High‐performance dielectric ceramic capacitors for automotive applications require high operation temperature, thermal stability, and reliability for dielectric ceramics. A broad composition search ...has been carried out to replace the existing BaTiO3‐based dielectrics having limited upper operating temperature due to the relatively low Curie temperature at around 120°C. However, most of the developed compositions are too complicated and compositionally sensitive, making them difficult to commercialize. This study introduces a dielectrically reliable ceramic system based on Bi1/2Na1/2TiO3 (BNT) with a wide operation temperature range simply by adding paraelectric CaZrO3 (CZ). At 15 mol% addition of CZ to BNT, the permittivity variation within ±15% from −55 to 280°C was achieved, which surpasses the EIA‐X9R standard. Moreover, the dielectric reliability was shown with low dielectric loss (tanδ < 0.02) for the aforementioned temperature range and remarkable dielectric breakdown strength (∼260 kV/cm) at room temperature. Along with the proposal of a promising high‐performance dielectric material, structural analysis and dielectric behavior investigation as a function of CZ contents were presented.
Use of intravascular ultrasound (IVUS) promotes better clinical outcomes for coronary intervention in complex coronary lesions. However, randomized data demonstrating the clinical usefulness of IVUS ...are limited for lesions treated with drug-eluting stents.
To determine whether the long-term clinical outcomes with IVUS-guided drug-eluting stent implantation are superior to those with angiography-guided implantation in patients with long coronary lesions.
The Impact of Intravascular Ultrasound Guidance on Outcomes of Xience Prime Stents in Long Lesions (IVUS-XPL) randomized, multicenter trial was conducted in 1400 patients with long coronary lesions (implanted stent ≥28 mm in length) between October 2010 and July 2014 at 20 centers in Korea.
Patients were randomly assigned to receive IVUS-guided (n = 700) or angiography-guided (n = 700) everolimus-eluting stent implantation.
Primary outcome measure was the composite of major adverse cardiac events, including cardiac death, target lesion-related myocardial infarction, or ischemia-driven target lesion revascularization at 1 year, analyzed by intention-to-treat.
One-year follow-up was complete in 1323 patients (94.5%). Major adverse cardiac events at 1 year occurred in 19 patients (2.9%) undergoing IVUS-guided and in 39 patients (5.8%) undergoing angiography-guided stent implantation (absolute difference, -2.97% 95% CI, -5.14% to -0.79%) (hazard ratio HR, 0.48 95% CI, 0.28 to 0.83, P = .007). The difference was driven by a lower risk of ischemia-driven target lesion revascularization in patients undergoing IVUS-guided (17 2.5%) compared with angiography-guided (33 5.0%) stent implantation (HR, 0.51 95% CI, 0.28 to 0.91, P = .02). Cardiac death and target lesion-related myocardial infarction were not significantly different between the 2 groups. For cardiac death, there were 3 patients (0.4%) in the IVUS-guided group and 5 patients (0.7%) in the angiography-guided group (HR, 0.60 95% CI, 0.14 to 2.52, P = .48). Target lesion-related myocardial infarction occurred in 1 patient (0.1%) in the angiography-guided stent implantation group (P = .32).
Among patients requiring long coronary stent implantation, the use of IVUS-guided everolimus-eluting stent implantation, compared with angiography-guided stent implantation, resulted in a significantly lower rate of the composite of major adverse cardiac events at 1 year. These differences were primarily due to lower risk of target lesion revascularization.
clinicaltrials.gov Identifier: NCT01308281.
The genus Disporum Salisb. is widely distributed in East Asia, yet phylogenetically relevant morphological traits useful for differentiating many of the small, perennial, herbaceous species remain ...poorly described. To address this, leaf, floral, pollen, and orbicule micromorphology of four Korean Disporum species was investigated using light and scanning electron microscopy. All Korean Disporum species examined had hypostomatic leaves, with anomocytic stomatal complexes found only on the abaxial epidermis. Guard cell length varied among species, ranging from 44.30 μm in D. viridescens to 53.49 μm in D. uniflorum. The epidermal cells of the investigated Disporum taxa had sinuate anticlinal cell walls on both adaxial and abaxial surfaces. The surface of the guard and subsidiary cells were either smooth with weak striations or had strongly wrinkled striations. The pollen grains of all Korean Disporum taxa were monads, monosulcate with granular aperture membranes, subprolate to prolate in shape with microreticulate or verrucate exine surfaces. The mean size of pollen grains ranged from 46.38 to 49.92 μm in polar length and from 34.39 to 39.58 μm in equatorial diameter across species. Sexine ornamentation was a taxonomically relevant trait for differentiating Korean Disporum taxa. Additionally, the presence of orbicules as well as the orbicular characters (e.g., size, shape, ornamentation, and association pattern) are described for the first time in species from this genus. The present investigation of leaf and floral micromorphology using light and scanning electron microscopy provides valuable information for the taxonomic differentiation and identification of Disporum species in Korea.
Research Highlights
A detailed micromorphological description of leaf, floral characters (tepal, stigma, style), pollen and orbicule is provided for Korean Disporum species using scanning electron microscopy (SEM) and light microscopy (LM).
The presence of orbicules and their taxonomic implications in Korean Disporum species are described for the first time.
Phylogenetically informative pollen and orbicule micromorphological characters are described, improving understanding the systematic relationships of Korean species in the genus Disproum.
With the exponential growth of the semiconductor industry, radiation-hardness has become an indispensable property of memory devices. However, implementation of radiation-hardened semiconductor ...memory devices inevitably requires various radiation-hardening technologies from the layout level to the system level, and such technologies incur a significant energy overhead. Thus, there is a growing demand for emerging memory devices that are energy-efficient and intrinsically radiation-hard. Here, we report a nanoelectromechanical non-volatile memory (NEM-NVM) with an ultra-low energy consumption and radiation-hardness. To achieve an ultra-low operating energy of less than 10 Formula: see text, we introduce an out-of-plane electrode configuration and electrothermal erase operation. These approaches enable the NEM-NVM to be programmed with an ultra-low energy of 2.83 Formula: see text. Furthermore, due to its mechanically operating mechanisms and radiation-robust structural material, the NEM-NVM retains its superb characteristics without radiation-induced degradation such as increased leakage current, threshold voltage shift, and unintended bit-flip even after 1 Mrad irradiation.
Atomically smooth van der Waals materials are structurally stable in a monolayer and a few layers but are susceptible to oxygen-rich environments. In particular, recently emerging materials such as ...black phosphorus and perovskite have revealed stronger environmental sensitivity than other two-dimensional layered materials, often obscuring the interesting intrinsic electronic and optical properties. Unleashing the true potential of these materials requires oxidation-free sample preparation that protects thin flakes from air exposure. Here, we fabricated few-layer hafnium disulfide (HfS2) field effect transistors (FETs) using an integrated vacuum cluster system and study their electronic properties and stability under ambient conditions. By performing all the device fabrication and characterization procedure under an oxygen- and moisture-free environment, we found that few-layer AA-stacking HfS2-FETs display excellent field effect responses (I on/I off ≈ 107) with reduced hysteresis compared to the FETs prepared under ambient conditions. Oxidation of HfS2 occurs uniformly over the entire area, increasing the film thickness by 250% at a prolonged oxidation time of >120 h, while defects on the surface are the preferential initial oxidation sites. We further demonstrated that the stability of the device in air is significantly improved by passivating FETs with BN in a vacuum cluster.
We present the results of high-resolution (R ≥ 30,000) optical and near-infrared (NIR) spectroscopic monitoring observations of an FU Orionis-type object (FUor), V960 Mon, which underwent an outburst ...in 2014 November. We have monitored this object with the Bohyunsan Optical Echelle Spectrograph and the Immersion GRating INfrared Spectrograph since 2014 December. Various features produced by a wind, disk, and outflow/jet were detected. The wind features varied over time and continually weakened after the outburst. We detected double-peaked line profiles in the optical and NIR, and the line widths tend to decrease with increasing wavelength, indicative of Keplerian disk rotation. The disk features in the optical and NIR spectra fit well with G-type and K-type stellar spectra convolved with a kernel to account for the maximum projected disk rotation velocities of about 40.3 3.8 km s−1 and 36.3 3.9 km s−1, respectively. We also report the detection of S ii and H2 emission lines, which are jet/outflow tracers and rarely found in FUors.
This paper is focused on the development a new metric that can provide information on similarity between a frequency response function (FRF) from a finite element (FE) model and from an experiment to ...determine a target level of FE model accuracy in a deterministic sense. Typically, this metric could be used in setting a target level of model updating of an FE model that predicts structural-acoustic responses in high modal density mid-frequency regimes. The FRF similarity metric (FRFSM) is based on the likelihood between two FRFs with an assumed normal distribution of structural-acoustic responses. A normalization process over the frequency range of concern provides a metric value between 0 and 1. A numerical model that consists of two substructures and joint bushings objectively examined the characteristics of the proposed FRFSM with known parameter errors. The numerical study showed that the proposed FRFSM well represented the overall difference between two FRFs over the whole frequency band. Next, subjective evaluations that consist of evaluating the similarity for two pairs of FRFs by an expert group within an automotive company were conducted to assess the performance of the proposed metric. Subjective evaluations were conducted for various FRF sets in automotive noise and vibration responses. After compensating the subjective test results in calculating the correlation with the proposed metric, the performance of the metric was investigated. Additionally, the capability of the proposed metric when it represents the amount of updating in the frequency domain was illustrated by comparing the degree of correlation with the subjective evaluations. Comparisons with the results of the subjective evaluations showed that the FRFSM well represented the experts’ knowledge on the similarity of two FRFs, both in an absolute sense and in relative accuracies of the updated FE models.
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•A new similarity metric for two FRFs on a normalized scale 0, 1 was proposed.•FRFSM well represented the difference of FRFs over the whole frequency band.•FRFSM showed excellent correlation with that of expert evaluations.•FRFSM is appropriate in the model validation of large and complex FE models.
Two novel n‐type Zintl thermoelectric materials of Ca4.97(1)Pr0.03Al2Sb6 and Ca4.94(2)Sm0.06Al2Sb6 were synthesized with the addition of two types of trivalent rare‐earth metals dopants and ...characterized by powder and single crystal x‐ray diffraction analyses. Two title compounds adopted the orthorhombic Ca5Ga2As6‐type phase and contained seven crystallographically unique atomic positions including one particular Ca/Pr or Ca/Sm mixed‐site. The crystal structure can be described as a combination of the one‐dimensional (1D) Al2Sb4Sb4/2∞1 infinite chains and the cationic elements in between the 1D chains. Electrical transport property measurements proved that Ca4.97(1)Pr0.03Al2Sb6 and Ca4.94(2)Sm0.06Al2Sb6 were indeed novel n‐type Zintl phase semiconductors with the maximum electrical conductivities of 69.51 and 75.51 S/cm at 846 K and the Seebeck coefficients of −43.26 and − 29.00 μV/K at 703 K, respectively. Density functional theory calculations proved that the successful n‐type doping should be attributed to a small margin of slight antibonding states near EF on the Sb1Sb1 crystal orbital Hamilton population (COHP) curve.
Two novel Zintl phases of Ca4.97(1)Pr0.03Al2Sb6 and Ca4.94(2)Sm0.06Al2Sb6 were successfully synthesized with some addition of Pr3+ and Sm3+‐dopants in the Ca5−xRExAl2Sb6 (RE = rare‐earth metals) system, and electrical transport property measurements proved that these compounds were indeed the n‐type thermoelectric materials having electrons as primary charge carriers.
Tactile pressure sensors as flexible bioelectronic devices have been regarded as the key component for recently emerging applications in electronic skins, health-monitoring devices, or human–machine ...interfaces. However, their narrow range of sensible pressure and their difficulty in forming high integrations represent major limitations for various potential applications. Herein, we report fully integrated, active-matrix arrays of pressure-sensitive MoS2 transistors with mechanoluminescent layers and air dielectrics for wide detectable range from footsteps to cellular motions. The inclusion of mechanoluminescent materials as well as air spaces can increase the sensitivity significantly over entire pressure regimes. In addition, the high integration capability of these active-matrix sensory circuitries can enhance their spatial resolution to the level sufficient to analyze the pressure distribution in a single cardiomyocyte. We envision that these wide-range pressure sensors will provide a new strategy toward next-generation electronics at biomachine interfaces to monitor various mechanical and biological phenomena at single-cell resolution.
Compared to conventional CMOS-only circuits, CMOS-nanoelectromechanical (CMOS-NEM) hybrid circuits provide significant advantages such as improved energy efficiency, owing to the near-zero leakage ...current of NEM memory, and increased chip density through their vertical stacking ability. In recent hybrid circuits, the conventional role of NEM memory has been to facilitate switching within the signal path. Yet, the high resistance of the NEM memory induces signal degradation and delay issues when situated within the signal path. In this letter, we propose an alternative approach by utilizing the NEM memory as a configuration memory outside the signal path, effectively avoiding the potential disadvantages associated with its high resistance characteristics. The proposed circuit is demonstrated as a 1-to-4 demultiplexer, storing select line data. This demonstration introduces new possibilities for future enhancements in the designing of CMOS-NEM hybrid circuits.
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