One pot solvothermal synthesis of organic acid coated magnetic iron oxide nanoparticles

Indexación: ScieloABSTRACT In this work we present the synthesis and characterization of iron oxide nanoparticles (IONPs), which were structurally and magnetically characterized. The use of iron salts and an organic acid (l-serine or ascorbic acid) as precursors under solvothermal conditions yielded these coated IONPs. The powder X-ray diffraction pattern of FeO-1 and FeO-2 is consistent with hematite (α-Fe2O3) and hematite-maghemite ((α-Fe2O3/γ-Fe2O3) respectively. The TEM analysis permits to estimate an average size of 10 nm for the FeO-1 sample. The magnetic characterization of the samples through the M(H) plots showed a very low coercivity value for both samples, being 53 Oe for FeO-1 and 10 Oe for FeO-2, indicating the very weak ferromagnetic character of the synthesized iron oxide species. Even though both organic acids under solvothermal conditions permit to obtain coated IONPs in one pot reaction, l-serine produces a more narrow-size distribution

Phylogenetic relationships and larval morphology of the recently described diving beetle genus Laccomimus (Coleoptera: Dytiscidae: Laccophilinae)

The larvae of the diving beetle genus Laccomimus Toledo & Michat, 2015 (Laccophilinae) are studied for the first time, based on detailed descriptions and illustrations of all instars of L. distinctus Toledo & Michat, 2015, with particular emphasis on morphometry and chaetotaxy. The phylogenetic relationships of this genus within the tribe Laccophilini are analyzed cladistically. Laccomimus is recovered as part of a clade that includes the genera Australphilus Watts, 1978, Neptosternus Sharp, 1882 and Laccophilus Leach, 1815 and is characterized by the presence of natatory setae on the tibia and tarsus, and within this clade it is a sister to the other genera. Third-instar larvae of Laccomimus and Africophilus Guignot, 1948 share the mediodistal insertion of the seta CO7 on the meso- and metacoxa, a short and spine-like seta TI6 on the metatibia, a ventrally sclerotized abdominal segment V and a short urogomphus. These characters are considered plesiomorphic and indicate a basal position of both genera within the Laccophilini. All instars of Laccomimus are characterized by the anterolateral lobes of the frontoclypeus clearly projecting beyond the anterior margin and the last abdominal segment strongly elongated. Diagnostic features of the first instar are: frontoclypeus unmodified posteriorly, lamellae clypeales thin and hair-like, pores ANe, MXb–d–f–i, LAb–c and seta TR3 absent, seta LA3 and an additional dorsal pore present on the prementum, abdominal tergites I–VII with anterior transverse carina, and ventral surface of the abdominal segment VI sclerotized.Fil: Michat, Mariano Cruz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Toledo, Mario. Università di Parma; Itali

Stern-Gerlach Entanglement in Spinor Bose-Einstein Condensates

Entanglement of spin and position variables produced by spatially inhomogeneous magnetic fields of Stern-Gerlach type acting on spinor Bose-Einstein condensates may lead to interference effects at the level of one-boson densities. A model is worked out for these effects which is amenable to analytical calculation for gaussian shaped condensates. The resulting interference effects are sensitive to the spin polarization properties of the condensate.Comment: 9 pages, 2 figure

Map Matching for the public transport network in Xalapa City / Map Matching para a rede de transportes públicos na Cidade de Xalapa

In Xalapa, Veracruz, Mexico, there was not a correct description of the more than 100 public transport bus routes that existed, for which a collective event was held to collect Global Positioning System locations. The trajectories obtained were not adjusted to the layout of the city's public road network, due to measurement errors caused by the variety of devices used for tracking. To recover the correct trajectories, a Map Matching algorithm was used based on the optimization of paths in graphs whose nodes belong to the public roads of the city. This work presents the description of the data collection methodology and the construction of the graphs for the implementation of the algorithm that finally recovered the real routes

RKB: a Semantic Web knowledge base for RNA

Increasingly sophisticated knowledge about RNA structure and function requires an inclusive knowledge representation that facilitates the integration of independently –generated information arising from such efforts as genome sequencing projects, microarray analyses, structure determination and RNA SELEX experiments. While RNAML, an XML-based representation, has been proposed as an exchange format for a select subset of information, it lacks domain-specific semantics that are essential for answering questions that require expert knowledge. Here, we describe an RNA knowledge base (RKB) for structure-based knowledge using RDF/OWL Semantic Web technologies. RKB extends a number of ontologies and contains basic terminology for nucleic acid composition along with context/model-specific structural features such as sugar conformations, base pairings and base stackings. RKB (available at http://semanticscience.org/projects/rkb) is populated with PDB entries and MC-Annotate structural annotation. We show queries to the RKB using description logic reasoning, thus opening the door to question answering over independently-published RNA knowledge using Semantic Web technologies

A reassessment of the taxonomic status of Paraglyptodon Castellanos, 1932 (Mammalia, Cingulata, Glyptodontia)

Castellanos described and published about new genera of glyptodonts, according to a phylogenetic scheme mainly based on the evolution of the external surface of the dorsal carapace. Among these new genera, Castellanos proposed Paraglyptodon as the predecessor of Glyptodon, and included within Paraglyptodon all known species of Glyptodontinae recovered from “horizontes pre-Ensenadenses”, and within Glyptodon all known species from “Horizontes pampeanos”, restricting the latter to the Quaternary. All the species that belong to Paraglyptodon, that is Paraglyptodon chapalmalensis, Paraglyptodon uquiensis, Paraglyptodon dubius, and Paraglyptodon paranensis were established based on one, two or few osteoderms, mostly from the dorsal carapace. Regarding P. paranensis and P. dubius, Oliva and collaborators consider the first as a nomen vanum, representing an indeterminate Glyptodontinae, and the second as a synonym of P. chapalmalensis. Upon re-examination of the holotypes of P. chapalmalensis and P. uquiensis together with their comparison with other well-known specimens of glyptodonts, mainly with Glyptodon (of both juvenile and adult stages), we found the same ornamentation in different sections of the dorsal carapaces, particularly in P. chapalmalensis and in juvenile stages of Glyptodon spp.We could not identify features that would allow us to make a distinction between the holotype of P. uquiensis and Glyptodon spp. Therefore, we consider that a new taxon guide for naming the Upper Chapadmalalan biozone is necessary. The biostratigraphic range of Glyptodon could possibly be extended to the late Pliocene. However, new records and studies are needed to verify the existence of this taxon in the Chapadmalalan Stage/Age in its type locality.Facultad de Ciencias Naturales y Muse

Una propuesta para la enseñanza de los números decimales en un contexto agrícola

La propuesta se configuró a partir de un estudio de caso, en el que se hizo un diseño de tareas integrando TIC, siguiendo los seis principios de la Educación Matemática Realista que proyectan la matematización progresiva, en donde, los estudiantes construyen modelos matemáticos, partiendo de la exploración de situaciones cercanas a su contexto. En particular, se retomó las prácticas de siembra de hortalizas, basados en datos técnicos necesarios en los que se potencia la notación decimal. Se determinó que las aproximaciones a la construcción de los racionales parten del contexto de medida, desarrollando las matemáticas de forma intuitiva, a través de estrategias empíricas y de niveles preformales. Esta experiencia reconoce que los números racionales en su representación decimal periódica finita generan en los estudiantes un nivel de complejidad mayor en la comprensión, puesto que no se trata únicamente de leer y operar con estas representaciones numéricas; sino que, a partir de ellas, los estudiantes pueden trabajar las equivalencias entre fracciones decimales, relaciones porcentuales y de manera progresiva abstraer propiedades de los números decimales diferentes a las de los números naturales