Electron-microscopic observation of BaTiO3 prepared by additive assisted aqueous synthesis

Bulk barium titanate (BaTiO3) has found widespread applications especially in multi-layered ceramic capacitors (MLCCs) and embedded decoupling capacitors (EDC). In the last years, the interest in one-dimensional (1D) nanostructured ferroelectric systems (nanotubes, nanowires, nanorods, nanobelts, nanofibers) is increasing. Recently theoretical studies reported an enhancement of ferroelectricity in 1D systems. Although the hydrothermal and aqueous synthesis of equiaxed barium titanate powders have been thoroughly investigated the growth of barium titanate anisotropic nanoparticles still less known. Indeed it is particularly dificult to modify the crystal habit by hydrothermal and related methods. However it is expected that the presence of some additives during the synthesis will change the growth kinetic

Electron spin resonance investigation of Mn^{2+} ions and their dynamics in manganese doped SrTiO_3

Using electron spin resonance, lattice position and dynamic properties of Mn2+ ions were studied in 0.5 and 2 % manganese doped SrTiO3 ceramics prepared by conventional mixed oxide method. The measurements showed that Mn2+ ions substitute preferably up to 97 % for Sr if the ceramics is prepared with a deficit of Sr ions. Motional narrowing of the Mn2+ ESR spectrum was observed when temperature increases from 120 K to 240-250 K that was explained as a manifestation of off-center position of this ion at the Sr site. From the analysis of the ESR spectra the activation energy Ea = 86 mV and frequency factor 1/?0 ? (2-10)x10^(-14) 1/s for jumping of the impurity between symmetrical off-center positions were determined. Both values are in agreement with those derived previously from dielectric relaxation. This proves the origin of dielectric anomalies in SrTiO3:Mn as those produced by the reorientation dynamics of Mn2+ dipoles.Comment: 16 pages, 6 figure

FACE GROSSEIRA, HIPOTONIA E REGRESSÃO DO NEURODESENVOLVIMENTO

Inborn errors of metabolism are a heterogeneous class of multisystemic diseases which, although individually rare, are collectively quite common. Central nervous system is usually affected. The authors report the case of a five-month-old girl, daughter of non-consanguineous parents, born after an unremarkable full-term pregnancy and delivery. Hypotonia and neurodevelopmental regression were noted from the age of five months, along with progressive onset of facial dysmorphism, hepatomegaly, seizures, and dilated cardiomyopathy. Gangliosidosis type 1 diagnosis was confirmed by biochemical, enzymatic, and genetic findings. This report enhances the relevance of multidisciplinary approach and follow-up.Os erros hereditários do metabolismo são um grupo de doenças heterogéneas e multissistémicas. Apesar de cada doença individualmente ser rara, no seu conjunto são relativamente comuns. O sistema nervoso central é habitualmente afetado. Os autores apresentam o caso de uma lactente de cinco meses de idade, filha de pais não consanguíneos, nascida de uma gravidez de termo e parto sem intercorrências. Aos cinco meses, iniciou um quadro de hipotonia e regressão do desenvolvimento, apresentando ao longo do tempo dismorfismo facial, hepatomegália, convulsões e cardiomiopatia dilatada. O diagnóstico de Gangliosidose tipo 1 foi confirmado por achados bioquímicos, enzimáticos e genéticos. Este caso clínico reforça a relevância de uma abordagem e seguimento multidisciplinares.info:eu-repo/semantics/publishedVersio

Identificação prática de giberela em cevada.

Esta publicação tem, como objetivos, reunir informações teóricas básicas sobre giberela em cevada (Hordeum vulgare), descrever os sintomas da doença, em distintos estádios de desenvolvimento da espiga, e os sinais do patógeno, além de disponibilizar imagens da doença, de fácil reconhecimento, proporcionando suporte para que produtores, agentes da assistência técnica, estudantes e público em geral possam identificá-la.ODS 2

World state of quality: a frontier approach to benchmark the performance of countries worldwide

Purpose - The World State of Quality (WSQ) Project aims to evaluate, analyse, rank and categorise countries according to their performance in quality as a multidimensional concept. The Project involves the computation of an overall score for each country, obtained as a weighted average of ranking positions of 16 metrics, with weights determined by a panel of experts. Methodology-This work proposes an alternative strategy for that procedure, using a Benefit-of-the-Doubt (BoD) Composite Indicator approach under the framework of Data Envelopment Analysis (DEA). This strategy avoids the need of using subjective weights and normalising data by rank positions, using a more objective procedure to obtain the countries’ ranking. A new overall score of the World State of Quality is proposed, which allows the categorisation of countries’ performance. The novel insights resulting from the use of this methodology are discussed, including the identification of strengths and weaknesses of the various countries, and the peers that can be used for facilitating continuous improvements policies. Findings - The results show that the BoD approach and the original method used by the WSQ Project present comparable results. Countries’ strengths and weaknesses and their suitable peers and targets for benchmarking are presented with illustrative examples. Originality/value – A novel frontier approach for countries’ benchmarking regarding their performance in quality is proposed, incorporating new insights into the current method.FCT - Fundação para a Ciência e a Tecnologia(2021.05244)The authors acknowledge the financial support provided by FCT- Fundação para a Ciência e a Tecnologia (Portuguese National Funding Agency for Science, Research and Technology) through PhD research grants and SFRH/BD/131285/2017. This work has been supported by FCT – Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020

Two Displacive Ferroelectric Phase Transitions in Multiferroic Quadruple Perovskite BiMn7O12BiMn_{7}O_{12}

We report on the microwave, terahertz (THz), infrared and Raman spectroscopic studies of $BiMn_{7}O_{12}$ ceramics, shedding more light into the nature of two structural phase transitions and their possible relation with ferroelectricity in this compound. We observed a softening of one polar phonon in the THz range on cooling towards 460 and 300 K, i.e., temperatures at which $BiMn_{7}O_{12}$ undergoes subsequent structural phase transitions from monoclinic $\textit{I2/m}$ to polar monoclinic $\textit{Im}$ and triclinic $\textit{P1}$ phases. The soft phonon causes dielectric anomalies typical for displacive ferroelectric phase transitions. Microwave measurements performed at 5.8 GHz up to 400 K qualitatively confirmed not only the dielectric anomaly at 300 K, but also revealed two other weak dielectric anomalies near the magnetic phase transitions at 60 K and 28 K. This evidences the multiferroic nature of the low-temperature phases, although the relatively high conductivity in the kHz and Hz spectral range prevented us from directly measuring the permittivity and ferroelectric polarization. Some Raman modes sense the magnetic phase transitions occurring near 60 and 25 K, showing that spin-phonon coupling is relevant in this compound and in this temperature range. The deviation of the Mn-O stretching mode frequency from the anharmonic temperature behavior was successfully explained by the spin correlation function calculated from the magnetic contribution to the specific heat