Scaling relations for magnetic nanoparticles

A detailed investigation of the scaling relations recently proposed by [J. d'Albuquerque e Castro, D. Altbir, J. C. Retamal, and P. Vargas, Phys. Rev. Lett. 88, 237202 (2002)] to study the magnetic properties of nanoparticles is presented. Analytical expressions for the total energy of three characteristic internal configurations of the particles are obtained, in terms of which the behavior of the magnetic phase diagram for those particles upon scaling of the exchange interaction is discussed. The exponent $\eta$ in scaling relations is shown to be dependent on the geometry of the vortex core, and results for specific cases are presented.Comment: 6 pages, 4 figure

Structural modelling of medieval walls

International Seminar on Structural Analysis of Historical Constructions (3º 2001 Guimaraens)Sistemas constructivos medievales a menudo involucrados la construcción de múltiples capas paredes formadas por dos caras de sillería o mampostería con un relleno central que consiste en escombros ligada con mortero, generalmente cal-basado. Se trata de una construcción simple y eficiente sistema que se siguió utilizando en los siglos posteriores. Sin embargo, el modelado estructural de este tipo de pared no es fácil de lograr. Los dos pared caras no están vinculados rígidamente y, por otro lado, las bóvedas son normalmente compatibles sólo en el la cara interna, lo que resulta en la eficiencia reducida de la unidad de pared. Modelos comunes de elementos finitos no son capaces de resolver muchos de los problemas que surgen cuando se aplican a una monumental construcción. En este trabajo se aborda el problema y propone varias posibilidades de solución con diferentes tipos de elementos .. También proporciona dos ejemplos de monumentos góticos en Galicia (España) en el que comportamiento estructural se ha estudiado el uso de algunos de estos modelos de cálculo: las iglesias de Guimaraens y Cambados.[Abstract]Medieval construction systems usually involved the construction of multi-layer walls formed by two faces of ashlar work or masonry with a central infilling consisting of rubble bound with mortar, generally lime-based. It is a simple and efficient construction system which continued to be used in subsequent centuries. Nevertheless, structural modelling of this type of wall is not easy to achieve. The two wall faces are not rigidly bound and on the other hand, vaults are normally supported only on the intemal face, resulting in reduced efficiency of the wall unit. Common models of finite elements are unable to solve many of the problems that arise when they are applied to a monumental construction. This paper tackles the problem and puts forward various possibilities of solution with different element types.. It also provides two examples of Gothic monuments in Galicia (Spain) in which structural behaviour was studied using some of these calculation models: the churches of Guimarei and Cambados

Clean-in-place monitoring of different food fouling materials using ultrasonic measurements

Clean-in-Place is an autonomous technique used to clean the internal surfaces of processing equipment in thefood and drink sector. However, these systems clean for a longer time than required with negative economic andenvironmental impacts. In this work, an ultrasonic sensor system was developed to monitor the cleaning ofdifferent food fouling materials at laboratory scale. The fouling removal of three different food materials wasalso studied at different cleaning fluid temperatures. The three food materials had different cleaning mechanisms,which could be monitored successfully with the ultrasonic system. Tomato paste and gravy appeared to becleaned by mechanical forces whereas malt extract dissolved into the cleaning water. The results yielded fromthe cleaning of the malt was found to be repeatable whereas the tomato and gravy were more variable betweenrepeat experiments. It was found that changes in recorded ultrasonic signals were mainly affected by the area offouling that covered the transducer's active element

Surviving anoxia in marine sediments: The metabolic response of ubiquitous benthic foraminifera (Ammonia tepida)

High input of organic carbon and/or slowly renewing bottom waters frequently create periods with low dissolved oxygen concentrations on continental shelves and in coastal areas; such events can have strong impacts on benthic ecosystems. Among the meiofauna living in these environments, benthic foraminifera are often the most tolerant to low oxygen levels. Indeed, some species are able to survive complete anoxia for weeks to months. One known mechanism for this, observed in several species, is denitrification. For other species, a state of highly reduced metabolism, essentially a state of dormancy, has been proposed but never demonstrated. Here, we combined a 4 weeks feeding experiment, using 13C-enriched diatom biofilm, with correlated TEM and NanoSIMS imaging, plus bulk analysis of concentration and stable carbon isotopic composition of total organic matter and individual fatty acids, to study metabolic differences in the intertidal species Ammonia tepida exposed to oxic and anoxic conditions. Strongly contrasting cellular-level dynamics of ingestion and transfer of the ingested biofilm components were observed between the two conditions. Under oxic conditions, within a few days, intact diatoms were ingested, degraded, and their components assimilated, in part for biosynthesis of different cellular components: 13C-labeled lipid droplets formed after a few days and were subsequently lost (partially) through respiration. In contrast, in anoxia, fewer diatoms were initially ingested and these were not assimilated or metabolized further, but remained visible within the foraminiferal cytoplasm even after 4 weeks. Under oxic conditions, compound specific 13C analyses showed substantial de novo synthesis by the foraminifera of specific polyunsaturated fatty acids (PUFAs), such as 20:4(n-6). Very limited PUFA synthesis was observed under anoxia. Together, our results show that anoxia induced a greatly reduced rate of heterotrophic metabolism in Ammonia tepida on a time scale of less than 24 hours, these observations are consistent with a state of dormancy

Intelligent Resource Use to Deliver Waste Valorisation and Process Resilience in Manufacturing Environments

© 2020 Johnson Matthey Circular economy (CE) thinking has emerged as a route to sustainable manufacture, with related cradle-to-cradle implications requiring implementation from the design stage. The challenge lies in moving manufacturing environments away from the traditional linear economy paradigm, where materials, energy and water have often been designed to move out of the system and into receivership of waste management bodies after use. Recent applications of industrial digital technologies (IDTs: for example internet of things, data-driven modelling, cyber-physical systems, cloud manufacturing, cognitive computing) to manufacturing may be instrumental in transforming manufacturing from linear to circular. However, although IDTs and CE have been the focus of intensive research, there is currently limited research exploring the relationship between IDTs and the CE and how the former may drive the implementation of CE. This article aims to close the knowledge gap by exploring how an IDT (data-driven modelling) may facilitate and advance CE principles within process manufacturing systems, specifically waste valorisation and process resilience. These applications are then demonstrated through two real-world manufacturing case studies: (a) minimising resource consumption of industrial cleaning processes and (b) transforming wastewater treatment plants (WWTPs) into manufacturing centres

Ultrasonic Measurements and Machine Learning for Monitoring the Removal of Surface Fouling during Clean-in-Place Processes

Cleaning is an essential operation in the food and drink manufacturing sector, although it comes with significant economic and environmental costs. Cleaning is generally performed using autonomous Clean-in-Place (CIP) processes, which often over-clean, as suitable technologies do not exist to determine when fouling has been removed from the internal surfaces of processing equipment. This research combines ultrasonic measurements and machine learning methods to determine when fouling has been removed from a test section of pipework for a range of different food materials. The results show that the proposed methodology is successful in predicting when fouling is present on the test section with accuracies up to 99% for the range of different machine learning algorithms studied. Various aspects relating to the training data set and input data selection were studied to determine their effect on the performance of the different machine learning methods studied. It was found that the classification models performed better when data points were extracted directly from the ultrasonic waves and when data sets were combined for different fouling materials

Magnetic behavior of nanoparticles in patterned thin films

The magnetic behavior of truncated conical nanoparticles in patterned thin films is investigated as a function of their size and shape. Using a scaling technique, phase diagrams giving the relative stability of characteristic internal magnetic structures of the particles are obtained. The role of the uniaxial anisotropy in determining the magnetic properties of such systems is discussed, and a simple method for stablishing its strength is proposed.Comment: 4 pages, 4 figure

Regioisomerism in cationic sulfonyl-substituted [Ir(C^N)2(N^N)]+ complexes: its influence on photophysical properties and LEC performance

In a series of regioisomeric [Ir(C^N) 2 (bpy)] + complexes containing methylsulfonyl groups on the cyclometallating ligands, the influence of the substitution position on photophysical, electrochemical and LEC device properties is investigated