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The attention on piezoelectric devices has been moved in the past decade to lead-free ceramics, especially on (Ba,Ca)(Ti,Zr)O3-based materials, due to growing environmental concerns. Here we report a systematic evaluation of the effect that electric field application has on the structure, microstructure and electrical properties of Ba0.9Ca0.1Ti0.9Zr0.1O3 (BCTZ) lead-free ceramics. Powders were prepared by Pechini method. Dense ceramic samples were sintered at 1275 °C for 5 h. As observed by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS), the ceramics are single perovskite-type structure phases and they are homogeneous both at global and local scales. Rietveld analysis of the diffraction patterns for the non-poled sample is consistent with a coexistence of ferroelectric tetragonal P4mm and rhombohedral R3m symmetries. It is shown that the electric field induces changes in rhombohedral–tetragonal relative content that facilitates the polarization process of the system. Ceramics exhibit a significantly high piezoelectric response with a d33 value as high as ∼390 pC N−1, which is comparable to soft Pb(Zr1−xTix)O3 (PZTs). Scanning Electron Microscopy (SEM) analysis showed an average grain size of 20 μm and complex ferroelectric domains. A confocal Raman spectroscopy and imaging study carried out on both types of samples reveals that, upon application of an electric field, the E(LO3) + A1(LO2) + E(TO4) mode of the Raman spectra shifts to lower frequencies, indicating a reduction of the bonding force between the ions at the B-site of the perovskite (Ti4+, Zr4+) and the oxygen ions of the octahedron for the poled samples. Besides, the mentioned spatially resolved mode of the Raman spectra shows a narrower distribution in the poled sample, monitoring the polarization alignment effect in the direction of the field. These characteristics are related to the complex ferroelectric domain distribution. The polar structure changes are revealed after the application of the electric field, as well by the changes on the dielectric permittivity curves as a function of the temperature. Ceramics also display a high ferroelectric remnant polarization (Pr = 15.3 μC cm−2) and low coercive field (EC = 1.5 kV cm−1) at room temperature. [ABSTRACT FROM AUTHOR]

Highlights: [•] Low temperature processing was performed in Ba0.9Ca0.1Ti0.9Zr0.1O3 ceramics. [•] Pechini method allowed synthesizing Ba0.9Ca0.1Ti0.9Zr0.1O3 at low temperature. [•] Sintered ceramics at 1250 and 1275°C showed good piezoelectric properties. [•] Fine grained BCZT ceramics, are achieved at low temperature. [ABSTRACT FROM AUTHOR]

A chabazite-type zeolite was prepared by the hydrothermal method. Before ion exchange, the chabazite was activated with ammonium chloride (NH 4 Cl). The ion exchange process was carried out at a controlled temperature and constant stirring to obtain ion-exchanged chabazites of Ti 4+ chabazite (TiCHA), Zn 2+ chabazite (ZnCHA), Cu 2+ chabazite (CuCHA), Ag + chabazite (AgCHA) and Au 3+ chabazite (AuCHA). Modified chabazite samples were characterized by X-ray diffraction (XRD), scanning electron microscope equipped with energy-dispersive spectroscopy (SEM-EDS), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), N 2 adsorption methods and UV-visible diffuse reflectance spectroscopy (DRS). XRD results revealed that the chabazite structure did not undergo any modification during the exchange treatments. The photocatalytic activity of chabazite samples was evaluated by the degradation of methylene blue (MB) in the presence of H 2 O 2 under ultraviolet (UV) light illumination. The photodegradation results showed a higher degradation efficiency of modified chabazites, compared to the synthesized chabazite. CuCHA showed an efficiency of 98.92% in MB degradation, with a constant of k = 0.0266 min -1 following a first-order kinetic mechanism. Then, it was demonstrated that the modified chabazites could be used for the photodegradation of dyes.

Objective: To determine the estrogen-dependency of the bladder and urethral function and the coordinated activation of pelvic floor muscles (PFM) during micturition., Methods: We allocated age-matched female rabbits to control, 1-month ovariectomized (OVX), and OVX plus 2-week estradiol benzoate (EB) groups to record cystometry, urethral pressure, and electromyograms of bulbospongiosus (Bsm), and pubococcygeus muscles (Pcm) simultaneously. We also measured serum estradiol levels and myofiber cross-sectional area. We assessed urodynamic and urethral variables, categorized the Bsm-Pcm activation patterns at storage and voiding phases, and obtained the power spectrum density of muscle activation around the voiding phase. We investigated the influence of ovarian hormones, in general, and the contribution of estrogen, particularly on the functions of the bladder, urethra, and PFM. Statistical significance was set at P < 0.05., Results: Ovarian hormones influence the bladder, urethral, and PFM functions. The urodynamics analyses indicated estrogens contribute to voiding duration and, to a lesser extent, to the time between bladder contractions. Urethral pressure at closure (maximal pressure-to-maximal urethral pressure ratio) improved partially (8%, P < 0.05) in the OVX plus 2-week estradiol benzoate compared with OVX, but urethral resistance increased (∼1.9-fold, P < 0.05) compared with control rabbits. Our findings support that Pcm activity at voiding is estrogen-sensitive, albeit EB administration reduced it at storage resume, which relates to high urethral resistance., Conclusions: Ovariectomy impairs bladder and urethral pressures and Bsm and Pcm activation at micturition in anesthetized rabbits. Estrogen administration partially reverts some of these effects and influences Pcm activation., Competing Interests: Financial disclosures/conflicts of interest: None reported., (Copyright © 2021 by The North American Menopause Society.)

Aim: To determine the effect of the lumbosacral ventral root avulsion (VRA) on the reflex activation of bladder, urethra, and activation of perineal muscles during micturition in female rabbits., Methods: We allocated 14 virgin female rabbits to evaluate, first, the gross anatomy of lumbosacral spinal cord root (n = 5) and, second, to determine the effect of VRA on perineal muscles during micturition (n = 9). We recorded cystometrograms, urethral pressure, and electromyograms of the bulbospongiosus (Bsm) and ischiocavernosus (Ism) muscles before and after the L6-S2 VRA. Standard variables were measured from each recording and analyzed to identify significant differences (P < .05)., Results: We found that the L6-S2 VRA affected directly the bladder and urethral function and reduced the duration and the frequency of the bursting of Ism and Bsm muscles during voiding. The Ism and Bsm showed a phasic activation, of different frequencies, during the voiding phase and the L6-S2 VRA inhibited the co-contraction of the Ism and Bsm-bladder-urethra., Conclusions: The Ism and Bsm are activated at different frequencies to trigger the voiding phase. The L6-S2 VRA affected the activity pattern of both perineal muscles. These modifications affected the bladder and urethra function. It is possible that the restoration of the activation frequency of perineal muscles contributed for an efficient bladder contraction., (© 2020 Wiley Periodicals, Inc.)

Aims: To evaluate the combined effect of age and multiparity on the micturition reflex, including pelvic floor muscle activation., Methods: Young and mature nulliparous rabbits were compared to young and mature multiparas (n = 6 per group). Cystometrograms and urethral pressure (UP) were performed while simultaneously recording the electromyogram (EMG) activity of the pubococcygeus and bulbospongiosus muscles to establish their functional correlation to urological function., Results: Multiparity and age significantly influence the bladder and UP affecting the voiding efficiency and intercontraction interval. Such interaction also reduced the UP threshold, timing, and duration. Other bladder and urethral variables were predominantly affected only by age. Urodynamic alterations correlated with abnormal patterns or absent EMG activity of the pubococcygeus and bulbospongiosus muscles., Conclusions: The present findings strongly suggest that multiparity and age affects specific pelvic floor muscle reflex activation during micturition, and may contribute to alterations in bladder and urethral function. This data broadens our understanding of the critical role of the appropriate activity of the individual pelvic floor muscles in micturition., (© 2019 Wiley Periodicals, Inc.)

Ceramic powders of Sr1-1.5xYbxTiO3 (x = 0.0, 0.0125, 0.025, 0.05 and 0.075) solid solutions were synthesized by the polymeric complex method. The crystal structure, microstructure and optical properties of the powders annealed at 800 °C for 1 h were investigated by X-ray diffraction, scanning electron microscopy, and diffuse reflectance and photoluminescence spectroscopy, respectively. All the solid solutions exhibit a cubic perovskite-like structure. The reflectance spectra show a broadband below 400 nm ascribed to the ligand-to-metal charge transfer (LMCT) O2- → Ti4+ fundamental state. The Yb3+ (λem = 980 nm) excitation spectra show a broadband being also compatible with the LMCT O2- → Ti4+ state, indicating the energy transfer from the host to the Yb3+. The sample with x = 0.025 presents the highest emission intensity upon near UV excitation, which is further enhanced when the powder is treated under an oxygen-rich atmosphere. The luminescence quenching of Yb3+ is explained as due to defects associated with O2- and Sr2+ vacancies. Finally, it is shown that the solid solutions may downshift photons from UV to wavelengths where a crystalline-silicon photovoltaic solar cell has a higher spectral responsivity.

Aims: To determine the impact of hypothyroidism on the bladder and urethral functions as well as in the activation of the pubococcygeous (Pcm) and bulbospongiosus (Bsm) during micturition., Methods: Age-matched control and methimazole-induced hypothyroid female rabbits were used to simultaneously record cystometrograms, urethral pressure, and the reflex activation of Pcm and Bsm during the induced micturition. Urodynamic and urethral variables were measured. Activation or no activation of the Pcm and Bsm during the storage and voiding phases of micturition were categorized as 1 or 0. Significant differences (P ≤ 0.05) between control and hypothyroid groups were determined with unpaired Student-t or Mann-Whitney tests., Results: One-month induced hypothyroidism increased the residual volume and threshold pressure while the opposite was true for the voided volume, maximal pressure, and voiding efficiency. Urethral pressure was also affected as supported by a notorious augmentation of the urethral resistance, among other changes in the rest of measured variables. Hypothyroidism also affected the reflex activation of the Pcm in the voiding phase of micturition., Conclusions: Our findings demonstrate hypothyroidism impairs the bladder and, urethral functions, and reflex activation of Pcm and Bsm affecting the micturition in female rabbits., (© 2018 Wiley Periodicals, Inc.)

Aims: To characterize the contractile properties of the bulbospongiosus (Bsm), isquiocavernosus (Ism), and pubococcygeus muscles (Pcm), and their involvement in the genesis of vaginal pressure in nulliparous and multiparous rabbits., Methods: Age-matched nulliparous and multiparous rabbits were used to record the isometric contractile responses of each muscle as well as the intravaginal pressure evoked by single square electrical pulses and stimulation trains of ascending frequency. To establish significant differences between groups, two-tail unpaired Student t tests were carried out. The linear correlation between intravaginal pressure and muscle contractile force was analyzed with Pearson correlation tests. For all cases, a P ≤ 0.05 was set as statistically significant., Results: Multiparity decreased the contractile force of Bsm and Ism generated by high-frequency stimulation trains. The normalized force of the Pcm increased when evoked at 1, 4, and 10 Hz while this decreased at higher frequencies (20, 50, and 100 Hz). The contraction of both Bsm and Ism raised particularly the pressure on the perineal vagina while that of the Pcm increased the pressure in the pelvic vagina. Such a functional segregation is still present in multiparous rabbits albeit it was modified., Conclusions: Multiparity induces changes in the contractile responses of Bsm, Ism, and Pcm, which alterates the vaginal pressure., (© 2017 Wiley Periodicals, Inc.)

The solid-state method was used to synthesize single phase potassium-sodium niobate (KNN) co-doped with the La 3+ -Mn 4+ and Eu 3+ -Fe 3+ ion pairs. Structural determination of all studied solid solutions was accomplished by XRD and Rietveld refinement method. Electron paramagnetic resonance (EPR) studies were performed to determine the oxidation state of paramagnetic centers. Optical spectroscopy measurements, excitation, emission and decay lifetime were carried out for each solid solution. The present study reveals that doping KNN with La 3+ -Mn 4+ and Eu 3+ -Fe 3+ at concentrations of 0.5 mol % and 1 mol %, respectively, improves the ferroelectric and piezoelectric behavior and induce the generation of optical properties in the material for potential applications.

Purpose: To determine anatomic and functional properties of the bulboglandularis muscle (Bgm) for clarifying its role in micturition in female rabbits., Material and Methods: Virgin female rabbits were used to describe the gross anatomy and innervation of the Bgm, to determine the effect of the Bgm contraction on urethral pressure, and to evaluate the Bgm activity during the induced-micturition. Both electromyogram and cystometrogram activity were simultaneously recorded in urethane-anesthetized rabbits. Bladder function was assessed measuring standard urodynamic variables before and after blocking the Bgm activity for approaching its contribution to micturition. The relevance of the Bgm activation for micturition was approached applying lidocaine injections., Results: The Bgm was composed of circularly oriented striated fibers enveloping distal urethra and pelvic vagina. Both the venous plexus and urethra were comprised by the Bgm contraction induced by electrical stimulation. The Bgm showed bursts of tonic activity at the storage phase of micturition that gradually decreased until turning off as the onset of the voiding phase. The voided volume, the voiding efficiency, the threshold pressure, and the maximal pressure were decreased after lidocaine injection. Contrastingly, the threshold volume, the residual volume, the voiding duration, and the urethral resistance at voiding were increased., Conclusions: Present anatomical and physiological findings support that the Bgm acts as a sphincter during micturition of female rabbits. Neurourol. Urodynam. 35:689-695, 2016. © 2015 Wiley Periodicals, Inc., (© 2015 Wiley Periodicals, Inc.)

Until now, lead zirconate titanate (PZT) based ceramics are the most widely used in piezoelectric devices. However, the use of lead is being avoided due to its toxicity and environmental risks. Indeed, the attention in piezoelectric devices has been moved to lead-free ceramics, especially on (K,Na)NbO3-based materials, due to growing environmental concerns. Here we report a systematic evaluation of the effects of the compositional modifications induced by replacement of the B-sites with Sb(5+) ions in 0.96[(K0.48Na0.52)0.95Li0.05Nb1-xSbxO3]-0.04[BaZrO3] lead-free piezoceramics. We show that this compositional design is the driving force for the development of the high piezoelectric properties. So, we find that this phenomenon can be explained by the stabilization of a Rhombohedral-Tetragonal (R-T) phase boundary close to room temperature, that facilities the polarization process of the system and exhibits a significantly high piezoelectric response with a d33 value as high as ∼400 pC/N, which is comparable to part soft PZTs. As a result, we believe that the general strategy and design principles described in this study open the possibility of obtaining (K,Na)NbO3-based lead-free ceramics with enhanced properties, expanding their application range.

Lead-free ferroelectric ceramics based on the Na(0.5)Bi(0.5)TiO3 system, in solid solution with Pr(3+) and La(3+), are synthesized by the Pechini method at low temperature. The powders calcined at 700 °C are found to be below 200 nm in mean crystal size. The dielectric properties reveal a diffuse phase transition. In Na(0.5)Bi(0.5)TiO3 ceramics the rhombohedral to tetragonal transition temperature (T(R-T)) appears near 190 °C, and the Curie temperature (T(C)) at 280 °C. These transitions are shifted when Pr(3+) and La(3+) cations are introduced into the lattice. The ferroelectric properties are also affected, causing the remnant polarization and coercive field to diminish with the increase in La(3+) content. In addition, the piezoelectric properties decrease in the same way with La(3+) concentration. Finally, the red luminescence of Pr(3+) is improved when lanthanum concentration is increased.