565 research outputs found

    V Jornadas de Archiveros de Universidades, Universidad de Córdoba, 28 y 29 de abril de 1999

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    Description of the 5th Congress of Archivists of Universities in the University of Cordova 28th-29th April 199

    Joan Roig i Soler: una certa imatge de Badalona

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    L'organització de la Junta Corregimental de Cervera (1808-1814)

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    Solvent effects on the properties of hyperbranched polythiophenes

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    The structural and electronic properties of all-thiophene dendrimers and dendrons in solution have been evaluated using very different theoretical approaches based on quantum mechanical (QM) and hybrid QM/molecular mechanics (MM) methodologies: (i) calculations on minimum energy conformations using an implicit solvation model in combination with density functional theory (DFT) or time-dependent DFT (TD-DFT) methods; (ii) hybrid QM/MM calculations, in which the solute and solvent molecules are represented at the DFT level as point charges, respectively, on snapshots extracted from classical molecular dynamics (MD) simulations using explicit solvent molecules, and (iii) QM/MM-MD trajectories in which the solute is described at the DFT or TD-DFT level and the explicit solvent molecules are represented using classical force-fields. Calculations have been performed in dichloromethane, tetrahydrofuran and dimethylformamide. A comparison of the results obtained using the different approaches with the available experimental data indicates that the incorporation of effects associated with both the conformational dynamics of the dendrimer and the explicit solvent molecules is strictly necessary to satisfactorily reproduce the properties of the investigated systems. Accordingly, QM/MM-MD simulations are able to capture such effects providing a reliable description of electronic properties–conformational flexibility relationships in all-Th dendrimers.Peer ReviewedPostprint (author's final draft

    A Capability-Centric Approach to Cyber Risk Assessment and Mitigation

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    Cyber-enabled systems are increasingly ubiquitous and interconnected, showing up in traditional enterprise settings as well as increasingly diverse contexts, including critical infrastructure, avionics, cars, smartphones, home automation, and medical devices. Meanwhile, the impact of cyber attacks against these systems on our missions, business objectives, and personal lives has never been greater. Despite these stakes, the analysis of cyber risk and mitigations to that risk tends to be a subjective, labor-intensive, and costly endeavor, with results that can be as suspect as they are perishable. We identified the following gaps in those risk results: concerns for (1) their repeatability/reproducibility, (2) the time required to obtain them, and (3) the completeness of the analysis per the degree of attack surface coverage. In this dissertation, we consider whether it is possible to make progress in addressing these gaps with the introduction of a new artifact called “BluGen.” BluGen is an automated platform for cyber risk assessment that employs a set of new risk analytics together with a highly-structured underlying cyber knowledge management repository. To help evaluate the hypotheses tied to the gaps identified, we conducted a study comparing BluGen to a cyber risk assessment methodology called EVRA. EVRA is representative of current practice and has been applied extensively over the past eight years to both fielded systems and systems under design. We used Design Science principles in the construction and investigation of BluGen, during which we considered each of the three gaps. The results of our investigation found support for the hypotheses tied to the gaps that BluGen is designed to address. Specifically, BluGen helps address the first gap by virtue of its methods/analytics executing as deterministic, automated processes. In the same way, BluGen helps address the second gap by producing its results at machine speeds in no worse than quadratic time complexity, seconds in this case. This result compares to the 25 hours that the EVRA team required to perform the same analysis. BluGen helps to address the third gap via its use of an underlying knowledge repository of cyber-related threats, mappings of those threats to cyber assets, and mappings of mitigations to the threats. The results show that manual analysis using EVRA covered about 12% of the attack surface considered by BluGen

    El Arte español y la primera exposición de industrias artísticas /

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    Forma part del projecte: Biblioteca Digital d'Història de l'Art Hispànic (UAB)Localització de l'original: Biblioteca Museu Víctor BalaguerConferència llegida per Antoni García Llansó (1854-1914) al Círculo de Bellas Artes de Barcelona, relacionada amb la Primera Exposición de indústrias artísticas i l'art espanyolConferencia leída por Antonio García Llansó (1854-1914) en el Círculo de Bellas Artes de Barcelona, relacionada con la Primera Exposición de industrias artísticas y el arte españolPaper read by Antonio García Llansó (1854-1914) at the Círculo de Bellas Artes of Barcelona related to the First Exhibition of Artistic Industries and Spanish ar

    Soluble polythiophenes as anticorrosive additives for marine epoxy paints

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    This study compares the resistance against corrosion of a marine epoxy primer modified with Zn-3(PO4)(2) (10 wt%) or a small concentration (0.3 wt%) of conducting polymer (CP) as inorganic or organic anticorrosive pigment, respectively. More specifically, the behavior of three different CPs has been evaluated: polyaniline (PAni) emeraldine base, poly(3-thiophen-3-yl-acrylic acid methyl ester) and poly(2-thiophen-3-yl-malonic acid dimethyl ester), the latter two being soluble polythiophene (PTh) derivatives bearing carboxylate side groups. In a first stage, the structural, thermal, and mechanical properties of all the modified epoxy coatings were characterized using infrared spectroscopy, thermogravimetric analyses and stress-strain assays, respectively. After this, accelerated corrosion assays have evidenced that the degree of protection imparted by a small concentration of PAni is higher than that obtained using 10wt% of Zn-3(PO4)(2). Indeed, PAni has been found to be more effective as anticorrosive additive than the two PTh derivatives. This fact has been attributed to the electroactivity of the former, which is higher than that of the latter. Thus, the ability to store charge has been proposed to be also responsible of protection against corrosion imparted by organic additives, based on CPs.Peer ReviewedPostprint (author’s final draft

    Nanoperforations in poly(lactic acid) free-standing nanomembranes to promote interactions with cell filopodia

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    Nanoperforated poly(lactic acid) (PLA) free-standing nanomembranes (FsNMs) have been prepared using a two-step process: (1) spin-coating a mixture of immiscible polymers to provoke phase segregation and formation of appropriated nanofeatures (i.e. phase separation domains with dimensions similar to the entire film thickness); and (2) selective solvent etching to transform such nanofeatures into nanoperforations. For this purpose, PLA has been mixed with polyethylene glycol (PEG) and poly(vinyl alcohol) (PVA). Unfortunately, the characteristics of PLA:PEG mixtures were not appropriated to prepare nanoperforated FsNMs. In contrast, perforated PLA FsNMs with pores crossing the entire film thickness, which have been characterized by scanning electron microscopy and atomic force microscopy, were obtained using PLA:PVA mixtures. The diameter (¿) of such pores has been controlled through both the PLA:PVA ratio and the processing conditions of the mixtures, FsNMs with pores of ¿ ˜ 0.8 µm, 170 nm and 65 nm being achieved. Investigations on nanoperforated FsNMs (i.e. those with ¿ ˜ 170 and 65 nm), which are the more regular, reveal that pores crossing the entire membrane thickness do not affect the surface wettability of PLA but drastically enhances the cellular response of this biomaterial. Thus, cell proliferation assays indicate that cell viability in PLA with perforations of ¿ ˜ 170 nm is ~2.6 and ~2.2 higher than in non-perforated PLA and PLA with perforations of ¿ ˜ 65 nm, respectively. This excellent response has been attributed to the similarity between the nanoperforations with ¿ ˜ 170 nm and the filopodia filaments in cells (¿ ˜ 100–200 nm), which play a crucial role in cell migration processes. The favorable interaction between the perforated membrane nanofeatures and cell filopodia has been corroborated by optical and scanning electron microscopies.Peer ReviewedPostprint (author's final draft
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