1,721,003 research outputs found
Pulizia in linea del filo metallico su impianti di trafilatura ad alta velocità: Innovazione, ecologia e performance
No full textNei processi di trafilatura il filo metallico subisce una sequenza di passaggi forzati attraverso matrici (filiere), di diametro decrescente,
che ne riducono progressivamente la sezione fino al valore desiderato. Per assicurare il passaggio attraverso le filiere, riducendo
quanto più possibile l’attrito, è necessaria una lubrificazione, ottenuta tramite l’utilizzo di diverse sostanze chimiche: si passa da
emulsioni acqua/olio per lubrificazione liquida, a stearati di sodio e/o calcio o polimeri per lubrificazione solida. Tali lubrificanti
devono formare un film sottile, omogeneo e ben adeso al filo, ma devono poter essere rimossi al termine dei processi di riduzione
di sezione se si desidera ottenere un filo superficialmente pulito e pronto per eventuali successivi trattamenti galvanici, termici o
di rivestimento superficiale di vario genere. In questo articolo verrà analizzata una tecnica innovativa per la pulizia del filo, in linea
con l’impianto di trafilatura, applicabile sia a monte del processo (pulizia/decapaggio della vergella) sia a valle (pulizia finale prebobinatura).
La tecnica in esame, basata su un processo elettrochimico, può essere integrata su linee già esistenti e va a sostituire le vasche
chimiche o ad ultrasuoni di pulizia post-trafilatura, facendo uso di elettroliti a minor impatto ambientale rispetto ai tradizionali
liquidi per sgrassaggio acido e alcalino
Microwave-assisted preparation of multi principal element alloys by powder metallurgy approach
Full text linkAccording to literature, the synthetic route to produce High entropy alloys (HEAs) should guarantee short alloying time, efficient cooling and capability to operate in controlled atmosphere. Such conditions can be achieved using high frequency electromagnetic fields, like microwave heating. In this work FeCoNiCrAl and FeCoNiCuAl, both equiatomic and reinforced by the 10% wt. of SiC were prepared by microwave assisted techniques. Results show that direct microwave heating of the powder precursors occurs, until the ignition conditions are reached. The temperature and duration of the microwave-assisted process result much lower than other conventional powder metallurgy routes, but at the cost of a higher residual porosity. Sample characterization confirmed that the powder metallurgy approach is suitable to retain the shape of the load imparted during forming by uniaxial pressing. The homogeneity of the samples resulted in being good in all cases, without the dendritic segregation typically occurring by liquid phase processing. © 2017 European Powder Metallurgy Association (EPMA
A micro/nanoscale surface mechanical study on morpho-functional changes in multilineage-differentiated human mesenchymal stem cells.
No full textIn recent years MSCs have become a very attractive tool in tissue engineering and regenerative medicine because of their ability to be committed along several lineages through chemical or physical stimuli. Nevertheless their therapeutic potential and plasticity are not yet totally understood. This report describes the use of AFM together with conventional microscopies to obtain mechanical information on cell surfaces and deposited extra cellular matrix molecules, after inducing the differentiation of human MSCs towards three typical mesoderm phenotypes. The aim is to correlate morphological, functional, and mechanical aspects of human MSCs to obtain a deeper understanding of their great potential
EFFECTS OF REPEATED EXPOSURE TO HIGH-VOLTAGE ELECTRIC-DISCHARGES AND LOW-FREQUENCY ELECTROMAGNETIC-FIELDS ON CULTURED MOUSE P3X63AG8 PLASMACYTOMA CELLS
No full textMicrowave energy application to combustion synthesis: A comprehensive review of recent advancements and most promising perspectives
No full textMicrowave heating fundamentally differs from other heating techniques as the consequence of its unique characteristic of being based on the electromagnetic energy transfer from the microwaves source to the interacting material, which according to its electric, dielectric, and magnetic properties can convert the absorbed energy into heat. This peculiar heating mechanism is at the basis of plenty of unquestionable advantages that were reported during the last three decades in most of the different branches of chemistry as well as materials science, thus including also combustion synthesis. After a brief overview of the microwave heating fundamentals as well as of the different components constituting the scientific microwave applicators, all the most significant and recent advancements in the use of microwaves as energy source in both solid-state as well as solution combustion synthesis processes will be comprehensively reviewed, highlighting the unique opportunities arising from the coupling of these two energy efficient techniques. Moreover the possible employment of less conventional frequencies as well as the use of new-generation solid state generators will be critically discussed also in the framework of scaling-up and microwave reactor design considerations
A Micro-nanoscale surface mechanical study on morpho-functional changes in multilineage differentiateted human mesenchymal stem cells
No full textIn recent years MSCs have become a very attractive tool in tissue engineering and regenerative medicine because of their ability to be committed along several lineages through chemical or physical stimuli. Nevertheless their therapeutic potential and plasticity are not yet totally understood. This report describes the use of AFM together with conventional microscopies to obtain mechanical information on cell surfaces and deposited extra cellular matrix molecules, after inducing the differentiation of human MSCs towards three typical mesoderm phenotypes. The aim is to correlate morphological, functional, and mechanical aspects of human MSCs to obtain a deeper understanding of their great potential
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Carboxy-terminal fragment of osteogenic growth peptide in vitro increases bone marrow cell density in idiopathic myelofibrosis
No full textIdiopathic myelofibrosis (IMF) is a clonal stem cell disorder characterized by reactive fibrosis of bone marrow sustained by a complex cytokine network. At present, no efficacious therapy for this disease exists. Synthetic carboxy-terminal pentapeptide of osteogenic growth factor (sOGP10-14) can increase bone marrow cellularity and the number of haematopoietic colonies; this study evaluated the activity of sOGP10-14 in IMF. Fragments of bone marrow biopsies from patients affected by IMF were cultured with or without the addition of sOGP10-14. Cellular density was evaluated by image analysis, and transforming growth factor-beta1 (TGF-beta1) concentration was immunologically assayed in the supernatant of cultured bone marrow biopsies. The proliferation rate of the megakaryoblastic M07-e cell line, cultured in the presence of either granulocyte-macrophage colony stimulating factor or thrombopoietin (TPO), and with or without sOGP10-14, was evaluated. Megakaryocyte colony forming unit (CFU-Mk) assay was performed on bone marrow samples of IMF patients with or without sOGP10-14. After 14 d, bone marrow cellularity was significantly increased in samples cultured with the pentapeptide. Moreover, sOGP10-14 induced a significant increase of TGF-beta in culture supernatants. TPO-primed proliferation of M07-e was reduced by sOGP10-14, and the pentapeptide significantly reduced CFU-Mk on IMF bone-marrow-derived cells. sOGP10-14 increased ex vivo bone marrow cellularity in IMF. This action could be related to the megakaryocyte inhibition induced by the interference of this pentapeptide with growth factor activities. These findings suggest that a deficiency of osteoblast-related factors may play a role in bone marrow failure in IMF
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