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Tetramethylammonium hydroxide (TMAH), which is a chemical used in the electronic industry, is classified as a hazardous material (HAZMAT class 8) that threatens aquatic ecosystems and human health. Consequently, numerous studies have attempted to remove TMAH using various treatment methods, including advanced oxidation processes such as ozone, UV, or Fenton oxidation. However, prior research has indicated a low kinetic rate of TMAH removal. In this context, we proposed an alternative to TMAH degradation by combining a cold plasma (CP) process with periodate oxidation. As for the kinetics of TMAH removal, the kinetic constant was improved by 5 times (0.1661 and 0.0301 for 40.56 and 2.2 W, respectively) as the electric power of a CP system increased from 2.2 to 40.56 W. The kinetic constant of a 40.56 W CP system further increased by 54 times (1.6250) than a 2 W CP system when 4 mM periodate was used simultaneously. As a result, the integrated CP/periodate system represented 2 times higher TMAH removal efficiency (29.5%) than a 2 W CP system (14.4%). This excellent TMAH degradation capability of the integrated CP/periodate system became pronounced at pH 10 and 25 °C. Overall, the integrated CP/periodate system is expected to be a viable management option for effectively controlling hazardous TMAH chemicals. [Display omitted] • The integrated CP/periodate system successfully removed TMAH. • The CP/periodate process showed a higher kinetic constant than the other processes. • The optimal CP power and periodate concentration led to a 2 times higher removal rate. • The CP process reduced toxicity by over 50% in 1 h. • The integrated CP/periodate system performed best at pH 10 and 25 °C. [ABSTRACT FROM AUTHOR]

Myocardial ischemia-reperfusion (IR) generates stress-induced senescent cells (SISCs) that play an important role in the pathophysiology of adverse cardiac remodeling and heart failure via secretion of pro-inflammatory molecules and matrix-degrading proteases. Thus, removal of senescent cells using a senolytic drug could be a potentially effective treatment. However, clinical studies on cancer treatment with a senolytic drug have revealed that systemic administration of a senolytic drug often causes systemic toxicity. Herein we show for the first time that local delivery of a senolytic drug can effectively treat myocardial IR injury. We found that biodegradable poly(lactic-co-glycolic acid) nanoparticle-based local delivery of a senolytic drug (ABT263-PLGA) successfully eliminated SISCs in the IR-injured rat hearts without systemic toxicity. Consequently, the treatment ameliorated inflammatory responses and attenuated adverse remodeling. Surprisingly, the ABT263-PLGA treatment restored the cardiac function over time, whereas the cardiac function decreased over time in the no treatment group. Mechanistically, the ABT263-PLGA treatment not only markedly reduced the expression of pro-inflammatory molecules and matrix-degrading proteases, but also induced macrophage polarization from the inflammatory phase to the reparative phase via efferocytosis of apoptotic SISCs by macrophages. Therefore, the senolytic strategy with ABT263-PLGA in the early stage of myocardial IR injury may be an effective therapeutic option for myocardial infarction. This study describes a local injection of senolytic drug-loaded nanoparticles that selectively kills stress-induced senescent cells (SISCs) in infarcted heart. Removal of SISCs decreases inflammatory cytokines and normal cell death. We firstly revealed that further efferocytosis of apoptotic senescent cells by macrophages restores cardiac function after myocardial ischemia-reperfusion injury. Importantly, a local injection of senolytic drug did not exhibit systemic toxicity, but a systemic injection did. Our findings not only spotlight the basic understanding of therapeutic potential of senolysis in infarcted myocardium, but also pave the way for the further application of senolytic drug for non-aging related diseases. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, a partial honeycomb land was proposed for improving the sealing performance of a labyrinth seal which has been widely applied to the low-pressure section of a gas turbine. The partial honeycomb land in this experiment is distinguished by a solid strip under the fin of the honeycomb land labyrinth seal. The tested fin front angle of the labyrinth seal was 60°, and the clearance size ranged from 1.15 to 2.82 times the fin tip thickness. The honeycomb cell diameter was 4 times the fin tip thickness, and the honeycomb cell depth was 10.58 times the fin tip thickness. The experiments were conducted under pressure ratios ranging from 1.1 to 2.5, and it was confirmed that the application of the partial honeycomb land resulted in a maximum 39.4 % reduction in the discharge coefficient. Computational Fluid Dynamics (CFD) analysis revealed that the application of the partial honeycomb land altered the flow of leakage, leading to a decrease in the effective clearance. It was confirmed that, for the honeycomb labyrinth seal with smaller clearance, the sealing performance degradation for the conventional honeycomb land case due to the weakened vortex inside the fin cavity was not observed for the case with partial honeycomb land. Therefore, the improvement in sealing performance of the labyrinth seal with partial honeycomb land was attributed not only to the reduction in the effective leakage flow area, but also to the maintained vortex size, which induced resistance to the leakage flow even in smaller clearance conditions. [ABSTRACT FROM AUTHOR]

Quorum quenching (QQ) has been extensively studied in sewage treatment membrane bioreactors (MBRs) to alleviate biofouling, but its application in industrial-wastewater MBRs remains limited. This study confirmed the applicability of QQ in MBRs treating wastewater from the display manufacturing process. QQ alginate and QQ polyvinyl alcohol (PVA)/alginate beads, which entrapped Bacillus sp. SDC-U1, a QQ isolate from tetramethylammonium hydroxide (TMAH)-wastewater treatment sludge, were applied to a lab-scale MBR treating real wastewater containing TMAH, a developer used in the display manufacturing process. To immobilize pH-sensitive SDC-U1 on PVA/alginate beads, the first cross-linking solution's pH was adjusted to 5, followed by a 4 h incubation in Luria-Bertani broth to enhance the activity of SDC-U1. MBRs with QQ alginate and QQ PVA/alginate beads showed a 40 % and 365 % longer time to reach 30 kPa TMP, respectively, compared to MBRs without beads. QQ beads significantly reduced the concentration of various N -acyl homoserine lactones, which are signaling molecules involved in quorum sensing, in the MBR. The observation of biofilm on the membrane surface confirmed the biofouling mitigation by QQ application. This study demonstrates that biofouling can be effectively mitigated using appropriate QQ bacteria and their immobilization methods in industrial wastewater MBRs containing toxic substances like TMAH. [Display omitted] • Quorum quenching (QQ) could mitigate biofouling in display wastewater treatment MBR. • Bacillus sp. SDC-U1 was immobilized on polyvinyl alcohol(PVA)/alginate bead. • A method for immobilizing pH-sensitive bacteria on PVA/alginate beads was developed. • QQ PVA/alginate beads lengthened the recovery cleaning cycle by 4.8 times. • The activity of QQ PVA/alginate bead was maintained in the MBR for over 50 d. [ABSTRACT FROM AUTHOR]

Conversion of carbon dioxide (CO 2) to useful chemicals is considered a potential solution to resolve the climate threat. In this study, a facile metal-organic framework (MOF)-mediated strategy to obtain an efficient electrocatalyst for the synthesis of methane (CH 4) is suggested. Cu-based MOF-74 was chosen as the precursor, which was electrochemically reduced to obtain Cu nanoparticles (NPs). The porous structure of the MOF serves as a template for the synthesis of isolated Cu NP clusters with high catalytic activities and high efficiencies for the CH 4 production in the electrochemical CO 2 reduction reaction. The MOF-derived Cu NPs demonstrate high Faradaic efficiency (>50%) for the CH 4 production with suppressed C 2 production, and 2.3-fold higher methanation activity at −1.3 V (vs. RHE) compared to the commercial Cu NPs. [ABSTRACT FROM AUTHOR]

Abstract An in-depth study on the photovoltaic characteristics under indoor lights, i.e., light-emitting diode (LED), fluorescent lamps, and halogen lamps, was performed with varying the photoactive layer thickness (120–870 nm), by comparing those under 1-sun condition. The semi-crystalline mid-gap photoactive polymer, poly[(2,5-bis(2-hexyldecyloxy)phenylene)- alt -(5,6-difluoro-4,7-di(thiophen-2-yl)benzo[ c ][1,2,5]thiadiazole)] (PPDT2FBT) and a fullerene derivative, [6,6]-phenyl C 71 butyric acid methyl ester (PC 70 BM) were used as a photoactive layer. In the contrary to the measurements under 1-sun condition, the indoor devices show a clearly different behavior, showing the thickness tolerant short-circuit current density (J SC) and fill factor (FF) values with 280–870 nm thick photoactive layers. The retained J SC and FF values of thick indoor devices were discussed in terms of the parasitic resistance effects based on the single-diode equivalent circuit model. The much lower series/shunt resistance (R s/ R P) ratio was measured with thick photoactive layer (≥280 nm), resulting in negligible decreases in the J SC and FF values even with a 870-nm-thick active layer under the LED condition. Under 1000 lx LED light, the PPDT2FBT:PC 70 BM device showed an optimum power conversion efficiency (PCE) of 16% (max power density, 44.8 μW/cm2) with an open-circuit voltage of 587 mV, a J SC of 117 μA/cm2, and a FF of 65.2. The device with a 870-nm-thick active layer still exhibited an excellent performance with a PCE of 12.5%. These results clearly suggest that the critical parasitic resistance effects on the performance vary depending on the light illumination condition, and the large R P associated with the viable thick photoactive layer and the well-matched absorption (of photoactive layer) with the irradiance spectrum (of indoor light) are essential to realize efficient indoor photovoltaic cells with high J SC and FF. Graphical abstract The semi-crystalline polymer (PPDT2FBT) and a fullerene derivative (PC 70 BM) were used as a photoactive layer of organic photovoltaics. By varying the thickness of the photoactive layer (120–870 nm), we compared the performance under 1-sun and the indoor lights (LED, fluorescent and halogen). Unlike 1-sun condition, short-circuit current density and fill factor remained high under indoor illumination even as the active layer thickness was increased from 280 to 870 nm. fx1 Highlights • OPVs with a PPDT2FBT:PC 70 BM-based photoactive layer were fabricated. • The thickness of the photoactive layers was varied from 120 nm to 870 nm. • The J SC and fill factor remained high even with the 870-nm-thick photoactive layer. • PPDT2FBT:PC 70 BM-based OPVs yielded 16.0 % efficiency under an 1000 lx LED lamp. [ABSTRACT FROM AUTHOR]

Highlights • Enhanced durability performance in silicate-surface impregnated concrete. • SEM analysis for quantitative surface analyzing. • Considerations of submerged and spraying period of silicate and TiO 2. • Verification of durability and mechanical performance through surface impregnation. • Verification of self-cleaning and self-purification through TiO 2. Abstract This paper proposes an integrated concrete surface treatment with surface enhancement via silicate impregnation and surface spraying with TiO 2 (a photocatalyst). In this work, two types of silicate-based materials, sodium alumina silicate (SAS) and colloidal silica (COS) were used. Various tests were carried out to characterize the silicate properties and engineering performance of the impregnated concrete. In addition, the purification performance in concrete sprayed with TiO 2 was investigated. Concrete impregnated with silicate and sprayed with TiO 2 showed an improvement in the durability and mechanical performance because of the addition of the CSH gel and TiO 2 barrier. After impregnation, the TiO 2 applied by spraying retained good performance for the removal of acetaldehyde and methyl orange. [ABSTRACT FROM AUTHOR]

Herein, a new strategy for micro/nanoparticles removal in water using a triboelectric nanogenerator (TENG) is demonstrated. Removal process based on electrophoretic force can extract particles from water by its zeta potential due to the electric fields generated by the TENG, in other words, higher performance TENG removes more particles. High-performance TENG based on a three-dimensional porous-pyramid polydimethylsiloxane shows a power output nearly three times higher than that of a flat film-based TENG. With the proposed TENG, the removal rate is 21.4%, which is 5.6 times higher than that for the flat TENG (3.8%). By measuring the coverage area of the particles attached to the electrode, it was found that the removal of particles was significantly affected by the output voltage and operation time of the TENG. A TENG-driven self-powered electrophoretic system that removes sub-micron nanoparticles of polystyrene, CdSe/CdZnS, ZnO, and SiO 2 is successfully demonstrated. [Display omitted] • A micro/nanoparticles removal system based on electrophoresis with high output voltage triboelectric nanogenerator. • Proposed porous pyramid PDMS based TENGs generated 464 V which is 4 times higher than flat PDMS based TENGs. • High performance TENGs removed the toxic particles 5.6 times more than flat one. • Through the proposed removal process, plastic, heavy metal composite, ceramic and oxide material were successfully removed. [ABSTRACT FROM AUTHOR]

Piezoelectric semiconductor materials have emerged as the most attractive material for nanogenerator (NG)-based prototype applications, such as piezotronics, piezophotonics and energy harvesting, due to the coupling of piezoelectric and semiconducting dual properties. Understanding the mechanisms for high power generation, charge transport behavior, energy band modulations, and role of depletion width in piezoelectric semiconducting p-n junction, through piezoelectric charges developed by external mechanical strains, are essential for various NGs. Here, we demonstrate enhancement of the output power of one-dimensional zinc oxide (ZnO) nanowires (NWs)-based NG using a p-type semiconductor polymer, by controlling their energy band at depletion width in the piezoelectric semiconducting p-n junction interface and native defects presented in as-grown ZnO NWs. The piezoelectric output performance from the P3HT-coated ZnO NWs-based NG was several times higher than that from the pristine ZnO NWs-based NG, under application of the same vertical compressive strain. Holes from the p-type P3HT polymer significantly reduced the piezoelectric potential screening effect caused by free electrons in ZnO. Theoretical investigations using COMSOL multiphysics software were also carried out, in order to understand the improvement in the performance of surface passivated ZnO NWs-based NG, in terms of free carriers concentration and holes diffusion, due to the formation of p-n junction at the interface of ZnO and P3HT, and depletion width change. [ABSTRACT FROM AUTHOR]

• Holistic approach to obtaining the optimum torrefaction condition of spent coffee ground. • The fuel properties of torrefied spent coffee grounds were studied using proximate, elemental, gas and FTIR analysis. Excessive use of fossil fuels has contributed significantly to global warming and the impending energy crisis, necessitating the promotion and development of alternative energy sources to achieve green energy or energy neutrality. Converting waste biomass into energy has a significance impact in solid waste management. Spent coffee grounds (SCG) are the primary residue from the coffee industry generated during the coffee brewing process. This study, therefore, aims to improve the fuel properties of SCG via torrefaction and investigates the characteristics of torrefied products. A horizontal tubular reactor, at temperatures ranging from 250 °C to 350 °C at 20 °C intervals, and residence times ranging from 0 to 30 min with 10-min intervals, were utilized for torrefaction. The associated physical and chemical transformations in SCG torrefaction were investigated using proximate and ultimate analysis, gas composition, thermogravimetric and derivative analyses along with Fourier Transform Infrared Spectroscopy (FTIR). The mass and energy yields decreased while the higher heating value increased with the increase in torrefaction temperature. Additionally, the decrease in the oxygen content and increase in the fixed carbon content helped to improve the fuel properties of the SCG. A torrefaction temperature of 290 °C and a residence time of 10 min was found to be the optimal conditions for SCG torrefaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • QQ strains were isolated from MBR used to treat wastewater containing toxic TMAH. • QQ isolates, SDC-U1 and -A8, showed promising QQ activity in the presence of TMAH. • SDC-U1 and -A8 exhibited high growth rates under aerobic and anaerobic conditions. • SDC-U1 and -A8 inhibited the biofilm formation of PAO1 and activated sludge. N -acylhomoserine lactone (AHL)-based bacterial communication through quorum sensing (QS) is one of the main causes of biofouling. Although quorum quenching (QQ) has proven to be an effective strategy against biofouling in membrane bioreactors (MBRs) for municipal wastewater treatment, its applicability for industrial wastewater treatment has rarely been studied. This is the first study to isolate QQ strains from the activated sludge used to treat industrial wastewater containing toxic tetramethylammonium hydroxide (TMAH) and 1-methyl-2-pyrrolidinone. The two QQ strains from genus Bacillus (SDC-U1 and SDC-A8) survived and effectively degraded QS signals in the presence of TMAH. They also showed resistance to toxic byproducts of TMAH degradation such as ammonium and formaldehyde. They effectively reduced the biofilm formation of Pseudomonas aeruginosa PAO1 and mixed community of activated sludge. The strains isolated in this study thus have the potential to be employed to reduce membrane biofouling in MBRs during the treatment of TMAH-containing wastewater. [ABSTRACT FROM AUTHOR]

Highlights: [•] Demonstration of oxy-coal combustion is planned for the Youngdong boiler by retrofit. [•] The retrofit boiler can achieve good combustion in both air- and oxy-coal modes. [•] The wide cross-section in the burner zone increases the contribution of char gasification. [•] Supply of most oxidizers through burners lowers the wall heat flux in oxy-coal modes. [ABSTRACT FROM AUTHOR]

Abstract: We have investigated effects of the solvent polarity of a polymeric insulator on field-effect mobility in a pentacene used thin-film transistor (TFT). In our work, we used a poly(4-vinylphenol) (PVP) as a gate insulator to dissolve three different solvents. As the solvent polarity of the PVP solution is increased, the field-effect mobility is dramatically increased by a factor of five (from 0.30cm2/Vs to 1.51cm2/Vs). We found that an increase of polar solvents in polymeric insulators results in improved electrical properties in the organic TFTs. [Copyright &y& Elsevier]

Abstract: We describe how the charge carrier injection and transport are influenced by thermal cracks in a 6,13-bis(triisopropylsilylethynyl) (TIPS) pentacene film in terms of the contact resistance and the channel resistance in a TIPS pentacene thin-film transistor (TFT). Through a post-thermal annealing (PTA) process at a certain temperature Ta , the high structural order of TIPS-pentacene molecules is produced without thermal cracks, the carrier mobility of the TIPS pentacene TFT is maximized, and both the contact resistance and the channel resistance are minimized. Our quantitative description of the relationship between the PTA treatment and the interfacial resistance behavior would provide a useful basis for understanding the thermal stability and the electrical performance of a solution-processed organic TFT. [Copyright &y& Elsevier]

• PEMFCs with 0.3, 0.5, and 1.0 mm-thick flow channels/ribs are tested. • The effect by increasing operating pressure in different channels is investigated. • Diffusion of reactants by varying channels and pressure are investigated. • Non-dimensional flow characteristics are investigated based on Sh, Re and Sc. Variation in performance of polymer electrolyte membrane fuel cells (PEMFCs) is analyzed, focusing on operating pressure and change in the width of the flow channels. At 0 bar, the maximum power densities are 431, 569, and 799 mW/cm2 with the width of 1.0, 0.5, and 0.3 mm, and at 3.0 bar, the maximum power densities are enhanced to 650, 829, and 914 mW/cm2, respectively. A pair of bipolar plates having the largest width exhibit the highest effect of the pressurized operation, and thus the most considerable change rate in maximum power density (50.8%). To investigate the diffusion phenomenon in the flow channels, a correlation is derived by introducing non-dimensional parameters. The dimensionless number associated with vertical diffusion, Sherwood number, decreases with lessening the width of flow channels and increasing the operating pressure, and diffusion characteristics of PEMFCs are generalized through Sherwood number correlation consisting of Reynolds and Schmidt number. Polymer electrolyte membrane fuel cell; Electrochemical impedance spectroscopy; Flow channel; Diffusion; Sherwood number [Display omitted] [ABSTRACT FROM AUTHOR]

A multi-walled carbon nanotube (CNT) sheet was employed and investigated as a microporous layer (MPL) of proton exchange membrane fuel cell (PEMFC). The CNT sheet was synthesized via floating catalyst chemical vapor deposition method. The CNT sheet MPLs with the thickness of 15, 30, and 100 μm were prepared and compared with a commercial carbon-black MPL. As a result, it was found that the PEMFC with the 15-μm-thick CNT sheet MPL showed high electrochemical performance, and it outtopped the conventional PEMFC. The 15-μm-thick CNT sheet MPL increased the peak power density by 50.9% in air-supplied cathode and 20.9% in pure oxygen-supplied cathode compared to the conventional PEMFC. Through electrochemical impedance analyses, it was found that the CNT sheet MPL effectively decreased a charge transfer resistance, which is attributed to the improved reaction kinetics and mass transport through the MPL. [Display omitted] • CNT sheet was employed as a microporous layer for PEMFCs. • CNT sheet was fabricated via cost-effective floating catalyst CVD method. • Electrochemical performance was increased by 20.9%–50.9% through this approach. • EIS and SEM were employed to further investigate the performance enhancement. [ABSTRACT FROM AUTHOR]

• This study presents OTFT manufacturing and electrical characteristics. • We used DPP-DTT organic channel and Parylene-C gate dielectric. • The OTFT has flexible characteristics because it was made on a Parylene-C substrate. • Most of the manufacturing process was achieved through the solution process. Organic thin-film transistors (OTFTs) fabricated on Parylene-C substrates have the advantages of a simple process, low cost, and flexible characteristics. This study introduces the manufacturing method and electrical characteristics of an OTFT using organic materials as the substrate, gate dielectric, and channel material. PDPP2T-TT-OD(DPP-DTT) is used as the channel material, which is a highly mobile p-type polymer with good air stability. The proposed OTFT device has flexible characteristics because it is fabricated on a Parylene-C substrate and can be used even in a curved state. Furthermore, the manufacturing process was largely achieved via a simple, low-cost solution process using spin-coating and photolithography with a photo-curable material. Under flat conditions, the threshold voltage (V TH) is approximately –3 V, the average I ON /I OFF ratio is approximately 105, and the mobility is 0.84 cm2/Vs. [ABSTRACT FROM AUTHOR]

For radiation protection optimization, ICRP proposed dose constraint as quantitative value for planned exposure situation based on representative person concept. The objective of this study is to derive dose constraints for the general public around nuclear power plants in Korea by applying representative person concept. The dose constraints for the general public around NPPs were derived through a total of six steps. The steps consisted of setting source terms, setting exposure pathways and scenarios, setting candidate groups for a critical group decision, setting habit data, calculating radiation doses, and proposing dose constraints. Through these steps, the radiation dose distribution of the general public around the NPPs was obtained, and dose constraints were proposed using the dose distribution. Radiation doses to the general public around all the Korea NPP sites ranged 1.63 × 10−2 to 1.32 × 10−1 mSv/y. Using the dose distribution, 0.15 mSv/y, 0.10 mSv/y, and 0.08 mSv/y were proposed as dose constraints. The dose constraint values derived in this study are proposals. Therefore, it is judged that the dose constraints should need furthermore discussion with regulators, licensees, and radiation protection experts considering societal and economic factors for radiation protection. The proposal for dose constraints developed in this study can be used to optimize radiation protection for the general public around the NPPs. • This study aims to derive the dose constraints for the general public around nuclear power plants (NPPs) in Korea for optimization of radiation protection • The dose constraints were derived using 10-year data of radioactive effluents released from all Korea NPPs and ICRP representative person concept. • Distribution of radiation doses to the general public around all the NPP sites in Korea ranged 1.63 × 10−2 to 1.32 × 10−1 mSv/y. • Three dose constraints, including 0.15 mSv/y, 0.10 mSv/y, and 0.08 mSv/y were finally proposed in this study. [ABSTRACT FROM AUTHOR]

In proton exchange membrane fuel cells (PEMFCs), securing sufficient hydration in perfluorosulfonic acid (PFSA) membrane is considered an indicator of performance and durability. Here, we present a straightforward yet effective strategy that sandwiches the nanoporous carbon nanotube (CNT) sheet between the cathodic gas diffusion backing layer (GDBL) and bipolar plate (BP) of a conventional membrane electrode assembly (MEA). CNT sheets are synthesized through the cost-effective direct spinning method. The carbon source, winding rates, and the number of layers are varied to tailor the thickness and nanoporous morphology of the CNT sheets (5, 15, and 30 μm). CNT interlayer MEAs are evaluated for their performance in various temperature and relative humidity (RH), ranges of 80–120 °C and 25–100% RH. With these nanoporous CNT sheets, reactants disperse homogeneously, enhancing membrane hydration and interfacial contact, thereby fulfilling superior performance compared to conventional under entire conditions. Among CNT interlayers, the 30 μm records a 115.4% enhanced peak power density (0.28 W cm−2) and 89.2% extended durability (∼187 h) than conventional under 120 °C and 25% RH. Our strategy delivers a broader perspective of PEMFCs and other fuel cell types based on their ease of production and reproducibility. [Display omitted] • Nanoporous CNT functional interlayers were prepared by direct spinning. • CNT interlayer notably boosts the performance of PEFMCs under all test conditions. • CNT interlayer also achieves 89.2% extended durability of PEMFCs. • These promising boosting mechanisms were demonstrated and optimized. [ABSTRACT FROM AUTHOR]

In this study, various heat transfer measurement models using infrared (IR) thermography were applied to a flat plate and cylinders to examine the accuracy and suitability of the measurements in a transonic blow-down test facility recently developed at Korea Aerospace University. Experiments were performed under three inlet velocity conditions for the flat plate, and for the cylinders, two diameters, two turbulence intensity levels, and five inlet velocity conditions. The surface temperature distribution during the experiment was acquired using an IR camera, and the surface heat transfer coefficient (HTC) was calculated using four HTC calculation models based on the one-dimensional semi-infinite (1D SI) solid assumption: step change (STEP), Duhamel's superposition (DUH), 1D finite volumetric model (1D FVM), and linear regression model (LRM). The LRM showed minimum deviation with reference correlation for the flat plate heat transfer measurements, while STEP, DUH, and 1D FVM showed increased deviations at higher mainstream velocity conditions. The measurements by LRM at the cylinder stagnation location showed the most comparable value with the reference correlation, whereas STEP and FVM showed about 10% deviation from the reference. It is concluded that the LRM is the most suitable heat transfer calculation model for high velocity tests because the model excludes the ramping data during the transient tests, and it can also obtain the local adiabatic wall temperature experimentally. [ABSTRACT FROM AUTHOR]

In this study, water removal is observed through a transparent fuel cell, and the relationships between it and the responses of voltage and impedance are analyzed. The water flows in the channel are accompanied by voltage soaring. For all studied cases, water flow appearances increase as GDL flooding is induced by supplying more vapor; for example, under a stoichiometry ratio of 2.0, the number of water flow appearances is 0, 3, and 25 for 1800 s as relative humidity increase to 30, 50, and 100%. The average voltage is calculated, and a positive relationship between it and the frequency of water flows is determined. The results reveal that frequent flooding-induced water removal could be one strategy to enhance fuel cell performance. [Display omitted] • The transparent PEMFC is fabricated for observation of water flows at channels. • The water flows appear with every fluctuation of the voltage jump and impedance drop. • GDL flooding induced by more supplied vapor results in frequent water removal from porous electrode. • The performance is enhanced due to frequent voltage recoveries under flooding inducing operation. [ABSTRACT FROM AUTHOR]

Either side of organic photovoltaics incorporates a transparent conducting electrode for light entry, which becomes particularly crucial under indoor light conditions with low light intensity. However, since electrical resistivity and optical transparency with respect to film thickness are mutually contradictory, sufficiently thick (>150 nm) electrodes are inevitably required to ensure the appropriate electrical conductivity, at the sacrifice of transmittance. This paper introduces an electric field induced filament doping method to realize ultra-thin indium tin oxide with high conductivity. The proposed method allows for injecting metal dopants (i.e., Ni) into ultra-thin indium tin oxide under an electric field, enabling substantial resistance reduction while retaining high transmittance and low surface roughness. Optimum light absorption and effective carrier transport via filament doping provides improved performance for indoor organic photovoltaics. As a proof-of-principle demonstration, we fabricate poly(3-hexylthiophene):indene-C60 bisadduct based inverted organic photovoltaics with 10 nm Ni-doped indium tin oxide as a transparent cathode, leading to a power conversion efficiency of 14.6 ± 1.8% under the 1000-lux light-emitting diode. This efficiency is 40% higher than that achieved from the device using commercially available 150 nm indium tin oxide. Image 1 • Highly conductive ultra-thin (<30 nm) ITO films via filament doping are produced. • Produced ITO films are used as transparent cathode for indoor ogranic photovoltaics. • A power conversion efficiency of 14.6% is achieved under the 1000-lux LED light. [ABSTRACT FROM AUTHOR]

Abstract Recently, while increasing research has been focused toward improving the efficiency of various photovoltaic devices under low light intensities, few studies have reported on multi-donor-, multi-acceptor-based bulk heterojunctions (BHJ). In this study, we have demonstrated the utilization of a quaternary BHJ for indoor light energy harvesting applications. We utilized a PCDTBT:PTB7:PC 61 BM:PC 71 BM-based BHJ structure in order to improve the morphology, absorption window, and the charge transport properties of the photovoltaic device. The ability of ternary photovoltaics to attain high power-conversion efficiency (PCE) by improving the morphology and the charge transport properties had already been validated in another study. We show that the advantages of a stable quaternary solar cell can also be achieved with an optimized BHJ composition ratio of 5:5:3:12, which provides a PCE of 10.6%. Our device showed high shunt resistance and low series resistance, thus facilitating appreciable charge extraction even under low-intensity light conditions such as 500 lx white LED illumination. Graphical abstract Image 1 Highlights • Organic photovoltaics (OPVs) have shown to be promising for indoor energy harvesters. • Complementary absorption of the incident spectrum can improve the short-circuit current density of the OPV. • Requirement of careful optimization of active layer thickness was observed through optical simulation. • Experiment verified that quaternary OPV can obtain 10% power-conversion efficiency under indoor LED illumination. • 10% PCE was attained through complementary absorption and high shunt resistance of the OPV. [ABSTRACT FROM AUTHOR]

Abstract We report the indoor performance of flexible organic photovoltaic devices utilizing quasi-amorphous ZnO/Ag/ZnO as the transparent conducting electrode. A ZnO/Ag/ZnO electrode with specific thickness values of 40/9/50 nm provides excellent transparent conducting electrode properties with transmittances up to 92% in the visible region, a sheet resistance of 4.8 Ω/sq, and a root-mean squared surface roughness value of 2.1 nm. In addition, the micro-cavity effect and quasi-amorphous structural properties of the ZnO/Ag/ZnO electrode allow further enhanced light absorption and mechanical stability, respectively. Poly (3-hexylthiophene):indene-C 60 bisadduct photoactive layer-based inverted organic photovoltaics with the ZnO/Ag/ZnO (40/9/50 nm) electrode yield an averaged power-conversion efficiency of 12.3% under a light-emitting diode lamp with a luminance of 500 lux, which is 20% greater than the power-conversion efficiency value of the reference organic photovoltaics with an indium tin oxide electrode. Furthermore, the same organic photovoltaics on flexible polyethylene terephthalate substrates exhibit excellent mechanical stability (i.e., 92% of the initial power-conversion efficiency value is maintained even after 400 bending cycles with a bending radius of 9.55 mm), with averaged power-conversion efficiency values of 10.2% under the 500-lux light-emitting diode. Graphical abstract Image 1 Highlights • OPVs with clear and flexible ZnO/Ag/ZnO electrodes are fabricated. • Quasi-amorphous ZnO/Ag/ZnO electrodes provide excellent mechanical flexibility. • Micro-cavity effects via ZnO/Ag/ZnO enhance light absorption into OPVs. • ZnO/Ag/ZnO-based OPVs show a 12.3% conversion efficiency under a 500 lux LED. [ABSTRACT FROM AUTHOR]

Indoor solar cells are an attractive option to install in buildings to harvest the energy emitted by indoor lighting. They can be implemented as a stand-alone grid, or as part of an integrated energy harvesting unit. Previous research has utilized amorphous silicon and dye-sensitized solar cells for power generation from a fluorescent light source. In our study, we evaluated the applicability of a poly (3-hexylthiophene):indene-C60 bisadduct solar cell to harvest the light spectrum from an indoor light-emitting diode (LED). Because the absorption peak of poly (3-hexylthiophene) overlaps the LED spectrum peak, it serves as a good candidate for indoor light harvesting under an LED source. We have extracted the power conversion efficiency of the solar cell under different LED illuminance values, such as 200, 800, 1000, and 2000 lx. With the help of finite-difference time domain simulations, we optimized the solar device structure for each illuminance. The results detailed in this article were intended to assess the applicability of organic solar cells as indoor photovoltaics, and to provide a methodology to optimize the photovoltaic structure to maximize its efficiency. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNT) based nanoporous layer contacting the catalyst layer in polymer electrolyte membrane fuel cells (PEMFCs) is investigated. Nanoporous CNT-5, CNT-15, and CNT-40 sheets are prepared via direct spinning method with thicknesses is 5, 15, and 40 μm, respectively. The ethanol-derived CNT-5 possess sparse pore networks, whereas CNT-15 and CNT-40 derived from acetone exhibit fine networks, and CNT-15 and CNT-40 differ only in thickness. The CNTs are employed as either standalone nanoporous layer or as an additional layer with carbon-black microporous layer (MPL). Scanning electron microscopy and sessile drop method are utilized for CNT characterization. Current-voltage polarization curve and electrochemical impedance spectroscopy are recorded for the PEMFC characterization. The best performance is obtained when CNT-15 is adopted as an additional nanoporous layer with MPL in the dry operation. The current densities at a cell voltage of 0.6 V are 0.454 and 0.743 A cm−2 in dry and wet operations, respectively, corresponding to an increase of 28.5% and 57.1%, respectively, compared to carbon-black MPL. Enhancements in water management and reaction kinetics lead to this performance increase. In particular, the enhanced water storage and expulsion are benefits differentiated from employing CNT as the single nanoporous layer. [Display omitted] ∙ CNT-based nanoporous layers were employed to GDL of PEMFC. ∙CNTs were fabricated via cost-effective direct spinning method. ∙Additional nanoporous layer (w/ MPL) increased current density by 57% (at 0.6 V). ∙Mitigated charge transfer and ohmic resistances led to performance enhancements. ∙The correlation between the quality of CNT and fuel cell performance was subpar. [ABSTRACT FROM AUTHOR]

3D-printed flexible flow-field plates are employed in this study to realize a bendable polymer electrolyte membrane fuel cell (PEMFC). The prepared bendable PEMFC consists of a membrane electrode assembly (MEA), current collectors, and flow-field plates. The performance of the fuel cell is measured in the flat and bent positions. Polarization curves and impedance plots are analyzed to assess the fuel cell performance. A peak power density of 87.1 mW cm−2 is obtained for the fuel cell with the maximum bending, while a power density of 30.2 mW cm−2 is obtained in the flat position. The enhanced performance is attributed to the compressive stress applied to the reaction sites of the MEA during bending of the fuel cell. The compressive stress is calculated using finite element analysis (FEA). According to the FEA results, the compressive stress occurring at the MEA intensifies as the curvature of the fuel cell increases, resulting in significantly decreased ohmic and charge transfer resistances. The successfully realized bendable fuel cell with 3D-printed flexible flow-field plates exhibits flexibility, decent performance, and a simple structure. It is also competitive in terms of the cost of manufacturing owing to the use of 3D printing. [Display omitted] • A bendable PEMFC was realized with flexible flow-field plates. • Flexible flow-field plates were fabricated by 3D printing. • Performance of the bendable fuel cell was evaluated both in flat and bent positions. • FEA was performed to investigate compressive stress that occurred by bending. • The bendable fuel cell can operate for more than 12 h with bent shape. [ABSTRACT FROM AUTHOR]

Alternative acceptors for fullerene-derivatives need to be considered for indoor organic photovoltaics (OPVs) due to their spectrally inefficient light absorption ability and photo-instability which limits performance. Here, we report a highly efficient and photo-stable indoor OPV comprising an amalgamation of a wide band-gap donor(poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c']dithiophene-4,8-dionz) and a modified ITIC-based NFA (3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis (4-hexylmeta-phenyl)-dithieno [2,3-2′,3′-d']-s indaceno [1,2b:5,6b] dithiopheneethylexyloxy) (m -ITIC-O-EH)) with alkoxy side chains. Due to its excellent absorption properties in the near-infrared region, the m -ITIC-O-EH-based OPV exhibited an extraordinarily high maximum output power density (P max) (95.6 μW/cm2), >3 times greater than the P max (31.9 μW/cm2) of a reference fullerene acceptor-based (PC 70 BM) OPV under a 1000 lx halogen lamp (P in = 8.4 mW/cm2). Furthermore, the m -ITIC-O-EH-based OPV exhibited satisfactory photo-stability with >80% retention of its initial power conversion efficiency (PCE) under the continuous light soaking of the halogen lamp (1000 lx) for 12 h. The high-indoor performance of the alkoxy-substituted NFA-based OPVs highlights their potential for implementation in Internet of Things applications. [Display omitted] • ITIC-based NFA material (m -ITIC-O-EH) is utilized in indoor organic photovoltaics. • NFA-based OPVs exhibited outstanding P max of 95.6 μW/cm2 under 1000lx halogen lamp. • The NFA has an excellent absorption property in the near-infra red region. • NFA-based OPVs exhibited remarkable efficiency of 21.6% under 1000-lx LED lamp. • NFA-based OPVs revealed superb photostability under 1000-lx halogen lamp. [ABSTRACT FROM AUTHOR]