Temporal Behavior of the Individual Soft Microparticles: Understanding the Detection by Particle Impact Electrochemistry

Emerging progress of the Particle Impact Electrochemistry (PIE) technique has opened a novel field of detection and characterization of many analyte particles. 1 PIE comprises detection of changes in current when collisions of individual micro or nanoparticles are linked with an electrochemical event at the surface of an ultramicroelectrode (UME). 2 Being a rapid, low cost, and analyzing of one analyte at a time, PIE is widely used to characterize the shape, size distribution, and catalytic activity of nanoparticles. 2-5 To explore the scope of PIE for the detection of soft microparticles (absence of crystalline structure), ferrocene (Fc) trapped toluene-in-water emulsion droplets was used as a model with ultramicroelectrode. Droplets were analyzed by tracking the oxidation of Fc inside the droplet in the presence of an ionic liquid acting as emulsifier and conductivity enhancer. The droplet diameter was determined electrochemically using Faraday’s law. PIE was able to characterize the polydisperse size distribution of the droplets successfully. A 3D lattice random walk simulation indicated the stochastic nature of the droplet motion. Unlike nanoparticles, the droplets have slow kinetics and the collision dynamics associated with adsorption on the electrode surface. The adsorbing droplet generated similar spike-like electrical signals in real-time experiments that follow the bulk electrolysis model. These findings will facilitate the characterization of polydisperse microparticles including bacteria, which also adsorb and have similar size and density as the droplets in this work. Finally, because electrolysis time spans from hundreds of milliseconds to a second, single events of such duration are detectable with present-day instrumentation in contrast to non-adsorbing nanoparticles that have nanosecond collisions.https://scholarscompass.vcu.edu/gradposters/1057/thumbnail.jp

Collisions or Adsorption: An Electrochemical Random Walk Decides

Current-time recordings of toluene microdroplets emulsified in water and containing 20 mM Ferrocene (Fc), show multiple electrochemical peaks from oxidation of Fc on disk microelectrodes (5μm-diameter). The average droplet diameter (~0.7 μm) determined from area integration of the peaks was close to Dynamic Light Scattering measurements (~1 μm). Random walk simulations were performed deriving equations to simulate droplet electrolysis using the diffusion and thermal velocity expressions established by Einstein. The simulations show that multiple droplet-electrode collisions, lasting ~0.11 μs each, occur before a droplet wanders away. Updating the Fc-concentration at every collision shows that a droplet only oxidizes ~0.58 % of its content in one collisional journey. In fact, it would take ~5.45 x 106 collisions and ~1.26 h to electrolyze the Fc in one droplet with the collision frequency derived from the thermal velocity (~0.52 cm/s) of a 1μm-droplet. To simulate adsorption, the droplet was immobilized at first contact with the electrode while the electrolysis current continued to be iteratively computed until the end of the simulation. This approach along with modeling of instrumental filtering produced the best match of experimental peaks, which were attributed to electrolysis from single adsorption events instead of elastic collisions. These results point to a heightened sensitivity and speed when relying on adsorption instead of elastic collisions. The electrochemical current for the former is limited by the probability of adsorption per collision, whereas for the latter, the current depends on the collision frequency and the probability of electron transfer per collision.https://scholarscompass.vcu.edu/gradposters/1152/thumbnail.jp

Desempenho estudantil acadêmico na parte inicial da carreira de Doutor em Medicina da Universidade da República

Adriana Fernández-Álvarez: Departamento de Educación Médica, Facultad de Medicina, Universidad de la República. Coordinación del Ciclo Básico Clínico Comunitario, Unidad de Coordinación Curricular, Facultad de Medicina, Universidad de la República, Uruguay.-- Julio C. Siciliano: Departamento de Histología y Embriología, Facultad de Medicina, Universidad de la República, Uruguay. Coordinación del Ciclo Básico Clínico Comunitario, Unidad de Coordinación Curricular, Facultad de Medicina, Universidad de la República, Uruguay.-- Contacto: Adriana Fernández-Álvarez. E-mail: [email protected] este trabajo se presentan los resultados de una indagación de carácter diagnóstico acerca del desempeño académico de los estudiantes de Medicina en los cursos y exámenes correspondientes al ciclo Básico Clínico Comunitario (semestres 2 al 6 de la carrera) en el lapso 2009 a 2016. Los datos correspondientes a inscripciones, aprobaciones y no aprobaciones de cursos y exámenes se obtuvieron y sistematizaron a partir de fuentes secundarias oficiales de origen institucional. Se realizó un análisis cuantitativo ex-post en un estudio de tipo descriptivo que incluyó análisis estadístico inferencial en uno de sus ítems. El análisis evidenció que: I) en la evaluación de los exámenes predomina como resultado la no aprobación sin embargo en la evaluación de cursos predomina la aprobación; II) recursar tras renunciar a cursos aprobados no mejora el desempeño estudiantil en los cursos; III) el desempeño en cursos y exámenes de una cohorte es superior en los estudiantes que aprueban el examen final de BCC1 en el primer o segundo período que en quienes no lo hacen (test χ2; p < 0,001). Además, existió asociación positiva entre aprobar BCC1 en el primer o segundo período y la aprobación de mayor cantidad de cursos (V de Cramer 0,508; p < 0,001) y exámenes (V de Cramer según períodos 0,813 y 0,727; p < 0,001) en el tramo de carrera considerado. Estos datos constituyen un insumo para la evaluación de la implementación del plan de estudios y de la necesidad eventual de realizar ajustes a la normativa vigente.This paper presents the results of aresearch that deals with the academic performance of medical students in the courses and exams corresponding to semesters from 2 to 6 of medical school, which includes basic, clinical and community studies. Data about enrollment, approval and non-approval of courses and exams, between 2009 and 2016, were obtained and systematized from official sec-ondary sources of institutional origin. A quantitative ex-post analysis was performed in a descriptive study that included inferential statistical analysis in one of its items. Results showed:I) non-approval condition predominates in the exams califications, however, approval condition predominates at the courses evaluations; II) recoursing after renouncing to a previously approved course does not improve performance; III)performance in courses and exams of a cohort is better in those students who ap-proved the final exam of BCC1 immediately after course than in those that did not (test χ; p < 0,001). In addition, it was detected a positive association between approving BCC1 immediately after course and the approval of a greater number of courses (Cramer ́s V 0.508, p < 0.001) and exams (Cramer ́s V according to periods 0.813 and 0.727, p < 0.001) in the considered lapse at medical school. These data will be useful for the evaluation of the curriculum structure implementation and for an eventual adjustment of the current regulations.Este artigo apresenta os resultados de um inquérito de diagnóstico sobre o desempenho acadêmico dos estudantes de medicina nos cursos e exames correspondentes ao ciclo clínico comunitário bási-co (semestres 2 a 6 do curso) no período de 2009 a 2016. Os dados para inscrição, aprovação e não aprovação de cursos e exames foram obtidos e sistematizados a partir de fontes secundárias oficiais de origem institucional. Uma análise quantitativa ex-post foi realizada em um estudo descritivo que incluía análise estatística inferencial em um de seus itens. A análise mostrou que: I) na avaliação dos exames, a não aprovação predomina como resultado, no entanto, na avaliação dos cursos, a aprovação predomina; II) voltar a cursar cursos já aprovados não melhora o desempenho dos alunos nos cursos; III) o desempenho em cursos e exames de uma coorte é maior nos alunos que passam o exame BCC1 final no primeiro ou segundo período do que naqueles que não (teste χ2; p <0,001). Além disso, houve associação positiva entre a aprovação de BCC1 no primeiro ou segundo período e a aprovação de mais cursos (Cramer V 0.508; p <0.001) e exames (Cramer V de acordo com os períodos 0.813 e 0.727; p <0.001) no trecho considerado. Esses dados constituem um insumo para a avaliação da implementa-ção do currículo e a eventual necessidade de fazer ajustes aos regulamentos vigentes

Cell mediated immune response elicited in mice after immunization with the P64k meningococcal protein: epitope mapping

The P64k protein of Neisseria meningitidis has been reported as an immunological carrier for weak immunogens. This investigation was aimed at characterizing the T-cell response produced in primed mice and at identifying T helper cell epitopes within this molecule. BALB/c mice subcutaneously immunized with the recombinant antigen provided inguinal lymph node cells (LNC) that proliferated in the presence of P64k in a dose-dependent manner. Proliferating cells secreted IL-4 while the concentration of IL-12 remained unaltered in the culture supernatant. By testing a panel of 59 overlapping synthetic peptides spanning the entire sequence of the antigen a T-cell determinant was localized. Prime-boost and lymphoproliferation experiments, conducted with highly purified synthetic peptides, confirmed that the segment including amino acids 470-485 comprises a T-cell epitope within the P64k molecule

Encuesta seroepidemiológica de pian en la Costa Pacífica colombiana

Yaws has been endemic in the Pacific Coast of Colombia, but the actual prevalence is not known. For this reason we carried out a survey in the communities of this part of the countty where cases had been observed. The active search for cases was based on clinical observations of patients with dermatological disorders, to whom VDRL and FA-ABS tests were administered. The epidemiological survey included 4 intradomiciliary cases for each of the clinical patients detected and also 42 extradomiciliary cases. From a total of 1,830 persons examined, only 6 presented positive results for the VDRL and FTA-ABS tests, which represents a treponema infection prevalence of 0.3%. None of the clinically suspected yaw cases reacted positively to the mentioned tests. These findings permit us to conclude that yaws is not a public health problem in the Pacific Coast of Colombia, and that the sole use of clinical parameters induces to mistaken diagnosis.El pian ha sido endémico en la Costa Pacífica colombiana, pero actualmente su frecuencia real es desconocida, razón por la cual se realizó un estudio en las comunidades de esta zona del país donde se habían conocido casos de pian. Se hizo búsqueda activa de casos clínicos sospechosos a través de examen físico de personas con problemas dermatológicos; a todos ellos se les practicaron exámenes serológicos de VDRL y FTA-ABS. Por cada caso clínico sospechoso de pian, se estudiaron - por clínica y serologia - 4 contactos intradomiciliarios y 42 contactos extradomiciliarios. De las 1.830 personas examinadas, sólo 6 fueron reactivas a las pruebas de VDRL y FTA-ABS, lo cual representa una prevalencia de treponematosis de 0,3%. Ninguna de las pruebas serológicas fue reactiva en los casos clínicos sospechosos de pian. Esto nos lleva a concluir que, en la Costa Pacífica colombiana, el pian no es un problema de salud pública y que se registran como pian otras enfermedades cuando el diagnóstico tiene sólo bases clínicas

First lunar outpost

Design and research efforts at the University of Puerto Rico have focused on the evaluation and refinement of the Habitability Criteria for a prolonged human presence in space during the last four years. Living quarters for a Mars mission and a third generation lunar base concept were proposed. This academic year, 1991-92, work on further refinement of the habitability criteria and design of partial gravity furniture was carried on. During the first semester, design alternatives for furniture necessary in a habitat design optimized for lunar and Martian environments were developed. Designs are based on recent research data from lunar and Mars gravity simulations, and current NASA standards. Artifacts will be submitted to NASA architects to be tested in KC-135 flights. Test findings will be submitted for incorporation in future updates to NASA habitat design standards. Second semester work was aimed at integrating these findings into the First Lunar Outpost (FLO), a mission scenario currently being considered by NASA. The mission consists of a manned return to the moon by crews of four astronauts for periods of 45 days. The major hardware components of the mission are as follows: (1) a Crew Module for the delivery of the crew and their supplies, and (2) the Habitat Module, which will arrive on the Moon unmanned. Our design efforts concentrated on this Habitat Module and on application of habitability criteria. Different geometries for the pressure vessel and their impact on the interior architecture were studied. Upon the selection of a geometry, a more detailed analysis of the interior design was performed, taking into consideration the reduced gravity, and the protection against radiation, micrometeorites, and the extreme temperature variation. A proposal for a FLO was submitted by the students, consisting essentially of a 24-feet (7.3 m.) by 35-feet (10.67 m) high vertical cylinder with work areas, crew quarters, galley, wardroom, leisure facilities, health maintenance, waste management, EVA operations facilities, and safe havens

Diversity of HLA Class I and Class II blocks and conserved extended haplotypes in Lacandon Mayans.

Here we studied HLA blocks and haplotypes in a group of 218 Lacandon Maya Native American using a high-resolution next generation sequencing (NGS) method. We assessed the genetic diversity of HLA class I and class II in this population, and determined the most probable ancestry of Lacandon Maya HLA class I and class II haplotypes. Importantly, this Native American group showed a high degree of both HLA homozygosity and linkage disequilibrium across the HLA region and also lower class II HLA allelic diversity than most previously reported populations (including other Native American groups). Distinctive alleles present in the Lacandon population include HLA-A*24:14 and HLA-B*40:08. Furthermore, in Lacandons we observed a high frequency of haplotypes containing the allele HLA-DRB1*04:11, a relatively frequent allele in comparison with other neighboring indigenous groups. The specific demographic history of the Lacandon population including inbreeding, as well as pathogen selection, may have elevated the frequencies of a small number of HLA class II alleles and DNA blocks. To assess the possible role of different selective pressures in determining Native American HLA diversity, we evaluated the relationship between genetic diversity at HLA-A, HLA-B and HLA-DRB1 and pathogen richness for a global dataset and for Native American populations alone. In keeping with previous studies of such relationships we included distance from Africa as a covariate. After correction for multiple comparisons we did not find any significant relationship between pathogen diversity and HLA genetic diversity (as measured by polymorphism information content) in either our global dataset or the Native American subset of the dataset. We found the expected negative relationship between genetic diversity and distance from Africa in the global dataset, but no relationship between HLA genetic diversity and distance from Africa when Native American populations were considered alone

Extracellular ATP hydrolysis in Caco-2 human intestinal cell line

Extracellular nucleotides and nucleosides activate signaling pathways that play major roles in the physiology and pathophysiology of the gastrointestinal tract. Ectonucleotidases hydrolyze extracellular nucleotides and thus regulate ligand exposure to purinergic receptors. In this study, we investigated the expression, localization and activities of ectonucleotidases using Caco-2 cells, a model of human intestinal epithelial cells. In addition, by studying ATP release and the rates of extracellular ATP (eATP) hydrolysis, we analyzed the contribution of these processes to the regulation of eATP in these cells. Results show that Caco-2 cells regulate the metabolism of eATP and by-products by ecto-nucleoside triphosphate diphosphohydrolase-1 and -2, a neutral ecto-phosphatase and ecto-5′-nucleotidase. All these ectoenzymes were kinetically characterized using intact cells, and their presence confirmed by denatured and native gels, western blot and cytoimmunofluorescence techniques. In addition, regulation of eATP was studied by monitoring the dynamic balance between intracellular ATP release and ectoATPase activity. Following mechanical and hypotonic stimuli, Caco-2 cells triggered a strong but transient release of intracellular ATP, with almost no energy cost, leading to a steep increase of eATP concentration, which was later reduced by ectoATPase activity. A data-driven algorithm allowed quantifying and predicting the rates of ATP release and ATP consumption contributing to the dynamic accumulation of ATP at the cell surface.Fil: Schachter, Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Alvarez, Cora Lilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Bazzi, Zaher. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Faillace, Maria Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Corradi, Gerardo Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Hattab, C.. Universite de Paris. Institut National de la Transfusion Sanguine.; FranciaFil: Rinaldi, Debora Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Gonzalez-Lebrero, Rodolfo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Pucci Molineris, Melisa Eliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Sévigny, J.. Laval University; CanadáFil: Ostuni, M. A.. Universite de Paris; Francia. Universite Paris D. Diderot - Paris 7. French National Institute Of Blood Transfusion.; FranciaFil: Schwarzbaum, Pablo Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; Argentin

Atlantic mammal traits: a dataset of morphological traits of mammals in the atlantic forest of south America

Measures of traits are the basis of functional biological diversity. Numerous works consider mean species-level measures of traits while ignoring individual variance within species. However, there is a large amount of variation within species and it is increasingly apparent that it is important to consider trait variation not only between species, but also within species. Mammals are an interesting group for investigating trait-based approaches because they play diverse and important ecological functions (e.g., pollination, seed dispersal, predation, grazing) that are correlated with functional traits. Here we compile a data set comprising morphological and life history information of 279 mammal species from 39,850 individuals of 388 populations ranging from −5.83 to −29.75 decimal degrees of latitude and −34.82 to −56.73 decimal degrees of longitude in the Atlantic forest of South America. We present trait information from 16,840 individuals of 181 species of non-volant mammals (Rodentia, Didelphimorphia, Carnivora, Primates, Cingulata, Artiodactyla, Pilosa, Lagomorpha, Perissodactyla) and from 23,010 individuals of 98 species of volant mammals (Chiroptera). The traits reported include body mass, age, sex, reproductive stage, as well as the geographic coordinates of sampling for all taxa. Moreover, we gathered information on forearm length for bats and body length and tail length for rodents and marsupials. No copyright restrictions are associated with the use of this data set. Please cite this data paper when the data are used in publications. We also request that researchers and teachers inform us of how they are using the data.Fil: Gonçalves, Fernando. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Bovendorp, Ricardo S.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Beca, Gabrielle. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Bello, Carolina. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Costa Pereira, Raul. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Muylaert, Renata L.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Rodarte, Raisa R.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Villar, Nacho. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Souza, Rafael. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Graipel, Maurício E.. Universidade Federal de Santa Catarina; BrasilFil: Cherem, Jorge J.. Caipora Cooperativa, Florianopolis; BrasilFil: Faria, Deborah. Universidade Estadual de Santa Cruz; BrasilFil: Baumgarten, Julio. Universidade Estadual de Santa Cruz; BrasilFil: Alvarez, Martín R.. Universidade Estadual de Santa Cruz; BrasilFil: Vieira, Emerson M.. Universidade do Brasília; BrasilFil: Cáceres, Nilton. Universidade Federal de Santa María. Santa María; BrasilFil: Pardini, Renata. Universidade de Sao Paulo; BrasilFil: Leite, Yuri L. R.. Universidade Federal do Espírito Santo; BrasilFil: Costa, Leonora Pires. Universidade Federal do Espírito Santo; BrasilFil: Mello, Marco Aurelio Ribeiro. Universidade Federal de Minas Gerais; BrasilFil: Fischer, Erich. Universidade Federal do Mato Grosso do Sul; BrasilFil: Passos, Fernando C.. Universidade Federal do Paraná; BrasilFil: Varzinczak, Luiz H.. Universidade Federal do Paraná; BrasilFil: Prevedello, Jayme A.. Universidade do Estado de Rio do Janeiro; BrasilFil: Cruz-Neto, Ariovaldo P.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Carvalho, Fernando. Universidade do Extremo Sul Catarinense; BrasilFil: Reis Percequillo, Alexandre. Universidade de Sao Paulo; BrasilFil: Paviolo, Agustin Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú; ArgentinaFil: Duarte, José M. B.. Universidade Estadual Paulista Julio de Mesquita Filho; Brasil. Fundación Oswaldo Cruz; BrasilFil: Bernard, Enrico. Universidade Federal de Pernambuco; BrasilFil: Agostini, Ilaria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú; ArgentinaFil: Lamattina, Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; Argentina. Ministerio de Salud de la Nación; ArgentinaFil: Vanderhoeven, Ezequiel Andres. Ministerio de Salud de la Nación; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; Argentin

Design-Based Research in CALL

The purpose of this volume is to expand and refine our understanding of the use of design-based research (DBR) in CALL by contributing to the growing body of literature in this area. We have tried our best to strike a balance between theoretical considerations and concrete examples of DBR. The first section of this volume focuses on theoretical perspectives and ideas that can inform the use of DBR in CALL. The second section contains studies that illustrate DBR through concrete instances of its operationalization. We hope this volume will be a useful source of information and inspiration for those considering to further explore DBR in CALL. For updates on DBR in CALL, please visit the companion site to this volume: https://sites.google.com/site/designbasedresearch/https://lib.dr.iastate.edu/language_books/1006/thumbnail.jp