Polytechnic University of Valencia

About: Polytechnic University of Valencia is a education organization based out in Valencia, Spain. It is known for research contribution in the topics: Catalysis & Population. The organization has 16282 authors who have published 40162 publications receiving 850234 citations.

Effect of the cooling rate on the nucleation kinetics of poly(L-lactic acid) and its influence on morphology

Abstract: Although the crystallization kinetics of PLLA is slow enough to allow one to obtain amorphous samples by cooling from the melt at moderate rates, surprisingly, at the same time, the formation of crystallization nuclei is difficult to avoid. Their amount depends on the cooling rate from the melt: the higher the cooling rate, the lower the amount of available nuclei after reaching the glass state. Cooling at controlled rates of 5−300 °C/min was performed by making use of a relatively new high-speed calorimetry technology, high-performance DSC (HPer DSC). Subsequent isothermal cold crystallization of amorphous PLLA, at different temperatures distributed across the bell-shaped crystal growth curve, was shown to depend on the rate at which the glass state was attained, reflecting the number of nuclei formed. However, (only) after complete cold crystallization, the DSC heating curves and the resulting morphology measured by optical microscopy and AFM were shown to be independent of the previous cooling rate in...

Underwater wireless sensor communications in the 2.4 GHz ISM frequency band.

Abstract: One of the main problems in underwater communications is the low data rate available due to the use of low frequencies. Moreover, there are many problems inherent to the medium such as reflections, refraction, energy dispersion, etc., that greatly degrade communication between devices. In some cases, wireless sensors must be placed quite close to each other in order to take more accurate measurements from the water while having high communication bandwidth. In these cases, while most researchers focus their efforts on increasing the data rate for low frequencies, we propose the use of the 2.4 GHz ISM frequency band in these special cases. In this paper, we show our wireless sensor node deployment and its performance obtained from a real scenario and measures taken for different frequencies, modulations and data transfer rates. The performed tests show the maximum distance between sensors, the number of lost packets and the average round trip time. Based on our measurements, we provide some experimental models of underwater communication in fresh water using EM waves in the 2.4 GHz ISM frequency band. Finally, we compare our communication system proposal with the existing systems. Although our proposal provides short communication distances, it provides high data transfer rates. It can be used for precision monitoring in applications such as contaminated ecosystems or for device communicate at high depth.

Ferromagnetic Coupling through Spin Polarization in a Dinuclear Copper(II) Metallacyclophane.

Abstract: First organic radicals, now metal complexes: A successful extension to metal complexes of a well-known organic radical approach to ferromagnetism is exemplified by the triplet ground-state molecule containing two Cu(II) centers connected by a double m-phenylenediamide skeleton of the cyclophane type shown in the scheme.