Development and Field Test of Integrated Electronics Piezoelectric Accelerometer Based on Lead-Free Piezoelectric Ceramic for Centrifugal Pump Monitoring.

In this study, an Integrated Electronics Piezoelectric (IEPE)-type accelerometer based on an environmentally friendly lead-free piezoceramic was fabricated, and its field applicability was verified using a cooling pump owned by the Korea Atomic Energy Research Institute (KAERI). As an environmentally friendly piezoelectric material, 0.96(K,Na)NbO-0.

Enhanced thermal stability by short-range ordered ferroelectricity in KNaNbO-based piezoelectric oxides.

Industrial application of lead-free piezoelectric ceramics is prevented by intrinsic thermal instability. Herein, we propose a method to achieve outstanding thermal stability of converse piezoelectric constant () in lead-free potassium sodium niobate (KNN)-based ceramics by inducing a synergistic interaction between the grain size and polar configuration. Based on computational methods using phase-field simulations and first-principles calculations, the relationship between the grain size and polar configuration is demonstrated, and the possibility of achieving improved thermal stability in fine grains is suggested.

Lead-Free Piezoelectric Acceleration Sensor Built Using a (K,Na)NbO Bulk Ceramic Modified by Bi-Based Perovskites.

Piezoelectric accelerometers using a lead-free (K,Na)NbO (KNN) piezoceramic modified by a mixture of two Bi-based perovskites, Bi(Na,K,Li)ZrO (BNKLZ) and BiScO (BS), were designed, fabricated and characterized. Ring-shaped ceramics were prepared using a conventional solid-state reaction method for integration into a compression-mode accelerometer. A beneficial rhombohedral-tetragonal (R-T) phase boundary structure, especially enriched with T phase, was produced by modifying intrinsic phase transition temperatures, yielding a large piezoelectric charge coefficient (310 pC/N) and a high Curie temperature (331 °C).

Piezoelectric Energy Harvesting from Two-Dimensional Boron Nitride Nanoflakes.

Two-dimensional (2D) piezoelectric hexagonal boron nitride nanoflakes (h-BN NFs) were synthesized by a mechanochemical exfoliation process and transferred onto an electrode line-patterned plastic substrate to characterize the energy harvesting ability of individual NFs by external stress. A single BN NF produced alternate piezoelectric output sources of ∼50 mV and ∼30 pA when deformed by mechanical bendings. The piezoelectric voltage coefficient () of a single BN NF was experimentally determined to be 2.

Design Optimization of Bulk Piezoelectric Acceleration Sensor for Enhanced Performance.

While seeking to achieve high performances of a bulk piezoelectric acceleration sensor, we investigated the behavior of the design variables of the sensor components and optimized the sensor design using a numerical simulation based on piezoelectric analysis and metamodeling. The optimized results demonstrated that there was an exponential dependency in the trade-off relation between two performance indicators, the electric voltage and the resonant frequency, as induced by the design characteristics of the sensor. Among the design variables, a decrease in the base height and epoxy thickness and an increase in the piezo element's inner diameter had a positive effect on two performances, while the head dimensions (diameter and height) exhibited the opposite effect on them.

Proposal of a rhombohedral-tetragonal phase composition for maximizing piezoelectricity of (K,Na)NbO ceramics.

Great progress in the field of piezoelectricity of (K,Na)NbO (KNN) lead-free ceramics, driven by emerging rhombohedral-tetragonal (R-T) phase boundary, has instigated research activity regarding elaborate controls of the phase boundary structure. Through phase-microstructure-property mapping in KNN ceramics doped with Bi-containing perovskite oxides, in this study we for the first time report the existence of a certain R-T phase boundary state by which to create maximum piezoelectric response in KNN systems. This phase boundary condition is usually comprised of approximately 15% R phase and 85% T phase, regardless of the choice of dopant material.

Aging-resistant nanofluids containing covalent functionalized boron nitride nanosheets.

Developing a thermally stable nanofluid that can maintain good thermo-conductive and flow performance at moderate or elevated temperatures for prolonged periods of time is a great challenge in heat transfer applications. Here, the thermal conductivity and rheological properties as well as their thermal stability characteristics of a nanofluid containing two-dimensional (2D) hexagonal boron nitride nanosheets (h-BNNSs) in ethylene glycol (EG) are presented, in comparison with those for a graphene oxide (GO) nanofluid as a counterpart. In place of a surfactant, hydroxyl functional groups covalently bound to the BNNS surface provided excellent compatibility and stable dispersion of the particles within EG at temperatures up to 90 °C.

Rapid and direct synthesis of complex perovskite oxides through a highly energetic planetary milling.

The search for a new and facile synthetic route that is simple, economical and environmentally safe is one of the most challenging issues related to the synthesis of functional complex oxides. Herein, we report the expeditious synthesis of single-phase perovskite oxides by a high-rate mechanochemical reaction, which is generally difficult through conventional milling methods. With the help of a highly energetic planetary ball mill, lead-free piezoelectric perovskite oxides of (Bi, Na)TiO, (K, Na)NbO and their modified complex compositions were directly synthesized with low contamination.

Nanogenerators consisting of direct-grown piezoelectrics on multi-walled carbon nanotubes using flexoelectric effects.

We report the first attempt to prepare a flexoelectric nanogenerator consisting of direct-grown piezoelectrics on multi-walled carbon nanotubes (mwCNT). Direct-grown piezoelectrics on mwCNTs are formed by a stirring and heating method using a Pb(Zr0.52Ti0.

Precisely Determining Ultralow level UO2(2+) in Natural Water with Plasmonic Nanowire Interstice Sensor.

Uranium is an essential raw material in nuclear energy generation; however, its use raises concerns about the possibility of severe damage to human health and the natural environment. In this work, we report an ultrasensitive uranyl ion (UO2(2+)) detection method in natural water that uses a plasmonic nanowire interstice (PNI) sensor combined with a DNAzyme-cleaved reaction. UO2(2+) induces the cleavage of DNAzymes into enzyme strands and released strands, which include Raman-active molecules.

Effects of sintering temperature on the pyrochlore phase in PZT nanotubes and their transformation to the perovskite phase by coating with PbO multilayers.

We report the phase evolution of Pb(Zr0.52Ti0.48)O3 nanotubes (PZT-NTs), from the pyrochlore to perovskite phase, with an outer diameter of about 420 nm and a wall thickness of about 10 nm.

The role of hand-assisted laparoscopic surgery in a right hemicolectomy for right-sided colon cancer.

Purpose: The purpose of this study is to evaluate the perioperative and long-term oncologic outcomes of hand-assisted laparoscopic surgery (HALS) and standard laparoscopic surgery (SLS) and assess the role of HALS in the management of right-sided colon cancer.

Methods: The study group included 53 patients who underwent HALS and 45 patients who underwent SLS for right-sided colon cancer between April 2002 and December 2008.

Results: The patients in each group were similar in age, American Society of Anesthesiologist (ASA) score, body mass index, and history of previous abdominal surgeries.

Phototoxic effect of blue light on the planktonic and biofilm state of anaerobic periodontal pathogens.

Purpose: The purpose of this study was to compare the phototoxic effects of blue light exposure on periodontal pathogens in both planktonic and biofilm cultures.

Methods: Strains of Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, and Porphyromonas gingivalis, in planktonic or biofilm states, were exposed to visible light at wavelengths of 400.520 nm.

Reliability evaluation of nano-bi/silver paste sensor electrode for detecting trace metals.

The reliability of sensor characteristics for a nano-bismuth (Bi)/silver (Ag) paste electrode has been investigated by comparison with Hg/Bi film electrodes in terms of accuracy and precision. Using Ag paste instead of carbon paste as a conducting layer, the sensitivity and detection limit of the sensor electrode were more enhanced due to a lower electrical conductivity of Ag. For the evaluation of detecting ability, the Zn, Cd, and Pb ion concentrations of the prepared standard solutions were experimentally measured on Hg film, Bi film, and nano-Bi electrodes using anodic stripping voltammetry.

Effect of phase stability degradation of bismuth on sensor characteristics of nano-bismuth fixed electrode.

Effect of phase stability degradation of bismuth on sensor characteristics of nano-bismuth fixed electrode has been investigated using square-wave anodic stripping voltammetry technique, scanning electron microscopy (SEM) and X-ray diffraction (XRD) spectroscopy. From the analyses of square-wave anodic stripping voltammograms (SWASV) repetitively measured on the nano-bismuth fixed electrode, it was found that the oxidation peak currents dropped by 81%, 68% and 59% for zinc, cadmium and lead, respectively, after the 100th measurement (about 400 min of operation time). The sphere bismuth nanoparticles gradually changed to the agglomerates with petal shape as the operation time increased.

Marginal bony changes in relation to different vertical positions of dental implants.

Purpose: The purpose of this study was to radiographically evaluate marginal bony changes in relation to different vertical positions of dental implants.

Methods: Two hundred implants placed in 107 patients were examined. The implants were classified by the vertical positions of the fixture-abutment connection (microgap): 'bone level,' 'above bone level,' or 'below bone level.

The effect of implant shape and bone preparation on primary stability.

Purpose: The purpose of this study was to evaluate the effects of implant shape and bone preparation on the primary stability of the implants using resonance frequency analysis.

Methods: Sixty bovine rib blocks were used for soft and hard bone models. Each rib block received two types of dental implant fixtures; a straight-screw type and tapered-screw type.

Synthesis of nanocrystalline bismuth and its application to the detection of trace metals.

Surface modified carbon strip electrode with Bi nanopowder was suggested for a simultaneous analysis of Zn, Cd, and Pb ions by a square wave anodic stripping voltammetry, and the influence of the modifying Bi mass and particle size on the trace metal response was investigated. The Bi nanopowders with various particle size distributions were synthesized by an optimization of the gas condensation condition, in which a refractory crucible was applied for the evaporation of volatile Bi, and then immobilized on the surface of a working electrode. The result of the stripping measurements shows that when the modifying mass and the particle size of the Bi powder were in the range of 2 to 5 microg/cm2 and less than 300 nm, respectively, a well-developed and reproducible stripping response was obtained.

Homogeneous dispersion of TiC nano particles in a cast carbon steel matrix.

Metal matrix nano-composites (MMNCs) (metal matrix with nano-sized ceramic particles) can be of great significance because of their high performance and thus it would be advantageous to produce as-cast bulk MMNCs. However, it is so difficult to disperse nano-sized ceramic particles uniformly in molten metal. In this study, carbon steel matrix composites with a homogeneous dispersion of TiC nano particles were fabricated by conventional liquid metal casting method.