Towards the fabrication of sintered IDEAL-Cells by tape casting, wet powders spraying and screen printing

The realization of complete anode supported cells reproducing the IDEAL-Cell concept was approached by standard and inexpensive ceramic processes like tape casting, screen printing and wet powder spraying. Both commercial and custom powders were employed to build-up layers for button cells (1 inch footprint) and larger (5?5 cm2) substrates. This paper reports the details of the slurries formulation as well as the deposition parameters and sintering conditions. Resulting microstructural features are also presented together with an outlook on future steps of the activit

<i>Ex vivo</i> cutaneous penetration of econazole nitrate from SLN incorporated in hydrophilic gels

Solid lipid nanoparticles (SLN) are considered as innovative drug carrier for topical application. The small size of the lipid particles ensures close contact to the stratum corneum and can increase the amount of the drug penetrating into the skin and it allows controlled drug release. The aim of this study was to develop controlled release gels containing SLN dispersions loaded with Econazole Nitrate (ECN) and to evaluate ex vivo skin penetration of the drug released from the particles

B-site vacancy induced Raman scattering in BaTiO3-based ferroelectric ceramics

Defects, in particular vacancies, play a crucial role in substituted perovskite systems, influencing the structural features that underpin ferroelectricity. B-site vacancies introduce cation disorder in the perovskite lattice and are in fact one of the main driving forces for relaxor behaviour in barium titanate (BaTiO3, BT) based ferroelectrics. In this work, material systems are carefully selected to qualitatively study the change in B-site vacancy concentration for heterovalent substituted BT-based ferroelectric polycrystals. Raman spectroscopy was used to investigate those systems, and B-site vacancy specific Raman modes were identified unambiguously by comparison with charge-compensated BT, where B-site vacancies are absent. This study validates the hypothesis that vacancies induce Raman scattering because of symmetry breaking in the BT lattice, establishing this method as a vital tool to study substitutional defects in ceramic materials

Dual cells with mixed protonic-anionic conductivity for reversible SOFC/SOEC operation

International audienceThe dual cell concept is a novel design for solid oxide fuel cells operating at intermediate temperature. The cell comprises a series of five layers with different compositions, alternating two dense electrolytes and three porous layers, i.e. the outer electrodes and a central membrane. The dual cell concept makes it possible to separate the compartment for water formation from both fuel and oxidant chambers. Such a three-chamber configuration gives many advantages related to fuel dilution, materials corrosion, and reversibility between fuel cell and electrolyser operational modes (SOFC/SOEC) at high temperature. Dual conductivity (protonic/anionic) can be achieved by joining two dense BaCe0.85Y0.15O3-δ (BCY) and Ce0.85Y0.15O2-δ (YDC) electrolytes through a porous ceramic central membrane made up of both materials. Complete anode-supported dual cells have been fabricated by a combination of pressing, casting, printing, wet spraying, and plasma spraying techniques. Electrochemical tests carried out by impedance spectroscopy showed the feasibility of the concept and successful reversible operation of the dual cell. The fabrication route, the microstructural and electrochemical testing results are reported in this work, and partially compared to simulated results from an electrochemical model developed describing the dual cell concept

Fluoride uptake and translocation in food crops grown in fluoride-rich soils.

This research article published by John Wiley & Sons, Inc., 2020BACKGROUND The East African Rift Valley (EARV) area is characterized by an intense volcanic activity, which largely influences the nature of soils, ground and surface waters causing a transfer of fluoride from volcanic emissions to the environment. Field experiments were conducted in F‐contaminated areas of Ngarenanyuki (Arumeru district) in North Tanzania. In order to evaluate the potential fluoride exposure from the diet and the related health risk for the local population, the content of fluoride in soil and plant tissues was assessed, focusing on the edible portions (leaves, fruits or seeds) of the main cultivated and consumed food crops in the area. RESULTS Average fluoride contents of 8.0, 11.4, 11.3 and 14.2 mg kg−1 of dry matter were observed respectively for maize (Zea mays L.), tomato (Lycopersicon esculentum Mill.), bean (Phaseolus vulgaris L.) and kale (Brassica sp. pl .) edible parts. The cumulative estimated average daily dose (EADD) ranged from 0.026 to 0.165 mg F d−1 kg−1 among different rural population groups and considering two different hypotheses of absorption fraction (75% or 100%), i.e. the amount of fluoride that is absorbed during the digestion process. The associated hazard index (HI) values varied from 0.43 to 2.75. CONCLUSIONS Considering the dietary habits of the local population, the outcomes of the present study suggest that the investigated crops can substantially contribute to fluoride related diseases, especially in earlier ages

Energy Harvesting Potential of Polymer Composites

Energy is available all around us in different forms and shapes such as from sun, wind, waves, vibrations etc. The enormous amount of mechanical energy released in everyday life by human walking, transportation movement, sound waves and other, represent renewable and safe energy source. Piezoelectric generators exhibit a great potential for powering up low-power portable devices and self-powered electronic systems by extraction of mechanical energy. Employment of lead-free piezoelectric materials will be a breakthrough of a completely new type of safe and harmless production of energy for daily life. Recent challenge in electronics is also utilization of flexible electronics with the ability to bend into diverse shapes which expands the applications of modern electronic devices in different areas.Polymer PVDF/piezoelectric ceramics, flexible composite films were prepared by hot pressing method. The influence of hot pressing method on the formation of electroactive PVDF phases in the polymer was proven by FTIR analysis. DSC analysis have shown the change of PVDF crystallinity degree in the flexible films with addition of ceramics filler particles. The dielectric permittivity value increased with the addition of filler in the polymer matrix while the relaxation processes were governed mostly by the PVDF matrix. Polarization of flexible films enhanced the formation of PVDF electroactive β- phase in the samples. Energy harvesting potential was studied by measuring of voltage output under the impulse hammer load

Flexible composite films with enhanced piezoelectric properties for energy harvesting and wireless ultrasound-powered technology

In the last years, ultrasound energy harvesting has emerged as the most promising technique for wireless power supply of implanted medical devices. These devices require flexible piezoelectric materials with high piezoelectric response in the ultrasonic range. Here we report on bio-compatible NBT-BT/PVDF flexible composites, with variable filler content up to 50 vol%, prepared by a properly designed and optimized process, which incorporates in a complex connectivity pattern fully sintered NBT-BT crystalline powders in a PVDF matrix. The dielectric constant of the flexible composites increased from 10 of pure PVDF polymer to 110 of composite films with 50 vol% NBT-BT content, while the high frequency piezoelectric d33 constant increased from 0.2 pC/N to 33 pC/N for the same samples. The composite with 50 vol% NBT-BT exhibits the figure of merit for the harvested ultrasound energy d33g33 ≅ 1.54 × 10−12 m3/J, which is comparable to the figure of merit for the NBT-BT piezoelectric ceramic (1.8 × 10−12 m3/J) and higher than other reported results for random composites. Based on these results, this study provides an easy method to fabricate random flexible piezoelectric composites with enhanced high frequency piezoelectric response and high energy density harvested from an ultrasound source

Advantages and limitations of active phase silanization in PVDF composites: Focus on electrical properties and energy harvesting potential

In order to further improve the performance of 0.94[(Bi0.5Na0.5)TiO3]-0.06BaTiO3/ polyvinylidene fluoride (NBT-BT/PVDF) flexible composite films prepared by the hot-pressing method, the effect of surface modification of the NBT-BT particles on the structure and properties of the films was investigated. Two coupling agents, namely, (3-aminopropyl)triethoxysilane (APTES) and dodecyl triethoxysilane (DDTES) were added to enhance dispersion and interfacial adhesion of the active phase powder with the polymer matrix. The highest amount of the electroactive PVDF β-phase was formed in APTES-modified samples while in DDTES samples mainly γ-phase was formed as shown by Fourier-transform infrared spectroscopy analysis. Differential scanning calorimetry measurements indicated that the addition of filler particles reduced the total crystallinity degree of the PVDF. Dielectric permittivity values as well as dielectric losses decreased for silanized samples due to reduced tension at the interface between particles and polymer. Strong intermolecular interaction between the PVDF chains and the APTES-modified particles led to enhanced breakdown strength of these samples. The highest level of agglomeration in the DDTES-modified samples induced the deterioration of ferroelectric properties. The highest voltage output of 15 V and 225 μW of powerwas obtained for the APTES-modified harvester, evidencing their potential for energy harvesting applications

ENHANCED PROPERTIES OF PVDF COMPOSITES BY ACTIVE PHASE SILANIZATION

0.94[(Bi0.5Na0.5)TiO3]-0.06BaTiO3/polyvinylidene fluoride flexible composite films were prepared by the hot-pressing method. Surface modification of active phase particles was performed using two coupling agents, namely, (3- aminopropyl)triethoxysilane (APTES) and dodecyl triethoxysilane (DDTES) to enable good adhesion of active phase particles with the polymer matrix. The highest amount of electroactive PVDF β- phase was formed in APTES-modified samples while in DDTES samples mainly γ- phase was formed. Dielectric permittivity values and dielectric losses decreased for silanized samples due to reduced tension at the interface between particles and polymer. Strong intermolecular interaction between the PVDF chains and the APTES-modified particles led to enhanced breakdown strength of these samples. After the polarization of films, energy harvesting potential was evaluated for all samples. The highest voltage output of ~ 15 V and power ~ 225 μW were obtained for a single APTES-modified harvester [1-2]

Su alcuni reperti umani del paleolitico superiore di grotta Paglicci nel Gargano (Foggia): analisi paleobiologiche

L’interesse del presente elaborato si fonda sulla descrizione e analisi comparativa di una serie di reperti scheletrici provenienti dal giacimento del Paleolitico superiore di Grotta Paglicci (Rignano Garganico, Foggia).La località assunse già dal Paleolitico inferiore-medio (nel riparo) antistante la grotta una posizione importante.Si tratta di una serie fortunata di circostanze che permise all’umanità paleolitica di frequentare per millenni il sito, testimoniato appunto dalla complessa stratigrafia che nel tempo si è dimostrata alla ricerca archeologica ricca di reperti ossei umani e animali e di un’industria litica che va almeno nel Paleolitico superiore dall’Aurignaziano all’Epigravettiano. Ogni elemento osseo umano sono stati misurati seguendo, quando l’elemento permetteva in un certo qual modo il rilievo, la metodologia di Martin e Saller (1956). Per gli elementi dentari è stata seguita amcora ancora questa metodologia in più quella di Dahlberg, (1956) presa in considerazione in un’opera mirata al solo studio dei denti. Ci si è limitati alle sole misurazione proprio perché la maggior parte dei resti sono di soggetti infantili il cui reperimento è sempre molto limitato in questi antichi periodi della “storia” umana.Per ogni elemento, e qui più che altro è stato utilizzato l’elemento dentario, dato che le ossa in genere, infantili o di adulto che siano sono troppo frammnetarie perché valga la pena di passare ad un confronto con altri elementi di siti differnti, vengono presi in considerazione i relativi dati (caratteri metrici s’intende) e confrontati con gli omologhi sincroni e diacronici, omo e eterotopic