Estenosis esofágica benigna en un felino asociada a la administración oral de doxiciclina. Terapéutica endoscópica

Se presenta un caso de estenosis esofágica en un felino, asociada a la administración oral de doxiciclina. Se describe su tratamiento endoscópico.

A numerical analysis of an Active Magnetic Regenerative Refrigerant system with a multi-layer regenerator

Abstract The Active Magnetic Regenerative Refrigeration (AMRR) cycle is a special kind of regenerator for the magnetic refrigerator, in which the magnetic material matrix works both as a refrigerating medium and as a heat regenerating medium, while the fluid flowing in the porous matrix works as a heat transfer medium. The performance of an AMRR cycle depends strongly on the behaviour of the adiabatic magnetization temperature change as a function of material temperature in the flow direction of the regenerator. In the present paper, a practical model for predicting the performance and efficiency of an AMRR cycle has been developed. The model simulates both the ferromagnetic material and the entire cycle of an AMR operating in conformity with a Brayton regenerative cycle. The model simulates different kinds of layered regenerators operating at their optimal operation point. The program study the Gd-x Tb1-x alloys as constituent materials for the regenerator over the temperature range 275 – 295 K, and Gdx Dy1-x alloys in the temperature range 260 – 280 K. With this model, the refrigeration capacity, the power consumption and consequently the coefficient of performance can be predicted. The results show a greater COP for the refrigerator based on the magnetocaloric technology compared with the COP of a classical vapour compression plant working between the same thermal levels

Kinetic energy harvesting for enhancing sustainability of refrigerated transportation

The industry of temperature-controlled transportation has shown significant growth in recent years, and this growth is expected to continue in the future. As the sector expands, it's crucial to focus on reducing energy consumption and greenhouse gas emissions related to transport refrigeration systems to meet the planned decarbonization goals. In this study, the energy and environmental benefits of implementing an electric Kinetic Energy Recovery System (KERS) on a refrigerated light-duty commercial van, equipped with a vapor compression refrigeration (VCR) system, are assessed by means of dynamic simulation. The KERS considered involves a LiFePO4 battery as electricity storage system, a brushless motor-generator unit and a hybrid inverter able to both charge the battery and power the refrigeration system. For each component of the system, i.e. the engine, the alternator, the transmission system and the KERS, the real efficiencies have been considered. The dynamic behaviour of the KERS is simulated by using data obtained by performing a real urban single-delivery 40 km mission, during which the vehicle operating conditions, as well as the electricity demand of the refrigeration system, have been measured. The estimation of the potential benefits of the proposed solution has been performed by comparing the electricity produced by the KERS (and available for use) and the measured energy demand of the refrigeration system. The results have shown that the electricity available for use could cover more than 47% of the total electricity demand. This means that nearly half of the primary energy/fuel consumption can be saved by employing a KERS in refrigerated-light duty vehicles. In particular, emissions savings ranging between 9 and 13 gCO2,e and cost savings between 0.4 and 0.7 c€ per kilometer travelled can be achieved, resulting in an average payback period of 8 years. In addition, when considering the entire useful life of a refrigerated van equal to 10 years, CO2,e savings of 4515–6710 kgCO2,e are obtained. The low complexity of the proposed system and the availability of the components on the market, together with the results obtained by simulation, make using KERS in refrigerated transport a promising solution throughout the decarbonization of the refrigerated transport sector

A review on thermal management of battery packs for electric vehicles

The development of efficient Electric Vehicles (EVs) is related to the management of different parts of the powertrain, as the Lithium-ion (Li-ion) batteries. An important feature which affects their safety, performance, and useful life is the average temperature which must be included in an optimal range to prevent several dangerous phenomena. For this reason, Thermal Management Systems (TMSs) of battery packs of EVs are necessary to guarantee correct functioning in all environments and operating conditions. This review has the intention to divulge the recent developments in the thermal management of Li-ion batteries of EVs reached by researchers and car manufacturers to compare academic studies to the state of the art of the automotive industry from a thermal engineering point of view. Several experimental and numerical studies published in literature have been reported, and nine EV models have been analysed to explain how car manufacturers have developed their new models launched on the market. The choice of the models has been made since the quantity and the quality of data available on the official sites of manufacturers and specialist journals. In conclusion, the future perspectives of thermal management of battery packs are resumed to understand which path research and car manufacturers are following for the next generation of EVs

Refrigeration plant exergetic analysis varying the compressor capacity

The paper presents an exergetic analysis of a vapour compressor refrigeration plant when the refrigeration capacity is controlled by varying the compressor speed. The aim is performance evaluation of both the whole plant and its individual components. The analysis of the exergy flow destroyed in each device of the plant varying the compressor speed has been carried out in order to determine the relative irreversibility of the plant components. The vapour compression plant is subjected to a commercially available cold store. The compressor working with R22, R407C and R507 and designed for a revolution speed corresponding to 50 Hz supply current frequency, has been used varying the frequency in the range 30–50 Hz. In this range, the most suitable working fluids proposed as substitutes of R22, as R407C (R32/R125/R134a 23/25/52% in mass), R507 (R125/R143A 50/50% in mass) and R417A (R125/R134a/R600 46.6/50/3.4% in mass), have been tested. The variable-speed compressor is fitted with a pulse-width modulated source inverter (PWM) predominantly used in medium power applications due to its relatively low cost and high efficiency. The basic difference between variable speed refrigeration and conventional refrigeration systems is in the control of the system capacity at part-load conditions. The conventional refrigeration systems are characterized by compressor on/off cycles arising from by the thermostatic control. On the contrary when the inverter is used the capacity of the refrigeration system is matched to the load regulating the compressor motor speed. When the control of the compressor capacity is obtained by varying its speed there is an energy saving with respect to the thermostatic control. The best results of the exergetic analysis have been obtained using R22 followed by the non-azeotropic mixture designed as R407C that confirms, among the fluid candidates R22 substitution a better performance, shown also at the compressor nominal speed

Comparison between adenosine triphosphate bioluminescence and aerobic colony count to assess surface sanitation in the hospital environment

Background: Adenosine triphosphate bioluminescence produced by the firefly luciferase has been successfully introduced to verify cleaning procedures in the food industry according to the Hazard Analysis Critical Control Point program. Our aim was to evaluate the reliability of bioluminescence as a tool to monitor the effectiveness of sanitation in healthcare settings, in comparison with the microbiological gold standard. Methods: 614 surfaces of various material were randomly sampled in Policlinico University Hospital units in Palermo, Italy, to detect adenosine triphosphate bioluminescence and aerobic colony count. Linear regression model and Pearson correlation coefficient were used to estimate the relationship between the two variables of the study. Results: Aerobic colony count median was 1.71 colony forming units/cm2 (interquartile range = 3.8), whereas adenosine triphosphate median was 59.9 relative light units/cm2 (interquartile range = 128.3). Pearson coefficient R2 was 0.09. Sensitivity and specificity of bioluminescence test with respect to microbiology were 46% and 71%, whereas positive predictive value and negative predictive value were 53% and 65%, respectively. Conclusion: According to our results, there seemed to be no linear correlation between aerobic colony count and adenosine triphosphate values, suggesting that current bioluminescence technology has not any proportional relationships with culturable microbes contaminating environmental surfaces in health-care settings

Hydrodynamic Characterization of GULF STREAM Circulation in a Pilot Scale Fluidized Bed Combustor

The present study addresses the hydrodynamics of a pilot-scale fluidized bed combustor with a focus on the establishment of "Gulf Stream" circulation patterns as a solids mixing promoter. Time-resolved pressure signals measured at different locations in the bed and in the plenum were analyzed in the time, frequency and phase-space domains. Results were matched against qualitative characterization of fluidization patterns by visual observation of the bed surface

Zeolite-based monoliths for water softening by ion exchange/precipitation process

In this work, the design of a monolithic softener obtained by geopolymer gel conversion is proposed. The softener used consists in a geopolymeric macroporous matrix functionalized by the co-crystallization of zeolite A and X in mixture. The dual nature of the proposed material promotes a softening process based on the synergistic effect of cation exchange and alkaline precipitation. A softening capacity of 90% and 54% for Ca2+ and Mg2+ respectively was attained in 24 h. In fact, the softener reported a Cation Exchange Capacity (CEC) value of 4.43 meq g−1. Technical features such as density, porosity and mechanical resistance were also measured. The use of this monolithic softener can improve performance and sustainability of hardness removal from tap water, reducing the production of sludge and adding the possibility to partially regenerate or reuse it

Individual metering and submetering for cooling application

In 2012 the Energy Efficiency Directive (EED) has set mandatory installation of individual metering and submetering systems for accounting thermal energy consumption in buildings where centralized heating/cooling sources are present, when technically feasible and cost efficient. As a consequence, direct thermal energy meters or indirect heat accounting systems have spread widely in residential buildings, for metering and sub-metering in space heating applications. On the other hand, individual metering of thermal energy in space cooling is a difficult task, due to the very different types of cooling systems and to the lack of technical and legal metrology regulation. In this paper possible solutions available for direct metering and submetering of different types of centralized cooling systems are discussed. Indeed, for direct metering application, the cooling fluid flow metering is a particularly crucial issue due to small pipe diameters and different fluid properties. Thus, the authors carried out an experimental comparison between a Coriolis flow-meter and an ultrasonic clamp-on flow-meter in the cooling fluid circuit of a direct expansion system. Tests have been performed at different operative temperature differences between flow and return, showing relative errors within ± 10%