Characteristics of High Content Steel Briquettes Using Nanosized Solid Binders.

In this study, we investigated the characteristics of high-content steel briquettes produced using various nanoscale solid binders and steel byproducts (SS, SCS, SLD, and BSD). The average particle size was 0.171 nm for S5, 0.065 nm for S1, 0.058 nm for S4, and 0.040 nm for S2 and S3. The SEM-EDS analysis of the solid power binder resulted in mostly rectangular images. The compressive strength of the high-content steel briquettes was 120 kgf/cm², with the highest HSL1 using S4 binders. The compressive strength of the high-content steel briquettes was in the order of HSS4 > HSS1 > HSS3 > HSS5 > HSS2.

Impact of the COVID-19 pandemic on the lifestyle, mental health, and quality of life of adults in South Korea.

OBJECTIVE: The COVID-19 pandemic continues to pose significant challenges to nations. The Korean government aimed to mitigate the spread of COVID-19 through stay-at-home strategies and maintaining social distance, which are likely to result in major changes in the lifestyle, mental health, and quality of life of citizens. This study aimed to investigate the impact of the COVID-19 pandemic on these factors in Koreans over 20 years old. METHODS: The study sample consisted of 104 adults in South Korea aged over 20 years. An online survey was conducted between August and October 2020, in which participants were asked to complete the Yonsei Lifestyle Profile to assess lifestyle changes, the Center for Epidemiological Studies-Depression Scale, and the World Health Organization Quality of Life Scale abbreviated version. To investigate the changes in people's lifestyles, depression, and quality of life post COVID-19, descriptive statistics were calculated for these indicators before and after the onset of the pandemic. The p-value was two-sided, and values <0.05, were regarded as statistically significant. RESULTS: There was a significant decline in physical and other meaningful activities, including activities of daily living, leisure, social activity, and education. However, there were no significant changes in nutrition, except in the consumption of carbohydrates and minerals. Participants reported that their quality of life and mental health had decreased after the pandemic struck. CONCLUSIONS: We obtained novel data on the changes in the lifestyle, mental health, and quality of life of South Korean adults before and after the onset of the pandemic. The results of our study may assist health policymakers and practitioners in the development of health education or relevant interventions to deal with the pandemic situation as well as future crises.

Colorimetric Textile Sensor for the Simultaneous Detection of NH3 and HCl Gases.

For the immediate detection of strong gaseous alkalis and acids, colorimetric textile sensors based on halochromic dyes are highly valuable for monitoring gas leakages. To date, colorimetric textile sensors for dual-gas detection have usually been fabricated by electrospinning methods. Although nanofibrous sensors have excellent pH sensitivity, they are difficult to use commercially because of their low durability, low productivity, and high production costs. In this study, we introduce novel textile sensors with high pH sensitivity and durability via a facile and low-cost screen-printing method. To fabricate these textiles sensors, Dye 3 and RhYK dyes were both incorporated into a polyester fabric. The fabricated sensors exhibited high detection rates (<10 s) and distinctive color changes under alkaline or acidic conditions, even at low gas concentrations. Furthermore, the fabricated sensors showed an outstanding durability and reversibility after washing and drying and were confirmed to contain limited amounts of hazardous materials. Thus, our results show that the fabricated textile sensors could be used in safety apparel that changes its color in the presence of harmful gases.

Fabrication of piezoelectric poly(L-lactic acid)/BaTiO3 fibre by the melt-spinning process.

Poly(L-lactic acid) (PLLA) based piezoelectric polymers are gradually becoming the substitute for the conventional piezoelectric ceramic and polymeric materials due to their low cost and biodegradable, non-toxic, piezoelectric and non-pyroelectric nature. To improve the piezoelectric properties of melt-spun poly(L-lactic acid) (PLLA)/BaTiO3, we optimized the post-processing conditions to increase the proportion of the ß crystalline phase. The α → ß phase transition behaviour was determined by two-dimensional wide-angle x-ray diffraction and differential scanning calorimetry. The piezoelectric properties of PLLA/BaTiO3 fibres were characterised in their yarn and textile form through a tapping method. From these results, we confirmed that the crystalline phase transition of PLLA/BaTiO3 fibres was significantly enhanced under the optimised post-processing conditions at a draw ratio of 3 and temperature of 120 °C during the melt-spinning process. The results indicated that PLLA/BaTiO3 fibres could be a one of the material for organic-based piezoelectric sensors for application in textile-based wearable piezoelectric devices.

Washable Colorimetric Nanofiber Nonwoven for Ammonia Gas Detection.

The colorimetric sensor is a facile, cost-effective, and non-power-operated green energy material for gas detection. In this study, the colorimetric sensing property of a meta-aramid/dye 3 nanofiber sensor for ammonia (NH3) gas detection was investigated. This colorimetric sensor was prepared using various dye 3 concentrations via electrospinning. Morphological, thermal, structural, and mechanical analyses of the sensor were carried out by field-emission scanning electron microscopy, thermogravimetric analysis, Fourier-transform infrared spectroscopy, and a universal testing machine, respectively. A homemade computer color matching machine connected with a gas flow device characterized the response of the meta-aramid/dye 3 nanofiber colorimetric sensor to various exposure levels of NH3 gas. From the results, we confirmed that this colorimetric green energy sensor could detect ammonia gas in the concentration of 1-10 ppm with a sensing response time of 10 s at room temperature. After washing with laundry detergent for 30 min, the colorimetric sensors still exhibited sensing property and reversibility.

Methylammonium Iodide-Mediated Controlled Crystal Growth of CsPbI2Br Films for Efficient and Stable All-Inorganic Perovskite Solar Cells.

A high-quality perovskite film is a key aspect contributing to high photovoltaic performance of all-inorganic perovskite solar cells. We herein demonstrate that the addition of methylammonium iodide (MAI) influences effectively both the tailored film morphology and precise crystal growth to construct high-quality CsPbI2Br films. It is found that an MAI additive retards the crystallization kinetics to control the inorganic perovskite films to form a highly crystalline α-CsPbI2Br structure consisting of microsized grains with reduced defect density. The optimal MAI additive (10 wt %) achieves a power conversion efficiency (PCE) of 10.40% for the CsPbI2Br-based all-inorganic perovskite solar cells, which is >30% enhancement from 6.95% of the pristine one. The solar cells employing the MAI additive possess high operational and thermal stability, retaining >70% of the original PCE after aging for 1500 h in ambient atmosphere and under continuous heating at 85 °C for 30 h, respectively. The photovoltaic performance with an indoor light source was also examined using a white light-emitting diode (6500 K, 1000 lux), showing promising PCEs of 23.51% with a stabilized power output of 21.15%.

A Highly Porous Nonwoven Thermoplastic Polyurethane/Polypropylene-Based Triboelectric Nanogenerator for Energy Harvesting by Human Walking.

: A highly porous nonwoven thermoplastic polyurethane (TPU)/Polypropylene (PP) triboelectric nanogenerator (N-TENG) was developed. To fabricate the triboelectric layers, the TPU nanofiber was directly electrospun onto the nonwoven PP at different basis weights (15, 30, and 50 g/m2). The surface morphologies and porosities of the nonwoven PP and TPU nanofiber mats were characterized by field-emission scanning electron microscopy and porosimetry. The triboelectric performance of the nonwoven TPU/PP based TENG was found to improve with an increase in the basis weight of nonwoven PP. The maximum output voltage and current of the TPU/PP N-TENG with 50% PP basis weight reached 110.18 ± 6.06 V and 7.28 ± 0.67 µA, respectively, due to high air volume of nonwoven without spacers. In order to demonstrate its practical application as a generator, a TPU/PP N-TENG-attached insole for footwear was fabricated. The N-TENG was used as a power source to turn on 57 light-emitting diodes through human-walking, without any charging system. Thus, owing to its excellent energy-conversion performance, simple fabrication process, and low cost, the breathable and wearable nonwoven fiber-based TENG is suitable for large-scale production, to be used in wearable devices.

Nano- And Microfiber-Based Fully Fabric Triboelectric Nanogenerator For Wearable Devices.

The combination of the triboelectric effect and static electricity as a triboelectric nanogenerator (TENG) has been extensively studied. TENGs using nanofibers have advantages such as high surface roughness, porous structure, and ease of production by electrospinning; however, their shortcomings include high-cost, limited yield, and poor mechanical properties. Microfibers are produced on mass scale at low cost; they are solvent-free, their thickness can be easily controlled, and they have relatively better mechanical properties than nanofiber webs. Herein, a nano- and micro-fiber-based TENG (NMF-TENG) was fabricated using a nylon 6 nanofiber mat and melt blown nonwoven polypropylene (PP) as triboelectric layers. Hence, the advantages of nanofibers and microfibers are maintained and mutually complemented. The NMF-TENG was manufactured by electrospinning nylon 6 on the nonwoven PP, and then attaching Ni coated fabric electrodes on the top and bottom of the triboelectric layers. The morphology, porosity, pore size distribution, and fiber diameters of the triboelectric layers were investigated. The triboelectric output performances were confirmed by controlling the pressure area and basis weight of the nonwoven PP. This study proposes a low-cost fabrication process of NMF-TENGs with high air-permeability, durability, and productivity, which makes them applicable to a variety of wearable electronics.

Fabrication of Colorimetric Textile Sensor Based on Rhodamine Dye for Acidic Gas Detection.

For the immediate detection of gaseous strong acids, it is advantageous to employ colorimetric textile sensors based on halochromic dyes. Thus, a rhodamine dye with superior pH sensitivity and high thermal stability was synthesized and incorporated in nylon 6 and polyester fabrics to fabricate textile sensors through dyeing and printing methods. The spectral properties and solubility of the dye were examined; sensitivity to acidic gas as well as durability and reversibility of the fabricated textile sensors were investigated. Both dyed and printed sensors exhibited a high reaction rate and distinctive color change under the acidic condition owing to the high pH sensitivity of the dye. In addition, both sensors have outstanding durability and reversibility after washing and drying.