Effect of Industrial Heat Treatment and Barrel Finishing on the Mechanical Performance of Ti6Al4V Processed by Selective Laser Melting

Additive manufacturing is now capable of delivering high-quality, complex-shaped metallic components. The titanium alloy Ti6Al4V is an example of a printable metal being broadly used for advanced structural applications. A sound characterization of static mechanical properties of additively manufactured material is crucial for its proper application, and here specifically for Ti6Al4V. This includes a complete understanding of the influence of postprocess treatment on the material behavior, which has not been reached yet. In the present paper, the postprocess effects of surface finish and heat treatment on the mechanical performance of Ti6Al4V after selective laser melting were investigated. Some samples were subjected to barrel finishing at two different intensities, while different sets of specimens underwent several thermal cycles. As a reference, a control group of specimens was included, which did not undergo any postprocessing. The treatments were selected to be effective and easy to perform, being suitable for real industrial applications. Tensile tests were performed on all the samples, to obtain yield stress, ultimate tensile strength and elongation at fracture. The area reduction of the barrel-finished samples, after being tested, was measured by using a 3D scanner, as a further indication of ductility. Experimental results are reported and discussed, highlighting the effect of postprocessing treatments on the mechanical response. We then propose the optimal postprocessing procedure to enhance ductility without compromising strength, for structures manufactured from Ti6Al4V with selective laser melting

Studio portrait of a man with two children

A man in urban clothes with traditional elements is posing with two children in light-coloured urban dresses, also with traditional elements

Indagine alle origini del Repubblicanesimo machiavelliano. Il pensiero politico a Firenze fra Trecento e Quattrocento.

Machiavelli: Le parti sociali, ontologicamente connotate e fra loro irriducibili, si armonizzano a vantaggio del bene comune, in un quadro politico di sovranità delle Leggi e di regime istituzionale repubblicano (Discorsi), esito di un processo storico di sviluppo conflittuale ed allargamento democratico (Istorie). 1) da Remigio de’ Girolami: riconoscimento del conflitto di parti come dato di fatto sociale, positivo quando sfocia in una realizzazione armonica nelle istituzioni del Comune e nella pace delle Leggi. 2) da Bartolo da Sassoferrato: il regime repubblicano, vigente nei Comuni italiani e compatibile con l’ordinamento imperiale, garantisce a livello politico (giuridico ed istituzionale) l’armonizzazione delle parti. 3) da Marchionne di Coppo Stefani: il conflitto non nasce solo dalla polarizzazione di fazioni opposte, ma da esigenze eterogenee dei gruppi, che si differenziano nel corso dello sviluppo storico e lottano per il potere. 4) da Coluccio Salutati: Libertas è sinonimo di autonomia politica, nel quadro dell’Impero, e di dominio della Legge sugli interessi personali (contro il Visconti) o di fazione (contro i Ciompi). 5) da Leonardo Bruni: Patria è la sovranità di un Popolo su se stesso (autolegislazione), limitata da confini territoriali ed ispirata, istituzionalmente e giuridicamente, alla Res Publica romana, di cui Firenze è erede

Studio portrait of a man

Full-length shot of a man sitting on a chair in urban clothes and a felt hat (fez). He is wearing a medal around his neck. He is resting his arm on a dresser with books

Space and time in the parietal cortex: fMRI Evidence for a meural asymmetry

How are space and time related in the brain? This study contrasts two proposals that make different predictions about the interaction between spatial and temporal magnitudes. Whereas ATOM implies that space and time are symmetrically related, Metaphor Theory claims they are asymmetrically related. Here we investigated whether space and time activate the same neural structures in the inferior parietal cortex (IPC) and whether the activation is symmetric or asymmetric across domains. We measured participants’ neural activity while they made temporal and spatial judgments on the same visual stimuli. The behavioral results replicated earlier observations of a space-time asymmetry: Temporal judgments were more strongly influenced by irrelevant spatial information than vice versa. The BOLD fMRI data indicated that space and time activated overlapping clusters in the IPC and that, consistent with Metaphor Theory, this activation was asymmetric: The shared region of IPC was activated more strongly during temporal judgments than during spatial judgments. We consider three possible interpretations of this neural asymmetry, based on 3 possible functions of IPC

Import, Export and Turnover in Morocco

International trade is commonly view as an useful tool to remove market distortions, to promote competition among firms and hence increase welfare. However, trade openness is not costless and unavoidably creates gainers and losers (Wood (1995, 1998)). Hence, a complete evaluation of the gain from trade should consider both efficiency benefits and adjustment costs. Indeed, to enjoy of the gain from trade liberalisation, some adjustment processes are required. Increasing trade will induce reallocation of resources from less efficient firms to more productive one, with a final positive effect on growth and uncertain consequences for the labour market. With increasing competition, the less efficient firms will exit from the market and the others should increase their productivity to strengthen their position. The first attempts to analyse the impact of trade on labour market focused on the net change in wage and employment levels (Bottini (2005) and Hoeckman and Winters (2005) for a review of the literature). However, further analysis have highlighted that looking at total levels of employment is likely to conceal important dynamics in the labour market and in the economic analysis (Davis and Haltiwanger, 1996). Indeed net change in total employment is derived by adding up new places available through the entry of new firms and expansion of existing firms and employment losses over shrinking and exiting establishments. Studying the link between trade liberalisation and job dynamics is hence a way to examine how increasing trade impacts on job turnover and input reallocation. Furthermore, it is important to detangle the effect of trade on labour market by dealing separately with import and export flows. The available literature shows that trade liberalisation will lead to labour reallocation, with jobs moving away from import-competing industries toward export industries (Davidson and Matusz (2001)). Intuitively, import and export flows have an opposite impact on labour market. Increasing import competition worsen market condition for domestic firms and causes firms exit and downsizing with a final negative effect on employment. On the other side, increasing exports creates more opportunities for domestic firms, induces sector expansion and creation of new jobs. Finally, trade liberalisation. has been also blamed for a “race to the bottom” in the labour market in the form of lower compliance with labour market standards, more extensive use of part-time and temporary labour, and a decrease in the job quality for the neo-employed (Goldberg and Pavcnik, 2004). Hence, it would be interesting to investigate whether trade liberalisation impact in a different way on temporary and permanent workers. The purpose of this paper is to study how import and export flows impact on job reallocation in the Moroccan economy

Escobajos de la vid como fuente de compuestos fenólicos con propiedades antioxidantes

Winemaking industry generates considerable amounts of bunch stems that are usually wasted despite their potential value as source of bioactive compounds. Phenolic profiles and antioxidant capacity (AC) of bunch stem extracts from eight grape varieties of Vitis vinifera L. were determined. Sixteen phenolic compounds (PC) were quantified by high performance-liquid chromatography-diode array detection (HPLC-DAD). The maximum concentrations corresponded to the flavanols (+)-catechin (6462 μg g-1 DW) and procyanidin B1 (1987 μg g-1 DW), followed by the hydroxycinnamic acid caftaric acid (2967 μg g-1 DW). Naringin, myricetin and OH-tyrosol were identified for the first time in grape bunch stems. Total phenolic content (TPC) of extracts, assessed as gallic acid equivalents (GAE), ranged between 47 and 125 mg GAE g-1 DW. The AC of extracts was appraised by ORAC, ABTS and DPPH assays, with a good correlation between TPC and AC when measured by ABTS and DPPH (r ≥ 0.92), while for ORAC the correlation was lower (r ≤ 0.41). Samples of cv. Malbec, the most representative variety of Argentina, presented the highest contents in PC, particularly flavanols. The results showed that grape bunch stems may be an inexpensive, sustainable and high value source of bioactive compounds as functional ingredients.La industria vitivinícola genera cantidades considerables de escobajo que generalmente se desperdician a pesar de su valor potencial como fuente de compuestos bioactivos. En este trabajo se determinaron los perfiles fenólicos y capacidad antioxidantes (CA) de extractos de escobajo de ocho variedades diferentes de Vitis vinífera L. Se cuantificaron 16 compuestos fenólicos (PC) utilizando cromatografía líquida de alta resolución acoplada a detector de arreglo de diodos (HPLC-DAD). Las concentraciones más elevadas obtenidas correspondieron a los flavanoles (+)-catequina (6462 μg g-1 peso seco) y procianidina B1 (1987 μg g-1 peso seco), seguido del ácido caftárico (2967 μg g-1 peso seco). La naringenina, miricetina y OH-tirosol fueron identificados por primera vez en escobajos. El contenido total de compuestos fenólicos (TPC) de los extractos determinado con equivalentes de ácido gálico (GAE) presentó valores entre 47 y 125 mg GAE g-1 peso seco. La CA de los extractos fue determinada mediante las técnicas ORAC, ABTS y DPPH, evidenciando una buena correlación entre TPC y la CA medida mediante ABTS y DPPH (r ≥ 0,92), mientras que para ORAC la correlación fue más baja (r ≤ 0,41). La muestra de variedad más representativa de Argentina, cv. Malbec, presentó los mayores niveles de PC, particularmente flavanoles. Los resultados evidencian que los escobajos pueden ser una fuente económica, sostenible y de alto valor de compuestos bioactivos para su utilización como ingredientes funcionales.Fil: Ferreyra, Susana Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; ArgentinaFil: Bottini, Ambrosio Rubén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; Argentina. Universidad "Juan Agustín Maza"; ArgentinaFil: Fontana, Ariel Ramón. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; Argentin

EFFETTI DELLA RADIAZIONE A MICROONDE SULLE REAZIONI CHIMICHE

A partire dagli anni ’80 le microonde sono state utilizzate nei laboratori chimici come mezzo di riscaldamento di miscele di reazione, in alternativa ai mezzi convenzionali. Sorprendentemente il riscaldamento a MW influisce in modo assai favorevole sul decorso di molte reazioni; i vantaggi di questo metodo sono spesso impagabili. In questo elaborato vengono presentati i meccanismi di interazione delle microonde con la miscela di reazione, con particolare attenzione a quelli termici e alle ipotesi di interazione non termica. Sono poi considerati i dati cinetici di letteratura per tre tipi di reazione: (1) cicloisomerizzaazione in acqua di 2-alchinilaniline per dari indoli sostituiti; (2) produzione di un materiale organico-inorganico con un processo sol-gel a partire da Si(OEt)4 e da un copolimero PE-PEG-Si; (3) metatesi olefinica catalizzata da Rutenio in assenza di solvente. I dati a disposizione sono analizzati tramite le equazioni di Arrhenius e di Eyring. Nessuna delle cinetiche esaminate mostra esplicitamente l’esistenza di effetti non termici delle microonde sulle velocità di reazione. Tuttavia la prima reazione presenta varie pecularietà non spiegabili come semplici effetti termici