tested. Distortion of the samples during solvent absorption caused small errors in the measurement of the volume and elastic modulus of the samples. The measurement in the increase in mass of the sample provided the most reliable method for estimating any ink/squeegee compatibility problems. Relaxation in the air returned the squeegee to its original mass. No clear relationship could be established between the surface roughness of the sample and the change in squeegee properties.Exposure to ultraviolet (UV) ink increased the mass of the sample with time. Unlike exposure to solvent-based inks, the effect of UV exposure was cumulative with relaxation between exposures doing little to reduce the mass of the squeegee. Relaxation of the squeegee over a two-week period of time under room temperature conditions did little to reduce the mass back to its original level. A printing experiment with an ‘inked’ and new squeegee showed that a two-hour exposure caused a hard squeegee to act like a medium and resulted in a 0.05 increase in printed density. Finite element modelling of a ‘compound’ squeegee showed that the change in modulus had a significant effect on the deformation of the squeegee tip.RésuméDans le cadre de la sérigraphie c’est le squeegee qui force l’encre à pénétrer la claie et la claie à entrer en contact avec le substrat. Le squeegee, qui est fabriqué de polyuréthane, a une influence majeure sur la qualité des impressions sérigraphiques. Cet article résume un programme expérimental conçu pour examiner la durabilité des squeegees quand ils sont exposés aux encres et aux solvants. Plus le squeegee était souple plus il était affecté par son exposition à n’importe quel encre ou solvant, avec des accroissements de la masse de jusqu’à 14%, des accroissements du volume de jusqu’à 12% et des diminutions du module élastique de jusqu’à 80%. Parmi toutes le liquides testées, l’encre au solvant et le produit de nettoyage à point d’ébullition bas avaient le plus grand effet. La déformation des échantillons pendant l’absorption des solvants a causé de petites erreurs en ce qui concerne la mesure du volume et du module élastique des échantillons. La mesure de l’accroissement de la masse de l’échantillon représentait la méthode la plus fiable d’évaluer des problèmes dans le domaine de la compatibilité squeegee/encre. Une diminution [de la pression] de l’air a restitué le squeegee à sa masse originale. On ne pouvait pas établir un clair rapport entre la rugosité de la surface de l’échantillon et les variations des propriétés du squeegee.Au fil du temps, l’exposition à l ’encre UV a augmenté la masse de l’échantillon. Contrairement au cas de l’exposition aux encres au solvant, l’effet de l’exposition UV était cumulatit et les relâchements entre expositions n’ont pas fait grand-chose pour réduire la masse du squeegee. L’inactivité du squeegee pendant une période de deux semaines à température ambiante n’a pas fait grand-chose pour réduire la masse à son niveau original. Une expérience d’impression avec un squeegee enduit d’encre et un squeegee neut a démontré qu’une exposition de deux heures a provoqué un squeegee dur à agir en tant que médium et a abouti à un accroissement de la densité d’impression de 0.05. Le modelage par élément fini d’un squeegee composé a montré que le tait de changer le module a eu un effet signifiant sur la détormation du bout du squeegee.ZusammenfassungDer Rakel wird im Siebdruck eingesetzt, um Tinten und Farben in den Sieb, und den Sieb in Kontakt mit dem Substrat zu bringen. Der polyurethanrakel hat einen grossen Einfluß auf die Druckqualität. Diese Arbeit faßt ein experimentelles Programm zusammen, die Haltbarkeit des Rakels under Aussetzung zu Lösungsmitteln und Druckfarben zu bewerten. Je weicher der Rakel, desto stärker wurde er von Druckfarben und Lösungsmitteln angegriffen, mit dem Effekt daß die Masse des Rakels um bis zu 14% zunahm, das Volumen um 12% zunahm, und die Elastizität um bis zu 80% abnahm. Der leicht flüchtige Reiniger und lösungsmittelreiche Farben hatten den größten Effekt. Die Distortion der Proben durch Lösungsmitteladsorption verursachte kleine Fehler bei der Messung des Volumens und der Elastizität der Proben. Die Gewichtszunahme stellte sich als die zuverlässigste Methode heraus, Inkompatibilitätsprobleme zwischen Rakel und Farben vorherzusagen. Nach einiger Zeit and der frischen Luff kehrte der Rakel zu seinem Originalgewicht zurück. Wir stellten keine klare Verbindung zwischen der Oberflächenaufrauhung der Rakelprobe und der Veränderungen der Rakeleigenschaften fest.UV-Druckfarben hatten auch den Effekt, mit der Zeit das Gewicht des Rakels zu erhöhen. Im Gegensatz zu lösungsmittelhaltigen Farben war der UV-Effekt kummulativ, und Zeit an der Frischluff hatte kaum einen Effekt auf das Rakelgewicht, selbst über einen Zeitraum von zwei Wochen bei Raumtemperatur. Ein Druckexperiment, einen von Farben angegriffenen Rakel mit einem neuen Rakel zu vergleichen, zeigte, daß sich das angegriffene Rakel nach zwei Stunden Druckzeit wie ein Medium verhält und die Druckdichte um 0.05 erhöht. Ein finites Elementmodell eines “compound” Rakels zeigte daß die Veränderung des Modulus einen deutlichen Effekt auf die Deformierung der Rakelspitze hatte.

Viscosity control in the screen printing of ceramic transfers

SummariesThis paper describes an experimental investigation into process parameter effects and viscosity variation on colour control in the printing of ceramic transfers. This has been achieved through the completion of controlled experiments and monitoring of a commercial production run. The findings indicate that process parameter adjustments have only a small impact on print quality, the most dominant term being ink viscosity variation through solvent evaporation. Through determination of the dependence of colour change on viscosity change, coupled with the dependence of viscosity on solvent addition, it has been possible to establish a strategy for solvent addition. This was found to be most sensitive at low solvent addition levels and this identifies the need for close viscosity control to ensure consistent colour quality. The methodology that has been established in this work is also applicable to other ink systems where significant carrier loss is experienced during a printing run.RésuméCet article décrit une enquête expérimentale sur les effets des paramètres de procédé et des variations de viscosité, sur le contrôle de la couleur dans le domaine des décalcomanies pour céramiques. Ce but a été atteint grace à la réalisation des expériences contrôlés et à la surveillance de l’opération d’une chaîne de fabricatiion commerciale. Les résultats indiquent que les ajustements des paramètres de procédé n’ont que peu d’ influence sur la qualité de l’impression. L’élément qui a le plus grand impact est la variation de viscosité due à l’évaporation du solvant. Grace à la détermination du fait que le changement de la couleur dépendait de la variation de viscosité et que la viscosité dépendait de l’addition du solvant, il fut possible d’établir une stratégie vis à vis de l’addition du solvant. Il a été trouvé que cette stratégie était au plus sensible quand les niveaux du solvant étaient bas. Cela indique le besoin de bien contrôler la viscosité afin d’assurer une qualité de couleur qui soit invariable. La méthodologie qui a été étabolie au cours de ce travail a des applications dans le cadre d’autres systèmes d’encre où il y a des pertes notables de l’élément porteur de l’encre pendant un tirage.ZusammenfassungDiese Arbeit beschäftigt sich mit der experimenteller Erforschung des Effekts verschiedener in Prozessparameter und Viskositäten auf die Farbkontrolle beim Drucken von keramischen Transfers. Dieses wurde erreicht durch ein kontrolliertes Experiment und durch die Beobachtung eines kommerziellen Produktionsdurchlaufes. Unsere Ergebnisse zeigen, daß die Veränderung der Prozeßparameter nur einen geringen Einfluß auf die Druckqualität hat. Ein wesentlich größeren Einfluß hatte die Veränderung der Farbviskosität durch die Verdunstung des Lösungsmittels. Wir ermittelten wie die Farbveränderung von der Viskosität abhängt, und wie wiederrum die Viskosität von der Zugabe von Lösungsmitteln abhängt. So gelang es uns, eine Strategie für die korrekte Beigabe von Lösungsmitteln zu entwickeln. Wir fanden daß die Viskositätskontrolle bei geringem Lösungsmittelzusatz besonders empfindlich war, das heißt daß die Viskosität besonders gut kontrolliert werden muß um eine gleichbleibende Farbqualität zu erreichen. Diese Methode kann auch in anderen Drucksystemen verwendet werden, wo ein deutlicher Verlust des Farbträgers während des Druckvorganges zu erwarten ist.