Naturaleza de los radicales libres de alanina

En la actualidad la Resonancia Paramagnética Electrónica (RPE) de la alanina (CH3CH(NH2)COOH) irradiada, es la base del sistema dosimétrico Alanina/RPE que se utiliza para controlar procesos de irradiación a nivel industrial y a nivel terapéutico. En este sistema dosimétrico generalmente se mide la intensidad de la línea central . del patrón de polvos de RPE de los radicales libres de alanina (el CH3 e HCOOH y posiblemente otras especies), inducidos previamente por radiaci6n ionizante, para luego relacionar esta intensidad con la dosis absorbida. El origen del patrón de polvos de RPE de la alanina irradiada, base de este sistema dosimétrico hasta ahora, sin embargo, no ha sido perfectamente interpretado. En este trabajo se analizan su estructura y su origeri. Como antecedentes se puede mencionar que, en general, se acepta que algunas de las señales de resonancia que aparecen en el espectro de RPE son debidas a . la especie de radical libre CH3 e HR (R = CO2). en donde el griJpo amino NH2 de la alanina CH3CH(NH2)R es eliminado por el efecto de la radiación (Miyagawa and Gordy, 1960, 1962 ; Morton et al., 1961 ). Por otra parte, también existen evidencias experimentales de que se pueden inducir especies secundarias de radicales libres (Brustad et al., 1964; Samskog et al., 1980 ; Kuroda et al., 1982 ; Matsuki et al., 1982 ; Cabral Prieto et al., 1994 ; Pilbrow et al., 1996; Vitaly et al., 1996) y/o defectos cristalin,:,s (Kuroda et al., 1982 ; Hófer et al., 1989 ; Nakagawa et al., 1993 ; Brustolon et al., 1994) al irradiar alanina con radiación ionizante. Un rasgo espectral adicional del patrón de polvos de RPE de l0s radicales libres de alanina son las denominadas líneas satélite, debidas a transiciones de baja probabilidad (prohibidas por la regla de selección de espin, .1m1 = ± 1) , que aparecen en el espectro (Miyagawa and Gordy, 1960 ; Hófer et al., 1989 ; Arber et al., 1991 ; Barnard et al., 1996; presente trabajo). Si bien e'5taf, líneas satélite ya fueron identificadas, a partir de su medición surge una señalización mas sistemática de ellas. La asignación de estas líneas como satélite aún, sin embargo, presenta controversias. A partir del. estudio de esas líneas satélite en este trabajo, se muestran evidencias adicionales sobre la generación de al menos cuatro especies secundarias de radicales libres al irradiar, a temperatura ambiente, muestras de alanina policristalina. Esto último, como resultado del análisis numérico de convolución y deconvolución que se realiza a los espectrcs de RPE que se observan después de tratar a los radicales de alanina con luz UV y calor. Por otra parte, cuando se analiza el efecto que tiene el sili cón (rr.aterial aglutinante que se utiliza para producir el dosímetro de alanina del LFAM c1el ININ1) sobre la generación de los radicales libres al irradiar alanina, se obtienen evidencias de que este material aglutinante (el silicón) inhibe la formación de al menos (i) una especie secundaria de radicales libres y/o (ii) de defectos cristalinos. Como parte de este trabajo y en el contexto de los datos experimentales sobre el efecto del aglutinante (silicón), el efecto de otros aglutinantes (como parafina y otros polímeros, etc.) podrá también estudiarse para ampliar el estudio de la naturaleza de los radicales libres que se inducen al irradiar muestras de ala 1ina aglutinada. Dado que la técnica de deconvolución, para aumentar la resolL:ción espectral, es una herramienta básica de este trabajo, se reporta la comp::lración entre dos métodos numéricos de deconvolución (uno aproximado y otro no aproximado), mostrando la utilidad de dichas técnicas de análisis para los casos en donde existe una gran superposición de señales espectrales. Adicionalmente a esta comparación, entre métodos de deconvolución (Cabral Prieto et al., 1991, 1993, 1994 ; Hedberg y Ehrnberg, 1968), la técnica de deconvolución es mejorada al poder eliminar señales de alta frecuencia que pueden aparecer en los espectros deconvolucionados ; esto es, como resultado del proceso numérico de deconvolución

Effect of the Fe Nanoparticles Generated by Pulsed Plasma in Liquid in the Catalyzed Ozone Removal of Phenolphthalein

We have synthesized, in this work, zero valent iron (ZVI) nanoparticles to improve the efficiency of degradation of phenolphthalein catalyzed by ozone in aqueous solution. The Fe nanoparticles were obtained using the pulsed plasma in liquid (PPL) method with water as the liquid medium. Such nanoparticles have a mean size of 12 nm and are composed of ~80% Fe0, while the rest are a mixture of Fe+2 and Fe+3 oxides. The degradation of phenolphthalein was carried on a glass reactor injecting a constant amount of ozone and introducing different concentrations of Fe nanoparticles to the system. When using pure ozone, the percentage of degradation of phenolphthalein measured by colorimetry after one hour of reaction was 84%. However, when Fe nanoparticles are used, such percentage can be as high as 98% in 50 minutes of reaction. Furthermore, the degradation rate constant was 0.0334 min−1 with only ozone and it can be as high as 0.0733 min−1 with Fe nanoparticles. Finally, the total mineralization of phenolphthalein was obtained by total organic carbon (TOC) determinations. It is shown that when using only ozone, we obtained a percentage of mineralization of 49% and 96% when using the highest concentration of Fe nanoparticles

Synthesis and characterization of nanometric magnetite coated by oleic acid and the surfactant CTAB

For the intermediate and largest particles a mixture of magnetite and maghemite phases were produced as the saturation magnetization values of MS ∼ 60 emu/g indicated; these values were measured for most samples, independently of the coating surfactant concentration, and according to the ZFC-FC curves the blocking temperatures were 225K and 275K for the smallest and largest magnetite nanoparticles, respectively. The synthesis method was highly reproducible.Nanometric magnetite (nm-Fe3O4) particles were prepared by the reverse co-precipitation synthesis method, obtaining particle sizes that ranged from 4 to 8.5 nm. In their synthesis, the concentration of iron salts of ferric nitrate, Fe(NO3)3⋅9H2O, and ferrous sulfate, FeSO4⋅7H2O, were varied relative to the chemical reaction volume and by using different surfactants such as oleic acid (OA) and hexadecyltrimethylammonium bromide (CTAB). The nm-Fe3O4 particles were characterized by transmission electron microscopy (TEM), Mössbauer spectroscopy (MS), magnetic and X-ray diffraction (XRD) measurements

Hyperthermia studies using inductive and ultrasound methods on E. coli bacteria and mouse glioma cells

The survival of Escherichia coli bacteria and mouse glioma cells were studied under different temperatures using direct heating in water, ultrasound, and magnetic fluid hyperthermia. The survival of these microorganisms depended on whether the heating mode was continuous or discontinuous, surviving more in the former than in the discontinuous heating mode. Whereas Escherichia coli bacteria did not survive at temperatures ≥50∘C, the mouse glioma cells did not survive at temperatures ≥48∘C

Orange peel + nanostructured zero-valent-iron composite for the removal of hexavalent chromium in water

In this work we used the Pulsed Plasma in Liquid technique to synthesize zero-valent iron nanostructures. We used a DC Power Source to produce such plasma on water and methanol. The obtained particles were characterized by TEM to determine their shape and size and Mossbauer Spectroscopy to investigate the chemical state of the iron present. We found that 80% of the particles produced in water are composed of metallic iron and when methanol is used 97% of the particles are metallic iron. Once the Fe colloid was formed, orange skin was impregnated with these nanostructures for the removal of in water solution. The Cr(VI) removal experiments were done in a batch system in the presence of the composites at an inicial concentration of 50 ppm of Cr(VI). When using the iron nanostructures supported on the orange peel, the percentage of removal is 100% in the case of nanostructures formed in water and 96% when obtained in methanol

Spectroscopic and mechanical studies on the Fe-based amorphous alloy 2605SA1

The Vickers micro-hardness of this alloy was unusually dependent on the heat treatment from 300 to 634K, inferring important micro-structural changes and the presence of amorphous grains before its phase transition. Once the alloy is crystallized, the micro-hardness is characteristic of a brittle alloy, the main problem of these alloys. Within the amorphous state, other properties like free-volume, magnetic states and Fe-Fe distances were followed by PALS and MS, respectively, to analyze those micro-structural changes, thermally induced, which are of paramount interest to understand their brittleness problem

Fungal planet description sheets: 625-715

Novel species of fungi described in this study include those from various countries as follows: Australia:Apiognomonia lasiopetali on Lasiopetalum sp Blastacervulus eucalyptorum on Eucalyptus adesmophloia,Bullanockia australis (incl. Bullanockia gen. nov.) on Kingia australis, Caliciopsis eucalypti on Eucalyptus marginata, Celerioriella petrophiles on Petrophile teretifolia, Coleophoma xanthosiae on Xanthosia rotundifolia, Coniothyrium hakeae on Hakea sp Diatrypella banksiae on Banksia formosa, Disculoides corymbiae on Corymbia calophylla, Elsinoë eelemani on Melaleuca alternifolia, Elsinoë eucalyptigena onEucalyptus kingsmillii, Elsinoë preissianae on Eucalyptus preissiana, Eucasphaeria rustici on Eucalyptus creta, Hyweljonesia queenslandica (incl. Hyweljonesia gen. nov.) on the cocoon of an unidentified microlepidoptera, Mycodiella eucalypti (incl. Mycodiella gen. nov.) on Eucalyptus diversicolor,Myrtapenidiella sporadicae on Eucalyptus sporadica, Neocrinula xanthorrhoeae (incl. Neocrinula gen. nov.) on Xanthorrhoea sp, Ophiocordyceps nooreniae on dead ant, Phaeosphaeriopsis agavacearum on Agavesp, Phlogicylindrium mokarei on Eucalyptus sp, Phyllosticta acaciigena on Acacia suaveolens,Pleurophoma acaciae on Acacia glaucoptera, Pyrenochaeta hakeae on Hakea sp, Readeriella lehmannii onEucalyptus lehmannii, Saccharata banksiae on Banksia grandis, Saccharata daviesiae on Daviesia pachyphylla, Saccharata eucalyptorum on Eucalyptus bigalerita, Saccharata hakeae on Hakea baxteri,Saccharata hakeicola on Hakea victoria, Saccharata lambertiae on Lambertia ericifolia, Saccharata petrophiles on Petrophile sp, Saccharata petrophilicola on Petrophile fastigiata, Sphaerellopsis hakeae onHakea sp, and Teichospora kingiae on Kingia australis. Brazil: Adautomilanezia caesalpiniae (incl. Adautomilanezia gen. nov.) on Caesalpina echinata, Arthrophiala arthrospora (incl. Arthrophiala gen. nov.) on Sagittaria montevidensis, Diaporthe caatingaensis (endophyte from Tacinga inamoena), Geastrum ishikawae on sandy soil, Geastrum pusillipilosum on soil, Gymnopus pygmaeus on dead leaves and sticks,Inonotus hymenonitens on decayed angiosperm trunk, Pyricularia urashimae on Urochloa brizantha, andSynnemellisia aurantia on Passiflora edulis. Chile: Tubulicrinis australis on Lophosoria quadripinnata.France: Cercophora squamulosa from submerged wood, and Scedosporium cereisporum from fluids of a wastewater treatment plant. Hawaii: Beltraniella acaciae, Dactylaria acaciae, Rhexodenticula acaciae,Rubikia evansii and Torula acaciae (all on Acacia koa). India: Lepidoderma echinosporum on dead semi-woody stems, and Rhodocybe rubrobrunnea from soil. Iran: Talaromyces kabodanensis from hypersaline soil.La Réunion: Neocordana musarum from leaves of Musa sp. Malaysia: Anungitea eucalyptigena onEucalyptus grandis × pellita, Camptomeriphila leucaenae (incl. Camptomeriphila gen. nov.) on Leucaena leucocephala, Castanediella communis on Eucalyptus pellita, Eucalyptostroma eucalypti (incl.Eucalyptostroma gen. nov.) on Eucalyptus pellita, Melanconiella syzygii on Syzygium sp, Mycophilomyces periconiae (incl. Mycophilomyces gen. nov.) as hyperparasite on Periconia on leaves of Albizia falcataria,Synnemadiella eucalypti (incl. Synnemadiella gen. nov.) on Eucalyptus pellita, and Teichospora nephelii onNephelium lappaceum. Mexico: Aspergillus bicephalus from soil. New Zealand: Aplosporella sophorae onSophora microphylla, Libertasomyces platani on Platanus sp, Neothyronectria sophorae (incl.Neothyronectria gen. nov.) on Sophora microphylla, Parastagonospora phoenicicola on Phoenix canariensis, Phaeoacremonium pseudopanacis on Pseudopanax crassifolius, Phlyctema phoenicis onPhoenix canariensis, and Pseudoascochyta novae-zelandiae on Cordyline australis. Panama: Chalara panamensis from needle litter of Pinus cf. caribaea. South Africa: Exophiala eucalypti on leaves ofEucalyptus sp, Fantasmomyces hyalinus (incl. Fantasmomyces gen. nov.) on Acacia exuvialis,Paracladophialophora carceris (incl. Paracladophialophora gen. nov.) on Aloe sp, and Umthunziomyces hagahagensis (incl. Umthunziomyces gen. nov.) on Mimusops caffra. Spain: Clavaria griseobrunnea on bare ground in Pteridium aquilinum field, Cyathus ibericus on small fallen branches of Pinus halepensis, Gyroporus pseudolacteus in humus of Pinus pinaster, and Pseudoascochyta pratensis (incl. Pseudoascochyta gen. nov.) from soil. Thailand: Neoascochyta adenii on Adenium obesum, and Ochroconis capsici on Capsicum annuum. UK: Fusicolla melogrammae from dead stromata of Melogramma campylosporum on bark ofCarpinus betulus. Uruguay: Myrmecridium pulvericola from house dust. USA: Neoscolecobasidium agapanthi (incl. Neoscolecobasidium gen. nov.) on Agapanthus sp, Polyscytalum purgamentum on leaf litter,Pseudopithomyces diversisporus from human toenail, Saksenaea trapezispora from knee wound of a soldier, and Sirococcus quercus from Quercus sp. Morphological and culture characteristics along with DNA barcodes are provided. © 2017 Naturalis Biodiversity Center & Westerdijk Fungal Biodiversity Institute

NEOTROPICAL XENARTHRANS: a data set of occurrence of xenarthran species in the Neotropics

Xenarthrans—anteaters, sloths, and armadillos—have essential functions for ecosystem maintenance, such as insect control and nutrient cycling, playing key roles as ecosystem engineers. Because of habitat loss and fragmentation, hunting pressure, and conflicts with domestic dogs, these species have been threatened locally, regionally, or even across their full distribution ranges. The Neotropics harbor 21 species of armadillos, 10 anteaters, and 6 sloths. Our data set includes the families Chlamyphoridae (13), Dasypodidae (7), Myrmecophagidae (3), Bradypodidae (4), and Megalonychidae (2). We have no occurrence data on Dasypus pilosus (Dasypodidae). Regarding Cyclopedidae, until recently, only one species was recognized, but new genetic studies have revealed that the group is represented by seven species. In this data paper, we compiled a total of 42,528 records of 31 species, represented by occurrence and quantitative data, totaling 24,847 unique georeferenced records. The geographic range is from the southern United States, Mexico, and Caribbean countries at the northern portion of the Neotropics, to the austral distribution in Argentina, Paraguay, Chile, and Uruguay. Regarding anteaters, Myrmecophaga tridactyla has the most records (n = 5,941), and Cyclopes sp. have the fewest (n = 240). The armadillo species with the most data is Dasypus novemcinctus (n = 11,588), and the fewest data are recorded for Calyptophractus retusus (n = 33). With regard to sloth species, Bradypus variegatus has the most records (n = 962), and Bradypus pygmaeus has the fewest (n = 12). Our main objective with Neotropical Xenarthrans is to make occurrence and quantitative data available to facilitate more ecological research, particularly if we integrate the xenarthran data with other data sets of Neotropical Series that will become available very soon (i.e., Neotropical Carnivores, Neotropical Invasive Mammals, and Neotropical Hunters and Dogs). Therefore, studies on trophic cascades, hunting pressure, habitat loss, fragmentation effects, species invasion, and climate change effects will be possible with the Neotropical Xenarthrans data set. Please cite this data paper when using its data in publications. We also request that researchers and teachers inform us of how they are using these data