Experimental magnetic form factors in Co3V2O8: A combined study of ab initio calculations, magnetic Compton scattering and polarized neutron diffraction

We present a combination of ab initio calculations, magnetic Compton scattering and polarized neutron experiments, which elucidate the density distribution of unpaired electrons in the kagome staircase system Co3V2O8. Ab initio wave functions were used to calculate the spin densities in real and momentum space, which show good agreement with the respective experiments. It has been found that the spin polarized orbitals are equally distributed between the t2g and the eg levels for the spine (s) Co ions, while the eg orbitals of the cross-tie (c) Co ions only represent 30% of the atomic spin density. Furthermore, the results reveal that the magnetic moments of the cross-tie Co ions, which are significantly smaller than those of the spine Co ions in the zero-field ferromagnetic structure, do not saturate by applying an external magnetic field of 2 T along the easy axis a, but that the increasing bulk magnetization originates from induced magnetic moments on the O and V sites. The refined individual magnetic moments are mu(Co_c)=1.54(4) mu_B, mu(Co_s)=2.87(3) mu_B, mu(V)=0.41(4) mu_B, mu(O1)=0.05(5) mu_B, mu(O2)=0.35(5) mu_B, and; mu(O3)=0.36(5) mu_B combining to the same macroscopic magnetization value, which was previously only attributed to the Co ions

New strategies invonving upconverting nanoparticles for determining moderate temperatures by luminescence thermometry

Producción CientíficaHere we analyze alternative luminescence thermometry techniques to FIR, such as intensity ratio luminescence thermometry between the emission arising from two electronic levels that are not necessarily thermally coupled, but that show different evolutions with temperature, and lifetime luminescence nanothermometry in (Ho,Tm,Yb):KLu(WO4)2 and (Er,Yb):NaY2F5O nanoparticles. (Ho,Tm,Yb):KLu(WO4)2 nanoparticles exhibited a maximum relative sensitivity of 0.61% K−1, similar to that achievable in Er-doped systems, which are the upconverting systems presenting the highest sensitivity. From another side, (Er,Yb):NaY2F5O nanocrystals show great potentiality as thermal sensors at the nanoscale for moderate temperatures due to the incorporation of additional non-radiative relaxation mechanisms that shorten the emission lifetime generated by the oxygen present in the structure when compared to (Er,Yb):NaYF4 nanoparticles exhibiting the highest upconversion efficiency. We used those nanoparticles for ex-vivo temperature determination by laser induced heating in chicken breast using lifetime-based thermometry. The results obtained indicate that these techniques might constitute alternatives to FIR with potential applications for the determination of moderate temperatures, with sensitivities comparable to those that can be achieved by FIR or even higher.Ministerio de Economía, Industria y Competitividad (Projects MAT2013-47395-C4-1-4-R, and TEC2014-55948-R)Catalan Government (Projects no. 2014SGR1358 and 2013FI_B 01032

Effect of Azospirillum brasilense coinoculated with Rhizobium on Phaseolus vulgaris flavonoids and Nod factor production under salt stress

The effects of salt upon Azospirillum brasilense strain Cd on plant growth, nodulation, flavonoid and lipochitooligosaccharide (LCOs-Nod factor) production, were sequentially followed after 4, 7 and 14 days during a Rhizobium-Phaseolus vulgaris cv. Negro Jamapa interaction, in a hydroponics growth system. Azospirillum brasilense promoted root branching in bean seedling roots and increased secretion of nodgene-inducing flavonoid species, as detected by high-performance liquid chromatography (HPLC). The results also support that A. brasilense allows a longer, more persistent exudation of flavonoids by bean roots. A general positive effect of Azospirillum-Rhizobium coinoculation on the expression of nod-genes by Rhizobium tropici CIAT899 and Rhizobium etli ISP42, and on nodulation factor patterns, was observed in the presence of root exudates. The negative effects obtained under salt stress on nod-gene expression and on Nod factors’ appearance were relieved in coinoculated plants.Fil: Dardanelli, Marta Susana. Universidad de Sevilla; España. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Fernández de Córdoba, Francisco J.. Universidad de Sevilla; EspañaFil: Espuny, M. Rosario. Universidad de Sevilla; EspañaFil: Rodríguez Carvajal, Miguel A.. Universidad de Sevilla; EspañaFil: Soria Díaz, María E.. Universidad de Sevilla; EspañaFil: Gil Serrano, Antonio M.. Universidad de Sevilla; EspañaFil: Okon, Yaacov. The Hebrew University of Jerusalem; IsraelFil: Megías, Manuel. Universidad de Sevilla; Españ

Fabrication of p-type porous GaN on silicon and epitaxial GaN

Abstract : Porous GaN layers are grown on silicon from gold or platinum catalyst seed layers, and self-catalyzed on epitaxial GaN films on sapphire. Using a Mg-based precursor, we demonstrate p-type doping of the porous GaN. Electrical measurements for p-type GaN on Si show Ohmic and Schottky behavior from gold and platinum seeded GaN, respectively. Ohmicity is attributed to the formation of a Ga2Au intermetallic. Porous p-type GaN was also achieved on epitaxial n-GaN on sapphire, and transport measurements confirm a p-n junction commensurate with a doping density of 1018 cm 3. Photoluminescence and cathodoluminescence confirm emission from Mg-acceptors in porous p-type GaN

Reptiles y aves del Distrito de Manejo Integrado Cabo Manglares Bajo Mira-Frontera, Pacífico colombiano

We evaluated the diversity of reptiles and birds in the Distrito de Manejo Integrado de Cabo Manglares Bajo Mira-Frontera, department of Nariño, Colombia, through samplings carried out in November 2018. We carried out time-constrained searches for reptiles, and free route and observation points for birds. We obtained 25 records of reptiles, belonging to three orders, 17 families, 23 genera and 24 species. For birds, we recorded 179 individuals, belonging to 16 orders, 40 families, 106 genera and 119 species. The records of the turtles Lepidochelys olivacea, categorized as Vulnerable, and Chelonia mydas, Endangered, stand out for reptiles, as well as the species Caiman crocodilus and Boa constrictor, included in Appendix II of CITES. The records of 31 migratory species stand out for birds, as well as three Near Threatened species (Ramphastos ambiguus, Campephilus gayaquilensis, Capito squamatus).Evaluamos la diversidad de reptiles y aves en el Distrito de Manejo Integrado de Cabo Manglares Bajo Mira-Frontera, en el departamento de Nariño, Colombia, mediante muestreos hechos en noviembre de 2018. Para reptiles se realizaron búsquedas libres delimitadas por tiempo; para aves, se realizaron recorridos libres y puntos de observación. Se obtuvieron 25 registros de reptiles pertenecientes a tres órdenes, 17 familias, 23 géneros y 24 especies. De aves se registraron 179 individuos pertenecientes a 16 órdenes, 40 familias, 106 géneros y 119 especies. Para reptiles se destacan los registros de las tortugas Lepidochelys olivacea, categorizada como Vulnerable, y Chelonia mydas, En Peligro, y las especies Caiman crocodilus y Boa constrictor, incluidas en el apéndice II de CITES. Para las aves se destacan los registros de 31 especies migratorias, y tres especies Casi Amenazadas (Ramphastos ambiguus, Campephilus gayaquilensis, Capito squamatus)

Toll-Like Receptors in Secondary Obstructive Cholangiopathy

Secondary obstructive cholangiopathy is characterized by intra- or extrahepatic bile tract obstruction. Liver inflammation and structural alterations develop due to progressive bile stagnation. Most frequent etiologies are biliary atresia in children, and hepatolithiasis, postcholecystectomy bile duct injury, and biliary primary cirrhosis in adults, which causes chronic biliary cholangitis. Bile ectasia predisposes to multiple pathogens: viral infections in biliary atresia; Gram-positive and/or Gram-negative bacteria cholangitis found in hepatolithiasis and postcholecystectomy bile duct injury. Transmembrane toll-like receptors (TLRs) are activated by virus, bacteria, fungi, and parasite stimuli. Even though TLR-2 and TLR-4 are the most studied receptors related to liver infectious diseases, other TLRs play an important role in response to microorganism damage. Acquired immune response is not vertically transmitted and reflects the infectious diseases history of individuals; in contrast, innate immunity is based on antigen recognition by specific receptors designated as pattern recognition receptors and is transmitted vertically through the germ cells. Understanding the mechanisms for bile duct inflammation is essential for the future development of therapeutic alternatives in order to avoid immune-mediated destruction on secondary obstructive cholangiopathy. The role of TLRs in biliary atresia, hepatolithiasis, bile duct injury, and primary biliary cirrhosis is described in this paper

Resistencia antimicrobiana de cepas de Escherichia coli aisladas de contenidos de bursa de Fabricio de aves para engorde

The aim of this study was to determine the percentage of sensitivity or resistance of strains of E. coli isolated from asymptomatic broiler chicken against 18 common antibiotics used in poultry and in human medicine. In addition, strains that produce extended-spectrum beta-lactamases (ESBL) from a farm or slaughterhouses in the poultry area of Santander, Colombia. The circulation of strains resistant to beta-lactams, cephalosporins, aminoglycosides, quinolones and sulfonamides was determined, as well as antibiotics widely used in other non-farm environments. The content of the bursa of Fabricius was cultivated in McConkey agar obtaining 46 strains of E. coli. Susceptibility tests (n=18) were conducted to the isolated strains, and 91% of the strains were resistant to ampicillin and 80% to cephalosporins. The association of antibiotics with beta-lactamase inhibitors (ampicillin sulbactam and amoxicillin / clavulanic acid) showed 30% resistance. The double disc test was used to evaluate the presence of strains of E. coli producing extendedspectrum beta-lactamases (ESBL) confirming its presence in 63% of the samples. Results showed the presence of E. coli strains in asymptomatic chicken broilers with high antimicrobial resistance, including expression of ESBL.El objetivo de la presente investigación fue determinar el porcentaje de sensibilidad o resistencia de cepas de E. coli aisladas de pollo de engorde asintomático frente a 18 antibióticos comunes utilizados en avicultura y medicina humana; a su vez, cepas productoras de betalactamasas de espectro extendido (BLEES), procedentes de granja o plantas de beneficio de la zona avícola de Santander, Colombia. Se determinó la circulación de cepas resistentes a betalactámicos, cefalosporinas, aminoglucósidos, quinolonas y sulfonamidas, así como antibióticos de amplio uso en ambientes ajenos a las granjas. Se aislaron 46 cepas de E. coli del contenido de bolsas de Fabricio de 100 pollos de engorde entre 2 y 6 semanas de edad (20 procedentes de una granja avícola y 80 de una planta de sacrificio) en Santander, Colombia. Las muestras fueron cultivadas en agar McConkey. Se realizaron pruebas de sensibilidad a las cepas aisladas con 18 antimicrobianos. El 91% de las cepas fueron resistentes a la ampicilina y el 80% a las cefalosporinas; así mismo, al enfrentar las cepas con la asociación de antibióticos con inhibidores de betalactamasas (ampicilina sulbactam y amoxacilina/ácido clavulánico), se encontró 30% de resistencia. Se utilizó la prueba del doble disco para evaluar la presencia de cepas de E. coli productoras de betalactamasas de espectro extendido (BLEES) confirmando su presencia en el 63% de las muestras. Se evidencia la presencia de cepas de E. coli en aves de engorde asintomáticas, con alta resistencia antimicrobiana, incluyendo expresión de BLEES

Mapping Temperature Distribution Generated by Photothermal Conversion in Graphene Film Using Er,Yb:NaYF4 Nanoparticles Prepared by Microwave-Assisted Solvothermal Method

This study analyzes the mapping of temperature distribution generated by graphene in a glass slide cover after illumination at 808 nm with a good thermal resolution. For this purpose, Er,Yb:NaYF4 nanoparticles prepared by a microwave-assisted solvothermal method were used as upconversion luminescent nanothermometers. By tuning the basic parameters of the synthesis procedure, such as the time and temperature of reaction and the concentration of ethanol and water, we were able to control the size and the crystalline phase of the nanoparticles, and to have the right conditions to obtain 100% of the β hexagonal phase, the most efficient spectroscopically. We observed that the thermal sensitivity that can be achieved with these particles is a function of the size of the nanoparticles and the crystalline phase in which they crystallize. We believe that, with suitable changes, these nanoparticles might be used in the future to map temperature gradients in living cells while maintaining a good thermal resolution

Alimentos funcionales, alfalfa y fitoestrógenos

Functional food development has been increased during the last years due to the population interest in foods that have not only a nutritional function but a health benefit as well reducing the risk of suffering several diseases. Alfalfa has been intended as cattle feed, although several investigations have reported that alfalfa contains bioactive compounds –phytochemicals- proteins with an estrogenic effect, and antimicrobial and antioxidant compounds, being classified as a functional food with protection against cancer, diabetes and cardiovascular and other diseases. The aim of the present study is to offer a general information outline, through a bibliographic review, of functional foods status, focusing on alfalfa and its phytochemicals (phytoestrogens), compounds that give it its functional food character and its adverse effects shown in the reproductive system of experimental animals as well. Such dichotomy between adverse and beneficial effects is the sign that shows that it is needed more information and more studies to be done in order to establish the effect of phytoestrogens in the development and reproductive function in animals, its agonistic and antagonistic effect and risk-benefit balance in its consumption.El desarrollo de alimentos funcionales en los últimos años ha ido en aumento debido principalmente, al interés de la población por alimentos que no solo cumplan con la función nutricional sino también por que tengan un efecto benéfico en salud reduciendo así el riesgo a padecer diversas enfermedades. La alfalfa ha sido generalmente un alimento destinado para la alimentación del ganado, sin embargo, en diversas investigaciones alrededor del mundo se ha reportado que contiene compuestos bioactivos –fitoquímicos– y proteínas con efecto estrogénico, antimicrobiano y antioxidante, así como también protector contra enfermedades cardiovasculares, cáncer y diabetes, entre otras, clasificándola potencialmente como un alimento funcional. El presente documento tiene como objetivo dar un bosquejo general informativo a través de la búsqueda y revisión bibliográfica acerca de los alimentos funcionales y en especial de la alfalfa y constituyentes fitoquímicos (fitoestrógenos) que la ubican dentro de este grupo de alimentos; así como los hallazgos que se han reportado como efectos adversos en animales experimentales específicamente en el aparato reproductivo debido al consumo de este tipo de fitocompuestos. Esta dicotomía entre los efectos adversos y benéficos no es más que la señalización de que aún falta mucha más información y estudios que realizar respecto al resultado que pueden tener los fitoestrógenos en el desarrollo y función reproductiva de animales, el agonismo y antagonismo de su efecto así como la concordancia en el riesgo-beneficio de su consumo