Construction of a uniform zeolitic imidazole framework (ZIF-8) nanocrystal through a wet chemical route towards supercapacitor application.

Exploring larger surface area electrode materials is crucial for the development of an efficient supercapacitors (SCs) with superior electrochemical performance. Herein, a cost-effective strategy was adopted to synthesize a series of ZIF8 nanocrystals, and their size effect as a function of surface area was also examined. The resultant ZIF8-4 nanocrystal exhibits a uniform hexagonal structure with a large surface area (2800 m2 g-1) and nanometre size while maintaining a yield as high as 78%. The SCs performance was explored by employing different aqueous electrolytes (0.5 M H2SO4 and 1 M KOH) in a three-electrode set-up. The SC performance using a basic electrolyte (1 M KOH) was superior owing to the high ionic mobility of K+. The optimized ZIF8-4 nanocrystal electrode showed a faradaic reaction with a highest capacitance of 1420 F g-1 at 1 A g-1 of current density compared to other as-prepared electrodes in the three-electrode assembly. In addition, the resultant ZIF8-4 was embedded into a symmetric supercapacitor (SSC), and the device offered 350 F g-1 of capacitance with a maximum energy and power density of 43.7 W h kg-1 and 900 W kg-1 at 1 A g-1 of current density, respectively. To determine the practical viewpoint and real-world applications of the ZIF8-4 SSC device, 7000 GCD cycles were performed at 10 A g-1 of current density. Significantly, the device exhibited a cycling stability around 90% compared to the initial capacitance. Therefore, these findings provide a pathway for constructing large surface area ZIF8-based electrodes for high-value-added energy storage applications, particularly supercapacitors.

Tunning the Zeolitic Imidazole Framework (ZIF8) through the Wet Chemical Route for the Hydrogen Evolution Reaction.

Utilizing zeolitic imidazolate frameworks (ZIFs) poses a significant challenge that demands a facile synthesis method to produce uniform and nanometer-scale materials with high surface areas while achieving high yields. Herein, we demonstrate a facile and cost-effective strategy to systematically produce ZIF8 nanocrystals. Typically, ZIF8 nanocrystal synthesis involves a wet chemical route. As the reaction time decreased (150, 120, and 90 min), the size of the ZIF8 crystals decreased with uniform morphology, and productivity reached as high as 89%. The composition of the product was confirmed through XRD, FE-SEM, TEM, EDS, and Raman spectroscopy. The ZIF8 synthesized with different reaction time was finally employed for catalyzing the electrochemical hydrogen evaluation reaction (HER). The optimized ZIF8-3 obtained at 90 min of reaction time exhibited a superior catalytic action on the HER in alkaline medium, along with a remarkably long-term stability for 24 h compared with the other ZIF8 nanocrystals obtained at different reaction times. Specifically, the optimized ZIF8-3 sample revealed an HER overpotential of 172 mV and a Tafel slope of 104.15 mV·dec-1. This finding, thus, demonstrates ZIF8 as a promising electrocatalyst for the production of high-value-added green and sustainable hydrogen energy.

Enhancement of electrochromic properties using nanostructured amorphous tungsten trioxide thin films.

Electrochromic technologies have recently attracted attention due to their energy-saving performance for reducing green gas emissions. The materials design and preparation of electrochromic materials with sufficient microstructure and crystallographic features for suitable ion intercalation/deintercalation are essential for high performance and efficiency. In the present work, nanostructured amorphous tungsten trioxide (WO3) films are electrodeposited to enhance electrochromic properties by controlling the pH of electrolytes. Electron microscopy and spectroelectrochemical analysis demonstrate that smaller grain sizes result in larger electrochemical reactive surface areas and shorter ion diffusion lengths. Consequently, the ions efficiently intercalated and deintercalated during the coloring and bleaching states, respectively. In particular, prepared WO3 films at electrolyte pH 1.4 demonstrate high optical modulation (74.83%) and good transmittance switching speeds (1.56 and 2.06 s during coloring and bleaching, respectively) at 650 nm, as well as comparable coloration efficiency (61.92 cm2 C-1 at 650 nm).

A nationwide survey on the management of the COVID-19 pandemic and respiratory disease in South Korea.

Background: This study aimed to explore individual prevalence of respiratory symptoms and to describe the Korean population's treatment approaches, preventive health behaviors, and mental health conditions during the pandemic. Methods: We analyzed responses from an online nationwide survey, conducted between February 2021 to May 2021, about people's experiences during the pandemic. Statistical analysis was also performed to see if there were any significant differences in treatment and prevention strategies between different groups of respondents (between those had respiratory symptoms, compared with those who did not, and between those tested positive for COVID-19, compared with those who did not). Results: A total of 2,177 survey respondents completed the survey and, of these, only 142 had experienced symptoms. The most frequently reported respiratory infections related symptoms were runny or blocked nose (47.6%), cough (45.5%), fever (44.1%), sore throat (42.0%), and fatigue (30.1%). More than half of the respondents (53.1%) used complementary and alternative medicine (CAM) approaches as means of preventive measures. In terms of preventive behaviors, the more emphasized behaviors were mask-wearing (58.9%) and hand-washing after coming home (42.7%). The majority of the respondents (64.9%) did not show signs of mental health issues. Conclusion: In South Korea, conventional medicine was mainly used for COVID-19 treatment whereas CAM was commonly used as preventive measures. COVID-19 was also found to have less impact on the general population's mental health. The findings of this study may shed light on how the pandemic impacted the general population.

Maca (Lepidium meyenii Walp.) on semen quality parameters: A systematic review and meta-analysis.

Background: This study aimed to examine the evidence for the effect of Lepidium meyenii Walp. [Brassicaceae] (L. meyenii W.), known as maca, on improving semen quality. Methods: Nine databases were searched for randomized controlled trials (RCTs) that examined the parameters for improvements in semen quality, regardless of the type of L. meyenii W. The risk of bias (ROB) among the studies was evaluated according to the Cochrane ROB tool. Results: Five RCTs met all of the inclusion criteria. Three RCTs showed mixed efficacy of maca in improving semen quality parameters, including sperm concentration and sperm motility, in men experiencing infertility. The meta-analysis also failed to show the efficacy of maca in increasing the sperm concentration compared to the placebo (weighted mean difference, 2.22, 95% confidence interval -2.94 to 7.37, p = 0.4). Two other RCTs also showed mixed effects of maca on several semen quality parameters in healthy men. Conclusion: The evidence from the included studies suggests unclear effects of maca on semen quality parameters in both men experiencing infertility and healthy men. However, the total number of RCTs and the total sample size were too small to draw firm conclusions.

Strainer-Separable TiO2 on Halloysite Nanocomposite-Embedded Alginate Capsules with Enhanced Photocatalytic Activity for Degradation of Organic Dyes.

Photocatalysis driven by natural sunlight is an attractive approach to removing pollutants from wastewater. Although TiO2-based photocatalysts using various support nano-materials with high catalytic activity and reusability have been developed for purifying wastewater, the centrifugal separation methods used for the nanocatalysts limit their use for treating large amounts of water. Here, we prepared a TiO2 nano-catalyst supported on a halloysite nanotube (HNT)-encapsulated alginate capsule (TiO2@HNT/Alcap) to recapture the catalysts rapidly without centrifugation. The structure of TiO2@HNT/Alcap was characterized by X-ray diffraction, SEM, and TGA. In our system, the combination of HNTs and alginate capsules (Alcaps) improved the efficiency of adsorption of organic pollutants to TiO2, and their milli = meter scale structure allowed ultra-fast filtering using a strainer. The TiO2@HNT/Alcaps showed ~1.7 times higher adsorption of rhodamine B compared to empty alginate capsules and also showed ~10 and ~6 times higher degradation rate compared to the HNT/Alcaps and TiO2/Alcaps, respectively.

Highly Efficient Adsorption of Anionic Dye on Acid-Treated Halloysite Nanotubes.

The adsorption capability of eosin Y as a model anionic dye on natural halloysite nanotubes (HNTs) and sulfuric acid-treated HNTs as a function of acid treatment time (1 h, 3 h, and 5 h) was examined. Scanning electron microscopy revealed that natural HNTs had a very uniform surface, whereas acid-treated HNTs had a rough surface with structural defects, which increased with acid treatment time. The total specific pore volume and total surface area of the acid-treated HNTs increased due to formation of nanopores in the HNTs via dissolution of the inner AlO6 octahedral layer. With acid treatment, the surface ξ-potentials were positively shifted from -42.9 mV (for the natural HNTs) to -1.9, -3.0, and +1.2 mV after 1, 3, and 5 h, respectively. The adsorption amount (qe) of eosin Y on natural HNTs and the three acid-treated HNTs was 2.3, 125.5, 118.9, and 118.9 mg g-1, respectively, implying that the adsorption capacity of acid-treated HNTs is ~50 times higher than that of natural HNTs. In this study, we clearly demonstrated that acid-treated HNTs can be used as highly efficient nanomaterials for removal of dyes from wastewater containing anionic dyes.

Averaging Pixel Current Adjustment Technique for Reducing Fixed Pattern Noise in the Bolometer-Type Uncooled Infrared Image Sensor.

In this paper, we propose an averaging pixel current adjustment technique for reducing fixed pattern noise (FPN) in the bolometer-type uncooled infrared image sensor. The averaging pixel current adjustment technique is composed of active pixel, reference pixel, and calibration circuit. Polysilicon resistors were used in each active pixel and reference pixel. Resistance deviation among active pixels integrated with the same resistance value cause FPN. The principle of the averaging pixel current adjustment technique for removing FPN is based on the subtraction of dark current of the active pixel from the dark current of the reference pixel. The subtracted current is converted into the voltage, which contains pixel calibration information. The calibration circuit is used to adjust the calibration current. After calibration, the nano-ampere current is output with small deviation. The proposed averaging pixel current adjustment technique is implemented by a chip composed of a pixel array, a calibration circuit, average current generators, and readout circuits. The chip was fabricated using a standard 0.35 µm CMOS process and its performance was evaluated.

Effects of Offset Pixel Aperture Width on the Performances of Monochrome CMOS Image Sensors for Depth Extraction.

This paper presents the effects of offset pixel aperture width on the performance of monochrome (MONO) CMOS image sensors (CISs) for a three-dimensional image sensor. Using a technique to integrate the offset pixel aperture (OPA) inside each pixel, the depth information can be acquired using a disparity from OPA patterns. The OPA is classified into two pattern types: Left-offset pixel aperture (LOPA) and right-offset pixel aperture (ROPA). These OPAs are divided into odd and even rows and integrated in a pixel array. To analyze the correlation between the OPA width and the sensor characteristics, experiments were conducted by configuring the test elements group (TEG) regions. The OPA width of the TEG region for the measurement varied in the range of 0.3-0.5 µm. As the aperture width decreased, the disparity of the image increased, while the sensitivity decreased. It is possible to acquire depth information by the disparity obtained from the proposed MONO CIS using the OPA technique without an external light source. Therefore, the proposed MONO CIS with OPA could easily be applied to miniaturized devices. The proposed MONO CIS was designed and manufactured using the 0.11 µm CIS process.

Development and Evaluation of a Reconstitutable Dry Suspension to Improve the Dissolution and Oral Absorption of Poorly Water-Soluble Celecoxib.

This study aims at developing and evaluating reconstitutable dry suspension (RDS) improved for dissolution rate, oral absorption, and convenience of use of poorly water-soluble celecoxib (CXB). Micro-sized CXB particle was used to manufacture nanosuspension by using bead milling and then RDS was made by spray-drying the nanosuspension with effective resuspension agent, dextrin. The redispersibility, morphology, particle size, crystallinity, stability, dissolution, and pharmacokinetic profile of the RDS were evaluated. RDS was effectively reconstituted into nanoparticles in 775.8 ± 11.6 nm. It was confirmed that CXB particles are reduced into needle-shape ones in size after the bead-milling process, and the description of CXB was the same in the reconstituted suspension. Through the CXB crystallinity study using differential scanning calorimetry (DSC) and XRD analysis, it was identified that CXB has the CXB active pharmaceutical ingredient (API)'s original crystallinity after the bead milling and spray-drying process. In vitro dissolution of RDS was higher than that of CXB powder (93% versus 28% dissolution at 30 min). Furthermore, RDS formulation resulted in 5.7 and 6.3-fold higher area under the curve (AUC∞) and peak concentration (Cmax) of CXB compared to after oral administration of CXB powder in rats. Collectively, our results suggest that the RDS may be a potential oral dosage formulation for CXB to improve its bioavailability and patient compliance.

Robust Diagnosis Method Based on Parameter Estimation for an Interturn Short-Circuit Fault in Multipole PMSM under High-Speed Operation.

This paper proposes a diagnosis method for a multipole permanent magnet synchronous motor (PMSM) under an interturn short circuit fault. Previous works in this area have suffered from the uncertainties of the PMSM parameters, which can lead to misdiagnosis. The proposed method estimates the q-axis inductance (Lq) of the faulty PMSM to solve this problem. The proposed method also estimates the faulty phase and the value of G, which serves as an index of the severity of the fault. The q-axis current is used to estimate the faulty phase, the values of G and Lq. For this reason, two open-loop observers and an optimization method based on a particle-swarm are implemented. The q-axis current of a healthy PMSM is estimated by the open-loop observer with the parameters of a healthy PMSM. The Lq estimation significantly compensates for the estimation errors in high-speed operation. The experimental results demonstrate that the proposed method can estimate the faulty phase, G, and Lq besides exhibiting robustness against parameter uncertainties.

Fabrication and Characterization of Graphene-Based Electrochemical Sensors for Glucose Measurement.

Glucose in the blood is generally measured by electrochemical method using glucose oxidase (GOx) which acts as enzymes and reduced graphene oxide (rGO) composite. The rGO, which has low dispersibility, reduces the sensing capability of sensors. In order to solve this problem, the rGO electrodes with the addition of polyvinylpyrrolidone (PVP) have been reported. However, rGO with low electrical conductivity and mobility is not compatible to the electrochemical system. In this study, graphene with excellent electrical properties was added to PVP protected rGO. The rGO was synthesized using a Hummer and Offeman's method. Graphene was synthesized using chemical vapor deposition (CVD) with a Cu catalyst. Platinum (Pt) electrodes, Ag/AgCl, and PVP protected rGO were used as working electrode, reference electrode, and counter electrode, respectively. Surface morphology and structural properties of graphene were analyzed using atomic force microscopy (AFM), Raman spectroscopy, and Fourier transform infrared spectroscopy (FT-IR). Cyclic voltametry (CV) and I-V probe station were used to analyze the performance of the electrodes. Glucose concentration was systematically varied and the reduction current was monitored using I-V probe station.

Implementation of an integrated op-amp based chaotic neuron model and observation of its chaotic dynamics.

This paper presents a fully integrated circuit implementation of an operational amplifier (op-amp) based chaotic neuron model with a bipolar output function, experimental measurements, and analyses of its chaotic behavior. The proposed chaotic neuron model integrated circuit consists of several op-amps, sample and hold circuits, a nonlinear function block for chaotic signal generation, a clock generator, a nonlinear output function, etc. Based on the HSPICE (circuit program) simulation results, approximated empirical equations for analyses were formulated. Then, the chaotic dynamical responses such as bifurcation diagrams, time series, and Lyapunov exponent were calculated using these empirical equations. In addition, we performed simulations about two chaotic neuron systems with four synapses to confirm neural network connections and got normal behavior of the chaotic neuron such as internal state bifurcation diagram according to the synaptic weight variation. The proposed circuit was fabricated using a 0.8-µm single poly complementary metal-oxide semiconductor technology. Measurements of the fabricated single chaotic neuron with ± 2.5 V power supplies and a 10 kHz sampling clock frequency were carried out and compared with the simulated results.

Results of a phase III, 8-week, multicenter, prospective, randomized, double-blind, parallel-group clinical trial to assess the effects of amlodipine camsylate versus amlodipine besylate in Korean adults with mild to moderate hypertension.

BACKGROUND: Amlodipine besylate has been used in Korea for the treatment of hypertension for >17 years, with well-established efficacy and tolerability. Amlodipine camsylate is a newer formulation developed for generic use. It has been assessed in terms of physical stability and pharmacokinetic and pharmacodynamic properties and been found to be effective in lowering blood pressure in preclinical and Phase I and II trials. However, to date, no studies have compared the clinical effectiveness of amlodipine camsylate and amlodipine besylate in treating hypertension. OBJECTIVE: This study was designed to determine the effectiveness and tolerability of amlodipine camsylate compared with amlodipine besylate in Korean patients with mild to moderate hypertension. METHODS: This Phase III, 8-week, prospective, randomized, double-blind, parallel-group study was conducted in 13 cardiology centers across the Republic of Korea. Male and female Korean patients aged 18 to 75 years having uncomplicated, mild to moderate, essential hypertension (sitting diastolic blood pressure [SiDBP] 90-<110 mm Hg) and receiving no antihypertensives in the 2 weeks before randomization were eligible. Patients were randomly assigned to receive oral treatment with amlodipine camsylate or amlodipine besylate. For the first 4 weeks, patients received amlodipine 5 mg QD (morning). After 4 weeks, if either blood pressure was > or =140/ > or =90 mm Hg or SiDBP had not decreased by > or =10 mm Hg from baseline, the dose of amlodipine was increased to 10 mg QD for 4 weeks. Trough blood pressure and heart rate were measured in duplicate with the patient in the sitting position at each clinic visit (baseline [week 0] and weeks 4 and 8 of treatment); mean values were calculated and recorded. At weeks 4 and 8, tolerability was assessed using history taking and laboratory analysis, and compliance was assessed using pill counts. The primary end point was change from baseline in SiDBP at week 8. Secondary end points were change from baseline in sitting systolic blood pressure (SiSBP) at week 8 in the total population and in the subgroup of patients who had previously received antihypertensive treatment versus those who had not. RESULTS: A total of 189 patients were enrolled (mean age, 53 years; 105 women, 84 men; mean body weight, 65.8 kg). One patient in the amlodipine camsylate group dropped out of the study at week 0 of treatment (this patient did not use any study medication) and was excluded from the modified intent-to-treat (ITT) analysis. Thus, 188 patients were treated and included in the ITT analysis (94 patients per treatment group; ITT analysis); 161 patients were included in the perprotocol (PP) analysis (n = 80 for amlodipine camsylate, n = 81 for amlodipine besylate) (14 patients in the amlodipine camsylate group and 13 patients in the amlodipine besylate group were excluded from the PP analysis due to consistent withdrawal or protocol violation). Mean (SD) SiSBP and SiDBP were significantly decreased from baseline in both groups (amlodipine camsylate, from 146.7 [12.3]/96.6 [5.4] to 127.9 [14.8]/83.4 [7.7] mm Hg [both, P < 0.001]; amlodipine besylate, from 146.8 [12.8]/96.7 [5.1] to 128.0 [10.1]/83.8 [7.5] mm Hg [both, P < 0.001]). The differences in SiSBP/SiDBP between the 2 groups at week 8 were not significant. The SiDBP response rates in the subgroups that had and had not been previously treated with antihypertensives were statistically similar (56/69 [81.2%] and 83/92 [90.2%], respectively). The prevalences of clinical adverse events (AEs) were not significantly different between the 2 treatment groups (amlodipine camsylate, 27.3 %; amlodipine besylate, 28.7%). The most common AEs were dizziness and dyspnea (both in 3/94 [3.2%] and 1/94 [1.1%] patients who received amlodipine camsylate and amlodipine besylate, respectively). CONCLUSION: The effectiveness and tolerability of amlodipine camsylate were not significantly different from those of amlodipine besylate in these Korean adults with mild to moderate hypertension.