In this work, the adsorption and orientation on gold nanoparticles (AuNps) of a new family of cruciform systems consisting of thiophene rings and imino groups were studied. The structural ...modification and its influence on the adsorbate‐substrate interaction were evaluated by UV–Vis spectroscopy and Surface Enhanced Raman Spectroscopy (SERS). The absence of SERS spectrum for (N,N′‐bis(4‐(trifluoromethyl)benzylidene)‐2,5‐di (thiophene‐2‐yl)‐1,4‐diaminobenzene) CFF shows that the inclusion of a trifluoromethyl group (‐CF3) on the benzylidene fragment limits the interaction of the CFF system with the gold substrate, in contrast, to that obtained for (N, N′‐dibenzylidene‐2,5‐di (thiophene‐2‐yl) ‐1,4‐diaminobenzene) 2‐CF and (N, N′‐bis (4‐methoxybenzylidene) ‐2,5‐di (thiophene‐2yl) ‐1,4‐diaminobenzene) CMF, where the adsorption took place preferentially through the thiophene rings, resulting in partial quinoidization. On the other hand, the interaction for compound (N, N′‐bis (4‐methylenepyridinyl) ‐2,5‐di (thiophene‐2‐yl) ‐1,4‐diaminobenzene) CPy with the surface was conducted by means of the pyridinic fragments. The systematic modification of the bifunctional cruciform systems, with groups of different nature, makes it possible to rationalize the structural aspects that directly influence the adsorbate‐substrate interaction and molecular orientation on gold substrates. These structural parameters are the basis to the development of stable molecular assemblies, which can act as basic building blocks in the manufacture of molecular switches.
The adsorption and orientation of a new family of cruciform systems were evaluated by Surface Amplified Raman Spectroscopy (SERS). In this sense, the structural modifications allowed modulating the substrate‐adsorbate interaction center, affinity, and preferential orientation of the adsorbates with respect to the gold nanoparticles.
Resumen Este trabajo describe cómo circularon, en el ámbito local y global, algunas hipótesis sobre el cometa Halley de 1910, y cómo estas afectaron en el proceso de legitimación de expertos en ...materia astronómica y en el desarrollado de públicos de la ciencia en Chile. Asimismo, el artículo demuestra que la movilidad de estos conocimientos se produjo a través del despliegue de un mercado editorial dedicado al fenómeno celeste en el periodo. La perspectiva teórica desde la que se aborda esta problemática considera a la historia de la ciencia y se concentra, en la relevancia de las audiencias, por lo que las fuentes de este estudio consisten en dispositivos impresos publicados en Chile durante esos años, sobre todo proyectos periodísticos de amplia cobertura y distribución que, gracias a la modernización de la industria editorial, comenzaron a circular a inicios del siglo XX.
Este trabajo analiza la labor que ejerció el Club de Señoras de Santiago para tejer un puente entre las mujeres de clase alta y la comunidad científica en Chile a principios del siglo xx. El estudio ...utiliza como fuente principal el programa de conferencias científicas desarrollado en las dependencias del Club en sus primeros diez años de funcionamiento, en el que puede observarse el intento por acercar a estas mujeres a los académicos universitarios y autoridades científicas en general. Esto se materializa a través de ciertas estrategias identificadas. Entre ellas, la visibilización de que estas mujeres eran necesarias para la comunidad científica académica, para que esta última pudiera desarrollar teorías y proyectos científicos, sobre todo, en materia de higiene; y por otra, la promoción de un discurso que defendía la compatibilidad de las actividades científicas y académicas con las responsabilidades domésticas atribuidastradicionalmente a las mujeres de esta clase social.
Objective/Context: This paper studies the first Chilean school newspapers led by women and the role of high school students as mediators of scientific knowledge at the end of the 19th century and the ...beginning of the 20th. The analysis is part of the expansion and modernization of the press and publishing industry, as well as the influence of positivism and the educational reforms that were implemented in Chile during that period, a context in which the ruling class considered scientific knowledge, both its development and access to it by the population, as a priority. Methodology: The article is based on the studies of historians of science who have understood audiences as active agents in generating new knowledge, problematizing categories such as expert, amateur and layman, and examining the types of relationships they sustained. This theoretical perspective is applied to analyzing the magazines of four women’s high schools that took advantage of the valid study plans to access the university in the period and is complemented with other sources, such as prospectuses and relevant administrative documents. Originality: The study makes visible the role of women in science and, specifically, Chilean schoolgirls in this context, which have not been studied from the perspective presented here. Conclusions: Despite the lack of attention given to this population group in terms of scientific contribution, it is shown that high school students were active readers, disseminators and producers of knowledge, managing magazines, generating networks and circulating the knowledge beyond the walls of their educational establishments.
Objetivo/Contexto: Este trabalho estuda os primeiros jornais escolares chilenos liderados por mulheres e o papel dos alunos do ensino médio como mediadores do conhecimento científco no final do século XIX e início do século XX. A análise está inserida no contexto da expansão e modernização da imprensa, bem como da influência do positivismo e das reformas educacionais que estavam sendo implementadas no Chile naquele período, um contexto em que a classe dominante considerava o conhecimento científico uma prioridade, tanto a nível de desenvolvimento quanto de acesso da população. Metodologia: O artigo tem como base os estudos de historiadores da ciência que estudaram o público leigo, dentre eles as mulheres, como agentes ativos na circulação e geração de novos conhecimentos. Essa perspectiva teórica é aplicada à análise das publicações de quatro escolas secundárias femininas que seguiam os programas curriculares válidos para o ingresso na universidade no período, e é complementada por outras fontes, como prospectos e documentos administrativos relevantes. Originalidade: O estudo dá visibilidade ao papel das mulheres na disseminação e apropriação do conhecimento científico e, especificamente, das alunas chilenas nesse contexto, que não foram estudadas sob a perspectiva da presente pesquisa. Conclusões: Apesar da falta de atenção dada a esse grupo populacional em termos de contribuição científica, foi demonstrado que as alunas do ensino médio eram leitoras ativas, disseminadoras e produtoras de conhecimento, gerenciando publicações, gerando redes e fazendo o conhecimento circular para além dos muros de suas instituições de ensino.
Objetivo/Contexto: Este trabajo estudia los primeros periódicos escolares chilenos liderados por mujeres, y el papel de las estudiantes de secundaria como mediadoras del saber científico a fines del siglo XIX y principios del XX. El análisis se enmarca en la expansión y modernización de la prensa, así como en la influencia del positivismo y las reformas educativas que se estaban implementando en Chile en ese periodo, contexto en el que la clase dirigente consideró como una prioridad el conocimiento científico, tanto en su desarrollo como en el acceso a este por parte de la población. Metodología: El artículo se basa en los trabajos de historiadores de la ciencia que han estudiado los públicos o audiencias legas, entre ellas, a las mujeres, como agentes activos en la circulación y generación de nuevo conocimiento. Esta perspectiva teórica se aplica al análisis de las revistas de cuatro liceos femeninos que se acogieron a los planes de estudios válidos para acceder a la universidad en el periodo, y se complementa con otras fuentes, tales como prospectos y documentos administrativos relevantes. Originalidad: El estudio visibiliza el papel de las mujeres en la difusión y apropiación del conocimiento científico y, en específico, de las escolares chilenas en ese contexto, quienes no han sido estudiadas desde la perspectiva aquí planteada. Conclusiones: Pese a la falta de atención que se le ha brindado a este grupo de la población en materia de contribución científica, se demuestra que las estudiantes de secundaria fueron activas lectoras, divulgadoras y productoras de saberes, que gestionaron revistas, generaron redes e hicieron circular el conocimiento más allá de los muros de sus establecimientos educativos.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Aquí se presentan los resultados de los análisis de espectroscopía Raman e Infrarroja de pigmentos rojos provenientes de dos contextos fúnebres del cementerio de Topater-1, además de otras dos ...muestras, una del sector San Salvador y otra sin referencia como muestra de control. Todos los pigmentos fueron hallados en el área de Calama, norte de Chile (ca. 500 AC – 100 DC). El cromóforo rojo identificado en todos los casos fue hematita, además de distintos tipos de arcilla y cantidades variables de materia orgánica. Los contenidos de arcillas se relacionan con diversas fuentes de aprovisionamiento, mientras que la presencia de materia orgánica sugiere procesos tecnológicos. Luego, el contraste de estos resultados con la evidencia arqueológica local permite explorar prácticas tecnológicas donde es importante la relación individuo-paisaje o medio ambiente. Esta evidencia es significativa porque confluye con prácticas fúnebres donde se depositan estos pigmentos en valvas de Concholepas concholepas. La realización en la región de estudios de largo alcance bajo esta óptica permitiría: i) dar fundamento estadístico a estas nociones preliminares, ii) proponer acciones analítico-instrumentales posteriores, y iii) inferir sobre el manejo y la circulación local de la hematita y las prácticas asociadas.
Here we present the results of the Raman and Infrared spectroscopy analysis of red pigments from two funeral contexts from the Topater-1 cemetery, in addition to two other samples, one from the San Salvador sector, and another without reference as a control sample. All pigments were found in the Calama area, northern Chile (ca. 500 BC - 100 AD). The red chromophore identified in all cases was hematite, as well as different types of clay and variable amounts of organic matter. The clay contents are related to various sources of supply, while the presence of organic matter suggests technological processes. Then, the contrast of these results with the local archaeological evidence allows us to explore technological practices where the individual-landscape or environment relationship is important. This evidence is significant because they converge with funeral practices where these pigments are deposited in valves of Concholepas concholepas. Carrying out long-range studies in the region from this perspective would allow: i) to give a statistical basis to these preliminary notions, ii) to propose subsequent analytical-instrumental actions, and iii) to infer on the management and local circulation of hematite and the associated practices.
Increased IL-6 production induces, via STAT3 phosphorylation, hepatic transcription of the gene encoding the iron-regulatory hormone, hepcidin, leading to development of anemia of chronic disease ...(ACD). Inhibition of bone morphogenetic protein (BMP) signaling prevents the induction of hepcidin gene expression by IL-6 and ameliorates ACD. Using mice with hepatocyte-specific deficiency of Alk2 or Alk3, we sought to identify the BMP type I receptor that participates in IL-6–mediated induction of hepcidin gene expression. Mice were injected with adenovirus specifying IL-6 (Ad.IL-6) or control adenovirus. Seventy-two hours later, serum iron concentrations and hepatic levels of STAT3 phosphorylation and hepcidin messenger RNA were measured. Additional mice were injected with recombinant murine IL-6 (mIL-6) or vehicle, and hepatic hepcidin gene expression was measured 4 hours later. Deficiency of Alk2 or Alk3 did not alter the ability of Ad.IL-6 injection to induce hepatic STAT3 phosphorylation. Ad.IL-6 increased hepatic hepcidin messenger RNA levels and decreased serum iron concentrations in Alk2- but not Alk3-deficient mice. Similarly, administration of mIL-6 induced hepatic hepcidin gene expression in Alk2- but not Alk3-deficient mice. These results demonstrate that the ability of IL-6 to induce hepatic hepcidin gene expression and reduce serum iron concentrations is dependent on the BMP type I receptor Alk3.
•Presence of the BMP type I receptor Alk3 is required for interleukin-6 to induce hepatic hepcidin gene expression.•Alk3 contributes to the induction of hypoferremia by interleukin-6.
In the present work, the synthesis, electropolymerization and polymer characterization of 2,6-di(4-butylphenyl)-4,8-dithiophenylbenzobisoxazole are reported. The synthesis involves several steps from ...1,4-benzoquinone to form 2,5-diamine-3,6-dibromohydroquinone, which is condensed with 4-butylbenzoyl chloride and later with thiophen-2-ylmagnesium bromide through Kumada coupling reactions. This monomer is polymerized by potentiodynamic cyclic voltammetry. The voltammograms show a dependency on the range of applied potential, and three different processes of thermodynamically reversible oxidation and reduction occur on a platinum surface. Theoretical calculations are used to characterize these redox processes. The distribution of the frontier orbital density for the monomer and trimer forms show the participation of the thiophene ring in the polymerization processes and partial oxidation of the benzoxazole fragment. The characterization of the polymeric deposit was carried out by scanning electron microscopy and Raman spectroscopy. A dependence of both the morphology and vibrational state of the polymer on the potential range applied exists. This is attributed to the different conformations and dihedral angles of the macromolecule. Finally, the optical properties of the material indicate the existence of intramolecular charge transfer through the system’s thiophene and benzobisoxazole (donor and acceptor).
PDF
