Structure Evolution of Ge-Doped CaTiO3 (CTG) at High Pressure: Search for the First 2:4 Locked-Tilt Perovskite by Synchrotron X-ray Diffraction and DFT Calculations.

This research investigates the high-pressure behavior of the Ca(Ti0.95Ge0.05)O3 perovskite, a candidate of the locked-tilt perovskite family (orthorhombic compounds characterized by the absence of changes in the octahedral tilt and volume reduction under pressure controlled solely by isotropic compression). The study combines experimental high-pressure synchrotron diffraction data with density functional theory (DFT) calculations, complemented by the X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), to understand the structural evolution of the perovskite under pressure. The results show that CTG undergoes nearly isotropic compression with the same compressibility along all three unit-cell axes (i.e., Ka0 = Kb0 = Kc0, giving a normalized cell distortion factor with pressure dnorm(P) = 1). However, a modest increase in octahedral tilting with pressure is revealed by DFT calculations, qualifying CTG as a new type of GdFeO3-type perovskite that exhibits both isotropic compression and nonlocked tilting. This finding complements two existing types: perovskites with anisotropic compression and tilting changes and those with isotropic compression and locked tilting. The multimethod approach provides valuable insights into the structural evolution of locked-tilt perovskites under high pressure and establishes a protocol for the efficient study of complex high-pressure systems. The results have implications for the design of new functional materials with desirable properties.

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.

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.

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.

DRESS: relato de caso com estudo genético / DRESS syndrome: case report with genetic testin

A síndrome de hipersensibilidade a drogas com eosinofilia e sintomas sistêmicos (DRESS) é uma rara reação adversa a drogas com potencial de morte e sequelas em longo prazo. Os anticonvulsivantes aromáticos estão entre os medicamentos mais relacionados. Relatamos um caso de DRESS em associação com o alelo HLA-A*31:01, destacando aspectos clínico-laboratoriais, abordagem diagnóstica e acompanhamento ambulatorial de sequelas tardias. Homem com 69 anos, natural do Japão, internado com suspeita clínica de DRESS. Havia iniciado carbamazepina 4 semanas antes do rash cutâneo para tratamento de epilepsia. Apresentou biópsia cutânea compatível com farmacodermia. O paciente foi tratado com prednisolona por 4 meses. A tipagem HLA-A-B-DRB1 por PCR-RSSO (ONE LAMBDA) e SSP alelo específico revelou HLA relacionado a reações de hipersensibilidade à carbamazepina. O teste de contato realizado com carbamazepina a 10% no primeiro ano após a reação foi positivo. A restrição futura da classe de anticonvulsivantes aromáticos foi recomendada. Oito meses após a aparente resolução clínica da DRESS, o paciente desenvolveu aumento dos anticorpos antitireoideanos e doença de Hashimoto. Treze meses após a o início da reação, foi observado aumento nos títulos de FAN, sem manifestações clínicas. Este relato de caso descreve aspectos clínico-laboratoriais típicos de DRESS relativos ao diagnóstico clínico-laboratorial e histopatológico, bem como evolução clínica em curto e longo prazos. A abordagem farmacogenética e o teste de contato foram importantes para a confirmação da imputabilidade da carbamazepina na etiologia da DRESS.

Drug reaction with eosinophilia and systemic symptoms (DRESS syndrome) is a rare, potentially fatal adverse reaction to drugs that may have long-term sequelae. Aromatic anticonvulsants are among the drugs most commonly associated with DRESS. We report a case of DRESS associated with allele HLA-A*31:01, with emphasis on clinical and laboratory findings, the diagnostic approach adopted, and outpatient follow-up of late sequelae. A 69-year old Japanese male patient was admitted with a clinical suspicion of DRESS. He had started carbamazepine treatment for epilepsy 4 weeks before the rash. He presented skin biopsy compatible with pharmacodermia. The patient was treated with prednisolone for 4 months. HLA-A-B-DRB1 typing using the PCRRSSO technique (ONE LAMBDA) and specific SSP allele revealed HLA related to hypersensitivity reactions to carbamazepine. The skin test performed with carbamazepine 10% on the first day after the reaction resulted positive. Future restriction of aromatic anticonvulsants was recommended. Eight months after the apparent clinical resolution of DRESS, the patient showed increased levels of antithyroid antibodies and Hashimoto disease. Thirteen months after the onset of the reaction, increased FAN results were observed, with no clinical manifestations. This case report describes clinical and laboratory aspects of DRESS related to clinical, laboratory, and histopathological diagnosis, as well as clinical evolution in the short and long terms. The pharmacogenetic approach and the skin test were important to confirm the imputability of carbamazepine in the etiology of DRESS.