Cesium dihydrogen phosphate (CsH2PO4) holds great potential as electrolyte for intermediate-temperature fuel cells and electrochemical devices due to its high proton conductivity (>= 10-2 S/cm). This study reports on the variation of the microstructure of CsH2PO4 and its effect on its electrical and thermal properties, with special attention to the low-temperature conductivity behavior. To manipulate morphology, the particle size was decreased by wet ball-milling, while variations in grain growth were achieved by cold sintering. Above the superprotonic phase transition, the electrical conductivity was effectively independent of the grain size. Nonetheless, at lower temperatures, a brick layer analysis on the impedance data revealed that the conductivity of the monoclinic phase is governed by the conduction pathways along the parallel grain boundaries due to the humidified atmosphere. Overall, we propose two conduction mechanisms that could explain the grain boundary conductivity of these samples, revealing critical links between sample morphology and low-temperature electrical behavior.

In this work, we investigated the electrical and dielectric properties of a new biocomposite-based vinyl resin emulsion reinforced with microparticles of green microcrystalline cellulose. We measured the electrical response of each sample by assessing AC electrical conductivity in the temperature range of 260–340 K and in the frequency range of 100 Hz–1 MHz. The electrical conductivity dispersion is well described by Jonscher’s power law. Accordingly, the associated mechanism conductivity is due to the correlated barrier-hopping conduction mechanism. Dielectric properties were performed using the electric modulus formalism and analyzed according to the Havriliak-Negami model. For the neat vinyl resin emulsion, the observed relaxation process is attributed to the α-relaxation. When the fillers are added to the vinyl resin emulsion, a water dipolar polarization is identified for temperatures below the glass transition temperature and a superposition of α-relaxation and an interfacial polarization, known as Maxwell–Wagner-Sillars, for temperatures above the glass transition point. The activation energies of these are determined according to the Arrhenius law. Dielectric analysis allowed for probing the reinforcement/matrix adhesion, which can control the electrical conductivity performance of the composite materials.

Phytotoxins produced by marine microalgae, such as paralytic shellfish toxins (PSTs), can accumulate in bivalve molluscs, representing a human health concern due to the life-threatening symptoms they cause. To avoid the commercialization of contaminated bivalves, monitoring programs were established in the EU. The purpose of this work is the implementation of a PST transforming enzyme—carbamoylase—in an impedimetric test for rapid simultaneous detection of several carbamate and N-sulfocarbamoyl PSTs. Carbamoylase hydrolyses carbamate and sulfocarbamoyl toxins, which may account for up to 90% of bivalve toxicity related to PSTs. Conformational changes of carbamoylase accompanying enzymatic reactions were probed by Fourier transform mid-infrared spectroscopy (FT-MIR) and electrochemical impedance spectroscopy (EIS). Furthermore, a combination of EIS with a metal electrode and a carbamoylase-based assay was employed to harness changes in the enzyme conformation and adsorption on the electrode surface during the enzymatic reaction as an analytical signal. After optimization of the working conditions, the developed impedimetric e-tongue could quantify N-sulfocarbamoyl toxins with a detection limit of 0.1 µM. The developed e-tongue allows the detection of these toxins at concentration levels observed in bivalves with PST toxicity close to the regulatory limit. The quantification of a sum of N-sulfocarbamoyl PSTs in naturally contaminated mussel extracts using the developed impedimetric e-tongue has been demonstrated.

The knowledge of the microwave dielectric properties of materials has great significance for scientific and industrial applications. The measurement of the complex permittivity, ε*=ε′−iε″, in this frequency range, can be made using the small perturbation theory. In this method, the resonance frequency and the quality factor of a cavity, with and without a sample, can be used to calculate the complex dielectric permittivity of the material. The design of a cavity resonator implies solving the Maxwell equations inside that cavity, respecting the boundary conditions.This method was applied to characterize the dielectric properties of yttrium ferrites, that were prepared by solid state reaction, and exposed to different heat treatments. Structural and morphological characterizations were also performed. A correlation between these properties is presented. The best results, in terms of energy storage at microwave frequencies, are obtained for the sample heat treated at 1400 °C, with ε´=6.4, at 2.7 GHz, and with losses tangent lower than 10–4, at 300 K.

Rigid polyurethane foams (RPUF) are mainly used as thermal insulators materials. These materials are drawing the attention of the emerging sector of the Internet of Things (IoT) due to their features such as good chemical resistance, lightweight, and tunable mechanical properties. Yet, for IoT applications, the electrical conductivity of this type of materials should be increased substantially. To address this challenge, as well as the urgency to use renewable and sustainable resources, semi-conductive RPUF were synthesized using crude lignin-based polyol (LBP) doped with multi-walled carbon nanotubes (MWCNT) and coated with PEDOT: PSS, using the dip coating technique. The ensuing semi-conductive RPUF has low density (33-34 kg/m(3)), high electrical conductivity (in the order of magnitude of 10(- 5 )S/m), and a stretchability enhancement of almost 50 % upon coating with PEDOT: PSS. Furthermore, the mechanical performance of RPUFs can be adjusted using MWCNT and fine tuning of the formulation. Lignin being an abundant natural aromatic polyol allows the partial replacement of fossil derived polyols in the production of RPUFs and its aromatic structure contributes to the thermal and mechanical stability of the ensuing foams.

The present study optimized the properties of the electropolymerized polyaniline (PANI) solid inner contact for a potentiometric chemical sensor by varying the thickness of the polymer layer. A potentiometric sensor for detecting one of the paralytic shellfish toxins, decarbamoyl saxitoxin (dcSTX), in mussel extracts was selected as a case study. The plasticized PVC membrane composition, developed in previous work for the detection of this toxin, was used. The structure and electrical properties of PANI layers of different thicknesses were studied using scanning electron microscopy and electrochemical impedance spectroscopy. The effect of PANI solid contact thickness on the characteristics of the potentiometric sensor, including sensitivity, detection limit, and selectivity to dcSTX in buffer solutions and mussel extracts, was evaluated. The formation of a water layer at the inner solid contact and PVC membrane interface was investigated using electrochemical impedance spectroscopy and a water test. PANI layer thickness 1.1 mu m was found to be optimal for solid inner contact for potentiometric sensor with PVC membrane providing highest sensitivity and selectivity.

This paper reports research on the electrical conduction mechanisms of nanofluids, formed by adding carbon nanotube (CNT) and 0.5 wt% of graphite (Gt) particles to engine oil, in the range of temperatures up to 400 K. An analysis of the dc conductivity of nanofluids versus CNT concentration and temperature, have shown a percolation threshold of 0.6 wt% and revealed the PTCR (Positive Temperature Coefficient of Resistivity) effect for temperatures below the critical value Tc approximate to 350 K and concentrations above the critical percolation threshold. The ac conductivity of all samples was fitted in the range of frequency from 100 Hz to 1 MHz using the Jonscher power law, which allows for the specification of the appropriate electrical conduction mechanism using the exponent s in that law. The electric modulus has shown two dielectric relaxations for the nanofluid-based CNT fillers; the first one at low frequency is related to interfacial polarization, while the second one at high frequency is attributed to the interaction between CNT nanoparticles and dipolar molecules of commercial oil additives. The modulus spectra were fitted using the Havriliak-Negami model.

Nanofluids generated by the addition of various fractions of multi-walled carbon nanotubes (MWCNTs) and 0.5 wt

This study presents the dielectric properties of a barium titanate–gadolinium ferrite composite material, obtained through a solid-state reaction method. The aim of this research was to create a composite material with enhanced dielectric properties compared to each individual component, and to investigate the electrical properties of the composites, using impedance spectroscopy. The structural and morphologic properties were analyzed using X-ray diffraction and scanning electron microscopy, respectively. Impedance spectroscopy measurements were performed over a wide frequency range (100–0.1 GHz) and temperature (45–170 °C) to evaluate the electrical behavior of the material. The dielectric relaxations were analyzed using the Havriliak–Negami function, and the key electrical parameters such as relaxation frequency, dielectric strength, and electrical conductivity were extracted. Several relaxation processes were identified, which depend on the mixture of the initial titanate and ferrite materials, and a correlation between structural, morphologic, and electrical properties was exposed. The sample with the highest dielectric constant was the 25 wt% gadolinium ferrite composite, with ε′ close to 240 and loss tangent values below 0.1, affording it the more appropriate composition for energy storage devices such as lead-free dielectric capacitors.

Foot ulceration and infection is associated with a substantial increase in morbidity and mortality in patients with diabetes. We present a clinical case of recurrent diabetic foot infection with an atypical clinical evolution. A 58-year-old male patient with type 1 diabetes and a history of bilateral Charcot foot neuroarthropathy was followed at our Diabetic Foot Clinic for an unhealed plantar foot ulcer for >1.5 years with recurrent episodes of infection. He was admitted to hospital due to foot ulcer reinfection with sepsis and ipsilateral lower limb cellulitis. The foot infection was found to be associated with an underlying abscess in the anterior compartment of the leg, with a cutaneous fistulous course with extensive alterations of an inflammatory nature. Exudate from the lesion was drained and tissue biopsied, revealing Serratia marcescens and Klebsiella oxytoca with dystrophic calcification (DC). Surgical excision of dystrophic tissue with debridement of the fistulous tracts was performed. The excised material corroborated the presence of fibroadipose connective tissue with marked DC, as well as areas of mixed inflammation compatible with a chronic infectious aetiology. Targeted long-term antibiotic therapy was implemented, for a total of six weeks, with a favourable clinical evolution and complete closure of the lesion at the final follow-up. DC results from calcium deposition in degenerated tissues without evidence of systemic mineral imbalance and is a potential cause of non-healing ulcers. Few cases of DC have been reported in diabetic foot patients and its treatment remains challenging and controversial. A longer follow-up period is necessary to verify the effectiveness of our approach.

Recent research in solid-state physics and materials engineering focuses on the development of new dielectric materials, with bismuth-based pyrochlores being already extensively applied in communications technology for their excellent dielectric properties and relatively low sintering temperatures. Herein, the structural, morphological, electrical, and magnetic properties of Bi1.34Fe0.66Nb1.34O6.35 ceramic, prepared by the sol–gel method and sintered at 500 °C, are investigated. The Rietveld refinement of the XRD pattern showed a cubic phase belonging to the space group Fd-3m and a crystallite size of 42 nm. Transmission electron microscopy further confirmed the crystallite size and the homogeneous distribution of Bi, Fe, Nb, and O elements, as evidenced by high-angle annular dark field imaging and STEM-EDX mapping. The morphology of the sample, assessed by scanning electron microscopy, is characterized by submicron-sized spherical particles. Dielectric spectroscopic studies revealed that the dielectric properties, strongly influenced by frequency and temperature, indicate the material’s potential for energy storage due to lower dielectric loss compared to the dielectric constant. The observed relaxation phenomena, confirmed through variations in dielectric loss and loss tangent, highlight the influence of grain boundaries and temperature on electron hopping and charge carrier dynamics. Using SQUID magnetometry, we identified two distinct magnetic phases. The primary phase, corresponding to the Bi1.34Fe0.66Nb1.34O6.35 ceramic, exhibits an antiferromagnetic behavior below its Néel temperature at around 8.8 K. A secondary high-Curie temperature ferrimagnetic phase, likely vestigial maghemite and/or magnetite, was also detected, indicating an estimated fraction below 0.02 wt.%.

In recent decades, the requirements for implantable medical devices have increased, but the risks of implant rejection still exist. These issues are primarily associated with poor osseointegration, leading to biofilm formation on the implant surface. This study focuses on addressing these issues by developing a biomaterial for implant coatings. 45S5 bioglass® has been widely used in tissue engineering due to its ability to form a hydroxyapatite layer, ensuring a strong bond between the hard tissue and the bioglass. In this context, 45S5 bioglasses®, modified by the incorporation of different amounts of copper oxide, from 0 to 8 mol%, were synthesized by the melt–quenching technique. The incorporation of Cu ions did not show a significant change in the glass structure. Since the bioglass exhibited the capacity for being polarized, thereby promoting the osseointegration effectiveness, the electrical properties of the prepared samples were studied using the impedance spectroscopy method, in the frequency range of 102–106 Hz and temperature range of 200–400 K. The effects of CuO on charge transport mobility were investigated. Additionally, the bioactivity of the modified bioglasses was evaluated through immersion tests in simulated body fluid. The results revealed the initiation of a Ca–P-rich layer formation on the surface within 24 h, indicating the potential of the bioglasses to enhance the bone regeneration process.

This work investigates the dielectric properties of barium titanate/gadolinium ferrite ceramic composites, with different concentrations of each material. Our objective was to increase the storage ability of this material, finding a compromise between high permittivity and low dielectric losses. A two-step sintering procedure was used in the preparation of the composites to attain the desired results. Their morphological, structural and electrical properties were tested using scanning electron microscopy, X-Ray powder diffraction and impedance spectroscopy, respectively. Dielectric characterizations were performed on the frequency band of 100 Hz-1 MHz and for different temperatures (180-380 K). The best compromise between barium titanate and gadolinium ferrite in the composition was calculated in order to obtain a potential material for electrical energy storage. The sample with 25% gadolinium ferrite presented the best results. The dielectric constant reached values of the order of 2000, at 1 kHz and 340 K. It was also important not to have very high losses, and this was confirmed by the calculated loss tangent.

This work presents an investigation on the optical and structural properties of two series of nanocomposites based on the incorporation of spherical- (NDs) or rod-shaped (NRs) semiconductive crystalline titanium dioxide (TiO2) nanoparticles (NPs) into an insulating amorphous polymethylmethacrylate (PMMA) matrix. The UV-visible absorbance and reflectance measurements reveal that the increase in TiO2 NP concentration within the polymer matrix reduces the forbidden band size for both NDs and NRs, leading to an improvement of the refractive index. SEM and TEM morphological characterizations were performed to investigate the size, size distribution and NPs dispersion within the polymeric matrix. The structural analyses performed by using X-ray diffraction show peaks ascribed to the TiO2 crystalline structure while infrared (FT-IR) spectra indicate the occurrence of interactions between nanofillers and the polymer chain of the host matrix.

INTRODUÇÃO: Toda profissão existe por causa do consumo ou necessidade de uma população e todas as profissões estão de certa forma interligadas em uma grande cadeia de produção, prestação de serviços e

The Food and agriculture system plays a determining role in many countries ambitions to achieve net-zero by 2050. Sector pathways consistent with this objective most frequently describe sustainable intensification as the dominant response. This narrows the option space for the agricultural sector and restricts its ability to address multiple sustainability issues simultaneously. Here we present an interactive model ARISE (AgRIculture and food SystEm interactive model) which allows stakeholders to design complementary food and agriculture sector pathways and build consensus. As a first case study, we provided an environment-oriented NGO assessment of a UK agroecology pathway and evaluate the benefits in comparison with alternative pathways available in the literature and developed by the UK Government. This shows how the ARISE model can enable the exploration of critical trade-offs between the multiple sustainability objectives.

Polymeric membranes are widely used in guided bone regeneration (GBR), particularly in dentistry. In addition, bioactive glasses can be added to the polymers in order to develop a matrix that is osteoconductive and osteoinductive, increasing cell adhesion and proliferation. The bioactive glasses allow the insertion into its network of therapeutic ions in order to add specific biological properties. The addition of zinc into bioactive glasses can promote antibacterial activity and induce the differentiation and proliferation of the bone cells. In this study, bioactive glasses containing zinc (0.25, 0.5, 1 and 2 mol%) were developed and structurally and biologically characterized. The biological results show that the Zn-containing bioactive glasses do not present significant antibacterial activity, but the addition of zinc at the highest concentration does not compromise the bioactivity and promotes the viability of Saos-2 cells. The cell culture assays in the membranes (PCL, PCL:BG and PCL:BGZn2) showed that zinc addition promotes cell viability and an increase in alkaline phosphatase (ALP) production.

Additive manufacturing (AM), also known as three-dimensional (3D) printing, allows the fabrication of complex parts, which are impossible or very expensive to produce using traditional processes. That is the case for dinnerware and artworks (stoneware, porcelain and clay-based products). After the piece is formed, the greenware is fired at high temperatures so that these pieces gain its mechanical strength and aesthetics. The conventional (gas or resistive heating elements) firing usually requires long heating cycles, presently requiring around 10 h to reach temperatures as high as 1200 °C. Searching for faster processes, 3D-printed stoneware were fired using microwave (MW) radiation. The pieces were fired within 10% of the conventional processing time. The temperature were controlled using a pyrometer and monitored using Process Temperature Control Rings (PTCRs). An error of 1.25% was calculated between the PTCR (1207 ± 15 °C) and the pyrometer (1200 °C). Microwave-fast-fired pieces show similar mechanical strength to the references and to the electrically fast-fired pieces (41, 46 and 34 (N/mm2), respectively), presenting aesthetic features closer to the reference. Total porosities of ~4%, ~5% and ~9% were determined for microwave, electrically fast-fired and reference samples. Numerical studies have shown to be essential to better understand and improve the firing process using microwave radiation. In summary, microwave heating can be employed as an alternative to stoneware conventional firing methods, not compromising the quality and features of the processed pieces, and with gains in the heating time.

The aim of this study is to establish a connection or correlation between the electrical and structural properties of ternary composites, which were prepared by adding multi-walled carbon nanotubes (MWCNT) and graphite (Gr) as conductive fillers to an insulating polyester matrix. The study utilized small-angle neutron scattering, infrared and Raman spectroscopy for structural characterization. Electrical measurements were conducted within a frequency range of 100 Hz to 1 MHz and a temperature range of 200–380 K. The alternating current (AC) conductivity showed a frequency dependence following Jonscher’s power law. The temperature dependence of the AC conductivity suggested that the electrical conduction within the material is a thermally activated process. The temperature-dependent behavior of the direct current (DC) conductivity suggests that below and above the critical temperature, there is a pronounced positive and negative temperature coefficient of resistivity, respectively. In comparison to MWCNT/polyester or Gr/polyester composites, the percolation threshold of the MWCNT/Gr/polyester composite is much lower. Additionally, applying the Arrhenius equation to analyze the temperature dependence of DC conductivity reveals that the inclusion of MWCNT and Gr in the polyester matrix results in a decrease in activation energy.

The evolution of porcelain closed porosity during microwave and electric fast-firing is investigated and compared with that of conventionally gas-fired porcelain (taken as reference). Samples were fired in less than 70 min and are considered to be fast-fired as their processing takes less than one-half of the conventional heating time (similar to 210 min). The closed porosity relationship with the porcelain functional properties explains some of the observed differences between microwave and electrically fired porcelain. Electrically-fired samples at 1100 degrees C present a microstructure like that of the biscuit reference, fired at similar to 1000 degrees C in 460 min, whereas microwave-fired samples already show some vitrification at this temperature. The samples microwave fired between 1300 degrees C and 1380 degrees C, in 70 min, present a microstructure similar to that of reference samples fired at 1380 degrees C in 210 min. Electric fast-firing requires similar to 80 degrees C higher firing temperatures (between 1350 degrees C and 1380 degrees C than microwave fast-firing to reach similar features. Both electrically and microwave fast-fired porcelain show similar microstructure evolutions and densifications (similar to 95% of the real density, equal to 2.57 g.cm(-3)), the microwave-fired samples presenting a more developed microstructure state for the same firing temperature.