Crystal structure and electrical properties of textured Ba2Bi4Ti5O18 ceramics

Highly textured Ba2Bi4Ti5O18 ceramic was prepared by spark plasma sintering (SPS). X-ray diffraction of the ceramics revealed the coexistence of a major ferroelectric phase (Space group, SG: B2cb) and a minor paraelectric phase (SG: I4/mmm) at room temperature. A diffused phase transition was observed at around 240 °C. The evolution of the switching current peaks in the electric current vs. electric field (I-E) loops with increasing temperature was interpreted by the structural changes and temperature dependent polarisation reversal processes. The slim polarisation vs. electric field (P-E) loops, the extra switching current peaks in the I-E loops and the non-zero piezoelectric d33 coefficient indicate that Ba2Bi4Ti5O18 is a relaxor ferroelectric material. The recoverable energy density (0.41 ± 0.01 J/cm3) of Ba2Bi4Ti5O18 ceramics in the perpendicular direction to the SPS pressing direction is close to that of Pb(Mg1/3Nb2/3)O3-based ceramics. The obtained results suggest Ba2Bi4Ti5O18 ceramics might be promising for energy storage applications

Development of High-performance Carbon and Phosphorus Anode Materials for Sodium-ion Batteries

Abstract Lithium-ion batteries, as dominant power sources for prevailing consumer electronics and electric vehicles, have been plagued by limited lithium resources with the soaring prices. Sodium-ion batteries, benefitted from ubiquitous and inexpensive sodium resources without toxicity and pollution, have emerged as promising alternatives for large-scale applications. Considering their kinetic challenges and disadvantageous energy densities, it is urgently necessary to pursue high-performance electrode materials to remedy these intrinsic defects. For anode materials, the primary choices of sodium metal and graphite are correspondingly denied for safety issues and intercalation incapability. Therefore, the objective for this doctoral work is to develop high-performance anode materials with large reversible capacities, long cycle life, high rate capabilities, and environmental friendliness. Carbon anode materials with the high electrochemical durability and physical/chemical stability have been chosen as objects in the first part. Additionally, phosphorus anode materials with a highest theoretical specific capacity and a desirable operating voltage range have been selected as objects in the second part. Firstly, carbon-based materials with optimized porosities and functionalities have been introduced into an ether-based electrolyte. A novel synergistic mechanism, incorporating the sodium ion insertion into disordered structure with the solvated sodium ions co-intercalation into graphitic structure, has been utilized to boost the sodium storage capabilities of porous carbon blacks. Simultaneously, the controlled emergence of a robust SEI thin film in ether-based electrolyte could maintain the fragile porous structure and further facilitate the sodium ions/solvated sodium ion compounds migrations. Furthermore, the desirable microporosity and the oxygenated functionalities could provide more active sites for sodium storage. Secondly, the effects of storage conditions and binders on electrochemical performances of P/C electrodes have been investigated. Initially, the formation and accumulation of phosphate compounds was identified for P/C electrodes. Even though the cycle stability of an aged electrode would be improved by an oxidation layer toward the smaller volume changes, the formation of these insulating compounds would sacrifice the reversible capacity and rate capability. Surprisingly, the utilization of different binders would determine the oxidation degrees of P/C electrodes. Their electrochemical properties have positive relationship with oxidation of active phosphorus for electrodes using different binders

Tailoring the interfaces of silicon/carbon nanotube for high rate lithium-ion battery anodes

Abstract(#br)Micrometer-sized silicon powders, due to its high specific capacity, easy accessibility, and low cost, have been regarded as an attractive anode material for lithium-ion batteries. The severer mechanical instability and high inter-particle resistance during cycling, however, hinder its further application. In this work, a novel potholed micrometer-sized silicon powders (PMSi)/carbon nanotubes (CNT)/C electrode is proposed. The resulting three-dimensional (3D) conductive framework and multi-point contact network exhibit ideal structural stability and high-rate cycling property. Hence, the volume resistivity of PMSi/CNT/C (157 Ω m) is reduced significantly relative to traditional PMSi/commercial carbon nanotubes (CCT)/C composite (400 Ω m). By testing the fabricated half-cell LIB with the PMSi/CNT/C composite anode, high reversible specific capacity of 2533 mAh g −1 with a remarkable high initial coulombic efficiency of 89.07% and over 840 mA h g −1 for 1000 cycles at 2 A g −1 is measured. Even at the rate of 20 A g −1 , the PMSi/CNT/C electrode shows a capacity of 463 mAh g −1 . A full cell contained the PMSi/CNT/C anode and a LiFePO 4 /LiMn 2 O 4 cathode successfully ignites an LED array (∼1.5W), further demonstrating its outstanding electrical driving property

Magnetic Iron Oxide Nanoparticles: Synthesis and Surface Functionalization Strategies

Surface functionalized magnetic iron oxide nanoparticles (NPs) are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis. This review focuses on the recent development and various strategies in preparation, structure, and magnetic properties of naked and surface functionalized iron oxide NPs and their corresponding application briefly. In order to implement the practical application, the particles must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of iron oxide NPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The problems and major challenges, along with the directions for the synthesis and surface functionalization of iron oxide NPs, are considered. Finally, some future trends and prospective in these research areas are also discussed

One-Dimensional-Like Titania/4′-Pentyl-4-Biphenylcarbonitrile Composite Synthesized Under Magnetic Field and its Structure–Photocatalytic Activity Relationship

The demonstration of the structure–properties relationship of shape-dependent photocatalysts remains a challenge today. Herein, one-dimensional (1-D)-like titania (TiO2), as a model photocatalyst, has been synthesized under a strong magnetic field in the presence of a magnetically responsive liquid crystal as the structure-aligning agent to demonstrate the relationship between a well-aligned structure and its photocatalytic properties. The importance of the 1-D-like TiO2 and its relationship with the electronic structures that affect the electron–hole recombination and the photocatalytic activity need to be clarified. The synthesis of 1-D-like TiO2 with liquid crystal as the structure-aligning agent was carried out using the sol–gel method under a magnetic field (0.3 T). The mixture of liquid crystal, 4′-pentyl-4-biphenylcarbonitrile (5CB), tetra-n-butyl orthotitanate (TBOT), 2-propanol, and water, was subjected to slow hydrolysis under a magnetic field. The TiO2–5CB took a well-aligned whiskerlike shape when the reaction mixture was placed under the magnetic field, while irregularly shaped TiO2–5CB particles were formed when no magnetic field was applied. It shows that the strong interaction between 5CB and TBOT during the hydrolysis process under a magnetic field controls the shape of titania. The intensity of the emission peaks in the photoluminescence spectrum of 1-D-like TiO2–5CB was lowered compared with the TiO2–5CB synthesized without the magnetic field, suggesting the occurrence of electron transfer from 5CB to the 1-D-like TiO2–5CB during ultraviolet irradiation. Apart from that, direct current electrical conductivity and Hall effect studies showed that the 1-D-like TiO2 composite enhanced electron mobility. Thus, the recombination of electrons and holes was delayed due to the increase in electron mobility; hence, the photocatalytic activity of the 1-D-like TiO2 composite in the oxidation of styrene in the presence of aqueous hydrogen peroxide under UV irradiation was enhanced. This suggests that the 1-D-like shape of TiO2 composite plays an important role in its photocatalytic activity

Pediatric and Adolescent Nephrology Facing the Future: Diagnostic Advances and Prognostic Biomarkers in Everyday Practice

The Special Issue entitled “Pediatric and adolescent nephrology facing the future: diagnostic advances and prognostic biomarkers in everyday practice” contains articles written in the era when COVID-19 had not yet been a major clinical problem in children. Now that we know its multifaceted clinical course, complications concerning the kidneys, and childhood-specific post-COVID pediatric inflammatory multisystem syndrome (PIMS), the value of diagnostic and prognostic biomarkers in the pediatric area should be appreciated, and their importance ought to increase

Comparison of home vs gym-based delivery exercise modes of two 8-week supervised aerobic training regimes on cardiorespiratory fitness and arterial stiffness in adults with Intellectual and Developmental Disability

As doenças cardiovasculares (DCV) são uma das principais causas de morte em pessoas com dificuldade intelectual e de desenvolvimento (DID). Fatores de risco tradicionais e emergentes estão associados ao desenvolvimento de DCV. A atividade física é considerada uma estratégia universal para a redução do risco de DCV. No entanto, o confinamento domiciliário apenas permite aplicar intervenções domiciliárias e até ao momento, a eficácia deste tipo de intervenção na redução de fatores de risco em pessoas com DID permanece esclarecer. O objetivo do estudo foi comparar contextos de exercício, domiciliário vs presencial, durante 8 semanas de dois regimes de treino aeróbio supervisionados na rigidez arterial e na aptidão cardiorrespiratória em adultos com DID. A intervenção incluí-o 17 adultos com DID que foram divididos em dois regimes: treino intervalado em sprints (SIT) e treino contínuo (CAET). Os treinos foram realizados 3 vezes por semana durante 60 minutos. A intervenção presencial melhorou a aptidão cardiorrespiratória e ambos os contextos resultaram em melhorias semelhantes na rigidez arterial. Concluindo, uma intervenção domiciliária consegue minimizar alguns efeitos fisiológicos deletérios de um confinamento obrigatório em vários fatores de risco, no entanto não corresponde aos benefícios de uma intervenção presencial, independentemente do regime de treino aeróbio.Cardiovascular diseases (CVD) are a leading cause of death in people with intellectual and developmental disability (IDD). Traditional and emergent risk factors such as cardiorespiratory fitness and arterial stiffness are associated with the development of CVD. Physical activity has been appointed as an essential universal strategy for reducing the risk of CVD. However, during the mandatory lockdown home-based interventions are the only alternative to reduce risk factors, and the efficacy of these interventions needs to be confirmed in people with IDD. The present study aims to compare home vs gym-based delivery exercise modes of two 8- week supervised aerobic training regimes on cardiorespiratory fitness and arterial stiffness in adults with IDD. The intervention included 17 adults with IDD and participants were divided into two regimes: sprint interval training (SIT) and continuous aerobic exercise training (CAET). Training for both regimes was performed 3 times a week for 60 minutes. Only the gym-based intervention improved cardiorespiratory fitness and both contexts had similar results on arterial stiffness. In conclusion, a home-based intervention may minimize the deleterious physiological effects of a mandatory lockdown on several risk factors but does not match the benefits of a gym-based intervention, regardless of exercise regim