Particle Chemistry Research Articles

Is phenomenal consciousness really a special case in science?

In the metaphysics of science, it is often held that higher-level properties are grounded in micro-physical properties. According to many philosophers, however, phenomenal consciousness resists this view. Many famous arguments in Philosophy of Mind have been given to reject this notion. In this paper, we argue that there is something odd about the idea that phenomenal consciousness is a special case in science and give a constructive proposal on how consciousness can fit in the natural world. To do so, we will first introduce a general notion of what grounding is. Then, we will briefly explain how the arguments for the specialness of phenomenal consciousness work by considering two famous examples, namely the zombie and the knowledge argument. In a further step, we will briefly discuss two cases from other areas in science, i.e., in particle physics and chemistry. We will demonstrate that the standard view about the reductive relation does not hold, even in these paradigm cases of the natural sciences. If what we argue is true, we think that most arguments from phenomenal consciousness cannot defeat physicalism per se. Finally, we will introduce an alternative way to naturalize phenomenal consciousness.

Size distribution, sources and chemistry of ultrafine particles at Barcelona-El Prat Airport, Spain

The rapid expansion of the aviation sector raises concerns about air quality impacts within and around airports. Ultrafine particles (UFP, diameter < 100 nm) are of particular concern due to their potential adverse health effects. In this study, particle number concentrations (PNC), particle number size distribution (PNSD), and other ancillary pollutants such as particulate matter (PM), nitrogen oxides (NOX), black carbon (BC), sulfur dioxide (SO2), ozone (O3), carbon monoxide (CO) and benzene, as well as organic markers and trace elements (in quasi-UFP) were measured at Barcelona-El Prat Airport (80 m and 250 m from the main taxiway and runway). Comparisons were made with an urban background (UB) location, and source apportionment of PNSD was performed using Positive Matrix Factorization (PMF). PNC inside the airport was nine-fold higher than the UB, and fifteen-fold higher when considering only nucleation mode particles (< 25 nm). Six sources contributing to PNC were identified inside the airport: Taxiing (48.7 %; mode diameter = 17 nm), Industrial/Shipping (7.4 %; mode diameter = 35 nm), Diesel (3.9 %; mode diameter = 64 nm), Regional recirculation (1.1 %; mode diameter = 100 nm), Photonucleation (16.6 %; mode diameter = 13 nm) and Takeoff (18.5 %; mode diameter = 23 nm). Due to the measurement location and prevailing wind patterns, no significant contributions from landings were detected. Chemical analysis of quasi-UFP collected on Electrical Low-Pressure Impactor (ELPI + ) filters (stages 2 to 6: 17–165 nm) revealed higher concentrations (> 2-fold) of Fe, Al, Cr, Cu, Mo, Mn, Pb, Ti, and Sb at the airport compared to the UB, with Al exhibiting the most pronounced disparity. Generally, PAH levels were low at both sites, although concentrations were higher at the airport relative to the UB. Overall, this study provides a comprehensive understanding of UFP within a major European airport, identifying the different sources contributing to PNC and PNSD.

Chemistry and Physics of Wet Foam Stability for Porous Ceramics: A Review

The unique structural properties of porous ceramics, such as low thermal conductivity, high surface area, controlled permeability, and low density, make this material valuable for a wide range of applications. Its uses include insulation, catalyst carriers, filters, bio-scaffolds for tissue engineering, and composite manufacturing. However, existing processing methods for porous ceramics, namely replica techniques and sacrificial templates, are complex, release harmful gases, have limited microstructure control, and are expensive. In contrast, the direct foaming method offers a simple and cost-effective approach. By modifying the surface chemistry of ceramic particles in a colloidal suspension, the hydrophilic particles are transformed into hydrophobic ones using surfactants. This method produces porous ceramics with interconnected pores, creating a hierarchical structure that is suitable for applications like nano-filters. This review emphasizes the importance of interconnected porosity in developing advanced ceramic materials with tailored properties for various applications. Interconnected pores play a vital role in facilitating mass transport, improving mechanical properties, and enabling fluid or gas infiltration. This level of porosity control allows for the customization of ceramic materials for specific purposes, including filtration, catalysis, energy storage, and biomaterials.

Source Identification Using Principal Component Analysis and Health Risk Assessment of Heavy Metals Contamination in PM2.5 Near an Industrial Area in Thailand

AbstractIndustrialization has led to a surge in air pollution-related problems, as particulate matter (PM) containing heavy metals poses significant health risks. Understanding airborne particle chemistry, particularly the presence of heavy metals, is vital for effective air quality management and health interventions. This study analysed heavy metal levels in PM2.5 across various sites near an industrial zone in Thailand, including areas near main roads, the industrial zone, as well as indoor and outdoor areas of childcare centres. The concentrations of ambient PM2.5 were found to exceed national standards and acceptable limits during the cool dry season, particularly in the industrial zone (46.4 µg/m3), followed by areas near main roads (41.0 µg/m3) and childcare centres (31.6 µg/m3). The impact of the indoor–outdoor relationship on PM2.5 concentration within childcare centres varied. During the cool dry season, Aluminium had the highest concentration, while lead (Pb) across all sites raised environmental concerns. Remarkably, indoor childcare centres showed higher Pb levels than industrial zones and areas near the main road. Principal Component Analysis revealed the distinct factors linked to specific metals, implying contributions from industrial and transportation sources. Lead isotopic analysis indicated potential associations between lead sources and industries like smelting and refining. During the cool dry season, non-carcinogenic risks were concerning (HI &gt; 1), especially near roads and industrial areas. Vulnerabilities were also observed in students and teachers within indoor childcare centres. This study underscores the importance of monitoring and reducing heavy metal pollution in PM2.5, especially in childcare centres near industrial zones, to preserve public health and regional air quality.

Using Indoor and Outdoor Measurements to Understand Building Protectiveness against Wildfire, Atmospheric Inversion, and Firework PM2.5 Pollution Events

The world has seen an increase in the frequency and severity of elevated outdoor pollution events exacerbated by the rise in distant polluting events (i.e., wildfires). We examined the intersection between indoor and outdoor air quality in an urban area using research-grade sensors to explore PM2.5 infiltration across a variety of pollution events by testing two separate indoor environments within the same building. We confirmed prior work suggesting that indoor environments in buildings are most protective during wintertime inversion events and less so during fireworks and wildfire events. The building indoor environment protectiveness varies notably during different pollution episodes, especially those that have traveled longer distances (e.g., wildfires), and we found evidence of varied infiltration rates across PM2.5 types. Inversion events have the lowest infiltration rates (13–22%), followed by fireworks (53–58%), and wildfires have the highest infiltration rates (62–70%), with distant wildfire events persisting longer and, therefore, infiltrating for greater durations than local-wildfire-related particle matter. The differences in PM infiltration rates were likely due to the combined effects of several factors, including varying particle size, concentration, and chemistry. Subsequently, the local wildfires had different temporal air quality impacts than distant wildfire pollution in this case. Based on these findings, indoor air quality appears more conducive to protective action and policies than outdoor air quality because the built environment may serve to shield individuals from outdoor air.

Multi-Scale Development and Integration of Granular Activated Carbon Electrodes in Multiphase Electrochemical Systems

Providing clean water remains a significant challenge in underserved areas that lack access to public water systems or are affected by extreme natural events like hurricanes. Electrochemical technologies show promise for developing affordable and effective water treatment systems due to their ability to efficiently oxidize contaminants. Particularly, the electrochemical synthesis of in-situ reagents, such as H2O2, systems can oxidize contaminants over the full range of pH with high oxidation potential, leaving only water and oxygen at the end of process, making it a safe and effective method for water treatment. This study is focused on integrating carbon-based electrodes into electrochemical water treatment systems emphasizing their scalability, cost effectiveness, and the efficient generation of reactive oxygen species (ROS). By employing multiscale computational approaches, we develop a comprehensive mechanistic understanding and optimization of ROS generation at the surface of granular activated carbon (GAC) electrodes. Using reactive molecular dynamics simulations, the thermodynamic and transport properties of water-based electrolyte (e.g., adsorption, viscosity, and diffusion) are investigated as a function of the GAC particle size and chemistry. The obtained results show that tuning the GAC particle structure at nanoscale can improve the local diffusion rates by three times. Subsequently, multiphase continuum simulations are used to integrate the GAC electrodes in full electrochemical systems through optimizing the dispersion and the solid-liquid-gas interactions in a reactive environment. The computational findings reveal that higher production of H2O2 and are observed at optimized electrode porosity values when the GAC electrodes are integrated at the system level. These observations are linked to the complex reactive solid-fluid interactions. Specifically, the electrochemical oxygen bubble splitting and coalescence are minimized by optimizing the electrode porosity, which improves the dispersion mass transfer processes by at least one order of magnitude. This leads to higher generation rates of ROS and enhanced degradation of water contaminants. These mechanistic observations will help in designing and scaling up carbon-based electrodes for developing efficient and cost-effective electrochemical water treatment reactors.

Artificial chemotaxis under electrodiffusiophoresis

HypothesisThrough a large parameter space, electric fields can tune colloidal interactions and forces leading to diverse static and dynamical structures. So far, however, field-driven interactions have been limited to dipole-dipole and hydrodynamic contributions. Nonetheless, in this work, we propose that under the right conditions, electric fields can also induce interactions based on local chemical fields and diffusiophoretic flows. ExperimentsHerein, we present a strategy to generate and measure 3D chemical gradients under electric fields. In this approach, faradaic reactions at electrodes induce global pH gradients that drive long-range transport through electrodiffusiophoresis. Simultaneously, the electric field induces local pH gradients by driving the particle's double layer far from equilibrium. FindingsAs a result, while global pH gradients lead to 2D focusing away from electrodes, local pH gradients induce aggregation in the third dimension. Evidence points to a mechanism of interaction based on diffusiophoresis. Interparticle interactions display a strong dependence on surface chemistry, zeta potential and diameter of particles. Furthermore, pH gradients can be readily tuned by adjusting the voltage and frequency of the electric field. For large Péclet numbers, we observed a collective chemotactic-like collapse of particles. Remarkably, such collapse occurs without reactions at a particle's surface. By mixing particles with different sizes, we also demonstrate, through experiments and Brownian dynamics simulations, the emergence of non-reciprocal interactions, where small particles are more drawn towards large ones.

The color systematics of volcanic ashfall samples in estimating eruption sequences: a case study of the 2017–2018 eruption at Shinmoe-dake, Kirishima volcano, Southwest Japan

The color of pyroclasts is fundamental, because it reflects various magma properties and eruption processes, including particle morphology, chemistry, and petrological characteristics. However, deriving the componentry ratio (CR) of pyroclasts for ongoing eruption monitoring remains challenging due to the lack of a robust quantitative standard. The derivation of the CR, as well as other petrological analyses, is too laborious and time-consuming to introduce as a sustainable monitoring method. To address this, we employed spectroscopic colorimetry to rapidly and quantitatively describe eruptive product colors, enabling CR derivation based on clear, objective standards for ash particle classification. Through color spectroscopy of bulk and sieved ash samples, we analyzed the major size fraction for time-series samples during the waxing stage of the 2017–2018 Shinmoe-dake eruption in Kirishima volcano, Southwest Japan. Our findings reveal that the color changes in bulk ash systematically changed with the evolution of componentry. This temporal color change was due to an increase in the amount of vesicular particles with clear glass against dark angular lava particles, as well as a grain size change, which we interpret as an indication of a transition from phreatic/phreatomagmatic to magmatic eruption. Subsequently, the color of the ash changed when the amount of different lava particles increased gradually, coinciding with a shift toward a more dominant effusion of lava. As the lava effusion continued, a slight reddening of the ash, indiscernible to the naked eye, was clearly detected by the spectrometer before the onset of intermittent Vulcanian eruptions. We interpreted this reddening as oxidation resulting from decreased ascent speed and caprock formation, which accumulates overpressure for Vulcanian explosions. These results highlight the potential of rapid, objective color value and componentry derivation for sustainable quasi-real-time monitoring of ongoing eruption materials.Graphical

Mechanistic Insights into N2O5-Halide Ions Chemistry at the Air-Water Interface.

The activation of halogens (X = Cl, Br, I) by N2O5 is linked to NOx sources, ozone concentrations, NO3 reactivity, and the chemistry of halide-containing aerosol particles. However, a detailed chemical mechanism is still lacking. Herein, we explored the chemistry of the N2O5···X- systems at the air-water interface. Two different reaction pathways were identified for the reaction of N2O5 with X- at the air-water interface: the formation of XNO2 or XONO, along with NO3-. In the case of the Cl- system, the ClNO2 generation pathway is more favorable, while for the Br- and I- systems, the formation of BrONO and IONO is barrierless, making them the predominant products. Furthermore, the mechanisms of formation of X2 from XNO2 and XONO were also investigated. The high energy barriers of reactions and the high free energies of the products compared to those of the reactants indicate that ClNO2 is stable at the air-water interface. Contrary to the widely held belief regarding X2 producing from the reaction of XNO2 with X-, our calculations demonstrate that BrONO and IONO initially form stable BrONO···Br- and IONO···I- complexes, which then subsequently react with Br- and I- to form Br3- and I3-, respectively. Finally, Br3- and I3- decompose to form Br2 and I2. These findings have significant implications for experimental interpretation and offer new insights into halogen cycling in the atmosphere.

Evidence of both molecular cloud and fluid chemistry in Ryugu regolith.

The sulfur chemistry of (162173) Ryugu particles can be a powerful tracer of molecular cloud chemistry and small body processes, but it has not been well explored. We report identification of organosulfurs and a sulfate grain in two Ryugu particles, A0070 and A0093. The sulfate grain shows oxygen isotope ratios (δ17O = -11.0 ± 4.3 per mil, δ18O = -7.8 ± 2.3 per mil) that are akin to silicates in Ryugu but exhibit mass-independent sulfur isotopic fractionation (Δ33S = +5 ± 2 per mil). A methionine-like coating on the sulfate grain is isotopically anomalous (δ15N = +62 ± 2 per mil). Both the sulfate and organosulfurs can simultaneously form and survive during aqueous alteration within Ryugu's parent body, under reduced conditions, low temperature, and a pH >7 in the presence of N-rich organic molecules. This work extends the heliocentric zone where anomalous sulfur, formed by selective photodissociation of H2S gas in the molecular cloud, is found.

Role of UV radiation and oxidation on polyethylene micro- and nanoplastics: impacts on cadmium sorption, bioaccumulation, and toxicity in fish intestinal cells

This study investigated the role of ultraviolet (UV) radiation and oxidation in high-density polyethylene microplastics (2–15 μm) and nanoplastics (0.2–9.9 μm) (NMPs) on particle chemistry, morphology, and reactivity with cadmium (Cd). Additionally, toxicity of NMPs alone and with Cd was evaluated using RTgutGC cells, a model of the rainbow trout (Oncorhynchus mykiss) intestine. The role on NMPs on Cd bioaccumulation in RTgutGC cells was also evaluated. Dynamic light scattering indicated that after UV radiation NPs agglomerated size increased from 0.8 to 28 µm, and to 8 µm when Cd was added. Oxidized MPs agglomerated size increased from 11 and 7 to 46 and 27 µm in non-UV- and UV-aged oxidized MPs when adding Cd, respectively. Cd-coated particles exhibited generally significantly higher zeta potential than non-Cd-coated particles, while attenuated total reflectance–Fourier transform infrared spectroscopy showed that the functional chemistry of the particles was oxidized and modified after being exposed to UV radiation. Presence of NMPs resulted in a significant decrease in Cd bioaccumulation in RTgutGC cells (100.5–87.9 ng Cd/mg protein) compared to Cd alone (138.1 ng Cd/mg protein), although this was not quite significant for co-exposures with UV-aged NPs (105.7 ng Cd/mg protein). No toxicity was observed in RTgutGC cells exposed to NMPs alone for 24 h. Moreover, co-exposures with Cd indicated that NMPs reduce the toxicity of Cd. Altogether these results show that UV aging enhances NMP surface reactivity, increasing Cd absorption in solution, which resulted in a reduction in Cd bioavailability and toxicity.

Submicrometer Particle Impact Dynamics and Chemistry.

Experimental studies of the collision phenomena of submicrometer particles is a developing field. This review examines the range of phenomena that can be observed with new experimental approaches. The primary focus is on single-particle impact studies enabled by charge detection mass spectrometry (CDMS) implemented using the Aerosol Impact Spectrometer (AIS) at the University of California, San Diego. The AIS combines electrospray ionization, aerodynamic lens techniques, CDMS, and an electrostatic linear accelerator to study the dynamics of particle impact over a wide range of incident velocities. The AIS has been used for single-particle impact experiments on positively charged particles of diverse composition, including polystyrene latex spheres, tin particles, and ice grains, over a wide range of impact velocities. Detection schemes based on induced charge measurements and time-of-flight mass spectrometry have enabled measurements of the impact inelasticity through the determination of the coefficient of restitution, measurements of the angular distributions of scattered submicrometer particles, and the chemical composition and dissociation of solute molecules in hypervelocity ice grain impacts.

In Situ Lung Dust Analysis by Automated Field Emission Scanning Electron Microscopy With Energy Dispersive X-ray Spectroscopy: A Method for Assessing Inorganic Particles in Lung Tissue From Coal Miners.

Overexposure to respirable coal mine dust can cause severe lung disease including progressive massive fibrosis (PMF). Field emission scanning electron microscopy with energy dispersive x-ray spectroscopy (FESEM-EDS) has been used for in situ lung dust particle analysis for evaluation of disease etiology. Automating such work can reduce time, costs, and user bias. To develop and test an automated FESEM-EDS method for in situ analysis of inorganic particles in coal miner lung tissue. We programmed an automated FESEM-EDS procedure to collect particle size and elemental data, using lung tissue from 10 underground coal miners with PMF and 4 control cases. A statistical clustering approach was used to establish classification criteria based on particle chemistry. Data were correlated to PMF/non-PMF areas of the tissue, using corresponding brightfield microscopy images. Results for each miner case were compared with a separate corresponding analysis of particles recovered following tissue digestion. In situ analysis of miner tissues showed higher particle number densities than controls and densities were generally higher in PMF than non-PMF areas. Particle counts were typically dominated by aluminum silicates with varying percentages of silica. Compared to digestion results for the miner tissues, in situ results indicated lower density of particles (number per tissue volume), larger size, and a lower ratio of silica to total silicates-probably due to frequent particle clustering in situ. Automated FESEM-EDS analysis of lung dust is feasible in situ and could be applied to a larger set of mineral dust-exposed lung tissues to investigate specific histologic features of PMF and other dust-related occupational diseases.

Correlation between phase composition and physicochemical properties in Cu-, Mo-, and W- doped bismuth vanadate

We report a detailed study about the correlation between the physicochemical properties of solvothermally synthesized pristine and 1 %, 2.5 %, and 5 % Cu, Mo, and W-doped bismuth vanadate (BiVO4, BVO) with its phase composition. The effect of the dopant and the duration of synthesis (8 h and 20 h) on the physicochemical properties of BVO allowed us to tune the ratio of monoclinic scheelite to tetragonal zircon phase in BVO powders. This approach helped us to establish the relationship between the presence of monoclinic scheelite or tetragonal zircon phase with structural, morphological and optical properties of BVO powders, obtained by different physicochemical methods (e.g. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Diffuse Reflectance Spectroscopy (DRS) and Photoluminescence spectroscopy (PL)). The results indicated that, in addition to XRD, Raman, and DRS, several other methods could distinguish between the two phases. For example, SEM analysis revealed that monoclinic scheelite BVO exhibits either elongated assemblies of cube-like particles or prismatic particles with sizes ∼500 nm. In contrast, tetragonal zircon BVO exclusively exhibited porous spherical particles with diameter ∼2 μm. DRS and Raman spectroscopy indicated that there is a possibility of distinguishing between the two phases if their shares are large enough. For instance, monoclinic BVO showed band gap values in the range of 2.35–2.52 eV, while tetragonal zircon BVO exhibited values in the range of 2.80–3.00 eV. XPS showed a correlation between phase composition and surface chemistry of BVO only for Cu-doped samples, revealing the presence of Cu+ in monoclinic BVO and the presence of both Cu+ and Cu2+ in tetragonal zircon BVO. PL showed that monoclinic scheelite BVO displayed decreased charge recombination compared to tetragonal zircon BVO. Deeper insight into the correlation between the physicochemical properties and phase composition of Cu, Mo, and W-doped bismuth vanadate (BiVO4, BVO) was based on water/pentanol medium (2:1 vol%) as a novel synthesis pathway. This may open new avenues for the broader methodological exploration of surface chemistry, particle size, and morphology of BVO particles through the use of diverse functionalization agents. Finally, the established links between phase composition and structural, morphological, and other physicochemical properties provide new and more predictable opportunities for further improvement of BVO properties for various applications.

Statistical analysis and environmental impact of pre-existing particle growth events in a Northern Chinese coastal megacity: A 725-day study in 2010–2018

Pre-existing particles usually constitute the major fraction of atmospheric particles, except during some episodes in the presence of strong emissions and/or secondary generation of fresh particles. Previous case studies have investigated the growth of pre-existing particles and their potential environmental and climate impacts. However, there is limited knowledge about the statistical characteristics of these growth events and related effects. In this study, we examine pre-existing particle growth events using a large dataset (725 days from 2010 to 2018) collected at a coastal megacity in northern China. The occurrence frequency of pre-existing particle growth events was 12.4 % (90 out of 725 days). When these events were related to measured criteria air pollutants, no significant differences were found in PM2.5, SO2, NO2 and NO2 + O3 concentrations between periods with and without pre-existing particle growth events. These 90-day events can be further classified into two categories, i.e., Category 1, with 68 % of events representing the growth of pre-existing particles alone, and Category 2, with 32 % of events representing the simultaneous growth of pre-existing and newly formed particles. In Category 2, the growth rates of pre-existing particles and newly formed particles were close in 21 % of the cases, while pre-existing particles exhibited significantly larger growth rates in 69 % of the cases. Conversely, in 10 % of the cases, the growth rates of newly formed particles were larger. The different growth rate mechanisms were discussed in terms of the volatility of atmospheric condensation vapors. In addition, we present case studies on the impact of pre-existing particle growth on cloud condensation nuclei simultaneously measured, specifically considering the chemistry of condensation vapors and pre-existing particles.

Measurement report: A comparison of ground-level ice-nucleating-particle abundance and aerosol properties during autumn at contrasting marine and terrestrial locations

Abstract. Ice-nucleating particles (INPs) are an essential class of aerosols found worldwide that have far-reaching but poorly quantified climate feedback mechanisms through interaction with clouds and impacts on precipitation. These particles can have highly variable physicochemical properties in the atmosphere, and it is crucial to continuously monitor their long-term concentration relative to total ambient aerosol populations at a wide variety of sites to comprehensively understand aerosol–cloud interactions in the atmosphere. Hence, our study applied an in situ forced expansion cooling device to measure ambient INP concentrations and test its automated continuous measurements at atmospheric observatories, where complementary aerosol instruments are heavily equipped. Using collocated aerosol size, number, and composition measurements from these sites, we analyzed the correlation between sources and abundance of INPs in different environments. Toward this aim, we have measured ground-level INP concentrations at two contrasting sites, one in the Southern Great Plains (SGP) region of the United States with a substantial terrestrially influenced aerosol population and one in the Eastern North Atlantic Ocean (ENA) region with a primarily marine-influenced aerosol population. These measurements examined INPs mainly formed through immersion freezing and were performed at a ≤ 12 min resolution and with a wide range of heterogeneous freezing temperatures (Ts above −31 °C) for at least 45 d at each site. The associated INP data analysis was conducted in a consistent manner. We also explored the additional offline characterization of ambient aerosol particle samples from both locations in comparison to in situ data. From our ENA data, on average, INP abundance ranges from ≈ 1 to ≈ 20 L−1 (−30 °C ≤ T ≤ −20 °C) during October–November 2020. Backward air mass trajectories reveal a strong marine influence at ENA with 75.7 % of air masses originating over the Atlantic Ocean and 96.6 % of air masses traveling over open water, but analysis of particle chemistry suggests an additional INP source besides maritime aerosols (e.g., sea spray aerosols) at ENA. In contrast, 90.8 % of air masses at the SGP location originated from the North American continent, and 96.1 % of the time, these air masses traveled over land. As a result, organic-rich SGP aerosols from terrestrial sources exhibited notably high INP abundance from ≈ 1 to ≈ 100 L−1 (−30 °C ≤ T ≤ −15 °C) during October–November 2019. The probability density function of aerosol surface area-scaled immersion freezing efficiency (ice nucleation active surface site density; ns) was assessed for selected freezing temperatures. While the INP concentrations measured at SGP are higher than those of ENA, the ns(T) values of SGP (≈ 105 to ≈ 107 m−2 for −30 °C ≤ T ≤ −15 °C) are reciprocally lower than ENA for approximately 2 orders of magnitude (≈ 107 to ≈ 109 m−2 for −30 °C ≤ T ≤ −15 °C). The observed difference in ns(T) mainly stems from varied available aerosol surface areas, Saer, from two sites (Saer,SGP &gt; Saer,ENA). INP parameterizations were developed as a function of examined freezing temperatures from SGP and ENA for our study periods.

Anti-fogging/dry-dust transparent superhydrophobic surfaces based on liquid-like molecule brush modified nanofiber cluster structures

Transparent protective coatings capable of preventing fog and dust accumulation have broad application prospect in photovoltaic systems, optical devices and consumer electronics. Although a number of superhydrophobic coatings have been developed for self-cleaning purpose over the past three decades, there is still a lack of surfaces that can simultaneously possess high transparency, remarkable superhydrophobicity, and excellent fog and dust resistance. In this study, we have prepared surfaces featuring sub-wavelength nanofiber cluster structures through a facile plasma etching method, and further modified the surface with liquid-like perfluoropolyether (PFPE) brushes. The prepared PFPE modified nanofibrous surface (PFPE-NS) exhibits superior optical transparency (transmittance 90.4 % ± 0.7 %) and water repellency, with a water contact angle as high as 171.0° ± 0.6° and sliding angle down to 0.5° ± 0.1° (5 µL). More importantly, benefitted from the nanofiber cluster structures and the slippery liquid-like surface chemistry, the adhesion and accumulation of fog droplets and dust particles on PFPE-NS is greatly inhibited. As a consequence, PFPE-NS can keep excellent optical clearness after 2 h fogging test and maintain an average transmittance above 87 % after 24 h dusting test. Our study provides a promising strategy through constructing liquid-like nanofibrous coating for optical protection that could be applicable in practical rainy, foggy, and dusty environments.

Modeling Novel Aqueous Particle and Cloud Chemistry Processes of Biomass Burning Phenols and Their Potential to Form Secondary Organic Aerosols.

Phenols emitted from biomass burning contribute significantly to secondary organic aerosol (SOA) formation through the partitioning of semivolatile products formed from gas-phase chemistry and multiphase chemistry in aerosol liquid water and clouds. The aqueous-phase SOA (aqSOA) formed via hydroxyl radical (•OH), singlet molecular oxygen (1O2*), and triplet excited states of organic compounds (3C*), which oxidize dissolved phenols in the aqueous phase, might play a significant role in the evolution of organic aerosol (OA). However, a quantitative and predictive understanding of aqSOA has been challenging. Here, we develop a stand-alone box model to investigate the formation of SOA from gas-phase •OH chemistry and aqSOA formed by the dissolution of phenols followed by their aqueous-phase reactions with •OH, 1O2*, and 3C* in cloud droplets and aerosol liquid water. We investigate four phenolic compounds, i.e., phenol, guaiacol, syringol, and guaiacyl acetone (GA), which represent some of the key potential sources of aqSOA from biomass burning in clouds. For the same initial precursor organic gas that dissolves in aerosol/cloud liquid water and subsequently reacts with aqueous phase oxidants, we predict that the aqSOA formation potential (defined as aqSOA formed per unit dissolved organic gas concentration) of these phenols is higher than that of isoprene-epoxydiol (IEPOX), a well-known aqSOA precursor. Cloud droplets can dissolve a broader range of soluble phenols compared to aqueous aerosols, since the liquid water contents of aerosols are orders of magnitude smaller than cloud droplets. Our simulations suggest that highly soluble and reactive multifunctional phenols like GA would predominantly undergo cloud chemistry within cloud layers, while gas-phase chemistry is likely to be more important for less soluble phenols. But in the absence of clouds, the condensation of low-volatility products from gas-phase oxidation followed by their reversible partitioning to organic aerosols dominates SOA formation, while the SOA formed through aqueous aerosol chemistry increases with relative humidity (RH), approaching 40% of the sum of gas and aqueous aerosol chemistry at 95% RH for GA. Our model developments of biomass-burning phenols and their aqueous chemistry can be readily implemented in regional and global atmospheric chemistry models to investigate the aqueous aerosol and cloud chemistry of biomass-burning organic gases in the atmosphere.

Soils surrounding saline-alkaline lakes of Nhecolândia, Pantanal, Brazil: Toposequences, mineralogy and chemistry

The Nhecolândia subregion of the Brazilian Pantanal, subject to a highly seasonal climate, hosts a diverse range of freshwater and saline-alkaline lakes. The latter can be green due to cyanobacterial bloom, black due to dissolved organic matter, or crystalline. Over the past two decades, numerous studies in the region have explored the connections between the lake type, the surrounding soils, and water table dynamics. However, these insights emerged from independent studies conducted at multiple sites, making their synthesis challenging and leaving questions about the differences between lake types. Our research focuses on a representative Nhecolândia site, aiming to comprehensively understand soil and lake genesis and dynamics. For each lake type, we conducted detailed toposequence soil studies, assessing particle size distribution, chemistry and mineralogy of the <2 mm fraction of identified horizons. A 49-month temporal study utilizing PlanetScope satellite data examined lake connections to the hydrographic network affected by seasonal flooding. Our findings confirmed the general organization and mineralogy of soils around saline-alkaline lakes. Notably, we identified variations in soil toposequences corresponding to different lake type. Two types of silcrete were observed: one acidic, found at the upper slopes, and the other alkaline, located at the lower slopes. We determined that, for endorheism and lake alkalinization, the presence of a ridge around a lake is insufficient. Instead, deep impermeable horizons in the lower portion of the toposequences are essential. Additionally, crystalline lakes differentiate from black and green ones due to less efficient hydraulic isolation. Our comprehensive dataset from a single site provides a valuable resource for guiding and developing more specific studies on these alkaline systems.

Meaningful Metrics for an Efficient Solvent-Free Formulation of Polymer – Argyrodite Hybrid Solid Electrolyte

Solid-state batteries generate huge excitement with the promise of higher energy density than current Li-ion technology, thanks to the use of lithium metal at the anode1. Recent advancements in ceramic electrolytes demonstrate comparable conductivity with liquid ones2. However, the brittleness of ceramics results in mechanical limitations, during both assembly and cycling3, constraining the scale-up of pure-ceramic batteries. Hybrid solid electrolytes (HSE) can overcome this hurdle by combining the superior ionic conductivity of inorganic fillers with the scalable process of polymer electrolytes in a unique material. Depending on the amount of ceramic electrolyte, two types of HSE can be prepared: a ceramic-in-polymer approach, in which the inorganic filler disturbs the polymer crystallinity; and a polymer-in-ceramic system where the organic electrolyte mainly acts as a binder. Many parameters such as polymer molar mass, type and concentration of Li salt, chemistry and size of ceramic particles and the mixing route, make the HSE formulation an intricate process. As a result, there is a large disparity in the reported formulations and performances of HSE4. In particular, most approaches focus on a slurry-assisted preparation, which becomes a limiting factor when using sulfide-based electrolytes, as these ceramics degrade in common solvents used for binder processing5.To circumvent these issues, we propose a novel, solvent-free HSE preparation, combining an organic matrix based on poly(ethylene oxide) and lithium bis(trifluoromethanesulfonyl)imide (PEO:LiTFSI), with the highly conductive argyrodite-type Li6PS5Cl. The optimization of the HSE formulation is driven by key metrics, defined as sufficient ionic conductivity (σion ≥ 10-4 S.cm-1 @25°C) and adequate mechanical characteristics (self-standing property and ability to process as thin membrane <100 µm). Through rational screening, we elucidate the impact of formulation parameters and find the organic-to-inorganic ratio, the polymer molar mass and the ratio of mixed polymer lengths to be factors of paramount importance. Our methodology leads to an optimized formulation of the HSE with high ceramic content (75 wt.%) that meets the fixed criteria. Furthermore, we introduce an activation mechanism fitting (Arrhenius or Vulger-Tammann-Fulcher) as a new and effective metric to unravel the ionic pathway within the HSE. A shift in both ionic conductivity, mechanical cohesion and type of activation mechanism is observed at a unique threshold of 75 wt.% ceramic content. We show that our optimized polymer-in-ceramic HSE provides enhanced conduction through the ceramic network (10-4 S.cm-1 @25°C), displaying an Arrhenius activation, compared to ceramic-in-polymer HSEs, which behave as conventional PEO:LiTFSI following a VTF model. This gain in conductivity coincides with a higher mechanical resistance, as confirmed by tensile test on HSE membranes. Probing the compatibility of the organic and inorganic phases, using electrochemical impedance spectroscopy (EIS) alongside solid-state nuclear magnetic resonance (ssNMR), reveals the formation of an interphase, the quantity and resistivity of which grow with time and temperature. Finally, electrochemical performances are evaluated by assembling an HSE-based battery, which displays comparable stability as pure-ceramic ones (> 100 cycles before reaching 20% capacity loss at C/5) but still suffers from higher polarization and thus lower capacity (130 vs 150 mAh.g-1 at C/20). Janek, J. et al., Nat Energy 1, 16141 (2016).Abakumov, A. et al., Nat Commun 11, 4976 (2020).Doux, J.-M. et al., J. Mater. Chem. A 8, 5049–5055 (2020).Horowitz, Y. et al., J. Electrochem. Soc. 167, 160514 (2020).Ruhl, J. et al., Adv. Ener. Sust. Res. 2, 2000077 (2021).