Caratterizzazione ad usura di rivestimenti PVD con e senza laser texturing

Il processo di laser texturing (LST) è una delle tecniche più promettenti nel campo delle microlavorazioni superficialiin quanto consente di ottenere un eccellente controllo della forma e delle dimensioni delle microcavitàprodotte ed è estremamente veloce e senza ricadute dannose per l’ambiente. Recentemente si è assistito allosviluppo di diversi lavori nei quali il laser è stato impiegato per migliorare il comportamento tribologico di componentimeccanici in materiale metallico. Le microcavità, realizzate per ablazione dal fascio laser sulla superficiedi interesse, infatti hanno diversi aspetti positivi da questo punto di vista perché generano un sistema diffusodi microspinte idrodinamiche sulla superficie e agiscono come riserve di lubrificante da una parte e come trappoleper i detriti di usura dall’altra, ritardando così, l’innesco di meccanismi di usura da terzo corpo. Nel presentelavoro si presentano i risultati di una sperimentazione volta a valutare l’effetto dell’introduzione di unalavorazione superficiale di texturing laser sulla superficie di riporti PVD in TiN. Per il texturing è stata utilizzatauna sorgente laser in fibra innovativa ad alta efficienza che ha consentito, una volta ottimizzati i parametridi processo, di ottenere dimensioni controllate delle microcavità, una buona geometria delle stesse e di evitarela presenza di residui di lavorazione anche sui coating ceramici oggetto dello studio. I test di usura in condizionidi strisciamento lubrificato con alto carico applicato e bassa velocità relativa , sono stati condotti sul rivestimentoTiN microlavorato e per confronto sul tal quale e su un rivestimento autolubrificante commerciale,il WC/C. I risultati ottenuti mostrano un marcato incremento delle prestazioni a usura per il rivestimento lasercon texturing (fino al 50% di riduzione del volume di usura) e l’assenza di significativi danneggiamenti del rivestimentoin presenza delle microcavità e delle sollecitazioni di usura applicate. Nel breve futuro si eseguiràpertanto un approfondimento ulteriore per valutare anche l’economia di scala del ciclo di lavorazione

Corrosion behavior and surface properties of PVD coatings for mold technology applications

Chrome plating is still one of the best solutions to coat martensitic steel used in the molding of plastics and rubbers. However, current stringent regulations on environmental impact call for more sustainable processes. In the present work, some physical vapor deposition (PVD) nitride coatings were produced on X155CrMoV12 steel and characterized in terms of both corrosion behavior and surface properties. Results indicated that titanium-based PVD coatings could be a valuable alternative to chromium-based coatings as they exhibited a good compromise between corrosion and surface properties. AlTiN and TiN PVD coatings exhibited adequate hardness for plastic mold applications, with AlTiN reaching hardness as high as 2000 HV. Moreover, the critical loads and adhesion properties were found to be definitely better than those of chromium-based coatings. From a corrosion point of view, the presence of multilayers in AlTiN did not seem to be beneficial as the breakdown potential for TiN (single layer) was ca. 1.1 V vs. saturated calomel electrode (SCE) compared to 0.85 V vs. SCE for AlTiN in aggressive media (NaCl)

DNA damage and transcriptional regulation in iPSC-derived neurons from Ataxia Telangiectasia patients

Abstract Ataxia Telangiectasia (A-T) is neurodegenerative syndrome caused by inherited mutations inactivating the ATM kinase, a master regulator of the DNA damage response (DDR). What makes neurons vulnerable to ATM loss remains unclear. In this study we assessed on human iPSC-derived neurons whether the abnormal accumulation of DNA-Topoisomerase 1 adducts (Top1ccs) found in A-T impairs transcription elongation, thus favoring neurodegeneration. Furthermore, whether neuronal activity-induced immediate early genes (IEGs), a process involving the formation of DNA breaks, is affected by ATM deficiency. We found that Top1cc trapping by CPT induces an ATM-dependent DDR as well as an ATM-independent induction of IEGs and repression especially of long genes. As revealed by nascent RNA sequencing, transcriptional elongation and recovery were found to proceed with the same rate, irrespective of gene length and ATM status. Neuronal activity induced by glutamate receptors stimulation, or membrane depolarization with KCl, triggered a DDR and expression of IEGs, the latter independent of ATM. In unperturbed A-T neurons a set of genes (FN1, DCN, RASGRF1, FZD1, EOMES, SHH, NR2E1) implicated in the development, maintenance and physiology of central nervous system was specifically downregulated, underscoring their potential involvement in the neurodegenerative process in A-T patients

Clinical presentation of celiac disease and diagnosis accuracy in a single-center european pediatric cohort over 10 years

(1) Background: Changes in the clinical presentation of celiac disease (CD) in children have been reported. The guidelines of the European Society of Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) allow esophagogastroduodenoscopy (EGD) with biopsies to be avoided under specific circumstances. We aimed to assess the clinical picture of pediatric CD patients at diagnosis and to validate ESPGHAN non-biopsy criteria. (2) Methods: Patients with suspected CD or undergoing screening from 2004 to 2014 at the University Hospital in Modena, Italy were enrolled. The accuracy of ESPGHAN non-biopsy criteria and modified versions were assessed. (3) Results: In total, 410 patients were enrolled, of whom 403 were considered for analysis. Of the patients considered, 45 were asymptomatic and diagnosed with CD (11.2%) while 358 patients (88.2%) were symptomatic, of whom 295 were diagnosed with CD. Among symptomatic CD patients, 57 (19.3%) had gastrointestinal symptoms, 98 (33%) had atypical symptoms and 140 (47.4%) had both. No difference was found for the presence of gastrointestinal symptoms at different ages. The non-biopsy ESPGHAN criteria yielded an accuracy of 59.4% with a positive predictive value (PPV) of 100%; 173 out of 308 EGD (56.2%) could have been avoided. The modified 7× and 5× upper limit of normal cut-offs for IgA anti tissue-transglutaminase reached 60.7% and 64.3% of EGD avoided, respectively. (4) Conclusions: Over 10 years, late age at diagnosis and increased rates of atypical CD presentation were found. ESPGHAN non-biopsy criteria are accurate for CD diagnosis and allow half of unneeded EGD to be avoided. Modified versions allowed sparing a greater number of EGD

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

SPARC regulation of PMN clearance protects from pristane-induced lupus and rheumatoid arthritis

The secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein with unexpected immunosuppressive function in myeloid cells. We investigated the role of SPARC in autoimmunity using the pristane-induced model of lupus that, in mice, mimics human systemic lupus erythematosus (SLE). Sparc−/− mice developed earlier and more severe renal disease, multi-organ parenchymal damage, and arthritis than the wild-type counterpart. Sparc+/- heterozygous mice showed an intermediate phenotype suggesting Sparc gene dosage in autoimmune-related events. Mechanistically, reduced Sparc expression in neutrophils blocks their clearance by macrophages, through defective delivery of don't-eat-me signals. Dying Sparc−/− neutrophils that escape macrophage scavenging become source of autoantigens for dendritic cell presentation and are a direct stimulation for γδT cells. Gene profile analysis of knee synovial biopsies from SLE-associated arthritis showed an inverse correlation between SPARC and key autoimmune genes. These results point to SPARC down-regulation as a leading event characterizing SLE and rheumatoid arthritis pathogenesis

Synthesis and biological evaluation of dual action cyclo-RGD/SMAC mimetic conjugates targeting αvβ3/αvβ5 integrins and IAP proteins

The rational design, synthesis and in vitro biological evaluation of dual action conjugates 11-13, containing a tumour targeting, integrin a(v)beta(3)/a(v)beta(5) ligand portion and a pro-apoptotic SMAC mimetic portion (cyclo-RGD/SMAC mimetic conjugates) are reported. The binding strength of the two separate units is generally maintained by these dual action conjugates. In particular, the connection between the separate units (anchor points on each unit; nature, length and stability of the linker) influences the activity of each portion against its molecular targets (integrins a(v)beta(3)/a(v)beta(5) for cyclo-RGD, IAP proteins for SMAC mimetics). Each conjugate portion tolerates different substitutions while preserving the binding affinity for each target

Oncogenic KRAS sensitizes premalignant, but not malignant cells, to Noxa-dependent apoptosis through the activation of the MEK/ERK pathway

KRAS is mutated in about 20-25% of all human cancers and especially in pancreatic, lung and colorectal tumors. Oncogenic KRAS stimulates several pro-survival pathways, but it also triggers the trans-activation of pro-apoptotic genes. In our work, we show that G13D mutations of KRAS activate the MAPK pathway, and ERK2, but not ERK1, up-regulates Noxa basal levels. Accordingly, premalignant epithelial cells are sensitized to various cytotoxic compounds in a Noxa-dependent manner. In contrast to these findings, colorectal cancer cell sensitivity to treatment is independent of KRAS status and Noxa levels are not up-regulated in the presence of mutated KRAS despite the fact that ERK2 still promotes Noxa expression. We therefore speculated that other survival pathways are counteracting the pro-apoptotic effect of mutated KRAS and found that the inhibition of AKT restores sensitivity to treatment, especially in presence of oncogenic KRAS. In conclusion, our work suggests that the pharmacological inhibition of the pathways triggered by mutated KRAS could also switch off its oncogene-activated pro-apoptotic stimulation. On the contrary, the combination of chemotherapy to inhibitors of specific pro-survival pathways, such as the one controlled by AKT, could enhance treatment efficacy by exploiting the pro-death stimulation derived by oncogene activation

The modifier role of RET-G691S polymorphism in hereditary medullary thyroid carcinoma : functional characterization and expression/penetrance studies

Background: Hereditary medullary thyroid carcinoma (MTC) is caused by germ-line gain of function mutations in the RET proto-oncogene, and a phenotypic variability among carriers of the same mutation has been reported. We recently observed this phenomenon in a large familial MTC (FMTC) family carrying the RET-S891A mutation. Among genetic modifiers affecting RET-driven MTC, a role has been hypothesized for RET-G691S non-synonymous polymorphism, though the issue remains controversial. Aim of this study was to define the in vitro contribution of RET-G691S to the oncogenic potential of the RET-S891A, previously shown to harbour low transforming activity. Methods: The RET-S891A and RET-G691S/S891A mutants were generated by site-directed mutagenesis, transiently transfected in HEK293T cells and stably expressed in NIH3T3 cells. Their oncogenic potential was defined by assessing the migration ability by wound healing assay and the anchorage-independent growth by soft agar assay in NIH3T3 cells stably expressing either the single or the double mutants. Two RET-S891A families were characterised for the presence of RET-G691S. Results: The functional studies demonstrated that RET-G691S/S891A double mutant displays a higher oncogenic potential than RET-S891A single mutant, assessed by focus formation and migration ability. Moreover, among the 25 RET-S891A carriers, a trend towards an earlier age of diagnosis was found in the MTC patients harboring RET-S891A in association with RET-G691S. Conclusions: We demonstrate that the RET-G691S non-synonymous polymorphism enhances in vitro the oncogenic activity of RET-S891A. Moreover, an effect on the phenotype was observed in the RET-G691S/S891A patients, thus suggesting that the analysis of this polymorphism could contribute to the decision on the more appropriate clinical and follow-up management

Mitochondrial permeabilization engages NF-kappa B-dependent anti-tumour activity under caspase deficiency

Apoptosis represents a key anti-cancer therapeutic effector mechanism. During apoptosis, mitochondrial outer membrane permeabilization (MOMP) typically kills cells even in the absence of caspase activity. Caspase activity can also have a variety of unwanted consequences that include DNA damage. We therefore investigated whether MOMP-induced caspase-independent cell death (CICD) might be a better way to kill cancer cells. We find that cells undergoing CICD display potent pro-inflammatory effects relative to apoptosis. Underlying this, MOMP was found to stimulate NF-κB activity through the downregulation of inhibitor of apoptosis proteins. Strikingly, engagement of CICD displays potent anti-tumorigenic effects, often promoting complete tumour regression in a manner dependent on intact immunity. Our data demonstrate that by activating NF-κB, MOMP can exert additional signalling functions besides triggering cell death. Moreover, they support a rationale for engaging caspase-independent cell death in cell-killing anti-cancer therapies