Fabrication of corrugated Ge-doped silica fibers

We present a method of fabricating Ge-doped SiO2 fibers with corrugations around their full circumference for a desired length in the longitudinal direction. The procedure comprises three steps: hydrogenation of Ge-doped SiO2 fibers to increase photosensitivity, recording of Bragg gratings with ultraviolet light to achieve modulation of refractive index, and chemical etching. Finite-length, radially corrugated fibers may be used as couplers. Corrugated tapered fibers are used as high energy throughput probes in scanning near-field optical microscopy

Selective laser melting of a high precision turbomachinery application in IN718 alloy

The paper describes the manufacture of an outlet guide vane (OGV) component, in IN718 alloy, used in jet engines by Selective Laser Melting (SLM). The OGV component is a static part in the last stage of the compressor and is characterised as a series of airfoils or vanes secured by two flanged rings. The part tolerances at the leading and trailing edge require a high dimensional precision of +/-0.072 m whilst the profile tolerances are slightly more generous. The current challenge to manufacture a prototype OGV in IN718 alloy from a wrought stock involves a lengthy machining process in a hard-to-machine alloy. The tooling access is greatly restricted between the curved vanes, and the process involves careful fixturing and process management to mitigate residual stress in the component arising from the removal of material.Partial funding of this research by the project of Polish National Agency for Academic Exchange (NAWA, PPI/APM/2018/1/00045/U/001), Poland

Study of the impact resistance of laminated composites based on Elium acrylic matrix subjected to prior fatigue aging

La résistance à l'impact est l'une des caractéristiques les plus essentielles des structures composites, par conséquent, son examen pour un nouveau matériau a une importance fondamentale. Cette thèse de doctorat est consacrée à la caractérisation de la résine thermoplastique ELIUM Acrylique renforcée par un tissu de fibres de verre tissées, qui appartient à une nouvelle catégorie de matériaux nécessitant des tests poussés avant leur application dans l'industrie. Sa haute résistance, son faible poids ainsi que son faible coût de production offrent d'excellentes opportunités pour de nombreuses applications dans l'industrie automobile en remplacement des stratifiés à base de polymères thermodurcissables. Cette étude présente un travail expérimental en lien avec l'effet de l'endommagement dû au vieillissement en fatigue à faible et haut nombre de cycles, de deux groupes de composites [0°/90°]4 et [45°/ 45°]4, sur leurs résistances à l'impact basse et grande vitesse. Une comparaison entre les données expérimentales et les résultats issues des simulations numériques au moyen d'un modèle macroscopique proposé pour les échantillons GFRE [0°/90°]4 non vieillis de 1.8 mm d'épaisseur est présentée. La réponse des matériaux au chargement en fatigue a été évaluée à travers l'analyse de la variation de rigidité. Ce programme de vieillissement en fatigue a été interrompu pour une valeur donnée de la chute de la raideur, avant la rupture de l'éprouvette. La rigidité initiale a été réduite d'environ 17 % pour le composite GFRE [0°/90°]4, après les tests LCF ou HCF. Cette réduction était beaucoup plus prononcée dans le cas du composite GFRE [45°/45°]4. Elle était estimée à 48 %. La résistance à l'impact basse vitesse a été mesurée en termes de force maximale, d'énergie absorbée et de seuil de pénétration, tandis que la résistance à l'impact grande vitesse a été mesurée en termes de limite balistique et de dissipation de l'énergie totale. Les éprouvettes non vieillies impactées à des énergies de 5 J, 10 J et 30 J n'ont pas été perforées et arborent une grande capacité à faire rebondir l'impacteur. Les composites impactés, ayant été soumis au préalable à la fatigue à faible nombre de cycles (LCF) ont montré la plus forte diminution de la pente initiale sur courbes caractéristiques de la force en fonction du déplacement. Cette réduction significative de la rigidité est causée par la fissuration de la matrice et le décollement de l'interface entre les fibres et la matrice. La réduction de la force maximale pour les essais réalisés à une énergie d'impact de 50 J pour les composites vieillies : GFRE [0°/90°]4 et GFRE [45°/45°]4 était d'environ de 11 % et 19 %, respectivement. L'analyse de l'évolution de l'énergie absorbée lors des tests d'impact a permis de confirmer que les matériaux vieillis GFRE [45°/45°]4 présentaient la plus faible résistance aux chocs. Comme pour les résultats obtenus en impact basse vitesse, l'analyse de la dissipation d'énergie et de l'évolution de la force d'impact lors des essais de perforation a permis de conclure que les plaques composites GFRE [0°/90°]4, ayant au préalable subi un chargement en fatigue, avaient les meilleures performances balistiques et une dissipation d'énergie plus élevée que celle du composite GFRE [45°/45°]4. Il a également été observé que les composites GFRE [45°/45°]4 vieillis en fatigue par chargement cyclique à une contrainte inférieure ou supérieure à la limite élastique avaient des limites balistiques inférieures de 20 m/s à celles de composites vieillies GFRE [0°/90°]4. Les prédictions numériques des limites balistiques, des vitesses résiduelles ainsi que l'analyse de l'absorption d'énergie réalisée à l'aide du code éléments finis ABAQUS/Explicit ont montré un bon accord avec les données expérimentales et ont confirmé la pertinence de l'approche proposée.Impact resistance is one of the most critical features of the composite structures, and therefore, its examination for a new material has a fundamental importance. This thesis is devoted to the characterization of the fully recyclable thermoplastic ELIUM Acrylic resin reinforced by glass fabric woven that belongs to a new category of materials requiring advanced testing before their application in responsible elements of engineering structures. Its high strength, low weight as well as low production cost give an excellent opportunities to its wide application in the automotive industry as a replacement of the thermoset-based laminates. The study presents an experimental work concerning the effect of damage due to low and high cyclic fatigue aging of two groups of specimens with two different woven fabric orientations in relation to the acting load: [0°/90°]4 and [45°/45°]4, on their low and high impact velocity properties. Subsequently, a comparison of the experimental data with the results of numerical simulations predicted by the macroscopic model proposed for the non-aged GFRE [0°/90°]4 specimens of 1.8 mm thickness are shown. A response of the materials on fatigue loading was evaluated in terms of the stiffness variation analysis. The fatigue aging program was interrupted at a given value of the stiffness drop, prior to the specimen failure. The initial stiffness was reduced by about 17 % for the GFRE [0°/90°]4, after either LCF or HCF tests. Such reduction was much more pronounced in the case of GFRE [45°/45°]4. It was equal to 48 %. The low velocity impact resistance was measured in terms of load peak, absorbed energy and penetration threshold, while the high velocity impact resistance using the ballistic limit and total energy dissipation. The non-aged specimens impacted at energy of 5 J, 10 J and 30 J were not perforated and showed a great ability to rebound the impactor. The composites subjected to low cyclic fatigue (LCF) demonstrated the greatest decrease of the initial slope of the force-displacement characteristics. It results from the significant reduction of stiffness caused by the matrix cracking and interface debonding taking place between the fibers and matrix. The maximum force reduction for tests carried out at the impact energy of 50 J for GFRE [0°/90°]4 and GFRE [45°/45°]4 was equal to 11% and 19%, respectively. Analysis of the absorbed energy during impact tests confirmed, that the aged materials containing the woven fabric oriented at the angle of 45° exhibited the weakest impact resistance. Similarly to the tests at low velocity impact, the analysis of the energy dissipation and evolution of the impact force during perforation tests confirmed, that GFRE [0°/90°]4 plates subjected to uniaxial fatigue loading had better ballistic performance and higher energy dissipation than GFRE [45°/45°]4 targets. It was also observed that specimens of GFRE [45°/45°]4 aged by cyclic loading at the stress either below or above the yield point had 20 m/s lower ballistic limits compared to those of GFRE [0°/90°]4. Therefore, one can conclude that the fibers orientation, fatigue aging, and glass fibers concentration significantly affect the elastic properties, and as a consequence, lead to the stiffness reduction and decrease of the energy absorbed and ballistic limit. The results are in agreement with the analyzes of damage phenomena. The numerical predictions of the ballistic limits, residual velocities as well as the analysis of energy absorption performed using the finite element software ABAQUS/Explicit exhibited a good agreement with the experimental data and confirmed the relevance of the approach proposed

Aptamers—Diagnostic and Therapeutic Solution in SARS-CoV-2

The SARS-CoV-2 virus is currently the most serious challenge to global public health. Its emergence has severely disrupted the functioning of health services and the economic and social situation worldwide. Therefore, new diagnostic and therapeutic tools are urgently needed to allow for the early detection of the SARS-CoV-2 virus and appropriate treatment, which is crucial for the effective control of the COVID-19 disease. The ideal solution seems to be the use of aptamers—short fragments of nucleic acids, DNA or RNA—that can bind selected proteins with high specificity and affinity. They can be used in methods that base the reading of the test result on fluorescence phenomena, chemiluminescence, and electrochemical changes. Exploiting the properties of aptamers will enable the introduction of rapid, sensitive, specific, and low-cost tests for the routine diagnosis of SARS-CoV-2. Aptamers are excellent candidates for the development of point-of-care diagnostic devices and are potential therapeutic tools for the treatment of COVID-19. They can effectively block coronavirus activity in multiple fields by binding viral proteins and acting as carriers of therapeutic substances. In this review, we present recent developments in the design of various types of aptasensors to detect and treat the SARS-CoV-2 infection

Computational Fracture Evolution Analysis of Steel-Fiber-Reinforced Concrete Using Concrete Continuous Damage and Fiber Progressive Models

The process of concrete cracking is a common problem because the first micro-cracks due to the loss of moisture may appear even before the concrete is loaded. The application of fracture mechanics allows for a better understanding of this problem. Steel-fiber-reinforced concrete (SFRC) samples with a notch were subjected to a three-point bending test, and the results for crack energy were used to analyze the concrete’s material properties. In this paper, an experimental and numerical analysis of SFRC with rapid changes in the force (F) crack mouth opening displacement (CMOD) curve (F-CMOD) is presented. In order to obtain the relevant F-CMOD diagrams, three-point bending tests were carried out with non-standard samples with a thickness equal to one-third of the width of standard samples. For analysis purposes, crimped steel fibers were adopted. A probabilistic analysis of the most important parameters describing the material in question, such as peak strength, post-cracking strength, crack mouth opening displacement (CMOD), fracture energy, and the post-cracking deformation modulus, was conducted. The tests and the analysis of their results show that the quasi-static numerical method can be applied to obtain suitable results. However, significant dynamic effects during experiments that influence the F-CMOD curves are hard to reflect well in numerical calculations

Mutacje genu IDH1 — stanowisko ekspertów

Ivosidenib is a potent — administered orally — inhibitor of IDH1-dependent pathway. Preclinical evidence of its efficacy has been confirmed by the results of prospective clinical trials in patients with IDH1-mutated acute myeloid leukemia and cholangiocarcinoma. Optimal use of ivosidinib — similarly to other targeted anti-cancer agents — depends on the efficient and precise morphological and molecular diagnostic procedures. Thea im of this publication is to present current methods ofIDH1 testing and scientific evidence on the use of ivosidenib in patients with acute myeloid leukemia as well as cholangiocarcinoma.Iwosydenib jest silnym — stosowanym doustnie — inhibitorem szlaku zależnego od IDH1. Przedkliniczne dowody wartości iwosydenibu zostały potwierdzone przez wyniki prospektywnych badań klinicznych u chorych na ostrą białaczkę szpikową i raka dróg żółciowych z mutacją w genie IDH1. Optymalne wykorzystanie iwosydenibu — podobnie do innych ukierunkowanych leków przeciwnowotworowych — zależy od sprawnej i dokładnej diagnostyki morfologicznej i molekularnej. Artykuł został przygotowany w celu przedstawienia obecnych metod oceny stanu genu IDH1 i naukowego uzasadnienia dla stosowania iwosydenibu w ostrej białaczce szpikowej oraz raku dróg żółciowych

Mutacje genu IDH1 — stanowisko ekspertów

Iwosydenib jest silnym — stosowanym doustnie — inhibitorem szlaku zależnego od IDH1. Przedkliniczne dowody wartości iwosydenibu zostały potwierdzone przez wyniki prospektywnych badań klinicznych u chorych na ostrą białaczkę szpikową i raka dróg żółciowych z mutacją w genie IDH1. Optymalne wykorzystanie iwosydenibu — podobnie do innych ukierunkowanych leków przeciwnowotworowych — zależy od sprawnej i dokładnej diagnostyki morfologicznej i molekularnej. Artykuł został przygotowany w celu przedstawienia obecnych metod oceny stanu genu IDH1 i naukowego uzasadnienia dla stosowania iwosydenibu w ostrej białaczce szpikowej oraz raku dróg żółciowych

Effect of Uniaxial Fatigue Aging and Fabric Orientation on Low Impact Velocity Response of Glass Fibers/Elium Acrylic Composite Laminates

Impact resistance is one of the most critical features of composite structures, and therefore, its examination for a new material has a fundamental importance. This paper is devoted to the characterization of the fully recyclable thermoplastic ELIUM acrylic resin reinforced by glass fabric woven, which belongs to a new category of materials requiring advanced testing before their application in responsible elements of engineering structures. Its high strength, low weight as well as low production cost give excellent opportunities for its wide application in the automotive industry as a replacement of the thermoset-based laminates. The study presents an experimental work concerning the effect of damage due to low and high cyclic fatigue aging of two groups of specimens, first with the woven fabric orientations of [0°/90°]4 and secondly with [45°/45°]4, on the low impact velocity properties. The impact resistance was measured in terms of load peak, absorbed energy, penetration threshold and damage analysis. The low velocity impact results indicate that the uniaxial cyclic loading (fatigue aging) of the material leads to the reduction of impact resistance, especially at the high impact energy levels. Scanning Electron Microscopy (SEM) and Computed Tomography (CT) scan observations reveal that the damage area grows with the increase of both strain amplitude and impact energy