Flexible and Hierarchical 3D Interconnected Silver Nanowires/Cellulosic Paper-Based Thermoelectric Sheets with Superior Electrical Conductivity and Ultrahigh Thermal Dispersion Capability.

To date, various electronic devices have been strategically fabricated, and simultaneous realization of high electrical conductivity, sensing property, and heat-conducting property by a simple, efficient, and accurate approach is significant but still challenging. Here, cellulosic fiber supported 3D interconnected silver nanowire (AgNW) networks with hierarchical structures are rationally designed to achieve excellent electrical conductivity and superior thermal dispersion capability. In particular, thermal annealing at the junctions enables both phonon and electron transfer as well as impedes interfacial slippage. In the current study, the AgNW/cellulosic paper with the low Ag content (1.55 wt %) exhibits a low sheet resistance of 0.51 Ω sq-1. More importantly, the AgNW/cellulosic paper-based flexible strain sensor has been reasonably developed, which can be applied to monitor various microstructural changes and human motions with high sensitivity and robust stability (fast response/relaxation time of ∼100 ms and high stability >2000 bending-stretching cycles). The AgNW/cellulosic paper-based device also displays efficient thermal dispersion property, which offers exciting opportunities for thermal management application. Furthermore, the obtained hybrid paper exhibits superior heat dispersion capacity for thermal management devices. Overall, uniform dispersion and 3D interconnected junctions of AgNW among the fibers inside the cellulosic papers lead to the combination of high mechanical strength, highly efficient electrical conductivity, and ultrahigh heat dispersion property. The AgNW/cellulosic paper has promising potentials in the flexible and wearable sensing elements, thermal management materials, and artificial intelligence devices.

Advection and dispersion heat transport mechanisms in the quantification of shallow geothermal resources and associated environmental impacts.

Borehole Heat Exchangers (BHEs) are increasingly being used to exploit shallow geothermal energy. This paper presents a new methodology to provide a response to the need for a regional quantification of the geothermal potential that can be extracted by BHEs and the associated environmental impacts. A set of analytical solutions facilitates accurate calculation of the heat exchange of BHEs with the ground and its environmental impacts. For the first time, advection and dispersion heat transport mechanisms and the temporal evolution from the start of operation of the BHE are taken into account in the regional estimation of shallow geothermal resources. This methodology is integrated in a GIS environment, which facilitates the management of input and output data at a regional scale. An example of the methodology's application is presented for Barcelona, in Spain. As a result of the application, it is possible to show the strengths and improvements of this methodology in the development of potential maps of low temperature geothermal energy as well as maps of environmental impacts. The minimum and maximum energy potential values for the study site are 50 and 1800 W/m(2) for a drilled depth of 100 m, proportionally to Darcy velocity. Regarding to thermal impacts, the higher the groundwater velocity and the energy potential, the higher the size of the thermal plume after 6 months of exploitation, whose length ranges from 10 to 27 m long. A sensitivity analysis was carried out in the calculation of heat exchange rate and its impacts for different scenarios and for a wide range of Darcy velocities. The results of this analysis lead to the conclusion that the consideration of dispersion effects and temporal evolution of the exploitation prevent significant differences up to a factor 2.5 in the heat exchange rate accuracy and up to several orders of magnitude in the impacts generated.

Trabajos originales Preferencia termal de machos adultos de Cryphiops caementarius previamente aclimatados a diferen- tes temperaturas / Thermal preference of adult males of Cryphiops caementarius previously acclimated at different temperatures

Resumen El objetivo fue determinar la preferencia termal de machos adultos de Cryphiops caementarius previamente aclimatados a diferentes temperaturas. Los camarones se colectaron del río Pativilca. En laboratorio, los camarones se aclimataron durante 30 días en nueve acuarios, cada uno con 10 recipientes circulares. En cada recipiente hubo un camarón (10 por acuario). Las temperaturas de aclimatación fueron de 19, 24 y 28 °C. El sistema de gradiente de temperatura (12 a 33 °C) fue una canaleta de PVC (3 m de longitud y 10 cm de profundidad) con 18 compartimentos. En un extremo de la canaleta se colocaron termorreguladores sumergibles (100W) y en el otro extremo, bolsas con hidrogel congeladas. La preferencia termal se determinó por el método agudo y las pruebas se realizaron entre las 08:00 y 14:00 h. Los camarones aclimatados a 24 °C se desplazaron a compartimentos cuyas temperaturas fueron más altas que la temperatura de aclimatación. Los camarones aclimatados a 24 °C se desplazaron a compartimentos cuyas temperaturas fueron alrededor de la temperatura de aclimatación. Los camarones aclimatados a 28 °C se desplazaron a compartimentos donde las temperaturas fueron más bajas que aquella de aclimatación. La preferencia termal de los camarones aclimatados a 19 °C fue de 22.7 °C, y la de los aclimatados a 24 °C fue de 24.8 °C, ambos sin diferencias significativas (p>0.05). En cambio, en los aclimatados a 28°C fue de 21.1 °C, que solo difirió (p<0.05) con los aclimatados a 19 °C. La preferencia termal final fue de 24.5 °C.

Abstract In this work, we establish the thermal preference of Cryphiops caementarius adult males, previously acclimated at different temperatures. Shrimp were collected from the Pativilca River. In the laboratory, shrimp were acclimated for 30 days in nine aquariums, each with 10 circular containers. In each container, there was a shrimp (10 per aquarium). Acclimation temperatures were 19, 24 and 28 °C. The gradient temperature system (12 to 33 °C) consisted for a PVC gutter (3 m long and 10 cm deep) with 18 compartments. Submersible thermoregulators (100W) were placed at one end of the gutter and the other end, frozen hydrogel bags. The thermal preference was determined by the acute method and the tests were performed between 08:00 and 14:00 h. Shrimp acclimated at 24 °C moved to compartments whose temperatures were higher than the acclimation temperature. Shrimp acclimated at 24 °C moved to compartments whose temperatures were around the acclimation temperature. Shrimp acclimated at 28 °C moved to compartments where temperatures were lower than acclimation. The thermal preference of acclimated shrimp at 19 °C was 22.7 °C, and those acclimated at 24 °C were 24.8 °C, both without significant differences (p>0.05). On the other hand, in acclimated ones at 28 °C it was 21.1 °C, which only differed (p<0.05) with those acclimated at 19 °C. The final thermal preference was 24.5 °C.