322,925 research outputs found
Sviluppo di trattamenti termici per componenti automotive colati in lega di alluminio secondario allo stato semi-solido
No full textstudio dell'influenza della temperatura e del tempo di solubilizzazione sulle carattteristiche microstrutturali e le proprietà meccaniche di una lega secondaria AlSi7Cu3Mg colata allo stato semi-solido. Analisi della sferoidizzazione del Silicio eutettico, della dissoluzione delle fasi intermetalliche ricche in rame e la variazione di durezza della lega
Effect of NaCl, KCl e Na3AlF6 on the refining process of aluminium alloys
No full textTo maximize the efficiency of the fluxes during the refining of the aluminium alloy scrap, a proper balance of the salts is required. This study preliminarily investigates the influence of different concentrations of NaCl, KCl and Na3AlF6 on the chemical and physical properties of the fluxes used during the refining process of the aluminium alloys. The melting temperature and the viscosity of the flux at different concentrations of NaCl, KCl and Na3AlF6 were analysed, as well as the ability to dissolve the aluminium oxide. Furthermore, the dissolution of the flux in water was investigated. The results showed how the melting temperature of the flux decreases, while the viscosity increases as the cryolite content increases. The attitude of dissolving the Al oxide is favoured by the addition of Na3AlF6, even at low concentrations and reduced time of treatment. The dissolution of the oxide allows the liquid aluminium entrapped in the scrap to be released and to return into the molten bath, thus increasing the yield of the refining process. On the contrary, the dissolution of the flux in water is reduced after the addition of cryolite
Influence of T6 and T7 Heat Treatments on the Mechanical Properties of Rheocast Secondary AlSi7Cu3Mg Alloy
No full textThe effects of T6 and T7 heat treatmentsHeat treatment on the mechanical propertiesMechanical properties of a rheocast secondary AlSi7Cu3Mg alloyAlloys are investigated. A lower arm automotiveAutomotive suspension was cast as a demonstrator. While the solution treatment was optimized in previous research, the quenching rate and the ageing treatment were here studied. The influence of the quenching process on the component’s distortionDistortion was analysed by a coordinate-measuring technique. The results indicated a significant effect of the quenching rate on the tensile properties as well as the distortionDistortion of the component. Water quenching led to a greater distortionDistortion of the component compared to still-air cooling. The elongation to fractureFracture seemed to be less affected by the quenching process. Higher ductility was obtained after the over-ageing T7 treatment, while the yieldYield and tensile strengths were similar to those obtained after a peak ageing T6 treatment
Effect of T6 heat treatment on the microstructure and hardness of secondary AlSi9Cu3(Fe) alloys produced by semi-solid SEED process
No full textThe effect of the T6 heat treatment on the microstructure and hardness of a secondary semi-solid AlSi9Cu3(Fe) alloy have been investigated by using optical, scanning and transmission electron microscopy and hardness testing. The semi-solid alloy was produced using the swirled enthalpy equilibration device (SEED). The solution heat treatments were performed at 450, 470 and 490 °C for 1 to 6 h followed by water quenching and artificial ageing at 160, 180 and 220 °C for holding times ranging from 1 to 30 h. The microstructural investigations have revealed the spheroidization of the eutectic Si and the dissolution of the majority of Cu-rich compounds after all the solution heat treatments; moreover, the greater the solution temperature and time, the higher the hardness of the alloy. Unacceptable surface blistering has been observed for severe solution condition, 490 °C for 3 and 6 h. The artificial ageing at 160 °C for 24 h has led to the highest alloy strengthening thanks to the precipitation of β” and Q’ (or L) phases within the α-Al matrix. The hardening peaks at higher temperatures have been early achieved due to faster hardening kinetic; however, the lower number density of β” and Q’ (or L) phases and the presence of coarser θ’ precipitates result in a reduction of hardness values for peak aged condition at 180 and 220 °C, respectively
Initiation of psychotropic medication in hospitalized patients with COVID-19: Association with clinical and biological characteristics
No full textIntroduction: Inpatients with coronavirus disease 2019 (COVID-19) show a high rate of neuropsychiatric manifestations, possibly related to a higher risk of serious illness or death. Use of psychotropic medications (PMs) indicates the presence of neuropsychiatric symptoms in COVID-19 patients. So far, potential clinical predictors of use of PMs have not been much investigated. In order to extend research in this area, we aimed to investigate the prevalence of PM prescription among a sample of inpatients with COVID-19 and to find potential predictors of initiation of PMs in these individuals.
Methods: This is a cross-sectional single-center study, conducted during the first outbreak peak in a hospital of northern Italy. Information on socio-demographic characteristics, comorbidities, routine blood test, use of potential COVID-19 treatments, and length of stay were retrieved from medical records.
Results: Data were available for 151 inpatients. Forty-seven of them (31.1%) started at least one prescription of a PM. PM prescription was significantly inversely associated with lymphocyte and platelet counts. A significant association was also found for lactate dehydrogenase (LDH).
Conclusion: Our findings suggest that the initiation of PMs could be common among COVID-19 inpatients. Lymphocyte and platelet counts as well as LDH levels may reflect neuropsychiatric complications of COVID-19
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Indagando la natura “multilivello” di uno spazio politico : un’analisi Twitter-based sulle Elezioni Regionali del 2015 in Italia
No full textGli studi che finora si sono occupati di ricostruire come gli elettorati percepiscono la competizione tra partiti (e i loro leader) sono per lo piu’ consistiti in analisi, talvolta comparate, della struttura di questa a livello nazionale. Eppure la coesistenza di sfere competitive locali pone necessariamente il problema, oltre che l’interesse, di confrontare la configurazione di spazi politici a diversi livelli territoriali.
Il caso di studio su cui questo contributo si concentra è quello delle elezioni regionali del 2015 in Italia. Diverse sono le ragioni che suggeriscono la peculiarità di tale contesto competitivo rispetto a quello nazionale. Tra queste, i caratteri del sistema elettorale, tra cui, in alcune regioni, il voto diretto al candidato presidente con voto disgiunto e il voto di preferenza. Ricordiamo inoltre le diversificate strategie di apparentamento coalizionale, spesso non congruenti con quelle esistenti a livello nazionale. Da non dimenticare, infine, la loro natura di second-order elections. Da ciò discende l’ipotesi che tali peculiarità comportino, a livello locale, una perturbazione della rappresentazione nazionale dello spazio.
Tale aspettativa è rimasta finora inesplorata per via di una sostanziale mancanza di dati. Oggi, tuttavia, l’imponente sviluppo di tecniche di raccolta e analisi di social media data (in particolare Twitter) sembra offrire importanti opportunità in questo senso. Sulla scia di alcuni studi precedenti, il presente contributo si pone come un esercizio per capire se l’analisi di dati raccolti su tale piattaforma possa costituire una soluzione metodologica affidabile, oltre che meno costosa rispetto a quelle tradizionali, anche per affrontare il problema della configurazione di spazi politici a diversi livelli di governo territoriale. La strategia empirica che utilizzeremo per testare le nostre ipotesi farà riferimento a tradizionali tecniche di multidimensional scaling. Queste verranno applicate all’analisi dei legami di following tra utenti, partiti e liste nazionali e locali su Twitter, di cui già altri autori hanno dimostrato l’affidabilità in relazione alla determinazione delle posizioni ideologiche di partiti e candidati a livello nazionale
Dynamic regulation of Arabidopsis β-AMYLASE1 by glutathione and thioredoxins affects starch in guard cells
No full textGuard cells control the opening and closure of stomatal pores in response to internal and external stimuli, ensuring gas exchange in plants. In Arabidopsis (Arabidopsis thaliana), beta-AMYLASE1 (BAM1), assisted by alpha-AMYLASE3, begins degrading starch at dawn in guard cells to promote stomatal opening. Both enzymes are controlled by reversible disulfide bond formation, which decreases their activity. In the present study, we investigated the sensitivity of BAM1 to other redox-dependent post-translational modifications (PTM) both in vitro and in vivo. In vitro, H2O2 reversibly inactivates BAM1 and, in the presence of glutathione (GSH), induces S-glutathionylation of BAM1. Glutathionylated BAM1 is active and transiently protected from H2O2 inhibition. However, the glutathionylated state of BAM1 has limited stability and can be slowly resolved by a second cysteine with the formation of the intramolecular disulfide bond that inhibits BAM1 activity. Thioredoxin f can fully revert the inhibition by reducing the disulfide to a dithiol. In vivo, Arabidopsis mutants with lower plastidial GSH reductase activity, and consequently modified GSH homeostasis, showed higher BAM1 activity, lower starch levels in guard cells, and altered stomata aperture, indicating that GSH redox potential impacts stomatal physiology, possibly through BAM1. Moreover, plastidial BAM1 presents a prime example for the role of glutathionylation functioning as a transiently protective PTM, interfering with the formation of inhibitory disulfide bonds. This example illustrates how transitions between protein cysteinyl thiol PTMs can orchestrate dynamic responses involving several redox systems.The redox homeostasis of GSH regulates starch metabolism in guard cells by influencing the activation state of the beta-AMYLASE1, a key enzyme in guard cell starch degradation
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