Nonsmooth Nonconvex Variational Reconstruction for Electrical Impedance Tomography

Electrical Impedance Tomography is an imaging technique that aims to reconstruct the inner conductivity distribution of a medium starting from a set of measured voltages registered by a series of electrodes that are positioned on the surface of the medium. Such technique was used for the first time in geological studies in 1930 and then applied to industrial procedures. The first clinical use of EIT dates back to 1987. In 2018 EIT was validated in tissue engineering as a noninvasive and label-free imaging and monitoring tool for cell distribution (cell growth, differentiation and tissue formation) in 3D scaffolds. EIT problem can be split into a Forward and an Inverse problem. The aim of Forward EIT is to define the set of measured voltages starting from a known conductivity distribution. If the forward problem is characterized by a nonlinear mapping, called Forward Operator, from the conductivity distribution to the measured voltages, inverse EIT consists of inverting the Forward Operator. This leads to an ill-posed problem which requires regularization, either in the model or in the numerical method that is applied to define the solution. The inverse problem is modelled as a Nonlinear Least Squares problem, where one seeks to minimize the mismatch beetween the measured voltages and the ones generated by the reconstructed conductivity. Reconstruction techniques require the introduction of a regularization term which forces the reconstructed data to stick to certain prior information. In this dissertation, some state-of-the-art regularization methods are analyzed and compared via EIDORS, a specific software for EIT problems. The aim is to reconstruct the variation in conductivity within a 2D section of a 3D scaffold. Furthermore a variational formulation on a 2D mesh for a space-variant regularization is proposed, based on a combination of high order and nonconvex operators, which respectively seek to recover piecewise inhomogeneous and piecewise linear regions

Mechanism of the fluxional behaviour in (1–5-η-cycloheptadienyl)-(1–5-η-cycloheptatrienyl)iron

Evidence for a 1.2-shift mechanism of the 1-5-η-cycloheptatrienyl moiety with respect to the central iron atom of the title compound is presented together with absolute assignments of the ^(13)C n.m.r. chemical shifts of the C_(7)H_(7) ring. A low-temperature rocking motion of both rings can be frozen out at -70 °C

The intriguing methoxycarbonylation of trimethylsilylacetylene in the presence of Drent's catalytic system

The alkoxycarbonylation of trimethylsilylacetylene has been studied in order to develop an atom economic sustainable synthesis of 2-(trimethylsilyl)acrylates, a family of valuable intermediates. Pd(OAc)2 in combination with CH3SO3H and diphenyl-(pyridin-2-yl)phosphine or diphenyl-(6-methyl-pyridin-2-yl)phosphine is an active catalyst for the reaction affording mixtures of the sought 2-(trimethylsilyl)acrylate and the isomeric 3-(trimethylsilyl)acrylate. The phosphine ligand has a dramatic effect on the reaction. When employing diphenyl-(pyridin-2-yl)phosphine, it is necessary to carry out the reaction at 80°C in order to observe a modest catalytic activity, and the product is an almost equimolecular mixture of the two isomeric esters. On the contrary, when employing diphenyl-(6-methyl-pyridin-2-yl)phosphine, the reaction proceeds under much milder conditions affording with high rate (turnover frequency [TOF] up to 1200 h−1) and selectivity (>95%) of the sought 2-(trimethylsilyl)acrylate. The reaction conditions have been optimized, and the effects of phosphine/palladium, acid/palladium, reaction time, temperature, and CO pressure have been investigated. © 2021 The Authors. Applied Organometallic Chemistry published by John Wiley & Sons Ltd

[PdCl2{8-(di-tert-butylphosphinooxy)quinoline)}]: a highly efficient catalyst for Suzuki-Miyaura reaction

The complex [PdCl2(P-N)] containing the basic and sterically demanding 8-(di-tert-butylphosphinooxy)quinoline ligand (P-N) is a highly efficient catalyst for the coupling of phenylboronic acid with aryl bromides or aryl chlorides. The influence of solvent and base has been investigated, the highest rates being observed at 110 C in toluene with K2CO3 as the base. With aryl bromides the reaction rates are almost independent on the electronic properties of the para aryl substituents, on the contrary, reduced reaction rates are observed when bulky substituents are present on the substrate. Nevertheless the coupling of 2-bromo-1,3,5-trimethylbenzene with phenylboronic acid can be carried out to completion in 2 h using a catalyst loading of 0.02 mol %. Under optimized reaction conditions, turnover frequencies as high as 1900 h(-1) can be obtained in the coupling of 4-chloroacetophenone with phenylboronic acid: lower reaction rates are obtained with Substrates bearing EDG substituents on the aryl group. (C) 2009 Elsevier Ltd. All rights reserved

Due algoritmi per la fattorizzazione matriciale non negativa con applicazione al clustering

In questa tesi vengono descritti il problema della fattorizzazione non negativa ortogonale (ONMF) con applicazione al clustering e due algoritmi elaborati da F. Pompili, N. Gillis, P.A. Absil e F. Gilneur per l'approssimazione numerica della coppia di matrici soluzione di tale problema: il primo algoritmo legato a una variante delle k-medie sferiche e il secondo basato sul metodo della Lagrangiana aumentata. Particolare attenzione viene prestata alla base teorica su cui si fonda il primo algoritmo, cioè l'equivalenza tra il problema delle k-medie sferiche pesate e il problema ONMF descritta dal Teorema 2.6. Per ciascun algoritmo vengono analizzati punti di forza e di debolezza e suggerita la tipologia di data set per cui risultano più indicati al fine di determinare un'opportuna divisione in cluster. Il primo capitolo, di carattere introduttivo, descrive i concetti di clustering e di fattorizzazione non negativa, proponendo una formulazione matematica utile ai fini della trattazione. Il secondo capitolo è dedicato all'algoritmo EMONMF, di cui è proposta la descrizione teorica e l'applicazione al problema di text clustering con oggetto una matrice termine-documento di articoli medici. Il terzo capitolo è dedicato all'algoritmo ONPMF di cui sono descritti i metodi di ottimizzazione su cui è costruito, cioè il metodo del gradiente proiettato e della Lagrangiana aumentata, e gli esperimenti numerici sono applicati all'Iris data set contenuto nel file matlab fisheriris. Infine, nel quarto e ultimo capitolo vengono proposti due confronti numerici degli algoritmi, che vengono analizzati in termini di iterazioni, tempi di elaborazione, stabilità e precisione della fattorizzazione e del clustering. Il primo confronto è applicato all'hyperspectral unmixing con oggetto il data set Hubble e il secondo è applicato al pattern recognition con oggetto U.S. Postal Service database. I codici Matlab sono disponibili all'indirizzo https://github.com/filippo-p/onmf

Polyamidoamide Dendrimers and Cross-Linking Agents for Stabilized Bioenzymatic Resistant Metal-Free Bovine Collagen

The work reports the use of polyamidoamine dendrimers (PAMAM) and a cross-linking agent, 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide/N-hydroxysuccinimide (EDC/NHS) or 4-(4,6-dimethoxy[1,3,5]triazin-2-yl)-4-methyl-morpholinium chloride (DMTMM), for the thermal stabilization of dermal bovine collagen. The efficiency of EDC/NHS/PAMAM and DMTMM/PAMAM in the cross-linking of collagen is correlated to the increase of the collagen shrinkage temperature (Ts), measured by differential scanning calorimetry (DSC). An alternative enzymatic protocol was adopted to measure the degradability of EDC/NHS/PAMAM tanned hides; these data are correlated to the thermal stability values measured by DSC. In the presence of PAMAMs, EDC/NHS provides very high stabilization of bovine dermal collagen, giving Ts of up to 95 °C, while DMTMM achieves lower stabilization. Preliminary tanning tests carried out in best reaction conditions show that EDC/NHS/PAMAM could be an interesting, environmentally-sustainable tanning system which is completely free of metals, formaldehyde, and phenols. Two new unreported dendrimeric species were synthesized and employed

Phenotypical variation and taxonomic correlates of five closely related Andean species of Poa (Poaceae) along geographic and climatic gradients

Poa anfamensis, P. jujuyensis, P.lilloi, P. parviceps and P. scaberula (Poaceae) are a group of morphologically similar species. These species inhabit cool grasslands and mesic puna. They are highly polymorphic and their circumscriptions are uncertain, especially the entities around P. scaberula. Univariate and multivariate analyses (PCA and DA) were conducted to evaluate the morphological variation among 150 herbarium specimens identified as P. anfamensis, P. jujuyensis, P. lilloi, P. parviceps and P. scaberula. Forty morphological characters were included and their patterns of variation were analyzed among specimens, together with their relationship with environmental variables, using correlation analysis. The relationships between morphological variation and geographical distance, and climatic variables among specimens, were compared with Mantel permutation tests. Taxa were delimited according to the observed clustering of specimens in the PCA plots and DA, and diagnostic characters were identified. The five taxa showed continuous morphological variation. Morphological variation is explained by geographical and climatic factors such as elevation, geographical distance, latitudinal and longitudinal gradients, temperature and precipitation in the different sites in the Andes. Altitudinal and geographical distance are apparently more decisive factors in phenotypic differentiation and could have played a large role in interspecific differentiation among Poa entities, as shown by the stronger and significant association between vegetative and reproductive phenotype and altitudinal distance, and between vegetative and reproductive phenotype and geographical distance. In addition, we observed uncoupling among vegetative and floral characters in Poa specimens that grow along environmental gradients; these characters are responding independently to different abiotic forces promoting genetic divergence and speciation. Based on the results, P. anfamensis and P. parviceps are synonymised with P. scaberula, and P. jujuyensis is synonymised with P. lilloi.Fil: Scrivanti, Lidia Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); ArgentinaFil: Mestre, Luciana Mariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Anton, Ana Maria Ramona. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); Argentin

Synthesis of 4-Isobutylbenzaldehyde an Important Intermediate for the Fragrance (+)- and (-)-Silvial®

The synthesis of 4-isobutylbenzaldehyde, a valuable precursor for the fragrance Silvial® (3-(4-isobutylphenyl)-2-methylpropanal), is reported. Three different synthetic approaches are reported starting either from 4-isobutylbenzoic acid (via benzyl alcohol, or via acyl chloride), or by Suzuki-Miyaura cross-coupling reaction between 4-bromobenzaldehyde and 2-methylpropylboronic acid

Synthesis of the Chiral Fragrance Methyl Chamomile by Asymmetric Hydrogenation

An alternative synthesis of enantiomerically enriched 2-methylpentanoic butyl ester (Methyl Chamomile) is proposed. The process entails three different steps: the key one is the asymmetric hydrogenation of 2-methylenpentanoic acid catalysed by a Ru(II) complex and a chiral diphosphine

Teaching plant diversity at University level: an innovative didactic approach

Se implementó una propuesta didáctica innovadora en la asignatura Diversidad Vegetal II (Biología, Universidad Nacional de Córdoba) a partir de problemas y preguntas, promoviendo la participación activa de los alumnos en el aprendizaje. Se realizó una encuesta para evaluar el logro de objetivos, la percepción de los alumnos y las falencias en la implementación. La mayoría de los alumnos calificó como buena o muy buena la propuesta general y los trabajos prácticos, considerando adecuado el modo de evaluación. El balance entre las distintas actividades fue razonable sólo para la mitad de los alumnos, aspecto que debe ser reconsiderado. Observamos un gran entusiasmo y motivación en los alumnos por asistir y participar en las clases, donde se sintieron estimulados para, con la guía de los docentes, buscar información, discutirla e intentar autogestionar el conocimiento sobre plantas.An innovative didactic proposal was implemented for the discipline of Vascular Plant Diversity (Biology, National University of Córdoba, Argentine) based on problems and research questions to promote the active participation of students in the learning process. An interview was performed to evaluate objectives, student perception, and inaccuracies in the implementation of the proposal. Most students rated the general proposal and the practical activities as good or very good, and said that the evaluations were adequate. The balance of the different activities was adequate for only half of the students. Thus, we need to revise this point. We perceived a great enthusiasm and motivation of the students to participate in the different class activities. They were stimulated to search and discuss the information, and to obtain by themselves the knowledge on plants through the professor’s guide.Fil: Galetto, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Urcelay, Roberto Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Torres, Carolina Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Nattero, Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Romanutti, Alejandra Aida. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Scrivanti, Lidia Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Anton, Ana Maria Ramona. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santiago del Estero. Universidad Nacional de Santiago del Estero. Centro de Investigaciones y Transferencia de Santiago del Estero; Argentin