METTL3 regulates WTAP protein homeostasis

The Wilms tumor 1 (WT1)-associated protein (WTAP) is upregulated in many tumors, including, acute myeloid leukemia (AML), where it plays an oncogenic role by interacting with different proteins involved in RNA processing and cell proliferation. In addition, WTAP is also a regulator of the nuclear complex required for the deposition of N6-methyladenosine (m6A) into mRNAs, containing the METTL3 methyltransferase. However, it is not clear if WTAP may have m6A-independent regulatory functions that might contribute to its oncogenic role. Here, we show that both knockdown and overexpression of METTL3 protein results in WTAP protein upregulation, indicating that METTL3 levels are critical for WTAP protein homeostasis. However, we show that WTAP upregulation is not sufficient to promote cell proliferation in the absence of a functional METTL3. Therein, these data indicate that the reported oncogenic function of WTAP is strictly connected to a functional m6A methylation complex

Predicting viscosity and surface tension at high temperature of porcelain stoneware bodies: A methodological approach

The shear viscosity and the glass-vapor surface tension at high temperature are crucial to understand the viscous flow sintering kinetics of porcelain stoneware. Moreover, the pyroplastic deformation depends on the viscosity of the whole body, which is made up of a suspension of crystals dispersed in the melt. The existing fundamental theoretical background, along with semi-empirical constitutive laws for viscous flow sintering and glass densification, can be exploited through different approaches to estimate the physical properties at high temperatures starting from amount and chemical composition of the melt. In this work, a comprehensive attempt to predict the properties of the liquid phase is proposed by means of a detailed overview of existing models for viscosity and surface tension of glasses and melts at high temperature. The chemical composition of the vitreous phase and its physical properties at high temperature are estimated through an experimental approach based on the qualitative and quantitative chemical and phase analyses (by Rietveld refinement of X-ray powder diffraction patterns) of different porcelain-like materials. Repercussions on the firing behavior of ceramic bodies, are discussed. Comparative examples are provided for porcelain stoneware tiles, vitreous china and porcelain bodies, disclosing differences in composition and properties but a common sintering mechanism

High temperature viscosity of porcelain stoneware bodies

The viscosity of porcelain stoneware at high temperatures is crucial to understanding the vitrification path, the viscous flow sintering kinetics, and the pyroplastic deformation of this material. The final viscosity of porcelain stoneware has to be determined considering both the viscosity of the liquid phase formed by the melting of feldspars – and other minerals – and the viscosity of the body made up of a suspension of crystals dispersed in the melt. A fundamental theoretical background along with semi-empirical constitutive laws on viscous flow sintering, glass densification, as well as on the high viscosity of liquids and melts already exists. Different approaches are needed to measure/estimate the two viscosities and the parameterization depends on both the chemical composition of the liquid phase and persistence of crystal phases in the melt. In this work, a first attempt to predict the viscosity of a porcelain stoneware liquid phase is proposed by means of a detailed overview of preexisting models for high temperature viscosities of glasses and melts. Although models developed for glasses take into account a large number of oxides and they can be applied to melts characterized by a wide compositional range, the maximum concentration of alumina expected by these models is too low compared with that of the systems investigated here. On the other hand, the models proposed for granitic melts, although based on a lower number of oxides, take into account alumina levels closer to those of the systems of interest. In this contribution it is demonstrated that the latter models can be used to predict the viscosity at high temperature of porcelain-like bodies. Comparative examples are provided for porcelain stoneware tiles, vitreous china, and porcelain bodies

Phase evolution during reactive sintering by viscous flow: Disclosing the inner workings in porcelain stoneware firing

Porcelain stoneware is sintered by partial vitrification through viscous flow of a liquid phase formed at high temperature. This sintering process involves a complex evolution of both phase composition and chemistry of the liquid phase, according to the dynamic equilibrium established with the residual minerals and the new crystalline phases formed during firing. The present contribution overviews the evolution of phase composition and microstructure of seven body formulations during firing at different temperatures and dwell times. Each mixture was characterized from the chemical point of view and, once fired, by XRPD (quantitative phase composition), SEM and optical microscopy (microstructure). Moreover, the sintering behavior of the batches was investigated in isothermal conditions by optical thermo-dilatometric analysis. The results indicate that the continuous variation of the phase composition during the heating treatment affects the chemical composition of the liquid phase reflected on the densification kinetics and pyroplastic deformation of tiles

In situ high-temperature structural evolution of the Ca(Ti,Ge)O3 perovskite solid solution: looking for a new locked-tilt perovskite

A recent synchrotron structural investigation at high-pressure (HP) sets YAl0.25Cr0.75O3 orthorhombic perovskite as the prototype of the so-called "locked-tilt" perovskites. Placed at the boundary of the previously described structural evolution models for GdFeO3-type perovskites at HP, YAl0.25Cr0.75O3 represents the first finding of a perovskite characterized by the absence of changes in the octahedral tilting (as well as octahedral distortion), and a volume reduction with P exclusively controlled by an isotropic polyhedral compression. Although a theoretical modeling of a new locked-tilt perovskite can be done with a high degree of accuracy, the only way to confirm the possible occurrence of a perovskite belonging to this family is through new experiments at non-ambient conditions (HP or High Temperature, HT). The use of geochemical constrains, and the assessment of the "normalized cell distortion factor with pressure/temperature, dnorm(P/T)" for several perovskite solid solutions, allowed the identification of three possible locked-tilt perovskite formulations, i.e., La(Mn0.69Ga0.31)O3, Ca(Ti0.95Ge0.05)O3, and (Sc0.86Y0.14)AlO3, respectively. The aim of our proposal is to investigate at HT the above identified Ca(Ti,Ge)O3 perovskite solid solution which were previously characterized at ambient conditions through structural refinements from X-ray Powder Diffraction (XRPD). Besides to extend the locked-tilt perovskite family, this investigation will provide a deeper comprehension on the role of these compounds in view of their application as functional materials (e.g., multiferroics, layered perovskites). Furthermore, the structural modification at HT of a hypothesized locked-tilt perovskite where the cubic site has a lower formal charge than the octahedral site (i.e., the 2:4 Ca(Ti0.95Ge0.05)O3), will be extremely useful from a geophysical viewpoint to outline a more accurate Earth's mantle model

Porcelain versus Porcelain Stoneware: So Close, So Different. Sintering Kinetics, Phase Evolution, and Vitrification Paths

Five porcelain and porcelain stoneware bodies were investigated to compare sintering mechanisms and kinetics, phase and microstructure evolution, and high temperature stability. All batches were designed with the same raw materials and processing conditions, and characterized by optical dilatometry, XRF, XRPD-Rietveld, FEG-SEM and technological properties. Porcelain and porcelain stoneware behave distinctly during sintering, with the convolution of completely different phase evolution and melt composition/structure. The firing behavior of porcelain is essentially controlled by microstructural features. Changes in mullitization create conditions for a relatively fast densification rate at lower temperature (depolymerized melt, lower solid load) then to contrast deformations at high temperature (enhanced effective viscosity by increasing solid load, mullite aspect ratio, and melt polymerization). In porcelain stoneware, the sintering behavior is basically governed by physical and chemical properties of the melt, which depend on the stability of quartz and mullite at high temperature. A buffering effect ensures adequate effective viscosity to counteract deformation, either by preserving a sufficient skeleton or by increasing melt viscosity if quartz is melted. When a large amount of soda–lime glass is used, no buffering effect occurs with melting of feldspars, as both solid load and melt viscosity decrease. In this batch, the persistence of a feldspathic skeleton plays a key role to control pyroplasticity

Ceramisation of hazardous elements: benefits and pitfalls of the inertisation through silicate ceramics

The addition of wastes to silicate ceramics can considerably expand the compositional spectrum of raw materials with a possible inclusion of hazardous components. The present work quantitatively examines relevant literature to determine whether the benefits of incorporating hazardous elements (HEs) into silicate ceramics outweigh the pitfalls. The mobility of various HEs (Ba, Zn, Cu, Cr, Mo, As, Pb, Ni, and Cd) has been parameterised by three descriptors (immobilisation efficiency, mobilised fraction, and hazard quotient) using leaching data. HEs can be incorporated into both crystalline and glassy phases, depending on the ceramic body type. Moreover, silicate ceramics exhibit a remarkably high immobilisation efficiency (often exceeding 99.9%), as accomplished for Ba, Cd, Ni, and Zn elements. The pitfalls of the inertization process include an insufficient stabilisation of incorporated HEs, as indicated by the high hazard quotients (beyond the permissible limits established for inert materials) obtained in some cases for Mo, As, Cr, Pb, and Cu elements. Such behaviour is related to oxy-anionic complexes (Mo, As, Cr) that can form their own phases or are not linked to the tetrahedral framework of aluminosilicate glass. Pb and Cu elements are preferentially partitioned to glass with a low coordination number, while As and especially Mo are not always stabilised in silicate ceramics. These drawbacks necessitate conducting additional studies to develop appropriate inertisation strategies for these elements

Viscous flow sintering of porcelain stoneware revisited

Porcelain stoneware tiles, as porcelain items, are sintered by vitrification through viscous flow of an abundant liquid phase formed at high temperatures. Such a process must be kept under strict control to achieve the desired properties of final products and prevent defects induced by pyroplasticity. This is particularly true for large tiles, where production emphasizes on requirements of uniform densification and minimal deformations at high temperatures. This contribution will critically overview the state-of-the-art of porcelain stoneware sintering and the challenges for the development of large slabs. The level of acquaintance with different phenomena involved in viscous flow sintering will be discussed, discerning what is already known, what is recognised, but still needs to be fully understood, and what could arise from in-depth comprehension. The KNOWNS: the evolution of microstructure and phase composition during firing is well known and phenomenological models have been developed for viscous flow densification of porcelain stoneware. Combined effects on pyroplasticity by liquid phase viscosity and solid load have been disclosed. The way by which Na/K ratio and other chemical keys of porcelain stoneware composition affect sintering kinetics is known. The role of mullite crystallisation/dissolution and beta-alpha quartz transition on technological properties has been recognised. The KNOWN UNKNOWNS: dynamic changes in composition and physical properties of the liquid phase during firing are envisaged, but vitrification and reactive sintering have not been modelled yet. In particular, there are uncertainties regarding the actual effect on sintering kinetics and pyroplasticity due to crystals suspended in the melt according to their variable shape and size distribution. The effect of starting porosity on densification degree and kinetics; the homogeneity and miscibility of liquid phases; gas solubility in the liquid phase at the highest firing temperatures (and its role on closed porosity and bloating); the Fe2+/Fe3+ ratio dependence on temperature and its consequence on the melt viscosity remain unclear. The UNKNOWN UNKNOWNS: modelling of densification curves and prediction of physical properties of porcelain stoneware tiles, through computational calculations, may prefigure the role of further variables not considered yet. The extension of such modelling efforts from laboratory to industrial scale may disclose the occurrence of scale effects, particularly in the case of large slabs and different shaping techniques. A better comprehension of kinetic aspects, resulting by the convolution of various factors, may unveil unexpected results, such as memory effects from raw materials or microstructural features

VITA OLEI

Il software VITA OLEI consente di stimare il termine minimo di conservazione dell’olio extra vergine di oliva sulla base di parametri compositivi del prodotto determinati mediante analisi chimiche e strumentali. Il software VITA OLEI può essere utile in particolare per produttori ed imbottigliatori di olio extra vergine di oliva allo scopo di stimarne la shelf-life. I dati, ovvero i risultati delle analisi di oli di oliva sottoposti ad uno studio di shelf-life, impiegati per la creazione del software, sono stati prodotti nell’ambito del progetto OLEUM nel task coordinato dall’Università degli Studi di Perugia. Requisiti tecnici: PC; Windows (64 bit) 7, 8, 10, 11; licenza software