Partially oxidized inter-doped RuNi alloy aerogel for the hydrogen evolution reaction in both alkaline and acidic media.

A facile reduction and doping process is employed with the supercritical ethanol drying method to form RuNi alloy aerogels. The optimized heterostructure comprising RuNi metal, RuO2, and NiO phases is synthesized through partial oxidation. When applied to the surface of Ni foam, the multiphase aerogels form a morphology of highly porous 0D colloidal aerogel networks on the surface. RuNi alloy-Ni foam oxidized at 350 °C (RuNi-350@NF) has an overpotential of 89 and 61 mV in 1 M KOH and 0.5 M H2SO4 media at 50 mA cm-2, as well as satisfactory long-term stability. Additionally, the Tafel slopes in alkaline and acidic media are found to be 34 and 30.9 mV dec-1, respectively. Furthermore, it exhibits long-term stability (35 h) in alkaline and acidic media at high current densities of 50 mA cm-2, respectively. This study presents a novel strategy for developing exceptionally efficient and free-standing 3D porous aerogel electrocatalysts with potential applications in hydrogen production.

Quantification of tire wear particles in road dust based on synthetic/natural rubber ratio using pyrolysis-gas chromatography-mass spectrometry across diverse tire types.

Increase in road traffic leads to increased concentrations of tire-wear particles (TWPs), a prominent source of microplastics from vehicles, in road dust. These particles can re-enter the atmosphere or move into aquatic ecosystems via runoff, impacting the environment. Consequently, accurately assessing and managing TWP levels in road dust is crucial. However, the ISO method (ISO/TS 20593 and 21396) uses a constant ratio of styrene-butadiene rubber (SBR) to natural rubber (NR) for all tires, disregarding the variability in tire composition across different types and brands. Our study found substantial SBR content (15.7 %) in heavyweight truck tires, traditionally believed to be predominantly NR. We evaluated the SBR/NR content in 15 tire types and proposed a method to more accurately evaluate TWP concentrations in road dust from five different locations. Our findings suggest that the conventional ISO method may underestimate the concentrations of TWP due to its reliance on a static ratio of SBR/NR. This study underscores the necessity for a more flexible approach that can adapt to the variability in SBR and NR content across different tire types. By delineating the limitations inherent in current assessment methods, our research contributes to a more adaptable understanding of TWP concentrations in road dust. This advancement prompts the development of a revised methodology that more accurately reflects the diverse compositions of tire rubber in environmental samples.

PECI-Net: Bolus segmentation from video fluoroscopic swallowing study images using preprocessing ensemble and cascaded inference.

Bolus segmentation is crucial for the automated detection of swallowing disorders in videofluoroscopic swallowing studies (VFSS). However, it is difficult for the model to accurately segment a bolus region in a VFSS image because VFSS images are translucent, have low contrast and unclear region boundaries, and lack color information. To overcome these challenges, we propose PECI-Net, a network architecture for VFSS image analysis that combines two novel techniques: the preprocessing ensemble network (PEN) and the cascaded inference network (CIN). PEN enhances the sharpness and contrast of the VFSS image by combining multiple preprocessing algorithms in a learnable way. CIN reduces ambiguity in bolus segmentation by using context from other regions through cascaded inference. Moreover, CIN prevents undesirable side effects from unreliably segmented regions by referring to the context in an asymmetric way. In experiments, PECI-Net exhibited higher performance than four recently developed baseline models, outperforming TernausNet, the best among the baseline models, by 4.54% and the widely used UNet by 10.83%. The results of the ablation studies confirm that CIN and PEN are effective in improving bolus segmentation performance.

Influence of Thiol-Functionalized Polysilsesquioxane/Phosphorus Flame-Retardant Blends on the Flammability and Thermal, Mechanical, and Volatile Organic Compound (VOC) Emission Properties of Epoxy Resins.

In this study, thiol-functionalized ladder-like polysesquioxanes end-capped with methyl and phenyl groups were synthesized via a simple sol-gel method and characterized through gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and thermogravimetric analysis (TGA). Additionally, epoxy blends of different formulations were prepared. Their structural, flame-retardant, thermal, and mechanical properties, as well as volatile organic compound (VOC) emissions, were determined using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), TGA, scanning electron microscopy (SEM), limiting oxygen index (LOI), cone calorimetry, and a VOC analyzer. Compared to epoxy blends with flame retardants containing elemental phosphorus alone, those with flame retardants containing elemental phosphorus combined with silicon and sulfur exhibited superior thermal, flame-retardant, and mechanical properties with low VOC emissions. SEM of the residual char revealed a dense and continuous morphology without holes or cracks. In particular, LOI values for the combustion of methyl and phenyl end-capped polysilsesquioxane mixtures were 32.3 and 33.7, respectively, compared to 28.4% of the LOI value for the blends containing only phosphorus compounds. The silicon-sulfur-phosphorus-containing blends displayed reduced flammability concerning the blends using a flame retardant containing only phosphorus. This reflects the cooperative effects of various flame-retardant moieties.

Design of 2-Pyridone Fluorophores for Brighter Emissions at Longer Wavelengths.

The recent discovery of blue fluorophores with high quantum yields based on pyridone structures inspired the development of new low-molecular-weight fluorophores with bright emissions at tunable wavelengths, which are highly attractive for various applications. In this study, we propose a rational design strategy for 2-pyridone-based fluorophores with bright emissions at long wavelengths. With a detailed understanding of the positional substitution effects on each carbon atom of the 2-pyridone core, we developed a bright blue fluorophore (λabs =377 nm; λem =433 nm; ϵ=13,200 M-1 cm-1 ; ϕF =88 %) through C3 -aryl and C4 -ester substitutions followed by cyclization. Furthermore, by applying the intramolecular charge transfer (ICT) principle, we invented a bright green fluorophore through C3 - and C4 -diester and C6 -aryl substitutions. The ICT fluorophore based on the pyridone structure shows large molar absorptivity (ϵ=20,100 M-1 cm-1 ), longer emission wavelength (λem =539 nm), high emission quantum yield (ϕF =74 %), and large Stokes shift (Δv=5720 cm-1 ), which are comparable to those of practical fluorescent probes.

Small is Beautiful: Electronic Origin and Synthetic Evolution of Single-Benzene Fluorophores.

ConspectusSingle-benzene fluorophores (SBFs) are small molecules that produce visible light by using only one benzene ring as the sole aromatic core. This Account centers around the chemistry of a new class of SBF that we accidentally discovered but rationally developed and refined afterward. In a failed experiment that took an unintended reaction pathway, we encountered the bright green fluorescence of ortho-diacetylphenylenediamine (o-DAPA). Despite its uninspiring look, reminiscent of textbook examples of simple benzene derivatives, this molecule had neither been synthesized nor isolated before. This discovery led to our studies on the larger DAPA family, including isomeric m-DAPA and p-DAPA. Remarkably, p-DAPA is the lightest red fluorophore, with a molecular weight of only 192. While o- and p-DAPA are emissive, m-DAPA rapidly undergoes internal conversion, facilitated by sequential proton transfer reactions in the excited state.Leveraging the synthetic utility of the amine group, we carried out straightforward single-step modifications to create a full-color SBF library from p-DAPA as the common precursor. During the course of the investigation, we made another fortuitous discovery. With increasing acidity of the N-H group, the excited-state intramolecular proton transfer reaction is promoted, opening up additional pathways for emission to occur at even longer wavelengths. Tipping the balance between the two excited-state tautomers enabled the first example of a single-benzene white-light emitter. We demonstrated the practical utility of these molecules in white light-emitting devices and live cell imaging.According to the particle-in-a-box model, it is difficult to expect a molecule with only one small aromatic ring to produce long-wavelength emission. SBFs rise to this challenge by exploiting electron donor-acceptor pairs around the benzene core, which lowers the energy of light absorption. However, this answers only half of the question. Where do the exceptionally large spectral shifts in the light emission of SBFs originate from? Chemists have long been curious about the molecular mechanisms underlying the dramatic spectral shifts observed in SBFs. Prevailing paradigms invoke the charge transfer (CT) between electron donor and acceptor groups in the excited state. However, without a large π-skeleton for effective charge separation, how could benzene support a CT-type excited state? Our experimental and theoretical studies have revealed that large excited-state antiaromaticity (ESAA) of the benzene core itself is responsible for this remarkable phenomenon. The core matters, not the periphery. With appropriate molecular design, large and extended π-conjugation is no longer a prerequisite for long-wavelength light emission.

E2E-BPF microscope: extended depth-of-field microscopy using learning-based implementation of binary phase filter and image deconvolution.

Several image-based biomedical diagnoses require high-resolution imaging capabilities at large spatial scales. However, conventional microscopes exhibit an inherent trade-off between depth-of-field (DoF) and spatial resolution, and thus require objects to be refocused at each lateral location, which is time consuming. Here, we present a computational imaging platform, termed E2E-BPF microscope, which enables large-area, high-resolution imaging of large-scale objects without serial refocusing. This method involves a physics-incorporated, deep-learned design of binary phase filter (BPF) and jointly optimized deconvolution neural network, which altogether produces high-resolution, high-contrast images over extended depth ranges. We demonstrate the method through numerical simulations and experiments with fluorescently labeled beads, cells and tissue section, and present high-resolution imaging capability over a 15.5-fold larger DoF than the conventional microscope. Our method provides highly effective and scalable strategy for DoF-extended optical imaging system, and is expected to find numerous applications in rapid image-based diagnosis, optical vision, and metrology.

The Effectiveness of a Mechanical Ventilation System for Indoor PM2.5 in Residential Houses.

The mechanical ventilation systems used in houses are designed to reduce carbon dioxide emissions while minimizing the energy loss resulting from ventilation. However, the increase in indoor fine particulate (PM2.5) concentration because of external PM2.5 influx through the ventilation system poses a problem. Here, we analyzed the changes in indoor PM2.5 concentration, distinguishing between cases of high and low outdoor PM2.5 concentrations and considering the efficiency of the filters used in residential mechanical ventilation systems. When using filters with the minimum efficiency reporting value (MERV) of 10 in the ventilation system, the outdoor PM2.5 concentration was 5 µg/m³; compared to the initial concentration, the indoor PM2.5 concentration after 60 min decreased to 73%. When the outdoor PM2.5 concentration was 30-40 µg/m³, the indoor PM2.5 concentration reached 91%. However, when MERV 13 filters were used, the indoor PM2.5 concentration consistently dropped to 73-76%, regardless of the outdoor PM2.5 concentration. Furthermore, by comparing the established equation with the mass balance model, the error was confirmed to be within 5%, indicating a good fit. This allows for the prediction of indoor PM2.5 under various conditions when using mechanical ventilation systems, enabling the formulation of strategies for maintaining indoor PM2.5, as recommended by the World Health Organization.

Strategies for Effective Management of Indoor Air Quality in a Kindergarten: CO2 and Fine Particulate Matter Concentrations.

The educational and play-related activities of children proceed mainly indoors in a kindergarten. High concentrations of indoor PM2.5 and CO2 have been linked to various harmful effects on children, considerably impacting their educational outcomes in kindergarten. In this study, we explore different scenarios involving the operation of mechanical ventilation systems and air purifiers in kindergartens. Using numerical models to analyze indoor CO2 and PM2.5 concentration, we aim to optimize strategies that effectively reduce these harmful pollutants. We found that the amount of ventilation required to maintain good air quality, per child, was approximately 20.4 m3/h. However, we also found that as the amount of ventilation increased, so did the concentration of indoor PM2.5; we found that this issue can be resolved using a high-grade filter (i.e., a MERV 13 grade filter with a collection efficiency of 75%). This study provides a scientific basis for reducing PM2.5 concentrations in kindergartens, while keeping CO2 levels low.

Retention of Intrinsic Photophysical Properties of Porphyrin Building Blocks in 3D Organic Frameworks through Magic Angle Alignment.

Construction of three-dimensional (3D) frameworks maintaining intrinsic photophysical properties of monomeric building blocks is difficult and challenging due to the existence of various molecular interactions, such as metal-organic and π-π interactions. A 3D hydrogen-bonded organic framework (YSH-1Zn) with permanent porosity was constructed using a porphyrin having six carboxylic acid groups (1Zn). Brunauer-Emmett-Teller surface area measurement indicated that YSH-1Zn has a porous structure with a surface area of 392 m2/g. Single-crystal X-ray diffraction analysis revealed that 1Zn creates a 5-fold interwoven 3D network structure adopting a monoclinic system with a space group of P21/c. Each 1Zn within a single crystal exhibits parallel alignment with a slip-stack angle of 54.6°, in good agreement with the magic angle. Although the center-to-center distance of the nearest zinc atoms in YSH-1Zn is only 5.181 Å, the UV/vis absorption and fluorescence emission of YSH-1Zn are not different from those of 1Zn, indicating the absence of an interaction between excitons. Due to the magic angle alignment of 1Zn, the fluorescence lifetime, decay profiles, and quantum yield remained uniform even in the solid state.

Rapid estimation of tire-wear particle concentration in road dust using PM10 and traffic data in a ternary plot.

Air pollution, a pressing global issue, is significantly exacerbated by airborne particulate matter (PM), affecting air quality and human health. Urban vehicular activities majorly contribute to PM rise through both exhaust and non-exhaust emissions. Despite strides in managing exhaust emissions, non-exhaust particles, such as tire wear particles (TWP) remain under-addressed. This research proposes a method for estimating TWP concentrations using PM10 data and traffic activity, which could offer a valuable tool for controlling roadside fine particles and TWP. This paper introduces a ternary plotting technique and step-by-step procedure to estimate TWP levels in road dust using only PM10 and traffic data. Traditional analysis of TWP via pyrolysis-gas chromatography-mass spectrometry is complex and time-consuming. Hence, our proposed approach presents an alternate method that leverages readily accessible PM and traffic data, providing critical information for road management interpretation. The triangular plot analysis demonstrated a linear correlation: [log(Traffic) + 2]-[250,000/TWP-13]-0.18PM10. While the resulting correlation may vary based on specific road conditions, the method can be tailored to different regions, offering insights into efficient estimation of TWP concentrations and promoting improved roadside pollution management.

Effect of Synthetic Low-Odor Thiol-Based Hardeners Containing Hydroxyl and Methyl Groups on the Curing Behavior, Thermal, and Mechanical Properties of Epoxy Resins.

A novel thiol-functionalized polysilsesqioxane containing hydroxyl and methyl groups was synthesized using a simple acid-catalyzed sol-gel method to develop an epoxy hardener with low odor, low volatile organic compound (VOC) emissions, and fast curing at low temperatures. The synthesized thiol-based hardeners were characterized using Fourier transform infrared spectroscopy, nuclear magnetic resonance, thermogravimetric analysis (TGA), and gel permeation chromatography and compared with commercially available hardeners in terms of odor intensity and VOC emissions using the air dilution olfaction method and VOC analysis. The curing behavior and thermal and mechanical properties of the epoxy compounds prepared with the synthesized thiol-based hardeners were also evaluated. The results showed that synthetic thiol-based hardeners containing methyl and hydroxyl groups initiated the curing reaction of epoxy compounds at 53 °C and 45 °C, respectively. In contrast, commercial thiol-based hardeners initiated the curing reaction at 67 °C. Additionally, epoxy compounds with methyl-containing synthetic thiol-based hardeners exhibited higher TGA at a 5% weight loss temperature (>50 °C) and lap shear strength (20%) than those of the epoxy compounds with commercial thiol-based hardeners.

Material flow analysis-based assessment of polypropylene-fiber-containing microplastics released from disposable masks: Characterizing distribution in the environmental media.

With the upsurge in the use of disposable masks during the coronavirus disease pandemic, improper disposal of discarded masks and their negative impact on the environment have emerged as major issues. Improperly disposed of masks release various pollutants, particularly microplastic (MP) fibers, which can harm both terrestrial and aquatic ecosystems by interfering with the nutrient cycling, plant growth, and the health and reproductive success of organisms. This study assesses the environmental distribution of polypropylene (PP)-containing MPs, generated from disposable masks, using material flow analysis (MFA). The system flowchart is designed based on the processing efficiency of various compartments in the MFA model. The highest amount of MPs (99.7 %) is found in the landfill and soil compartments. A scenario analysis reveals that waste incineration significantly reduces the amount of MP transferred to landfills. Therefore, considering cogeneration and gradually increasing the incineration treatment rate are crucial to manage the processing load of waste incineration plants and minimize the negative impact of MPs on the environment. The findings provide insights into the potential environmental exposure associated with the improper disposal of waste masks and indicate strategies for sustainable mask disposal and management.

Bioaccumulation of Lead, Cadmium, and Arsenic in a Mining Area and Its Associated Health Effects.

Soil contamination is associated with a high potential for health issues. This study aimed to investigate the bioaccumulation of heavy metals and its associated health impact among residents near a mining area. We performed environmental monitoring by analyzing lead (Pb), cadmium (Cd), and arsenic (As) levels in soil and rice samples, as well as biomonitoring by analyzing blood and urine samples from 58 residents living near the mine. Additionally, concentration trends were investigated among 26 participants in a 2013 study. The Cd and As levels in the soil samples and Cd levels in the rice samples exceeded the criteria for concern. The geometric mean blood Cd level (2.12 µg/L) was two times higher than that in the general population aged > 40 years. The blood Cd level showed decreasing trends from the previous measurements of 4.56-2.25 µg/L, but was still higher than that in the general population. The blood and urine Cd levels were higher in those with a low estimated glomerular filtration rate (eGFR) than in those with normal eGFR. In conclusion, heavy metals from mining areas can accumulate in soil and rice, adversely impacting human health. Continuous environmental monitoring and biomonitoring are required to ensure the safety of residents.

Mitochondrial aconitase suppresses immunity by modulating oxaloacetate and the mitochondrial unfolded protein response.

Accumulating evidence indicates that mitochondria play crucial roles in immunity. However, the role of the mitochondrial Krebs cycle in immunity remains largely unknown, in particular at the organism level. Here we show that mitochondrial aconitase, ACO-2, a Krebs cycle enzyme that catalyzes the conversion of citrate to isocitrate, inhibits immunity against pathogenic bacteria in C. elegans. We find that the genetic inhibition of aco-2 decreases the level of oxaloacetate. This increases the mitochondrial unfolded protein response, subsequently upregulating the transcription factor ATFS-1, which contributes to enhanced immunity against pathogenic bacteria. We show that the genetic inhibition of mammalian ACO2 increases immunity against pathogenic bacteria by modulating the mitochondrial unfolded protein response and oxaloacetate levels in cultured cells. Because mitochondrial aconitase is highly conserved across phyla, a therapeutic strategy targeting ACO2 may eventually help properly control immunity in humans.

Rapid generation of aged tire-wear particles using dry-, wet-, and cryo-milling for ecotoxicity testing.

Strict environmental laws have been enacted to regulate the emission of exhaust particulate matter (PM), which is one of the most hazardous pollutants that reduce air quality and pose a serious risk to the human health. In addition, non-exhaust PM, such as road wear, tire wear, and brake wear debris, is a significant source of airborne pollutants. Road dust less than 100 µm in size may include tire wear particles (TWPs), which are broken down into finer particles with sizes on the order of tens of micrometers because of weathering. TWPs can be transported to water bodies via runoff, potentially contaminating water systems and negatively affecting aquatic ecosystems. Therefore, ecotoxicity tests using reference TWPs are required to investigate the impact of TWPs on the human health and environment. In this study, aged TWPs were produced using dry-, wet-, and cryo-milling methods, and the dispersion stability of TWPs in dechlorinated water was evaluated. Aged TWPs prepared by dry- and wet-milling had an average particle size of 20 µm, whereas pristine TWPs had an irregular shape and average particle size of 100 µm. The capacity of the ball-milling cylinder and excessively long 28-d generation time constrain the amount of aged TWPs that can be produced through conventional milling. In contrast, cryo-milling reduces the particle size of TWPs at the rate of -275.0 µm/d, which is nine times higher than that upon dry- and wet-milling. Dispersed cryo-milled TWPs had a hydrodiameter of 2.02 µm and were more stable in the aqueous phase in relation to the other aged TWPs. The results of this study suggest that cryo-milled TWPs can be used for aquatic exposure assessments as controls for real-world TWPs.

Overall distribution of tire-wear particles, nano­carbon black, and heavy metals in size-fractionated road dust collected from steel industrial complexes.

Tire-wear particles (TWP) from vehicles serves as a non-exhaust emission source. The mass content of metallic species in road dust may increase owing to the traffic of heavy vehicles and industrial activity; consequently, metallic particles are also present in road dust. Herein, road dust collected from steel industrial complexes with high traffic of high-weight vehicles and the composition distribution of five size-fractioned particle sizes were analyzed. Road dust samples were collected from three areas near steelmaking complexes. The mass distribution of TWP, carbon black (CB), bituminous coal, and heavy metals (Fe, Zn, Mn, Pb, Ni, As, Cu, Cd, and Hg) in different size fractions of road dust was quantified by combining four different analytical techniques. In the magnetic separation for <45 µm fraction, 34.4 wt% and 50.9 wt% was removed for steelmaking and steel-related industrial complexes, respectively. As the particle size decreased, the mass content of Fe, Mn, and TWP increased. The enrichment factors of Mn, Zn, and Ni were higher than two, indicating that they were related to industrial activities in steel complexes. The maximum concentrations of TWP and CB originating from the vehicle varied depending on the region and particle size range: TWP 2.066 wt% at 45-75 µm (industrial complex) and CB 5.559 wt% at 75-160 µm (steel complex). Coal was only found in the steel complex. Finally, to reduce the exposure of the finest particles to road dust, three methods were suggested. Magnetic fraction must be removed from road dust using magnetic separation; the fly dust of coal during transportation must be suppressed, and covers must be used in coal yards; the mass contents of TWP and CB in road dust should be removed by vacuum cleaning instead of water flushing.

Single-Benzene Dual-Emitters Harness Excited-State Antiaromaticity for White Light Generation and Fluorescence Imaging.

Molecular emitters simultaneously generating light at different wavelengths have wide applications. With a small molecule, however, it is challenging to realize two independent radiative pathways. We invented the first examples of dual-emissive single-benzene fluorophores (SBFs). Two emissive tautomers are generated by synthetic modulation of the hydrogen bond acidity, which opens up pathways for excited-state proton transfer. White light is produced by a delicate balance between the energy and intensity of the emission from each tautomer. We show that the excited-state antiaromaticity of the benzene core itself dictates the proton movements driving the tautomer equilibrium. Using this simple benzene platform, a fluorinated SBF was synthesized with a record high solubility in perfluorocarbon solvents. White light-emitting devices and multicolor imaging of perfluorocarbon nanodroplets in live cells demonstrate the practical utility of these molecules.

Rapid electrochemical biosensor composed of DNA probe/iridium nanoparticle bilayer for Aphanizomenon flos-aquae detection in fresh water.

Toxic cyanobacteria pose a serious threat to aquatic ecosystems and require adequate detection and control systems. Aphanizomenon flos-aquae is a harmful cyanobacterium that produces the toxicant saxitoxin. Therefore, it is necessary to detect the presence of A. flos-aquae in lakes and rivers. We proposed a rapid electrochemical biosensor composed of DNA primer/iridium nanoparticles (IrNP) bilyer for the detection of A. flos-aquae in freshwater. The extracted A. flos-aquae gene (rbcL-rbcX) is used as a target, and it was fixed to the electrode using a 5'-thiolated DNA primer (capture probe). Then, Avidin@IrNPs complex for amplification of electrical signals was bound to the target through a 3'-biotinylated DNA primer (detection probe). To rapidly detect the target, an alternating current electrothermal flow technique was introduced in the detection step, which could reduce the detection time to within 20 min. To confirm the biosensor fabrication, atomic force microscopy was used to investigate the surface morphology. To evaluate the biosensor performance, cyclic voltammetry and electrochemical impedance spectroscopy were used. The target gene was detected at a concentration of 9.99 pg/mL in tap water, and the detection range was 0.1 ng/mL to 103 ng/mL with high selectivity. Based on the combined system, we employed A. flos-aquae in tap water. This rapid cyanobacteria detection system is a powerful tool for CyanoHABs in the field.