Stepwise emergence of CO gas sensing response and selectivity on SnO2 using C supports and PtOx decoration.

Room temperature gas sensing is crucial for practical devices used in indoor environments. Among various materials, metal oxides are commonly used for gas sensing, but their strong insulating properties limit their effectiveness at room temperature. To address this issue, many studies have explored diverse methods such as nanoparticle decoration or conductive support, etc. Here, we report the emergence of gas-sensing functionality at room temperature with improved CO gas selectivity on SnO2 nanoparticles through sequential steps by using amorphous carbon (a-C) support and PtOx decoration. The SnO2 decorated on amorphous carbon shows enhanced gas adsorption compared to inactive gas sensing on SnO2 decorated carbon support. The higher Vo site of SnO2 on a-C induces gas adsorption sites, which are related to the higher sp2 bonding caused by the large density of C defects. The ambiguous gas selectivity of SnO2/a-C is tailored by PtOx decoration, which exhibits six values of sensing responses (Rg/Ra or Ra/Rg) under CO gas at room temperature with higher selectivity. Compared to PtOx/a-C, which shows no response, the enhanced CO gas sensing functionality is attributed to the CO adsorption site on PtOx-decorated SnO2 particles. This report not only demonstrates the applicability of CO gas sensing at room temperature but also suggests a strategy for using SnO2 and carbon compositions in gas sensing devices.

Alpha-Gal IgE Prevalence Patterns in the United States: An Investigation of 3,000 Military Recruits.

BACKGROUND: IgE to the oligosaccharide galactose-alpha-1,3-galactose (alpha-gal) is an important cause of allergic reactions to mammalian meat. The "alpha-gal syndrome" is strongly associated with a preceding history of tick bites and in the United States is most commonly reported in parts of the southeast, but there has been limited investigation into national alpha-gal sensitization patterns and the relevance of other risk factors. OBJECTIVE: To systematically investigate alpha-gal IgE prevalence, regional patterns, and risk factors. METHODS: Alpha-gal IgE was measured by ImmunoCAP in biobanked serum samples collected from 3000 service members who presented for intake to 1 of 10 military bases in the central/eastern United States. Alpha-gal IgE sensitization (cutoff 0.1 international units/mL) was related to home of record at enlistment. RESULTS: Of the cohort, 2456 (81.9%) subjects were male, median age was 19 years (interquartile range: 18-22 years), and alpha-gal IgE was detected in 179 (6.0%). Home of record spanned all 50 states, with a median of 36 recruits per state (range: 3-261). The highest prevalence rates were in Arkansas (39%), Oklahoma (35%), and Missouri (29%), with several other southeastern states >10%. Granular mapping revealed sensitization patterns that closely mimicked county-level Amblyomma americanum reports and Ehrlichia chaffeensis infections. Sensitization was associated with male sex, rural residence, and White race in univariate and multivariable models. CONCLUSIONS: In this systematic survey, the prevalence of alpha-gal IgE among incoming military personnel was 6.0%. There were significant regional differences, with an overall pattern consistent with the known range of the lone star tick (A. americanum) and highest frequency in an area including Arkansas, Oklahoma, and Missouri.

Electrically-stimulated cellular and tissue events are coordinated through ion channel-mediated calcium influx and chromatin modifications across the cytosol-nucleus space.

Electrical stimulation (ES) through biomaterials and devices has been implicated in activating diverse cell behaviors while facilitating tissue healing process. Despite its significance in modulating biological events, the mechanisms governing ES-activated cellular phenomena remain largely elusive. Here, we demonstrated that millisecond-pulsed temporal ES profoundly impacted a spectrum of cellular events across the membrane-cytosol-nuclear space. These include activated ion channels, intracellular calcium influx, actomyosin contractility, cell migration and proliferation, and secretome release. Such events were coordinated mainly through ES-activated ion channels and calcium oscillation dynamics. Notably, ES increased the chromatin accessibility of genes, particularly those associated with the ES-activated cellular events, underscoring the significance of epigenetic changes in ES-induced behavioral outcomes. We identified histone acetylation (mediated by histone acetyltransferases), among other chromatin modifications, is key in reshaping the chromatin landscape upon ES. These observations were further validated through experiments involving ex vivo skin tissue samples, including activated ion channels and calcium influx, increased cell proliferation and actomyosin contractility, elevated secretome profile, and more accessible chromatin structure following ES. This work provides novel insights into the mechanisms underlying ES-activated cell and tissue events, ultimately guiding design principles for the development of electrical devices and materials effective for tissue repair and wound healing.

Neural Tissue-Like, not Supraphysiological, Electrical Conductivity Stimulates Neuronal Lineage Specification through Calcium Signaling and Epigenetic Modification.

Electrical conductivity is a pivotal biophysical factor for neural interfaces, though optimal values remain controversial due to challenges isolating this cue. To address this issue, conductive substrates made of carbon nanotubes and graphene oxide nanoribbons, exhibiting a spectrum of conductivities from 0.02 to 3.2 S m-1, while controlling other surface properties is designed. The focus is to ascertain whether varying conductivity in isolation has any discernable impact on neural lineage specification. Remarkably, neural-tissue-like low conductivity (0.02-0.1 S m-1) prompted neural stem/progenitor cells to exhibit a greater propensity toward neuronal lineage specification (neurons and oligodendrocytes, not astrocytes) compared to high supraphysiological conductivity (3.2 S m-1). High conductivity instigated the apoptotic process, characterized by increased apoptotic fraction and decreased neurogenic morphological features, primarily due to calcium overload. Conversely, cells exposed to physiological conductivity displayed epigenetic changes, specifically increased chromatin openness with H3acetylation (H3ac) and neurogenic-transcription-factor activation, along with a more balanced intracellular calcium response. The pharmacological inhibition of H3ac further supported the idea that such epigenetic changes might play a key role in driving neuronal specification in response to neural-tissue-like, not supraphysiological, conductive cues. These findings underscore the necessity of optimal conductivity when designing neural interfaces and scaffolds to stimulate neuronal differentiation and facilitate the repair process.

Effective single web-structured electrode for high membrane electrode assembly performance in polymer electrolyte membrane fuel cell.

To achieve a sustainable society, CO2 emissions must be reduced and efficiency of energy systems must be enhanced. The polymer electrolyte membrane fuel cell (PEMFC) has zero CO2 emissions and high effectiveness for various applications. A well-designed membrane electrolyte assembly (MEA) composed of electrode layers of effective materials and structure can alter the performance and durability of PEMFC. We demonstrate an efficient electrode deposition method through a well-designed carbon single web with a porous 3D web structure that can be commercially adopted. To achieve excellent electrochemical properties, active Pt nanoparticles are controlled by a nanoglue effect on a highly graphitized carbon surface. The developed MEA exhibits a notable maximum power density of 1082 mW/cm2 at 80°C, H2/air, 50% RH, and 1.8 atm; low cathode loading of 0.1 mgPt/cm2; and catalytic performance decays of only 23.18 and 13.42% under commercial-based durability protocols, respectively, thereby achieving all desirables for commercial applications.

Erosion-Driven Enamel Crystallite Growth Phenomenon at the Tooth Surface In Vitro.

The erosion of tooth enamel is a common oral disease. The erosion pattern and location and the effects of nanoscale chemical composition on the erosion susceptibility of enamel have been well documented. However, the enamel remineralization accompanied by erosion and its underlying physicochemical mechanisms still remain poorly understood. Here, using rat molars selected for its good relevancy to human teeth, we investigated the remineralization behavior of the outermost enamel surface at the nanoscale level during erosion in diluted hydrochloric acid solutions. While particles on the outermost enamel surface that represent the termination of crystallites protruding to the surface from the near-surface core eroded by acid-attack, the lateral-growth of the particles (i.e., the main remineralization picture of the surface enamel) occurred concurrently. Ionic analyses indicate that the particle growth is driven by the local increase in pH near the eroding enamel surface as a result of the combination of the PO43- and CO32- released from the enamel surface with H+. As the pH increases eventually to the equilibrium pH level (∼5.5), a local supersaturation of solute ions is induced, resulting in particle growth. A simple growth model based on the experimental results together with an assumption that the particle growth is a diffusional process suggests that the particle growth rate is controlled by the degree of supersaturation and accommodation site for solute ions, which are affected by the pH of solution eroding the enamel surface. The remineralization mechanism presented by our study can explain how the enamel on being acid-exposed or tooth decay progress by beverage or food can naturally remineralize in the oral cavity and how remineralization can foster different surface topology at the nanoscale, depending on the pH value of etchant before the dental filling material is applied.

Harnessing Strong Metal-Support Interaction to Proliferate the Dry Reforming of Methane Performance by In Situ Reduction.

The strong bonding at the interface between the metal and the support, which can inhibit the undesirable aggregation of metal nanoparticles and carbon deposition from reforming of hydrocarbon, is well known as the classical strong metal-support interaction (SMSI). SMSI of nanocatalysts was significantly affected by heat treatment and reducing conditions during catalyst preparation.the heat treatment and reduction conditions during catalyst preparation. SMSI can be weakened by the decrement of metal-doped sites in the supporting oxide and can often deactivate catalysts by the encapsulation of active sites through these processes. To retain SMSI near the active sites and to enhance the catalytic activity of the nanocatalyst, it is essential to increase the number of surficial metal-doped sites between nanometal and the support. Herein, we propose a mild reduction process using dry methane (CH4/CO2) gas that suppresses the aggregation of nanoparticles and increases the exposed interface between the metal and support, Ni and cerium oxide. The effects of mild reduction on the chemical state of Ni-cerium oxide nanocatalysts were specifically investigated in this study. As a result, mild reduction led to form large amounts of the Ni3+ phase at the catalyst surface of which SMSI was significantly enhanced. It can be easily fabricated while the dry reforming of methane (DRM) reaction is on stream. The superior performance of the catalyst achieved a considerably high CH4 conversion rate of approximately 60% and stable operation up to 550 h at a low temperature, 600 °C.

Biological Potential of Polyethylene Glycol (PEG)-Functionalized Graphene Quantum Dots in In Vitro Neural Stem/Progenitor Cells.

Stem cell therapy is one of the novel and prospective fields. The ability of stem cells to differentiate into different lineages makes them attractive candidates for several therapies. It is essential to understand the cell fate, distribution, and function of transplanted cells in the local microenvironment before their applications. Therefore, it is necessary to develop an accurate and reliable labeling method of stem cells for imaging techniques to track their translocation after transplantation. The graphitic quantum dots (GQDs) are selected among various stem cell labeling and tracking strategies which have high photoluminescence ability, photostability, relatively low cytotoxicity, tunable surface functional groups, and delivering capacity. Since GQDs interact easily with the cell and interfere with cell behavior through surface functional groups, an appropriate surface modification needs to be considered to get close to the ideal labeling nanoprobes. In this study, polyethylene glycol (PEG) is used to improve biocompatibility while simultaneously maintaining the photoluminescent potentials of GQDs. The biochemically inert PEG successfully covered the surface of GQDs. The PEG-GQDs composites show adequate bioimaging capabilities when internalized into neural stem/progenitor cells (NSPCs). Furthermore, the bio-inertness of the PEG-GQDs is confirmed. Herein, we introduce the PEG-GQDs as a valuable tool for stem cell labeling and tracking for biomedical therapies in the field of neural regeneration.

Mechanistic Pathways for the Molecular Step Growth of Calcium Oxalate Monohydrate Crystal Revealed by In Situ Liquid-Phase Atomic Force Microscopy.

Calcium oxalate monohydrate (COM) crystal is the most common crystalline component of human kidney stones. The molecular-scale inhibitory mechanisms of COM crystal growth by urinary biomolecules such as citrate and osteopontin adsorbed onto the crystal surface are now well understood. However, the pathways by which dissolved calcium and oxalate ions are incorporated into the molecular step of the COM crystal surface, leading to COM crystal growth-a prerequisite to be elucidated for developing effective therapeutics to inhibit COM stones-remain unknown. Here, using in situ liquid-phase atomic microscopy along with a step kinetic model, we reveal the pathways of the calcium and oxalate ions into the COM molecular step via the growth speed analysis of the molecular steps with respect to their step width at the nanoscale. Our results show that, primarily, the ions are adsorbed onto the terrace of the crystal surface from the solution-the rate-controlling stage for the molecular step growth, i.e., COM crystal growth-and then diffuse over it and are eventually incorporated into the steps. This primary pathway of the ions is unaffected by the model peptide D-Asp6 adsorbed on the COM crystal surface, suggesting that urinary biomolecules will not alter the pathway. These new findings rendering an essential understanding of the fundamental growth mechanism of COM crystal at the nanoscale provide crucial insights beneficial to the development of effective therapeutics for COM kidney stones.

Electricity auto-generating skin patch promotes wound healing process by activation of mechanosensitive ion channels.

Electricity constitutes a natural biophysical component that preserves tissue homeostasis and modulates many biological processes, including the repair of damaged tissues. Wound healing involves intricate cellular events, such as inflammation, angiogenesis, matrix synthesis, and epithelialization whereby multiple cell types sense the environmental cues to rebuild the structure and functions. Here, we report that electricity auto-generating glucose-responsive enzymatic-biofuel-cell (EBC) skin patch stimulates the wound healing process. Rat wounded-skin model and in vitro cell cultures showed that EBC accelerated wound healing by modulating inflammation while stimulating angiogenesis, fibroblast fuctionality and matrix synthesis. Of note, EBC-activated cellular bahaviors were linked to the signalings involved with calcium influx, which predominantly dependent on the mechanosensitive ion channels, primarily Piezo1. Inhibition of Piezo1-receptor impaired the EBC-induced key functions of both fibroblasts and endothelial cells in the wound healing. This study highlights the significant roles of electricity played in wound healing through activated mechanosensitive ion channels and the calcium influx, and suggests the possibility of the electricity auto-generating EBC-based skin patch for use as a wound healing device.

Transparent Bendable Secondary Zinc-Air Batteries by Controlled Void Ionic Separators.

First ever transparent bendable secondary zinc-air batteries were fabricated. Transparent stainless-steel mesh was utilized as the current collector for the electrodes due to its reliable mechanical stability and electrical conductivity. After which separate methods were used to apply the active redox species. For the preparation of the anode, zinc was loaded by an electroplating process to the mesh. For the cathode, catalyst ink solution was spray coated with an airbrush for desired dimensions. An alkaline gel electrolyte layer was used for the electrolyte. Microscale domain control of the materials becomes a crucial factor for fabricating transparent batteries. As for the presented cell, anionic exchange polymer layer has been uniquely incorporated on to the cathode mesh as the separator which becomes a key procedure in the fabrication process for obtaining the desired optical properties of the battery. The ionic resin is applied in a fashion where controlled voids exist between the openings of the grid which facilitates light passage while guaranteeing electrical insulation between the electrodes. Further analysis correlates the electrode dimensions to the transparency of the system. Recorded average light transmittance is 48.8% in the visible light region and exhibited a maximum power density of 9.77 mW/cm2. The produced battery shows both transparent and flexible properties while maintaining a stable discharge/charge operation.

Effects of dispersed copper nanoparticles on Ni-ceria based dry methanol fuelled low temperature solid oxide fuel cells.

Methanol is an attractive energy source due to its portability and thermodynamic coke resistance by its oxygen content. In order to operate dry methanol fuel low temperature solid oxide fuel cells (LT-SOFCs), it is important to solve the problems of carbon formation and its low performance. In this study, copper impregnation was selected to decrease the carbon deposition and enhance the performance at low temperature. The interaction of copper, ceria and nickel improves CO oxidation capacity which improves coke tolerance and nano-sized nickel copper alloys improved durability and catalytic performance under methanol feed. It markedly amplified the performance about 0.4 W cm-2 at 550 °C with the durable operation at 1.4 A cm-2 over 50 h. Loading copper nanoparticles is promising method for Ni-ceria based LT-SOFC using methanol fuel with high performance and stable operation.

Oxide-Carbon Nanofibrous Composite Support for a Highly Active and Stable Polymer Electrolyte Membrane Fuel-Cell Catalyst.

Well-designed electronic configurations and structural properties of electrocatalyst alter the activity, stability, and mass transport for enhanced catalytic reactions. We introduce a nanofibrous oxide-carbon composite by an in situ method of carbon nanofiber (CNF) growth by highly dispersed Ni nanoparticles that are exsoluted from a NiTiO3 surface. The nanofibrous feature has a 3D web structure with improved mass-transfer properties at the electrode. In addition, the design of the CNF/TiO2 support allows for complex properties for excellent stability and activity from the TiO2 oxide support and high electric conductivity through the connected CNF, respectively. Developed CNF/TiO2-Pt nanofibrous catalyst displays exemplary oxygen-reduction reaction (ORR) activity with significant improvement of the electrochemical surface area. Moreover, exceptional resistance to carbon corrosion and Pt dissolution is proven by durability-test protocols based on the Department of Energy. These results are well-reflected to the single-cell tests with even-better performance at the kinetic zone compared to the commercial Pt/C under different operation conditions. CNF/TiO2-Pt displays an enhanced active state due to the strong synergetic interactions, which decrease the Pt d-band vacancy by electron transfer from the oxide-carbon support. A distinct reaction mechanism is also proposed and eventually demonstrates a promising example of an ORR electrocatalyst design.

Interface-designed Membranes with Shape-controlled Patterns for High-performance Polymer Electrolyte Membrane Fuel Cells.

Polymer electrolyte membrane fuel cell is a promising zero-emission power generator for stationary/automotive applications. However, key issues, such as performance and costs, are still remained for an economical commercialization. Here, we fabricated a high-performance membrane electrode assembly (MEA) using an interfacial design based on well-arrayed micro-patterned membranes including circles, squares and hexagons with different sizes, which are produced by a facile elastomeric mold method. The best MEA performance is achieved using patterned Nafion membrane with a circle 2 µm in size, which exhibited a very high power density of 1906 mW/cm(2) at 75 °C and Pt loading of 0.4 mg/cm(2) with 73% improvement compared to the commercial membrane. The improved performance are attributed to the decreased MEA resistances and increased surface area for higher Pt utilization of over 80%. From these enhanced properties, it is possible to operate at lower Pt loading of 0.2 mg/cm(2) with an outstanding performance of 1555 mW/cm(2) and even at air/low humidity operations.