High-Temperature Behavior of High-Pressure Diecast Alloys Based on the Al-Si-Cu System: The Role Played by Chemical Composition

Al-Si-Cu foundry alloys are widely applied in the form of high-pressure diecast components. They feature hypo- or nearly eutectic compositions, such as AlSi9Cu3(Fe), AlSi11Cu2(Fe), and AlSi12Cu1(Fe) alloys, which are used in the present study. Diecast specimens, with a thickness of 3 mm, were used for tension tests. The short-term mechanical behavior was characterized at temperatures from 25 up to 450 C. At temperatures above 200 C, the tensile strength properties (YS and UTS) of the investigated alloys were severely affected by temperature, and less by chemical differences. Material hardness and ductility indexes better highlighted the differences in the mechanical behavior of these age-hardenable alloys and allowed us to relate them to the microstructure and its changes that took place at test temperatures. Thermodynamic calculations were found to be useful tools to predict phases formed during solidification, as well as those related to precipitation strengthening. By means of the performed comprehensive material characterization, deeper knowledge of the microstructural changes of Al-Si-Cu foundry alloys during short-term mechanical behavior was obtained. The gained knowledge can be used as input data for constitutive modeling of the investigated alloys

Influence of long heat treatments on hardness and tribological behaviour of HVOF sprayed WC-CoCr and Cr3C2-25NiCr coatings

Thermally sprayed tungsten and chromium carbide-based coatings are widely applied in several industrial applications and in harsh environments where the tribological resistance is required, such as in many components for oil &gas or petrochemical industries. The microstructural stability of the coatings is a key feature for improving the working life of components exposed at high temperature during service. While WC and Cr 3C2 -based coatings are known to be suitable materials for low and high temperature, respectively, there is the need to know their behavior at intermediate temperature to make a proper selection in these cases. In the present study two different coatings, WC-10Co-4Cr and Cr 3C2 -25NiCr, were deposited by HVOF and analyzed comparing the as received conditions with the aged conditions after isothermal treatments. The effect of aging at temperatures in the range 250-40 as evaluated focusing on hardness behaviour in function of aging time and temperature. Furthermore, wear tests measurements were performed, before and after aging, for evaluating the exposure effect on the tribological properties of both coatings

Tribological and mechanical behaviour of Cr3C2–NiCr thermally sprayed coatings after prolonged aging

Cr3C2–NiCr HVOF thermally sprayed coatings have been extensively applied on industrial components working at high temperature to improve their erosion, corrosion and oxidation resistance. In order to monitor the coating microstructural stability, a systematic investigation in the intermediate range of temperature 250–400 °C was carried out. Improved hardness and sliding wear resistance of the Cr3C2-based coatings was observed after long-term aging at temperature higher than 250 °C. However, the residual stress relaxation and a strengthening effect contributed to reduce the cracking resistance of the aged coatings, anticipating the onset of damage and crack opening to lower deflection levels during four-point bending tests

Life events and benign paroxysmal positional vertigo: a case-controlled study.

CONCLUSIONS: Within the poorly understood mechanisms implicated in the aetiology of benign paroxysmal positional vertigo (BPPV), the results of this trial provide clinical evidence of a potential role of emotional stress connected to adverse life events as a trigger of otoconial dysfunction. High levels of anxiety, depression and somatization were recorded and considered psychogenic precursors of BPPV, thus emphasizing the role of psychological distress in precipitating peripheral vestibular disorders. Therefore, appraisal of life stress and psychological attitudes may have potential implications in the clinical assessment of this labyrinthine vertigo and its frequent relapses. OBJECTIVES: BPPV is one of the most common peripheral vestibular disorders, and although it has been the subject of several studies and debates, its aetiology still remains unknown in most cases. Because it has been shown that emotional stress is related to the onset or worsening of other inner ear dysfunctions such as M\ue9ni\ue8re's disease and sudden hearing loss, this study investigated the hypothesis that life events, mood and psychological attitudes may have a causal relationship with BPPV. PATIENTS AND METHODS: Fifty patients (40 females and 10 men; mean age 43.5+/-10.1 years, range 30-65 years) were recruited and compared with 50 healthy volunteers matched for sex, age and socio-demographic variables. Patients were selected among dizzy patients who were referred to the ENT Clinic of the University of Modena and Reggio Emilia from the emergency unit with a primary diagnosis of 'positional vertigo' and enrolled in the study only if they had a paroxysmal positional nystagmus as diagnosed by Dix-Hallpike and Semont's manoeuvres. Patients with a history of recurrent vertigo and additional otoneurological diseases were excluded. The Paykel Life Events Scale, Spielberger State-Trait Anxiety Inventory, Symptom Check List-90 Revisited and Hamilton Depression Scale were the psychometric questionnaires used to complete the audiological and vestibular examinations. RESULTS: Patients with BPPV reported significantly more life events than control subjects in the year preceding the onset of vertigo (p0.05). Psychometric questionnaires recorded significantly higher levels of anxiety, depression and somatization in the pathological sample (p<0.005), as well as an increased obsessive-compulsive attitude (p<0.05)

Italia contemporanea

Italia contemporanea, prima rivista italiana di storia contemporanea, \ue8 il trimestrale dell\u2019Insmli: Istituto nazionale per la storia del movimento di liberazione in Italia. Dal 1974 essa costituisce la continuazione de Il Movimento di liberazione in Italia, che accompagn\uf2 la nascita dell\u2019Istituto nel 1949 come espressione del suo impegno scientifico e culturale. Il profondo legame della rivista e dell'Istituto con il patrimonio della cultura antifascista \ue8 espresso dall'attenzione al revisionismo e ai tentativi di annullare i fondamenti antifascisti della democrazia repubblicana. Nel corso degli anni gli interessi della rivista si sono via via ampliati e, accanto alle tematiche del binomio fascismo/antifascismo, si sono progressivamente rivolti al passaggio dal fascismo alla repubblica e ai grandi temi del Novecento: dai modelli di sviluppo economico, al nesso Stato-autonomie, al fascismo locale, al colonialismo, al razzismo. I contatti con numerosi centri di ricerca internazionale hanno portato ad un allargamento degli orizzonti geografici e tematici rivolto alla storia dell\u2019Europa e degli Stati Uniti

An uncommon cause of hemoptysis: aortobronchial fistula

Abstract Background Hemoptysis is a frequent sign of respiratory and non-respiratory diseases. While in most cases the underlying cause is rapidly identified, sometimes the real etiology might be misdiagnosed with dramatic delay in treatment. Case presentation A 46-year-old man with hiatal hernia and a history of aortic surgery for aortic coarctation presented with dramatic episodes of hemoptysis and subsequent severe anemia (6,9 g/dl). Digestive and respiratory endoscopy resulted not exhaustive, thus he underwent a contrast-enhanced computed tomography (CT) scan of the chest that showed an aneurysmal dilatation of the descending thoracic aorta with suspected aortobronchial fistula. He underwent cardiac surgery that confirmed the diagnosis and successfully treated the fistula. Conclusion We briefly review the literature to raise clinical awareness on this uncommon cause of hemoptysis

Giustizia straordinaria tra fascismo e democrazia. I processi presso le Corti d\u2019assise e nei tribunali militari

Nella fase di impianto della democrazia repubblicana la necessit\ue0 di \uabfare i conti\ubb con il passato fascista si presenta come un\u2019esigenza ineludibile. A questo scopo, gi\ue0 nel corso del conflitto vengono definiti organismi e prassi di giustizia speciale che hanno come obiettivo la punizione dei crimini avvenuti nel corso della Seconda guerra mondiale. Da un lato, a pochi giorni dalla liberazione vengono istituite le Corti d\u2019assise straordinarie, organismi responsabili a livello provinciale del giudizio sugli imputati accusati di collaborazionismo; dall\u2019altro lato, la competenza sui crimini di guerra viene affidata all\u2019attivit\ue0 dei tribunali militari sia italiani che alleati. Questo volume presenta una serie di studi e ricerche che, a partire dagli esiti dei processi istruiti da tali corti e tribunali, disegnano un profilo del fascismo repubblicano, si misurano con le modalit\ue0 di occupazione nazista, si interrogano sui confini tra diritto e politica nel giudizio sulla transizione dalla dittatura alla democrazia