Strain engineering in alloy nanoparticles

The deformation of interatomic distances with respect to those of the perfect crystal generates atomic-level strain. In nanoalloys, strain can arise because of finite size, morphology, domain structure and lattice mismatch between their atomic compounds. Strain can strongly affect the functional properties of nanoalloys, as it alters their electronic energy levels. Moreover, atomic-level strain generates atomic-level stress, which in turn results in distortions induced by strain. When the stress accumulated in a nanoalloy exceeds a certain level, the particle can relax that stress by undergoing structural transitions such as shape and/or chemical ordering transitions. Atomic-level strain is then a powerful tool to control and manipulate the structural and functional properties of nanoalloys. This requires a combined theoretical and experimental approach both to deeply understand the physical origin of strain, and to characterize it with a sub-angstrom resolution. Here, we present a theoretical analysis of the main sources of strain in nanoalloys, we analyse how atomic-level strain can be experimentally measured with transmission electron microscopy, we discuss its effect on the functional properties of nanoalloys, finally we describe how atomic-level stress arises from atomic-level strain, and how stress can induce structural transformations at the nanoscale

Concepções sobre a tecnologia de novos estudantes de carreiras científico-tecnológicas na Argentina

This research paper presents an analysis of the opinion of new students of the undergraduate programs in Biotechnology and Food Engineering of the National University of Quilmes (Argentina) —UNQ—, about various aspects of Technology (T). The COCTS test (Vázquez et al., 2006) was used as an instrument and analyzing the answers were analyzed with statistical and non-statistical methods. This methodology presents variations with respect to those normally used when applying said test. The study showed that students have visions about T that are far from those held by specialists. Even inconsistencies were detected within the same opinions, which could indicate the lack of a coherent mental model about the phenomenon. As for the methodological proposals, they were useful to show behaviors that the previous methods did not show. A lack of the essential components of scientific literacy was observed in students who have chosen a technological scientific career (Biotechnology, Food Engineering).Este trabajo presenta el análisis de la opinión de alumnos nóveles de las carreras de licenciatura en Biotecnología e Ingeniería en Alimentos de la Universidad Nacional de Quilmes (Argentina) UNQ, acerca de diversos aspectos de la Tecnología (T). Se utilizó como instrumento el Cuestionario de Opiniones sobre Ciencia, Tecnología y Sociedad cocts (Vázquez et al., 2006) y se analizaron las respuestas con métodos estadísticos y no estadísticos. Esta metodología presenta variaciones respecto a las que habitualmente se utilizan al aplicar dicho cuestionario. El estudio mostró que los estudiantes poseen visiones sobre la T, que están alejadas de las sostenidas por los especialistas. Incluso, se detectaron incoherencias dentro de las mismas opiniones, lo que podría indicar la falta de un modelo mental coherente acerca del fenómeno. En cuanto a las propuestas metodológicas, resultaron útiles para mostrar comportamientos que los métodos anteriores no evidenciaban. Se observó una carencia de los componentes esenciales de la alfabetización científica en alumnos que han elegido una carrera científico tecnológica (Biotecnología, Ingeniería en Alimentos).Este artigo de pesquisa apresenta a análise da opinião de novos alunos dos programas de graduação em Biotecnologia e Engenharia de Alimentos da Universidade Nacional de Quilmes (Argentina) sobre Tecnologia (T). O questionário cocts (Vázquez et al., 2006) foi utilizado como instrumento e as respostas foram analisadas com métodos estatísticos e não estatísticos. Essa metodologia apresenta variações em relação àquelas normalmente utilizadas na aplicação do referido questionário. O estudo mostrou que os alunos têm visões sobre a T que estão longe das realizadas por especialistas. Até inconsistências foram detectadas nas mesmas opiniões, o que poderia indicar a falta de um modelo mental coerente sobre o fenômeno. Quanto às propostas metodológicas, elas foram úteis para mostrar comportamentos que os métodos anteriores não mostraram. A carência dos componentes essenciais da literacia científica foi observada nos alunos que optaram pela carreira científica tecnológica (Biotecnologia, Engenharia de Alimentos)

Conservation Medicine: a STS approach to environmental, food and health education

En la actualidad, han surgido numerosos campos del conocimiento relacionados a la problemática ambiental, alimentaria y de salud, producto de la interacción humana con el ambiente. A través del conocimiento de estas áreas, pueden abordarse temáticas que permiten una comprensión de aspectos de la Ciencia, la Tecnología y la Sociedad. En este trabajo, se presenta una aplicación educativa denominada “Medicina de la Conservación” (MdlC), una disciplina que engloba, bajo una única salud, a la salud animal, humana y del ambiente. En el presente artículo se emplea la MdlC como herramienta educativa para incorporar contenidos CTS dentro del área de las ciencias naturales y, además, fomentar el Pensamiento Crítico. Se desarrolla una Unidad Didáctica, UD aplicada a tres grupos: uno de nivel medio de una escuela agropecuaria, otro de formación del profesorado y por último, un grupo de estudiantes de ingeniería en alimentos. La UD incluyó el abordaje de las Enfermedades Transmitidas por Alimentos (ETA) y las zoonosis en diferentes espacios como la granja de la escuela, los zoológicos, los bioparques y los parques nacionales. Para la evaluación de la UD, se utilizó un cuestionario y el formato de entrevista del proyecto: Educación de las competencias científica, tecnológica y pensamiento crítico mediante la enseñanza de temas de naturaleza de ciencia y tecnología (CYTPENCRI). De los resultados se destacan el interés, la motivación y el desarrollo de toma de decisiones por parte del estudiantado frente a las zoonosis y ETA a partir del abordaje desde la MdlC.Currently, numerous fields of knowledge have emerged related to environmental, food and health problems, as a result of human interaction with the environment. Through knowledge of these areas, topics that allow an understanding of aspects of Science, Technology and Society can be addressed. In this work, an educational application called “Conservation Medicine” (CM) is presented, a discipline that encompasses, under a single health, animal, human and environmental health. In this article, the CM is used as an educational tool to incorporate CTS content within the natural sciences area and, in addition, to promote Critical Thinking. A Didactic Unit is developed, DU applied to three groups: one of medium level of an agricultural school, another of teacher training and finally, a group of students of food engineering. The DU included the approach of Foodborne Diseases (FD) and zoonoses in different spaces such as the school farm, zoos, bioparks and national parks. For the evaluation of the DU, a questionnaire and the interview format of the project were used: Education of scientific, technological and critical thinking skills through the teaching of subjects of a science and technology nature (CYTPENCRI). The results highlight the interest, motivation and the development of decision-making by the students against zoonoses and FD from the approach from the CM.Atualmente, surgiram inúmeras áreas do conhecimento relacionadas a problemas ambientais, alimentares e de saúde, como resultado da interação humana com o meio ambiente. Através do conhecimento dessas áreas, podem ser abordados tópicos que permitem o entendimento entre os aspectos da Ciência, Tecnologia e Sociedade. Neste trabalho, é apresentada uma aplicação educacional denominada “Medicina de Conservação” (MdC), disciplina que engloba, sob uma única saúde, saúde animal, humana e ambiental. Neste artigo, o MdC é usado como uma ferramenta educacional para incorporar o conteúdo da CTS na área de ciências naturais e, além disso, para promover o Pensamento Crítico. É desenvolvida uma Unidade Didática (UD), aplicada a três grupos: um de nível médio de uma escola agrícola, outro de formação de professores e, finalmente, um grupo de estudantes de engenharia de alimentos. A UD incluiu a abordagem de Doenças Transmitidas por Alimentos (DTA) e zoonoses em diferentes espaços, como a fazenda da escola, zoológicos, bioparques e parques nacionais. Para a avaliação da UD, utilizou-se um questionário e o formato de entrevista do projeto: Educação de habilidades de pensamento científico, tecnológico e crítico por meio do ensino de disciplinas de natureza científica e tecnológica (CYTPENCRI). Os resultados destacam o interesse, a motivação e o desenvolvimento da tomada de decisões dos estudantes contra zoonoses e DTA a partir da abordagem do MdC.Fil: Lampert, Damian Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; ArgentinaFil: Russo, Matias. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias; Argentina. Universidad Nacional de Quilmes; ArgentinaFil: Scandroglio, Natalia. No especifíca;Fil: Roncaglia, Diana Inés. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentin

Ultradeformable archaeosomes as new topical adjuvants

Ultradeformable archaeosomes (UDA) are vesicles made of soybean phosphatidylcholine (SPC), sodium cholate (NaChol) and polar lipids from Halorubrum tebenquichense (3:1:3 wt/wt). Although ultradeformable liposomes (UDL, made of SPC and NaChol at 6:1 wt/wt) and UDA were neither captured nor caused cytotoxicity on keratinocytes, UDA was avidly captured by macrophages, their viability being reduced by 0.4-1.6 mg/mL phospholipids by 25 to 60%. Instead, UDL were poorly captured and caused no toxicity. Balb/C mice immunized by the topical route with four doses of ovalbumin (OVA)-loaded UDA, at 75 μg OVA/600 μg phospholipids (125 nm mean size and -42 mV zeta potential), induced IgG titers tenfold to 100-fold higher than those immunized with OVA-loaded UDL at the same dosage. Both matrices penetrate to the same skin depth (nearly 10 μm after 1 hour on excised human skin), being the higher topical adjuvancy and higher phagocytic uptake of UDA related to its glycolipid content.Fil: Higa, Leticia Herminia. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Schilrreff, Priscila. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; ArgentinaFil: Perez, Ana Paula. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; ArgentinaFil: Iriarte, Maiara A.. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; ArgentinaFil: Roncaglia, Diana Inés. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Morilla, María José. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; ArgentinaFil: Romero, Eder Lilia. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Archaeosomes made of Halorubrum tebenquichense total polar lipids: A new source of adjuvancy

Background: Archaeosomes (ARC), vesicles prepared from total polar lipids (TPL) extracted from selected genera and species from the Archaea domain, elicit both antibody and cell-mediated immunity to the entrapped antigen, as well as efficient cross priming of exogenous antigens, evoking a profound memory response. Screening for unexplored Archaea genus as new sources of adjuvancy, here we report the presence of two new Halorubrum tebenquichense strains isolated from grey crystals (GC) and black mood (BM) strata from a littoral Argentinean Patagonia salt flat. Cytotoxicity, intracellular transit and immune response induced by two subcutaneous (sc) administrations (days 0 and 21) with BSA entrapped in ARC made of TPL either form BM (ARC-BM) and from GC (ARC-GC) at 2% w/w (BSA/lipids), to C3H/HeN mice (25 μg BSA, 1.3 mg of archaeal lipids per mouse) and boosted on day 180 with 25 μg of bare BSA, were determined. Results: DNA G+C content (59.5 and 61.7% mol BM and GC, respectively), 16S rDNA sequentiation, DNA-DNA hybridization, arbitrarily primed fingerprint assay and biochemical data confirmed that BM and GC isolates were two non-previously described strains of H. tebenquichense. Both multilamellar ARC mean size were 564 ± 22 nm, with -50 mV zeta-potential, and were not cytotoxic on Vero cells up to 1 mg/ml and up to 0.1 mg/ml of lipids on J-774 macrophages (XTT method). ARC inner aqueous content remained inside the phago-lysosomal system of J-774 cells beyond the first incubation hour at 37°C, as revealed by pyranine loaded in ARC. Upon subcutaneous immunization of C3H/HeN mice, BSA entrapped in ARC-BM or ARC-GC elicited a strong and sustained primary antibody response, as well as improved specific humoral immunity after boosting with the bare antigen. Both IgG1 and IgG2a enhanced antibody titers could be demonstrated in long-term (200 days) recall suggesting induction of a mixed Th1/Th2 response. Conclusion: We herein report the finding of new H. tebenquichense non alkaliphilic strains in Argentinean Patagonia together with the adjuvant properties of ARC after sc administration in mice. Our results indicate that archaeosomes prepared with TPL from these two strains could be successfully used as vaccine delivery vehicles

Percolation thresholds in chemical disordered excitable media

The behavior of chemical waves advancing through a disordered excitable medium is investigated in terms of percolation theory and autowave properties in the framework of the light-sensitive Belousov-Zhabotinsky reaction. By controlling the number of sites with a given illumination, different percolation thresholds for propagation are observed, which depend on the relative wave transmittances of the two-state medium considered

Archaeosomes made of Halorubrum tebenquichense total polar lipids: a new source of adjuvancy

<p>Abstract</p> <p>Background</p> <p>Archaeosomes (ARC), vesicles prepared from total polar lipids (TPL) extracted from selected genera and species from the Archaea domain, elicit both antibody and cell-mediated immunity to the entrapped antigen, as well as efficient cross priming of exogenous antigens, evoking a profound memory response. Screening for unexplored Archaea genus as new sources of adjuvancy, here we report the presence of two new <it>Halorubrum tebenquichense </it>strains isolated from grey crystals (<it>GC</it>) and black mood (<it>BM</it>) strata from a littoral Argentinean Patagonia salt flat. Cytotoxicity, intracellular transit and immune response induced by two subcutaneous (sc) administrations (days 0 and 21) with BSA entrapped in ARC made of TPL either form <it>BM </it>(ARC-BM) and from <it>GC </it>(ARC-GC) at 2% w/w (BSA/lipids), to C3H/HeN mice (25 μg BSA, 1.3 mg of archaeal lipids per mouse) and boosted on day 180 with 25 μg of bare BSA, were determined.</p> <p>Results</p> <p>DNA G+C content (59.5 and 61.7% mol <it>BM </it>and <it>GC</it>, respectively), 16S rDNA sequentiation, DNA-DNA hybridization, arbitrarily primed fingerprint assay and biochemical data confirmed that <it>BM </it>and <it>GC </it>isolates were two non-previously described strains of <it>H. tebenquichense</it>. Both multilamellar ARC mean size were 564 ± 22 nm, with -50 mV zeta-potential, and were not cytotoxic on Vero cells up to 1 mg/ml and up to 0.1 mg/ml of lipids on J-774 macrophages (XTT method). ARC inner aqueous content remained inside the phago-lysosomal system of J-774 cells beyond the first incubation hour at 37°C, as revealed by pyranine loaded in ARC. Upon subcutaneous immunization of C3H/HeN mice, BSA entrapped in ARC-BM or ARC-GC elicited a strong and sustained primary antibody response, as well as improved specific humoral immunity after boosting with the bare antigen. Both IgG1 and IgG2a enhanced antibody titers could be demonstrated in long-term (200 days) recall suggesting induction of a mixed Th1/Th2 response.</p> <p>Conclusion</p> <p>We herein report the finding of new <it>H. tebenquichense </it>non alkaliphilic strains in Argentinean Patagonia together with the adjuvant properties of ARC after sc administration in mice. Our results indicate that archaeosomes prepared with TPL from these two strains could be successfully used as vaccine delivery vehicles.</p

Frame-by-frame observations of structure fluctuations in single mass-selected Au clusters using aberration-corrected electron microscopy

The multi-dimensional potential energy surface (PES) of a nanoparticle, such as a bare cluster of metal atoms, controls both the structure and dynamic behaviour of the particle. These properties are the subject of numerous theoretical simulations. However, quantitative experimental measurements of critical PES parameters are needed to regulate the models employed in the theoretical work. Experimental measurements of parameters are currently few in number, while model parameters taken from bulk systems may not be suitable for nanosystems. Here we describe a new measurement methodology, in which the isomer structures of a single deposited nanocluster are obtained frame-by-frame in an aberration-corrected scanning transmission electron microscope (ac-STEM) in high angle annular dark field (HAADF) mode. Several gold clusters containing 309 ± 15 atoms were analysed individually after deposition from a mass-selected cluster source onto an amorphous carbon film. The main isomers identified are icosahedral (Ih), decahedral (Dh) and face-centred-cubic (fcc) (the bulk structure), alongside many amorphous (glassy) structures. The results, which are broadly consistent with static ac-STEM measurements of an ensemble of such clusters, open the way to dynamic measurements of many different nanoparticles of diverse sizes, shapes and compositions

Archaeosomes made of Halorubrum tebenquichense total polar lipids: A new source of adjuvancy

Background: Archaeosomes (ARC), vesicles prepared from total polar lipids (TPL) extracted from selected genera and species from the Archaea domain, elicit both antibody and cell-mediated immunity to the entrapped antigen, as well as efficient cross priming of exogenous antigens, evoking a profound memory response. Screening for unexplored Archaea genus as new sources of adjuvancy, here we report the presence of two new Halorubrum tebenquichense strains isolated from grey crystals (GC) and black mood (BM) strata from a littoral Argentinean Patagonia salt flat. Cytotoxicity, intracellular transit and immune response induced by two subcutaneous (sc) administrations (days 0 and 21) with BSA entrapped in ARC made of TPL either form BM (ARC-BM) and from GC (ARC-GC) at 2% w/w (BSA/lipids), to C3H/HeN mice (25 μg BSA, 1.3 mg of archaeal lipids per mouse) and boosted on day 180 with 25 μg of bare BSA, were determined. Results: DNA G+C content (59.5 and 61.7% mol BM and GC, respectively), 16S rDNA sequentiation, DNA-DNA hybridization, arbitrarily primed fingerprint assay and biochemical data confirmed that BM and GC isolates were two non-previously described strains of H. tebenquichense. Both multilamellar ARC mean size were 564 ± 22 nm, with -50 mV zeta-potential, and were not cytotoxic on Vero cells up to 1 mg/ml and up to 0.1 mg/ml of lipids on J-774 macrophages (XTT method). ARC inner aqueous content remained inside the phago-lysosomal system of J-774 cells beyond the first incubation hour at 37°C, as revealed by pyranine loaded in ARC. Upon subcutaneous immunization of C3H/HeN mice, BSA entrapped in ARC-BM or ARC-GC elicited a strong and sustained primary antibody response, as well as improved specific humoral immunity after boosting with the bare antigen. Both IgG1 and IgG2a enhanced antibody titers could be demonstrated in long-term (200 days) recall suggesting induction of a mixed Th1/Th2 response. Conclusion: We herein report the finding of new H. tebenquichense non alkaliphilic strains in Argentinean Patagonia together with the adjuvant properties of ARC after sc administration in mice. Our results indicate that archaeosomes prepared with TPL from these two strains could be successfully used as vaccine delivery vehicles.Facultad de Ciencias Exacta