Graphene-Based Electrodes for Silicon Heterojunction Solar Cell Technology.

Transparent conductive electrodes based on graphene have been previously proposed as an attractive candidate for optoelectronic devices. While graphene alone lacks the antireflectance properties needed in many applications, it can still be coupled with traditional transparent conductive oxides, further enhancing their electrical performance. In this work, the effect of combining indium tin oxide with between one and three graphene monolayers as the top electrode in silicon heterojunction solar cells is analyzed. Prior to the metal grid deposition, the electrical conductance of the hybrid electrodes was evaluated through reflection-mode terahertz time-domain spectroscopy. The obtained conductance maps showed a clear electrical improvement with each additional graphene sheet. In the electrical characterization of the finished solar cells, this translated to a meaningful reduction in the series resistance and an increase in the devices' fill factor. On the other hand, each additional sheet absorbs part of the incoming radiation, causing the short circuit current to simultaneously decrease. Consequently, additional graphene monolayers past the first one did not further enhance the efficiency of the reference cells. Ultimately, the increase obtained in the fill factor endorses graphene-based hybrid electrodes as a potential concept for improving solar cells' efficiency in future novel designs.

Comparative study of ring and random cavities for fiber lasers.

An experimental comparison of three fiber laser structures with the same Raman gain medium is presented in order to establish the main pros and cons of each basic scheme. The first fiber laser is based on a hybrid ring-random fiber laser, the second one is a pure ring fiber laser, and the last one is a random fiber laser. Several aspects have been taken into account in the study. First, from the optical point of view, the parameters of interest compared are output power, lasing threshold, slope efficiency, power fluctuations, and the longitudinal modes have been analyzed. Second, the possible utilization of fiber lasers in digital modulated optical communication systems is also studied.

Conformational flexibility of mephenesin.

The mephenesin molecule (3-(2-methylphenoxy)propane-1,2-diol) serves as a test bank to explore several structural and dynamical issues, such as conformational flexibility, the orientation of the carbon linear chain relative to the benzene plane, or the effect of substituent position on the rotational barrier of a methyl group. The molecule has been studied by rotational spectroscopy in the 4-18 GHz frequency range by Fourier-transform methods in a supersonic expansion. The experiment has been backed by a previous conformational search plus optimization of the lowest energy structures by ab initio and density functional quantum calculations. The three lowest-lying conformers that can interconvert to each other by simple bond rotations have been detected in the jet. Rotational parameters for all structures have been obtained, and methyl torsional barriers have been determined for the two lowest-lying rotamers. The lowest-lying structure of mephenesin is highly planar, with all carbon atoms lying nearly in the benzene ring plane, and is stabilized by the formation of cooperative intramolecular hydrogen bonding. An estimation of the relative abundance of the detected conformers indicates that the energetically most stable conformer will have an abundance near 80% at temperatures relevant for biological activity.

Multiplexing of six micro-displacement suspended-core Sagnac interferometer sensors with a Raman-Erbium fiber laser.

This work experimentally demonstrates a long-range optical fiber sensing network for the multiplexing of fiber sensors based on photonic crystal fibers. Specifically, six photonic crystal fiber sensors which are based on a Sagnac interferometer that includes a suspended-core fiber have been used. These sensors offer a high sensitivity for micro-displacement measurements. The fiber sensor network presents a ladder structure and its operation mode is based on a fiber ring laser which combines Raman and Erbium doped fiber amplification. Thus, we show the first demonstration of photonic crystal fiber sensors for remote measurement applications up to 75 km.

Optical fiber networks for remote fiber optic sensors.

This paper presents an overview of optical fiber sensor networks for remote sensing. Firstly, the state of the art of remote fiber sensor systems has been considered. We have summarized the great evolution of these systems in recent years; this progress confirms that fiber-optic remote sensing is a promising technology with a wide field of practical applications. Afterwards, the most representative remote fiber-optic sensor systems are briefly explained, discussing their schemes, challenges, pros and cons. Finally, a synopsis of the main factors to take into consideration in the design of a remote sensor system is gathered.

Remote (250 km) fiber Bragg grating multiplexing system.

We propose and demonstrate two ultra-long range fiber Bragg grating (FBG) sensor interrogation systems. In the first approach four FBGs are located 200 km from the monitoring station and a signal to noise ratio of 20 dB is obtained. The second improved version is able to detect the four multiplexed FBGs placed 250 km away, offering a signal to noise ratio of 6-8 dB. Consequently, this last system represents the longest range FBG sensor system reported so far that includes fiber sensor multiplexing capability. Both simple systems are based on a wavelength swept laser to scan the reflection spectra of the FBGs, and they are composed by two identical-lengths optical paths: the first one intended to launch the amplified laser signal by means of Raman amplification and the other one is employed to guide the reflection signal to the reception system.

Estado psicológico de los corredores populares de maratón en los días anteriores a la prueba / Psychological state of recreational marathon runners on the days prior to the race

En este estudio, se ha investigado el estado psicológico de corredores populares de maratón 65-12 horas antes de la prueba, en tres variables relevantes: ansiedad-estado somática, ansiedad-estado cognitiva y autoconfianza-estado. Los resultados han mostrado puntuaciones bajas en las dos variables de ansiedad y altas en autoconfianza, con correlaciones significativas negativas entre la autoconfianza y cada variable de ansiedad, y una correlación significativa positiva entre la ansiedad somática y la ansiedad cognitiva. También se encontró una correlación significativa negativa entre la ansiedad somática y la edad de los sujetos, y la ansiedad somática y la experiencia de los participantes, así como una correlación positiva entre la ansiedad somática y el mejor tiempo realizado en maratones anteriores. No se hallaron diferencias significativas en función de la proximidad de la prueba, y se observó un mejor funcionamiento psicológico en los corredores con mayor experiencia y mejor rendimiento previo (AU)

The present study has investigated the psychological state of recreational marathon runners 65-12 hours prior to the event, considering three relevant variables: somatic state-anxiety, cognitive state-anxiety, and state self-confidence. Results have shown low scores in both somatic and cognitive anxiety and high scores in self-confidence, with negative significant correlations between self-confidence and somatic anxiety, and self-confidence and cognitive anxiety, and a positive significant correlation between somatic and cognitive anxiety. Likewise, a negative significant correlation was found between somatic anxiety and age, and between somatic anxiety and the previous experience of the participants. A positive significant correlation was also found between somatic anxiety and the best time in previous marathon races. Finally,significant differences were not found considering the proximity of the race, and a better psychological functioning was observed in subjects with higher previous experience and better previous performance (AU)