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Sample records for hydrophobically modified hydrosoluble

  1. Hydrosoluble vitamins.

    Science.gov (United States)

    Chawla, Jasvinder; Kvarnberg, David

    2014-01-01

    The hydrosoluble vitamins are a group of organic substances that are required by humans in small amounts to prevent disorders of metabolism. Significant progress has been made in our understanding of the biochemical, physiologic and nutritional aspects of the water-soluble vitamins. Deficiency of these particular vitamins, most commonly due to inadequate nutrition, can result in disorders of the nervous system. Many of these disorders have been successfully prevented in developed countries; however, they are still common in developing countries. Of the hydrosoluble vitamins, the nervous system depends the most on vitamins B and C (ascorbic acid) for proper functioning. The B group vitamins include thiamin (vitamin B1), riboflavin (vitamin B2), niacin or niacinamide (vitamin B3), pantothenic acid (vitamin B5), pyridoxine or pyridoxal (vitamin B6) and cobalamin (vitamin B12). Clinical findings depend upon the deficiency of the underlying vitamin; generally, deficiency symptoms are seen from a combination rather than an isolated vitamin deficiency. True hereditary metabolic disorders and serious deficiency-associated diseases are rare and in general limited to particular geographic regions and high-risk groups. Their recognition is truly important as that determines the appropriate therapeutic management. The general availability of vitamins to practically everyone and several national health programs have saved many lives and prevented complications. However, there has been some apprehension for several decades about how harmless generous dosages of these vitamins are. Overt overdosages can cause vitamin toxicity affecting various body systems including the nervous system. Systemically, vitamin toxicity is associated with nonspecific symptoms, such as nausea, vomiting, diarrhea, and skin rash which are common with any acute or chronic vitamin overdose. At a national level, recommended daily allowances for vitamins become policy statements. Nutrition policy has far

  2. Solution properties of hydrophobically modified

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    A.M. Al-Sabagh

    2016-12-01

    Full Text Available We tested nine hydrophobically modified polyacrylamides with molecular weights situated between 1.58 and 0.89 × 106 g/mol for enhanced oil recovery applications. Their solution properties were investigated in the distilled water, brine solution, formation water and sea water. Their critical association concentrations were determined from the relationship between their concentrations and the corresponding apparent viscosities (ηapp at 30 °C at shear rate 6 s−1. They were between 0.4 and 0.5 g/dl. The brine solutions of 0.5 g/dl of HM-PAMs were investigated at different conditions regarding their apparent viscosities. Such conditions were mono and divalent cations, temperature ranging from 30 to 90 °C, the shear rate ranging from 6 to 30 s−1 and the aging time for 45 days. The surface and interfacial tensions for the HM-PAMs were measured for concentration range from 0.01 to 1 g/dl brine solutions at 30 °C and their emulsification efficiencies were investigated for 7 days. The discrepancy in the properties and efficiencies of the tested copolymers was discussed in the light of their chemical structure.

  3. Hydrophobically modified polyelectrolytes : synthesis, properties and interactions with surfactants

    NARCIS (Netherlands)

    Nieuwkerk, A.C.

    1998-01-01

    Hydrophobically modified polyelectrolytes can form micelle-like aggregates, so-called microdomains, in aqueous solution. The hydrophobic side chains constitute the apolar inner part of these microdomains and the hydrophilic groups on the polyelectrolyte backbone are at the surface of the

  4. Liposomes coated with hydrophobically modified hydroxyethyl cellulose: Influence of hydrophobic chain length and degree of modification.

    Science.gov (United States)

    Smistad, Gro; Nyström, Bo; Zhu, Kaizheng; Grønvold, Marthe Karoline; Røv-Johnsen, Anne; Hiorth, Marianne

    2017-08-01

    Nanoparticulate systems with an uncharged hydrophilic surface may have a great potential in mucosal drug delivery. In the present study liposomes were coated with hydrophobically modified hydroxyethyl cellulose (HM-HEC) to create a sterically stabilized liposomal system with an uncharged surface. The aim was to clarify the influence of the amount of hydrophobic modification of HEC and the length of the hydrophobic moiety, on the stability of the system and on the release properties. HM-HEC with different degrees of hydrophobic modification (1 and 2mol%) and hydrophobic groups with different chain lengths (C8, C12, C16) were included in the study, as well as fluid phase and gel phase liposomes. Both types of liposomes were successfully coated with HM-HEC containing 1mol% of hydrophobic groups, while 2mol% did not work for the intended pharmaceutical applications. The polymer coated gel phase liposomes were stable (size, zeta potential, leakage) for 24 weeks at 4°C, with no differences between the C8 and C16 HM-HEC coating. For the fluid phase liposomes a size increase was observed after 24 weeks at 4°C for all formulations; the C8 HM-HEC coated liposomes increased the most. No differences in the leakage during storage at 4°C or in the release at 35°C were observed between the fluid phase formulations. To conclude; HM-HEC with a shorter hydrophobic chain length resulted in a less stable product for the fluid phase liposomes, while no influence of the chain length was observed for the gel phase liposomes (1mol% HM). Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Adsorption of Hydrophobically Modified Polyelectrolytes on Hydrophobic Substrates Adsorption de polyélectrolytes modifiés hydrophobiquement sur les substrats hydrophobes

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    Mays J. W.

    2006-12-01

    Full Text Available A series of diblock copolymers, poly (tert-butyl styrene-sodium poly (styrene sulfonate with different molecular weight and percentage of sulfonation have been used to study the effect of polymer structure on its adsorption behavior onto hydrophobically modified silicon wafers. The percentage of the hydrophobic block varies from 3. 6-8. 9%. Previous studies show that salt concentration is very important for the adsorption of such polyelectrolytes onto silica surfaces. Octadecyltriethoxysilane (OTE has been used to modify the silicon wafer which changes the water contact angle from 50° on unmodified silica to 100° to 120°. On this hydrophobic surface, we found that the adsorption of these slightly hydrophobically modified polyelectrolytes is close to the 4/23rd power of salt concentration predicted by a recent model. The grafting density is also consistent with a dependence on the length of the hydrophobic block to the -12/23rd power, and the length of the polyelectrolyte block to the -6/23rd power, predicted by this model. Une série de copolymères à diblocs poly (tert-butyle styrène-sodium (sulfonate de polystyrène de masses moléculaires et pourcentages de sulfonation différents ont été utilisés pour étudier les effets de la structure du polymère sur son pouvoir d'adsorption sur des surfaces de silicium modifiées hydrophobiquement. Le pourcentage du bloc hydrophobe varie de 3,6 à 8,9%. Les études antérieures montrent que la concentration saline est très importante pour l'adsorption de ces polyélectrolytes sur les surfaces de silice. Nous avons utilisé l'octadecyltriéthoxysilane (OTE pour modifier la surface de silicium qui change l'angle de contact de l'eau de 50° sur la silice non modifiée à une valeur comprise entre 100° et 120° sur la silice modifiée. Sur cette surface hydrophobe, nous constatons que l'adsorption de ces polyélectrolytes légèrement modifiés hydrophobiquement est proche de la loi puissance 4

  6. Synthesis and characterization of hydrophobically modified polymeric betaines

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    Alexey Shakhvorostov

    2015-09-01

    Full Text Available Polymeric betaines containing long alkyl chains C12H25, C14H29, C16H33 and C18H37 were synthesized by Michael addition reaction of alkylaminocrotonates and methacrylic acid (MAA. They were characterized by FTIR, 13C NMR, DSC, DLS, GPC, cryo-TEM, viscometry and zeta-potential measurements. The polymers were fully soluble in DMF, THF and DMSO, partially dissolved in aromatic hydrocarbons (benzene, toluene, o-xylene and formed colloid solutions in aqueous KOH. In aqueous KOH and DMSO solutions, hydrophobically modified polymeric betaines behaved as polyelectrolytes. The average hydrodynamic size and zeta potential of diluted aqueous solutions of hydrophobic polybetainess containing dodecyl-, tetradecyl-, hexadecyl-, and octadecyl groups were studied as a function of pH. Anomalous low values of the isoelectric point (IEP of amphoteric macromolecules were found to be in the range of pH 2.7-3.4. According to DLS data, the average size of macromolecules tends to decrease with dilution. Zeta-potential of amphoteric macromolecules in aqueous solution is much higher than that in DMSO. The cryo-TEM results revealed that in both aqueous KOH and DMSO media, the micron- and nanosized vesicles existed. The structural organization of vesicles in water and DMSO is discussed. The wax inhibition effect of hydrophobic polybetaines at a decrease of the pour point temperatures of high paraffinic oils was better in comparison with commercial available ethylene-vinylacetate copolymers (EVA.

  7. Hydrophobicity of electron beam modified surface of hydroxyapatite films

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    Gregor, M., E-mail: gregor@fmph.uniba.sk [Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, 84248 Bratislava (Slovakia); Plecenik, T. [Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, 84248 Bratislava (Slovakia); Tofail, S.A.M. [Materials & Surface Science Institute, University of Limerick, Limerick (Ireland); Zahoran, M.; Truchly, M. [Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, 84248 Bratislava (Slovakia); Vargova, M. [Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University, 84215 Bratislava (Slovakia); Laffir, F. [Materials & Surface Science Institute, University of Limerick, Limerick (Ireland); Plesch, G. [Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University, 84215 Bratislava (Slovakia); Kus, P.; Plecenik, A. [Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, 84248 Bratislava (Slovakia)

    2015-05-15

    Highlights: • Surface potential of hydroxyapatite films were modified by focused electron beam. • Micron-sized domains of modified surface potential were created. • Wettability and surface free energy of the irradiated areas was studied. • Possible mechanisms of increased surface hydrophobicity are discussed. - Abstract: Arrays of micron-sized domains of modified surface potential were created on hydroxyapatite films by mid-energy (20 keV) electron beam irradiation available in a laboratory scanning electron microscope. The dosage of electron beam was varied between 10{sup −3} and 10{sup 3} μC/cm{sup 2} to inject charge into the film surface. Contrary to the conventional electrowetting theory, the dosage of injected charge used in creating such microdomains caused a gradual increase of the water contact angle from 57° to 93° due to the elimination of the polar component of the surface free energy. Surface contamination by carbonaceous species can be held only partially responsible for such behavior at lower dosage of electron beam. A transfer of free surface charge to water and an electron beam induced disruption of polar orientation of OH ions have been attributed to be influencial factors in the overall dewetting behavior.

  8. Rheological Properties in Aqueous Solution for Hydrophobically Modified Polyacrylamides Prepared in Inverse Emulsion Polymerization

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    Shirley Carro

    2017-01-01

    Full Text Available Inverse emulsion polymerization technique was employed to synthesize hydrophobically modified polyacrylamide polymers with hydrophobe contents near to feed composition. Three different structures were obtained: multisticker, telechelic, and combined. N-Dimethyl-acrylamide (DMAM, n-dodecylacrylamide (DAM, and n-hexadecylacrylamide (HDAM were used as hydrophobic comonomers. The effect of the hydrophobe length of comonomer, the initial monomer, and surfactant concentrations on shear viscosity was studied. Results show that the molecular weight of copolymer increases with initial monomer concentration and by increasing emulsifier concentration it remained almost constant. Shear viscosity measurements results show that the length of the hydrophobic comonomer augments the hydrophobic interactions causing an increase in viscosity and that the polymer thickening ability is higher for combined polymers.

  9. Chemical treatment of the intra-canal dentin surface: a new approach to modify dentin hydrophobicity

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    Cesar GAITAN-FONSECA

    2013-01-01

    Full Text Available Objective This study evaluated the hydrophobicity of dentin surfaces that were modified through chemical silanization with octadecyltrichlorosilane (OTS. Material and Methods An in vitro experimental study was performed using 40 human permanent incisors that were divided into the following two groups: non-silanized and silanized. The specimens were pretreated and chemically modified with OTS. After the chemical modification, the dentin hydrophobicity was examined using a water contact angle measurement (WCA. The effectiveness of the modification of hydrophobicity was verified by the fluid permeability test (FPT. Results and Conclusions Statistically significant differences were found in the values of WCA and FPT between the two groups. After silanization, the hydrophobic intraradicular dentin surface exhibited in vitro properties that limit fluid penetration into the sealed root canal. This chemical treatment is a new approach for improving the sealing of the root canal system.

  10. The new method of modifying the hydrophobic properties of expanded perlite

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    Vogt Elżbieta

    2017-01-01

    Full Text Available The progressive industrialization and development of the automotive industry is the cause of the increasing demand for chemical products, especially oil products. Unfortunately, during processing, transportation or storage of these products, they get very often into the environment causing pollution. The removal of the results of accidents is still a current problem. The techniques which employ various types of sorbents deserve special attention among the several methods of eliminating the effects of pollutions. Moreover, expanded hydrophobic perlite is an interesting material among sorbents which are used on a large scale. The new method of modifying the hydrophobic properties of expanded perlite, with the use of solutions of stearic acid in organic solvents, was presented. The perlite that was used in research was produced by the PerliPol registered partnership in Bełchatów. Hydrophobic properties of the obtained materials were determined on the basis of the results achieved due to the modified film flotation method, “floating on water” test and on the basis of the value of water retention for individual samples. All grain fractions of perlite obtained hydrophobic properties which were better than or comparable to the hydrophobic properties of the HydroPerl (PerlPol commercial material used to remove petroleum product pollution. The hydrophobization process significantly improved the adsorption capacity of modified perlite to petroleum product pollution.

  11. In vitro evaluation of tissue adhesives composed of hydrophobically modified gelatins and disuccinimidyl tartrate

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    Miyuki Matsuda

    2012-01-01

    Full Text Available The effect of the hydrophobic group content in gelatin on the bonding strength of novel tissue–penetrating tissue adhesives was evaluated. The hydrophobic groups introduced into gelatin were the saturated hexanoyl, palmitoyl, and stearoyl groups, and the unsaturated oleoyl group. A collagen casing was employed as an adherend to model soft tissue for the in vitro determination of bonding strength of tissue adhesives composed of various hydrophobically modified gelatins and disuccinimidyl tartrate. The adhesive composed of stearoyl-modified gelatin (7.4% stearoyl; 10Ste and disuccinimidyl tartrate showed the highest bonding strength. The bonding strength of the adhesives decreased as the degree of substitution of the hydrophobic groups increased. Cell culture experiments demonstrated that fluorescein isothiocyanate-labeled 10Ste was integrated onto the surface of smooth muscle cells and showed no cytotoxicity. These results suggest that 10Ste interacted with the hydrophobic domains of collagen casings, such as hydrophobic amino acid residues and cell membranes. Therefore, 10Ste–disuccinimidyl tartrate is a promising adhesive for use in aortic dissection.

  12. The modified nanocrystalline cellulose for hydrophobic drug delivery

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    Qing, Weixia [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004 (China); Medical College, Henan University, Kaifeng 475004 (China); Wang, Yong [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004 (China); Wang, Youyou [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004 (China); Key Lab of Natural Medicine and Immun-engineering of Henan Province, Henan University, Kaifeng 475004 (China); Zhao, Dongbao [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004 (China); Liu, Xiuhua, E-mail: ll514527@163.com [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004 (China); Key Lab of Natural Medicine and Immun-engineering of Henan Province, Henan University, Kaifeng 475004 (China); Zhu, Jinhua [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004 (China)

    2016-03-15

    Graphical abstract: - Highlights: • Torispherical NCC was synthesized through the improvements on the hydrolysis method. • NCC was firstly modified with CTMAB as a drug carrier. • Luteolin and luteoloside loading CTMAB-coated NCC were studied. - Abstract: In this work, torispherical nanocrystalline cellulose (NCC) was synthesized, and firstly modified with a cationic surfactant cetyltrimethylammonium bromide (CTMAB). It was proved that the kinetics of NCC adsorbing CTMAB followed the pseudo-second-order kinetics equation, and the adsorption isotherm model followed Freundlich which was multi molecular layer adsorption model. The morphology and structure of NCC and CTMAB-coated NCC were characterized by transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). Stabilities of NCC and CTMAB-coated NCC were assayed by zeta potential. The results showed that NCC in CTMAB solution was well-dispersed and stable. Moreover, the drug loading and release performance of CTMAB-coated NCC were studied using luteolin (LUT) and luteoloside (LUS) as model drugs.

  13. The modified nanocrystalline cellulose for hydrophobic drug delivery

    International Nuclear Information System (INIS)

    Qing, Weixia; Wang, Yong; Wang, Youyou; Zhao, Dongbao; Liu, Xiuhua; Zhu, Jinhua

    2016-01-01

    Graphical abstract: - Highlights: • Torispherical NCC was synthesized through the improvements on the hydrolysis method. • NCC was firstly modified with CTMAB as a drug carrier. • Luteolin and luteoloside loading CTMAB-coated NCC were studied. - Abstract: In this work, torispherical nanocrystalline cellulose (NCC) was synthesized, and firstly modified with a cationic surfactant cetyltrimethylammonium bromide (CTMAB). It was proved that the kinetics of NCC adsorbing CTMAB followed the pseudo-second-order kinetics equation, and the adsorption isotherm model followed Freundlich which was multi molecular layer adsorption model. The morphology and structure of NCC and CTMAB-coated NCC were characterized by transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). Stabilities of NCC and CTMAB-coated NCC were assayed by zeta potential. The results showed that NCC in CTMAB solution was well-dispersed and stable. Moreover, the drug loading and release performance of CTMAB-coated NCC were studied using luteolin (LUT) and luteoloside (LUS) as model drugs.

  14. Hydrophobically modified chitosan/gold nanoparticles for DNA delivery

    International Nuclear Information System (INIS)

    Bhattarai, Shanta Raj; Remant Bahadur, K.C.; Aryal, Santosh; Bhattarai, Narayan; Kim, Sun Young; Yi, Ho Keun; Hwang, Pyoung Han; Kim, Hak Yong

    2008-01-01

    Present study dealt an application of modified chitosan gold nanoparticles (Nac-6-Au) for the immobilization of necked plasmid DNA. Gold nanoparticles stabilized with N-acylated chitosan were prepared by graft-onto approach. The stabilized gold nanoparticles were characterized by different physico-chemical techniques such as UV-vis, TEM, ELS and DLS. MTT assay was used for in vitro cytotoxicity of the nanoparticles into three different cell lines (NIH 3T3, CT-26 and MCF-7). The formulation of plasmid DNA with the nanoparticles corresponds to the complex forming capacity and in-vitro/in-vivo transfection efficiency was studied via gel electrophoresis and transfection methods, respectively. Results showed the modified chitosan gold nanoparticles were well-dispersed and spherical in shape with average size around 10∼12 nm in triple distilled water at pH 7.4, and showed relatively no cytotoxicity at low concentration. Addition of plasmid DNA on the aqueous solution of the nanoparticles markedly reduced surface potential (50.0∼66.6%) as well as resulted in a 13.33% increase in hydrodynamic diameters of the formulated nanoparticles. Transfection efficiency of Nac-6-Au/DNA was dependent on cell type, and higher β-galactosidase activity was observed on MCF-7 breast cancer cell. Typically, this activity was 5 times higher in 4.5 mg/ml nanoparticles concentration than that achieved by the nanoparticles of other concentrations (and/or control). However, this activity was lower in in-vitro and dramatically higher in in-vivo than that of commercially available transfection kit (Lipofectin (registered) ) and DNA. From these results, it can be expected to develop alternative new vectors for gene delivery

  15. SYNTHESIS AND CATALYTIC PROPERTIES OF HYDROPHOBICALLY-MODIFIED POLY(ALKYLMETHYLDIALLYLAMMONIUM CHLORIDES)

    NARCIS (Netherlands)

    Wang, G.J; Engberts, J.B.F.N.

    Novel non-cross-linked and cross-linked, hydrophobically modified homo- and copolymers were synthesized by free-radical cyclo(co)polymerization of alkylmethyldiallylammonium chloride monomers in aqueous solution using ammonium persulfate as the initiator. Cross-linking was brought about by addition

  16. Hydrophobically Modified Sulfonated Polyacrylamides for IOR: Correlations between Associative Behavior and Injectivity in the Diluted Regime Polyacrylamides sulfonés modifiés hydrophobes pour la RAH (IOR : corrélations entre le caractère associatif et l’injectivité en régime dilué

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    Dupuis G.

    2013-01-01

    Full Text Available We report new experimental correlations between the injectivity through polycarbonate membranes and associative properties of random Hydrophobically Modified Water Soluble Polymers (HMWSP with sulfonated polyacrylamides (SPAM backbones and variable compositions in hydrophobic units. The investigations are focused on both their associative behavior in the diluted and semi-diluted regime and their injectivity under frontal filtration conditions in the diluted regime. Results from viscosimetric and dynamic light scattering measurements indicate the existence of thresholds in terms of amount (≥ 0.5 mol% and mass (≥ C12 of alkyl hydrophobic units above which interchain interactions arise. These interactions are evidenced by the presence of multichain aggregates in diluted solutions and by enhanced thickening abilities in semi- diluted solutions. The filtration study was performed with capillary pore membranes (track-etched in the Darcy regime under constant -flow rate and high Jamming Ratio conditions. Results show that: injection of diluted solutions of HMWSP without interchaininteractions (i.e. with composition in hydrophobic units belowthe above mentioned thresholds does not lead to significantmobility and permeability reductions as compared to theinjection of a reference Water Soluble Polymer (WSP; injection of diluted solutions of HMWSP with interchain interactions leads to significant mobility and permeability reductions; HMWSP-induced mobility and permeability reductions are essentially due to irreversible polymer adsorption on the pore walls and not to the formation of filter-cakes; HMWSP adsorbed layers thicknesses are limited by the effective stress applied by the solution’s flow in the pores. Nous présentons de nouvelles corrélations expérimentales entre l’injectivité dans des membranes de polycarbonate et le caractère associatif de Polymères Hydrosolubles Modifiés Hydrophobes (PHMH ayant des squelettes de polyacrylamide

  17. Surface modification to produce hydrophobic nano-silica particles using sodium dodecyl sulfate as a modifier

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    Qiao, Bing; Liang, Yong; Wang, Ting-Jie, E-mail: wangtj@tsinghua.edu.cn; Jiang, Yanping

    2016-02-28

    Graphical abstract: Nano silica particle was modified to produce hydrophobic surface with contact angle of 107° using the water soluble SDS as a modifier through a new route. The grafted density reached 1.82–2 nm. Brønsted acid sites supply proton to react with SDS via generating carbocation, forming a Si–O–C structure. - Highlights: • Silica was modified to produce hydrophobic surface using SDS as modifier. • The route is free of organic solvent and gets perfect contact of SDS and silica. • Contact angle of modified silica particles reached 107°. • Grafted density on the silica surface reached 1.82 SDS nm{sup −2}. • Brønsted acid sites supply proton to react with SDS via generating carbocation. - Abstract: Hydrophobic silica particles were prepared using the surfactant sodium dodecyl sulfate (SDS) as a modifier by a new route comprising three processes, namely, aqueous mixing, spray drying and thermal treatment. Since SDS dissolves in water, this route is free of an organic solvent and gave a perfect dispersion of SDS, that is, there was excellent contact between SDS and silica particles in the modification reaction. The hydrophobicity of the modified surface was verified by the contact angle of the nano-sized silica particles, which was 107°. The SDS grafting density reached 1.82 nm{sup −2}, which is near the highest value in the literature. The optimal parameters of the SDS/SiO{sub 2} ratio in the aqueous phase, process temperature and time of thermal treatment were determined to be 20%, 200 °C and 30 min, respectively. The grafting mechanism was studied by comparing the modification with that on same sized TiO{sub 2} particles, which indicated that the protons of the Brønsted acid sites on the surface of SiO{sub 2} reacted with SDS to give a carbocation which then formed a Si–O–C structure. This work showed that the hydrophilic surface of silica can be modified to be a hydrophobic surface by using a water soluble modifier SDS in a

  18. Effect of nano silica based modifying agent for hydrophobic coating application

    International Nuclear Information System (INIS)

    Nurul Huda Mudri; Nik Ghazali Nik Salleh; Mek Zah Salleh

    2016-01-01

    Hydrophobic coatings find wide application in industry due to their unique features such as water repellent and self-cleaning properties. In this study, modifying agent was synthesized by way of nano silica particles dispersion in polydimethyl siloxane with addition of surfactant, catalyst and stabilizer using high speed distemper. The modifying agent was added into coating formulation and cured under UV exposure. Scanning Electron Microscopy image of the film found that the nano silica particles were distributed well on substrate. Contact angle measurement gave the highest reading of 116 degree for 20 % wt of the modifying agent. The optical properties of the film were evaluated via transmission and haze test. (author)

  19. Fabrication of superhydrophobic sol-gel composite films using hydrophobically modified colloidal zinc hydroxide.

    Science.gov (United States)

    Lakshmi, R V; Basu, Bharathibai J

    2009-11-15

    A superhydrophobic sol-gel composite film was fabricated by incorporating hydrophobically modified colloidal zinc hydroxide (CZH) in sol-gel matrix. CZH was prepared by controlled precipitation and modified by treatment with stearic acid. The concentration of stearic acid and stirring time were optimized to obtain modified CZH with very high water contact angle (WCA) of 165 degrees and sliding angle (SA)superhydrophobic surfaces. FTIR spectrum also confirmed the presence of zinc stearate in the composite film. The method is simple and cost-effective and does not involve any expensive chemicals or equipments.

  20. Properties of POPC/POPE supported lipid bilayers modified with hydrophobic quantum dots on polyelectrolyte cushions.

    Science.gov (United States)

    Kolasinska-Sojka, Marta; Wlodek, Magdalena; Szuwarzynski, Michal; Kereiche, Sami; Kovacik, Lubomir; Warszynski, Piotr

    2017-10-01

    The formation and properties of supported lipid bilayers (SLB) containing hydrophobic nanoparticles (NP) was studied in relation to underlying cushion obtained from selected polyelectrolyte multilayers. Lipid vesicles were formed from zwitterionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and negatively charged 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) in phosphate buffer (PBS). As hydrophobic nanoparticles - quantum dots (QD) with size of 3.8nm (emission wavelength of 420nm) were used. Polyelectrolyte multilayers (PEM) were constructed by the sequential, i.e., layer-by-layer (LbL) adsorption of alternately charged polyelectrolytes from their solutions. Liposomes and Liposome-QDs complexes were studied with Transmission Cryo-Electron Microscopy (Cryo-TEM) to verify the quality of vesicles and the position of QD within lipid bilayer. Deposition of liposomes and liposomes with quantum dots on polyelectrolyte films was studied in situ using quartz crystal microbalance with dissipation (QCM-D) technique. The fluorescence emission spectra were analyzed for both: suspension of liposomes with nanoparticles and for supported lipid bilayers containing QD on PEM. It was demonstrated that quantum dots are located in the hydrophobic part of lipid bilayer. Moreover, we proved that such QD-modified liposomes formed supported lipid bilayers and their final structure depended on the type of underlying cushion. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Protection of oxidative hair color fading from shampoo washing by hydrophobically modified cationic polymers.

    Science.gov (United States)

    Zhou, Y; Foltis, L; Moore, D J; Rigoletto, R

    2009-01-01

    The fading of oxidative color in hair as a result of daily shampoo washing activities has become a common problem and a source of frequent complaints by consumers. The fading occurs primarily through hair dye solubility in water. One aspect of the current study investigates the physical and chemical factors that influence hair color fading during the washing process. This is accomplished by testing hair dye dissolution in water from dyed hair samples with variation of surfactant type, pH, and hair type. Furthermore, a new approach to preventing color fading is developed aiming to provide an effective barrier function for hair dye from dissolving into water. The preliminary investigation of a series of polymers with various functional groups indicates that polymers with hydrophobically modified and cationic functionalities are most effective in preventing hair dye dissolution in water. It is also evident that a synergistic effect of the polymer's hydrophobic moieties and cationic charges are important on hair color protection during shampoo washing processes. A primary example of a polymer within this category is a cationic terpolymer of vinylpyrrolidone, dimethylaminopropyl methacrylamide, and methacryloylaminopropyl lauryldimonium chloride (INCI: Polyquaternium-55). The color protection benefit of this polymer is evaluated using newly developed methodologies for evaluating hair color changes, such as hair color fading tests through multiple shampoo washes with mannequin heads and hair tresses, both derived from human hair, colorimetry, and quantitative digital image analysis. In addition, new infrared spectroscopic imaging techniques are used to detect the hair dye deposition behavior inside hair fibers both with and without the color protection treatment. Both visual and instrumental measurement results indicate that Polyquaternium-55 provides a high level of color protection when formulated in a hair color protection regimen with up to 50% color protection. This

  2. Differences between tethered polyelectrolyte chains adsorbed onto bare mica and hydrophobically modified mica, comparison with theory.

    Science.gov (United States)

    Balastre, Marc; Tamashiro, Mario N.; Hernandez, Ernesto; Pincus, Philip; Tirrell, Matthew

    2001-03-01

    End-grafted polymers generated from the adsorption of asymmetric diblock copolymers on solid surface play an important role in many areas of science and technology. While the small insoluble block acts as an anchor, the charged soluble block confers useful properties to the surface. This study looks at tethered layers of poly(styrene sulfonate)/poly(t-butyl styrene) (PtBS-PSS) adsorbed on both mica (hydrophilic) and octadecyltriethoxysilane (OTE) modified mica (hydrophobic). Normal compressing forces at two different constant grafting densities (bare and modified mica) were measured with the surface force apparatus and compared with theoretical prediction. The effect of salt concentration (Cs) upon the thickness of the self-assembled layers (Lo) was measured in each case. For adsorption of diblock copolymers onto OTE the resulting scaling relationship is much closer to the brush theory, Lo Cs-1/3. This result suggests that the adsorbed amount on mica is not high enough to form a brush.

  3. Hydrophobically modified inulin as an amphiphilic carbohydrate polymer for micellar delivery of paclitaxel for intravenous route.

    Science.gov (United States)

    Muley, Pratik; Kumar, Sunny; El Kourati, Fadoua; Kesharwani, Siddharth S; Tummala, Hemachand

    2016-03-16

    Micellization offers several advantages for the delivery of water insoluble drugs including a nanoparticulate 'core-shell' delivery system for drug targeting. Recently, hydrophobically modified polysaccharides (HMPs) are gaining recognition as micelle forming polymers to encapsulate hydrophobic drugs. In this manuscript, for the first time, we have evaluated the self-assembling properties of a lauryl carbamate derivative of the poly-fructose natural polymer inulin (Inutec SP1(®) (INT)) to form paclitaxel (PTX) loaded micelles. INT self-assembled into well-defined micellar structures in aqueous environment with a low critical micellar concentration of 27.8 μg/ml. INT micelles exhibited excellent hemocompatibility and low toxicity to cultured cells. PTX loaded INT micelles exhibited a mean size of 256.37 ± 10.45 nm with excellent drug encapsulation efficiency (95.66 ± 2.25%) and loading (8.69 ± 0.22%). PTX loaded micelles also displayed sustained release of PTX and enhanced anti-cancer efficacy in-vitro in mouse melanoma cells (B16F10) compared to Taxol formulation with Cremophor EL as solvent. In addition, PTX loaded INT micelles exhibited comparable in-vivo antitumor activity in B16F10 allograft mouse model at half the dose of Taxol. In conclusion, INT offers safe, inexpensive and natural alternative to widely used PEG-modified polymers for the formulation of micellar delivery systems for paclitaxel. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Synthesis, characterisation and physicochemical properties of hydrophobically modified inulin using long-chain fatty acyl chlorides.

    Science.gov (United States)

    Han, Lingyu; Ratcliffe, I; Williams, P A

    2017-12-15

    A series of inulin derivatives were synthesized in aqueous solution using acyl chlorides with varying alkyl chain length (C10-C16). They were characterised using a number of techniques including MALDI TOF-MS, 1 H NMR and FTIR and their degree of substitution determined. The solution properties of the hydrophobically modified inulins were investigated using dye solubilisation and surface tension and it was confirmed that the molecules aggregated in solution above a critical concentration (critical aggregation concentration, CAC). The value of the CAC was found to be reasonably consistent between the different techniques and was shown to decrease with increasing hydrophobe chain length. It was found that the C10, C12 and C14 derivatives formed stable oil-in-water emulsions and the emulsion droplet size decreased with increasing alkyl chain length. The C16 derivative was not able to produce stable oil-in-water emulsions; however, it was able to form stable water-in-oil emulsions. The fact that the derivatives are able to form micellar-like aggregates and stabilise emulsions makes them suitable candidates for the encapsulation and delivery of active compounds with potential application in food, cosmetic, personal care and pharmaceutical formulations. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Hydrophobically Modified siRNAs Silence Huntingtin mRNA in Primary Neurons and Mouse Brain

    Directory of Open Access Journals (Sweden)

    Julia F Alterman

    2015-01-01

    Full Text Available Applications of RNA interference for neuroscience research have been limited by a lack of simple and efficient methods to deliver oligonucleotides to primary neurons in culture and to the brain. Here, we show that primary neurons rapidly internalize hydrophobically modified siRNAs (hsiRNAs added directly to the culture medium without lipid formulation. We identify functional hsiRNAs targeting the mRNA of huntingtin, the mutation of which is responsible for Huntington's disease, and show that direct uptake in neurons induces potent and specific silencing in vitro. Moreover, a single injection of unformulated hsiRNA into mouse brain silences Htt mRNA with minimal neuronal toxicity. Thus, hsiRNAs embody a class of therapeutic oligonucleotides that enable simple and straightforward functional studies of genes involved in neuronal biology and neurodegenerative disorders in a native biological context.

  6. Development of Cy5.5-Labeled Hydrophobically Modified Glycol Chitosan Nanoparticles for Protein Delivery

    Science.gov (United States)

    Chin, Amanda

    Therapeutic proteins are often highly susceptible to enzymatic degradation, thus restricting their in vivo stability. To overcome this limitation, delivery systems designed to promote uptake and reduce degradation kinetics have undergone a rapid shift from macro-scale systems to nanomaterial based carriers. Many of these nanomaterials, however, elicit immune responses and may have cytotoxic effects both in vitro and in vivo. The naturally derived polysaccharide chitosan has emerged as a promising biodegradable material and has been utilized for many biomedical applications; nevertheless, its function is often constrained by poor solubility. Glycol chitosan, a derivative of chitosan, can be hydrophobically modified to impart amphiphilic properties that enable the self-assembly into nanoparticles in aqueous media at neutral pH. This nanoparticle system has shown initial success as a therapeutic agent in several model cell culture systems, but little is known about its stability against enzymatic degradation. Therefore, the goal of this research was to investigate the resistance of hydrophobically modified glycol chitosan against enzyme-catalyzed degradation using an in vivo simulated system containing lysozyme. To synthesize the nanoparticles, hydrophobic cholanic acid was first covalently conjugated to glycol chitosan using of N-(3-Dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). Conjugates were purified by dialysis, lyophilized, and ultra-sonicated to form nanoparticles. Fourier transform infrared (FT-IR) spectroscopy confirmed the binding of 5beta-cholanic acid to the glycol chitosan. Particle size and stability over time were determined with dynamic light scattering (DLS), and particle morphology was evaluated by transmission electron microscopy (TEM). The average diameter of the nanoparticles was approximately 200 nm, which remained stable at 4°C for up to 10 days. Additionally, a near infrared fluorescent (NIRF) dye

  7. Progesterone binding nano-carriers based on hydrophobically modified hyperbranched polyglycerols

    Science.gov (United States)

    Alizadeh Noghani, M.; Brooks, D. E.

    2016-02-01

    Progesterone (Pro) is a potent neurosteroid and promotes recovery from moderate Traumatic Brain Injury but its clinical application is severely impeded by its poor water solubility. Here we demonstrate that reversibly binding Pro within hydrophobically modified hyperbranched polyglycerol (HPG-Cn-MPEG) enhances its solubility, stability and bioavailability. Synthesis, characterization and Pro loading into HPG-Cn-MPEG is described. The release kinetics are correlated with structural properties and the results of Differential Scanning Calorimetry studies of a family of HPG-Cn-MPEGs of varying molecular weight and alkylation. While the maximum amount of Pro bound correlates well with the amount of alkyl carbon per molecule contributing to its hydrophobicity, the dominant first order rate constant for Pro release correlates strongly with the amount of structured or bound water in the dendritic domain of the polymer. The results provide evidence to justify more detailed studies of interactions with biological systems, both single cells and in animal models.Progesterone (Pro) is a potent neurosteroid and promotes recovery from moderate Traumatic Brain Injury but its clinical application is severely impeded by its poor water solubility. Here we demonstrate that reversibly binding Pro within hydrophobically modified hyperbranched polyglycerol (HPG-Cn-MPEG) enhances its solubility, stability and bioavailability. Synthesis, characterization and Pro loading into HPG-Cn-MPEG is described. The release kinetics are correlated with structural properties and the results of Differential Scanning Calorimetry studies of a family of HPG-Cn-MPEGs of varying molecular weight and alkylation. While the maximum amount of Pro bound correlates well with the amount of alkyl carbon per molecule contributing to its hydrophobicity, the dominant first order rate constant for Pro release correlates strongly with the amount of structured or bound water in the dendritic domain of the polymer. The

  8. Effect of hydrophobic groups on the adsorption conformation of modified polycarboxylate superplasticizer investigated by molecular dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Hongxia [State Key Laboratory of High Performance Civil Engineering Materials, Nanjing 210008, Jiangsu (China); Jiangsu Sobute New Materials Co. Ltd., Nanjing 211103, Jiangsu (China); Wang, Yanwei, E-mail: wangyanwei@cnjsjk.cn [State Key Laboratory of High Performance Civil Engineering Materials, Nanjing 210008, Jiangsu (China); Jiangsu Sobute New Materials Co. Ltd., Nanjing 211103, Jiangsu (China); Yang, Yong; Shu, Xin; Yan, Han [State Key Laboratory of High Performance Civil Engineering Materials, Nanjing 210008, Jiangsu (China); Jiangsu Sobute New Materials Co. Ltd., Nanjing 211103, Jiangsu (China); Ran, Qianping, E-mail: qpran@cnjsjk.cn [State Key Laboratory of High Performance Civil Engineering Materials, Nanjing 210008, Jiangsu (China); Jiangsu Sobute New Materials Co. Ltd., Nanjing 211103, Jiangsu (China)

    2017-06-15

    Highlights: • Adsorption conformation of comb-like PCE was studied by all-atom MD simulations. • A comparison is made between vacuum-based and solution-based simulations. • Effects of hydrophobic modifications on adsorption properties are elucidated. - Abstract: All-atom molecular dynamics (MD) simulations were used to study the adsorption conformations of hydrophobically-modified comb-shaped polycarboxylate ether-based (PCE) superplasticizer molecules on a model surface of dicalcium silicate (C{sub 2}S) in vacuum and in an explicit solution, respectively. Three different hydrophobic modifying groups, namely, the ethyl group, the n-butyl group and the phenyl group, decorated to the backbone, were examined. Comparing the hydrophobically-modified PCEs to the unmodified one, differences were found in the binding energy, the adsorption conformation and the water density at the interface. The interaction between PCE molecules and C{sub 2}S was weakened in a solution with explicit solvents than that obtained from vacuum-based simulations. The presence of hydrophobic groups lowered the polymer-surface binding energy, decreased the radius of gyration (Rg) of the adsorbed polymer, increased the peak position in the heavy-atom density profiles in the direction perpendicular to the surface, and also caused the adsorbed conformations to be more globular in shape. The parallel and perpendicular components (relative to the surface plane) of the geometric sizes of the adsorbed polymers were calculated, and the results showed that the presence of hydrophobically modifying groups decreased the in-plane radius while increased the adsorption layer thickness compared to the unmodified control. The presence of PCEs perturbed the dense water layer above the C{sub 2}S surface and lowered the water density. Perturbations to the interfacial water density were found to correlate nicely with the adsorbed conformations of PCEs.

  9. Synthesis and characterization of high molecular weight hydrophobically modified polyacrylamide nanolatexes using novel nonionic polymerizable surfactants

    Directory of Open Access Journals (Sweden)

    A.M. Al-Sabagh

    2013-12-01

    Full Text Available In this article, nine hydrophobically modified polyacrylamides (HM-PAM nanolatexes, were synthesized by copolymerizing the acrylamide monomer and novel polymerizable surfactants (surfmers. The reaction was carried out by inverse microemulsion copolymerization technique. The copolymerization was initiated by redox initiators composed of potassium peroxodisulphate and sodium bisulfite. The emulsion was stabilized using mixed tween 85 and span 80 as nonionic emulsifiers. The prepared HM-PAMs were classified into three groups according to the surfmers used in the copolymerization. The chemical structures of the prepared HM-PAMs were confirmed by FT-IR, 1H NMR and 13C NMR. The thermal properties were estimated with the thermal gravimetric analysis (TGA. The size and morphology of the prepared latexes were investigated by the dynamic light scattering (DLS and the High Resolution Transmission Electron Microscope (HRTEM. Finally, the molecular weights of the prepared copolymers were determined by the GPC and the viscosity average molecular weight method. They were situated between 1.58 × 106 and 0.89 × 106.

  10. Feeding calves with hydrosoluble soybean extract. I. Performance and digestibility

    Directory of Open Access Journals (Sweden)

    Sergio Novita Esteves

    1995-06-01

    Full Text Available The aim of this investigation was to study the total replacement of powder milk protein (SL for hydrosoluble soybean extract (EHS in feeding 5-day-old Holstein male calves. The experiment was carried out using 3 treatment throughout the period of milk intake (5 to 90 days of life. In treatment I, SL was supplied from the 5th to 90th day of life. In treatment II, SL was supplied until the 29th day, and, from the 30th to 90th day, EHS was supplied. In treatment III, EHS was supplied from the 5th day of life. After this period the calves were weaned and received the same hay and concentrate feed as in the milk intake period, up to 180 days. During the milk intake period, the animals of treatment II, showed in average lower food intake, decreased daily weight gain and poorer digestibility of nutrients than animals from treatment I (P<0.05. In the post-weaning period food intake and average daily gain were similar. Calves of treatment III lost weight throughout the experiment, showed very weak body condition and were sacrified.

  11. Hydrophobic-modified nano-cellulose fiber/PLA biodegradable composites for lowering water vapor transmission rate (WVTR) of paper.

    Science.gov (United States)

    Song, Zhaoping; Xiao, Huining; Zhao, Yi

    2014-10-13

    New biodegradable nanocomposites have been successfully prepared by incorporating modified nano-cellulose fibers (NCF) in a biodegradable polylactic acid (PLA) matrix in this work. The hydrophobic-modified NCF was obtained by grafting hydrophobic monomers on NCF to improve the compatibility between NCF and PLA during blending. The resulting NCF/PLA composites were then applied on paper surface via a cast-coating process in an attempt to reduce the water vapor transmission rate (WVTR) of paper. The WVTR tests, conducted under various testing conditions and with different coating weights, demonstrated that the modified NCF/PLA composites coating played a critical role in lowering WVTR of paper. The lowest WVTR value was 34 g/m(2)/d, which was obtained with an addition of 1% of modified NCF to PLA and the composites coating weight at 40 g/m(2) and substantially lower than the control value at 1315 g/m(2)/d. The paper coated with the modified biodegradable composite is promising as green-based packaging materials. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Sensory evaluation of ice cream with hydrosoluble soy extract

    Directory of Open Access Journals (Sweden)

    Bueno, M.M.,

    2017-11-01

    Full Text Available Ice cream is a nutritious food because it contains ingredients responsible for supplying energy to the body. Soy has a high nutritional value and functional properties which make it to be an alternative ingredient to replace cow's milk. The purpose of this paper was to formulate an ice cream with hydrosoluble soy extract and submitted to a sensory evaluation. Two formulations of ice cream were prepared: one soy-based and the other with cow's milk (control. Both ice creams were submitted to a sensory evaluation in order to evaluate the appearance, flavor and texture attributes, for this examination it was used the hedonic scale of nine points. For the appearance attribute, the soy-based ice cream had an average score of 7.6, which means between “liked moderately and liked very much”, and cow’s milk ice cream had an average score of 8.1, “liked very much”. For the texture attribute, the soy-based ice cream reached an average of 7.4, meaning “like moderately” and “liked very much” and the cow´s milk ice cream obtained an average of 8.2, meaning “liked very much”. The flavor attribute had an average score of 6.1, meaning “liked slightly” and 8.2 “liked very much” for the soy-based ice cream and the cow´s milk ice cream respectively. When the assessors were asked about their purchase intention, 68% said that certainly they would buy the control sample and 32% definitely or probably would buy the soy-based ice cream. The sensory parameters evaluated showed that the soy-based ice cream had a good acceptance.

  13. Super-Hydrophobic/Icephobic Coatings Based on Silica Nanoparticles Modified by Self-Assembled Monolayers

    Directory of Open Access Journals (Sweden)

    Junpeng Liu

    2016-12-01

    Full Text Available A super-hydrophobic surface has been obtained from nanocomposite materials based on silica nanoparticles and self-assembled monolayers of 1H,1H,2H,2H-perfluorooctyltriethoxysilane (POTS using spin coating and chemical vapor deposition methods. Scanning electron microscope images reveal the porous structure of the silica nanoparticles, which can trap small-scale air pockets. An average water contact angle of 163° and bouncing off of incoming water droplets suggest that a super-hydrophobic surface has been obtained based on the silica nanoparticles and POTS coating. The monitored water droplet icing test results show that icing is significantly delayed by silica-based nano-coatings compared with bare substrates and commercial icephobic products. Ice adhesion test results show that the ice adhesion strength is reduced remarkably by silica-based nano-coatings. The bouncing phenomenon of water droplets, the icing delay performance and the lower ice adhesion strength suggest that the super-hydrophobic coatings based on a combination of silica and POTS also show icephobicity. An erosion test rig based on pressurized pneumatic water impinging impact was used to evaluate the durability of the super-hydrophobic/icephobic coatings. The results show that durable coatings have been obtained, although improvement will be needed in future work aiming for applications in aerospace.

  14. Comblike poly(ethylene oxide)/hydrophobic C6 branched chitosan surfactant polymers as anti-infection surface modifying agents.

    Science.gov (United States)

    Mai-ngam, Katanchalee

    2006-05-01

    A series of structurally well-defined poly(ethylene oxide)/hydrophobic C6 branched chitosan surfactant polymers that undergo surface induced self assembly on hydrophobic biomaterial surfaces were synthesized and characterized. The surfactant polymers consist of low molecular weight (Mw) chitosan backbone with hydrophilic poly(ethylene oxide) (PEO) and hydrophobic hexyl pendant groups. Chitosan was depolymerized by nitrous acid deaminative cleavage. Hexanal and aldehyde-terminated PEO chains were simultaneously attached to low Mw chitosan hydrochloride via reductive amination. The surfactant polymers were prepared with various ratios of the two side chains. The molecular composition of the surfactant polymers was determined by FT-IR and 1H NMR. Surface active properties at the air-water interface were determined by Langmuir film balance measurements. The surfactant polymers with PEO/hexyl ratios of 1:3.0 and 1:14.4 were used as surface modifying agents to investigate their anti-infection properties. E. coli adhesion on Silastic surface was decreased significantly by the surfactant polymer with PEO/hexyl 1:3.0. Surface growth of adherent E. coli was effectively suppressed by both tested surfactant polymers.

  15. Release of a Poorly Soluble Drug from Hydrophobically Modified Poly (Acrylic Acid in Simulated Intestinal Fluids.

    Directory of Open Access Journals (Sweden)

    Patrik Knöös

    Full Text Available A large part of new pharmaceutical substances are characterized by a poor solubility and high hydrophobicity, which might lead to a difference in drug adsorption between fasted and fed patients. We have previously evaluated the release of hydrophobic drugs from tablets based on Pemulen TR2 and showed that the release can be manipulated by adding surfactants. Here we further evaluate the possibility to use Pemulen TR2 in controlled release tablet formulations containing a poorly soluble substance, griseofulvin. The release is evaluated in simulated intestinal media that model the fasted state (FaSSIF medium or fed state (FeSSIF. The rheology of polymer gels is studied in separate experiments, in order to gain more information on possible interactions. The release of griseofulvin in tablets without surfactant varied greatly and the slowest release were observed in FeSSIF. Addition of SDS to the tablets eliminated the differences and all tablets showed a slow linear release, which is of obvious relevance for robust drug delivery. Comparing the data from the release studies and the rheology experiment showed that the effects on the release from the different media could to a large extent be rationalised as a consequence of the interactions between the polymer and the surfactants in the media. The study shows that Pemulen TR2 is a candidate for controlled release formulations in which addition of surfactant provides a way to eliminate food effects on the release profile. However, the formulation used needs to be designed to give a faster release rate than the tablets currently investigated.

  16. Thermal treatment to improve the hydrophobicity of ground CaCO3 particles modified with sodium stearate

    Science.gov (United States)

    Liang, Yong; Yu, Keyi; Zheng, Qinzhong; Xie, Jiuren; Wang, Ting-Jie

    2018-04-01

    The surface modification of calcium carbonate (CaCO3) particles, which is used as a filler, significantly affects the properties of the composed materials. The effects of thermal treatment on ground calcium carbonate (GCC) particles subjected to hydrophobic modification using sodium stearate (RCOONa) were studied. The contact angle of the modified GCC particles increased from 24.7° to 118.9° when the amount of RCOONa added was increased from 0% to 5% and then decreased to 97.5° when the RCOONa content was further increased to 10%. When a large amount of RCOONa was added, RCOO- reacts with Ca2+ and generates (RCOO)2Ca nuclei, which are adsorbed on the surface of the GCC particles, forming a discontinuous (RCOO)2Ca modified layer. After thermal treatment under sealed conditions, the contact angle of the GCC particles modified using 1.5% RCOONa/GCC increased from 112.8° to 139.6°. The thermal stability of the (RCOO)2Ca modified layer was increased, with the temperature increase of the mass-loss peak from 358.0 to 463.0 °C. It is confirmed that the spreading of melted (RCOO)2Ca nuclei on the surface of the GCC particles during the thermal treatment increased the continuity of the modified layer, converting the physical adsorption of the (RCOO)2Ca nuclei into chemisorption. The grafting density of RCOO- on the GCC particle surface after thermal treatment approximates to 5.00/nm2, which is close to the single-molecular-layer grafting density of RCOO-, indicating that excellent modification was achieved.

  17. Fabrication and anti-frosting performance of super hydrophobic coating based on modified nano-sized calcium carbonate and ordinary polyacrylate

    Energy Technology Data Exchange (ETDEWEB)

    Wang Hao [Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China); Tang Liming [Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China)], E-mail: tanglm@mail.tsinghua.edu.cn; Wu Xiaomin; Dai Wantian [Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China); Qiu Yipeng [Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China)

    2007-09-15

    Nano-sized calcium carbonate (CaCO{sub 3}) particles were modified by heptadecafluorodecyl trimethoxysilane under acidic water condition. An ordinary polyacrylate prepared via radical copolymerization of methyl methacrylate, butyl acrylate, acrylic acid and {beta}-hydroxyethyl methacrylate was used as the binder to form hydrophobic coatings with the modified CaCO{sub 3}. Super hydrophobic coating with water contact angle of 155{sup o} was obtained from modified CaCO{sub 3} and the polyacrylate at their weight ratio of 8/2 by a simple procedure. Based on surface analysis by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS), the super hydrophobicity can be attributed to both the surface microstructure and surface enrichment of fluoroalkyl chains. Due to a low water sliding angle, carbon black powder on super hydrophobic surface was easily removed by rolling water droplet. Furthermore, the anti-frosting performance of different surfaces was investigated, which indicated that the frost formed on superhydrophobic surface was greatly retarded compared with that on bare copper surface. The surface kept super hydrophobicity even after freezing-thawing treatment for 10 times.

  18. A modified parallel artificial membrane permeability assay for evaluating the bioconcentration of highly hydrophobic chemicals in fish.

    Science.gov (United States)

    Kwon, Jung-Hwan; Escher, Beate I

    2008-03-01

    Low cost in vitro tools are needed at the screening stage of assessment of bioaccumulation potential of new and existing chemicals because the number of chemical substances that needs to be tested highly exceeds the capacity of in vivo bioconcentration tests. Thus, the parallel artificial membrane permeability assay (PAMPA) system was modified to predict passive uptake/ elimination rate in fish. To overcome the difficulties associated with low aqueous solubility and high membrane affinity of highly hydrophobic chemicals, we measured the rate of permeation from the donor poly(dimethylsiloxane)(PDMS) disk to the acceptor PDMS disk through aqueous and PDMS membrane boundary layers and term the modified PAMPA system "PDMS-PAMPA". Twenty chemicals were selected for validation of PDMS-PAMPA. The measured permeability is proportional to the passive elimination rate constant in fish and was used to predict the "minimum" in vivo elimination rate constant. The in vivo data were very close to predicted values except for a few polar chemicals and metabolically active chemicals, such as pyrene and benzo[a]pyrene. Thus, PDMS-PAMPA can be an appropriate in vitro system for nonmetabolizable chemicals. Combination with metabolic clearance rates using a battery of metabolic degradation assays would enhance the applicability for metabolizable chemicals.

  19. Constructing Fluorine-Free and Cost-Effective Superhydrophobic Surface with Normal-Alcohol-Modified Hydrophobic SiO2 Nanoparticles.

    Science.gov (United States)

    Ye, Hui; Zhu, Liqun; Li, Weiping; Liu, Huicong; Chen, Haining

    2017-01-11

    Superhydrophobic coatings have drawn much attention in recent years for their wide potential applications. However, a simple, cost-effective, and environmentally friendly approach is still lacked. Herein, a promising approach using nonhazardous chemicals was proposed, in which multiple hydrophobic functionalized silica nanoparticles (SiO 2 NPs) were first prepared as core component, through the efficient reaction between amino group containing SiO 2 NPs and the isocyanate containing hydrophobic surface modifiers synthesized by normal alcohols, followed by simply spraying onto various substrates for superhydrophobic functionalization. Furthermore, to further improve the mechanical durability, an organic-inorganic composite superhydrophobic coating was fabricated by incorporating cross-linking agent (polyisocyanate) into the mixture of hydrophobic-functionalized SiO 2 NPs and hydroxyl acrylic resin. The hybrid coating with cross-linked network structures is very stable with excellent mechanical durability, self-cleaning property and corrosion resistance.

  20. Construction of Hydrophobic Wood Surface and Mechanical Property of Wood Cell Wall on Nanoscale Modified by Dimethyldichlorosilane

    Science.gov (United States)

    Yang, Rui; Wang, Siqun; Zhou, Dingguo; Zhang, Jie; Lan, Ping; Jia, Chong

    2018-01-01

    Dimethyldichlorosilane was used to improve the hydrophobicity of wood surface. The water contact angle of the treated wood surface increased from 85° to 143°, which indicated increased hydrophobicity. The nanomechanical properties of the wood cell wall were evaluated using a nanoindentation test to analyse the hydrophobic mechanism on the nano scale. The elastic modulus of the cell wall was significantly affected by the concentration but the influence of treatment time is insignificant. The hardness of the cell wall for treated samples was significantly affected by both treatment time and concentration. The interaction between treatment time and concentration was extremely significant for the elastic modulus of the wood cell wall.

  1. Increased Loading, Efficacy and Sustained Release of Silibinin, a Poorly Soluble Drug Using Hydrophobically-Modified Chitosan Nanoparticles for Enhanced Delivery of Anticancer Drug Delivery Systems

    Directory of Open Access Journals (Sweden)

    Cha Yee Kuen

    2017-11-01

    Full Text Available Conventional delivery of anticancer drugs is less effective due to pharmacological drawbacks such as lack of aqueous solubility and poor cellular accumulation. This study reports the increased drug loading, therapeutic delivery, and cellular accumulation of silibinin (SLB, a poorly water-soluble phenolic compound using a hydrophobically-modified chitosan nanoparticle (pCNP system. In this study, chitosan nanoparticles were hydrophobically-modified to confer a palmitoyl group as confirmed by 2,4,6-Trinitrobenzenesulfonic acid (TNBS assay. Physicochemical features of the nanoparticles were studied using the TNBS assay, and Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR analyses. The FTIR profile and electron microscopy correlated the successful formation of pCNP and pCNP-SLB as nano-sized particles, while Dynamic Light Scattering (DLS and Field Emission-Scanning Electron Microscopy (FESEM results exhibited an expansion in size between pCNP and pCNP-SLB to accommodate the drug within its particle core. To evaluate the cytotoxicity of the nanoparticles, a Methylthiazolyldiphenyl-tetrazolium bromide (MTT cytotoxicity assay was subsequently performed using the A549 lung cancer cell line. Cytotoxicity assays exhibited an enhanced efficacy of SLB when delivered by CNP and pCNP. Interestingly, controlled release delivery of SLB was achieved using the pCNP-SLB system, conferring higher cytotoxic effects and lower IC50 values in 72-h treatments compared to CNP-SLB, which was attributed to the hydrophobic modification of the CNP system.

  2. The use of dielectric spectroscopy for the characterisation of the precipitation of hydrophobically modified poly(acrylic-acid) with divalent barium ions

    DEFF Research Database (Denmark)

    Christensen, Peter Vittrup; Keiding, Kristian

    2009-01-01

    The use of dielectric spectroscopy as a monitor for coagulation processes was investigated. Hydrophobically modified poly(acrylic-acid) polymers were used as model macromolecules and coagulated with barium ions. The coagulation process was quantified using a photometric dispersion analyser, thereby...... serving as a point of reference for the dielectric spectroscopy. It was found that the hydrophobic modification increased the dosage of barium needed to obtain complete coagulation, whereas the dosage required to initiate coagulation was lowered. The coagulation of the polymer samples caused...... the relaxation time of the measured dielectric dispersion to increase, and this parameter was found to be a good indicator of the formation of polymer aggregates. The magnitude of the dielectric dispersion decreased as a function of barium dosage, but when coagulation was initiated an increase was observed...

  3. Water dispersal and functionalization of hydrophobic Iron oxide nanoparticles with lipid-modified poly(amidoamine) dendrimers

    NARCIS (Netherlands)

    Boni, A; Albertazzi, L.; Innocenti, C; Gemmi, M; Bifone, A

    2013-01-01

    A novel and facile method for water dispersal of hydrophobic iron oxide nanoparticles based on the amphiphilic PAMAM-C-12 dendrimer is described. Stable and highly concentrated water dispersions of multifunctional, magnetic nanoparticles were obtained with this single-step approach, and showed

  4. Structure of DNA-Cationic Surfactant Complexes at Hydrophobically Modified and Hydrophilic Silica Surfaces as Revealed by Neutron Reflectometry

    DEFF Research Database (Denmark)

    Cardenas Gomez, Marite; Wacklin, Hanna; Campbell, Richard A.

    2011-01-01

    with dodecyltrimethylammonium bromide (DTAB) and hexadecyltrimethylammonium bromide (CTAB) on hydrophobic surfaces, where we show that DNA molecules are located on top of a self-assembled surfactant monolayer, with the thickness of the DNA layer and the surfactant DNA ratio determined by the surface coverage of the underlying...... interfacial structures, a higher concentration in relation to its cmc is required for the more soluble DTAB surfactant with a shorter alkyl chain than for CTAB. Our results suggest that the DNA Molecules Will spontaneously form a relatively dense, thin layer on top of a surfactant monolayer (hydrophobic...... surface) or a layer of admicelles (hydrophilic surface) as long as the surface concentration of surfactant is great enough to ensure a high interfacial-charge density. These findings have implications for bioanalytical and nanotechnology applications, which require the deposition of DNA layers with well...

  5. Formation of unimer nanoparticles by controlling the self-association of hydrophobically modified poly(amino acid)s.

    Science.gov (United States)

    Akagi, Takami; Piyapakorn, Phassamon; Akashi, Mitsuru

    2012-03-20

    Amphiphilic block or graft copolymers have been demonstrated to form a variety of self-assembled nano/microstructures in selective solvents. In this study, the self-association behavior of biodegradable graft copolymers composed of poly(γ-glutamic acid) (γ-PGA) as the hydrophilic segment and L-phenylalanine (Phe) as the hydrophobic segment in aqueous solution was investigated. The association behavior and unimer nanoparticle formation of these γ-PGA-graft-Phe (γ-PGA-Phe) copolymers in aqueous solution were characterized with a focus on the effect of the Phe grafting degree on the intra- and interpolymer association of γ-PGA-Phe. The particle size and number of polymer aggregates (N(agg)) in one particle of the γ-PGA-Phe depended on the Phe grafting degree. The size of γ-PGA-Phe with 12, 27, 35, or 42% Phe grafting (γ-PGA-Phe-12, -27, -35, or -42) was about 8-14 nm and the N(agg) was about 1, supporting the presence of a unimolecular graft copolymer in PBS. The pyrene fluorescence data indicated that γ-PGA-Phe-35 and -42 have hydrophobic domains formed by the intrapolymer association of Phe attached to γ-PGA. These results suggest that the Phe grafting degree is critical to the association behavior of γ-PGA-Phe and that γ-PGA-Phe-35 and -42 could form unimer nanoparticles. Moreover, when γ-PGA-Phe-42 dissolved in DMSO was added to various concentrations of NaCl solution, the particle size and N(agg) could be easily controlled by changing the NaCl concentration during the formation of the particles. These results suggest that biodegradable γ-PGA-Phe is useful for the fabrication of very small nanoparticles. It is expected that γ-PGA-Phe nanoparticles, including unimer particles, will have great potential as multifunctional carriers for pharmaceutical and biomedical applications, such as drug and vaccine delivery systems.

  6. Thiol-modified gold-coated glass as an efficient hydrophobic substrate for drop coating deposition Raman (DCDR) technique

    Czech Academy of Sciences Publication Activity Database

    Kočišová, E.; Procházka, M.; Šípová, Hana

    2016-01-01

    Roč. 47, č. 11 (2016), s. 1394-1396 ISSN 0377-0486 R&D Projects: GA ČR(CZ) GBP205/12/G118 Institutional support: RVO:67985882 Keywords : thiol-modified Au-coated glass * drop coating deposition Raman * liposome Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.969, year: 2016

  7. Drug delivery from hydrophobic-modified mesoporous silicas: Control via modification level and site-selective modification

    International Nuclear Information System (INIS)

    Tang Qunli; Chen Yuxi; Chen Jianghua; Li Jin; Xu Yao; Wu Dong; Sun Yuhan

    2010-01-01

    Dimethylsilyl (DMS) modified mesoporous silicas were successfully prepared via co-condensation and post-grafting modification methods. The post-grafting modification was carried out by the reaction of the as-synthesized MCM-41 material (before CTAB removal) with diethoxydimethylsinale (DEDMS). N 2 adsorption-desorption and 29 Si MAS NMR characterization demonstrated that different amount of DMS groups were successfully incorporated into the co-condensation modified samples, and the functional DMS groups were placed selectively on the pore openings and external pore surfaces in the post-grafting modified samples. Subsequently, the controlled drug delivery properties from the resulting DMS-modified mesoporous silicas were investigated in detail. The drug adsorption experiments showed that the adsorption capacities were mainly depended on the content of silanol group (CSG) in the corresponding carriers. The in vitro tests exhibited that the incorporation of DMS groups greatly retarded the ibuprofen release rate. Moreover, the ibuprofen release profiles could be well modulated by varying DMS modification levels and site-selective distribution of functional groups in mesoporous carriers. - The distribution of DMS groups on the pore surfaces of the mesostructures strongly affects the drug release rate. The P-M41-1 and the P-M41-2 possess the close DMS modification levels as the C-M41-10, but the ibuprofen release rates from the P-M41-1 and P-M41-2 are much slower than that from the C-M41-10.

  8. Robust analysis of the hydrophobic basic analytes loratadine and desloratadine in pharmaceutical preparations and biological fluids by sweeping-cyclodextrin-modified micellar electrokinetic chromatography.

    Science.gov (United States)

    El-Awady, Mohamed; Belal, Fathalla; Pyell, Ute

    2013-09-27

    The analysis of hydrophobic basic analytes by micellar electrokinetic chromatography (MEKC) is usually challenging because of the tendency of these analytes to be adsorbed onto the inner capillary wall in addition to the difficulty to separate these compounds as they exhibit extremely high retention factors. A robust and reliable method for the simultaneous determination of loratadine (LOR) and its major metabolite desloratadine (DSL) is developed based on cyclodextrin-modified micellar electrokinetic chromatography (CD-MEKC) with acidic sample matrix and basic background electrolyte (BGE). The influence of the sample matrix on the reachable focusing efficiency is studied. It is shown that the application of a low pH sample solution mitigates problems associated with the low solubility of the hydrophobic basic analytes in aqueous solution while having advantages with regard to on-line focusing. Moreover, the use of a basic BGE reduces the adsorption of these analytes in the separation compartment. The separation of the studied analytes is achieved in less than 7min using a BGE consisting of 10mmolL(-1) disodium tetraborate buffer, pH 9.30 containing 40mmolL(-1) SDS and 20mmolL(-1) hydroxypropyl-β-CD while the sample solution is composed of 10mmolL(-1) phosphoric acid, pH 2.15. A full validation study of the developed method based on the pharmacopeial guidelines is performed. The method is successfully applied to the analysis of the studied drugs in tablets without interference of tablet additives as well as the analysis of spiked human urine without any sample pretreatment. Furthermore, DSL can be detected as an impurity in LOR bulk powder at the stated pharmacopeial limit (0.1%, w/w). The selectivity of the developed method allows the analysis of LOR and DSL in combination with the co-formulated drug pseudoephedrine. It is shown that in CD-MEKC with basic BGE, solute-wall interactions are effectively suppressed allowing the development of efficient and precise

  9. Thiolated and S-protected hydrophobically modified cross-linked poly(acrylic acid)--a new generation of multifunctional polymers.

    Science.gov (United States)

    Bonengel, Sonja; Haupstein, Sabine; Perera, Glen; Bernkop-Schnürch, Andreas

    2014-10-01

    The aim of this study was to create a novel multifunctional polymer by covalent attachment of l-cysteine to the polymeric backbone of hydrophobically modified cross-linked poly(acrylic acid) (AC1030). Secondly, the free thiol groups of the resulting thiomer were activated using 2-mercaptonicotinic acid (2-MNA) to provide full reactivity and stability. Within this study, 1167.36 μmol cysteine and 865.72 μmol 2-MNA could be coupled per gram polymer. Studies evaluating mucoadhesive properties revealed a 4-fold extended adherence time to native small intestinal mucosa for the thiomer (AC1030-cysteine) as well as an 18-fold prolonged adhesion for the preactivated thiomer (AC1030-Cyst-2-MNA) compared to the unmodified polymer. Modification of the polymer led to a higher tablet stability concerning the thiomer and the S-protected thiomer, but a decelerated water uptake could be observed only for the preactivated thiomer. Neither the novel conjugates nor the unmodified polymer showed severe toxicity on Caco-2 cells. Evaluation of emulsification capacity proofed the ability to incorporate lipophilic compounds like medium chain triglycerides and the preservation of the emulsifying properties after the modifications. According to these results thiolated AC1030 as well as the S-protected thiolated polymer might provide a promising tool for solid and semisolid formulations in pharmaceutical development. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Assessment of Collagen-Induced Arthritis Using Cyanine 5.5 Conjugated with Hydrophobically Modified Glycol Chitosan Nanoparticles: Correlation with 18F-Fluorodeoxyglucose Positron Emission Tomography Data

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Ji Hyeon; Lee, Sang Hoon; Lee, Sheen Woo; Moon, Dae Huk [Asan Medical Center, Ulsan University College of Medicine, Seoul (Korea, Republic of); Park, Kyoung Soon [Biomedical Research Center, Seoul (Korea, Republic of); Biswal, Sandip [Stanford University School of Medicine, Stanford (United States)

    2012-07-15

    To evaluate the potential and correlation between near-infrared fluorescence (NIRF) imaging using cyanine 5.5 conjugated with hydrophobically modified glycol chitosan nanoparticles (HGC-Cy5.5) and {sup 18}F-fluorodeoxyglucose-positron emission tomography ({sup 18}F-FDG-PET) imaging of collagen-induced arthritis (CIA). We used 10 CIA and 3 normal mice. Nine days after the injecting collagen twice, microPET imaging was performed 40 minutes after the intravenous injection of 9.3 MBq {sup 18}F-FDG in 200 {mu}L PBS. One day later, NIRF imaging was performed two hours after the intravenous injection of HGC-cy5.5 (5 mg/kg). We assessed the correlation between these two modalities in the knees and ankles of CIA mice. The mean standardized uptake values of {sup 18}F-FDG for knees and ankles were 1.68 {+-} 0.76 and 0.79 {+-} 0.71, respectively, for CIA mice; and 0.57 {+-} 0.17 and 0.54 {+-} 0.20 respectively for control mice. From the NIRF images, the total photon counts per 30 mm{sup 2} for knees and ankles were 2.32 {+-} 1.54 X 10{sup 5} and 2.75 {+-} 1.51 X 10{sup 5}, respectively, for CIA mice, and 1.22 {+-} 0.27 X 10{sup 5} and 0.88 {+-} 0.24 X 10{sup 5}, respectively, for control mice. These two modalities showed a moderate correlation for knees (r = 0.604, p = 0.005) and ankles (r = 0.464, p = 0.039). Moreover, both HGC-Cy5.5 (p = 0.002) and {sup 18}F-FDG-PET (p = 0.005) imaging also showed statistically significant differences between CIA and normal mice. NIRF imaging using HGC-Cy5.5 was moderately correlated with {sup 18}F-FDG-PET imaging in the CIA model. As such, HGC-Cy5.5 imaging can be used for the early detection of rheumatoid arthritis.

  11. Fabrication of FDTS-modified PDMS-ZnO nanocomposite hydrophobic coating with anti-fouling capability for corrosion protection of Q235 steel.

    Science.gov (United States)

    Arukalam, Innocent O; Oguzie, Emeka E; Li, Ying

    2016-12-15

    Perfluorodecyltrichlorosilane-based poly(dimethylsiloxane)-ZnO (FDTS-based PDMS-ZnO) nanocomposite coating with anti-corrosion and anti-fouling capabilities has been prepared using a one-step fabrication technique. XPS analysis and contact angle measurements showed the fluorine content to increase, while the hydrophobicity of the coatings decreased with addition of FDTS. XRD analysis revealed existence of ZnO nanoparticles of dimensions ranging from 11.45 to 93.01nm on the surface of coatings, with the mean particle size decreasing with FDTS addition, and was confirmed by SEM and TEM observations. Interestingly, the anti-corrosion performance and mechanical properties of the coatings increased remarkably on addition of FDTS. Indeed, the observed low adhesion strength, surface energies and the outstanding anti-corrosive properties imply that the obtained coating would be useful in anti-fouling applications. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Determination of hydrophobic coenzyme a esters and other lipids using a biosensor comprising a modified coenzyme a- and acyl-coa binding protein (acbp)

    DEFF Research Database (Denmark)

    2002-01-01

    , food and feed preparations, tissue extracts, acyl-CoA synthetase reaction media and various laboratory conditions using a modified Coenzyme A- and acyl-CoA binding protein (ACBP) is provided. Furthermore the invention relates to a construct comprising a peptide and a signal moiety for performing...

  13. [The effect of hydrophobic surface properties of protein on its resistance to denaturation by organic solvents (using modified alpha-chymotrypsin as an example].

    Science.gov (United States)

    Kudriashova, E V; Belova, A B; Vinogradov, A A; Mozhaev, V V

    1994-03-01

    Catalytic activity of covalently modified alpha-chymotrypsin in water/cosolvent solutions was investigated. The stability of chymotrypsin increases upon modification with hydrophilic reagents, such as glyceraldehyde, pyrometallic and succinic anhydrides, and glucosamine. Correlation was observed between the protein's stability in organic solvents and the degree of hydrophilization of the protein's surface. The protein is the more stable, the higher are the modification degree and the hydrophilicity of the modifying residue. At a certain critical hydrophilization degree of chymotrypsin a limit of stability is achieved. The stabilization effect can be accounted for by the fact that the interaction between water molecules on the surface and protein's functional groups become stronger in the hydrophilized protein.

  14. The α-chymotrypsin and its hydrophobic derivatives in inverse micelles; L'α-chymotrypsine et ses derives hydrophobes en micelles inverses

    Energy Technology Data Exchange (ETDEWEB)

    Pitre, Franck

    1993-01-29

    The α-chymotrypsin is among the most used enzymes, notably and particularly in medicine for therapeutic treatments as well as in biochemistry to determine the amine acid sequence of proteins. This research thesis addresses the study of interactions between a micro-emulsion system and an enzymatic system, and more particularly the behaviour of α-chymotrypsin in AOT inverse micelles. After a brief description of the inverse micellar system and of previously obtained results on the solubilisation of α-chymotrypsin in inverse micelles, the author reports the study of the inverse micellar phase in presence of α-chymotrypsin at the vicinity of the maximum solubility. Various techniques are used for this purpose: UV-visible absorption spectrophotometry, conductometry, and X ray scattering. Then, the author describes the chemical modification of α-chymotrypsin, and reports the study of structural as well as reaction modifications introduced during the solubilisation of α-chymotrypsin modified in inverse micelles [French] L'α-chymotrypsine compte parmi les enzymes les plus utilisees dans le monde. Elle est employee tout aussi bien en medecine pour des actions therapeutiques qu'en biochimie afin de determiner entre autre la sequence en acides amines des proteines a etudier. Son succes provient en partie du fait qu'elle hydrolyse avec efficacite un grand nombre de liaisons peptidiques. Les micelles inverses sont un milieu adequat pour permettre l'hydrolyse de molecules relativement hydrophobes par l'α-chymotrypsine. Elle peut ainsi fonctionner dans un milieu tres fortement organique sans etre denaturee. Nous avons montre d'une part que l'α-chymotrypsine se localise au coeur de la micelle inverse sans contact permanent avec les molecules tensioactives. La solubilisation de l'α-chymotrypsine n'a aucune influence sur la taille, pour des micelles dont le rayon est superieur a celui de l'enzyme, et sur le potentiel d'interaction intermicellaire et ceci meme pour des

  15. Synthesis of hydrosoluble cryptophanes, designed to encapsulate xenon, and of hemi-cryptophanes functionalized to complex lanthanide (III) ions, with the intention to apply them in medical imaging

    International Nuclear Information System (INIS)

    Godart, Estelle

    2017-01-01

    This book details all the research work that has been done during three years of Ph-D. After a chapter dedicated to the general principles of supramolecular chemistry, and some of its applications, we focalize on the use of cage-shapes molecules (cryptophanes and hemi-cryptophanes) in order to build probes for biological imaging. We successively mention the way toward the synthesis of a hemi-cryptophane able to complex Gadolinium(III), to use it it as a proton-MRI contrast agent, then toward the elaboration of hydrosoluble cryptophanes adapted to 129 Xe NMR and MRI. This PhD manuscript ends with the synthesis of a new hemi-cryptophane functionalized to form complexes with Terbium(III) and Europium(III), whose fluorescence properties are promising. (author)

  16. Responsive gelation of hydrophobized linear polymer

    DEFF Research Database (Denmark)

    Madsen, Claus Greve; Toeth, Joachim; Jørgensen, Lene

    In this study we present the rheological properties of a physically linked polymer network, composed of linear hydrophilic chains, modified with hydrophobic moieties in each end. Solutions of the polymer in ethanol-water mixtures showed Newtonian behaviour up to about 99 % ethanol, with the highest...

  17. Design of textured surfaces for super-hydrophobicity

    Indian Academy of Sciences (India)

    Prithvi Raj Jelia

    2017-11-11

    Nov 11, 2017 ... as silicon wafer [1, 10, 11]. Yoon et al [12] used a modified ... The explanation for the increase in the contact angle or hydrophobicity on the ... water droplets on super-hydrophobic surfaces that exhibit large contact angles are ...

  18. 疏水改性阳离子高分子絮凝剂的合成及其絮凝性能%Synthesis of the hydrophobic, modified, cationic, and polymeric flocculant and its flocculation capacity for wastewater

    Institute of Scientific and Technical Information of China (English)

    王永军; 吕学良; 郭海军

    2017-01-01

    Hydrophobic,modified,cationic,and polymeric flocculant P (DMC-MMA)has been polymerized and prepared by soap-free emulsion polymerization,using methacryloxyethyltrimethyl ammonium chloride (DMC) and methyl methacrylate (MMA)as raw materials.The influences of different factors,including monomer mass fraction,reaction temperature,initiator dosage and reaction time on the P (DMC-MMA)removing effect are investigated.The results show that under the following conditions:total monomer mass fraction is 30%,n (DMC):n (MMA)=7:3,reaction temperature 75 ℃,initiator dosage 0.5% and reaction time 8 h,the prepared P(DMC-MMA)has good flocculation effect.The maximum oil removing rate can reach 96%.In addition,the flocs do not adhere to the walls.%以甲基丙烯酰氧乙基三甲基氯化铵(DMC)和甲基丙烯酸甲酯(MMA)为原料,通过无皂乳液聚合制备了流动性好的疏水改性阳离子型高分子絮凝剂P (DMC-MMA),并考察了不同因素对P(DMC-MMA)除油效果的影响.结果表明:在单体总质量分数为30%、n(DMC):n(MMA)=7:3、反应温度75℃、引发剂用量为0.5%、反应时间8h条件下制备的P(DMC-MMA)具有良好的絮凝效果,最高除油率可达96%,且絮体不黏壁.

  19. Cholesterol and fat lowering with hydrophobic polysaccharide derivatives

    Czech Academy of Sciences Publication Activity Database

    Čopíková, J.; Taubner, T.; Tůma, J.; Synytsya, A.; Dušková, Dagmar; Marounek, Milan

    2015-01-01

    Roč. 116, č. 1 (2015), s. 207-214 ISSN 0144-8617 Institutional support: RVO:67985904 Keywords : hydrophobically modified polysaccharides * structure * thermal analysis Subject RIV: CE - Biochemistry Impact factor: 4.219, year: 2015

  20. Fabrication of hydrophobic/super-hydrophobic nanofilms on magnesium alloys by polymer plating

    International Nuclear Information System (INIS)

    Kang Zhixin; Lai Xiaoming; Sang Jing; Li Yuanyuan

    2011-01-01

    Hydrophobic/super-hydrophobic nanofilms with improved corrosion resistance were fabricated on the surfaces of Mg–Mn–Ce magnesium alloy by a surface modification technique, named as polymer plating, which has been developed to modify superficial characteristics of magnesium alloys with polymeric nanofilms through synthesized organic compounds of triazine dithiol containing functional groups. The nanofilms were prepared by the electrochemical and polymerization reactions during polymer plating analyzed from characteristics of Fourier transform infrared spectrophotometer, X-ray photoelectron spectroscopy and scanning electron microscopy. The fabricated nanofilms changed the surface wettability of blank magnesium alloy from hydrophilic to hydrophobic with contact angle 119.0° of distilled water with lower surface free energy of 20.59 mJ/m 2 and even super-hydrophobic with contact angle 158.3° with lowest surface free energy of 4.68 mJ/m 2 by different functional nanofilms on their surfaces. Alteration of wettability from hydrophilic to hydrophobic and super-hydrophobic resulted from their low surface free energy and surface morphology with micro- and nano-rough structures. The corrosion behaviors from potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) show that the super-hydrophobic nanofilm has higher corrosion resistance and stability in 0.1 mol/L NaCl solution and lower corrosion current density (I corr ) with R ct increasing two orders of magnitude of 16,500 Ω·cm 2 compared to that obtained for blank of 485 Ω·cm 2 .

  1. Pigmentos lipossolúveis e hidrossolúveis em plantas de salvínia sob toxicidade por cromo Liposoluble and hydrosoluble pigments in salvinia under chromium toxicity

    Directory of Open Access Journals (Sweden)

    P.F. Pereira

    2012-12-01

    Full Text Available Devido à intensa utilização industrial, o cromo é considerado um importante poluente ambiental. O presente trabalho objetivou determinar os teores de pigmentos hidro e lipossolúveis em plantas de salvínia expostas a concentrações crescentes de Cr, visando estabelecer parâmetros bioquímicos para utilização dessa macrófita em programas de biomonitoramento e/ou fitorremediação da poluição causada por esse poluente metálico em ambientes aquáticos. As plantas foram submetidas a concentrações crescentes de Cr e avaliadas após quatro, seis e dez dias de tratamento. Os resultados dos ensaios permitiram concluir que plantas de salvínia sob condições de estresse por Cr apresentam reduções nas concentrações das clorofilas a, b e total e, em contraste, aumentos nas concentrações de antocianinas totais. Embora a concentração de carotenoides totais não tenha sido alterada em resposta ao Cr, as variações nas concentrações dos demais pigmentos lipossolúveis e dos pigmentos hidrossolúveis observadas nas folhas das plantas de salvínia podem ser utilizadas como parâmetros bioquímicos de biomonitoramento da poluição causada por esse elemento metálico em ambientes aquáticos.Due to widespread industrial use, chromium is considered a serious environmental pollutant. This study aimed to determine the content of hydrosoluble and liposoluble pigments in salvinia plants exposed to increasing concentrations of Cr, to establish biochemical parameters for the use of macrophyta in pollution bio-monitoring programs and/or phyto-remediation in aquatic environments by this pollutant metal. The plants were exposed to increasing concentrations of Cr and evaluated after four, six, and ten days of treatment. The test results showed that salvinia plants under stress conditions for Cr exhibit decreases in the concentrations of chlorophylls a, b, and total, and, in contrast, increases in anthocyanin concentrations. Although the

  2. Hydrophobic treatment of concrete

    NARCIS (Netherlands)

    Vries, J. de; Polder, R.B.

    1996-01-01

    As part of the maintenance policy of the Dutch Ministry of Transport, Civil Engineering Division, hydrophobic treatment of concrete was considered as an additional protective measure against penetration of aggressive substances, for instance deicing salts in bridge decks. A set of tests was designed

  3. Analytical method (HPLC, validation used for identification and assay of the pharmaceutical active ingredient, Tylosin tartrate for veterinary use and its finite product Tilodem 50, hydrosoluble powder

    Directory of Open Access Journals (Sweden)

    Maria Neagu

    2010-12-01

    Full Text Available In SC DELOS IMPEX ’96 SRL the quality of the active pharmaceutical ingredient (API for the finite product Tilodem 50 - hydrosoluble powder was acomkplished in the respect of last European Pharmacopoeia.The method for analysis used in this purpose was the compendial method „Tylosin tartrate for veterinary use” in EurPh. in vigour edition and represent a variant developed and validation „in house”.The parameters which was included in the methodology validation for chromatographic method are the followings: Selectivity, Linearity, Linearity range, Detection and Quantification limits, Precision, Repeatability (intra day, Inter-Day Reproductibility, Accuracy, Robustness, Solutions’ stability and System suitability. According to the European Pharmacopoeia, the active pharmaceutical ingredient is consistent, in terms of quality, if it contains Tylosin A - minimum 80% and the amount of Tylosin A, B, C, D, at minimum 95%. Identification and determination of each component separately (Tylosin A, B, C, D is possible by chromatographic separation-HPLC. Validation of analytical methods is presented below.

  4. Fabrication of hydrophobic/super-hydrophobic nanofilms on magnesium alloys by polymer plating

    Energy Technology Data Exchange (ETDEWEB)

    Kang Zhixin, E-mail: zxkang@scut.edu.cn; Lai Xiaoming; Sang Jing; Li Yuanyuan

    2011-11-01

    Hydrophobic/super-hydrophobic nanofilms with improved corrosion resistance were fabricated on the surfaces of Mg-Mn-Ce magnesium alloy by a surface modification technique, named as polymer plating, which has been developed to modify superficial characteristics of magnesium alloys with polymeric nanofilms through synthesized organic compounds of triazine dithiol containing functional groups. The nanofilms were prepared by the electrochemical and polymerization reactions during polymer plating analyzed from characteristics of Fourier transform infrared spectrophotometer, X-ray photoelectron spectroscopy and scanning electron microscopy. The fabricated nanofilms changed the surface wettability of blank magnesium alloy from hydrophilic to hydrophobic with contact angle 119.0 Degree-Sign of distilled water with lower surface free energy of 20.59 mJ/m{sup 2} and even super-hydrophobic with contact angle 158.3 Degree-Sign with lowest surface free energy of 4.68 mJ/m{sup 2} by different functional nanofilms on their surfaces. Alteration of wettability from hydrophilic to hydrophobic and super-hydrophobic resulted from their low surface free energy and surface morphology with micro- and nano-rough structures. The corrosion behaviors from potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) show that the super-hydrophobic nanofilm has higher corrosion resistance and stability in 0.1 mol/L NaCl solution and lower corrosion current density (I{sub corr}) with R{sub ct} increasing two orders of magnitude of 16,500 {Omega}{center_dot}cm{sup 2} compared to that obtained for blank of 485 {Omega}{center_dot}cm{sup 2}.

  5. Water on a Hydrophobic surface

    Science.gov (United States)

    Scruggs, Ryan; Zhu, Mengjue; Poynor, Adele

    2012-02-01

    Hydrophobicity, meaning literally fear of water, is exhibited on the surfaces of non-stick cooking pans and water resistant clothing, on the leaves of the lotus plan, or even during the protein folding process in our bodies. Hydrophobicity is directly measured by determining a contact angle between water and an objects surface. Associated with a hydrophobic surface is the depletion layer, a low density region approximately 0.2 nm thick. We study this region by comparing data found in lab using surface plasmon resonance techniques to theoretical calculations. Experiments use gold slides coated in ODT and Mercapto solutions to model both hydrophobic and hydrophilic surfaces respectively.

  6. The validation of the analytical method (HPLC, use for identification and assay of the pharmaceutical active ingredient, colistine sulphate and the finished product Colidem 50 – hydrosoluble powder, in SC DELOS impex ‘96 SRL

    Directory of Open Access Journals (Sweden)

    Maria Neagu,

    2011-06-01

    Full Text Available In SC DELOS IMPEX ’96 SRL the quality of the active pharmaceutical ingredient (API for the finished product Colidem 50 - hydrosoluble powder is make according to European Pharmacopoeia, curent edition. The method for analysis use in this purpose is the compendial method „Colistine sulphate” in E.P. in current edition and represent a optimized variant, developed and validated „in house”.The parameters which was included in the methodology validation for chromatographic method are the follow: Selectivity/Specificity, Linearity, Range of Linearity, Limit of Detection and Limit of Quantification, Precision (Repeatability - intra day, inter-Day Reproducibility, Accuracy, Robustness, Stability Solutions and System Suitability.

  7. Nanoscale encapsulation: the structure of cations in hydrophobic microporous aluminosilicates

    International Nuclear Information System (INIS)

    Wasserman, S.R.; Yuchs, S.E.; Giaquinta, D.; Soderholm, L.; Song, Kang.

    1996-01-01

    Hydrophobic microporous aluminosilicates, created by organic surface modification of inherently hydrophilic materials such as zeolites and clays, are currently being investigated as storage media for hazardous cations. Use of organic monolayers to modify the surface of an aluminosilicate after introducing an ion into the zeolite/clay reduces the interaction of water with the material. Resulting systems are about 20 times more resistant to leaching of stored ion. XAS spectra from the encapsulated ion demonstrate that byproducts from the organic modifier can complex with the stored cation. This complexation can result in a decreased affinity of the cation for the aluminosilicate matrix. Changing the organic modifier eliminates this problem. XAS spectra also indicate that the reactivity and speciation of the encapsulated ion may change upon application of the hydrophobic layer

  8. Preparation of inorganic hydrophobic catalysts

    International Nuclear Information System (INIS)

    Yang, Yong; Wang, Heyi; Du, Yang

    2009-04-01

    In order to catalyse the oxidation of tritium gas, two inorganic hydrophobic catalysts are prepared. Under room temperature, the catalysed oxidation ratio of 0.3%-1% (V/V) hydrogen gas in air is higher than 95%. Pt-II inorganic hydrophobic catalysts has obviously better catalysing ability than Pt-PTFE and lower ability than Pt-SDB in H 2 -HTO isotopic exchange, because the pressure resistence of Pt-II is much higher than Pt-SDB, it can be used to the CECE cell of heavy water detritium system. (authors)

  9. Influence of variation in mobile phase pH and solute pK(a) with the change of organic modifier fraction on QSRRs of hydrophobicity and RP-HPLC retention of weakly acidic compounds.

    Science.gov (United States)

    Han, Shu-ying; Liang, Chao; Zou, Kuan; Qiao, Jun-qin; Lian, Hong-zhen; Ge, Xin

    2012-11-15

    The variation in mobile phase pH and ionizable solute dissociation constant (pK(a)) with the change of organic modifier fraction in hydroorganic mobile phase has seemingly been a troublesome problem in studies and applications of reversed phase high performance liquid chromatography (RP-HPLC). Most of the early studies regarding the RP-HPLC of acid-base compounds have to measure the actual pH of the mixed mobile phase rigorously, sometimes bringing difficulties in the practices of liquid chromatographic separation. In this paper, the effect of this variation on the apparent n-octanol/water partition coefficient (K(ow)″) and the related quantitative structure-retention relationship (QSRR) of logK(ow)″ vs. logk(w), the logarithm of retention factor of analytes in neat aqueous mobile phases, was investigated for weakly acidic compounds. This QSRR is commonly used as a classical method for K(ow) measurement by RP-HPLC. The theoretical and experimental derivation revealed that the variation in mobile phase pH and solute pK(a) will not affect the QSRRs of acidic compounds. This conclusion is proved to be suitable for various types of ion-suppressors, i.e., strong acid (perchloric acid), weak acid (acetic acid) and buffer salt (potassium dihydrogen phosphate/phosphoric acid, PBS). The QSRRs of logK(ow)″ vs. logk(w) were modeled by 11 substituted benzoic acids using different types of ion-suppressors in a binary methanol-water mobile phase to confirm our deduction. Although different types of ion-suppressor all can be used as mobile phase pH modifiers, the QSRR model obtained by using perchloric acid as the ion-suppressor was found to have the best result, and the slightly inferior QSRRs were obtained by using acetic acid or PBS as the ion-suppressor. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Hydrophobic patches on protein surfaces

    NARCIS (Netherlands)

    Lijnzaad, P.

    2007-01-01

    Hydrophobicity is a prime determinant of the structure and function of proteins. It is the driving force behind the folding of soluble proteins, and when exposed on the surface, it is frequently involved in recognition and binding of ligands and other proteins. The energetic cost of

  11. Transparent Hydrophobic Coating by Sol Gel Method

    International Nuclear Information System (INIS)

    Mohd Hamzah Harun; Nik Ghazali Nik Salleh; Mahathir Mohamed; Mohd Sofian Alias

    2016-01-01

    Transparent hydrophobic coating of inorganic based tetra orthosilicate (TEOS) was prepared by sol gel method by varying fluoroalkylsilane (FAS) content which works as hydrophobic agent. Surface contact angle, transmittance degree and surface morphology were characterized for each sample. All samples show good transparency which was confirmed by UV visible spectroscopy. The hydrophobicity obtained increases with FAS content indicates that FAS is best candidate to induce hydrophobicity for inorganic coating. (author)

  12. 21 CFR 584.700 - Hydrophobic silicas.

    Science.gov (United States)

    2010-04-01

    ...) Product. Amorphous fumed hydrophobic silica or precipitated hydrophobic silica (CAS Reg. No. 68611-0944... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Hydrophobic silicas. 584.700 Section 584.700 Food... DRUGS, FEEDS, AND RELATED PRODUCTS FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE IN FEED AND...

  13. Modification of epoxy resin, silicon and glass surfaces with alkyl- or fluoroalkylsilanes for hydrophobic properties

    International Nuclear Information System (INIS)

    Marczak, Jacek; Kargol, Marta; Psarski, Maciej; Celichowski, Grzegorz

    2016-01-01

    Graphical abstract: - Highlights: • Chemical structure of alkylsilanes and fluoroalkylsilanes can affect the hydrophobic and surface performance of the modified samples. • Wet chemical hydrophobization is relatively simple and inexpensive method to obtain hydrophobic/superhydrophobic coatings. • The samples degradation is not observed and hydrophobic coatings seem to be stable in UV light. - Abstract: Preparation of superhydrophobic materials inspired by nature has attracted a great scientific interest in recent decades. Some of these materials have hierarchical lotus-like structures, i.e. micro- and nano-objects coated by hydrophobic compounds. A major challenge of applying the superhydrophobic surfaces for the self-cleaning coatings preparation is their improved efficiency in varying atmospheric conditions, e.g. UV light. The objective of this research work was to investigate the effect of the different chemical structure and the surface free energy on the hydrophobic and tribological properties of the alkylsilanes and fluoroalkylsilanes deposited on silicon wafers, glass slides and epoxy resin. Tribological and hydrophobic properties of the modified surfaces were correlated with their chemical structures. Chemical structures of the deposited materials were examined by using Fourier transform infrared (FT-IR) spectroscopy and hydrophobic properties were investigated by water contact angle (WCA) and surface free energy (SFE) measurements. The modified surfaces exhibited water contact angles of above 100° for the selected modifiers. It was noticed that the replacement of hydrogen atoms by fluorine atoms in alkyl chain caused an increase in the water contact angle values and a decrease in friction coefficients. The obtained results showed that the carbon chain length of a modifier and its chemical structure can strongly affect the hydrophobic and tribological properties of the modified surfaces. The highest values of WCA, lowest values of SFE and coefficient

  14. Hydrophobic-Core Microcapsules and Their Formation

    Science.gov (United States)

    Calle, Luz M. (Inventor); Li, Wenyan (Inventor); Buhrow, Jerry W. (Inventor); Jolley, Scott T. (Inventor)

    2016-01-01

    Hydrophobic-core microcapsules and methods of their formation are provided. A hydrophobic-core microcapsule may include a shell that encapsulates a hydrophobic substance with a core substance, such as dye, corrosion indicator, corrosion inhibitor, and/or healing agent, dissolved or dispersed therein. The hydrophobic-core microcapsules may be formed from an emulsion having hydrophobic-phase droplets, e.g., containing the core substance and shell-forming compound, dispersed in a hydrophilic phase. The shells of the microcapsules may be capable of being broken down in response to being contacted by an alkali, e.g., produced during corrosion, contacting the shell.

  15. Complexing power of hydro-soluble degradation products from γ-irradiated polyvinylchloride. Influence on Eu(OH)_3(s) solubility and Eu(III) speciation in neutral to alkaline environment

    International Nuclear Information System (INIS)

    Reiller, Pascal E.; Badji, Hawa; Tabarant, Michel; Vercouter, Thomas; Fromentin, Elodie; Ferry, Muriel; Dannoux-Papin, Adeline

    2017-01-01

    The complexing power of hydrosoluble degradation products (HDPs) from an alkaline hydrolysis of a 10 MGy γ-irradiated polyvinylchloride is studied. The complexation of Eu(III), as an analogue of lanthanide and actinide radionuclides at their +III oxidation state for oxygen containing functions, is evidenced both from the increasing of Eu(OH)_3(s) dissolution, and from a complexometric titration by time-resolved luminescence spectroscopy. The dissolution of Eu(OH)_3(s) in a simplified alkaline solution (0.3 M KOH/0.1 M NaOH) increases moderately, but significantly, with the HDPs concentration. The luminescence signal of the supernatant clearly indicates the presence of several complexed Eu(III) species. Performing a complexometric titration of Eu(III) from pH 6 by alkaline HDPs shows the formation of two different species with increasing HDPs' concentration and pH. Operational complexation constants - based on dissolved carbon concentration - are proposed. The analyses of the spectra and luminescence decays seem to confirm the presence of two different species.

  16. Complexing power of hydro-soluble degradation products from γ-irradiated polyvinylchloride. Influence on Eu(OH){sub 3}(s) solubility and Eu(III) speciation in neutral to alkaline environment

    Energy Technology Data Exchange (ETDEWEB)

    Reiller, Pascal E.; Badji, Hawa; Tabarant, Michel; Vercouter, Thomas [CEA, Paris-Saclay Univ., Gif-sur-Yvette (France). Service d' Etudes Analytiques et de Reactivite des Surfaces (SEARS); Fromentin, Elodie; Ferry, Muriel [CEA, Paris-Saclay Univ., Gif-sur-Yvette (France). Service d' Etudes du Comportement des Radionucleides (SECR); Dannoux-Papin, Adeline [CEA, Bagnols-sur-Ceze (France). Service des Procedes de Decontamination et d' Enrobage

    2017-10-01

    The complexing power of hydrosoluble degradation products (HDPs) from an alkaline hydrolysis of a 10 MGy γ-irradiated polyvinylchloride is studied. The complexation of Eu(III), as an analogue of lanthanide and actinide radionuclides at their +III oxidation state for oxygen containing functions, is evidenced both from the increasing of Eu(OH){sub 3}(s) dissolution, and from a complexometric titration by time-resolved luminescence spectroscopy. The dissolution of Eu(OH){sub 3}(s) in a simplified alkaline solution (0.3 M KOH/0.1 M NaOH) increases moderately, but significantly, with the HDPs concentration. The luminescence signal of the supernatant clearly indicates the presence of several complexed Eu(III) species. Performing a complexometric titration of Eu(III) from pH 6 by alkaline HDPs shows the formation of two different species with increasing HDPs' concentration and pH. Operational complexation constants - based on dissolved carbon concentration - are proposed. The analyses of the spectra and luminescence decays seem to confirm the presence of two different species.

  17. Fabrication of TiO2/EP super-hydrophobic thin film on filter paper surface.

    Science.gov (United States)

    Gao, Zhengxin; Zhai, Xianglin; Liu, Feng; Zhang, Ming; Zang, Deli; Wang, Chengyu

    2015-09-05

    A composite filter paper with super-hydrophobicity was obtained by adhering micro/nano structure of amorphous titanium dioxide on the filter paper surface with modifying low surface energy material. By virtue of the coupling agent, which plays an important part in bonding amorphous titanium dioxide and epoxy resin, the structure of super-hydrophobic thin film on the filter paper surface is extremely stable. The microstructure of super-hydrophobic filter paper was characterized by scanning electron microscopy (SEM), the images showed that the as-prepared filter paper was covered with uniform amorphous titanium dioxide particles, generating a roughness structure on the filter paper surface. The super-hydrophobic performance of the filter paper was characterized by water contact angle measurements. The observations showed that the wettability of filter paper samples transformed from super-hydrophilicity to super-hydrophobicity with the water contact angle of 153 ± 1°. Some experiments were also designed to test the effect of water-oil separation and UV-resistant by the super-hydrophobic filter paper. The prepared super-hydrophobic filter paper worked efficiently and simply in water-oil separation as well as enduringly in anti-UV property after the experiments. This method offers an opportunity to the practical applications of the super-hydrophobic filter paper. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Hydrophobically Modified Chitosan Gauze for Control of Massive Hemorrhage

    Science.gov (United States)

    2016-01-01

    wound in a similar fashion to a beaver dam stopping the flow of water in a stream. This mechanism is supported by Figure 3, which shows that both ChG...RF, Roberts CP, Leppaniemi A. A profile of combat injury. J Trauma. 2003; 54(5 Suppl):S13-S19. 4. Kauvar DS, Lefering R, Wade CE. Impact of

  19. Monolayers and thin films of dextran hydrophobically modified

    International Nuclear Information System (INIS)

    Leiva, Angel; Munoz, Natalia; Gargallo, Ligia; Radic, Deodato; Urzua, Marcela

    2010-01-01

    A series of biodegradable graft copolymers were synthesized by grafting e-caprolactone over dextran of different molecular weights. The obtained copolymers were characterized by Fourier transform infrared spectroscopy FTIR, proton nuclear magnetic resonance 1H NMR, thermogravimetry and elemental analysis. Stable monolayers at the air-water interface and spin coated thin films were prepared and characterized by the Langmuir technique and by contact angle measurements respectively. The compressibility and static surface elasticity of the monolayers and the surface energy of copolymer thin films show dependence with the e-caprolactone content. >From these results it can be concluded that the surface properties of grafted copolymers can be modulated by their composition. Additionally, according to the obtained results, e-caprolactone grafted-dextrans show potential for being used in different applications where surface properties are important. (author)

  20. Influence of hydrophobic characteristic of organo-modified precursor ...

    Indian Academy of Sciences (India)

    mize repelling or dirt removal when the water falls on it. The commercial products .... invasive back-scattering (NIBS) technology (173. ◦ detection optics), in .... of species with different structures (Rikowski and Marsmann. 1997). 3.2 Particle size ...

  1. Is Br2 hydration hydrophobic?

    Science.gov (United States)

    Alcaraz-Torres, A; Gamboa-Suárez, A; Bernal-Uruchurtu, M I

    2017-02-28

    The spectroscopic properties of bromine in aqueous systems suggest it can behave as either hydrophilic or hydrophobic solute. In small water clusters, the halogen bond and the hydrogen-halogen interaction are responsible for its specific way of binding. In water hydrates, it is efficiently hosted by two different cages forming the crystal structure and it has been frequently assumed that there is little or no interaction between the guest and the host. Bromine in liquid solution poses a challenging question due to its non-negligible solubility and the large blue shift measured in its absorption spectra. Using a refined semi-empirical force field, PM3-PIF, we performed a Born-Oppenheimer molecular dynamics study of bromine in liquid water. Here we present a detailed study in which we retrieved the most representative hydration structures in terms of the most frequent positions around bromine and the most common water orientations. Albeit being an approximate description of the total hydration phenomenon, it captures the contribution of the leading molecular interactions in form of the recurrent structures. Our findings confirm that the spectroscopic signature is mainly caused by the closest neighbors. The dynamics of the whole first hydration shell strongly suggests that the external molecules in that structure effectively isolate the bulk from the presence of bromine. The solvation structure fluctuates from a hydrophilic to a hydrophobic-like environment along the studied trajectory.

  2. Characterisation of nanomaterial hydrophobicity using engineered surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Desmet, Cloé; Valsesia, Andrea; Oddo, Arianna; Ceccone, Giacomo; Spampinato, Valentina; Rossi, François; Colpo, Pascal, E-mail: pascal.colpo@ec.europa.eu [Directorate Health, Consumer and Reference Materials, Consumer Products Safety Unit (Italy)

    2017-03-15

    Characterisation of engineered nanomaterials (NMs) is of outmost importance for the assessment of the potential risks arising from their extensive use. NMs display indeed a large variety of physico-chemical properties that drastically affect their interaction with biological systems. Among them, hydrophobicity is an important property that is nevertheless only slightly covered by the current physico-chemical characterisation techniques. In this work, we developed a method for the direct characterisation of NM hydrophobicity. The determination of the nanomaterial hydrophobic character is carried out by the direct measurement of the affinity of the NMs for different collectors. Each collector is an engineered surface designed in order to present specific surface charge and hydrophobicity degrees. Being thus characterised by a combination of surface energy components, the collectors enable the NM immobilisation with surface coverage in relation to their hydrophobicity. The experimental results are explained by using the extended DLVO theory, which takes into account the hydrophobic forces acting between NMs and collectors.

  3. Rhizosphere hydrophobicity: A positive trait in the competition for water.

    Science.gov (United States)

    Zeppenfeld, Thorsten; Balkenhol, Niko; Kóvacs, Kristóf; Carminati, Andrea

    2017-01-01

    The ability to acquire water from the soil is a major driver in interspecific plant competition and it depends on several root functional traits. One of these traits is the excretion of gel-like compounds (mucilage) that modify physical soil properties. Mucilage secreted by roots becomes hydrophobic upon drying, impedes the rewetting of the soil close to the root, the so called rhizosphere, and reduces water availability to plants. The function of rhizosphere hydrophobicity is not easily understandable when looking at a single plant, but it may constitute a competitive advantage at the ecosystem level. We hypothesize that by making the top soil hydrophobic, deep-rooted plants avoid competititon with shallow-rooted plants. To test this hypothesis we used an individual-based model to simulate water uptake and growth of two virtual plant species, one deep-rooted plant capable of making the soil hydrophobic and a shallow-rooted plant. We ran scenarios with different precipitation regimes ranging from dry to wet (350, 700, and 1400 mm total annual precipitation) and from high to low precipitation frequencies (1, 7, and 14 days). Plant species abundance and biomass were chosen as indicators for competitiveness of plant species. At constant precipitation frequency mucilage hydrophobicity lead to a benefit in biomass and abundance of the tap-rooted population. Under wet conditions this effect diminished and tap-rooted plants were less productive. Without this trait both species coexisted. The effect of root exudation trait remained constant under different precipitation frequencies. This study shows that mucilage secretion is a competitive trait for the acquisition of water. This advantage is achieved by the modification of the soil hydraulic properties and specifically by inducing water repellency in soil regions which are shared with other species.

  4. Rhizosphere hydrophobicity: A positive trait in the competition for water.

    Directory of Open Access Journals (Sweden)

    Thorsten Zeppenfeld

    Full Text Available The ability to acquire water from the soil is a major driver in interspecific plant competition and it depends on several root functional traits. One of these traits is the excretion of gel-like compounds (mucilage that modify physical soil properties. Mucilage secreted by roots becomes hydrophobic upon drying, impedes the rewetting of the soil close to the root, the so called rhizosphere, and reduces water availability to plants. The function of rhizosphere hydrophobicity is not easily understandable when looking at a single plant, but it may constitute a competitive advantage at the ecosystem level. We hypothesize that by making the top soil hydrophobic, deep-rooted plants avoid competititon with shallow-rooted plants. To test this hypothesis we used an individual-based model to simulate water uptake and growth of two virtual plant species, one deep-rooted plant capable of making the soil hydrophobic and a shallow-rooted plant. We ran scenarios with different precipitation regimes ranging from dry to wet (350, 700, and 1400 mm total annual precipitation and from high to low precipitation frequencies (1, 7, and 14 days. Plant species abundance and biomass were chosen as indicators for competitiveness of plant species. At constant precipitation frequency mucilage hydrophobicity lead to a benefit in biomass and abundance of the tap-rooted population. Under wet conditions this effect diminished and tap-rooted plants were less productive. Without this trait both species coexisted. The effect of root exudation trait remained constant under different precipitation frequencies. This study shows that mucilage secretion is a competitive trait for the acquisition of water. This advantage is achieved by the modification of the soil hydraulic properties and specifically by inducing water repellency in soil regions which are shared with other species.

  5. Patterned hydrophobic and hydrophilic surfaces of ultra-smooth nanocrystalline diamond layers

    Energy Technology Data Exchange (ETDEWEB)

    Mertens, M., E-mail: michael.mertens@uni-ulm.de [Institute of Micro and Nanomaterials, Ulm University, 89081 Ulm (Germany); Mohr, M.; Brühne, K.; Fecht, H.J. [Institute of Micro and Nanomaterials, Ulm University, 89081 Ulm (Germany); Łojkowski, M.; Święszkowski, W. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Warsaw (Poland); Łojkowski, W. [Institute of High Pressure Physics, Polish Academy of Sciences, Warsaw (Poland)

    2016-12-30

    Highlights: • Hydrophobic and hydrophilic properties on fluorine-, hydrogen- and oxygen- terminated ultra-nanocrystalline diamond films. • Micropatterned - multi-terminated layers with both hydrophobic and hydrophilic areas on one sample. • Visualization of multi-terminated surfaces by e.g. SEM and LFM. • Roughness and friction investigations on different terminated surfaces. • Smooth and biocompatible surfaces with same roughness regardless of hydrophobicity for microbiological investigations. - Abstract: In this work, we show that ultra nanocrystalline diamond (UNCD) surfaces have been modified to add them hydrophobic and hydrophilic properties. The nanocrystalline diamond films were deposited using the hot filament chemical vapor deposition (HFCVD) technique. This allows growing diamond on different substrates which can be even 3D or structured. Silicon and, for optical applications, transparent quartz glass are the preferred substrates for UNCD layers growth. Fluorine termination leads to strong hydrophobic properties as indicated by a high contact angle for water of more than 100°. Hydrogen termination shows lesser hydrophobic behavior. Hydrophilic characteristics has been realised with oxygen termination. X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX) measurements confirm the oxygen and fluorine- termination on the nanocrystalline diamond surface. Further, by micropatterning using photolithography, multi-terminated layers have been created with both hydrophobic and hydrophilic areas. In addition, we have shown that retermination is achieved, and the properties of the surface have been changed from hydrophobic to hydrophilic and vice versa. Micro- roughness and stress in the grown film influences slightly the wetting angle as well. The opportunity to realize local differences in hydrophobicity on nanocrystalline diamond layers, in any size or geometry, offers interesting applications for example in

  6. Durability of hydrophobic treatment of concrete

    NARCIS (Netherlands)

    Vries, J. de; Polder, R.B.; Borsje, H.

    1998-01-01

    The subject of this study was the performance of hydrophobic treatment to protect concrete against chloride penetration from de-icing salts. Hydrophobic treatment makes a concrete surface absorb less water and less chloride. Test methods and requirements for commercial products were established. In

  7. Durability of hydrophobic treatment of concrete

    NARCIS (Netherlands)

    Vries, J. de; Polder, R.B.; Borsje, H.

    1998-01-01

    The subject of this study was the performance of hydrophobic treatment to protect concrete against chloride penetration from de-icing salts. Hydrophobic treatment makes a concrete surface absorb less water and less chloride. Several types of tests were carried out to study the performance of

  8. Dynamics of Wetting of Ultra Hydrophobic Surfaces

    Science.gov (United States)

    Mohammad Karim, Alireza; Kim, Jeong-Hyun; Rothstein, Jonathan; Kavehpour, Pirouz; Mechanical and Industrial Engineering, University of Massachusetts, Amherst Collaboration

    2013-11-01

    Controlling the surface wettability of hydrophobic and super hydrophobic surfaces has extensive industrial applications ranging from coating, painting and printing technology and waterproof clothing to efficiency increase in power and water plants. This requires enhancing the knowledge about the dynamics of wetting on these hydrophobic surfaces. We have done experimental investigation on the dynamics of wetting on hydrophobic surfaces by looking deeply in to the dependency of the dynamic contact angles both advancing and receding on the velocity of the three-phase boundary (Solid/Liquid/Gas interface) using the Wilhelmy plate method with different ultra-hydrophobic surfaces. Several fluids with different surface tension and viscosity are used to study the effect of physical properties of liquids on the governing laws.

  9. On the use of 31P NMR for the quantification of hydrosoluble phosphorus-containing compounds in coral host tissues and cultured zooxanthellae

    Science.gov (United States)

    Godinot, Claire; Gaysinski, Marc; Thomas, Olivier P.; Ferrier-Pagès, Christine; Grover, Renaud

    2016-02-01

    31P Nuclear Magnetic Resonance (NMR) was assessed to investigate the phosphorus-containing compounds present in the tissues of the scleractinian coral Stylophora pistillata as well as of cultured zooxanthellae (CZ). Results showed that phosphorus-containing compounds observed in CZ were mainly phosphate and phosphate esters. Phosphate accounted for 19 ± 2% of the total phosphorus compounds observed in CZ maintained under low P-levels (0.02 μM). Adding 5 mM of dissolved inorganic phosphorus (KH2PO4) to the CZ culture medium led to a 3.1-fold increase in intracellular phosphate, while adding 5 mM of dissolved organic phosphorus led to a reduction in the concentration of phosphorus compounds, including a 2.5-fold intracellular phosphate decrease. In sharp contrast to zooxanthellae, the host mainly contained phosphonates, and to a lesser extent, phosphate esters and phosphate. Two-months of host starvation decreased the phosphate content by 2.4 fold, while bleaching of fed corals did not modify this content. Based on 31P NMR analyses, this study highlights the importance of phosphonates in the composition of coral host tissues, and illustrates the impact of phosphorus availability on the phosphorus composition of host tissues and CZ, both through feeding of the host and inorganic phosphorus enrichment of the CZ.

  10. Water-based adhesives with tailored hydrophobic association: dilution resistance and improved setting behavior.

    Science.gov (United States)

    Dundua, Alexander; Landfester, Katharina; Taden, Andreas

    2014-11-01

    Hydrophobic association and stimuli-responsiveness is a powerful tool towards water-based adhesives with strongly improved properties, which is demonstrated based on the example of hydrophobically modified alkali-soluble latexes (HASE) with modulated association. Their rheological properties are highly tunable due to the hydrophobic domains that act as physical crosslinking sites of adjustable interaction strength. Ethanol, propanol, and butanol are used as water-soluble model additives with different hydrophobicity in order to specifically target the association sites and impact the viscoelastic properties and stimuli-responsiveness. The rheological and mechanical property response upon dilution with water can be tailored, and dilution-resistant or even dilution-thickening systems are obtained. The investigations are of high importance for water-based adhesives, as our findings provide insight into general structure-property relationships to improve their setting behavior, especially upon contact with wet substrates. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Synthesis and characterization of lamellar aragonite with hydrophobic property

    International Nuclear Information System (INIS)

    Wang Chengyu; Xu Yang; Liu Yalan; Li Jian

    2009-01-01

    A novel and simple synthetic method for the preparation of hydrophobic lamellar aragonite has been developed. The crystallization of aragonite was conducted by the reaction of sodium carbonate with calcium chloride in the presence of sodium stearate. The resulting products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and the contact angle. The results revealed that sodium stearate plays an important role in determining the structure and morphology of the sample. Besides, we have succeeded in surface modification of particles in situ at the same time. The contact angle of the modified aragonite reached 108.59 deg.

  12. Fabrication of super-hydrophobic duo-structures

    Science.gov (United States)

    Zhang, X. Y.; Zhang, F.; Jiang, Y. J.; Wang, Y. Y.; Shi, Z. W.; Peng, C. S.

    2015-04-01

    Recently, super-hydrophobicity has attracted increasing attention due to its huge potential in the practical applications. In this paper, we have presented a duo-structure of the combination of micro-dot-matrix and nano-candle-soot. Polydimethylsiloxane (PDMS) was used as a combination layer between the dot-matrix and the soot particles. Firstly, a period of 9-μm dot-matrix was easily fabricated on the K9 glass using the most simple and mature photolithography process. Secondly, the dot-matrix surface was coated by a thin film of PDMS (elastomer: hardener=10:1) which was diluted by methylbenzene at the volume ratio of 1:8. Thirdly, we held the PDMS modified surface over a candle flame to deposit a soot layer and followed by a gentle water-risen to remove the non-adhered particles. At last, the samples were baked at 85°C for 2 hours and then the duo-structure surface with both micro-size dot-matrix and nano-size soot particles was obtained. The SEM indicated this novel surface morphology was quite like a lotus leaf of the well-know micro-nano-binary structures. As a result, the contact angle meter demonstrated such surface exhibited a perfect super-hydrophobicity with water contact angle of 153° and sliding angle of 3°. Besides, just listed as above, the fabrication process for our structure was quite more easy, smart and low-cost compared with the other production technique for super-hydrophobic surfaces such as the phase separation method, electrochemical deposition and chemical vapor deposition etc. Hence, this super-hydrophobic duo-structure reported in this letter was a great promising candidate for a wide and rapid commercialization in the future.

  13. Surface analysis of selected hydrophobic materials

    Science.gov (United States)

    Wisniewska, Sylwia Katarzyna

    This dissertation contains a series of studies on hydrophobic surfaces by various surface sensitive techniques such as contact angle measurements, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Hydrophobic surfaces have been classified as mineral surfaces, organic synthetic surfaces, or natural biological surfaces. As a model hydrophobic mineral surface, elemental sulfur has been selected. The sulfur surface has been characterized for selected allotropic forms of sulfur such as rhombic, monoclinic, plastic, and cyclohexasulfur. Additionally, dextrin adsorption at the sulfur surface was measured. The structure of a dextrin molecule showing hydrophobic sites has been presented to support the proposed hydrophobic bonding nature of dextrin adsorption at the sulfur surface. As a model organic hydrophobic surface, primary fatty amines such as dodecylamine, hexadecylamine, and octadecylamine were chosen. An increase of hydrophobicity, significant changes of infrared bands, and surface topographical changes with time were observed for each amine. Based on the results it was concluded that hydrocarbon chain rearrangement associated with recrystallization took place at the surface during contact with air. A barley straw surface was selected as a model of biological hydrophobic surfaces. The differences in the contact angles for various straw surfaces were explained by the presence of a wax layer. SEM images confirmed the heterogeneity and complexity of the wax crystal structure. AFM measurements provided additional structural details including a measure of surface roughness. Additionally, straw degradation as a result of conditioning in an aqueous environment was studied. Significant contact angle changes were observed as soon as one day after conditioning. FTIR studies showed a gradual wax layer removal due to straw surface decomposition. SEM and AFM images revealed topographical changes and biological

  14. Hydrophobic Modification of Layered Clays and Compatibility for Epoxy Nanocomposites

    Directory of Open Access Journals (Sweden)

    Jiang-Jen Lin

    2010-04-01

    Full Text Available Recent studies on the intercalation and exfoliation of layered clays with polymeric intercalating agents involving poly(oxypropylene-amines and the particular uses for epoxy nanocomposites are reviewed. For intercalation, counter-ionic exchange reactions of clays including cationic layered silicates and anionic Al-Mg layered double hydroxide (LDH with polymeric organic ions afforded organoclays led to spatial interlayer expansion from 12 to 92 Å (X-ray diffraction as well as hydrophobic property. The inorganic clays of layered structure could be modified by the poly(oxypropyleneamine-salts as the intercalating agents with molecular weights ranging from 230 to 5,000 g/mol. Furthermore, natural montmorillonite (MMT clay could be exfoliated into thin layer silicate platelets (ca. 1 nm thickness in one step by using polymeric types of exfoliating agents. Different lateral dimensions of MMT, synthetic fluorinated Mica and LDH clays had been cured into epoxy nanocomposites. The hydrophobic amine-salt modification resulting in high spacing of layered or exfoliation of individual clay platelets is the most important factor for gaining significant improvements of properties. In particular, these modified clays were reported to gain significant improvements such as reduced coefficient of thermal expansion (CTE, enhanced thermal stability, and hardness. The utilization of these layered clays for initiating the epoxy self-polymerization was also reported to have a unique compatibility between clay and organic resin matrix. However, the matrix domain lacks of covalently bonded crosslink and leads to the isolation of powder material. It is generally concluded that the hydrophobic expansion of the clay inter-gallery spacing is the crucial step for enhancing the compatibility and the ultimate preparation of the advanced epoxy materials.

  15. Hydrophobic Modification of Layered Clays and Compatibility for Epoxy Nanocomposites

    Science.gov (United States)

    Lin, Jiang-Jen; Chan, Ying-Nan; Lan, Yi-Fen

    2010-01-01

    Recent studies on the intercalation and exfoliation of layered clays with polymeric intercalating agents involving poly(oxypropylene)-amines and the particular uses for epoxy nanocomposites are reviewed. For intercalation, counter-ionic exchange reactions of clays including cationic layered silicates and anionic Al-Mg layered double hydroxide (LDH) with polymeric organic ions afforded organoclays led to spatial interlayer expansion from 12 to 92 Å (X-ray diffraction) as well as hydrophobic property. The inorganic clays of layered structure could be modified by the poly(oxypropylene)amine-salts as the intercalating agents with molecular weights ranging from 230 to 5,000 g/mol. Furthermore, natural montmorillonite (MMT) clay could be exfoliated into thin layer silicate platelets (ca. 1 nm thickness) in one step by using polymeric types of exfoliating agents. Different lateral dimensions of MMT, synthetic fluorinated Mica and LDH clays had been cured into epoxy nanocomposites. The hydrophobic amine-salt modification resulting in high spacing of layered or exfoliation of individual clay platelets is the most important factor for gaining significant improvements of properties. In particular, these modified clays were reported to gain significant improvements such as reduced coefficient of thermal expansion (CTE), enhanced thermal stability, and hardness. The utilization of these layered clays for initiating the epoxy self-polymerization was also reported to have a unique compatibility between clay and organic resin matrix. However, the matrix domain lacks of covalently bonded crosslink and leads to the isolation of powder material. It is generally concluded that the hydrophobic expansion of the clay inter-gallery spacing is the crucial step for enhancing the compatibility and the ultimate preparation of the advanced epoxy materials.

  16. Heat-resistant hydrophobic-oleophobic coatings

    OpenAIRE

    Uyanik, Mehmet; Arpac, Ertugrul; Schmidt, Helmut K.; Akarsu, Murat; Sayilkan, Funda; Sayilkan, Hikmet

    2006-01-01

    Thermally and chemically durable hydrophobic oleophobic coatings, containing different ceramic particles such as SiO2, SiC, Al 2O3, which can be alternative instead of Teflon, have been developed and applied on the aluminum substrates by spin-coating method. Polyimides, which are high-thermal resistant heteroaromatic polymers, were synthesized, and fluor oligomers were added to these polymers to obtain hydrophobic-oleophobic properties. After coating, Al surface was subjected to Taber-abrasio...

  17. Hydrophobic Materials Based on Salts of Di(2-ethylhexyl)phosphoric Acid

    Science.gov (United States)

    Kizim, N. F.; Golubina, E. N.

    2018-03-01

    Interfacial formations of material based on metals di(2-ethylhexyl)phosphates of various metals exhibit hydrophobic properties. The contact angle of the surface, modified by the interfacial formations materials, could reach up to 140° depending on the nature of the solvent, the metal salt, the number of applications.

  18. Fish skin bacteria: Colonial and cellular hydrophobicity.

    Science.gov (United States)

    Sar, N; Rosenberg, E

    1987-05-01

    Bacteria were desorbed from the skin of healthy, fast-swimming fish by several procedures, including brief exposure to sonic oscillation and treatment with nontoxic surface active agents. The surface properties of these bacteria were studied by measuring their adhesion to hexadecane, as well as by a newly developed, simple method for studying the hydrophobicity of bacterial lawns. This method, referred to as the "Direction of Spreading" (DOS) method, consists of recording the direction to which a water drop spreads when introduced at the border between bacterial lawns and other surfaces. Of the 13 fish skin isolates examined, two strains were as hydrophobic as polystyrene by the DOS method. Suspended cells of one of these strains adhered strongly to hexadecane (84%), whereas cells of the other strain adhered poorly (13%). Another strain which was almost as hydrophobic as polystyrene by the DOS method did not adhere to hexadecane at all. Similarly, lawns of three other strains were more hydrophobic than glass by the DOS method, but cell suspensions prepared from these colonies showed little or no adhesion to hexadecane. The high colonial but relatively low cellular hydrophobicity could be due to a hydrophobic slime that is removed during the suspension and washing procedures. The possibility that specific bacteria assist in fish locomotion by changing the surface properties of the fish skin and by producing drag-reducing polymers is discussed.

  19. Drag reduction in reservoir rock surface: Hydrophobic modification by SiO{sub 2} nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Yong-Li, E-mail: yylhill@163.com [College of Chemistry & Chemical Engineering, Xi’an Shiyou University, Xi’an 710065 (China); Cui, Ming-Yue; Jiang, Wei-Dong; He, An-Le; Liang, Chong [Langfang Branch of Research Institute of Petroleum Exploration & Development, Langfang 065007 (China)

    2017-02-28

    Graphical abstract: The micro-nanoscale hierarchical structures at the sandstone core surface are constructed by adsorption of the modified silica nanoparticles, which leads to the effect of drag reduction to improve the low injection rate in ultra-low permeability reservoirs. - Highlights: • A micro-nanoscale hierarchical structure is formed at the reservoir rock surface. • An inversion has happened from hydrophilic into hydrophobic modified by nanofluids. • The effect of drag reduction to improve the low injection rate is realized. • The mechanism of drag reduction induced from the modified core surface was unclosed. - Abstract: Based on the adsorption behavior of modified silica nanoparticles in the sandstone core surface, the hydrophobic surface was constructed, which consists of micro-nanoscale hierarchical structure. This modified core surface presents a property of drag reduction and meets the challenge of high injection pressure and low injection rate in low or ultra-low permeability reservoir. The modification effects on the surface of silica nanoparticles and reservoir cores, mainly concerning hydrophobicity and fine structure, were determined by measurements of contact angle and scanning electron microscopy. Experimental results indicate that after successful modification, the contact angle of silica nanoparticles varies from 19.5° to 141.7°, exhibiting remarkable hydrophobic properties. These modified hydrophobic silica nanoparticles display a good adsorption behavior at the core surface to form micro-nanobinary structure. As for the wettability of these modified core surfaces, a reversal has happened from hydrophilic into hydrophobic and its contact angle increases from 59.1° to 105.9°. The core displacement experiments show that the relative permeability for water has significantly increased by an average of 40.3% via core surface modification, with the effects of reducing injection pressure and improving injection performance of water

  20. Drag reduction in reservoir rock surface: Hydrophobic modification by SiO_2 nanofluids

    International Nuclear Information System (INIS)

    Yan, Yong-Li; Cui, Ming-Yue; Jiang, Wei-Dong; He, An-Le; Liang, Chong

    2017-01-01

    Graphical abstract: The micro-nanoscale hierarchical structures at the sandstone core surface are constructed by adsorption of the modified silica nanoparticles, which leads to the effect of drag reduction to improve the low injection rate in ultra-low permeability reservoirs. - Highlights: • A micro-nanoscale hierarchical structure is formed at the reservoir rock surface. • An inversion has happened from hydrophilic into hydrophobic modified by nanofluids. • The effect of drag reduction to improve the low injection rate is realized. • The mechanism of drag reduction induced from the modified core surface was unclosed. - Abstract: Based on the adsorption behavior of modified silica nanoparticles in the sandstone core surface, the hydrophobic surface was constructed, which consists of micro-nanoscale hierarchical structure. This modified core surface presents a property of drag reduction and meets the challenge of high injection pressure and low injection rate in low or ultra-low permeability reservoir. The modification effects on the surface of silica nanoparticles and reservoir cores, mainly concerning hydrophobicity and fine structure, were determined by measurements of contact angle and scanning electron microscopy. Experimental results indicate that after successful modification, the contact angle of silica nanoparticles varies from 19.5° to 141.7°, exhibiting remarkable hydrophobic properties. These modified hydrophobic silica nanoparticles display a good adsorption behavior at the core surface to form micro-nanobinary structure. As for the wettability of these modified core surfaces, a reversal has happened from hydrophilic into hydrophobic and its contact angle increases from 59.1° to 105.9°. The core displacement experiments show that the relative permeability for water has significantly increased by an average of 40.3% via core surface modification, with the effects of reducing injection pressure and improving injection performance of water

  1. Computational models for structure-hydrophobicity relationships of 4-carboxyl-2,6-dinitrophenyl azo hydroxynaphthalenes.

    Science.gov (United States)

    Idowu, Olakunle S; Adegoke, Olajire A; Idowu, Abiola; Olaniyi, Ajibola A

    2007-01-01

    Some phenyl azo hydroxynaphthalene dyes (e.g., sunset yellow) are certified as approved colorants for food, cosmetics, and drug formulations. The hydrophobicity of 4 newly synthesized azo dyes of the phenyl azo hydroxynaphthalene class was investigated, as a training set, with the goal of developing models for quantitative structure-property relationships (QSPR). Retention behavior of the molecules reversed-phase thin-layer chromatography (RPTLC) was investigated using liquid paraffin-coated silica gel as the stationary phase. Mobile phases consisted of aqueous mixtures of methanol, acetone, and dimethylformamide (DMF). Basic hydrophobicity parameter (Rmw), specific hydrophobic surface area (S), and isocratic chromatographic hydrophobicity index (phio) were computed from the chromatographic data. The hydrophobicity index (Rm) decreased linearly with increasing concentration of organic modifiers. Extrapolated Rmw values obtained by using DMF and acetone differ significantly from the value obtained by using methanol as organic modifier [P dyes and may also play useful roles in computer-assisted molecular discovery of nontoxic azo dyes.

  2. Bio-inspired hydrophobic modification of cellulose nanocrystals with castor oil.

    Science.gov (United States)

    Shang, Qianqian; Liu, Chengguo; Hu, Yun; Jia, Puyou; Hu, Lihong; Zhou, Yonghong

    2018-07-01

    This work presents an efficient and environmentally friendly approach to generate hydrophobic cellulose nanocrystals (CNC) using thiol-containing castor oil (CO-SH) as a renewable hydrophobe with the assist of bio-inspired dopamine at room temperature. The modification process included the formation of the polydopamine (PDA) buffer layer on CNC surfaces and the Michael addition reaction between the catechol moieties of PDA coating and thiol groups of CO-SH. The morphology, crystalline structure, surface chemistry, thermal stability and hydrophobicity of the modified CNC were charactered by TEM, XRD, FT-IR, solid-state 13 C NMR, XPS, TGA and contact angle analysis. The modified CNC preserved cellulose crystallinity, displayed higher thermal stability than unmodified CNC, and was highly hydrophobic with a water contact angle of 95.6°. The simplicity and versatility of the surface modification strategy inspired by adhesive protein of mussel may promote rapid development of hydrophobic bio-based nanomaterials for various applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Pathways to dewetting in hydrophobic confinement.

    Science.gov (United States)

    Remsing, Richard C; Xi, Erte; Vembanur, Srivathsan; Sharma, Sumit; Debenedetti, Pablo G; Garde, Shekhar; Patel, Amish J

    2015-07-07

    Liquid water can become metastable with respect to its vapor in hydrophobic confinement. The resulting dewetting transitions are often impeded by large kinetic barriers. According to macroscopic theory, such barriers arise from the free energy required to nucleate a critical vapor tube that spans the region between two hydrophobic surfaces--tubes with smaller radii collapse, whereas larger ones grow to dry the entire confined region. Using extensive molecular simulations of water between two nanoscopic hydrophobic surfaces, in conjunction with advanced sampling techniques, here we show that for intersurface separations that thermodynamically favor dewetting, the barrier to dewetting does not correspond to the formation of a (classical) critical vapor tube. Instead, it corresponds to an abrupt transition from an isolated cavity adjacent to one of the confining surfaces to a gap-spanning vapor tube that is already larger than the critical vapor tube anticipated by macroscopic theory. Correspondingly, the barrier to dewetting is also smaller than the classical expectation. We show that the peculiar nature of water density fluctuations adjacent to extended hydrophobic surfaces--namely, the enhanced likelihood of observing low-density fluctuations relative to Gaussian statistics--facilitates this nonclassical behavior. By stabilizing isolated cavities relative to vapor tubes, enhanced water density fluctuations thus stabilize novel pathways, which circumvent the classical barriers and offer diminished resistance to dewetting. Our results thus suggest a key role for fluctuations in speeding up the kinetics of numerous phenomena ranging from Cassie-Wenzel transitions on superhydrophobic surfaces, to hydrophobically driven biomolecular folding and assembly.

  4. Evaporation rate of water in hydrophobic confinement.

    Science.gov (United States)

    Sharma, Sumit; Debenedetti, Pablo G

    2012-03-20

    The drying of hydrophobic cavities is believed to play an important role in biophysical phenomena such as the folding of globular proteins, the opening and closing of ligand-gated ion channels, and ligand binding to hydrophobic pockets. We use forward flux sampling, a molecular simulation technique, to compute the rate of capillary evaporation of water confined between two hydrophobic surfaces separated by nanoscopic gaps, as a function of gap, surface size, and temperature. Over the range of conditions investigated (gaps between 9 and 14 Å and surface areas between 1 and 9 nm(2)), the free energy barrier to evaporation scales linearly with the gap between hydrophobic surfaces, suggesting that line tension makes the predominant contribution to the free energy barrier. The exponential dependence of the evaporation rate on the gap between confining surfaces causes a 10 order-of-magnitude decrease in the rate when the gap increases from 9 to 14 Å. The computed free energy barriers are of the order of 50 kT and are predominantly enthalpic. Evaporation rates per unit area are found to be two orders of magnitude faster in confinement by the larger (9 nm(2)) than by the smaller (1 nm(2)) surfaces considered here, at otherwise identical conditions. We show that this rate enhancement is a consequence of the dependence of hydrophobic hydration on the size of solvated objects. For sufficiently large surfaces, the critical nucleus for the evaporation process is a gap-spanning vapor tube.

  5. Addressing brain tumors with targeted gold nanoparticles: a new gold standard for hydrophobic drug delivery?

    Science.gov (United States)

    Cheng, Yu; Meyers, Joseph D; Agnes, Richard S; Doane, Tennyson L; Kenney, Malcolm E; Broome, Ann-Marie; Burda, Clemens; Basilion, James P

    2011-08-22

    EGF-modified Au NP-Pc 4 conjugates showed 10-fold improved selectivity to the brain tumor compared to untargeted conjugates. The hydrophobic photodynamic therapy drug Pc 4 can be delivered efficiently into glioma brain tumors by EGF peptide-targeted Au NPs. Compared to the untargeted conjugates, EGF-Au NP-Pc 4 conjugates showed 10-fold improved selectivity to the brain tumor. This delivery system holds promise for future delivery of a wider range of hydrophobic therapeutic drugs for the treatment of hard-to-reach cancers. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Controllable picoliter pipetting using hydrophobic microfluidic valves

    Science.gov (United States)

    Zhang, M.; Huang, J.; Qian, X.; Mi, S.; Wang, X.

    2017-06-01

    A picoliter pipetting technique using the microfluidic method is presented. Utilizing the hydrophobic self-assembled monolayer films patterned in microchannels as pressure-controlled valves, a small volume of liquid can be separated by a designed channel trap and then ejected from the channel end at a higher pressure. The liquid trap section is composed of a T-shaped channel junction and a hydrophobic patch. The liquid volume can be precisely controlled by varying the distance of the hydrophobic patch from the T-junction. By this means, liquid less than 100 pl can be separated and pipetted. The developed device is potentially useful for sample dispensing in biological, medical, and chemical applications.

  7. Biosurfactant-enhanced bioremediation of hydrophobic pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Cameotra, S.S.; Makkar, R.S. [Inst. of Microbial Technology, Chandigarh (India)

    2010-01-15

    Biosurfactants are surface-active compounds synthesized by a wide variety of microorganisms. They are molecules that have both hydrophobic and - philic domains and are capable of lowering the surface tension and the interfacial tension of the growth medium. Biosurfactants possess different chemical structures-lipopeptides, glycolipids, neutral lipids, and fatty acids. They are nontoxic biomolecules that are biodegradable. Biosurfactants also exhibit strong emulsification of hydrophobic compounds and form stable emulsions. Polycyclic aromatic hydrocarbons (PAHs), crude on sludge, and pesticides call be toxic, mutagenic, and carcinogenic compounds that pollute the environment. They are released into the environment as a result of oil spillage and by-products of coal treatment processes. The low water solubility of these compounds limits their availability to microorganisms, which is a potential problem for bioremediation of contaminated sites. Microbially produced surfactants enhance the bioavailability of these hydrophobic compounds for bioremediation. Therefore, biosurfactant-enhanced solubility of pollutants has potential hioremediation applications.

  8. Towards understanding hydrophobic recovery of plasma treated polymers: Storing in high polarity liquids suppresses hydrophobic recovery

    International Nuclear Information System (INIS)

    Bormashenko, Edward; Chaniel, Gilad; Grynyov, Roman

    2013-01-01

    The phenomenon of hydrophobic recovery was studied for cold air plasma treated polyethylene films. Plasma-treated polymer films were immersed into liquids with very different polarities such as ethanol, acetone, carbon tetrachloride, benzene and carbon disulphide. Hydrophobic recovery was studied by measurement of contact angles. Immersion into high polarity liquids slows markedly the hydrophobic recovery. We relate this slowing to dipole–dipole interaction of polar groups of the polymer with those of the liquids. This kind of interaction becomes decisive when polar groups of polymer chains are at least partially spatially fixed.

  9. Structuring unbreakable hydrophobic barriers in paper

    Science.gov (United States)

    Nargang, Tobias M.; Kotz, Frederik; Rapp, Bastian E.

    2018-02-01

    Hydrophobic barriers are one of the key elements of microfluidic paper based analytical devices (μPADs).μPADs are simple and cost efficient and they can be carried out without the need of high standard laboratories. To carry out such a test a method is needed to create stable hydrophobic barriers. Commonly used methods like printing wax or polystyrene have the major drawback that these barriers are stiff and break if bended which means they will no longer be able to retain a liquid sample. Here we present silanes to structure hydrophobic barriers via polycondensation and show a silanization method which combines the advantages of flexible silane/siloxane layers with the short processing times of UV-light based structuring. The barriers are created by using methoxy silanes which are mixed with a photo acid generator (PAG) as photoinitiator. Also a photosensitizer was given to the mixture to increase the effectiveness of the PAG. After the PAG is activated by UV-light the silane is hydrolyzed and coupled to the cellulose via polycondensation. The created hydrophobic barriers are highly stable and do not break if being bended.

  10. A method for detecting hydrophobic patches protein

    NARCIS (Netherlands)

    Lijnzaad, P.; Berendsen, H.J.C.; Argos, P.

    1996-01-01

    A method for the detection of hydrophobic patches on the surfaces of protein tertiary structures is presented, it delineates explicit contiguous pieces of surface of arbitrary size and shape that consist solely of carbon and sulphur atoms using a dot representation of the solvent-accessible surface,

  11. Hydrophobicity measurements of microfiltration and ultrafiltration membranes.

    NARCIS (Netherlands)

    Keurentjes, J.T.F.; Harbrecht, J.G.; Brinkman, D.; Hanemaaijer, J.H.; Cohen Stuart, M.A.; Riet, van 't K.

    1989-01-01

    A method for the determination of the hydrophobicity of membrane materials is developed. The advantage of this method over existing methods is that it is not influenced by the presence of the pores. A piece of the membrane material is submerged horizontally in a liquid with surface tension L.

  12. The new view of hydrophobic free energy.

    Science.gov (United States)

    Baldwin, Robert L

    2013-04-17

    In the new view, hydrophobic free energy is measured by the work of solute transfer of hydrocarbon gases from vapor to aqueous solution. Reasons are given for believing that older values, measured by solute transfer from a reference solvent to water, are not quantitatively correct. The hydrophobic free energy from gas-liquid transfer is the sum of two opposing quantities, the cavity work (unfavorable) and the solute-solvent interaction energy (favorable). Values of the interaction energy have been found by simulation for linear alkanes and are used here to find the cavity work, which scales linearly with molar volume, not accessible surface area. The hydrophobic free energy is the dominant factor driving folding as judged by the heat capacity change for transfer, which agrees with values for solvating hydrocarbon gases. There is an apparent conflict with earlier values of hydrophobic free energy from studies of large-to-small mutations and an explanation is given. Copyright © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  13. Efficacy of Hydrophobic Coatings in Protecting Oak Wood Surfaces during Accelerated Weathering

    Directory of Open Access Journals (Sweden)

    Miloš Pánek

    2017-10-01

    Full Text Available The durability of transparent coatings applied to an oak wood exterior is relatively low due to its anatomic structure and chemical composition. Enhancement of the protection of oak wood against weathering using transparent hydrophobic coatings is presented in this study. Oak wood surfaces were modified using UV-stabilizers, hindered amine light stabilizer (HALS, and ZnO and TiO2 nanoparticles before the application of a commercial hydrophobic topcoat. A transparent oil-based coating was used as a control coating system. The artificial weathering test lasted 6 weeks and colour, gloss, and contact angle changes were regularly evaluated during this period. The changes in the microscopic structure were studied with confocal laser scanning microscopy. The results proved limited durability against weathering of both tested hydrophobic coatings. The formation of micro-cracks causing the leaching of degraded wood compounds and discolouration of oak wood were observed after 1 or 3 weeks of the weathering test. Until then, an oil-based coating film had protected the wood sufficiently, but after 6 weeks the wood was fully defoliated to its non-homogenous thickness, which was caused by the presence of large oak vessels, and by the effects of specific oak tannins. Using transparent hydrophobic coatings can prolong the service life of the exteriors of wood products by decreasing their moisture content. Without proper construction protection against rainwater, the hydrophobic coating itself cannot guarantee the preservation of the natural appearance of wood exteriors.

  14. Preparing hydrophobic nanocellulose-silica film by a facile one-pot method.

    Science.gov (United States)

    Le, Duy; Kongparakul, Suwadee; Samart, Chanatip; Phanthong, Patchiya; Karnjanakom, Surachai; Abudula, Abuliti; Guan, Guoqing

    2016-11-20

    Hydrophobic nanocellulose-silica film was successfully prepared by a facile one-pot method using tetraethoxysilane (TEOS) and dodecyl triethoxylsilane (DTES). Morphological characterization of the hydrophobic nanocellulose-silica (NC-SiO2-DTES) film showed well self-assembled DTES modified silica spherical nanoparticles with the particle sizes in the range of 88-126nm over the nanocellulose film. The hydrophobicity of the NC-SiO2-DTES film was achieved owing to the improvement of roughness of the nanocellulose film by coating dodecyl- terminated silica nanoparticles. An increase in DTES loading amount and reaction time increased the hydrophobicity of the film, and the optimum condition for NC-SiO2-DTES film preparation was achieved at DTES/TEOS molar ratio of 2.0 for 8h reaction time. Besides, the NC-SiO2-DTES film performed superoleophilic property with octane and hexadecane contact angles of 0°. It also showed an excellent hydrophobic property over all pH values ranged from 1 to 14. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Modification of Deeply Buried Hydrophobic Interfaces by Ionic Surfactants

    Energy Technology Data Exchange (ETDEWEB)

    L Tamam; D Pontoni Z Sapir; S Yefet; S Sloutskin; B Ocko; H Reichert; M Deutsch

    2011-12-31

    Hydrophobicity, the spontaneous segregation of oil and water, can be modified by surfactants. The way this modification occurs is studied at the oil-water interface for a range of alkanes and two ionic surfactants. A liquid interfacial monolayer, consisting of a mixture of alkane molecules and surfactant tails, is found. Upon cooling, it freezes at T{sub s}, well above the alkane's bulk freezing temperature, T{sub b}. The monolayer's phase diagram, derived by surface tensiometry, is accounted for by a mixtures-based theory. The monolayer's structure is measured by high-energy X-ray reflectivity above and below T{sub s}. A solid-solid transition in the frozen monolayer, occurring approximately 3 C below T{sub s}, is discovered and tentatively suggested to be a rotator-to-crystal transition.

  16. Transforming plastic surfaces with electrophilic backbones from hydrophobic to hydrophilic.

    Science.gov (United States)

    Kim, Samuel; Bowen, Raffick A R; Zare, Richard N

    2015-01-28

    We demonstrate a simple nonaqueous reaction scheme for transforming the surface of plastics from hydrophobic to hydrophilic. The chemical modification is achieved by base-catalyzed trans-esterification with polyols. It is permanent, does not release contaminants, and causes no optical or mechanical distortion of the plastic. We present contact angle measurements to show successful modification of several types of plastics including poly(ethylene terephthalate) (PET) and polycarbonate (PC). Its applicability to blood analysis is explored using chemically modified PET blood collection tubes and found to be quite satisfactory. We expect this approach will reduce the cost of manufacturing plastic devices with optimized wettability and can be generalized to other types of plastic materials having an electrophilic linkage as its backbone.

  17. Studies on polyurethane adhesives and surface modification of hydrophobic substrates

    Science.gov (United States)

    Krishnamoorthy, Jayaraman

    studies involved making functionalized, thickness-controlled, wettability-controlled multilayers on hydrophobic substrates and the adsorption of carboxylic acid-terminated poly(styrene-b-isoprene) on alumina/silica substrates. Poly(vinyl alcohol) has been shown to adsorb onto hydrophobic surfaces irreversibly due to hydrophobic interactions. This thin semicrystalline coating is chemically modified using acid chlorides, butyl isocyanate and butanal to form thicker and hydrophobic coatings. The products of the modification reactions allow adsorption of a subsequent layer of poly(vinyl alcohol) that could subsequently be hydrophobized. This 2-step (adsorption/chemical modification) allows layer-by-layer deposition to prepare coatings with thickness, chemical structure and wettability control on any hydrophobic surface. Research on adsorption characteristics of carboxylic acid-terminated poly(styrene-b-isoprene) involved syntheses of block copolymers with the functional group present at specific ends. Comparative adsorption studies for carboxylic acid-terminated and hydrogen-terminated block copolymers was carried out on alumina and silica substrates.

  18. Surface modification of coconut shell based activated carbon for the improvement of hydrophobic VOC removal.

    Science.gov (United States)

    Li, Lin; Liu, Suqin; Liu, Junxin

    2011-08-30

    In this study, coconut shell based carbons were chemically treated by ammonia, sodium hydroxide, nitric acid, sulphuric acid, and phosphoric acid to determine suitable modification for improving adsorption ability of hydrophobic volatile organic compounds (VOCs) on granular activated carbons (GAC). The saturated adsorption capacities of o-xylene, a hydrophobic volatile organic compound, were measured and adsorption effects of the original and modified activated carbons were compared. Results showed that GAC modified by alkalis had better o-xylene adsorption capacity. Uptake amount was enhanced by 26.5% and reduced by 21.6% after modification by NH(3)H(2)O and H(2)SO(4), respectively. Compared with the original, GAC modified by acid had less adsorption capacity. Both SEM/EDAX and BET were used to identify the structural characteristics of the tested GAC, while IR spectroscopy and Boehm's titration were applied to analysis the surface functional groups. Relationships between physicochemical characteristics of GAC and their adsorption performances demonstrated that o-xylene adsorption capacity was related to surface area, pore volume, and functional groups of the GAC surface. Removing surface oxygen groups, which constitute the source of surface acidity, and reducing hydrophilic carbon surface favors adsorption capacity of hydrophobic VOCs on carbons. The performances of modified GACs were also investigated in the purification of gases containing complex components (o-xylene and steam) in the stream. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. Development of new additive for drilling fluid from the partial hydrophobization N,N,N-trimethyl chitosan (TMC)

    International Nuclear Information System (INIS)

    Carmo, Thacyla C. do; Lopes, Grazielle; Silva, Joaquim F.M. da; Nascimento, Regina S.V.

    2009-01-01

    N,N,N-trimethyl chitosan (TMC) hydrophobically modified can act as an excellent additive for drilling fluids water based, working as inhibitor of reactive shales and rheological modifiers. The cationic chitosan was obtained by reaction of chitosan with CH 3 I in N-methyl-2-pyrrolidone to obtain the TMC and chitosan was also hydrophobically modified with palmitoil chloride to get Quit P. Through another route, Quit P was modified to obtain the cationic TMCP. The derivatives were characterized by FT-IR and 1 HNMR spectrophotometry allowing the calculation of the degree of quaternization of the TMC. The rheology tests showed that the system with TMCP presented pseudo plastic behavior, while the system with TMC behaved as a Newtonian fluid. The results indicated that TMCP can act as rheology modifier for water-based drilling fluids. (author)

  20. Adsorption of hydrophobic organic compounds onto a hydrophobic carbonaceous geosorbent in the presence of surfactants.

    Science.gov (United States)

    Wang, Peng; Keller, Arturo A

    2008-06-01

    The adsorption of hydrophobic organic compounds (HOCs; atrazine and diuron) onto lampblack was studied in the presence of nonionic, cationic, and anionic surfactants (Triton(R) X-100), benzalkonium chloride [BC], and linear alkylbenzene sulfonate [LAS]) to determine the effect of the surfactant on HOC adsorption onto a hydrophobic carbonaceous geosorbent. Linear alkylbenzene sulfonate showed an adsorption capacity higher than that of BC but similar to that of Triton X-100, implying the charge property of a surfactant is not a useful indicator for predicting the surfactant's adsorption onto a hydrophobic medium. The results also indicated that the octanol-water partition coefficient (K(OW)) of a surfactant is not a good predictor of that surfactant's sorption onto a hydrophobic medium. Under subsaturation adsorption conditions (i.e., before sorption saturation is reached), surfactant adsorption reduced HOC adsorption to a significant extent, with the reduction in HOC adsorption increasing monotonically with the amount of surfactant adsorbed. Among the three surfactants, Triton X-100 was the most effective in reducing HOC adsorption, whereas BC and LAS showed similar effectiveness in this regard. Under the same amount of the surfactant sorbed, the reduction in atrazine adsorption was consistently greater than that for diuron because of atrazine's lower hydrophobicity. No significant difference was observed in the amount of the HOC adsorbed under different adsorption sequences. Our results showed that the presence of surfactant can significantly decrease HOC adsorption onto hydrophobic environmental media and, thus, is important in predicting HOC fate and transport in the environment.

  1. Hydrophobicity-induced drying transition in alkanethiol self ...

    Indian Academy of Sciences (India)

    Raman Research Institute, C.V. Raman Avenue, Bangalore 560 080, India ... Hydrophobicity; hydrophobic gap; self-assembled monolayer; length scale dependent .... From our work, we find that when the alkanethiol SAM is prepared from a.

  2. Fabrication of semi-transparent super-hydrophobic surface based on silica hierarchical structures

    KAUST Repository

    Chen, Ping-Hei

    2011-01-01

    This study successfully develops a versatile method of producing superhydrophobic surfaces with micro/nano-silica hierarchical structures on glass surfaces. Optically transparent super hydrophobic silica thin films were prepared by spin-coating silica particles suspended in a precursor solution of silane, ethanol, and H2O with molar ratio of 1:4:4. The resulting super hydrophobic films were characterized by scanning electron microscopy (SEM), optical transmission, and contact angle measurements. The glass substrates in this study were modified with different particles: micro-silica particles, nano-silica particles, and hierarchical structures. This study includes SEM micrographs of the modified glass surfaces with hierarchical structures at different magnifications. © 2011 The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.

  3. Single Molecule Sensors to Study Hydrophobic Phenomena

    OpenAIRE

    Geisler, Michael

    2010-01-01

    The nature and magnitude of the hydrophobic interaction is crucial for many technical and biological processes. In the current study a molecular probe was developed which consists of a single polymer that is bound onto the tip of an AFM cantilever in order to study these effects on the molecular scale. In the following, equilibrium forces are measured and factors of influence such as temperature, cosolvents and chemical composition are varied. Thereby, the system under investigation is so sma...

  4. Influence of Hydrophobicity on Polyelectrolyte Complexation

    Energy Technology Data Exchange (ETDEWEB)

    Sadman, Kazi [Department; amp, Engineering, Northwestern University, Evanston, Illinois 60208, United States; Wang, Qifeng [Department; amp, Engineering, Northwestern University, Evanston, Illinois 60208, United States; Chen, Yaoyao [Department; amp, Engineering, Northwestern University, Evanston, Illinois 60208, United States; Keshavarz, Bavand [Department; Jiang, Zhang [X-ray; Shull, Kenneth R. [Department; amp, Engineering, Northwestern University, Evanston, Illinois 60208, United States

    2017-11-16

    Polyelectrolyte complexes are a fascinating class of soft materials that can span the full spectrum of mechanical properties from low viscosity fluids to glassy solids. This spectrum can be accessed by modulating the extent of electrostatic association in these complexes. However, to realize the full potential of polyelectrolyte complexes as functional materials their molecular level details need to be clearly correlated with their mechanical response. The present work demonstrates that by making simple amendments to the chain architecture it is possible to affect the salt responsiveness of polyelectrolyte complexes in a systematic manner. This is achieved by quaternizing poly(4-vinylpyridine) (QVP) with methyl, ethyl and propyl substituents– thereby increasing the hydrophobicity with increasing side chain length– and complexing them with a common anionic polyelectrolyte, poly(styrene sulfonate). The mechanical 1 ACS Paragon Plus Environment behavior of these complexes is compared to the more hydrophilic system of poly(styrene sulfonate) and poly(diallyldimethylammonium) by quantifying the swelling behavior in response to salt stimuli. More hydrophobic complexes are found to be more resistant to doping by salt, yet the mechanical properties of the complex remain contingent on the overall swelling ratio of the complex itself, following near universal swelling-modulus master curves that are quantified in this work. The rheological behavior of QVP complex coacervates are found to be approximately the same, only requiring higher salt concentrations to overcome strong hydrophobic interactions, demonstrating that hydrophobicity can be used as an important parameter for tuning the stability of polyelectrolyte complexes in general, while still preserving the ability to be processed “saloplastically”.

  5. Hydrophobic treatment of concrete as protection against chloride penetration

    NARCIS (Netherlands)

    Vries, J. de; Polder, R.B.; Borsje, H.

    1996-01-01

    Hydrophobic treatment makes a concrete surface absorb less water and less chloride. Hydrophobic treatment was studied as a protection agninst chloride penetration from deicing salts. Test methods were designed. Nine hydrophobic products were tested, of which three complied to the requirements on

  6. Adsorption of dextrin on hydrophobic minerals.

    Science.gov (United States)

    Beaussart, Audrey; Mierczynska-Vasilev, Agnieszka; Beattie, David A

    2009-09-01

    The adsorption of dextrin on talc, molybdenite, and graphite (three naturally hydrophobic minerals) has been compared. Adsorption isotherms and in situ tapping mode atomic force microscope (TMAFM) imaging have enabled polymer adsorbed amount and morphology of the adsorbed layer (area coverage and polymer domain size) to be determined and also the amount of hydration water in the structure of the adsorbed layer. The effect of the polymer on the mineral contact angles, measured by the captive bubble method on cleaved mineral surfaces, indicates clear correlations between the hydrophobicity reduction of the minerals, the adsorbed amount, and the surface coverage of the adsorbed polymer. Predictions of the flotation recovery of the treated mineral phases have been confirmed by performing batch flotation experiments. The influence of the polymer surface coverage on flotation recovery has highlighted the importance of this key parameter in the predictions of depressant efficiency. The roles of the initial hydrophobicity and the surface structure of the mineral basal plane in determining adsorption parameters and flotation response of the polymer-treated minerals are also discussed.

  7. Poly thiophene hydrophobic and hydrophilic compounds, silver and iodine synthesized by plasma

    International Nuclear Information System (INIS)

    Palacios, J.C.; Chavez, J.A.; Olayo, M.G.; Cruz, G.J.

    2007-01-01

    Compounds in thin films of poly thiophene with silver and poly thiophene doped with iodine and silver using splendor discharges were synthesized. It is studied the wettability of the compounds and its transport properties. It was found that the compounds can modify their hydrophilic to hydrophobic behavior controlling their surface ruggedness and the metallic content. The doped with iodine plays a fundamental paper in the modification of the ruggedness of the compounds. (Author)

  8. The association of low-molecular-weight hydrophobic compounds with native casein micelles in bovine milk.

    Science.gov (United States)

    Cheema, M; Mohan, M S; Campagna, S R; Jurat-Fuentes, J L; Harte, F M

    2015-08-01

    The agreed biological function of the casein micelles in milk is to carry minerals (calcium, magnesium, and phosphorus) from mother to young along with amino acids for growth and development. Recently, native and modified casein micelles were used as encapsulating and delivery agents for various hydrophobic low-molecular-weight probes. The ability of modified casein micelles to bind certain probes may derive from the binding affinity of native casein micelles. Hence, a study with milk from single cows was conducted to further elucidate the association of hydrophobic molecules into native casein micelles and further understand their biological function. Hydrophobic and hydrophilic extraction followed by ultraperformance liquid chromatography-high resolution mass spectrometry analysis were performed over protein fractions obtained from size exclusion fractionation of raw skim milk. Hydrophobic compounds, including phosphatidylcholine, lyso-phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin, showed strong association exclusively to casein micelles as compared with whey proteins, whereas hydrophilic compounds did not display any preference for their association among milk proteins. Further analysis using liquid chromatography-tandem mass spectrometry detected 42 compounds associated solely with the casein-micelles fraction. Mass fragments in tandem mass spectrometry identified 4 of these compounds as phosphatidylcholine with fatty acid composition of 16:0/18:1, 14:0/16:0, 16:0/16:0, and 18:1/18:0. These results support that transporting low-molecular-weight hydrophobic molecules is also a biological function of the casein micelles in milk. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  9. Dewetting and Hydrophobic Interaction in Physical and Biological Systems

    Science.gov (United States)

    Berne, Bruce J.; Weeks, John D.; Zhou, Ruhong

    2013-01-01

    Hydrophobicity manifests itself differently on large and small length scales. This review focuses on large length scale hydrophobicity, particularly on dewetting at single hydrophobic surfaces and drying in regions bounded on two or more sides by hydrophobic surfaces. We review applicable theories, simulations and experiments pertaining to large scale hydrophobicity in physical and biomoleclar systems and clarify some of the critical issues pertaining to this subject. Given space constraints, we could not review all of the significant and interesting work in this very active field. PMID:18928403

  10. Polymer-surfactant interactions studied by titration microcalorimetry : Influence of polymer hydrophobicity, electrostatic forces, and surfactant aggregational state

    NARCIS (Netherlands)

    Kevelam, J; van Breemen, J.F.L.; Blokzijl, W.; Engberts, J.B.F.N.

    1996-01-01

    Isothermal titration microcalorimetry has been applied to investigate the interactions between hydrophobically-modified water-soluble polymers and surfactants. The following polymers were used in this study: poly(sodium acrylate-co-n-alkyl methacrylate) (A), where n-alkyl = C9H19, C12H25, and C18H37

  11. Evaluation of hydrophobicity in PAH-contaminated soils during phytoremediation

    International Nuclear Information System (INIS)

    Cofield, Naressa; Banks, M. Katherine; Schwab, A. Paul

    2007-01-01

    The impact of recalcitrant organic compounds on soil hydrophobicity was evaluated in contaminated soil from a manufactured gas plant site following 12 months of phytoremediation. Significant reduction in soil wetting and water retention was observed in contaminated soil compared to an uncontaminated control. Phytoremediation was effective at reducing total PAHs by 69% with corresponding changes in soil classification from extremely hydrophobic (initial sample) to moderately-strongly hydrophobic (planted) and hydrophilic-very hydrophilic (unplanted) after 12 months. The greatest reduction in soil hydrophobicity was observed in the unplanted, unfertilized treatments that had the lowest removal rate of PAHs. The presence of plants may contribute to hydrophobicity in contaminated soil. - The presence of recalcitrant hydrophobic organic pollutants may enhance soil hydrophobicity

  12. Ultrathin Hydrophobic Coatings Obtained on Polyethylene Terephthalate Materials in Supercritical Carbon Dioxide with Co-Solvents

    Science.gov (United States)

    Kumeeva, T. Yu.; Prorokova, N. P.

    2018-02-01

    The surface properties of ultradisperse polytetrafluoroethylene coatings on polyethylene terephthalate materials modified in a supercritical carbon dioxide medium with co-solvent additions (aliphatic alcohols) were analyzed. An atomic force microscopy study revealed the peculiarities of the morphology of the hydrophobic coatings formed in the presence of co-solvents. The contribution of the co-solvents to the formation of the surface layer with a low surface energy was evaluated from the surface energy components of the modified polyester material. The stability of the coatings against dry friction was analyzed.

  13. The hydrophobic effect: Molecular dynamics simulations of water confined between extended hydrophobic and hydrophilic surfaces

    DEFF Research Database (Denmark)

    Jensen, Morten Østergaard; Mouritsen, Ole G.; Peters, Günther H.J.

    2004-01-01

    Structural and dynamic properties of water confined between two parallel, extended, either hydrophobic or hydrophilic crystalline surfaces of n-alkane C36H74 or n-alcohol C35H71OH, are studied by molecular dynamics simulations. Electron density profiles, directly compared with corresponding......-correlation functions reveal that water molecules have characteristic diffusive behavior and orientational ordering due to the lack of hydrogen bonding interactions with the surface. These observations suggest that the altered dynamical properties of water in contact with extended hydrophobic surfaces together...... at both surfaces. The ordering is characteristically different between the surfaces and of longer range at the hydrophilic surface. Furthermore, the dynamic properties of water are different at the two surfaces and different from the bulk behavior. In particular, at the hydrophobic surface, time...

  14. Modelling oral up-take of hydrophobic and super-hydrophobic chemicals in fish.

    Science.gov (United States)

    Larisch, Wolfgang; Goss, Kai-Uwe

    2018-01-24

    We have extended a recently published toxicokinetic model for fish (TK-fish) towards the oral up-take of contaminants. Validation with hydrophobic chemicals revealed that diffusive transport through aqueous boundary layers in the gastro-intestinal tract and in the blood is the limiting process. This process can only be modelled correctly if facilitated transport by albumin or bile micelles through these boundary layers is accounted for. In a case study we have investigated the up-take of a super hydrophobic chemical, Dechlorane Plus. Our results suggest that there is no indication of a hydrophobicity or size cut-off in the bioconcentration of this chemical. Based on an extremely high, but mechanistically sound facilitation factor we received model results in good agreement with experimental values from the literature. The results also indicate that established experimental procedures for BCF determination cannot cover the very slow up-take and clearance kinetics that are to be expected for such a chemical.

  15. Diameter-dependent hydrophobicity in carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Kyakuno, Haruka, E-mail: h-kyakuno@kanagawa-u.ac.jp [Department of Physics, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji 192-0397 (Japan); Institute of Physics, Faculty of Engineering, Kanagawa University, Yokohama 221-8686 (Japan); Fukasawa, Mamoru; Ichimura, Ryota; Nakai, Yusuke; Maniwa, Yutaka, E-mail: maniwa@phys.se.tmu.ac.jp [Department of Physics, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji 192-0397 (Japan); Matsuda, Kazuyuki [Institute of Physics, Faculty of Engineering, Kanagawa University, Yokohama 221-8686 (Japan); Miyata, Yasumitsu [Department of Physics, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji 192-0397 (Japan); PRESTO, JST, Kawaguchi 332-0012 (Japan); Saito, Takeshi [Nanotube Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565 (Japan)

    2016-08-14

    Single-wall carbon nanotubes (SWCNTs) are a good model system that provides atomically smooth nanocavities. It has been reported that water-SWCNTs exhibit hydrophobicity depending on the temperature T and the SWCNT diameter D. SWCNTs adsorb water molecules spontaneously in their cylindrical pores around room temperature, whereas they exhibit a hydrophilic-hydrophobic transition or wet-dry transition (WDT) at a critical temperature T{sub wd} ≈ 220-230 K and above a critical diameter D{sub c} ≈ 1.4-1.6 nm. However, details of the WDT phenomenon and its mechanism remain unknown. Here, we report a systematic experimental study involving X-ray diffraction, optical microscopy, and differential scanning calorimetry. It is found that water molecules inside thick SWCNTs (D > D{sub c}) evaporate and condense into ice Ih outside the SWCNTs at T{sub wd} upon cooling, and the ice Ih evaporates and condenses inside the SWCNTs upon heating. On the other hand, residual water trapped inside the SWCNTs below T{sub wd} freezes. Molecular dynamics simulations indicate that upon lowering T, the hydrophobicity of thick SWCNTs increases without any structural transition, while the water inside thin SWCNTs (D < D{sub c}) exhibits a structural transition, forming an ordered ice. This ice has a well-developed hydrogen bonding network adapting to the cylindrical pores of the SWCNTs. Thus, the unusual diameter dependence of the WDT is attributed to the adaptability of the structure of water to the pore dimension and shape.

  16. Achieving enhanced hydrophobicity of graphene membranes by covalent modification with polydimethylsiloxane

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Wei-Wei; Li, Hang [College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065 (China); Shi, Ling-Ying, E-mail: shilingying@scu.edu.cn [College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065 (China); Diao, Yong-Fu; Zhang, Yu-Lin; Ran, Rong [College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065 (China); Ni, Wei, E-mail: niwei@iccas.ac.cn [Institute of Chemical Materials, China Academy of Engineering Physics, Chengdu 610200 (China)

    2017-05-15

    Highlights: • The graphene oxide (GO) was covalently modified by amino terminated polydimethylsiloxane (PDMS) through amidation reaction. • Through the vacuum filtration method, the GO, RGO and PDMS-modified graphene membranes were successfully prepared respectively. • The morphology of membranes had smooth surface and well-stacked structure indicated by SEM and EDS mapping results. • The contact angle of GO-g-PDMS membrane was high to be 129.5° indicating a great enhancement of hydrophobicity. - Abstract: In this study, the graphene oxide was covalently modified by amino terminated polydimethylsiloxane (PDMS) through amidation reaction. And the membranes of the graphene oxide (GO), reduced graphene oxide (RGO) and PDMS-covalently modified graphene were prepared respectively by a vacuum filtration method, and the wettability of these membranes were investigated. Infrared spectroscopy, Raman, X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetry analysis combined with dispersion ability indicated that PDMS chains were successfully grafted on the surface of graphene oxide sheets. The morphology of the prepared membranes had smooth surface and well-stacked structure in the cross-section indicated by the scanning electron microscope and EDS-mapping. The contact angle measurements indicated that the PDMS-modified graphene membrane with water contact angle 129.5° showed increased hydrophobicity compared with GO and RGO membranes.

  17. Fabrication and tribological properties of super-hydrophobic surfaces based on porous silicon

    International Nuclear Information System (INIS)

    Liu, Y.H.; Wang, X.K.; Luo, J.B.; Lu, X.C.

    2009-01-01

    In the present work, super-hydrophobic surfaces based on porous silicon (PS) were constructed by the self-assembled molecular films and their tribological properties were investigated. A simple chemical etching approach was developed to fabricate PS with the certain rough microstructure surface, which can be observed by the environmental scanning electron microscopy (ESEM). The hydrocarbon and fluorocarbon alkylsilane molecular films were self-assembled on PS, which was confirmed by the X-ray photoelectron spectroscopy (XPS) measurement. In contrast to PS, the alkylsilane molecular films modified PS (mPS) were super-hydrophobic since the apparent water contact angle (CA) exceeded 160 deg. The tribological properties of PS and the mPS were investigated by a ball-on-disk tribometer during the processes of different sliding velocities and normal loads. The experimental results showed that the alkylsilane molecular films could decrease the friction coefficient. Due to the difference of chain structure and functional groups, the fluorinated alkylsilane films are better candidates for improving the hydrophobicity and lubricating characteristics of PS comparing to the non-fluorinated ones. The carbon chain length of alkylsilane molecules self-assembling on the Si or PS substrates could have little effects on the hydrophobic properties and the tribology performances.

  18. Atmospheric pressure plasma polymerization of 1,3-butadiene for hydrophobic finishing of textile substrates

    International Nuclear Information System (INIS)

    Samanta, Kartick K; Jassal, Manjeet; Agrawal, Ashwini K

    2010-01-01

    Atmospheric pressure plasma processing of textile has both ecological and economical advantages over the wet-chemical processing. However, reaction in atmospheric pressure plasma has important challenges to be overcome before it can be successfully used for finishing applications in textile. These challenges are (i) generating stable glow plasma in presence liquid/gaseous monomer, and (ii) keeping the generated radicals active in the presence of contaminants such as oxygen and air. In this study, a stable glow plasma was generated at atmospheric pressure in the mixture of gaseous reactive monomer-1,3-butadiene and He and was made to react with cellulosic textile substrate. After 12 min of plasma treatment, the hydrophilic surface of the cellulosic substrate turned into highly hydrophobic surface. The hydrophobic finish was found to be durable to soap washing. After soap washing, a water drop of 37 μl took around 250 s to get absorbed in the treated sample compared to 0 . Both top and bottom sides of the fabric showed similar hydrophobic results in terms of water absorbency and contact angle. The results may be attributed to chemical reaction of butadiene with the cellulosic textile substrate. The surface characterization of the plasma modified samples under SEM and AFM revealed modification of the surface under <100 nm. The results showed that atmospheric pressure plasma can be successfully used for carrying out reaction of 1,3-butadiene with cellulosic textile substrates for producing hydrophobic surface finish.

  19. Influence of the Hydrophobicity of Polyelectrolytes on Polyelectrolyte Complex Formation and Complex Particle Structure and Shape

    Directory of Open Access Journals (Sweden)

    Gudrun Petzold

    2011-08-01

    Full Text Available Polyelectrolyte complexes (PECs were prepared by structural uniform and strongly charged cationic and anionic modified alternating maleic anhydride copolymers. The hydrophobicity of the polyelectrolytes was changed by the comonomers (ethylene, isobutylene and styrene. Additionally, the n−/n+ ratio of the molar charges of the polyelectrolytes and the procedure of formation were varied. The colloidal stability of the systems and the size, shape, and structure of the PEC particles were investigated by turbidimetry, dynamic light scattering (DLS and atomic force microscopy (AFM. Dynamic light scattering indicates that beside large PEC particle aggregates distinct smaller particles were formed by the copolymers which have the highest hydrophobicity (styrene. These findings could be proved by AFM. Fractal dimension (D, root mean square (RMS roughness and the surface profiles of the PEC particles adsorbed on mica allow the following conclusions: the higher the hydrophobicity of the polyelectrolytes, the broader is the particle size distribution and the minor is the swelling of the PEC particles. Hence, the most compact particles are formed with the very hydrophobic copolymer.

  20. Effect of whey goat milk kefir on hydrophobicity of E. coli O157:H7, S. typhi bacteria and C. albicans

    Directory of Open Access Journals (Sweden)

    Dedi Fardiaz

    2012-03-01

    Full Text Available The hydrophobicity of bacteria. was determined using BATH (Bacteria adhesion to hydrocarbon test. All bacteria showed that 0,9 ml n-octane exposure gave a positive response and indicating that E. coli O157:H7 was categorized as moderate hydrophobic bacteria,  while S.  typhi  and C. albicans were catagorized as  highly hydrophobic bacteria. Goat Milk Kefir increased hydrophobicity of E.  coli O157:H7 by 24.40, however, decreased hydrophobicity of S. typhi by 47.56  and C. albicans by 70.14 percent, respectively. This finding showed that one of the inhibition mechanism may be caused by  an interaction  of  organic acid and peptide  compounds with cell membrane, in which hydrophobic sites of component  modified the hydrophobicity of the bacteria cell surface. The hydrophobicity modification in bacterial  cell wall might result inhibition of adhetion bacteria at cell host. Key words : Enterophatogenic bacteria, hidrophobisitas bacteria

  1. Hydrophobic Calcium Carbonate for Cement Surface

    Directory of Open Access Journals (Sweden)

    Shashi B. Atla

    2017-12-01

    Full Text Available This report describes a novel way to generate a highly effective hydrophobic cement surface via a carbonation route using sodium stearate. Carbonation reaction was carried out at different temperatures to investigate the hydrophobicity and morphology of the calcium carbonate formed with this process. With increasing temperatures, the particles changed from irregular shapes to more uniform rod-like structures and then aggregated to form a plate-like formation. The contact angle against water was found to increase with increasing temperature; after 90 °C there was no further increase. The maximum contact angle of 129° was obtained at the temperature of 60 °C. It was also found that carbonation increased the micro hardness of the cement material. The micro hardness was found to be dependent on the morphology of the CaCO3 particles. The rod like structures which caused increased mineral filler produced a material with enhanced strength. The 13C cross polarization magic-angle spinning NMR spectra gave plausible explanation of the interaction of organic-inorganic moieties.

  2. The effect of enhancing the hydrophobicity of OMMT on the characteristics of PMMA/OMMT nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Yamagata, Shuichi, E-mail: shuic@den.hokudai.ac.jp [Department of Orthodontics, Graduate School of Dental Medicine, Hokkaido University, Kita 13 Nishi 7, Kita-ku, Sapporo 060-8586 (Japan); Hamba, Yusuke [Department of Orthodontics, Graduate School of Dental Medicine, Hokkaido University, Kita 13 Nishi 7, Kita-ku, Sapporo 060-8586 (Japan); Akasaka, Tsukasa [Department of Biomedical Materials and Engineering, Graduate School of Dental Medicine, Hokkaido University, Kita 13 Nishi 7, Kita-ku, Sapporo 060-8586 (Japan); Ushijima, Natsumi [Support Section for Education and Research, Graduate School of Dental Medicine, Hokkaido University, Kita 13 Nishi 7, Kita-ku, Sapporo 060-8586 (Japan); Uo, Motohiro [Advanced Biomaterials, Department of Restorative Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8549 (Japan); Iida, Junichiro [Department of Orthodontics, Graduate School of Dental Medicine, Hokkaido University, Kita 13 Nishi 7, Kita-ku, Sapporo 060-8586 (Japan); Watari, Fumio [Department of Biomedical Materials and Engineering, Graduate School of Dental Medicine, Hokkaido University, Kita 13 Nishi 7, Kita-ku, Sapporo 060-8586 (Japan)

    2012-12-01

    Highlights: Black-Right-Pointing-Pointer PMMA/OMMT nanocomposites were fabricated using a solution intercalation method. Black-Right-Pointing-Pointer The silicate platelets were largely well dispersed independent of the hydrophobicity. Black-Right-Pointing-Pointer The partially exfoliation of the silicate layers were observed. Black-Right-Pointing-Pointer The flexural modulus of the nanocomposites increased favorably. Black-Right-Pointing-Pointer The strain at breakage of the nanocomposites remained suitable for our use. - Abstract: Transparent poly(methyl methacrylate)/organically modified montmorillonite (PMMA/OMMT) nanocomposites were fabricated using a solution intercalation method. Two grades of OMMT modified with quaternary alkylammonium ions and containing different amounts of organic matter, NZ70 and NX, were used. X-ray diffraction patterns showed that the peaks regarded as a (0 0 1) d-spacing and a second peak were shifted toward lower 2{theta} values, implying the expansion or the partial exfoliation of the silicate layers, respectively. TEM images showed that the silicate platelets were largely well dispersed independent of the hydrophobicity, although some aggregates were observed. The flexural modulus of the PMMA/OMMT nanocomposites increased favorably with an increasing amount of OMMT of either grade. However, only the NX displayed comparable strain at breakage to that of the PMMA. These results suggest that the highly hydrophobic grade NX shows great promise for use in nanocomposites made via solution intercalation.

  3. The effect of enhancing the hydrophobicity of OMMT on the characteristics of PMMA/OMMT nanocomposites

    International Nuclear Information System (INIS)

    Yamagata, Shuichi; Hamba, Yusuke; Akasaka, Tsukasa; Ushijima, Natsumi; Uo, Motohiro; Iida, Junichiro; Watari, Fumio

    2012-01-01

    Highlights: ► PMMA/OMMT nanocomposites were fabricated using a solution intercalation method. ► The silicate platelets were largely well dispersed independent of the hydrophobicity. ► The partially exfoliation of the silicate layers were observed. ► The flexural modulus of the nanocomposites increased favorably. ► The strain at breakage of the nanocomposites remained suitable for our use. - Abstract: Transparent poly(methyl methacrylate)/organically modified montmorillonite (PMMA/OMMT) nanocomposites were fabricated using a solution intercalation method. Two grades of OMMT modified with quaternary alkylammonium ions and containing different amounts of organic matter, NZ70 and NX, were used. X-ray diffraction patterns showed that the peaks regarded as a (0 0 1) d-spacing and a second peak were shifted toward lower 2θ values, implying the expansion or the partial exfoliation of the silicate layers, respectively. TEM images showed that the silicate platelets were largely well dispersed independent of the hydrophobicity, although some aggregates were observed. The flexural modulus of the PMMA/OMMT nanocomposites increased favorably with an increasing amount of OMMT of either grade. However, only the NX displayed comparable strain at breakage to that of the PMMA. These results suggest that the highly hydrophobic grade NX shows great promise for use in nanocomposites made via solution intercalation.

  4. Hydrophobic ZnO-TiO2 Nanocomposite with Photocatalytic Promoting Self-Cleaning Surface

    Directory of Open Access Journals (Sweden)

    Qiang Wei

    2015-01-01

    Full Text Available The hydrophobicity and self-cleaning are the important influence factors on the precision and environment resistance of quartz crystal microbalance (QCM in detecting organic gas molecules. In this paper, ZnO nanorod array is prepared via the in situ method on the QCM coated with Au film via hydrothermal process. ZnO nanorod array film on QCM is modified by β-CD in hydrothermal process and then decorated by TiO2 after being impregnated in P25 suspension. The results show that as-prepared ZnO-TiO2 nanocomposite exhibits excellent hydrophobicity for water molecules and superior self-cleaning property for organic molecules under UV irradiation.

  5. Hydrophobic duck feathers and their simulation on textile substrates for water repellent treatment

    International Nuclear Information System (INIS)

    Liu Yuyang; Chen Xianqiong; Xin, J H

    2008-01-01

    Inspired by the non-wetting phenomena of duck feathers, the water repellent property of duck feathers was studied at the nanoscale. The microstructures of the duck feather were investigated by a scanning electron microscope (SEM) imaging method through a step-by-step magnifying procedure. The SEM results show that duck feathers have a multi-scale structure and that this multi-scale structure as well as the preening oil are responsible for their super hydrophobic behavior. The microstructures of the duck feather were simulated on textile substrates using the biopolymer chitosan as building blocks through a novel surface solution precipitation (SSP) method, and then the textile substrates were further modified with a silicone compound to achieve low surface energy. The resultant textiles exhibit super water repellent properties, thus providing a simple bionic way to create super hydrophobic surfaces on soft substrates using flexible material as building blocks

  6. Increasing the Performance of Vacuum Membrane Distillation Using Micro-Structured Hydrophobic Aluminum Hollow Fiber Membranes

    Directory of Open Access Journals (Sweden)

    Chia-Chieh Ko

    2017-04-01

    Full Text Available This study develops a micro-structured hydrophobic alumina hollow fiber with a high permeate flux of 60 Lm−2h−1 and salt rejection over 99.9% in a vacuum membrane distillation process. The fiber is fabricated by phase inversion and sintering, and then modified with fluoroalkylsilanes to render it hydrophobic. The influence of the sintering temperature and feeding temperature in membrane distillation (MD on the characteristics of the fiber and MD performance are investigated. The vacuum membrane distillation uses 3.5 wt % NaCl aqueous solution at 70 °C at 0.03 bar. The permeate flux of 60 Lm−2h−1 is the highest, compared with reported data and is higher than that for polymeric hollow fiber membranes.

  7. Hydrophobically associating polymers for oil field applications

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, K.C. [Taylor Industrial Research Inc., Victoria, BC (Canada); Nasr-El-Din, H.A. [Saudi Aramco, Dharhan (Saudi Arabia). R and D Center

    2007-07-01

    This paper discussed developments in water soluble hydrophobically associating polymers and their use in oilfield applications. The polymers are now being investigated for the potential application in enhanced oil recovery (EOR) as well as in completion fluids and profile modifications. The polymers are also purported to selectively reduce water permeability in sandstones. This study showed that the adsorption behaviour of the associating polymers is of greater significance than the rheology, particularly in non-damaging completion fluids and in profile modification. Issues related to acid diversion and conformance control applications were discussed, and drag reducing agents were reviewed. The study also discussed drilling and completion fluids; adsorption behaviour; rheology; and synthesis and characterization. It was concluded that gels are now being developed for conformance control and continued use for modification of water relative permeability. 35 refs., 5 figs.

  8. Hydrophobicity and charge shape cellular metabolite concentrations.

    Directory of Open Access Journals (Sweden)

    Arren Bar-Even

    2011-10-01

    Full Text Available What governs the concentrations of metabolites within living cells? Beyond specific metabolic and enzymatic considerations, are there global trends that affect their values? We hypothesize that the physico-chemical properties of metabolites considerably affect their in-vivo concentrations. The recently achieved experimental capability to measure the concentrations of many metabolites simultaneously has made the testing of this hypothesis possible. Here, we analyze such recently available data sets of metabolite concentrations within E. coli, S. cerevisiae, B. subtilis and human. Overall, these data sets encompass more than twenty conditions, each containing dozens (28-108 of simultaneously measured metabolites. We test for correlations with various physico-chemical properties and find that the number of charged atoms, non-polar surface area, lipophilicity and solubility consistently correlate with concentration. In most data sets, a change in one of these properties elicits a ~100 fold increase in metabolite concentrations. We find that the non-polar surface area and number of charged atoms account for almost half of the variation in concentrations in the most reliable and comprehensive data set. Analyzing specific groups of metabolites, such as amino-acids or phosphorylated nucleotides, reveals even a higher dependence of concentration on hydrophobicity. We suggest that these findings can be explained by evolutionary constraints imposed on metabolite concentrations and discuss possible selective pressures that can account for them. These include the reduction of solute leakage through the lipid membrane, avoidance of deleterious aggregates and reduction of non-specific hydrophobic binding. By highlighting the global constraints imposed on metabolic pathways, future research could shed light onto aspects of biochemical evolution and the chemical constraints that bound metabolic engineering efforts.

  9. Influence of hydrophobic modification in alginate-based hydrogels for biomedical applications

    Science.gov (United States)

    Choudhary, Soumitra

    Alginate has been exploited commercially for decades in foods, textiles, paper, pharmaceutical industries, and also as a detoxifier for removing heavy metals. Alginate is also popular in cell encapsulation because of its relatively mild gelation protocol and simple chemistry with which biological active entities can be immobilized. Surface modification of alginate gels has been explored to induce desired cell interactions with the gel matrix. These modifications alter the bulk properties, which strongly determine on how cells feel and response to the three-dimensional microenvironment. However, there is a need to develop strategies to engineer functionalities into bulk alginate hydrogels that not only preserve their inherent qualities but are also less toxic. In this thesis, our main focus was to optimize the mechanical properties of alginate-based hydrogels, and by doing so control the performance of the biomaterials. In the first scheme, we used alginate and hydrophobically modified ethyl hydroxy ethyl cellulose as components in interpenetrating polymer network (IPN) gels. The second network was used to control gelation time and rheological properties. We believe these experiments also may provide insight into the mechanical and structural properties of more complex biopolymer gels and naturally-occurring IPNs. Next, we worked on incorporating a hydrophobic moiety directly into the alginate chain, resulting in materials for extended release of hydrophobic drugs. We successfully synthesized hydrophobically modified alginate (HMA) by attaching octylamine groups onto the alginate backbone by standard carbodiimide based amide coupling reaction. Solubility of several model hydrophobic drugs in dilute HMA solutions was found to be increased by more than an order of magnitude. HMA hydrogels, prepared by crosslinking the alginate chains with calcium ions, were found to exhibit excellent mechanical properties (modulus ˜100 kPa) with release extended upto 5 days. Ability

  10. Atmospheric pressure plasma polymerization of 1,3-butadiene for hydrophobic finishing of textile substrates

    Energy Technology Data Exchange (ETDEWEB)

    Samanta, Kartick K; Jassal, Manjeet; Agrawal, Ashwini K, E-mail: ashwini@smita-iitd.co, E-mail: manjeet.jassal@smita-iitd.co [Smart and Innovative Textile Materials Group (SMITA), Department of Textile Technology, Indian Institute of Technology, Hauz Khas, New Delhi-110016 (India)

    2010-02-01

    Atmospheric pressure plasma processing of textile has both ecological and economical advantages over the wet-chemical processing. However, reaction in atmospheric pressure plasma has important challenges to be overcome before it can be successfully used for finishing applications in textile. These challenges are (i) generating stable glow plasma in presence liquid/gaseous monomer, and (ii) keeping the generated radicals active in the presence of contaminants such as oxygen and air. In this study, a stable glow plasma was generated at atmospheric pressure in the mixture of gaseous reactive monomer-1,3-butadiene and He and was made to react with cellulosic textile substrate. After 12 min of plasma treatment, the hydrophilic surface of the cellulosic substrate turned into highly hydrophobic surface. The hydrophobic finish was found to be durable to soap washing. After soap washing, a water drop of 37 {mu}l took around 250 s to get absorbed in the treated sample compared to < 1 s in the untreated samples. The plasma modified samples showed water contact angle of around 134{sup 0}. Both top and bottom sides of the fabric showed similar hydrophobic results in terms of water absorbency and contact angle. The results may be attributed to chemical reaction of butadiene with the cellulosic textile substrate. The surface characterization of the plasma modified samples under SEM and AFM revealed modification of the surface under <100 nm. The results showed that atmospheric pressure plasma can be successfully used for carrying out reaction of 1,3-butadiene with cellulosic textile substrates for producing hydrophobic surface finish.

  11. Biodegradable modified Phba systems

    International Nuclear Information System (INIS)

    Aniscenko, L.; Dzenis, M.; Erkske, D.; Tupureina, V.; Savenkova, L.; Muizniece - Braslava, S.

    2004-01-01

    Compositions as well as production technology of ecologically sound biodegradable multicomponent polymer systems were developed. Our objective was to design some bio plastic based composites with required mechanical properties and biodegradability intended for use as biodegradable packaging. Significant characteristics required for food packaging such as barrier properties (water and oxygen permeability) and influence of γ-radiation on the structure and changes of main characteristics of some modified PHB matrices was evaluated. It was found that barrier properties were plasticizers chemical nature and sterilization with γ-radiation dependent and were comparable with corresponding values of typical polymeric packaging films. Low γ-radiation levels (25 kGy) can be recommended as an effective sterilization method of PHB based packaging materials. Purposely designed bio plastic packaging may provide an alternative to traditional synthetic packaging materials without reducing the comfort of the end-user due to specific qualities of PHB - biodegradability, Biocompatibility and hydrophobic nature

  12. Hydrophobic deep eutectic solvents as water-immiscible extractants

    NARCIS (Netherlands)

    Osch, van D.J.G.P.; Zubeir, L.F.; Bruinhorst, van den A.; Alves da Rocha, M.A.; Kroon, M.C.

    2015-01-01

    Hydrophobic deep eutectic solvents (DESs) are presented for the first time. They consist of decanoic acid and various quaternary ammonium salts. The effect of the alkyl chains on the hydrophobicity and the equilibrium of the two-phase DES–water system were investigated. These new DESs were

  13. Micro- and nanoscale characterization of hydrophobic and hydrophilic leaf surfaces

    International Nuclear Information System (INIS)

    Bhushan, Bharat; Jung, Yong Chae

    2006-01-01

    Superhydrophobic surfaces as well as low adhesion and friction are desirable for various industrial applications. Certain plant leaves are known to be hydrophobic in nature due to their roughness and the presence of a thin wax film on the surface of the leaf. The purpose of this study is to fully characterize the leaf surfaces on the micro- and nanoscale while separating out the effects of the micro- and the nanobumps of hydrophobic leaves on the hydrophobicity. Hydrophilic leaves were also studied to better understand the role of wax and roughness. Furthermore, the adhesion and friction properties of hydrophobic and hydrophilic leaves were studied. Using an optical profiler and an atomic/friction force microscope (AFM/FFM), measurements were made to fully characterize the leaf surfaces. It is shown that the nanobumps play a more important role than the microbumps in the hydrophobic nature as well as friction of the leaf. This study will be useful in developing superhydrophobic surfaces

  14. Prediction of Hydrophobic Cores of Proteins Using Wavelet Analysis.

    Science.gov (United States)

    Hirakawa; Kuhara

    1997-01-01

    Information concerning the secondary structures, flexibility, epitope and hydrophobic regions of amino acid sequences can be extracted by assigning physicochemical indices to each amino acid residue, and information on structure can be derived using the sliding window averaging technique, which is in wide use for smoothing out raw functions. Wavelet analysis has shown great potential and applicability in many fields, such as astronomy, radar, earthquake prediction, and signal or image processing. This approach is efficient for removing noise from various functions. Here we employed wavelet analysis to smooth out a plot assigned to a hydrophobicity index for amino acid sequences. We then used the resulting function to predict hydrophobic cores in globular proteins. We calculated the prediction accuracy for the hydrophobic cores of 88 representative set of proteins. Use of wavelet analysis made feasible the prediction of hydrophobic cores at 6.13% greater accuracy than the sliding window averaging technique.

  15. Modified cyanobacteria

    Science.gov (United States)

    Vermaas, Willem F J.

    2014-06-17

    Disclosed is a modified photoautotrophic bacterium comprising genes of interest that are modified in terms of their expression and/or coding region sequence, wherein modification of the genes of interest increases production of a desired product in the bacterium relative to the amount of the desired product production in a photoautotrophic bacterium that is not modified with respect to the genes of interest.

  16. Permeable reactive barrier of surface hydrophobic granular activated carbon coupled with elemental iron for the removal of 2,4-dichlorophenol in water

    Energy Technology Data Exchange (ETDEWEB)

    Yang Ji, E-mail: yangji@ecust.edu.cn [School of Resources and Environmental Engineering, State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200237 (China); Cao Limei; Guo Rui; Jia Jinping [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2010-12-15

    Granular activated carbon was modified with dimethyl dichlorosilane to improve its surface hydrophobicity, and therefore to improve the performance of permeable reactive barrier constructed with the modified granular activated carbon and elemental iron. X-ray photoelectron spectroscopy shows that the surface silicon concentration of the modified granular activated carbon is higher than that of the original one, leading to the increased surface hydrophobicity. Although the specific surface area decreased from 895 to 835 m{sup 2} g{sup -1}, the modified granular activated carbon could adsorb 20% more 2,4-dichlorophenol than the original one did in water. It is also proven that the permeable reactive barrier with the modified granular activated carbon is more efficient at 2,4-dichlorophenol dechlorination, in which process 2,4-dichlorophenol is transformed to 2-chlorophenol or 4-chlorophenol then to phenol, or to phenol directly.

  17. Permeable reactive barrier of surface hydrophobic granular activated carbon coupled with elemental iron for the removal of 2,4-dichlorophenol in water

    International Nuclear Information System (INIS)

    Yang Ji; Cao Limei; Guo Rui; Jia Jinping

    2010-01-01

    Granular activated carbon was modified with dimethyl dichlorosilane to improve its surface hydrophobicity, and therefore to improve the performance of permeable reactive barrier constructed with the modified granular activated carbon and elemental iron. X-ray photoelectron spectroscopy shows that the surface silicon concentration of the modified granular activated carbon is higher than that of the original one, leading to the increased surface hydrophobicity. Although the specific surface area decreased from 895 to 835 m 2 g -1 , the modified granular activated carbon could adsorb 20% more 2,4-dichlorophenol than the original one did in water. It is also proven that the permeable reactive barrier with the modified granular activated carbon is more efficient at 2,4-dichlorophenol dechlorination, in which process 2,4-dichlorophenol is transformed to 2-chlorophenol or 4-chlorophenol then to phenol, or to phenol directly.

  18. Permeable reactive barrier of surface hydrophobic granular activated carbon coupled with elemental iron for the removal of 2,4-dichlorophenol in water.

    Science.gov (United States)

    Yang, Ji; Cao, Limei; Guo, Rui; Jia, Jinping

    2010-12-15

    Granular activated carbon was modified with dimethyl dichlorosilane to improve its surface hydrophobicity, and therefore to improve the performance of permeable reactive barrier constructed with the modified granular activated carbon and elemental iron. X-ray photoelectron spectroscopy shows that the surface silicon concentration of the modified granular activated carbon is higher than that of the original one, leading to the increased surface hydrophobicity. Although the specific surface area decreased from 895 to 835 m(2)g(-1), the modified granular activated carbon could adsorb 20% more 2,4-dichlorophenol than the original one did in water. It is also proven that the permeable reactive barrier with the modified granular activated carbon is more efficient at 2,4-dichlorophenol dechlorination, in which process 2,4-dichlorophenol is transformed to 2-chlorophenol or 4-chlorophenol then to phenol, or to phenol directly. Copyright © 2010 Elsevier B.V. All rights reserved.

  19. Targeting of the hydrophobic metabolome by pathogens.

    Science.gov (United States)

    Helms, J Bernd; Kaloyanova, Dora V; Strating, Jeroen R P; van Hellemond, Jaap J; van der Schaar, Hilde M; Tielens, Aloysius G M; van Kuppeveld, Frank J M; Brouwers, Jos F

    2015-05-01

    The hydrophobic molecules of the metabolome - also named the lipidome - constitute a major part of the entire metabolome. Novel technologies show the existence of a staggering number of individual lipid species, the biological functions of which are, with the exception of only a few lipid species, unknown. Much can be learned from pathogens that have evolved to take advantage of the complexity of the lipidome to escape the immune system of the host organism and to allow their survival and replication. Different types of pathogens target different lipids as shown in interaction maps, allowing visualization of differences between different types of pathogens. Bacterial and viral pathogens target predominantly structural and signaling lipids to alter the cellular phenotype of the host cell. Fungal and parasitic pathogens have complex lipidomes themselves and target predominantly the release of polyunsaturated fatty acids from the host cell lipidome, resulting in the generation of eicosanoids by either the host cell or the pathogen. Thus, whereas viruses and bacteria induce predominantly alterations in lipid metabolites at the host cell level, eukaryotic pathogens focus on interference with lipid metabolites affecting systemic inflammatory reactions that are part of the immune system. A better understanding of the interplay between host-pathogen interactions will not only help elucidate the fundamental role of lipid species in cellular physiology, but will also aid in the generation of novel therapeutic drugs. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. Solubilization of Hydrophobic Dyes in Surfactant Solutions

    Directory of Open Access Journals (Sweden)

    Ali Reza Tehrani-Bagha

    2013-02-01

    Full Text Available In this paper, the use of surfactants for solubilization of hydrophobic organic dyes (mainly solvent and disperse dyes has been reviewed. The effect of parameters such as the chemical structures of the surfactant and the dye, addition of salt and of polyelectrolytes, pH, and temperature on dye solubilization has been discussed. Surfactant self-assemble into micelles in aqueous solution and below the concentration where this occurs—the critical micelle concentration (CMC—there is no solubilization. Above the CMC, the amount of solubilized dye increases linearly with the increase in surfactant concentration. It is demonstrated that different surfactants work best for different dyes. In general, nonionic surfactants have higher solubilization power than anionic and cationic surfactants. It is likely that the reason for the good performance of nonionic surfactants is that they allow dyes to be accommodated not only in the inner, hydrocarbon part of the micelle but also in the headgroup shell. It is demonstrated that the location of a dye in a surfactant micelle can be assessed from the absorption spectrum of the dye-containing micellar solution.

  1. Dropwise condensation on hydrophobic bumps and dimples

    Science.gov (United States)

    Yao, Yuehan; Aizenberg, Joanna; Park, Kyoo-Chul

    2018-04-01

    Surface topography plays an important role in promoting or suppressing localized condensation. In this work, we study the growth of water droplets on hydrophobic convex surface textures such as bumps and concave surface textures such as dimples with a millimeter scale radius of curvature. We analyze the spatio-temporal droplet size distribution under a supersaturation condition created by keeping the uniform surface temperature below the dew point and show its relationship with the sign and magnitude of the surface curvature. In particular, in contrast to the well-known capillary condensation effect, we report an unexpectedly less favorable condensation on smaller, millimeter-scale dimples where the capillary condensation effect is negligible. To explain these experimental results, we numerically calculated the diffusion flux of water vapor around the surface textures, showing that its magnitude is higher on bumps and lower on dimples compared to a flat surface. We envision that our understanding of millimetric surface topography can be applied to improve the energy efficiency of condensation in applications such as water harvesting, heating, ventilation, and air conditioning systems for buildings and transportation, heat exchangers, thermal desalination plants, and fuel processing systems.

  2. Robust hydrophobic polyurethane fibrous membranes with tunable porous structure for waterproof and breathable application

    Science.gov (United States)

    Gu, Jiatai; Gu, Haihong; Cao, Jin; Chen, Shaojie; Li, Ni; Xiong, Jie

    2018-05-01

    In this work, novel nanofibrous membranes with waterproof and breathable (W&B) performance were successfully fabricated by the combination of electrospinning and surface modification technology. This fibrous membranes consisted of polyurethane (PU), NaCl, and fluoroalkylsilane (FAS). Firstly, The fibrous construction and porous structure of fibrous membranes were regulated by tuning the NaCl concentrations in PU solutions. Then, the obtained PU/NaCl fibrous membranes were further modified with fluoroalkylsilane (FAS) to improve hydrophobic property. The synergistic effect of porous structure and hydrophobicity on waterproof and breathable performance was investigated. Furthermore, the mechanical property of fibrous membranes was deeply analysed on the basis of macromolecule orientation and adhesive structure. Benefiting from the optimized porous structure and hydrophobic modification, the resultant fibrous membranes exhibited excellent waterproof (hydrostatic pressure of 1261 Mbar), breathable (water vapor transmission (WVT) rate of 9.06 kg m-2 d-1 and air permeability of 4.8 mm s-1) performance, as well as high tensile strength (breakage stress of 10.4 MPa), suggesting a promising candidate for various applications, especially in protective clothing.

  3. Highly lipophilic pluronics-conjugated polyamidoamine dendrimer nanocarriers as potential delivery system for hydrophobic drugs

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Thi Tram Chau [Institute of Research and Development, Duy Tan University, Da Nang City 550000 (Viet Nam); Department of Chemical Engineering, Industrial University of HCMC, HCMC 70000 (Viet Nam); Nguyen, Cuu Khoa, E-mail: nckhoavnn@yahoo.com [Department of Materials and Pharmaceutical Chemistry, Vietnam Academy of Science and Technology, HCMC 70000 (Viet Nam); Nguyen, Thi Hiep [Biomedical Engineering Department, International University, National Universities in HCMC, HCMC 70000 (Viet Nam); Tran, Ngoc Quyen, E-mail: tnquyen@iams.vast.vn [Institute of Research and Development, Duy Tan University, Da Nang City 550000 (Viet Nam); Department of Materials and Pharmaceutical Chemistry, Vietnam Academy of Science and Technology, HCMC 70000 (Viet Nam)

    2017-01-01

    In the study, four kinds of pluronics (P123, F68, F127 and F108) with varying hydrophilic-lipophilic balance (HLB) values were modified and conjugated on 4th generation of polyamidoamine dendrimer (PAMAM). The obtained results from FT-IR, {sup 1}H NMR and GPC showed that the pluronics effectively conjugated on the dendrimer. The molecular weight of four PAMAM G4.0-Pluronics and its morphologies are in range of 200.15–377.14 kDa and around 60–180 nm in diameter by TEM, respectively. Loading efficiency and release of hydrophobic fluorouracil (5-FU) anticancer drug were evaluated by HPLC; Interesting that the dendrimer nanocarrier was conjugated with the highly lipophilic pluronic P123 (G4.0-P123) exhibiting a higher drug loading efficiency (up to 76.25%) in comparison with another pluronics. Live/dead fibroblast cell staining assay mentioned that all conjugated nanocarriers are highly biocompatible. The drug-loaded nanocarriers also indicated a highly anti-proliferative activity against MCF-7 breast cancer cell. The obtained results demonstrated a great potential of the highly lipophilic pluronics-conjugated nanocarriers in hydrophobic drugs delivery for biomedical applications. - Highlights: • Biocompatible pluronic-conjugated polyamidoamine dendrimers were prepared at nanoscale for drug delivery. • The dendrimer nanocarrier was decorated with a lipophilic pluronic exhibiting a higher drug loading efficiency. • The pluronic-functionalized nanocarriers demonstrated a great potential for delivering hydrophobic drugs.

  4. Decreased hydrophobicity of iridescent feathers: a potential cost of shiny plumage.

    Science.gov (United States)

    Eliason, Chad M; Shawkey, Matthew D

    2011-07-01

    Honest advertisement models posit that sexually selected traits are costly to produce, maintain or otherwise bear. Brightly coloured feathers are thought to be classic examples of these models, but evidence for a cost in feathers not coloured by carotenoid pigments is scarce. Unlike pigment-based colours, iridescent feather colours are produced by light scattering in modified feather barbules that are characteristically flattened and twisted towards the feather surface. These modifications increase light reflectance, but also expose more surface area for water adhesion, suggesting a potential trade-off between colour and hydrophobicity. Using light microscopy, spectrometry, contact angle goniometry and self-cleaning experiments, we show that iridescent feathers of mallards, Anas platyrhynchos, are less hydrophobic than adjacent non-iridescent feathers, and that this is primarily caused by differences in barbule microstructure. Furthermore, as a result of this decreased hydrophobicity, iridescent feathers are less efficient at self-cleaning than non-iridescent feathers. Together, these results suggest a previously unforeseen cost of iridescent plumage traits that may help to explain the evolution and distribution of iridescence in birds.

  5. Surface Hydrophobicity Causes SO2 Tolerance in Lichens

    Science.gov (United States)

    Hauck, Markus; Jürgens, Sascha-René; Brinkmann, Martin; Herminghaus, Stephan

    2008-01-01

    Background and Aims The superhydrophobicity of the thallus surface in one of the most SO2-tolerant lichen species, Lecanora conizaeoides, suggests that surface hydrophobicity could be a general feature of lichen symbioses controlling their tolerance to SO2. The study described here tests this hypothesis. Methods Water droplets of the size of a raindrop were placed on the surface of air-dry thalli in 50 lichen species of known SO2 tolerance and contact angles were measured to quantify hydrophobicity. Key Results The wettability of lichen thalli ranges from strongly hydrophobic to strongly hydrophilic. SO2 tolerance of the studied lichen species increased with increasing hydrophobicity of the thallus surface. Extraction of extracellular lichen secondary metabolites with acetone reduced, but did not abolish the hydrophobicity of lichen thalli. Conclusions Surface hydrophobicity is the main factor controlling SO2 tolerance in lichens. It presumably originally evolved as an adaptation to wet habitats preventing the depression of net photosynthesis due to supersaturation of the thallus with water. Hydrophilicity of lichen thalli is an adaptation to dry or humid, but not directly rain-exposed habitats. The crucial role of surface hydrophobicity in SO2 also explains why many markedly SO2-tolerant species are additionally tolerant to other (chemically unrelated) toxic substances including heavy metals. PMID:18077467

  6. RF plasma based selective modification of hydrophilic regions on super hydrophobic surface

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jaehyun; Hwang, Sangyeon; Cho, Dae-Hyun [Department of Mechanical Engineering, Sungkyunkwan University, Suwon 16419 (Korea, Republic of); Hong, Jungwoo [Department of Mechanical Engineering, Graduate of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141 (Korea, Republic of); Shin, Jennifer H., E-mail: j_shin@kaist.ac.kr [Department of Mechanical Engineering, Graduate of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141 (Korea, Republic of); Byun, Doyoung, E-mail: dybyun@skku.edu [Department of Mechanical Engineering, Sungkyunkwan University, Suwon 16419 (Korea, Republic of)

    2017-02-01

    Highlights: • Simple and amenable reforming method for a substrate with disparate patterns of hydrophilic dots on super-hydrophobic surfaces is proposed. • Wettability characteristics and modification mechanism for the surfaces are conducted and revealed through SEM, AFM, WSI, and SIMS. • Several representative materials for various applications are successfully deposited. - Abstract: Selective modification and regional alterations of the surface property have gained a great deal of attention to many engineers. In this paper, we present a simple, a cost-effective, and amendable reforming method for disparate patterns of hydrophilic regions on super-hydrophobic surfaces. Uniform super-hydrophobic layer (Contact angle; CA > 150°, root mean square (RMS) roughness ∼0.28 nm) can be formed using the atmospheric radio frequency (RF) plasma on top of the selective hydrophilic (CA ∼ 70°, RMS roughness ∼0.34 nm) patterns imprinted by electrohydrodynamic (EHD) jet printing technology with polar alcohols (butyl carbitol or ethanol). The wettability of the modified surface was investigated qualitatively utilizing scanning electron microscopy (SEM), atomic force microscopy (AFM), and wavelength scanning interferometer (WSI). Secondary ion mass spectroscopy (SIMS) analysis showed that the alcohol addiction reaction changed the types of radicals on the super-hydrophobic surface. The wettability was found to depend sensitively on chemical radicals on the surface, not on surface morphology (particle size and surface roughness). Furthermore, three different kinds of representative hydrophilic samples (polystyrene nano-particle aqueous solution, Salmonella bacteria medium, and poly(3,4-ethylenediocythiophene) ink) were tested for uniform deposition onto the desired hydrophilic regions. This simple strategy would have broad applications in various research fields that require selective deposition of target materials.

  7. Biomimetic hydrophobic surface fabricated by chemical etching method from hierarchically structured magnesium alloy substrate

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yan; Yin, Xiaoming; Zhang, Jijia [Key Laboratory of Bionic Engineering (Ministry of Education), Jilin University, Changchun 130022 (China); Wang, Yaming [Institute for Advanced Ceramics, Harbin Institute of Technology, Harbin 150001 (China); Han, Zhiwu, E-mail: zwhan@jlu.edu.cn [Key Laboratory of Bionic Engineering (Ministry of Education), Jilin University, Changchun 130022 (China); Ren, Luquan [Key Laboratory of Bionic Engineering (Ministry of Education), Jilin University, Changchun 130022 (China)

    2013-09-01

    As one of the lightest metal materials, magnesium alloy plays an important role in industry such as automobile, airplane and electronic product. However, magnesium alloy is hindered due to its high chemical activity and easily corroded. Here, inspired by typical plant surfaces such as lotus leaves and petals of red rose with super-hydrophobic character, the new hydrophobic surface is fabricated on magnesium alloy to improve anti-corrosion by two-step methodology. The procedure is that the samples are processed by laser first and then immersed and etched in the aqueous AgNO{sub 3} solution concentrations of 0.1 mol/L, 0.3 mol/L and 0.5 mol/L for different times of 15 s, 40 s and 60 s, respectively, finally modified by DTS (CH{sub 3}(CH{sub 2}){sub 11}Si(OCH{sub 3}){sub 3}). The microstructure, chemical composition, wettability and anti-corrosion are characterized by means of SEM, XPS, water contact angle measurement and electrochemical method. The hydrophobic surfaces with microscale crater-like and nanoscale flower-like binary structure are obtained. The low-energy material is contained in surface after DTS treatment. The contact angles could reach up to 138.4 ± 2°, which hydrophobic property is both related to the micro–nano binary structure and chemical composition. The results of electrochemical measurements show that anti-corrosion property of magnesium alloy is improved. Furthermore, our research is expected to create some ideas from natural enlightenment to improve anti-corrosion property of magnesium alloy while this method can be easily extended to other metal materials.

  8. RF plasma based selective modification of hydrophilic regions on super hydrophobic surface

    International Nuclear Information System (INIS)

    Lee, Jaehyun; Hwang, Sangyeon; Cho, Dae-Hyun; Hong, Jungwoo; Shin, Jennifer H.; Byun, Doyoung

    2017-01-01

    Highlights: • Simple and amenable reforming method for a substrate with disparate patterns of hydrophilic dots on super-hydrophobic surfaces is proposed. • Wettability characteristics and modification mechanism for the surfaces are conducted and revealed through SEM, AFM, WSI, and SIMS. • Several representative materials for various applications are successfully deposited. - Abstract: Selective modification and regional alterations of the surface property have gained a great deal of attention to many engineers. In this paper, we present a simple, a cost-effective, and amendable reforming method for disparate patterns of hydrophilic regions on super-hydrophobic surfaces. Uniform super-hydrophobic layer (Contact angle; CA > 150°, root mean square (RMS) roughness ∼0.28 nm) can be formed using the atmospheric radio frequency (RF) plasma on top of the selective hydrophilic (CA ∼ 70°, RMS roughness ∼0.34 nm) patterns imprinted by electrohydrodynamic (EHD) jet printing technology with polar alcohols (butyl carbitol or ethanol). The wettability of the modified surface was investigated qualitatively utilizing scanning electron microscopy (SEM), atomic force microscopy (AFM), and wavelength scanning interferometer (WSI). Secondary ion mass spectroscopy (SIMS) analysis showed that the alcohol addiction reaction changed the types of radicals on the super-hydrophobic surface. The wettability was found to depend sensitively on chemical radicals on the surface, not on surface morphology (particle size and surface roughness). Furthermore, three different kinds of representative hydrophilic samples (polystyrene nano-particle aqueous solution, Salmonella bacteria medium, and poly(3,4-ethylenediocythiophene) ink) were tested for uniform deposition onto the desired hydrophilic regions. This simple strategy would have broad applications in various research fields that require selective deposition of target materials.

  9. Evolving a polymerase for hydrophobic base analogues.

    Science.gov (United States)

    Loakes, David; Gallego, José; Pinheiro, Vitor B; Kool, Eric T; Holliger, Philipp

    2009-10-21

    Hydrophobic base analogues (HBAs) have shown great promise for the expansion of the chemical and coding potential of nucleic acids but are generally poor polymerase substrates. While extensive synthetic efforts have yielded examples of HBAs with favorable substrate properties, their discovery has remained challenging. Here we describe a complementary strategy for improving HBA substrate properties by directed evolution of a dedicated polymerase using compartmentalized self-replication (CSR) with the archetypal HBA 5-nitroindole (d5NI) and its derivative 5-nitroindole-3-carboxamide (d5NIC) as selection substrates. Starting from a repertoire of chimeric polymerases generated by molecular breeding of DNA polymerase genes from the genus Thermus, we isolated a polymerase (5D4) with a generically enhanced ability to utilize HBAs. The selected polymerase. 5D4 was able to form and extend d5NI and d5NIC (d5NI(C)) self-pairs as well as d5NI(C) heteropairs with all four bases with efficiencies approaching, or exceeding, those of the cognate Watson-Crick pairs, despite significant distortions caused by the intercalation of the d5NI(C) heterocycles into the opposing strand base stack, as shown by nuclear magnetic resonance spectroscopy (NMR). Unlike Taq polymerase, 5D4 was also able to extend HBA pairs such as Pyrene: varphi (abasic site), d5NI: varphi, and isocarbostyril (ICS): 7-azaindole (7AI), allowed bypass of a chemically diverse spectrum of HBAs, and enabled PCR amplification with primers comprising multiple d5NI(C)-substitutions, while maintaining high levels of catalytic activity and fidelity. The selected polymerase 5D4 promises to expand the range of nucleobase analogues amenable to replication and should find numerous applications, including the synthesis and replication of nucleic acid polymers with expanded chemical and functional diversity.

  10. New Method for Super Hydrophobic Treatment of Gas Diffusion Layers for Proton Exchange Membrane Fuel Cells Using Electrochemical Reduction of Diazonium Salts.

    Science.gov (United States)

    Thomas, Yohann R J; Benayad, Anass; Schroder, Maxime; Morin, Arnaud; Pauchet, Joël

    2015-07-15

    The purpose of this article is to report a new method for the surface functionalization of commercially available gas diffusion layers (GDLs) by the electrochemical reduction of diazonium salt containing hydrophobic functional groups. The method results in superhydrophobic GDLs, over a large area, without pore blocking. An X-ray photoelectron spectroscopy study based on core level spectra and chemical mapping has demonstrated the successful grafting route, resulting in a homogeneous distribution of the covalently bonded hydrophobic molecules on the surface of the GDL fibers. The result was corroborated by contact angle measurement, showing similar hydrophobicity between the grafted and PTFE-modified GDLs. The electrochemically modified GDLs were tested in proton exchange membrane fuel cells under automotive, wet, and dry conditions and demonstrated improved performance over traditional GDLs.

  11. Fluoroalkyl and Alkyl Chains Have Similar Hydrophobicities in Binding to the “Hydrophobic Wall” of Carbonic Anhydrase

    Energy Technology Data Exchange (ETDEWEB)

    J Mecinovic; P Snyder; K Mirica; S Bai; E Mack; R Kwant; D Moustakas; A Heroux; G Whitesides

    2011-12-31

    The hydrophobic effect, the free-energetically favorable association of nonpolar solutes in water, makes a dominant contribution to binding of many systems of ligands and proteins. The objective of this study was to examine the hydrophobic effect in biomolecular recognition using two chemically different but structurally similar hydrophobic groups, aliphatic hydrocarbons and aliphatic fluorocarbons, and to determine whether the hydrophobicity of the two groups could be distinguished by thermodynamic and biostructural analysis. This paper uses isothermal titration calorimetry (ITC) to examine the thermodynamics of binding of benzenesulfonamides substituted in the para position with alkyl and fluoroalkyl chains (H{sub 2}NSO{sub 2}C{sub 6}H{sub 4}-CONHCH{sub 2}(CX{sub 2}){sub n}CX{sub 3}, n = 0-4, X = H, F) to human carbonic anhydrase II (HCA II). Both alkyl and fluoroalkyl substituents contribute favorably to the enthalpy and the entropy of binding; these contributions increase as the length of chain of the hydrophobic substituent increases. Crystallography of the protein-ligand complexes indicates that the benzenesulfonamide groups of all ligands examined bind with similar geometry, that the tail groups associate with the hydrophobic wall of HCA II (which is made up of the side chains of residues Phe131, Val135, Pro202, and Leu204), and that the structure of the protein is indistinguishable for all but one of the complexes (the longest member of the fluoroalkyl series). Analysis of the thermodynamics of binding as a function of structure is compatible with the hypothesis that hydrophobic binding of both alkyl and fluoroalkyl chains to hydrophobic surface of carbonic anhydrase is due primarily to the release of nonoptimally hydrogen-bonded water molecules that hydrate the binding cavity (including the hydrophobic wall) of HCA II and to the release of water molecules that surround the hydrophobic chain of the ligands. This study defines the balance of enthalpic and

  12. Hydrophobic mismatch in gramicidin A'/lecithin systems

    International Nuclear Information System (INIS)

    Watnick, P.I.; Chan, S.I.; Dea, P.

    1990-01-01

    Gramicidin A' (GA') has been added to three lipid systems of varying hydrophobic thickness: dimyristoyllecithin (DML), dipalmitoyllecithin (DPL), and distearoyllecithin (DSL). The similarity in length between the hydrophobic portion of GA' and the hydrocarbon chains of the lipid bilayers has been studied by using 31 P and 2 H NMR. Hydrophobic mismatch has been found to be most severe in the DML bilayer system and minimal in the case of DSL. In addition, the effects of hydrophobic mismatch on the cooperative properties of the bilayer have been obtained from 2 H NMR relaxation measurements. The results indicate that incorporation of the peptide into the bilayer disrupts the cooperative director fluctuations characteristic of pure multilamellar lipid dispersions. Finally, the GA'/lecithin ratio at which the well-known transformation from bilayer to reverse hexagonal (H II ) phase occurs is shown to depend on the acyl chain length of the phospholipid. A rationale is proposed for this chain length dependence

  13. Hydrophobic effect of silica functionalized with silylated Ti ...

    Indian Academy of Sciences (India)

    aCentre for Sustainable Nanomaterials, Ibnu Sina Institute for Scientific and Industrial Research,. Universiti ... rate of water adsorption capacity for the hydrophobic catalysts prepared. .... analyzed by Gas Chromatography, Shimadzu model.

  14. Inverse colloidal crystal membranes for hydrophobic interaction membrane chromatography.

    Science.gov (United States)

    Vu, Anh T; Wang, Xinying; Wickramasinghe, S Ranil; Yu, Bing; Yuan, Hua; Cong, Hailin; Luo, Yongli; Tang, Jianguo

    2015-08-01

    Hydrophobic interaction membrane chromatography has gained interest due to its excellent performance in the purification of humanized monoclonal antibodies. The membrane material used in hydrophobic interaction membrane chromatography has typically been commercially available polyvinylidene fluoride. In this contribution, newly developed inverse colloidal crystal membranes that have uniform pores, high porosity and, therefore, high surface area for protein binding are used as hydrophobic interaction membrane chromatography membranes for humanized monoclonal antibody immunoglobulin G purification. The capacity of the inverse colloidal crystal membranes developed here is up to ten times greater than commercially available polyvinylidene fluoride membranes with a similar pore size. This work highlights the importance of developing uniform pore size high porosity membranes in order to maximize the capacity of hydrophobic interaction membrane chromatography. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Impact of Hydrophobic Pollutants' Behavior on Occupational and Environmental Health

    Directory of Open Access Journals (Sweden)

    Ijeoma Kanu

    2005-01-01

    Full Text Available This paper reviews the influence of hydrophobic pollutant behavior on environmental hazards and risks. The definition and examples of hydrophobic pollutants are given as a guide to better understand the sources of release and the media of dispersion in the environment. The properties and behavior of hydrophobic pollutants are described and their influence on environmental hazard and risk is reviewed and evaluated. The overall outcome of the assessment and evaluation showed that all hydrophobic pollutants are hazardous and risky to all organisms, including man. Their risk effects are due to their inherent persistence, bioaccumulation potential, environmental mobility, and reactivity. Their hazardous effects on organisms occur at varying spatial and temporal degrees of emissions, toxicities, exposures, and concentrations.

  16. Protein-induced bilayer Perturbations: Lipid ordering and hydrophobic coupling

    DEFF Research Database (Denmark)

    Petersen, Frederic Nicolas Rønne; Laursen, Ib; Bohr, Henrik

    2009-01-01

    The host lipid bilayer is increasingly being recognized as an important non-specific regulator of membrane protein function. Despite considerable progress the interplay between hydrophobic coupling and lipid ordering is still elusive. We use electron spin resonance (ESR) to study the interaction...... between the model protein gramicidin and lipid bilayers of varying thickness. The free energy of the interaction is up to −6 kJ/mol; thus not strongly favored over lipid–lipid interactions. Incorporation of gramicidin results in increased order parameters with increased protein concentration...... and hydrophobic mismatch. Our findings also show that at high protein:lipid ratios the lipids are motionally restricted but not completely immobilized. Both exchange on and off rate values for the lipid ↔ gramicidin interaction are lowest at optimal hydrophobic matching. Hydrophobic mismatch of few Å results...

  17. On the enrichment of hydrophobic organic compounds in fog droplets

    Science.gov (United States)

    Valsaraj, K. T.; Thoma, G. J.; Reible, D. D.; Thibodeaux, L. J.

    The unusual degree of enrichment of hydrophobic organics in fogwater droplets reported by several investigators can be interpreted as a result of (a) the effects of temperature correction on the reported enrichment factors, (b) the effects of colloidal organic matter (both filterable and non-filterable) in fog water and (c) the effects of the large air-water interfacial adsorption of neutral hydrophobic organics on the tiny fog droplets. The enrichment factor was directly correlated to the hydrophobicity (or the activity coefficient in water) of the compounds, as indicated by their octanol-water partition constants. Compounds with large octanol-water partition coefficients (high activity coefficients in water) showed the largest enrichment. Available experimental data on the adsorption of hydrophobic compounds at the air-water interface and on colloidal organic carbon were used to show that the large specific air-water interfacial areas of fog droplets contribute significantly to the enrichment factor.

  18. Temperature effects on the hydrophobic force between two ...

    Indian Academy of Sciences (India)

    TUHIN SAMANTA

    2018-03-02

    Mar 2, 2018 ... We perform the molecular dynamics simulations to investigate ... molecular assemblies and in the formation of protein complexes.1–7 One of the important manifestations of the hydrophobic interactions is observed in oil-water.

  19. Preparation and characterization of hydrophobic platinum-doped ...

    Indian Academy of Sciences (India)

    Administrator

    2013-05-31

    May 31, 2013 ... drawback of inaccessible micropores and mineral impuri- ties. More recently, there has ... hydrophobicity and mechnical strength. PTFE binder was ... were measured by BET surface area measurement system. (Micromeritics ...

  20. CARNAUBA WAX USED AS AN HYDROPHOBIC AGENT FOR EXPANDED VERMICULITE

    Directory of Open Access Journals (Sweden)

    M.A.F. Melo

    1998-03-01

    Full Text Available This work deals with the use of carnauba wax as an expansion and hydrophobicity agent for vermiculite, to be utilized in the sorption process of oil in water. Evaluation of the system (oil-water-hydrophobic vermiculite submersion percentage was considered in assessing the performance of vermiculite in comparison to a Mexican turf. Carnauba wax seems to be more efficient in both fresh and salt waters.

  1. New Approaches in the Engineering and Characterization of Macromolecular Interfaces Across the Length Scales: Applications to Hydrophobic and Stimulus Responsive Polymers

    NARCIS (Netherlands)

    Song, Jing

    2007-01-01

    The aim of the present Thesis is to enhance characterization and surface engineering approaches to test and control physico-chemical changes on modified hydrophobic (LDPE and PDMS) and stimulus-responsive (PFS) polymers across different length scales. [Here LDPE denotes low density polyethylene,

  2. Hydrophobic polymers modification of mesoporous silica with large pore size for drug release

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Shenmin, E-mail: smzhu@sjtu.edu.c [Shanghai Jiao Tong University, State Key Lab of Metal Matrix Composites (China); Zhang Di; Yang Na [Fudan University, Ministry of Education, Key Lab of Molecular Engineering of Polymers (China)

    2009-04-15

    Mesostructure cellular foam (MCF) materials were modified with hydrophobic polyisoprene (PI) through free radical polymerization in the pores network, and the resulting materials (MCF-PI) were investigated as matrices for drug storage. The successful synthesis of PI inside MCF was characterized by Fourier transform infrared (FT-IR), hydrogen nuclear magnetic resonance ({sup 1}H NMR), X-ray diffraction patterns (XRD) and nitrogen adsorption/desorption measurements. It was interesting to find the resultant system held a relatively large pore size (19.5 nm) and pore volume (1.02 cm{sup 3} g{sup -1}), which would benefit for drug storage. Ibuprofen (IBU) and vancomycin were selected as model drugs and loaded onto unmodified MCF and modified MCF (MCF-PI). The adsorption capacities of these model drugs on MCF-PI were observed increase as compared to that of on pure MCF, due to the trap effects induced by polyisoprene chains inside the pores. The delivery system of MCF-PI was found to be more favorable for the adsorption of IBU (31 wt%, IBU/silica), possibly attributing to the hydrophobic interaction between IBU and PI formed on the internal surface of MCF matrix. The release of drug through the porous network was investigated by measuring uptake and release of IBU.

  3. Scientific basis of a new method for hydrophobic modification of mineral binders using peat products

    Directory of Open Access Journals (Sweden)

    O. Misnikov

    2016-10-01

    Full Text Available This study deals with the issue of caking of mineral binding materials during storage and transportation. The author conducted a critical analysis of known methods for the protection of cement from exposure to moisture and water vapour. Common disadvantages of these methods are their low effectiveness and complexity of use in industrial and domestic environments. This article introduces a new method for hydrophobising construction materials using peat, which achieves high water repellency in the modified materials with relatively low expenditure on organic materials. The author proposes film coating of the mineral particles of dispersed hydrophilic materials as a protection mechanism against their undesirable exposure to moisture during storage. The insulating film consists of hydrophobic products (bitumens released during thermal decomposition of the organic matter in peat. The estimated thickness of the bitumen film is about 12 nm and it does not adversely affect the flow properties of the powder. A model of the formation of film coatings on mineral particles is provided and their elemental chemical composition is determined. It is shown experimentally that the modified hydrophobic cement is protected from exposure to liquid vapours, and optimal values of organic component concentrations in the dispersed mineral matter that do not reduce the strength of cement mortar are identified.

  4. Surface modification of cellulose isolated from Sesamun indicum underutilized seed: A means of enhancing cellulose hydrophobicity

    Directory of Open Access Journals (Sweden)

    Adewale Adewuyi

    2017-09-01

    Full Text Available Cellulose (SC isolated from sesame seed (SS was surface modified with the introduction of an ester functional group via a simple reaction to produce the modified product (SA. SS, SC and SA were characterized using Fourier transform infrared (FTIR, X-ray diffraction (XRD, thermogravimetric analysis (TG, particle size distribution (PSD, zeta potential and scanning electron microscopy (SEM. SC and SA were evaluated for their water holding capacity (WC, oil holding capacity (OC, swelling capacity (SW and their ability to adsorb heavy metals. The FTIR revealed peaks corresponding to the formation of the ester functional group at the surface of SA. The crystallinity of SC was 28.02% but after the modification, it increased to 77.03% in SA. The PSD of SC and SA was both monomodal with sizes of 10.1305 μm in SC and 10.2511 μm in SA. The adsorption capacity of SC towards Pb (II and Cu (II ions was higher than that of SA. However, SA was unable to adsorb Cu (II ions. SA exhibited the lower WC and SW values as compared to SC which suggested an improved hydrophobicity after the modification. This study has shown that hydrophobicity can be improved in cellulose via surface modification.

  5. Measuring hydrophobic micropore volumes in geosorbents from trichloroethylene desorption data.

    Science.gov (United States)

    Cheng, Hefa; Reinhard, Martin

    2006-06-01

    Hydrophobic micropores can play a significant role in controlling the long-term release of organic contaminants from geosorbents. We describe a technique for quantifying the total and the hydrophobic mineral micropore volumes based on the mass of trichloroethylene (TCE) sorbed in the slow-releasing pores under dry and wet conditions, respectively. Micropore desorption models were used to differentiate the fast- and slow-desorbing fractions in desorption profiles. The micropore environment in which organic molecules were sorbed in the presence of water was probed by studying the transformation of a water-reactive compound (2,2-dichloropropane or 2,2-DCP). For sediment from an alluvial aquifer, the total and hydrophobic micropore volumes estimated using this technique were 4.65 microL/g and 0.027 microL/g (0.58% of total), respectively. In microporous silica gel A, a hydrophobic micropore volume of 0.038 microL/g (0.035% of reported total) was measured. The dehydrohalogenation rate of 2,2-DCP sorbed in hydrophobic micropores of the sediment was slower than that reported in bulk water, indicating an environment of low water activity. The results suggest that hydrolyzable organic contaminants sorbed in hydrophobic micropores react slower than in bulk water, consistent with the reported persistence of reactive contaminants in natural soils.

  6. Frosting characteristics on hydrophobic and superhydrophobic surfaces: A review

    International Nuclear Information System (INIS)

    Kim, Min-Hwan; Kim, Hisuk; Lee, Kwan-Soo; Kim, Dong Rip

    2017-01-01

    Highlights: • Fabrication methods of hydrophobic metal surfaces were investigated. • Mechanisms of ice crystal formation were reviewed in terms of static contact angle. • Future researches for frost retardation on heat exchanger surfaces were discussed. - Abstract: Fabrication methods of the hydrophobic property on metal surfaces and frosting characteristics on hydrophobic surfaces were investigated. A hydrophobic surface with a static contact angle of less than 150° was implemented by surface coating or etching, and a superhydrophobic surface with a static contact angle of greater than 150° was realized by a hybrid method using both coating and etching. The changes in surface properties affected the behaviors of the early stage frosting from the dry surface to the formation of ice crystals. On the hydrophobic surfaces, ice crystals were formed by freezing after condensation. Isolated-droplet freezing and inter-droplet freezing are mechanisms by which the condensate undergoes a phase change into ice crystals. Through isolated-droplet freezing, a supercooled condensate changes phase into ice crystals by forming ice nuclei based on the classical nucleation theory. In addition, through inter-droplet freezing, ice crystals are propagated due to the difference in saturation vapor pressure between supercooled condensates and ice crystals. The formation and propagation of ice crystals are delayed as the static contact angle increases. Additionally, based on a review, future researches that is needed to improve hydrophobic technologies are discussed.

  7. Soil hydrophobicity: comparative study of usual determination methods

    Directory of Open Access Journals (Sweden)

    Eduardo Saldanha Vogelmann

    2015-02-01

    Full Text Available Hydrophobic or water repellent soils slowly absorb water because of the low wett ability of the soil particles which are coated with hydrophobic organic substances. These pose significant effects on plant growth, water infiltration and retention, surface runoff and erosion. The objective of this study was to compare the performance of tension micro-infiltrometer(TMI and the water drop penetration time (WDPT methods in the determination of the hydrophobicity index of eighteen soils from southern Brazil. Soil samples were collected from the 0-5cm soil layer to determine particle size distribution, organic matter content, hydrophobicity index of soil aggregates and droplet penetration time of disaggregated and sieved soil samples. For the TMI method the soil samples were subjected to minor changes due to the use of macroaggregates to preserve the distribution of solid constituents in the soil. Due to the homogeneity of the soil samples the WDPT method gave smaller coefficients of variation unlike the TMI method where the soil structure is preserved. However, both methods had low coefficients of variation, and are thus effective for determining the soil hydrophobicity, especially when the log hydrophobicity index or log WDPT is >1.

  8. Silane decorated metallic nanorods for hydrophobic applications

    International Nuclear Information System (INIS)

    Kannarpady, Ganesh K.; Sharma, Rajesh; Liu Bo; Trigwell, Steve; Ryerson, Charles; Biris, Alexandru S.

    2010-01-01

    A novel technique to modify a metallic surface for anti-icing applications is presented. An oblique angle deposition (OAD) technique has been used to fabricate metallic nanorods of Aluminum and Tungsten on a glass substrate. A conformal coating of a silane has been applied using a molecular vapor deposition technique. The resulting surface has shown a static contact angle of 134 deg. with the water droplet. SEM, AFM and XPS have been used to study the surface modification. This is a highly promising approach for anti-icing applications due to its scalability at a very low cost.

  9. Binding of hydrophobic antigens to surfaces

    DEFF Research Database (Denmark)

    2017-01-01

    A first aspect of the present invention is a method of detecting antibodies comprising the steps of: i) providing a first group of beads comprising a surface modified with C1-C10 alkyl groups comprising amine, ammonium, ether and/or hydroxyl groups, ii) contacting said first group of beads......-antigen-antibody conjugates, and v) detecting said bead-antigen-antibody conjugates. Further aspects include an antibody detection kit, a bead-antigen conjugate and a composition comprising at least two different groups of bead-antigen-conjugates....

  10. Development of hydrophobic clay–alumina based capillary membrane for desalination of brine by membrane distillation

    Directory of Open Access Journals (Sweden)

    Rakhi Das

    2016-09-01

    Full Text Available Clay–alumina compositions of 0, 20, 40 and 55 weight percent (wt% clay and rest alumina were maintained in porous support preparation by extrusion followed by sintering at 1300 °C for 2.5 h to obtain 3 mm/2 mm (outer diameter/inner diameter capillary. 1H,1H,2H,2H-perfluorodecyltriethoxysilane (97% (C8 was used to modify the capillary surface of all compositions without any intermediate membrane layer to impart hydrophobic characteristics and compared in terms of contact angle produced by the capillaries with water and liquid entry pressure (LEPw. FTIR analysis showed that the hydrophilic surface of the capillary membranes was efficiently modified by the proposed grafting method. Capillary with 55 wt% clay produced a pore size of 1.43 micron and was considered as an ideal candidate for grafting with C8 polymer to impart surface hydrophobicity. The contact angle and LEPw value obtained for this modified membrane (C-55-M were 145° and 1 bar, respectively. The modified capillary membrane was applied for desalination of brine by air gap membrane distillation (AGMD at a feed pressure of 0.85 bar. Maximum flux obtained for C-55-M membrane was 98.66 L/m2 day at a temperature difference of 60 °C with salt rejection of 99.96%. Mass transfer coefficient of C-55-M was 16 × 10−3 mm/s at feed temperature of 70 °C.

  11. Enzymatic hydrophobization of jute fabrics and its effect on the mechanical and interfacial properties of jute/PP composites

    Directory of Open Access Journals (Sweden)

    A. Dong

    2016-05-01

    Full Text Available In this work, a hydrophobic surface of lignocellulosic jute fabric was achieved via the laccase-mediated grafting of octadecylamine (OA on lignin moieties of jute aiming to improve the interfacial compatibility with the hydrophobic polypropylene (PP resins in the fiber-reinforced composites. Firstly, the surface and total elemental compositions of the modified jute fabrics were investigated by X-ray photoelectron spectroscopy (XPS and elemental analysis, respectively. The increases in the surface C/O ratio and total nitrogen content of jute fabrics after the laccase/OA treatment indicated that OA molecules were successfully grafted onto the jute surface mediated by laccase. The grafting percentage of OA on jute fabrics was 0.96%. The surface hydrophobicity of jute fabrics with static contact angle of 112.5°, advancing angle of 116.4° and receding angle of 42.7° supported the presence of nonpolar alkyl chains on the jute surface after the laccase-mediated OA-grafting. The tensile strength, tensile modulus as well as the elongation at break of the hydrophobized jute/PP composites were increased. The fracture surface of the composites became neat and the jute fibers on the section surface were surrounded by PP resins closely, which suggested better interfacial adhesion between the jute reinforcement and the PP resin.

  12. Characterization of highly hydrophobic textiles by means of X-ray microtomography, wettability analysis and drop impact

    Science.gov (United States)

    Santini, M.; Guilizzoni, M.; Fest-Santini, S.; Lorenzi, M.

    2017-11-01

    Highly hydrophobic surfaces have been intensively investigated in the last years because their properties may lead to very promising technological spillovers encompassing both everyday use and high-tech fields. Focusing on textiles, hydrophobic fabrics are of major interest for applications ranging from clothes to architecture to environment protection and energy conversion. Gas diffusion media - made by a gas diffusion layer (GDL) and a microporous layer (MPL) - for fuel cells are a good benchmark to develop techniques aimed at characterizing the wetting performances of engineered textiles. An experimental investigation was carried out about carbon-based, PTFE-treated GDLs with and without MPLs. Two samples (woven and woven-non-woven) were analysed before and after coating with a MPL. Their three-dimensional structure was reconstructed and analysed by computer-aided X-ray microtomography (µCT). Static and dynamic wettability analyses were then carried out using a modified axisymmetric drop shape analysis technique. All the surfaces exhibited very high hydrophobicity, three of them near to a super-hydrophobic behavior. Water drop impacts were performed, evidencing different bouncing, sticking and fragmentation outcomes for which critical values of the Weber number were identified. Finally, a µCT scan of a drop on a GDL was performed, confirming the Cassie-Baxter wetting state on such surface.

  13. Application of perfluorinated acids as ion-pairing reagents for reversed-phase chromatography and retention-hydrophobicity relationships studies of selected beta-blockers.

    Science.gov (United States)

    Flieger, J

    2010-01-22

    The addition of the homologous series of perfluorinated acids-trifluoroacetic acid (TFAA), pentafluoropropionic acid (PFPA), heptafluorobutyric acid (HFBA) to mobile phases for reversed-phase high-performance liquid chromatography (RP-HPLC) of beta-blockers was tested. Acidic modifiers were responsible for acidification of mobile phase (pH 3) ensuring the protonation of the beta-blockers and further ion pairs creation. The effect of the type and concentration of mobile phase additives on retention parameters, the efficiency of the peaks, their symmetry and separation selectivity of the beta-blockers mixture were all studied. It appeared that at increasing acid concentration, the retention factor, for all compounds investigated, increased to varying degrees. It should be stressed that the presence of acids more significantly affected the retention of the most hydrophobic beta-blockers. Differences in hydrophobicity of drugs can be maximized through variation of the hydrophobicity of additives. Thus, the relative increase in the retention depends on either concentration and hydrophobicity of the anionic mobile phase additive or hydrophobicity of analytes. According to QSRR (quantitative structure retention relationship) methodology, chromatographic lipophilicity parameters: isocratic log k and log k(w) values (extrapolated retention to pure water) were correlated with the molecular (log P(o/w)) and apparent (log P(app)) octanol-water partition coefficients obtained experimentally by countercurrent chromatography (CCC) or predicted by Pallas software. The obtained, satisfactory retention-hydrophobicity correlations indicate that, in the case of the basic drugs examined in RP-HPLC systems modified with perfluorinated acids, the retention is mainly governed by their hydrophobicity. Copyright 2009 Elsevier B.V. All rights reserved.

  14. Elaboration of highly hydrophobic polymeric surface — a potential strategy to reduce the adhesion of pathogenic bacteria?

    Energy Technology Data Exchange (ETDEWEB)

    Poncin-Epaillard, F., E-mail: fabienne.poncin-epaillard@univ-lemans.fr [Institut des Molécules et Matériaux du Mans (IMMM), département Polymères, Colloïdes et Interfaces, UMR CNRS 6283 Université LUNAM, av. O. Messiaen, 72085 Le Mans (France); Herry, J.M. [INRA-AgroParisTech, UMR 1319 MICALIS, équipe B2HM, 25 avenue de la République, 91300 Massy (France); Marmey, P.; Legeay, G. [CTTM, 20 rue Thalès de Milet 72000 Le Mans (France); Debarnot, D. [Institut des Molécules et Matériaux du Mans (IMMM), département Polymères, Colloïdes et Interfaces, UMR CNRS 6283 Université LUNAM, av. O. Messiaen, 72085 Le Mans (France); Bellon-Fontaine, M.N. [INRA-AgroParisTech, UMR 1319 MICALIS, équipe B2HM, 25 avenue de la République, 91300 Massy (France)

    2013-04-01

    Different polymeric surfaces have been modified in order to reach a high hydrophobic character, indeed the superhydrophobicity property. For this purpose, polypropylene and polystyrene have been treated by RF or μwaves CF{sub 4} plasma with different volumes, the results were compared according to the density of injected power. The effect of pretreatment such as mechanical abrasion or plasma activation was also studied. The modified surfaces were shown as hydrophobic, or even superhydrophobic depending of defects density. They were characterized by measurement of wettability and roughness at different scales, i.e. macroscopic, mesoscopic and atomic. It has been shown that a homogeneous surface at the macroscopic scale could be heterogeneous at lower mesoscopic scale. This was associated with the crystallinity of the material. The bioadhesion tests were performed with Gram positive and negative pathogenic strains: Listeria monocytogenes, Pseudomonas aeruginosa and Hafnia alvei. They have demonstrated an antibacterial efficiency of very hydrophobic and amorphous PS treated for all strains tested and a strain-dependent efficiency with modified PP surface being very heterogeneous at the mesoscopic scale. Thus, these biological results pointed out not only the respective role of the surface chemistry and topography in bacterial adhesion, but also the dependence on the peaks and valley distribution at bacteria dimension scale. Highlights: ► Simple, eco-friendly modification of polymers leading to highly hydrophobic property ► Plasma treatment inducing surface fluorination and roughness ► Study of non-adhesion of different types of bacteria onto such polymeric surfaces ► Dependence of their non-adhesion on surface topography whatever their characteristics.

  15. Improved gel electrophoresis matrix for hydrophobic protein separation and identification.

    Science.gov (United States)

    Tokarski, Caroline; Fillet, Marianne; Rolando, Christian

    2011-03-01

    We propose an improved acrylamide gel for the separation of hydrophobic proteins. The separation strategy is based on the incorporation of N-alkylated and N,N'-dialkylated acrylamide monomers in the gel composition in order to increase hydrophobic interactions between the gel matrix and the membrane proteins. Focusing on the most efficient monomer, N,N'-dimethylacrylamide, the potentiality of the new matrix was evaluated on membrane proteins of the human colon HCT-116 cell line. Protein analysis was performed using an adapted analytical strategy based on FT-ICR tandem mass spectrometry. As a result of this comparative study, including advanced reproducibility experiments, more hydrophobic proteins were identified in the new gel (average GRAVY: -0.085) than in the classical gel (average GRAVY: -0.411). Highly hydrophobic peptides were identified reaching a GRAVY value up to 1.450, therefore indicating their probable locations in the membrane. Focusing on predicted transmembrane domains, it can be pointed out that 27 proteins were identified in the hydrophobic gel containing up to 11 transmembrane domains; in the classical gel, only 5 proteins containing 1 transmembrane domain were successfully identified. For example, multiple ionic channels and receptors were characterized in the hydrophobic gel such as the sodium/potassium channel and the glutamate or the transferrin receptors whereas they are traditionally detected using specific enrichment techniques such as immunoprecipitation. In total, membrane proteins identified in the classical gel are well documented in the literature, while most of the membrane proteins only identified on the hydrophobic gel have rarely or never been described using a proteomic-based approach. 2010 Elsevier Inc. All rights reserved.

  16. Influence of hydrophobicity on the chemical treatments of graphene

    Science.gov (United States)

    Rai, Krishna Bahadur; Khadka, Ishwor Bahadur; Kim, Eun Hye; Ahn, Sung Joon; Kim, Hyun Woo; Ahn, Joung Real

    2018-01-01

    The defect-free transfer of graphene grown by using chemical vapor deposition is essential for its applications to electronic devices. For the reduction of inevitable chemical residues, such as polar molecules and ionized impurities resulting from the transfer process, a hydrophobic polydimethyl-siloxane (PDMS) film was coated on a SiO2/Si wafer. The hydrophobic PDMS film resulted in fewer defects in graphene in comparison to a bare SiO2/Si wafer, as measured with Raman spectroscopy. We also studied the influence of the hydrophobic PDMS film on the chemical doping of graphene. Here, nitric acid (HNO3) was used to make p-type graphene. When graphene was transferred onto a SiO2/Si wafer coated with the hydrophobic PDMS film, fewer defects, compared to those in graphene transferred onto a bare SiO2/Si wafer, were created in grapheme by HNO3 as measured with Raman spectroscopy. The experiments suggest that when graphene is transferred onto a hydrophobic film, the number of defects created by chemical molecules can be reduced.

  17. Hydrophobic polymers for orodispersible films: a quality by design approach.

    Science.gov (United States)

    Borges, Ana Filipa; Silva, Branca M A; Silva, Cláudia; Coelho, Jorge F J; Simões, Sérgio

    2016-10-01

    To develop orodispersible films (ODF) based on hydrophobic polymers with higher stability to ordinary environmental humidity conditions without compromising their fast disintegration time. A quality by design approach was applied to screen three different formulations each one based on a different hydrophobic polymer: polyvinyl acetate, methacrylate-based copolymer and shellac. The screening formulations were characterized regarding their mechanical properties, residual water content, disintegration time and appearance, in order to find a suitable ODF formulation according to established critical quality attributes. The selected critical process parameters for the selection of appropriate ODF formulations were the percentage of the different excipients and the plasticizer type. Three hydrophobic-based matrices with fast disintegration were developed. These were generically composed by a hydrophobic polymer, a stabilizer, a disintegrant and a plasticizer. It verified that the common components within the three different formulations behave differently depending on the system/chemical environment that they were included. It was shown that it is possible to develop oral films based on hydrophobic polymers with fast disintegration time, good texture and appearance, breaking a paradigm of the ODF research field.

  18. Hydrophobic core substitutions in calbindin D9k

    DEFF Research Database (Denmark)

    Kragelund, B B; Jönsson, M; Bifulco, G

    1998-01-01

    Hydrophobic core residues have a marked influence on the Ca2+-binding properties of calbindin D9k, even though there are no direct contacts between these residues and the bound Ca2+ ions. Eleven different mutants with substitutions in the hydrophobic core were produced, and their equilibrium Ca2+...... that the hydrophobic core residues promote Ca2+ binding both by contributing to the preformation of the Ca2+ sites in the apo state and by preferentially stabilizing the Ca2+-bound state.......Hydrophobic core residues have a marked influence on the Ca2+-binding properties of calbindin D9k, even though there are no direct contacts between these residues and the bound Ca2+ ions. Eleven different mutants with substitutions in the hydrophobic core were produced, and their equilibrium Ca2...... that the mutation causes only very minimal perturbations in the immediate vicinity of residue 61. Substitutions of alanines or glycines for bulky residues in the center of the core were found to have significant effects on both Ca2+ affinity and dissociation rates. These substitutions caused a reduction in affinity...

  19. Preparation of highly hydrophobic cotton fabrics by modification with bifunctional silsesquioxanes in the sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Przybylak, Marcin, E-mail: marcin.przybylak@ppnt.poznan.pl [Poznań Science and Technology Park, Adam Mickiewicz University Foundation, Rubież 46, 61-612 Poznań (Poland); Maciejewski, Hieronim, E-mail: maciejm@amu.edu.pl [Poznań Science and Technology Park, Adam Mickiewicz University Foundation, Rubież 46, 61-612 Poznań (Poland); Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznań (Poland); Dutkiewicz, Agnieszka, E-mail: agdut@interia.pl [Poznań Science and Technology Park, Adam Mickiewicz University Foundation, Rubież 46, 61-612 Poznań (Poland)

    2016-11-30

    Highlights: • Fabric hydrophobization process using bifunctional silsesquioxanes was studied. • Superhydrophobic fabric was produced using fluorofunctional silsesquioxanes. • Surface of modified fabrics was analyzed using different techniques. - Abstract: The surface modification of cotton fabrics was carried out using two types of bifunctional fluorinated silsesquioxanes with different ratios of functional groups. The modification was performed either by one- or two-step process. Two methods, the sol-gel and the dip coating method were used in different configurations. The heat treatment and the washing process were applied after modification. The wettability of cotton fabric was evaluated by measuring water contact angles (WCA). Changes in the surface morphology were examined by scanning electron microscopy (SEM, SEM-LFD) and atomic force microscopy (AFM). Moreover, the modified fabrics were subjected to analysis of elemental composition of the applied coatings using SEM-EDS techniques. Highly hydrophobic textiles were obtained in all cases studied and one of the modifications resulted in imparting superhydrophobic properties. Most of impregnated textiles remained hydrophobic even after multiple washing process which shows that the studied modification is durable.

  20. Preparation of enhanced hydrophobic poly(L-lactide-co-ε-caprolactone) films surface and its blood compatibility

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seung Il; Lim, Jin Ik; Jung, Youngmee; Mun, Cho Hay [Division of Life and Health Science, Biomaterials Research Center, Korea Institute of Science and Technology, Seoul (Korea, Republic of); Kim, Ji Heung, E-mail: kimjh@skku.edu [Department of Chemical Engineering, Polymer Technology Institute, Sungkyunkwan University, Suwon, Kyunggi (Korea, Republic of); Kim, Soo Hyun, E-mail: soohkim@kist.re.kr [Division of Life and Health Science, Biomaterials Research Center, Korea Institute of Science and Technology, Seoul (Korea, Republic of); KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul (Korea, Republic of)

    2013-07-01

    Hydrophobicity-enhanced poly(L-lactide-co-ε-caprolactone) (PLCL) (50:50) films were cast by using the solvent–nonsolvent casting method. PLCL (50:50) was synthesized by the well-known random copolymerization process and confirmed by {sup 1}H NMR analysis. The molecular weight of the synthesized PLCL was measured by gel permeation chromatography (GPC). Number-average (Mn), weight-average (Mw) molecular weights and polydispersity (Mw/Mn) were 7 × 10{sup 4}, 1.2 × 10{sup 5}, and 1.7, respectively. PLCL films were cast in vacuum condition with various nonsolvents and nonsolvent ratios. Tetrahydrofuran (THF) was used as the solvent and three different alcohols were used as the nonsolvent: methanol, ethanol, and isopropyl alcohol (IPA). Surface hydrophobicity was confirmed by water contact angle. The water contact angle was increased from 81° ± 2° to 107° ± 2°. Water contact angle was influenced by surface porosity and topography. The prepared film surfaces were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The change of crystalline property was characterized by X-ray diffraction (XRD). Platelet adhesion tests on the modified PLCL film surfaces were evaluated by platelet-rich plasma (PRP). The modified film surface exhibited enhanced hydrophobicity and reduced platelet adhesion ratio depending on the surface topography. One of the candidate products proposed as a potential blood compatible material showed a markedly reduced platelet adhesion property.

  1. Fabrication and characterization of a novel hydrophobic CaCO{sub 3} grafted by hydroxylated poly(vinyl chloride) chains

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Lixia [State Key Laboratory of Polymer Materials Engineering, Sichuan University (China); School of Chemical Science and Technology, Yunnan University (China); Yang, Simei; Luo, Xin [School of Chemical Science and Technology, Yunnan University (China); Lei, Jingxin [State Key Laboratory of Polymer Materials Engineering, Sichuan University (China); Cao, Qiue [School of Chemical Science and Technology, Yunnan University (China); Wang, Jiliang, E-mail: jlwang@ynu.edu.cn [School of Chemical Science and Technology, Yunnan University (China)

    2015-12-01

    Highlights: • Hydroxylated poly(vinyl chloride) (PVC-OH) with different molecular weight and hydroxyl value was successfully prepared by the suspension copolymerization. • PVC-OH was grafted onto the surface of CaCO{sub 3} particles by the urethane formation reaction. • The modified CaCO{sub 3} particles show excellent hydrophobicity. - Abstract: The hydroxylated PVC (PVC-OH) was successfully synthesized by a suspension polymerization of vinyl chloride (VC), butyl acrylate (BA) and hydroxyethyl acrylate (HEA). Novel hydrophobic CaCO{sub 3} was then prepared by a urethane formation reaction between methylene diphenyl diisocyanate (MDI) and the −OH groups both in the PVC-OH chains and on the surface of pristine CaCO{sub 3} particles. The effect of the PVC-OH content on the grafting ratio of treated CaCO{sub 3} particles was extensively investigated. Combining the result of Fourier transform infrared (FTIR) with that of water contact angle, it can be concluded that the hydrophobicity of CaCO{sub 3} had been efficiently improved by the PVC-OH segments grafted on the surface of CaCO{sub 3} particles. X-ray diffraction (XRD), thermal gravity analysis (TGA), scanning electron microscope (SEM) and transmission electron microscope (TEM) were also used to study crystalline behaviors, thermal stability and surface morphology of the modified CaCO{sub 3} particles, respectively. The change of specific surface area implying surface modification was investigated as well.

  2. Functional bacterial amyloid increases Pseudomonas biofilm hydrophobicity and stiffness

    DEFF Research Database (Denmark)

    Zeng, Guanghong; Vad, Brian S; Dueholm, Morten S

    2015-01-01

    The success of Pseudomonas species as opportunistic pathogens derives in great part from their ability to form stable biofilms that offer protection against chemical and mechanical attack. The extracellular matrix of biofilms contains numerous biomolecules, and it has recently been discovered...... that in Pseudomonas one of the components includes β-sheet rich amyloid fibrils (functional amyloid) produced by the fap operon. However, the role of the functional amyloid within the biofilm has not yet been investigated in detail. Here we investigate how the fap-based amyloid produced by Pseudomonas affects biofilm...... hydrophobicity and mechanical properties. Using atomic force microscopy imaging and force spectroscopy, we show that the amyloid renders individual cells more resistant to drying and alters their interactions with hydrophobic probes. Importantly, amyloid makes Pseudomonas more hydrophobic and increases biofilm...

  3. Evaluation of Dimethylformamide (DMF) as an Organic Modifier in ...

    African Journals Online (AJOL)

    ... (DMF) as an organic modifier in hydrophobicity index (Rm) determination. Method: We quantitatively evaluated the problem of partial miscibility of phases associated with the reversed phase thin layer chromatographic (RPTLC) system, using liquid paraffin as stationary phase and acetone/water mixtures as mobile phase.

  4. Driving force for hydrophobic interaction at different length scales.

    Science.gov (United States)

    Zangi, Ronen

    2011-03-17

    We study by molecular dynamics simulations the driving force for the hydrophobic interaction between graphene sheets of different sizes down to the atomic scale. Similar to the prediction by Lum, Chandler, and Weeks for hard-sphere solvation [J. Phys. Chem. B 1999, 103, 4570-4577], we find the driving force to be length-scale dependent, despite the fact that our model systems do not exhibit dewetting. For small hydrophobic solutes, the association is purely entropic, while enthalpy favors dissociation. The latter is demonstrated to arise from the enhancement of hydrogen bonding between the water molecules around small hydrophobes. On the other hand, the attraction between large graphene sheets is dominated by enthalpy which mainly originates from direct solute-solute interactions. The crossover length is found to be inside the range of 0.3-1.5 nm(2) of the surface area of the hydrophobe that is eliminated in the association process. In the large-scale regime, different thermodynamic properties are scalable with this change of surface area. In particular, upon dimerization, a total and a water-induced stabilization of approximately 65 and 12 kJ/mol/nm(2) are obtained, respectively, and on average around one hydrogen bond is gained per 1 nm(2) of graphene sheet association. Furthermore, the potential of mean force between the sheets is also scalable except for interplate distances smaller than 0.64 nm which corresponds to the region around the barrier for removing the last layer of water. It turns out that, as the surface area increases, the relative height of the barrier for association decreases and the range of attraction increases. It is also shown that, around small hydrophobic solutes, the lifetime of the hydrogen bonds is longer than in the bulk, while around large hydrophobes it is the same. Nevertheless, the rearrangement of the hydrogen-bond network for both length-scale regimes is slower than in bulk water. © 2011 American Chemical Society

  5. Super-Hydrophobic Green Corrosion Inhibitor On Carbon Steel

    Science.gov (United States)

    Hassan, H.; Ismail, A.; Ahmad, S.; Soon, C. F.

    2017-06-01

    There are many examples of organic coatings used for corrosion protection. In particular, hydrophobic and super-hydrophobic coatings are shown to give good protection because of their enhanced ability to slow down transport of water and ions through the coating. The purpose of this research is to develop water repellent coating to avoid direct contact between metal and environment corrosive and mitigate corrosion attack at pipeline system. This water repellent characteristic on super-hydrophobic coating was coated by electrodeposition method. Wettability of carbon steel with super-hydrophobic coating (cerium chloride and myristic acid) and oxidized surface was investigated through contact angle and inhibitor performance test. The inhibitor performance was studied in 25% tannin acid corrosion test at 30°C and 3.5% sodium chloride (NaCl). The water contact angle test was determined by placing a 4-μL water droplet of distilled water. It shows that the wettability of contact angle super-hydrophobic with an angle of 151.60° at zero minute can be classified as super-hydrophobic characteristic. By added tannin acid as inhibitor the corrosion protection on carbon steel becomes more consistent. This reveals that the ability of the coating to withstand with the corrosion attack in the seawater at different period of immersions. The results elucidate that the weight loss increased as the time of exposure increased. However, the corrosion rates for uncoated carbon steel is high compared to coated carbon steel. As a conclusion, from both samples it can be seen that the coated carbon steel has less corrosion rated compared to uncoated carbon steel and addition of inhibitor to the seawater provides more protection to resist corrosion attack on carbon steel.

  6. Hydrothermal preparation of hydrophobic and hydrophilic nanoparticles of iron oxide and a modification with CM-dextran

    Energy Technology Data Exchange (ETDEWEB)

    Repko, Anton, E-mail: repko@natur.cuni.cz; Niznansky, Daniel; Matulkova, Irena [Charles University in Prague, Department of Inorganic Chemistry, Faculty of Science (Czech Republic); Kalbac, Martin [J. Heyrovsky Institute of Physical Chemistry of the AS CR, v.v.i. (Czech Republic); Vejpravova, Jana [Institute of Physics AS CR, v.v.i., Department of Magnetic Nanosystems (Czech Republic)

    2013-07-15

    Hydrophobic and hydrophilic particles of iron oxide (magnetite/maghemite) with diameter of 6-10 nm were prepared by hydrothermal hydrolysis of iron oleate in water/pentanol/oleic acid system at 180 Degree-Sign C. The hydrophobic/hydrophilic nature of resulting particles was controlled by the presence of sodium oleate and by manipulating the ionic strength (with NaCl). The final particle size was controlled by additional organic solvent (octanol or toluene) and by seed growth. Hydrophilic particles (6 nm) were further modified by carboxymethyl-dextran in water to obtain stable and well-dispersed superparamagnetic nanoparticles suitable for biomedical application. The prepared particles were characterized by transmission electron microscopy, thermogravimetry, Fourier-transform infrared spectroscopy, magnetic measurements, Moessbauer spectroscopy, dynamic light scattering, and zeta-potential measurement.

  7. Intercalation of small hydrophobic molecules in lipid bilayers containing cholesterol

    Energy Technology Data Exchange (ETDEWEB)

    Worcester, D.L.; Hamacher, K.; Kaiser, H.; Kulasekere, R.; Torbet, J. [Univ. of Missouri, Columbia, MO (United States)

    1994-12-31

    Partitioning of small hydrophobic molecules into lipid bilayers containing cholesterol has been studied using the 2XC diffractometer at the University of Missouri Research Reactor. Locations of the compounds were determined by Fourier difference methods with data from both deuterated and undeuterated compounds introduced into the bilayers from the vapor phase. Data fitting procedures were developed for determining how well the compounds were localized. The compounds were found to be localized in a narrow region at the center of the hydrophobic layer, between the two halves of the bilayer. The structures are therefore intercalated structures with the long axis of the molecules in the plane of the bilayer.

  8. Radiation-induced changes in membrane hydrophobicity in liposomes

    International Nuclear Information System (INIS)

    Nakazawa, Tohru; Nagatsuka, Shinichiro; Yukawa, Osami

    1985-01-01

    Effects of γ-radiation on the physical state of membranes were examined with liposomes of lecithin (phosphatidylcholine) from soybean and rat liver microsomes using spin labeling method. There was a slight increase in the membrane fluidity after irradiation. However, a marked decrease in the membrane hydrophobicity by irradiation was observed in the peripheral region in both types of membranes, in parallel with an increase in the lipid peroxidation. These results suggest that irradiation mainly causes a decrease in the membrane hydrophobicity through lipid peroxidation. (author)

  9. Intercalation of small hydrophobic molecules in lipid bilayers containing cholesterol

    International Nuclear Information System (INIS)

    Worcester, D.L.; Hamacher, K.; Kaiser, H.; Kulasekere, R.; Torbet, J.

    1994-01-01

    Partitioning of small hydrophobic molecules into lipid bilayers containing cholesterol has been studied using the 2XC diffractometer at the University of Missouri Research Reactor. Locations of the compounds were determined by Fourier difference methods with data from both deuterated and undeuterated compounds introduced into the bilayers from the vapor phase. Data fitting procedures were developed for determining how well the compounds were localized. The compounds were found to be localized in a narrow region at the center of the hydrophobic layer, between the two halves of the bilayer. The structures are therefore intercalated structures with the long axis of the molecules in the plane of the bilayer

  10. Hydrophobic ampersand hydrophilic: Theoretical models of solvation for molecular biophysics

    International Nuclear Information System (INIS)

    Pratt, L.R.; Tawa, G.J.; Hummer, G.; Garcia, A.E.; Corcelli, S.A.

    1996-01-01

    Molecular statistical thermodynamic models of hydration for chemistry and biophysics have advanced abruptly in recent years. With liquid water as solvent, salvation phenomena are classified as either hydrophobic or hydrophilic effects. Recent progress in treatment of hydrophilic effects have been motivated by continuum dielectric models interpreted as a modelistic implementation of second order perturbation theory. New results testing that perturbation theory of hydrophilic effects are presented and discussed. Recent progress in treatment of hydrophobic effects has been achieved by applying information theory to discover models of packing effects in dense liquids. The simplest models to which those ideas lead are presented and discussed

  11. Artificial hairy surfaces with a nearly perfect hydrophobic response.

    Science.gov (United States)

    Hsu, Shu-Hau; Sigmund, Wolfgang M

    2010-02-02

    A nearly perfect hydrophobic interface by dint of mimicking hairs of arthropods was achieved for the first time. These Gamma-shape artificial hairs were made via a membrane casting technique on polypropylene substrates. This extreme hydrophobicity merely arises from microstructure modification, and no further chemical treatments are needed. The ultralow adhesion to water droplets was evaluated through video assessment, and it is believed to be attributed to the mechanical response of the artificial hairs. The principle of this fabrication technique is accessible and is expected to be compatible with large-area fabrication of superhydrophobic interfaces.

  12. Modified SEAGULL

    Science.gov (United States)

    Salas, M. D.; Kuehn, M. S.

    1994-01-01

    Original version of program incorporated into program SRGULL (LEW-15093) for use on National Aero-Space Plane project, its duty being to model forebody, inlet, and nozzle portions of vehicle. However, real-gas chemistry effects in hypersonic flow fields limited accuracy of that version, because it assumed perfect-gas properties. As a result, SEAGULL modified according to real-gas equilibrium-chemistry methodology. This program analyzes two-dimensional, hypersonic flows of real gases. Modified version of SEAGULL maintains as much of original program as possible, and retains ability to execute original perfect-gas version.

  13. Fabrication of highly hydrophobic two-component thermosetting polyurethane surfaces with silica nanoparticles

    Science.gov (United States)

    Yang, Guang; Song, Jialu; Hou, Xianghui

    2018-05-01

    Highly hydrophobic thermosetting polyurethane (TSU) surfaces with micro-nano hierarchical structures were developed by a simple process combined with sandpaper templates and nano-silica embellishment. Sandpapers with grit sizes varying from 240 to 7000 grit were used to obtain micro-scale roughness on an intrinsic hydrophilic TSU surface. The surface wettability was investigated by contact angle measurement. It was found that the largest contact angle of the TSU surface without nanoparticles at 102 ± 3° was obtained when the template was 240-grit sandpaper and the molding progress started after 45 min curing of TSU. Silica nanoparticles modified with polydimethylsiloxane were scattered onto the surfaces of both the polymer and the template to construct the desirable nanostructures. The influences of the morphology, surface composition and the silica content on the TSU surface wettability were studied by scanning electron microscopy (SEM), attenuated total reflection (ATR) infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and contact angle measurements. The surface of the TSU/SiO2 nanocomposites containing 4 wt% silica nanoparticles exhibited a distinctive dual-scale structure and excellent hydrophobicity with the contact angle above 150°. The mechanism of wettability was also discussed by Wenzel model and Cassie-Baxter model.

  14. Adsorption of benzyldimethylhexadecylammonium chloride at the hydrophobic silica-water interface studied by total internal reflection Raman spectroscopy: effects of silica surface properties and metal salt addition.

    Science.gov (United States)

    Grenoble, Zlata; Baldelli, Steven

    2013-08-29

    The adsorption of the cationic surfactant benzyldimethylhexadecylammonium (BDMHA(+)) chloride was studied at an octadecyltrichlorosilane (OTS)-monolayer-modified silica-water interface by Raman spectroscopy in total internal reflection (TIR) geometry. The present study demonstrates the capabilities of this spectroscopic technique to evaluate thermodynamic and kinetic BDMHA(+)Cl(-) adsorption properties at the hydrophobic silica surface. The surface coverage of BDMHA(+) decreased by 50% at the hydrophobic OTS-silica surface relative to the surface coverage on bare silica; the dominating driving mechanisms for surfactant adsorption were identified as hydrophobic effects and head group charge screening by the electrolyte counterions. Addition of magnesium metal salt (MgCl2) to the aqueous solution (∼ neutral pH) lowered the surface coverage and moderately increased the Langmuir adsorption constants relative to those of the pure surfactant. These trends were previously observed at the hydrophilic, negatively charged silica surface but with a smaller change in the Gibbs free energy of adsorption at the hydrophobic silica surface. The hydrophobic OTS-silica surface properties resulted in shorter times for the surfactant to reach steady-state adsorption conditions compared to the slow adsorption kinetics previously seen with the surfactant at the hydrophilic surface. Adsorption isotherms, based on Raman signal intensities from spectral analysis, were developed according to the Langmuir adsorption model for the pure surfactant at the OTS-silica-water interface; the modified Langmuir model was applied to the surfactant adsorption in the presence of 5, 10, 50, and 100 mM magnesium chloride. Spectral analysis of the Raman scattering intensities and geometric considerations suggests a hemimicelle-type surface aggregate as the most likely surfactant structure at the OTS-silica surface. The different kinetics observed at the hydrophilic versus the hydrophobic silica surface

  15. Photoinduced hydrophobic surface of graphene oxide thin films

    International Nuclear Information System (INIS)

    Zhang Xiaoyan; Song Peng; Cui Xiaoli

    2012-01-01

    Graphene oxide (GO) thin films were deposited on transparent conducting oxide substrates and glass slides by spin coating method at room temperature. The wettability of GO thin films before and after ultraviolet (UV) irradiation was characterized with water contact angles, which increased from 27.3° to 57.6° after 3 h of irradiation, indicating a photo-induced hydrophobic surface. The UV–vis absorption spectra, Raman spectroscopy, X-ray photoelectron spectroscopy, and conductivity measurements of GO films before and after UV irradiation were taken to study the mechanism of photoinduced hydrophobic surface of GO thin films. It is demonstrated that the photoinduced hydrophobic surface is ascribed to the elimination of oxygen-containing functional groups on GO molecules. This work provides a simple strategy to control the wettability properties of GO thin films by UV irradiation. - Highlights: ► Photoinduced hydrophobic surface of graphene oxide thin films has been demonstrated. ► Elimination of oxygen-containing functional groups in graphene oxide achieved by UV irradiation. ► We provide novel strategy to control surface wettability of GO thin films by UV irradiation.

  16. Hydrophobic Ice Confined between Graphene and MoS2

    NARCIS (Netherlands)

    Bampoulis, Pantelis; Teernstra, V.J.; Lohse, Detlef; Zandvliet, Henricus J.W.; Poelsema, Bene

    2016-01-01

    The structure and nature of water confined between hydrophobic molybdenum disulfide (MoS2) and graphene (Gr) are investigated at room temperature by means of atomic force microscopy. We find the formation of two-dimensional (2D) crystalline ice layers. In contrast to the hexagonal ice “bilayers” of

  17. Toward a Simple Molecular Theory of Hydrophobic Hydration.

    Czech Academy of Sciences Publication Activity Database

    Jirsák, Jan; Škvor, J.; Nezbeda, Ivo

    2014-01-01

    Roč. 189, SI (2014), s. 13-19 ISSN 0167-7322 R&D Projects: GA AV ČR IAA200760905 Institutional support: RVO:67985858 Keywords : perturbation theory * primitive models * hydrophobic hydration Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 2.515, year: 2014

  18. Water structure near single and multi-layer nanoscopic hydrophobic ...

    Indian Academy of Sciences (India)

    Wintec

    We have performed a series of molecular dynamics simulations of water containing two nano- scopic hydrophobic ..... the simulation for l00 ps for equilibration during which ... was further run for a production phase of 100–200 ps depending on ...

  19. Effect of photocatalytic and hydrophobic coatings on brewery surface microorganisms.

    Science.gov (United States)

    Priha, O; Laakso, J; Tapani, K; Levänen, E; Kolari, M; Mäntylä, T; Storgårds, E

    2011-11-01

    The aim of this study was to determine whether process hygiene in the beverage industry could be improved by applying new coating techniques to process surfaces. Photocatalytic titanium dioxide (TiO(2)) and hydrophobic coatings applied to stainless steel with or without added antimicrobial compounds were studied in laboratory attachment tests and in a 15-month process study. No clear reductions in numbers of attached microbes were obtained with photocatalytic coatings, except for coatings to which silver had been added. These TiO(2)+Ag coatings reduced microbial coverage in laboratory studies and in some process samples. Hydrophobic coatings reduced the area coverage of microorganisms in 4-h laboratory studies but did not affect colony counts in laboratory or process studies. The surfaces had changed from hydrophobic into hydrophilic during the process study. The coatings did not mechanically fully withstand process conditions; part of the hydrophobic coatings had peeled off, most of the precipitated Ag had dissolved, and some of the TiO(2) coatings were damaged. In conclusion, functional coatings have potential for reducing microbial loads on beverage industry surfaces, but these coatings need further development.

  20. Are N-methyl groups of Tetramethylurea (TMU) Hydrophobic? A ...

    Indian Academy of Sciences (India)

    of three dimensional tetrahedral H-bond network to two dimensional zig-zag chain-like structure often found in alcohols. A comparison to ... All these results indicate hydrophobic interaction-induced aggregation of TMU in dilute aqueous solutions which .... off by gently blowing hot air around the outer surface of the cuvette.

  1. Production of hydrophobic amino acids from biobased resources

    NARCIS (Netherlands)

    Widyarani, W.; Sari, Yessie W.; Ratnaningsih, Enny; Sanders, Johan P.M.; Bruins, Marieke E.

    2016-01-01

    Protein hydrolysis enables production of peptides and free amino acids that are suitable for usage in food and feed or can be used as precursors for bulk chemicals. Several essential amino acids for food and feed have hydrophobic side chains; this property may also be exploited for subsequent

  2. Development of breathable hydrophobic/hydrophilic functional textiles

    NARCIS (Netherlands)

    Agrawal, P. (Pramod); Brink, G.J. (Ger)

    2013-01-01

    The proposed bi-functional protective structure intended to have hydrophilic interior towards the skin surface and hydrophobic exterior for protection, ensuring fast transfer of moisture between body and external environment. The sandwich structure is prepared using 100% wool jersey and varieties of

  3. Nanocarriers from GRAS Zein Proteins to Encapsulate Hydrophobic Actives.

    Science.gov (United States)

    Weissmueller, Nikolas T; Lu, Hoang D; Hurley, Amanda; Prud'homme, Robert K

    2016-11-14

    One factor limiting the expansion of nanomedicines has been the high cost of the materials and processes required for their production. We present a continuous, scalable, low cost nanoencapsulation process, Flash Nanoprecipitation (FNP) that enables the production of nanocarriers (NCs) with a narrow size distribution using zein corn proteins. Zein is a low cost, GRAS protein (having the FDA status of "Generally Regarded as Safe") currently used in food applications, which acts as an effective encapsulant for hydrophobic compounds using FNP. The four-stream FNP configuration allows the encapsulation of very hydrophobic compounds in a way that is not possible with previous precipitation processes. We present the encapsulation of several model active compounds with as high as 45 wt % drug loading with respect to zein concentration into ∼100 nm nanocarriers. Three examples are presented: (1) the pro-drug antioxidant, vitamin E-acetate, (2) an anticholera quorum-sensing modulator CAI-1 ((S)-3-hydroxytridecan-4-one; CAI-1 that reduces Vibrio cholerae virulence by modulating cellular communication), and (3) hydrophobic fluorescent dyes with a range of hydrophobicities. The specific interaction between zein and the milk protein, sodium caseinate, provides stabilization of the NCs in PBS, LB medium, and in pH 2 solutions. The stability and size changes in the three media provide information on the mechanism of assembly of the zein/active/casein NC.

  4. Incorporation of Certain Hydrophobic Excipients in the Core of Melt ...

    African Journals Online (AJOL)

    Patrick Erah

    incorporation of hydrophobic materials (talc or magnesium stearate) in the core of such granules may further retard .... (500mg) was filled into a capsule shell and ... of the drug particles. The effect of melt granulation on the release profiles of paracetamol is shown in Fig 1. The melt granulations displayed a retarded release.

  5. Forces involved in bacterial adhesion to hydrophilic and hydrophobic surfaces

    NARCIS (Netherlands)

    Boks, N.P.; Norde, W.; Meil, H.C.; Busscher, H.J.

    2008-01-01

    Using a parallel-plate flow chamber, the hydrodynamic shear forces to prevent bacterial adhesion (F-prev) and to detach adhering bacteria (F-det) were evaluated for hydrophilic glass, hydrophobic, dimethyldichlorosilane (DDS)-coated glass and six different bacterial strains, in order to test the

  6. Preparation of alveolate hydrophobic catalyst for tritium waste gas treatment

    International Nuclear Information System (INIS)

    Yang, Yong; Peng, Shuming; Wang, Heyi; Du, Yang; Li, Jiamao

    2016-01-01

    Highlights: • The catalyst is hydrophobic, it will not be poisoned by steam in room air at room temperature which is better than Pt-Al 2 O 3 . • At room temperature, the conversion of low concentration of H2 and tritium gas in room air over the catalyst is high. • The air resistance of catalyst is much lower than graininess Pt-Al 2 O 3 . • It is inorganic and will not burn. - Abstract: To prepare a catalyst for the detritiation of waste gases at high flow rates, a heat-resistant hydrophobic zeolitic molecular sieve coating was synthesized on the surface of alveolate cordierite by hydrothermal processing. The alveolate hydrophobic catalyst prepared from the support was essentially waterproof and not easily poisoned by moisture. At room temperature, the conversion of low concentrations of H 2 in humid air over the catalyst was higher than 95% at different space velocities (0–16,000 h −1 ) and different relative humidities. The reaction rate constant of the oxidation of tritium over alveolate hydrophobic catalyst is 0.182 s −1 at 293.3 K–293.7 K and 59%–60% RH, it is much higher than the catalyst of reference honeycomb catalyst.

  7. The Ligand Substitution Reactions of Hydrophobic Vitamin B12 ...

    African Journals Online (AJOL)

    South African Journal of Chemistry ... The equilibrium constants, K, for the reaction of five-membered heterocyclic nitrogenous bases (the azoles imidazole, pyrazole and 1,2,4-triazole) with displacement of ... Keywords: Hydrophobic vitamin B12, cobalt corrinoids, equilibrium constants, solvent polarity, trans influence.

  8. Enhanced adsorption of benzene vapor on granular activated carbon under humid conditions due to shifts in hydrophobicity and total micropore volume.

    Science.gov (United States)

    Liu, Han-Bing; Yang, Bing; Xue, Nan-Dong

    2016-11-15

    A series of hydrophobic-modified (polydimethylsiloxane (PDMS) coating) activated carbons (ACs) were developed to answer a fundamental question: what are the determinants that dominate the adsorption on ACs under humid conditions? Using column experiments, an inter-comparison among bare-AC and PDMS-coated ACs was conducted regarding the association of surface characteristics and adsorption capacity. Primary outcomes occurred in two dominating markers, hydrophobicity and total micropore volume, which played a key role in water adsorption on ACs. However, their contributions to water adsorption on ACs substantially differed under different Pwater/Pair conditions. Hydrophobicity was the only contributor in Pwater/Pair=0.1-0.6, while the two markers contributed equally in Pwater/Pair=0.7-1.0. Furthermore, PDMS-coated AC had a significant increase in benzene adsorption capacities compared to bare-AC at 0-90% relative humidity, while these differences were not significant among PDMS-coated ACs. It is thus presumed that the balance between the two markers can be shifted to favor almost unchanged benzene adsorption capacities among PDMS-coated ACs over a large range of relative humidity. These findings suggest potential benefits of PDMS coating onto ACs in enhancing selective adsorption of hydrophobic volatile organic compounds under high humid conditions. To develop new porous materials with both high total micropore volume and hydrophobicity should thus be considered. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Bacterial adhesion and biofilm formation on surfaces of variable roughness and hydrophobicity

    DEFF Research Database (Denmark)

    Tang, Lone; Pillai, Saju; Iversen, Anders

    L.Biofilm formation on surfaces in food production and processing can deteriorate the quality of food products and be a hazard to consumers. The food industry currently uses a number of approaches to either remove biofilm or prevent its formation. Due to the inherent resilience of bacteria...... in biofilm, a particularly attractive approach is the modification of surfaces with the aim to impede the first step in biofilm formation, namely bacterial adhesion. Surface properties such as hydrophobicity, roughness and predisposition for fouling by protein are recognised as important in bacterial...... adhesion. Sol-gel technology and the recent availability of organic modified silicas have lead to development of hybrid organic/inorganic glass ceramic coatings with specialised surface properties. In this study we investigate bacterial adhesion and the subsequent biofilm formation on stainless steel (SS...

  10. Solution-Processed Organic and Halide Perovskite Transistors on Hydrophobic Surfaces.

    Science.gov (United States)

    Ward, Jeremy W; Smith, Hannah L; Zeidell, Andrew; Diemer, Peter J; Baker, Stephen R; Lee, Hyunsu; Payne, Marcia M; Anthony, John E; Guthold, Martin; Jurchescu, Oana D

    2017-05-31

    Solution-processable electronic devices are highly desirable due to their low cost and compatibility with flexible substrates. However, they are often challenging to fabricate due to the hydrophobic nature of the surfaces of the constituent layers. Here, we use a protein solution to modify the surface properties and to improve the wettability of the fluoropolymer dielectric Cytop. The engineered hydrophilic surface is successfully incorporated in bottom-gate solution-deposited organic field-effect transistors (OFETs) and hybrid organic-inorganic trihalide perovskite field-effect transistors (HTP-FETs) fabricated on flexible substrates. Our analysis of the density of trapping states at the semiconductor-dielectric interface suggests that the increase in the trap density as a result of the chemical treatment is minimal. As a result, the devices exhibit good charge carrier mobilities, near-zero threshold voltages, and low electrical hysteresis.

  11. Encapsulation of hydrophobic dyes in polystyrene micro- and nanoparticles via swelling procedures.

    Science.gov (United States)

    Behnke, Thomas; Würth, Christian; Hoffmann, Katrin; Hübner, Martin; Panne, Ulrich; Resch-Genger, Ute

    2011-05-01

    Aiming at the derivation of a generalized procedure for the straightforward preparation of particles fluorescing in the visible and near-infrared (NIR) spectral region, different swelling procedures for the loading of the hydrophobic polarity-probe Nile Red into nano- and micrometer sized polystyrene particles were studied and compared with respect to the optical properties of the resulting particles. The effect of the amount of incorporated dye on the spectroscopic properties of the particles was investigated for differently sized beads with different surface chemistries, i.e., non-functionalized, amino-modified and PEG-grafted surfaces. Moreover, photostability and leaking studies were performed. The main criterion for the optimization of the dye loading procedures was a high and thermally and photochemically stable fluorescence output of the particles for the future application of these systems as fluorescent labels. © Springer Science+Business Media, LLC 2010

  12. Study of vitamin A derivative complexation in natural and modified cyclodextrins

    International Nuclear Information System (INIS)

    Weisse, Sandrine

    1999-01-01

    This research thesis reports a test of solubilisation and stabilisation of retinol, a highly hydrophobic and unsteady molecule, by natural or modified cyclodextrins. The author first recalls retinol physical-chemical characteristics, and then evokes the different techniques (other than cyclodextrins) used to modify these characteristics. Then, the author addresses the complexes of inclusion of retinol in cyclodextrins, and the associated characterization techniques [fr

  13. Hydrolysis of polyacrylamide containing associative hydrophobic groups: effect of the degree of hydrolysis and ionic strength on the viscosity in aqueous medium

    International Nuclear Information System (INIS)

    Lima, Bruna V. de; Vidal, Rosangela R.L.; Reis, Jeanne H.C. dos; Balaban, Rosangela de C.

    2009-01-01

    The HAPAM-10N polymer (hydrophobically modified and partially hydrolyzed polyacrylamide) was obtained by partial hydrolysis of HAPAM (hydrophobically modified polyacrylamide) precursor containing very low amount of hydrophobic groups (0.75%) in 0.1 M NaCl and 0.25 M NaOH aqueous solutions, at 40 deg C for 10 min. Hydrolysis degree of 44.64 % was obtained by 13 C NMR. The viscosity of polymers solutions was evaluated as a function of polymer concentration, ionic strength and temperature, at constant shear rate. The viscosity of HAPAM solutions increased with polymer concentration, however, it did not change significantly with the increase of ionic strength, and decreased with the temperature enhancement. The viscosity of HAPAM-10N solutions increased significantly in distilled water, due to electrostatic repulsions among carboxylate groups. However, with the increase of polymer concentration, ionic strength and temperature, it was not observed a significant increase of viscosity, probably due to the low amount of hydrophobic groups and high hydrolysis degree. (author)

  14. Modification of hydrophobic acrylic intraocular lens with poly(ethylene glycol) by atmospheric pressure glow discharge: A facile approach

    International Nuclear Information System (INIS)

    Lin Lin; Wang Yao; Huang Xiaodan; Xu Zhikang; Yao Ke

    2010-01-01

    To improve the anterior surface biocompatibility of hydrophobic acrylic intraocular lens (IOL) in a convenient and continuous way, poly(ethylene glycol)s (PEGs) were immobilized by atmospheric pressure glow discharge (APGD) treatment using argon as the discharge gas. The hydrophilicity and chemical changes on the IOL surface were characterized by static water contact angle and X-ray photoelectron spectroscopy to confirm the covalent binding of PEG. The morphology of the IOL surface was observed under field emission scanning electron microscopy and atomic force microscopy. The surface biocompatibility was evaluated by adhesion experiments with platelets, macrophages, and lens epithelial cells (LECs) in vitro. The results revealed that the anterior surface of the PEG-grafted IOL displayed significantly and permanently improved hydrophilicity. Cell repellency was observed, especially in the PEG-modified IOL group, which resisted the attachment of platelets, macrophages and LECs. Moreover, the spread and growth of cells were suppressed, which may be attributed to the steric stabilization force and chain mobility effect of the modified PEG. All of these results indicated that hydrophobic acrylic IOLs can be hydrophilic modified by PEG through APGD treatment in a convenient and continuous manner which will provide advantages for further industrial applications.

  15. Development of new additive for drilling fluid from the partial hydrophobization N,N,N-trimethyl chitosan (TMC); Desenvolvimento de novos aditivos para fluidos de perfuracao a partir da hidrofobizacao parcial da N,N,N trimetilquitosana (TMQ)

    Energy Technology Data Exchange (ETDEWEB)

    Carmo, Thacyla C. do; Lopes, Grazielle; Silva, Joaquim F.M. da; Nascimento, Regina S.V., E-mail: cycyla@hotmail.co [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Polo de Xistoquimica

    2009-07-01

    N,N,N-trimethyl chitosan (TMC) hydrophobically modified can act as an excellent additive for drilling fluids water based, working as inhibitor of reactive shales and rheological modifiers. The cationic chitosan was obtained by reaction of chitosan with CH{sub 3}I in N-methyl-2-pyrrolidone to obtain the TMC and chitosan was also hydrophobically modified with palmitoil chloride to get Quit P. Through another route, Quit P was modified to obtain the cationic TMCP. The derivatives were characterized by FT-IR and {sup 1}HNMR spectrophotometry allowing the calculation of the degree of quaternization of the TMC. The rheology tests showed that the system with TMCP presented pseudo plastic behavior, while the system with TMC behaved as a Newtonian fluid. The results indicated that TMCP can act as rheology modifier for water-based drilling fluids. (author)

  16. Using heat-treated starch to modify the surface of biochar and improve the tensile properties of biochar-filled stryene-butadiene rubber composites

    Science.gov (United States)

    Heat-treated starch is a renewable material that can be used to modify the surface chemistry of small particles. In this work, heat-treated starch was used to coat hydrophilic biochar particles in order to make them more hydrophobic. Then when added as filler to hydrophobic styrene-butadiene rubber,...

  17. Order and correlation contributions to the entropy of hydrophobic solvation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Maoyuan; Besford, Quinn Alexander; Mulvaney, Thomas; Gray-Weale, Angus, E-mail: gusgw@gusgw.net [School of Chemistry, The University of Melbourne, Victoria 3010 (Australia)

    2015-03-21

    The entropy of hydrophobic solvation has been explained as the result of ordered solvation structures, of hydrogen bonds, of the small size of the water molecule, of dispersion forces, and of solvent density fluctuations. We report a new approach to the calculation of the entropy of hydrophobic solvation, along with tests of and comparisons to several other methods. The methods are assessed in the light of the available thermodynamic and spectroscopic information on the effects of temperature on hydrophobic solvation. Five model hydrophobes in SPC/E water give benchmark solvation entropies via Widom’s test-particle insertion method, and other methods and models are tested against these particle-insertion results. Entropies associated with distributions of tetrahedral order, of electric field, and of solvent dipole orientations are examined. We find these contributions are small compared to the benchmark particle-insertion entropy. Competitive with or better than other theories in accuracy, but with no free parameters, is the new estimate of the entropy contributed by correlations between dipole moments. Dipole correlations account for most of the hydrophobic solvation entropy for all models studied and capture the distinctive temperature dependence seen in thermodynamic and spectroscopic experiments. Entropies based on pair and many-body correlations in number density approach the correct magnitudes but fail to describe temperature and size dependences, respectively. Hydrogen-bond definitions and free energies that best reproduce entropies from simulations are reported, but it is difficult to choose one hydrogen bond model that fits a variety of experiments. The use of information theory, scaled-particle theory, and related methods is discussed briefly. Our results provide a test of the Frank-Evans hypothesis that the negative solvation entropy is due to structured water near the solute, complement the spectroscopic detection of that solvation structure by

  18. Polypeptide nanogels with hydrophobic moieties in the cross-linked ionic cores: Synthesis, characterization and implications for anticancer drug delivery

    Science.gov (United States)

    Kim, Jong Oh; Oberoi, Hardeep S.; Desale, Swapnil; Kabanov, Alexander V.; Bronich, Tatiana K.

    2014-01-01

    Polymer nanogels have gained considerable attention as a potential platform for drug delivery applications. Here we describe the design and synthesis of novel polypeptide-based nanogels with hydrophobic moieties in the cross-linked ionic cores. Diblock copolymer, poly(ethylene glycol)-b-poly(L-glutamic acid), hydrophobically modified with L-phenylalanine methyl ester moieties was used for controlled template synthesis of nanogels with small size (ca. 70 nm in diameter) and narrow particle size distribution. Steady-state and time-resolved fluorescence studies using coumarin C153 indicated the existence of hydrophobic domains in the ionic cores of the nanogels. Stable doxorubicin-loaded nanogels were prepared at high drug capacity (30 w/w%). We show that nanogels are enzymatically-degradable leading to accelerated drug release under simulated lysosomal acidic pH. Furthermore, we demonstrate that the nanogel-based formulation of doxorubicin is well tolerated and exhibit an improved antitumor activity compared to a free doxorubicin in an ovarian tumor xenograft mouse model. Our results signify the point to a potential of these biodegradable nanogels as attractive carriers for delivery of chemotherapeutics. PMID:23998716

  19. Interfacial Modifiers

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Ina; French, Roger H.

    2018-03-19

    Our project objective in the first and only Budget Period was to demonstrate the potential of nm-scale organofunctional silane coatings as a method of extending the lifetime of PV materials and devices. Specifically, the target was to double the lifetime performance of a laminated Cu(In,Ga)Se2 (CIGS) cell under real-world and accelerated aging exposure conditions. Key findings are that modification of aluminum-doped zinc oxide (AZO) films (materials used as transparent conductive oxide (TCO) top contacts) resulted in decreased degradation of optical and electrical properties under damp heat (DH) exposure compared to un-modified AZO. The most significant finding is that modification of the AZO top contact of full CIGS devices resulted in significantly improved properties under DH exposure compared to un-modified devices, by a factor of 4 after 1000 h. Results of this one-year project have demonstrated that surface functionalization is a viable pathway for extending the lifetime of state-of-the-art CIGS devices.

  20. Features of the corrosion protection of aluminium alloys by creation of hydrophobic coatings

    Science.gov (United States)

    Sinebryukhov, S. L.; Gnedenkov, S. V.; Egorkin, V. S.; Vyaliy, I. E.

    2017-09-01

    Results of the study of hydrophobic layers on aluminum alloy, which underwent plasma electrolytic oxidation (PEO) and subsequent deposition of the hydrophobic agent have been described. Coatings formed by deposition of dispersion of the hydrophobic agent containing SiO2 nanoparticles on the surface of the PEO-layer are characterized by high contact angles and inhibitive properties. The formed composite layers were found to be characterized with hydrophobicity and high barrier properties.

  1. Impact of a Hydrophobic Sphere onto a Bath

    Science.gov (United States)

    Harris, Daniel M.; Edmonds, John; Galeano-Rios, Carlos A.; Milewski, Paul A.

    2017-11-01

    Small hydrophobic particles impacting a water surface can rebound completely from the interface (Lee & Kim, Langmuir, 2008). In the present work, we focus on the bouncing dynamics of millimetric hydrophobic spheres impacting the surface of a quiescent water bath. Particular attention is given to the dependence of the normal coefficient of restitution and contact time on the impact velocity and the radius and density of the sphere. Our experimental observations are compared to the predictions of a fluid model derived from linearized Navier-Stokes under the assumption of a high Reynolds number regime (Galeano-Rios et al., JFM, in press). In the model, the motions of the sphere and the fluid interface are found by imposing the natural geometric and kinematic compatibility conditions. Future directions will be discussed. C.A.G.-R. and P.A.M. gratefully acknowledge support through the EPSRC project EP/N018176/1.

  2. Influence of chemistry on wetting dynamics of nanotextured hydrophobic surfaces.

    Science.gov (United States)

    Di Mundo, Rosa; Palumbo, Fabio; d'Agostino, Riccardo

    2010-04-06

    In this work, the role of a chemical parameter, such as the degree of fluorination, on the wetting behavior of nanotextured hydrophobic surfaces is investigated. Texture and chemistry tuning of the surfaces has been accomplished with single batch radiofrequency low-pressure plasma processes. Polystyrene substrates have been textured by CF(4) plasma etching and subsequently covered by thin films with a tunable F-to-C ratio, obtained in discharges fed with C(4)F(8)-C(2)H(4). Measurements of wetting dynamics reveal a regime transition from adhesive-hydrophobic to slippery-superhydrophobic, i.e., from wet to non wet states, as the F-to-C rises at constant topography. Such achievements are strengthened by calculation of the solid fraction of surface water contact area applying Cassie-Baxter advancing and receding equations to water contact angle data of textured and flat reference surfaces.

  3. Cell surface hydrophobicity of dental plaque microorganisms in situ.

    OpenAIRE

    Rosenberg, M; Judes, H; Weiss, E

    1983-01-01

    The cell surface hydrophobicity of bacteria obtained directly from human tooth surfaces was assayed by measuring their adherence to liquid hydrocarbons. Fresh samples of supragingival dental plaque were washed and dispersed in buffer. Adherence of the plaque microorganisms to hexadecane, octane, and xylene was tested turbidimetrically and by direct microscopic observation. The results clearly show that the vast majority of bacteria comprising dental plaque exhibit pronounced cell surface hydr...

  4. Preparative characteristics of hydrophobic polymer catalyst for the tritium removal

    International Nuclear Information System (INIS)

    Kang, Hee Suk; Choi, H. J.; Lee, H. S.; Ahn, D. H.; Kim, K. R.; Paek, S. W.; Paek, S. W.; Kim, J. G.; Chung, H. S.

    2001-05-01

    The optimum method for the fabrication of hydrophobic catalyst was selected and the apparatuses for the preparation of catalyst support with high yield was developed for the large scale production. Also, we summarized the method of improving the physical property of the catalyst support, the loading characteristics of Pt metal as a catalyst, and the characteristics of the apparatus for the fabrication of the catalysts on a large scale

  5. Preparative characteristics of hydrophobic polymer catalyst for the tritium removal

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Hee Suk; Choi, H. J.; Lee, H. S.; Ahn, D. H.; Kim, K. R.; Paek, S. W.; Kim, J. G.; Chung, H. S

    2001-05-01

    The optimum method for the fabrication of hydrophobic catalyst was selected and the apparatuses for the preparation of catalyst support with high yield was developed for the large scale production. Also, we summarized the method of improving the physical property of the catalyst support, the loading characteristics of Pt metal as a catalyst, and the characteristics of the apparatus for the fabrication of the catalysts on a large scale.

  6. SET-LRP of the Hydrophobic Biobased Menthyl Acrylate.

    Science.gov (United States)

    Bensabeh, Nabil; Ronda, Joan C; Galià, Marina; Cádiz, Virginia; Lligadas, Gerard; Percec, Virgil

    2018-04-09

    Cu(0) wire-catalyzed single electron transfer-living radical polymerization (SET-LRP) of (-)-menthyl acrylate, a biobased hydrophobic monomer, was investigated at 25 °C in ethanol, isopropanol, ethyl lactate, 2,2,2-trifluoroethanol (TFE), and 2,2,3,3-tetrafluoropropanol (TFP). All solvents are known to promote, in the presence of N ligands, the mechanistically required self-regulated disproportionation of Cu(I)Br into Cu(0) and Cu(II)Br 2 . Both fluorinated alcohols brought out their characteristics of universal SET-LRP solvents and showed the proper polarity balance to mediate an efficient polymerization of this bulky and hydrophobic monomer. Together with the secondary alkyl halide initiator, methyl 2-bromopropionate (MBP), and the tris(2-dimethylaminoethyl)amine (Me 6 -TREN) ligand, TFE and TPF mediated an efficient SET-LRP of MnA at room temperature that proceeds through a self-generated biphasic system. The results presented here demonstrate that Cu(0) wire-catalyzed SET-LRP can be used to target polyMnA with different block lengths and narrow molecular weight distribution at room temperature. Indeed, the use of a combination of techniques that include GPC, 1 H NMR, MALDI-TOF MS performed before and after thioetherification of bromine terminus via "thio-bromo" click chemistry, and in situ reinitiation copolymerization experiments supports the near perfect chain end functionality of the synthesized biobased hydrophobic polymers. These results expand the possibilities of SET-LRP into the area of renewable resources where hydrophobic compounds are widespread.

  7. MICROBIAL CELL-SURFACE HYDROPHOBICITY - THE INVOLVEMENT OF ELECTROSTATIC INTERACTIONS IN MICROBIAL ADHESION TO HYDROCARBONS (MATH)

    NARCIS (Netherlands)

    GEERTSEMADOORNBUSCH, GI; VANDERMEI, HC; BUSSCHER, HJ

    Microbial adhesion to hydrocarbons (MATH) is the most commonly used method to determine microbial cell surface hydrophobicity. Since, however, the assay is based on adhesion, it is questionable whether the results reflect only the cell surface hydrophobicity or an interplay of hydrophobicity and

  8. Nanoparticles modified with multiple organic acids

    Science.gov (United States)

    Cook, Ronald Lee (Inventor); Luebben, Silvia DeVito (Inventor); Myers, Andrew William (Inventor); Smith, Bryan Matthew (Inventor); Elliott, Brian John (Inventor); Kreutzer, Cory (Inventor); Wilson, Carolina (Inventor); Meiser, Manfred (Inventor)

    2007-01-01

    Surface-modified nanoparticles of boehmite, and methods for preparing the same. Aluminum oxyhydroxide nanoparticles are surface modified by reaction with selected amounts of organic acids. In particular, the nanoparticle surface is modified by reactions with two or more different carboxylic acids, at least one of which is an organic carboxylic acid. The product is a surface modified boehmite nanoparticle that has an inorganic aluminum oxyhydroxide core, or part aluminum oxyhydroxide core and a surface-bonded organic shell. Organic carboxylic acids of this invention contain at least one carboxylic acid group and one carbon-hydrogen bond. One embodiment of this invention provides boehmite nanoparticles that have been surface modified with two or more acids one of which additional carries at least one reactive functional group. Another embodiment of this invention provides boehmite nanoparticles that have been surface modified with multiple acids one of which has molecular weight or average molecular weight greater than or equal to 500 Daltons. Yet, another embodiment of this invention provides boehmite nanoparticles that are surface modified with two or more acids one of which is hydrophobic in nature and has solubility in water of less than 15 by weight. The products of the methods of this invention have specific useful properties when used in mixture with liquids, as filler in solids, or as stand-alone entities.

  9. Nanoparticles modified with multiple organic acids

    Science.gov (United States)

    Cook, Ronald Lee; Luebben, Silvia DeVito; Myers, Andrew William; Smith, Bryan Matthew; Elliott, Brian John; Kreutzer, Cory; Wilson, Carolina; Meiser, Manfred

    2007-07-17

    Surface-modified nanoparticles of boehmite, and methods for preparing the same. Aluminum oxyhydroxide nanoparticles are surface modified by reaction with selected amounts of organic acids. In particular, the nanoparticle surface is modified by reactions with two or more different carboxylic acids, at least one of which is an organic carboxylic acid. The product is a surface modified boehmite nanoparticle that has an inorganic aluminum oxyhydroxide core, or part aluminum oxyhydroxide core and a surface-bonded organic shell. Organic carboxylic acids of this invention contain at least one carboxylic acid group and one carbon-hydrogen bond. One embodiment of this invention provides boehmite nanoparticles that have been surface modified with two or more acids one of which additional carries at least one reactive functional group. Another embodiment of this invention provides boehmite nanoparticles that have been surface modified with multiple acids one of which has molecular weight or average molecular weight greater than or equal to 500 Daltons. Yet, another embodiment of this invention provides boehmite nanoparticles that are surface modified with two or more acids one of which is hydrophobic in nature and has solubility in water of less than 15 by weight. The products of the methods of this invention have specific useful properties when used in mixture with liquids, as filler in solids, or as stand-alone entities.

  10. Ag/C:F Antibacterial and hydrophobic nanocomposite coatings

    Science.gov (United States)

    Kylián, Ondřej; Kratochvíl, Jiří; Petr, Martin; Kuzminova, Anna; Slavínská, Danka; Biederman, Hynek; Beranová, Jana

    Silver-based nanomaterials that exhibit antibacterial character are intensively studied as they represent promising weapon against multi-drug resistant bacteria. Equally important class of materials represent coatings that have highly water repellent nature. Such materials may be used for fabrication of anti-fogging or self-cleaning surfaces. The aim of this study is to combine both of these valuable material characteristics. Antibacterial and highly hydrophobic Ag/C:F nanocomposite films were fabricated by means of gas aggregation source of Ag nanoparticles and sputter deposition of C:F matrix. The nanocomposite coatings had three-layer structure C:F base layer/Ag nanoparticles/C:F top layer. It is shown that the increasing number of Ag nanoparticles in produced coatings leads not only in enhancement of their antibacterial activity, but also causes substantial increase of their hydrophobicity. Under optimized conditions, the coatings are super-hydrophobic with water contact angle equal to 165∘ and are capable to induce 6-log reduction of bacteria presented in solution within 4h.

  11. Repulsive effects of hydrophobic diamond thin films on biomolecule detection

    Energy Technology Data Exchange (ETDEWEB)

    Ruslinda, A. Rahim, E-mail: ruslindarahim@gmail.com [Institute of Nano Electronic Engineering, Universiti Malaysia Perlis, Jln Kgr-Alor Setar, Seriab, 01000 Kangar, Perlis (Malaysia); Department of Nano Science and Nano Engineering, School of Advance Science and Engineering, Ohkubo 3-4-1, Shinjuku, 169-8555 Tokyo (Japan); Ishiyama, Y. [Department of Nano Science and Nano Engineering, School of Advance Science and Engineering, Ohkubo 3-4-1, Shinjuku, 169-8555 Tokyo (Japan); Penmatsa, V. [Department of Mechanical and Materials Engineering, Florida International University, 10555 West Flagler Street, Miami, FL 33174 (United States); Ibori, S.; Kawarada, H. [Department of Nano Science and Nano Engineering, School of Advance Science and Engineering, Ohkubo 3-4-1, Shinjuku, 169-8555 Tokyo (Japan)

    2015-02-15

    Highlights: • We report the effect of fluorine plasma treatment on diamond thin film to resist the nonspecific adsorption of biomolecules. • The diamond thin film were highly hydrophobic with a surface energy value of ∼25 mN/m. • The repulsive effect shows excellent binding efficiency for both DNA and HIV-1 Tat protein. - Abstract: The repulsive effect of hydrophobic diamond thin film on biomolecule detection, such as single-nucleotide polymorphisms and human immunodeficiency virus type 1 trans-activator of transcription peptide protein detection, was investigated using a mixture of a fluorine-, amine-, and hydrogen-terminated diamond surfaces. These chemical modifications lead to the formation of a surface that effectively resists the nonspecific adsorption of proteins and other biomolecules. The effect of fluorine plasma treatment on elemental composition was also investigated via X-ray photoelectron spectroscopy (XPS). XPS results revealed a fluorocarbon layer on the diamond thin films. The contact angle measurement results indicated that the fluorine-treated diamond thin films were highly hydrophobic with a surface energy value of ∼25 mN/m.

  12. Repulsive effects of hydrophobic diamond thin films on biomolecule detection

    International Nuclear Information System (INIS)

    Ruslinda, A. Rahim; Ishiyama, Y.; Penmatsa, V.; Ibori, S.; Kawarada, H.

    2015-01-01

    Highlights: • We report the effect of fluorine plasma treatment on diamond thin film to resist the nonspecific adsorption of biomolecules. • The diamond thin film were highly hydrophobic with a surface energy value of ∼25 mN/m. • The repulsive effect shows excellent binding efficiency for both DNA and HIV-1 Tat protein. - Abstract: The repulsive effect of hydrophobic diamond thin film on biomolecule detection, such as single-nucleotide polymorphisms and human immunodeficiency virus type 1 trans-activator of transcription peptide protein detection, was investigated using a mixture of a fluorine-, amine-, and hydrogen-terminated diamond surfaces. These chemical modifications lead to the formation of a surface that effectively resists the nonspecific adsorption of proteins and other biomolecules. The effect of fluorine plasma treatment on elemental composition was also investigated via X-ray photoelectron spectroscopy (XPS). XPS results revealed a fluorocarbon layer on the diamond thin films. The contact angle measurement results indicated that the fluorine-treated diamond thin films were highly hydrophobic with a surface energy value of ∼25 mN/m

  13. Double-grooved nanofibre surfaces with enhanced anisotropic hydrophobicity.

    Science.gov (United States)

    Liang, Meimei; Chen, Xin; Xu, Yang; Zhu, Lei; Jin, Xiangyu; Huang, Chen

    2017-11-02

    This study reports a facile method for fabricating double-grooved fibrous surfaces. The primary grooves of the surface are formed by aligned fibres, while the secondary grooves are achieved by oriented nanogrooves on the fibre surface. Investigation into the formation mechanism reveals that the nanogrooves can be readily tailored through adjusting the solvent ratio and relative humidity. With this understanding, a variety of polymers have been successfully electrospun into fibres having the same nanogrooved feature. These fibres show high resemblance to natural hierarchical structures, and thereby endowing the corresponding double-grooved surface with enhanced anisotropic hydrophobicity. A water droplet at a parallel direction to the grooves exhibits a much higher contact angle and a lower roll-off angle than the droplet at a perpendicular direction. The application potential of such anisotropic hydrophobicity has been demonstrated via a fog collection experiment, in which the double-grooved surface can harvest the largest amount of water. Moreover, the fabrication method requires neither post-treatment nor sophisticated equipment, making us anticipate that the double-grooved surface would be competitive in areas where a highly ordered surface, a large surface area and an anisotropic hydrophobicity are preferred.

  14. Poly thiophene hydrophobic and hydrophilic compounds, silver and iodine synthesized by plasma; Compuestos hidrofobicos e hidrofilicos de politiofeno, plata y yodo sintetizados por plasma

    Energy Technology Data Exchange (ETDEWEB)

    Palacios, J.C.; Chavez, J.A. [IIM, UNAM, Circuito exterior, Ciudad Universitaria, 04510 Coyoacan, D.F. (Mexico); Olayo, M.G.; Cruz, G.J. [ININ, Apdo. Postal 18-1027, 11801 Mexico D.F. (Mexico)

    2007-07-01

    Compounds in thin films of poly thiophene with silver and poly thiophene doped with iodine and silver using splendor discharges were synthesized. It is studied the wettability of the compounds and its transport properties. It was found that the compounds can modify their hydrophilic to hydrophobic behavior controlling their surface ruggedness and the metallic content. The doped with iodine plays a fundamental paper in the modification of the ruggedness of the compounds. (Author)

  15. Characterization of electrochemically modified polycrystalline platinum surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Krebs, L.C.; Ishida, Takanobu.

    1991-12-01

    The characterization of electrochemically modified polycrystalline platinum surfaces has been accomplished through the use of four major electrochemical techniques. These were chronoamperometry, chronopotentiommetry, cyclic voltammetry, and linear sweep voltammetry. A systematic study on the under-potential deposition of several transition metals has been performed. The most interesting of these were: Ag, Cu, Cd, and Pb. It was determined, by subjecting the platinum electrode surface to a single potential scan between {minus}0.24 and +1.25 V{sub SCE} while stirring the solution, that the electrocatalytic activity would be regenerated. As a consequence of this study, a much simpler method for producing ultra high purity water from acidic permanganate has been developed. This method results in water that surpasses the water produced by pyrocatalytic distillation. It has also been seen that the wettability of polycrystalline platinum surfaces is greatly dependent on the quantity of oxide present. Oxide-free platinum is hydrophobic and gives a contact angle in the range of 55 to 62 degrees. We have also modified polycrystalline platinum surface with the electrically conducting polymer poly-{rho}-phenylene. This polymer is very stable in dilute sulfuric acid solutions, even under applied oxidative potentials. It is also highly resistant to electrochemical hydrogenation. The wettability of the polymer modified platinum surface is severely dependent on the choice of supporting electrolyte chosen for the electrochemical polymerization. Tetraethylammonium tetrafluoroborate produces a film that is as hydrophobic as Teflon, whereas tetraethylammonium perchlorate produces a film that is more hydrophilic than oxide-free platinum.

  16. Characterization of electrochemically modified polycrystalline platinum surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Krebs, Leonard C. [State Univ. of New York (SUNY), Stony Brook, NY (United States); Ishida, Takanobu [State Univ. of New York (SUNY), Stony Brook, NY (United States)

    1991-12-01

    The characterization of electrochemically modified polycrystalline platinum surfaces has been accomplished through the use of four major electrochemical techniques. These were chronoamperometry, chronopotentiommetry, cyclic voltammetry, and linear sweep voltammetry. A systematic study on the under-potential deposition of several transition metals has been performed. The most interesting of these were: Ag, Cu, Cd, and Pb. It was determined, by subjecting the platinum electrode surface to a single potential scan between -0.24 and +1.25 VSCE while stirring the solution, that the electrocatalytic activity would be regenerated. As a consequence of this study, a much simpler method for producing ultra high purity water from acidic permanganate has been developed. This method results in water that surpasses the water produced by pyrocatalytic distillation. It has also been seen that the wettability of polycrystalline platinum surfaces is greatly dependent on the quantity of oxide present. Oxide-free platinum is hydrophobic and gives a contact angle in the range of 55 to 62 degrees. We have also modified polycrystalline platinum surface with the electrically conducting polymer poly-ρ-phenylene. This polymer is very stable in dilute sulfuric acid solutions, even under applied oxidative potentials. It is also highly resistant to electrochemical hydrogenation. The wettability of the polymer modified platinum surface is severely dependent on the choice of supporting electrolyte chosen for the electrochemical polymerization. Tetraethylammonium tetrafluoroborate produces a film that is as hydrophobic as Teflon, whereas tetraethylammonium perchlorate produces a film that is more hydrophilic than oxide-free platinum.

  17. Durable PROX catalyst based on gold nanoparticles and hydrophobic silica

    KAUST Repository

    Laveille, Paco; Guillois, Kevin; Tuel, Alain; Petit, Corine; Basset, Jean-Marie; Caps, Valerie

    2016-01-01

    3 nm gold nanoparticles (Au NP) obtained by direct chemical reduction of AuPPh3Cl in the presence of methyl-terminated silica exhibit superior durability for low temperature CO oxidation in the presence of hydrogen (PROX). The activity of hydrophobic Au/SiO2-R972 indeed appears much more stable with time-on-stream than those of the OH-terminated, hydrophilic Au/TiO2 and Au/Al2O3 catalysts, with similar Au NP size. This enhanced stability is attributed to the peculiar catalyst surface of Au/SiO2-R972. Not only may the support hydrophobicity concentrate and facilitate reactant adsorption and product desorption over Au NP, but methyl-terminated SiO2-R972 likely also inhibits carbonatation of the Au/support interface. Hence, at a temperature at which H2/H2O “cleaning” of the carbonate-contaminated Au/Al2O3 and Au/TiO2 surface is inefficient (< 100°C), passivated Au/SiO2-R972 displays much more stable PROX activity. Besides, the virtual absence of surface hydroxyl groups, which provide sites for water formation in H2/O2 atmospheres, can also account for the improved PROX selectivity (>85%) observed over Au/SiO2-R972. This new example, of CO oxidation activity of gold nanoparticles dispersed over a hydrophobic, “inert” support, clearly emphasizes the role of hydrogen as a promoter for the gold-catalyzed oxidation of CO at low temperature. Unlike support-mediated oxygen activation, hydrogen-only mediated oxygen activation takes full advantage of the hydrophobic surface, which is much more resistant against CO2 and thus remains free of poisonous carbonate species, as compared with hydroxyl-terminated catalysts. Hence, although the absence of surface hydroxyl groups prevents the hydrophobic Au/SiO2-R972 catalyst to reach the state-of-the-art activities initially displayed by Au/TiO2 and Au/Al2O3, it brings long-term stability with time-on-stream and superior selectivity, which opens up promising perspectives in the development of viable PROX catalysts based on gold.

  18. Durable PROX catalyst based on gold nanoparticles and hydrophobic silica

    KAUST Repository

    Laveille, Paco

    2016-01-20

    3 nm gold nanoparticles (Au NP) obtained by direct chemical reduction of AuPPh3Cl in the presence of methyl-terminated silica exhibit superior durability for low temperature CO oxidation in the presence of hydrogen (PROX). The activity of hydrophobic Au/SiO2-R972 indeed appears much more stable with time-on-stream than those of the OH-terminated, hydrophilic Au/TiO2 and Au/Al2O3 catalysts, with similar Au NP size. This enhanced stability is attributed to the peculiar catalyst surface of Au/SiO2-R972. Not only may the support hydrophobicity concentrate and facilitate reactant adsorption and product desorption over Au NP, but methyl-terminated SiO2-R972 likely also inhibits carbonatation of the Au/support interface. Hence, at a temperature at which H2/H2O “cleaning” of the carbonate-contaminated Au/Al2O3 and Au/TiO2 surface is inefficient (< 100°C), passivated Au/SiO2-R972 displays much more stable PROX activity. Besides, the virtual absence of surface hydroxyl groups, which provide sites for water formation in H2/O2 atmospheres, can also account for the improved PROX selectivity (>85%) observed over Au/SiO2-R972. This new example, of CO oxidation activity of gold nanoparticles dispersed over a hydrophobic, “inert” support, clearly emphasizes the role of hydrogen as a promoter for the gold-catalyzed oxidation of CO at low temperature. Unlike support-mediated oxygen activation, hydrogen-only mediated oxygen activation takes full advantage of the hydrophobic surface, which is much more resistant against CO2 and thus remains free of poisonous carbonate species, as compared with hydroxyl-terminated catalysts. Hence, although the absence of surface hydroxyl groups prevents the hydrophobic Au/SiO2-R972 catalyst to reach the state-of-the-art activities initially displayed by Au/TiO2 and Au/Al2O3, it brings long-term stability with time-on-stream and superior selectivity, which opens up promising perspectives in the development of viable PROX catalysts based on gold.

  19. Analytical study of condensation heat transfer on titanium tube with super-hydrophobic surface

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Dae Yun; Park, Hyun Gyu; Lee, Kwon Yeong [Handong Global University, Pohang (Korea, Republic of)

    2016-05-15

    There are many nuclear or fossil power plants which occupy more than 85% among entire power plants in the world. These plants release heat through condenser into nature. The condenser is an important component for cooling the working fluid after the turbine. Its performance is related with material and size of its tubes. To have good performance or to reduce condenser size, it is important to increase condensation heat transfer coefficient on condenser tubes. Ma et al. executed heat transfer experiment in dropwise condensation with non-condensable gas, and studied how the amount of air and pressure difference affect condensation heat transfer coefficient. The more non-condensable gas existed, the condensation heat transfer coefficient was decreased. Shen et al. studied condensation heat transfer at horizontal bundle tubes. Several variables such as coolant velocity, saturated pressure, and surface conditions were studied. As a result, surface modified brass tube and stainless tube showed higher condensation heat transfer coefficient as much as 1.3 and 1.4 times comparing with their bare tubes, in 70 kPa vacuum condition respectively. Rausch et al. studied dropwise condensation on ion-implanted titanium surface. Experimental study is performed to evaluate the performance of surface modified titanium tube in vacuum state. SAM coating is used to make super-hydrophobic surface of titanium tube. Preliminary analysis were performed considering filmwise and dropwise condensations, respectively. Experiment facility is almost prepared and the test result will be shown soon.

  20. Hydrophilic/hydrophobic surface modification impact on colloid lithography: Schottky-like defects, dislocation, and ideal distribution

    Science.gov (United States)

    Burtsev, Vasilii; Marchuk, Valentina; Kugaevskiy, Artem; Guselnikova, Olga; Elashnikov, Roman; Miliutina, Elena; Postnikov, Pavel; Svorcik, Vaclav; Lyutakov, Oleksiy

    2018-03-01

    Nano-spheres lithography is actually considered as a powerful tool to manufacture various periodic structures with a wide potential in the field of nano- and micro-fabrication. However, during self-assembling of colloid microspheres, various defects and mismatches can appear. In this work the size and quality of single-domains of closed-packed polystyrene (PS), grown up on thin Au layers modified by hydrophilic or hydrophobic functional groups via diazonium chemistry was studied. The effects of the surface modification on the quality and single-domain size of polystyrene (PS) microspheres array were investigated and discussed. Modified surfaces were characterized using the AFM and wettability tests. PS colloidal suspension was deposited using the drop evaporation method. Resulted PS microspheres array was characterized using the SEM, AFM and confocal microscopy technique.

  1. Two-phase synthesis of hydrophobic ionic liquid-capped gold nanoparticles and their application for sensing cholesterol

    International Nuclear Information System (INIS)

    Dong, Mingjun; Nan, Zhihan; Liu, Panpan; Zhang, Yanjun; Xue, Zhonghua; Lu, Xiaoquan; Liu, Xiuhui

    2014-01-01

    Highlights: • A novel cholesterol biosensor was constructed based on ChOx-IL-capped-AuNPs/GCE. • IL-capped-AuNPs was synthesized using two-phase synthesis and employed as a conducting matrix to immobilize ChOx. • Direct electrochemistry of ChOx on the electrode was obtained. • The ChOx-IL-capped-AuNPs/GCE exhibit remarkable performance for cholesterol detection. - Abstract: A novel scheme for fabrication of hydrophobic ionic liquid-capped gold nanoparticles (IL-capped AuNPs) modified electrode is presented and its application potential for cholesterol biosensor is investigated. Highly stable gold nanoparticles were characterized by UV–vis absorption spectroscopy and transmission electron microscopy (TEM). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) indicated that IL-capped AuNPs nanocomposites showed excellent electrical conductivity. Furthermore, cholesterol oxidase (ChOx) was directly immobilized on the IL-capped AuNPs nanocomposite, and then the direct electrochemistry of ChOx on the modified glass carbon electrode (GCE) was obtained. As a new platform in cholesterol analysis, ChOx-IL-capped AuNPs/GCE exhibited a linear response to cholesterol in the range of 0.1–50 μM with a detection limit of 0.033 μM. Therefore, hydrophobic ionic liquid-capped gold nanoparticles would serve as a good candidate material to construct the related enzyme biosensors

  2. Unexpected Rheological Behavior of Hydrophobic Associative Shellac-based Oligomeric Food Thickener.

    Science.gov (United States)

    Gao, Jianan; Li, Kun; Xu, Juan; Zhang, Wen-Wen; Ma, Jinju; Liu, Lanxiang; Sun, Yanlin; Zhang, Hong; Li, Kai

    2018-06-07

    The sodium shellac constituting of "surfactant" monomer, which is sensitive to shear stress, exhibits shear-thickening behavior at low concentration (5 wt%), and reacts with H+ to retain the transient high viscosity under shear, is introduced in this study. The appearance of the sodium shellac with different concentrations in aqueous mode also could be described. The steady-shear flow test proved that under high shear rate, sodium shellac suspension could change from Newtonian fluid to continuous shear thickening of non-Newtonian fluid. Dynamic oscillation test suggested that the sodium shellac solution at low concentration (0.1 and 1 wt%) under low shear rate represented classic viscous fluid behavior (G´´G´), and the solution at high concentration (5, 10 and 15 wt%) represented the classic the elastic gel behavior (G´´G´). Moreover, high shear rate caused a cross-linking point between G´´and G´ curve; at the low concentration, this could be the gel point and at high concentration, it could be attributed to the broken of gel. All of these transforming points were relating to the interaction between the sodium clusters. This interaction should be the hydrophobic association between the particles. In order to prove phenomenon, classic hydrophilic polymer PEO was employed as the disrupting factor to the hydrophobic association. As expected, the shear-thickening behavior vanished after mixing with PEO, which verified our assumption. On the other hand, the high viscosity of the suspension under shear could be retained by reaction with H+ to solidify the transient hydroclusters under shear, meanwhile, sodium shellac had great potential as the functional shear-thickener which could modify the rheological property of the polymer with carboxyl groups, e.g. pectin, alginate or polyacrylic acid. Thus, this natural and green thicker has great potential in food, medical gel, green adhesive, or cosmetic products.

  3. Surface hydrophobic co-modification of hollow silica nanoparticles toward large-area transparent superhydrophobic coatings.

    Science.gov (United States)

    Gao, Liangjuan; He, Junhui

    2013-04-15

    The present paper reports a novel, simple, and efficient approach to fabricate transparent superhydrophobic coatings on glass substrates by spray-coating stearic acid (STA) and 1H,1H,2H,2H-perflurooctyltriethoxysilane (POTS) co-modified hollow silica nanoparticles (SPHSNs), the surfaces of which were hydrophobic. The surface wettability of coatings was dependent on the conditions of post-treatment: the water contact angle of coating increased and then leveled off with increase in either the drying temperature or the drying time. When the coating was treated at 150°C for 5h, the water contact angle was as high as 160° and the sliding angle was lower than 1°, reaching excellent superhydrophobicity. They remained 159° and ≤1°, respectively, even after 3months storage under indoor conditions (20°C, 20%RH), demonstrating the long time stability of coating superhydrophobicity. The coating was robust both to the impact of water droplets (297 cm/s) and to acidic (pH=1) and basic (pH=14) droplets. It showed good transparency in the visible-near infrared spectral range, and the maximum transmittance reached as high as 89%. Fourier transform infrared spectroscopy, transmission electron microscopy, differential scanning calorimetry, and thermogravimetric analysis were used to investigate the interactions among STA, POTS, and hollow silica nanoparticles (HSNs). Scanning electron microscopy and atomic force microscopy were used to observe and estimate the morphology and surface roughness of coatings. Optical properties were characterized by a UV-visible-near infrared spectrophotometer. Surface wettability was studied by a contact angle/interface system. The enhancement of hydrophobicity to superhydrophobicity by post-treatment was discussed based on the transition from the Wenzel state to the Cassie state. Copyright © 2013 Elsevier Inc. All rights reserved.

  4. Microstructure and Transparent Super-Hydrophobic Performance of Vacuum Cold-Sprayed Al2O3 and SiO2 Aerogel Composite Coating

    Science.gov (United States)

    Li, Jie; Zhang, Yu; Ma, Kai; Pan, Xi-De; Li, Cheng-Xin; Yang, Guan-Jun; Li, Chang-Jiu

    2018-02-01

    In this study, vacuum cold spraying was used as a simple and fast way to prepare transparent super-hydrophobic coatings. Submicrometer-sized Al2O3 powder modified by 1,1,2,2-tetrahydroperfluorodecyltriethoxysilane and mixed with hydrophobic SiO2 aerogel was employed for the coating deposition. The deposition mechanisms of pure Al2O3 powder and Al2O3-SiO2 mixed powder were examined, and the effects of powder structure on the hydrophobicity and light transmittance of the coatings were evaluated. The results showed that appropriate contents of SiO2 aerogel in the mixed powder could provide sufficient cushioning to the deposition of submicrometer Al2O3 powder during spraying. The prepared composite coating surface showed rough structures with a large number of submicrometer convex deposited particles, characterized by being super-hydrophobic. Also, the transmittance of the obtained coating was higher than 80% in the range of visible light.

  5. Behavior of a Liquid Bridge between Nonparallel Hydrophobic Surfaces.

    Science.gov (United States)

    Ataei, Mohammadmehdi; Chen, Huanchen; Amirfazli, Alidad

    2017-12-26

    When a liquid bridge is formed between two nonparallel identical surfaces, it can move along the surfaces. Literature indicates that the direction of bridge movement is governed by the wettability of surfaces. When the surfaces are hydrophilic, the motion of the bridge is always toward the cusp (intersection of the plane of the two bounding surfaces). On the other hand, the movement is hitherto thought to be always pointing away from the cusp when the surfaces are hydrophobic. In this study, through experiments, numerical simulations, and analytical reasoning, we demonstrate that for hydrophobic surfaces, wettability is not the only factor determining the direction of the motion. A new geometrical parameter, i.e., confinement (cf), was defined as the ratio of the distance of the farthest contact point of the bridge to the cusp, and that of the closest contact point to the cusp. The direction of the motion depends on the amount of confinement (cf). When the distance between the surfaces is large (resulting in a small cf), the bridge tends to move toward the cusp through a pinning/depinning mechanism of contact lines. When the distance between the surfaces is small (large cf), the bridge tends to move away from the cusp. For a specific system, a maximum cf value (cf max ) exists. A sliding behavior (i.e., simultaneous advancing on the wider side and receding on the narrower side) can also be seen when a liquid bridge is compressed such that the cf exceeds the cf max . Contact angle hysteresis (CAH) is identified as an underpinning phenomenon that together with cf fundamentally explains the movement of a trapped liquid between two hydrophobic surfaces. If there is no CAH, however, i.e., the case of ideal hydrophobic surfaces, the cf will be a constant; we show that the bridge slides toward the cusp when it is stretched, while it slides away from the cusp when it is compressed (note sliding motion is different from motion due to pinning/depinning mechanism of contact

  6. Hydrophobicity classification of polymeric materials based on fractal dimension

    Directory of Open Access Journals (Sweden)

    Daniel Thomazini

    2008-12-01

    Full Text Available This study proposes a new method to obtain hydrophobicity classification (HC in high voltage polymer insulators. In the method mentioned, the HC was analyzed by fractal dimension (fd and its processing time was evaluated having as a goal the application in mobile devices. Texture images were created from spraying solutions produced of mixtures of isopropyl alcohol and distilled water in proportions, which ranged from 0 to 100% volume of alcohol (%AIA. Based on these solutions, the contact angles of the drops were measured and the textures were used as patterns for fractal dimension calculations.

  7. Fabrication of corona-free nanoparticles with tunable hydrophobicity.

    Science.gov (United States)

    Moyano, Daniel F; Saha, Krishnendu; Prakash, Gyan; Yan, Bo; Kong, Hao; Yazdani, Mahdieh; Rotello, Vincent M

    2014-07-22

    A protein corona is formed at the surface of nanoparticles in the presence of biological fluids, masking the surface properties of the particle and complicating the relationship between chemical functionality and biological effects. We present here a series of zwitterionic NPs of variable hydrophobicity that do not adsorb proteins at moderate levels of serum protein and do not form hard coronas at physiological serum concentrations. These particles provide platforms to evaluate nanobiological behavior such as cell uptake and hemolysis dictated directly by chemical motifs at the nanoparticle surface.

  8. Investigation of melt agglomeration process with a hydrophobic binder in combination with sucrose stearate.

    Science.gov (United States)

    Heng, Paul Wan Sia; Wong, Tin Wui; Cheong, Wai See

    2003-08-01

    The melt agglomeration process of lactose powder with hydrogenated cottonseed oil (HCO) as the hydrophobic meltable binder was investigated by studying the physicochemical properties of molten HCO modified by sucrose stearates S170, S770 and S1570. The size, size distribution, micromeritic and adhesion properties of agglomerates as well as surface tension, contact angle, viscosity and specific volume of molten HCO, with and without sucrose stearates, were examined. The viscosity, specific volume and surface tension of molten HCO were found to be modified to varying extents by sucrose stearates which are available in different HLB values and melt properties. The growth of melt agglomerates was promoted predominantly by an increase in viscosity, an increase in specific volume or a decrease in surface tension of the molten binding liquid. The agglomerate growth propensity was higher with an increase in inter-particulate binding strength, agglomerate surface wetness and extent of agglomerate consolidation which enhanced the liquid migration from agglomerate core to periphery leading to an increased surface plasticity for coalescence. The inclusion of high concentrations of completely meltable sucrose stearate S170 greatly induced the growth of agglomerates through increased specific volume and viscosity of the molten binding liquid. On the other hand, the inclusion of incompletely meltable sucrose stearates S770 and S1570 promoted the agglomeration mainly via the reduction in surface tension of the molten binding liquid with declining agglomerate growth propensity at high sucrose stearate concentrations. In addition to being an agglomeration modifier, sucrose stearate demonstrated anti-adherent property in melt agglomeration process. The properties of molten HCO and melt agglomerates were dependent on the type and concentration of sucrose stearate added.

  9. A thermochemical approach to enhance hydrophobicity of SiC/SiO{sub 2} powder using γ-methacryloxypropyl trimethoxy silane and octylphenol polyoxyethylene ether (7)

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chunxue; Feng, Dandan; Wang, Xiangke; Li, Zhihong; Zhu, Yumei, E-mail: zhuyumei@tju.edu.cn

    2016-01-01

    Graphical abstract: Through the exploration of modification mechanism, the hydrophilic properties of SiC/SiO{sub 2}-KH570-OP-7 were far superior to SiC/SiO{sub 2}-KH570. - Highlights: • A novel universal method is performed to enhance hydrophobicity of SiC/SiO{sub 2} powder. • Through pyrolysis of KH570 and OP-7, hydrophilic groups is grafted. • The hydrophobicity of SiC/SiO{sub 2}-KH570-OP-7 was far superior to SiC/SiO{sub 2}-KH570. • A possible formation mechanism of hydrophilic surface was proposed. • Surface changes on SiC/SiO{sub 2}-KH570-OP-7 powder were analyzed via SEM, FTIR, XPS. - Abstract: A thermochemical synthetic methodology for silicon carbide/silica (SiC/SiO{sub 2}) powder modified by integrating γ-methacryloxypropyl trimethoxy silane (KH570) and octylphenol polyoxyethylene ether (7) (OP-7) with hydrophilic SiC/SiO{sub 2} particles is described. On account of weak hydrophobicity of SiC/SiO{sub 2} powder modified by KH570 (SiC/SiO{sub 2}-KH570), the study focuses on the improvement of hydrophobicity utilizing alkylation reaction between OP-7 and KH570 at high temperature. Compared with using KH570 alone, SiC/SiO{sub 2} powder modified by KH570 and OP-7 (SiC/SiO{sub 2}-KH570-OP-7) shows better water resistance, and also an increased contact angle from 73.8° to 136.4°, resulting thus an improved hydrophobicity. Fourier transform infrared spectroscopy (FTIR), as well as X-ray photoelectron spectroscopy (XPS), was utilized to characterize these surfaces, and the results indicated that KH570 and OP-7 can be covalently bonded on the surface of SiC/SiO{sub 2} powder. Furthermore, it has been deeply investigated in the paper not only the possible modes of non-oxidative thermal degradation of OP-7 and KH570, but also the formation mechanism of more hydrophobic SiC/SiO{sub 2}-KH570-OP-7 powder, which probably will have a potential utility for other inorganic materials.

  10. Enhanced water transport and salt rejection through hydrophobic zeolite pores

    Science.gov (United States)

    Humplik, Thomas; Lee, Jongho; O'Hern, Sean; Laoui, Tahar; Karnik, Rohit; Wang, Evelyn N.

    2017-12-01

    The potential of improvements to reverse osmosis (RO) desalination by incorporating porous nanostructured materials such as zeolites into the selective layer in the membrane has spurred substantial research efforts over the past decade. However, because of the lack of methods to probe transport across these materials, it is still unclear which pore size or internal surface chemistry is optimal for maximizing permeability and salt rejection. We developed a platform to measure the transport of water and salt across a single layer of zeolite crystals, elucidating the effects of internal wettability on water and salt transport through the ≈5.5 Å pores of MFI zeolites. MFI zeolites with a more hydrophobic (i.e., less attractive) internal surface chemistry facilitated an approximately order of magnitude increase in water permeability compared to more hydrophilic MFI zeolites, while simultaneously fully rejecting both potassium and chlorine ions. However, our results also demonstrated approximately two orders of magnitude lower permeability compared to molecular simulations. This decreased performance suggests that additional transport resistances (such as surface barriers, pore collapse or blockages due to contamination) may be limiting the performance of experimental nanostructured membranes. Nevertheless, the inclusion of hydrophobic sub-nanometer pores into the active layer of RO membranes should improve both the water permeability and salt rejection of future RO membranes (Fasano et al 2016 Nat. Commun. 7 12762).

  11. Review: Milk Proteins as Nanocarrier Systems for Hydrophobic Nutraceuticals.

    Science.gov (United States)

    Kimpel, Florian; Schmitt, Joachim J

    2015-11-01

    Milk proteins and milk protein aggregates are among the most important nanovehicles in food technology. Milk proteins have various functional properties that facilitate their ability to carry hydrophobic nutraceutical substances. The main functional transport properties that were examined in the reviewed studies are binding of molecules or ions, surface activity, aggregation, gelation, and interaction with other polymers. Hydrophobic binding has been investigated using caseins and isolated β-casein as well as whey proteins. Surface activity of caseins has been used to create emulsion-based carrier systems. Furthermore, caseins are able to self-assemble into micelles, which can incorporate molecules. Gelation and interaction with other polymers can be used to encapsulate molecules into protein networks. The release of transported substances mainly depends on pH and swelling behavior of the proteins. The targeted use of nanocarrier systems requires specific knowledge about the binding mechanisms between the proteins and the carried substances in a certain food matrix. © 2015 Institute of Food Technologists®

  12. Synthesis of silver nanocubes in a hydrophobic binary organic solvent.

    Energy Technology Data Exchange (ETDEWEB)

    Peng, S.; Sun, Y. (Center for Nanoscale Materials)

    2010-01-01

    Synthesis of metal nanoparticles with controlled shapes in hydrophobic solvents is challenging because homogeneous nucleation with high rate in these solvents is favorable for the formation of multiply twinned (MT) nanoparticles with spherical morphology. In this work, we report an inhomogeneous nucleation strategy in a binary hydrophobic solvent mediated by dimethyldistearylammonium chloride (DDAC), resulting in the coexistence of single-crystalline Ag polyhedrons and MT Ag quasi-spheres at the beginning of the reaction. In the consequent step, the MT Ag nanoparticles are selectively etched and dissolved through oxidation by NO{sub 3}{sup -} ions (from the Ag precursor, AgNO{sub 3}) with the assistance of Cl{sup -} ions (from DDAC). The dissolved Ag species are then reduced and deposited on the more stable single-crystalline polyhedrons to form Ag nanocubes. Synergy of the oxidative etching of MT particles and growth of single-crystalline particles leads to Ag nanocubes with high purity when the ripening time is long enough. For example, refluxing a mixing solvent of octyl ether and oleylamine containing AgNO{sub 3} (0.02 M) and DDAC (0.03 M) at 260 C for 1 h results in Ag nanocubes with an average edge length of 34 nm and a purity higher than 95%.

  13. A capillary pumping device utilizing super-hydrophobic silicon grass

    International Nuclear Information System (INIS)

    Kung, Chun-Fei; Chang, Chien-Cheng; Chu, Chin-Chou

    2011-01-01

    In this study, we show that a compact silicon grass surface can be generated by utilizing the induced coupled plasma method with suitably chosen fabrication parameters. This super-hydrophobic structure suspends deionized water on top of the grass and keeps the contact angle at around 153°. The silicon grass is used to improve the driving efficiency of a capillary pumping micro-duct (without sidewalls), which is completely defined by a bottom hydrophilic stripe (adjacent to a Teflon substrate) and a fully top-covered hydrophobic Teflon surface which is coated on a glass substrate. The channel has a height of 3 µm and a width of 100 µm. In this work, the Teflon substrate is replaced with the silicon grass surface. When the fluid is flowing through the micro-duct on the stripe, the interface between the silicon grass and the hydrophilic stripe forms a stable air cushion barrier to the fluid, thus effectively reducing the frictional force. By changing only the interface with this replacement, we demonstrate that the average measured velocities of the new design show improvements of 21% and 17% in the driving efficiency over the original design for transporting deionized water and human blood, respectively. It is also shown that the measured data of the present design are closer to the values predicted by a theoretical analysis which relates the flow velocity to the contact angles, surface tension and fluid viscosity

  14. Hydrophobicity and thermodynamic response for aqueous solutions of amphiphiles

    Science.gov (United States)

    Zemánková, Katerina; Troncoso, Jacobo; Cerdeiriña, Claudio A.; Romaní, Luis; Anisimov, Mikhail A.

    2016-06-01

    The anomalous behavior of aqueous solutions of amphiphiles in the water-rich region is analyzed via a phenomenological approach that utilizes the isobaric heat capacity Cp as an experimental probe. We report extensive data for solutions of 14 amphiphiles as a function of temperature at atmospheric pressure. Beyond that, Cp data but also isobaric thermal expansivities and isothermal compressibilities for three solutions of tert-butanol as a function of both temperature and pressure are presented. Results rule out the possibility that the observed phenomenology is associated with the anomalous thermodynamics of pure water. Indeed, our Cp data, quantitatively consistent with recent spectroscopic analyses, suggest that water-mediated interactions between the nonpolar parts of amphiphiles are at the origin of anomalies, with the effects of such "hydrophobic aggregation" being observed at mole fractions as small as 0.01. Physicochemical details like the size, the electronic charge distribution and the geometry of amphiphile molecules as well as third-order derivatives of the Gibbs energy and the associated Koga lines support the above claims while they further contribute to characterizing the role of hydrophobicity in these phenomena. Progress with a view to gain a deeper, more concrete understanding remains.

  15. Enhanced water transport and salt rejection through hydrophobic zeolite pores.

    Science.gov (United States)

    Humplik, Thomas; Lee, Jongho; O'Hern, Sean; Laoui, Tahar; Karnik, Rohit; Wang, Evelyn N

    2017-12-15

    The potential of improvements to reverse osmosis (RO) desalination by incorporating porous nanostructured materials such as zeolites into the selective layer in the membrane has spurred substantial research efforts over the past decade. However, because of the lack of methods to probe transport across these materials, it is still unclear which pore size or internal surface chemistry is optimal for maximizing permeability and salt rejection. We developed a platform to measure the transport of water and salt across a single layer of zeolite crystals, elucidating the effects of internal wettability on water and salt transport through the ≈5.5 Å pores of MFI zeolites. MFI zeolites with a more hydrophobic (i.e., less attractive) internal surface chemistry facilitated an approximately order of magnitude increase in water permeability compared to more hydrophilic MFI zeolites, while simultaneously fully rejecting both potassium and chlorine ions. However, our results also demonstrated approximately two orders of magnitude lower permeability compared to molecular simulations. This decreased performance suggests that additional transport resistances (such as surface barriers, pore collapse or blockages due to contamination) may be limiting the performance of experimental nanostructured membranes. Nevertheless, the inclusion of hydrophobic sub-nanometer pores into the active layer of RO membranes should improve both the water permeability and salt rejection of future RO membranes (Fasano et al 2016 Nat. Commun. 7 12762).

  16. Hydrophobicity studies of polymer thin films with varied CNT concentration

    Science.gov (United States)

    M. Rodzi, N. H.; M. Shahimin, M.; Poopalan, P.; Man, B.; M. Nor, M. N.

    2013-12-01

    Surface functionalization studies for re-creating a `Lotus Leaf' effect (superhydrophobic) have been carried out for the past decade; looking for the material which can provide high transparency, low energy surface and high surface roughness. Fabrication of polydimethylsiloxane (PDMS) and multiwalled carbon nanotubes (MWCNT) hybrid thin film variations on glass to produce near-superhydrophobic surfaces is presented in this paper. There are three important parameters studied in producing hydrophobic surfaces based on the hybrid thin films; concentration of PDMS, concentration of MWCNT and droplet sizes. The study is carried out by using PDMS of varied cross linker ratio (10:1, 30:1 and 50:1) with MWCNT concentration of 1mg, 10mg and 15mg for 0.5 μl, 2.0 μl, 5.0 μl and 10 μl droplet sizes. The resulting hybrid thin films show that hydrophobicity increased with increasing cross linker ratio and MWCNT percentage in the PDMS solution. A near superhydrophobic surface can be created when using 15 mg of MWCNT with 50:1 cross linker ratio PDMS thin films, measured on 10 μl droplet size. The hybrid thin films produced can be potentially tailored to the application of biosensors, MEMS and even commercial devices.

  17. EWOD driven cleaning of bioparticles on hydrophobic and superhydrophobic surfaces.

    Science.gov (United States)

    Jönsson-Niedziółka, M; Lapierre, F; Coffinier, Y; Parry, S J; Zoueshtiagh, F; Foat, T; Thomy, V; Boukherroub, R

    2011-02-07

    Environmental air monitoring is of great interest due to the large number of people concerned and exposed to different possible risks. From the most common particles in our environment (e.g. by-products of combustion or pollens) to more specific and dangerous agents (e.g. pathogenic micro-organisms), there are a large range of particles that need to be controlled. In this article we propose an original study on the collection of electrostatically deposited particles using electrowetting droplet displacement. A variety of particles were studied, from synthetic particles (e.g. Polystyrene Latex (PSL) microsphere) to different classes of biological particle (proteins, bacterial spores and a viral simulant). Furthermore, we have compared ElectroWetting-On-Dielectric (EWOD) collecting efficiency using either a hydrophobic or a superhydrophobic counter electrode. We observe different cleaning efficiencies, depending on the hydrophobicity of the substrate (varying from 45% to 99%). Superhydrophobic surfaces show the best cleaning efficiency with water droplets for all investigated particles (MS2 bacteriophage, BG (Bacillus atrophaeus) spores, OA (ovalbumin) proteins, and PSL).

  18. Hydrophobic Collapse of Ubiquitin Generates Rapid Protein-Water Motions.

    Science.gov (United States)

    Wirtz, Hanna; Schäfer, Sarah; Hoberg, Claudius; Reid, Korey M; Leitner, David M; Havenith, Martina

    2018-06-04

    We report time-resolved measurements of the coupled protein-water modes of solvated ubiquitin during protein folding. Kinetic terahertz absorption (KITA) spectroscopy serves as a label-free technique for monitoring large scale conformational changes and folding of proteins subsequent to a sudden T-jump. We report here KITA measurements at an unprecedented time resolution of 500 ns, a resolution 2 orders of magnitude better than those of any previous KITA measurements, which reveal the coupled ubiquitin-solvent dynamics even in the initial phase of hydrophobic collapse. Complementary equilibrium experiments and molecular simulations of ubiquitin solutions are performed to clarify non-equilibrium contributions and reveal the molecular picture upon a change in structure, respectively. On the basis of our results, we propose that in the case of ubiquitin a rapid (<500 ns) initial phase of the hydrophobic collapse from the elongated protein to a molten globule structure precedes secondary structure formation. We find that these very first steps, including large-amplitude changes within the unfolded manifold, are accompanied by a rapid (<500 ns) pronounced change of the coupled protein-solvent response. The KITA response upon secondary structure formation exhibits an opposite sign, which indicates a distinct effect on the solvent-exposed surface.

  19. Study and application of hydrophobic catalyst in treating tritium waste

    International Nuclear Information System (INIS)

    Dan, Gui-ping; Zhang, Dong; Qiu, Yong-mei; Yuan, Guo-Qi

    2008-01-01

    Tritium decontamination from tritium waste is important for the management of tritium waste. Tritium removal from waste tritium oxide can not only get tritium, but also reduce the amount of waste tritium. At the meantime, by cleaning the tritium pollution gas can also reduce the tritium exhausting from tritium facility. At present, the process of hydrogen isotopic exchange in tritium removal from waste tritium oxide and coordination oxidisation-adsorption in tritium cleaning from waste tritium gas are the mainly methods. In these methods, hydrophobic catalysts which can be used in these process are the key technology. There are many references about their preparing and applying, but few on the estimation about their performance changing during their applying. However, their performance stability on isotopic catalytic exchange and catalytic oxidisation will affect their using in reaction. Hydrophobic catalyst Pt-SDB which can be used in tritium isotopic exchange between tritium oxide and hydrogen and the cleaning of tritium pollution gas have been prepared in our laboratory in early days. In order to estimating their performance stability during their using, this work will investigate their stability on their catalytic activity and their radiation-resistance tritium. (author)

  20. Acid-degradable and bioerodible modified polyhydroxylated materials

    Energy Technology Data Exchange (ETDEWEB)

    Frechet, Jean M. J.; Bachelder, Eric M.; Beaudette, Tristan T.; Broaders, Kyle E.

    2017-05-09

    Compositions and methods of making a modified polyhydroxylated polymer comprising a polyhydroxylated polymer having reversibly modified hydroxyl groups, whereby the hydroxyl groups are modified by an acid-catalyzed reaction between a polydroxylated polymer and a reagent such as acetals, aldehydes, vinyl ethers and ketones such that the modified polyhydroxylated polymers become insoluble in water but freely soluble in common organic solvents allowing for the facile preparation of acid-sensitive materials. Materials made from these polymers can be made to degrade in a pH-dependent manner. Both hydrophobic and hydrophilic cargoes were successfully loaded into particles made from the present polymers using single and double emulsion techniques, respectively. Due to its ease of preparation, processability, pH-sensitivity, and biocompatibility, of the present modified polyhydroxylated polymers should find use in numerous drug delivery applications.

  1. Mechanical Degradation Onset of Polyethylene Oxide Used as a Hydrosoluble Model Polymer for Enhanced Oil Recovery Seuil de dégradation mécanique de solutions de polymères utilisés en récupération assistée des hydrocarbures

    Directory of Open Access Journals (Sweden)

    Dupas A.

    2013-02-01

    Full Text Available Water soluble polymers such as polyacrylamide are used in polymer flooding, which is an advanced technique of Enhanced Oil Recovery (EOR. It aims at improving crude oil displacement in reservoir by pushing it with a viscous injected fluid. Polymer flood is challenged by mechanical degradation of long macromolecules during intense flows. Many studies reported that above a critical extensional rate hbox{$varepsilon^{mathrm{cdot }}_{mathrm{c}}$} ε c · , polymer chains can break and lose their rheological properties. The molecular weight (M dependence of hbox{$varepsilon^{mathrm{cdot }}_{mathrm{c}}$} ε c · for dilute solutions in laminar flows was shown to follow a power law: hbox{$varepsilon^{mathrm{cdot }}_{mathrm{c}}$} ε c · ≈ Mw–k. An experimental study has been performed to investigate the onset of mechanical degradation in both laminar and turbulent flows and for both dilute and semi dilute polyethylene oxide aqueous solutions. It reveals that the exponent k strongly depends on the concentration and flow regimes and also on solvent quality. Results show that mechanical degradation mainly affects long chains, that it is favoured at high concentrations, under poor solvent conditions. They also evidence that the extensional viscosity at low strain rates decreases to the same extent as shear viscosities due to mechanical degradation. However, the decrease of the extensional viscous properties at high strain rates is much more pronounced. Les polymères hydrosolubles comme les polyacrylamides peuvent être utilisés en récupération assistée des hydrocarbures (Enhanced Oil Recovery (EOR par injection de polymère. Cette technique vise à augmenter la production de brut en le poussant du réservoir vers un puits producteur à l’aide d’une solution de polymère suffisamment visqueuse. Les polymères utilisés à cet effet ont des masses moléculaires supérieures à 106 g/mol, ce qui les rend sensibles à la dégradation. En raison

  2. Extraction and Hydrophobic Modification of Cotton Stalk Bark Fiber

    Directory of Open Access Journals (Sweden)

    Ya-Yu Li

    2016-01-01

    Full Text Available Cotton stalk bark fiber (CSBF was extracted at high temperature and under high pressure, under the condition of the alkali content of 11 wt%. Experimental results proved that the extraction yield of CSBF was 27.3 wt%, and the residual alkali concentration was 2.1 wt%. Then five kinds of modifiers including methyl methacrylate (MMA, MMA plus initiator, epoxy propane, copper ethanolamine, and silane coupling agent were chosen to modify the surface of CSBF. It was found by measuring water retention value (WRV that these five kinds of modifiers were all effective and the silane coupling agent was best modifier among all. The optimal modifying conditions of silane coupling agent were obtained: modifier concentration was 5%, the mixing temperature was 20°C, the mixing time was 1 h, and vacuum drying time was 1 h. Under the optimal condition, the WRV of the modified CSBF was 89%. It is expected that these modified CSBF may be a filler with strengthening effect in wood plastic composites (WPC fields.

  3. How microorganisms use hydrophobicity and what does this mean for human needs?

    Directory of Open Access Journals (Sweden)

    Anna eKrasowska

    2014-08-01

    Full Text Available Cell surface hydrophobicity (CSH plays a crucial role in the attachment to, or detachment from the surfaces. The influence of CSH on adhesion of microorganisms to biotic and abiotic surfaces in medicine as well as in bioremediation and fermentation industry has both negative and positive aspects. Hydrophobic microorganisms cause the damage of surfaces by biofilm formation; on the other hand, they can readily accumulate on organic pollutants and decompose them. Hydrophilic microorganisms also play a considerable role in removing organic wastes from the environment because of their high resistance to hydrophobic chemicals. Despite the many studies on the environmental and metabolic factors affecting cell surface hydrophobicity (CSH, the knowledge of this subject is still scanty and is in most cases limited to observing the impact of hydrophobicity on adhesion, aggregation or flocculation. The future of research seems to lie in finding a way to managing the microbial adhesion process, perhaps by steering cell hydrophobicity.

  4. Enhanced the hydrophobic surface and the photo-activity of TiO2-SiO2 composites

    Science.gov (United States)

    Wahyuni, S.; Prasetya, A. T.

    2017-02-01

    The aim of this research is to develop nanomaterials for coating applications. This research studied the effect of various TiO2-SiO2 composites in acrylic paint to enhance the hydrophobic properties of the substrate. Titanium dioxide containing silica in the range 20-35 mol% has been synthesized using sol-gel route. The XRD’s spectra show that increasing SiO2 content in the composite, decreasing its crystalline properties but increasing the surface area. TiO2-SiO2 composite was dispersed in acrylic paint in 2% composition by weight. The largest contact angle was 70, which produced by the substrate coated with TS-35-modified acrylic paint. This study also investigated the enhanced photo-activity of TiO2-SiO2 modified with poly-aniline. The XRD spectra show that the treatment does not change the crystal structure of TiO2. The photo-activity of the composite was evaluated by degradation of Rhodamine-B with visible light. The best performance of the degradation process was handled by the composite treated with 0.1mL anilines per gram of TiO2-SiO2 composite (TSP-A). On the other side, the contact angle 70 has not shown an excellent hydrophobic activity. However, the AFM spectra showed that nanoroughness has started to form on the surface of acrylic paint modified with TiO2-SiO2 than acrylic alone.

  5. Fabrication of Robust Super hydrophobic Bamboo Based on ZnO Nano sheet Networks with Improved Water-, UV-, and Fire-Resistant Properties

    International Nuclear Information System (INIS)

    Li, J.; Sun, Q.; Yao, Q.; Wang, J.; Han, Sh.; Jin, Ch.

    2014-01-01

    Bamboo with water-resistant, UV-resistant, and fire-resistant properties was desirable in modern society. In this paper, the original bamboo was firstly treated with ZnO sol and then hydrothermally the ZnO nano sheet networks grow onto the bamboo surface and subsequently modified with fluoro alkyl silane (FAS-17). The FAS-17 treated bamboo substrate exhibited not only robust super hydrophobicity with a high contact angle of 161° but also stable repellency towards simulated acid rain (ph = 3) with a contact angle of 152°. Except for its robust super hydrophobicity, such a bamboo also presents superior water-resistant, UV-resistant, and fire-resistant properties.

  6. Preparation of hydrophobic Pt-catalysts for decontamination of nuclear effluents

    International Nuclear Information System (INIS)

    Ionita, Gh.; Popescu, I.; Retegan, T.; Stefanescu, I.

    2005-01-01

    Based on the long experience of the authors, in the preparation, testing and evaluation of the performances of hydrophobic catalysts, and based on the reviewed references, this paper presents up-to-date R and D activities on the preparation methods and applications of the hydrophobic catalysts, in deuterium and tritium separation. The objectives of the paper are: (1) to provide a database for selection of the most appropriate catalyst and catalytic packing for above mentioned processes, (2) to evaluate the potentiality of hydrophobic Pt-catalysts in the deuterium and tritium separation (3) to asses and to find a new procedure for preparation a new improved hydrophobic catalyst. The merits of the hydrophobic catalysts are shown in comparison to hydrophilic catalysts. As results of the review some general conclusions about the applications of hydrophobic catalysts in environmental field are as follow: (1) the hydrophobic Pt-catalysts packed in the trickle bed reactors showed a high catalytic activity and long stability; (2) the utilization of the hydrophobic Pt-catalysts for tritium removal from liquid and gaseous effluent in nuclear field was entirely confirmed on industrial scale; (3) the extension of the utilization of the hydrophobic Pt-catalysts in other new processes, which take place in presence of liquid water or high humidity are subjected to testing. (author)

  7. Preparation of hydrophobic Pt-catalysts for decontamination of nuclear effluents

    International Nuclear Information System (INIS)

    Ionita, Gh.; Popescu, I.; Retegan, T.; Stefanescu, I.

    2004-01-01

    Based on the long experience of the authors, in the preparation, testing and evaluation of the performances of hydrophobic catalysts, and based on the reviewed references, this paper presents up-to-date R and D activities on the preparation methods and applications of the hydrophobic catalysts, in deuterium and tritium separation. The objectives of the paper are: - to provide a database for selection of the most appropriate catalyst and catalytic packing for above mentioned processes; - to evaluate the potentiality of hydrophobic Pt-catalysts in the deuterium and tritium separation; - to assess and to find a new procedure for preparation a new improved hydrophobic catalyst. The merits of the hydrophobic catalysts are shown in comparison to hydrophilic catalysts. As results of the review some general conclusions about the applications of hydrophobic catalysts in environmental field are as follows: - the hydrophobic Pt-catalysts packed in the trickle bed reactors showed a high catalytic activity and long stability; - the utilization of the hydrophobic Pt-catalysts for tritium removal from liquid and gaseous effluent in nuclear field was entirely confirmed on industrial scale; - the extension of the utilization of the hydrophobic Pt-catalysts in other new processes, which take place in presence of liquid water or high humidity are subject to testing. (authors)

  8. Current status for applications of hydrophobic platinum catalysts in tritium removal from nuclear effluents

    International Nuclear Information System (INIS)

    Vagner, Irina; Ionita, Gheorghe; Varlam, Carmen

    2008-01-01

    Full text: Based on the long experience of the authors, in the preparation, testing and evaluation of the performances of hydrophobic catalysts, and based on the reviewed references, this paper presents up-to-date R and D results on the preparation methods and applications of the hydrophobic catalysts, in deuterium and tritium separation. The objectives of the paper are: 1. to provide a database for selection of the most appropriate catalyst and catalytic packing for above mentioned processes; 2. to evaluate the potentiality of hydrophobic Pt-catalysts in the deuterium and tritium separation; 3. to assess and find a new procedure for preparation of a new improved hydrophobic catalyst. The merits of the hydrophobic catalysts are shown in comparison to hydrophilic catalysts. As results of the review some general conclusions about the applications of hydrophobic catalysts in environmental field are as follow: 1. the hydrophobic Pt-catalysts packed in the trickle bed reactors showed a high catalytic activity and long stability; 2. the utilization of the hydrophobic Pt-catalysts for tritium removal from liquid and gaseous effluent in nuclear field was entirely confirmed on industrial scale; 3. the extension of the utilization of the hydrophobic Pt-catalysts to other new processes, which take place in presence of liquid water or high humidity, like VOCs oxidation from wastewater or H 2 -O 2 catalytic recombination, are subject to testing

  9. Synthesis of biocompatible hydrophobic silica-gelatin nano-hybrid by sol-gel process.

    Science.gov (United States)

    Smitha, S; Shajesh, P; Mukundan, P; Nair, T D R; Warrier, K G K

    2007-03-15

    Silica-biopolymer hybrid has been synthesised using colloidal silica as the precursor for silica and gelatin as the biopolymer counterpart. The surface modification of the hybrid material has been done with methyltrimethoxysilane leading to the formation of biocompatible hydrophobic silica-gelatin hybrid. Here we are reporting hydrophobic silica-gelatin hybrid and coating precursor for the first time. The hybrid gel has been evaluated for chemical modification, thermal degradation, hydrophobicity, particle size, transparency under the UV-visible region and morphology. FTIR spectroscopy has been used to verify the presence of CH(3) groups which introduce hydrophobicity to the SiO2-MTMS-gelatin hybrids. The hydrophobic property has also been tailored by varying the concentration of methyltrimethoxysilane. Contact angle by Wilhelmy plate method of transparent hydrophobic silica-gelatin coatings has been found to be as high as approximately 95 degrees . Oxidation of the organic group which induces the hydrophobic character occurs at 530 degrees C which indicates that the surface hydrophobicity is retained up to that temperature. Optical transmittance of SiO2-MTMS-gelatin hybrid coatings on glass substrates has been found to be close to 100% which will enable the hybrid for possible optical applications and also for preparation of transparent biocompatible hydrophobic coatings on biological substrates such as leather.

  10. Frictional forces between hydrophilic and hydrophobic particle coated nanostructured surfaces

    DEFF Research Database (Denmark)

    Hansson, Petra M; Claesson, Per M.; Swerin, Agne

    2013-01-01

    Friction forces have long been associated with the famous Amontons' rule that states that the friction force is linearly dependent on the applied normal load, with the proportionality constant being known as the friction coefficient. Amontons' rule is however purely phenomenological and does...... not in itself provide any information on why the friction coefficient is different for different material combinations. In this study, friction forces between a colloidal probe and nanostructured particle coated surfaces in an aqueous environment exhibiting different roughness length scales were measured...... by utilizing the atomic force microscope (AFM). The chemistry of the surfaces and the probe was varied between hydrophilic silica and hydrophobized silica. For hydrophilic silica surfaces, the friction coefficient was significantly higher for the particle coated surfaces than on the flat reference surface. All...

  11. Effect of hydrophobic microstructured surfaces on conductive ink printing

    International Nuclear Information System (INIS)

    Kim, Seunghwan; Kang, Hyun Wook; Lee, Kyung Heon; Sung, Hyung Jin

    2011-01-01

    Conductive ink was printed on various microstructured substrates to measure the printing quality. Poly-dimethylsiloxane (PDMS) substrates were used to test the printability of the hydrophobic surface material. Microstructured arrays of 10 µm regular PDMS cubes were prepared using the MEMS fabrication technique. The gap distance between the cubes was varied from 10 to 40 µm. The printing wettability of the microstructured surfaces was determined by measuring the contact angle of a droplet of silver conductive ink. Screen-printing methods were used in the conductive line printing experiment. Test line patterns with finely varying widths (30–250 µm) were printed repeatedly, and the conductivity of the printed lines was measured. The printability, which was defined as the ratio of the successfully printed patterns to the total number of printed patterns, was analyzed as a function of the linewidth and the gap distance of the microstructured surfaces

  12. Harvesting electrostatic energy using super-hydrophobic surfaces

    Science.gov (United States)

    Pociecha, Dominik; Zylka, Pawel

    2016-11-01

    Almost all environments are now being extensively populated by miniaturized, nano-powered electronic sensor devices communicated together through wireless sensor networks building Internet of Things (IoT). Various energy harvesting techniques are being more and more frequently proposed for battery-less powering of such remote, unattended, implantable or wearable sensors or other low-power electronic gadgets. Energy harvesting relays on extracting energy from the ambient sources readily accessible at the sensor location and converting it into electrical power. The paper exploits possibility of generating electric energy safely accessible for nano-power electronics using tribo-electric and electrostatic induction phenomena displayed at super-hydrophobic surfaces impinged by water droplets. Mechanism of such interaction is discussed and illustrated by experimental results.

  13. Thermodynamics of water intrusion in nanoporous hydrophobic solids.

    Science.gov (United States)

    Cailliez, Fabien; Trzpit, Mickael; Soulard, Michel; Demachy, Isabelle; Boutin, Anne; Patarin, Joël; Fuchs, Alain H

    2008-08-28

    We report a joint experimental and molecular simulation study of water intrusion in silicalite-1 and ferrerite zeolites. The main conclusion of this study is that water condensation takes place through a genuine first-order phase transition, provided that the interconnected pores structure is 3-dimensional. In the extreme confinement situation (ferrierite zeolite), condensation takes place through a continuous transition, which is explained by a shift of both the first-order transition line and the critical point with increasing confinement. The present findings are at odds with the common belief that conventional phase transitions cannot take place in microporous solids such as zeolites. The most important features of the intrusion/extrusion process can be understood in terms of equilibrium thermodynamics considerations. We believe that these findings are very general for hydrophobic solids, i.e. for both nonwetting as well as wetting water-solid interface systems.

  14. Fabrication of superhydrophobic cotton fabrics by silica hydrosol and hydrophobization

    Science.gov (United States)

    Xu, Lihui; Zhuang, Wei; Xu, Bi; Cai, Zaisheng

    2011-04-01

    Superhydrophobic cotton fabrics were prepared by the incorporation of silica nanoparticles and subsequent hydrophobization with hexadecyltrimethoxysilane (HDTMS). The silica nanoparticles were synthesized via sol-gel reaction with methyl trimethoxy silane (MTMS) as the precursor in the presence of the base catalyst and surfactant in aqueous solution. As for the resulting products, characterization by particle size analyzer, scanning electron microscopy (SEM), scanning probe microscopy (SPM), X-ray photoelectron spectroscopy (XPS), and thermal gravimetric analysis (TGA) were performed respectively. The size of SiO2 nanoparticles can be controlled by adjusting the catalyst and surfactant concentrations. The wettability of cotton textiles was evaluated by the water contact angle (WCA) and water shedding angle (WSA) measurements. The results showed that the treated cotton sample displayed remarkable water repellency with a WCA of 151.9° for a 5 μL water droplet and a WSA of 13° for a 15 μL water droplet.

  15. Neutron structure of the hydrophobic plant protein crambin

    International Nuclear Information System (INIS)

    Teeter, M.M.; Kossiakoff, A.A.

    1982-01-01

    Crystals of the small hydrophobic protein crambin have been shown to diffract to a resolution of at least 0.88 A. This means that crambin presents a rare opportunity to study a protein structure at virtually atomic resolution. The high resolution of the diffraction pattern coupled with the assets of neutron diffraction present the distinct possibility that crambin's analysis may surpass that of any other protein system in degree and accuracy of detail. The neutron crambin structure is currently being refined at 1.50 A (44.9% of the data to 1.2 A has also been included). It is expected that a nominal resolution of 1.0 A can be achieved. 15 references, 6 figures, 2 tables

  16. Evaporation of Nanosuspensions on Substrates with Different Hydrophobicity.

    Science.gov (United States)

    Perrin, Lionel; Pajor-Swierzy, Anna; Magdassi, Shlomo; Kamyshny, Alexander; Ortega, Francisco; Rubio, Ramón G

    2018-01-24

    Liquid drop evaporation on surfaces is present in many industrial and medical applications, e.g., printed electronics, spraying of pesticides, DNA mapping, etc. Despite this strong interest, a theoretical description of the dynamic of the evaporation of complex liquid mixtures and nanosuspensions is still lacking. Indeed, one of the aspects that have not been included in the current theoretical descriptions is the competition between the kinetics of evaporation and the adsorption of surfactants and/or particles at the liquid/vapor and liquid/solid interfaces. Materials formed by an electrically isolating solid on which a patterned conducting layer was formed by the deposits left after drop evaporation have been considered as very promising for building electrical circuits on flexible plastic substrates. In this work, we have done an exhaustive study of the evaporation of nanosuspensions of latex and hydrophobized silver nanoparticles on four substrates of different hydrophobicity. The advancing and receding contact angles as well as the time dependence of the volume of the droplets have been measured over a broad range of particle concentrations. Also, mixtures of silver particles and a surfactant, commonly used in industrial printing, have been examined. Furthermore, the adsorption kinetics at both the air/liquid and solid/liquid interfaces have been measured. Whereas the latex particles do not adsorb at the solid/liquid and only slightly reduce the surface tension, the silver particles strongly adsorb at both interfaces. The experimental results of the evaporation process were compared with the predictions of the theory of Semenov et al. (Evaporation of Sessile Water Droplets: Universal Behavior in the Presence of Contact Angle Hysteresis. Colloids Surf. Physicochem. Eng. Asp. 2011, 391 (1-3), 135-144) and showed surprisingly good agreement despite that the theory was developed for pure liquids. The morphology of the deposits left by the droplets after total

  17. Polyurethane-acrylate-based hydrophobic film: Facile fabrication, characterization, and application

    Science.gov (United States)

    Park, Jongsung; Nguyen, Bui Quoc Huy; Kim, Ji-Kwan; Shanmugasundaram, Arunkumar; Lee, Dong-Weon

    2018-06-01

    Polyurethane-acrylate (PUA) is a versatile UV-curable polymer with a short curing time at room temperature, whose surface structure can be flexibly modified by applying various micropatterns. In this paper, we propose a facile and cost-effective fabrication method for the continuous production of an optically transparent PUA-based superhydrophobic thin film. Poly(dimethylsiloxane) (PDMS) was employed as a soft mold for the fabrication of PUA films through the roll-to-roll technique. In addition, nanosilica was spray-coated onto the PUA surface to further improve the hydrophobicity. The fabricated PUA thin film showed the highest static water contact angle (WCA) of ∼140°. The high durability of the PUA film was also demonstrated through mechanical impacting tests. Furthermore, only ∼2% of voltage loss was observed in the solar panel covered with the PUA-based superhydrophobic film. These obtained results indicate the feasibility of applying the film as a protective layer in applications requiring a high transparency and a self-cleaning effect.

  18. Hydrophobic Janus Foam Motors: Self-Propulsion and On-The-Fly Oil Absorption

    Directory of Open Access Journals (Sweden)

    Xiaofeng Li

    2018-01-01

    Full Text Available In this work, we for the first time have proposed and fabricated a self-propelled Janus foam motor for on-the-fly oil absorption on water by simply loading camphor/stearic acid (SA mixture as fuels into one end of the SA-modified polyvinyl alcohol (PVA foam. The as-fabricated Janus foam motors show an efficient Marangoni effect-based self-propulsion on water for a long lifetime due to the effective inhibition of the rapid release of camphor by the hydrophobic SA in the fuel mixture. Furthermore, they can automatically search, capture, and absorb oil droplets on the fly, and then be spontaneously self-assembled after oil absorption due to the self-propulsion of the motors as well as the attractive capillary interactions between the motors and oil droplets. This facilitates the subsequent collection of the motors from water after the treatment. Since the as-developed Janus foam motors can effectively integrate intriguing behaviors of the self-propulsion, efficient oil capture, and spontaneous self-assembly, they hold great promise for practical applications in water treatment.

  19. Characterization and Antibiofouling Performance Investigation of Hydrophobic Silver Nanocomposite Membranes: A Comparative Study.

    Science.gov (United States)

    Amouamouha, Maryam; Badalians Gholikandi, Gagik

    2017-11-12

    Biofouling is one of the drawbacks restricting the industrial applications of membranes. In this study, different thicknesses of silver nanoparticles with proper adhesion were deposited on poly(vinylidenefluoride) (PVDF) and polyethersulfone (PES) surfaces by physical vapor deposition (PVD). The crystalline and structural properties of modified and pure membranes were investigated by carrying out X-ray diffraction (XRD) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Scanning electron microscope (SEM) and atomic force microscopy (AFM) analyses were employed to examine the surface morphology and the bacteria anti-adhesion property of the membranes. The morphology measurements confirmed that even though after silver grafting the surface became more hydrophobic, the homogeneity increased and the flux reduction decreased after coating. Moreover a comparison between PVDF and PES revealed that CFU (colony forming units) reduced 64.5% on PVDF surface and 31.1% on PES surface after modification. In conclusion, PVD improved the performance of the membrane antibiofouling, and it is more promising to be used for PVDF rather than PES.

  20. Laser texturing of Hastelloy C276 alloy surface for improved hydrophobicity and friction coefficient

    Science.gov (United States)

    Yilbas, B. S.; Ali, H.

    2016-03-01

    Laser treatment of Hastelloy C276 alloy is carried out under the high pressure nitrogen assisting gas environment. Morphological and metallurgical changes in the laser treated layer are examined using the analytical tools including, scanning electron and atomic force microscopes, X-ray diffraction, energy dispersive spectroscopy, and Fourier transform infrared spectroscopy. Microhardness is measured and the residual stress formed in the laser treated surface is determined from the X-ray data. The hydrophibicity of the laser treated surface is assessed using the sessile drop method. Friction coefficient of the laser treated layer is obtained incorporating the micro-tribometer. It is found that closely spaced laser canning tracks create a self-annealing effect in the laser treated layer and lowers the thermal stress levels through modifying the cooling rates at the surface. A dense structure, consisting of fine size grains, enhances the microhardness of the surface. The residual stress formed at the surface is compressive and it is in the order of -800 MPa. Laser treatment improves the surface hydrophobicity significantly because of the formation of surface texture composing of micro/nano-pillars.

  1. Enhanced fluorescence imaging performance of hydrophobic colloidal ZnO nanoparticles by a facile method

    International Nuclear Information System (INIS)

    Zang, Zhigang; Tang, Xiaosheng

    2015-01-01

    Highlights: • A dual phase hydrothermal method was developed to synthesize ZnO nanoparticles. • ZnO nanoparticles show a stability and solubility in the aqueous environment. • ZnO nanoparticles with a blue emission wavelength at around 420 nm and small size (30 nm). • ZnO nanoparticles as biological labeling agent was also shown. - Abstract: A facile synthesis method for the formation of ZnO nanoparticles by using a double-phase reaction was demonstrated in this paper. The morphology of the synthesized ZnO nanoparticles shows a flower-shape. Hydrogen peroxide was used as a unique oxygenic source to promote the formation of ZnO in the presence of organic zinc precursor. The as-synthesized ZnO nanoparticles also show a stability and solubility in the aqueous environment. The structure and properties of ZnO nanoparticles were investigated by the transmission electron microscopy (TEM) and X-ray diffraction (XRD) as well as UV–vis and photoluminescence spectroscopy. The as-prepared hydrophobic colloidal ZnO nanoparticles could be modified to become water-soluble via ligand exchange with amineothanethiol⋅HCl while retaining the photoluminescence properties. In addition, the potential application for biological label of water-soluble ZnO nanoparticles were also demonstrated. These results not only have applications towards using colloidal ZnO nanoparticles effectively in biological fluorescence imaging, but also promote its application in the field of targeted drug delivery

  2. The Five Ws (and one H of Super-Hydrophobic Surfaces in Medicine

    Directory of Open Access Journals (Sweden)

    Francesco Gentile

    2014-05-01

    Full Text Available Super-hydrophobic surfaces (SHSs are bio-inspired, artificial microfabricated interfaces, in which a pattern of cylindrical micropillars is modified to incorporate details at the nanoscale. For those systems, the integration of different scales translates into superior properties, including the ability of manipulating biological solutions. The five Ws, five Ws and one H or the six Ws (6W, are questions, whose answers are considered basic in information-gathering. They constitute a formula for getting the complete story on a subject. According to the principle of the six Ws, a report can only be considered complete if it answers these questions starting with an interrogative word: who, why, what, where, when, how. Each question should have a factual answer. In what follows, SHSs and some of the most promising applications thereof are reviewed following the scheme of the 6W. We will show how these surfaces can be integrated into bio-photonic devices for the identification and detection of a single molecule. We will describe how SHSs and nanoporous silicon matrices can be combined to yield devices with the capability of harvesting small molecules, where the cut-off size can be adequately controlled. We will describe how this concept is utilized for obtaining a direct TEM image of a DNA molecule.

  3. The five Ws (and one H) of super-hydrophobic surfaces in medicine

    KAUST Repository

    Gentile, F.

    2014-05-05

    Super-hydrophobic surfaces (SHSs) are bio-inspired, artificial microfabricated interfaces, in which a pattern of cylindrical micropillars is modified to incorporate details at the nanoscale. For those systems, the integration of different scales translates into superior properties, including the ability of manipulating biological solutions. The five Ws, five Ws and one H or the six Ws (6W), are questions, whose answers are considered basic in information-gathering. They constitute a formula for getting the complete story on a subject. According to the principle of the six Ws, a report can only be considered complete if it answers these questions starting with an interrogative word: who, why, what, where, when, how. Each question should have a factual answer. In what follows, SHSs and some of the most promising applications thereof are reviewed following the scheme of the 6W. We will show how these surfaces can be integrated into bio-photonic devices for the identification and detection of a single molecule. We will describe how SHSs and nanoporous silicon matrices can be combined to yield devices with the capability of harvesting small molecules, where the cut-off size can be adequately controlled. We will describe how this concept is utilized for obtaining a direct TEM image of a DNA molecule. 2014 by the authors; licensee MDPI, Basel, Switzerland.

  4. Direct synthesis of hydrophobic graphene-based nanosheets via chemical modification of exfoliated graphene oxide.

    Science.gov (United States)

    Wang, Jigang; Wang, Yongsheng; He, Dawei; Liu, Zhiyong; Wu, Hongpeng; Wang, Haiteng; Zhao, Yu; Zhang, Hui; Yang, Bingyang; Xu, Haiteng; Fu, Ming

    2012-08-01

    Hydrophobic graphene-based material at the nanoscale was prepared by treatment of exfoliated graphene oxide with organic isocyanates. The lipophilic modified graphene oxide (LMGO) can then be exfoliated into the functionalized graphene nanoplatelets that can form a stable dispersion in polar aprotic solvents. AFM image shows the thickness of LMGO is approximately 1 nm. Characterization of LMGO by elemental analysis suggested that the chemical treatment results in the functionalization of the carboxyl and hydroxyl groups in GO via formation of amides and carbamate esters, respectively. The degree of GO functionalization can be controlled via either the reactivity of the isocyanate or the reaction time. Then we investigated the thermal properties of the SPFGraphene by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), the TGA curve shows a greater weight loss of approximately 20% occurred indicating removal of functional groups from the LMGO sheets and an obvious exothermic peak at 176 degrees can be observed from 150 to 250 degrees. We also compared the structure of graphene oxide with the structure of chemical treated graphene oxide by FT-IR spectroscopy. The morphology and microstructure of the LMGO nanosheets were also characterized by SEM and XRD. Graphene can be used to fabricate a wide range of simple electronic devices such as field-effect transistors, resonators, quantum dots and some other extensive industrial manufacture such as super capacitor, li ion battery, solar cells and even transparent electrodes in device applications.

  5. Characterization and Antibiofouling Performance Investigation of Hydrophobic Silver Nanocomposite Membranes: A Comparative Study

    Directory of Open Access Journals (Sweden)

    Maryam Amouamouha

    2017-11-01

    Full Text Available Biofouling is one of the drawbacks restricting the industrial applications of membranes. In this study, different thicknesses of silver nanoparticles with proper adhesion were deposited on poly(vinylidenefluoride (PVDF and polyethersulfone (PES surfaces by physical vapor deposition (PVD. The crystalline and structural properties of modified and pure membranes were investigated by carrying out X-ray diffraction (XRD and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR. Scanning electron microscope (SEM and atomic force microscopy (AFM analyses were employed to examine the surface morphology and the bacteria anti-adhesion property of the membranes. The morphology measurements confirmed that even though after silver grafting the surface became more hydrophobic, the homogeneity increased and the flux reduction decreased after coating. Moreover a comparison between PVDF and PES revealed that CFU (colony forming units reduced 64.5% on PVDF surface and 31.1% on PES surface after modification. In conclusion, PVD improved the performance of the membrane antibiofouling, and it is more promising to be used for PVDF rather than PES.

  6. Adsorption of human fibrinogen and albumin onto hydrophobic and hydrophilic Ti6Al4V powder

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez-Sánchez, Jesús; Gallardo-Moreno, Amparo M.; Bruque, José M.; González-Martín, M. Luisa, E-mail: mlglez@unex.es

    2016-07-15

    Adsorption of proteins on solid surfaces has been widely studied because of its importance in various biotechnological, medical and technical applications, such as medical implants or biosensors. One of the main problems is the adsorption-induced conformational changes because they often modify the biological activity of the proteins, which is believed to be a key factor on the subsequent cellular adhesion. The aim of this work is the study of the adsorption of human fibrinogen (Fg) and human serum albumin (HSA) onto Ti6Al4V particles, commercially available on different size, that are used to elaborate scaffolds to provide structural support to cell proliferation, promoting tissue development and bone regeneration among others. The study was done through the analysis of the adsorption isotherms and the electrical characterization of surfaces after adsorption in terms of the zeta potential (ζ). From this analysis it seems that Fg adsorbs preferentially vertically oriented (end-on) and HSA moves sequentially over the surface of the Ti6Al4V particles through dimmer formation, allowing adsorption progress over this initial bilayer. The zeta potential values of both proteins remain constant when the monolayer is formed. The study also extends the analysis of both adsorption behaviour and ζ potential characterization factors to the influence of the substrate hydrophobicity as this property can be modified for the Ti6Al4V by irradiating it with ultraviolet light (UV-C) without changes on its chemical composition [1,2]. Differences at low protein concentrations were found for both isotherms and zeta-potential values.

  7. Selective on site separation and detection of molecules in diluted solutions with super-hydrophobic clusters of plasmonic nanoparticles

    KAUST Repository

    Gentile, Francesco T.; Coluccio, Maria Laura; Proietti Zaccaria, Remo; Francardi, Marco; Cojoc, Gheorghe; Perozziello, Gerardo; Raimondo, Raffaella; Candeloro, Patrizio; Di Fabrizio, Enzo M.

    2014-01-01

    Super-hydrophobic surfaces are bio-inspired interfaces with a superficial texture that, in its most common evolution, is formed by a periodic lattice of silicon micro-pillars. Similar surfaces reveal superior properties compared to conventional flat surfaces, including very low friction coefficients. In this work, we modified meso-porous silicon micro-pillars to incorporate networks of metal nano-particles into the porous matrix. In doing so, we obtained a multifunctional-hierarchical system in which (i) at a larger micrometric scale, the super-hydrophobic pillars bring the molecules dissolved in an ultralow-concentration droplet to the active sites of the device, (ii) at an intermediate meso-scale, the meso-porous silicon film adsorbs the low molecular weight content of the solution and, (iii) at a smaller nanometric scale, the aggregates of silver nano-particles would measure the target molecules with unprecedented sensitivity. In the results, we demonstrated how this scheme can be utilized to isolate and detect small molecules in a diluted solution in very low abundance ranges. The presented platform, coupled to Raman or other spectroscopy techniques, is a realistic candidate for the protein expression profiling of biological fluids. © 2014 the Partner Organisations.

  8. Towards increased selectivity of drug delivery to cancer cells: development of a LDL-based nanodelivery system for hydrophobic photosensitizers

    Science.gov (United States)

    Buzova, Diana; Huntosova, Veronika; Kasak, Peter; Petrovajova, Dana; Joniova, Jaroslava; Dzurova, Lenka; Nadova, Zuzana; Sureau, Franck; Midkovsky, Pavol; Jancura, Daniel

    2012-10-01

    Low-density lipoproteins (LDL), a natural in vivo carrier of cholesterol in the vascular system, play a key role in the delivery of hydrophobic photosensitizers (pts) to tumor cells in photodynamic therapy (PDT) of cancer. To make this delivery system even more efficient, we have constructed a nano-delivery system by coating of LDL surface by polyethylene glycol (PEG) and dextran. Fluorescence spectroscopy and confocal fluorescence imaging were used to characterize redistribution of hypericin (Hyp), a natural potent pts, loaded in LDL/PEG and LDL/dextran complexes to free LDL molecules as well as to monitor cellular uptake of Hyp by U87-MG cells. It was shown than the redistribution process of Hyp between LDL molecules is significantly suppressed by dextran coating of LDL surface. On the other hand, PEG does not significantly influence this process. The modification of LDL molecules by the polymers does not inhibit their recognition by cellular LDL receptors. U-87 MG cellular uptake of Hyp loaded in LDL/PEG and LDL/dextran complexes appears to be similar to that one observed for Hyp transported by unmodified LDL particles. It is proposed that by polymers modified LDL molecules could be used as a basis for construction of a drug transport system for targeted delivery of hydrophobic drugs to cancer cells expressing high level of LDL receptors.

  9. Development of a new LDL-based transport system for hydrophobic/amphiphilic drug delivery to cancer cells.

    Science.gov (United States)

    Huntosova, Veronika; Buzova, Diana; Petrovajova, Dana; Kasak, Peter; Nadova, Zuzana; Jancura, Daniel; Sureau, Franck; Miskovsky, Pavol

    2012-10-15

    Low-density lipoproteins (LDL), a natural in vivo carrier of cholesterol in the vascular system, play a key role in the delivery of hydrophobic/amphiphilic photosensitizers to tumor cells in photodynamic therapy of cancer. To make this delivery system even more efficient, we have constructed a nano-delivery system by coating of LDL surface by dextran. Fluorescence spectroscopy, confocal fluorescence imaging, stopped-flow experiments and flow-cytometry were used to characterize redistribution of hypericin (Hyp), a natural occurring potent photosensitizer, loaded in LDL/dextran complex to free LDL molecules as well as to monitor cellular uptake of Hyp by U87-MG cells. It is shown that the redistribution process of Hyp between LDL molecules is significantly suppressed by dextran coating of LDL surface. The modification of LDL molecules by dextran does not inhibit their recognition by cellular LDL receptors and U-87 MG cellular uptake of Hyp loaded in LDL/dextran complex appears to be similar to that one observed for Hyp transported by unmodified LDL particles. Thus, it is proposed that dextran modified LDL molecules could be used as a basis for construction of a drug transport system for targeted delivery of hydrophobic/amphiphilic drugs to cancer cells expressing high level of LDL receptors. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Facile phase transfer of hydrophobic nanoparticles with poly(ethylene glycol) grafted hyperbranched poly(amido amine)

    International Nuclear Information System (INIS)

    Ji Minglei; Yang Wuli; Ren Qingguang; Lu Daru

    2009-01-01

    In order to enhance the dispersion ability of hydrophobic nanoparticles in water while maintaining their unique properties, we utilized poly(ethylene glycol) grafted hyperbranched poly(amido amine) (h-PAMAM-g-PEG) to modify three types of hydrophobic nanoparticle, CdSe, Au, and Fe 3 O 4 , and transferred them into water to extend their applications in biology. Considering the large amounts of amino groups in hyperbranched poly(amido amine) (h-PAMAM) polymer, complexation interaction between h-PAMAM-g-PEG copolymer and nanoparticles was achieved and ligand exchange between the copolymers and original small molecules ligands occurred. The transferred nanoparticles could be easily dispersed in water with better stability, and their unique properties, such as fluorescence, surface plasmon resonance, and superparamagnetism, were well maintained in the ligand exchange process. In addition, increasing the number of grafted PEG showed a negative effect on the ligand exchange process. Due to the existence of h-PAMAM-g-PEG ligands, the stabilized nanoparticles have improved stability in aqueous and ionic solutions. In the case of CdSe nanoparticles, the h-PAMAM-g-PEG layer leads to a lower cytotoxicity when compared with bare CdSe particles, and they could be directly used in bioimaging.

  11. Dielectric properties of modified graphene oxide filled polyurethane nanocomposites and its correlation with rheology

    NARCIS (Netherlands)

    Sadasivuni, K.K.; Ponnamma, D.; Kumar, B.; Strankowski, M.; Cardinaels, R.M.; Moldenaers, P.; Thomas, S.; Grohens, Y.

    2014-01-01

    This study aims at investigating the dynamic mechanical, dielectric and rheological properties of reinforced polyurethane (PU) nanocomposites containing hydrophilic graphene oxide (GO) and/or hydrophobic modified graphene oxide (mGO) sheets. The organic modification of GO was performed with

  12. Preparation and characterization of the nanocomposites from chemically modified nanocellulose and poly(lactic acid)

    Science.gov (United States)

    Liqing Wei; Shupin Luo; Armando G. McDonald; Umesh P. Agarwal; Kolby C. Hirth; Laurent M. Matuana; Ronald C. Sabo; Nicole M. Stark

    2017-01-01

    Cellulose nanocrystals (CNCs) are renewable and sustainable filler for polymeric nanocomposites. However, their high hydrophilicity limits their use with hydrophobic polymer for composite materials. In this study, freeze-dried CNCs were modified by transesterification with canola oil fatty acid methyl ester to reduce the hydrophilicity. The transesterified CNCs (CNCFE...

  13. Reference interaction site model with hydrophobicity induced density inhomogeneity: An analytical theory to compute solvation properties of large hydrophobic solutes in the mixture of polyatomic solvent molecules

    International Nuclear Information System (INIS)

    Cao, Siqin; Sheong, Fu Kit; Huang, Xuhui

    2015-01-01

    Reference interaction site model (RISM) has recently become a popular approach in the study of thermodynamical and structural properties of the solvent around macromolecules. On the other hand, it was widely suggested that there exists water density depletion around large hydrophobic solutes (>1 nm), and this may pose a great challenge to the RISM theory. In this paper, we develop a new analytical theory, the Reference Interaction Site Model with Hydrophobicity induced density Inhomogeneity (RISM-HI), to compute solvent radial distribution function (RDF) around large hydrophobic solute in water as well as its mixture with other polyatomic organic solvents. To achieve this, we have explicitly considered the density inhomogeneity at the solute-solvent interface using the framework of the Yvon-Born-Green hierarchy, and the RISM theory is used to obtain the solute-solvent pair correlation. In order to efficiently solve the relevant equations while maintaining reasonable accuracy, we have also developed a new closure called the D2 closure. With this new theory, the solvent RDFs around a large hydrophobic particle in water and different water-acetonitrile mixtures could be computed, which agree well with the results of the molecular dynamics simulations. Furthermore, we show that our RISM-HI theory can also efficiently compute the solvation free energy of solute with a wide range of hydrophobicity in various water-acetonitrile solvent mixtures with a reasonable accuracy. We anticipate that our theory could be widely applied to compute the thermodynamic and structural properties for the solvation of hydrophobic solute

  14. Deuterium exchange reaction in a trickle bed packed with a mixture of hydrophobic catalyst and hydrophilic packings

    International Nuclear Information System (INIS)

    Seungwoo Paek; Heui-Joo Choi; DO-Hee Ahn; Kwang-Rag Kim; Minsoo Lee; Sung-Paal Yim; Hongsuk Chung

    2006-01-01

    Full text of publication follows: The isotopic exchange reaction between hydrogen and water on the platinum supported catalysts provides a useful step for separating hydrogen isotopes such as deuterium and tritium. The CECE (Combined Electrolysis Catalytic Exchange) with a hydrophobic catalyst is a very effective method to remove small quantities of tritium from light or heavy waste water streams because of its high separation factor and mild operating conditions. The CECE column is composed of an electrolysis cell and a liquid phase catalytic exchange column. This paper deals with the experiments for the hydrogen isotopic exchange reaction in a trickle bed reactor packed with a hydrophobic catalyst in order to develop the catalytic column of the CECE. Hydrophobic Pt/SDBC catalyst which has been developed for the LPCE column of WTRF (Wolsong Tritium Removal Facility) was tested in a trickle bed reactor. The catalyst column was packed with a mixture of hydrophobic catalyst and hydrophilic packing (Dixon gauze ring) to improve liquid distribution and vapor/liquid transfer area. An experimental apparatus was built for the test of the catalyst at various temperatures and gas velocities. The catalyst was packed wet into the column and water was injected at the top through a liquid distributor and trickled through a catalyst mixture. Hydrogen gas passed up the column and deuterium was transferred to water stream flowing counter currently. The temperature of the column was controlled to maintain at 60 deg. C using water jackets around the reactor and equilibrator, a feed waster heater, and a circulation water heater. A metal bellows pump was used to circulate the hydrogen gas at the typical flow rate of 60 LPM.The reactor pressure was controlled to maintain at 135 kPa (abs) by a water column. Gas samples were drawn off from the top and bottom of the column. The difference in deuterium concentration between the inlet and outlet gas samples was analyzed using Gas

  15. Deuterium exchange reaction in a trickle bed packed with a mixture of hydrophobic catalyst and hydrophilic packings

    Energy Technology Data Exchange (ETDEWEB)

    Seungwoo Paek [KAERI (Korea, Republic of); Heui-Joo Choi; DO-Hee Ahn; Kwang-Rag Kim; Minsoo Lee; Sung-Paal Yim; Hongsuk Chung

    2006-07-01

    Full text of publication follows: The isotopic exchange reaction between hydrogen and water on the platinum supported catalysts provides a useful step for separating hydrogen isotopes such as deuterium and tritium. The CECE (Combined Electrolysis Catalytic Exchange) with a hydrophobic catalyst is a very effective method to remove small quantities of tritium from light or heavy waste water streams because of its high separation factor and mild operating conditions. The CECE column is composed of an electrolysis cell and a liquid phase catalytic exchange column. This paper deals with the experiments for the hydrogen isotopic exchange reaction in a trickle bed reactor packed with a hydrophobic catalyst in order to develop the catalytic column of the CECE. Hydrophobic Pt/SDBC catalyst which has been developed for the LPCE column of WTRF (Wolsong Tritium Removal Facility) was tested in a trickle bed reactor. The catalyst column was packed with a mixture of hydrophobic catalyst and hydrophilic packing (Dixon gauze ring) to improve liquid distribution and vapor/liquid transfer area. An experimental apparatus was built for the test of the catalyst at various temperatures and gas velocities. The catalyst was packed wet into the column and water was injected at the top through a liquid distributor and trickled through a catalyst mixture. Hydrogen gas passed up the column and deuterium was transferred to water stream flowing counter currently. The temperature of the column was controlled to maintain at 60 deg. C using water jackets around the reactor and equilibrator, a feed waster heater, and a circulation water heater. A metal bellows pump was used to circulate the hydrogen gas at the typical flow rate of 60 LPM.The reactor pressure was controlled to maintain at 135 kPa (abs) by a water column. Gas samples were drawn off from the top and bottom of the column. The difference in deuterium concentration between the inlet and outlet gas samples was analyzed using Gas

  16. Influence of the solubilization of ribonuclease and of its hydrophobic derivatives on water-in-oil microemulsions

    International Nuclear Information System (INIS)

    Michel, Fabienne

    1993-01-01

    This research thesis addresses the study of the structural disruption of a water-in-oil microemulsion during the solubilization of an enzyme. More precisely, the microemulsion is the water/isooctane system, stabilised by the commonly named AOT anionic surfactant, and the disrupting agent is an enzymatic protein, ribonuclease A. The author addresses the following topics: interactions in microemulsion, percolation in microemulsion, use of microemulsions as micro-reactor, chemical modification of enzymes, and reactivity of enzymes. After a recall of the main results concerning AOT inverse micelles, the author addresses the influence of ribonuclease solubilisation on the micellar system. The micellar environment is then used as a micro-reactor in order to fix hydrophobic molecules in a covalent way onto the ribonuclease A, and then to promote the percolation process. The author then studies the structure of the microemulsion in presence of modified enzymes [fr

  17. Carbon dioxide solubilities in decanoic acid-based hydrophobic deep eutectic solvents

    NARCIS (Netherlands)

    Zubeir, Lawien F.; Van Osch, Dannie J.G.P.; Rocha, Marisa A.A.; Banat, Fawzi; Kroon, Maaike C.

    2018-01-01

    The solubility of CO2 in hydrophobic deep eutectic solvents (DESs) has been measured for the first time. Six different hydrophobic DESs are studied in the temperature range from 298 to 323 K and at CO2 pressures up to 2 MPa. The results are evaluated by comparing the solubility data with existing

  18. Characterizing time-dependent contact angles for sands hydrophobized with oleic and stearic acids

    DEFF Research Database (Denmark)

    Subedi, S; Kawamoto, K; Jayarathna, L

    2012-01-01

    -frequency precipitation. A potential solution is to alter soil grain surfaces to become water repellent by mixing or coating the soil cover material with hydrophobic agents (HAs). In this study, hydrophobic CBs comprised of sands mixed with environmentally friendly HAs (oleic acid [OA] and stearic acid [SA]) were studied...

  19. Tuning hydrophobicity of zein nanoparticles to control rheological behavior of Pickering emulsions

    NARCIS (Netherlands)

    Zou, Yuan; Baalen, van Carlijn; Yang, Xiaoquan; Scholten, E.

    2018-01-01

    In the present work, the influence of hydrophobicity of zein/tannic acid complex particles (ZTPs) on the rheological behavior of ZTP-stabilized emulsion gels is described. The hydrophobicity of the particles was controlled by the incorporation of different amounts of hydrophilic tannic acid, while

  20. Influence of cosolvents on the hydrophobic surface immobilization topography of Candida antarctica lipase B

    Science.gov (United States)

    The presence of cosolvents and co-solutes during the immobilization of lipases on hydrophobic supports may influence the extent of lipase immobilization and the long-term catalytic stability of the biocatalyst. Candida antarctica B lipase immobilization was examined on a hydrophobic surface, i.e., ...

  1. Synthesis of hydrophobic peptides : An Fmoc “Solubilising Tail” method

    NARCIS (Netherlands)

    Choma, Christin T.; Robillard, George T.; Englebretsen, Darren R.

    1998-01-01

    The development of an Fmoc method for synthesis and purification of hydrophobic peptides using a “solubihsing tail” strategy is described. Peptide-constructs of the form hydrophobic peptide-[CHmb ester]-solubilising peptide were synthesised. Procedures for forming the 4-Hmb ester linkage, and

  2. Molecular dynamics simulations of the hydrophobin SC3 at a hydrophobic/hydrophilic interface

    NARCIS (Netherlands)

    Fan, Hao; Wang, Xiaoqin; Zhu, Jiang; Robillard, George T.; Mark, Alan E.

    2006-01-01

    Hydrophobins are small (similar to 100 aa) proteins that have an important role in the growth and development of mycelial fungi. They are surface active and, after secretion by the fungi, self-assemble into amphipathic membranes at hydrophobic/hydrophilic interfaces, reversing the hydrophobicity of

  3. Premicellar interaction of PEO-PPO-PEO triblock copolymers with partially hydrophobic alcohols: NMR study

    Czech Academy of Sciences Publication Activity Database

    Kříž, Jaroslav; Dybal, Jiří

    2013-01-01

    Roč. 51, č. 5 (2013), s. 275-282 ISSN 0749-1581 R&D Projects: GA ČR GAP205/11/1657; GA ČR GA203/09/1478 Institutional support: RVO:61389013 Keywords : pluronics * hydrophobic interaction * hydrophobic alcohols Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.559, year: 2013

  4. Medicinal utility of boron clusters. Receptor modulators bearing carborane as a hydrophobic pharmacophore

    International Nuclear Information System (INIS)

    Endo, Y.; Iijima, T.; Yaguchi, K.; Yoshimi, T.; Yamakoshi, Y.; Kawachi, E.; Kagechika, H.

    2000-01-01

    The hydrophobic character and spherical geometry of carboranes may allow their use as a hydrophobic pharmacophore in biologically active molecules. We report potent cellular nuclear receptor ligands with carborane such as retinoids and estrogens. These receptor ligands raise the possibility for therapeutic agents, and their membrane transport characteristics and concentration in cellular nucleus may provide potential use for BNCT. (author)

  5. Human Gastric Mucosal Hydrophobicity Does dot Decrease with Helicobacter Pylori Infection or Chronological Age

    Directory of Open Access Journals (Sweden)

    Mohammed S Al-Marhoon

    2005-01-01

    Full Text Available BACKGROUND AND AIMS: Infection with cytotoxin-associated gene A (cagA Helicobacter pylori is associated with severe gastric diseases. Previous studies in humans have reported a decreased gastric hydrophobicity with H pylori infection. The aim of the present study was to differentiate between the effect of cagA+ and cagA- strains on gastric mucus hydrophobicity.

  6. Fabricating Super-hydrophobic Polydimethylsiloxane Surfaces by a Simple Filler-Dissolved Process

    Science.gov (United States)

    Lin, Yung-Tsan; Chou, Jung-Hua

    2010-12-01

    The self-cleaning effect of super-hydrophobic surfaces has attracted the attention of researchers. Typical ways of manufacturing super-hydrophobic surfaces include the use of either dedicated equipment or a complex chemical process. In this study, a simple innovative filler-dissolved method is developed using mainly powder salt and rinsing to form hydrophobic surfaces. This method can produce large super-hydrophobic surfaces with porous and micro rib surface structures. It can also be applied to curved surfaces, including flexible membranes. The contact angle of the manufactured artificial hydrophobic surface is about 160°. Furthermore, water droplets roll off the surface readily at a sliding angle of less than 5°, resembling the nonwetting lotus like effect.

  7. Subnanomolar Sensitivity of Filter Paper-Based SERS Sensor for Pesticide Detection by Hydrophobicity Change of Paper Surface.

    Science.gov (United States)

    Lee, Minwoo; Oh, Kyudeok; Choi, Han-Kyu; Lee, Sung Gun; Youn, Hye Jung; Lee, Hak Lae; Jeong, Dae Hong

    2018-01-26

    As a cost-effective approach for detecting trace amounts of pesticides, filter paper-based SERS sensors have been the subject of intensive research. One of the hurdles to overcome is the difficulty of retaining nanoparticles on the surface of the paper because of the hydrophilic nature of the cellulose fibers in paper. This reduces the sensitivity and reproducibility of paper-based SERS sensors due to the low density of nanoparticles and short retention time of analytes on the paper surface. In this study, filter paper was treated with alkyl ketene dimer (AKD) to modify its property from hydrophilic to hydrophobic. AKD treatment increased the contact angle of the aqueous silver nanoparticle (AgNP) dispersion, which consequently increased the density of AgNPs. The retention time of the analyte was also increased by preventing its rapid absorption into the filter paper. The SERS signal was strongly enhanced by the increased number of SERS hot spots owing to the increased density of AgNPs on a small contact area of the filter surface. The reproducibility and sensitivity of the SERS signal were optimized by controlling the distribution of AgNPs on the surface of the filter paper by adjusting the concentration of the AgNP solution. Using this SERS sensor with a hydrophobicity-modified filter paper, the spot-to-spot variation of the SERS intensity of 25 spots of 4-aminothiophenol was 6.19%, and the limits of detection of thiram and ferbam as test pesticides were measured to be 0.46 nM and 0.49 nM, respectively. These proof-of-concept results indicate that this paper-based SERS sensor can serve for highly sensitive pesticide detection with low cost and easy fabrication.

  8. Development of Water Detritiation Process Using the Hydrophobic Platinum Catalyst

    International Nuclear Information System (INIS)

    Ahn, D.H.; Paek, S.; Choi, H.J.; Kim, K.R.; Chung, H.; Yim, S.P.; Lee, M.S.

    2006-01-01

    Radioactive emissions and occupational doses by tritium are mainly caused by tritiated water escaping from equipment in the nuclear industry. Improving the leak-tightness of equipment is effective in reducing emissions and internal dose but is not a long-term solution. Water detritiation was consider to be the most effective tritium control option since tritium is removed right from the source. The WTRF (Wolsong Tritium Removal Facility) is under construction now with the completion date of June, 2006 in Korea. It is designed to remove tritium from tritiated heavy water in each of the existing four Candu units at Wolsong site. We developed a hydrophobic platinum catalyst (Pt/SDBC catalyst) that would be used at the LPCE (Liquid Phase Catalytic Exchange) column in the WTRF. The catalytic rate constants of the newly developed catalyst for the deuterium exchange reaction between water vapor and hydrogen gas were measured in a recycle reactor. The catalytic rate constants of the Pt/SDBC catalyst decreased with reaction time and were much greater than that required, 2.0 x 10 -4 mol (D 2 )/s/g(pellet) in the design of the WTRF. Tritium removal efficiency of the WTRF, which is important for a safe and reliable operation of the facility, depends on the design and operating variables. A theoretical model based on the design and operating variables of the LPCE process was set up, and the equations between the parameters were derived. Numerical calculation result from a computer program shows steep increase of the detritiation factor of the LPCE process with respect to temperature increase and mild increase with respect to pressure decrease. The other parametric study shows that the calculated detritiation factors increase as the catalyst efficiency, number of theoretical stages of hydrophilic packing, the detritiation factor of cryogenic distillation system and the total number of sections increase. We also proceeded with the experiments for the hydrogen isotopic exchange

  9. Hydrophobic environment is a key factor for the stability of thermophilic proteins.

    Science.gov (United States)

    Gromiha, M Michael; Pathak, Manish C; Saraboji, Kadhirvel; Ortlund, Eric A; Gaucher, Eric A

    2013-04-01

    The stability of thermophilic proteins has been viewed from different perspectives and there is yet no unified principle to understand this stability. It would be valuable to reveal the most important interactions for designing thermostable proteins for such applications as industrial protein engineering. In this work, we have systematically analyzed the importance of various interactions by computing different parameters such as surrounding hydrophobicity, inter-residue interactions, ion-pairs and hydrogen bonds. The importance of each interaction has been determined by its predicted relative contribution in thermophiles versus the same contribution in mesophilic homologues based on a dataset of 373 protein families. We predict that hydrophobic environment is the major factor for the stability of thermophilic proteins and found that 80% of thermophilic proteins analyzed showed higher hydrophobicity than their mesophilic counterparts. Ion pairs, hydrogen bonds, and interaction energy are also important and favored in 68%, 50%, and 62% of thermophilic proteins, respectively. Interestingly, thermophilic proteins with decreased hydrophobic environments display a greater number of hydrogen bonds and/or ion pairs. The systematic elimination of mesophilic proteins based on surrounding hydrophobicity, interaction energy, and ion pairs/hydrogen bonds, led to correctly identifying 95% of the thermophilic proteins in our analyses. Our analysis was also applied to another, more refined set of 102 thermophilic-mesophilic pairs, which again identified hydrophobicity as a dominant property in 71% of the thermophilic proteins. Further, the notion of surrounding hydrophobicity, which characterizes the hydrophobic behavior of residues in a protein environment, has been applied to the three-dimensional structures of elongation factor-Tu proteins and we found that the thermophilic proteins are enriched with a hydrophobic environment. The results obtained in this work highlight the

  10. Optical-Electrical-Chemical Engineering of PEDOT:PSS by Incorporation of Hydrophobic Nafion for Efficient and Stable Perovskite Solar Cells.

    Science.gov (United States)

    Ma, Shuang; Qiao, Wenyuan; Cheng, Tai; Zhang, Bing; Yao, Jianxi; Alsaedi, Ahmed; Hayat, Tasawar; Ding, Yong; Tan, Zhan'ao; Dai, Songyuan

    2018-01-31

    In PIN-type perovskite solar cells (PSCs), the hydroscopicity and acidity of the poly(3,4-ethylenedioxythiophene)-poly(styrene-sulfonate) (PEDOT:PSS) hole transport layer (HTL) have critical influences on the device stability. To eliminate these problems, Nafion, the hydrophobic perfluorosulfonic copolymer, is incorporated into PEDOT:PSS by a simple spin-coating process. For the modified film, Nafion/PSSH (poly(styrene sulfonate) acid) acts as an electron-blocking layer on the surface and the PEDOT-rich domain tends to gather into larger particles with better interchain charge transfer inside the film. Consequently, the modified PEDOT:PSS HTL shows enhanced conductivity and light transmittance as well as more favorable work function, ending up with the increased short-circuit current density (J sc ) and open-circuit voltage (V oc ) of the device. Finally, PSCs with Nafion-modified HTLs achieve the best power conversion efficiency of 16.72%, with 23.76% improvement compared with PEDOT:PSS-only devices (13.51%). Most importantly, the device stability is obviously enhanced because of the hydrophobicity and chemical and mechanical stability of the Nafion polymer that is enriched on the surface of the PEDOT:PSS film.

  11. Mechanisms of water infiltration into conical hydrophobic nanopores.

    Science.gov (United States)

    Liu, Ling; Zhao, Jianbing; Yin, Chun-Yang; Culligan, Patricia J; Chen, Xi

    2009-08-14

    Fluid channels with inclined solid walls (e.g. cone- and slit-shaped pores) have wide and promising applications in micro- and nano-engineering and science. In this paper, we use molecular dynamics (MD) simulations to investigate the mechanisms of water infiltration (adsorption) into cone-shaped nanopores made of a hydrophobic graphene sheet. When the apex angle is relatively small, an external pressure is required to initiate infiltration and the pressure should keep increasing in order to further advance the water front inside the nanopore. By enlarging the apex angle, the pressure required for sustaining infiltration can be effectively lowered. When the apex angle is sufficiently large, under ambient condition water can spontaneously infiltrate to a certain depth of the nanopore, after which an external pressure is still required to infiltrate more water molecules. The unusual involvement of both spontaneous and pressure-assisted infiltration mechanisms in the case of blunt nanocones, as well as other unique nanofluid characteristics, is explained by the Young's relation enriched with the size effects of surface tension and contact angle in the nanoscale confinement.

  12. Dynamically slow processes in supercooled water confined between hydrophobic plates

    Energy Technology Data Exchange (ETDEWEB)

    Franzese, Giancarlo [Departamento de Fisica Fundamental, Universidad de Barcelona, Diagonal 647, Barcelona 08028 (Spain); Santos, Francisco de los, E-mail: gfranzese@ub.ed, E-mail: fdlsant@ugr.e [Departamento de Electromagnetismo y Fisica de la Materia, Universidad de Granada, Fuentenueva s/n, 18071 Granada (Spain)

    2009-12-16

    We study the dynamics of water confined between hydrophobic flat surfaces at low temperature. At different pressures, we observe different behaviors that we understand in terms of the hydrogen bond dynamics. At high pressure, the formation of the open structure of the hydrogen bond network is inhibited and the surfaces can be rapidly dried (dewetted) by formation of a large cavity with decreasing temperature. At lower pressure we observe strong non-exponential behavior of the correlation function, but with no strong increase of the correlation time. This behavior can be associated, on the one hand, to the rapid ordering of the hydrogen bonds that generates heterogeneities and, on the other hand, to the lack of a single timescale as a consequence of the cooperativity in the vicinity of the liquid-liquid critical point that characterizes the phase diagram at low temperature of the water model considered here. At very low pressures, the gradual formation of the hydrogen bond network is responsible for the large increase of the correlation time and, eventually, the dynamical arrest of the system, with a strikingly different dewetting process, characterized by the formation of many small cavities.

  13. Dynamically slow processes in supercooled water confined between hydrophobic plates

    International Nuclear Information System (INIS)

    Franzese, Giancarlo; Santos, Francisco de los

    2009-01-01

    We study the dynamics of water confined between hydrophobic flat surfaces at low temperature. At different pressures, we observe different behaviors that we understand in terms of the hydrogen bond dynamics. At high pressure, the formation of the open structure of the hydrogen bond network is inhibited and the surfaces can be rapidly dried (dewetted) by formation of a large cavity with decreasing temperature. At lower pressure we observe strong non-exponential behavior of the correlation function, but with no strong increase of the correlation time. This behavior can be associated, on the one hand, to the rapid ordering of the hydrogen bonds that generates heterogeneities and, on the other hand, to the lack of a single timescale as a consequence of the cooperativity in the vicinity of the liquid-liquid critical point that characterizes the phase diagram at low temperature of the water model considered here. At very low pressures, the gradual formation of the hydrogen bond network is responsible for the large increase of the correlation time and, eventually, the dynamical arrest of the system, with a strikingly different dewetting process, characterized by the formation of many small cavities.

  14. Free energy barriers to evaporation of water in hydrophobic confinement.

    Science.gov (United States)

    Sharma, Sumit; Debenedetti, Pablo G

    2012-11-08

    We use umbrella sampling Monte Carlo and forward and reverse forward flux sampling (FFS) simulation techniques to compute the free energy barriers to evaporation of water confined between two hydrophobic surfaces separated by nanoscopic gaps, as a function of the gap width, at 1 bar and 298 K. The evaporation mechanism for small (1 × 1 nm(2)) surfaces is found to be fundamentally different from that for large (3 × 3 nm(2)) surfaces. In the latter case, the evaporation proceeds via the formation of a gap-spanning tubular cavity. The 1 × 1 nm(2) surfaces, in contrast, are too small to accommodate a stable vapor cavity. Accordingly, the associated free energy barriers correspond to the formation of a critical-sized cavity for sufficiently large confining surfaces, and to complete emptying of the gap region for small confining surfaces. The free energy barriers to evaporation were found to be of O(20kT) for 14 Å gaps, and to increase by approximately ~5kT with every 1 Å increase in the gap width. The entropy contribution to the free energy of evaporation was found to be independent of the gap width.

  15. Effects of solute--solvent attractive forces on hydrophobic correlations

    International Nuclear Information System (INIS)

    Pratt, L.R.; Chandler, D.

    1980-01-01

    A theory is presented for the effect of slowly varying attractive forces on correlations between nonpolar solutes in dilute aqueous solution. We find that hydrophobic correlations are sensitive to relatively long range slowly varying interactions. Thus, it is possible to make qualitative changes in these correlations by introducing small changes in the attractive forces. Several model calculations are presented to illustrate these facts. The contributions of the Lennard-Jones attractive forces to the computer simulation results of Pangali, Rao, and Berne are calculated. For this case it is found that the potential of mean force between spherical nonpolar solutes is hardly affected by inclusion of attractive forces. However, the osmotic second virial coefficient is dominated by the contributions of the attractive forces. For spherical solutes which provide a reasonable model for the methane molecule, inclusion of attractive forces produces a qualitative change in the methane--methane potential of mean force. The connection between these effects of slowly varying attractive forces and the enthalpic part of Ben-Naim's deltaA/sup H/I is discussed

  16. Thermally stable silica-coated hydrophobic gold nanoparticles.

    Science.gov (United States)

    Kanehara, Masayuki; Watanabe, Yuka; Teranishi, Toshiharu

    2009-01-01

    We have successfully developed a method for silica coating on hydrophobic dodecanethiol-protected Au nanoparticles with coating thickness ranging from 10 to 40 nm. The formation of silica-coated Au nanoparticles could be accomplished via the preparation of hydrophilic Au nanoparticle micelles by cationic surfactant encapsulation in aqueous phase, followed by hydrolysis of tetraethylorthosilicate on the hydrophilic surface of gold nanoparticle micelles. Silica-coated Au nanoparticles exhibited quite high thermal stability, that is, no agglomeration of the Au cores could be observed after annealing at 600 degrees C for 30 min. Silica-coated Au nanoparticles could serve as a template to derive hollow nanoparticles. An addition of NaCN solution to silica-coated Au nanoparticles led the formation of hollow silica nanoparticles, which were redispersible in deionized water. The formation of the hollow silica nanoparticles results from the mesoporous structures of the silica shell and such a mesoporous structure is applicable to both catalyst support and drug delivery.

  17. Hydrophobic pinning with copper nanowhiskers leads to bactericidal properties.

    Directory of Open Access Journals (Sweden)

    Ajay Vikram Singh

    Full Text Available The considerable morbidity associated with hospitalized patients and clinics in developed countries due to biofilm formation on biomedical implants and surgical instruments is a heavy economic burden. An alternative to chemically treated surfaces for bactericidal activity started emerging from micro/nanoscale topographical cues in the last decade. Here, we demonstrate a putative antibacterial surface using copper nanowhiskers deposited by molecular beam epitaxy. Furthermore, the control of biological response is based on hydrophobic pinning of water droplets in the Wenzel regime, causing mechanical injury and cell death. Scanning electron microscopy images revealed the details of the surface morphology and non-contact mode laser scanning of the surface revealed the microtopography-associated quantitative parameters. Introducing the bacterial culture over nanowhiskers produces mechanical injury to cells, leading to a reduction in cell density over time due to local pinning of culture medium to whisker surfaces. Extended culture to 72 hours to observe biofilm formation revealed biofilm inhibition with scattered microcolonies and significantly reduced biovolume on nanowhiskers. Therefore, surfaces patterned with copper nanowhiskers can serve as potential antibiofilm surfaces. The topography-based antibacterial surfaces introduce a novel prospect in developing mechanoresponsive nanobiomaterials to reduce the risk of medical device biofilm-associated infections, contrary to chemical leaching of copper as a traditional bactericidal agent.

  18. Effects of modified β-cyclodextrin on thermal stability and conformation of lysozyme

    International Nuclear Information System (INIS)

    Kamiyama, Tadashi; Satoh, Megumi; Tateishi, Takahiro; Nojiri, Tomoaki; Takeuchi, Daisuke; Kimura, Takayoshi

    2012-01-01

    Highlights: ► Effects of cyclodextrin on stability and conformation of lysozyme were clarified. ► The CD influences the hydrophobic interaction of lysozyme by the inclusion. ► The CD relatively destabilized the folded state by stabilizing the unfolded state. ► The destabilization depends on the concentration and the substituent of CD. ► The conformation of lysozyme was more spread at unfolded state by inclusion of CD. - Abstract: Effects of cyclic oligosaccharide cyclodextrin (CD) on stability and conformation of lysozyme were clarified thermodynamically and rheologically by DSC, viscosity, and circular dichroism measurements. The modified β-CD relatively destabilized the folded state of lysozyme by stabilizing the unfolded state due to inclusion of hydrophobic part into the hydrophobic interior of CD. The order of higher destabilization effect was acetyl-β-CD > methyl-β-CD > hydroxypropyl-β-CD. Apparent number of bound CD to unfolded state for methyl-, hydroxypropyl-, and acetyl-β-CD is 6.7 ± 0.7, 4.2 ± 1.1, and 18.6 ± 4.3 and the binding constant is 5.5 ± 0.8, 6.7 ± 2.4, and 4.4 ± 1.2 L mol −1 , respectively. The viscosity for unfolded state was increased with an increase in the each modified β-CD concentration, suggesting that the inclusion of CD on a part of hydrophobic core at unfolded state leads to break the hydrophobic core, then lysozyme would be more spread structure. The substituent of CD can accelerate instability by directly breaking hydrogen bond and/or can restrain instability by increase in hydrophobic interaction. The fact that the each modified CDs has different destabilization effect shows a possibility to control the stability of protein by the substitution of CD.

  19. Flame retardant and hydrophobic properties of novel sol-gel derived phytic acid/silica hybrid organic-inorganic coatings for silk fabric

    Science.gov (United States)

    Cheng, Xian-Wei; Liang, Cheng-Xi; Guan, Jin-Ping; Yang, Xu-Hong; Tang, Ren-Cheng

    2018-01-01

    In this work, a novel phosphorus-rich hybrid organic-inorganic silica coating for improving the flame retardancy of silk fabric was prepared using naturally occurring phytic acid as phosphorus precursor and catalyst for the hydrolysis of tetraethoxysilane. In addition, three silane coupling agents, namely 3-aminopropyldimethoxymethylsilane, 3-chloropropyltrimethoxysilane and 3-methacryloxypropyltrimethoxysilane, were added in the hybrid sol as cross-linkers with the aim of developing hydrophobic coatings and improving the washing durability of the treated silk fabric. The condensation degree of the hybrid sol was characterized by solid-state 29Si nuclear magnetic resonance spectroscopy. The flammability and thermal degradation properties of the treated silk fabrics were determined in terms of limiting oxygen index, vertical burning, pyrolysis combustion flow calorimetry and thermogravimetric analyses. The surface morphology and hydrophobicity of the treated silk fabrics were evaluated by scanning electron microscopy, atomic force microscopy and water contact angle tests. The flammability tests revealed that the silicon sol could endow silk fabric with excellent flame retardancy when doped with phytic acid, and the treated silk fabrics self-extinguished immediately when the ignition source was removed. The silk fabrics treated with the modified hybrid sols exhibited hydrophobic surface and also better durability to washing.

  20. Effects of content and surface hydrophobic modification of BaTiO3 on the cooling properties of ASA (acrylonitrile-styrene-acrylate copolymer)

    Science.gov (United States)

    Xiang, Bo; Zhang, Jun

    2018-01-01

    For the field of cool material, barium titanate (BaTiO3, BT) is still a new member that needs to be further studied. Herein, the effects of both content and surface hydrophobic modification of BT on the cooling properties of acrylonitrile-styrene-acrylate copolymer (ASA) were detailedly investigated, aiming to fabricate composited cool material. Butyl acrylate (BA) was employed to convert the surface of BT from hydrophilic to hydrophobic. The addition of unmodified BT could significantly improve the solar reflectance of ASA, especially when the addition amount is 3 vol%, the near infrared (NIR) reflectance increased from 22.02 to 72.60%. However, serious agglomeration occurred when the addition amount increased to 5 vol% and therefore led to a relatively smaller increase in solar reflectance and an obvious decline in impact strength. After surface hydrophobic modification, the modified BT (M-BT) presented better dispersibility in ASA matrix, which contributed to the improvement of both solar reflectance and impact strength. In addition, the temperature test provided a more sufficient and intuitive way to evaluate the cooling effect of the composited cool materials, and a significant decrease (over 10 °C) could be achieved in the temperature test when M-BT particles were introduced.

  1. Hydrophobic surface modification of TiO2 nanoparticles for production of acrylonitrile-styrene-acrylate terpolymer/TiO2 composited cool materials

    Science.gov (United States)

    Qi, Yanli; Xiang, Bo; Tan, Wubin; Zhang, Jun

    2017-10-01

    Hydrophobic surface modification of TiO2 was conducted for production of acrylonitrile-styrene-acrylate (ASA) terpolymer/titanium dioxide (TiO2) composited cool materials. Different amount of 3-methacryloxypropyl-trimethoxysilane (MPS) was employed to change hydrophilic surface of TiO2 into hydrophobic surface. The hydrophobic organosilane chains were successfully grafted onto TiO2 through Sisbnd Osbnd Ti bonds, which were verified by Fourier transformed infrared spectra and X-ray photoelectron spectroscopy. The water contact angle of the sample added with TiO2 modified by 5 wt% MPS increased from 86° to 113°. Besides, all the ASA/TiO2 composites showed significant improvement in both solar reflectance and cooling property. The reflectance of the composites throughout the near infrared (NIR) region and the whole solar wavelength is increased by 113.92% and 43.35% compared with pristine ASA resin. Simultaneously, significant drop in temperature demonstrates excellent cooling property. A maximum decrease approach to 27 °C was observed in indoor temperature test, while a decrease around 9 °C tested outdoors is achieved.

  2. Super-hydrophobic surfaces of SiO₂-coated SiC nanowires: fabrication, mechanism and ultraviolet-durable super-hydrophobicity.

    Science.gov (United States)

    Zhao, Jian; Li, Zhenjiang; Zhang, Meng; Meng, Alan

    2015-04-15

    The interest in highly water-repellent surfaces of SiO2-coated SiC nanowires has grown in recent years due to the desire for self-cleaning and anticorrosive surfaces. It is imperative that a simple chemical treatment with fluoroalkylsilane (FAS, CF3(CF2)7CH2CH2Si(OC2H5)3) in ethanol solution at room temperature resulted in super-hydrophobic surfaces of SiO2-coated SiC nanowires. The static water contact angle of SiO2-coated SiC nanowires surfaces was changed from 0° to 153° and the morphology, microstructure and crystal phase of the products were almost no transformation before and after super-hydrophobic treatment. Moreover, a mechanism was expounded reasonably, which could elucidate the reasons for their super-hydrophobic behavior. It is important that the super-hydrophobic surfaces of SiO2-coated SiC nanowires possessed ultraviolet-durable (UV-durable) super-hydrophobicity. Copyright © 2014 Elsevier Inc. All rights reserved.

  3. Temperature dependence of the evaporation lengthscale for water confined between two hydrophobic plates.

    Science.gov (United States)

    Djikaev, Yuri S; Ruckenstein, Eli

    2015-07-01

    Liquid water in a hydrophobic confinement is the object of high interest in physicochemical sciences. Confined between two macroscopic hydrophobic surfaces, liquid water transforms into vapor if the distance between surfaces is smaller than a critical separation, referred to as the evaporation lengthscale. To investigate the temperature dependence of the evaporation lengthscale of water confined between two hydrophobic parallel plates, we use the combination of the density functional theory (DFT) with the probabilistic hydrogen bond (PHB) model for water-water hydrogen bonding. The PHB model provides an analytic expression for the average number of hydrogen bonds per water molecule as a function of its distance to a hydrophobic surface and its curvature. Knowing this expression, one can implement the effect of hydrogen bonding between water molecules on their interaction with the hydrophobe into DFT, which is then employed to determine the distribution of water molecules between two macroscopic hydrophobic plates at various interplate distances and various temperatures. For water confined between hydrophobic plates, our results suggest the evaporation lengthscale to be of the order of several nanometers and a linearly increasing function of temperature from T=293 K to T=333 K, qualitatively consistent with previous results. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Soft matter interactions at the molecular scale: interaction forces and energies between single hydrophobic model peptides.

    Science.gov (United States)

    Stock, Philipp; Utzig, Thomas; Valtiner, Markus

    2017-02-08

    In all realms of soft matter research a fundamental understanding of the structure/property relationships based on molecular interactions is crucial for developing a framework for the targeted design of soft materials. However, a molecular picture is often difficult to ascertain and yet essential for understanding the many different competing interactions at play, including entropies and cooperativities, hydration effects, and the enormous design space of soft matter. Here, we characterized for the first time the interaction between single hydrophobic molecules quantitatively using atomic force microscopy, and demonstrated that single molecular hydrophobic interaction free energies are dominated by the area of the smallest interacting hydrophobe. The interaction free energy amounts to 3-4 kT per hydrophobic unit. Also, we find that the transition state of the hydrophobic interactions is located at 3 Å with respect to the ground state, based on Bell-Evans theory. Our results provide a new path for understanding the nature of hydrophobic interactions at the single molecular scale. Our approach enables us to systematically vary hydrophobic and any other interaction type by utilizing peptide chemistry providing a strategic advancement to unravel molecular surface and soft matter interactions at the single molecular scale.

  5. Continuous droplet removal upon dropwise condensation of humid air on a hydrophobic micropatterned surface.

    Science.gov (United States)

    Zamuruyev, Konstantin O; Bardaweel, Hamzeh K; Carron, Christopher J; Kenyon, Nicholas J; Brand, Oliver; Delplanque, Jean-Pierre; Davis, Cristina E

    2014-08-26

    Combination of two physical phenomena, capillary pressure gradient and wettability gradient, allows a simple two-step fabrication process that yields a reliable hydrophobic self-cleaning condenser surface. The surface is fabricated with specific microscopic topography and further treatment with a chemically inert low-surface-energy material. This process does not require growth of nanofeatures (nanotubes) or hydrophilic-hydrophobic patterning of the surface. Trapezoidal geometry of the microfeatures facilitates droplet transfer from the Wenzel to the Cassie state and reduces droplet critical diameter. The geometry of the micropatterns enhances local coalescence and directional movement for droplets with diameter much smaller than the radial length of the micropatterns. The hydrophobic self-cleaning micropatterned condenser surface prevents liquid film formation and promotes continuous dropwise condensation cycle. Upon dropwise condensation, droplets follow a designed wettability gradient created with micropatterns from the most hydrophobic to the least hydrophobic end of the surface. The surface has higher condensation efficiency, due to its directional self-cleaning property, than a plain hydrophobic surface. We explain the self-actuated droplet collection mechanism on the condenser surface and demonstrate experimentally the creation of an effective wettability gradient over a 6 mm radial distance. In spite of its fabrication simplicity, the fabricated surface demonstrates self-cleaning property, enhanced condensation performance, and reliability over time. Our work enables creation of a hydrophobic condenser surface with the directional self-cleaning property that can be used for collection of biological (chemical, environmental) aerosol samples or for condensation enhancement.

  6. Detection of secondary structure elements in proteins by hydrophobic cluster analysis.

    Science.gov (United States)

    Woodcock, S; Mornon, J P; Henrissat, B

    1992-10-01

    Hydrophobic cluster analysis (HCA) is a protein sequence comparison method based on alpha-helical representations of the sequences where the size, shape and orientation of the clusters of hydrophobic residues are primarily compared. The effectiveness of HCA has been suggested to originate from its potential ability to focus on the residues forming the hydrophobic core of globular proteins. We have addressed the robustness of the bidimensional representation used for HCA in its ability to detect the regular secondary structure elements of proteins. Various parameters have been studied such as those governing cluster size and limits, the hydrophobic residues constituting the clusters as well as the potential shift of the cluster positions with respect to the position of the regular secondary structure elements. The following results have been found to support the alpha-helical bidimensional representation used in HCA: (i) there is a positive correlation (clearly above background noise) between the hydrophobic clusters and the regular secondary structure elements in proteins; (ii) the hydrophobic clusters are centred on the regular secondary structure elements; (iii) the pitch of the helical representation which gives the best correspondence is that of an alpha-helix. The correspondence between hydrophobic clusters and regular secondary structure elements suggests a way to implement variable gap penalties during the automatic alignment of protein sequences.

  7. Engineering Extreme Hydrophobic and Super Slippery Water Shedding Surfaces

    Science.gov (United States)

    McHale, Glen

    2017-04-01

    The intrinsic water repellency of a material is fundamentally determined by its surface chemistry, but alone this does not determine the ability of a surface to shed water. Physical factors such as the surface texture/topography, rigidity/flexibility, granularity/porosity combined with the intrinsic wetting properties of the liquid with the surface and whether it is infused by a lubricating liquid are equally important. In this talk I will outline fundamental, but simple, ideas on the topographic enhancement of surface chemistry to create superhydrophobicity, the adhesion of particles to liquid-air interfaces to create liquid marbles, elastocapillarity to create droplet wrapping, and lubricant impregnated surfaces to create completely mobile droplets [1-3]. I will discuss how these ideas have their origins in natural systems and surfaces, such as Lotus leaves, galling aphids and the Nepenthes pitcher plant. I will show how we have applied these concepts to study the wetting of granular systems, such as sand, to understand extreme soil water repellency. I will argue that relaxing the assumption that a solid substrate is fixed in shape and arrangement, can lead to the formation of liquid marbles, whereby a droplet self-coats in a hydrophobic powder/grains. I will show that the concepts of wetting and porosity blur as liquids penetrate into a porous or granular substrate. I will also discuss how lubricant impregnated super slippery surfaces can be used to study a pure constant contact angle mode of droplet evaporation [4]. Finally, I will show dewetting of a surface is not simply a video reversal of wetting [5], and I will give an example of the use of perfect hydrophobicity using the Leidenfrost effect to create a new type of low friction mechanical and hear engine [6]. References: [1] Shirtcliffe, N. J., et al., An introduction to superhydrophobicity. Advances in Colloid and Interface Science, vol. 161, pp.124-138 (2010). [2] McHale, G. & Newton, M. I. Liquid

  8. Function of C-terminal hydrophobic region in fructose dehydrogenase

    International Nuclear Information System (INIS)

    Sugimoto, Yu; Kawai, Shota; Kitazumi, Yuki; Shirai, Osamu; Kano, Kenji

    2015-01-01

    Fructose dehydrogenase (FDH) catalyzes oxidation of D-fructose into 2-keto-D-fructose and is one of the enzymes allowing a direct electron transfer (DET)-type bioelectrocatalysis. FDH is a heterotrimeric membrane-bound enzyme (subunit I, II, and III) and subunit II has a C terminal hydrophobic region (CHR), which was expected to play a role in anchoring to membranes from the amino acid sequence. We have constructed a mutated FDH lacking of CHR (ΔchrFDH). Contrary to the expected function of CHR, ΔchrFDH is expressed in the membrane fraction, and subunit I/III subcomplex (ΔcFDH) is also expressed in a similar activity level but in the soluble fraction. In addition, the enzyme activity of the purified ΔchrFDH is about one twentieth of the native FDH. These results indicate that CHR is concerned with the binding between subunit I(/III) and subunit II and then with the enzyme activity. ΔchrFDH has clear DET activity that is larger than that expected from the solution activity, and the characteristics of the catalytic wave of ΔchrFDH are very similar to those of FDH. The deletion of CHR seems to increase the amounts of the enzyme with the proper orientation for the DET reaction at electrode surfaces. Gel filtration chromatography coupled with urea treatment shows that the binding in ΔchrFDH is stronger than that in FDH. It can be considered that the rigid binding between subunit I(/III) and II without CHR results in a conformation different from the native one, which leads to the decrease in the enzyme activity in solution

  9. Impact of Dendrimers on Solubility of Hydrophobic Drug Molecules

    Directory of Open Access Journals (Sweden)

    Sonam Choudhary

    2017-05-01

    Full Text Available Adequate aqueous solubility has been one of the desired properties while selecting drug molecules and other bio-actives for product development. Often solubility of a drug determines its pharmaceutical and therapeutic performance. Majority of newly synthesized drug molecules fail or are rejected during the early phases of drug discovery and development due to their limited solubility. Sufficient permeability, aqueous solubility and physicochemical stability of the drug are important for achieving adequate bioavailability and therapeutic outcome. A number of different approaches including co-solvency, micellar solubilization, micronization, pH adjustment, chemical modification, and solid dispersion have been explored toward improving the solubility of various poorly aqueous-soluble drugs. Dendrimers, a new class of polymers, possess great potential for drug solubility improvement, by virtue of their unique properties. These hyper-branched, mono-dispersed molecules have the distinct ability to bind the drug molecules on periphery as well as to encapsulate these molecules within the dendritic structure. There are numerous reported studies which have successfully used dendrimers to enhance the solubilization of poorly soluble drugs. These promising outcomes have encouraged the researchers to design, synthesize, and evaluate various dendritic polymers for their use in drug delivery and product development. This review will discuss the aspects and role of dendrimers in the solubility enhancement of poorly soluble drugs. The review will also highlight the important and relevant properties of dendrimers which contribute toward drug solubilization. Finally, hydrophobic drugs which have been explored for dendrimer assisted solubilization, and the current marketing status of dendrimers will be discussed.

  10. Thermal destruction of organic waste hydrophobicity for agricultural soils application.

    Science.gov (United States)

    Comino, Francisco; Aranda, Víctor; Domínguez-Vidal, Ana; Ayora-Cañada, María José

    2017-11-01

    Use of organic amendments is a good strategy for combating the growing problem of soil degradation due to deterioration of organic matter content, particularly severe in semi-arid European Mediterranean regions, while at the same time providing an opportunity for recycling organic wastes. Olive mill pomace (OMP), the main by-product of the olive oil industry, is being used increasingly in olive grove soils for this purpose. Although the positive effects of OMP amendments have been widely studied, they also have some negative effects on soil. One of the most critical is that they increase water repellency (WR) due to the presence of poorly evolved, strongly aliphatic compounds. This detrimental effect has received very little attention, although it may impair plant water availability and infiltration rates, increase erosion and lower long-term soil quality. This study proposed, for the first time, thermal treatment as an effective way of reducing WR in organic amendments (i.e. mixtures of OMP, olive tree pruning, chicken manure and spent coffee grounds) prior to their application to soil. Thermal treatment at 275 °C proved effective in removing WR, while lower temperatures (175 or 225 °C) can even increase it. Changes by thermal treatment in the characteristics of the organic amendments studied with FTIR and UV-Vis spectroscopy and thermogravimetric analysis showed that it strongly reduced the aliphatic compounds mainly responsible for their hydrophobicity, concentrated aromatic compounds and increased thermostability. Heating also reduced phytotoxicity, making all of the organic amendments usable in the field (germination index over 100%). Therefore, heating at 275 °C could be an acceptable option for removing WR from organic amendments, enhancing their quality with more stable evolved characteristics. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Changes in antibiotic sensitivity and cell surface hydrophobicity in Escherichia coli injured by heating, freezing, drying or gamma radiation

    International Nuclear Information System (INIS)

    Mackey, B.M.

    1983-01-01

    Escherichia coli cells exposed to mild heating, freezing and thawing, drying or γ-radiation were sensitised to hydrophobic antibiotics and sodium deoxycholate but not to small hydrophilic antibiotics. These stress treatments also caused increases in cell surface hydrophobicity broadly reflecting the degree of sensitivity to hydrophobic antibiotics. (Auth.)

  12. Environmentally responsive surface-modified silica nanoparticles for enhanced oil recovery

    International Nuclear Information System (INIS)

    Behzadi, Abed; Mohammadi, Aliasghar

    2016-01-01

    Environmentally responsive surface-modified nanoparticles are colloidal nanoparticles coated with, at least, two physicochemically distinct surface groups. Recent advances in the synthesis and production of nanoparticles have enabled the production of environmentally responsive surface-modified nanoparticles with both hydrophilic and hydrophobic surface groups. These nanoparticles act like colloidal surfactants. In this paper, environmentally responsive surface-modified silica nanoparticles are synthesized and used for enhancement of oil recovery. For this purpose, silica nanoparticles are coated with polyethylene glycol chains as hydrophilic agent and propyl chains as hydrophobic agent at various quantities, and their ability to modulate oil–water interface properties and oil recovery is examined. Oil–water interfacial tension and water surface tension are decreased by 50 % in the presence of silica nanoparticles coated with both agents. Measuring oil-drop contact angle on oil-wetted glass slides and carbonate rock sections, after aging in various surface-modified silica nanofluids, indicates that the wettability of various oil-wetted surfaces is modified from strongly oil-wet to water-wet. Flooding nanofluids to glass micro-models and pore-level investigations demonstrate that surface modification of silica nanoparticles, specially, with both hydrophilic and hydrophobic agents improves considerably their performance in increasing oil recovery and wettability alteration.

  13. Environmentally responsive surface-modified silica nanoparticles for enhanced oil recovery

    Energy Technology Data Exchange (ETDEWEB)

    Behzadi, Abed; Mohammadi, Aliasghar, E-mail: amohammadi@sharif.edu [Sharif University of Technology, Department of Chemical and Petroleum Engineering (Iran, Islamic Republic of)

    2016-09-15

    Environmentally responsive surface-modified nanoparticles are colloidal nanoparticles coated with, at least, two physicochemically distinct surface groups. Recent advances in the synthesis and production of nanoparticles have enabled the production of environmentally responsive surface-modified nanoparticles with both hydrophilic and hydrophobic surface groups. These nanoparticles act like colloidal surfactants. In this paper, environmentally responsive surface-modified silica nanoparticles are synthesized and used for enhancement of oil recovery. For this purpose, silica nanoparticles are coated with polyethylene glycol chains as hydrophilic agent and propyl chains as hydrophobic agent at various quantities, and their ability to modulate oil–water interface properties and oil recovery is examined. Oil–water interfacial tension and water surface tension are decreased by 50 % in the presence of silica nanoparticles coated with both agents. Measuring oil-drop contact angle on oil-wetted glass slides and carbonate rock sections, after aging in various surface-modified silica nanofluids, indicates that the wettability of various oil-wetted surfaces is modified from strongly oil-wet to water-wet. Flooding nanofluids to glass micro-models and pore-level investigations demonstrate that surface modification of silica nanoparticles, specially, with both hydrophilic and hydrophobic agents improves considerably their performance in increasing oil recovery and wettability alteration.

  14. Hydrophobic Coatings by Thiol-Ene Click Functionalization of Silsesquioxanes with Tunable Architecture.

    Science.gov (United States)

    Dirè, Sandra; Bottone, Davide; Callone, Emanuela; Maniglio, Devid; Génois, Isabelle; Ribot, François

    2017-08-08

    The hydrolysis-condensation of trialkoxysilanes under strictly controlled conditions allows the production of silsesquioxanes (SSQs) with tunable size and architecture ranging from ladder to cage-like structures. These nano-objects can serve as building blocks for the preparation of hybrid organic/inorganic materials with selected properties. The SSQs growth can be tuned by simply controlling the reaction duration in the in situ water production route (ISWP), where the kinetics of the esterification reaction between carboxylic acids and alcohols rules out the extent of organosilane hydrolysis-condensation. Tunable SSQs with thiol functionalities (SH-NBBs) are suitable for further modification by exploiting the simple thiol-ene click reaction, thus allowing for modifying the wettability properties of derived coatings. In this paper, coatings were prepared from SH-NBBs with different architecture onto cotton fabrics and paper, and further functionalized with long alkyl chains by means of initiator-free UV-induced thiol-ene coupling with 1-decene (C10) and 1-tetradecene (C14). The coatings appeared to homogeneously cover the natural fibers and imparted a multi-scale roughness that was not affected by the click functionalization step. The two-step functionalization of cotton and paper warrants a stable highly hydrophobic character to the surface of natural materials that, in perspective, suggests a possible application in filtration devices for oil-water separation. Furthermore, the purification of SH-NBBs from ISWP by-products was possible during the coating process, and this step allowed for the fast, initiator-free, click-coupling of purified NBBs with C10 and C14 in solution with a nearly quantitative yield. Therefore, this approach is an alternative route to get sol-gel-derived, ladder-like, and cage-like SSQs functionalized with long alkyl chains.

  15. N,O6-partially acetylated chitosan nanoparticles hydrophobically-modified for controlled release of steroids and vitamin E

    DEFF Research Database (Denmark)

    Quinones, Javier Perez; Gothelf, Kurt Vesterager; Kjems, Jørgen

    2013-01-01

    Diosgenin, two synthetic analogs of brassinosteroids, testosterone and dl-α-tocopherol were covalently linked to synthetic water-soluble N,O6-partially acetylated chitosan, for their controlled release. Drug linking was confirmed by FTIR spectroscopy and proton NMR. Conjugates were also character......Diosgenin, two synthetic analogs of brassinosteroids, testosterone and dl-α-tocopherol were covalently linked to synthetic water-soluble N,O6-partially acetylated chitosan, for their controlled release. Drug linking was confirmed by FTIR spectroscopy and proton NMR. Conjugates were also...

  16. Characterization of modified clinoptilolite

    International Nuclear Information System (INIS)

    Novosad, J.; Jandl, J.; Woollins, J.D.

    1992-01-01

    Samples of clinoptilolite were modified using insoluble hexacyanoferrate from aqueous solution. The modified samples were characterized by elemental analysis, powder X-ray diffraction, solid state NMR and vibrational spectroscopy. The sorption properties of modified clinoptilolite were studied, too. Higher affinity for 137 Cs sorption in comparison with the natural clinoptilolite has been proved. (author) 5 refs.; 3 figs.; 2 tabs

  17. Pool boiling of nanoparticle-modified surface with interlaced wettability

    KAUST Repository

    Hsu, Chin-Chi; Su, Tsung-Wen; Chen, Ping-Hei

    2012-01-01

    This study investigated the pool boiling heat transfer under heating surfaces with various interlaced wettability. Nano-silica particles were used as the coating element to vary the interlaced wettability of the surface. The experimental results revealed that when the wettability of a surface is uniform, the critical heat flux increases with the more wettable surface; however, when the wettability of a surface is modified interlacedly, regardless of whether the modified region becomes more hydrophilic or hydrophobic, the critical heat flux is consistently higher than that of the isotropic surface. In addition, this study observed that critical heat flux was higher when the contact angle difference between the plain surface and the modified region was smaller. © 2012 Hsu et al.

  18. Development of road soil cement compositions modified with complex additive based on polycarboxylic ether

    Science.gov (United States)

    Bulanov, P. E.; Vdovin, E. A.; Mavliev, L. F.; Kuznetsov, D. A.

    2018-03-01

    The paper is focused on the research results of the main physical and technical properties of the cement-stabilized polymineral clay modified with a complex hydrophobic plasticizer based on polycarboxylate and octyltriethoxysilane ethers. A graphical result interpretation of the mathematic model which shows the influence of the complex hydrophobic plasticizer components on the cement-stabilized polymineral clay, containing more than 85% of relict minerals, has been designed. The research significance for the building sector lies in the fact that applying a complex hydrophobic plasticizer provides increasing the compressive strength of the cement-stabilized polymineral clay up to 102%, the tensile bending strength – up to 88%, the freeze-thaw resistance – up to 114%.

  19. Molecular origin of urea driven hydrophobic polymer collapse and unfolding depending on side chain chemistry.

    Science.gov (United States)

    Nayar, Divya; Folberth, Angelina; van der Vegt, Nico F A

    2017-07-19

    Osmolytes affect hydrophobic collapse and protein folding equilibria. The underlying mechanisms are, however, not well understood. We report large-scale conformational sampling of two hydrophobic polymers with secondary and tertiary amide side chains using extensive molecular dynamics simulations. The calculated free energy of unfolding increases with urea for the secondary amide, yet decreases for the tertiary amide, in agreement with experiment. The underlying mechanism is rooted in opposing entropic driving forces: while urea screens the hydrophobic macromolecular interface and drives unfolding of the tertiary amide, urea's concomitant loss in configurational entropy drives collapse of the secondary amide. Only at sufficiently high urea concentrations bivalent urea hydrogen bonding interactions with the secondary amide lead to further stabilisation of its collapsed state. The observations provide a new angle on the interplay between side chain chemistry, urea hydrogen bonding, and the role of urea in attenuating or strengthening the hydrophobic effect.

  20. Enhancement of Water Evaporation on Solid Surfaces with Nanoscale Hydrophobic-Hydrophilic Patterns.

    Science.gov (United States)

    Wan, Rongzheng; Wang, Chunlei; Lei, Xiaoling; Zhou, Guoquan; Fang, Haiping

    2015-11-06

    Using molecular dynamics simulations, we show that the evaporation of nanoscale water on hydrophobic-hydrophilic patterned surfaces is unexpectedly faster than that on any surfaces with uniform wettability. The key to this phenomenon is that, on the patterned surface, the evaporation rate from the hydrophilic region only slightly decreases due to the correspondingly increased water thickness; meanwhile, a considerable number of water molecules evaporate from the hydrophobic region despite the lack of water film. Most of the evaporated water from the hydrophobic region originates from the hydrophilic region by diffusing across the contact lines. Further analysis shows that the evaporation rate from the hydrophobic region is approximately proportional to the total length of the contact lines.

  1. An experimental investigation of evaporating sessile droplet on super-hydrophobic surface

    International Nuclear Information System (INIS)

    Shin, Dong Hwan; Lee, Seong Hyuk; Yoo, Jung Yul

    2008-01-01

    The objective of this study is to investigate the evaporation process of a water droplet on hydrophobic and hydrophilic surfaces. Time-dependent contact angle, height, radius, surface area, and volume were measured for three different surfaces, such as glass, OctadecylTrichloroSilane(OTS), and AlkylKetene Dimmer(AKD) using a digital image analysis technique. For hydrophilic surfaces, the measured contact angle, liquid volume, and height are also compared with numerical estimation. It is found that for super-hydrophobic surfaces, the contact line becomes no longer pinned during evaporation, and three distinct stages for hydrophobic surface cannot be found. For the super-hydrophobic surface, it takes the longest time for evaporation because the droplet maintains spherical shape even near the end of evaporation process

  2. Evaluation of Relative Yeast Cell Surface Hydrophobicity Measured by Flow Cytometry

    Directory of Open Access Journals (Sweden)

    Lisa Colling

    2005-01-01

    Full Text Available Objective: To develop an efficient method for evaluating cell surface hydrophobicity and to apply the method to demonstrate the effects of fungal growth conditions on cell surface properties.

  3. Production and characterization of hydrophobic zinc borate by using palm oil

    Institute of Scientific and Technical Information of China (English)

    Nil Baran Acarali; Nurcan Tugrul; Emek Moroydor Derun; Sabriye Piskin

    2013-01-01

    Zinc borate (ZB) was synthesized using zinc oxide, boric acid synthesized from colemanite, and reference ZB as seed. The eff ects of reaction parameters such as reaction time, reactant ratio, and seed ratio on its yield were examined. Then, the eff ects of palm oil with solvents (isopropyl alcohol (IPA), ethanol, and methanol) added to the reaction on its hydrophobicity were explored. Reactions were carried out under determined reaction conditions with magnetically and mechanically stirred systems. The produced ZB was characterized by X-ray diff raction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and measurements of contact angle identified hydrophobicity. The results showed that hydrophobic ZB was successfully produced under determined reaction conditions. The change of process parameters influenced its yield and the usage of palm oil provided hydrophobicity.

  4. Super-hydrophobic nickel films with micro-nano hierarchical structure prepared by electrodeposition

    International Nuclear Information System (INIS)

    Hang Tao; Hu Anmin; Ling Huiqin; Li Ming; Mao Dali

    2010-01-01

    Super-hydrophobic nickel films were prepared by a simple and low cost electrodepositing method. The surface morphologies of the films characterized by scanning electronic microscope exhibit hierarchical structure with micro-nanocones array, which can be responsible for their super-hydrophobic characteristic (water contact angle over 150 o ) without chemical modification. The wettability of the film can be varied from super-hydrophobic (water contact angle 154 o ) to relatively hydrophilic (water contact angle 87 o ) by controlling the size of the micro-nanocones. The mechanism of the hydrophobic characteristic of nickel films with this unique structure was illustrated by several models. Such micro-nanostructure and its special wettability are expected to be applied in the practical industry.

  5. Relation between the characteristic molecular volume and hydrophobicity of nonpolar molecules

    Energy Technology Data Exchange (ETDEWEB)

    Sedov, Igor A., E-mail: igor_sedov@inbox.ru; Solomonov, Boris N., E-mail: boris.solomonov@ksu.r

    2010-09-15

    Experimental values of the Gibbs free energies of hydration for a set of nonpolar or very slightly polar compounds are analyzed in order to investigate how does the hydrophobic effect depend on molecular structure and shape. The contribution due to the hydrophobic effect is evaluated using a method we suggested previously. A number of values of the Gibbs free energies of solvation in dimethyl sulfoxide and in hexadecane, which are required for calculation, were determined by gas chromatographic headspace analysis. It is found that the Gibbs hydrophobic effect energy is linearly dependent on characteristic molecular volume for a large variety of solutes with branched and unbranched carbon chains, different functional groups and atomic composition. Molecular structure and shape do not significantly affect the hydrophobicity of chemical species, and molecular volume is a main factor determining it.

  6. Effects of nanometric hydrophobic layer on performances of solar photovoltaic collectors

    Directory of Open Access Journals (Sweden)

    Andrei BUTUZA

    2014-11-01

    Full Text Available The study refers to the experimental investigation of solar photovoltaic collectors' behaviour when the glazed surface is treated with a nanometric layer of hydrophobic solution. The experiment was carried out on two photovoltaic collectors, of which one was considered as reference and the other one was coated with a commercial hydrophobic solution. It was studied the evolution of the following electrical parameters: current, voltage, power, efficiency and daily energy production. The voltage was almost unaffected, but for all the others parameters, important drop were recorded. The preliminary conclusion of the study is that the use of hydrophobic solutions, for the treatment of glazed surfaces of solar collectors is not recommended. This hypothesis needs supplementary investigations and measurements in the context of reduced available information concerning the optical properties of hydrophobic solutions.

  7. The performance analysis of direct methanol fuel cells with different hydrophobic anode channels

    Science.gov (United States)

    Yeh, Hung-Chun; Yang, Ruey-Jen; Luo, Win-Jet; Jiang, Jia-You; Kuan, Yean-Der; Lin, Xin-Quan

    In order to enhance the performance of the direct methanol fuel cell (DMFC), the product of CO 2 bubble has to be efficiently removed from the anode channel during the electrochemical reaction. In this study, the materials of Polymethyl Methacrylate (PMMA) with hydrophilic property and polydimethylsiloxane (PDMS) with hydrophobic property are used to form the anode cannel. The channel is fabricated through a microelectromechanical system (MEMS) manufacture process of the DMFCs. In addition, some particles with high hydrophobic properties are added into the PDMS materials in order to further reduce the hydro-resistance in the anode channel. The performance of the DMFCs is investigated under the influence of operation conditions, including operation temperature, flow rate, and methanol concentration. It is found that the performance of the DMFC, which is made of PDMS with high hydrophobic particles, can be greatly enhanced and the hydrophobic property of the particles can be unaffected by different operation conditions.

  8. Fabricated super-hydrophobic film with potentiostatic electrolysis method on copper for corrosion protection

    International Nuclear Information System (INIS)

    Wang Peng; Qiu Ri; Zhang Dun; Lin Zhifeng; Hou Baorong

    2010-01-01

    A novel one-step potentiostatic electrolysis method was proposed to fabricate super-hydrophobic film on copper surface. The resulted film was characterized by contact angle tests, Fourier transform infrared spectra (FT-IR), X-ray photoelectron spectroscopy (XPS), Field emission scanning electron microscopy (FE-SEM) and electrochemical measurements. It could be inferred that the super-hydrophobic property resulted from the flower-like structure of copper tetradecanoate film. In the presence of super-hydrophobic film, the anodic and cathodic polarization current densities are reduced for more than five and four orders of magnitude, respectively. The air trapped in the film is the essential contributor of the anticorrosion property of film for its insulation, the copper tetradecanoate film itself acts as a 'frame' to trap air as well as a coating with inhibition effect. The super-hydrophobic film presents excellent inhibition effect to the copper corrosion and stability in water containing Cl - .

  9. Silica-bound copper(II)triazacyclononane as a phosphate esterase: effect of linker length and surface hydrophobicity.

    Science.gov (United States)

    Bodsgard, Brett R; Clark, Robert W; Ehrbar, Anthony W; Burstyn, Judith N

    2009-04-07

    A series of silica-bound Cu(ii) triazacyclononane materials was prepared to study the effect of linker length and surface hydrophobicity on the hydrolysis of phosphate esters. The general synthetic approach for these heterogeneous reagents was rhodium-catalyzed hydrosilation between an alkenyl-modified triazacyclononane and hydride-modified silica followed by metallation with a Cu(ii) salt. Elemental analysis confirmed that organic functionalization of the silica gel was successful and provided an estimate of the surface concentration of triazacyclononane. EPR spectra were consistent with square pyramidal Cu(ii), indicating that Cu(ii) ions were bound to the immobilized macrocycles. The hydrolytic efficacies of these heterogeneous reagents were tested with bis(p-nitrophenyl)phosphate (BNPP) and diethyl 4-nitrophenyl phosphate (paraoxon). The agent that performed best was an octyl-linked, propanol-blocked material. This material had the most hydrophilic surface and the most accessible active site, achieving a rate maximum on par with the other materials, but in fewer cycles and without an induction period.

  10. Mapping Hydrophobicity on the Protein Molecular Surface at Atom-Level Resolution

    Science.gov (United States)

    Nicolau Jr., Dan V.; Paszek, Ewa; Fulga, Florin; Nicolau, Dan V.

    2014-01-01

    A precise representation of the spatial distribution of hydrophobicity, hydrophilicity and charges on the molecular surface of proteins is critical for the understanding of the interaction with small molecules and larger systems. The representation of hydrophobicity is rarely done at atom-level, as this property is generally assigned to residues. A new methodology for the derivation of atomic hydrophobicity from any amino acid-based hydrophobicity scale was used to derive 8 sets of atomic hydrophobicities, one of which was used to generate the molecular surfaces for 35 proteins with convex structures, 5 of which, i.e., lysozyme, ribonuclease, hemoglobin, albumin and IgG, have been analyzed in more detail. Sets of the molecular surfaces of the model proteins have been constructed using spherical probes with increasingly large radii, from 1.4 to 20 Å, followed by the quantification of (i) the surface hydrophobicity; (ii) their respective molecular surface areas, i.e., total, hydrophilic and hydrophobic area; and (iii) their relative densities, i.e., divided by the total molecular area; or specific densities, i.e., divided by property-specific area. Compared with the amino acid-based formalism, the atom-level description reveals molecular surfaces which (i) present an approximately two times more hydrophilic areas; with (ii) less extended, but between 2 to 5 times more intense hydrophilic patches; and (iii) 3 to 20 times more extended hydrophobic areas. The hydrophobic areas are also approximately 2 times more hydrophobicity-intense. This, more pronounced “leopard skin”-like, design of the protein molecular surface has been confirmed by comparing the results for a restricted set of homologous proteins, i.e., hemoglobins diverging by only one residue (Trp37). These results suggest that the representation of hydrophobicity on the protein molecular surfaces at atom-level resolution, coupled with the probing of the molecular surface at different geometric resolutions

  11. Control and characterization of textured, hydrophobic ionomer surfaces

    Science.gov (United States)

    Wang, Xueyuan

    Polymer thin films are of increasing interest in many industrial and technological applications. Superhydrophobic, self-cleaning surfaces have attracted a lot of attention for their application in self-cleaning, anti-sticking coatings, stain resistance, or anti-contamination surfaces in diverse technologies, including medical, transportation, textiles, electronics and paints. This thesis focuses on the preparation of nanometer to micrometer-size particle textured surfaces which are desirable for super water repellency. Textured surfaces consisting of nanometer to micrometer-sized lightly sulfonated polystyrene ionomer (SPS) particles were prepared by rapid evaporation of the solvent from a dilute polymer solution cast onto silica. The effect of the solvent used to spin coat the film, the molecular weight of the ionomer, and the rate of solvent evaporation were investigated. The nano-particle or micron-particle textured ionomer surfaces were prepared by either spin coating or solution casting ionomer solutions at controlled evaporation rates. The surface morphologies were consistent with a spinodal decomposition mechanism where the surface first existed as a percolated-like structure and then ripened into droplets if molecular mobility was retained for sufficient time. The SPS particles or particle aggregates were robust and resisted deformation even after annealing at 120°C for one week. The water contact angles on as-prepared surfaces were relatively low, ~ 90° since the polar groups in ionomer reduce the surface hydrophobicity. After chemical vapor deposition of 1H,1H,2H,2H-perfluorooctyltrichlorosilane, the surface contact angles increased to ~ 109° on smooth surfaces and ~140° on the textured surfaces. Water droplets stuck to these surfaces even when tilted 90 degrees. Superhydrophobic surfaces were prepared by spraying coating ionomer solutions and Chemical Vapor Deposition (CVD) of 1H,1H,2H,2H-perfluorooctyltrichlorosilane onto textured surfaces. The

  12. Water in contact with extended hydrophobic surfaces: Direct evidence of weak dewetting

    International Nuclear Information System (INIS)

    Jensen, Torben R.; Kjaer, Kristian; Oestergaard Jensen, Morten; Peters, Guenther H.; Reitzel, Niels; Balashev, Konstantin; Bjoernholm, Thomas

    2003-01-01

    X-ray reflectivity measurements reveal a significant dewetting of a large hydrophobic paraffin surface floating on water. The dewetting phenomenon extends less than 15 A into the bulk water phase and results in an integrated density deficit of about one water molecule per 25-30 A 2 of water in contact with the paraffin surface. The results are supported by molecular dynamics simulations and related to the hydrophobic effect

  13. Hydrophobic and superhydrophobic surfaces fabricated using atmospheric pressure cold plasma technology: A review.

    Science.gov (United States)

    Dimitrakellis, Panagiotis; Gogolides, Evangelos

    2018-04-01

    Hydrophobic surfaces are often used to reduce wetting of surfaces by water. In particular, superhydrophobic surfaces are highly desired for several applications due to their exceptional properties such as self-cleaning, anti-icing, anti-friction and others. Such surfaces can be prepared via numerous methods including plasma technology, a dry technique with low environmental impact. Atmospheric pressure plasma (APP) has recently attracted significant attention as lower-cost alternative to low-pressure plasmas, and as a candidate for continuous rather than batch processing. Although there are many reviews on water-repellent surfaces, and a few reviews on APP technology, there are hardly any review works on APP processing for hydrophobic and superhydrohobic surface fabrication, a topic of high importance in nanotechnology and interface science. Herein, we critically review the advances on hydrophobic and superhydrophobic surface fabrication using APP technology, trying also to give some perspectives in the field. After a short introduction to superhydrophobicity of nanostructured surfaces and to APPs we focus this review on three different aspects: (1) The atmospheric plasma reactor technology used for fabrication of (super)hydrophobic surfaces. (2) The APP process for hydrophobic surface preparation. The hydrophobic surface preparation processes are categorized methodologically as: a) activation, b) grafting, c) polymerization, d) roughening and hydrophobization. Each category includes subcategories related to different precursors used. (3) One of the most important sections of this review concerns superhydrophobic surfaces fabricated using APP. These are methodologically characterized as follows: a) single step processes where micro-nano textured topography and low surface energy coating are created at the same time, or b) multiple step processes, where these steps occur sequentially in or out of the plasma. We end the review with some perspectives in the field. We

  14. Molecular-scale hydrophobic interactions between hard-sphere reference solutes are attractive and endothermic.

    Science.gov (United States)

    Chaudhari, Mangesh I; Holleran, Sinead A; Ashbaugh, Henry S; Pratt, Lawrence R

    2013-12-17

    The osmotic second virial coefficients, B2, for atomic-sized hard spheres in water are attractive (B2 attractive with increasing temperature (ΔB2/ΔT attractive and endothermic at moderate temperatures. Hydrophobic interactions between atomic-sized hard spheres in water are more attractive than predicted by the available statistical mechanical theory. These results constitute an initial step toward detailed molecular theory of additional intermolecular interaction features, specifically, attractive interactions associated with hydrophobic solutes.

  15. Separation of deuterium by H2/H2O reaction with hydrophobic platinum catalyst

    International Nuclear Information System (INIS)

    Kitamoto, A.; Takashima, Y.; Shimizu, M.

    The separation performance of a trickle bed exchange column packed with a hydrophobic or waterproof catalyst is related to operating conditions such as hydrogen surface velocity, water flow rate, and temperature. The optimum carrier type and catalyst platinum content were determined. The continuous injection of roughly 10 3 ppm O 2 regenerates the catalyst effectively. The ratio of hydrophobic catalyst to hydrophilic packing is an important factor in increasing the exchange rate in deuterium extraction

  16. Hydrophobic coating of microfluidic chips structured by SU-8 polymer for segmented flow operation

    International Nuclear Information System (INIS)

    Schumacher, J T; Grodrian, A; Metze, J; Kremin, C; Hoffmann, M

    2008-01-01

    We present a hydrophobization procedure for SU-8-based microfluidic chips on borofloat substrates. Different layouts of gold electrodes passivated by the polymer have been investigated. The chips are used for segmented flow in a two-fluid mode that requires a distinct hydrophobicity of the channel walls which is generated by the use of specific silane. In this paper we describe the production and silanization of the chips and demonstrate segmented flow operation

  17. Hydrophobic Light-to-Heat Conversion Membranes with Self-Healing Ability for Interfacial Solar Heating

    KAUST Repository

    Zhang, Lianbin

    2015-07-01

    Self-healing hydrophobic light-to-heat conversion membranes for interfacial solar heating are fabricated by deposition of light-to-heat conversion material of polypyrrole onto porous stainless steel mesh, followed by hydrophobic fluoroalkylsilane modification. The mesh-based membranes spontaneously stay at the water–air interface, collect and convert solar light into heat, and locally heat only the water surface for an enhanced evaporation.

  18. Mutation of exposed hydrophobic amino acids to arginine to increase protein stability

    OpenAIRE

    Strub, Caroline; Alies, Carole; Lougarre, Andrée; Ladurantie, Caroline; Czaplicki, Jerzy; Fournier, Didier

    2004-01-01

    Abstract Background One strategy to increase the stability of proteins is to reduce the area of water-accessible hydrophobic surface. Results In order to test it, we replaced 14 solvent-exposed hydrophobic residues of acetylcholinesterase by arginine. The stabilities of the resulting proteins were tested using denaturation by high temperature, organic solvents, urea and by proteolytic digestion. Conclusion Altough the mutational effects were rather small, this strategy proved to be successful...

  19. Hydrophobic Light-to-Heat Conversion Membranes with Self-Healing Ability for Interfacial Solar Heating

    KAUST Repository

    Zhang, Lianbin; Tang, Bo; Wu, Jinbo; Li, Renyuan; Wang, Peng

    2015-01-01

    Self-healing hydrophobic light-to-heat conversion membranes for interfacial solar heating are fabricated by deposition of light-to-heat conversion material of polypyrrole onto porous stainless steel mesh, followed by hydrophobic fluoroalkylsilane modification. The mesh-based membranes spontaneously stay at the water–air interface, collect and convert solar light into heat, and locally heat only the water surface for an enhanced evaporation.

  20. Effects of large volume injection of aliphatic alcohols as sample diluents on the retention of low hydrophobic solutes in reversed-phase liquid chromatography.

    Science.gov (United States)

    David, Victor; Galaon, Toma; Aboul-Enein, Hassan Y

    2014-01-03

    Recent studies showed that injection of large volume of hydrophobic solvents used as sample diluents could be applied in reversed-phase liquid chromatography (RP-LC). This study reports a systematic research focused on the influence of a series of aliphatic alcohols (from methanol to 1-octanol) on the retention process in RP-LC, when large volumes of sample are injected on the column. Several model analytes with low hydrophobic character were studied by RP-LC process, for mobile phases containing methanol or acetonitrile as organic modifiers in different proportions with aqueous component. It was found that starting with 1-butanol, the aliphatic alcohols can be used as sample solvents and they can be injected in high volumes, but they may influence the retention factor and peak shape of the dissolved solutes. The dependence of the retention factor of the studied analytes on the injection volume of these alcohols is linear, with a decrease of its value as the sample volume is increased. The retention process in case of injecting up to 200μL of upper alcohols is dependent also on the content of the organic modifier (methanol or acetonitrile) in mobile phase. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Fabrication and hydrophobic characteristics of micro / nanostructures on polydimethylsiloxane surface prepared by picosecond laser

    Science.gov (United States)

    Bin, Wang; Dong, Shiyun; Yan, Shixing; Gang, Xiao; Xie, Zhiwei

    2018-03-01

    Picosecond laser has ultrashort pulse width and ultrastrong peak power, which makes it widely used in the field of micro-nanoscale fabrication. polydimethylsiloxane (PDMS) is a typical silicone elastomer with good hydrophobicity. In order to further improve the hydrophobicity of PDMS, the picosecond laser was used to fabricate a grid-like microstructure on the surface of PDMS, and the relationship between hydrophobicity of PDMS with surface microstructure and laser processing parameters, such as processing times and cell spacing was studied. The results show that: compared with the unprocessed PDMS, the presence of surface microstructure significantly improved the hydrophobicity of PDMS. When the number of processing is constant, the hydrophobicity of PDMS decreases with the increase of cell spacing. However, when the cell spacing is fixed, the hydrophobicity of PDMS first increases and then decreases with the increase of processing times. In particular, when the times of laser processing is 6 and the cell spacing is 50μm, the contact angle of PDMS increased from 113° to 154°, which reached the level of superhydrophobic.

  2. Characteristics improvement of hydrophobic polytetrafluoroethylene-platinum catalysts for tritium separation

    International Nuclear Information System (INIS)

    Popescu, I.; Ionita, Gh.; Dobrinescu, D.; Varlam, C.; Stefanescu, I.

    2006-01-01

    Full text: Based on the long experience of the authors in the preparation, testing and evaluation of the performances of hydrophobic catalysts and based on the reviewed references, this paper presents up-to-date R and D activities on the preparation methods and applications of the hydrophobic catalysts in tritium separation. The objectives of the paper are: how to improve the characteristics and performance of platinum hydrophobic catalysts; to assess and find a new procedure for the preparation of a new improved hydrophobic catalyst. From reviewed references one can conclude that platinum is the most active and efficient catalytic metal while the polytetrafluoroethylene is the best wet-proofing agent. A new improved hydrophobic Pt-catalyst has been proposed and its testing is now underway. The main steps and experimental conditions of preparation are thoroughly discussed. A new wet-proofing agent and new binders (titanium dioxide, cerium dioxide, zirconium dioxide) with a catalytic role are proposed and tested. The physico-structural parameters of the improved catalyst have been determined and are discussed in detail. The new proposal is a promising idea to improve the performance of conventional hydrophobic Pt-catalysts. (authors)

  3. The hydrophilic/hydrophobic ratio vs. dissolved organics removal by coagulation – A review

    Directory of Open Access Journals (Sweden)

    Djamel Ghernaout

    2014-07-01

    Full Text Available This review discusses the hydrophilic/hydrophobic ratio as a function of the hydrophilic and hydrophobic contents removal by coagulation process. It is well established that coagulation process could bring a reduction in dissolved organic carbon of around 30–60% by increasing the coagulant dose and optimising reaction pH, in which large organic molecules with hydrophobic property was removed preferentially. Furthermore, the literature affirmed that the greater removal of UV-absorbing substances indicates that alum coagulation preferentially removed the hydrophobic fraction of the total organic carbon. For the hydrophobic fraction, it needs to be removed entirely without its transformation into hydrophilic fractions by coagulation process avoiding pre-chlorination/pre-oxidation due to the risk of organic molecules fragmentation. Determining the exact numerical values of the hydrophilic/hydrophobic ratio for raw water and treated water at different stages of the treatment processes in a water treatment plant, as for the DCO/DBO5 ratio in the case of wastewater treatment, would help on more focusing on OM control and removal.

  4. A study of degradation resistance and cytocompatibility of super-hydrophobic coating on magnesium.

    Science.gov (United States)

    Zhang, Yufen; Feyerabend, Frank; Tang, Shawei; Hu, Jin; Lu, Xiaopeng; Blawert, Carsten; Lin, Tiegui

    2017-09-01

    Calcium stearate based super-hydrophobic coating was deposited on plasma electrolytic oxidation (PEO) pre-treated magnesium substrate. The pre-treated magnesium and super-hydrophobic coating covered sample were characterized by scanning electron microscopy, X-ray diffraction and electrochemical corrosion measurements. The cytocompatibility and degradation resistance of magnesium, pre-treated magnesium and super-hydrophobic coating were analysed in terms of cell adhesion and osteoblast differentiation. The results indicate that the calcium stearate top coating shows super-hydrophobicity and that the surface is composed of micro/nanostructure. The super-hydrophobic coating covered sample shows higher barrier properties compared with the PEO pre-treated magnesium and bare magnesium. Human osteoblast proliferation, but not differentiation is enhanced by the PEO coating. Contrary, the super-hydrophobic coating reduces proliferation, but enhances differentiation of osteoblast, observable by the formation of hydroxyapatite. The combination of corrosion protection and cell reaction indicates that this system could be interesting for biomedical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. The role of hydrophobic interactions for the formation of gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, R.H.; Wang, J.; Eriksson, J.C. [Virginia Polytech Inst. and State Univ., Blacksburg, VA (United States). Center for Advanced Separation Technologies; Sum, A.K. [Colorado School of Mines, Golden, CO (United States). Dept. of Chemical Engineering

    2008-07-01

    The process of hydrate formation remains largely unexplained due to a lack of evidence for the water molecules around the hydrophobic solute such as methane, and the nucleation process leading to the clustering that induces hydrate growth. However, the water structure is known to play a major role in the mechanism for hydrate nucleation. This paper presented evidence that hydrophobic solutes promote the structuring of water. Water molecules at room temperature tend to form ice structures around the hydrocarbon chains of surfactant molecules dissolved in water. An atomic force microscope (AFM) was used in this study to measure the surface forces between thiolated gold surfaces. The purpose was to better understand the structure of the thin films of water between hydrophobic surfaces. The water molecules tended to reorganize themselves to form ordered structures, which may be related to the nucleation of hydrates. The entropy reduction associated with the ice structure can be considered as the net driving force for self-assembly. Recent studies have revealed that long-range attractive forces exist between hydrophobic surfaces, which are likely to result from structuring of the water molecules in the vicinity of the hydrophobic surfaces. Similarly, the hydrophobic nature of most gas hydrate formers may induce ordering of water molecules in the vicinity of dissolved solutes. It was concluded that the results of this study may be used to develop a new mechanism for the formation of gas hydrates, including methane. 20 refs., 2 figs.

  6. Non-invasive high throughput approach for protein hydrophobicity determination based on surface tension.

    Science.gov (United States)

    Amrhein, Sven; Bauer, Katharina Christin; Galm, Lara; Hubbuch, Jürgen

    2015-12-01

    The surface hydrophobicity of a protein is an important factor for its interactions in solution and thus the outcome of its production process. Yet most of the methods are not able to evaluate the influence of these hydrophobic interactions under natural conditions. In the present work we have established a high resolution stalagmometric method for surface tension determination on a liquid handling station, which can cope with accuracy as well as high throughput requirements. Surface tensions could be derived with a low sample consumption (800 μL) and a high reproducibility (content. The protein influence on the solutions' surface tension was correlated to the hydrophobicity of lysozyme, human lysozyme, BSA, and α-lactalbumin. Differences in proteins' hydrophobic character depending on pH and species could be resolved. Within this work we have developed a pH dependent hydrophobicity ranking, which was found to be in good agreement with literature. For the studied pH range of 3-9 lysozyme from chicken egg white was identified to be the most hydrophilic. α-lactalbumin at pH 3 exhibited the most pronounced hydrophobic character. The stalagmometric method occurred to outclass the widely used spectrophotometric method with bromophenol blue sodium salt as it gave reasonable results without restrictions on pH and protein species. © 2015 Wiley Periodicals, Inc.

  7. Quenched polyelectrolytes with hydrophobicity independent from chemical charge fraction: A SANS and SAXS study

    Directory of Open Access Journals (Sweden)

    Souha Ben Mahmoud

    2017-11-01

    Full Text Available We investigate by SANS and SAXS the structure of semidilute aqueous hydrophobic quenched polyelectrolyte solutions, in which we can vary independently the hydrophobicity and the chemical/electrostatic charge fraction (above the Manning condensation threshold 36%. Such a de-correlation is the original point of the work, reached using statistical tri-copolymers poly(acrylamide-co-styrene-co-2-acrylamido-2-methylpropane-sodium sulfonate, poly(AMx-co-STy-co-AMPSz. The hydrophobicity is brought by ST, the chemical electrostatic charge by AMPS and solubility without charge by AM. We consider that although these copolymers have chemical structure different from partially sulfonated polystyrene sulfonate, PS-co-SSNa, made of two monomers, one charged, one hydrophobic, they have however vicinal behavior. The variation of chemical charge, has no strong consequence on the structure properties which is in agreement with the fact that it is always larger than the Manning threshold. The dependence of q∗ with AM content shows that AM reduces hydrophobicity. The similarity with PS-co-SSNa, for which pearl necklace-like conformations were directly measured by SANS (form factor using ZAC method, suggests that pearl necklace conformations are also adopted by these tri-copolymers and that this behavior could be so generalized to a much larger range of synthetic hydrophobic polyelectrolytes using simple copolymerization.

  8. Cationic flocculants carrying hydrophobic functionalities: applications for solid/liquid separation.

    Science.gov (United States)

    Schwarz, S; Jaeger, W; Paulke, B-R; Bratskaya, S; Smolka, N; Bohrisch, J

    2007-07-26

    The flocculation behaviors of three series of polycations with narrow molecular weight distributions carrying hydrophobic substituents on their backbones [poly(N-vinylbenzyl-N,N,N-trimethylammonium chloride), poly(N-vinylbenzyl-N,N-dimethyl-N-butylammonium chloride), and poly(N-vinylbenzylpyridinium chloride)] were investigated in dispersions of monodisperse polystyrene latexes and kaolin. Apparently, the charge density of the polycations decreases with increasing substituent hydrophobicity and increasing molecular weight of the polyelectrolytes. The necessary amount of flocculant for phase separation in dispersions with high substrate surface charge densities increases with increasing hydrophobicity of the polyelectrolyte. Nevertheless, the introduction of hydrophobic functionalities is beneficial, resulting in a substantial broadening of the range between the minimum and maximum amounts of flocculant necessary for efficient flocculation (flocculation window). An increase in ionic strength supports this effect. When the substrate has a low charge density, the hydrophobic interactions play a much more significant role in the flocculation process. Here, the minimum efficient doses remained the same for all three polyelectrolytes investigated, but the width of the flocculation window increased as the polycation hydrophobicity and the molecular weight increased. The necessary amount of flocculant increased with an increase in particle size at constant solid content of the dispersion, as well as with a decreasing number of particles at a constant particle size.

  9. Optically transparent super-hydrophobic thin film fabricated by reusable polyurethane-acrylate (PUA) mold

    Science.gov (United States)

    Park, J.-S.; Park, J.-H.; Lee, D.-W.

    2018-02-01

    In this paper, we describe a simple manufacturing method for producing an optically transparent super-hydrophobic polymer thin film using a reusable photo-curable polymer mold. Soluble photoresist (PR) molds were prepared with under-exposed and under-baked processes, which created unique hierarchical micro/nano structures. The reverse phase of the PR mold was replicated on the surface of polydimethylsiloxane (PDMS) substrates. The unique patterns on the replicated PDMS molds were successfully transferred back to the UV curable polyurethane-acrylate (PUA) using a laboratory-made UV exposure system. Continuous production of the super-hydrophobic PDMS thin film was demonstrated using the reusable PUA mold. In addition, hydrophobic nano-silica powder was sprayed onto the micro/nano structured PDMS surfaces to further improve hydrophobicity. The fabricated PDMS thin films with hierarchical surface texturing showed a water contact angle  ⩾150°. Excellent optical transmittance within the range of visible light of wavelengths between 400-800 nm was experimentally confirmed using a spectrophotometer. High efficiency of the super-hydrophobic PDMS film in optical transparency was also confirmed using solar panels. The fabricated PUA molds are very suitable for use in roll-to-roll or roll-to-plate systems which allow continuous production of super-hydrophobic thin films with an excellent optical transparency.

  10. Biochemical characterization of the small hydrophobic protein of avian metapneumovirus.

    Science.gov (United States)

    Deng, Qiji; Song, Minxun; Demers, Andrew; Weng, Yuejin; Lu, Wuxun; Wang, Dan; Kaushik, Radhey S; Yu, Qingzhong; Li, Feng

    2012-08-01

    Avian metapneumovirus (AMPV) is a paramyxovirus that has three membrane proteins (G, F, and SH). Among them, the SH protein is a small type II integral membrane protein that is incorporated into virions and is only present in certain paramyxoviruses. In the present study, we show that the AMPV SH protein is modified by N-linked glycans and can be released into the extracellular environment. Furthermore, we demonstrate that glycosylated AMPV SH proteins form homodimers through cysteine-mediated disulfide bonds, which has not been reported previously for SH proteins of paramyxoviruses. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Green technological approach to synthesis hydrophobic stable crystalline calcite particles with one-pot synthesis for oil-water separation during oil spill cleanup.

    Science.gov (United States)

    Wu, Min-Nan; Maity, Jyoti Prakash; Bundschuh, Jochen; Li, Che-Feng; Lee, Chin-Rong; Hsu, Chun-Mei; Lee, Wen-Chien; Huang, Chung-Ho; Chen, Chien-Yen

    2017-10-15

    The process of separating oil and water from oil/water mixtures is an attractive strategy to answer the menace caused by industrial oil spills and oily wastewater. In addition, water coproduced during hydrocarbon exploitation, which can be an economic burden and risk for freshwater resources, can become an important freshwater source after suitable water-oil separation. For oil-water separation purposes, considerable attention has been paid to the preparation of hydrophobic-oleophilic materials with modified surface roughness. However, due to issues of thermodynamic instability, costly and complex methods as well as lack of ecofriendly compounds, most of hydrophobic surface modified particles are of limited practical application. The study presents a facile procedure, to synthesize crystalline particles of calcite, which is the most stable polymorph of CaCO 3 from industrial CaCO 3 using oleic acid as an additive in a one-pot synthesis method. The XRD results show that the synthesized particles were a well-crystallized form of calcite. The FTIR results reflect the appearance of the alkyl groups from the oleic acid in synthesized particles which promotes the production of calcite with 'rice shape' (1.64 μm) (aggregated by spherical nanoparticle of 19.56 nm) morphology with concomitant changes in its surface wettability from hydrophilic to hydrophobic. The synthesized particles exhibited near to super hydrophobicity with ∼99% active ratio and a contact angle of 143.8°. The synthesized hydrophobic calcite particles had an oleophilic nature where waste diesel oil adsorption capacity of synthesized calcium carbonate (HCF) showed a very high (>99%) and fast (7 s) oil removal from oil-water mixture. The functional group of long alkyl chain including of CO bounds may play critical roles for adsorption of diesel oils. Moreover, the thermodynamically stable crystalline polymorph calcite (compared to vaterite) exhibited excellent recyclability. The isothermal study

  12. Preferential hydrophobic interactions are responsible for a preference of D-amino acids in the aminoacylation of 5'-AMP with hydrophobic amino acids

    Science.gov (United States)

    Lacey, J. C. Jr; Wickramasinghe, N. S.; Sabatini, R. S.

    1992-01-01

    We have studied the chemistry of aminoacyl AMP to model reactions at the 3' terminus of aminoacyl tRNA for the purpose of understanding the origin of protein synthesis. The present studies relate to the D, L preference in the esterification of 5'-AMP. All N-acetyl amino acids we studied showed faster reaction of the D-isomer, with a generally decreasing preference for D-isomer as the hydrophobicity of the amino acid decreased. The beta-branched amino acids, Ile and Val, showed an extreme preference for D-isomer. Ac-Leu, the gamma-branched amino acid, showed a slightly low D/L ratio relative to its hydrophobicity. The molecular basis for these preferences for D-isomer is understandable in the light of our previous studies and seems to be due to preferential hydrophobic interaction of the D-isomer with adenine. The preference for hydrophobic D-amino acids can be decreased by addition of an organic solvent to the reaction medium. Conversely, peptidylation with Ac-PhePhe shows a preference for the LL isomer over the DD isomer.

  13. An assessment on preparation methods and applications of hydrophobic Pt-catalyst in nuclear and environmental field

    International Nuclear Information System (INIS)

    Ionita, Gh.; Stefanescu, I.; Varlam, Carmen

    2001-01-01

    Based on the long experience of the authors in the preparation, testing and evaluation of the performances of hydrophobic catalysts and based on the reviewed references, this paper presents up-to-date R and D activities on the preparation and application of hydrophobic catalysts for use in nuclear and environmental fields. Unlike the conventional hydrophilic catalysts, the hydrophobic catalysts repel the liquid water and allow the transport of the gaseous reactants and reaction products to and from catalytic active centers. For deuterium and tritium separation, over one hundred hydrophobic catalyst types have been prepared in different experimental conditions and by a large diversity of wet proofing methods. The influence of about twenty parameters on catalytic activity have been also studied. The purpose of this paper is: (1) to provide a database for preparation and selection of he most appropriate method for preparing an active hydrophobic catalyst, (2) to show how to use the hydrophobic catalyst and how to operate efficiently the reactor packed with hydrophobic catalyst, (3) to evaluate the performances and potentiality of hydrophobic catalysts in nuclear and environmental field, (4) evaluation of applications of hydrophobic catalysts in nuclear and environmental fields. As result, the following categories are shown: (1) the hydrophobic catalysts based on platinum and Teflon as wet-proofing proved to have the highest activity and the longest stability, (2) the utilization of hydrophobic catalyst as ordered mixed catalytic packing in the trickle bed or separated bed reactors is more efficient and has been entirely proved on industrial scale for tritium separation process, (3) the extension of the applications of hydrophobic catalysts for other processes which take place in the presence of saturated humidity or liquid water in environmental protection field. The merits of hydrophobic Pt-catalysts for tritium separation are discussed in comparison to other

  14. Porous membrane modifier as a new trend for deoiling process

    Directory of Open Access Journals (Sweden)

    Nermen H. Mohamed

    2017-09-01

    Full Text Available Porous membranes are prepared through micro phase separation of immiscible polymers consisting of hydrophobic polymer (polystyrene and hydrophilic polymer (poly(2-vinylpyridine. The greatest difficulties during petrolatum deoiling are related to the filtration stage for obtaining microcrystalline wax. The present study deals with the addition of porous membrane as modifier for the crystal structure of solid hydrocarbons, which will be the cornerstone in rearrangement and reformulation of new hard crystals in deoiling process. XRD and SEM photographs were used to evaluate the crystallinity and crystal sizes of the separated hard waxes.

  15. A New Route for Preparation of Hydrophobic Silica Nanoparticles Using a Mixture of Poly(dimethylsiloxane and Diethyl Carbonate

    Directory of Open Access Journals (Sweden)

    Iryna Protsak

    2018-01-01

    Full Text Available Organosilicon layers chemically anchored on silica surfaces show high carbon content, good thermal and chemical stability and find numerous applications as fillers in polymer systems, thickeners in dispersing media, and as the stationary phases and carriers in chromatography. Methyl-terminated poly(dimethylsiloxanes (PDMSs are typically considered to be inert and not suitable for surface modification because of the absence of readily hydrolyzable groups. Therefore, in this paper, we report a new approach for surface modification of silica (SiO2 nanoparticles with poly(dimethylsiloxanes with different lengths of polymer chains (PDMS-20, PDMS-50, PDMS-100 in the presence of diethyl carbonate (DEC as initiator of siloxane bond splitting. Infrared spectroscopy (IR, elemental analysis (CHN, transmission electron microscopy (TEM, atomic force microscopy (AFM, rotational viscosity and contact angle of wetting were employed for the characterization of the raw fumed silica and modified silica nanoparticles. Elemental analysis data revealed that the carbon content in the grafted layer is higher than 8 wt % for all modified silicas, but it decreases significantly after sample treatment in polar media for silicas which were modified using neat PDMS. The IR spectroscopy data indicated full involvement of free silanol groups in the chemisorption process at a relatively low temperature (220 °C for all resulting samples. The contact angle studies confirmed hydrophobic surface properties of the obtained materials. The rheology results illustrated that fumed silica modified with mixtures of PDMS-x/DEC exhibited thixotropic behavior in industrial oil (I-40A, and exhibited a fully reversible nanostructure and shorter structure recovery time than nanosilicas modified with neat PDMS. The obtained results from AFM and TEM analysis revealed that the modification of fumed silica with mixtures of PDMS-20/DEC allows obtaining narrow particle size distribution with

  16. Use of hydrophobic Pt-catalysts in tritium removal from effluents

    International Nuclear Information System (INIS)

    Gheorghe, Ionita; Popescu, Irina; Stefanescu, Ioan; Steflea, Dumitru; Varlam, Carmen

    2002-01-01

    Based on the long experience of the authors, in the preparation, testing and evaluation of the performances of hydrophobic catalysts, and based on the reviewed references, this paper presents up-to-date R and D activities on the application of the hydrophobic catalysts in tritium removal from nuclear effluents. Tritium removal from the heavy water reactor and nuclear reprocessing plant, the cleanup of atmosphere and gaseous effluents by hydrogen-oxygen recombination, removal of oxygen dissolved in water are presented and discussed. Unlike the conventional hydrophilic catalysts, the hydrophobic catalysts keep a high catalytic activity and stability, even under the direct contact to liquid water or in presence of saturated humidity. A large diversity of catalyst types (over 100 catalysts) was prepared and tested in order to make them feasible for such processes. The objectives of the review are: - to provide a database for selection of the most appropriate catalyst and catalytic packing for above mentioned processes; - the designing and operation of reactor packed with hydrophobic catalysts; - to evaluate the potentiality of hydrophobic Pt-catalysts in the present and future applications. The most important results are the following: - the hydrophobic Pt-catalysts packed in the trickle bed or separated bed reactors, showed a high catalytic activity and long stability; - the utilization of the hydrophobic Pt-catalysts for the hydrogen isotopes (tritium and deuterium) separation and for hydrogen-oxygen recombination in nuclear field was entirely confirmed on industrial scale; - the improvement of the inner geometry of the reactors and of the composition of mixed catalytic packing as well as the evaluation of performances of separation processes constitute a major contribution of the authors; - the extension of the utilization of the hydrophobic Pt-catalysts in the oxidation of volatile organic compounds from wastewater; - the removal of dissolved oxygen, and deuterium

  17. On Modified Bar recursion

    DEFF Research Database (Denmark)

    Oliva, Paulo Borges

    2002-01-01

    Modified bar recursion is a variant of Spector's bar recursion which can be used to give a realizability interpretation of the classical axiom of dependent choice. This realizability allows for the extraction of witnesses from proofs of forall-exists-formulas in classical analysis. In this talk I...... shall report on results regarding the relationship between modified and Spector's bar recursion. I shall also show that a seemingly weak form of modified bar recursion is as strong as "full" modified bar recursion in higher types....

  18. Identification of potential hydrophobic properties of carbon layer from the coffee bean waste

    Science.gov (United States)

    Fitria, D.; Baroroh, L. A. Al; Destyorini, F.; Widayatno, W. B.; Amal, M. I.; Wismogroho, A. S.

    2018-03-01

    The significant increase of waste due to vast development of human civilization and industrialization has plunged humanity into various environmental issues. Nowadays, the concern on waste handling and conversion into more valuable material has become one of hot research topics. Biomass waste has great abundance with various types that can be utilized for many applications such as landfill, recycled-material, adsorbent, separation, catalysis, and so on. In this study, coffee bean waste (CBW) was used as a source to produce hydrophobic layer. The CBW was converted into amorphous carbon using simple carbonization method at 500 °C, dispersed in acetic acid and then mixed with polyvinyl alcohol (PVA) at low temperature heating. In order to investigate effects of composition on hydrophobicity properties, ratio of carbon and PVA was varied. In addition, acetic acid was used to evaluate effect of dispersant on hydrophobic properties. SEM analysis reveals unique morphology of carbon layer. The measurement of contact angle demonstrates that this unique morphology possesses comparable hydrophobicity with that of some well-known materials. Fourier transform infrared spectroscopy (FTIR) analysis confirms the effect of PVA bonding and carbon layer on its hydrophobicity.

  19. Unravelling the hydrophobicity of urea in water using thermodiffusion: implications for protein denaturation.

    Science.gov (United States)

    Niether, Doreen; Di Lecce, Silvia; Bresme, Fernando; Wiegand, Simone

    2018-01-03

    Urea is widely used as a protein denaturant in aqueous solutions. Experimental and computer simulation studies have shown that it dissolves in water almost ideally at high concentrations, introducing little disruption in the water hydrogen bonded structure. However, at concentrations of the order of 5 M or higher, urea induces denaturation in a wide range of proteins. The origin of this behaviour is not completely understood, but it is believed to stem from a balance between urea-protein and urea-water interactions, with urea becoming possibly hydrophobic at a specific concentration range. The small changes observed in the water structure make it difficult to connect the denaturation effects to the solvation properties. Here we show that the exquisite sensitivity of thermodiffusion to solute-water interactions allows the identification of the onset of hydrophobicity of urea-water mixtures. The hydrophobic behaviour is reflected in a sign reversal of the temperature dependent slope of the Soret coefficient, which is observed, both in experiments and non-equilibrium computer simulations at ∼5 M concentration of urea in water. This concentration regime corresponds to the one where abrupt changes in the denaturation of proteins are commonly observed. We show that the onset of hydrophobicity is intrinsically connected to the urea-water interactions. Our results allow us to identify correlations between the Soret coefficient and the partition coefficient, log P, hence establishing the thermodiffusion technique as a powerful approach to study hydrophobicity.

  20. Effect of material flexibility on the thermodynamics and kinetics of hydrophobically induced evaporation of water.

    Science.gov (United States)

    Altabet, Y Elia; Haji-Akbari, Amir; Debenedetti, Pablo G

    2017-03-28

    The evaporation of water induced by confinement between hydrophobic surfaces has received much attention due to its suggested functional role in numerous biophysical phenomena and its importance as a general mechanism of hydrophobic self-assembly. Although much progress has been made in understanding the basic physics of hydrophobically induced evaporation, a comprehensive understanding of the substrate material features (e.g., geometry, chemistry, and mechanical properties) that promote or inhibit such transitions remains lacking. In particular, comparatively little research has explored the relationship between water's phase behavior in hydrophobic confinement and the mechanical properties of the confining material. Here, we report the results of extensive molecular simulations characterizing the rates, free energy barriers, and mechanism of water evaporation when confined between model hydrophobic materials with tunable flexibility. A single-order-of-magnitude reduction in the material's modulus results in up to a nine-orders-of-magnitude increase in the evaporation rate, with the corresponding characteristic time decreasing from tens of seconds to tens of nanoseconds. Such a modulus reduction results in a 24-orders-of-magnitude decrease in the reverse rate of condensation, with time scales increasing from nanoseconds to tens of millions of years. Free energy calculations provide the barriers to evaporation and confirm our previous theoretical predictions that making the material more flexible stabilizes the confined vapor with respect to liquid. The mechanism of evaporation involves surface bubbles growing/coalescing to form a subcritical gap-spanning tube, which then must grow to cross the barrier.

  1. Tuning the hydrophobicity of mica surfaces by hyperthermal Ar ion irradiation

    International Nuclear Information System (INIS)

    Keller, Adrian; Ogaki, Ryosuke; Bald, Ilko; Dong Mingdong; Kingshott, Peter; Fritzsche, Monika; Facsko, Stefan; Besenbacher, Flemming

    2011-01-01

    The hydrophobicity of surfaces has a strong influence on their interactions with biomolecules such as proteins. Therefore, for in vitro studies of bio-surface interactions model surfaces with tailored hydrophobicity are of utmost importance. Here, we present a method for tuning the hydrophobicity of atomically flat mica surfaces by hyperthermal Ar ion irradiation. Due to the sub-100 eV energies, only negligible roughening of the surface is observed at low ion fluences and also the chemical composition of the mica crystal remains almost undisturbed. However, the ion irradiation induces the preferential removal of the outermost layer of K + ions from the surface, leading to the exposure of the underlying aluminosilicate sheets which feature a large number of centers for C adsorption. The irradiated surface thus exhibits an enhanced chemical reactivity toward hydrocarbons, resulting in the adsorption of a thin hydrocarbon film from the environment. Aging these surfaces under ambient conditions leads to a continuous increase of their contact angle until a fully hydrophobic surface with a contact angle >80 deg. is obtained after a period of about 3 months. This method thus enables the fabrication of ultrasmooth biological model surfaces with precisely tailored hydrophobicity.

  2. Proline-poor hydrophobic domains modulate the assembly and material properties of polymeric elastin.

    Science.gov (United States)

    Muiznieks, Lisa D; Reichheld, Sean E; Sitarz, Eva E; Miao, Ming; Keeley, Fred W

    2015-10-01

    Elastin is a self-assembling extracellular matrix protein that provides elasticity to tissues. For entropic elastomers such as elastin, conformational disorder of the monomer building block, even in the polymeric form, is essential for elastomeric recoil. The highly hydrophobic monomer employs a range of strategies for maintaining disorder and flexibility within hydrophobic domains, particularly involving a minimum compositional threshold of proline and glycine residues. However, the native sequence of hydrophobic elastin domain 30 is uncharacteristically proline-poor and, as an isolated polypeptide, is susceptible to formation of amyloid-like structures comprised of stacked β-sheet. Here we investigated the biophysical and mechanical properties of multiple sets of elastin-like polypeptides designed with different numbers of proline-poor domain 30 from human or rat tropoelastins. We compared the contributions of these proline-poor hydrophobic sequences to self-assembly through characterization of phase separation, and to the tensile properties of cross-linked, polymeric materials. We demonstrate that length of hydrophobic domains and propensity to form β-structure, both affecting polypeptide chain flexibility and cross-link density, play key roles in modulating elastin mechanical properties. This study advances the understanding of elastin sequence-structure-function relationships, and provides new insights that will directly support rational approaches to the design of biomaterials with defined suites of mechanical properties. © 2015 Wiley Periodicals, Inc.

  3. Improving Hydrophobicity of Glass Surface Using Dielectric Barrier Discharge Treatment in Atmospheric Air

    International Nuclear Information System (INIS)

    Fang Zhi; Qiu Yuchang; Wang Hui; Kuffel, E

    2007-01-01

    Non-thermal plasmas under atmospheric pressure are of great interest in industrial applications, especially in material surface treatment. In this paper, the treatment of a glass surface for improving hydrophobicity using the non-thermal plasma generated by dielectric barrier discharge (DBD) at atmospheric pressure in ambient air is conducted, and the surface properties of the glass before and after the DBD treatment are studied by using contact angle measurement, surface resistance measurement and wet flashover voltage tests. The effects of the applied voltage and time duration of DBD on the surface modification are studied, and the optimal conditions for the treatment are obtained. It is found that a layer of hydrophobic coating is formed on the glass surface after spraying a thin layer of silicone oil and undergoing the DBD treatment, and the improvement of hydrophobicity depends on DBD voltage and treating time. It seems that there exists an optimum treating time for a certain applied voltage of DBD during the surface treatment. The test results of thermal aging and chemical aging show that the hydrophobic layer has quite stable characteristics. The interaction mechanism between the DBD plasma and the glass surface is discussed. It is concluded that CH 3 and large molecule radicals can react with the radicals in the glass surface to replace OH, and the hydrophobicity of the glass surface is improved accordingly

  4. On gel electrophoresis of dielectric charged particles with hydrophobic surface: A combined theoretical and numerical study.

    Science.gov (United States)

    Majee, Partha Sarathi; Bhattacharyya, Somnath; Gopmandal, Partha Pratim; Ohshima, Hiroyuki

    2018-03-01

    A theoretical study on the gel electrophoresis of a charged particle incorporating the effects of dielectric polarization and surface hydrophobicity at the particle-liquid interface is made. A simplified model based on the weak applied field and low charge density assumption is also presented and compared with the full numerical model for a nonpolarizable particle to elucidate the nonlinear effects such as double layer polarization and relaxation as well as surface conduction. The main motivation of this study is to analyze the electrophoresis of the surface functionalized nanoparticle with tunable hydrophobicity or charged fluid drop in gel medium by considering the electrokinetic effects and hydrodynamic interactions between the particle and the gel medium. An effective medium approach, in which the transport in the electrolyte-saturated hydrogel medium is governed by the Brinkman equation, is adopted in the present analysis. The governing electrokinetic equations based on the conservation principles are solved numerically. The Navier-slip boundary condition along with the continuity condition of dielectric displacement are imposed on the surface of the hydrophobic polarizable particle. The impact of the slip length on the electrophoresis is profound for a thinner Debye layer, however, surface conduction effect also becomes significant for a hydrophobic particle. Impact of hydrophobicity and relaxation effects are higher for a larger particle. Dielectric polarization creates a reduction in its electrophoretic propulsion and has negligible impact at the thinner Debye length as well as lower gel screening length. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Heating and reduction affect the reaction with tannins of wine protein fractions differing in hydrophobicity.

    Science.gov (United States)

    Marangon, Matteo; Vincenzi, Simone; Lucchetta, Marco; Curioni, Andrea

    2010-02-15

    During the storage, bottled white wines can manifest haziness due to the insolubilisation of the grape proteins that may 'survive' in the fermentation process. Although the exact mechanism of this occurrence is not fully understood, proteins and tannins are considered two of the key factors involved in wine hazing, since their aggregation leads to the formation of insoluble particles. To better understand this complex interaction, proteins and tannins from the same unfined Pinot grigio wine were separated. Wine proteins were then fractionated by hydrophobic interaction chromatography (HIC). A significant correlation between hydrophobicity of the wine protein fractions and the haze formed after reacting with wine tannins was found, with the most reactive fractions revealing (by SDS-PAGE and RP-HPLC analyses) the predominant presence of thaumatin-like proteins. Moreover, the effects of both protein heating and disulfide bonds reduction (with dithiotreithol) on haze formation in the presence of tannins were assessed. These treatments generally resulted in an improved reactivity with tannins, and this phenomenon was related to both the surface hydrophobicity and composition of the protein fractions. Therefore, haze formation in wines seems to be related to hydrophobic interactions occurring among proteins and tannins. These interactions should occur on hydrophobic tannin-binding sites, whose exposition on the proteins can depend on both protein heating and reduction. Copyright 2009 Elsevier B.V. All rights reserved.

  6. Breakup Behavior of a Capillary Bridge on a Hydrophobic Stripe Separating Two Hydrophilic Stripes

    Science.gov (United States)

    Hartmann, Maximilian; Hardt, Steffen

    2017-11-01

    The breakup dynamics of a capillary bridge on a hydrophobic area between two liquid filaments occupying two parallel hydrophilic stripes is studied experimentally. In addition calculations with the finite-element software Surface Evolver are performed to obtain the corresponding stable minimal surfaces. Droplets of de-ionized water are placed on substrates with alternating hydrophilic and hydrophobic stripes of different width. Their volume decreases by evaporation. This results in a droplet shaped as the letter ``H'' covering two hydrophilic stripes separated by one hydrophobic stripe. The width of the capillary bridge d(t) on the hydrophobic stripe during the breakup process is observed using a high-speed camera mounted on a bright-field microscope. The results of the experiments and the numerical studies show that the critical width dcrit, indicating the point where the capillary bridge becomes unstable, mainly depends on the width ratio of the hydrophilic and hydrophobic stripes. It is found that the time derivative of d(t) first decreases after dcrit has been reached. The final breakup dynamics then follows a t 2 / 3 scaling. We kindly acknowledge the financial support by the German Research Foundation (DFG) within the Collaborative Research Centre 1194 ``Interaction of Transport and Wetting Processes'', Project A02a.

  7. Hydrophobicity Tuning by the Fast Evolution of Mold Temperature during Injection Molding

    Directory of Open Access Journals (Sweden)

    Sara Liparoti

    2018-03-01

    Full Text Available The surface topography of a molded part strongly affects its functional properties, such as hydrophobicity, cleaning capabilities, adhesion, biological defense and frictional resistance. In this paper, the possibility to tune and increase the hydrophobicity of a molded polymeric part was explored. An isotactic polypropylene was injection molded with fast cavity surface temperature evolutions, obtained adopting a specifically designed heating system layered below the cavity surface. The surface topology was characterized by atomic force microscopy (AFM and, concerning of hydrophobicity, by measuring the water static contact angle. Results show that the hydrophobicity increases with both the temperature level and the time the cavity surface temperature was kept high. In particular, the contact angle of the molded sample was found to increase from 90°, with conventional molding conditions, up to 113° with 160 °C of cavity surface temperature kept for 18 s. This increase was found to be due to the presence of sub-micro and nano-structures characterized by high values of spatial frequencies which could be more accurately replicated by adopting high heating temperatures and times. The surface topography and the hydrophobicity resulted therefore tunable by selecting appropriate injection molding conditions.

  8. Spray-coating process in preparing PTFE-PPS composite super-hydrophobic coating

    Directory of Open Access Journals (Sweden)

    Rui Weng

    2014-03-01

    Full Text Available In order to improve the performance of a liquid-floated rotor micro-gyroscope, the resistance of the moving interface between the rotor and the floating liquid must be reduced. Hydrophobic treatment can reduce the frictional resistance between such interfaces, therefore we proposed a method to prepare a poly-tetrafluoroethylene (PTFE-poly-phenylene sulphide (PPS composite super-hydrophobic coating, based on a spraying process. This method can quickly prepare a continuous, uniform PTFE-PPS composite super-hydrophobic surface on a 2J85 material. This method can be divided into three steps, namely: pre-treatment; chemical etching; and spraying. The total time for this is around three hours. When the PTFE concentration is 4%, the average contact angle of the hydrophobic coating surface is 158°. If silicon dioxide nanoparticles are added, this can further improve the adhesion and mechanical strength of the super-hydrophobic composite coating. The maximum average contact angle can reach as high as 164° when the mass fraction of PTFE, PPS and silicon dioxide is 1:1:1.

  9. Spray-coating process in preparing PTFE-PPS composite super-hydrophobic coating

    Science.gov (United States)

    Weng, Rui; Zhang, Haifeng; Liu, Xiaowei

    2014-03-01

    In order to improve the performance of a liquid-floated rotor micro-gyroscope, the resistance of the moving interface between the rotor and the floating liquid must be reduced. Hydrophobic treatment can reduce the frictional resistance between such interfaces, therefore we proposed a method to prepare a poly-tetrafluoroethylene (PTFE)-poly-phenylene sulphide (PPS) composite super-hydrophobic coating, based on a spraying process. This method can quickly prepare a continuous, uniform PTFE-PPS composite super-hydrophobic surface on a 2J85 material. This method can be divided into three steps, namely: pre-treatment; chemical etching; and spraying. The total time for this is around three hours. When the PTFE concentration is 4%, the average contact angle of the hydrophobic coating surface is 158°. If silicon dioxide nanoparticles are added, this can further improve the adhesion and mechanical strength of the super-hydrophobic composite coating. The maximum average contact angle can reach as high as 164° when the mass fraction of PTFE, PPS and silicon dioxide is 1:1:1.

  10. Analysis of hydrophobic interactions of antagonists with the beta2-adrenergic receptor.

    Science.gov (United States)

    Novoseletsky, V N; Pyrkov, T V; Efremov, R G

    2010-01-01

    The adrenergic receptors mediate a wide variety of physiological responses, including vasodilatation and vasoconstriction, heart rate modulation, and others. Beta-adrenergic antagonists ('beta-blockers') thus constitute a widely used class of drugs in cardiovascular medicine as well as in management of anxiety, migraine, and glaucoma. The importance of the hydrophobic effect has been evidenced for a wide range of beta-blocker properties. To better understand the role of the hydrophobic effect in recognition of beta-blockers by their receptor, we carried out a molecular docking study combined with an original approach to estimate receptor-ligand hydrophobic interactions. The proposed method is based on automatic detection of molecular fragments in ligands and the analysis of their interactions with receptors separately. A series of beta-blockers, based on phenylethanolamines and phenoxypropanolamines, were docked to the beta2-adrenoceptor binding site in the crystal structure. Hydrophobic complementarity between the ligand and the receptor was calculated using the PLATINUM web-server (http://model.nmr.ru/platinum). Based on the analysis of the hydrophobic match for molecular fragments of beta-blockers, we have developed a new scoring function which efficiently predicts dissociation constant (pKd) with strong correlations (r(2) approximately 0.8) with experimental data.

  11. Manufacturing of mushroom-shaped structures and its hydrophobic robustness analysis based on energy minimization approach

    Science.gov (United States)

    Wang, Li; Yang, Xiaonan; Wang, Quandai; Yang, Zhiqiang; Duan, Hui; Lu, Bingheng

    2017-07-01

    The construction of stable hydrophobic surfaces has increasingly gained attention owing to its wide range of potential applications. However, these surfaces may become wet and lose their slip effect owing to insufficient hydrophobic stability. Pillars with a mushroom-shaped tip are believed to enhance hydrophobicity stability. This work presents a facile method of manufacturing mushroom-shaped structures, where, compared with the previously used method, the modulation of the cap thickness, cap diameter, and stem height of the structures is more convenient. The effects of the development time on the cap diameter and overhanging angle are investigated and well-defined mushroom-shaped structures are demonstrated. The effect of the microstructure geometry on the contact state of a droplet is predicted by taking an energy minimization approach and is experimentally validated with nonvolatile ultraviolet-curable polymer with a low surface tension by inspecting the profiles of liquid-vapor interface deformation and tracking the trace of the receding contact line after exposure to ultraviolet light. Theoretical and experimental results show that, compared with regular pillar arrays having a vertical sidewall, the mushroom-like structures can effectively enhance hydrophobic stability. The proposed manufacturing method will be useful for fabricating robust hydrophobic surfaces in a cost-effective and convenient manner.

  12. Study on hydrophobicity degradation of gas diffusion layer in proton exchange membrane fuel cells

    International Nuclear Information System (INIS)

    Yu, Shuchun; Li, Xiaojin; Li, Jin; Liu, Sa; Lu, Wangting; Shao, Zhigang; Yi, Baolian

    2013-01-01

    Highlights: • The hydrophobicity degradation mechanism of GDL was proposed thoroughly. • C-O and C=O groups appeared on the surfaces of GDL after immersion. • The relative content of PTFE in GDL decreased after immersion. • The surfaces and inner structure of GDL destroyed after immersion. - Abstract: As one of the essential components of proton exchange membrane fuel cell (PEMFC), gas diffusion layer (GDL) is of importance on water management, as well on the performance and durability of PEMFC. In this paper, the hydrophobicity degradation of GDL was investigated by immersing it in the 1.0 mol L −1 H 2 SO 4 solution saturated by air for 1200 h. From the measurements of contact angle and water permeability, the hydrophobic characteristics of the pristine and immersed GDLs were compared. To investigate the causes for hydrophobicity degradation, the GDLs were analyzed by scanning electron microscopy, X-ray photoelectron spectroscopy and thermogravimetry. Further, the chemical compositions of H 2 SO 4 solutions before and after immersion test were analyzed with infrared spectroscopy. Results showed that the hydrophobicity of immersed GDL decreased distinctly, which was caused by the damage of physical structure and surface characteristics. Moreover, the immersed GDL showed a worse fuel cell performance than the pristine GDL, especially under a low humidity condition

  13. Hydrophobicity study of kaolinite from La Unión, Antioquia

    Directory of Open Access Journals (Sweden)

    Liliana M. Usuga-Manco

    2015-07-01

    Full Text Available In this research three methodologies to convert the hydrophilic surface of kaolinite into a hydrophobic surface are proposed, this condition is required to recover this mineral by means of froth flotation. Taking into account the anisotropy, zeta potential and complex surface electrical properties of the kaolinite, three surface chemical treatments based on the interacting and absorption of anionic collectors onto the mineral surface, causing an increase in the contact angle and thus increased hydrophobicity of kaolinite were applied. The methodologies proposed were interactions of kaolinite particles with: sodium dodecyl sulfate solutions with concentration 1x10-3M, 1x10-4M, 1x10-5M; sodium dodecyl sulfate solutions 1x10-3M, 1x10-4M, 1x10-5M with further interaction with kerosene solutions 127000 ppm; and oleic acid solutions 1x10-3M, 1x10-4M, 1x10-5M, each one with a five minutes of interaction. The experimental results obtained by zeta potential and contact angle of the kaolinite before and after applying chemical treatments indicate that larger the chain length of the collector and its concentration, bigger the contact angle and so, more hydrophobic the surface (edge or face. In order to optimize, control and understand this solid-liquid interaction phenomenon is suggested to find out about the hydrophobization mechanism of kaolinite with oleic acid and its percentage of hydrophobization.

  14. Modified Allergens for Immunotherapy.

    Science.gov (United States)

    Satitsuksanoa, Pattraporn; Głobińska, Anna; Jansen, Kirstin; van de Veen, Willem; Akdis, Mübeccel

    2018-02-16

    During the past few decades, modified allergens have been developed for use in allergen-specific immunotherapy (AIT) with the aim to improve efficacy and reduce adverse effects. This review aims to provide an overview of the different types of modified allergens, their mechanism of action and their potential for improving AIT. In-depth research in the field of allergen modifications as well as the advance of recombinant DNA technology have paved the way for improved diagnosis and research on human allergic diseases. A wide range of structurally modified allergens has been generated including allergen peptides, chemically altered allergoids, adjuvant-coupled allergens, and nanoparticle-based allergy vaccines. These modified allergens show promise for the development of AIT regimens with improved safety and long-term efficacy. Certain modifications ensure reduced IgE reactivity and retained T cell reactivity, which facilities induction of immune tolerance to the allergen. To date, multiple clinical trials have been performed using modified allergens. Promising results were obtained for the modified cat, grass and birch pollen, and house dust mite allergens. The use of modified allergens holds promise for improving AIT efficacy and safety. There is however a need for larger clinical studies to reliably assess the added benefit for the patient of using modified allergens for AIT.

  15. Immobilization of Gibberella fujikuroi cells with carriers modified by radiation polymerization

    International Nuclear Information System (INIS)

    Lu Zhaoxin; Xie Zhongchuan; Wei Qijiang

    1994-01-01

    Gibberella fujikuroi cells were immobilized on modified carriers (gauze) by using the radiation polymerization technique. The mycelium was firmly adhered to the surface of fibril covered with hydrophobic polymer, poly (diethylene glycol dimethyl acrylate) and hydrophobic-hydrophilic copolymer poly (diethylene glycol dimethyl acrylate-sodium acrylate), but it was not immobilized onto the polyethylene net, which has a similar network structure to that of the modified carrier. The weight of immobilized cells was affected by covered polymer. Gibberellic acid productivity in immobilized cells was similar to that of free cells, and the immobilized cells was of good stability. A optimum culture condition for gibberellic acid production was at pH 5.5 and under 20 ∼ 30 degree C

  16. Modified Chitosan Nanoparticle by Radiation Synthesis: An Approach to Drug Delivery and Bio-Based Additive for Biomedical Applications

    International Nuclear Information System (INIS)

    Pasanphan, W.; Rimdusit, P.; Rattanawongwiboon, T.; Choofong, S.

    2010-01-01

    Self-assembly chitosan nanoparticle (CsNP) has been synthesized via radiolytic methodology using gamma irradiation. The systematic condition in preparation was studied. Chitosan nanoparticle was modified using hydrophobic core of deoxycholic acid (DC) and stearyl methacrylate (SMA) and the hydrophilic shell of polyethylene glycol monomethacrylate (PEG). The hydrophobic/hydrophilic CsNP was prepared for drug carrier molecule. The SMA-CsNP was also conjugated with pyperidine, hindered amine light stabilizer function, to achieve a bio-based additive for biomedical plastic. (author)

  17. Modified Chitosan Nanoparticle by Radiation Synthesis: An Approach to Drug Delivery and Bio-Based Additive for Biomedical Applications

    Energy Technology Data Exchange (ETDEWEB)

    Pasanphan, W.; Rimdusit, P.; Rattanawongwiboon, T.; Choofong, S., E-mail: sciwvm@ku.ac.th, E-mail: pwanvimol@yahoo.com [Kasetsart University, Faculty of Science, Department of Applied Radiation and Isotopes, 50 Phahonyothin Road, Chatuchak, Bangkok 1090 (Thailand)

    2010-07-01

    Self-assembly chitosan nanoparticle (CsNP) has been synthesized via radiolytic methodology using gamma irradiation. The systematic condition in preparation was studied. Chitosan nanoparticle was modified using hydrophobic core of deoxycholic acid (DC) and stearyl methacrylate (SMA) and the hydrophilic shell of polyethylene glycol monomethacrylate (PEG). The hydrophobic/hydrophilic CsNP was prepared for drug carrier molecule. The SMA-CsNP was also conjugated with pyperidine, hindered amine light stabilizer function, to achieve a bio-based additive for biomedical plastic. (author)

  18. A rheological study of hydrophobic-surface-active polymer systems structuration; Etude rheologique de la structuration de systemes polymere hydrophobe-tensioactif

    Energy Technology Data Exchange (ETDEWEB)

    Heinrich, E.

    1997-01-29

    This work deals with the study of the rheology and the structuration of hydrophobic polymer and surfactant systems. The used associative polymers are acrylamide/nonyl methacrylate copolymers and the surfactant is nonionic. They are particularly used for hydrocarbons extraction techniques as drilling (drilling fluids) or wells cementation. The studied materials are first characterized by different analytic techniques. This preliminary stage of the work gives a good insight of the physico-chemical parameters of the systems. The effect of surfactant was shown by studying the variation of Newtonian viscosity as a function of surfactant concentration. This yields bell curves, whose maximum determines the critical aggregation concentration (cac). The hydrophobic effect is analysed in different polymer concentration regimes, in quasi-static conditions, and under shear. The study of the dynamic visco-elasticity of semi-dilute solutions allows to observe the effect of the hydrophobic associations on the relaxation time of the chains. The system can be described as a superposition of two networks of junctions: the network of physical entanglements and a second one formed by the hydrophobic links. Phenomena of structuration have been observed at room temperature for surfactant concentrations close to the cac. The increase of viscosity or elastic modulus can be 3 to 4 orders of magnitude. The effect of the temperature on the structure of the systems is studied as well. The rheological characterization of the Sol-Gel transition is developed and the rheological behavior of the solutions in a structured state shows a critical stress for rupture of the structure. Microscopic observations of the birefringence of the solutions display the existence of lamellar vesicles, which leads to the following assumption: the formation of big spherulites create a rigidification of the macromolecular network. (author) 190 refs.

  19. Creation of hydrophobic surfaces using a paint containing functionalized oxide particles

    Science.gov (United States)

    Sino, Paul Albert L.; Herrera, Marvin U.; Balela, Mary Donnabelle L.

    2017-05-01

    Hydrophobic surfaces were created by coating various substrates (aluminum sheet, soda-lime glass, silicon carbide polishing paper, glass with double-sided adhesive) with paint containing functionalized oxide particles. The paint was created by functionalizing oxide particles (ground ZnO, TiO2 nanoparticles, or TiO2 microparticles) with fluorosilane molecules in absolute ethanol. Water contact angle of samples shows that the coated substrate becomes hydrophobic (water contact angle ≥ 90°). Among the oxides that were used, ground ZnO yielded contact angle exemplifying superhydrophobicity (water contact angle ≥ 150°). Scanning electron micrograph of paint-containing TiO2 nanoparticles shows rough functionalized oxides structures which probably increase the hydrophobicity of the surface.

  20. Enhancing Stability of Perovskite Solar Cells to Moisture by the Facile Hydrophobic Passivation.

    Science.gov (United States)

    Hwang, Insung; Jeong, Inyoung; Lee, Jinwoo; Ko, Min Jae; Yong, Kijung

    2015-08-12

    In this study, a novel and facile passivation process for a perovskite solar cell is reported. Poor stability in ambient atmosphere, which is the most critical demerit of a perovskite solar cell, is overcome by a simple passivation process using a hydrophobic polymer layer. Teflon, the hydrophobic polymer, is deposited on the top of a perovskite solar cell by a spin-coating method. With the hydrophobic passivation, the perovskite solar cell shows negligible degradation after a 30 day storage in ambient atmosphere. Suppressed degradation of the perovskite film is proved in various ways: X-ray diffraction, light absorption spectrum, and quartz crystal microbalance. This simple but effective passivation process suggests new kind of approach to enhance stability of perovskite solar cells to moisture.

  1. Preparation of Pt-PTFE hydrophobic catalyst for hydrogen-water isotope exchange

    International Nuclear Information System (INIS)

    Li Junhua; Kang Yi; Han Yande; Ruan Hao; Dou Qincheng; Hu Shilin

    2001-01-01

    The hydrophobic catalyst used in the hydrogen-water isotope exchange is prepared with Pt as the active metal, PTFE as the hydrophobic material, active carbon or silicon dioxide as the support. The isotope catalytic exchange reaction between hydrogen and water is carried out in the trickle bed and the effects of different carriers, mass fraction of Pt and PTFE on the catalytic activity are discussed. The experimental results show that the activity of Pt-C-PTFE hydrophobic catalyst with the ratio between PTFE and Pt-C from 1 to 2 is higher than other kinds of catalysts and the overall volume transfer coefficient is increased with the increasing of the hydrogen flow rate and reaction temperature

  2. Reversible superhydrophilicity and hydrophobicity switching of V2O5 thin films deposited by magnetron sputtering

    Science.gov (United States)

    Zhang, Chunzi; Peng, Zhiguang; Cui, Xiaoyu; Neil, Eric; Li, Yuanshi; Kasap, Safa; Yang, Qiaoqin

    2018-03-01

    V2O5 thin films are well-known "smart" materials due to their reversible wettability under UV irradiation and dark storage. Their surfaces are usually hydrophobic and turn into hydrophilic under UV irradiation. However, the V2O5 thin films deposited by magnetron sputtering in present work are superhydrophilic and turned into hydrophobic after days' of storage in air. This change can be recovered by heating. The effects of many factors including surface roughness, irradiation from visible light, UV, & X-ray, and storage in air & vacuum on the reversible switching of wettability were investigated. The results show that air absorption is the main factor causing the film surface change from superhydrophilicity to hydrophobicity.

  3. Performance of a Novel Hydrophobic Mesoporous Material for High Temperature Catalytic Oxidation of Naphthalene

    Directory of Open Access Journals (Sweden)

    Guotao Zhao

    2014-01-01

    Full Text Available A high surface area, hydrophobic mesoporous material, MFS, has been successfully synthesized by a hydrothermal synthesis method using a perfluorinated surfactant, SURFLON S-386, as the single template. N2 adsorption and TEM were employed to characterize the pore structure and morphology of MFS. Static water adsorption test indicates that the hydrophobicity of MFS is significantly higher than that of MCM-41. XPS and Py-GC/MS analysis confirmed the existence of perfluoroalkyl groups in MFS which led to its high hydrophobicity. MFS was used as a support for CuO in experiments of catalytic combustion of naphthalene, where it showed a significant advantage over MCM-41 and ZSM-5. SEM was helpful in understanding why CuO-MFS performed so well in the catalytic combustion of naphthalene. Experimental results indicated that MFS was a suitable support for catalytic combustion of large molecular organic compounds, especially for some high temperature catalytic reactions when water vapor was present.

  4. Hydrophobic agglomeration of apatite fines induced by sodium oleate in aqueous solutions

    Directory of Open Access Journals (Sweden)

    Bingqiao Yang

    2018-06-01

    Full Text Available In this work, the hydrophobic agglomeration of apatite fines induced by sodium oleate in aqueous solutions has been investigated through the measurement of agglomeration degree and fractal dimension. The results showed that the agglomeration degree of apatite fines and agglomerates morphology was strongly depended on sodium oleate concentration, pH, stirring speed and time. Better agglomeration degree and more regular agglomerates were achieved at sodium oleate concentration of 5 × 10−5 mol/L under neutral condition. The critical stirring speed for agglomerates rupture was 1000 rev/min, above which, prolonged stirring time would cause breakage and restructure of the agglomerates after a certain stirring time, resulting in lower agglomeration degree and more regular agglomerates. The agglomeration degree of apatite fines could be greatly enhanced with the addition of emulsified kerosene, but only if the apatite surface was hydrophobic enough. Keywords: Hydrophobic agglomeration, Apatite fines, Agglomeration degree, Fractal dimension, Sodium oleate

  5. Supramolecular Complex Antioxidant Consisting of Vitamins C, E and Hydrophilic-Hydrophobic Silica Nanoparticles

    Science.gov (United States)

    Laguta, I. V.; Kuzema, P. O.; Stavinskaya, O. N.; Kazakova, O. A.

    Samples with varied amount of surface trimethylsilyl groups were obtained via gas-phase chemical modification of silica nanoparticles. The biocompatibility tests conducted in erythrocyte suspension have shown that hydrophobization of silica decreases its damaging effect to the cells. Being wettable in aqueous media, partially silylated silicas have higher affinity to hydrophobic bioactive molecules in comparison with the initial silica. Novel antioxidant consisting of vitamins C and E and silica with 40% of surface trimethylsilyl groups was formulated. It was found that supramolecular complexes are formed on the silica surface due to the affinity of water- and fat-soluble antioxidants to hydrophilic silanol and hydrophobic trimethylsilyl groups, respectively. Test reactions (total phenolic index determination, DPPH test) and in vitro studies (spectral analysis of erythrocyte suspensions undergoing UV irradiation) revealed the correlation between antioxidant activity of the complex antioxidant and the vitamins’ content. The antioxidant remained active during long-term storage under standard conditions.

  6. Multivalent-Counterion-Induced Surfactant Multilayer Formation at Hydrophobic and Hydrophilic Solid-Solution Interfaces.

    Science.gov (United States)

    Penfold, Jeffrey; Thomas, Robert K; Li, Peixun; Xu, Hui; Tucker, Ian M; Petkov, Jordan T; Sivia, Devinderjit S

    2015-06-23

    Surface multilayer formation from the anionic-nonionic surfactant mixture of sodium dodecyl dioxyethylene sulfate, SLES, and monododecyl dodecaethylene glycol, C12E12, by the addition of multivalent Al(3+) counterions at the solid-solution interface is observed and characterized by neutron reflectivity, NR. The ability to form surface multilayer structures on hydrophobic and hydrophilic silica and cellulose surfaces is demonstrated. The surface multilayer formation is more pronounced and more well developed on the hydrophilic and hydrophobic silica surfaces than on the hydrophilic and hydrophobic cellulose surfaces. The less well developed multilayer formation on the cellulose surfaces is attributed to the greater surface inhomogeneities of the cellulose surface which partially inhibit lateral coherence and growth of the multilayer domains at the surface. The surface multilayer formation is associated with extreme wetting properties and offers the potential for the manipulation of the solid surfaces for enhanced adsorption and control of the wetting behavior.

  7. Hydrogen isotope separation in hydrophobic catalysts between hydrogen and liquid water

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Linsen, E-mail: yls2005@mail.ustc.edu.cn [China Academy of Engineering Physics, Mianyang 621900 (China); Luo, Deli [Science and Technology on Surface Physics and Chemistry Laboratory, Jiangyou 621907 (China); Tang, Tao; Yang, Wan; Yang, Yong [China Academy of Engineering Physics, Mianyang 621900 (China)

    2015-11-15

    Hydrogen isotope catalytic exchange between hydrogen and liquid water is a very effective process for deuterium-depleted potable water production and heavy water detritiation. To improve the characteristics of hydrophobic catalysts for this type of reaction, foamed and cellular structures of hydrophobic carbon-supported platinum catalysts were successfully prepared. Separation of deuterium or tritium from liquid water was carried out by liquid-phase catalytic exchange. At a gas–liquid ratio of 1.53 and exchange temperature of 70 °C, the theoretical plate height of the hydrophobic catalyst (HETP = 34.2 cm) was slightly lower than previously reported values. Changing the concentration of the exchange column outlet water yielded nonlinear changes in the height of the packing layer. Configurations of deuterium-depleted potable water and detritiation of heavy water provide references for practical applications.

  8. Investigations on reducing microbiologically-influenced corrosion of aluminum by using super-hydrophobic surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Liu Tao, E-mail: liutao@shmtu.edu.c [Institute of Marine Materials Science and Engineering, Shanghai Maritime University, Shanghai 201306 (China); Dong Lihua; Liu Tong; Yin Yansheng [Institute of Marine Materials Science and Engineering, Shanghai Maritime University, Shanghai 201306 (China)

    2010-07-15

    Electrochemical impedance spectroscopy, potentiodynamic polarization and scanning electron microscopy were carried out to determine the effect of super-hydrophobic surfaces on the marine bacterium Vibrio natriegens (V. natriegens) adhesion. Four different samples were prepared in order to investigate the anti-biocorrosion mechanism of super-hydrophobic surfaces. Potentiodynamic polarization suggested that the V. natriegens attached on the surface mainly enhanced the reaction kinetics of the anodic reaction and accelerated the dissolution of aluminum. EIS results were interpreted with different equivalent circuits to model the physicoelectric characteristics of the electrode/biofilm/solution interface. The results showed that neither anodization nor chemical modification could decrease the bacterial adhesion and corrosion rate individually. V. natriegens showed only weak attachment to the super-hydrophobic surface, and the biocorrosion mechanism was closely associated with surface energy and surface topography.

  9. Investigations on reducing microbiologically-influenced corrosion of aluminum by using super-hydrophobic surfaces

    International Nuclear Information System (INIS)

    Liu Tao; Dong Lihua; Liu Tong; Yin Yansheng

    2010-01-01

    Electrochemical impedance spectroscopy, potentiodynamic polarization and scanning electron microscopy were carried out to determine the effect of super-hydrophobic surfaces on the marine bacterium Vibrio natriegens (V. natriegens) adhesion. Four different samples were prepared in order to investigate the anti-biocorrosion mechanism of super-hydrophobic surfaces. Potentiodynamic polarization suggested that the V. natriegens attached on the surface mainly enhanced the reaction kinetics of the anodic reaction and accelerated the dissolution of aluminum. EIS results were interpreted with different equivalent circuits to model the physicoelectric characteristics of the electrode/biofilm/solution interface. The results showed that neither anodization nor chemical modification could decrease the bacterial adhesion and corrosion rate individually. V. natriegens showed only weak attachment to the super-hydrophobic surface, and the biocorrosion mechanism was closely associated with surface energy and surface topography.

  10. Carbohydrate-Based Host-Guest Complexation of Hydrophobic Antibiotics for the Enhancement of Antibacterial Activity.

    Science.gov (United States)

    Jeong, Daham; Joo, Sang-Woo; Shinde, Vijay Vilas; Cho, Eunae; Jung, Seunho

    2017-08-08

    Host-guest complexation with various hydrophobic drugs has been used to enhance the solubility, permeability, and stability of guest drugs. Physical changes in hydrophobic drugs by complexation have been related to corresponding increases in the bioavailability of these drugs. Carbohydrates, including various derivatives of cyclodextrins, cyclosophoraoses, and some linear oligosaccharides, are generally used as host complexation agents in drug delivery systems. Many antibiotics with low bioavailability have some limitations to their clinical use due to their intrinsically poor aqueous solubility. Bioavailability enhancement is therefore an important step to achieve the desired concentration of antibiotics in the treatment of bacterial infections. Antibiotics encapsulated in a complexation-based drug delivery system will display improved antibacterial activity making it possible to reduce dosages and overcome the serious global problem of antibiotic resistance. Here, we review the present research trends in carbohydrate-based host-guest complexation of various hydrophobic antibiotics as an efficient delivery system to improve solubility, permeability, stability, and controlled release.

  11. Standard Test Method for Hydrophobic Surface Films by the Atomizer Test

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1965-01-01

    1.1 This test method covers the detection of the presence of hydrophobic (nonwetting) films on surfaces and the presence of hydrophobic organic materials in processing ambients. When properly conducted, the test will enable detection of fractional molecular layers of hydrophobic organic contaminants. On very rough or porous surfaces the sensitivity of the test may be significantly decreased. 1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  12. The hydrophobic and omnidirectional antireflection coating of SiO2 nanospheres with C18-TEOS

    Science.gov (United States)

    Hsu, Cheng-Chih; Lan, Wen-Lin; Chen, Nien-Po; Wu, Chyan-Chyi

    2014-06-01

    This paper demonstrates the antireflection coating of SiO2 nanospheres applied to cover glass by using the optimal spin-coating method. Because of the hydrolysis and condensation reactions between the SiO2 nanosphere antireflection (AR) coating and n-octadecyltriethoxysilane solution (C18-TEOS), the contact angle of the AR coating with hydrophobic treatment is improved approximately 38%, and the moisture-resistance remains unchanged, which preserved similar transmittance for six weeks. Furthermore, the AR coating with hydrophobic treatment exhibits approximately 3% and 7% improvement in the transmittance at normal and oblique incidence, respectively. The hydrophobic and omnidirectional AR coating with nanoscale SiO2 particles can be fabricated using the proposed simple and economical method.

  13. Hydrophobization by Means of Nanotechnology on Greek Sandstones Used as Building Facades

    Directory of Open Access Journals (Sweden)

    Georgios Karagiannis

    2013-01-01

    Full Text Available Modern sustainable architecture indicates the use of local natural stones for building. Greek sandstones from Epirus (Demati, Greece, EN 12440 used as building facades meet aesthetic and have high mechanical properties, but the inevitable interaction between stone materials and natural or anthropogenic weathering factors controls the type, and extent of stone damages. In the present paper, samples of sandstone were treated with a conventional hydrophobic product and four solutions of the same product, enriched with nanosilica of different concentrations. The properties of the treated samples, such as porosity and pore size distribution, microstructure, static contact angle of a water droplet, and durability to deterioration cycles (freeze-thaw were recorded and conclusions were drawn. The research indicates the increased hydrophobic properties in nanosilica solutions but also the optimum content in nanoparticles that provides hydrophobicity without altering the properties of the stone.

  14. Plasma jet array treatment to improve the hydrophobicity of contaminated HTV silicone rubber

    Science.gov (United States)

    Zhang, Ruobing; Han, Qianting; Xia, Yan; Li, Shuang

    2017-10-01

    An atmospheric-pressure plasma jet array specially designed for HTV silicone rubber treatment is reported in this paper. Stable plasma containing highly energetic active particles was uniformly generated in the plasma jet array. The discharge pattern was affected by the applied voltage. The divergence phenomenon was observed at low gas flow rate and abated when the flow rate increased. Temperature of the plasma plume is close to room temperature which makes it feasible for temperature-sensitive material treatment. Hydrophobicity of contaminated HTV silicone rubber was significantly improved after quick exposure of the plasma jet array, and the effective treatment area reached 120 mm × 50 mm (length × width). Reactive particles in the plasma accelerate accumulation of the hydrophobic molecules, namely low molecular weight silicone chains, on the contaminated surface, which result in a hydrophobicity improvement of the HTV silicone rubber.

  15. Standard Test Method for Hydrophobic Surface Films by the Water-Break Test

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2002-01-01

    1.1 This test method covers the detection of the presence of hydrophobic (nonwetting) films on surfaces and the presence of hydrophobic organic materials in processing ambients. When properly conducted, the test will enable detection of molecular layers of hydrophobic organic contaminants. On very rough or porous surfaces, the sensitivity of the test may be significantly decreased. 1.2 The values stated in SI units are to be regarded as the standard. The inch-pound values given in parentheses are for information only. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  16. Investigation of Fatty Acid Ketohydrazone Modified Liposome’s Properties as a Drug Carrier

    Directory of Open Access Journals (Sweden)

    Keita Hayashi

    2015-01-01

    Full Text Available pH-responsive liposomes were prepared by modifying the liposome with acid-cleaving amphiphiles. Palmitic ketohydrazone (P-KH or stearic ketohydrazone (S-KH, composed of hydrophilic sugar headgroup and hydrophobic acyl chain, was used as a modifier of the DMPC liposome. Because the ketohydrazone group of P-KH or S-KH was cleaved at low pH conditions (modified liposomes was observed probably via an endocytic pathway. The membrane properties of these liposomes were characterized, focusing on the variation of both polarity (measured by Laurdan and membrane fluidity (measured by DPH at low pH condition. The interface of the P-KH modified liposome at acidic pH was found to become more hydrophobic and less fluidic as compared with that at neutral pH; that is, P-KH modified liposome became more rigid structure. Therefore, it seems that the P-KH modified liposome could protect encapsulated drugs from the enzymes in the lysosome. This study shows the novel approach about design of pH-responsive liposomes based on the membrane properties.

  17. Mesoporous fluorocarbon-modified silica aerogel membranes enabling long-term continuous CO2 capture with large absorption flux enhancements.

    Science.gov (United States)

    Lin, Yi-Feng; Chen, Chien-Hua; Tung, Kuo-Lun; Wei, Te-Yu; Lu, Shih-Yuan; Chang, Kai-Shiun

    2013-03-01

    The use of a membrane contactor combined with a hydrophobic porous membrane and an amine absorbent has attracted considerable attention for the capture of CO2 because of its extensive use, low operational costs, and low energy consumption. The hydrophobic porous membrane interface prevents the passage of the amine absorbent but allows the penetration of CO2 molecules that are captured by the amine absorbent. Herein, highly porous SiO2 aerogels modified with hydrophobic fluorocarbon functional groups (CF3 ) were successfully coated onto a macroporous Al2 O3 membrane; their performance in a membrane contactor for CO2 absorption is discussed. The SiO2 aerogel membrane modified with CF3 functional groups exhibits the highest CO2 absorption flux and can be continuously operated for CO2 absorption for extended periods of time. This study suggests that a SiO2 aerogel membrane modified with CF3 functional groups could potentially be used in a membrane contactor for CO2 absorption. Also, the resulting hydrophobic SiO2 aerogel membrane contactor is a promising technology for large-scale CO2 absorption during the post-combustion process in power plants. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. A Density Functional Theory Evaluation of Hydrophobic Solvation: Ne, Ar and Kr in a 50-Water Cluster. Implications for the Hydrophobic Effect.

    Science.gov (United States)

    Kobko, Nadya; Marianski, Mateusz; Asensio, Amparo; Wieczorek, Robert; Dannenberg, J J

    2012-06-15

    The physical explanation for the hydrophobic effect has been the subject of disagreement. Physical organic chemists tend to use a explanation related to pressure, while many biochemists prefer an explanation that involves decreased entropy of the aqueous solvent. We present DFT calculations at the B3LYP/6-31G(d,p) and X3LYP/6-31G(d,p) levels on the solvation of three noble gases (Ne, Ar, and Kr) in clusters of 50 waters. Vibrational analyses show no substantial decreases in the vibrational entropies of the waters in any of the three clusters. The observed positive free energies of transfer from the gas phase or from nonpolar solvents to water appear to be due to the work needed to make a suitable hole in the aqueous solvent. We distinguish between hydrophobic solvations (explicitly studied here) and the hydrophobic effect that occurs when a solute (or transition state) can decrease its volume through conformational change (which is not possible for the noble gases).

  19. Surface hydrophobicity of Aspergillus nidulans conidiospores and its role in pellet formation

    DEFF Research Database (Denmark)

    Dynesen, Jens Østergaard; Nielsen, Jens

    2003-01-01

    Formation of pellets by Aspergillus nidulans is primarily due to agglomeration of the fungal conidiospores. Although agglomeration of conidiospores has been known for a long time, its mechanism has not been clearly elucidated. To study the influence of the fungal conidiospore wall hydrophobicity...... on conidiospore agglomeration, pellet formation of an A. nidulans wild type and strains deleted in the conidiospore-wall-associated hydrophobins DewA and RodA was compared at different pH values. From contact angle measurements, RodA was found to be more important for the surface hydrophobicity than Dew...

  20. Preparation of durable hydrophobic cellulose fabric from water glass and mixed organosilanes

    Science.gov (United States)

    Shang, Song-Min; Li, Zhengxiong; Xing, Yanjun; Xin, John H.; Tao, Xiao-Ming

    2010-12-01

    Durable superhydrophobic cellulose fabric was prepared from water glass and n-octadecyltriethoxysilane (ODTES) with 3-glycidyloxypropyltrimethoxysilane (GPTMS) as crosslinker by sol-gel method. The result showed that the addition of GPTMS could result in a better fixation of silica coating from water glass on cellulose fabric. The silanization of hydrolyzed ODTES at different temperatures and times was studied and optimized. The results showed that silanization time was more important than temperature in forming durable hydrophobic surface. The durability of superhydrophobicity treatment was analyzed by XPS. As a result, the superhydrophobic cotton treated under the optimal condition still remained hydrophobic properties after 50 washing cycles.

  1. Ion Transfer Voltammetry Associated with Two Polarizable Interfaces Within Water and Moderately Hydrophobic Ionic Liquid Systems

    DEFF Research Database (Denmark)

    Gan, Shiyu; Zhou, Min; Zhang, Jingdong

    2013-01-01

    An electrochemical system composed of two polarizable interfaces (the metallic electrode|water and water|ionic liquid interfaces), namely two‐polarized‐interface (TPI) technique, has been proposed to explore the ion transfer processes between water and moderately hydrophobic ionic liquids (W...... to an extremely narrow polarized potential window (ppw) caused by these moderately hydrophobic ionic components. In this article, we show that TPI technique has virtually eliminated the ppw limitation based on a controlling step of concentration polarization at the electrode|water interface. With the aid...

  2. Hydrophobic Interaction Chromatography for Bottom-Up Proteomics Analysis of Single Proteins and Protein Complexes.

    Science.gov (United States)

    Rackiewicz, Michal; Große-Hovest, Ludger; Alpert, Andrew J; Zarei, Mostafa; Dengjel, Jörn

    2017-06-02

    Hydrophobic interaction chromatography (HIC) is a robust standard analytical method to purify proteins while preserving their biological activity. It is widely used to study post-translational modifications of proteins and drug-protein interactions. In the current manuscript we employed HIC to separate proteins, followed by bottom-up LC-MS/MS experiments. We used this approach to fractionate antibody species followed by comprehensive peptide mapping as well as to study protein complexes in human cells. HIC-reversed-phase chromatography (RPC)-mass spectrometry (MS) is a powerful alternative to fractionate proteins for bottom-up proteomics experiments making use of their distinct hydrophobic properties.

  3. Hydrophobic catalyst applications in the nuclear field and in environmental studies

    International Nuclear Information System (INIS)

    Ionita, Gheorghe; Popescu, Irina; Stefanescu, Ioan; Varlam, Carmen

    2002-01-01

    The paper presents methods of preparation and applications of hydrophobic platinum catalysts in nuclear field and environmental protection. These catalysts allow the transport of gaseous reactants and reaction products to and from catalytic active centers since the pore blocking by water is avoided. Hence the activity and stability of the catalysts increase and isotopic exchange columns with simpler internal structure can be achieved. The aim of the paper is: 1. to give a data base regarding the preparation methods of the optimal catalyst type; 2. to indicate the utilization and operation procedures of hydrophobic catalysts with mixed and simple packings; 3. to evaluate the performances and applications of hydrophobic catalysts. Over one hundred of hydrophobic catalysts of the active metal/support type were prepared in our laboratory. Hydrophobic features were obtained by different methods like these: - coating a hydrophilic conventional catalyst with a hydrophobic agent such as silicone or teflon; - supporting the active metal directly into the pores of a hydrophobic support; - mixing the teflon powder with a hydrophilic conventional catalyst; coating the support with teflon followed by the impregnation with the precursor of the active metal. The most important application of these catalysts is detritiation of the heavy water used as moderator and coolant in CANDU type reactors. Build-up of tritium in heavy water following the neutron capture by deuterium leads to a reduction in the moderating properties and at the same time leads to a contamination hazard for both operation personnel and environment. Tritium recovery leads this way to both improving the moderating qualities of the heavy water and obtaining valuable pure tritium of high importance in fusion research and other laboratory studies. One gram of tritium costs about USD 10,000. The physical chemical process is water-hydrogen catalyzed isotopic exchange. Also discussed in the paper is the separation of

  4. Intra-chain organisation of hydrophobic residues controls inter-chain aggregation rates of amphiphilic polymers

    Science.gov (United States)

    Varilly, Patrick; Willard, Adam P.; Kirkegaard, Julius B.; Knowles, Tuomas P. J.; Chandler, David

    2017-04-01

    Aggregation of amphiphiles through the action of hydrophobic interactions is a common feature in soft condensed matter systems and is of particular importance in the context of biophysics as it underlies both the generation of functional biological machinery as well as the formation of pathological misassembled states of proteins. Here we explore the aggregation behaviour of amphiphilic polymers using lattice Monte Carlo calculations and show that the distribution of hydrophobic residues within the polymer sequence determines the facility with which dry/wet interfaces can be created and that such interfaces drive the aggregation process.

  5. Effect of water content on the water repellency for hydrophobized sands

    Science.gov (United States)

    Subedi, S.; Kawamoto, K.; Kuroda, T.; Moldrup, P.; Komatsu, T.

    2011-12-01

    Alternative earthen covers such as capillary barriers (CBs) and evapotranspirative covers are recognized as useful technical and low-cost solutions for limiting water infiltration and controlling seepage flow at solid waste landfills in semi-arid and arid regions. However, their application to the landfills at wet regions seems to be matter of concern due to loss of their impending capability under high precipitation. One of the possible techniques to enhance the impermeable properties of CBs is to alter soil grain surfaces to be water-repellent by mixing/coating hydrophobic agents (HAs). In order to examine a potential use of model sands hydrophobized with locally available and environmental-friendly HAs such as oleic acid (OA) and stearic acid (SA) for hydrophobic CBs. In the present study, we first characterized the effect of water content on the degree of water repellency (WR) for hydrophobized sands and volcanic ash soil at different depth. Secondly, the time dependency of the contact angle in hydrophobized sands and volcanic ash soils at different water content was evaluated. Further, the effects of hydrophobic organic matter contents on the WR of hydrophobized sands were investigated by horizontal infiltration test. We investigated the degree of WR as functions of volumetric water content (θ) of a volcanic ash soil samples from different depth and water adjusted hydrophobized sand samples with different ratio of HAs by using sessile drop method (SDM). The initial contact angle (αi) measured from SDM decreased gradually with increasing water content in OA and SA coated samples. Measured αi values for volcanic ash soils increased with increasing water content and reached a peak values of 111.7o at θ= 0.325 cm3 cm-3, where-after αi gradually decreased. Each test sample exhibited sharp decrease in contact angle with time at higher water content. Sorptivity values for oleic acid coated samples decreased with increasing HA content and reached the minimum

  6. Effects of polarity, hydrophobicity, and density of ionic liquids on cellulose solubility.

    Science.gov (United States)

    Abe, Mitsuru; Kuroda, Kosuke; Sato, Daiki; Kunimura, Haruhito; Ohno, Hiroyuki

    2015-12-28

    We have synthesised novel ionic liquids (ILs) to show both cellulose dissolution ability and LCST-type phase transition after mixing with water. To realise both polar and hydrophobic properties, tetraalkylphosphonium cations and a series of carboxylate anions were employed to assume hydrophobic and highly polar properties, respectively. Effects of their alkyl chain length on the water compatibility and cellulose solubility of the corresponding ILs were systematically examined. We succeeded in synthesising novel ILs which dissolve cellulose and separable with water at moderate temperature. Through the present study, we have clarified that not only polarity but also density of ILs is an important factor in designing the ILs for cellulose dissolution.

  7. Conformation of bovine submaxillary mucin layers on hydrophobic surface as studied by biomolecular probes

    DEFF Research Database (Denmark)

    Pakkanen, Kirsi I.; Madsen, Jan Busk; Lee, Seunghwan

    2015-01-01

    In the present study, the conformational changes of bovine submaxillary mucin (BSM) adsorbed on a hydrophobic surface (polystyrene (PS)) as a function of concentration in bulk solution (up to 2mg/mL) have been investigated with biomolecular probe-based approaches, including bicinchoninic acid (BCA),enzyme-linkedimmunosorbentassay(EIA...... solution. Adsorbed masses of BSM onto hydrophobic surface, as probe by BCA, showed a continuously increasing trend up to 2mg/mL. But, the signals from EIA and ELLA, which probe the concentration of available unglycosylatedC-terminals and the central glycosylated regions, respectively, showed complicated...

  8. Hydrophobic interactions between polymethacrylic acid and sodium laureth sulfate in aqueous solutions

    Science.gov (United States)

    Yaremko, Z. M.; Fedushinskaya, L. B.; Burka, O. A.; Soltys, M. N.

    2014-09-01

    The role of hydrophobic interaction in the development of associative processes is demonstrated, based on the concentration dependences of the viscosity and pH of binary solutions of polymethacrylic acid as an anionic polyelectrolyte and sodium laureth sulfate as an anionic surfactant. It is found that the inflection point on the dependence of the difference between the pH values of binary solutions of polymethacrylic acid and sodium laureth sulfate on the polyelectrolyte concentration is a criterion for determining the predominant contribution from hydrophobic interaction, as is the inflection point on the dependence of pH of individual solutions of polymethacrylic acid on the polyelectrolyte concentration.

  9. Design and fabrication of a nanostructured surface combining antireflective and enhanced-hydrophobic effects

    International Nuclear Information System (INIS)

    Chang, Y C; Mei, G H; Chang, T W; Wang, T J; Lin, D Z; Lee, C K

    2007-01-01

    Herein, we propose a special type of periodic subwavelength structure, which is optically an effective gradient-index (GRIN) antireflective surface that also exhibits enhanced-hydrophobic behaviour. Our new concept was developed adopting both the effective medium theory (EMT) and Wenzel's wettability model. To demonstrate the concept, an inverted pyramid structure was fabricated by electron beam (EB) lithography and anisotropic etching. The experimental data was found to be in good agreement with the theoretical prediction. Some potential applications that can benefit from this combination of antireflection and enhanced-hydrophobicity features are discussed

  10. Preparation and Characterization of Fluorinated Hydrophobic UV-Crosslinkable Thiol-Ene Polyurethane Coatings

    Directory of Open Access Journals (Sweden)

    Wenjing Xia

    2017-08-01

    Full Text Available The polyurethane prepolymer terminated with a double bond was synthesized using isophorone diisocyanate (IPDI, hydroxyl terminated polybutadiene (HTPB, 1,4-butanediol (BDO, and 2-hydroxyethyl acrylate (HEA. Then, a series of innovative UV-curable polyurethane coatings were prepared by blending ene-terminated polyurethane, fluoroacrylate monomer, and multifunctional thiol crosslinker upon UV exposure. The incorporation of fluoroacrylate monomer and multifunctional thiols into polyurethane coatings significantly enhanced the hydrophobic property, mechanical property, pencil hardness, and glossiness of the polyurethane coatings. This method of preparing UV crosslinkable, hydrophobic polyurethane coatings based on thiol-ene chemistry exhibited numerous advantages over other UV photocuring systems.

  11. Exploiting hydrophobicity for efficient production of transmembrane helices for structure determination by NMR spectroscopy

    DEFF Research Database (Denmark)

    Bugge, Katrine Østergaard; Steinocher, Helena; Brooks, Andrew J.

    2015-01-01

    -labeled protein. In this work, we have exploited the hydrophobic nature of membrane proteins to develop a simple and efficient production scheme for isotope-labeled single-pass transmembrane domains (TMDs) with or without intrinsically disordered regions. We have evaluated the applicability and limitations...... of the strategy using seven membrane protein variants that differ in their overall hydrophobicity and length and show a recovery for suitable variants of >70%. The developed production scheme is cost-efficient and easy to implement and has the potential to facilitate an increase in the number of structures...

  12. Hydrophobic cotton textile surfaces using an amphiphilic graphene oxide (GO) coating

    International Nuclear Information System (INIS)

    Tissera, Nadeeka D.; Wijesena, Ruchira N.; Perera, J. Rangana; Nalin de Silva, K.M.; Amaratunge, Gehan A.J.

    2015-01-01

    Graphical abstract: - Highlights: • Different GO dispersions were prepared by sonicating different amounts of GO in water. Degree of exfoliation of these GO sheets in water was analyzed using Atomic Force Microscopy (AFM). • AFM results obtained showed higher the GO concentration on water more the size of GO sheets and lesser the degree of exfoliation. • GO with different amounts was deposited on cotton fabric using simple dyeing method. • High GO loading on cotton increase the surface area coverage of the textile fibers with GO sheets. This led to less edge to mid area ratio of grafted GO sheets. • As contribution of mid area of GO increase on fiber surface cotton fabric becomes more hydrophobic. • Amphiphilic property of GO sheets was used to lower the surface energy of the cotton fibers leading to hydrophobic property. - Abstract: We report for the first time hydrophobic properties on cotton fabric successfully achieved by grafting graphene oxide on the fabric surface, using a dyeing method. Graphite oxide synthesized by oxidizing natural flake graphite employing improved Hummer's method showed an inter layer spacing of ∼1 nm from XRD. Synthesized graphite oxide was exfoliated in water using ultrasound energy to obtain graphene oxide (GO). AFM data obtained for the graphene oxide dispersed in an aqueous medium revealed a non-uniform size distribution. FTIR characterization of the synthesized GO sheets showed both hydrophilic and hydrophobic functional groups present on the nano sheets giving them an amphiphilic property. GO flakes of different sizes were successfully grafted on to a cotton fabric surface using a dip dry method. Loading different amounts of graphene oxide on the cotton fiber surface allowed the fabric to demonstrate different degrees of hydrophobicity. The highest observed water contact angle was at 143° with the highest loading of graphene oxide. The fabric surfaces grafted with GO also exhibits adhesive type hydrophobicity

  13. Phase I Field Test Results of an Innovative DNAPL Remediation Technology: The Hydrophobic Lance

    International Nuclear Information System (INIS)

    Tuck, D.M.

    1999-01-01

    An innovative technology for recovery of pure phase DNAPL was deployed in the subsurface near the M-Area Settling Basin, continuing the support of the A/M Area Ground Water Corrective Action Program (per Part B requirements). This technology, the Hydrophobic Lance, operates by placing a neutral/hydrophobic surface (Teflon) in contact with the DNAPL. This changes the in situ conditions experienced by the DNAPL, allowing it to selectively drain into a sump from which it can be pumped. Collection of even small amounts of DNAPL can save years of pump-and-treat operation because of the generally low solubility of DNAPL components

  14. Using sewage sludge pyrolytic gas to modify titanium alloy to obtain high-performance anodes in bio-electrochemical systems

    Science.gov (United States)

    Gu, Yuan; Ying, Kang; Shen, Dongsheng; Huang, Lijie; Ying, Xianbin; Huang, Haoqian; Cheng, Kun; Chen, Jiazheng; Zhou, Yuyang; Chen, Ting; Feng, Huajun

    2017-12-01

    Titanium is under consideration as a potential stable bio-anode because of its high conductivity, suitable mechanical properties, and electrochemical inertness in the operating potential window of bio-electrochemical systems; however, its application is limited by its poor electron-transfer capacity with electroactive bacteria and weak ability to form biofilms on its hydrophobic surface. This study reports an effective and low-cost way to convert a hydrophobic titanium alloy surface into a hydrophilic surface that can be used as a bio-electrode with higher electron-transfer rates. Pyrolytic gas of sewage sludge is used to modify the titanium alloy. The current generation, anodic biofilm formation surface, and hydrophobicity are systematically investigated by comparing bare electrodes with three modified electrodes. Maximum current density (15.80 A/m2), achieved using a modified electrode, is 316-fold higher than that of the bare titanium alloy electrode (0.05 A/m2) and that achieved by titanium alloy electrodes modified by other methods (12.70 A/m2). The pyrolytic gas-modified titanium alloy electrode can be used as a high-performance and scalable bio-anode for bio-electrochemical systems because of its high electron-transfer rates, hydrophilic nature, and ability to achieve high current density.

  15. Hydrophobic, Hydrophilic, and Amphiphilic Polyglycocarbonates with Linear and Macrocyclic Architectures from Bicyclic Glycocarbonates Derived from CO2 and Glucoside

    KAUST Repository

    Pati, Debasis

    2017-02-09

    Two bicyclic glycocarbonates were synthesized in five steps from α-methyl-d-glucoside without resorting to phosgene or to its derivatives for the first time. The 4- and 6-positions of glucose were modified to introduce a six-membered carbonate ring, using CO as the carbonylating reagent; the 2- and 3-positions of the same glucoside substrate were first transformed into either methyl or triethylene glycol monomethyl ether groups to protect these positions from undesirable reactions and also to impart hydrophobicity in the first case and hydrophilicity in the second. The polymerization behavior of these bicyclic glycocarbonates was then investigated under different conditions. On the one hand, through ring-opening polymerization of the above monomers, linear polyglycocarbonate homopolymers and diblock copolymers were obtained initiated by p-methylbenzyl alcohol using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as catalyst; on the other hand, macrocyclic polyglycocarbonate homopolymers and diblock copolymers were grown using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) which served as zwitterionic initiator. The various architectures derived were all thoroughly characterized by NMR, GPC, and MALDI-tof and shown to exhibit the expected structure. Finally, the self-assembly of linear and macrocyclic amphiphilic copolyglycocarbonates in water was investigated and characterized by cryo-TEM.

  16. Hydrophobic, Hydrophilic, and Amphiphilic Polyglycocarbonates with Linear and Macrocyclic Architectures from Bicyclic Glycocarbonates Derived from CO2 and Glucoside

    KAUST Repository

    Pati, Debasis; Feng, Xiaoshuang; Hadjichristidis, Nikolaos; Gnanou, Yves

    2017-01-01

    Two bicyclic glycocarbonates were synthesized in five steps from α-methyl-d-glucoside without resorting to phosgene or to its derivatives for the first time. The 4- and 6-positions of glucose were modified to introduce a six-membered carbonate ring, using CO as the carbonylating reagent; the 2- and 3-positions of the same glucoside substrate were first transformed into either methyl or triethylene glycol monomethyl ether groups to protect these positions from undesirable reactions and also to impart hydrophobicity in the first case and hydrophilicity in the second. The polymerization behavior of these bicyclic glycocarbonates was then investigated under different conditions. On the one hand, through ring-opening polymerization of the above monomers, linear polyglycocarbonate homopolymers and diblock copolymers were obtained initiated by p-methylbenzyl alcohol using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as catalyst; on the other hand, macrocyclic polyglycocarbonate homopolymers and diblock copolymers were grown using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) which served as zwitterionic initiator. The various architectures derived were all thoroughly characterized by NMR, GPC, and MALDI-tof and shown to exhibit the expected structure. Finally, the self-assembly of linear and macrocyclic amphiphilic copolyglycocarbonates in water was investigated and characterized by cryo-TEM.

  17. Study of tetrapodal ZnO-PDMS composites: a comparison of fillers shapes in stiffness and hydrophobicity improvements.

    Directory of Open Access Journals (Sweden)

    Xin Jin

    Full Text Available ZnO particles of different size and structures were used as fillers to modify the silicone rubber, in order to reveal the effect of the filler shape in the polymer composites. Tetrapodal shaped microparticles, short microfibers/whiskers, and nanosized spherical particles from ZnO have been used as fillers to fabricate the different ZnO-Silicone composites. The detailed microstructures of the fillers as well as synthesized composites using scanning electron microscopy have been presented here. The tensile elastic modulus and water contact angle, which are important parameters for bio-mimetic applications, of fabricated composites with different fillers have been measured and compared. Among all three types of fillers, tetrapodal shaped ZnO microparticles showed the best performance in terms of increase in hydrophobicity of material cross-section as well as the stiffness of the composites. It has been demonstrated that the tetrapodal shaped microparticles gain their advantage due to the special shape, which avoids agglomeration problems as in the case for nanoparticles, and the difficulty of achieving truly random distribution for whisker fillers.

  18. Study of tetrapodal ZnO-PDMS composites: a comparison of fillers shapes in stiffness and hydrophobicity improvements.

    Science.gov (United States)

    Jin, Xin; Deng, Mao; Kaps, Sören; Zhu, Xinwei; Hölken, Iris; Mess, Kristin; Adelung, Rainer; Mishra, Yogendra Kumar

    2014-01-01

    ZnO particles of different size and structures were used as fillers to modify the silicone rubber, in order to reveal the effect of the filler shape in the polymer composites. Tetrapodal shaped microparticles, short microfibers/whiskers, and nanosized spherical particles from ZnO have been used as fillers to fabricate the different ZnO-Silicone composites. The detailed microstructures of the fillers as well as synthesized composites using scanning electron microscopy have been presented here. The tensile elastic modulus and water contact angle, which are important parameters for bio-mimetic applications, of fabricated composites with different fillers have been measured and compared. Among all three types of fillers, tetrapodal shaped ZnO microparticles showed the best performance in terms of increase in hydrophobicity of material cross-section as well as the stiffness of the composites. It has been demonstrated that the tetrapodal shaped microparticles gain their advantage due to the special shape, which avoids agglomeration problems as in the case for nanoparticles, and the difficulty of achieving truly random distribution for whisker fillers.

  19. Modification of a hydrophobic layer by a point mutation in syntaxin 1A regulates the rate of synaptic vesicle fusion.

    Directory of Open Access Journals (Sweden)

    Robert D Lagow

    2007-04-01

    Full Text Available Both constitutive secretion and Ca(2+-regulated exocytosis require the assembly of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE complexes. At present, little is known about how the SNARE complexes mediating these two distinct pathways differ in structure. Using the Drosophila neuromuscular synapse as a model, we show that a mutation modifying a hydrophobic layer in syntaxin 1A regulates the rate of vesicle fusion. Syntaxin 1A molecules share a highly conserved threonine in the C-terminal +7 layer near the transmembrane domain. Mutation of this threonine to isoleucine results in a structural change that more closely resembles those found in syntaxins ascribed to the constitutive secretory pathway. Flies carrying the I254 mutant protein have increased levels of SNARE complexes and dramatically enhanced rate of both constitutive and evoked vesicle fusion. In contrast, overexpression of the T254 wild-type protein in neurons reduces vesicle fusion only in the I254 mutant background. These results are consistent with molecular dynamics simulations of the SNARE core complex, suggesting that T254 serves as an internal brake to dampen SNARE zippering and impede vesicle fusion, whereas I254 favors fusion by enhancing intermolecular interaction within the SNARE core complex.

  20. Synthesis of Environmentally Responsive Polymers by Atom Transfer Radical Polymerization: Generation of Reversible Hydrophilic and Hydrophobic Surfaces

    Directory of Open Access Journals (Sweden)

    Vikas Mittal

    2010-05-01

    Full Text Available Environmentally responsive poly(N-isopropylacrylamide brushes were grafted from the surface of polymer particles or flat surfaces in order to generate reversible hydrophilic and hydrophobic surfaces. The use of atom transfer radical polymerization was demonstrated for the grafting of polymer brushes as it allows efficient control on the amount of grafted polymer. The polymer particles were generated with or without surfactant in the emulsion polymerization and their surface could be modified with the atom transfer radical polymerization (ATRP initiator. The uniform functionalization of the surface with ATRP initiator was responsible for the uniform grafting of polymer brushes. The grafted brushes responded reversibly with changes in temperature indicating that the reversible responsive behavior could be translated to the particle surfaces. The particles were observed to adsorb and desorb protein and virus molecules by changing the temperatures below or higher than 32 °C. The initiator functionalized particles could also be adsorbed on the flat surfaces. The adsorption process also required optimization of the heat treatment conditions to form a uniform layer of the particles on the substrate. The grafted polymer brushes also responded to the changes in temperatures similar to the spherical particles studied through water droplets placed on the flat substrates.

  1. Reduction of Urinary Tract Infections Caused By Urethral Catheter through the Implementation of Hydrophobic Coating and Geometrical Modifications

    Science.gov (United States)

    Gare, Aya

    2013-11-01

    Catheter-Associated Urinary Tract Infection (CAUTI) is the most common nosocomial infection in the U.S. healthcare system. The obstruction of urine caused by confined air bubbles result in the development of urinary back-flow and stagnation, wherein microbial pathogens could multiply rapidly and colonization within catheters become commonplace. Infections can be prevented by aseptic insertion and the maintenance of a closed drainage system, keeping high infection control standards, and preventing back-flow from the catheter bag. The goal of this study is to assess the effectiveness of a simple, low cost, modification that may be implemented into current catheter designs to reduce the incidence of CAUTI. Using the principle of transmission of fluid-pressure and the Young-Laplace equation for capillary pressure difference, this research focuses on improving the liquid flow in the presence of confined bubbles to prevent stagnation and reflux of bacteria-ridden urine into the body. Preliminary experiments are performed on a variety of tubes with hydrophobic-coating the interior, as well as geometrically modifying the tubes. Proof-of-Concept Prototype tubes are used to represent the drainage system of the catheter structure.

  2. Modified Nance palatal button

    Directory of Open Access Journals (Sweden)

    Nitin Arora

    2015-01-01

    Full Text Available This paper describes modified Nance palatal button by which problems encountered in the palatal region around the acrylic button during space closure and molar distalization can be minimized.

  3. Modified microdissection electrocautery needle

    OpenAIRE

    Singh, Virendra; Kumar, Pramod

    2014-01-01

    Electrocautery is routinely used in surgical procedures. The commercially available microdissection electrocautery needles are costly. To overcome this disadvantage, we have modified monopolar electrocautery tip to function as well as commercially available systems.

  4. Biological response modifiers

    Energy Technology Data Exchange (ETDEWEB)

    Weller, R.E.

    1991-10-01

    Much of what used to be called immunotherapy is now included in the term biological response modifiers. Biological response modifiers (BRMs) are defined as those agents or approaches that modify the relationship between the tumor and host by modifying the host's biological response to tumor cells with resultant therapeutic effects.'' Most of the early work with BRMs centered around observations of spontaneous tumor regression and the association of tumor regression with concurrent bacterial infections. The BRM can modify the host response in the following ways: Increase the host's antitumor responses through augmentation and/or restoration of effector mechanisms or mediators of the host's defense or decrease the deleterious component by the host's reaction; Increase the host's defenses by the administration of natural biologics (or the synthetic derivatives thereof) as effectors or mediators of an antitumor response; Augment the host's response to modified tumor cells or vaccines, which might stimulate a greater response by the host or increase tumor-cell sensitivity to an existing response; Decrease the transformation and/or increase differentiation (maturation) of tumor cells; or Increase the ability of the host to tolerate damage by cytotoxic modalities of cancer treatment.

  5. Optimal Hydrophobicity in Ring-Opening Metathesis Polymerization-Based Protein Mimics Required for siRNA Internalization.

    Science.gov (United States)

    deRonde, Brittany M; Posey, Nicholas D; Otter, Ronja; Caffrey, Leah M; Minter, Lisa M; Tew, Gregory N

    2016-06-13

    Exploring the role of polymer structure for the internalization of biologically relevant cargo, specifically siRNA, is of critical importance to the development of improved delivery reagents. Herein, we report guanidinium-rich protein transduction domain mimics (PTDMs) based on a ring-opening metathesis polymerization scaffold containing tunable hydrophobic moieties that promote siRNA internalization. Structure-activity relationships using Jurkat T cells and HeLa cells were explored to determine how the length of the hydrophobic block and the hydrophobic side chain compositions of these PTDMs impacted siRNA internalization. To explore the hydrophobic block length, two different series of diblock copolymers were synthesized: one series with symmetric block lengths and one with asymmetric block lengths. At similar cationic block lengths, asymmetric and symmetric PTDMs promoted siRNA internalization in the same percentages of the cell population regardless of the hydrophobic block length; however, with 20 repeat units of cationic charge, the asymmetric block length had greater siRNA internalization, highlighting the nontrivial relationships between hydrophobicity and overall cationic charge. To further probe how the hydrophobic side chains impacted siRNA internalization, an additional series of asymmetric PTDMs was synthesized that featured a fixed hydrophobic block length of five repeat units that contained either dimethyl (dMe), methyl phenyl (MePh), or diphenyl (dPh) side chains and varied cationic block lengths. This series was further expanded to incorporate hydrophobic blocks consisting of diethyl (dEt), diisobutyl (diBu), and dicyclohexyl (dCy) based repeat units to better define the hydrophobic window for which our PTDMs had optimal activity. High-performance liquid chromatography retention times quantified the relative hydrophobicities of the noncationic building blocks. PTDMs containing the MePh, diBu, and dPh hydrophobic blocks were shown to have superior

  6. Adsorption of hydrophobin on different self-assembled monolayers: the role of the hydrophobic dipole and the electric dipole.

    Science.gov (United States)

    Peng, Chunwang; Liu, Jie; Zhao, Daohui; Zhou, Jian

    2014-09-30

    In this work, the adsorptions of hydrophobin (HFBI) on four different self-assembled monolayers (SAMs) (i.e., CH3-SAM, OH-SAM, COOH-SAM, and NH2-SAM) were investigated by parallel tempering Monte Carlo and molecular dynamics simulations. Simulation results indicate that the orientation of HFBI adsorbed on neutral surfaces is dominated by a hydrophobic dipole. HFBI adsorbs on the hydrophobic CH3-SAM through its hydrophobic patch and adopts a nearly vertical hydrophobic dipole relative to the surface, while it is nearly horizontal when adsorbed on the hydrophilic OH-SAM. For charged SAM surfaces, HFBI adopts a nearly vertical electric dipole relative to the surface. HFBI has the narrowest orientation distribution on the CH3-SAM, and thus can form an ordered monolayer and reverse the wettability of the surface. For HFBI adsorption on charged SAMs, the adsorption strength weakens as the surface charge density increases. Compared with those on other SAMs, a larger area of the hydrophobic patch is exposed to the solution when HFBI adsorbs on the NH2-SAM. This leads to an increase of the hydrophobicity of the surface, which is consistent with the experimental results. The binding of HFBI to the CH3-SAM is mainly through hydrophobic interactions, while it is mediated through a hydration water layer near the surface for the OH-SAM. For the charged SAM surfaces, the adsorption is mainly induced by electrostatic interactions between the charged surfaces and the oppositely charged residues. The effect of a hydrophobic dipole on protein adsorption onto hydrophobic surfaces is similar to that of an electric dipole for charged surfaces. Therefore, the hydrophobic dipole may be applied to predict the probable orientations of protein adsorbed on hydrophobic surfaces.

  7. Influence of surface modified nano silica on alkyd binder before and after accelerated weathering

    DEFF Research Database (Denmark)

    Nikolic, Miroslav; Nguyen, Hiep Dinh; Daugaard, Anders Egede

    2016-01-01

    Introduction of nano fillers in exterior wood coatings is not straight forward. Influence on aging of polymer binder needs to be taken into account along with possible benefits that nano fillers can provide immediately after application. This study shows the influence of two differently modified...... hydrophobic nano silica on an alkyd binder for exterior wood coatings. One month after application, the highest strength and energy required to break the films was obtained with addition of 3% disilazane modified silica. Changes in tensile properties were accompanied with a small increase in glass transition...

  8. Enhanced Bioactivity of α-Tocopheryl Succinate Based Block Copolymer Nanoparticles by Reduced Hydrophobicity.

    Science.gov (United States)

    Palao-Suay, Raquel; Aguilar, María Rosa; Parra-Ruiz, Francisco J; Maji, Samarendra; Hoogenboom, Richard; Rohner, Nathan A; Thomas, Susan N; Román, Julio San

    2016-12-01

    Well-structured amphiphilic copolymers are necessary to obtain self-assembled nanoparticles (NPs) based on synthetic polymers. Highly homogeneous and monodispersed macromolecules obtained by controlled polymerization have successfully been used for this purpose. However, disaggregation of the organized macromolecules is desired when a bioactive element, such as α-tocopheryl succinate, is introduced in self-assembled NPs and this element must be exposed or released to exert its action. The aim of this work is to demonstrate that the bioactivity of synthetic NPs based on defined reversible addition-fragmentation chain transfer polymerization copolymers can be enhanced by the introduction of hydrophilic comonomers in the hydrophobic segment. The amphiphilic terpolymers are based on poly(ethylene glycol) (PEG) as hydrophilic block, and a hydrophobic block based on a methacrylic derivative of α-tocopheryl succinate (MTOS) and small amounts of 2-hydroxyethyl methacrylate (HEMA) (PEG-b-poly(MTOS-co-HEMA)). The introduction of HEMA reduces hydrophobicity and introduces "disorder" both in the homogeneous blocks and the compact core of the corresponding NPs. These NPs are able to encapsulate additional α-tocopheryl succinate (α-TOS) with high efficiency and their biological activity is much higher than that described for the unmodified copolymers, proposedly due to more efficient degradation and release of α-TOS, demonstrating the importance of the hydrophilic-hydrophobic balance. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Comparison of the Fouling Release Properties of Hydrophobic Fluorinated and Hydrophilic PEGylated Block Copolymer Surfaces

    International Nuclear Information System (INIS)

    Krishnan, S.; Wang, N.; Ober, C.; Finlay, J.; Callow, M.; Callow, J.; Hexemer, A.; Sohn, K.; Kramer, E.; Fischer, D.

    2006-01-01

    To understand the role of surface wettability in adhesion of cells, the attachment of two different marine algae was studied on hydrophobic and hydrophilic polymer surfaces. Adhesion of cells of the diatom Navicula and sporelings (young plants) of the green macroalga Ulva to an underwater surface is mainly by interactions between the surface and the adhesive exopolymers, which the cells secrete upon settlement and during subsequent colonization and growth. Two types of block copolymers, one with poly(ethylene glycol) side-chains and the other with liquid crystalline, fluorinated side-chains, were used to prepare the hydrophilic and hydrophobic surfaces, respectively. The formation of a liquid crystalline smectic phase in the latter inhibited molecular reorganization at the surface, which is generally an issue when a highly hydrophobic surface is in contact with water. The adhesion strength was assessed by the fraction of settled cells (Navicula) or biomass (Ulva) that detached from the surface in a water flow channel with a wall shear stress of 53 Pa. The two species exhibited opposite adhesion behavior on the same sets of surfaces. While Navicula cells released more easily from hydrophilic surfaces, Ulva sporelings showed higher removal from hydrophobic surfaces. This highlights the importance of differences in cell-surface interactions in determining the strength of adhesion of cells to substrates

  10. Modeling of Hydrophobic Surfaces by the Stokes Problem With the Stick–Slip Boundary Conditions

    Czech Academy of Sciences Publication Activity Database

    Kučera, R.; Šátek, V.; Haslinger, Jaroslav; Fialová, S.; Pochylý, F.

    2017-01-01

    Roč. 139, č. 1 (2017), č. článku 011202. ISSN 0098-2202 Institutional support: RVO:68145535 Keywords : algebra * boundary conditions * hydrophobicity * Lagrange multipliers * Navier Stokes equations Subject RIV: BA - General Mathematics OBOR OECD: Applied mathematics Impact factor: 1.437, year: 2016 http://fluidsengineering.asmedigitalcollection.asme.org/article.aspx?articleid=2536532

  11. Synthesis of hydrophobic zeolite X-SiO{sub 2} core-shell composites

    Energy Technology Data Exchange (ETDEWEB)

    Liu Liying [School of Material and Metallurgy, Northeastern University, Shenyang, Liaoning 110004 (China); Cooperative Research Centre for Greenhouse Gas Technologies (CO-2CRC) (Australia); Singh, Ranjeet; Li Gang; Xiao Gongkui [Cooperative Research Centre for Greenhouse Gas Technologies (CO-2CRC) (Australia); Department of Chemical Engineering, Monash University, Clayton, Victoria 3800 (Australia); Webley, Paul A., E-mail: paul.webley@eng.monash.edu.au [Cooperative Research Centre for Greenhouse Gas Technologies (CO-2CRC) (Australia); Department of Chemical and Biomolecular Engineering, University of Melbourne, Victoria 3010 (Australia); Zhai Yuchun [School of Material and Metallurgy, Northeastern University, Shenyang, Liaoning 110004 (China)

    2012-04-16

    Highlights: Black-Right-Pointing-Pointer Hydrophobic 13X zeolite composites with silicalite and mesoporous silica shells are designed. Black-Right-Pointing-Pointer These core-shell composites are silynated and their hydrophobicity is tested. Black-Right-Pointing-Pointer Addition of silica layer increases the density of surface hydroxyl groups which makes the improvement of the hydrophobicity possible by further silynation. - Abstract: Core-shell structures of zeolite X coated with silicalite as well as mesoporous (MCM-41) have been synthesized. Furthermore, the surfaces of the silicalite and mesoporous silica shells were silylated using organosilanes. The materials were characterized by X-ray diffraction, nitrogen adsorption/desorption, scanning and transmission electron microscopy. The results show that the properties of zeolite 13X-silicalite and zeolite 13X-mesoporous silica core-shells composite structures are well maintained even after the modification. As expected, the shell thickness increased with increase in synthesis time, however, the micropore volume decreased. Silylation with smaller organosilanes (trimethyl chlorosilane) resulted in decrease in surface area as they diffused through the pores; however, bulkier silane reacted with surface hydroxyl groups and maintained the pore structure. Contact angle measurements revealed that hydrophobicity of zeolite 13X was enhanced by the microporous and mesoporous shell coating and was further improved by silylation.

  12. Topology and cellular localization of the small hydrophobic protein of avian metapneumovirus

    Science.gov (United States)

    The small hydrophobic protein (SH) is a type II integral membrane protein that is packaged into virions and is only present in certain paramyxoviruses including metapneumovirus. In addition to a highly divergent primary sequence, SH proteins vary significantly in size among the different viruses. Hu...

  13. In situ sorption of hydrophobic organic compounds to sediment amended with activated carbon

    NARCIS (Netherlands)

    Kupryianchyk, D.; Rakowska, M.I.; Grotenhuis, J.T.C.; Koelmans, A.A.

    2012-01-01

    Contaminated sediments can be remediated by adding carbonaceous materials (CM), e.g. activated carbons (AC). Here, we analyze published datasets from AC amendment trials to identify variation in the effectiveness of AC in reducing porewater concentrations of hydrophobic organic contaminants (HOCs).

  14. PC-SAFT modeling of CO2 solubilities in hydrophobic deep eutectic solvents

    NARCIS (Netherlands)

    Dietz, C.H.J.T.; van Osch, D.J.G.P.; Kroon, M.C.; Sadowski, G.; van Sint Annaland, M.; Gallucci, F.; Zubeir, L.F.; Held, C.

    2017-01-01

    The PC-SAFT 'pseudo-pure' approach was used for the modeling of CO2 solubilities in various hydrophobic deep eutectic solvents (DESs) for the first time. Only liquid density data were used to obtain the segment number, the temperature-independent segment diameter and the dispersion-energy parameter,

  15. Hydrophobic Drug-Loaded PEGylated Magnetic Liposomes for Drug-Controlled Release

    Science.gov (United States)

    Hardiansyah, Andri; Yang, Ming-Chien; Liu, Ting-Yu; Kuo, Chih-Yu; Huang, Li-Ying; Chan, Tzu-Yi

    2017-05-01

    Less targeted and limited solubility of hydrophobic-based drug are one of the serious obstacles in drug delivery system. Thus, new strategies to enhance the solubility of hydrophobic drug and controlled release behaviors would be developed. Herein, curcumin, a model of hydrophobic drug, has been loaded into PEGylated magnetic liposomes as a drug carrier platform for drug controlled release system. Inductive magnetic heating (hyperthermia)-stimulated drug release, in vitro cellular cytotoxicity assay of curcumin-loaded PEGylated magnetic liposomes and cellular internalization-induced by magnetic guidance would be investigated. The resultant of drug carriers could disperse homogeneously in aqueous solution, showing a superparamagnetic characteristic and could inductive magnetic heating with external high-frequency magnetic field (HFMF). In vitro curcumin release studies confirmed that the drug carriers exhibited no significant release at 37 °C, whereas exhibited rapid releasing at 45 °C. However, it would display enormous (three times higher) curcumin releasing under the HFMF exposure, compared with that without HFMF exposure at 45 °C. In vitro cytotoxicity test shows that curcumin-loaded PEGylated magnetic liposomes could efficiently kill MCF-7 cells in parallel with increasing curcumin concentration. Fluorescence microscopy observed that these drug carriers could internalize efficiently into the cellular compartment of MCF-7 cells. Thus, it would be anticipated that the novel hydrophobic drug-loaded PEGylated magnetic liposomes in combination with inductive magnetic heating are promising to apply in the combination of chemotherapy and thermotherapy for cancer therapy.

  16. Fabrication of hydrophobic surface with hierarchical structure on Mg alloy and its corrosion resistance

    International Nuclear Information System (INIS)

    Wang Jun; Li Dandan; Liu Qi; Yin Xi; Zhang Ying; Jing Xiaoyan; Zhang Milin

    2010-01-01

    A hydrotalcite/hydromagnesite conversion coating with hierarchical structure has been fabricated on a Mg alloy substrate by in situ hydrothermal crystallization method. A MgO layer existing between the hydrotalcite/hydromagnesite film and the substrate was formed prior to the hydrotalcite/hydromagnesite film during the crystallization process. After surface treatment with silane coupling agent, the surface of conversion coating changes from hydrophilic to hydrophobic. Scanning electron microscopy (SEM) revealed that the silylated conversion coating with hierarchical structure maintains the original rough surface of which was composed of numerous micro-scale flakes and beautiful flower-like protrusions. Polarization measurements have shown that the hydrophobic conversion coating exhibited a low corrosion current density value of 0.432 μA/cm 2 , which means that the hydrophobic conversion coating can effectively protect Mg alloy from corrosion. Electrochemical impedance spectroscopy (EIS) showed that the impedance of the hydrophobic conversion coating was 9000 Ω. It means that the coating served as a passive layer with high charge transfer resistance.

  17. BRACHIAL EFFLUX OF HYDROPHOBIC ORGANIC COMPOUNDS BY RAINBOW TROUT (ONCORHYNCHUS MYKISS)

    Science.gov (United States)

    Data on the branchial elimination of hydrophobic compounds has been suggested as key information in the development of PBTK models for fish. The hypothesis is that branchial efflux of high log Kow compounds proceeds to an equilibrium between the afferent blood and expired water. ...

  18. BRANCHIAL EFFLUX OF HYDROPHOBIC ORGANIC COMPOUNDS BY RAINBOW TROUT (ONCORHYNCHUS MYKISS)

    Science.gov (United States)

    Development of PBTK models for fish has been impededd by a lack of data on the branchial elimination of hydrophobic compounds. The hypothesis is that branchial efflux of high log Kow compounds proceeds to an equilibrium between the afferent blood and expired water. Branchial effl...

  19. Water around fullerene shape amphiphiles: A molecular dynamics simulation study of hydrophobic hydration

    Energy Technology Data Exchange (ETDEWEB)

    Varanasi, S. R., E-mail: s.raovaranasi@uq.edu.au, E-mail: guskova@ipfdd.de; John, A. [Institut Theorie der Polymere, Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden D-01069 (Germany); Guskova, O. A., E-mail: s.raovaranasi@uq.edu.au, E-mail: guskova@ipfdd.de [Institut Theorie der Polymere, Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden D-01069 (Germany); Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden D-01069 (Germany); Sommer, J.-U. [Institut Theorie der Polymere, Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden D-01069 (Germany); Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden D-01069 (Germany); Institut für Theoretische Physik, Technische Universität Dresden, Zellescher Weg 17, Dresden D-01069 (Germany)

    2015-06-14

    Fullerene C{sub 60} sub-colloidal particle with diameter ∼1 nm represents a boundary case between small and large hydrophobic solutes on the length scale of hydrophobic hydration. In the present paper, a molecular dynamics simulation is performed to investigate this complex phenomenon for bare C{sub 60} fullerene and its amphiphilic/charged derivatives, so called shape amphiphiles. Since most of the unique properties of water originate from the pattern of hydrogen bond network and its dynamics, spatial, and orientational aspects of water in solvation shells around the solute surface having hydrophilic and hydrophobic regions are analyzed. Dynamical properties such as translational-rotational mobility, reorientational correlation and occupation time correlation functions of water molecules, and diffusion coefficients are also calculated. Slower dynamics of solvent molecules—water retardation—in the vicinity of the solutes is observed. Both the topological properties of hydrogen bond pattern and the “dangling” –OH groups that represent surface defects in water network are monitored. The fraction of such defect structures is increased near the hydrophobic cap of fullerenes. Some “dry” regions of C{sub 60} are observed which can be considered as signatures of surface dewetting. In an effort to provide molecular level insight into the thermodynamics of hydration, the free energy of solvation is determined for a family of fullerene particles using thermodynamic integration technique.

  20. Water in contact with extended hydrophobic surfaces: Direct evidence of weak dewetting

    DEFF Research Database (Denmark)

    Jensen, Torben René; Jensen, Morten Østergaard; Reitzel, Niels

    2003-01-01

    X-ray reflectivity measurements reveal a significant dewetting of a large hydrophobic paraffin surface floating on water. The dewetting phenomenon extends less than 15 Angstrom into the bulk water phase and results in an integrated density deficit of about one water molecule per 25-30 Angstrom(2...

  1. Enzymatic Treatments to Improve Mechanical Properties and Surface Hydrophobicity of Jute Fiber Membranes

    Directory of Open Access Journals (Sweden)

    Aixue Dong

    2016-02-01

    Full Text Available Fiber membranes prepared from jute fragments can be valuable, low cost, and renewable. They have broad application prospects in packing bags, geotextiles, filters, and composite reinforcements. Traditionally, chemical adhesives have been used to improve the properties of jute fiber membranes. A series of new laccase, laccase/mediator systems, and multi-enzyme synergisms were attempted. After the laccase treatment of jute fragments, the mechanical properties and surface hydrophobicity of the produced fiber membranes increased because of the cross-coupling of lignins with ether bonds mediated by laccase. The optimum conditions were a buffer pH of 4.5 and an incubation temperature of 60 °C with 0.92 U/mL laccase for 3 h. Laccase/guaiacol and laccase/alkali lignin treatments resulted in remarkable increases in the mechanical properties; in contrast, the laccase/2,2’-azino-bis-(3-ethylthiazoline-6-sulfonate (ABTS and laccase/2,6-dimethoxyphenol treatments led to a decrease. The laccase/ guaiacol system was favorable to the surface hydrophobicity of jute fiber membranes. However, the laccase/alkali lignin system had the opposite effect. Xylanase/laccase and cellulase/laccase combined treatments were able to enhance both the mechanical properties and the surface hydrophobicity of jute fiber membranes. Among these, cellulase/laccase treatment performed better; compared to mechanical properties, the surface hydrophobicity of the jute fiber membranes showed only a slight increase after the enzymatic multi-step processes.

  2. Partitioning of hydrophobic organic contaminants between polymer and lipids for two silicones and low density polyethylene

    DEFF Research Database (Denmark)

    Smedes, Foppe; Rusina, Tatsiana P.; Beeltje, Henry

    2017-01-01

    Polymers are increasingly used for passive sampling of neutral hydrophobic organic substances (HOC) in environmental media including water, air, soil, sediment and even biological tissue. The equilibrium concentration of HOC in the polymer can be measured and then converted into equilibrium conce...... for a thermodynamically sound risk assessment of HOC contained in microplastics....

  3. Rheological Properties of Associative Star Polymers in Aqueous Solutions: Effect of Hydrophobe Length and Polymer Topology

    DEFF Research Database (Denmark)

    Hietala, Sami; Strandman, Satu; Jarvi, Paula

    2009-01-01

    triblock copolymer. These polymers, synthesized by atom transfer radical polymerization (ATRP), were found to form hydrogels due to intermolecular association originating from the PS blocks. The increasing length of the PS block was observed to lead to more elastic networks due to increased hydrophobic...

  4. Synthesis and surface modification of hydrophobic magnetite to processible magnetite at silica-propylamine

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Kyoungja [Korea Institute of Science and Technology, Nanomaterials Research Center, P.O. Box 131, Cheongryang, Seoul 130-650 (Korea, Republic of)]. E-mail: kjwoo@kist.re.kr; Hong, Jangwon [Korea Institute of Science and Technology, Nanomaterials Research Center, P.O. Box 131, Cheongryang, Seoul 130-650 (Korea, Republic of); Ahn, Jae-Pyoung [Korea Institute of Science and Technology, Nanomaterials Research Center, P.O. Box 131, Cheongryang, Seoul 130-650 (Korea, Republic of)

    2005-05-15

    Hydrophobic magnetite nanoparticles with a narrow size distribution were prepared by thermal decomposition of Fe(CO){sub 5} in octyl ether solution of oleic acid and by consecutive aeration. The nanoparticles were converted into magnetite core/silica shell (magnetite at silica) structured particles with hydrophilic and processible aminopropyl groups on their surfaces.

  5. Role of the hydrophobic phase for the unique rheologica properties of saponin adsorption layers

    NARCIS (Netherlands)

    Golemanov, K.; Tcholakova, S.; Denkov, N.; Pelan, E.G.; Stoyanov, S.D.

    2014-01-01

    Saponins are a diverse class of natural, plant derived surfactants, with peculiar molecular structure consisting of a hydrophobic scaffold and one or several hydrophilic oligosaccharide chains. Saponins have strong surface activity and are used as natural emulsifiers and foaming agents in food and

  6. Tritium removal by hydrogen isotopic exchange between hydrogen gas and water on hydrophobic catalyst

    International Nuclear Information System (INIS)

    Morishita, T.; Isomura, S.; Izawa, H.; Nakane, R.

    1980-01-01

    Many kinds of the hydrophobic catalysts for hydrogen isotopic exchange between hydrogen gas and water have been prepared. The carriers are the hydrophobic organic materials such as polytetrafluoroethylene(PTFE), monofluorocarbon-PTFE mixture(PTFE-FC), and styrene-divinylbenzene copolymer(SDB). 0.1 to 2 wt % Pt is deposited on the carriers. The Pt/SDB catalyst has much higher activity than the Pt/PTFE catalyst and the Pt/PTFE-FC catalyst shows the intermediate value of catalytic activity. The observation of electron microscope shows that the degrees of dispersion of Pt particles on the hydrophobic carriers result in the difference of catalytic activities. A gas-liquid separated type column containing ten stages is constructed. Each stage is composed of both the hydrophobic catalyst bed for the hydrogen gas/water vapor isotopic exchange and the packed column type bed for the water vapor/liquid water isotopic exchange. In the column hydrogen gas and water flow countercurrently and hydrogen isotopes are separated

  7. Tailoring super-hydrophobic properties of electrochemical biosensor for early cancer detection

    KAUST Repository

    Malara, Natalia; Gentile, Francesco; Ferrara, Lorenzo; Villani, Marco; Iannotta, Salvatore; Zappettini, Andrea; Di Fabrizio, Enzo M.; Trunzo, Valentina; Mollace, Vincenzo; Coppedé , Nicola

    2016-01-01

    of health, sub-clinical and cancer patients. The device comprises arrays of super-hydrophobic micro-pillars in which a finite number of pillars incorporates nano-electrodes for site specific measurements of a solution. Due to its nano-scale architecture

  8. Partitioning of hydrophobic organic contaminants between polymer and lipids for two silicones and low density polyethylene

    NARCIS (Netherlands)

    Smedes, F.; Rusina, T.P.; Beeltje, H.; Mayer, P.

    2017-01-01

    Polymers are increasingly used for passive sampling of neutral hydrophobic organic substances (HOC) in environmental media including water, air, soil, sediment and even biological tissue. The equilibrium concentration of HOC in the polymer can be measured and then converted into equilibrium

  9. How osmolytes influence hydrophobic polymer conformations: A unified view from experiment and theory.

    Science.gov (United States)

    Mondal, Jagannath; Halverson, Duncan; Li, Isaac T S; Stirnemann, Guillaume; Walker, Gilbert C; Berne, Bruce J

    2015-07-28

    It is currently the consensus belief that protective osmolytes such as trimethylamine N-oxide (TMAO) favor protein folding by being excluded from the vicinity of a protein, whereas denaturing osmolytes such as urea lead to protein unfolding by strongly binding to the surface. Despite there being consensus on how TMAO and urea affect proteins as a whole, very little is known as to their effects on the individual mechanisms responsible for protein structure formation, especially hydrophobic association. In the present study, we use single-molecule atomic force microscopy and molecular dynamics simulations to investigate the effects of TMAO and urea on the unfolding of the hydrophobic homopolymer polystyrene. Incorporated with interfacial energy measurements, our results show that TMAO and urea act on polystyrene as a protectant and a denaturant, respectively, while complying with Tanford-Wyman preferential binding theory. We provide a molecular explanation suggesting that TMAO molecules have a greater thermodynamic binding affinity with the collapsed conformation of polystyrene than with the extended conformation, while the reverse is true for urea molecules. Results presented here from both experiment and simulation are in line with earlier predictions on a model Lennard-Jones polymer while also demonstrating the distinction in the mechanism of osmolyte action between protein and hydrophobic polymer. This marks, to our knowledge, the first experimental observation of TMAO-induced hydrophobic collapse in a ternary aqueous system.

  10. SYNTHESIS AND CATALYTIC PROPERTIES OF CROSS-LINKED HYDROPHOBICALLY ASSOCIATING POLY(ALKYLMETHYLDIALLYLAMMONIUM BROMIDES)

    NARCIS (Netherlands)

    WANG, GJ; ENGBERTS, JBFN

    1994-01-01

    Cross-linked, hydrophobically associating homo- and copolymers were synthesized by free-radical cyclo(co)polymerization of alkylmethyldiallylammonium bromide monomers with a small amount of N,N'-methylenebisacrylamide in aqueous solution using ammonium persulfate as the initiator. The cross-linked

  11. Fabrication of hydrophobic compressed oil palm trunk surface by sol-gel process

    Science.gov (United States)

    Muzakir, Syafiqah; Salim, Nurjannah; Huda Abu Bakar, Nurul; Roslan, Rasidi; Sin, Lim Wan; Hashim, Rokiah

    2018-04-01

    Improvement of the robustness of hydrophobic surfaces is crucial to achieving commercial applications of these surfaces in such various areas as self-cleaning, water repellency and corrosion resistance. Compressed oil palm trunk (OPT) panel is one of potential product which can be used as panelling and indoor furniture application. By adding hydrophobic properties to compressed oil palm trunk panel might increase the application of compressed oil palm trunk especially for outdoor application. In this study, fabrication is using the sol-gel technique. Sol-gel was prepared by adding ethanol with Hexadecyl Trimethyl Ammonium Bromide (CTAB) solution with Tetraethyl Orthosilicate (TEOS) with surface modification of chlorotrimethylsilane (CTMS). The surface with hydrophobic coating was undergone surface analysis with contact angle machine with the aid of software SCA 20 and the determined of the morphology of surface with scanning electron microscope (SEM). The produced compressed oil palm trunk surfaces exhibited promising hydrophobic properties with a contact angle of 104° and the relatively better mechanical robustness.

  12. Immobilization of molecular cobalt electrocatalyst by hydrophobic interaction with hematite photoanode for highly stable oxygen evolution

    KAUST Repository

    Joya, Khurram

    2015-07-15

    A unique modification of a hematite photoanode with perfluorinated Co-phthalocyanine (CoFPc) by strong binding associated with hydrophobic interaction is demonstrated. The resultant molecular electrocatalyst – hematite photoanode hybrid material showed significant onset shift and high stability for photoelectrochemical oxidation evolution reaction (OER).

  13. Nanomechanical probing of soft matter through hydrophobic AFM tips fabricated by two-photon polymerization

    International Nuclear Information System (INIS)

    Suriano, Raffaella; De Marco, Carmela; Turri, Stefano; Zandrini, Tommaso; Osellame, Roberto; Bragheri, Francesca

    2016-01-01

    Atomic force microscopy (AFM) nanoindentation of soft materials is a powerful tool for probing mechanical properties of biomaterials. Though many results have been reported in this field over the last decade, adhesion forces between the tip and the sample hinder the elastic modulus measurement when hydrophilic soft samples are investigated. Here, two-photon polymerization (2PP) technology was used to fabricate hydrophobic perfluoropolyether-based AFM tips. The hydrophobic 2PP tips allowed us to overcome the limitations of commercial and functionalized tips as well as to successfully measure the elastic modulus of medically relevant soft materials in air. Our results obtained in the characterization of poly(dimethyl siloxane) and polyethylene glycol hydrogels showed lower adhesion forces over a larger measurement range when compared to measurements performed with commercial tips. The elastic moduli measured by means of hydrophobic 2PP AFM tips were also found to be comparable to those obtained using conventional techniques for macroscopic samples. We successfully showed that the hydrophobic AFM tips developed by this highly versatile technology enable the study of mechanical properties of soft matter, benefiting from reduced sample–tip interactions, and a custom-made shape and dimension of the tips. (paper)

  14. Role of air bubbles overlooked in the adsorption of perfluorooctanesulfonate on hydrophobic carbonaceous adsorbents.

    Science.gov (United States)

    Meng, Pingping; Deng, Shubo; Lu, Xinyu; Du, Ziwen; Wang, Bin; Huang, Jun; Wang, Yujue; Yu, Gang; Xing, Baoshan

    2014-12-02

    Hydrophobic interaction has been considered to be responsible for adsorption of perfluorooctanesulfonate (PFOS) on the surface of hydrophobic adsorbents, but the long C-F chain in PFOS is not only hydrophobic but also oleophobic. In this study, for the first time we propose that air bubbles on the surface of hydrophobic carbonaceous adsorbents play an important role in the adsorption of PFOS. The level of adsorption of PFOS on carbon nanotubes (CNTs), graphite (GI), graphene (GE), and powdered activated carbon (PAC) decreases after vacuum degassing. Vacuum degassing time and pressure significantly affect the removal of PFOS by these adsorbents. After vacuum degassing at 0.01 atm for 36 h, the extent of removal of PFOS by the pristine CNTs and GI decreases 79% and 74%, respectively, indicating the main contribution of air bubbles to PFOS adsorption. When the degassed solution is recontacted with air during the adsorption process, the removal of PFOS recovers to the value obtained without vacuum degassing, further verifying the key role of air bubbles in PFOS adsorption. By theoretical calculation, the distribution of PFOS in air bubbles on the adsorbent surfaces is discussed, and a new schematic sorption model of PFOS on carbonaceous adsorbents in the presence of air bubbles is proposed. The accumulation of PFOS at the interface of air bubbles on the adsorbents is primarily responsible for its adsorption, providing a new mechanistic insight into the transport, fate, and removal of PFOS.

  15. Effect of hydrophobic additive on oxygen transport in catalyst layer of proton exchange membrane fuel cells

    Science.gov (United States)

    Wang, Shunzhong; Li, Xiaohui; Wan, Zhaohui; Chen, Yanan; Tan, Jinting; Pan, Mu

    2018-03-01

    Oxygen transport resistance (OTR) is a critical factor influencing the performance of proton exchange membrane fuel cells (PEMFCs). In this paper, an effective method to reduce the OTR of catalyst layers (CLs) by introducing a hydrophobic additive into traditional CLs is proposed. A low-molecular-weight polytetrafluoroethylene (PTFE) is selected for its feasibility to prepare an emulsion, which is mixed with a traditional catalyst ink to successfully fabricate the CL with PTFE of 10 wt%. The PTFE film exists in the mesopores between the carbon particles. The limiting current of the hydrophobic CL was almost 4000 mA/cm2, which is 500 mA/cm2 higher than that of the traditional CL. PTFE reduces the OTR of the CL in the dry region by as much as 24 s/m compared to the traditional CL and expands the dry region from 2000 mA/cm2 in the traditional CL to 2500 mA/cm2. Furthermore, the CL with the hydrophobic agent can improve the oxygen transport in the wet region (>2000 mA/cm2) more effectively than that in the dry region. All these results indicate that the CL with the hydrophobic agent shows a superior performance in terms of optimizing water management and effectively reduces the OTR in PEMFCs.

  16. CORRELATION BETWEEN HYDROPHOBICITY AND RESISTANCE TO NONOXYNOL-9 AND VANCOMYCIN FOR UROGENITAL ISOLATES OF LACTOBACILLI

    NARCIS (Netherlands)

    TOMECZEK, L; REID, G; CUPERUS, PL; MCGROARTY, JA; VANDERMEI, HC; BRUCE, AW; KHOURY, AE; BUSSCHER, HJ

    1992-01-01

    Seven clinical isolates of lactobacilli were found to be relatively hydrophobic with a mean water-contact angle of 66 +/- 15 degrees, and to be susceptible to 1% nonoxynol-9 and vancomycin. However, seven other strains were relatively hydrophilic with a mean water-contact angle of 32 +/- 13 degrees,

  17. Diels-Alder reactions in water : Enforced hydrophobic interaction and hydrogen bonding

    NARCIS (Netherlands)

    Engberts, Jan B.F.N.

    1995-01-01

    Second-order rate constants have been measured for the Diels-Alder (DA) reactions of cyclopentadiene with dienophiles of varying hydrophobicity and hydrogen-bond acceptor capacity in water, in a series of organic solvents and in alcohol-water mixtures. The intramolecular DA reaction of

  18. DIELS-ALDER REACTIONS IN WATER - ENFORCED HYDROPHOBIC INTERACTION AND HYDROGEN-BONDING

    NARCIS (Netherlands)

    Engberts, J.B.F.N.

    Second-order rate constants have been measured for the Diels-Alder (DA) reactions of cyclopentadiene with dienophiles of varying hydrophobicity and hydrogen-bond acceptor capacity in water, in a series of organic solvents and in alcohol-water mixtures. The intramolecular DA reaction of

  19. Effects of the Hydrophobicity of the Reactants on Diels-Alder Reactions in Water

    NARCIS (Netherlands)

    Meijer, Ale; Otto, Sijbren; Engberts, Jan B.F.N.

    1998-01-01

    To assess the importance of the hydrophobicity of different parts of diene and dienophile on the aqueous acceleration of Diels-Alder reactions, second-order rate constants have been determined for the reactions of cyclopentadiene (1), 2,3-dimethyl-1,3-butadiene (4), and 1,3-cyclohexadiene (6) with

  20. Controlled Release from Zein Matrices : Interplay of Drug Hydrophobicity and pH

    NARCIS (Netherlands)

    Bouman, Jacob; Belton, Peter; Venema, Paul; van der Linden, Erik; de Vries, Renko; Qi, Sheng

    In earlier studies, the corn protein zein is found to be suitable as a sustained release agent, yet the range of drugs for which zein has been studied remains small. Here, zein is used as a sole excipient for drugs differing in hydrophobicity and isoelectric point: indomethacin, paracetamol and