Utilizing Domain Engineering to Achieve High-Polarization Relaxor Ferroelectrics for Low-Consumption Ceramic Capacitors.

This study focuses on incorporating NaNbO3 (NN) into the Ba0.85Ca0.15Zr0.9Ti0.1O3 (BCZT) lattice to form (1 - x)BCZT-xNN ceramics. Although antiferroelectricity was not observed, an observed domain-movement-diminishment behavior with increasing NN dopant induced the formation of high polarization walls (HPWs) between adjacent C-phases. The 0.90BCZT-0.10NN composition exhibited superior polarization compared to most BCZT-based ferroelectrics, as validated by mathematical derivation. Integration of these findings revealed a Wrec of 3.86 J/cm3 at 360 kV/cm, with a high Wrec/Eb ratio defining energy consumption efficiency in dielectric capacitors. This work introduces a novel approach to fabricating low-consumption dielectric capacitors. Additionally, a significantly high Wrec of 5.36 J/cm3 was achieved with an NN dopant concentration of 0.30.

Reaction Environment Regulation for Electrocatalytic CO2 Reduction in Acids.

The electrocatalytic CO2 reduction reaction (CO2RR) is a sustainable route for converting CO2 into value-added fuels and feedstocks, advancing a carbon-neutral economy. The electrolyte critically influences CO2 utilization, reaction rate and product selectivity. While typically conducted in neutral/alkaline aqueous electrolytes, the CO2RR faces challenges due to (bi)carbonate formation and its crossover to the anolyte, reducing efficiency and stability. Acidic media offer promise by suppressing these processes, but the low Faradaic efficiency, especially for multicarbon (C2+) products, and poor electrocatalyst stability persist. The effective regulation of the reaction environment at the cathode is essential to favor the CO2RR over the competitive hydrogen evolution reaction (HER) and improve long-term stability. This review examines progress in the acidic CO2RR, focusing on reaction environment regulation strategies such as electrocatalyst design, electrode modification and electrolyte engineering to promote the CO2RR. Insights into the reaction mechanisms via in situ/operando techniques and theoretical calculations are discussed, along with critical challenges and future directions in acidic CO2RR technology, offering guidance for developing practical systems for the carbon-neutral community.

Visualization of Bubble Nucleation and Growth Confined in 2D Flakes.

The nucleation and growth of bubbles within a solid matrix is a ubiquitous phenomenon that affects many natural and synthetic processes. However, such a bubbling process is almost "invisible" to common characterization methods because it has an intrinsically multiphased nature and occurs on very short time/length scales. Using in situ transmission electron microscopy to explore the decomposition of a solid precursor that emits gaseous byproducts, the direct observation of a complete nanoscale bubbling process confined in ultrathin 2D flakes is presented here. This result suggests a three-step pathway for bubble formation in the confined environment: void formation via spinodal decomposition, bubble nucleation from the spherization of voids, and bubble growth by coalescence. Furthermore, the systematic kinetics analysis based on COMSOL simulations shows that bubble growth is actually achieved by developing metastable or unstable necks between neighboring bubbles before coalescing into one. This thorough understanding of the bubbling mechanism in a confined geometry has implications for refining modern nucleation theories and controlling bubble-related processes in the fabrication of advanced materials (i.e., topological porous materials).

Crystal Structure and Ferroelectric Evidence of BaZnSi3 O8 , a Low-Permittivity Microwave Dielectric Ceramic.

BaZnSi3 O8 ceramic was prepared by the conventional solid-state method and sintered at 1100 °C. XRD and synchrotron Rietveld refinement analyses revealed the BaZnSi3 O8 ceramic presented a monoclinic structure with a space group of P21 /a (No.14), which is reported for the first time. The BaZnSi3 O8 ceramic presented a weak ferroelectricity, which was confirmed by the P-E loop and the 90° nanoscale ferroelectric domain. Although ϵr -T displayed two ϵr abnormal peaks at 400 °C and 460 °C, the Curie temperature (Tc ) was located at 460 °C according to the dielectric loss and Curie-Weiss law. Moreover, the BaZnSi3 O8 ceramic exhibited optimized microwave dielectric properties with ϵr =6.55, Q×f=52400 GHz, and τf =-24.5 ppm/°C. Hence, the BaZnSi3 O8 ceramic in the ternary BaO-ZnO-SiO2 system possessed both weak ferroelectricity and microwave dielectric properties. These results are expected to break the technical barrier of ferroelectric phase shifter applications in microwave and even millimeter-wave frequency bands.

Improvement of dielectric properties and energy storage performance in sandwich-structured P(VDF-CTFE) composites with low content of GO nanosheets.

Polymer-based dielectric capacitors play a notable part in the practical application of energy storage devices. Graphene oxide (GO) nanosheets can improve the dielectric properties of polymer-based composites. However, the breakdown strength will greatly reduce with the increase of GO content. Hence, the construction of sandwich structure can enhance the breakdown strength without reducing the dielectric constant. Herein, single-layered and sandwich-structured poly(vinylidene fluoride-co-chlorotrifluoroethylene) (P(VDF-CTFE)) nanocomposites with low content of GO nanosheets (<1.0 wt%) are prepared via employing a straightforward casting method. Compared with the single-layered composites and pure P(VDF-CTFE), the sandwich-structured composites exhibit comprehensively better performance compared. The sandwich-structured composite with 0.4 wt% GO nanosheets show an excellent dielectric constant of 13.6 (at 1 kHz) and an outstanding discharged energy density of 8.25 J cm-3at 3400 kV cm-1. These results demonstrate that the growth of the dielectric properties is owing to 2D GO nanosheets and the enhancement of breakdown strength due to the sandwich structure. The results from finite element simulation provide theoretical support for the design of high energy density composites.

Analysis on real-time phase delay in an interferometric FBG sensor array using polarization switching and the PGC hybrid processing method.

The polarization switching and phase generated carrier (PS-PGC) hybrid method is typically adopted to control signal fading induced by fiber birefringence and to precisely demodulate signals in interferometric fiber Bragg grating (FBG) sensor arrays. Unlike simple PGC demodulation, the real-time phase delay between the detected interference and the PGC carrier in the hybrid method has more adverse effects as both demodulation accuracy and background noise can be deteriorated, which may invalidate the polarization switching (PS) method. Aiming at this issue, the real-time phase delay and its compensation method were analyzed in detail in this paper. The features of the real-time phase delay in the PS-PGC hybrid method were summarized and the differences among polarization channels were investigated. Theoretical analysis indicated that the real-time phase delay mainly affected the interference complex synthesis (ICS) procedure, ultimately bringing about errors in the PS-PGC algorithm. The method for demodulating the real-time phase delay from sampled interference was presented, which provided the key compensation parameter. Experimental results showed that the compensation method could greatly improve the stability of the demodulated signal and suppress the sensor background phase noise. The amplitude of the demodulated signal was stabilized with a fluctuation less than ± 0.75dB and a noise suppression of 5dB. The acceptable compensation error was also analyzed.

Homogeneous ZnO nanowire arrays p-n junction for blue light-emitting diode applications.

ZnO is a promising short-wavelength light-emitting materials for its wide bandgap (3.37 eV) and large exciton binding energy (∼60 meV), however, practical p-type doped ZnO is the main challenge in this field. Here, Blue light-emitting diodes (LEDs) based on the homogeneous junctions of Sb doped ZnO nanowire arrays grown on Ga doped ZnO single crystal substrate are fabricated. Element analysis, FET and Hall-effect measurements demonstrate that the Sb atom has been successfully doped into ZnO nanowires to from p-type conductivity. On the benefit of high quality of nano-size homojunction, the fabricated LED shows low turn-on voltage turn-on voltage as low as 3.4 V and strong blue emission peak located at 425 nm at room temperature, which originate from interfacial recombination of ZnO nanowire p-n homojunctions. The present blue LED based on ZnO material may have potential applications in short-wavelength optoelectronic devices.

Influence of Structural Parameters on the Surface Enhanced Raman Scattering of Au Nanoarrays.

As an important research topic of surface enhanced Raman scattering (SERS), periodic metal nanoarrays have attracted remarkable attention due to their superior properties, such as excellent enhancing ability, and high structural homogeneity and stability. In this work, periodic Au nanostructures with variable repetitive unit size, Au nanoparticle size, and gap sizes are fabricated by electron beam lithography on SiO2/Si substrates to investigate the influence of these structural parameters on SERS performances. The SERS intensity is found to increase linearly with decreasing repetitive unit size (increase of Au nanoparticle number density), while shows no obvious dependence on the Au nanoparticle size. A SERS enhancement factor of 6.6 × 105 is obtained for Au arrays with a repetitive unit size of 200 nm. The gap size does not affect the SERS intensity when it is over 75 nm, and exhibits an obvious enhancement effect when it is below 25 nm. A linear quantitative relationship between the Raman intensity and analyte concentrations of R6G, as well as a limit of detection of 10-11 mol/L was achieved for an Au nanoparticle array with gap size of 25 nm.

Fabrication of CuO-Pt core-shell nanohooks by in situ reconstructing the Pt-shells.

The design of various nanostructures with specific compositions and shapes is highly demanded due to the widespread use of micro/nano electro-mechanical systems. In this work, one-dimensional CuO-Pt core-shell nanowires (NWs) are acquired by depositing Pt nanoparticles onto CuO NWs and then mechanically-shaped into nanohooks. Subsequently, the hook-like shape is maintained by the Pt-shell which is reconstructed via Joule heat and re-solidified after cooling down, during which the elastic strain energy is stored in the CuO-core. The results provide a simple strategy to design nanostructures with various compositions and shapes, implying the potential applications in mechanical energy storage and shape memory nanodevices.

Ultraviolet Detectors Based on Wide Bandgap Semiconductor Nanowire: A Review.

Ultraviolet (UV) detectors have attracted considerable attention in the past decade due to their extensive applications in the civil and military fields. Wide bandgap semiconductor-based UV detectors can detect UV light effectively, and nanowire structures can greatly improve the sensitivity of sensors with many quantum effects. This review summarizes recent developments in the classification and principles of UV detectors, i.e., photoconductive type, Schottky barrier type, metal-semiconductor-metal (MSM) type, p-n junction type and p-i-n junction type. The current state of the art in wide bandgap semiconductor materials suitable for producing nanowires for use in UV detectors, i.e., metallic oxide, III-nitride and SiC, during the last five years is also summarized. Finally, novel types of UV detectors such as hybrid nanostructure detectors, self-powered detectors and flexible detectors are introduced.

Remarkably Enhanced Room-Temperature Hydrogen Sensing of SnO2 Nanoflowers via Vacuum Annealing Treatment.

In this work, SnO2 nanoflowers synthesized by a hydrothermal method were employed as hydrogen sensing materials. The as-synthesized SnO2 nanoflowers consisted of cuboid-like SnO2 nanorods with tetragonal structures. A great increase in the relative content of surface-adsorbed oxygen was observed after the vacuum annealing treatment, and this increase could have been due to the increase in surface oxygen vacancies serving as preferential adsorption sites for oxygen species. Annealing treatment resulted in an 8% increase in the specific surface area of the samples. Moreover, the conductivity of the sensors decreased after the annealing treatment, which should be attributed to the increase in electron scattering around the defects and the compensated donor behavior of the oxygen vacancies due to the surface oxygen adsorption. The hydrogen sensors of the annealed samples, compared to those of the unannealed samples, exhibited a much higher sensitivity and faster response rate. The sensor response factor and response rate increased from 27.1% to 80.2% and 0.34%/s to 1.15%/s, respectively. This remarkable enhancement in sensing performance induced by the annealing treatment could be attributed to the larger specific surface areas and higher amount of surface-adsorbed oxygen, which provides a greater reaction space for hydrogen. Moreover, the sensors with annealed SnO2 nanoflowers also exhibited high selectivity towards hydrogen against CH4, CO, and ethanol.

Preoperative and postoperative analgesic techniques in the treatment of patients undergoing transabdominal hysterectomy: a preliminary randomized trial.

BACKGROUND: Although pre-emptive analgesia is commonly used for the management of postoperative pain in developed countries, no defined protocol has been carried out and widely practiced, especially in transabdominal hysterectomy. Keeping this in mind the present study aimed to investigate the effects of multimodal pre-emptive analgesia on pain management, stress response and inflammatory factors of patients undergoing transabdominal hysterectomy to find an optimized way of pre-emptive analgesia. METHODS: One hundred patients undergoing abdominal hysterectomy were randomly divided into four groups (Trial registration: ChiCTR-IPR-15005848). Group P1 was given intravenous flurbiprofen and epidural fentanyl + ketamine before surgery; Group P2 received intravenous flurbiprofen before surgery and epidural fentanyl + ketamine after surgery; Group P3 was given epidural fentanyl + ketamine before surgery and intravenous flurbiprofen after surgery; Patients in Group C received normal saline treatment. RESULTS: Compared with control group, the first time to request additional analgesics after surgery were significantly later (P < 0.05), 24 h dosage of analgesia were significantly less (P < 0.05), VAS score at all time periods after surgery were significantly lower (P < 0.05) in Group P1, P2, or P3. At 12 h or 24 h after surgery, VAS score in Group P1 was significantly lower than that in group P2 or P3 (P < 0.05, P < 0.05). No significant adverse effects were found among the groups (P > 0.05). At 1 or 2 days after surgery, the levels of cortisol, glucose, and IL-6, TNF-α in group P1, P2, and P3 were significantly lower than those in group C (P < 0.05); while, the levels in group P2, P3 were significantly lower than those in group P1 (P < 0.05). CONCLUSION: Multimodal pre-emptive analgesia could significantly lower VAS score, inhibit stress response, and reduce inflammatory response in patients undergoing transabdominal hysterectomy, which can be a rational strategy for pain control in future. TRIAL REGISTRATION: ChiCTR-IPR-15005848 on January 17, 2015.

Surprising Effects of Ti and Al2O3 Coatings on Tribocatalytic Degradation of Organic Dyes by GaN Nanoparticles.

GaN is more stable than most metal oxide semiconductors for the photocatalytic degradation of organic pollutants in harsh conditions, while its catalytic efficiency has been difficult to be substantially improved. In this study, the tribocatalytic degradation of organic dyes by GaN nanoparticles has been investigated. Stimulated through magnetic stirring using homemade Teflon magnetic rotary disks in glass beakers, the GaN nanoparticles were found to induce negligible degradation in rhodamine B (RhB) and methyl orange (MO) solutions. Surprisingly, the degradation was greatly enhanced in beakers with Ti and Al2O3 coatings on their bottoms: 99.2% and 99.8% of the 20 mg/L RhB solutions were degraded in 3 h for the Ti and Al2O3 coatings, respectively, and 56% and 60.2% of the 20 mg/L MO solutions were degraded in 24 h for the Ti and Al2O3 coatings, respectively. Moreover, the MO molecules were only broken into smaller organic molecules for the Ti coating, while they were completely degraded for the Al2O3 coating. These findings are important for the catalytic degradation of organic pollutants by GaN in harsh environments and for achieving a better understanding of tribocatalysis as well.

Ultrahigh Energy Storage in (Ag,Sm)(Nb,Ta)O3 Ceramics with a Stable Antiferroelectric Phase, Low Domain-Switching Barriers, and a High Breakdown Strength.

AgNbO3 (AN) antiferroelectrics (AFEs) are regarded as a promising candidate for high-property dielectric capacitors on account of their high maximum polarization, double polarization-electric field (P-E) loop characteristics, and environmental friendliness. However, high remnant polarization (Pr) and large polarization hysteresis loss from room-temperature ferrielectric behavior of AN and low breakdown strength (Eb) cause small recoverable energy density (Wrec) and efficiency (η). To solve these issues, herein, we have designed Sm3+ and Ta5+ co-doped AgNbO3. The addition of Sm3+ and Ta5+ reduces the tolerance factor, polarizability of B-site cations, and domain-switching barriers, enhancing AFE phase stability and decreasing hysteresis loss. Meanwhile, adding Sm3+ and Ta5+ leads to decreased grain sizes, increased band gap, and reduced leakage current, all contributing to increased Eb. As a benefit from the above synergistic effects, a high Wrec of 7.24 J/cm3, η of 72.55%, power density of 173.73 MW/cm3, and quick discharge rate of 18.4 ns, surpassing those of many lead-free ceramics, are obtained in the (Ag0.91Sm0.03)(Nb0.85Ta0.15)O3 ceramic. Finite element simulations for the breakdown path and transmission electron microscopy measurements of domains verify the rationality of the design strategy.

Enhancement of acoustic sensitivity of hollow-core photonic bandgap fibers.

The acoustic pressure sensitivities of hollow-core photonic bandgap fibers (HC-PBFs) with different thicknesses of silica outer-cladding and polymer jacket were experimentally investigated. Experiment with a HC-PBF with 7 µm-thick silica outer cladding and 100 µm-thick Parylene C jacket demonstrated a pressure sensitivity 10 dB higher than the commercial HC-1550-02 fiber and 25 dB higher than a standard single mode fiber. The significant enhancement in sensitivity would simplify the design of fiber hydrophone arrays and increase the number of sensors that could be multiplexed in a single fiber.

Genome and molecular characterization of a CSFV strain isolated from a CSF outbreak in South China.

In the present study, the full-length nucleotide sequences of the CSFV-GZ-2009 strain of classical swine fever virus (CSFV) isolated from a hog pen in Guangdong province in China was determined. Results demonstrated that the genome of CSFV-GZ-2009 is 12,298 nucleotides (nt) in length, is composed of a 373-nt 5'-untranslated region (UTR), has an 11,697-nt open reading frame encoding a polyprotein of 3,898 amino acids, and has a 228-nt 3'-UTR. Genome comparison of the CSFV-GZ-2009 isolate (GenBank accession No. HQ380231) with other CSFV strains was also analyzed. Gene regions from CSFV-GZ-2009 and other known strains were shown to share 92.7-96.7% identity at the nucleotide level and 94.7-99.2% identity at the amino acid level. Phylogenetic analysis of the full-length genome and the following regions E(rns), E2 and NS5B revealed that the CSFV-GZ-2009 isolate was classified within subgroup 1.1 of group I and closely related to the highly virulent strain JL1 (06), cF114, Shimen and SWH with pairwise distances of 0.0037, 0.0043, 0.0058 and 0.0107, respectively. Analysis of recombination with the SimPlot program demonstrated that strain CSFV-GZ-2009 was not a naturally homologous recombinant. Furthermore, the change of clinical signs of pigs after infection of CSFV-GZ-2009 isolates showed typical symptoms such as diarrhea, persistent fever, and mononuclear lymphocytopenia after CSFV infection. Based on phylogenetic analysis and an animal infection test, we could conclude that the CSFV-GZ-2009 isolate belonged to subgroup 1.1 of group I and was of high virulence.

Effect of Strontium Substitution on the Tribocatalytic Performance of Barium Titanate.

This study investigates the impact of Sr doping on the tribocatalytic performance of BaTiO3 in degrading organic pollutants. Ba1-xSrxTiO3 (x = 0-0.3) nanopowders are synthesized and their tribocatalytic performance evaluated. By doping Sr into BaTiO3, the tribocatalytic performance was enhanced, resulting in an approximately 35% improvement in the degradation efficiency of Rhodamine B using Ba0.8Sr0.2TiO3. Factors such as the friction contact area, stirring speed, and materials of the friction pairs also influenced the dye degradation. Electrochemical impedance spectroscopy revealed that Sr doping improved BaTiO3's charge transfer efficiency, thereby boosting its tribocatalytic performance. These findings indicate potential applications for Ba1-xSrxTiO3 in dye degradation processes.

3D relationship between hierarchical canal network and gradient mineralization of shark tooth osteodentin.

Osteodentin is a dominant mineralized collagenous tissue in the teeth of many fishes, with structural and histological characteristics resembling those of bone. Osteodentin, like bone, comprises osteons as basic structural building blocks, however, it lacks the osteocytes and the lacuno-canalicular network (LCN), which are known to play critical roles in controlling the mineralization of the collagenous matrix in bone. Although numerous vascular canals exist in osteodentin, their role in tooth maturation and the matrix mineralization process remain poorly understood. Here, high resolution micro-computed tomography (micro-CT) and focused ion beam-scanning electron microscopy (FIB-SEM) were used to obtain 3D structural information of osteodentin in shark teeth at multiple scales. We observed a complex 3D network of primary canals with a diameter ranging from ∼10 µm to ∼120 µm, where the canals are surrounded by osteon-like concentric layers of lamellae, with 'interosteonal' tissue intervening between neighboring osteons. In addition, numerous hierarchically branched secondary canals extended radially from the primary canals into the interosteonal tissue, decreasing in diameter from ∼10 µm to hundreds of nanometers. Interestingly, the mineralization degree increases from the periphery of primary canals into the interosteonal tissue, suggesting that mineralization begins in the interosteonal tissue. Correspondingly, the hardness and elastic modulus of the interosteonal tissue are higher than those of the osteonal tissue. These results demonstrate that the 3D hierarchical canal network is positioned to play a critical role in controlling the gradient mineralization of osteodentin, also providing valuable insight into the formation of mineralized collagenous tissue without osteocytes and LCN. STATEMENT OF SIGNIFICANCE: Bone is a composite material with versatile mechanical properties. Osteocytes and their lacuno-canalicular network (LCN) are known to play critical roles during formation of human bone. However, the bone and osteodentin of many fishes, although lacking osteocytes and LCN, exhibit similar osteon-like structure and mechanical functions. Here, using various high resolution 3D characterization techniques, we reveal that the 3D network of primary canals and numerous hierarchically branched secondary canals correlate with the mineralization gradient and micromechanical properties of osteonal and interosteonal tissues of shark tooth osteodentin. This work significantly improves our understanding of the construction of bone-like mineralized tissue without osteocytes and LCN, and provides inspirations for the fabrication of functional materials with hierarchical structure.

Giant Piezoelectric Output and Stability Enhancement in Piezopolymer Composites with Liquid Metal Nanofillers.

Integrating nanomaterials into the polymer matrix is an effective strategy to optimize the performance of polymer-based piezoelectric devices. Nevertheless, the trade-off between the output enhancement and stability maintenance of piezoelectric composites usually leads to an unsatisfied overall performance for the high-strength operation of devices. Here, by setting liquid metal (LM) nanodroplets as the nanofillers in a poly(vinylidene difluoride) (PVDF) matrix, the as-formed liquid-solid/conductive-dielectric interfaces significantly promote the piezoelectric output and the reliability of this piezoelectric composite. A giant performance improvement featured is obtained with, nearly 1000% boosting on the output voltage (as high as 212 V), 270% increment on the piezoelectric coefficient (d33 ∼51.1 pC N-1 ) and long-term reliability on both structure and output (over 36 000 cycles). The design of a novel heterogenous interface with both mechanical matching and electric coupling can be the new orientation for developing high performance piezoelectric composite-based devices.

Transient reflectance spectra of adaptive filters based on dynamic population gratings.

We propose a novel and practical method to exactly measure the transient reflectance spectra (TRS) of the adaptive filters based on dynamic population gratings. The modulating signals applied to the laser source play an important role. We specially designed a train of triangular amplitude modulated pulses with a small duty to modulate the laser frequency, and then the TRS was obtained from the grating responses to this pulse train. The measured half-zero-point bandwidths of the filter with and without 2.6 m cavity length are 20 and 60 MHz, respectively. Our research also indicates that the relatively high input power and a short cavity length may enhance the antiperturbation ability of lasers.