Gate induced enhancement of spin-orbit coupling in dilute fluorinated graphene

We analyze the origin of spin-orbit coupling (SOC) in fluorinated graphene using Density Functional Theory (DFT) and a tight-binding model for the relevant orbitals. As it turns out, the dominant source of SOC is the atomic spin-orbit of fluorine adatoms and not the impurity induced SOC based on the distortion of the graphene plane as in hydrogenated graphene. More interestingly, our DFT calculations show that SOC is strongly affected by both the type and concentrations of the graphene's carriers, being enhanced by electron doping and reduced by hole doping. This effect is due to the charge transfer to the fluorine adatom and the consequent change in the fluorine-carbon bonding. Our simple tight-binding model, that includes the SOC of the $2p$ orbitals of F and effective parameters based on maximally localized Wannier functions, is able to account for the effect. The strong enhancement of the SOC induced by graphene doping opens the possibility to tune the spin relaxation in this material.Comment: 9 pages, 8 figure

Diffusion of fluorine adatoms on doped graphene

We calculate the diffusion barrier of fluorine adatoms on doped graphene in the diluted limit using Density Functional Theory. We found that the barrier $\Delta$ strongly depends on the magnitude and character of the graphene's doping ($\delta n$): it increases for hole doping ($\delta n<0$) and decreases for electron doping ($\delta n>0$). Near the neutrality point the functional dependence can be approximately by $\Delta=\Delta_0-\alpha\, \delta n$ where $\alpha\simeq6\times10^{-12}$ meVcm$^2$. This effect leads to significant changes of the diffusion constant with doping even at room temperature and could also affect the low temperature diffusion dynamics due to the presence of substrate induced charge puddles. In addition, this might open up the possibility to engineer the F dynamics on graphene by using local gates.Comment: 4 pages, 4 figure

Short communication: Effects of the addition of a marigold extract to diets fed to channel catfish (Ictalurus punctatus) on growth parameters

The expansion of aquaculture in the last 10 years has made it an important source of protein worldwide. However, increased production, and the culture intensification it carries, results in higher risk of infectious disease due to poor water quality and high stocking densities. ... Marigold (Tagetes erecta L.) is a plant native to Mexico whose flowers accumulate carotenoids. Natural carotenoids extracted from marigold have been used in aquaculture to help in the survival of fish juvenile stages by strengthening their immunological system, thus reducing mortality rates. The effect of carotenoids in fish health may exert a positive effect on fish growth indices; however, these effects on growth parameters have not been studied in channel catfish (Ictalurus punctatus), which is the most cultured fish species in north-eastern Mexico, and one of the most cultured on the southern United States. Consequently, the aim of this study was to investigate if there were significant differences in growth among channel catfish juveniles when fed diets containing various carotenoid doses from a natural source

Short communication: Effects of the addition of a marigold extract to diets fed to channel catfish (Ictalurus punctatus) on growth parameters

The expansion of aquaculture in the last 10 years has made it an important source of protein worldwide. However, increased production, and the culture intensification it carries, results in higher risk of infectious disease due to poor water quality and high stocking densities. ... Marigold (Tagetes erecta L.) is a plant native to Mexico whose flowers accumulate carotenoids. Natural carotenoids extracted from marigold have been used in aquaculture to help in the survival of fish juvenile stages by strengthening their immunological system, thus reducing mortality rates. The effect of carotenoids in fish health may exert a positive effect on fish growth indices; however, these effects on growth parameters have not been studied in channel catfish (Ictalurus punctatus), which is the most cultured fish species in north-eastern Mexico, and one of the most cultured on the southern United States. Consequently, the aim of this study was to investigate if there were significant differences in growth among channel catfish juveniles when fed diets containing various carotenoid doses from a natural source

Spatiotemporal changes in aerosol properties by hygroscopic growth and impacts on radiative forcing and heating rates during DISCOVER-AQ 2011

This research has been supported by the H2020 Marie Sklodowska-Curie Actions (grant no. 778349), the Spanish Ministry of Economy and Competitiveness (RTI2018101154.A.I00), and by the Russian Science Foundation (project 2117-00114, entitled Development of lidar retrieval algorithms).This work focuses on the characterization of vertically resolved aerosol hygroscopicity properties and their direct radiative effects through a unique combination of ground-based and airborne remote sensing measurements during the Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) 2011 field campaign in the Baltimore-Washington DC metropolitan area. To that end, we combined aerosol measurements from a multiwavelength Raman lidar located at NASA Goddard Space Flight Center and the airborne NASA Langley High Spectral Resolution Lidar-1 (HSRL-1) lidar system. In situ measurements aboard the P-3B airplane and ground-based Aerosol Robotic Network - Distributed Regional Aerosol Gridded Observational Network (AERONET-DRAGON) served to validate and complement quantifications of aerosol hygroscopicity from lidar measurements and also to extend the study both temporally and spatially. The focus here is on 22 and 29 July 2011, which were very humid days and characterized by a stable atmosphere and increasing relative humidity with height in the planetary boundary layer (PBL). Combined lidar and radiosonde (temperature and water vapor mixing ratio) measurements allowed the retrieval of the Hanel hygroscopic growth factor which agreed with that obtained from airborne in situ measurements and also explained the significant increase of extinction and backscattering with height. Airborne measurements also confirmed aerosol hygroscopicity throughout the entire day in the PBL and identified sulfates and water-soluble organic carbon as the main species of aerosol particles. The combined Raman and HSRL-1 measurements permitted the inversion for aerosol microphysical properties revealing an increase of particle radius with altitude consistent with hygroscopic growth. Aerosol hygroscopicity pattern served as a possible explanation of aerosol optical depth increases during the day, particularly for fine-mode particles. Lidar measurements were used as input to the libRadtran radiative transfer code to obtain vertically resolved aerosol radiative effects and heating rates under dry and humid conditions, and the results reveal that aerosol hygroscopicity is responsible for larger cooling effects in the shortwave range (7-10 W m(-2) depending on aerosol load) near the ground, while heating rates produced a warming of 0.12 K d(-1) near the top of PBL where aerosol hygroscopic growth was highest.H2020 Marie Sklodowska-Curie Actions 778349Spanish Ministry of Economy and Competitiveness RTI2018101154.A.I00Russian Science Foundation (RSF) 2117-0011

TiO2/Au/TiO2 multilayer thin-film photoanodes synthesized by pulsed laser deposition for photoelectrochemical degradation of organic pollutants

Most commonly employed anodes for photoelectrochemical degradation of organic contaminants in water are too thick, resulting in a low degradation efficiency due to the excessive electron-hole recombination. Multilayer-type TiO 2 /Au/TiO 2 nanocomposites have been prepared as photoanode thin films by pulsed laser deposition (PLD). The films were composed of six TiO 2 and five Au alternate layers, with total thickness of about 212 nm, aimed to optimize the absorption of photons and minimize the recombination. The influence of gold on the optical, structural, and chemical properties of the semiconductor nanocomposites was investigated. The band gap determined from Tauc model was 3.22 eV, close to that obtained by spectroscopic ellipsometry and lower than that of the TiO 2 film, revealing an enhancement of visible light absorption. The catalytic performance of PLD films was evaluated by using them as anodes in electro-oxidation (EO) and photoanodes in photoelectrocatalysis (PEC) to degrade 39-157 mg L ⁻¹ paracetamol in sulfate medium. The drug removal was very slow in EO, due to the low ability to form [rad] OH on the anode surface, which was significantly enhanced upon UVA irradiation in PEC. The presence of Cl ⁻ allowed a faster degradation by produced active chlorine. Finally, a hybrid process involving PEC + photoelectro-Fenton (PEF) with an air-diffusion cathode yielded total paracetamol decay in 4-5 min at an anodic potential of +4.0 V because of the efficient [rad] OH generation from Fenton's and photo-Fenton reactions. Hydroquinone, p-benzoquinone and hydroxylated products were detected during EO and PEC. The generation of active chlorine was confirmed by identifying a chlorinated derivative, N-(4-chloro-2-hydroxyphenyl)acetamide, in PEC + PEF treatment

CROMOSOMAS, LESIÓN DEL ADN Y MALFORMACIÓN NUCLEAR EN LA TORTUGA DULCEACUÍCOLA KINOSTERNON LEUCOSTOMUM (TESTUDINES: KINOSTERNIDAE)

Kinosternon leucostomum is one of the common freshwater turtles in Tabasco State, Mexico. However, studies of this species are limited for this region. The pollution in aquatic ecosystems from Tabasco is increasing and the effects on wildlife have not been properly made. Therefore, a chromosomic study and DNA lesion and nuclear malformation was performed in K. leucostomum from Tabasco. The karyotype in the turtle K. leucostomum is 34 msm/A + 22 T/C(2n=56 chromosomes). Also, intracellular malformations were identified: Chromosomes and DNA damage (micronucleus), binucleated cells, trinucleated cells, tetranucleated cells, cells in apoptosis and nucleoplasmic bridge, in irregular proportions. The probable origin of cell disorders is due to the presence of contaminants in aquatic ecosystems from Tabasco.La especie Kinosternon leucostomum, es una de las tortugas dulceacuícolas comunes del estado de Tabasco, México. Sin embargo, los estudios en esta especie son escasos para esta región. La contaminación en los ecosistemas acuáticos de Tabasco están aumentando cada vez más, y los efectos a la fauna silvestre no se han realizado adecuadamente. Por ello, se realizó un estudio cromosómico, de lesión de ADN y malformación nuclear en la especie K. leucostomum de Tabasco. El cariotipo en la tortuga K. leucostomum fue 34 msm/A + 22 T/C (2n=56 cromosomas). También, se identificaron malformaciones intracelulares: lesión del ADN y cromosomas (micronúcleos), células binucleadas, células trinucleadas, células tetranucleadas, células en apoptosis y puentes nucleoplásmicos, en proporciones irregulares. El origen probable de las alteraciones celulares es debido a la presencia de contaminantes en los ecosistemas acuáticos de Tabasco

Monitor de área pasivo para neutrones

La relevancia de la presencia de neutrones en los LINACs para radioterapia ha sido establecida en los reportes 79 y 102 de la NCRP1. La medición de la contribución de la dosis y su distribución en el paciente es importante para evaluar el riesgo de la inducción de tumores secundarios2. Para medir el espectro de neutrones o cualquier magnitud dosimétrica asociada, dentro de las salas de radioterapia con LINACs se debe usar un sistema pasivo3. En este trabajo se presenta el diseño de un monitor de área para neutrones con detector pasivo, así como su desempeño en un LINAC de 15 MV