Weak Hydrophobicity Research Articles

Emergence of Aeromonas salmonicida subsp. masoucida MHJM250: unveiling pathological characteristics and antimicrobial susceptibility in golden mahseer, Tor putitora (Hamilton, 1822) in India.

Aeromonas salmonicida subsp. masoucida, designated as laboratory strain MHJM250, was characterized from a naturally infected farmed golden mahseer, Tor putitora. The infected fish exhibited clinical signs of erosion at the caudal fin and hemorrhage onx the ventral body surface. Molecular identification through 16S rDNA and phylogenetic analysis revealed 100% similarity with a known strain A. salmonicida subsp. masoucida (MT122821.1). MHJM250 exhibited positive reactions for oxidase, catalase, esculin, MR-VP, O/F and utilized arginine and lysine. It also demonstrated siderophore activity, thrived at various NaCl concentrations, hydrolyzed gelatinase, skimmed milk and casinase. In vitro studies exhibited its hemolytic nature, significant biofilm production in glucose-rich tryptone soya broth and beta-hemolysis. MHJM250 didn't produce slime and was non-precipitated upon boiling. It showed crystal violet binding characteristics and auto-agglutination with relatively weak hydrophobicity (25%). In the challenge assay, intraperitoneal administration of MHJM250 to T. pitutora fingerlings at 108 CFU mL-1 resulted in pathogenicity with 3% mortality and mild hemorrhagic symptoms. Histopathological analysis revealed degenerative changes in gill, kidney, liver, muscle, and intestine samples. The bacterium displayed resistance to several antibiotics (µg/disc); ampicillin (10µg), ampicillin/ sulbactam (10/10 µg), clindamycin (2µg), linezolid (30µg), penicillin G (10µg) and rifampicin (5µg) and varied minimum inhibitory concentrations against oxytetracycline, erythromycin and florfenicol. Transmission electron microscopy showed its rod-shaped structure with single polar flagellum and lophotrichous flagella. An investigation on the molecular basis for virulence factors of A. salmonicida subsp. masoucida MHJM250 may offer crucial understandings to formulate disease prevention and control strategies in aquaculture.

Structure-dependent destructive adsorption of organophosphate flame retardants on lipid membranes

The widespread use of organophosphate flame retardants (OPFRs), a serious type of pervasive environmental contaminants, has led to a global concern regarding their diverse toxicities to living beings. Using a combination of experimental and theoretical approaches, we systematically studied the adsorption, accumulation, and influence of a series of OPFRs on the lipid membranes of bacteria and cells. Our results revealed that OPFRs can aggregate in lipid membranes, leading to the destruction of membrane integrity. During this process, the molecular structure of the OPFRs is a dominant factor that significantly influences the strength of their interaction with the lipid membrane, resulting in varying degrees of biotoxicity. Triphenyl phosphate (TPHP), owing to its large molecular size and strong hydrophobicity, causes severe membrane disruption through the formation of nanoclusters. The corresponding severe toxicity originates from the phase transitions of the lipid membranes. In contrast, smaller OPFRs such as triethyl phosphate (TEP) and tris(2-chloroethyl) phosphate (TCEP) have weaker hydrophobicity and induce minimal membrane disturbance and ineffective damage. In vivo, gavage of TPHP induced more severe barrier damage and inflammatory infiltration in mice than TEP or TCEP, confirming the higher toxicity of TPHP. Overall, our study elucidates the structure-dependent adsorption of OPFRs onto lipid membranes, highlighting their destructive interactions with membranes as the origin of OPFR toxicity.

In-Depth Characterization for Methionine Oxidization in Complementary Domain Region by Hydrophobic Interaction Chromatography.

The oxidation of the complementarity-determining region (CDR) in monoclonal antibodies (mAbs) is a critical quality attribute that can affect the clinical efficacy and safety of recombinant mAb therapeutics. In this study, a robust hydrophobic interaction chromatography (HIC) method was developed to quantify and characterize CDR oxidation variants in mAb-A by using a Proteomix Butyl-NP5 column. The HIC analysis revealed oxidation variants that eluted earlier than the main species with weaker hydrophobicity. It was found that Met105 in the CDR was more susceptible to oxidation. Additionally, it was noted that the oxidation of Met105 on a single heavy chain resulted in elution at a distinct position compared to the oxidation on two heavy chains. This observation led to the fractionation and enrichment of the oxidized variants for further evaluation of their biofunction. The study also demonstrated that the oxidation of Met105 did not impact the antigen-binding capacity but significantly reduced the PD-1/PD-L1 blockade activity of mAb-A. The HIC method, which was employed to quantify CDR oxidation, underwent validation and was subsequently utilized for stability studies as well as for assessing the similarity between mAb-A and its reference product.

Impact of Local Environment on Selectivity of Ag and Cu Gas Diffusion Electrodes with Strong Hydrophobic Substrate during the Electrochemical Reduction of CO2

Electrochemical CO2 reduction (CO2RR) is a promising pathway to convert detrimental CO2 emissions into sustainable fuels and chemicals, and close the carbon loop1. To ensure the industrial applicability of this technology, electrocatalysts need to be highly active, selective towards a desired product, and offer long-term stability. High activity can be achieved with gas diffusion electrodes (GDEs), in which the CO2 reactant is supplied directly from the gas phase, however reaching high selectivity toward a single product over time remains a challenge. Recently, the control of the local environment around the catalyst has been identified to be a key factor to ensure high selectivity and stability2.In this work, we show that the local environment around the catalyst drives the selectivity of the catalyst depending on the pore size and hydrophobicity of the GDE. GDEs with large pores and weak hydrophobicity lead to poor selectivity toward carbon products, while GDEs with small pore and strong hydrophobicity yield a greatly improved Faradaic efficiency (FE) towards CO in the case of Ag (FE > 70%)2 and towards C2H4 in the case of Cu (FE > 50%) 3 at 200 mA/cm2 for several hours. The further increase of current density is detrimental to the performance of the GDEs, which points to a limitation of the transport of CO2 to the electrocatalyst. Additionally, CO reduction experiments show a qualitatively similar behavior but at much lower current densities. These findings are consistent with the presence of an electrolyte layer wetting the electrocatalyst that forces the electrocatalytic reaction to take place at double phase boundaries. Finally, we provide evidence for the correlation between the loss of selectivity towards carbon products over time and the precipitation of carbonates by operando synchrotron X-rays diffraction experiments4.In summary, our results highlight the importance of controlling the local environment near the catalyst to enhance the selectivity towards carbon products during CO2RR. References 1A. Senocrate, C. Battaglia, J. Energy Storage 2021, 36, 102373 2A. Senocrate, F. Bernasconi, D. Rentsch, K. Kraft, M. Trottmann, A. Wichser, D. Bleiner, C. Battaglia, ACS Appl. Energy Mater. 2022, 5, 14504 3F. Bernasconi, A. Senocrate, P. Kraus, C. Battaglia, Energy & Environ. Science Catalysis, 2023, 1, 1009 4F. Bernasconi, A. Senocrate, N. Plainpan, M. Mirolo, Q. Wang, C. Battaglia, submitted

Synergizing tetra-coordinated Ti sites anchored onto micropore-free silica with Au sites to boost propylene hydro-oxidation

Constructing tetra-coordinated Ti sites on the micropore-free oxide surface as a substitute for the Ti-containing zeolites to synergize with Au sites for propylene epoxidation with H2 and O2 to propylene oxide (HOPO) can solve the problems resulting from micropores but remains a great challenge. Here, we report a facile strategy to anchor tetra-coordinated Ti sites onto micropore-free silica by precisely cleaving the surface hydroxyl and siloxane bridges of silica to generate under-coordinated O sites to bind Ti sites. Multiple spectroscopic characterizations, including ultraviolet Raman, UV–vis and Fourier transformation infrared and 29Si solid nuclear magnetic resonance spectroscopy, demonstrate the anchored Ti sites on the surface of silica are mainly the target tetra-coordinated ones. It is further unveiled that the removal of surface hydroxyl also improves the hydrophobicity of synthesized Ti-SiO2, which enhances the desorption of PO. Benefitting from the weak acidic properties, high hydrophobicity and micropore-free structures, the tetra-coordinated Ti sites on silica synergize well with Au sites in propylene epoxidation, demonstrating high activity, selectivity and stability, which are superior to those achieved on the most extensively researched Au/TS-1 catalysts.

Comparative Study of Using Superhydrophobic and Icephobic Surface Coatings for Aircraft Icing Mitigation

We report a comparative study to evaluate the effects of surface coatings with different hydrophobicities and icephobicities on the performance of a hybrid anti-/de-icing system that integrates surface heating with hydro-/ice-phobic coating for aircraft icing mitigation. While a flexible electric film heater wrapped around the leading edge of an airfoil/wing model was used to heat the airfoil frontal surface to prevent ice accretion near the airfoil leading edge, three different kinds of coatings were applied to coat the airfoil model at three distinct spanwise locations, which included an icephobic coating with an outstanding icephobicity but a weak hydrophobicity; a superhydrophobic surface (SHS) coating with outstanding water repellency but a moderate icephobicity; and a commonly used hydrophilic coating with poor hydrophobicity and poor icephobicity. Surface wettability was found to play a more important role than icephobicity in affecting the performance of the hybrid anti-/de-icing systems. In comparison to the approach of forceful heating the hydrophilic airfoil surface, the hybrid approach with the SHS coating was found to be able to achieve about 90% energy savings in keeping the entire airfoil surface ice-free; the corresponding energy savings for the hybrid system with the icephobic coating was only about 10%.

Effect of Hydrophilic and Hydrophobic Composite Microporous Layer Coated Gas Diffusion Layers on PEFC Performance

In order to widen the market application of the polymer electrolyte fuel cell (PEFC), the output power of the PEFC system must be increased. One of the barriers is the cell voltage loss under high current density conditions. This is mainly caused by the deteriorated reactant mass transport, which is blocked by the water flooding at the catalyst layer (CL), microporous layer (MPL), and gas diffusion layer (GDL). Modifying the MPL coated on the GDL is an accessible way to provide better water management for PEFCs to elongate the operating range of the cell, so a novel MPL-coated GDL should be developed to realize the goal. Previously, we evaluated double MPL-coated GDLs, which coated a thin hydrophilic layer on the hydrophobic MPL-coated GDL in the through-plane direction. The extra hydrophilic layer was influential in promoting the introduction of water into the small pores of the hydrophobic MPL, enhancing the ability to reduce flooding, and the oxygen transport resistance under high humidity conditions can be declined.The present study evaluates a novel composite MPL that the hydrophobic and hydrophilic pores are randomly allocated in the same layer. Excess water is expelled from the hydrophilic pores while maintaining gas transport by the hydrophobic pores. To determine the appropriate hydrophobic and hydrophilic compositions, we first evaluated the most commonly used hydrophobic polytetrafluoroethylene (PTFE) binder, and the contact angle of PTFE-MPL was 136°. Polyvinyl alcohol (PVA) was chosen as the hydrophilic binder, and the contact angle of PVA-MPL was 105°. The slurry containing PTFE, PVA, carbon black, and distilled water was mixed using a mixer and then spread on the carbon paper substrate by a bar coating machine. The temperature was heated at 350°C to sinter the MPL on the substrate. However, the sintering temperature of PVA should be lower than 150°C, so the PVA in the composite MPL was burned and led to a similar contact angle as the PTFE-MPL. Meanwhile, the performance enhancement could not be obtained compared with a PTFE-MPL-coated GDL. Oppositely, when decreasing the sintering temperature to 150C°, the PTFE-PVA composite MPL demonstrated strong hydrophilicity with a small contact angle value, and the performance was exacerbated than the PTFE-MPL. Therefore, to coordinate the lower sintering temperature of PVA, polyvinylidene difluoride (PVDF) was selected as the hydrophobic binder. The contact angle of PVDF-MPL was 143°. After the PVA was preserved, the unexpectedly strong hydrophilicity was exhibited in PVDF-PVA composite MPL, aggravating the liquid water accumulation in the MPL and without performance improvement. Finally, the Nafion ionomer with relatively weak hydrophobicity was used for the composite MPL. As a hydrophilicity complement, titanium dioxide (TiO2) particles were added to the slurry to control hydrophilicity. The contact angle of Nafion/TiO2-MPL was 113°. Similarly, the Nafion/TiO2-PVDF composite MPL indicated a contact angle of 114°, and the water permeability test proved that separate hydrophobic and hydrophilic pores were generated.The oxygen transport resistances were measured based on the limiting current density values of polarization curves to evaluate the ability of the MPL-coated GDL to reduce flooding under high humidity conditions. The active area of the MEA was 1.0 cm2, and the cell temperature was kept at 35°C. Pure hydrogen and diluted oxygen (2 vol% O2 and 98 vol% N2) gases were supplied at the anode and cathode, respectively, and the flow rates were set at 1000 cm3 min-1. The relative humidity of gases supplied to the anode and cathode was 200%RH, and the gas backpressure was set at zero. The oxygen transport resistance of the Nafion/TiO2-PVDF composite MPL-coated GDL was lower than that obtained with a commercial SGL-22BB GDL. Thus, an appropriate composite MPL-coated GDL effectively enhanced PEFC performance under high humidity conditions.

Highly Hydrophobic Gelatin Nanocomposite Film Assisted by Nano-ZnO/(3-Aminopropyl) Triethoxysilane/Stearic Acid Coating for Liquid Food Packaging.

Biodegradable gelatin (G) food packaging films are in increasing demand as the substitution of petroleum-based preservative materials. However, G packaging films universally suffer from weak hydrophobicity in practical applications. Constructing a hydrophobic micro/nanocoating with low surface energy is an effective countermeasure. However, the poor compatibility with the hydrophilic G substrate often leads to the weak interfacial adhesion and poor durability of the hydrophobic coating. To overcome this obstacle, we used (3-aminopropyl) triethoxysilane (APS) as an interfacial bridging agent to prepare a highly hydrophobic, versatile G nanocomposite film. Specifically, tannic acid (TA)-modified nanohydroxyapatite (n-HA) particles (THA) were introduced in G matrix (G-THA) to improve the mechanical properties. Micro/nanostructure with low surface energy composed of nanozinc oxide (Nano-ZnO)/APS/stearic acid (SA) (NAS) was constructed on the surface of G-THA film (G-THA/NAS) through one-step spray treatment. Consequently, as-prepared G-THA/NAS film presented excellent mechanics (tensile strength: 7.6 MPa, elongation at break: 292.7%), water resistance ability (water contact angle: 150.4°), high UV-shielding (0% transmittance at 200 nm), degradability (100% degradation rate after buried in the natural soil for 15 days), antioxidant (78.8% of 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity), and antimicrobial (inhibition zone against Escherichia coli: 15.0 mm and Staphylococcus aureus: 16.5 mm) properties. It should be emphasized that the bridging function of APS significantly improves the interfacial adhesion ability of the NAS coating with more than 95% remaining area after the cross-cut adhesion test. Meanwhile, the G-THA/NAS film could maintain stable and long-lasting hydrophobic surfaces against UV radiation, high temperature, and abrasion. Based on these multifunctional properties, the G-THA/NAS film was successfully applied as a liquid packaging material. To sum up, we provide a feasible and effective method to prepare high-performance green packaging films.

Flexible composite phase change material with improved hydrophobicity and thermal conductivity characters for thermal management

Phase change materials (PCMs) are increasingly popularized in the field of passive thermal management. However, several inherent defects such as strong rigidity, weak hydrophobicity and poor thermal conductivity have seriously hindered their widespread development. This work introduces a novel composite PCM with thermally-induced flexibility as well as enhanced hydrophobic and thermally conductive abilities, which is synthetized by physical melting and mixing of palmitic acid (PA), olefin block copolymer (OBC) and hexagonal boron nitride (h-BN). Experimental results demonstrate that OBC helps to realize flexibility and hydrophobicity, while h-BN is essential to spurring thermal conductivity growth but incapable of impairing surface wettability. 66.5 wt% PA, 28.5 wt% OBC and 5 wt% h-BN are convinced to be the appropriate formula of composite for the hydrophobic modification and the weighing between thermal conductivity and thermal storage capacity. The as-prepared flexible PCM reverses its surface wettability from hydrophilicity to hydrophobicity, accompanied by 27.0 % increment in water contact angle compared with the case of using only PA. The resultant also presents fine physiochemical compatibility, suitable phase transition parameters, and excellent thermal stability and reliability. Furthermore, highly reliable hydrophobicity is confirmed under four harsh conditions for prolonged application.

Functional toner for office laser printer and its application for printing of paper-based superwettable patterns and devices

Laserjet printing is a kind of facile and digital do-it-yourself strategies, which is of importance to fabricate inexpensive paper-based microfluidic devices. However, the printed hydrophobic barrier is not hydrophobic enough due to the weak hydrophobicity and requires subsequent heating, which can lead to the pyrolysis of cellulose in the paper and influence the detection results. Here, for the first time, we report a kind of functional toner including toner and polydopamine (PDA) nanocapsules which contains oleic acid modified ferric tetroxide (OA-Fe3O4) and octadecylamine (ODA), which is suitable for printing with desired shapes and sizes to lead to formation of superhydrophobic barriers. Moreover, patterns printed with functional toner have good stability, including resistance to moisture, ultraviolet (UV) and bending. Finally, a proof-of-concept of metal and nitrite ions testing is demonstrated using colorimetric analysis, and the results show that the printed devices successfully perform instant detection of ions. The developed functional toner offers easy fabrication, cost-effectiveness and mass production of paper-based devices. In general, this strategy provides a new idea and technical support for the rapid prototyping of microfluidic paper-based analytical devices (μPADs) using laserjet printing.

Photoacoustic Method as a Tool for Analysis of Concentration-Dependent Thermal Effusivity in a Mixture of Methyl Alcohol and Water

It has been shown in the present paper that exploitation of the experimental potential of a photoacoustic technique can provide information on a type of intermolecular interactions in aqueous mixtures containing organic liquids, when the basic parameters of these mixtures, such as density, ρ, specific heat, cp, or thermal conductivity, λ, are unknown. Earlier investigations of concentration dependence of effusivity in different aqueous solutions of organic liquids demonstrated that the photoacoustics method is a sensitive tool to identify hydrophobic properties of such liquids. In our experiment this suggestion was exploited for a solution of methanol which is known to display much weaker hydrophobicity than other alcohols. It was confirmed that the location of extreme deviations from linearity for the thermal effusivity, Δe, agrees well with that of characteristic points for the isentropic compressibility coefficient, κS, and the excess molar volume, VEm, as a function of the concentration.

Lactic acid bacteria with a strong antioxidant function isolated from "Jiangshui," pickles, and feces.

Excessive free radicals and iron death lead to oxidative damage, which is one of the main causes of aging and diseases. In this field of antioxidation, developing new, safe, and efficient antioxidants is the main research focus. Lactic acid bacteria (LAB) are natural antioxidants with good antioxidant activity and can regulate gastrointestinal microecological balance and immunity. In this study, 15 LAB strains from fermented foods ("Jiangshui" and pickles) or feces were evaluated in terms of their antioxidant attributes. Strains with strong antioxidant capacity were preliminarily screened by the following tests: 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl radical, superoxide anion radical scavenging capacity; ferrous ion chelating assay; hydrogen peroxide tolerance capacity. Then, the adhesion of the screened strains to the intestinal tract was examined using hydrophobic and auto-aggregation tests. The safety of the strains was analyzed based on their minimum inhibitory concentration and hemolysis, and 16S rRNA was used for molecular biological identification. Antimicrobial activity tests showed them probiotic function. The cell-free supernatant of selected strains were used to explore the protective effect against oxidative damage cells. The scavenging rate of DPPH, hydroxyl radicals, and ferrous ion-chelating of 15 strains ranged from 28.81-82.75%, 6.54-68.52%, and 9.46-17.92%, respectively, the scavenging superoxide anion scavenging activity all exceeded 10%. According to all the antioxidant-related tests, strains possessing high antioxidant activities J2-4, J2-5, J2-9, YP-1, and W-4 were screened, these five strains demonstrated tolerance to 2 mM hydrogen peroxide. J2-4, J2-5, and J2-9 were Lactobacillus fermentans and γ-hemolytic (non-hemolytic). YP-1 and W-4 were Lactobacillus paracasei and α-hemolytic (grass-green hemolytic). Although L. paracasei has been proven as a safe probiotic without hemolytic characteristics, the hemolytic characteristics of YP-1 and W-4 should be further studied. Due to the weak hydrophobicity and antimicrobial activity of J2-4, finally, we selected J2-5, J2-9 for cell experiment, J2-5 and J2-9 showed an excellent ability that resistant to oxidative damage by increasing SOD, CAT, T-AOC activity of 293T cells. Therefore, J2-5, and J2-9 strains from fermented foods "Jiangshui" could be used as potential antioxidants for functional food, health care, and skincare.

Nanobubble Enhances Rutile Flotation Separation in Styrene Phosphoric Acid System

Due to the weak hydrophobicity of styrene phosphoric acid (SPA), the amount used as a collector for rutile flotation is too large, resulting in high beneficiation costs. In this study, SPA was modified by nanobubbles to enhance its hydrophobicity. In this paper, the modification of SPA by nanobubbles and the adsorption mechanism of SPA on rutile surface before and after modification were studied by means of nanoparticle tracking analysis, micro-bubble flotation test, contact angle test, zeta potential test, etc. The results show that SPA can significantly increase the concentration of bulk nanobubbles, increase the flotation recovery of rutile from 55% to 69%, and reduce the dosage of SPA from 101 mg/L to 70 mg/L. Nanobubbles interact with SPA in the form of water drainage, significantly reducing the zeta potential of the rutile surface and increasing the solid–liquid interface contact angle of rutile surface. A model of the interaction between nanobubbles, SPA, and rutile surface is established, which is helpful to understand the process mechanism of nanobubble flotation.

Chemical profiling of Ziziphi spinosae semen using on-line comprehensive two-dimensional LC-MS based on a novel phthalic anhydride bonded stationary phase.

Ziziphi spinosae semen has been widely used to treat insomnia and anxiety. To profile its chemical components, an online comprehensive two-dimensional LC-MS was developed. In this two-dimensional LC system, a novel phthalic anhydride bonded stationary phase column was combined with a C18 column. As a result, this new stationary phase exhibited remarkable differences in separation selectivity from C18, achieving a good orthogonality of 83.3%. Moreover, this new stationary phase with weaker hydrophobicity than C18 realized solvent compatibility in the online configuration. Coupled with tandem MS, 154 compounds were identified, including 51 unreported compounds. Compared with one-dimensional LC-MS, this online two-dimensional LC-MS system exhibited a much higher resolving power in isomer separation. This work provided an effective separation and characterization method for the material basis of Ziziphi spinosae semen. This strategy provides ideas for the material basis research of other traditional Chinese medicines. This article is protected by copyright. All rights reserved.

Impacts of chain and head lengths of nonionic alkyl ethoxylate surfactants on cytotoxicity to human corneal and skin cells in agri-spraying processes*

HypothesisNonionic surfactants are widely used as co-formulants in agrochemical sprays. During spraying, they may come into direct contact with humans and animals, causing irritation in different tissues. However, how the molecular structures of these surfactants affect their toxicity towards human eye and skin at the cellular level has not been well characterised. ExperimentIn this study, the cytotoxicities of two sets of nonionic surfactants (alkyl ethoxylate, CnEm) against human corneal and skin cell lines were examined, with one set composed of varied surfactant head length but fixed tail length (C12E4-23) and the other set oppositely composed (C10-16E6). The cell viability and morphology against different nonionic surfactants for varied exposure times were studied, followed by characterisation of their membrane-lytic ability. FindingNonionic surfactants with intermediate amphiphilicity killed cells rapidly due to their strong membrane-lytic power. Those with weak or strong hydrophobicity exhibited low cytotoxicity but had different modes of action depending on their hydrophobicity. Hydrophobic surfactants were found to adsorb on to cell membranes with no observed structural damage for 2 hr. Hydrophilic surfactants were also found to adsorb on to cell membranes but did cause mild structural changes. While the changes were not sufficient to elicit large cytoplasmic leakage over short periods of time, membrane associations did cause cell shrinkage which eventually resulted in cell death over longer exposure periods. These results revealed that the specific amphiphilic nature of nonionic surfactants played a crucial role in determining their cytotoxicity. This work provided a useful basis for the assessment of amphiphilicity of the nonionic surfactants used in agrochemical sprays by balancing their efficiency, toxicity and environmental impact.

Hydrophobicity regulates self-assembly behavior of binding-induced fibrillogenesis peptides

Binding-induced fibrillogenesis (BIF) peptides have a promising future in biomedicine due to the processiblity in situ in vivo, which bind to a specific trigger and in situ self-assemble into nanofibrous structures (BIF process) with excellent physical/biological functions. Alkyl chains in BIF peptides as hydrophobic tails have an important effect on self-assembly behaviors of BIF peptides. Herein, BIF peptides (trigger: Ca2+ or integrin) with different hydrophobic alkyl chains are designed to explore the influence of hydrophobicity on self-assembly behaviors of BIF peptides (Abbreviation as BIF4, BIF8, and BIF16 for 4, 8, 16 carbons of alkyl chains). It is found that BIF peptides with weak hydrophobicity (BIF4) do not form fibrous structure upon binding to Ca2+, but in nanoparticle formulation. While with strong hydrophobicity, BIF16 initially self-assemble into nanoparticles, which further bind to Ca2+ and self-assemble into nanofibers with a β-sheet conformation. As a result, when incubated with HUVECs overexpressing integrins on surfaces, BIF4 were internalized as nanoparticles without BIF process, but BIF16 performed BIF process and attached on cell surfaces. This study provides experimental evidences of the hydrophobicity effect on self-assembly behavior of BIF peptides and directs applications of BIF peptides with controllable self-assembly

Hygroscopic hydrophobic coatings from cellulose: Manipulation of the aggregation morphology of water

Fogging and icing are common phenomena in nature, but they bring huge harm in the human life and production, such as the deterioration of optical devices, the detriment of vehicles operating, the destruction of power transmission lines. In this work, we designed and constructed a cationic cellulose derivative with both weak hygroscopicity and high hydrophobicity to achieve a spontaneous management of the aggregation morphology of interfacial water, via precisely controlling the chemical structure of cellulose derivatives. As a result, the resultant cationic cellulose derivative can be used as a transparent and water-resistant coating, which exhibits universal anti-fogging, excellent anti-icing and anti-bioadhesive properties. Under low humidity, the coating can effectively absorb water to form a pseudo-film due to the ionized structure and retained hydroxyl groups. Under high humidity, the coating can promote water droplets to roll off due to the high hydrophobicity. The coating with weak hygroscopic core and high hydrophobic surface thus has a universal anti-fogging performance. In addition, this ionized coating with weak hygroscopicity can adjust the interfacial water performance, so it can reduce the freezing temperature of water to −30 ℃, and the ice adhesion stress to 10 kPa at −30 ℃. The freezing time of water exceeds 2 h at −25 ℃. Furthermore, the bacterial killing percentage on this coating is more than 97 % for Staphylococcus aureus. Due to high hydrophobicity and low surface energy, this coating has outstanding water-resistance, self-cleaning property, anti-chlorella adhesion and anti-protein adhesion. Therefore, such a multifunctional coating prepared by a simple structure design from natural cellulose has a great potential in display devices, traffics, solar products, wind generator, agricultural greenhouse, and other fields.

Banana Leaf Surface's Janus Wettability Transition from the Wenzel State to Cassie-Baxter State and the Underlying Mechanism.

Janus wettability plays an important role in certain special occasions. In this study, field emission scanning electron microscopy (FESEM) was used to observe the surface microstructure of banana leaves, the static wettability of the banana leaf surface was tested, and the dynamic response of water droplets falling at different heights and hitting on the adaxial and abaxial sides was studied. The study found that the nanopillars on the adaxial and abaxial sides of the banana leaf were different in shape. The nanopillars on the adaxial side were cone-shaped with large gaps, showing hydrophilicity (Wenzel state), and the heads of the nanopillars on the abaxial side were smooth and spherical with small gaps, showing weak hydrophobicity (Cassie–Baxter state). Banana leaves show Janus wettability, and the banana leaf surface has high adhesion properties. During the dynamic impact test, the adaxial and abaxial sides of the banana leaves showed different dynamic responses, and the wettability of the adaxial side of the banana leaves was always stronger than the abaxial side. Based on the structural parameters of nanopillars on the surface of the banana leaf and the classical wetting theory model, an ideal geometric model around a single nanopillar on both sides of the banana leaf was established. The results show that the established model has high accuracy and can reflect the experimental results effectively. When the apparent contact angle was 76.17°, and the intrinsic contact angle was 81.17° on the adaxial side of the banana leaf, steady hydrophilicity was shown. The abaxial side was similar. The underlying mechanism of Janus wettability on the banana leaf surface was elucidated. This study provides an important reference for the preparation of Janus wettability bionic surfaces and the efficient and high-quality management of banana orchards.

Pollution Flashover Characteristics of Composite Crossarm Insulator with a Large Diameter

The composite crossarm insulator differs greatly from the suspension insulator in structure and arrangement. This study aims to determine the pollution flashover characteristics of composite crossarm insulators under different voltage grades. Four types of AC composite crossarm insulators with diameters ranging from 100 mm to 450 mm are subjected to artificial pollution test, and then the effects of the surface hydrophobicity state of silicone rubber, core diameter, umbrella structure, arrangement, and insulation distance on the pollution flashover voltage of the composite crossarm insulators are analyzed. Under the pollution grade 0.2/1.0 mg/cm2 and voltage grade from 66 kV to 1000 kV, if the silicone rubber surface changes from HC5 to HC6, the pollution flashover voltage of the composite crossarm insulator will increase by 13.5% to 21.0% compared with the hydrophilic surface. If the core diameter changes from 100 mm to 300 mm, the pollution flashover voltage gradient decreases with the increase in core diameter; if the core diameter changes from 300 mm to 450 mm, the pollution flashover voltage gradient increases with core diameter. Under the same insulation height and core diameter, the umbrella structure will have a certain impact on pollution flashover voltage by up to 1.7% to 5.4%. Under the horizontal arrangement, the pollution flashover voltage can increase by 10.5% to 12.1% compared with that under the vertical arrangement. Under the hydrophilic surface and weak hydrophobicity state, the pollution flashover voltage has a linear relationship with the insulation distance. The above results can provide a reference for the structural design and optimization of the composite crossarm insulator.

Performance of rubber mortars containing silica coated rubber

This paper investigates the influence of silica coated rubber on the performance of rubber mortars. A classical Stöber sol-gel method is applied to produce a layer of silica coating on rubber particles, which is used to partially replace the fine aggregates in concrete. The effects of the surface-modified rubber particles on the flowability, mechanical strength, capillary water absorption rate, and microstructure of mortars are examined. The results show that the silica coating on the rubber particles reduces the contact angle between the rubber particles from 120° to 103° (i.e., by 17°) and changes the hydrophobic properties from strong hydrophobicity to weak hydrophobicity. The mechanical strengths of mortars are significantly improved by the incorporation of surface-modified rubber particles, i.e., from 41.60% to 44.86% (compressive strength) and from 7.80% to 26.28% (flexural strength). In addition, the incorporation of surface modified rubber particles increases the density of the mortar’s microstructure and enhances the interfaces with its surrounding pastes.