527 research outputs found
Investigating and monitoring central nave vaults of the Turin Cathedral with Acoustic Emissions and Thrust Network Analysis
Ancient masonry constructions and historical buildings, such as cathedrals, are exposed to considerable risks attributed to factors like ageing and long-term exposure to both dynamic and static variations in loading conditions. In this study, an innovative and promising monitoring approach was applied to assess the structural integrity of the vault in the central nave of the Turin Cathedral. Specifically, the outcomes obtained from Acoustic Emissions (AE) are correlated with the insights derived from the Thrust Network Analysis (TNA) conducted on the structure. This analysis considers the structural elements introduced early in the twentieth century to mitigate horizontal forces. Acoustic Emission (AE) is a commonly employed technique in structural monitoring to detect and analyze elastic waves generated by crack formation, providing valuable information about structural damage. The Thrust Network Analysis (TNA) is an approach that applies Heyman's principles to represent stress in masonry vaults. This method models the stresses as a discrete network of forces, achieving equilibrium with gravitational loads. In this context, the results obtained by TNA analysis are strictly correlated with AE localization results
Deep-Learning-Based Onset Time Precision in Acoustic Emission Non-Destructive Testing
To investigate the actual health status and mechanical properties of structural materials, both direct and/or indirect investigation procedures can be used. The acoustic emission (AE) method is a non-destructive indirect structural health monitoring method based on the analysis of the elastic wave propagation inside the material under study induced during cracks and micro-cracks coalescence, opening, and formation process. To capture reliable ultrasonic elastic waveform data, piezoelectric sensors are typically employed which are directly and firmly fixed and attached to the specimen under study. For identifying the region of crack formation, thus the position of structural damage in its early stage, at least four sensors must be employed simultaneously. Furthermore, the identification of the onset time is crucial to accomplishing this task. In this study, the authors proposed a deep-learning-based solution based on a U-net architecture for identifying onset time with a method attempting to overcome the existing limitations of traditional threshold-based methods. The onset time precision obtained with this artificial intelligence-based (AI) paradigm is discussed on an acknowledged dataset available in the literature based on Pencil Lead Break (PLB) data, commonly used as a benchmark in the AE field. Finally, the method is tested on some real AE signals acquired during laboratory testing of reinforced concrete specimens. The results demonstrated the actual potential of the proposed AI-based method in future real-time monitoring real- world applications
Lewis Base-Catalysed Enantioselective Radical Conjugate Addition for the Synthesis of Enantioenriched Pyrrolidinones
We report a catalytic asymmetric protocol for the preparation of chiral pyrrolidinones proceeding via a radical pathway. The chemistry exploits the combination of photoredox catalysis and Lewis base catalysis to realise the first example of asymmetric radical conjugate addition to α,β-unsaturated anhydrides and esters. The reaction is initiated by photoredox activation of N-arylglycines to generate, upon decarboxylation, α-amino radicals. These radicals are then intercepted stereoselectively by α,β-unsaturated acyl ammonium intermediates, whose formation is mastered by a chiral isothiourea organocatalyst. Cyclisation leads to catalyst turnover and formation of enantioenriched pyrrolidinones. The utility of the protocol was demonstrated with application to the synthesis of biologically-active γ-amino butyric acids
Green solvents and restoration: Application of biomass-derived solvents in cleaning procedures
Blends of solvents from non-renewable sources, often polluting and toxic to humans, are routinely used in the restoration of painted artifacts. Here we present the application of three different green solvents (and their mixtures) as a viable alternative to the standard triad of solvents (acetone, ethanol, and isooctane) used in the solubility test for cleaning polychromic artworks.
Solketal (SOLK), γ-valerolactone (GVL), and 2-ethylhexyl pelargonate (ARGO) were selected among the solvents achievable from bio-based synthons such as glycerol, levulinic acid, and pelargonic acid, which are mainly produced from biomass and renewable feedstocks as exhausted vegetable oils, carbohydrates, and lignocellulose. Specifically, ARGO solvent was prepared by esterification reaction and characterized by nuclear magnetic resonance (NMR) and mass spectroscopy coupled to gas chromatography (GC–MS).
Hansen solubility parameters for each solvent were determined by a group contribution method, thus enabling their placement in the Teas graph. Their penetration ability in wooden specimens was investigated by evaluating the volume retention of each solvent with different coated specimens.
The solvent ability of the selected compounds was tested by visible and UV observations on specimens prepared with film-forming substances (Dammar, Mastic, Shellac, Paraloid® B72 and linseed oil) brushed onto glass plates.
Our results pointed out the suitability of this solvent triad for application to panel painting surfaces. The effectiveness of mixtures made with the above green solvent was successfully tested to remove a terpenic varnish from a 16th century oil painting on a wooden panel
Photovoltaic characterization of di-branched organic sensitizers for DSSCs.
In this work, the data on the effect of peripheral functionalization of a series of triphenylamine based di-branched dyes used as sensitizers in dye-sensitized solar cells are presented. The effect of different alkyl functionalities on the donor moiety upon the optical and photovoltaics parameters have been investigated in dye-sensitized solar cells (DSSCs) using a 10-ÎĽm TiO2 active layer. The absorption spectra, output efficiency, and incident photon to conversion efficiency of the DSSCs have been collected. The data can be exploited for properly designing efficient, stable, and industrially viable dyes for third generation solar devices
The quest for a molecular capsule assembled via halogen bonds
A halogen-bonded capsule is obtained via directed assembly of a rigid tetra(3-pyridyl) cavitand and a flexible tetra(4-iodotetrafluorophenyl) calix[4]arene. The pyridyl nitrogen atoms from one cavitand molecule interact with the iodine atoms of a single
calixarene molecule through short and directional I…N halogen bonds. The flexibility of the ethylenedioxy moieties on the calixarene platform results in positional flexibility of the
iodotetrafluorobenzene sites which, coupled with a supramolecular chelating effect, allow for an effective partner-induced geometric fitting between four nitrogen atoms on the cavitand and four iodine atoms on the calixarene
The effects of two gold-N-heterocyclic carbene (NHC) complexes in ovarian cancer cells: a redox proteomic study
Purpose: Ovarian cancer is the fifth leading cause of cancer-related deaths in women. Standard treatment consists of tumor debulking surgery followed by platinum and paclitaxel chemotherapy; yet, despite the initial response, about 70-75% of patients develop resistance to chemotherapy. Gold compounds represent a family of very promising anticancer drugs. Among them, we previously investigated the cytotoxic and pro-apoptotic properties of Au(NHC) and Au(NHC)2PF6, i.e., a monocarbene gold(I) complex and the corresponding bis(carbene) complex. Gold compounds are known to alter the redox state of cells interacting with free cysteine and selenocysteine residues of several proteins. Herein, a redox proteomic study has been carried out to elucidate the mechanisms of cytotoxicity in A2780 human ovarian cancer cells. Methods: A biotinylated iodoacetamide labeling method coupled with mass spectrometry was used to identify oxidation-sensitive protein cysteines. Results: Gold carbene complexes cause extensive oxidation of several cellular proteins; many affected proteins belong to two major functional classes: carbohydrate metabolism, and cytoskeleton organization/cell adhesion. Among the affected proteins, Glyceraldehyde-3-phosphate dehydrogenase inhibition was proved by enzymatic assays and by ESI-MS studies. We also found that Au(NHC)2PF6 inhibits mitochondrial respiration impairing complex I function. Concerning the oxidized cytoskeletal proteins, gold binding to the free cysteines of actin was demonstrated by ESI-MS analysis. Notably, both gold compounds affected cell migration and invasion. Conclusions: In this study, we deepened the mode of action of Au(NHC) and Au(NHC)2PF6, identifying common cellular targets but confirming their different influence on the mitochondrial function
Assessment of Streptococcus pneumoniae pilus islet-1 prevalence in carried and transmitted isolates from mother–infant pairs on the Thailand–Burma border
AbstractStreptococcus pneumoniae pilus islet-1 (PI–1)-encoded pilus enhances in vitro adhesion to the respiratory epithelium and may contribute to pneumococcal nasopharyngeal colonization and transmission. The pilus subunits are regarded as potential protein vaccine candidates. In this study, we sought to determine PI–1 prevalence in carried pneumococcal isolates and explore its relationship with transmissibility or carriage duration. We studied 896 pneumococcal isolates collected during a longitudinal carriage study that included monthly nasopharyngeal swabbing of 234 infants and their mothers between the ages of 1 and 24 months. These were cultured according to the WHO pneumococcal carriage detection protocol. PI-1 PCR and genotyping by multilocus sequence typing were performed on isolates chosen according to specific carriage and transmission definitions. Overall, 35.2% of the isolates were PI-1-positive, but PI-1 presence was restricted to ten of the 34 serotypes studied and was most frequently associated with serotypes 19F and 23F; 47.5% of transmitted and 43.3% of non-transmitted isolates were PI-1-positive (OR 1.2; 95% CI 0.8-1.7; p 0.4). The duration of first-ever infant pneumococcal carriage was significantly longer with PI-1-positive organisms, but this difference was not significant at the individual serotype level. In conclusion, PI-1 is commonly found in pneumococcal carriage isolates, but does not appear to be associated with pneumococcal transmissibility or carriage duration
FormulaciĂłn y propiedades de biopolĂmero de recubrimiento para semillas de manĂ (Arachis hypogaea L.)
En este trabajo se presenta el diseño de una biopelĂcula de recubrimiento biodegradable, formulada con macromolĂ©culas naturales como almidĂłn, proteĂna y glicerol para ser aplicada sobre semillas de manĂ, a fin de aumentar la resistencia del tegumento y favorecer la fluidez en la siembra. Se ensayaron diversas formulaciones variando la concentraciĂłn y tipo de los almidones. Dos formulaciones, una a base de almidĂłn de maĂz y otra de almidĂłn de mandioca, fueron caracterizadas en su reologĂa y en las biopelĂculas se determinaron propiedades de barrera, hidrataciĂłn y solubilidad en agua. Aplicadas sobre semillas se evaluaron sus caracterĂsticas tecnolĂłgicas como espesor de capa, capacidad de absorciĂłn-desorciĂłn de humedad y su aporte a la fluidez y resistencia al daño mecánico. Las semillas recubiertas con el biopolĂmero constituido con 3 % de almidĂłn de mandioca evidenciaron mayor resistencia mecánica y fluidez y buenas propiedades de barrera. Este trabajo aporta una formulaciĂłn para el recubrimiento biopolimĂ©rico de semillas de manĂ, que al estar constituido por sustancias naturales de grado alimenticio y biodegradables, posee potencialidad de implementaciĂłn en el marco de la agricultura sustentable.This work shows a biodegradable coating biofilm design formulated with natural macromolecules such as starch, proteins, and glycerol, for its application on peanut seeds, to increase tegument resistance and fluency in sowing. Several formulations were assayed varying the concentration and types of starch. Two formulations, one based on corn starch and the other on cassava starch, were characterized in their rheology and their barrier, hydration and water solubility properties were determined. In coated seeds, biofilm technological characteristics, such as layer thickness, moisture absorption-desorption, contribution to fluency and mechanical damage resistance were tested. Seeds coated with biopolymer made up of 3 % cassava starch showed increased mechanical resistance and enhanced fluency and barrier properties. This work provides a formulation for the biopolimeric coating of peanut seeds, which being composed of natural, food grade and biodegradable substances, has the potential to be implemented in sustainable agriculture.Fil: Montoya, P.. Universidad Nacional de CĂłrdoba; ArgentinaFil: Cosiansi, J.. Universidad Nacional de CĂłrdoba; ArgentinaFil: Grasso, F.. Universidad Nacional de CĂłrdoba; ArgentinaFil: Melchiorre, Mariana Noemi. Instituto Nacional de TecnologĂa Agropecuaria. Centro de Investigaciones Agropecuarias. Unidad de Estudios Agropecuarios - Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Unidad de Estudios Agropecuarios; Argentin
Glucagon-Like Peptide-1 Counteracts Oxidative Stress-Dependent Apoptosis of Human Cardiac Progenitor Cells by Inhibiting the Activation of the c-Jun N-terminal Protein Kinase Signaling Pathway
AbstractIncreased apoptosis of cardiac progenitor cells (CPCs) has been proposed as a mechanism of myocardial damage and dysfunction. Glucagon-like peptide-1 (GLP-1) has been shown to improve heart recovery and function after ischemia and to promote cell survival. The protective effects of GLP-1 on oxidative stress-induced apoptosis were investigated in human CPCs isolated from human heart biopsies. Mesenchymal-type cells were isolated from human heart biopsies, exhibited the marker profile of CPCs, differentiated toward the myocardiocyte, adipocyte, chondrocyte, and osteocyte lineages under appropriate culture conditions, and expressed functional GLP-1 receptors. CPCs were incubated with GLP-1 with or without hydrogen peroxide (H2O2). Phospho- and total proteins were detected by immunoblotting and immunofluorescence analysis. Gene expression was evaluated by quantitative RT-PCR. The role of the canonical GLP-1 receptor was assessed by using the receptor antagonist exendin(9–39) and receptor-specific silencer small interfering RNAs. Cell apoptosis was quantified by an ELISA assay and by flow cytometry-detected Annexin V. Exposure of CPCs to H2O2 induced a 2-fold increase in cell apoptosis, mediated by activation of the c-Jun N-terminal protein kinase (JNK) pathway. Preincubation of CPCs with GLP-1 avoided H2O2-triggered JNK phosphorylation and nuclear localization, and protected CPCs from apoptosis. The GLP-1 effects were markedly reduced by coincubation with the receptor antagonist exendin(9–39), small interfering RNA-mediated silencing of the GLP-1 receptor, and pretreatment with the protein kinase A inhibitor H89. In conclusion, activation of GLP-1 receptors prevents oxidative stress-mediated apoptosis in human CPCs by interfering with JNK activation and may represent an important mechanism for the cardioprotective effects of GLP-1
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