Toward a complete understanding of quasi-static bubble growth and departure.

The distortion by gravity of a quasi-static bubble attached on an upward facing surface in a quiescent liquid is investigated. The contact angle evolution during the growth of such a bubble is studied, and the consequences on the motion of the contact line between the solid and the interface are discussed. From the initial case of a bubble attached to the rim of a nucleation site, the contact line can move inside the cavity for a highly wetting fluid, causing premature departure. For a higher wettability, the contact can either remain attached to the rim of the cavity or spread out of the cavity, depending on the cavity size and geometry. For the latter case, the bubble growth is investigated taking into account a contact angle hysteresis. Finally, a comprehensive map detailing various geometrical characteristics of bubbles is presented, ranging over several orders of magnitude of Bond numbers and normalized volumes. The map aims at being used as a tool for investigating bubble growth in a similar situation.

Topological wetting states of microdroplets on closed-loop structured surfaces: Breakdown of the Gibbs equation at the microscale.

Microdroplets are a class of soft matter that has been extensively employed for chemical, biochemical, and industrial applications. However, fabricating microdroplets with largely controllable contact-area shape and apparent contact angle, a key prerequisite for their applications, is still a challenge. Here, by engineering a type of surface with homocentric closed-loop microwalls/microchannels, we can achieve facile size, shape, and contact-angle tunability of microdroplets on the textured surfaces by design. More importantly, this class of surface topologies (with universal genus value = 1) allows us to reveal that the conventional Gibbs equation (widely used for assessing the edge effect on the apparent contact angle of macrodroplets) seems no longer applicable for water microdroplets or nanodroplets (evidenced by independent molecular dynamics simulations). Notably, for the flat surface with the intrinsic contact angle ~0°, we find that the critical contact angle on the microtextured counterparts (at edge angle 90°) can be as large as >130°, rather than 90° according to the Gibbs equation. Experiments show that the breakdown of the Gibbs equation occurs for microdroplets of different types of liquids including alcohol and hydrocarbon oils. Overall, the microtextured surface design and topological wetting states not only offer opportunities for diverse applications of microdroplets such as controllable chemical reactions and low-cost circuit fabrications but also provide testbeds for advancing the fundamental surface science of wetting beyond the Gibbs equation.

Low-grade wind-driven directional flow in anchored droplets.

Low-grade wind with airspeed Vwind < 5 m/s, while distributed far more abundantly, is still challenging to extract because current turbine-based technologies require particular geography (e.g., wide-open land or off-shore regions) with year-round Vwind > 5 m/s to effectively rotate the blades. Here, we report that low-speed airflow can sensitively enable directional flow within nanowire-anchored ionic liquid (IL) drops. Specifically, wind-induced air/liquid friction continuously raises directional leeward fluid transport in the upper portion, whereas three-phase contact line (TCL) pinning blocks further movement of IL. To remove excessive accumulation of IL near TCL, fluid dives, and headwind flow forms in the lower portion, as confirmed by microscope observation. Such stratified circulating flow within single drop can generate voltage output up to ~0.84 V, which we further scale up to ~60 V using drop "wind farms". Our results demonstrate a technology to tap the widespread low-grade wind as a reliable energy resource.

Impact of CAD/CAM burs lifetime on surface properties of dental zirconia: Implications for biocompatibility of custom abutments.

OBJECTIVE: To evaluate the effect of the deterioration of computer aided design/computer aided manufacturing (CAD/CAM) burs during zirconia milling, on surface roughness, contact angle, and fibroblast viability. MATERIALS AND METHODS: Ceramic blocks were milled and 75 ceramic disks (8 × 1.5 mm) made and allocated into three groups (n = 25): G1-brand new 2L and 1L burs, G2-2L bur at the end of lifetime and brand new 1L bur and G3-both burs at the end of their lifetimes. Roughness (Ra, Rq, and Rz) was evaluated using a 3D optical profilometer, the contact angle by the sessile drop method and the cell viability of the mouse NIH/3T3 fibroblast, using the Alamar Blue assay at intervals of 24, 48, and 72 h (ISO 10993-5). Data were analyzed by one-way ANOVA and Kruskal-Wallis tests (p ≤ 0.05). RESULTS: Roughness increased as the burs deteriorated and G3 (0.27 ± 0.04) presented a higher value for Ra (p < 0.001). The highest contact angle was observed in G3 (86.2 ± 2.66) when compared with G1 (63.7 ± 12.49) and G2 (75.3 ± 6.36) (p < 0.001). Alamar Blue indicated an increase in cell proliferation, with no significant differences among the groups at 24 and 72 h (p > 0.05). CONCLUSIONS: The deterioration of the burs increased the surface roughness and decreased the wettability, but did not interfere in cell viability and proliferation. CLINICAL SIGNIFICANCE: The use of custom zirconia abutments represents an effective strategy for single crowns restorations. Our findings suggest that these abutments can be efficiently milled using CAD/CAM burs within their recommended lifetime.

Enhancing Essential Oil Extraction from Lavandin Grosso Flowers via Plasma Treatment.

This study explores the impact of plasma treatment on Lavandin Grosso flowers and its influence on the extraction of essential oils (EOs) via hydrodistillation. Short plasma treatment times enhance the yield of EO extraction from 3.19% in untreated samples to 3.44%, corresponding to 1 min of plasma treatment, while longer treatment times (10 min) show diminishing returns to 3.07% of yield extraction. Chemical characterization (GC/MS and ATR-FTIR) indicates that plasma treatments do not significantly alter the chemical composition of the extracted EOs, preserving their aromatic qualities. Investigations into plasma-surface interactions reveal changes at the nanometer level, with XPS confirming alterations in the surface chemistry of Lavandin Grosso flowers by reducing surface carbon and increasing oxygen content, ultimately resulting in an increased presence of hydrophilic groups. The presence of hydrophilic groups enhances the interaction between the surface membrane of the glandular trichomes on Lavandin Grosso flowers and water vapor, consequently increasing the extraction of EOs. Furthermore, microscopic SEM examinations demonstrate that plasma treatments do not affect the morphology of glandular trichomes, emphasizing that surface modifications primarily occur at the nanoscale. This study underscores the potential of plasma technology as a tool to enhance EO yields from botanical sources while maintaining their chemical integrity.

Starch-Based Polysaccharide Systems with Bioactive Substances: Physicochemical and Wettability Characteristics.

Polysaccharide-based systems have very good emulsifying and stabilizing properties, and starch plays a leading role. Their modifications should add new quality features to the product to such an extent that preserves the structure-forming properties of native starch. The aim of this manuscript was to examine the physicochemical characteristics of the combinations of starch with phospholipids or lysozymes and determine the effect of starch modification (surface hydrophobization or biological additives) and preparation temperature (before and after gelatinization). Changes in electrokinetic potential (zeta), effective diameter, and size distribution as a function of time were analyzed using the dynamic light scattering and microelectrophoresis techniques. The wettability of starch-coated glass plates before and after modification was checked by the advancing and receding contact angle measurements, as well as the angle hysteresis, using the settle drop method as a complement to profilometry and FTIR. It can be generalized that starch dispersions are more stable than analogous n-alkane/starch emulsions at room and physiological temperatures. On the other hand, the contact angle hysteresis values usually decrease with temperature increase, pointing to a more homogeneous surface, and the hydrophobization effect decreases vs. the thickness of the substrate. Surface hydrophobization of starch carried out using an n-alkane film does not change its bulk properties and leads to improvement of its mechanical and functional properties. The obtained specific starch-based hybrid systems, characterized in detail by switchable wettability, give the possibility to determine the energetic state of the starch surface and understand the strength and specificity of interactions with substances of different polarities in biological processes and their applicability for multidirectional use.

Influence of fluoride characteristics on tooth surface protection in an erosive condition: A multifaceted characterization approach.

OBJECTIVE: To evaluate the effect of fluoride consistency and composition to protect enamel and dentin against the dental erosion. MATERIALS AND METHODS: Bovine enamel and dentin specimens were treated with artificial saliva, neutral fluoride gel (NFG), acidulated phosphate fluoride gel (AFG), neutral fluoride foam (NFF), and acidulated phosphate fluoride foam. The samples were subjected to cycling. Micro energy-dispersive X-ray fluorescence spectrometry, surface roughness (Ra), contact angle (CA), and scanning electron microscopy (SEM) were performed. Composition, CA and Ra data were analyzed by ANOVA and multiple comparison test (p < 0.05). RESULTS: The dentin protected had a significantly higher mineral content than in the control. Eroded unprotected enamel had higher Ra values than normal surfaces. Fluoride treatments increased the Ra in dentin samples. AFG increased the CA in enamel. Fluoride foams increased CA in dentin with reduced mineral loss. SEM analysis found a deposited layer on enamel treated with AFG and remnants of deposits on dentin treated with NFG and NFF. CONCLUSION: Regardless of the form of application, fluoride provided protection against erosion, however with different levels. CLINICAL SIGNIFICANCE: Applying the adequate fluoride form is relevant since the formulations have different effects on both enamel and dentin.

Effect of Anionic Surfactants on the Oil-Water-Rock Interactions by an Improved Washburn Method.

The complex and variable structure of subsurface oil reservoirs as well as the small pore throat size of reservoirs make it extremely important to investigate the effect of oil-water-rock interactions for enhancing oil recovery. In this paper, the powder wettability of oil sand with different polar solvents was investigated using the improved Washburn capillary rise method, and the surface free energy of oil sand was calculated in combination with the OWRK method. In addition, the wettability of anionic surfactants HABS and PS solutions on the surface of oil sand was determined, and it showed that their wetting rates showed different trends after CMC (critical micelle concentration). The C×cosθ value of HABS decreased significantly with increasing concentration, whereas PS showed little changes. This may be related to the aggregate structure formed by HABS on the oil sand surface. Meanwhile, the interfacial free energy between crude oil and oil sand was obtained by crude oil-to-oil sand wetting experiments, and found that the wetting rate of crude oil to oil sand was much lower than that of solvents and surfactants. In combination with the above results and the oil-water interfacial tension (IFT), the oil-water-rock three-phase contact angle and the work of adhesion between the crude oil and the solid were obtained by Young's equation. From the three-phase contact angle results, it can be found that the contact angle values of both HABS and PS are obviously higher than that of the simulated water, and both HABS and PS have the ability to significantly reduce the work of adhesion, which shows a strong ability to strip the oil film on the surface of the solid. The research results of this paper are helpful to understand the oil displacement mechanism of chemical flooding in reservoir pores, which is of great significance for improving oil recovery.

Surface-Active Ionic Liquids and Surface-Active Quaternary Ammonium Salts from Synthesis, Characterization to Antimicrobial Properties.

The present work provides new evidence of the ongoing potential of surface-active ionic liquids (SAILs) and surface-active quaternary ammonium salts (surface-active QASs). To achieve this, a series of compounds were synthesized with a yield of ≥85%, and their thermal analyses were studied. Additionally, antimicrobial activity against both human pathogenic and soil microorganisms was investigated. Subsequently, their surface properties were explored with the aim of utilizing SAILs and surface-active QASs as alternatives to commercial amphiphilic compounds. Finally, we analyzed the wettability of the leaves' surface of plants occurring in agricultural fields at different temperatures (from 5 to 25 °C) and the model plant membrane of leaves. Our results show that the synthesized compounds exhibit higher activity than their commercial analogues such as, i.e., didecyldimethylammonium chloride (DDAC) and dodecyltrimethylammonium bromide (C12TAB), for which the CMC values are 2 mM and 15 mM. The effectiveness of the antimicrobial properties of synthesized compounds relies on their hydrophobic nature accompanied by a cut-off effect. Moreover, the best wettability of the leaves' surface was observed at 25 °C. Our research has yielded valuable insights into the potential effectiveness of SAILs and surface-active QASs as versatile compounds, offering a promising alternative to established antimicrobials and crop protection agents, all the while preserving substantial surface activity.

Regulating Microstructure and Macroscopic Properties in Saturated Salt Solutions Containing Disordered Anions and Cations by Magnetic Field.

Saturated aqueous salt solutions have diverse applications in food production, mineral processing, pharmaceuticals, and environmental monitoring. However, the random and disordered arrangement of ions in these solutions poses limitations across different fields. In this study, we employ magnetic fields to regulate the disordered arrangement by a comprehensive methodology combining contact angle measurement, Raman spectroscopy, X-ray diffraction, and molecular dynamics simulations on saturated KCl solutions. Our findings reveal that weak magnetic fields impede the formation of K-Cl contact pairs and disrupt hydrogen bond networks, particularly DDAA and free OH types. However, they facilitate the interaction between water molecules and ions, leading to an increase in the number of K-O and Cl-H contact pairs, along with an expansion in ion hydration radius. These changes affect macroscopic properties, including the interaction with solid substrates and potential solubility increases. Our experimental and simulation results mutually validate each other, contributing to a theoretical framework for studying magnetic field-material interactions.

Self-Assembled Monolayers of a Fluorinated Phosphonic Acid as a Protective Coating on Aluminum.

Aluminum (Al) placed in hot water (HW) at 90 °C is roughened due to its reaction with water, forming Al hydroxide and Al oxide, as well as releasing hydrogen gas. The roughened surface is thus hydrophilic and possesses a hugely increased surface area, which can be useful in applications requiring hydrophilicity and increased surface area, such as atmospheric moisture harvesting. On the other hand, when using HW to roughen specified areas of an Al substrate, ways to protect the other areas from HW attacks are necessary. We demonstrated that self-assembled monolayers (SAMs) of a fluorinated phosphonic acid (FPA, CF3(CF2)13(CH2)2P(=O)(OH)2) derivatized on the native oxide of an Al film protected the underneath metal substrate from HW attack. The intact wettability and surface morphology of FPA-derivatized Al subjected to HW treatment were examined using contact angle measurement, and scanning electron microscopy and atomic force microscopy, respectively. Moreover, the surface and interface chemistry of FPA-derivatized Al before and after HW treatment were investigated by time-of-flight secondary ion mass spectrometry (ToF-SIMS), verifying that the FPA SAMs were intact upon HW treatment. The ToF-SIMS results therefore explained, on the molecular level, why HW treatment did not affect the underneath Al at all. FPA derivatization is thus expected to be developed as a patterning method for the formation of hydrophilic and hydrophobic areas on Al when combined with HW treatment.

Evaluation of surface tensions and root-dentin surface contact angles of different endodontic irrigation solutions.

BACKGROUND: Surface tension and contact angle properties, which play a crucial role in determining the effectiveness of irrigation solutions in penetrating dentin surfaces and dentin tubules, are highly important for the development of new irrigation solutions and their preferences. The aim of the current study was to compare the surface tension and contact angle properties of different irrigation solutions used in endodontics, both on the dentin surface and within dentin tubules. METHODS: In this study, the contact angles and surface tensions of 5.25% sodium hypochlorite (NaOCl), 17% ethylenediaminetetraacetic acid (EDTA), 2% chlorhexidine (CHX), 5% boric acid (BA), 0.02% hypochlorous acid (HOCl), 0.2% chlorine dioxide (ClO2), Biopure MTAD, QMix solutions, and distilled water (control group) were measured. Measurements were conducted using a goniometer device (Attension Theta Lite Tensiometer, Biolin Scientific, USA), employing the sessile drop method for contact angle measurements on pre-prepared dentin surfaces, and the pendant drop method for surface tension. RESULTS: Contact angle measurements revealed no statistically significant differences between the contact angle values of MTAD, ClO2, and CHX or between NaOCl, QMix, BA, and HOCl (p > 0.05). However, EDTA exhibited a significantly greater contact angle than did MTAD, ClO2, CHX, NaOCl, QMix, BA, and HOCl (p < 0.05). Furthermore, the contact angle of dentin with distilled water was greater than that with all other solutions tested (p < 0.05). Surface tension measurements revealed that the surface tension values of QMix and MTAD were statistically similar (p > 0.05). CHX exhibited lower surface tension than distilled water and HOCl (p < 0.05), and it also had lower surface tension than ClO2, NaOCl, and BA (p < 0.05). Additionally, the surface tension of the samples treated with EDTA was greater than that of all other solutions tested (p < 0.05). CONCLUSION: The direct linear relationship between the surface tension of liquids and contact angles on different surfaces may not always hold true, and these values should be considered independently for each solution on various surfaces. Considering the contact angles and surface tension properties of irrigation solutions with root canal dentin, it can be suggested for clinical use that ClO2 could be recommended over NaOCl, and similarly, BA could be recommended over EDTA.

Evaluation and assessment of the wettabilty and water contact angle of modified poly methyl methacrylate denture base materials against PEEK in cast partial denture framework: an in vitro study.

INTRODUCTION: The prevalence of adults with partially dental arches is expected to be more than imagined and patients requiring replacement of missing teeth are slowly increasing in number too. Removable partial dentures are known to provide for substantial replacement for the missing teeth with also added advantages when compared to fixed or implant prosthesis, mainly in elderly patients. Denture base material performance and durability are greatly influenced by wettability and water contact angle. In the case of dentures; adequate moisture distribution is necessary to ensure excellent wettability which has an influence on comfort and oral health. The purpose of conducting this study was to find out whether the advancements made using PEEK (Polyether ether ketone) would prove to be more beneficial than the current upgrades in the current material spectrum. MATERIALS AND METHODS: This study was performed under in vitro conditions. All the fabrication and processing was done only by one operator. The materials used were divided into three groups each comprising 20 samples. Group A was modified polymethylmethacrylate (Bredent Polyan), Group B was polyoxymethylene acetal resin (Biodentaplast) and Group C was PEEK. An Ossila Goniometer was used to measure the contact angle. The three types of liquids used for the testing included distilled water, natural saliva and mouth wetting solution (Wet Mouth Liquid, ICPA India). Human saliva was collected from an individual with no medical conditions and normal salivary secretion. RESULTS: The data was analyzed using One-way ANOVA test and a pairwise comparison using the Post Hoc Tukey's Honest Significant Difference. Table 1 consists of the mean water contact angles of the denture base materials and mean contact angles of various denture base materials. In saliva, mouth wetting solution and distilled water, the highest mean and least mean contact angle was seen in Polyan and Biodentaplast respectively. A signicant difference was seen between PEEK and Polyan and Biodentaplast and Polyan on further comparison. CONCLUSION: From the resources and the materials at our disposal, it could be concluded that Polyan, Biodentaplast and PEEK and could be used as viable options in cast partial denture framework.

Statistical Mechanics of Electrowetting.

We derive the ab initio equilibrium statistical mechanics of the gas-liquid-solid contact angle on planar periodic, monodisperse, textured surfaces subject to electrowetting. To that end, we extend an earlier theory that predicts the advance or recession of the contact line amount to distinct first-order phase transitions of the filling state in the ensemble of nearby surface cavities. Upon calculating the individual capacitance of a cavity subject to the influence of its near neighbors, we show how hysteresis, which is manifested by different advancing and receding contact angles, is affected by electrowetting. The analysis reveals nine distinct regimes characterizing contact angle behavior, three of which arise only when a voltage is applied to the conductive liquid drop. As the square voltage is progressively increased, the theory elucidates how the drop occasionally undergoes regime transitions triggering jumps in the contact angle, possibly changing its hysteresis, or saturating it at a value weakly dependent on further voltage growth. To illustrate these phenomena and validate the theory, we confront its predictions with four data sets. A benefit of the theory is that it forsakes trial and error when designing textured surfaces with specific contact angle behavior.

Leaf wettability and leaf angle affect air-moisture deposition in wheat for self-irrigation.

BACKGROUND: Climate change and depleting water sources demand scarce natural water supplies like air moisture to be used as an irrigation water source. Wheat production is threatened by the climate variability and extremes climate events especially heat waves and drought. The present study focused to develop the wheat plant for self-irrigation through optimizing leaf architecture and surface properties for precise irrigation. METHODS: Thirty-four genotypes were selected from 1796 genotypes with all combinations of leaf angle and leaf rolling. These genotypes were characterized for morpho-physiological traits and soil moisture content at stem-elongation and booting stages. Further, a core set of ten genotypes was evaluated for stem flow efficiency and leaf wettability. RESULTS: Biplot, heat map, and correlation analysis indicated wide diversity and traits association. The environmental parameters indicated substantial amount of air moisture (> 60% relative humidity) at the critical wheat growth stages. Leaf angle showed negative association with leaf rolling, physiological and yield traits, adaxial and abaxial contact angle while leaf angle showed positive association with the stem flow water. The wettability and air moisture harvesting indicated that the genotypes (coded as 1, 7, and 18) having semi-erect to erect leaf angle, spiral rolling, and hydrophilic leaf surface (<90o) with contact angle hysteresis less than 10o had higher soil moisture content (6-8%) and moisture harvesting efficiency (3.5 ml). CONCLUSIONS: These findings can provide the basis to develop self-irrigating, drought-tolerant wheat cultivars as an adaptation to climate change.

Thermoresponse of Odd-Even Effect in n-Alkanethiolate Self-Assembled Monolayers on Gold Substrates.

This study examines thermoresponse of odd-even effect in self-assembled monolayers (SAMs) of n-alkanethiolates (SCn , n=3-18) formed on template-stripped gold (AuTS ) using macro- and microscopic analytical techniques, contact angle goniometry (CAG) and vibrational sum frequency generation (VSFG) spectroscopy, respectively. Both CAG and VSFG analyses showed that the odd-even effect in liquid-like SAMs (n=3-9) disappeared upon heating at 50-70 °C, indicating that the heating led to increased structural disorder regardless of odd and even carbon numbers. In contrast, the opposite thermoresponse was observed for odd and even SCn molecules in wax- and solid-like SAMs (n=10-18). Namely, temperature-dependent orientational change of terminal CH3 relative to the surface normal was opposite for the odd and even molecules, thereby leading to mitigated odd-even effect. Our work offers important insights into thermoresponse of supramolecular structure in condensed organic matter.

Wettability and morphology of proboscises interweave with hawkmoth evolutionary history.

Hovering hawkmoths expend significant energy while feeding, which should select for greater feeding efficiency. Although increased feeding efficiency has been implicitly assumed, it has never been assessed. We hypothesized that hawkmoths have proboscises specialized for gathering nectar passively. Using contact angle and capillary pressure to evaluate capillary action of the proboscis, we conducted a comparative analysis of wetting and absorption properties for 13 species of hawkmoths. We showed that all 13 species have a hydrophilic proboscis. In contradistinction, the proboscises of all other tested lepidopteran species have a wetting dichotomy with only the distal ∼10% hydrophilic. Longer proboscises are more wettable, suggesting that species of hawkmoths with long proboscises are more efficient at acquiring nectar by the proboscis surface than are species with shorter proboscises. All hawkmoth species also show strong capillary pressure, which, together with the feeding behaviors we observed, ensures that nectar will be delivered to the food canal efficiently. The patterns we found suggest that different subfamilies of hawkmoths use different feeding strategies. Our comparative approach reveals that hawkmoths are unique among Lepidoptera and highlights the importance of considering the physical characteristics of the proboscis to understand the evolution and diversification of hawkmoths.

Perspectives on the Wetting of Solids in Pharmaceutical Systems.

PURPOSE: The ability of water and aqueous solutions to wet relatively nonpolar pharmaceutical solids during the processing and administration of solid dosage forms is an important part of development. RESULTS: Various factors, both fundamental and technological, which are important to wettability are reviewed and analyzed. Initially, the ideal thermodynamic importance of liquid surface tension and solid surface energetics, determined by the contact angle and the polarity of the solid surface, are established. Then, emphasis is placed on various factors that change the surface energetics due to crystal defects, polymorphism, varying Miller Indices, crystal habit, amorphous structure, variable surface concentration of components in a formulation mixture, surface roughness, and complex pore structure. Case studies cover single component systems (APIs and excipients), binary mixtures (amorphous solid dispersions and physical mixtures), multicomponent systems (granules and tablets), as well as disintegration and dissolution of solid oral dosage forms. CONCLUSIONS: This perspective and analysis indicates the primary importance of understanding and modifying solid surface energetics, surface chemical and physical heterogeneities, and pore structure to promote wettability in pharmaceutical systems.

Effects of Leaf Morphological and Chemical Properties on the Population Sizes of Epiphytes.

To explore the main factors affecting the distribution of microbes on leaf surfaces, the relationship between population sizes of epiphytes and the morphological structure and main physical and chemical properties of leaves from stylo (Stylosanthes guianensis), alfalfa (Medicago sativa), maize (Zea mays), and cocksfoot (Dactylis glomerata) were investigated. The research results showed that the contents of soluble sugar and total phenolics on the leaf surfaces were positively correlated with those in the leaf tissues (P < 0.001). The leaves with high wax content had better moisture retention capacity. The content of soluble sugar on the leaf surfaces was positively correlated with population sizes of lactic acid bacteria (LAB), aerobic bacteria, yeasts, and molds (P < 0.001). Likewise, a positive correlation was found between the content of inorganic phosphorus on the leaf surfaces and population sizes of LAB and aerobic bacteria. The total amount of wax on leaf surfaces was negatively related to population sizes of microbes, especially aerobic bacteria (P < 0.01) and molds (P < 0.001). On the contrary, the presence of trichomes provides a shelter for epiphytes and was positively correlated with population sizes of epiphytes at different degrees of significance. In conclusion, population sizes of epiphytes on the leaf surfaces were not only affected by chemical properties, but also by morphological traits of leaves.

Rapid Simulation of Decade-Scale Charcoal Aging in Soil: Changes in Physicochemical Properties and Their Environmental Implications.

In situ aging can change biochar properties, influencing their ecosystem benefits or risks over time. However, there is a lack of field verification of laboratory methods that attempt simulation of long-term natural aging of biochar. We exploited a decade-scale natural charcoal (a proxy for biochar) aging event to determine which lab-aging methods best mimicked field aging. We oxidized charcoal by ultraviolet A radiation (UVA), H2O2, or monochloramine (NH2Cl), and compared it to 10-year field-aged charcoal. We considered seven selected charcoal properties related to surface chemistry and organic matter release, and found that oxidation with 30% H2O2 most representatively simulated 10-year field aging for six out of seven properties. UVA aging failed to approximate oxidation levels while showing a distinctive dissolved organic carbon (DOC) release pattern. NH2Cl-aged charcoal was the most different, showing an increased persistent free radical (PFR) concentration and lower hydrophilicity. All lab oxidation techniques overpredicted polycyclic aromatic hydrocarbon release. The O/C ratio was well-correlated with DOC release, PFR concentration, surface charge, and charcoal pH, indicating the possibility to accurately predict biochar aging with a reduced suite of physicochemical properties. Overall, our rapid and verified lab-aging methods facilitate research toward derisking and enhancing long-term benefits of biochar application.