Effect of air entraining admixture on the properties of self-compacting concrete incorporating supplementary cementitious materials

Self-compacting concrete has gained a wide range of applications as a result of its unique properties, which can offer high strength and durable type of concrete with the proper selection of the raw materials. The purpose of this study was to show the effect of the use of high dosage of air entraining admixture on the properties of self-compacting concrete. An experimental investigation on the frost-salt scaling resistance of conventional and air entraining selfcompacting concrete incorporating slag-blended cement and supplementary cementitious materials was carried out. Further fresh and hardened properties tests including slump flow, V-funnel, compressive strength, splitting tensile strength, air void characteristics and water absorption tests were performed to obtain an objective evaluation between air and non-air entrained self-compacting concrete mixtures. Air void characteristics were evaluated through the automated image analysis procedure to enrich this investigation. Results indicate the following: the air entraining admixture highly decreased the compressive strength up to 52% and the metakaolin was the governing supplementary cementitious material concerning the scaling resistance and water absorption in comparison with the silica fume

Structural and optical properties of nanoparticles (V, Al) co-doped ZnO synthesized by sol–gel processes

ZnO, Zn0.9V0.1O and Zn0.89V0.1Al0.01O nanoparticles have been prepared by a sol–gel method and their structural and optical properties have been investigated. The obtained nanopowder was characterised by various techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. After thermal treatment at 500 C in air, the powder of Zn0.89V0.1Al0.01O with an average particle size of 25 nm presents a strong luminescence band in the visible range. The PL band energy position presents a small blue shift with the increase of measurement temperature. Different possible attributions of this emission band will be discussed

Sol–gel synthesis, structural and luminescence properties of MT-doped SiO2/Zn2SiO4 nanocomposites

The sol–gel method is used for the preparation of undoped, Mn and V-doped Zn2SiO4 particles embedded in SiO2 host matrix. The phase purity and morphological features were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) investigations. The obtained SiO2/Zn2SiO4 nanocomposite, exhibits a strong photoluminescence (PL) band centered at around 760nm, attributed to energy transfer occurs from Zn2SiO4 particles to NBOHs interfaces defects. In addition, the PL spectrum for the SiO2/Zn2SiO4:Mn nanocomposite showed that a dominant peak at 525nm appeared, which originated from the 4T1–6A1 transitions of Mn2+ ions. In the case of SiO2/Zn2SiO4:V, the PL reveals a band centered at about 540nm attributed to the effect of the V5+ in the host matrix nanocomposite

Processi di razzializzazione e pratiche di resistenza. Il caso del Movimento Migranti e Rifugiati Napoli

In Italia, come in tutti i paesi europei, é in atto processo di razzializzazione, in parte di lungo periodo, in parte relativo a que-st'epoca di rinnovate migrazioni, che si manifesta su diverse di-mensioni sociali. Questo processo non è solo simbolico, quindi attinente al linguaggio o alla sfera rappresentativa, ma riguarda la dimensione materiale del lavoro, ovvero della produzione della ricchezza, dello Stato e delle sue articolazioni territoriali, quindi del potere, del monopolio della violenza sul territorio e della pro-duzione gerarchica delle forme di cittadinanza. Di conseguenza, non si può impedire la razzializzazione e la riproduzione del raz-zismo solo intervenendo sul simbolico, sul linguaggio o sperando che l'autoriforma interna alle istituzioni produca un'astratta eguaglianza. Queste tendenze e processi vengono subiti passivamente dai soggetti che ne sono interessati. Il caso del Movimento Migranti e Rifugiati Napoli rappresenta un modello inedito di organizzazione che dal 2016 attraverso attività, sportelli di assistenza e poteste di piazza cerca di produrre pratiche di resistenza alle forme di razzismo istituzionale e alle tendenze di razzializzazione. Il presente studio cerca di descrivere e verificare in che misura queste azioni riescano effettivamente a contrastare, o meno, i processi i processi di razzializzazione

Editorial:Metformin: Beyond Diabetes

International audienc

Neurotropic Manifestations as a Potential Risk Factor for Schizophrenia Following in utero Exposure to SARS-CoV-2

Background: COVID-19 infection is associated with neurologic and psychiatric morbidity that suggests a direct effect of the virus or secondary effect of an inflammatory process. These neuropsychiatric consequences may increase the likelihood of schizophrenia in the offspring of women who become infected with COVID-19 during their pregnancy. Methods: We performed a directed narrative review of the literature focusing on the proposed pathophysiological processes that lead to schizophrenia and known pathological consequences of COVID-19 infection. Results: Schizophrenia in adult offspring has been associated with maternal infections during pregnancy by a wide range of respiratory and neurotropic pathogens. Spikes in the incidence of schizophrenia approximately 20 years after several influenza pandemics have been documented. There are multiple lines of evidence suggesting that a similar pattern may be seen due to the recent COVID-19 pandemic. These include the nonspecific consequences of acute illness and hyperpyrexia, as well as more specific derangements of brain development related to direct effects of the virus or secondary effects of the inflammatory response on the developing brain. There is the potential to prospectively test this hypothesis by following the offspring of women who are known to have developed COVID-19 during their pregnancy. Conclusion: The COVID-19 pandemic is likely associated with a range of future neuropsychiatric consequences in people whose mothers suffered the infection during their fetal development. It is important to try to follow these offspring to determine the full range of consequences of COVID-19 infection

Multivector and multivector matrix inverses in real Clifford algebras

We show how to compute the inverse of multivectors in finite dimensional real Clifford algebras Cl(p, q). For algebras over vector spaces of fewer than six dimensions, we provide explicit formulae for discriminating between divisors of zero and invertible multivectors, and for the computation of the inverse of a general invertible multivector. For algebras over vector spaces of dimension six or higher, we use isomorphisms between algebras, and between multivectors and matrix representations with multivector elements in Clifford algebras of lower dimension. Towards this end we provide explicit details of how to compute several forms of isomorphism that are essential to invert multivectors in arbitrarily chosen algebras. We also discuss briefly the computation of the inverses of matrices of multivectors by adapting an existing textbook algorithm for matrices to the multivector setting, using the previous results to compute the required inverses of individual multivectors