Quenching of the triplet state of safranine-O by aliphatic amines in AOT reverse micelles studied by transient absorption spectroscopy

The photophysics of Safranine-O (3,6-diamino-2,7-dimethyl-5 phenyl phenazinium chloride) (SfH+Cl-) was investigated in reverse micelles (RMs) of AOT  (sodium bis(2-ethylhexyl) sulfosuccinate) with special emphasis on the triplet state processes. The excited singlet state properties were measured by absorption and fluorescence spectroscopy. Steady state anisotropy was also measured as a function of the water content. All the measurements indicate that the dye is localized in the interface, sensing a medium of polarity similar to EtOH:water (3:1) mixtures. The triplet is formed in its monoprotonated form, independently of the pH of the water used to prepare the RMs. The  maximum of the T-T absorption spectrum in RMs confirms this conclusion. The triplet lifetime is much longer in AOT RMs than in homogeneous organic solvents. The intersystem crossing quantum yields are similar to those in organic solvents. A remarkable difference is observed in the quenching by aliphatic amines, while the quenching by the hydrophobic tributylamine is similar to that in methanol, the hydro-soluble triethanolamine is one order of magnitude more effective in RMs than in homogeneous solution. In the latter case  the quenching process is interpreted by a very fast intramicellar quenching, the overall kinetics being controlled by the exchange of amine molecules between RMs. Semireduced dye is formed in the quenching process in RMs in the di-protonated state with a comparable quantum yield to the monoprotonated state formed in homogeneous solvents. The results point to the advantage of the reverse micellar system for the generation of active radicals for the initiation of vinyl polymerization, since a much lower concentration of amine can be employed with similar quantum yields.Fil: Porcal, Gabriela Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Chesta, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Biasutti, Maria Alicia. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Bertolotti, Sonia Graciela. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Previtali, Carlos Mario. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin

Mesh sensitivity in discrete element simulation of flexible protection structures

The Discrete Element Method (DEM) has been employed in recent years to simulate flexible protection structures undergoing dynamic loading due to its inherent aptitude for dealing with inertial effects and large deformations. The individual structural elements are discretized with an arbitrary number of discrete elements, connected by spring-like remote interactions. In this work, we implement this approach using the parallel bond contact model and compare the numerical results at different discretization intervals with the analytical solutions of classical beam theory. Successively, we use the same model to simulate the punching test of a steel wire mesh and quantify the influence of a different number of elements on the macroscopic response

Non\u2011syndromic isolated dominant optic atrophy caused by the p.R468C mutation in the AFG3 like matrix AAA peptidase subunit 2 gene

Autosomal dominant optic atrophy (DOA) is the most frequent form of hereditary optic atrophy, a disease presenting with considerable inter- and intra-familial clinical variability. Although a number of mutations in different genes are now known to cause DOA, many cases remain undiagnosed. In an attempt to identify the underlying genetic defect, whole exome sequencing was performed in a 19-year-old male that had been affected by isolated DOA since childhood. The exome sequencing revealed a pathogenic mutation (p.R468C, c.1402C>T) in the AFG3 like matrix AAA peptidase subunit 2 (AFG3L2) gene, a gene known to be associated with spinocerebellar ataxia. The patient did not show any signs other than DOA. Thus, the result demonstrates the possibility that mutations in the AFG3L2 gene may be a cause of isolated autosomal DOA

THE USE OF TERRESTRIAL LASER SCANNING TECHNIQUES TO EVALUATE INDUSTRIAL MASONRY CHIMNEY VERTICALITY

Abstract. This paper presents a strategy to measure verticality deviations (i.e. inclination) of tall chimneys. The method uses laser scanning point clouds acquired around the chimney to estimate vertical deviations with millimeter-level precision. Horizontal slices derived from the point cloud allows us to inspect the geometry of the chimney at different heights. Two methods able to estimate the center at different levels are illustrated and discussed. A first solution is a manual approach that uses traditional CAD software, in which circle fitting is manually carried out through point cloud slices. The second method is instead automatic and provides not only center coordinates, but also statistics to evaluate metric quality. Two case studies are used to explain the procedures for the digital survey and the measurement of vertical deviations: the chimney in the old slaughterhouse of Piacenza (Italy), and the chimney in Leonardo Campus at Politecnico di Milano (Italy).</p

From survey to semantic representation for Cultural Heritage: the 3D modeling of recurring architectural elements

The digitization of Cultural Heritage paves the way for new approaches to surveying and restitution of historical sites. With a view to the management of integrated programs of documentation and conservation, the research is now focusing on the creation of information systems where to link the digital representation of a building to semantic knowledge. With reference to the emblematic case study of the Calci Charterhouse, also known as Pisa Charterhouse, this contribution illustrates an approach to be followed in the transition from 3D survey information, derived from laser scanner and photogrammetric techniques, to the creation of semantically enriched 3D models. The proposed approach is based on the recognition -segmentation and classification- of elements on the original raw point cloud, and on the manual mapping of NURBS elements on it. For this shape recognition process, reference to architectural treatises and vocabularies of classical architecture is a key step. The created building components are finally imported in a H-BIM environment, where they are enriched with semantic information related to historical knowledge, documentary sources and restoration activities

Photophysics and photochemistry of porphyrin core PAMAM dendrimers. Excited states interaction with quinones

Quenching of excited states of the meso-substituted tetraphenyl porphyrins with PAMAM branches, and one with PAMAM generation 1 peripherally-modified with thiazole groups by p-benzoquinones, were studied in DMF solution. Fluorescence lifetime measurements evidence a static component in the quenching process. The dynamic quenching rate constants were close to the diffusional limit except for the case of duroquinone. Apparent association constants of the porphyrin compounds with the quinones were determined by comparison of static and dynamic measurements of fluorescence quenching. The ground state interaction is very weak with the exception of tetrachlorobenzoquinone. The triplet state decay kinetics and the transient absorption spectra in the presence of the quinones were determined by laser flash photolysis. Triplet quenching rate constants were lower than those of singlet quenching. An electron transfer mechanism was proposed to explain the results. The long-time transient absorption spectra were assigned to the radical cation of the dyes. Relative radical yields were determined and a dependence on the side chains and the quencher was observed.Fil: Militello, María Paula. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Arbeloa, Ernesto Maximiliano. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Hernández Ramírez, Raquel E.. Tecnológico de Estudios Superiores de Coacalco; MéxicoFil: Lijanova, Irina Victorovna. Instituto Politécnico Nacional; MéxicoFil: Montejano, Hernan Alfredo. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Previtali, Carlos Mario. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Bertolotti, Sonia Graciela. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; Argentin

Semi-automated creation of accurate FEM meshes of heritage masonry walls from point cloud data

The structural analysis of buildings requires accurate spatial models. Additionally, pathologies such as settlement-induced damages are paramount in the assessment of heritage assets. This spatial information is used as a basis for Finite Element Method (FEM) meshes to evaluate the stability of the structure. Traditional data acquisition approaches rely on manual measurements which are labor intensive and error prone. Therefore, major simplifications are made to document structures efficiently. The goal of this research is to provide faster and more accurate procedures to capture the spatial information required by a FEM. This paper presents a semi-automated approach to create accurate models of complex heritage buildings for the purpose of structural analysis. By employing non-destructive techniques such as terrestrial laser scanning and photogrammetry, a complex mesh of the structure is created. Also, a methodology is proposed to capture crack information. A stepwise approach is elaborated to illustrate how the spatial information is adapted towards a FEM mesh. The results show a significant difference between the geometry our model and a traditional wire- frame model. Not only does accurate modelling result in deviating loads, it also affects the behavior of the object. Through the proposed approach, experts can develop highly accurate FEM meshes to assess the stability of the structure up to as-built conditionsPostprint (published version

From scan-to-BIM to a structural finite elements model of built heritage for dynamic simulation

The progress in information technology allows an innovative transformation of practices commonly involved in the engineering and construction field, especially in relation to the existing architectural heritage’s control and management activities. The proposed methodology takes advantage of an integrated 3D metric survey as a basis for an HBIM (Historic Building Information Modelling) model to be exploited for the definition of a Finite Elements Model (FEM). This paper aims to show the applicability of a digital process, stemmed from the integration in Rhinoceros 3D of a BIM structural model, leading to the dynamic simulation of the analytical FEM through PRO_SAP® (a PROfessional Structural Analysis Program). The described workflow investigates the interoperability issues, along with the difficulties in the Scan-to-HBIM processes, demonstrating how HBIM models can anyhow support operations aimed at maintaining and preserving existing historical assets, also from a structural point of view, even if with still persistent criticalities

Integrative IRT for documentation and interpretation of archaeological structures

The documentation of built heritage involves tangible and intangible features. Several morphological and metric aspects of architectural structures are acquired throughout a massive data capture system, such as the Terrestrial Laser Scanner (TLS) and the Structure from Motion (SfM) technique. They produce models that give information about the skin of architectural organism. Infrared Thermography (IRT) is one of the techniques used to investigate what is beyond the external layer. This technology is particularly significant in the diagnostics and conservation of the built heritage. In archaeology, the integration of data acquired through different sensors improves the analysis and the interpretation of findings that are incomplete or transformed. Starting from a topographic and photogrammetric survey, the procedure here proposed aims to combine the bidimensional IRT data together with the 3D point cloud. This system helps to overcome the Field of View (FoV) of each IRT image and provides a three-dimensional reading of the thermal behaviour of the object. This approach is based on the geometric constraints of the pair of RGB-IR images coming from two different sensors mounted inside a bi-camera commercial device. Knowing the approximate distance between the two sensors, and making the necessary simplifications allowed by the low resolution of the thermal sensor, we projected the colour of the IR images to the RGB point cloud. The procedure was applied is the so-called Nymphaeum of Egeria, an archaeological structure in the Caffarella Park (Rome, Italy), which is currently part of the Appia Antica Regional Park

Photophysics and reductive quenching reactivity of gadusol in solution

The photostability and photophysics of gadusol in aqueous solution has been studied. The photodecomposition quantum yields (ca. 4 × 10-2 and 1 × 10-4 at acidic and neutral pH, respectively) confirm the high photostability of the metabolite, independently of the presence of oxygen, under physiological conditions. The nature of the electronic transition of gadusol has been assigned as π → π* on the basis of the solvatochromic shifts of the UV absorption spectrum and the time-dependent density functional theory calculation of the vertical transition energies. The results from the photoacoustic calorimetry point to the rapid non-radiative decay as the dominant relaxation pathway of the excited species at pH 7, which is consistent with the proposed UV-sunscreening role of the molecule in the early atmosphere. Laser flash photolysis experiments probed that the ground state of the enolate form (gadusolate) undergoes electron transfer reactions with some triplet sensitizers in water or methanol solution. A rate constant of 2 × 108 M-1 s-1 has been determined for the quenching of rose bengal triplet state in water at pH 7. This reductive quenching reactivity may be considered as one of the underlying mechanisms that support the antioxidant capacity of gadusol in biological environments. © The Royal Society of Chemistry and Owner Societies 2011.Fil: Arbeloa, Ernesto Maximiliano. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Química; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Bertolotti, Sonia Graciela. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Churio, Maria Sandra. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata. Grupo de Investigación del Departamento de Química de la Unmdp | Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Físicas de Mar del Plata. Grupo de Investigación del Departamento de Química de la Unmdp; Argentin