Magnetization versus heat treatment in rapidly solidified NdFeB alloys

NdFeB melt-spun amorphous or partially amorphous alloys of four compositions were prepared. Their crystallization kinetics induced by thermal treatment was studied by differential scanning calorimetry and scanning and transmission electron microscopy. Scanning electron microscopy demonstrated that heterogeneous nucleation occurs preferentially at the ribbon surface which was in contact with the wheel. The explicit form of the kinetic equation that best describes the first stage of crystallization under high undercooling conditions was obtained for each alloy. From the crystallization results, the lower part of the experimental time-temperature-transformation curves was deduced for each alloy and extrapolated up to the high-temperature limit of their validity. Microstructural observations showed a typical size of the microcrystals obtained by heat treatment of ~100 nm. From the magnetic properties measured with a vibrating sample magnetometer, the same magnetic behavior of partially crystallized alloys is observed regardless of the temperature of annealing provided the same crystallization fraction, x, is achieved, at least for small values of x (typically ~10%).

Design and construction of precision heat fluxmeters

The possibility of local elastic instabilities is considered in a first¿order structural phase transition, typically a thermoelastic martensitic transformation, with associated interfacial and volumic strain energy. They appear, for instance, as the result of shape change accommodation by simultaneous growth of different crystallographic variants. The treatment is phenomenological and deals with growth in both thermoelastic equilibrium and in nonequilibrium conditions produced by the elastic instability. Scaling of the transformed fraction curves against temperature is predicted only in the case of purely thermoelastic growth. The role of the transformation latent heat on the relaxation kinetics is also considered, and it is shown that it tends to increase the characteristic relaxation times as adiabatic conditions are approached, by keeping the system closer to a constant temperature. The analysis also reveals that the energy dissipated in the relaxation process has a double origin: release of elastic energy Wi and entropy production Si. The latter is shown to depend on both temperature rate and thermal conduction in the system.

Carbon balance and crop residue management in dynamic equilibrium under a no-till system in Campos Gerais

The adoption of no-tillage systems (NT) and the maintenance of crop residues on the soil surface result in the long-term increase of carbon (C) in the system, promoting C sequestration and reducing C-CO2 emissions to the atmosphere. The purpose of this study was to evaluate the C sequestration rate and the minimum amount of crop residues required to maintain the dynamic C equilibrium (dC/dt = 0) of two soils (Typic Hapludox) with different textural classes. The experiment was arranged in a 2 x 2 x 2 randomized block factorial design. The following factors were analyzed: (a) two soil types: Typic Hapludox (Oxisol) with medium texture (LVTM) and Oxisol with clay texture (LVTA), (b) two sampling layers (0-5 and 5-20 cm), and (c) two sampling periods (P1 - October 2007; P2 - September 2008). Samples were collected from fields under a long-term (20 years) NT system with the following crop rotations: wheat/soybean/black oat + vetch/maize (LVTM) and wheat/maize/black oat + vetch/soybean (LVTA). The annual C sequestration rates were 0.83 and 0.76 Mg ha-1 for LVTM and LVTA, respectively. The estimates of the minimum amount of crop residues required to maintain a dynamic equilibrium (dC/dt = 0) were 7.13 and 6.53 Mg ha-1 year-1 for LVTM and LVTA, respectively. The C conversion rate in both studied soils was lower than that reported in other studies in the region, resulting in a greater amount of crop residues left on the soil surface.

A classical particle in heat bath under the influence of external noise

A very simple model of a classical particle in a heat bath under the influence of external noise is studied. By means of a suitable hypothesis, the heat bath is reduced to an internal colored noise (OrnsteinUhlenbeck noise). In a second step, an external noise is coupled to the bath. The steady state probability distributions are obtained.

Heat capacity measurements on the equiatomic compounds in Ni-X (X = Al, In, Si, Ge and Bi) and M-Sb (with M = Ni, Co and Fe) systems

Molar heat capacities of the binary compounds NiAl, NiIn, NiSi, NiGe, NiBi, NiSb, CoSb and FeSb were determined every 10 K by differential scanning calorimetry in the temperature range 310-1080 K. The experimental results have been fitted versus temperature according to C-p = a + b . T + c . T-2 + d . T-2. Results are given, discussed and compared to estimations found in the literature. Two compounds, NiBi and FeSb, are subject to transformations between 460 and 500 K. (C) 1999 Elsevier Science Ltd. All rights reserved.

Heat pulse line-source method to determine thermal conductivity of consolidated rocks

An instrument designed to measure thermal conductivity of consolidated rocks, dry or saturated, using a transient method is presented. The instrument measures relative values of the thermal conductivity, and it needs calibration to obtain absolute values. The device can be used as heat pulse line source and as continuous heat line source. Two parameters to determine thermal conductivity are proposed: TMAX, in heat pulse line source, and SLOPE, in continuous heat line source. Its performance is better, and the operation simpler, in heat pulse line-source mode with a measuring time of 170 s and a reproducibility better than 2.5%. The sample preparation is very simple on both modes. The performance has been tested with a set of ten rocks with thermal conductivity values between 1.4 and 5.2 W m¿1 K¿1 which covers the usual range for consolidated rocks.

Estimation of soil moisture in the root-zone from remote sensing data

Field-based soil moisture measurements are cumbersome. Thus, remote sensing techniques are needed because allows field and landscape-scale mapping of soil moisture depth-averaged through the root zone of existing vegetation. The objective of the study was to evaluate the accuracy of an empirical relationship to calculate soil moisture from remote sensing data of irrigated soils of the Apodi Plateau, in the Brazilian semiarid region. The empirical relationship had previously been tested for irrigated soils in Mexico, Egypt, and Pakistan, with promising results. In this study, the relationship was evaluated from experimental data collected from a cotton field. The experiment was carried out in an area of 5 ha with irrigated cotton. The energy balance and evaporative fraction (Λ) were measured by the Bowen ratio method. Soil moisture (θ) data were collected using a PR2 - Profile Probe (Delta-T Devices Ltd). The empirical relationship was tested using experimentally collected Λ and θ values and was applied using the Λ values obtained from the Surface Energy Balance Algorithm for Land (SEBAL) and three TM - Landsat 5 images. There was a close correlation between measured and estimated θ values (p<0.05, R² = 0.84) and there were no significant differences according to the Student t-test (p<0.01). The statistical analyses showed that the empirical relationship can be applied to estimate the root-zone soil moisture of irrigated soils, i.e. when the evaporative fraction is greater than 0.45.

Effect of anionic salts in concentrate mixture and calcium intake on some blood and urine minerals, acid-base balance and feed intake of dry pregnant cows on grass silage based feeding

Selostus: Kationi-anionitasapaino ja kalsiumin saanti ummessaolevien lypsylehmien säilörehuruokinnassa

Interventions aiming at balance confidence improvement in older adults: an updated review.

BACKGROUND: Loss of balance confidence is a frequent condition that affects 20-75% of community-dwelling older persons. Although a recent fall is a common trigger, loss of balance confidence also appears independent of previous experience with falls. Maintaining or improving balance confidence is important to avoid unnecessary, self-imposed restrictions of activity and subsequent disability. Holding another person's hand or using an assistive device while walking are simple interventions that are used naturally to address poor balance confidence in daily life. However, more complex interventions have also been developed and tested to achieve more sustained improvement in balance confidence. OBJECTIVES: This review describes interventions that have been tested to improve balance confidence in older community-dwelling persons. METHODS: Based on 2 recent systematic reviews, an additional search for literature was performed to update current information on interventions aiming at balance confidence improvement. Interventions were classified as those directly aimed at increasing balance confidence or not, and further stratified into those using monofactorial or multifactorial approaches. RESULTS: A total of 46 randomized controlled trials were identified. Five of the 8 interventions that directly targeted balance confidence showed benefits. Among those, multicomponent behavioral group interventions provided the most robust evidence of benefits in improving balance confidence and in decreasing activity avoidance. Among interventions not directly aiming at balance confidence improvement (11/21 studies with benefits), exercise (including tai chi) appears as the most promising monofactorial intervention. Nine of the 17 multifactorial fall prevention programs showed an effect on balance confidence, exercise being a main component in 7 of these 9 studies. Interventions that targeted elderly persons reporting poor balance confidence and/or those at risk for falls seemed more likely to be beneficial. CONCLUSIONS: Positive and sometimes sustained improvement in balance confidence can be achieved by various interventions among community-dwelling elderly persons. The effect of these interventions on activity restriction associated with poor balance confidence have been less well studied, but some studies also suggest potential benefits.

Negative impact of hypocaloric feeding and energy balance on clinical outcome in ICU patients

Résumé Introduction : Les patients nécessitant une prise en charge prolongée en milieu de soins intensifs et présentant une évolution compliquée, développent une réponse métabolique intense caractérisée généralement par un hypermétabolisme et un catabolisme protéique. La sévérité de leur atteinte pathologique expose ces patients à la malnutrition, due principalement à un apport nutritionnel insuffisant, et entraînant une balance énergétique déficitaire. Dans un nombre important d'unités de soins intensifs la nutrition des patients n'apparaît pas comme un objectif prioritaire de la prise en charge. En menant une étude prospective d'observation afin d'analyser la relation entre la balance énergétique et le pronostic clinique des patients avec séjours prolongés en soins intensifs, nous souhaitions changer cette attitude et démonter l'effet délétère de la malnutrition chez ce type de patient. Méthodes : Sur une période de 2 ans, tous les patients, dont le séjour en soins intensifs fut de 5 jours ou plus, ont été enrôlés. Les besoins en énergie pour chaque patient ont été déterminés soit par calorimétrie indirecte, soit au moyen d'une formule prenant en compte le poids du patient (30 kcal/kg/jour). Les patients ayant bénéficié d'une calorimétrie indirecte ont par ailleurs vérifié la justesse de la formule appliquée. L'âge, le sexe le poids préopératoire, la taille, et le « Body mass index » index de masse corporelle reconnu en milieu clinique ont été relevés. L'énergie délivrée l'était soit sous forme nutritionnelle (administration de nutrition entérale, parentérale ou mixte) soit sous forme non-nutritionnelle (perfusions : soluté glucosé, apport lipidique non nutritionnel). Les données de nutrition (cible théorique, cible prescrite, énergie nutritionnelle, énergie non-nutritionnelle, énergie totale, balance énergétique nutritionnelle, balance énergétique totale), et d'évolution clinique (nombre des jours de ventilation mécanique, nombre d'infections, utilisation des antibiotiques, durée du séjour, complications neurologiques, respiratoires gastro-intestinales, cardiovasculaires, rénales et hépatiques, scores de gravité pour patients en soins intensifs, valeurs hématologiques, sériques, microbiologiques) ont été analysées pour chacun des 669 jours de soins intensifs vécus par un total de 48 patients. Résultats : 48 patients de 57±16 ans dont le séjour a varié entre 5 et 49 jours (motif d'admission : polytraumatisés 10; chirurgie cardiaque 13; insuffisance respiratoire 7; pathologie gastro-intestinale 3; sepsis 3; transplantation 4; autre 8) ont été retenus. Si nous n'avons pu démontrer une relation entre la balance énergétique et plus particulièrement, le déficit énergétique, et la mortalité, il existe une relation hautement significative entre le déficit énergétique et la morbidité, à savoir les complications et les infections, qui prolongent naturellement la durée du séjour. De plus, bien que l'étude ne comporte aucune intervention et que nous ne puissions avancer qu'il existe une relation de cause à effet, l'analyse par régression multiple montre que le facteur pronostic le plus fiable est justement la balance énergétique, au détriment des scores habituellement utilisés en soins intensifs. L'évolution est indépendante tant de l'âge et du sexe, que du status nutritionnel préopératoire. L'étude ne prévoyait pas de récolter des données économiques : nous ne pouvons pas, dès lors, affirmer que l'augmentation des coûts engendrée par un séjour prolongé en unité de soins intensifs est induite par un déficit énergétique, même si le bon sens nous laisse penser qu'un séjour plus court engendre un coût moindre. Cette étude attire aussi l'attention sur l'origine du déficit énergétique : il se creuse au cours de la première semaine en soins intensifs, et pourrait donc être prévenu par une intervention nutritionnelle précoce, alors que les recommandations actuelles préconisent un apport énergétique, sous forme de nutrition artificielle, qu'à partir de 48 heures de séjour aux soins intensifs. Conclusions : L'étude montre que pour les patients de soins intensifs les plus graves, la balance énergétique devrait être considérée comme un objectif important de la prise en charge, nécessitant l'application d'un protocole de nutrition précoce. Enfin comme l'évolution à l'admission des patients est souvent imprévisible, et que le déficit s'installe dès la première semaine, il est légitime de s'interroger sur la nécessité d'appliquer ce protocole à tous les patients de soins intensifs et ceci dès leur admission. Summary Background and aims: Critically ill patients with complicated evolution are frequently hypermetabolic, catabolic, and at risk of underfeeding. The study aimed at assessing the relationship between energy balance and outcome in critically ill patients. Methods: Prospective observational study conducted in consecutive patients staying 5 days in the surgical ICU of a University hospital. Demographic data, time to feeding, route, energy delivery, and outcome were recorded. Energy balance was calculated as energy delivery minus target. Data in means+ SD, linear regressions between energy balance and outcome variables. Results: Forty eight patients aged 57±16 years were investigated; complete data are available in 669 days. Mechanical ventilation lasted 11±8 days, ICU stay 15+9 was days, and 30-days mortality was 38%. Time to feeding was 3.1 ±2.2 days. Enteral nutrition was the most frequent route with 433 days. Mean daily energy delivery was 1090±930 kcal. Combining enteral and parenteral nutrition achieved highest energy delivery. Cumulated energy balance was between -12,600+ 10,520 kcal, and correlated with complications (P<0.001), already after 1 week. Conclusion: Negative energy balances were correlated with increasing number of complications, particularly infections. Energy debt appears as a promising tool for nutritional follow-up, which should be further tested. Delaying initiation of nutritional support exposes the patients to energy deficits that cannot be compensated later on.

Giant heat dissipation at the low temperature reversible-irreversible transition in Gd5Ge4

The heat exchanged at the low-temperature first-order magnetostructural transition is directly measured in Gd5Ge4 . Results show that the origin and the temperature dependence of the heat exchanged varies with the reversible/irreversible character of the first-order transition. In the reversible regime, the heat exchanged by the sample is mostly due to the latent heat at the transition and decreases with decreasing temperature, while in the irreversible regime, the heat is irreversibly dissipated and increases strongly with decreasing temperature, reaching a value of 237 J/kg at 4 K.

Heat transfer between nanoparticles: Thermal conductance for near-field interactions

We analyze the heat transfer between two nanoparticles separated by a distance lying in the near-field domain in which energy interchange is due to the Coulomb interactions. The thermal conductance is computed by assuming that the particles have charge distributions characterized by fluctuating multipole moments in equilibrium with heat baths at two different temperatures. This quantity follows from the fluctuation-dissipation theorem for the fluctuations of the multipolar moments. We compare the behavior of the conductance as a function of the distance between the particles with the result obtained by means of molecular dynamics simulations. The formalism proposed enables us to provide a comprehensive explanation of the marked growth of the conductance when decreasing the distance between the nanoparticles.

Effect of anionic salts in concentrate mixture and magnesium intake on some blood and urine minerals and acid-base balance of dry pregnant cows on grass silage based feeding

Selostus: Kationi-anionitasapaino ja magnesiumin saanti ummessaolevien lypsylehmien säilörehuruokinnassa

Heat kernels and thermodynamics in Rindler space

We point out that using the heat kernel on a cone to compute the first quantum correction to the entropy of Rindler space does not yield the correct temperature dependence. In order to obtain the physics at arbitrary temperature one must compute the heat kernel in a geometry with different topology (without a conical singularity). This is done in two ways, which are shown to agree with computations performed by other methods. Also, we discuss the ambiguities in the regularization procedure and their physical consequences.