Academic literature on the topic 'Hydrophobicitet'

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Journal articles on the topic "Hydrophobicitet"

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Leelamanie, D. A. L., and Jutaro Karube. "Water stable aggregates of Japanese Andisol as affected by hydrophobicity and drying temperature." Journal of Hydrology and Hydromechanics 62, no. 2 (June 1, 2014): 97–100. http://dx.doi.org/10.2478/johh-2014-0019.

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Abstract Hydrophobicity is a property of soils that reduces their affinity for water, which may help impeding the pressure build-up within aggregates, and reducing aggregate disruption. The purpose of this study was to examine the relation of soil hydrophobicity and drying temperature to water stability of aggregates while preventing the floating of dry aggregates using unhydrophobized and hydrophobized surface Andisol. Soil was hydrophobized using stearic acid into different hydrophobicities. Hydrophobicity was determined using sessile drop contact angle and water drop penetration time (WDPT). Water stability of aggregates (%WSA) was determined using artificially prepared model aggregates. The %WSA increased as the contact angle and WDPT increased. Contact angle and WDPT, which provided maximum %WSA showing less than 1 s of floating, was around 100° and 5 s, respectively. Although the %WSA gradually increased with increasing contact angle and WDPT above this level, high levels of hydrophobicity initiated aggregate floating, which would cause undesirable effects of water repellency. Heating at 50°C for 5 h d-1 significantly affected %WSA and hydrophobicity in hydrophobized samples, but did not in unhydrophobized samples. The results indicate that the contact angle and wetting rate (WDPT) are closely related with the water stability of aggregates. The results further confirm that high levels of hydrophobicities induce aggregate floating, and the drying temperature has differential effects on hydrophobicity and aggregate stability depending on the hydrophobic materials present in the soil.
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Guerrero, Esther, José María Saugar, Katsumi Matsuzaki, and Luis Rivas. "Role of Positional Hydrophobicity in the Leishmanicidal Activity of Magainin 2." Antimicrobial Agents and Chemotherapy 48, no. 8 (August 2004): 2980–86. http://dx.doi.org/10.1128/aac.48.8.2980-2986.2004.

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ABSTRACT The emergence of membrane-active antimicrobial peptides as new alternatives against pathogens with multiantibiotic resistance requires the design of better analogues. Among the different physicochemical parameters involved in the optimization of linear antimicrobial peptides, positional hydrophobicity has recently been incorporated. This takes into consideration the concept of the topological distribution of hydrophobic residues throughout the sequence rather than the classical concept of hydrophobicity as a global parameter of the peptide, calculated as the summation of the individual hydrophobicities of the residues. In order to assess the contribution of this parameter to the leishmanicidal mechanisms of magainin 2 analogues, the activities of two of these analogues, MG-H1 (GIKKFLHIIWKFIKAFVGEIMNS) and MG-H2 (IIKKFLHSIWKFGKAFVGEIMNI), which have similar charges, amino acid compositions, and hydrophobicities but different positional hydrophobicities, against Leishmania donovani promastigotes were assayed (T. Tachi, R. F. Epand, R. M. Epand, and K. Matsuzaki, Biochemistry 41:10723-10731, 2002). The activities were compared with that of the parental peptide, F5W-magainin 2 (GIGKWLHSAKKFGKAFVGEIMNS). The three peptides were active at micromolar concentrations, in the order MG-H2 > MG-H1 > F5W-magainin 2. These activities differ from their hemolytic and bactericidal activities. The results demonstrate that positional hydrophobicity, which reflects the presence of short stretches of sequences rich in hydrophobic amino acids, plays an important role in the activities of leishmanicidal peptides.
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Regester, Geoffrey O., R. John Pearce, Victor W. K. Lee, and Michael E. Mangino. "Heat-related changes to the hydrophobicity of cheese whey correlate with levels of native β-lactoglobulin and α-lactalbumin." Journal of Dairy Research 59, no. 4 (November 1992): 527–32. http://dx.doi.org/10.1017/s0022029900027199.

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SummaryCorrelations were identified between levels of the native whey proteins, β-lactoglobulin and α-lactalbumin and the surface and total hydrophobicities of cheese whey in response to different heat treatments. Heat-induced changes in the native βlactoglobulin content and surface hydrophobicity of whey exhibited the most significant linear relationship while correlations between total hydrophobicity and the native proteins were less significant because of an atypical rise in the n−heptane-binding capacity of whey after high-temperature treatment. The content of native β-lactoglobulin in whey was more sensitive to heating than the content of native α-lactalbumin, while heat-related changes in the total hydrophobicity of whey were generally greater than similar changes in surface hydrophobicity.
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Chalmers, G. W., J. M. Gosline, and M. A. Lillie. "The hydrophobicity of vertebrate elastins." Journal of Experimental Biology 202, no. 3 (February 1, 1999): 301–14. http://dx.doi.org/10.1242/jeb.202.3.301.

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An evolutionary trend towards increasing hydrophobicity of vertebrate arterial elastins suggests that there is an adaptive advantage to higher hydrophobicity. The swelling and dynamic mechanical properties of elastins from several species were measured to test whether hydrophobicity is associated with mechanical performance. Hydrophobicity was quantified according to amino acid composition (HI), and two behaviour-based indices: the Flory-Huggins solvent interaction parameter (chi1), and a swelling index relating tissue volumes at 60 and 1 degrees C. Swelling index values correlated with chi1 and, for most species studied, with HI, suggesting that the different approaches used to quantify hydrophobicity are equally valid. Dynamic mechanical properties were measured both in a closed system, to control the effects of water content, and in an open system, to determine whether the increased swelling of hydrophobic materials at low temperatures offsets the direct stiffening effect of cold. There were no biologically significant differences in mechanical behaviour in either open or closed systems that could be attributed to hydrophobicity. Therefore, although the original function of hydrophobicity in an ancestral elastin may have been to produce molecular mobility, mechanical performance did not drive a subsequent increase in hydrophobicity. Higher hydrophobicities may have arisen to facilitate the manufacture of the elastic fibre.
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Miklavžin, Ana, Mateja Cegnar, Janez Kerč, and Julijana Kristl. "Effect of surface hydrophobicity of therapeutic protein loaded in polyelectrolyte nanoparticles on transepithelial permeability." Acta Pharmaceutica 68, no. 3 (September 1, 2018): 275–93. http://dx.doi.org/10.2478/acph-2018-0032.

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Abstract Oral delivery of protein drugs is greatly limited by low hydrophobicity, an important determinant for intestinal epithelial permeation and bioavailability. Herein, surface properties of recombinant erythropoietin were investigated using the fluorescent dye bis-ANS to monitor relative hydrophobicity for correlation with permeabilities with Caco-2 cells. At various pHs, bis-ANS fluorescence intensity indicated different surface hydrophobicities of erythropoietin molecules. Erythropoietin incorporated in chitosan or chitosan-trimethylchitosan (CS-TMC) nanoparticles prepared by polyelectrolyte complexation and ionotropic gelation with tripolyphosphate also showed different surface hydrophobicities. Chitosan nanoparticles with erythropoietin provided the most hydrophobic surface, followed by free erythropoietin (in water) and that loaded into CS-TMC nanoparticles. Chitosan nanoparticles were more effective than CS-TMC nanoparticles for permeation of erythropoietin across Caco-2 cell monolayers; the lowest permeability was shown by erythropoietin itself. Thus, hydrophilic protein molecules complexed with polyelectrolytes can provide more hydrophobic surfaces that enhance transepithelial permeability. This bis-ANS method also provides valuable information for the design of polyelectrolyte nanoparticules for oral delivery of protein drugs.
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Jeffs, Lloyd B., Ilungo J. Xavier, Russell E. Matai, and George G. Khachatourians. "Relationships between fungal spore morphologies and surface properties for entomopathogenic members of the general Beauveria, Metarhizium, Paecilomyces,Tolypocladium, and Verticillium." Canadian Journal of Microbiology 45, no. 11 (November 1, 1999): 936–48. http://dx.doi.org/10.1139/w99-097.

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The surface properties of aerial conidia (AC) from 24 strains of entomopathogenic fungi were studied and compared using the salt-mediated aggregation and sedimentation (SAS) assay, electron microscopy, FITC-labelled lectins, and spore dimensions. Spores with rugose surfaces were hydrophobic, whereas hydrophilic spores had smooth surfaces. Correlation analysis found no link between spore dimensions and either hydrophobicity or surface carbohydrates. However, there was a strong positive correlation between spore hydrophobicity and surface carbohydrates. The three spore types of Beauveria bassiana were all shown to possess discrete surface hydrophobicities, which were also strongly linked to surface carbohydrate profiles. Various chemical treatments had pronounced effects on spore surface properties, with sodium dodecyl sulfate (SDS) and formic acid (FA) reducing both lectin binding and surface hydrophobicity. When FA-protein extracts were separated and analysed using SDS-PAGE, only the hydrophobic spores had low molecular weight hydrophobin-like peptides that were unglycosylated and contained disulfide bonds. The strains with hydrophilic AC had much lower levels of FA-extractable protein per spore dry weight compared to their more hydrophobic counterparts. Moreover, extracts of the more hydrophobic spores tended to have greater protein:carbohydrate ratios.Key words: fungi, spores, hydrophobicity, lectins, morphology, microbial insecticides, protein.
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Zhang, Yongjian, Xin Gao, Hai Chu, and Bernard P. Binks. "Various crust morphologies of colloidal droplets dried on a super-hydrophobic surface." Canadian Journal of Physics 98, no. 11 (November 2020): 1055–59. http://dx.doi.org/10.1139/cjp-2019-0451.

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We have studied the evaporation of water droplets containing silica nanoparticles of various hydrophobicities deposited on a super-hydrophobic substrate. Evaporation induces particle accumulation at the droplet surface and results in the formation of a crust that buckles during further shrinkage. For droplets containing hydrophilic particles, a bowl-shaped crust was observed. For droplets containing hydrophobic particles, the crust develops a multi-buckled shape that could be completely suppressed by increasing the relative humidity. The varied buckling behavior of droplets may be attributed to the different mechanical properties of the gelled layer where particle hydrophobicity plays a role. Our work highlights the important role of particle hydrophobicity and relative humidity in the final crust morphology, thus shedding light on crust shape control and material design via the droplet evaporation approach.
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Millsap, Kevin W., Gregor Reid, Henny C. van der Mei, and Henk J. Busscher. "Cluster analysis of genotypically characterized Lactobacillus species based on physicochemical cell surface properties and their relationship with adhesion to hexadecane." Canadian Journal of Microbiology 43, no. 3 (March 1, 1997): 284–91. http://dx.doi.org/10.1139/m97-039.

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Lactobacilli can interfere with the adhesion of uropathogens to uroepithelial cells and catheter materials through a variety of mechanisms, such as adhesion. Lactobacillus adhesion to substratum surfaces has been theorized to result from the physicochemical properties of the interacting surfaces. In this paper physicochemical cell-surface properties, including hydrophobicity (determined by water contact angles), pH dependence of zeta potentials, elemental surface composition (determined by X-ray photoelectron spectroscopy), and adhesion to hexadecane, of four genotypically characterized Lactobacillus species (eight L. acidophilus, eight L. casei, four L. fermentum, and seven L. plantarum strains) were determined to see whether a grouping of the strains according to their phenotypes could be obtained that corresponded with the genotypic characterization of the strains. The strains showed major differences in physicochemical cell-surface properties: at the species level relationships could be observed between water contact angles, isoelectric points, and the N/C and O/C elemental surface concentration ratios, with nitrogen-containing groups (proteins) being responsible for increased hydrophobicities and isoelectric points, and oxygen-containing groups (phosphates and polysaccharides) yielding decreased hydrophobicities and isoelectric points. A hierarchical cluster analysis grouped all L. acidophilus strains in one well-separated cluster that also included two L. casei and two L. fermentum strains. Separation of L. acidophilus from the other species was done predominantly on the basis of increased cell surface hydrophobicity (average water contact angle of 63°) and isoelectric point (approximately pH 3.3) as compared with the other species, which had lower water contact angles and isoelectric points, and corresponded with the observation that only L. acidophilus strains adhered in measurable numbers to hexadecane. Also, the L. plantarum strains were grouped closely together in one cluster, but this cluster was heterogeneous due to the inclusion of L. casei and L. fermentum strains.Key words: Lactobacillus, surface properties, hydrophobicity, zeta potential, adhesion.
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Jeffs, Lloyd B., and George G. Khachatourians. "Estimation of spore hydrophobicity for members of the genera Beauveria, Metarhizium, and Tolypocladium by salt-mediated aggregation and sedimentation." Canadian Journal of Microbiology 43, no. 1 (January 1, 1997): 23–28. http://dx.doi.org/10.1139/m97-004.

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The surface hydrophobicities of fungal spores from the entomopathogenic genera Beauveria, Metarhizium, and Tolypocladium were quantitatively measured and compared using a novel assay employing salt-mediated aggregation and sedimentation (SAS). Spores with greater hydrophobicities were easily identified by their aggregation and sedimentation out of suspension at faster rates under lower salt concentrations. Of the three ammonium salts investigated for their salting-out potentials, ammonium sulfate gave the most pronounced effect, closely followed by ammonium chloride, and then ammonium acetate. Using the SAS assay, spores exhibited more pronounced hydrophobic properties at pH 5.8 than at higher pH values of 6.8 and 7.8. The effects of temperature and spore concentration upon the SAS assay were also investigated, with greater spore sedimentation occurring at elevated temperature. By plotting SAS values for two ammonium salt concentrations (0.01 and 0.1 M) in a coordinate system, it was possible to differentiate the hydrophobicities of all five spore isolates, clearly demonstrating the superiority of SAS over an existing phase-exclusion assay. The significance and potential of the SAS assay are also discussed.Key words: fungal spores, hydrophobicity, microassay, SAS, salting out, microbial insecticides.
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ASAMOTO, Yasumasa, Susumu TAZUMA, Hidenori OCHI, Kazuaki CHAYAMA, and Hiroshi SUZUKI. "Bile-salt hydrophobicity is a key factor regulating rat liver plasma-membrane communication: relation to bilayer structure, fluidity and transporter expression and function." Biochemical Journal 359, no. 3 (October 25, 2001): 605–10. http://dx.doi.org/10.1042/bj3590605.

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Bile-salt hydrophobicity regulates biliary phospholipid secretion and subselection. The aim of this study was to determine whether bile salts can influence liver plasma membrane phospholipids and fluidity in relation to the ATP-dependent transporter. Rats were depleted of bile salts by overnight biliary diversion and then sodium taurocholate was infused intravenously at a constant rate (200nmol/min per 100g of body weight), followed by infusion of bile salts with various hydrophobicities (taurochenodeoxycholate, tauroursodeoxycholate, tauro-β-muricholate, tauro-α-muricholate at 200nmol/min per 100g of body weight). The hydrophobicity of the infused bile salts correlated with that of biliary phospholipids, but was inversely related to that of the canalicular membrane bilayer. Canalicular membrane fluidity (estimated by 1,6-diphenyl-1,3,5-hexatriene fluorescence depolarization) and expression of multidrug-resistance proteins (Mrp2, Mrp3) and apical Na+-dependent bile-salt transporter (ASBT) were increased by hydrophilic bile salts, although there was no marked change in the expression of P-glycoprotein subfamilies (Mdr2). Bile-salt export pump (Bsep) expression was increased along with increasing bile-salt hydrophobicity. Bile salts modulate canalicular membrane phospholipids and membrane fluidity, as well as the ATP-dependent transporter expression and function, and these actions are associated with their hydrophobicity. The cytoprotective effect of hydrophilic bile salts seems to be associated with induction of Mrp2, Mrp3 and ASBT.
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Dissertations / Theses on the topic "Hydrophobicitet"

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Jönsson, Ingrid. "Bio-based water/dirt repellant wood coating." Thesis, KTH, Fiber- och polymerteknologi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298182.

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Syftet med detta examensarbete var att utveckla en helt bio-baserad vatten- och smutsavstötande ytbehandling för trä med ambitionen att ersätta en icke bio-baserad referens produkt på marknaden. Flera emulsioner med oljor och vaxer har framställts och analyserats utefter emulsionernas stabilitet och kvalitet. Flera av dessa emulsioners vattenabsorption, kontaktvinkel, pH värde vid ytan och åldrande i utomhusmiljö testades också efter att olika typer av trä behandlats med formuleringarna. En del av formuleringarna verkade ge liknande vattenabsorption som referensen på de olika typerna av trä med undantag för trä typ 4 där de bio-baserade formuleringarna presterade bättre än referensen. Vidare bildade även de bio-baserade formuleringarna en mindre gul och sträv yta jämfört med referensen och de genomgick dessutom en mindre fysisk förändring efter placering utomhus. Dock var stabiliteten för de bio-baserade emulsionerna sämre än för referensen. Dessutom resulterade de bio-baserade formuleringarna till en mindre pH sänkning på trä typ 3 med alkaliskt.
The aim of this thesis project was to develop a fully bio-based water and dirt repellent wood coating with the ambition to replace the current non-bio-based reference product on the market. Several wax and oil emulsions were made and analyzed in terms of emulsion quality and stability. Several formulations were also tested on different types of wood in terms of water absorption, weathering, surface pH and contact angle. Some formulations seam to give similar water absorption as the reference, the not bio-based product and performs similar on different types of wood with an exception on Wood type 4 where the bio-based formulations performs better than the current reference product. Secondly the bio-based formulations form a less yellow and rough coating compared to the current reference product. According to the weathering test the bio-based formulations seams to perform better. However, the stability of the bio-based formulation is not as good as the current reference product. Also, the developed bio-based conceptual formulations exhibited limited pH lowering on Wood type 3 with alkaline pH.
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Jones, Amanda Kay. "Hydrophobicity in polysaccharide gelation." Thesis, Cranfield University, 1992. http://dspace.lib.cranfield.ac.uk/handle/1826/4595.

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The role of hydrophobic substituents on the gelation mechanism of highly esterified pectin and the cellulose derivatives methylcellulose and hydroxypropylmethylcellulose (HPMC) has been explored by monitoring the behaviour of the amphiphilic polysaccharides in varying combinations of an ethylene glycoVwater solvent. The gelling ability (mechanical spectroscopy, visual observation) of very highly esterified (- 100%) pectin in high concentrations of ethylene glycol (>60%) is greatly reduced, however, the polymer still undergoes conformational ordering (CD, OR). A model for gel formation involving a two stage process has been proposed, comprising adoption of the ordered structure stabilised by hydrogen bonding between OH groups of contiguous polysaccharide chains, followed by (or coincident with) aggregation of the ordered sequences by 'hydrophobic' clustering of the fundamental structural subunits to form the three dimensional gel network. It has been found that ethylene glycol promotes the fIrst stage (ordering) but is antagonistic to the second (aggregation). The reversibility (mechanical spectroscopy) of the thermo-gelling cellulose derivatives can be largely abolished in the presence of ethylene glycol (40% for methylcellulose, 10% for HPMC), attributed to solubilisation of the proposed ordered 'bundle' structure at low temperatures removing the enthalpic advantage (DSC) of gel melting. The increased sensitivity of HPMC to modification of the solvent environment is due to the presence of the polar hydroxypropyl substituent causing an inceptive destabilisation of the 'bundle' structure. It is suggested that gelation is driven by the entropic advantage of melting-out 'cages' of structured water surrounding the hydrophobic groups giving rise to intermolecular 'hydrophobic' aggregation.
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Jäger, Robert. "Quantification and localization of molecular hydrophobicity." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=960539999.

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Crawford, Russell J., and n/a. "Particle size, hydrophobicity and flotation response." Swinburne University of Technology, 1986. http://adt.lib.swin.edu.au./public/adt-VSWT20070828.150946.

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Quartz particles of various discrete particle size ranges have been methylated to varying known mounts using trimethylchlorosilane and their flotation behaviour has been assessed in a modification of the Hallimond tube. For each particle size there is a definite degree of. surface coverage below which the particles do not float. A 'flotation domain' is identified which shorvs that both coarse (-100pm) and fine (-10pm) particles require a greater degree of surface coverage to initiate flotation than do intermediate (-40pm) particles. Water contact angles have been measured on quartz plates and powders which have been methylated (under the same conditions) with trimethylchlorosilane. Both advancing and receding water contact angles measured on quartz plates as a function of degree of surface methylationare in good agreement with the angles predicted by the Cassie equation. Advancing water contact angles measured on quartz particles as a function of degree of surface methylation are also in good agreement with angles predicted by the Cassie equation up to surface coverages of'about 70%. The angles measured at higher surface coverages are less than those anticipated by the Cassie equation. The flotation behaviour of the particles has been compared with that predicted by existing flotation theories. It has been shown that coarse particle behaviour is predicted by the kinetic theory of flotation proposed by Schulze. Fine particle behaviour, however, only qualitatively agrees with Scheludko's theory of fine particle behaviour. Calculated induction times, in conjunction with observed flotation behaviour, indicate that the bubble-particle attachment process is most efficient for particles of about 38pm in diameter ander the set experimental conditions used in this study. Flotation rate trials were performed for three particle size ranges and rate constants were evaluated for the various degrees of surface coverage. It was found that the dependence of rate constant on particle size is essentially linear.
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Fergusson, Christian. "Hydrophobicity of Low Temperature Vibrating Surfaces." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5589.

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This study proposes a method to enhance the anti-icing capabilities of superhydrophobic surfaces by utilizing vibration to further reduce contact time of an impacting droplet in addition to keeping the droplet in the Cassie-Baxter regime, where surface adhesion is lower than the opposing Wenzel regime. We tested this with two methods: by investigating the effects of vibration normal to the plane of a superhydrophobic surface being impacted by water droplets in a room temperature environment, with the surface horizontal in a room temperature environment and tiled in a subzero degree environment. The amplitude and frequency of the vibration were varied in our experiments. Our results show that the mean contact time of a 10µL droplet consistently decreased linearly as the vibration frequency increased, though the standard deviations drastically increased. The ice accretion in the second phase of the testing also had significant variance, which obfuscated any reliable trend from the introduction of vibration.
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Arbabzadeh, Sima-Dokht. "Functionality hydrophobicity relationships of selected food proteins." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69580.

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Commercial food proteins were used in order to study the relationship between hydrophobicity and two functional properties: emulsification and foaming. Hydrophobicity determined by sodium dodecyl sulfate (SDS) binding method and the cis-parinaric acid (CPA) fluorescence probe method gave poor statistical correlation with foaming and emulsification. The SDS binding method gave higher hydrophobicity and higher correlation values with foaming and emulsifying, than the fluorescence probe CPA method.
Fourier Transform Infrared (FTIR) spectroscopy was used to study the secondary structures, of the commercial food proteins. Infrared spectra of the protein samples with or without denaturing agents (SDS, urea, and guanidine) in the region of the amide I and II bands were determined in deuterium oxide (D$ sb{2}$O) buffer. Fourier self-deconvolution was used to study infrared band positions. BSA was an $ alpha$-helix protein, and in the presence of SDS, due to protein unfolding, exhibited a random coil structure. By correlating their infrared spectra to predetermined peak positions in the protein samples, it was shown that the legume proteins contained $ beta$-structure, and as SDS was added, exhibited non-ordered structures. The spectra of gluten samples were obtained only in the presence of SDS, showing either random coil, or non-ordered structures.
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Chacko, Blesson. "Hydrophobicity, solvation and structure formation in liquids." Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/27536.

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In this thesis we use density functional theory (DFT) to study the solvent mediated interactions between solvophobic, solvophilic and patchy nanostructures namely rectangular cross section blocks. We calculate both the density profiles and local compressibility around the blocks and the results obtained for our model system provide a means to understanding the basic physics of solvent mediated interactions between nanostructures, and between objects such as proteins in water, that possess hydrophobic and hydrophilic patches. Our results give an improved understanding of the behaviour of liquids around solvophobic objects and solvophobicity (hydrophobicity) in general. Secondly, we look into the physics incorporated in standard mean-field DFT. This is normally derived by making what appears to be a rather drastic approximation for the two body density distribution function: ρ(2)(r,r′) ≈ ρ(r)ρ(r′), where ρ(r) is the one-body density distribution function. We provide a rationale for why the DFT often does better than this approximation would make you expect. Finally, we develop a lattice model to understand the nature of the pattern formation exhibited by certain systems of particles deposited on liquid-air interfaces and in particular the nature of the transitions between the different patterned structures that are observed. This is done using Monte Carlo computer simulations and DFT and links the observed microphase ordering with the micellisation process seen e.g. in surfactant systems.
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Ho, Thu. "DEVELOPMENT OF MAGNETIC FABRICS WITH TUNABLE HYDROPHOBICITY." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/400.

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Polystyrene (PS) fiber mats incorporating iron (Fe) particles were fabricated by electrospinning and the hydrophobicity of the resulting magnetic fabrics was investigated with and without an applied magnetic field. The results show that the hydrophobicity (as measured using water droplet contact angle) increases in the presence of a magnetic field and the hysterisis in the advancing/receding contact angle (a measure of the stickiness of the surface) decreases in the presence of a magnetic field. It is also shown that the contact angle and hysterises increase with decreasing fiber diameter and mat thickness.
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Melki, Safi. "Etude du mouillage de structures fibreuses multi échelles : robustesse de l’hydrophobicité." Thesis, Mulhouse, 2014. http://www.theses.fr/2014MULH8863/document.

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Ces travaux ont pour but d’étudier le comportement au mouillage spontané (statique et dynamique) ainsi que le mouillage forcé, sous l’effet de la compression, de différentes structures textiles hydrophobes. Le mouillage forcé a permis d’évaluer la robustesse de l’hydrophobicité des structures textiles. En parallèle, un nouveau dispositif automatisé et plus approprié à l’étude du mouillage forcé a été mis au point. Les principaux résultats ont montré qu’une bonne hydrophobicité ne conduit pas forcément à une bonne robustesse : spontanément, la structure floquée est la seule à favoriser une configuration de Cassie-Baxter, cependant, sa robustesse est plus faible que celle des tissus. Les différents essais ont mis en évidence l’influence importante et majeure de certains paramètres, appropriés à chaque structure textile, sur son hydrophobicité et sa robustesse comme la densité et la finesse des poils pour les tissus floqués. Ils ont également montré que certains facteurs pouvaient améliorer l’hydrophobicité mais pas sa robustesse ou inversement. Ainsi, la robustesse de l’hydrophobicité n’est pas prévisible à partir des mesures du mouillage spontané
This work aims to study the spontaneous (static and dynamic) and the forced (under the effect of compression) wetting behaviour of different water-repellent textile structures. Forced wetting allowed to evaluate the robustness of the hydrophobicity of textile structures. In parallel, a new automated and more suitable device was developed for the study of forced wetting. The main results showed that a good hydrophobicity does not necessarily lead to a good robustness: spontaneously, the flocked structure is the only one to foster the Cassie-Baxter state, however, its hydrophobicity’s robustness is lower than that of the tissue. The different tests have highlighted the important and major influence of some parameters, adapted to each textile structure, on its hydrophobicity and its robustness such as the density and fineness of bristles for flocked fabrics. They also showed that some factors can improve the hydrophobicity but not its robustness or vice versa. Thus, the robustness of the hydrophobicity is not predictable from the measures of spontaneous wetting
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Akhtar, Mst Alpona. "Hydrophobicity of Magnetite Coating on Low Carbon Steel." Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1248389/.

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Superhydrophobic coatings (SHC) with excellent self-cleaning and corrosion resistance property is developed on magnetite coated AISI SAE 1020 steel by using a simple immersion method. Roughness measurement, scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), contact angle measurement (CAM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), potentiodynamic polarization test, electrochemical impedance spectroscopy (EIS), and qualitative characterization of self-cleaning behavior, antifouling property and durability of the coatings are assessed. A water contact angle as high as 152o on the coated surface with excellent self-cleaning and resistivity to corrosion and good longevity in atmospheric air is obtained. Self-cleaning test results prove that these surfaces can find applications in large scale production of engineering materials. Potentiodynamic polarization tests and EIS tests confirm that the superhydrophobic low carbon steel surfaces have better resistance to corrosion compared to bare steel and magnetite coated steel in 3.5% NaCl solution. But the longevity of the coated steel surfaces in 3.5% salt solution is limited, which is revealed by the immersion durability test. However, hydrophobic coatings (HC) have better stability in normal tap water, and it can stay unharmed up to 15 days. Finally, hydrophobic coatings on low carbon steel surface retains hydrophobic in open atmosphere for more than two months. Results of this investigation show surface roughness is a critical factor in manufacturing hydrophobic steel surfaces. Higher contact angles are obtained for rougher and more uniform surfaces. A linear mathematical relationship (y =6x+104; R2 = 0.93) is obtained between contact angle (y) and surface roughness (x).
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Books on the topic "Hydrophobicitet"

1

Du, Qishi. Developments in structure-based theoretical modeling of hydrophobicity for computer-aided drug design. Sudbury, Ont: Laurentian University Press, 1995.

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Alizai, A. K. Effect of corona impingement on hydrophobicity of various organic polymers with regard to ageing. Manchester: UMIST, 1996.

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Lelono, T. D. Effect of corona impingement on hydrophobicity of polyethylene, polypropylene, polyvinylchloride, polymethylmethacrylate and phenolic resin. Manchester: UMIST, 1994.

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Filippopoulos, K. Effect of D.C. Corona impingement on Hydrophobicity of Polythylene, Polyproylene, Polyvinychloride, Polymethylmethacrylate and Phenolic Resin. Manchester: UMIST, 1998.

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J, Doyle Ronald, and Rosenberg Mel, eds. Microbial cell surface hydrophobicity. Washington, D.C: American Society for Microbiology, 1990.

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Samuelsson, Matts-Ola. Degradation of adsorbed protein by attached bacteria in relationship to surface hydrophobicity. 1991.

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Berg, Marcus. Estimation of Hydrophobicity of Insulating Surfaces by Studying Sessile Water Drops (Uppsala Dissertations from the Faculty of Science & Technology, 33) ... the Faculty of Science & Technology, 33). Coronet Books, 2001.

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Book chapters on the topic "Hydrophobicitet"

1

Kobayashi, Kensei. "Hydrophobicity." In Encyclopedia of Astrobiology, 1. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-27833-4_5243-2.

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Kobayashi, Kensei. "Hydrophobicity." In Encyclopedia of Astrobiology, 1155. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-44185-5_5243.

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Sigmund, Wolfgang M., and Shu-Hau Hsu. "Hydrophobicity." In Encyclopedia of Membranes, 1002. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-662-44324-8_1383.

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Sigmund, Wolfgang M., and Shu-Hau Hsu. "Hydrophobicity." In Encyclopedia of Membranes, 1. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-40872-4_1383-3.

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Lag, J., Amos Hadas, Rhodes W. Fairbridge, J. C. Nóvoa Muñoz, X. Pontevedra Pombal, A. Martínez Cortizas, Gonzalo Almendros, et al. "Hydrophilicity, Hydrophobicity." In Encyclopedia of Soil Science, 329–30. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-3995-9_279.

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Smith, David E., and A. D. J. Haymet. "Computing Hydrophobicity." In Reviews in Computational Chemistry, 43–77. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2003. http://dx.doi.org/10.1002/0471466638.ch2.

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Rose, George D., and Jonathan E. Dworkin. "The Hydrophobicity Profile." In Prediction of Protein Structure and the Principles of Protein Conformation, 625–33. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4613-1571-1_15.

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Dworkin, Jonathan E., and George D. Rose. "Hydrophobicity Profiles Revisited." In Methods in Protein Sequence Analysis · 1986, 573–86. Totowa, NJ: Humana Press, 1987. http://dx.doi.org/10.1007/978-1-59259-480-1_49.

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Hallett, Paul D., Jörg Bachmann, Henryk Czachor, Emilia Urbanek, and Bin Zhang. "Hydrophobicity of Soil." In Encyclopedia of Agrophysics, 378–84. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-90-481-3585-1_195.

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Rao, S. Ramachandra. "Hydrophobicity and Contact Angle." In Surface Chemistry of Froth Flotation, 351–84. Boston, MA: Springer US, 2004. http://dx.doi.org/10.1007/978-1-4419-9124-9_8.

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Conference papers on the topic "Hydrophobicitet"

1

Wang, Pengtao, Majid Charmchi, Mengyan Shen, and Hongwei Sun. "Hydrophobicity of Nanostructured Films Characterized by a Quartz Crystal Microbalance." In ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icnmm2012-73202.

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The hydrophobicity of two types of nanostructured polymer films were fabricated and characterized with a novel quartz crystal microbalance (QCM) technique to investigate their static and dynamic hydrophobic properties. The nanofibrous films of polymethylmethacrylate (PMMA), PMMA/Polydimethylsiloxane (PDMS) and Polyacrylonitril (PAN) were prepared with an electrospinning process and a PMMA film with nanoscale roughness was fabricated using nanoimprint lithography (NIL) technique. Significantly different static and dynamic hydrophobicities (wettability) were found among these films and the correlation between hydrophobicity and the mechanical impedance of QCM to these films were developed both experimentally and theoretically. It was shown that QCM is capable of quantitatively characterizing the hydrophobicity of these nanostructured polymer surfaces. For nanofibrous films, the double layers — a viscoelastic nanofiber film and a liquid layer result in a nonlinear combination of mechanical impedances of QCM. To simplify the analysis, an apparent viscosity was introduced in the analysis to take into account the interactions between liquid and polymer surfaces. For NIL PMMA film, the hydrophobicity was altered by coating nano-roughened surface with a Teflon layer. The reduction in the mechanical impedance of QCM clearly demonstrates the enhancement of hydrophobicity. The experimental results showed that the hydrophobic surface lead to a small mechanical impedance while the hydrophilic surface resulted in a large mechanical impedance of QCM.
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Hung, Lung-Hsin, and Abraham P. Lee. "Optimization of Droplet Generation by Controlling PDMS Surface Hydrophobicity." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-61737.

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This paper presents an optimized method for droplet generation in PDMS microchannels. With controllable PDMS surface hydrophobicity and hydrophobicity recovery, alternative component droplets can be generated as anticipated. Different surface hydrophobicity results in different droplet generation patterns. Monodispersed water-in-oil and oil-in-water droplets are generated from hydrophilic and hydrophobic surface respectively. Nearly hydrophilic surface (30°<θ<50°) results in long-tailed droplets and less hydrophilic surface (70°<θ<80°) results in stream mixing. Discussion of methods to loss and recovery hydrophobicity of PDMS also included.
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Hongjie Sun, Yang Wang, Jiansheng Chen, and Henrik Hillborg. "Silicone rubber with improved hydrophobicity." In 2015 IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP). IEEE, 2015. http://dx.doi.org/10.1109/ceidp.2015.7352048.

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Liang, Chao, Wenming Yang, and Qingmin Liao. "Water droplets segmentation for hydrophobicity classification." In ICASSP 2012 - 2012 IEEE International Conference on Acoustics, Speech and Signal Processing. IEEE, 2012. http://dx.doi.org/10.1109/icassp.2012.6288098.

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Bai, Yun. "Research on hydrophobicity of graphene composites." In MATHEMATICAL SCIENCES AND ITS APPLICATIONS. Author(s), 2017. http://dx.doi.org/10.1063/1.4971890.

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Guan, Zhicheng, Kang Niu, Gongmao Peng, Fuzeng Zhang, Liming Wang, and Bernhard Lutz. "Hydrophobicity transfer property of silicone rubber material." In 2012 IEEE International Conference on Condition Monitoring and Diagnosis (CMD). IEEE, 2012. http://dx.doi.org/10.1109/cmd.2012.6416443.

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Dan Cristea, Paul, Octavian Arsene, Rodica Tuduce, and Dan V. Nicolau. "Protein surface analysis. Part 1: Hydrophobicity densities." In 2011 10th International Symposium on Signals, Circuits and Systems (ISSCS). IEEE, 2011. http://dx.doi.org/10.1109/isscs.2011.5978748.

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Zheng, Xu, and Zhanhua Silber-Li. "The hydrophobicity of surfaces with micro-structures." In 2006 1st IEEE International Conference on Nano/Micro Engineered and Molecular Systems. IEEE, 2006. http://dx.doi.org/10.1109/nems.2006.334870.

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Yang, Zhaoxiang, Zhidong Jia, Can Chen, Xuedong Zhang, Ling Liu, Ruigang Zhu, and Qiang Xie. "Hydrophobicity distribution analysis of DC composite insulators." In 2014 IEEE Electrical Insulation Conference (EIC). IEEE, 2014. http://dx.doi.org/10.1109/eic.2014.6869431.

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Bonner, Richard W. "Dropwise Condensation on Surfaces With Graded Hydrophobicity." In ASME 2009 Heat Transfer Summer Conference collocated with the InterPACK09 and 3rd Energy Sustainability Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/ht2009-88516.

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Dropwise condensation has shown the ability to increase condensation heat transfer coefficients by an order of magnitude over filmwise condensation. In standard dropwise condensation, liquid droplets forming on a sub-cooled nonwetting surface are removed from the surface by gravitational forces when the droplets reach a critical mass. The dependence on gravity for liquid removal limits the utilization of dropwise condensation in low gravity aerospace applications and horizontal surfaces. Presented in this study is a novel passive mechanism to remove droplets from a condensing surface using a surface energy gradient (wettability gradient) on the condensing surface. The wettability gradient creates a difference in contact angle across droplets condensing on the surface. The difference in contact angle across the droplets causes motion of the droplets to regions of increased wettability, without relying on additional forces. The movement of droplets away from the surface prevents flooding and allows for the condensation of new droplets on the surface. This paper presents an overall description of the wettability gradient mechanism and experimental condensation data acquired on surfaces with wettability gradients. A mechanism for creating the wettability gradients is also described, which involves varying the surface concentration of hydrophobic molecules through a self-assembled monolayer process.
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Reports on the topic "Hydrophobicitet"

1

Labuschagne, B. C. J., T. D. Wheelock, R. K. Guo, H. T. David, and R. Markuszewski. Prediction of coal hydrophobicity. Office of Scientific and Technical Information (OSTI), December 1988. http://dx.doi.org/10.2172/10163351.

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Kluger, Yuval. Membrane protein identification by hydrophobicity analysis. Office of Scientific and Technical Information (OSTI), November 2001. http://dx.doi.org/10.2172/799206.

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Labuschagne, B. C. J., R. Markuszewski, T. D. Wheelock, R. K. Guo, and H. T. David. Moisture content as a predictor of coal hydrophobicity. Office of Scientific and Technical Information (OSTI), December 1988. http://dx.doi.org/10.2172/10163787.

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