A novel ceramic matrix composite based on YNbO4–TiO2 for microwave applications

This work presents the dielectric properties of YNbO₄ (YNO)–TiO₂ composites in the microwave range. X-ray diffraction analysis demonstrates that the addition of TiO₂ to YNO results in the formation of a Y(Nb_0.5Ti_0.5)₂O₆ phase. In the microwave range, the values of permittivity and dielectric loss did not present major changes with the increment of TiO₂. Moreover, the addition of TiO₂ results in an improvement in the thermal stability of YNO, with YNO63 demonstrating a resonant frequency of ?8.96 ppm.°C^?1. We utilised numerical simulations to evaluate the behaviour of these materials as dielectric resonator antennae and it is found that they exhibit a reflection coefficient below ?10 dB at the resonant frequency, with a realised gain of 4.94 – 5.76 dBi, a bandwidth of 665–1050 MHz and a radiation efficiency above 84%. Our results indicate that YNO–TiO₂ composites are interesting candidates for microwave operating devices.     

Current advances concerning the most cited metal ions doped bioceramics and silicate-based bioactive glasses for bone tissue engineering

Studies related to biomaterials that stimulate the repair of living tissue have increased considerably, improving the quality of many people's lives that require surgery due to traumatic accidents, bone diseases, bone defects, and reconstructions. Among these biomaterials, bioceramics and bioactive glasses (BGs) have proved to be suitable for coating materials, cement, scaffolds, and nanoparticles, once they present good biocompatibility and degradability, able to generate osteoconduction on the surrounding tissue. However, the role of biomaterials in hard tissue engineering is not restricted to a structural replacement or for guiding tissue regeneration. Nowadays, it is expected that biomaterials develop a multifunctional role when implanted, orchestrating the process of tissue regeneration and providing to the body the capacity to heal itself. In this way, the incorporation of specific metal ions in bioceramics and BGs structure, including magnesium, silver, strontium, lithium, copper, iron, zinc, cobalt, and manganese are currently receiving enhanced interest as biomaterials for biomedical applications. When an ion is incorporated into the bioceramic structure, a new category of material is created, which has several unique properties that overcome the disadvantages of primitive material and favors its use in different biomedical applications. The doping can enhance handling properties, angiogenic and osteogenic performance, and antimicrobial activity. Therefore, this review aims to summarize the effect of selected metal ion dopants into bioceramics and silicate-based BGs in bone tissue engineering. Furthermore, new applications for doped bioceramics and BGs are highlighted, including cancer treatment and drug delivery.     

Foliar Spraying of Silicon Associated with Salicylic Acid Increases Silicon Absorption and Peanut Growth

Silicon - Silicon (Si) combined with foliar spraying of salicylic acid (SA) can affect the absorption of this beneficial element. A study with Si non-accumulators plants (soybean and bean) observed...     

Thermoset IM-LSI-based C/C-SiC: Influence of flow direction and weld lines on microstructure and mechanical properties

The production of ceramic matrix composites (CMC) based on C/C-SiC is still very cost-intensive and therefore only economical for a few applications. The fabrication of the preforms involves many costs that need to be reduced. In this work, the shaping of the CFRP-preforms is realized by thermoset injection molding, which enables large-scale production. The polymeric matrix used is a multi-component matrix consisting of novolak resin, curing agent and lubricant. Six millimeter chopped carbon fiber with a proportion of 50 wt.% were used as a reinforcement. These ingredients are processed by an industrial equipment for compounding and injection molding in order to manufacture a CFRP demonstrator representing a brake disc. Test specimens are cut out of the demonstrator in different directions in order to investigate influences of flow direction and weld lines on microstructural and mechanical properties. Afterward, the CFRP samples were converted to C/C-SiC composites by the liquid silicon infiltration process. The article addresses the flow behavior of the compound during the injection molding and the building of the weld lines in the demonstrator. In addition, results of the directional dependence of the microstructural and mechanical properties within the fabricated disc in the different production steps are presented.     

Plasmonic-excitonic multi-hybrid glass-based nanocomposites incorporating Ag plus core-shell CdSe/CdS and alloyed CdSxSe1−x nanoparticles

Successful fabrication of glass-based hybrid nanocomposites (GHNCs) incorporating Ag, core-shell CdSe/CdS and CdS_xSe_1?x nanoparticles (NPs) is herein reported. Both metallic (Ag) and semiconductor (CdSe/CdS) NPs were pre-synthesized, suspended in colloids and added into the sol-gel reaction medium which was used to fabricate the GHNCs. During fabrication of the nanocomposites a fraction (20–60%) of core-shell CdSe/CdS NPs was alloyed into CdS_xSe_1?x (0.20 < x < 0.35) NPs without changing morphology. Modulation of in situ alloying is possible via the relative content of organics added into the sol-gel protocol. Within colloids Ag (core-shell CdSe/CdS) NPs presented average diameter and polydispersity index of 49.5 nm (4.2 nm) and 0.41 (0.21), respectively. On the other hand, the Ag (core-shell CdSe/CdS) NPs’ average diameter and polydispersity index assessed from the GHNCs were respectively 51.5 nm (4.1 nm) and 0.43 (0.25), revealing negligible aggregation of the nanophases within the glass template. The new GHNCs herein introduced presented two independent excitonic transitions associated to homogenously dispersed semiconductor NPs, peaking around 420 nm (core-shell CdSe/CdS) and 650 nm (CdS_xSe_1?x) and matching the plasmonic resonance (Ag NPs) in the 400–500 nm range. We envisage that the new GHNCs represent very promising candidates for superior light manipulation while illuminated with multiple laser beams in quantum interference-based devices.     

Compliant activity rather than difficulty accelerates thought probe responsiveness and inhibits deliberate mind wandering

ABSTRACT

Mind wandering is a commonly intruding cognitive state that leads to diminished performance and increased error risk during a primary task. A controversy over whether easier or more difficult tasks increase mind wandering has led to mind wandering being proposed as two different states: deliberate and spontaneous. We hypothesise that forced engagement via persistent compliant activity may both increase responsiveness and inhibit non-instrumental activities including deliberate mind wandering. Twenty-eight healthy adults interacted with 2 pairs of stimuli, each pair having one low-interactivity version and a high-interactivity version requiring compliant activity. Mind wandering was assessed by thought probes, and subjective responses were rated using visual analogue scales. Reaction times were measured using Superlab. Compliant activity decreased the prevalence of deliberate mind wandering episodes but not of overall mind wandering. Thought probe durations were accelerated significantly by compliant activity, near-significantly by thinking on-task thoughts, and additively by the combination of both. Deliberate and spontaneous mind wandering elicited equivalent thought probe durations. We conclude that compliant activity works synergistically with lack of mind wandering to accelerate the difficult task of thought probe response but not simple reaction times. These results fit with an arousal model but not the attentional resources model.     

A feasibility study of Lactobacillus plantarum in fruit powders after processing and storage

The aim of this study was to develop fruit powders (apple, banana and strawberry) enriched with a probiotic strain (Lactobacillus plantarum 299v). Two methodologies were proposed: (i) drying of the fruit with probiotic culture incorporated (by convection) or (ii) drying of fruit (by convection) and addition of spray‐dried probiotic culture. In the first methodology, processing caused a notable reduction in probiotic viable counts in apple, but this reduction was lower during drying of banana and strawberry. A large reduction in viable cells was also recorded during storage. In the second methodology, the survival of L. plantarum 299v was considerably higher during spray‐drying, and fruit powders with a microbial content suitable for a probiotic food (10⁸–10⁹ cfu g^?1) were obtained. The fruit powders incorporating L. plantarum 299v can be stored at 4 °C or at room temperature, for at least 3 months. This preliminary study demonstrated that fruit powders are good carriers of probiotic cultures, but the techniques used to produce them should be carefully considered.