Graphene Synthesis by Plasma-Enhanced CVD Growth with Ethanol

A modified route to synthesize graphene flakes is proposed using the Chemical Vapor Deposition (CVD) technique, by using copper substrates as supports. The carbon source used was ethanol, the synthesis temperature was 950°C and the pressure was controlled along the whole process. In this CVD synthesis process the incorporation of the carbon source was produced at low pressure and 950°C inducing the appearance of a plasma blue flash inside the quartz tube. Apparently, the presence of this plasma blue flash is required for obtaining graphene flakes. The synthesized graphene was characterized by different techniques, showing the presence of non-oxidized graphene with high purityThis work was supported by the Spanish Education and Research Ministry (MEC) under Grant MAT2010- 19804 and from Ministerio de Economía y Competitividad (MINECO) of Spain, through the grant ENE2014-57977-C2-1-R. Financial support from the U.S. Department of Energy, through the Massie Chair Project at Turabo University and from the U.S. Department of Defense under Grant W911NF-14-1- 0046, are also acknowledge

Remote Photonic THz Generation using an Optical Frequency Comb and Multicore Fiber

This paper proposes and demonstrates a photonic THz generation technique based on an optical frequency comb and multicore fiber (MCF) transmission, with the advantage of remote generation with great reconfigurability and reduced digital signal processing (DSP). The feasibility of the proposed technique is evaluated experimentally comparing the performance when transmitting a data wavelength and a local oscillator for optical heterodyning over a single core or over different cores in a 1-km MCF link. The proposed remote photonic THz generation technique is demonstrated employing a 16QAM 12.5 GBd signal. A short wireless transmission at 183 GHz center frequency with 0.25 m antenna-separation is achieved after 1 km MCF, meeting the soft-decision decision forward error correction (SD-FEC) bit error rate (BER) recommendation of 210-2. The analysis includes the received photocurrent range for which the BER meets the standard hard-decision forward error correction (HD-FEC) recommendation of 3.810-3 BER. The BER performance is analyzed considering different DSP configurations, with and without frequency offset estimation (FOE) and decision-driven least mean squares (DD LMS) equalization. The performance of the remote photonic THz generation technique is evaluated comparatively against traditional free-running laser transmission over MCF, confirming the advantage of using comb generation to reduce the frequency offset fluctuation and simplify the DSP

Multicore fiber-assisted photonic sub-THz generation for full-duplex wireless transmission

This paper evaluates experimentally a centralized radio access network (C-RAN) based on multi-core fiber (MCF) for the transmission of high-bandwidth signals in the sub-THz band. We compare the system performance when the data and carrier wavelengths to be mixed at the receiver for optical heterodyning are transmitted over the same or over different cores of a MCF link. Full-duplex transmission on MCF is evaluated using the same received wireless signal downconverted and transmitted back as uplink over the same carrier wavelength. The performance with different digital signal processing (DSP) configurations and with higher-power interference in the other cores are also analyzed in this work. Successful provision of 12.5 GBd 16QAM signals is achieved after 1-km of 7-core MCF transmission including a short wireless link at 182 GHz, obtained with optical heterodyning. C-RAN implementation with MCF simplifies the remote nodes as all the lasers can be located in the central office, while minimizing the number of lasers needed at the central office thanks to wavelength re-use. It also provides more flexibility to the system, as it enables using the same LO for different purposes (i.e. THz generation of other data or optical modulation for uplink transmission)

Microspheres for the growth of silicon nanowires via vapor-liquid-solid mechanism

Silicon nanowires have been synthesized by a simple process using a suitable support containing silica and carbon microspheres. Nanowires were grown by thermal chemical vapor deposition via a vapor-liquid-solid mechanism with only the substrate as silicon source. The curved surface of the microsized spheres allows arranging the gold catalyst as nanoparticles with appropriate dimensions to catalyze the growth of nanowires. The resulting material is composed of the microspheres with the silicon nanowires attached on their surfaceThis work was supported by MICINN research Project MAT2010-19804. Financial support fromthe US Department of Energy through the Massie Chair project at University of Turabo is also acknowledged.The work of Arancha Gómez-Martínez was supported by the FPI fellowship from the Universidad Autónoma de Madrid.The authors thank I. Poveda for his technical assistance. The “Servicio Interdepartamental de Investigación (SIdI)” a tUniversidad Autónoma de Madrid and “Centro Nacional de Microscopía Español” (CNME) at Universidad Complutense deMadrid are also acknowledge

Photonic integrated circuits employing multi-core fiber for broadband radio beamsteering (Invited)

This paper presents an optical beamforming network based on a photonic integrated circuit employing a weaklycoupled multi-core fiber to connect the different antenna elements. The proposed beamformer enables a centralized control of the resulting steering angle. By means of wavelength tuning, fast and dynamic configuration of the induced delay (and associated beam steering angle) is achieved remotely. The experimental results confirm high throughput transmission (> 10 Gbps) with electrical data signals with up to 3GHz bandwidth in the 24 GHz RF band (K-band). Wireless transmission of 16QAM-modulated, 1.5 GHz-wide signals is demonstrated in the laboratory from –26˚ to 33˚ providing a scanning range of 59˚

Tri-axial accelerometry shows differences in energy expenditure and parental effort throughout the breeding season in long-lived raptors

Cutting-edge technologies are extremely useful to develop new workflows in studying ecological data, particularly to understand animal behavior and movement trajectories at the individual level. Although parental care is a well-studied phenomenon, most studies have been focused on direct observational or video recording data, as well as experimental manipulation. Therefore, what happens out of our sight still remains unknown. Using high-frequency GPS/GSM dataloggers and tri-axial accelerometers we monitored 25 Bonelli’s eagles Aquila fasciata during the breeding season to understand parental activities from a broader perspective. We used recursive data, measured as number of visits and residence time, to reveal nest attendance patterns of biparental care with role specialization between sexes. Accelerometry data interpreted as the overall dynamic body acceleration, a proxy of energy expenditure, showed strong differences in parental effort throughout the breeding season and between sexes. Thereby, males increased substantially their energetic requirements, due to the increased workload, while females spent most of the time on the nest. Furthermore, during critical phases of the breeding season, a low percentage of suitable hunting spots in eagles’ territories led them to increase their ranging behavior in order to find food, with important consequences in energy consumption and mortality risk. Our results highlight the crucial role of males in raptor species exhibiting biparental care. Finally, we exemplify how biologging technologies are an adequate and objective method to study parental care in raptors as well as to get deeper insight into breeding ecology of birds in general.This work was supported by Red Eléctrica de España, Iberdrola Foundation, and Wildlife Service of the Valencian Community Regional Government (Conselleria d’Agricultura, Desenvolupament Rural, Emergència Climàtica i Transició Ecològica, Generalitat Valenciana, Spain). A.M.P. and J.M.E. were supported by predoctoral grants of the University of Valencia [Grant Number 0113/2019] and the Basque Government [Grant Number PRE_2018_2_0112], respectively

The Impact of Suicide Bereavement on Educational and Occupational Functioning: A Qualitative Study of 460 Bereaved Adults.

People bereaved by suicide are at an increased risk of suicide and of dropping out of education or work. Explanations for these associations are unclear, and more research is needed to understand how improving support in educational or work settings for people bereaved by suicide might contribute to reducing suicide risk. Our objective was to explore the impact of suicide on occupational functioning. We conducted a cross-sectional online study of bereaved adults aged 18-40, recruited from staff and students of British higher educational institutions in 2010. We used thematic analysis to analyse free text responses to two questions probing the impact of suicide bereavement on work and education. Our analysis of responses from 460 adults bereaved by suicide identified three main themes: (i) specific aspects of grief that impacted on work performance, cognitive and emotional domains, and social confidence; (ii) structural challenges in work or educational settings including a lack of institutional support, the impact of taking time off, and changes to caring roles; and (iii) new perspectives on the role of work, including determination to achieve. Institutional support should be tailored to take account of the difficulties and experiences described

Development of a Low-Cost Optical Sensor to Detect Eutrophication in Irrigation Reservoirs

[EN] In irrigation ponds, the excess of nutrients can cause eutrophication, a massive growth of microscopic algae. It might cause different problems in the irrigation infrastructure and should be monitored. In this paper, we present a low-cost sensor based on optical absorption in order to determine the concentration of algae in irrigation ponds. The sensor is composed of 5 LEDs with different wavelengths and light-dependent resistances as photoreceptors. Data are gathered for the calibration of the prototype, including two turbidity sources, sediment and algae, including pure samples and mixed samples. Samples were measured at a different concentration from 15 mg/L to 4000 mg/L. Multiple regression models and artificial neural networks, with a training and validation phase, are compared as two alternative methods to classify the tested samples. Our results indicate that using multiple regression models, it is possible to estimate the concentration of alga with an average absolute error of 32.0 mg/L and an average relative error of 11.0%. On the other hand, it is possible to classify up to 100% of the samples in the validation phase with the artificial neural network. Thus, a novel prototype capable of distinguishing turbidity sources and two classification methodologies, which can be adapted to different node features, are proposed for the operation of the developed prototype.This work is partially funded by the Ministerio de Educacion, Cultura y Deporte through the"Ayudas para contratacion pre-doctoral de Formacion del Profesorado Universitario FPU (Convocatoria 2016)" grant number FPU16/05540 and by the Conselleria de Educacion, Cultura y Deporte through the "Subvenciones para la contratacion de personal investigador en fase postdoctoral", grant number APOSTD/2019/04.Rocher-Morant, J.; Parra-Boronat, L.; Jimenez, JM.; Lloret, J.; Basterrechea-Chertudi, DA. (2021). Development of a Low-Cost Optical Sensor to Detect Eutrophication in Irrigation Reservoirs. Sensors. 21(22):1-20. https://doi.org/10.3390/s21227637S120212