MICROSTRUTTURA DI UNA LEGA EN-AW 6082 DOPO LAMINAZIONE ASIMMETRICA

Nel presente lavoro è stata valutata la possibilità di utilizzare la laminazione asimmetrica per l’affinamento del grano cristallino in una lega EN-AW 6082. Sono state svolte diverse laminazioni per valutare l’influenza dal rapporto di asimmetria, definito come il rapporto tra la velocità tangenziale del cilindro superiore e di quello inferiore, sulla diminuzione della dimensione media del grano. Il materiale laminato è stato sottoposto a prove di microdurezza per valutare l’evoluzione delle proprietà meccaniche, a osservazioni in microscopia ottica ed elettronica in trasmissione (TEM) per monitorare i cambiamenti microstrutturali. A differenza delle altre tecniche di deformazione plastica severa, la laminazione asimmetrica sarebbe pronta per lo sfruttamento industriale e in questa ottica si inquadra questo lavoro di indagine

A comparison between asymmetric rolling and accumulative roll bonding as means to refine the grain structure of an Al-Mg-Si alloy

The possibility of refining the grain structureof a commercial Al-Mg-Si alloy wasevaluated using asymmetric rolling (ASR) andaccumulative roll bonding (ARB) in the severeplastic deformation (SPD) regime. Bars ofannealed alloy having a thickness of 10 mmwere asymmetrically rolled down to athickness of 0.23 mm with a laboratoryrolling mill featuring the possibility ofindependently modifying the rotational speedof its two rolls. The effect of the rollingtemperature was investigated by tests in therange 150-250°C. A parallel campaign wasalso conducted to investigate the effects ofwarm accumulative roll bonding of the samealloy and in the same temperature range.These tests were carried out on annealedsamples of 1 mm thickness. The experimentalcharacterization (both mechanical andm i c ro s t ructural) demonstrated thatasymmetric rolling and accumulative rollbonding can readily promote the achievementof ultrafine grained structures in Al-Mg-Sialloys

An osteosarcoma model by 3D printed polyurethane scaffold and in vitro generated bone extracellular matrix

Osteosarcoma is a primary bone tumor characterized by a dismal prognosis, especially in the case of recurrent disease or metastases. Therefore, tools to understand in-depth osteosarcoma progression and ultimately develop new therapeutics are urgently required. 3D in vitro models can provide an optimal option, as they are highly reproducible, yet sufficiently complex, thus reliable alternatives to 2D in vitro and in vivo models. Here, we describe 3D in vitro osteosarcoma models prepared by printing polyurethane (PU) by fused deposition modeling, further enriched with human mesenchymal stromal cell (hMSC)-secreted biomolecules. We printed scaffolds with different morphologies by changing their design (i.e., the distance between printed filaments and printed patterns) to obtain different pore geometry, size, and distribution. The printed PU scaffolds were stable during in vitro cultures, showed adequate porosity (55–67%) and tunable mechanical properties (Young’s modulus ranging in 0.5–4.0 MPa), and resulted in cytocompatible. We developed the in vitro model by seeding SAOS-2 cells on the optimal PU scaffold (i.e., 0.7 mm inter-filament distance, 60° pattern), by testing different pre-conditioning factors: none, undifferentiated hMSC-secreted, and osteo-differentiated hMSC-secreted extracellular matrix (ECM), which were obtained by cell lysis before SAOS-2 seeding. Scaffolds pre-cultured with osteo-differentiated hMSCs, subsequently lysed, and seeded with SAOS-2 cells showed optimal colonization, thus disclosing a suitable biomimetic microenvironment for osteosarcoma cells, which can be useful both in tumor biology study and, possibly, treatment

Trattamento di nitrurazione ionica di una lega di titanio commercialmente puro e di una lega Ti-6Al-4V

Nel presente lavoro sono state analizzate due leghe di titanio sottoposte a trattamenti di nitrurazione ionicaal fine di indagare l’influenza sia della composizione del materiale trattato sia dei parametri di processoutilizzati. Le indagini sperimentali sono state svolte attraverso analisi della microstruttura, misuredi composizione nello spessore mediante spettroscopia a emissione ottica e profili di microdurezza.Tra i risultati ottenuti si è evidenziato come i maggiori valori nei profili di microdurezza e di composizionenello spessore nitrurato si riscontrino nei campioni sottoposti a trattamenti prolungati o a cicli di diffusionealternati ai periodi di esposizione in atmosfera attiva. Si è dimostrato come l’arricchimento di azoto avvengain misura maggiore nella lega di Ti-6Al-4V rispetto al titanio commercialmente puro a parità di condizionidi trattamento. Infine nella lega Ti-6Al-4V durante il trattamento di nitrurazione si è misurato un accumulodi alluminio e di vanadio immediatamente a valle dello strato dei composti che contribuisce ad incrementarela durezza degli strati sub- superficiali

Tuning the 3D microenvironment of reprogrammed tubule cells enhances biomimetic modeling of polycystic kidney disease

Renal tubular cells frequently lose differentiation markers and physiological properties when propagated in conventional cell culture conditions. Embedding cells in 3D microenvironments or controlling their 3D assembly by bioprinting can enhance their physiological properties, which is beneficial for modeling diseases in vitro. A potential cellular source for modeling renal tubular physiology and kidney diseases in vitro are directly reprogrammed induced renal tubular epithelial cells (iRECs). iRECs were cultured in various biomaterials and as bioprinted tubular structures. They showed high compatibility with the embedding substrates and dispensing methods. The morphology of multicellular aggregates was substantially influenced by the 3D microenvironment. Transcriptomic analyses revealed signatures of differentially expressed genes specific to each of the selected biomaterials. Using a new cellular model for autosomal-dominant polycystic kidney disease, Pkd1$^{-/-}$ iRECs showed disrupted morphology in bioprinted tubules and a marked upregulation of the Aldehyde dehydrogenase 1a1 (Aldh1a1). In conclusion, 3D microenvironments strongly influence the morphology and expression profiles of iRECs, help to unmask disease phenotypes, and can be adapted to experimental demands. Combining a direct reprogramming approach with appropriate biomaterials will facilitate construction of biomimetic kidney tubules and disease models at the microscale

Predictors of CD34+ cell mobilization and collection in adult men with germ cell tumors: implications for the salvage treatment strategy

BACKGROUND: High-dose chemotherapy with tandem or triple carboplatin and etoposide course is currently the first curative choice for relapsing GCT. The collection of an adequate amount of hematopoietic (CD34(+)) stem cells is a priority. PATIENTS AND METHODS: We analyzed data of patients who underwent HDCT at 2 referral institutions. Chemotherapy followed by myeloid growth factors was applied in all cases. Uni- and multivariable models were used to evaluate the association between 2 prespecified variables and mobilization parameters. Analyses included only the first mobilizing course of chemotherapy and mobilization failures. RESULTS: A total of 116 consecutive patients underwent a mobilization attempt from December 1995 to November 2012. Mobilizing regimens included cyclophosphamide (CTX) 7 gr/m(2) (n = 39), cisplatin, etoposide, and ifosfamide (PEI) (n = 42), paclitaxel, cisplatin, and gemcitabine (TPG) (n = 11), and mixed regimens (n = 24). Thirty-seven percent were treated in first-line, 50% (n = 58) in second-line, 9.5% (n = 11) and 3.4% (n = 4) in third- and fourth-line settings, respectively. Six patients did not undergo HDCT because they were poor mobilizers, 2 in first- and second-line (1.9%), and 4 beyond the second-line (26.7%). In the multivariable model, third-line or later setting was associated with a lower CD34(+) cell peak/μL (P = .028) and a lower total CD34(+)/kg collected (P = .008). The latter was also influenced by the type of mobilizing regimen (P < .001). CONCLUSION: A decline in significant mobilization parameters was found, primarily depending on the pretreatment load. Results lend support to the role of CD34(+) cell mobilization in the therapeutic algorithm of relapsing GCT, for whom multiple HDCT courses are still an option, and potentially a cure

Tuning the 3D microenvironment of reprogrammed tubule cells enhances biomimetic modeling of polycystic kidney disease

Renal tubular cells frequently lose differentiation markers and physiological properties when propagated in conventional cell culture conditions. Embedding cells in 3D microenvironments or controlling their 3D assembly by bioprinting can enhance their physiological properties, which is beneficial for modeling diseases in vitro. A potential cellular source for modeling renal tubular physiology and kidney diseases in vitro are directly reprogrammed induced renal tubular epithelial cells (iRECs). iRECs were cultured in various biomaterials and as bioprinted tubular structures. They showed high compatibility with the embedding substrates and dispensing methods. The morphology of multicellular aggregates was substantially influenced by the 3D microenvironment. Transcriptomic analyses revealed signatures of differentially expressed genes specific to each of the selected biomaterials. Using a new cellular model for autosomal-dominant polycystic kidney disease, Pkd1(−/−) iRECs showed disrupted morphology in bioprinted tubules and a marked upregulation of the Aldehyde dehydrogenase 1a1 (Aldh1a1). In conclusion, 3D microenvironments strongly influence the morphology and expression profiles of iRECs, help to unmask disease phenotypes, and can be adapted to experimental demands. Combining a direct reprogramming approach with appropriate biomaterials will facilitate construction of biomimetic kidney tubules and disease models at the microscale