Friction Stir Welding of Ti6Al4V complex geometries for aeronautical applications: a feasibility study

While Friction Stir Welding (FSW) of aluminium alloys can be considered a mature technology, even for complex joint morphologies, as T joints welded “in transparency”, welding of hard material still presents several open issues. In fact, welding of titanium alloys is a challenging process due to the chemical, mechanical and thermal characteristics of such materials which are subjected to atmosphere contamination resulting in joint hydrogen, oxygen and nitrogen embrittlement; additionally, due to the high melting temperature, large distortion and residual stress are found in joints obtained by traditional fusion welding processes as gas metal arc welding, electron beam welding and laser welding. In this way a solid-state process, as FSW, represents a valid choice in order to overcome problems related to the material melting. It should be noticed that FSW of titanium alloys is definitely more complex than the same process referred to aluminium alloys. In the proposed paper, a feasibility study on the production of Ti6Al4V T-joints in one welding pass, i.e. the so-called transparency welding, is presented. The main process parameters, i.e. tool rotation and feed rate have been fixed, and the main metallurgical and mechanical properties of the joint have been analysed. Macro and micro observations of the joints have been performed relating the final microstructure to the input process parameters utilized

A new control parameter to predict micro‑warping‑induced job failure in LPBF of TI6AL4V titanium alloy

Laser powder bed fusion (LPBF) includes a few printing techniques widely used, in recent years, concerning the additive manufacturing of Ti6Al4V alloys. These produced parts, typically utilized in sectors such as aerospace and biomedical, are characterized by very high added value. It is therefore fundamental to identify the influence of process parameters typical of LPBF technology on the occurrence of warping leading to process failure. This study deals with the characterization of single-track and “micro-scale” level warping phenomena which may lead to protrusion of material over the powder bed and process failure before normal termination. This phenomenon was investigated as a function of process parameters, referring also to the strength and ductility characteristics of the manufactured samples. With this purpose, several samples were printed using variable process parameters both in terms of line energy density (LED) values and in terms of laser power and speed combinations such as to guarantee constant LED values. For the samples that did not show significant micro-warping phenomena, in addition to the transversal and longitudinal geometric characterization of the single track, tensile tests were performed to determine both the resistance of the material and the ductility characteristics. The single tracks, for given process parameters, were printed on a homogeneous material substrate. For every single track, a microstructural and morphological transverse and longitudinal characterization has been carried out and the measured geometrical features were correlated to the process parameters. The obtained results allowed the identification of a new threshold parameter, indicating the limit operating conditions beyond which significant warping phenomena and process failure occur

Thermal deterioration of the trans-/cis-ratio of bittering agents of commercial beers

Producción CientíficaThe use of reduced isomerised hop extracts to achieve both bitterness and light stability became very popular during the last decade. Changes during storage in four hop extracts and seven commercial lager beers are studied using HPLC and spectrophotometric techniques. The degradation of the iso-α-acids and tetrahydro iso-α-acids as a function of time is represented by the ratio, in percentage, of the sum of trans-isomer concentration to the sum of the cis-isomer concentration (T/C). The results provided conclusive evidence that the gradual decreased of bitterness intensity in beer was due to the degradation of iso-α-acids, notably to the instability of the trans-iso-α-acids. When the beers were stored for 14 days at 45◦C the decrease of the T/C average varied from 8.6 to 14.0%, except in lemon beer, in which case, T/C decreased 36.9%. The results allowed us to infer that in open storage and/or warm conditions the deterioration of beer was critical above 35◦C. On the other hand, the results showed that tetrahydro iso-α-acids remained unaltered

Ultra high-pressure homogenized emulsions stabilized by sodium caseinate: effects of protein concentration and pressure on emulsions structure and stability

Microstructure, physical properties and oxidative stability of emulsions treated by colloid mill (CM), conventional homogenization (CH, 15 MPa) and ultra-high-pressure homogenization (UHPH, 100–300 MPa) by using different concentrations of 1, 3 and 5 g/100 g of sodium caseinate (SC), were evaluated. The application of UHPH treatment at 200 and 300 MPa resulted in emulsions that were highly stable to creaming and oxidation, especially when the protein content increased from 1 to 3 and 5 g/100 g. Further, increasing the protein content to 3 and 5 g/100 g in UHPH emulsions tended to change the rheological behavior from Newtonian to shear thinning. CH emulsions containing 1 g/100 g of protein exhibited Newtonian flow behavior with lower tendencies to creaming compared to those formulated with 3 or 5 g/100 g. This study has proved that UHPH processing at pressures (200–300 MPa) and in the presence of sufficient amount of sodium caseinate (5 g/100 g), produces emulsions with oil droplets in nano-/submicron scale with a narrow size distribution and high physical and oxidative stabilities, compared to CM and CH treatments

Transcatheter Cardiac Surgery

The introduction of transcatheter aortic valve implantation (TAVI) have changed the management of patients affected by severe aortic stenosis. Nowadays, TAVI procedure represents the treatment of choice in patients with severe AS inoperable or at high risk. MDCT is the technique of choice in preoperative planning: it provides information regarding aortic valve and vascular access. Particular attention should be paid on bicuspid valve morphology. The choice of valve is, basically, based on confidence and experience of the operator and center

Report on research activities carried out for determination of mercury neuro-toxicological effects on cetacean brain

In this study we analyzed Hg and Se concentrations in dolphin brain tissues of fifteen specimens of striped dolphin (Stenella coeruleoalba) and eight specimens of bottlenose dolphin (Tursiops truncatus) stranded in the Tyrrhenian and Adriatic Seas, in order to assess the toxicological risks associated with Hg exposure. High Hg concentrations were found in brain tissues of both analyzed specie (1.86–243mg/kg dw for striped dolphin and 2.1–98.7 mg/kg dw for bottlenose dolphin), exceeding levels associated with marine mammals neurotoxicity. Although the results clearly suggest that the protective effects of Se against Hg toxicity occur in cetaceans’ brain tissues, a molar excess of mercury with respect to selenium was found, particularly in adult specimens of Stenella coeruleoalba. On contrary, negligible neuro-toxicological risks were found for Tursiops truncatus specimens, due to detoxification processes. Data obtained allowed to prove a more marked neuro-toxicological risk for adult specimens of Stenella coeruleoalba in both Tyrrhenian and Adriatic Seas

Report on research activities carried out for determination of Mercury in different tissues of cetaceans

Mercury concentration in different tissues of two dolphin species (Stenella coreuleoalba and Tursiops truncatus), stranded along the Italian coasts during the period 2000– 2009, were reported in order to assess Hg distribution patterns in different tissues. The highest concentrations of Hg were found in liver samples of both species (8.4-1752 mg/kg dw for Stenella coeruleoalba and 9.6-1404 mg/kg dw for Tursiops truncatus). Relative high mercury concentrations were reported also in kidney and lung tissues. The existence of Hg bioaccumulation process over time was also reported. The dataset documents the existence of different mechanisms of mercury bioaccumulation in the different tissues analyzed

Report on research activities carried out for determination of Cadmium and Arsenic in tissues of different cetacean species

Concentrations of Cd and As were determined in organs and tissues (muscle, heart, kidney, lung and liver) of two cetacean species (Stenella coeruleoalba and Truncatus truncatus) stranded along the Italian coasts during the period 2000–2009. Significant differences were found between Cd concentrations in the different analyzed tissues. Particularly, the kidney shows the highest concentrations of Cd in all analyzed specimens, followed by the liver. The heart shows the highest As concentrations with respect to the other tissues analyzed. Specimens of S. coeruleoalba show higher Cd concentrations in their tissue than specimens of T. truncatus, probably because of a higher proportion of squid in their diet

Relationships between optical aggregometry (type Born) and flow cytometry in evaluating ADP-induced platelet activation

Background: Platelet response to activating agents is used to monitor the efficacy of anti-aggregation therapies. The aim of our study has been to demonstrate the existence of relationships between early events of ADP-induced platelet activation, measured by flow cytometry and platelet-rich plasma aggregation,quantified by optical aggregometry. Methods: We evaluated peripheral blood of 12 donors. The following parameters were quantified by cytometry after stimulation with adenosine diphosphate (ADP) (0.5, 1, 2, 5, 10, 20 uM): CD62P (P-selectin) and PAC-1 expression, and cytosolic Ca2+ mobilization. Aggregation was measured by optical aggregometry. We also studied 13 patients, undergoing coronary stenting, treated with aspirin (before procedure) or with aspirin plus clopidogrel (after procedure). We evaluated CD62P and PAC-1 expression, aggregation,and vasodilator-stimulated phopshoprotein phosphorylation (platelet reactivity index, PRI). Results: Flow procedures were more sensitive than aggregometry, with a lowest interindividual variability. Linear relationships existed in donors between CD62P expression and Ca2+ mobilization (P<0.0001),and between aggregation and Ca2+ mobilization (P<0.0001). Linear relationships existed between aggregation and CD62P expression, as percentage (P<0.0001), or relative fluorescence intensity (RFI) (P<0.0001). Exponential equations related aggregation and PAC-1 expression, as percentage (P<0.0001), or RFI (P<0.0001). Linear relationships between aggregation and CD62P expression (as percentage) existed in the patients before (P=0.0022) and after procedure (P=0.0020. Exponential relationships between aggregation and PAC-1 expression (as percentage) existed before (P=0.0012) and after procedure (P=0.0024). Linear correlations related aggregation response predicted on CD62P expression, and measured aggregation inhibition after clopidogrel (P=0.0013) as well as predicted aggregation and PRI inhibition (P=0.0031). Conclusions: Tight relationships between aggregation and cytometric quantification of platelet markers in whole blood, in particular CD62P, allow to predict aggregation response to ADP from flow data in patients treated with aspirin alone or with aspirin plus clopidogrel

Urografia-TC multidetettore: ruolo diagnostico nella valutazione del paziente con ematuria non traumatica

L’ematuria può originare da qualsiasi tratto dell’apparato urinario e può essere anche unico segno di patologia neoplastica (cancro del rene o della vescica). La letteratura raccomanda pertanto di sottoporre ad attenta valutazione clinico-strumentale tutti i casi di ematuria, macroscopica e microscopica. Lo scopo del presente contributo è quello di definire il ruolo diagnostico dell’urografia-TC multidetettore (uTC-MD) nella valutazione di questo sintomo e analizzarne l’impatto nel management del paziente attraverso lo studio di 181 pazienti consecutivi valutati per macro- e microematuria nel periodo compreso tra gennaio 2003 e marzo 2006