Study of the Microstructure and Cracking Mechanisms of Hastelloy X Produced by Laser Powder Bed Fusion

Hastelloy X (HX) is a Ni-based superalloy which suffers from high crack susceptibility during the laser powder bed fusion (LPBF) process. In this work, the microstructure of as-built HX samples was rigorously investigated to understand the main mechanisms leading to crack formation. The microstructural features of as-built HX samples consisted of very fine dendrite architectures with dimensions typically less than 1 µm, coupled with the formation of sub-micrometric carbides, the largest ones were mainly distributed along the interdendritic regions and grain boundaries. From the microstructural analyses, it appeared that the formation of intergranular carbides provided weaker zones, which combined with high thermal residual stresses resulted in hot cracks formation along the grain boundaries. The carbides were extracted from the austenitic matrix and characterized by combining different techniques, showing the formation of various types of Mo-rich carbides, classified as M6C, M12C and MnCm type. The first two types of carbides are typically found in HX alloy, whereas the last one is a metastable carbide probably generated by the very high cooling rates of the process

Characterization of an Additive Manufactured TiAl Alloy-Steel Joint Produced by Electron Beam Welding

In this work, the characterization of the assembly of a steel shaft into a γ-TiAl part for turbocharger application, obtained using Electron Beam Welding (EBW) technology with a Ni-based filler, was carried out. The Ti-48Al-2Nb-0.7Cr-0.3Si (at %) alloy part was produced by Electron Beam Melting (EBM). This additive manufacturing technology allows the production of a lightweight part with complex shapes. The replacement of Nickel-based superalloys with TiAl alloys in turbocharger automotive applications will lead to an improvement of the engine performance and a substantial reduction in fuel consumption and emission. The welding process allows a promising joint to be obtained, not affecting the TiAl microstructure. Nevertheless, it causes the formation of diffusive layers between the Ni-based filler and both steel and TiAl, with the latter side being characterized by a very complex microstructure, which was fully characterized in this paper by means of Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, and nanoindentation. The diffusive interface has a thickness of about 6 µm, and it is composed of several layers. Specifically, from the TiAl alloy side, we find a layer of Ti₃Al followed by Al₃NiTi₂ and AlNi₂Ti. Subsequently Ni becomes more predominant, with a first layer characterized by abundant carbide/boride precipitation, and a second layer characterized by Si-enrichment. Then, the chemical composition of the Ni-based filler is gradually reached

Ultrastructural analysis reveals differences in the secretory activity among four regions of amniotic membrane

Human Amniotic Epithelial Cells (hAEC) from term placenta are a promising source of stem cells for regenerative medicine. In a previous study we observed histological heterogeneity, together with different expression of pluripotency markers and content in lipid granules among four regions of amniotic membrane (AM). To better investigate cell heterogeneity among different cell populations, we performed an ultrastructural study with Transmission Electron Microscopy. Term placentae from healthy women were collected after caesarean section and AM samples were freshly isolated from four regions: R1 (close to the umbilical cord); R2 (intermediate); R3 (peripheral to the placental disc); R4 (reflected amnion). Ultrastructural analysis revealed an epithelium of variable thickness, cellular shape, amount and type of vesicles in the four regions. The epithelium showed columnar hAEC with increased height in R1 and R3 and a multi-layered organization in R3, whereas it was a monolayer in the other regions. The highest amount of granules and vesicles was observed in R3, although R4 showed granules with a different density. Furthermore, in R1, R3 and R4 we noticed several vesicles of 100-150 nm in diameter, probably exosome-like structures, suggesting a consistent secretory activity. All along its length the epithelium was rich in microvilli both on the side facing the amniotic fluid and in lateral contacts (narrow desmosomal junctions) between cells. This in situ investigation shows for the first time differences in secretory activity and granules appearance along the AM as a proof of its heterogeneity. This could be relevant in clinical applications as the choice of the area could improve the effectiveness of AM/hAEC transplantation

General consensus on multimodal functions and validation analysis of perinatal derivatives for regenerative medicine applications.

Perinatal tissues, such as placenta and umbilical cord contain a variety of somatic stem cell types, spanning from the largely used hematopoietic stem and progenitor cells to the most recently described broadly multipotent epithelial and stromal cells. As perinatal derivatives (PnD), several of these cell types and related products provide an interesting regenerative potential for a variety of diseases. Within COST SPRINT Action, we continue our review series, revising and summarizing the modalities of action and proposed medical approaches using PnD products: cells, secretome, extracellular vesicles, and decellularized tissues. Focusing on the brain, bone, skeletal muscle, heart, intestinal, liver, and lung pathologies, we discuss the importance of potency testing in validating PnD therapeutics, and critically evaluate the concept of PnD application in the field of tissue regeneration. Hereby we aim to shed light on the actual therapeutic properties of PnD, with an open eye for future clinical application. This review is part of a quadrinomial series on functional/potency assays for validation of PnD, spanning biological functions, such as immunomodulation, anti-microbial/anti-cancer, anti-inflammation, wound healing, angiogenesis, and regeneration

Visita all'Osservatorio della Biodiversità marina e terrestre della Regione Sicilia - ORBS

Con il taglio inaugurale del nastro il 16 dicembre 2015, prende vita la struttura museale permanente dell'Osservatorio della Biodiversità marina e terrestre della Regione Sicilia che porta lo stesso nome del Progetto di Ricerca "ORBS – Sistema di comunicazione, informazione e diffusione dell'Osservatorio Regionale della Sicilia", intitolata il 21 dicembre 2018 al Dott. Sandro Fiorelli. Ad oggi, la struttura, è operativa presso la Sede Secondaria dell'Istituto per lo studio degli impatti Antropici e Sostenibilità in ambiente marino del Consiglio Nazionale delle Ricerche (IAS – CNR) di Capo Granitola. Il progetto ORBS, finanziato da Regione Siciliana - Assessorato alla Cooperazione, Commercio, Artigianato e Pesca - Dipartimento Pesca, con periodo di attività 2013 - 2015, si è concluso proprio con la realizzazione della struttura museale; l'Osservatorio è stato istituito dall'Assessorato del Territorio e dell'Ambiente della Regione Siciliana nell'ambito di un accordo quadro con ARPA, ISPRA e CNR. Grazie al progetto ORBS, docenti e allievi dell'Accademia di Belle Arti di Palermo e il personale CNR – IAS (ex IAMC) S. S. di Capo Granitola, hanno collaborato sinergicamente permettendo di realizzare delle azioni didattiche e creative di valore scientifico espresse con straordinaria forza e bellezza. Ricercatori e professori si sono confrontati al fine di combinare le proprie competenze riuscendo nel progetto ambizioso di coinvolgere e fondere i diversi ambiti scientifici sensibilizzando gli artisti ai temi della Biodiversità. Le opere prodotte, corredate da schede scientifiche, hanno oltre al valore artistico un aggiunto valore didattico. L'apertura della sezione espositiva dedicata alla diffusione e alla comunicazione della biodiversità rappresenta da un lato l'importante tappa conclusiva del progetto, dall'altro l'inizio di un percorso mirato alla diffusione della biodiversità verso il mondo giovanile, le scuole e per tutto il territorio. Questa strepitosa collaborazione "CNR – Accademia di Belle Arti di Palermo" conferma l'importanza e l'opportunità di unire arte e scienza per esaltare la percezione della ricerca scientifica da parte della comunità. La divulgazione della scienza è un'attività complessa e sicuramente necessita di competenze e attitudini multidisciplinari oltreché di motivazione ed entusiasmo. La comunicazione delle tematiche scientifiche, di per sé ardua nella traduzione al grande pubblico, grazie alla forza esplicativa dell'arte, diviene opportunità di riflessione, osservazione, confronto per le comunità di visitatori. Il coordinamento delle visite delle scuole di ogni ordine e grado, Enti Pubblici, Comunità Scientifica, Cariche Istituzionali, Delegazioni di Politici Italiani e Stranieri, Associazioni Culturali, Associazioni No-Profit di Volontariato, Associazioni di Promozione Sociale, Organizzazioni di Volontariato, Onlus, pubblico in generale, presso ORBS, è affidato al qualificato personale (tecnici, tecnologi e ricercatori) dell'IAS – CNR S. S. di Capo Granitola, che gestisce in prima persona i visitatori nel percorso didattico e promuove il valore della divulgazione scientifica perseguendo la terza missione degli Enti di Ricerca, attraverso l'applicazione diretta, la valorizzazione e l'impiego della conoscenza

Transposon-dependent induction of Vincent van Gogh's sunflowers: Exceptions revealed.

The radiate sunflower inflorescence is composed by zygomorphic ray flowers and actinomorphic disk flowers. Studies performed on mutants identify HaCYC2c, a CYCLOIDEA (CYC)-like gene, as one of the key players controlling flower symmetry in sunflower. turf and tub mutants are characterized by a shift from zygomorphic to actinomorphic ray flowers, caused by insertion of transposable elements (TEs) in HaCYC2c gene. In dbl or Chry mutants, an insertion upstream the coding region of HaCYC2c causes the ectopic expression of the gene and the shift from actinomorphic to zygomorphic disk flowers. We focused on Chry2 mutant: a 1034 bp insertion placed 558 bp before the start codon of HaCYC2c was identified. The insertion is a truncated version of a CACTA TE. Unexpectedly, phenotypic and genetic co-segregation analysis in F2 and F3 progenies derived from the crosses Chry2 × turf and turf × Chry2 demonstrated that CACTA insertion is not always sufficient to alter the expression of HaCYC2c gene and generate Chry2 phenotype. F3 plants homozygous for the CACTA insertion displayed either HaCYC2c transcription pattern identical to wild-type plants or a normal heterogamous inflorescence. Stated these results, we conclude that a much more complex regulatory system stays behind the Chry2 phenotype

Cancer-Homing CAR-T Cells and Endogenous Immune Population Dynamics

Chimeric antigen receptor (CAR) therapy is based on patient blood-derived T cells and natural killer cells, which are engineered in vitro to recognize a target antigen in cancer cells. Most CAR-T recognize target antigens through immunoglobulin antigen-binding regions. Hence, CAR-T cells do not require the major histocompatibility complex presentation of a target peptide. CAR-T therapy has been tremendously successful in the treatment of leukemias. On the other hand, the clinical efficacy of CAR-T cells is rarely detected against solid tumors. CAR-T-cell therapy of cancer faces many hurdles, starting from the administration of engineered cells, wherein CAR-T cells must encounter the correct chemotactic signals to traffic to the tumor in sufficient numbers. Additional obstacles arise from the hostile environment that cancers provide to CAR-T cells. Intense efforts have gone into tackling these pitfalls. However, we argue that some CAR-engineering strategies may risk missing the bigger picture, i.e., that a successful CAR-T-cell therapy must efficiently intertwine with the complex and heterogeneous responses that the body has already mounted against the tumor. Recent findings lend support to this model

Overexpression of L-galactono-1,4-lactone dehydrogenase (L-GalLDH) gene correlates with increased ascorbate concentration and reduced browning in leaves of Lactuca sativa L. after cutting

Ascorbic acid (AA) is one of the most powerful natural antioxidant able to prevent enzymatic browning after exogenous treatment of minimally-processed products. The specific mechanism by which AA prevents enzymatic browning remains still debated and a direct effect of endogenous AA stimulation and browning has never been studied. The manipulation of AA pathway is a promising approach to study the biochemicalmechanismbywhichAAacts as an antibrowning agent. In this work, cDNA of L-galactono-1,4-lactone dehydrogenase (L-GalLDH), one of the key gene of the Smirnoff–Wheeler’s branch of AA biosynthetic pathway, was isolated and overexpressed in lettuce (Lactuca sativa L. cv ‘Iceberg’), a species highly prone to browning. The hypothesis that the overexpression of L-GalLDH translates to AA accumulation and reduces the browning phenomena in lettuce leaves after cutting was tested. Our results indicate that transgenic lettuce plants, showing about 19-fold overexpression of L-GalLDHas compared towild type, had about?30 % of AA concentration in mature leaves. Transgenic plants exhibited reduced browning over the leaves, even 10 day after cutting, as demonstrated by higher values of luminosity (L*) and higher values of greenness (a*) compared to control plants. Overall, these findings provide a first evidence of the role of endogenous AA as browning-preventing agent. The obtainment of T2 transgenic lettuce plants is a promising first step to further determine the specificmechanismbywhichAA acts as an anti-browning preservative

The Capacity Of Cold Spray Additive Manufacturing Technology For Metallic Part Repairing

Cold spray as a coating deposition technology based on high-speed impact dynamics has thrived with considerable capabilities. In this process, sprayed particles are accelerated to a high velocity by a high-speed gas flow that is generated through a convergent-divergent de Laval type nozzle. A deposition is formed through the intensive plastic deformation of particles impacting on a substrate at a temperature below the melting point of the sprayed material. One of its key applications is the recovery of costly aircraft parts during the overhaul and repair. This process is used for providing surface modification or wear resistance to a substrate, depositing thermal barrier coatings and many other applications without the undesirable effects of process temperatures or metallurgical incompatibilities. This article presents the findings of a comprehensive state-of-the-art literature review of the scientific and technological progress of this technology in the field of repair using the concept of additive manufacturing