Kinetic parameters associated with self-heating of New Zealand coals under adiabatic conditions

Adiabatic self-heating tests were carried out on five New Zealand coal samples ranging in rank from lignite to high-volatile bituminous. Kinetic parameters of oxidation were obtained front the self-heating curves assuming Arrhenius behaviour. The activation energy E (kJ mol(-1)) and the pre-exponential factor A (s(-1)) were determined in the temperature range of 70-140 degreesC. The activation energy exhibited a definite rank relationship with a minimum E of 55 kJ mol(-1) occurring at a Suggate rank of similar to6.2 corresponding to subbituminous C. Either side of this rank there was a noticeable increase in the activation energy indicating lower reactivity of the coal. A similar rank trend was also observed in the R-70 self-heating rate index values that were taken from the initial portion of the self-heating curve front 40 to 70 degreesC. From these results it is clear that the adiabatic method is capable of providing reliable kinetic parameters of coal oxidation.

Desilication of MOR zeolite: Conventional versus microwave assisted heating

MOR zeolites were modified via desilication treatments with NaOH, under conventional and microwave heating. The samples were characterized by powder X-ray diffraction, (27)Al and (29)Si NMR spectroscopy. TEM and N(2) adsorption at -196 degrees C. The acidity of the samples and the space available inside the pores were evaluated through a catalytic model reaction, the isomerization of m-xylene, for which the profiles of the coke thermal decomposition were also analyzed. Powder X-ray diffraction and (29)Si and (27)Al MNR results show that in comparison with conventional heating, microwave irradiation (a less time consuming process) leads to identical amount of Si extraction from the zeolite framework. With this treatment. in addition to the customary mesopores development promoted by conventional heating, a partial conversion of the zeolite microporosity into larger micropores, is observed. The microwave irradiated and conventionally heated samples show different catalytic behavior in the m-xylene isomerization model reaction. It was observed that, by controlling the experimental conditions, it is possible to obtain samples with catalytic properties closer to the parent material, which is also confirmed by the respective coke analysis. (C) 2011 Elsevier B.V. All rights reserved.

Structural, physical, and chemical modifications induced by microwave heating on native agar-like galactans

Native agars from Gracilaria vermiculophylla produced in sustainable aquaculture systems (IMTA) were extracted under conventional (TWE) and microwave (MAE) heating. The optimal extracts from both processes were compared in terms of their properties. The agars’ structure was further investigated through Fourier transform infrared and NMR spectroscopy. Both samples showed a regular structure with an identical backbone, β-D-galactose (G) and 3,6-anhydro-α-L-galactose (LA) units; a considerable degree of methylation was found at C6 of the G units and, to a lesser extent, at C2 of the LA residues. The methylation degree in the G units was lower for MAEopt agar; the sulfate content was also reduced. MAE led to higher agar recoveries with drastic extraction time and solvent volume reductions. Two times lower values of [η] and Mv obtained for the MAEopt sample indicate substantial depolymerization of the polysaccharide backbone; this was reflected in its gelling properties; yet it was clearly appropriate for commercial application in soft-texture food products.

Comparative study about heating systems for pultrusion process

Different heating systems have been used in pultrusion, where the most widely used heaters are planar resistances. The primary objective of this study was to develop an improved heating system and compare its performance with that of a system with planar resistances. In this study, thermography was used to better understand the temperature profile along the die. Finite element analysis was performed to determine the amount of energy consumed by the heating systems. Improvements were made to the die to test the new heating system, and it was found that the new system reduced the setup time and energy consumption by approximately 57%.

Options and Requirements for a potential market entry into Portugal with renewable energy technologies that are applicable for heating and cooling of buildings

NSBE-UNL

Cost-efficient one-part alkali-activated mortars with low global warming potential for floor heating systems applications

Increasing building energy efficiency is one the most cost-effective ways to reduce emissions. The use of thermal insulation materials mitigates heat loss in buildings, therefore minimising heat energy needs. In recent years, several papers were published on the subject of foam alkali-activated cements with enhanced thermal conductivity. However, on those papers cost analysis was strangely avoided. This paper presents experimental results on one-part alkali-activated cements. It also includes global warming potential assessment and cost analysis. Foam one-part alkali-activated cements cost simulations considering two carbon dioxide social costs scenarios are also included. The results show that one-part alkali-activated cements mixtures based on 26%OPC + 58.3%FA + 8%CS + 7.7%CH and 3.5% hydrogen peroxide constitute a promising cost-efficient (67 euro/m3), thermal insulation solution for floor heating systems. This mixture presents a low global warming potential of 443 KgCO2eq/m3. The results confirm that in both carbon dioxide social cost scenarios the mixture 26 OPC + 58.3 FA + 8 CS + 7.7 CH with 3.5% hydrogen peroxide foaming agent is still the most cost efficient.

Production of whey protein-based aggregates under ohmic heating

Formation of whey protein isolate protein aggregates under the influence of moderate electric fields upon ohmic heating (OH) has been monitored through evaluation of molecular protein unfolding, loss of its solubility, and aggregation. To shed more light on the microstructure of the protein aggregates produced by OH, samples were assayed by transmission electron microscopy (TEM). Results show that during early steps of an OH thermal treatment, aggregation of whey proteins can be reduced with a concomitant reduction of the heating chargeby reducing the come-up time (CUT) needed to reach a target temperatureand increase of the electric field applied (from 6 to 12 V cm1). Exposure of reactive free thiol groups involved in molecular unfolding of -lactoglobulin (-lg) can be reduced from 10 to 20 %, when a CUT of 10 s is combined with an electric field of 12 V cm1. Kinetic and multivariate analysis evidenced that the presence of an electric field during heating contributes to a change in the amplitude of aggregation, as well as in the shape of the produced aggregates. TEM discloses the appearance of small fibrillar aggregates upon the influence of OH, which have recognized potential in the functionalization of food protein networks. This study demonstrated that OH technology can be used to tailor denaturation and aggregation behavior of whey proteins due to the presence of a constant electric field together with the ability to provide a very fast heating, thus overcoming heat transfer limitations that naturally occur during conventional thermal treatments.

Mejoramiento del comportamiento térmico de sistemas de calentamiento de agua solares termosifónicos hechos con materiales no convencionales y con tanques de almacenamiento verticales y horizontales Performance improvement of solar thermosyphonic systems for water heating made of non conventional materials and using horizontal and vertical storage tanks

El objeto de estudio de este proyecto son los sistemas de calentamiento de agua mediante energía solar que funcionan termosifónicamente. En particular se tratará con dos diseños particulares generados por fabricantes de la Provincia de Córdoba y que han solicitado el asesoramiento del Grupo de Energía Solar (GES) para el mejoramiento de la performance térmica de dichos equipos. Se trata de dos sistemas que tienen materiales no tradicionales y se diferencian además por tener una distinta disposición del tanque de almacenamiento: uno es en forma vertical y el otro en forma horizontal. Basados en los resultados de un ensayo bajo norma internacional, donde se detectaron algunas puntos factibles de mejora, se propone en este proyecto el análisis en detalle de los equipos, para lo cual se les debe desarmar completos, para realizar un estudio analítico y experimental de los mismos con el objeto de hacer un planteo teórico-analítico del comportamiento de los mismos, con la implementación de propuestas de mejora y chequeo de los resultados. Se propone entonces como objetivo lograr un mejoramiento de la performance térmica de los citados equipos a partir de un estudio experimental y analítico. Asumiendo esta posibilidad de mejora, se plantea la hipótesis de que es posible representar el funcionamiento de estos equipos mediante modelos físico-matemáticos desarrollados a partir de ecuaciones y correlaciones conocidas y procesos a interpretar mediante resoluciones numéricas y softwares específicos de simulación. De esta manera, se plantea el despieze completo de los equipos para estudiar en detalle su estructura y conexiones internas y a partir de la geometría, dimensiones y propiedades termofísicas de materiales constructivos y fluidos de trabajo, realizar modelos físico-matemáticos que permitan realizar variaciones de propiedades y geometría y así buscar las mejores combinaciones que produzcan equipos más eficientes térmicamente. Los modelos físico-matemáticos serán codificados en lenguajes de alto nivel para poder luego de una validación de los modelos, correr simulaciones en un software de reconocimiento internacional que permite sumar dichos modelos mediante un protocolo de comunicación, haciendo que las poderosas prestaciones del software se puedan aplicar a nuestros modelos. Se complementará el estudio con un análisis exergético para identificar los puntos críticos en que se producen las pérdidas de oportunidad de aprovechar la energía disponible, para así analizar cómo solucionar los problemas en dichos puntos. Los materiales a utilizar serán los propios equipos provistos por los fabricantes, que serán modificados convenientemente para operarlos como prototipos Se espera obtener un conocimiento acabado de los procesos y principios de funcionamiento de los equipos, que permita plantear las mejoras, las cuales se implementarán en los prototipos, realizándose una medición mediante norma igual a la inicial para ver en que magnitud se logran las mejoras esperadas. Se pretende además que las mejoras a implementar, en la etapa de transferencia a las empresas involucradas, redunden no sólo en un beneficio técnico, sino que también los sea desde el punto de vista económico. Para ello se trabajará también sobre los procesos y métodos de fabricación para que los equipos mejorados no sean mas caros que los originales y de ser posible sean aún más económicos, todo esto apuntando a la difusión de la energía solar térmica y poner al alcance de todos estos equipos tan convenientes para la propagación de las energías limpias. El proyecto redundará también en un importante beneficio para el conocimiento de la comunidad científica en general, con el aporte de nuevos resultados en diseños novedosos y con nuevos materiales. Además, la institución se beneficiará con la formación que obtendrán los integrantes del proyecto, muchos de ellos en etapa de realización de sus estudios de posgrado y en una etapa importante de su vida como investigadores. The main goal of this project is the improvement of two thermosyphonic solar water heating systems, made of non conventional materials and with different arrangement of their storage tanks: one is vertical and the other one horizontal. The thermosyphonic systems are provided by manufacturers of the Córdoba Province, who came to the Solar Energy Group (GES) of the National University of Río Cuarto looking for help for the design of their products. In an agreement with these manufacturers, it was proposed this project in order to work analytically and experimentally in order to obtain physical-mathematical models of these two systems, which allow for changes to look by means of simulations the best changes to implement on the equipments for the improvement of their thermal performance. Then, the materials to be used are the proper systems provided by the manufacturers, which will be disarmed to be studied in detail. After the analytical study the proposals of improvement will be implemented in a high level language of programming to perform simulations in the environment of a well-known software for energy simulations (TRNSYS). After the simulations, the best modifications will be physically implemented in the prototypes to perform finally the same normalized test of the beginning and check the magnitude of the implemented improvements. The importance of this project is based on the offer of better systems the companies would make, which would benefit the deployment of the thermal solar energy. Another relevant point is to make the new equipments at the same cost of the previous ones or cheaper, in order to achieve a good deployment of the solar water heating systems; then, the manufacture processes and methods must be studied to obtain not only good technical solutions, but also economical equipments. In addition, this project will contribute to the increasing of the knowledge in the area of thermosyphonic solar systems and the training of postgraduate students.

Local heating of human skin causes hyperemia without mediation by muscarinic cholinergic receptors or prostanoids.

RESUME Les changements locaux de la température à la surface de la peau humaine ont une influence importante sur sa perfusion. La chaleur augmente localement le flux sanguin cutané, mais les mécanismes et les médiateurs de cette réponse (réponse thermique d'hyperémie) sont incomplètement élucidés. Dans la présente étude, nous avons examiné la relation possible entre la réponse thermique d'hyperémie, les récepteurs cholinergiques muscariniques et la production des prostaglandines vasodilatatrices. Chez 13 sujets de sexe masculin en bonne santé âgés entre 20 et 30 ans, une chambre métallique (contenant de l'eau) dont la température peut être contrôlée, a été placée sur la face palmaire de leur avant-bras et utilisée pour augmenter la température de surface de 34 à 41°C. L'hyperémie cutanée consécutive a été enregistrée par l'intermédiaire d'un scanner laser-Doppler. Dans une expérience, chacun des 8 sujets a reçu un bolus i.v. de glycopyrolate (agent antimuscarinique) (4 µg/kg) lors d'une visite et de NaCl 0,9% lors de l'autre visite. La réponse thermique d'hyperémie a été déterminée dans l'heure suivant les injections. Les glycopyrolate a efficacement empêché la vasodilation des micro-vaisseaux cutanés induite par iontophorèse d'acétylcholine mais n'a pas influencé la réponse thermique d'hyperémie. Dans une deuxième expérience entreprise avec 5 autres sujets 1 g d'aspirine (inhibiteur de la cyclooxygénase) administrée oralement a totalement supprimé la vasodilatation induite dans la peau par le courant anodique, sans modifier la réponse thermique d'hyperémie. La présente étude confirme l'absence de stimulation des récepteurs muscariniques et la production de prostaglandines vaso-dilatatrices dans la vasodilatation induite chez l'homme par réchauffement local de la peau de l'avant-bras. ABSTRACT Local changes in surface temperature have a powerful influence on the perfusion of human skin. Heating increases local skin blood flow (SkBF), but the mechanisms and mediators of this response (thermal hyperemia response) are incompletely elucidated. In the present study, we examined the possible dependence of the thermal hyperemia response on stimulation of muscarinic cholinergic receptors and on production of vasodilator prostanoids. In 13 male healthy subjects aged 20 - 30 years, a temperature- controlled chamber was positioned on the volar face of one forearm and used to raise surface temperature from 34to41°C. The time-course of the resulting thermal hyperemia response was recorded with a laser-Doppler imager. In one experiment, each of 8 subjects received an i.v. bolus of the antimuscarinic agent glycopyrrolate (4µg/kg) on one visit and saline on the other. The thermal hyperemia response was determined within the hour following the injections. Glycopyrrolate effectively inhibited the skin vasodilation induced by iontophoresis of acetylcholine, but did not influence the thermal hyperemia response. In a second experiment conducted in 5 other subjects, 1 gram of the cyclooxygenase inhibitor aspirin administered orally totally abolished the vasodilation induced in the skin by anodal current, but also failed to modify the thermal hyperemia response. The present study excludes the stimulation of muscarinic receptors and the production of vasodilator prostaglandins as essential and nonredundant mechanisms for the vasodilation induced by local heating in human forearm skin.

The effect of in vitro heating on the distribution of nuclear matrix polypeptides in HeLa cells.

The in situ nuclear matrix was obtained from HeLa cells. After permeabilization with nonionic detergent, the resulting structures were incubated for 1 h at 37 degrees C to determine whether or not such an incubation might result in the redistribution of nuclear polypeptides which resisted extraction with buffers of high-ionic strength (1.6 M NaCl or 0.25 M (NH4)2SO4 as well as DNase I digestion. Using indirect immunofluorescence experiments and monoclonal antibodies we show that heating to 37 degrees C changes the distribution of a 160 kDa protein previously shown to be a component of the inner matrix network. On the other hand, a 125 kDa polypeptide was not affected at all by the incubation. Our results clearly indicate that the inclusion of a 37 degrees C incubation (for example during digestion with DNase I) in the protocol to obtain the in situ nuclear matrix can result in the formation of in vitro artifacts.

Skin hyperemia induced by local heating : why is it blunted on repeat stimulations ?

Background: In human skin, local heating produces local vasodilatation, a response termed thermal hyperemia. Thermal hyperemia is largely mediated by nitric oxide (NO). It is blunted on repeat stimulations applied to the same skin spot, a phenomenon termed desensitization. As this phenomenon could reflect a desensitization in the vasodilator effects of NO, we investigated whether a prior exposure to exogenous NO would result in an attenuated vasodilatory response to a subsequent thermal challenge. Methods: Thirteen healthy young men were studied. Skin blood flow (SkBF) was mesured on forearm skin with laser Doppler imaging. Exposure to exogenous NO was carried out by iontophoresis of sodium nitroprusside (SNP), a donor of NO. A local thermal stimulus (temperature step from 34 to 41°C maintained for 30 minutes) was applied with temperature-controlled chambers. We tested the influence of a previous transient exposure to exogenous NO on : 1) thermal hyperemia and 2) the response to a second identical exposure to exogeneous NO. Results: Thermal hyperemia (plateau SkBF at 30 minutes minus SkBF at 34°C) obtained on a site preexposed to exogenous NO two hours before was lower than obtained on a site preexposed to iontophoretic current only (mean±SD 395±139 perfusion units [PU] vs 540±79 PU ; p<0.01). When repeated on the same skin site two hours after the first one, exposure to exogenous NO led to a blunted vasodilatory response (298±121 PU vs 394±92 PU), although this difference was not statistically significant (p≈0.09). Conclusion: In forearm human skin, prior exposure to exogenous NO partially inhibits thermal hyperemia. These data support that desensitization of thermal hyperemia depends on a downregulation of the NO-cGMP pathway, possibly downstream from the endogenous production of NO.

Magnetic and in vitro heating properties of implants formed in situ from injectable formulations and containing superparamagnetic iron oxide nanoparticles (SPIONs) embedded in silica microparticles for magnetically induced local hyperthermia

The biological and therapeutic responses to hyperthermia, when it is envisaged as an anti-tumor treatment modality, are complex and variable. Heat delivery plays a critical role and is counteracted by more or less efficient body cooling, which is largely mediated by blood flow. In the case of magnetically mediated modality, the delivery of the magnetic particles, most often superparamagnetic iron oxide nanoparticles (SPIONs), is also critically involved. We focus here on the magnetic characterization of two injectable formulations able to gel in situ and entrap silica microparticles embedding SPIONs. These formulations have previously shown suitable syringeability and intratumoral distribution in vivo. The first formulation is based on alginate, and the second on a poly(ethylene-co-vinyl alcohol) (EVAL). Here we investigated the magnetic properties and heating capacities in an alternating magnetic field (141 kHz, 12 mT) for implants with increasing concentrations of magnetic microparticles. We found that the magnetic properties of the magnetic microparticles were preserved using the formulation and in the wet implant at 37 degrees C, as in vivo. Using two orthogonal methods, a common SLP (20 Wg(-1)) was found after weighting by magnetic microparticle fraction, suggesting that both formulations are able to properly carry the magnetic microparticles in situ while preserving their magnetic properties and heating capacities. (C) 2010 Elsevier B.V. All rights reserved.

The vasodilatory response of skin microcirculation to local heating is subject to desensitization

RAPPORT DE SYNTHESE Introduction : dans la présente étude, nous nous sommes intéressés à la vasodilatation cutanée induite par le réchauffement local (hyperémie thermique). Il est établi, qu'une partie de cette réponse vasculaire est médiée par l'oxyde nitrique (NO). De manière générale, les effets du NO peuvent être sujets à une désensibilisation, comme nous le démontre le phénomène bien connu de tolérance aux dérivés nitrés. Le but du présent travail était d'évaluer si une telle désensibilisation existe dans le cas de l'hyperémie thermique. Méthodes : nous avons donc examiné si une première stimulation thermique pouvait en atténuer une deuxième, induite plus tard sur le même site cutané à une intervalle de 2h ou 4h. Pour vérifier directement l'effet du réchauffement local sur la sensibilité de la microcirculation cutanée au NO, nous avons de plus appliqué un donneur de NO (nitroprussiate de sodium, SNP) par la technique d' iontophorèse, sur des sites cutanés préalablement soumis à un échauffement local 2h ou 4h auparavant. Nous avons examinés 12 sujets en bonne santé habituelle, de sexe masculin, non fumeurs, âgés de 18 à 30 ans, ne prenant aucune médication. Le flux sanguin dermique a été mesuré par imagerie laser Doppler (LDI, Moor Instruments) sur la face antérieur de l'avant-bras. Le réchauffement local de la peau a été effectué grâce a des petits anneaux métalliques thermo-contrôlés contenant de l'eau. La température était initialement de 34°C. Elle a été augmentée à 41 °C en une minute et maintenue à cette valeur durant 30 minutes. Cette manoeuvre a été répétée sur le même site cutané soit 2 h, soit 4h plus tard. Quant à l'iontophorèse de SNP, elle a été effectuée sur des sites ayant préalablement subi, 2h ou 4h auparavant, un échauffement unique appliqué selon la technique qui vient d'être décrite. Résultats : nous avons observé une atténuation de l'hyperémie thermique lorsque celleci était examinée 2h après un premier échauffement local. Lorsque l'intervalle était de 4h la réponse vasodilatatrice n'était pas réduite. Nous avons également observé une atténuation de la réponse vasodilatatrice au SNP lorsque celui-ci a était appliqué 2h, mais non 4h après un premier échauffement local. Conclusion :cette étude démontre que la réponse vasodilatatrice cutanée induite par l'échauffement local est bien sujette à désensibilisation, comme nous en avions formulé l'hypothèse. Ce phénomène est transitoire. Il est lié, au moins en partie, à une baisse de sensibilité de la microcirculation cutanée aux effets vasodilatateurs du NO.

Cooling and heating by adiabatic magnetization in Ni50Mn34In16 magnetic shape-memory alloy

We report on measurements of the adiabatic temperature change in the inverse magnetocaloric Ni50Mn34In16 alloy. It is shown that this alloy heats up with the application of a magnetic field around the Curie point due to the conventional magnetocaloric effect. In contrast, the inverse magnetocaloric effect associated with the martensitic transition results in the unusual decrease of temperature by adiabatic magnetization. We also provide magnetization and specific heat data which enable to compare the measured temperature changes to the values indirectly computed from thermodynamic relationships. Good agreement is obtained for the conventional effect at the second-order paramagnetic-ferromagnetic phase transition. However, at the first-order structural transition the measured values at high fields are lower than the computed ones. Irreversible thermodynamics arguments are given to show that such a discrepancy is due to the irreversibility of the first-order martensitic transition.

The vasodilatory response of skin microcirculation to local heating is subject to desensitization.

BACKGROUND: In humans, local heating increases skin perfusion by mechanisms dependent on nitric oxide (NO). Because the vascular effects of NO may be subject to desensitization, we examined whether a first local thermal stimulus would attenuate the hyperemic response to a second one applied later. METHODS: Twelve healthy young men were studied. Skin blood flow (SkBF) was measured on forearm skin with laser Doppler imaging. Local thermal stimuli (temperature step from 34 to 41 degrees C maintained for 30 minutes) were applied with temperature-controlled chambers. We also tested the influence of prior local heating on the vasodilation induced by sodium nitroprusside (SNP), a donor of NO. RESULTS: On reheating the same spot after two hours, the response of SkBF (i.e., plateau SkBF at 30 minutes minus SkBF at 34 degrees C) was lower than during the first stimulation (mean+/-SD 404+/-212 perfusion units [PU] vs. 635+/-100 PU; P&lt;0.001). There was no such difference when reheating after four hours (654+/-153 vs. 645+/-103 PU; P=NS). Two, but not four, hours after local heating, the response of SkBF to SNP was reduced. CONCLUSION: The NO-dependent hyperemic response induced by local heating in human skin is subject to desensitization. At least one part of the mechanism implicated consists of a desensitization to the effects of NO itself.