869 research outputs found

    Autonomous propulsion of carbon nanotubes powered by a multienzyme ensemble

    Get PDF
    Covalent attachment of the enzymes glucose oxidase and catalase to carbon nanotubes enables the tandem catalytic conversion of glucose and H2O2 formed to power autonomous movement of the nanotubes.

    Vox absentiae: tracce di un archivio conventuale disperso e distrutto. Santa Maria delle Grazie di Bergamo (OFM Obs.)

    Get PDF
    ITALIANO: L’archivio antico del convento di Santa Maria delle Grazie di Bergamo, dell’ordine dei frati Minori dell’Osservanza, risulta oggi disperso. Il contributo presenta l’atto di fondazione del convento, risalente al 1422, ma sopravvissuto solo nella trascrizione moderna di una copia autentica della fine del secolo XV o degli inizi del secolo XVI. I personaggi nominati nell’atto sono rintracciati nei documenti, in particolare il notaio rogatario e il notaio della copia autenticata. Infine, viene illustrato un testamento del 1474 di un giovane bergamasco in procinto di entrare nell’ordine, proprio nel convento delle Grazie. / ENGLISH: The ancient archive of the convent of Santa Maria delle Grazie in Bergamo, of the Order of Friars Minor of the Observance, is now lost. The contribution presents the founding act of the convent, dating back to 1422, but survived only in the modern transcription of an authentic copy of the end of the XVth Century or the beginning of the XVIth Century. The persons named are traced in the documents, in particular the notary of the original act and the notary of the certified copy. Finally, a testament of 1474 by a young Bergamasco about to enter the order, right in the convent ‘delle Grazie’, is illustrated

    Lewis : um software educacional baseado na filatelia

    Get PDF
    Trabalho de Conclusão de Curso (graduação)—Universidade de Brasília, Instituto de Ciências Exatas, Departamento de Ciência da Computação, 2018.A filatelia, definida como o ato de estudar e colecionar selos postais, apresenta uma riqueza cultural significativa pouco explorada pelo ensino básico tradicional. Assim, buscando enriquecer o processo de aprendizagem das escolas, bem como difundir esse hobby para vários alunos, conquistando com isso até mesmo o surgimento de possíveis novos filatelistas, nunca foi tão necessário, como agora, o desenvolvimento de ideias e soluções criativas que estimulassem ambos os seguimentos, o da filatelia e o do ensino. Diante desse desafio, o presente trabalho propõe a integração da filatelia ao ensino, a partir de tecnologias da informação e da gamificação. Desenvolvido para crianças entre 8 e 10 anos de idade, o projeto incentiva um aprendizado recreativo e lúdico, explorando de forma pedagógica o rico conteúdo da filatelia. A partir de uma abordagem interdisciplinar e de motivações extrínsecas, o protótipo desenvolvido passou por duas avaliações, sendo uma realizada por especialistas e a outra pelo framework de gamificação Octalysis. Ambas as avaliações apresentaram resultados positivos, considerando o protótipo adequado para a realização de seu objetivo.Philately, defined as the act of studying and collecting postage stamps, presents a significant cultural richness that is little explored by traditional basic education. Thus, seeking to enrich the learning process of schools, as well as spreading this hobby to several students, conquering with it even the emergence of possible new philatelists, was never as necessary, as now, the development of ideas and creative solutions that stimulate both foldings, philately and teaching. Given this challenge, the present work proposes the integration of philately to teaching, by the use of information technologies and gamification. Designed for children between 8 and 10 years of age, the project encourages recreational and playful learning, exploring the rich content of philately in a pedagogical way. Based on an interdisciplinary approach and extrinsic motivations, the prototype developed has undergone two assessments, one carried out by specialists and the other by the gamification framework Octalysis. Both assessments presented positive results, considering the appropriate prototype for achieving its objective

    La scrittura delle carte bresciane del secolo XII

    Get PDF
    Generally considered as the period in which a lot of factors (both within and outside the notarial practice) made the gap between books and documents handwriting become narrower, and the influence of the former increased on the latter, 12th century was characterized also in Brescia by a shared adaptation of notaries' script to the ancient and prestigious model of littera antiqua. The new 'diplomatic minuscule', documented since the very first years of the century by excellent (though isolated) cases (like the graphic experiences of iudex Ebezo and Rodulfus), became a widespread legacy among Brescia notaries in the mid-1150's. The papers aims at analyzing these graphical processes till to the resumption of a more cursive writing and the introduction of 'secondary' ligatures, that frankly foreshadow the most typical 13th century documentary script

    Nano-yarn carbon nanotube fiber based enzymatic glucose biosensor

    Get PDF
    This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2010 IOP Publishing Ltd.A novel brush-like electrode based on carbon nanotube (CNT) nano-yarn fiber has been designed for electrochemical biosensor applications and its efficacy as an enzymatic glucose biosensor demonstrated. The CNT nano-yarn fiber was spun directly from a chemical-vapor-deposition (CVD) gas flow reaction using a mixture of ethanol and acetone as the carbon source and an iron nano-catalyst. The fiber, 28 µm in diameter, was made of bundles of double walled CNTs (DWNTs) concentrically compacted into multiple layers forming a nano-porous network structure. Cyclic voltammetry study revealed a superior electrocatalytic activity for CNT fiber compared to the traditional Pt–Ir coil electrode. The electrode end tip of the CNT fiber was freeze-fractured to obtain a unique brush-like nano-structure resembling a scale-down electrical 'flex', where glucose oxidase (GOx) enzyme was immobilized using glutaraldehyde crosslinking in the presence of bovine serum albumin (BSA). An outer epoxy-polyurethane (EPU) layer was used as semi-permeable membrane. The sensor function was tested against a standard reference electrode. The sensitivities, linear detection range and linearity for detecting glucose for the miniature CNT fiber electrode were better than that reported for a Pt–Ir coil electrode. Thermal annealing of the CNT fiber at 250 °C for 30 min prior to fabrication of the sensor resulted in a 7.5 fold increase in glucose sensitivity. The as-spun CNT fiber based glucose biosensor was shown to be stable for up to 70 days. In addition, gold coating of the electrode connecting end of the CNT fiber resulted in extending the glucose detection limit to 25 µM. To conclude, superior efficiency of CNT fiber for glucose biosensing was demonstrated compared to a traditional Pt–Ir sensor.Brunel University, the Royal Society and the National Institute of Health

    El proceso de internacionalización de las principales aerolíneas españolas desde la perspectiva de velocidad y distancia

    Get PDF
    Las aerolíneas españolas han vivido procesos de internacionalización que se han visto afectados por la realidad económica de las décadas de 1990, 2000 y 2010. Los acontecimientos económicos que han tenido lugar en estas décadas, junto con las decisiones tomadas por estas empresas en relación a los factores velocidad y distancia en la internacionalización, han condicionado la evolución de estos procesos, en algunos aspectos alejándolos y, en otros, acercándolos a los planteamientos de los principales modelos teóricos. En el presente texto se comentan algunos de esos aspectos y se plantean nuevos elementos a tomar en consideración dentro del marco de las teorías de internacionalización de empresas y del sector aéreo.Universidad de Sevilla. Grado en Turism

    Uptake and release of double-walled carbon nanotubes by mammalian cells

    Get PDF
    Efforts to develop carbon nanotubes (CNTs) as nano-vehicles for precise and controlled drug and gene delivery, as well as markers for in vivo biomedical imaging, are currently hampered by uncertainties with regard to their cellular uptake, their fate in the body, and their safety. All of these processes are likely to be affected by the purity of CNT preparation, as well as the size and concentration of CNTs used, parameters that are often poorly controlled in biological experiments. It is demonstrated herein that under the experimental conditions of standard transfection methods, DWNTs are taken up by cultured cells but are then released after 24 h with no discernable stress response. The results support the potential therapeutic use of CNTs in many biomedical settings, such as cancer therapy

    Site-specific Forest-assembly of Single-Wall Carbon Nanotubes on Electron-beam Patterned SiOx/Si Substrates

    Full text link
    Based on electron-beam direct writing on the SiOx/Si substrates, favorable absorption sites for ferric cations (Fe3+ ions) were created on the surface oxide layer. This allowed Fe3+-assisted self-assembled arrays of single-wall carbon nanotube (SWNT) probes to be produced. Auger investigation indicated that the incident energetic electrons depleted oxygen, creating more dangling bonds around Si atoms at the surface of the SiOx layer. This resulted in a distinct difference in the friction forces from unexposed regions as measured by lateral force microscopy (LFM). Atomic force microscopy (AFM) affirmed that the irradiated domains absorbed considerably more Fe3+ ions upon immersion into pH 2.2 aqueous FeCl3 solution. This rendered a greater yield of FeO(OH)/FeOCl precipitates, primarily FeO(OH), upon subsequent washing with lightly basic dimethylformamide (DMF) solution. Such selective metalfunctionalization established the basis for the subsequent patterned forest-assembly of SWNTs as demonstrated by resonance Raman spectroscopy

    Surface patterning of carbon nanotubes can enhance their penetration through a phospholipid bilayer

    Full text link
    Nanotube patterning may occur naturally upon the spontaneous self-assembly of biomolecules onto the surface of single-walled carbon nanotubes (SWNTs). It results in periodically alternating bands of surface properties, ranging from relatively hydrophilic to hydrophobic, along the axis of the nanotube. Single Chain Mean Field (SCMF) theory has been used to estimate the free energy of systems in which a surface patterned nanotube penetrates a phospholipid bilayer. In contrast to un-patterned nanotubes with uniform surface properties, certain patterned nanotubes have been identified that display a relatively low and approximately constant system free energy (10 kT) as the nanotube traverses through the bilayer. These observations support the hypothesis that the spontaneous self-assembly of bio-molecules on the surface of SWNTs may facilitate nanotube transduction through cell membranes.Comment: Published in ACS Nano http://pubs.acs.org/doi/abs/10.1021/nn102763
    • …