Letteratura scientifica selezionata sul tema "Flacking"

This paper reports the diagnostic research of deteriorated paint layers from three mural panels made by Almada Negreiros found in the Alcântara Maritime Station in Lisbon. The aim was to understand the main decay phenomena to aid future conservation works. The methodology comprised in-situ analyses by technical photography in Vis, Vis-RaK and UVF, p-OM and h-EDXRF; micro sampling; OM, SEM-EDS, μ-XRD, μ-Raman, µ-FT-IR and Py-GC/MS. Preliminary results show that all the paint layers analyzed are affected by salts (alkali sulphates) that over time have caused flacking, lack of cohesion, erosion, and lacunae. The light greenish/greenish bluish paint layers in all three panels are the most affected. No organic binders were identified, only the presence of vinyl polymer in glossy paint surfaces.

Background: Huntington’s disease (HD) is a dominantly transmitted progressive neurodegenerative disorder due to abnormal expansion of cytosine-adenine-guanine (CAG) repeats in the huntingtin gene. Materials and Methods: The study involved a total of 35 HD patients identified through clinical evaluations. CAG repeats expansion analysis was conducted using polymerase chain reaction (PCR) to confirm positive cases. Results: Employing CAG flacking PCR in 35 cases, 19 tested positive, predominantly displaying CAG repeats in the range of 40–50. Noteworthy cases include a 5-month-old patient with 44 CAG repeats and an 80-year-old patient with 46 CAG repeats. Conclusion: The identification of the genetic defect in HD permits direct genetic testing to comprehend the complexities of HD in India, aiming for effective approaches in diagnosis, treatment, and prevention.

Denisova Cave in the Altai Mountains is a key site for investigation the ancient history of North and Central Asia and the processes of interaction between groups of hominins that have inhabited this territory over the past 300,000 years. This article presents the new results of the Early Upper Paleolithic archaeological materials investigation from Denisova Cave. In 2017–2019 in the South Chamber of the cave, Pleistocene deposits of layer 11 were excavated, which accumulated in the first half of MIS 3. The general paleogeographic estimation of natural complexes in the vicinity of the cave during the formation of layer 11 is based on the results of investigation a representative collection of large mammals and small vertebrates bone remains. These data evidence to the mosaic nature of landscapes characterized of the mountainous country, with steppe and rocky biotopes predominating. In the lithic industry from layer 11, primary flacking is characterized by parallel technology, aimed at obtaining elongated flakes, large blades and small bladelets. A radial technique was used to obtain short and shortened blanks. The toolkit contains expressive specimens of end-scrapers, burins, and retouched blades with a well-defined Upper Paleolithic morphology. At the same time, a significant share in this industry is made by the Middle Paleolithic component, represented by various types of sidescrapers, as well as denticulate, notched and spur-like tools. Along with the lithic industry, formal bone tools such as eyed needles, awls, points, and polishers were discovered. A representative series of various personal ornaments made of animal teeth and bones, mammoth ivory, gemstone, and other materials includes beads, pendants, tubular beads, rings and tiaras. The continuity of the technical and typological sequence in the development of the industries of the Denisova Cave suggests the formation of the Upper Paleolithic traditions on a local Middle Paleolithic basis. These materials are associated with the Ust-Karakol industrial variant identified in the Early Upper Paleolithic of Altai Mountains.

Large concrete structures such as buildings, bridges, and tunnels are aging. In Japan and many other countries, those built during economic reconstruction after World War II are about 60 to 70 years old, and flacking and other problems are becoming more noticeable. Periodic inspections were made mandatory by government and ministerial ordinance during the 2013-2014 fiscal year, and inspections based on the new standards have just begun. There are various methods to check the soundness of concrete, but the hammering test is widely used because it does not require special equipment. However, long experience is required to master the hammering test. Therefore, mechanization is desired. Although the difference between the sound of a defective part and a normal part is very small, we have shown that neural network is useful in our research. To use this technology in the actual field, it is necessary to meet the forms of concrete structures in various conditions. For example, flacking in concrete exists at various depths, and it is impossible to learn about flacking in all cases. This paper presents the results of a study of the possibility of finding flacking at different depths with a single inspection learning model and an idea to increase the accuracy of a learning model when we use a rolling hammer.

AbstractKRAS is one of the most highly mutated oncoproteins, which is overexpressed in various human cancers and implicated in poor survival. The G-quadruplex formed in KRAS oncogene promoter (KRAS-G4) is a transcriptional modulator and amenable to small molecule targeting. However, no available KRAS-G4-ligand complex structure has yet been determined, which seriously hinders the structure-based rational design of KRAS-G4 targeting drugs. In this study, we report the NMR solution structures of a bulge-containing KRAS-G4 bound to berberine and coptisine, respectively. The determined complex structure shows a 2:1 binding stoichiometry with each compound recruiting the adjacent flacking adenine residue to form a “quasi-triad plane” that stacks over the two external G-tetrads. The binding involves both π-stacking and electrostatic interactions. Moreover, berberine and coptisine significantly lowered the KRAS mRNA levels in cancer cells. Our study thus provides molecular details of ligand interactions with KRAS-G4 and is beneficial for the design of specific KRAS-G4-interactive drugs.

Un des enjeux de l'aéronautique est de réduire l'impact environnemental des avions. Cet objectif se traduit par le développement de solutions alternatives aux matériaux métalliques comme les composites à matrice céramique. Pour les applications visées, les pièces sont soumises à des environnements thermomécaniques et physico-chimiques (oxydation/corrosion) très sévères pouvant mener à la dégradation du matériau et à une limitation de sa durée de vie. Pour protéger le composite à matrice céramique (CMC), les pièces sont revêtues de barrières environnementales (EBC) qui limitent la corrosion du CMC. La compréhension des mécanismes d'endommagement des EBC sur CMC est donc cruciale pour le développement des pièces en CMC à base carbure.Dans ce contexte, cette thèse s'est focalisée sur le comportement aux interfaces des différents constituants du système pour analyser la tenue du revêtement sur CMC. Il s'agit ainsi, d'une part, de proposer et de mettre en place des essais à l'ambiante et à haute température pour quantifier l'amorçage et la propagation de décohésions aux interfaces et de caractériser les propriétés associées, telles que l'énergie d'adhérence du revêtement sur le CMC, en utilisant différentes méthodes expérimentales de suivi de fissuration par méthodes optiques. D'autre part, le but est de proposer un dialogue étroit entre les essais et les modélisations associées. Pour cela des essais de flexion 4 points ont été menés à température ambiante et à 1000°C afin de faire propager des fissures stables à l'interface du système. Des mesures de champs cinématiques par corrélation d'images ont permis d'alimenter des simulations éléments finis afin de suivre la propagation des fissures et d'extraire une énergie d'adhérence interfaciale à l'échelle macroscopique. Ces essais et leur exploitation ont servi à caractériser la phase de propagation pour les deux températures et de comparer l'adhérence de systèmes sains et de systèmes préalablement vieillis sous environnement oxydant. Dans un deuxième temps, des essais au banc laser avec la présence de gradients thermiques au sein du système ont permis de caractériser la phase d'amorçage. Des observations au microscope électronique à balayage, l'utilisation de caméras thermiques et de capteurs d'émission acoustique sont venus compléter la base de données expérimentales
One of the challenges in aeronautics is to reduce the environmental impact of airplanes. This objective is pursued through the development of alternative solutions to metallic materials such as ceramic matrix composites. For the intended applications, the components are exposed to extremely severe thermomechanical and physicochemical environments (oxidation/corrosion), which can lead to material degradation and limit their lifespan. To protect the ceramic matrix composite (CMC), the components are coated with environmental barrier coatings (EBC) that mitigate the corrosion of the CMC. Understanding the damage mechanisms of EBC on CMC is therefore crucial for the development of carbide-based CMC components.In this context, this thesis focused on the behavior at the interfaces of the different constituents of the system to analyze the adhesion of the coating on the CMC. The aim is, on the one hand, to propose and implement tests at ambient and high temperatures to quantify the initiation and propagation of delamination at the interfaces and to characterize the associated properties, such as the adhesion energy of the coating on the CMC, using various experimental crack-tracking methods based on optical techniques. On the other hand, the goal is to establish a close interaction between the tests and the associated modeling. For this purpose, four-point bending tests were conducted at room temperature and at 1000°C to propagate stable cracks at the interface of the system. Kinematic field measurements through image correlation were used to inform finite element simulations in order to track crack propagation and extract interfacial adhesion energy at the macroscopic scale. These tests and their analysis were used to characterize the propagation phase at both temperatures and to compare the adhesion of pristine systems with systems that had been previously aged in an oxidizing environment. In a second phase, laser bench tests with the presence of thermal gradients within the system allowed for the characterization of the initiation phase. Scanning electron microscope observations, along with the use of thermal cameras and acoustic emission sensors, complemented the experimental database

Abstract Structure-ice interaction is a complex process. The related failure process may include intermediate failures of ice, e.g. flacking, that decreases the load level temporarily before larger failures like bending failure occurs. Simultaneously, loads on a frame move and can reach a level of MN. The loads are commonly determined from the structural response with strain gauge measurements where the noise may be few kNs. As the changes in load level related to intermediate failures may be at the same level as noise, it is difficult to separate noise from the measurements. Empirical Mode Decomposition is a relatively new method in engineering that considers the measurement signal to be composed of a set of functions. The method parses the measurement data into Intrinsic Mode Functions that represent the true data and noise. Removing the modes related to noise enables the use of the method as a filter. This study applies the described filtration technique to the full-scale measurements conducted onboard S.A. Agulhas II in the Baltic Sea. The results demonstrate a good applicability of the method for the filtration of the data that can be applied in the load identification from the measurement data in the future studies.