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

Hydrophobic and optical characteristics of graphene and graphene oxide films transferred onto functionalized silica particles deposited glass surface

Science.gov (United States)

Yilbas, B. S.; Ibrahim, A.; Ali, H.; Khaled, M.; Laoui, T.

2018-06-01

Hydrophobic and optical transmittance characteristics of the functionalized silica particles on the glass surface prior and after transfer of graphene and graphene oxide films on the surface are examined. Nano-size silica particles are synthesized and functionalized via chemical grafting and deposited onto a glass surface. Graphene film, grown on copper substrate, was transferred onto the functionalized silica particles surface through direct fishing method. Graphene oxide layer was deposited onto the functionalized silica particles surface via spin coating technique. Morphological, hydrophobic, and optical characteristics of the functionalized silica particles deposited surface prior and after graphene and graphene oxide films transfer are examined using the analytical tools. It is found that the functionalized silica particles are agglomerated at the surface forming packed structures with few micro/nano size pores. This arrangement gives rise to water droplet contact angle and contact angle hysteresis in the order of 163° and 2°, respectively, and remains almost uniform over the entire surface. Transferring graphene and depositing graphene oxide films over the functionalized silica particles surface lowers the water droplet contact angle slightly (157-160°) and increases the contact angle hysteresis (4°). The addition of the graphene and graphene oxide films onto the surface of the deposited functionalized silica particles improves the optical transmittance.

Characteristics of laser textured silicon surface and effect of mud adhesion on hydrophobicity

Energy Technology Data Exchange (ETDEWEB)

Yilbas, B.S., E-mail: bsyilbas@kfupm.edu.sa [ME Department, King Fahd University of Petroleum & Minerals, Kfupm box 1913, Dhahran 31261 (Saudi Arabia); Ali, H. [ME Department, King Fahd University of Petroleum & Minerals, Kfupm box 1913, Dhahran 31261 (Saudi Arabia); Khaled, M. [CHEM Department, King Fahd University of Petroleum & Minerals, Dhahran (Saudi Arabia); Al-Aqeeli, N.; Abu-Dheir, N. [ME Department, King Fahd University of Petroleum & Minerals, Kfupm box 1913, Dhahran 31261 (Saudi Arabia); Varanasi, K.K. [Mechanical Engineering, Massachusetts Institute of Technology, Boston, MA (United States)

2015-10-01

Highlights: • Laser treatment increases surface microhardness and slightly lowers surface fracture toughness. • Residual stress formed is compressive and self-annealing effect of laser tracks lowers residual stress. • Nitride species lowers surface energy and adhesion work required to remove dust. • Mud residues do not have notable effect on fracture toughness and microhardness of treated surface. • Mud residues lower surface hydrophobicity. - Abstract: Laser gas assisted texturing of silicon wafer surface is carried out. Morphological and metallurgical changes in the treated layer are examined using the analytical tools. Microhardness and fracture toughness of the laser treated surface are measured using the indentation technique while residual stress formed is determined from the X-ray diffraction data. The hydrophobicity of the textured surfaces are assessed incorporating the contact angle data and compared with those of as received workpiece surfaces. Environmental dust accumulation and mud formation, due to air humidity, at the laser treated and as received workpiece surfaces are simulated and the effect of the mud residues on the properties of the laser treated surface are studied. The adhesion work due to the presence of the mud on the laser treated surface is also measured. It is found that laser textured surface composes of micro/nano poles and fibers, which in turn improves the surface hydrophobicity significantly. In addition, formation of nitride species contributes to microhardness increase and enhancement of surface hydrophobicity due to their low surface energy. The mud residues do not influence the fracture toughness and microhardness of the laser textured surface; however, they reduced the surface hydrophobicity significantly.

Characteristics of Hospitals Associated with Complete and Partial Implementation of Electronic Health Records.

Science.gov (United States)

Bhounsule, Prajakta; Peterson, Andrew M

2016-01-01

(1) To determine the proportion of hospitals with and without implementation of electronic health records (EHRs). (2) To examine characteristics of hospitals that report implementation of EHRs partially or completely versus those that report no implementation. (3) To identify hospital characteristics associated with nonimplementation to help devise future policy initiatives. This was a retrospective cross-sectional study using the 2012 American Hospital Association Annual Survey Database. The outcome variable was the implementation of EHRs completely or partially. Independent variables were hospital characteristics, such as staffing, organization structure, accreditations, ownership, and services and facilities provided at the hospitals. Descriptive frequencies were determined, and multinomial logistic regression was used to determine variables independently associated with complete or partial implementation of EHRs. In this study, 12.6 percent of hospitals reported no implementation of EHRs, while 43.9 percent of hospitals implemented EHRs partially and 43.5 percent implemented EHRs completely. Overall characteristics of hospitals with complete and partial implementation were similar. The multinomial regression model revealed a positive association between the number of licensed beds and complete implementation of EHRs. A positive association was found between children's general medical, surgical, and heart hospitals and complete implementation of EHRs. Conversely, psychiatric and rehabilitation hospitals, limited service hospitals, hospitals participating in a network, service hospitals, government nonfederal hospitals, and nongovernment not-for-profit hospitals showed less likelihood of complete implementation of EHRs. Study findings suggest a disparity of EHR implementation between larger, for-profit hospitals and smaller, not-for-profit hospitals. Low rates of implementation were observed with psychiatric and rehabilitation hospitals. EHR policy initiatives

Maillet type theorem for singular first order nonlinear partial differential equations of totally characteristic type. Part II

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Akira Shirai

2015-01-01

Full Text Available In this paper, we study the following nonlinear first order partial differential equation: \\[f(t,x,u,\\partial_t u,\\partial_x u=0\\quad\\text{with}\\quad u(0,x\\equiv 0.\\] The purpose of this paper is to determine the estimate of Gevrey order under the condition that the equation is singular of a totally characteristic type. The Gevrey order is indicated by the rate of divergence of a formal power series. This paper is a continuation of the previous papers [Convergence of formal solutions of singular first order nonlinear partial differential equations of totally characteristic type, Funkcial. Ekvac. 45 (2002, 187-208] and [Maillet type theorem for singular first order nonlinear partial differential equations of totally characteristic type, Surikaiseki Kenkyujo Kokyuroku, Kyoto University 1431 (2005, 94-106]. Especially the last-mentioned paper is regarded as part I of this paper.

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)

Quenched polyelectrolytes with hydrophobicity independent from chemical charge fraction: A SANS and SAXS study

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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.

Exploring Alternative Characteristic Curve Approaches to Linking Parameter Estimates from the Generalized Partial Credit Model.

Science.gov (United States)

Roberts, James S.; Bao, Han; Huang, Chun-Wei; Gagne, Phill

Characteristic curve approaches for linking parameters from the generalized partial credit model were examined for cases in which common (anchor) items are calibrated separately in two groups. Three of these approaches are simple extensions of the test characteristic curve (TCC), item characteristic curve (ICC), and operating characteristic curve…

Combustion and emissions characteristics of diesel engine fueled by biodiesel at partial load conditions

International Nuclear Information System (INIS)

An, H.; Yang, W.M.; Chou, S.K.; Chua, K.J.

2012-01-01

Highlights: ► Impact of engine load on engine’s performance, combustion and emission characteristics. ► The brake specific fuel consumption (BSFC) increases significantly at partial load conditions. ► The brake thermal efficiency (BTE) drops at lower engine loads, and increases at higher loads. ► The partial load also influences the trend of CO emissions. -- Abstract: This paper investigated the performance, combustion and emission characteristics of diesel engine fueled by biodiesel at partial load conditions. Experiments were conducted on a common-rail fuel injection diesel engine using ultra low sulfur diesel, biodiesel (B100) and their blend fuels of 10%, 20%, 50% (denoted as B10, B20 and B50 respectively) under various loads. The results show that biodiesel/blend fuels have significant impacts on the engine’s brake specific fuel consumption (BSFC) and brake thermal efficiency (BTE) at partial load conditions. The increase in BSFC for B100 is faster than that of pure diesel with the decrease of engine load. A largest increase of 28.1% in BSFC is found at 10% load. Whereas for BTE, the results show that the use of biodiesel results in a reduced thermal efficiency at lower engine loads and improved thermal efficiency at higher engine loads. Furthermore, the characteristics of carbon monoxide (CO) emissions are also changed at partial load conditions. When running at lower engine loads, the CO emission increases with the increase of biodiesel blend ratio and the decrease of engine speed. However, at higher engine loads, an opposite trend is obtained.

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.

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)

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

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.

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.

Synthesis and characterization of hydrophobically modified polymeric betaines

Directory of Open Access Journals (Sweden)

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.

Partial discharge characteristics and mechanism in voids at impulse voltages

International Nuclear Information System (INIS)

Zhao, X F; Guo, Z F; Wang, Y Y; Li, J H; Li, Y M; Yao, X

2011-01-01

Partial discharge (PD) characteristics and mechanism in artificial cavities in an epoxy plate have been investigated for different void dimensions and impulse voltage waveforms. A differential measurement system was developed in order to detect PD current pulses effectively. Experimental results showed that the 50% probability PD inception voltage (PDIV 50 ) increases initially as the cavity diameter decreases at constant depth for double exponential impulses as well as oscillating impulses, but after aging, it becomes independent of the cavity diameter. Moreover, some distinctive characteristics of PD (e.g. main discharge and reverse discharge during the rise and fall phases of the applied voltage) were also investigated. The differences of the PD propagation and the mechanism between double exponential impulses and oscillating impulse were discussed

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)

Anisotropic wetting characteristics versus roughness on machined surfaces of hydrophilic and hydrophobic materials

International Nuclear Information System (INIS)

Liang, Yande; Shu, Liming; Natsu, Wataru; He, Fuben

2015-01-01

Graphical abstract: - Highlights: • The aim is to investigate the influence of roughness on anisotropic wetting on machined surfaces. • The relationship between roughness and anisotropic wetting is modeled by thermodynamical analysis. • The effect of roughness on anisotropic wetting on hydrophilic materials is stronger than that on hydrophobic materials. • The energy barrier existing in the direction perpendicular to the lay is one of the main reasons for the anisotropic wetting. • The contact angle in the parallel direction is larger than that in the perpendicular direction. - Abstract: Anisotropic wetting of machined surfaces is widely applied in industries which can be greatly affected by roughness and solid's chemical properties. However, there has not been much work on it. A free-energy thermodynamic model is presented by analyzing geometry morphology of machined surfaces (2-D model surfaces), which demonstrates the influence of roughness on anisotropic wetting. It can be concluded that the energy barrier is one of the main reasons for the anisotropic wetting existing in the direction perpendicular to the lay. In addition, experiments in investigating anisotropic wetting, which was characterized by the static contact angle and droplet's distortion, were performed on machined surfaces with different roughness on hydrophilic and hydrophobic materials. The droplet's anisotropy found on machined surfaces increased with mean slope of roughness profile Kr. It indicates that roughness on anisotropic wetting on hydrophilic materials has a stronger effect than that on hydrophobic materials. Furthermore, the contact angles predicted by the model are basically consistent with the experimentally ones

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

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.

Fluctuating partially native-like topologies in the acid denatured ensemble of autolysis resistant HIV-1 protease.

Science.gov (United States)

Rout, Manoj Kumar; Hosur, Ramakrishna V

2009-02-01

Folding, in-vivo, starts from a denatured state and thus the nature of the denatured state would play an important role in directing the folding of a protein. We report here NMR characterization of the acid-denatured state of a mutant of HIV-1 protease, designed to prevent autolysis (Q7K, L33I, L63I) and to prevent cysteine oxidation (C67A and C95A). Secondary chemical shifts, TALOS analysis of chemical shifts and (15)N relaxation data (R(1), R(2), NOE) coupled with AABUF and hydrophobicity calculations, suggest formation of hydrophobic clusters and possibility of some partially native-like topologies in the acid denatured state of the protease. The structural and dynamics characteristics of the acid denatured PR seem to be considerably different from those of the guanidine or urea denatured states of some variants of PR. These would have implications for the folding and auto-processing of the enzyme in-vivo.

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.

Morphological bubble evolution induced by air diffusion on submerged hydrophobic structures

Science.gov (United States)

Lv, Pengyu; Xiang, Yaolei; Xue, Yahui; Lin, Hao; Duan, Huiling

2017-03-01

Bubbles trapped in the cavities always play important roles in the underwater applications of structured hydrophobic surfaces. Air exchange between bubbles and surrounding water has a significant influence on the morphological bubble evolution, which in turn frequently affects the functionalities of the surfaces, such as superhydrophobicity and drag reduction. In this paper, air diffusion induced bubble evolution on submerged hydrophobic micropores under reduced pressures is investigated experimentally and theoretically. The morphological behaviors of collective and single bubbles are observed using confocal microscopy. Four representative evolution phases of bubbles are captured in situ. After depressurization, bubbles will not only grow and coalesce but also shrink and split although the applied pressure remains negative. A diffusion-based model is used to analyze the evolution behavior and the results are consistent with the experimental data. A criterion for bubble growth and shrinkage is also derived along with a phase diagram, revealing that the competition of effective gas partial pressures across the two sides of the diffusion layer dominates the bubble evolution process. Strategies for controlling the bubble evolution behavior are also proposed based on the phase diagram. The current work provides a further understanding of the general behavior of bubble evolution induced by air diffusion and can be employed to better designs of functional microstructured hydrophobic surfaces.

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.

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

importance of hydrophobicity as the dominating characteristic in the stability of thermophilic proteins, and we anticipate this will be useful in our attempts to engineering thermostable proteins. Copyright © 2013 Wiley Periodicals, Inc.

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.

3DRISM-HI-D2MSA: an improved analytic theory to compute solvent structure around hydrophobic solutes with proper treatment of solute–solvent electrostatic interactions

KAUST Repository

Cao, Siqin

2017-12-22

The 3D reference interaction site model (3DRISM) is a powerful tool to study the thermodynamic and structural properties of liquids. However, for hydrophobic solutes, the inhomogeneity of the solvent density around them poses a great challenge to the 3DRISM theory. To address this issue, we have previously introduced the hydrophobic-induced density inhomogeneity theory (HI) for purely hydrophobic solutes. To further consider the complex hydrophobic solutes containing partial charges, here we propose the D2MSA closure to incorporate the short-range and long-range interactions with the D2 closure and the mean spherical approximation, respectively. We demonstrate that our new theory can compute the solvent distributions around real hydrophobic solutes in water and complex organic solvents that agree well with the explicit solvent molecular dynamics simulations.

3DRISM-HI-D2MSA: an improved analytic theory to compute solvent structure around hydrophobic solutes with proper treatment of solute–solvent electrostatic interactions

KAUST Repository

Cao, Siqin; Zhu, Lizhe; Huang, Xuhui

2017-01-01

The 3D reference interaction site model (3DRISM) is a powerful tool to study the thermodynamic and structural properties of liquids. However, for hydrophobic solutes, the inhomogeneity of the solvent density around them poses a great challenge to the 3DRISM theory. To address this issue, we have previously introduced the hydrophobic-induced density inhomogeneity theory (HI) for purely hydrophobic solutes. To further consider the complex hydrophobic solutes containing partial charges, here we propose the D2MSA closure to incorporate the short-range and long-range interactions with the D2 closure and the mean spherical approximation, respectively. We demonstrate that our new theory can compute the solvent distributions around real hydrophobic solutes in water and complex organic solvents that agree well with the explicit solvent molecular dynamics simulations.

3DRISM-HI-D2MSA: an improved analytic theory to compute solvent structure around hydrophobic solutes with proper treatment of solute–solvent electrostatic interactions

Science.gov (United States)

Cao, Siqin; Zhu, Lizhe; Huang, Xuhui

2018-04-01

The 3D reference interaction site model (3DRISM) is a powerful tool to study the thermodynamic and structural properties of liquids. However, for hydrophobic solutes, the inhomogeneity of the solvent density around them poses a great challenge to the 3DRISM theory. To address this issue, we have previously introduced the hydrophobic-induced density inhomogeneity theory (HI) for purely hydrophobic solutes. To further consider the complex hydrophobic solutes containing partial charges, here we propose the D2MSA closure to incorporate the short-range and long-range interactions with the D2 closure and the mean spherical approximation, respectively. We demonstrate that our new theory can compute the solvent distributions around real hydrophobic solutes in water and complex organic solvents that agree well with the explicit solvent molecular dynamics simulations.

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

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...

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.

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.

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

Directory of Open Access Journals (Sweden)

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

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

Comparison of Exposure Controls, Item Pool Characteristics, and Population Distributions for CAT Using the Partial Credit Model

Science.gov (United States)

Lee, HwaYoung; Dodd, Barbara G.

2012-01-01

This study investigated item exposure control procedures under various combinations of item pool characteristics and ability distributions in computerized adaptive testing based on the partial credit model. Three variables were manipulated: item pool characteristics (120 items for each of easy, medium, and hard item pools), two ability…

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)

Still Struggling: Characteristics of Youth with OCD Who Are Partial Responders to Medication Treatment

Science.gov (United States)

Freeman, J.; Sapyta, J.; Garcia, A.; Fitzgerald, D.; Khanna, M.; Choate-Summers, M.; Moore, P.; Chrisman, A.; Haff, N.; Naeem, A.; March, J.; Franklin, M.

2011-01-01

The primary aim of this paper is to examine the characteristics of a large sample of youth with OCD who are partial responders (i.e., still have clinically significant symptoms) to serotonin reuptake inhibitor (SRI) medication. The sample will be described with regard to: demographics, treatment history, OCD symptoms/severity, family history and…

Study on the electromagnetic waves propagation characteristics in partially ionized plasma slabs

Directory of Open Access Journals (Sweden)

Zhi-Bin Wang

2016-05-01

Full Text Available Propagation characteristics of electromagnetic (EM waves in partially ionized plasma slabs are studied in this paper. Such features are significant to applications in plasma antennas, blackout of re-entry flying vehicles, wave energy injection to plasmas, and etc. We in this paper developed a theoretical model of EM wave propagation perpendicular to a plasma slab with a one-dimensional density inhomogeneity along propagation direction to investigate essential characteristics of EM wave propagation in nonuniform plasmas. Particularly, the EM wave propagation in sub-wavelength plasma slabs, where the geometric optics approximation fails, is studied and in comparison with thicker slabs where the geometric optics approximation applies. The influences of both plasma and collisional frequencies, as well as the width of the plasma slab, on the EM wave propagation characteristics are discussed. The results can help the further understanding of propagation behaviours of EM waves in nonuniform plasma, and applications of the interactions between EM waves and plasmas.

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.

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.

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.

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.

A multi-staining chip using hydrophobic valves for exfoliative cytology in cancer

Science.gov (United States)

Lee, Tae Hee; Bu, Jiyoon; Moon, Jung Eun; Kim, Young Jun; Kang, Yoon-Tae; Cho, Young-Ho; Kim, In Sik

2017-07-01

Exfoliative cytology is a highly established technique for the diagnosis of tumors. Various microfluidic devices have been developed to minimize the sample numbers by conjugating multiple antibodies in a single sample. However, the previous multi-staining devices require complex control lines and valves operated by external power sources, to deliver multiple antibodies separately for a single sample. In addition, most of these devices are composed of hydrophobic materials, causing unreliable results due to the non-specific binding of antibodies. Here, we present a multi-staining chip using hydrophobic valves, which is formed by the partial treatment of 2-hydroxyethyl methacrylate (HEMA). Our chip consists of a circular chamber, divided into six equal fan-shaped regions. Switchable injection ports are located at the center of the chamber and at the middle of the arc of each fan-shaped zone. Thus, our device is beneficial for minimizing the control lines, since pre-treatment solutions flow from the center to outer ports, while six different antibodies are introduced oppositely from the outer ports. Furthermore, hydrophobic narrow channels, connecting the central region and each of the six fan-shaped zones, are closed by capillary effect, thus preventing the fluidic mixing without external power sources. Meanwhile, HEMA treatment on the exterior region results in hydrophobic-to-hydrophilic transition and prevents the non-specific binding of antibodies. For the application, we measured the expression of six different antibodies in a single sample using our device. The expression levels of each antibody highly matched the conventional immunocytochemistry results. Our device enables cancer screening with a small number of antibodies for a single sample.

A multi-staining chip using hydrophobic valves for exfoliative cytology in cancer

International Nuclear Information System (INIS)

Lee, Tae Hee; Bu, Jiyoon; Kim, Young Jun; Kang, Yoon-Tae; Cho, Young-Ho; Moon, Jung Eun; Kim, In Sik

2017-01-01

Exfoliative cytology is a highly established technique for the diagnosis of tumors. Various microfluidic devices have been developed to minimize the sample numbers by conjugating multiple antibodies in a single sample. However, the previous multi-staining devices require complex control lines and valves operated by external power sources, to deliver multiple antibodies separately for a single sample. In addition, most of these devices are composed of hydrophobic materials, causing unreliable results due to the non-specific binding of antibodies. Here, we present a multi-staining chip using hydrophobic valves, which is formed by the partial treatment of 2-hydroxyethyl methacrylate (HEMA). Our chip consists of a circular chamber, divided into six equal fan-shaped regions. Switchable injection ports are located at the center of the chamber and at the middle of the arc of each fan-shaped zone. Thus, our device is beneficial for minimizing the control lines, since pre-treatment solutions flow from the center to outer ports, while six different antibodies are introduced oppositely from the outer ports. Furthermore, hydrophobic narrow channels, connecting the central region and each of the six fan-shaped zones, are closed by capillary effect, thus preventing the fluidic mixing without external power sources. Meanwhile, HEMA treatment on the exterior region results in hydrophobic-to-hydrophilic transition and prevents the non-specific binding of antibodies. For the application, we measured the expression of six different antibodies in a single sample using our device. The expression levels of each antibody highly matched the conventional immunocytochemistry results. Our device enables cancer screening with a small number of antibodies for a single sample. (paper)

Effect of increased surface hydrophobicity via drug conjugation on the clearance of inhaled PEGylated polylysine dendrimers.

Science.gov (United States)

Haque, Shadabul; McLeod, Victoria M; Jones, Seth; Fung, Sandy; Whittaker, Michael; McIntosh, Michelle; Pouton, Colin; Owen, David J; Porter, Christopher J H; Kaminskas, Lisa M

2017-10-01

PEGylated polylysine dendrimers are attractive and well tolerated inhalable drug delivery platforms that have the potential to control the release, absorption kinetics and lung retention time of conjugated drugs. The clinical application of these systems though, would likely require partial substitution of surface PEG groups with drug molecules that are anticipated to alter their lung clearance kinetics and clearance pathways. In the current study, we therefore evaluated the impact of increased surface hydrophobicity via substitution of 50% surface PEG groups with a model hydrophobic drug (α-carboxyl OtButylated methotrexate) on the lung clearance of a Generation 5 PEGylated polylysine dendrimer in rats. PEG substitution with OtBu-methotrexate accelerated lung clearance of the dendrimer by increasing polylysine scaffold catabolism, improving systemic absorption of the intact dendrimer and low molecular weight products of scaffold catabolism, and enhancing mucociliary clearance. These results suggest that the conjugation of hydrophobic drug on the surface of a PEGylated dendrimer is likely to accelerate lung clearance when compared to a fully PEGylated dendrimer. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

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.

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.

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

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.

Internal flow and evaporation characteristic inside a water droplet on a vertical vibrating hydrophobic surface

International Nuclear Information System (INIS)

Kim Hun; Lim, Hee Chang

2015-01-01

This study aims to understand the internal flow and the evaporation characteristics of a deionized water droplet subjected to vertical forced vibrations. To predict and evaluate its resonance frequency, the theories of Lamb, Strani, and Sabetta have been applied. To visualize the precise mode, shape, and internal flow inside a droplet, the experiment utilizes a combination of a high-speed camera, macro lens, and continuous laser. As a result, a water droplet on a hydrophobic surface has its typical shape at each mode, and complicated vortices are observed inside the droplet. In particular, large symmetrical flow streams are generated along the vertical axis at each mode, with a large circulating movement from the bottom to the top and then to the triple contact line along the droplet surface. In addition, a bifurcation-shaped flow pattern is formed at modes 2 and 4, whereas a large ellipsoid-shape flow pattern forms at modes 6 and 8. Mode 4 has the fastest internal flow speed and evaporation rate, followed by modes 8 then 6, with 2 having the slowest of these properties. Each mode has the fastest evaporation rate amongst its neighboring frequencies. Finally, the droplet evaporation under vertical vibration would lead to more rapid evaporation, particularly for mode 4

Internal flow and evaporation characteristic inside a water droplet on a vertical vibrating hydrophobic surface

Energy Technology Data Exchange (ETDEWEB)

Kim Hun; Lim, Hee Chang [School of Mechanical Engineering, Pusan National University, Busan (Korea, Republic of)

2015-07-15

This study aims to understand the internal flow and the evaporation characteristics of a deionized water droplet subjected to vertical forced vibrations. To predict and evaluate its resonance frequency, the theories of Lamb, Strani, and Sabetta have been applied. To visualize the precise mode, shape, and internal flow inside a droplet, the experiment utilizes a combination of a high-speed camera, macro lens, and continuous laser. As a result, a water droplet on a hydrophobic surface has its typical shape at each mode, and complicated vortices are observed inside the droplet. In particular, large symmetrical flow streams are generated along the vertical axis at each mode, with a large circulating movement from the bottom to the top and then to the triple contact line along the droplet surface. In addition, a bifurcation-shaped flow pattern is formed at modes 2 and 4, whereas a large ellipsoid-shape flow pattern forms at modes 6 and 8. Mode 4 has the fastest internal flow speed and evaporation rate, followed by modes 8 then 6, with 2 having the slowest of these properties. Each mode has the fastest evaporation rate amongst its neighboring frequencies. Finally, the droplet evaporation under vertical vibration would lead to more rapid evaporation, particularly for mode 4.

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.

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.

Load transfer characteristics of unilateral distal extension removable partial dentures with polyacetal resin supporting components.

Science.gov (United States)

Jiao, T; Chang, T; Caputo, A A

2009-03-01

To photoelastically examine load transfer by unilateral distal extension removable partial dentures with supporting and retentive components made of the lower stiffness polyacetal resins. A mandibular photoelastic model, with edentulous space distal to the right second premolar and missing the left first molar, was constructed to determine the load transmission characteristics of a unilateral distal extension base removable partial denture. Individual simulants were used for tooth structure, periodontal ligament, and alveolar bone. Three designs were fabricated: a major connector and clasps made from polyacetal resin, a metal framework as the major connector with polyacetal resin clasp and denture base, and a traditional metal framework I-bar removable partial denture. Simulated posterior bilateral and unilateral occlusal loads were applied to the removable partial dentures. Under bilateral and left side unilateral loading, the highest stress was observed adjacent to the left side posterior teeth with the polyacetal removable partial denture. The lowest stress was seen with the traditional metal framework. Unilateral loads on the right edentulous region produced similar distributed stress under the denture base with all three designs but a somewhat higher intensity with the polyacetal framework. The polyacetal resin removable partial denture concentrated the highest stresses to the abutment and the bone. The traditional metal framework I-bar removable partial denture most equitably distributed force. The hybrid design that combined a metal framework and polyacetal clasp and denture base may be a viable alternative when aesthetics are of primary concern.

Influence of Nanosilica Filler Content in LDPE Composites on Partial Discharge Characteristics

Institute of Scientific and Technical Information of China (English)

Z. Abdul-Malek; A.M. Azzin; Y.Z. Ariel; Aulia; K.Y. Lau; M. Jaafar

2011-01-01

Partial discharges （PDs） due to artificial void in samples of LDPE nanocomposite sheet have been investiga- ted in this work. PDs may cause the degradation of insulating materials and may affect the lifetime of high-voltage ap- paratus. An experimental work using sphere ball-plane electrode system （CIGRE Method II） and a 1.0 mm LDPE composite sheet was carried out. Different weight percentages of nanosilica （0%, 2%, 4%, 6% and 8%） were used. PD experimental results, such as PD magnitude and PD number （both PD pulse polarities）, as functions of the ap- plied stress duration at a specified applied voltage were compared. The surface morphology of specimens was also presented and this conforms to the PD findings. The experimental results show that the PD characteristics of the LDPE generally improve with the introduction of nanosilica, the composite with the highest content of filler, namely the 8% （wt） nanosilica sample has the least partial discharge activities.

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

Continuous Hydrolysis and Liquid–Liquid Phase Separation of an Active Pharmaceutical Ingredient Intermediate Using a Miniscale Hydrophobic Membrane Separator

DEFF Research Database (Denmark)

Cervera Padrell, Albert Emili; Morthensen, Sofie Thage; Lewandowski, Daniel Jacob

2012-01-01

Continuous hydrolysis of an active pharmaceutical ingredient intermediate, and subsequent liquid–liquid (L-L) separation of the resulting organic and aqueous phases, have been achieved using a simple PTFE tube reactor connected to a miniscale hydrophobic membrane separator. An alkoxide product......, obtained in continuous mode by a Grignard reaction in THF, reacted with acidic water to produce partially miscible organic and aqueous phases containing Mg salts. Despite the partial THF–water miscibility, the two phases could be separated at total flow rates up to 40 mL/min at different flow ratios, using...

Hydrophobic hydration of poly-N-isopropyl acrylamide: a matter of the mean energetic state of water

Science.gov (United States)

Bischofberger, I.; Calzolari, D. C. E.; de Los Rios, P.; Jelezarov, I.; Trappe, V.

2014-03-01

The enthalpically favoured hydration of hydrophobic entities, termed hydrophobic hydration, impacts the phase behaviour of numerous amphiphiles in water. Here, we show experimental evidence that hydrophobic hydration is strongly determined by the mean energetics of the aqueous medium. We investigate the aggregation and collapse of an amphiphilic polymer, poly-N-isopropyl acrylamide (PNiPAM), in aqueous solutions containing small amounts of alcohol and find that the thermodynamic characteristics defining the phase transitions of PNiPAM evolve relative to the solvent composition at which the excess mixing enthalpy of the water/alcohol mixtures becomes minimal. Such correlation between solvent energetics and solution thermodynamics extends to other mixtures containing neutral organic solutes that are considered as kosmotropes to induce a strengthening of the hydrogen bonded water network. This denotes the energetics of water as a key parameter controlling the phase behaviour of PNiPAM and identifies the excess mixing enthalpy of water/kosmotrope mixtures as a gauge of the kosmotropic effect on hydrophobic assemblies.

Measurement of partial discharge inception characteristics in sub-cooled liquid nitrogen

International Nuclear Information System (INIS)

Koo, J.Y.; Lee, S.H.; Shin, W.J.; Khan, Umer A.; Oh, S.H.; Seong, J.K.; Lee, B.W.

2011-01-01

We measured partial discharge and partial discharge initiation voltage of subcooled liquid nitrogen. Various kinds of test samples have been prepared. Sub-cooled temperature in liquid nitrogen were changed. The number of PD pluses were decreased when 68 K liquid nitrogen was used. Sub-cooled liquid nitrogen has positive effects to suppress PD activities. Partial discharge (PD) measurement is one of the effective diagnostic techniques to predict abnormal high voltage dielectric insulation conditions of the electric equipments. PD diagnostic techniques were also could be utilized to evaluate the conditions of cryogenic dielectric insulation media of high temperature superconducting electric equipment in liquid nitrogen. Generally, liquid nitrogen at 77 K is used as cryogenic and dielectric media for high temperature superconducting devices for high voltage electric power systems. But due to generation of bubbles during quench conditions which cause harmful effect on the properties of liquid nitrogen insulation, sub-cooled nitrogen under 77 K was also employed to suppress bubble formation. In this work, investigation of PD characteristics of sub-cooled liquid nitrogen was conducted in order to clarify the relation between PD inception and the temperature of liquid nitrogen. It was observed that measured PDIV (PD inception voltage) shows little differences according to the sub-cooled temperature of liquid nitrogen, but the magnitude and total numbers of PD has been slightly decreased according the decrease of cooled temperature of liquid nitrogen. From experimental results, it was deduced that the sub-cooled liquid nitrogen from 68 K to 77 K, could be applicable without any considerations of the variation of PDIV.

Facile Synthesis of Highly Hydrophobic Cellulose Nanoparticles through Post-Esterification Microfluidization

Directory of Open Access Journals (Sweden)

Chunxiang Lin

2018-04-01

Full Text Available A post-esterification with a high degree of substitution (hDS mechanical treatment (Pe(hDSM approach was used for the production of highly hydrophobic cellulose nanoparticles (CNPs. The process has the advantages of substantially reducing the mechanical energy input for the production of CNPs and avoiding CNP aggregation through drying or solvent exchange. A conventional esterification reaction was carried out using a mixture of acetic anhydride, acetic acid, and concentrated sulfuric acid, but at temperatures of 60–85 °C. The successful hDS esterification of bleached eucalyptus kraft pulp fibers was confirmed by a variety of techniques, such as Fourier transform infrared (FTIR, solid state 13C NMR, X-ray photoelectron spectroscopy (XPS, elemental analyses, and X-ray diffraction (XRD. The CNP morphology and size were examined by atomic force microscopy (AFM as well as dynamic light scattering. The hydrophobicity of the PeM-CNP was confirmed by the redispersion of freeze-dried CNPs into organic solvents and water contact-angle measurements. Finally, the partial conversion of cellulose I to cellulose II through esterification improved PeM-CNP thermal stability.

Improving the performances of hydrophobic catalysts used for tritium recovery and enrichment processes In liquid and gaseous effluents

International Nuclear Information System (INIS)

Popescu, Irina; Ionita, Gheorghe; Varlam, Carmen

2007-01-01

Full text: Based on the long experience of the authors in the preparation, testing and evaluation of the performances of hydrophobic catalysts and based also 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: (1) how to improve the characteristics and performance of platinum hydrophobic catalysts; (2) to assess and find a new procedure for the preparation of a new improved hydrophobic catalyst. From reviewed references it results that platinum appears to be the most active and efficient catalytic metal while polytetrafluoroethylene is the best wetproofing agent. A new improved hydrophobic Pt-catalyst has been obtained and tests are now underway. The main steps and experimental conditions of preparation are largely discussed. A new wetproofing agent and new binding agents (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 for improving the performance of conventional hydrophobic Pt-catalysts. (authors)

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

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

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

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

Partial molar volume of anionic polyelectrolytes in aqueous solution.

Science.gov (United States)

Salamanca, Constain; Contreras, Martín; Gamboa, Consuelo

2007-05-15

In this work the partial molar volumes (V) of different anionic polyelectrolytes and hydrophobically modified polyelectrolytes (PHM) were measured. Polymers like polymaleic acid-co-styrene, polymaleic acid-co-1-olefin, polymaleic acid-co-vinyl-2-pyrrolidone, and polyacrylic acid (abbreviated as MAS-n, PA-n-K2, AMVP, and PAA, respectively) were employed. These materials were investigated by density measurements in highly dilute aqueous solutions. The molar volume results allow us to discuss the effect of the carboxylic groups and the contributions from the comonomeric principal chain. The PAA presents the smaller V, while the largest V value was for AMVP. The V of PHM shows a linear relationship with the number of methylene groups in the lateral chain. It is found that the magnitude of the contribution per methylene group decreases as the hydrophobic character of the environment increases.

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...

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.

Partially acetylated sugarcane bagasse for wicking oil from contaminated wetlands

Energy Technology Data Exchange (ETDEWEB)

Chung, S. [Samsung Engineering Co. Ltd., R and D Center, Suwon, Gyeonggi (Korea, Republic of); Suidan, M.T. [University of Cincinnati, School of Energy, Environmental, Biological and Medical Engineering, Cincinnati, OH (United States); Venosa, A.D. [NRMRL, U.S. EPA, Cincinnati, OH (United States)

2011-12-15

Sugarcane bagasse was partially acetylated to enhance its oil-wicking ability in saturated environments while holding moisture for hydrocarbon biodegradation. The water sorption capacity of raw bagasse was reduced fourfold after treatment, which indicated considerably increased hydrophobicity but not a limited capability to hold moisture for hydrocarbon biodegradation. Characterization results by Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and surface area analyzer suggested that treated bagasse exhibited enhanced hydrophobicity and surface area. Oil wicking test results indicate that treated bagasse is more effective in wicking oil from highly saturated environments than raw bagasse and suggest that application of this material in remediation of oil spills in highly saturated wetlands is promising. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Hydrophobic Coatings on Cotton Obtained by in Situ Plasma Polymerization of a Fluorinated Monomer in Ethanol Solutions.

Science.gov (United States)

Molina, Ricardo; Teixidó, Josep Maria; Kan, Chi-Wai; Jovančić, Petar

2017-02-15

Plasma polymerization using hydrophobic monomers in the gas phase is a well-known technology to generate hydrophobic coatings. However, synthesis of functional hydrophobic coatings using plasma technology in liquids has not yet been accomplished. This work is consequently focused on polymerization of a liquid fluorinated monomer on cotton fabric initiated by atmospheric plasma in a dielectric barrier discharge configuration. Functional hydrophobic coatings on cotton were successfully achieved using in situ atmospheric plasma-initiated polymerization of fluorinated monomer dissolved in ethanol. Gravimetric measurements reveal that the amount of polymer deposited on cotton substrates can be modulated with the concentration of monomer in ethanol solution, and cross-linking reactions occur during plasma polymerization of a fluorinated monomer even without the presence of a cross-linking agent. FTIR and XPS analysis were used to study the chemical composition of hydrophobic coatings and to get insights into the physicochemical processes involved in plasma treatment. SEM analysis reveals that at high monomer concentration, coatings possess a three-dimensional pattern with a characteristic interconnected porous network structure. EDX analysis reveals that plasma polymerization of fluorinated monomers takes place preferentially at the surface of cotton fabric and negligible polymerization takes place inside the cotton fabric. Wetting time measurements confirm the hydrophobicity of cotton coatings obtained although equilibrium moisture content was slightly decreased. Additionally, the abrasion behavior and resistance to washing of plasma-coated cotton has been evaluated.

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.

Partial differential equations

CERN Document Server

Evans, Lawrence C

2010-01-01

This text gives a comprehensive survey of modern techniques in the theoretical study of partial differential equations (PDEs) with particular emphasis on nonlinear equations. The exposition is divided into three parts: representation formulas for solutions; theory for linear partial differential equations; and theory for nonlinear partial differential equations. Included are complete treatments of the method of characteristics; energy methods within Sobolev spaces; regularity for second-order elliptic, parabolic, and hyperbolic equations; maximum principles; the multidimensional calculus of variations; viscosity solutions of Hamilton-Jacobi equations; shock waves and entropy criteria for conservation laws; and, much more.The author summarizes the relevant mathematics required to understand current research in PDEs, especially nonlinear PDEs. While he has reworked and simplified much of the classical theory (particularly the method of characteristics), he primarily emphasizes the modern interplay between funct...

The Manipulation of Hydrophobicity in Catalyst Design for Applications of Aerobic Alcohols Oxidation and Electrocatalytic Water Oxidation

KAUST Repository

Chen, Batian

2016-01-01

Hydrophobicity is the generalized characteristic of non-polar substances that brings about their exclusion from aqueous phases. This property, entropic in its nature, drives key self-assembly and phase separation processes in water. Protein folding

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.

Comparing the Spectroscopic and Molecular Characteristics of Different Dissolved Organic Matter Fractions Isolated by Hydrophobic and Anionic Exchange Resins Using Fluorescence Spectroscopy and FT-ICR-MS

Directory of Open Access Journals (Sweden)

Morgane Derrien

2017-07-01

Full Text Available Despite the environmental significance of dissolved organic matter (DOM, characterizing DOM is still challenging due to its structural complexity and heterogeneity. In this study, three different chemical fractions, including hydrophobic acid (HPOA, transphilic acid (TPIA, and hydrophilic neutral and base (HPIN/B fractions, were separated from bulk aquatic DOM samples, and their spectral features and the chemical composition at the molecular level were compared using both fluorescence excitation emission matrix-parallel factor analysis (EEM-PARAFAC and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS. The HPIN/B fraction was distinguished from the two acidic fractions (i.e., HPOA and TPIA by the EEM-PARAFAC, while the TPIA fraction was discriminated by using the molecular parameters derived from the FT-ICR MS analyses. Statistical comparison suggests that the spectral dissimilarity among the three chemical fractions might result from the acido-basic properties of DOM samples, while the differences in molecular composition were more likely to be affected by the hydrophobicity of the DOM fractions. The non-metric multidimensional scaling map further revealed that the HPOA was the most heterogeneous among the three fractions. The number of overlapping formulas among the three chemical fractions constituted only <5% of all identified formulas, and those between two different fractions ranged from 2.0% to 24.1%, implying relatively homogeneous properties of the individual chemical fractions with respect to molecular composition. Although employing chemical fractionation achieved a lowering of the DOM heterogeneity, prevalent signatures of either acido-basic property or the hydrophobic nature of DOM on the characteristics of three chemical isolated fractions were not found for this study.

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

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 ...

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)

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)

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.

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.

Formation of hydrophobic coating on glass surface using atmospheric pressure non-thermal plasma in ambient air

International Nuclear Information System (INIS)

Fang, Z; Qiu, Y; Kuffel, E

2004-01-01

Non-thermal plasmas under atmospheric pressure are of great interest in material surface processing because of their convenience, effectiveness and low cost. In this paper, the treatment of a glass surface for improving hydrophobicity using a non-thermal plasma generated by a dielectric barrier corona discharge (DBCD) with a needle array-to-plane electrode arrangement in atmospheric air is conducted, and the surface properties of the glass before and after the DBCD treatment are studied using contact angle measurement, surface resistance measurement and the wet flashover voltage test. The effects of the plasma dose (the product of average discharge power and treatment time) of DBCD on the surface modification are studied, and the mechanism of interaction between the plasma and glass surface is discussed. It is found that a layer of hydrophobic coating is formed on the glass surface through DBCD treatment, and the improvement of hydrophobicity depends on the plasma dose of the DBCD. It seems that there is an optimum plasma dose for the surface treatment. The test results of thermal ageing and chemical ageing show that the hydrophobic layer has quite stable characteristics

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.

Clinical Characteristics and Low Vision Rehabilitation Methods for Partially Sighted School-Age Children.

Science.gov (United States)

Özen Tunay, Zuhal; Çalışkan, Deniz; İdil, Aysun; Öztuna, Derya

2016-04-01

To determine the clinical features and the distribution of diagnosis in partially sighted school-age children, to report the chosen low vision rehabilitation methods and to emphasize the importance of low vision rehabilitation. The study included 150 partially sighted children between the ages of 6 and 18 years. The distribution of diagnosis, accompanying ocular findings, visual acuity of the children both for near and distance with and without low vision devices, and the methods of low vision rehabilitation (for distance and for near) were determined. The demographic characteristics of the children and the parental consanguinity were recorded. The mean age of children was 10.6 years and the median age was 10 years; 88 (58.7%) of them were male and 62 (41.3%) of them were female. According to distribution of diagnoses among the children, the most frequent diagnosis was hereditary fundus dystrophies (36%) followed by cortical visual impairment (18%). The most frequently used rehabilitation methods were: telescopic lenses (91.3%) for distance vision; magnifiers (38.7%) and telemicroscopic systems (26.0%) for near vision. A significant improvement in visual acuity both for distance and near vision were determined with low vision aids. A significant improvement in visual acuity can be achieved both for distance and near vision with low vision rehabilitation in partially sighted school-age children. It is important for ophthalmologists and pediatricians to guide parents and children to low vision rehabilitation.

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)

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...

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.

Assessment of water droplet evaporation mechanisms on hydrophobic and superhydrophobic substrates.

Science.gov (United States)

Pan, Zhenhai; Dash, Susmita; Weibel, Justin A; Garimella, Suresh V

2013-12-23

Evaporation rates are predicted and important transport mechanisms identified for evaporation of water droplets on hydrophobic (contact angle ~110°) and superhydrophobic (contact angle ~160°) substrates. Analytical models for droplet evaporation in the literature are usually simplified to include only vapor diffusion in the gas domain, and the system is assumed to be isothermal. In the comprehensive model developed in this study, evaporative cooling of the interface is accounted for, and vapor concentration is coupled to local temperature at the interface. Conjugate heat and mass transfer are solved in the solid substrate, liquid droplet, and surrounding gas. Buoyancy-driven convective flows in the droplet and vapor domains are also simulated. The influences of evaporative cooling and convection on the evaporation characteristics are determined quantitatively. The liquid-vapor interface temperature drop induced by evaporative cooling suppresses evaporation, while gas-phase natural convection acts to enhance evaporation. While the effects of these competing transport mechanisms are observed to counterbalance for evaporation on a hydrophobic surface, the stronger influence of evaporative cooling on a superhydrophobic surface accounts for an overprediction of experimental evaporation rates by ~20% with vapor diffusion-based models. The local evaporation fluxes along the liquid-vapor interface for both hydrophobic and superhydrophobic substrates are investigated. The highest local evaporation flux occurs at the three-phase contact line region due to proximity to the higher temperature substrate, rather than at the relatively colder droplet top; vapor diffusion-based models predict the opposite. The numerically calculated evaporation rates agree with experimental results to within 2% for superhydrophobic substrates and 3% for hydrophobic substrates. The large deviations between past analytical models and the experimental data are therefore reconciled with the

Epitope mapping of imidazolium cations in ionic liquid-protein interactions unveils the balance between hydrophobicity and electrostatics towards protein destabilisation.

Science.gov (United States)

Silva, Micael; Figueiredo, Angelo Miguel; Cabrita, Eurico J

2014-11-14

We investigated imidazolium-based ionic liquid (IL) interactions with human serum albumin (HSA) to discern the level of cation interactions towards protein stability. STD-NMR spectroscopy was used to observe the imidazolium IL protons involved in direct binding and to identify the interactions responsible for changes in Tm as accessed by differential scanning calorimetry (DSC). Cations influence protein stability less than anions but still significantly. It was found that longer alkyl side chains of imidazolium-based ILs (more hydrophobic) are associated with a higher destabilisation effect on HSA than short-alkyl groups (less hydrophobic). The reason for such destabilisation lies on the increased surface contact area of the cation with the protein, particularly on the hydrophobic contacts promoted by the terminus of the alkyl chain. The relevance of the hydrophobic contacts is clearly demonstrated by the introduction of a polar moiety in the alkyl chain: a methoxy or alcohol group. Such structural modification reduces the degree of hydrophobic contacts with HSA explaining the lesser extent of protein destabilisation when compared to longer alkyl side chain groups: above [C2mim](+). Competition STD-NMR experiments using [C2mim](+), [C4mim](+) and [C2OHmim](+) also validate the importance of the hydrophobic interactions. The combined effect of cation and anion interactions was explored using (35)Cl NMR. Such experiments show that the nature of the cation has no influence on the anion-protein contacts, still the nature of the anion modulates the cation-protein interaction. Herein we propose that more destabilising anions are likely to be a result of a partial contribution from the cation as a direct consequence of the different levels of interaction (cation-anion pair and cation-protein).

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.

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.

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.

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.

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.

On the Feasibility of Gap Detection of Power Transformer Partial Discharge UHF Signals: Gap Propagation Characteristics of Electromagnetic Waves

OpenAIRE

Xiaoxing Zhang; Guozhi Zhang; Yalong Li; Jian Zhang; Rui Huang

2017-01-01

This study analyzed the transformer electromagnetic gap propagation characteristics. The influence of gap size is also analyzed, and the results experimentally verified. The obtained results indicated that the gap propagation characteristics of electromagnetic wave signals radiated by the partial discharge (PD) source in different directions are substantially different. The intensity of the electromagnetic wave in the gap reaches a maximum at a gap height of 1 cm; and inside the gap, the inte...

In-line gas chromatographic apparatus for measuring the hydrophobic micropore volume (HMV) and contaminant transformation in mineral micropores

Energy Technology Data Exchange (ETDEWEB)

Cheng Hefa [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Reinhard, Martin, E-mail: reinhard@stanford.edu [Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305-4020 (United States)

2010-07-15

Desorption of hydrophobic organic compounds from micropores is characteristically slow compared to surface adsorption and partitioning. The slow-desorbing mass of a hydrophobic probe molecule can be used to calculate the hydrophobic micropore volume (HMV) of microporous solids. A gas chromatographic apparatus is described that allows characterization of the sorbed mass with respect to the desorption rate. The method is demonstrated using a dealuminated zeolite and an aquifer sand as the model and reference sorbents, respectively, and trichloroethylene (TCE) as the probe molecule. A glass column packed with the microporous sorbent is coupled directly to a gas chromatograph that is equipped with flame ionization and electron capture detectors. Sorption and desorption of TCE on the sorbent was measured by sampling the influent and effluent of the column using a combination of switching and injection valves. For geosorbents, the HMV is quantified based on Gurvitsch's rule from the mass of TCE desorbed at a rate that is characteristic for micropores. Instrumental requirements, design considerations, hardware details, detector calibration, performance, and data analysis are discussed along with applications. The method is novel and complements traditional vacuum gravimetric and piezometric techniques, which quantify the total pore volume under vacuum conditions. The HMV is more relevant than the total micropore volume for predicting the fate and transport of organic contaminants in the subsurface. Sorption in hydrophobic micropores strongly impacts the mobility of organic contaminants, and their chemical and biological transformations. The apparatus can serve as a tool for characterizing microprous solids and investigating contaminant-solid interactions.

In-line gas chromatographic apparatus for measuring the hydrophobic micropore volume (HMV) and contaminant transformation in mineral micropores

International Nuclear Information System (INIS)

Cheng Hefa; Reinhard, Martin

2010-01-01

Desorption of hydrophobic organic compounds from micropores is characteristically slow compared to surface adsorption and partitioning. The slow-desorbing mass of a hydrophobic probe molecule can be used to calculate the hydrophobic micropore volume (HMV) of microporous solids. A gas chromatographic apparatus is described that allows characterization of the sorbed mass with respect to the desorption rate. The method is demonstrated using a dealuminated zeolite and an aquifer sand as the model and reference sorbents, respectively, and trichloroethylene (TCE) as the probe molecule. A glass column packed with the microporous sorbent is coupled directly to a gas chromatograph that is equipped with flame ionization and electron capture detectors. Sorption and desorption of TCE on the sorbent was measured by sampling the influent and effluent of the column using a combination of switching and injection valves. For geosorbents, the HMV is quantified based on Gurvitsch's rule from the mass of TCE desorbed at a rate that is characteristic for micropores. Instrumental requirements, design considerations, hardware details, detector calibration, performance, and data analysis are discussed along with applications. The method is novel and complements traditional vacuum gravimetric and piezometric techniques, which quantify the total pore volume under vacuum conditions. The HMV is more relevant than the total micropore volume for predicting the fate and transport of organic contaminants in the subsurface. Sorption in hydrophobic micropores strongly impacts the mobility of organic contaminants, and their chemical and biological transformations. The apparatus can serve as a tool for characterizing microprous solids and investigating contaminant-solid interactions.

In-line gas chromatographic apparatus for measuring the hydrophobic micropore volume (HMV) and contaminant transformation in mineral micropores.

Science.gov (United States)

Cheng, Hefa; Reinhard, Martin

2010-07-15

Desorption of hydrophobic organic compounds from micropores is characteristically slow compared to surface adsorption and partitioning. The slow-desorbing mass of a hydrophobic probe molecule can be used to calculate the hydrophobic micropore volume (HMV) of microporous solids. A gas chromatographic apparatus is described that allows characterization of the sorbed mass with respect to the desorption rate. The method is demonstrated using a dealuminated zeolite and an aquifer sand as the model and reference sorbents, respectively, and trichloroethylene (TCE) as the probe molecule. A glass column packed with the microporous sorbent is coupled directly to a gas chromatograph that is equipped with flame ionization and electron capture detectors. Sorption and desorption of TCE on the sorbent was measured by sampling the influent and effluent of the column using a combination of switching and injection valves. For geosorbents, the HMV is quantified based on Gurvitsch's rule from the mass of TCE desorbed at a rate that is characteristic for micropores. Instrumental requirements, design considerations, hardware details, detector calibration, performance, and data analysis are discussed along with applications. The method is novel and complements traditional vacuum gravimetric and piezometric techniques, which quantify the total pore volume under vacuum conditions. The HMV is more relevant than the total micropore volume for predicting the fate and transport of organic contaminants in the subsurface. Sorption in hydrophobic micropores strongly impacts the mobility of organic contaminants, and their chemical and biological transformations. The apparatus can serve as a tool for characterizing microporous solids and investigating contaminant-solid interactions. 2010 Elsevier B.V. All rights reserved.

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.

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.

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.

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.

Beginning partial differential equations

CERN Document Server

O'Neil, Peter V

2011-01-01

A rigorous, yet accessible, introduction to partial differential equations-updated in a valuable new edition Beginning Partial Differential Equations, Second Edition provides a comprehensive introduction to partial differential equations (PDEs) with a special focus on the significance of characteristics, solutions by Fourier series, integrals and transforms, properties and physical interpretations of solutions, and a transition to the modern function space approach to PDEs. With its breadth of coverage, this new edition continues to present a broad introduction to the field, while also addres

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

Personality characteristics and their connection with learning efficiency of deaf and partially deaf pupils in mainstream primary and secondary school

OpenAIRE

Kastelic, Helena

2012-01-01

This thesis deals with personality characteristics and their connection with learning efficiency of deaf and partially deaf pupils and students in mainstream primary and secondary school. The theoretical part defines learning efficiency and focuses on the most significant factors of learning efficiency, including also personality characteristics of an individual. This thesis represents the idea of inclusion and its advantages and disadvantages and suggests to what extent it is present in our ...

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

Optimization of linear and branched alkane interactions with water to simulate hydrophobic hydration

Science.gov (United States)

Ashbaugh, Henry S.; Liu, Lixin; Surampudi, Lalitanand N.

2011-08-01

Previous studies of simple gas hydration have demonstrated that the accuracy of molecular simulations at capturing the thermodynamic signatures of hydrophobic hydration is linked both to the fidelity of the water model at replicating the experimental liquid density at ambient pressure and an accounting of polarization interactions between the solute and water. We extend those studies to examine alkane hydration using the transferable potentials for phase equilibria united-atom model for linear and branched alkanes, developed to reproduce alkane phase behavior, and the TIP4P/2005 model for water, which provides one of the best descriptions of liquid water for the available fixed-point charge models. Alkane site/water oxygen Lennard-Jones cross interactions were optimized to reproduce the experimental alkane hydration free energies over a range of temperatures. The optimized model reproduces the hydration free energies of the fitted alkanes with a root mean square difference between simulation and experiment of 0.06 kcal/mol over a wide temperature range, compared to 0.44 kcal/mol for the parent model. The optimized model accurately reproduces the temperature dependence of hydrophobic hydration, as characterized by the hydration enthalpies, entropies, and heat capacities, as well as the pressure response, as characterized by partial molar volumes.

Mechanical strength and hydrophobicity of cotton fabric after SF6 plasma treatment

Science.gov (United States)

Kamlangkla, K.; Paosawatyanyong, B.; Pavarajarn, V.; Hodak, Jose H.; Hodak, Satreerat K.

2010-08-01

Surface treatments to tailor fabric properties are in high demand by the modern garment industry. We studied the effect of radio-frequency inductively coupled SF plasma on the surface characteristics of cotton fabric. The duration of the treatment and the SF pressure were varied systematically. We measured the hydrophobicity of treated cotton as a function of storage time and washing cycles. We used the weight loss (%) along with the etching rate, the tensile strength, the morphology changes and the hydrophobicity of the fabric as observables after treatments with different plasma conditions. The weight loss remains below 1% but it significantly increases when the treatment time is longer than 5 min. Substantial changes in the surface morphology of the fiber are concomitant with the increased etching rate and increased weight loss with measurable consequences in their mechanical characteristics. The measured water absorption time reaches the maximum of 210 min when the SF pressure is higher than 0.3 Torr. The water contact angle ( 149°) and the absorption time (210 min) of cotton treated with extreme conditions appear to be durable as long as the fabric is not washed. X-ray photoelectron spectroscopy analysis reveals that the water absorption time of the fabric follows the same increasing trend as the fluorine/carbon ratio at the fabric surface and atom density of fluorine measured by Ar actinometer.

Mechanical strength and hydrophobicity of cotton fabric after SF6 plasma treatment

International Nuclear Information System (INIS)

Kamlangkla, K.; Paosawatyanyong, B.; Pavarajarn, V.; Hodak, Jose H.; Hodak, Satreerat K.

2010-01-01

Surface treatments to tailor fabric properties are in high demand by the modern garment industry. We studied the effect of radio-frequency inductively coupled SF 6 plasma on the surface characteristics of cotton fabric. The duration of the treatment and the SF 6 pressure were varied systematically. We measured the hydrophobicity of treated cotton as a function of storage time and washing cycles. We used the weight loss (%) along with the etching rate, the tensile strength, the morphology changes and the hydrophobicity of the fabric as observables after treatments with different plasma conditions. The weight loss remains below 1% but it significantly increases when the treatment time is longer than 5 min. Substantial changes in the surface morphology of the fiber are concomitant with the increased etching rate and increased weight loss with measurable consequences in their mechanical characteristics. The measured water absorption time reaches the maximum of 210 min when the SF 6 pressure is higher than 0.3 Torr. The water contact angle (149 deg.) and the absorption time (210 min) of cotton treated with extreme conditions appear to be durable as long as the fabric is not washed. X-ray photoelectron spectroscopy analysis reveals that the water absorption time of the fabric follows the same increasing trend as the fluorine/carbon ratio at the fabric surface and atom density of fluorine measured by Ar actinometer.

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.

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...

Partial Epilepsy with Auditory Features

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J Gordon Millichap

2004-07-01

Full Text Available The clinical characteristics of 53 sporadic (S cases of idiopathic partial epilepsy with auditory features (IPEAF were analyzed and compared to previously reported familial (F cases of autosomal dominant partial epilepsy with auditory features (ADPEAF in a study at the University of Bologna, Italy.

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.

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...

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

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.

Extruded black gram flour: Partial substitute for improving quality characteristics of Indian traditional snack

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Laxmi Ananthanarayan

2018-03-01

Full Text Available Background: During extrusion of black gram flour, formation of amylose-lipid complexes lowers down the gelatinization enthalpy of extrudates, and the partially gelatinized black gram starch leads to lowering down the water-holding capacity and alters functional properties resulting in changing quality attributes of the end product on frying/microwaving/roasting. Methods: Attempts have been made to improve the quality of an Indian traditional snack (e.g., papad by incorporating extruded black gram flour as partial substitute for raw (unextruded black gram flour. In present work, overall quality improvement was achieved by analyzing prefrying and postfrying characteristics (diameter, moisture content, expansion ratio, oil uptake, texture, and color of papad and physical properties (color and viscosity of fried oil. Results: Four different papad samples were prepared (control papads without addition of papadkhar, papads with use of 3% papadkhar, papads with incorporation of extruded black gram flour at 25% concentration, papads with incorporation of extruded black gram flour at 50% concentration along with 1% papadkhar and analyzed along standard market sample. Incorporation of extruded black gram flour in papad resulted in greater expansion with less oil uptake in fried papad. Further addition of extruded black gram flour permitted the use of lower concentration of papadkhar. After frying, the quality of oil was characterized after numerous frying cycles. Conclusion: Oil used for frying of papads containing highest concentration of papadkhar was effective only up to two frying cycles, after which color and viscosity increased significantly, adversely affecting the quality of fried oil. Keywords: Black gram flour, Extrusion, Prefrying and postfrying characteristics of papad, Quality of fried oil

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

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.

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.

Hydrophobic durability characteristics of butterfly wing surface after freezing cycles towards the design of nature inspired anti-icing surfaces.

Directory of Open Access Journals (Sweden)

Tingkun Chen

Full Text Available The hydrophobicity and anti-icing performance of the surfaces of some artificial hydrophobic coatings degraded after several icing and de-icing cycles. In this paper, the frost formation on the surfaces of butterfly wings from ten different species was observed, and the contact angles were measured after 0 to 6 frosting/defrosting cycles. The results show that no obvious changes in contact angle for the butterfly wing specimens were not obvious during the frosting/defrosting process. Further, the conclusion was inferred that the topography of the butterfly wing surface forms a special space structure which has a larger space inside that can accommodate more frozen droplets; this behavior prevents destruction of the structure. The findings of this study may provide a basis and new concepts for the design of novel industrially important surfaces to inhibit frost/ice growth, such as durable anti-icing coatings, which may decrease or prevent the socio-economic loss.

Hydrophobic durability characteristics of butterfly wing surface after freezing cycles towards the design of nature inspired anti-icing surfaces.

Science.gov (United States)

Chen, Tingkun; Cong, Qian; Qi, Yingchun; Jin, Jingfu; Choy, Kwang-Leong

2018-01-01

The hydrophobicity and anti-icing performance of the surfaces of some artificial hydrophobic coatings degraded after several icing and de-icing cycles. In this paper, the frost formation on the surfaces of butterfly wings from ten different species was observed, and the contact angles were measured after 0 to 6 frosting/defrosting cycles. The results show that no obvious changes in contact angle for the butterfly wing specimens were not obvious during the frosting/defrosting process. Further, the conclusion was inferred that the topography of the butterfly wing surface forms a special space structure which has a larger space inside that can accommodate more frozen droplets; this behavior prevents destruction of the structure. The findings of this study may provide a basis and new concepts for the design of novel industrially important surfaces to inhibit frost/ice growth, such as durable anti-icing coatings, which may decrease or prevent the socio-economic loss.

Partial discharge characteristics of polymer nanocomposite materials in electrical insulation: a review of sample preparation techniques, analysis methods, potential applications, and future trends.

Science.gov (United States)

Izzati, Wan Akmal; Arief, Yanuar Z; Adzis, Zuraimy; Shafanizam, Mohd

2014-01-01

Polymer nanocomposites have recently been attracting attention among researchers in electrical insulating applications from energy storage to power delivery. However, partial discharge has always been a predecessor to major faults and problems in this field. In addition, there is a lot more to explore, as neither the partial discharge characteristic in nanocomposites nor their electrical properties are clearly understood. By adding a small amount of weight percentage (wt%) of nanofillers, the physical, mechanical, and electrical properties of polymers can be greatly enhanced. For instance, nanofillers in nanocomposites such as silica (SiO2), alumina (Al2O3) and titania (TiO2) play a big role in providing a good approach to increasing the dielectric breakdown strength and partial discharge resistance of nanocomposites. Such polymer nanocomposites will be reviewed thoroughly in this paper, with the different experimental and analytical techniques used in previous studies. This paper also provides an academic review about partial discharge in polymer nanocomposites used as electrical insulating material from previous research, covering aspects of preparation, characteristics of the nanocomposite based on experimental works, application in power systems, methods and techniques of experiment and analysis, and future trends.

Analyzing the Molecular Kinetics of Water Spreading on Hydrophobic Surfaces via Molecular Dynamics Simulation.

Science.gov (United States)

Zhao, Lei; Cheng, Jiangtao

2017-09-07

In this paper, we report molecular kinetic analyses of water spreading on hydrophobic surfaces via molecular dynamics simulation. The hydrophobic surfaces are composed of amorphous polytetrafluoroethylene (PTFE) with a static contact angle of ~112.4° for water. On the basis of the molecular kinetic theory (MKT), the influences of both viscous damping and solid-liquid retarding were analyzed in evaluating contact line friction, which characterizes the frictional force on the contact line. The unit displacement length on PTFE was estimated to be ~0.621 nm and is ~4 times as long as the bond length of C-C backbone. The static friction coefficient was found to be ~[Formula: see text] Pa·s, which is on the same order of magnitude as the dynamic viscosity of water, and increases with the droplet size. A nondimensional number defined by the ratio of the standard deviation of wetting velocity to the characteristic wetting velocity was put forward to signify the strength of the inherent contact line fluctuation and unveil the mechanism of enhanced energy dissipation in nanoscale, whereas such effect would become insignificant in macroscale. Moreover, regarding a liquid droplet on hydrophobic or superhydrophobic surfaces, an approximate solution to the base radius development was derived by an asymptotic expansion approach.

Statistical Analysis of Partial Discharge Characteristics in Transformer Oil at the “Point-Plane” Electrode at Alternating Voltage

Directory of Open Access Journals (Sweden)

Korobeynikov S.M.

2017-08-01

Full Text Available In this paper, we consider the problems related to measuring and analyzing the characteristics of partial discharges which are the main instrument for oil-filled high-voltage electrical equipment diagnosing. The experiments on recording of partial discharges in transformer oil have been carried out in the “point-plane” electrode system at alternating current. The instantaneous voltage and the apparent charge have been measured depending on the root-mean-square voltage and the phase angle of partial discharges. This paper aimes at carrying out a statistical analysis of the obtained experimental results, in particular, the construction of a parametric probabilistic model of the dependence of the partial discharge inception voltage distribution on the value of the root-mean-square voltage. It differs from usual discharges which occur in liquid dielectric materials in case of sharp inhomogeneous electrode system. It has been suggested that discharges of a different type are the discharges in gas bubbles that occur when partial discharges in a liquid emerge. This assumption is confirmed by the fact that the number of such discharges increases with increasing the root-mean-square voltage value. It is the main novelty of this paper. This corresponds to the nature of the occurrence of such discharges. After rejecting the observations corresponding to discharges in gas bubbles, a parametric probabilistic model has been constructed. The model obtained makes it possible to determine the probability of partial discharge occurrence in a liquid at a given value of the instantaneous voltage depending on the root-mean-square voltage.

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”.

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.

Polybiguanide (PHMB) loaded in PLA scaffolds displaying high hydrophobic, biocompatibility and antibacterial properties

Energy Technology Data Exchange (ETDEWEB)

Llorens, Elena; Calderón, Silvia [Departament d' Enginyeria Química, Universitat Politècnica de Catalunya, Av. Diagonal 647, Barcelona E-08028 (Spain); Valle, Luis J. del, E-mail: luis.javier.del.valle@upc.edu [Departament d' Enginyeria Química, Universitat Politècnica de Catalunya, Av. Diagonal 647, Barcelona E-08028 (Spain); Puiggalí, Jordi [Departament d' Enginyeria Química, Universitat Politècnica de Catalunya, Av. Diagonal 647, Barcelona E-08028 (Spain); Center for Research in Nano-Engineering (CrNE), Universitat Politècnica de Catalunya, Edifici C, C/Pasqual i Vila s/n, Barcelona E-08028 (Spain)

2015-05-01

Polyhexamethylenebiguanide hydrochloride (PHMB), a low molecular weight polymer related to chlorohexidine (CHX), is a well-known antibacterial agent. In this study, polylactide (PLA) nanofibers loaded with PHMB were produced by electrospinning to obtain 3D biodegradable scaffolds with antibacterial properties. PLA fibers loaded with CHX were used as control. The electrospun fibers were studied and analyzed by SEM, FTIR, DSC and contact angle measurements. PHMB and CHX release from loaded scaffolds was evaluated, as well as their antibacterial activity and biocompatibility. The results showed that the nanofibers became smoother and their diameter smaller with increasing the amount of loaded PHMB. This feature led to an increase of both surface roughness and hydrophobicity of the scaffold. PHMB release was highly dependent on the hydrophilicity of the medium and differed from that determined for CHX. Lastly, PHMB-loaded PLA scaffolds showed antibacterial properties since they inhibited adhesion and bacterial growth, and exhibited biocompatible characteristics for the adhesion and proliferation of both fibroblast and epithelial cell lines. - Highlights: • Nanofibers of PLA-PHMB (antibacterial polymer) were prepared by electrospinning. • PHMB has hydrophilic character but the PLA-PHMB scaffolds were highly hydrophobic. • The high-hydrophobicity of the new scaffolds conditioned the release of PHMB. • The controlled release of PHMB inhibited the growth and bacterial adhesion. • PLA-PHMB scaffolds have biocompatibility with fibroblast and epithelial cells.

Polybiguanide (PHMB) loaded in PLA scaffolds displaying high hydrophobic, biocompatibility and antibacterial properties

International Nuclear Information System (INIS)

Llorens, Elena; Calderón, Silvia; Valle, Luis J. del; Puiggalí, Jordi

2015-01-01

Polyhexamethylenebiguanide hydrochloride (PHMB), a low molecular weight polymer related to chlorohexidine (CHX), is a well-known antibacterial agent. In this study, polylactide (PLA) nanofibers loaded with PHMB were produced by electrospinning to obtain 3D biodegradable scaffolds with antibacterial properties. PLA fibers loaded with CHX were used as control. The electrospun fibers were studied and analyzed by SEM, FTIR, DSC and contact angle measurements. PHMB and CHX release from loaded scaffolds was evaluated, as well as their antibacterial activity and biocompatibility. The results showed that the nanofibers became smoother and their diameter smaller with increasing the amount of loaded PHMB. This feature led to an increase of both surface roughness and hydrophobicity of the scaffold. PHMB release was highly dependent on the hydrophilicity of the medium and differed from that determined for CHX. Lastly, PHMB-loaded PLA scaffolds showed antibacterial properties since they inhibited adhesion and bacterial growth, and exhibited biocompatible characteristics for the adhesion and proliferation of both fibroblast and epithelial cell lines. - Highlights: • Nanofibers of PLA-PHMB (antibacterial polymer) were prepared by electrospinning. • PHMB has hydrophilic character but the PLA-PHMB scaffolds were highly hydrophobic. • The high-hydrophobicity of the new scaffolds conditioned the release of PHMB. • The controlled release of PHMB inhibited the growth and bacterial adhesion. • PLA-PHMB scaffolds have biocompatibility with fibroblast and epithelial cells

Partial ablation of uropygial gland effect on carcass characteristics of Akar Putra chicken.

Science.gov (United States)

Jawad, Hasan S A; Idris, L H; Bakar, Z B; Kassim, A B

2016-08-01

This study evaluated the effect of partial uropygialectomy (PU) on carcass traits of male and female Akar Putra chickens. Sixty chicks of each sex were evenly distributed into 5 treatment groups with 3 replicates per group containing 4 males and 4 females each, and reared for 12 wk. Homogeneity of the groups was satisfied with regard to the parity. Experimental treatments consisted of a control treatment (T1), and partial ablation of the uropygial gland was applied on the second, third, fourth, and fifth treatments at 3, 4, 5, and 6 wk of age, respectively. The chickens were fed ad libitum the same diets (1 to 13 d: starter; 14 d to slaughter: finisher). On the last d of the experiment, 12 birds were randomly selected from each treatment group (2 males and 2 females per replicate) and slaughtered to determine carcass characteristics, which included carcass weight, dressing percentage with or without eating giblets, and the relative weights of heart, liver, gizzard, thighs, wings, breast, back, and neck. From the results of the study, it was shown that the partial ablation of the uropygial gland at all ages had certain dependent effects concerning some carcass parameters, as shown by higher breast and back relative weights in males and breast relative weight in females. As a consequence, a positive effect also was noticed regarding the carcass morphology in terms of the increase in dressing percentage with or without eating giblets thus leading to an increase in the body weight and carcass weight. Furthermore, the best result was obtained in the second treatment when PU was applied at 3 wk of age compared with other experimental groups. Moreover, the current study provides a novel and economic alternative to enhance the body performance of poultry in general and Akar Putra chicken particularly. © 2016 Poultry Science Association Inc.

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

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.

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

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.

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.

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.

A hydrophobic organelle probe based on aggregation-induced emission: Nanosuspension preparation and direct use for endoplasmic reticulum imaging in living cells

Science.gov (United States)

Zheng, Sichao; Huang, Cuihong; Zhao, Xuyan; Zhang, Yong; Liu, Shuwen; Zhu, Qiuhua

2018-01-01

Organic fluorophores have a wide range of biological uses and are usually needed to be prepared as water-soluble compounds or nanoparticles for applications in aqueous biosystems owing to their hydrophobic properties, which often is a complex, time-consuming and high-cost process. Here, the nanoparticle preparation of hydrophobic fluorophores and their application in cell imaging have been investigated. It was found: a) fetal bovine serum (FBS) shows an excellent dispersion effect on hydrophobic small-molecule organic compounds; b) a hydrophobic C6-unsubstituted tetrahydropyrimidine (Me-THP-Naph) can be prepared as nanosuspensions utilizing cell culture medium with 10% FBS and directly be used as a specific real-time imaging probe for the endoplasmic reticulum (ER), a dynamic organelle playing a crucial role in many cellular processes. Compared with existing ER-targeted organic fluorescent probes, Me-THP-Naph, a product of an efficient five-component reaction that we developed, has unconventional aggregation-induced emission characteristics and shows advantages of low cost, long-term staining, good photostability, high signal-to-noise ratio and excellent biocompatibility, which make it a potential specific probe for real-time ER imaging. More importantly, this work affords a simple strategy for direct application of hydrophobic organic compounds in aqueous biological systems.

Mechanical strength and hydrophobicity of cotton fabric after SF{sub 6} plasma treatment

Energy Technology Data Exchange (ETDEWEB)

Kamlangkla, K. [Nanoscience and Nanotechnology Program, Center of Innovative Nanotechnology, Chulalongkorn University, Bangkok 10330 (Thailand); Paosawatyanyong, B. [Department of Physics, Faculty of Science, Chulalongkorn University, and ThEP Center, Commission on Higher Education, Bangkok 10330 (Thailand); Pavarajarn, V. [Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330 (Thailand); Hodak, Jose H. [Department of Physics, Faculty of Science, Mahidol University, Bangkok 10400 (Thailand); Hodak, Satreerat K., E-mail: Satreerat.H@Chula.ac.th [Department of Physics, Faculty of Science, Chulalongkorn University, and ThEP Center, Commission on Higher Education, Bangkok 10330 (Thailand)

2010-08-01

Surface treatments to tailor fabric properties are in high demand by the modern garment industry. We studied the effect of radio-frequency inductively coupled SF{sub 6} plasma on the surface characteristics of cotton fabric. The duration of the treatment and the SF{sub 6} pressure were varied systematically. We measured the hydrophobicity of treated cotton as a function of storage time and washing cycles. We used the weight loss (%) along with the etching rate, the tensile strength, the morphology changes and the hydrophobicity of the fabric as observables after treatments with different plasma conditions. The weight loss remains below 1% but it significantly increases when the treatment time is longer than 5 min. Substantial changes in the surface morphology of the fiber are concomitant with the increased etching rate and increased weight loss with measurable consequences in their mechanical characteristics. The measured water absorption time reaches the maximum of 210 min when the SF{sub 6} pressure is higher than 0.3 Torr. The water contact angle (149 deg.) and the absorption time (210 min) of cotton treated with extreme conditions appear to be durable as long as the fabric is not washed. X-ray photoelectron spectroscopy analysis reveals that the water absorption time of the fabric follows the same increasing trend as the fluorine/carbon ratio at the fabric surface and atom density of fluorine measured by Ar actinometer.

Liftoff characteristics of partially premixed flames under normal and microgravity conditions

Energy Technology Data Exchange (ETDEWEB)

Lock, Andrew J.; Briones, Alejandro M.; Aggarwal, Suresh K. [Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Qin, Xiao [Department of Mechanical & amp; Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States); Puri, Ishwar K. [Department of Engineering Science and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 (United States); Hegde, Uday [National Center for Microgravity Research, Cleveland, OH 44135 (United States)

2005-11-01

An experimental and computational investigation on the liftoff characteristics of laminar partially premixed flames (PPFs) under normal (1-g) and microgravity ({mu}-g) conditions is presented. Lifted methane-air PPFs were established in axisymmetric coflowing jets using nitrogen dilution and various levels of partial premixing. The {mu}-g experiments were conducted in the 2.2-s drop tower at the NASA Glenn Research Center. A time-accurate, implicit algorithm that uses a detailed description of the chemistry and includes radiation effects is used for the simulations. The predictions are validated through a comparison of the flame reaction zone topologies, liftoff heights, lengths, and oscillation frequencies. The effects of equivalence ratio, gravity, jet velocity, and radiation on flame topology, liftoff height, flame length, base structure, and oscillation frequency are characterized. Both the simulations and measurements indicate that under identical conditions, a lifted {mu}-g PPF is stabilized closer to the burner compared with the 1-g flame, and that the liftoff heights of both 1-g and {mu}-g flames decrease with increasing equivalence ratio and approach their respective nonpremixed flame limits. The liftoff height also increases as the jet velocity is increased. In addition, the flame base structure transitions from a triple- to a double-flame structure as the flame liftoff height decreases. A modified flame index is developed to distinguish between the rich premixed, lean premixed, and nonpremixed reaction zones near the flame base. The 1-g lifted flames exhibit well-organized oscillations due to buoyancy-induced instability, while the corresponding {mu}-g flames exhibit steady-state behavior. The effect of thermal radiation is to slightly decrease the liftoff heights of both 1-g and {mu}-g flames under coflow conditions.

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.

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.

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.

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.

Morphology-properties relationship of gas plasma treated hydrophobic meso-porous membranes and their improved performance for desalination by membrane distillation

International Nuclear Information System (INIS)

Dumée, Ludovic F.; Alglave, Hortense; Chaffraix, Thomas; Lin, Bao; Magniez, Kevin; Schütz, Jürg

2016-01-01

Graphical abstract: - Highlights: • Systematic surface modifications by gas plasma treatment of hydrophobic polymers. • Correlation between plasma parameters and materials surface energy and morphology. • Spectral analysis of the formation of functional groups across the membranes surface. • Relationship between wettability, roughness and performance. - Abstract: The impact on performance of the surface energy and roughness of membrane materials used for direct contact membrane distillation are critical but yet poorly investigated parameters. The capacity to alter the wettability of highly hydrophobic materials such as poly(tetra-fluoro-ethylene) (PTFE) by gas plasma treatments is reported in this paper. An equally important contribution from this investigation arises from illustrating how vaporized material from the treated sample participates after a short while in the composition of the plasma and fundamentally changes the result of surface chemistry processes. The water contact angle across the hydrophobic membranes is generally controlled by varying the plasma gas conditions, such as the plasma power, chamber pressure and irradiation duration. Changes to surface porosity and roughness of the bulk material as well as the surface chemistry, through specific and partial de-fluorination of the surface were detected and systematically studied by Fourier transform infra-red analysis and scanning electron microscopy. It was found that the rupture of fibrils, formed during membrane processing by thermal-stretching, led to the formation of a denser surface composed of nodules similar to these naturally acting as bridging points across the membrane material between fibrils. This structural change has a profound and impart a permanent effect on the permeation across the modified membranes, which was found to be enhanced by up to 10% for long plasma exposures while the selectivity of the membranes was found to remain unaffected by the treatment at a level higher

Morphology-properties relationship of gas plasma treated hydrophobic meso-porous membranes and their improved performance for desalination by membrane distillation

Energy Technology Data Exchange (ETDEWEB)

Dumée, Ludovic F., E-mail: ludovic.dumee@deakin.edu.au [Deakin University, Geelong Victoria–Australia - Institute for Frontier Materials (Australia); Alglave, Hortense; Chaffraix, Thomas; Lin, Bao; Magniez, Kevin [Deakin University, Geelong Victoria–Australia - Institute for Frontier Materials (Australia); Schütz, Jürg [CSIRO, Manufacturing Flagship, 75 Pigdons Road, 3216 Waurn Ponds, Victoria (Australia)

2016-02-15

Graphical abstract: - Highlights: • Systematic surface modifications by gas plasma treatment of hydrophobic polymers. • Correlation between plasma parameters and materials surface energy and morphology. • Spectral analysis of the formation of functional groups across the membranes surface. • Relationship between wettability, roughness and performance. - Abstract: The impact on performance of the surface energy and roughness of membrane materials used for direct contact membrane distillation are critical but yet poorly investigated parameters. The capacity to alter the wettability of highly hydrophobic materials such as poly(tetra-fluoro-ethylene) (PTFE) by gas plasma treatments is reported in this paper. An equally important contribution from this investigation arises from illustrating how vaporized material from the treated sample participates after a short while in the composition of the plasma and fundamentally changes the result of surface chemistry processes. The water contact angle across the hydrophobic membranes is generally controlled by varying the plasma gas conditions, such as the plasma power, chamber pressure and irradiation duration. Changes to surface porosity and roughness of the bulk material as well as the surface chemistry, through specific and partial de-fluorination of the surface were detected and systematically studied by Fourier transform infra-red analysis and scanning electron microscopy. It was found that the rupture of fibrils, formed during membrane processing by thermal-stretching, led to the formation of a denser surface composed of nodules similar to these naturally acting as bridging points across the membrane material between fibrils. This structural change has a profound and impart a permanent effect on the permeation across the modified membranes, which was found to be enhanced by up to 10% for long plasma exposures while the selectivity of the membranes was found to remain unaffected by the treatment at a level higher

Particle Surface Hydrophobicity and the Dechlorination of Chloro-Compounds by Iron Sulfides

Energy Technology Data Exchange (ETDEWEB)

Park, Sang-Won, E-mail: spark3@uncc.edu; Kim, Sung-Kuk; Kim, Jeong-Bae; Choi, Sung-Woo [Keimyung University, Department of Environmental Science and Engineering (Korea, Republic of); Inyang, Hilary I. [University of North Carolina at Charlotte, Global Institute for Energy and Environmental Systems (United States); Tokunaga, Shuzo [National Institute of Advanced Industrial Science and Technology (Japan)

2006-02-15

Halogenated aliphatic compounds (HACs) can be reduced by iron sulfides in aqueous systems. Generally, the thermodynamics and kinetics of dehalogenation reactions are controlled by the mineralogical and particle surface characteristics of the iron sulfide, the composition of the HAC and reaction conditions such as component concentrations, pH and Eh. In this theoretical and experimental investigation of CCl{sub 4} and C{sub 2}Cl{sub 6} reduction by FeS and FeS{sub 2}, the roles of hydrophobic and hydrophilic sites on the iron sulfides were analyzed. Experimental data obtained through zeta potential measurements, were used along with the Gouy-Chapman model and the simple two-layer surface complexation model to relate iron sulfide surface hydroxyl densities to the degree of HAC dehalogenation. The surface hydroxyl site densities of FeS and FeS{sub 2} were found to be 0.11 sites/nm{sup 2} and 0.21 sites/nm{sup 2}, respectively. During the dehalogenation reaction process, CCl{sub 4} was found to decrease to its first intermediate product CHCl{sub 3} within the first 20 hours followed by a slower process of conversion to CH{sub 2}Cl{sub 2}. The results also show that FeS is less hydrated (more hydrophobic) than FeS{sub 2}. For CCl{sub 4} and C{sub 2}Cl{sub 6}, FeS is a better dehalogenator than FeS{sub 2}. These results imply that particle surface hydrophobicity is a critical factor in surface-mediated dehalogenation of chlorinated compounds.

SN-38 loading capacity of hydrophobic polymer blend nanoparticles: formulation, optimization and efficacy evaluation.

Science.gov (United States)

Dimchevska, Simona; Geskovski, Nikola; Petruševski, Gjorgji; Chacorovska, Marina; Popeski-Dimovski, Riste; Ugarkovic, Sonja; Goracinova, Katerina

2017-03-01

One of the most important problems in nanoencapsulation of extremely hydrophobic drugs is poor drug loading due to rapid drug crystallization outside the polymer core. The effort to use nanoprecipitation, as a simple one-step procedure with good reproducibility and FDA approved polymers like Poly(lactic-co-glycolic acid) (PLGA) and Polycaprolactone (PCL), will only potentiate this issue. Considering that drug loading is one of the key defining characteristics, in this study we attempted to examine whether the nanoparticle (NP) core composed of two hydrophobic polymers will provide increased drug loading for 7-Ethyl-10-hydroxy-camptothecin (SN-38), relative to NPs prepared using individual polymers. D-optimal design was applied to optimize PLGA/PCL ratio in the polymer blend and the mode of addition of the amphiphilic copolymer Lutrol ® F127 in order to maximize SN-38 loading and obtain NPs with acceptable size for passive tumor targeting. Drug/polymer and polymer/polymer interaction analysis pointed to high degree of compatibility and miscibility among both hydrophobic polymers, providing core configuration with higher drug loading capacity. Toxicity studies outlined the biocompatibility of the blank NPs. Increased in vitro efficacy of drug-loaded NPs compared to the free drug was confirmed by growth inhibition studies using SW-480 cell line. Additionally, the optimized NP formulation showed very promising blood circulation profile with elimination half-time of 7.4 h.

The characteristics of SPECT images in childhood benign partial epilepsy

International Nuclear Information System (INIS)

Jia Shaowei; Liao Jianxiang; Liu Xiaoyan; Zheng Xiyuan; Qin Jiong; Pan Zhongyun; Zuo Qihua

1998-01-01

Purpose: To investigate childhood benign partial epilepsy (BPE) with SPECT. Methods: Double SPECT imaging was performed on 21 cases of BPE at the stage of wake (interval spike discharge) and sleep (spike discharge), under EEG monitoring. The transverse images were reconstructed after digital image subtraction. The quantitative analysis was conducted with brain flow change rate (BFCR) % mathematical model. Results: EEG monitoring demonstrated approximately normal background of 21 cases of BPE during the stage of wake, and spike discharge frequency markedly increased during the stage of sleep, 117 foci were showed by SPeCT in cases of BPE, and the average was 5.6 +- 1.6 foci/case. The characteristics of SPECT transverse images were 1) multiple foci of mirror, 2) mostly seen in Rolandic region, 3) circular symbol, 4) the radioactivity in foci decreased during the stage of wake (interval spike discharge) and increased during the stage of sleep (spike discharge). The concordance of SPECT and EEG was 93.1% (109/117 foci). The BFCR% of all epileptogenic foci exceeded normal limit (99% confidence interval). There was no correlation between the spike discharge frequency and BFCR% (r = 0.45, P>0.05). Conclusions: Regional cerebral blood flow and function were abnormal during the epileptogenic foci were discharging abnormally in BPE

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.

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.

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.

Beginning partial differential equations

CERN Document Server

O'Neil, Peter V

2014-01-01

A broad introduction to PDEs with an emphasis on specialized topics and applications occurring in a variety of fields Featuring a thoroughly revised presentation of topics, Beginning Partial Differential Equations, Third Edition provides a challenging, yet accessible,combination of techniques, applications, and introductory theory on the subjectof partial differential equations. The new edition offers nonstandard coverageon material including Burger's equation, the telegraph equation, damped wavemotion, and the use of characteristics to solve nonhomogeneous problems. The Third Edition is or

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

Tuning the Hydrophilic/Hydrophobic Balance to Control the Structure of Chitosan Films and Their Protein Release Behavior.

Science.gov (United States)

Becerra, Jose; Sudre, Guillaume; Royaud, Isabelle; Montserret, Roland; Verrier, Bernard; Rochas, Cyrille; Delair, Thierry; David, Laurent

2017-05-01

The control over the crystallinity of chitosan and chitosan/ovalbumin films can be achieved via an appropriate balance of the hydrophilic/hydrophobic interactions during the film formation process, which then controls the release kinetics of ovalbumin. Chitosan films were prepared by solvent casting. The presence of the anhydrous allomorph can be viewed as a probe of the hydrophobic conditions at the neutralization step. The semicrystalline structure, the swelling behavior of the films, the protein/chitosan interactions, and the release behavior of the films were impacted by the DA and the film processing parameters. At low DAs, the chitosan films neutralized in the solid state corresponded to the most hydrophobic environment, inducing the crystallization of the anhydrous allomorph with and without protein. The most hydrophilic conditions, leading to the hydrated allomorph, corresponded to non-neutralized films for the highest DAs. For the non-neutralized chitosan acetate (amorphous) films, the swelling increased when the DA decreased, whereas for the neutralized chitosan films, the swelling decreased. The in vitro release of ovalbumin (model protein) from chitosan films was controlled by their swelling behavior. For fast swelling films (DA = 45%), a burst effect was observed. On the contrary, a lag time was evidenced for DA = 2.5% with a limited release of the protein. Furthermore, by blending chitosans (DA = 2.5% and 45%), the release behavior was improved by reducing the burst effect and the lag time. The secondary structure of ovalbumin was partially maintained in the solid state, and the ovalbumin was released under its native form.

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.

Texture Analysis of Hydrophobic Polycarbonate and Polydimethylsiloxane Surfaces via Persistent Homology

Directory of Open Access Journals (Sweden)

Ali Nabi Duman

2017-09-01

Full Text Available Due to recent climate change-triggered, regular dust storms in the Middle East, dust mitigation has become the critical issue for solar energy harvesting devices. One of the methods to minimize and prevent dust adhesion and create self-cleaning abilities is to generate hydrophobic characteristics on surfaces. The purpose of this study is to explore the topological features of hydrophobic surfaces. We use non-standard techniques from topological data analysis to extract morphological features from the AFM images. Our method recovers most of the previous qualitative observations in a robust and quantitative way. Persistence diagrams, which is a summary of topological structures, witness quantitatively that the crystallized polycarbonate (PC surface possesses spherulites, voids, and fibrils, and the texture height and spherulite concentration increases with the increased immersion period. The approach also shows that the polydimethylsiloxane (PDMS exactly copied the structures at the PC surface but 80 to 90 percent of the nanofibrils were not copied at PDMS surface. We next extract a feature vector from each persistence diagram to show which experiments hold features with similar variance using principal component analysis (PCA. The K-means clustering algorithm is applied to the matrix of feature vectors to support the PCA result, grouping experiments with similar features.

Partial molar volume of n-alcohols at infinite dilution in water calculated by means of scaled particle theory.

Science.gov (United States)

Graziano, Giuseppe

2006-04-07

The partial molar volume of n-alcohols at infinite dilution in water is smaller than the molar volume in the neat liquid phase. It is shown that the formula for the partial molar volume at infinite dilution obtained from the scaled particle theory equation of state for binary hard sphere mixtures is able to reproduce in a satisfactory manner the experimental data over a large temperature range. This finding implies that the packing effects play the fundamental role in determining the partial molar volume at infinite dilution in water also for solutes, such as n-alcohols, forming H bonds with water molecules. Since the packing effects in water are largely related to the small size of its molecules, the latter feature is the ultimate cause of the decrease in partial molar volume associated with the hydrophobic effect.

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.

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

In situ crystallized zirconium phenylphosphonate films with crystals vertically to the substrate and their hydrophobic, dielectric, and anticorrosion properties.

Science.gov (United States)

Cui, Zhaohui; Zhang, Fazhi; Wang, Lei; Xu, Sailong; Guo, Xiaoxiao

2010-01-05

The in situ crystallization technique has been utilized to fabricate zirconium phenylphosphonate (ZrPP) films with their hexagonal crystallite perpendicular to the copper substrate. The micro/nano roughness surface structure, as well as the intrinsic hydrophobic characteristic of the surface functional groups, affords ZrPP films excellent hydrophobicity with water contact angle (CA) ranging from 134 degrees to 151 degrees , without any low-surface-energy modification. Particularly, in the corrosive solutions such as acidic or basic solutions over a wide pH from 2 to 12, no obvious fluctuation in CA was observed for all the ZrPP film. The k values of the hydrophobic ZrPP films are in the low-k range (k feature is proposed to bear ZrPP film a more stable low-k value in an ambient atmosphere. Besides, the polarization current of ZrPP films is reduced by 2 orders of magnitude, compared to that of the untreated copper substrate. Even deposited in a vacuum oven for 30 days at room temperature, ZrPP films also show excellent corrosion resistance, indicating a stable anticorrosion property.

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

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.

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.

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.

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

The new method of modifying the hydrophobic properties of expanded perlite

Directory of Open Access Journals (Sweden)

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.

Partially Cystic Thyroid Nodules: Ultrasound Findings of Malignancy

Energy Technology Data Exchange (ETDEWEB)

Park, Jang Mi; Choi, Yoon Jung; Kwag, Hyon Joo [Dept. of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

2012-09-15

To seek for the ultrasound (US) findings of partially cystic thyroid nodules that are associated with malignancy. We reviewed the US characteristics of 22 surgically confirmed partially cystic papillary carcinomas, and compared them with those of 80 benign partially cystic nodules. The review cases were selected in a random order from a total of 1029 partially cystic nodules that were diagnosed with an US-guided fine needle aspiration biopsy over a period of 8 years (June 2003 to October 2010) at our institution. In partially cystic thyroid nodules, a taller-than-wide shape (100%, p<0.001) and spiculated or microlobulated margin (58.3%, p 0.003) were significantly associated with malignancy. In terms of internal solid portion of the nodule, eccentric configuration (68.0%, p<0.001), non-smooth margin (81.3%, p<0.001), hypoechogenecity (30.0%, p<0.042), and microcalcification (89.5%, p<0.001) were more frequently demonstrated in malignant nodules than benign ones. In partially cystic thyroid nodules, understanding the characteristics of US findings is important to make a precise diagnosis of malignant nodules.

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

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

Directory of Open Access Journals (Sweden)

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.

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.

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.

Optimization of the process of synthesis of hydrophobic clay; Otimizacao do processo de sintese de uma argila hidrofobica

Energy Technology Data Exchange (ETDEWEB)

Muniz, C.C.; Silva, S.M.L. da [Universidade Federal de Campina Grande (UAEMa/UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais; Raposo, C.M.O., E-mail: raposo@dmg.ufcg.edu.b [Universidade Federal de Campina Grande (UAMG/UFCG), PB (Brazil). Unidade Academica de Mineracao e Geologia

2009-07-01

Bentonite is a nature silicate pertaining subclass of phyllosilicates 2:1, being formed of accessories minerals, which montmorillonite there is in content more significant. The minerals and intrinsic impurities in the mineral predominant, such as, the procedure of organic modification, probably, influence so significant the obtainment of hydrophobic powders with crystallographic characteristics most appropriate to obtainment of materials nanostructured. The aim of the work was the optimization of synthesis process of hydrophobic clay promoted at the powder prepared a new structural profile. The original matter, bentonite, from Bentonit Uniao Nordeste- BUN/Paraiba, was previously purified and organophilized used an ammonium quaternary salt. The characterization of solids prepared was realized by infrared spectroscopy and x-ray diffraction indicating the obtainment of material with competitive profile when compared to the commercial one. (author)

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.

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

Partial monosomy 8q and partial trisomy 9q due to the maternal translocation t(8;9(q24.3;q34.1)

DEFF Research Database (Denmark)

Tos, T; Alp, M Y; Eker, H K

2014-01-01

Partial trisomy 9q34-qter and partial monosomy 8q24.3-qter are very rare chromosomal abnormalities. Characteristic features of partial trisomy 9q34-qter are hypotonia, developmental delay, mild intellectual disability, dolichocephaly, distinct facial phenotype, long and thin fingers, and cardiac...

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

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...

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)

The H2A-H2B dimeric kinetic intermediate is stabilized by widespread hydrophobic burial with few fully native interactions.

Science.gov (United States)

Guyett, Paul J; Gloss, Lisa M

2012-01-20

The H2A-H2B histone heterodimer folds via monomeric and dimeric kinetic intermediates. Within ∼5 ms, the H2A and H2B polypeptides associate in a nearly diffusion limited reaction to form a dimeric ensemble, denoted I₂ and I₂*, the latter being a subpopulation characterized by a higher content of nonnative structure (NNS). The I₂ ensemble folds to the native heterodimer, N₂, through an observable, first-order kinetic phase. To determine the regions of structure in the I₂ ensemble, we characterized 26 Ala mutants of buried hydrophobic residues, spanning the three helices of the canonical histone folds of H2A and H2B and the H2B C-terminal helix. All but one targeted residue contributed significantly to the stability of I₂, the transition state and N₂; however, only residues in the hydrophobic core of the dimer interface perturbed the I₂* population. Destabilization of I₂* correlated with slower folding rates, implying that NNS is not a kinetic trap but rather accelerates folding. The pattern of Φ values indicated that residues forming intramolecular interactions in the peripheral helices contributed similar stability to I₂ and N₂, but residues involved in intermolecular interactions in the hydrophobic core are only partially folded in I₂. These findings suggest a dimerize-then-rearrange model. Residues throughout the histone fold contribute to the stability of I₂, but after the rapid dimerization reaction, the hydrophobic core of the dimer interface has few fully native interactions. In the transition state leading to N₂, more native-like interactions are developed and nonnative interactions are rearranged. Copyright © 2011 Elsevier Ltd. All rights reserved.

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.

Hydrophobicity of electron beam modified surface of hydroxyapatite films

Energy Technology Data Exchange (ETDEWEB)

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.

Entropic formulation for the protein folding process: Hydrophobic stability correlates with folding rates

Science.gov (United States)

Dal Molin, J. P.; Caliri, A.

2018-01-01

Here we focus on the conformational search for the native structure when it is ruled by the hydrophobic effect and steric specificities coming from amino acids. Our main tool of investigation is a 3D lattice model provided by a ten-letter alphabet, the stereochemical model. This minimalist model was conceived for Monte Carlo (MC) simulations when one keeps in mind the kinetic behavior of protein-like chains in solution. We have three central goals here. The first one is to characterize the folding time (τ) by two distinct sampling methods, so we present two sets of 103 MC simulations for a fast protein-like sequence. The resulting sets of characteristic folding times, τ and τq were obtained by the application of the standard Metropolis algorithm (MA), as well as by an enhanced algorithm (Mq A). The finding for τq shows two things: (i) the chain-solvent hydrophobic interactions {hk } plus a set of inter-residues steric constraints {ci,j } are able to emulate the conformational search for the native structure. For each one of the 103MC performed simulations, the target is always found within a finite time window; (ii) the ratio τq / τ ≅ 1 / 10 suggests that the effect of local thermal fluctuations, encompassed by the Tsallis weight, provides to the chain an innate efficiency to escape from energetic and steric traps. We performed additional MC simulations with variations of our design rule to attest this first result, both algorithms the MA and the Mq A were applied to a restricted set of targets, a physical insight is provided. Our second finding was obtained by a set of 600 independent MC simulations, only performed with the Mq A applied to an extended set of 200 representative targets, our native structures. The results show how structural patterns should modulate τq, which cover four orders of magnitude; this finding is our second goal. The third, and last result, was obtained with a special kind of simulation performed with the purpose to explore a

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.

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.

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.

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.

Characteristics of hydrogen produced by partial oxidation and auto-thermal reforming in a small methanol reformer

Science.gov (United States)

Horng, Rong-Fang; Chou, Huann-Ming; Lee, Chiou-Hwang; Tsai, Hsien-Te

This paper investigates experimentally, the transient characteristics of a small methanol reformer using partial oxidation (POX) and auto-thermal reforming (ATR) for fuel cell applications. The parameters varied were heating temperature, methanol supply rate, steady mode shifting temperature, O 2/C (O 2/CH 3OH) and S/C (H 2O/CH 3OH) molar ratios with the main aim of promoting a rapid response and a high flow rate of hydrogen. The experiments showed that a high steady mode shifting temperature resulted in a faster temperature rise at the catalyst outlet and vice versa and that a low steady mode shifting temperature resulted in a lower final hydrogen concentration. However, when the mode shifting temperature was too high, the hydrogen production response was not necessarily improved. It was subsequently shown that the optimum steady mode shifting temperature for this experimental set-up was approximately 75 °C. Further, the hydrogen concentration produced by the auto-thermal process was as high as 49.12% and the volume flow rate up to 23.0 L min -1 compared to 40.0% and 20.5 L min -1 produced by partial oxidation.

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.

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.

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.

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

Hydrophobic interaction chromatography in dual salt system increases protein binding capacity.

Science.gov (United States)

Senczuk, Anna M; Klinke, Ralph; Arakawa, Tsutomu; Vedantham, Ganesh; Yigzaw, Yinges

2009-08-01

Hydrophobic interaction chromatography (HIC) uses weakly hydrophobic resins and requires a salting-out salt to promote protein-resin interaction. The salting-out effects increase with protein and salt concentration. Dynamic binding capacity (DBC) is dependent on the binding constant, as well as on the flow characteristics during sample loading. DBC increases with the salt concentration but decreases with increasing flow rate. Dynamic and operational binding capacity have a major raw material cost/processing time impact on commercial scale production of monoclonal antibodies. In order to maximize DBC the highest salt concentration without causing precipitation is used. We report here a novel method to maintain protein solubility while increasing the DBC by using a combination of two salting-out salts (referred to as dual salt). In a series of experiments, we explored the dynamic capacity of a HIC resin (TosoBioscience Butyl 650M) with combinations of salts. Using a model antibody, we developed a system allowing us to increase the dynamic capacity up to twofold using the dual salt system over traditional, single salt system. We also investigated the application of this novel approach to several other proteins and salt combinations, and noted a similar protein solubility and DBC increase. The observed increase in DBC in the dual salt system was maintained at different linear flow rates and did not impact selectivity.

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.

Partial reconstitution of photoreceptor cGMP phosphodiesterase characteristics in cGMP phosphodiesterase-5.

Science.gov (United States)

Granovsky, A E; Artemyev, N O

2001-06-15

Photoreceptor cGMP phosphodiesterases (PDE6) are uniquely qualified to serve as effector enzymes in the vertebrate visual transduction cascade. In the dark-adapted photoreceptors, the activity of PDE6 is blocked via tight association with the inhibitory gamma-subunits (Pgamma). The Pgamma block is removed in the light-activated PDE6 by the visual G protein, transducin. Transducin-activated PDE6 exhibits an exceptionally high catalytic rate of cGMP hydrolysis ensuring high signal amplification. To identify the structural determinants for the inhibitory interaction with Pgamma and the remarkable cGMP hydrolytic ability, we sought to reproduce the PDE6 characteristics by mutagenesis of PDE5, a related cyclic GMP-specific, cGMP-binding PDE. PDE5 is insensitive to Pgamma and has a more than 100-fold lower k(cat) for cGMP hydrolysis. Our mutational analysis of chimeric PDE5/PDE6alpha' enzymes revealed that the inhibitory interaction of cone PDE6 catalytic subunits (PDE6alpha') with Pgamma is mediated primarily by three hydrophobic residues at the entry to the catalytic pocket, Met(758), Phe(777), and Phe(781). The maximal catalytic rate of PDE5 was enhanced by at least 10-fold with substitutions of PDE6alpha'-specific glycine residues for the corresponding PDE5 alanine residues, Ala(608) and Ala(612). The Gly residues are adjacent to the highly conserved metal binding motif His-Asn-X-X-His, which is essential for cGMP hydrolysis. Our results suggest that the unique Gly residues allow the PDE6 metal binding site to adopt a more favorable conformation for cGMP hydrolysis.

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).

Anatomic partial nephrectomy: technique evolution.

Science.gov (United States)

Azhar, Raed A; Metcalfe, Charles; Gill, Inderbir S

2015-03-01

Partial nephrectomy provides equivalent long-term oncologic and superior functional outcomes as radical nephrectomy for T1a renal masses. Herein, we review the various vascular clamping techniques employed during minimally invasive partial nephrectomy, describe the evolution of our partial nephrectomy technique and provide an update on contemporary thinking about the impact of ischemia on renal function. Recently, partial nephrectomy surgical technique has shifted away from main artery clamping and towards minimizing/eliminating global renal ischemia during partial nephrectomy. Supported by high-fidelity three-dimensional imaging, novel anatomic-based partial nephrectomy techniques have recently been developed, wherein partial nephrectomy can now be performed with segmental, minimal or zero global ischemia to the renal remnant. Sequential innovations have included early unclamping, segmental clamping, super-selective clamping and now culminating in anatomic zero-ischemia surgery. By eliminating 'under-the-gun' time pressure of ischemia for the surgeon, these techniques allow an unhurried, tightly contoured tumour excision with point-specific sutured haemostasis. Recent data indicate that zero-ischemia partial nephrectomy may provide better functional outcomes by minimizing/eliminating global ischemia and preserving greater vascularized kidney volume. Contemporary partial nephrectomy includes a spectrum of surgical techniques ranging from conventional-clamped to novel zero-ischemia approaches. Technique selection should be tailored to each individual case on the basis of tumour characteristics, surgical feasibility, surgeon experience, patient demographics and baseline renal function.

Complexation of Polyelectrolytes with Hydrophobic Drug Molecules in Salt-Free Solution: Theory and Simulations.

Science.gov (United States)

Lei, Qun-Li; Hadinoto, Kunn; Ni, Ran

2017-04-18

The delivery and dissolution of poorly soluble drugs is challenging in the pharmaceutical industry. One way to significantly improve the delivery efficiency is to incorporate these hydrophobic small molecules into a colloidal polyelectrolyes(PE)-drug complex in their ionized states. Despite its huge application value, the general mechanism of PE collapse and complex formation in this system has not been well understood. In this work, by combining a mean-field theory with extensive molecular simulations, we unveil the phase behaviors of the system under dilute and salt-free conditions. We find that the complexation is a first-order-like phase transition triggered by the hydrophobic attraction between the drug molecules. Importantly, the valence ratio between the drug molecule and PE monomer plays a crucial role in determining the stability and morphology of the complex. Moreover, the sign of the zeta potential and the net charge of the complex are found to be inverted as the hydrophobicity of the drug molecules increases. Both theory and simulation indicate that the complexation point and complex morphology and the electrostatic properties of the complex have a weak dependence on chain length. Finally, the dynamics aspect of PE-drug complexation is also explored, and it is found that the complex can be trapped into a nonequilibrium glasslike state when the hydropobicity of the drug molecule is too strong. Our work gives a clear physical picture behind the PE-drug complexation phenomenon and provides guidelines to fabricate the colloidal PE-drug complex with the desired physical characteristics.

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

Partially massless fields during inflation

Science.gov (United States)

Baumann, Daniel; Goon, Garrett; Lee, Hayden; Pimentel, Guilherme L.

2018-04-01

The representation theory of de Sitter space allows for a category of partially massless particles which have no flat space analog, but could have existed during inflation. We study the couplings of these exotic particles to inflationary perturbations and determine the resulting signatures in cosmological correlators. When inflationary perturbations interact through the exchange of these fields, their correlation functions inherit scalings that cannot be mimicked by extra massive fields. We discuss in detail the squeezed limit of the tensor-scalar-scalar bispectrum, and show that certain partially massless fields can violate the tensor consistency relation of single-field inflation. We also consider the collapsed limit of the scalar trispectrum, and find that the exchange of partially massless fields enhances its magnitude, while giving no contribution to the scalar bispectrum. These characteristic signatures provide clean detection channels for partially massless fields during inflation.

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.

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

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.

Characteristics of epoxy resin/SiO2 nanocomposite insulation: effects of plasma surface treatment on the nanoparticles.

Science.gov (United States)

Yan, Wei; Phung, B T; Han, Zhao Jun; Ostrikov, Kostya

2013-05-01

The present study compares the effects of two different material processing techniques on modifying hydrophilic SiO2 nanoparticles. In one method, the nanoparticles undergo plasma treatment by using a custom-developed atmospheric-pressure non-equilibrium plasma reactor. With the other method, they undergo chemical treatment which grafts silane groups onto their surface and turns them into hydrophobic. The treated nanoparticles are then used to synthesize epoxy resin-based nanocomposites for electrical insulation applications. Their characteristics are investigated and compared with the pure epoxy resin and nanocomposite fabricated with unmodified nanofillers counterparts. The dispersion features of the nanoparticles in the epoxy resin matrix are examined through scanning electron microscopy (SEM) images. All samples show evidence that the agglomerations are smaller than 30 nm in their diameters. This indicates good dispersion uniformity. The Weibull plot of breakdown strength and the recorded partial discharge (PD) events of the epoxy resin/plasma-treated hydrophilic SiO2 nanocomposite (ER/PTI) suggest that the plasma-treated specimen yields higher breakdown strength and lower PD magnitude as compared to the untreated ones. In contrast, surprisingly, lower breakdown strength is found for the nanocomposite made by the chemically treated hydrophobic particles, whereas the PD magnitude and PD numbers remain at a similar level as the plasma-treated ones.

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...

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

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 ...

Characteristics and self-cleaning effect of the transparent super-hydrophobic film having nanofibers array structures

Science.gov (United States)

Lee, Kyungjun; Lyu, Sungnam; Lee, Sangmin; Kim, Youn Sang; Hwang, Woonbong

2010-09-01

Transparent super-hydrophobic films were fabricated using the PDMS method and silane process, based on anodization in phosphoric acid. Contact angle tests were performed to determine the contact angle of each film according to the anodizing time. Transmittance tests also were performed to obtain the transparency of each TPT (trimethylolpropane propoxylate triacrylate) replica film according to the anodizing time. The contact angle was determined by studying the drop shape, and the transmittance was measured using a UV-spectrometer. The contact angle increases with increasing anodizing time, because increasing pillar length can trap more air between the TPT replica film and a drop of water. The transmittance falls with increasing anodizing time because the increasing pillar length causes a scattering effect. This study shows that the pillar length and transparency are inversely proportional. The TPT replica film having nanofibers array structures was better than other films in aspect of self-cleaning by doing quantitative experimentation.

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.

Hydrophobicity Tuning by the Fast Evolution of Mold Temperature during Injection Molding

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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.

Double-grooved nanofibre surfaces with enhanced anisotropic hydrophobicity.

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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.

Temperature Effect on Electrical Treeing and Partial Discharge Characteristics of Silicone Rubber-Based Nanocomposites

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Mohd Hafizi Ahmad

2015-01-01

Full Text Available This study investigated electrical treeing and its associated phase-resolved partial discharge (PD activities in room-temperature, vulcanized silicone rubber/organomontmorillonite nanocomposite sample materials over a range of temperatures in order to assess the effect of temperature on different filler concentrations under AC voltage. The samples were prepared with three levels of nanofiller content: 0% by weight (wt, 1% by wt, and 3% by wt. The electrical treeing and PD activities of these samples were investigated at temperatures of 20°C, 40°C, and 60°C. The results show that the characteristics of the electrical tree changed with increasing temperature. The tree inception times decreased at 20°C due to space charge dynamics, and the tree growth time increased at 40°C due to the increase in the number of cross-link network structures caused by the vulcanization process. At 60°C, more enhanced and reinforced properties of the silicone rubber-based nanocomposite samples occurred. This led to an increase in electrical tree inception time and electrical tree growth time. However, the PD characteristics, particularly the mean phase angle of occurrence of the positive and negative discharge distributions, were insensitive to variations in temperature. This reflects an enhanced stability in the nanocomposite electrical properties compared with the base polymer.

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

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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

Optically transparent super-hydrophobic thin film fabricated by reusable polyurethane-acrylate (PUA) mold

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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.

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.

CARNAUBA WAX USED AS AN HYDROPHOBIC AGENT FOR EXPANDED VERMICULITE

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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.

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

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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

Gradient elution behavior of proteins in hydrophobic interaction chromatography with U-shaped retention factor curves.

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Creasy, Arch; Lomino, Joseph; Barker, Gregory; Khetan, Anurag; Carta, Giorgio

2018-04-27

Protein retention in hydrophobic interaction chromatography is described by the solvophobic theory as a function of the kosmostropic salt concentration. In general, an increase in salt concentration drives protein partitioning to the hydrophobic surface while a decrease reduces it. In some cases, however, protein retention also increases at low salt concentrations resulting in a U-shaped retention factor curve. During gradient elution the salt concentration is gradually decreased from a high value thereby reducing the retention factor and increasing the protein chromatographic velocity. For these conditions, a steep gradient can overtake the protein in the column, causing it to rebind. Two dynamic models, one based on the local equilibrium theory and the other based on the linear driving force approximation, are presented. We show that the normalized gradient slope determines whether the protein elutes in the gradient, partially elutes, or is trapped in the column. Experimental results are presented for two different monoclonal antibodies and for lysozyme on Capto Phenyl (High Sub) resin. One of the mAbs and lysozyme exhibit U-shaped retention factor curves and for each, we determine the critical gradient slope beyond which 100% recovery is no longer possible. Elution with a reverse gradient is also demonstrated at low salt concentrations for these proteins. Understanding this behavior has implications in the design of gradient elution since the gradient slope impacts protein recovery. Copyright © 2018 Elsevier B.V. All rights reserved.

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

Creation of hydrophobic surfaces using a paint containing functionalized oxide particles

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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.

Cu(I)/Cu(II) mixed-valence surface complexes of S-[(2-hydroxyamino)-2-oxoethyl]-N,N-dibutyldithiocarbamate: Hydrophobic mechanism to malachite flotation.

Science.gov (United States)

Liu, Sheng; Zhong, Hong; Liu, Guangyi; Xu, Zhenghe

2018-02-15

Hydroxamate and sulfhydryl surfactants are effective collectors for flotation of copper minerals. The combination application of hydroxamate and sulfhydryl collectors has been proved to be an effective approach for improving the flotation recovery of non-sulfide copper minerals. A surfactant owing both hydroxamate and dithiocarbamate groups might exhibit strong affinity to non-sulfide copper minerals through double sites adsorption, rendering an enhanced hydrophobization to non-sulfide copper minerals flotation. The flotation performance of S-[(2-hydroxyamino)-2-oxoethyl]- N,N-dibutyldithiocarbamate (HABTC) to malachite, calcite and quartz were first evaluated through systematic micro-flotation experiments. HABTC's hydrophobic mechanism to malachite was further investigated and analyzed by zeta potential, Fourier transform infrared spectroscopy (FTIR), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS). The micro-flotation results demonstrated HABTC was an excellent collector for malachite flotation and exhibited favorable selectivity for flotation separation of malachite from quartz or calcite under pH 8.5-10.3. Zeta potential and FTIR implied that HABTC might bond with the surface copper atoms of malachite, with releasing the H + ions of its hydroxamate group into pulp. ToF-SIMS provided clear evidences that the Cu-hydroxamate and Cu-dithiocarbamate groups were formed on malachite surfaces after HABTC adsorption. XPS revealed that Cu(I)/Cu(II) mixed-valence surface complexes of HABTC anchored on malachite through formation of Cu(I)S and Cu(II)O bonds, accompanying with reduction of partial surface Cu(II) to Cu(I). The Cu(I)/Cu(II) mixed-valence double chelating character and "chair"-shape N,N-dibutyldithiocarbamate hydrophobic group, resulting in an enhanced affinity and hydrophobization of HABTC to malachite flotation. Copyright © 2017 Elsevier Inc. All rights reserved.

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.

Calcification of Hydrophilic Acrylic Intraocular Lenses With a Hydrophobic Surface: Laboratory Analysis of 6 Cases.

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Gartaganis, Sotirios P; Prahs, Philipp; Lazari, Eftichia D; Gartaganis, Panos S; Helbig, Horst; Koutsoukos, Petros G

2016-08-01

To investigate the nature and characteristic features of deposits causing opacification of intraocular lenses (IOLs) based on the examination of clinical findings using scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX) analysis. Retrospective, observational case series. This is a multicenter study of 6 hydrophilic acrylic IOLs (Lentis LS-502-1; Oculentis GmbH, Berlin, Germany) with a hydrophobic surface that were explanted from 5 patients because of opacification. Three patients had an uncomplicated phacoemulsification. One patient underwent combined phacoemulsification and pars plana vitrectomy for retinal detachment and later silicone oil endotamponade owing to redetachment. The last patient had a pars plana vitrectomy and silicone oil instillation combined with phacoemulsification for tractive retinal detachment and diabetic retinopathy. The explanted lenses were submitted to our laboratory and were examined by SEM and EDX in order to identify the morphologic features and the composition of the deposits. SEM and EDX analyses confirmed the presence of calcific deposits in the interior of the opacified hydrophilic IOLs, with a pattern showing the formation of lumps on the surface. The lumps were due to subsurface formation of calcium phosphate crystalline deposits. The crystallite clusters seemed to diffuse from the IOL interior to the surface. We demonstrated the calcification pattern of the hydrophilic IOL (Lentis LS-502-1) with a hydrophobic surface. Although hydrophilic acrylic lenses have a hydrophobic surface, the development of calcification is a possible threat initiating from the hydrophilic subsurface of the IOLs. Copyright © 2016 Elsevier Inc. All rights reserved.

Antibacterial Activity of Hydrophobic Composite Materials Containing a Visible-Light-Sensitive Photocatalyst

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Kentaro Yamauchi

2011-01-01

Full Text Available The conventional superhydrophobic surface offered by PTFE provides no sterilization performance and is not sufficiently repellent against organic liquids. These limit PTFE's application in the field of disinfection and result a lack of durability. N-doped TiO2 photocatalyst added PTFE composite material was developed to remedy these shortcomings. This paper reports the surface characteristics, and the bactericidal and self-cleaning performance of the newly-developed composite material. The material exhibited a contact angle exceeding 150 degrees consistent with its hydrophobicity despite the inclusion of the hydrophilic N-doped TiO2. The surface free energy obtained for this composite was 5.8 mN/m. Even when exposed to a weak fluorescent light intensity (100 lx for 24 hours, the viable cells of gram-negative E. coli on the 12% N-doped TiO2-PTFE film were reduced 5 logs. The higher bactericidal activity was also confirmed on the gram-positive MRSA. Compared with the N-doped TiO2 coating only, the inactivation rate of the composite material was significantly enhanced. Utilizing the N-doped TiO2 with the PTFE composite coating could successfully remove, by UV illumination, oleic acid adsorbed on its surface. These results demonstrate the potential applicability of the novel N-doped TiO2 photocatalyst hydrophobic composite material for both indoor antibacterial action and outdoor contamination prevention.

Artificial hairy surfaces with a nearly perfect hydrophobic response.

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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.

Facile fabrication of hydrophobic surfaces on mechanically alloyed-Mg/HA/TiO{sub 2}/MgO bionanocomposites

Energy Technology Data Exchange (ETDEWEB)

Khalajabadi, Shahrouz Zamani [Medical Devices and Technology Group (MEDITEG), Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia); Abdul Kadir, Mohammed Rafiq, E-mail: rafiq@biomedical.utm.my [Medical Devices and Technology Group (MEDITEG), Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia); Izman, Sudin; Mohd Yusop, Mohd Zamri [Department of Materials, Manufacturing and Industrial Engineering, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia)

2015-01-01

Highlights: • Mg/HA/TiO{sub 2}-based nanocomposite was produced using mechanical alloying. • The hydrophobic surface coverage was fabricated on the mechanical alloyed samples by annealing. • The morphological characteristics, phase evolution and wettability of nanocomposites and the hydrophobic surface coverage were investigated. • The activation energies and reaction kinetic of the powder mixture of nanocomposites were calculated. - Abstract: The effect of mechanical alloying and post-annealing on the phase evolution, microstructure, wettability and thermal stability of Mg–HA–TiO{sub 2}–MgO composites was investigated in this study. Phase evolution and microstructure analysis were performed using X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy and atomic force microscopy, as well as the wettability determined by contact angle measurements with SBF. The 16-h mechanical alloying resulted in the formation of MgTiO{sub 3}, CaTiO{sub 3}, Mg{sub 3}(PO{sub 4}){sub 2} and Mg(OH){sub 2} phases and a decrease in wettability of the nanocomposites. A hydrophobic film with hierarchical structures comprising nanoflakes of MgTiO{sub 3}, nano-cuboids of CaTiO{sub 3}, microspheres of Mg{sub 3}(PO{sub 4}){sub 2} and Mg(OH){sub 2} was successfully constructed on the surface of the Mg-based nanocomposites substrates as a result of the post-annealing process. After 1-h annealing at 630 °C, the synthesized hydrophobic surface on the nanocomposite substrates decreased the wettability, as the 8-h-mechanically alloyed samples exhibited a contact angle close to 93°. The formation activation energies and reaction kinetics of the powder mixture were investigated using differential thermal analysis and thermal gravimetric analysis. The released heat, weight loss percentage and reaction kinetics increased, while the formation activation energies of the exothermic reactions decreased following an increase in the milling time.

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

Analysis of hydrophobic interactions of antagonists with the beta2-adrenergic receptor.

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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.

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.

Maternal risk factors predicting child physical characteristics and dysmorphology in fetal alcohol syndrome and partial fetal alcohol syndrome.

Science.gov (United States)

May, Philip A; Tabachnick, Barbara G; Gossage, J Phillip; Kalberg, Wendy O; Marais, Anna-Susan; Robinson, Luther K; Manning, Melanie; Buckley, David; Hoyme, H Eugene

2011-12-01

Previous research in South Africa revealed very high rates of fetal alcohol syndrome (FAS), of 46-89 per 1000 among young children. Maternal and child data from studies in this community summarize the multiple predictors of FAS and partial fetal alcohol syndrome (PFAS). Sequential regression was employed to examine influences on child physical characteristics and dysmorphology from four categories of maternal traits: physical, demographic, childbearing, and drinking. Then, a structural equation model (SEM) was constructed to predict influences on child physical characteristics. Individual sequential regressions revealed that maternal drinking measures were the most powerful predictors of a child's physical anomalies (R² = .30, p < .001), followed by maternal demographics (R² = .24, p < .001), maternal physical characteristics (R²=.15, p < .001), and childbearing variables (R² = .06, p < .001). The SEM utilized both individual variables and the four composite categories of maternal traits to predict a set of child physical characteristics, including a total dysmorphology score. As predicted, drinking behavior is a relatively strong predictor of child physical characteristics (β = 0.61, p < .001), even when all other maternal risk variables are included; higher levels of drinking predict child physical anomalies. Overall, the SEM model explains 62% of the variance in child physical anomalies. As expected, drinking variables explain the most variance. But this highly controlled estimation of multiple effects also reveals a significant contribution played by maternal demographics and, to a lesser degree, maternal physical and childbearing variables. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

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

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.

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.

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.

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.

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.

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

Fouling Characteristics of Dissolved Organic Matter in Papermaking Process Water on Polyethersulfone Ultrafiltration Membranes

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Wenpeng Su

2015-07-01

Full Text Available In the papermaking industry, closure of process water (whitewater circuits has been used to reduce fresh water consumption. Membrane separation technology has potential for use in treating process water for recirculation. The purpose of this study was to reveal the fouling characteristics of a polyethersulfone (PES ultrafiltration membrane caused by dissolved organic matter (DOM in process water. Ultrafiltration membranes (UF and DAX ion exchange resins were applied to characterize the molecular weight (MW and hydrophilicity distribution of DOM. The interactions between various fractions of DOM and a PES ultrafiltration membrane were investigated. The membrane fouling characteristics were elucidated by examining the filtration resistances and linearized Herman’s blocking models. The results demonstrated that the membrane was fouled significantly by much of the MW distribution. The membrane was fouled more significantly by the low MW fraction rather than the high MW fraction. The filtration resistances and the fitted equation of Hermia’s laws indicated that hydrophilic organics were the main foulants. The hydrophilic organics partially block the membrane pores and form intermediate blocking, reducing the effective filtration area, while the hydrophobic organics form a gel layer or cake on the surface of the membrane.

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.

Hydrophobic Calcium Carbonate for Cement Surface

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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.

Defect Pattern Recognition Based on Partial Discharge Characteristics of Oil-Pressboard Insulation for UHVDC Converter Transformer

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Wen Si

2018-03-01

Full Text Available The ultra high voltage direct current (UHVDC transmission system has advantages in delivering electrical energy over long distance at high capacity. UHVDC converter transformer is a key apparatus and its insulation state greatly affects the safe operation of the transmission system. Partial discharge (PD characteristics of oil-pressboard insulation under combined AC-DC voltage are the foundation for analyzing the insulation state of UHVDC converter transformers. The defect pattern recognition based on PD characteristics is an important part of the state monitoring of converter transformers. In this paper, PD characteristics are investigated with the established experimental platform of three defect models (needle-plate, surface discharge and air gap under 1:1 combined AC-DC voltage. The different PD behaviors of three defect models are discussed and explained through simulation of electric field strength distribution and discharge mechanism. For the recognition of defect types when multiple types of sources coexist, the Random Forests algorithm is used for recognition. In order to reduce the computational layer and the loss of information caused by the extraction of traditional features, the preprocessed single PD pulses and phase information are chosen to be the features for learning and test. Zero-padding method is discussed for normalizing the features. Based on the experimental data, Random Forests and Least Squares Support Vector Machine are compared in the performance of computing time, recognition accuracy and adaptability. It is proved that Random Forests is more suitable for big data analysis.

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.

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.

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

Patterning Method for Silver Nanoparticle Electrodes in Fully Solution-Processed Organic Thin-Film Transistors Using Selectively Treated Hydrophilic and Hydrophobic Surfaces

Science.gov (United States)

Fukuda, Kenjiro; Takeda, Yasunori; Kobayashi, Yu; Shimizu, Masahiro; Sekine, Tomohito; Kumaki, Daisuke; Kurihara, Masato; Sakamoto, Masatomi; Tokito, Shizuo

2013-05-01

Fully solution-processed organic thin-film transistor (OTFT) devices have been fabricated with simple patterning process at a relatively low process temperature of 100 °C. In the patterning process, a hydrophobic amorphous fluoropolymer material, which was used as the gate dielectric layer and the underlying base layer, was treated with an oxygen plasma to selectively change its surface wetting properties from hydrophobic to hydrophilic. Silver source and drain electrodes were successfully formed in the treated areas with highly uniform line widths and without residues between the electrodes. Nonuniformities in the thickness of the silver electrodes originating from the “coffee-ring” effect were suppressed by optimizing the blend of solvents used with the silver nanoparticles, such that the printed electrodes are appropriate for bottom-gate OTFT devices. A fully solution-processed OTFT device using a polymer semiconductor material (PB16TTT) exhibited good electrical performance with no hysteresis in its transfer characteristics and with good linearity in its output characteristics. A relatively high carrier mobility of 0.14 cm2 V-1 s-1 and an on/off ratio of 1×105 were obtained with the fabricated TFT device.

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.

Novel strategy in increasing stability and corrosion resistance for super-hydrophobic coating on aluminum alloy surfaces

Energy Technology Data Exchange (ETDEWEB)

Yin Bo [Department of Applied Physics, Chongqing University, Chongqing, 400044 (China); Fang Liang, E-mail: fangliangcqu@yahoo.com.cn [Department of Applied Physics, Chongqing University, Chongqing, 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing, 400044 (China); Tang Anqiong; Huang Qiuliu; Hu Jia; Mao Jianhui [Department of Applied Physics, Chongqing University, Chongqing, 400044 (China); Bai, Ge; Bai, Huan [State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, Chongqing, 400044 (China)

2011-10-15

A novel super-hydrophobic coating was prepared by chemical modification on the anodized aluminum alloy surface. The surface structure was characterized by water contact angle measurement, scanning electron microscopy (SEM), and the composition was measured by X-ray photoelectron spectroscopy (XPS). The corrosion behavior of the super-hydrophobic coating was evaluated by the polarization curve and the electrochemical impedance spectroscopy (EIS). It was found that the static water contact angle on the surface of super-hydrophobic coating was as high as 167.7 {+-} 1.2 deg., and the sliding angle was 5 deg. The super-hydrophobic coating resulted in excellent corrosion resistance property and the super-hydrophobic coating showed a good stability.

Decoding Structural Properties of a Partially Unfolded Protein Substrate: En Route to Chaperone Binding.

Science.gov (United States)

Nagpal, Suhani; Tiwari, Satyam; Mapa, Koyeli; Thukral, Lipi

2015-01-01

Many proteins comprising of complex topologies require molecular chaperones to achieve their unique three-dimensional folded structure. The E.coli chaperone, GroEL binds with a large number of unfolded and partially folded proteins, to facilitate proper folding and prevent misfolding and aggregation. Although the major structural components of GroEL are well defined, scaffolds of the non-native substrates that determine chaperone-mediated folding have been difficult to recognize. Here we performed all-atomistic and replica-exchange molecular dynamics simulations to dissect non-native ensemble of an obligate GroEL folder, DapA. Thermodynamics analyses of unfolding simulations revealed populated intermediates with distinct structural characteristics. We found that surface exposed hydrophobic patches are significantly increased, primarily contributed from native and non-native β-sheet elements. We validate the structural properties of these conformers using experimental data, including circular dichroism (CD), 1-anilinonaphthalene-8-sulfonic acid (ANS) binding measurements and previously reported hydrogen-deutrium exchange coupled to mass spectrometry (HDX-MS). Further, we constructed network graphs to elucidate long-range intra-protein connectivity of native and intermediate topologies, demonstrating regions that serve as central "hubs". Overall, our results implicate that genomic variations (or mutations) in the distinct regions of protein structures might disrupt these topological signatures disabling chaperone-mediated folding, leading to formation of aggregates.

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.

Limiting hydrophobic behavior and reflectance response of dragonfly and damselfly wings

Science.gov (United States)

Aideo, Swati Nawami; Mohanta, Dambarudhar

2016-11-01

In this work, through water contact angle (CA) measurements, we explore hydrophobic behavior of different parts of the hind wings of a dragonfly, Gynacantha Dravida and of a damselfly, Pseudagrion Microcephalum. As we move from the basal to distal region, the contact angle (θ) was found to vary in the range of 120-136° for both the species. Moreover, the wing of the dragonfly was seen to be more hydrophobic than that of the damselfly one. An attempt has also been made to link roughness factor (rφ) and solid-water fraction (φ) through the simplified Wenzel and Cassie-Baxter models. We noticed that, rφ and φ tend to follow a linear relation that gives rφ = 1.47 in the limit, Δθ segment was believed to be stronger than that of the basal part, the edge parts of the dragonfly and damselfly wings exhibited exponential associated growing trends with increasing wavelength. The relative reflectance response, corresponding to ∼494 nm and 370 nm peaks, gets nearly doubled for the edge specimen as compared to the distal and basal parts. The edge- specimen, which comprises of rectangular shaped, periodic microstructures, displayed carotenoid based two broad peak maxima at ∼422 nm and ∼494 nm. The surface roughness which arises through the distribution of oblate-shaped nano-fibrils is believed to be the basis of sub-surface volume scattering. Interrelating nanostructure surface roughness based wettability and reflectance characteristics would provide new insights on structure-property relationship in naturally available soft matter systems including templates of biological origin.

On the Feasibility of Gap Detection of Power Transformer Partial Discharge UHF Signals: Gap Propagation Characteristics of Electromagnetic Waves

Directory of Open Access Journals (Sweden)

Xiaoxing Zhang

2017-10-01

Full Text Available This study analyzed the transformer electromagnetic gap propagation characteristics. The influence of gap size is also analyzed, and the results experimentally verified. The obtained results indicated that the gap propagation characteristics of electromagnetic wave signals radiated by the partial discharge (PD source in different directions are substantially different. The intensity of the electromagnetic wave in the gap reaches a maximum at a gap height of 1 cm; and inside the gap, the intensity of the electromagnetic wave depicted an increasing trend at the tail area of the gap. Finally, from the obtained results, some suggestions on where to install sensors in practical systems for ultra high frequency (UHF PD signal detection in the transformer gap are provided. The obtained results confirmed the feasibility of using this approach. These results can be seen as a benchmark and a challenge for further research in this field.

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.

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 - .

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

Structural Characteristics of Homogeneous Hydrophobic Ionic Liquid-HNO3-H2O Ternary System: Experimental Studies and Molecular Dynamics Simulations.

Science.gov (United States)

Fu, Jing; Yang, Y Isaac; Zhang, Jun; Chen, Qingde; Shen, Xinghai; Gao, Yi Qin

2016-06-16

The solubility of water in the hydrophobic ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][NTf2]) increases significantly in the presence of HNO3. [C2mim][NTf2] is completely miscible with HNO3 but immiscible with water. The triangular phase diagram of the ternary system [C2mim][NTf2]-HNO3-H2O was determined at 300.1 K. The homogeneous [C2mim][NTf2]-HNO3-H2O phase is thermodynamically stable, while it can be separated into two phases with an increase of water content. Experiments (electrospray ionization mass spectrometry, Fourier transform infrared spectrometry, and (1)H-nuclear magnetic resonance spectrometry) and molecular dynamics simulations were carried out to investigate the interaction between [C2mim][NTf2], HNO3, and water in the homogeneous phase. It was found that NO3(-) ions interact with both C2mim(+) and water via H-bonding and act as a "bridge" to induce a large amount of water to be dissolved in the hydrophobic IL phase. This confirms that the complexes [C2mim-NTf2-C2mim](+) and [NTf2-C2mim-NTf2](-) exist in the homogeneous [C2mim][NTf2]-HNO3-H2O system at the concentration of HNO3 up to 27.01 wt % and of water as high as 20.74 wt %.

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

Modeling, investigation and formulation of hydrophobic coatings for potential self-cleaning applications

Science.gov (United States)

Rios, Pablo Fabian

Self-cleaning surfaces have received a great deal of attention, both in research and commercial applications. Transparent and non-transparent self-cleaning surfaces are highly desired. The Lotus flower is a symbol of purity in Asian cultures, even when rising from muddy waters it stays clean and untouched by dirt. The Lotus leaf "self-cleaning" surface is hydrophobic and rough, showing a two-layer morphology. While hydrophobicity produces a high contact angle, surface morphology reduces the adhesion of dirt and water to the surface, thus water drops slide easily across the leaf carrying the dirt particles with them. Nature example in the Lotus-effect and extensive scientific research on related fields have rooted wide acceptance that high hydrophobicity can be obtained only by a proper combination of surface chemistry and roughness. Most researchers relate hydrophobicity to a high contact angle. However, the contact angle is not the only parameter that defines liquid-solid interactions. An additional parameter, the sliding angle, related to the adhesion between the liquid drop and the solid surface is also important in cases where liquid sliding is involved, such as self-cleaning applications. In this work, it is postulated that wetting which is related to the contact angle, and interfacial adhesion, which is related to the sliding angle, are interdependent phenomena and have to be considered simultaneously. A variety of models that relate the sliding angle to forces developed along the contact line between a liquid drop and a solid surface have been proposed in the literature. A new model is proposed here that quantifies the drop sliding phenomenon, based also on the interfacial adhesion across the contact area of the liquid/solid interface. The effects of roughness and chemical composition on the contact and sliding angles of hydrophobic smooth and rough surfaces were studied theoretically and experimentally. The validity of the proposed model was investigated

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

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,

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.

Effect of wall wettability on flow characteristics of gas-liquid two-phase flow

International Nuclear Information System (INIS)

Uematsu, Junichi; Abe, Kazuya; Hazuku, Tatsuya; Takamasa, Tomoji; Hibiki, Takashi

2007-01-01

To evaluate the effect of surface wettability in pipe wall on flow characteristics in a vertical upward gas-liquid to-phase flow, visualization study was performed using three test pipes, namely an acrylic pipe, a hydrophilic pipe, a hydrophobic pipe. Such basic flow characteristics as flow patterns and void fraction were investigated in these three pipes. In the hydrophilic pipe, the slug flow-to-churn flow transition boundary was shifted to higher gas velocity condition at a given liquid velocity, whereas the churn flow-to-annular flow transition boundary was shifted to lower gas velocity condition at a given liquid velocity. In the hydrophobic pipe, the inverted-churn flow regime was observed in the region where the churn flow regime was observed in the acrylic pipe, whereas the droplet flow regime was observed in the region where the annular flow regime was observed in the acrylic pipe. At high-gas flow rate condition, the mean void fraction in the hydrophobic pipe took relatively higher value to that in the acrylic pipe. (author)

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.

On formation of a partially coherent beam in a stable-resonator laser

International Nuclear Information System (INIS)

Suvorov, A A

2010-01-01

A new method involving the expansion of the field coherence function in partially coherent modes - the eigensolutions of the problem for the second-order coherence function in a stable resonator - is proposed for the theoretical description of the process of multimode laser beam formation. The method for solving the problem for arbitrary partially coherent modes is formulated and the expressions for these modes are derived in the general form. The characteristics of the fundamental partially coherent mode, which coincides with the coherence function of a Gaussian partially coherent beam, are analysed in detail. The partially coherent modes are shown to possess two spatial scales - the effective radius and the coherence radius, which makes them a convenient tool for solving the problem of generation of a partially coherent beam. It is found that the unambiguous relation between the characteristics of partially coherent modes and the stable-resonator parameters is achieved by involving into consideration not only the process of the beam formation by the resonator mirrors but also the process of interaction of radiation with the active laser medium. (laser beams and resonators)

Combustion characteristics of lemongrass (Cymbopogon flexuosus oil in a partial premixed charge compression ignition engine

Directory of Open Access Journals (Sweden)

Avinash Alagumalai

2015-09-01

Full Text Available Indeed, the development of alternate fuels for use in internal combustion engines has traditionally been an evolutionary process in which fuel-related problems are met and critical fuel properties are identified and their specific limits defined to resolve the problem. In this regard, this research outlines a vision of lemongrass oil combustion characteristics. In a nut-shell, the combustion phenomena of lemongrass oil were investigated at engine speed of 1500 rpm and compression ratio of 17.5 in a 4-stroke cycle compression ignition engine. Furthermore, the engine tests were conducted with partial premixed charge compression ignition-direct injection (PCCI-DI dual fuel system to profoundly address the combustion phenomena. Analysis of cylinder pressure data and heat-release analysis of neat and premixed lemongrass oil were demonstrated in-detail and compared with conventional diesel. The experimental outcomes disclosed that successful ignition and energy release trends can be obtained from a compression ignition engine fueled with lemongrass oil.

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.

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.

Evaluation of hydrophobic materials as matrices for controlled-release drug delivery.

Science.gov (United States)

Quadir, Mohiuddin Abdul; Rahman, M Sharifur; Karim, M Ziaul; Akter, Sanjida; Awkat, M Talat Bin; Reza, Md Selim

2003-07-01

The present study was undertaken to evaluate the effect of different insoluble and erodable wax-lipid based materials and their content level on the release profile of drug from matrix systems. Matrix tablets of theophylline were prepared using carnauba wax, bees wax, stearic acid, cetyl alcohol, cetostearyl alcohol and glyceryl monostearate as rate-retarding agents by direct compression process. The release of theophylline from these hydrophobic matrices was studied over 8-hours in buffer media of pH 6.8. Statistically significant difference was found among the drug release profile from different matrices. The release kinetics was found to be governed by the type and content of hydrophobic materials in the matrix. At lower level of wax matrices (25%), a potential burst release was observed with all the materials being studied. Bees wax could not exert any sustaining action while an extensive burst release was found with carnauba wax at this hydrophobic load. Increasing the concentration of fat-wax materials significantly decreased the burst effect of drug from the matrix. At higher hydrophobic level (50% of the matrix), the rate and extent of drug release was significantly reduced due to increased tortuosity and reduced porosity of the matrix. Cetostearyl alcohol imparted the strongest retardation of drug release irrespective of fat-wax level. Numerical fits indicate that the Higuchi square root of time model was the most appropriate one for describing the release profile of theophylline from hydrophobic matrices. The release mechanism was also explored and explained with biexponential equation. Application of this model indicates that Fickian or case I kinetics is the predominant mechanism of drug release from these wax-lipid matrices. The mean dissolution time (MDT) was calculated for all the formulations and the highest MDT value was obtained with cetostearyl matrix. The greater sustaining activity of cetostearyl alcohol can be attributed to some level of

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

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...

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.

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

Decreasing the emissions of a partially premixed gasoline fueled compression ignition engine by means of injection characteristics and EGR

Directory of Open Access Journals (Sweden)

Nemati Arash

2011-01-01

Full Text Available This paper is presented in order to elucidate some numerical investigations related to a partially premixed gasoline fuelled engine by means of three dimensional CFD code. Comparing with the diesel fuel, gasoline has lower soot emission because of its higher ignition delay. The application of double injection strategy reduces the maximum heat release rate and leads to the reduction of NOx emission. For validation of the model, the results for the mean in-cylinder pressure, H.R.R., NOx and soot emissions are compared with the corresponding experimental data and show good levels of agreement. The effects of injection characteristics such as, injection duration, spray angle, nozzle hole diameter, injected fuel temperature and EGR rate on combustion process and emission formation are investigated yielding the determination of the optimal point thereafter. The results indicated that optimization of injection characteristics leads to simultaneous reduction of NOx and soot emissions with negligible change in IMEP.

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.

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.

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.

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

Preparation of a novel dual-function strong cation exchange/hydrophobic interaction chromatography stationary phase for protein separation.

Science.gov (United States)

Zhao, Kailou; Yang, Li; Wang, Xuejiao; Bai, Quan; Yang, Fan; Wang, Fei

2012-08-30

We have explored a novel dual-function stationary phase which combines both strong cation exchange (SCX) and hydrophobic interaction chromatography (HIC) characteristics. The novel dual-function stationary phase is based on porous and spherical silica gel functionalized with ligand containing sulfonic and benzyl groups capable of electrostatic and hydrophobic interaction functionalities, which displays HIC character in a high salt concentration, and IEC character in a low salt concentration in mobile phase employed. As a result, it can be employed to separate proteins with SCX and HIC modes, respectively. The resolution and selectivity of the dual-function stationary phase were evaluated under both HIC and SCX modes with standard proteins and can be comparable to that of conventional IEC and HIC columns. More than 96% of mass and bioactivity recoveries of proteins can be achieved in both HIC and SCX modes, respectively. The results indicated that the novel dual-function column could replace two individual SCX and HIC columns for protein separation. Mixed retention mechanism of proteins on this dual-function column based on stoichiometric displacement theory (SDT) in LC was investigated to find the optimal balance of the magnitude of electrostatic and hydrophobic interactions between protein and the ligand on the silica surface in order to obtain high resolution and selectivity for protein separation. In addition, the effects of the hydrophobicity of the ligand of the dual-function packings and pH of the mobile phase used on protein separation were also investigated in detail. The results show that the ligand with suitable hydrophobicity to match the electrostatic interaction is very important to prepare the dual-function stationary phase, and a better resolution and selectivity can be obtained at pH 6.5 in SCX mode. Therefore, the dual-function column can replace two individual SCX and HIC columns for protein separation and be used to set up two-dimensional liquid

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.

Collision effects on propagation characteristics of electromagnetic waves in a sub-wavelength plasma slab of partially ionized dense plasmas

Science.gov (United States)

Bowen, LI; Zhibin, WANG; Qiuyue, NIE; Xiaogang, WANG; Fanrong, KONG; Zhenyu, WANG

2018-01-01

Intensive collisions between electrons and neutral particles in partially ionized plasmas generated in atmospheric/sub-atmospheric pressure environments can sufficiently affect the propagation characteristics of electromagnetic waves, particularly in the sub-wavelength regime. To investigate the collisional effect in such plasmas, we introduce a simplified plasma slab model with a thickness on the order of the wavelength of the incident electromagnetic wave. The scattering matrix method (SMM) is applied to solve the wave equation in the plasma slab with significant nonuniformity. Results show that the collisions between the electrons and the neutral particles, as well as the incident angle and the plasma thickness, can disturb the transmission and reduce reflection significantly.

Partial chord diagrams and matrix models

DEFF Research Database (Denmark)

Andersen, Jørgen Ellegaard; Fuji, Hiroyuki; Manabe, Masahide

In this article, the enumeration of partial chord diagrams is discussed via matrix model techniques. In addition to the basic data such as the number of backbones and chords, we also consider the Euler characteristic, the backbone spectrum, the boundary point spectrum, and the boundary length spe...

Dye-based coatings for hydrophobic valves and their application to polymer labs-on-a-chip

Science.gov (United States)

Riegger, L.; Mielnik, M. M.; Gulliksen, A.; Mark, D.; Steigert, J.; Lutz, S.; Clad, M.; Zengerle, R.; Koltay, P.; Hoffmann, J.

2010-04-01

We provide a method for the selective surface patterning of microfluidic chips with hydrophobic fluoropolymers which is demonstrated by the fabrication of hydrophobic valves via dispensing. It enables efficient optical quality control for the surface patterning thus permitting the low-cost production of highly reproducible hydrophobic valves. Specifically, different dyes for fluoropolymers enabling visual quality control (QC) are investigated, and two fluoropolymer-solvent-dye solutions based on fluorescent quantum dots (QD) and carbon black (CB) are presented in detail. The latter creates superhydrophobic surfaces on arbitrary substrates, e.g. chips made from cyclic olefin copolymer (COC, water contact angle = 157.9°), provides good visibility for the visual QC in polymer labs-on-a-chip and increases the burst pressures of the hydrophobic valves. Finally, an application is presented which aims at the on-chip amplification of mRNA based on defined flow control by hydrophobic valves is presented. Here, the optimization based on QC in combination with the Teflon-CB coating improves the burst pressure reproducibility from 14.5% down to 6.1% compared to Teflon-coated valves.

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

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...

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., ...

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.

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.

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.

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.

A network of hydrophobic residues impeding helix alphaC rotation maintains latency of kinase Gcn2, which phosphorylates the alpha subunit of translation initiation factor 2.

Science.gov (United States)

Gárriz, Andrés; Qiu, Hongfang; Dey, Madhusudan; Seo, Eun-Joo; Dever, Thomas E; Hinnebusch, Alan G

2009-03-01

Kinase Gcn2 is activated by amino acid starvation and downregulates translation initiation by phosphorylating the alpha subunit of translation initiation factor 2 (eIF2alpha). The Gcn2 kinase domain (KD) is inert and must be activated by tRNA binding to the adjacent regulatory domain. Previous work indicated that Saccharomyces cerevisiae Gcn2 latency results from inflexibility of the hinge connecting the N and C lobes and a partially obstructed ATP-binding site in the KD. Here, we provide strong evidence that a network of hydrophobic interactions centered on Leu-856 also promotes latency by constraining helix alphaC rotation in the KD in a manner relieved during amino acid starvation by tRNA binding and autophosphorylation of Thr-882 in the activation loop. Thus, we show that mutationally disrupting the hydrophobic network in various ways constitutively activates eIF2alpha phosphorylation in vivo and bypasses the requirement for a key tRNA binding motif (m2) and Thr-882 in Gcn2. In particular, replacing Leu-856 with any nonhydrophobic residue activates Gcn2, while substitutions with various hydrophobic residues maintain kinase latency. We further provide strong evidence that parallel, back-to-back dimerization of the KD is a step on the Gcn2 activation pathway promoted by tRNA binding and autophosphorylation. Remarkably, mutations that disrupt the L856 hydrophobic network or enhance hinge flexibility eliminate the need for the conserved salt bridge at the parallel dimer interface, implying that KD dimerization facilitates the reorientation of alphaC and remodeling of the active site for enhanced ATP binding and catalysis. We propose that hinge remodeling, parallel dimerization, and reorientation of alphaC are mutually reinforcing conformational transitions stimulated by tRNA binding and secured by the ensuing autophosphorylation of T882 for stable kinase activation.

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.

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.

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.

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.

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

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

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.

Conversion of hydrophilic SiOC nanofibrous membrane to robust hydrophobic materials by introducing palladium

Science.gov (United States)

Wu, Nan; Wan, Lynn Yuqin; Wang, Yingde; Ko, Frank

2017-12-01

Hydrophobic ceramic nanofibrous membranes have wide applications in the fields of high-temperature filters, oil/water separators, catalyst supports and membrane reactors, for their water repellency property, self-cleaning capability, good environmental stability and long life span. In this work, we fabricated an inherently hydrophobic ceramic nanofiber membrane without any surface modification through pyrolysis of electrospun polycarbosilane nanofibers. The hydrophobicity was introduced by the hierarchical microstructure formed on the surface of the nanofibers and the special surface composition by the addition of trace amounts of palladium. Furthermore, the flexible ceramic mats demonstrated robust chemical resistance properties with consistent hydrophobicity over the entire pH value range and effective water-in-oil emulsion separation performance. Interestingly, a highly cohesive force was found between water droplet and the ceramic membranes, suggesting their great potentials in micro-liquid transportation. This work provides a new route for adjusting the composition of ceramic surface and flexible, recyclable and multifunctional ceramic fibrous membranes for utilization in harsh environments.

Tailoring the surface chemical bond states of the NbN films by doping Ag: Achieving hard hydrophobic surface

Energy Technology Data Exchange (ETDEWEB)

Ren, Ping; Zhang, Kan; Du, Suxuan [Department of Materials Science, State Key Laboratory of Superhard Materials, and Key Laboratory of Automobile Materials, MOE, Jilin University, Changchun, 130012 (China); Meng, Qingnan [College of Construction Engineering, Jilin University, Changchun, 130026 (China); He, Xin [Department of Materials Science, State Key Laboratory of Superhard Materials, and Key Laboratory of Automobile Materials, MOE, Jilin University, Changchun, 130012 (China); Wang, Shuo [Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871 (China); Wen, Mao, E-mail: wenmao225@jlu.edu.cn [Department of Materials Science, State Key Laboratory of Superhard Materials, and Key Laboratory of Automobile Materials, MOE, Jilin University, Changchun, 130012 (China); Zheng, Weitao, E-mail: WTZheng@jlu.edu.cn [Department of Materials Science, State Key Laboratory of Superhard Materials, and Key Laboratory of Automobile Materials, MOE, Jilin University, Changchun, 130012 (China)

2017-06-15

Highlights: • Intrinsically hydrophilic NbN films can transfer to hydrophobic Nb-Ag-N films by doping Ag atoms into NbN sublattice. • Solute Ag can promote that the hydrophobic Ag{sub 2}O groups formed on the Nb-Ag-N film surface through self-oxidation. • The present work may provide a straightforward approach for the production of robust hydrophobic ceramic surfaces. - Abstract: Robust hydrophobic surfaces based on ceramics capable of withstanding harsh conditions such as abrasion, erosion and high temperature, are required in a broad range of applications. The metal cations with coordinative saturation or low electronegativity are commonly chosen to achieve the intrinsically hydrophobic ceramic by reducing Lewis acidity, and thus the ceramic systems are limited. In this work, we present a different picture that robust hydrophobic surface with high hardness (≥20 GPa) can be fabricated through doping Ag atoms into intrinsically hydrophilic ceramic film NbN by reactive co-sputtering. The transition of wettability from hydrophilic to hydrophobic of Nb-Ag-N films induced by Ag doping results from the appearance of Ag{sub 2}O groups on the films surfaces through self-oxidation, because Ag cations (Ag{sup +}) in Ag{sub 2}O are the filled-shell (4d{sup 10}5S{sup 0}) electronic structure with coordinative saturation that have no tendency to interact with water. The results show that surface Ag{sub 2}O benefited for hydrophobicity comes from the solute Ag atoms rather than precipitate metal Ag, in which the more Ag atoms incorporated into Nb-sublattice are able to further improve the hydrophobicity, whereas the precipitation of Ag nanoclusters would worsen it. The present work opens a window for fabricating robust hydrophobic surface through tailoring surface chemical bond states by doping Ag into transition metal nitrides.

Low proliferation and high apoptosis of osteoblastic cells on hydrophobic surface are associated with defective Ras signaling

International Nuclear Information System (INIS)

Chang, Eun-Ju; Kim, Hong-Hee; Huh, Jung-Eun; Kim, In-Ae; Seung Ko, Jea; Chung, Chong-Pyoung; Kim, Hyun-Man

2005-01-01

The hydrophobic (HPB) nature of most polymeric biomaterials has been a major obstacle in using those materials in vivo due to low compatibility with cells. However, there is little knowledge of the molecular detail to explain how surface hydrophobicity affects cell responses. In this study, we compared the proliferation and apoptosis of human osteoblastic MG63 cells adhered to hydrophilic (HPL) and hydrophobic surfaces. On the hydrophobic surface, less formation of focal contacts and actin stress fibers, a delay in cell cycle progression, and an increase in apoptosis were observed. By using fibroblast growth factor 1 (FGF1) as a model growth factor, we also investigated intracellular signaling pathways on hydrophilic and hydrophobic surfaces. The activation of Ras, Akt, and ERK by FGF1 was impaired in MG63 cells on the hydrophobic surface. The overexpression of constitutively active form of Ras and Akt rescued those cells from apoptosis and recovered cell cycle progression. Furthermore, their overexpression also restored the actin cytoskeletal organization on the hydrophobic surface. Finally, the proliferative, antiapoptotic, and cytoskeletal effects of constitutively active Ras in MG63 cells on the hydrophobic surface were blocked by wortmannin and PD98059 that inhibit Akt and ERK activation, respectively. Therefore, our results suggest that the activation of Ras and its downstream molecules Akt and ERK to an appropriate level is one of crucial elements in the determination of osteoblast cell responses. The Ras pathway may represent a cell biological target that should be considered for successful surface modification of biomaterials to induce adequate cell responses in the bone tissue

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.

Nanostructured hydrophobic DC sputtered inorganic oxide coating for outdoor glass insulators

Energy Technology Data Exchange (ETDEWEB)

Dave, V. [Department of Electrical Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Institute Instrumentation Centre, Indian Institute of Technology, Roorkee, Roorkee 247667 (India); Gupta, H.O. [Department of Electrical Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Chandra, R., E-mail: ramesfic@gmail.com [Institute Instrumentation Centre, Indian Institute of Technology, Roorkee, Roorkee 247667 (India)

2014-03-01

Graphical abstract: - Highlights: • Deposition of contamination on outdoor glass insulators and its physical and economical consequences were discussed. • Synthesis of nanostructured hydrophobic HfO{sub 2} film on glass as a remedial measure by varying DC sputtering power. • Investigated and correlated structural, optical, electrical and hydrophobic properties of HfO{sub 2} films with respect to power. • Optimum results were obtained at a 50 W DC sputtering power. - Abstract: We report the structural, optical and electrical properties of nanostructured hydrophobic inorganic hafnium oxide coating for outdoor glass insulator using DC sputtering technique to combat contamination problem. The properties were studied as a function of DC power. The characterization of the films was done using X-ray diffraction, EDS, surface profilometer, AFM, impedance analyser and water contact angle measurement system. The DC power was varied from 30 to 60 W and found to have a great impact on the properties of hafnium oxide. All the deposited samples were polycrystalline with nanostructured hydrophobic surfaces. The intensity of crystallinity of the film was found to be dependent on sputtering power and hydrophobicity was correlated to the nanoscale roughness of the films. The optical property reveals 80% average transmission for all the samples. The refractive index was found in the range of 1.85–1.92, near to the bulk value. The band gap calculated from transmission data was >5.3 eV for all deposited samples ensuring dielectric nature of the films. Surface energy calculated by two methods was found minimum for the film deposited at 50 W sputtering power. The resistivity was also high enough (∼10{sup 4} Ω cm) to hinder the flow of leakage current through the film. The dielectric constant (ε) was found to be thickness dependent and also high enough (ε{sub max} = 23.12) to bear the large electric field of outdoor insulators.

Startup and operating characteristics of an external air-lift reflux partial nitritation-ANAMMOX integrative reactor.

Science.gov (United States)

Li, Xiang; Huang, Yong; Yuan, Yi; Bi, Zhen; Liu, Xin

2017-08-01

The differences in the physiological characteristics between AOB and ANAMMOX bacteria lead to suboptimal performance when used in a single reactor. In this study, aerobic and anaerobic zones with different survival environments were constructed in a single reactor to realize partitioned culture of AOB and ANAMMOX bacteria. An external air-lift reflux system was formed which used the exhaust from the aeration zone as power to return the effluent to the aeration zone. The reflux system effectively alleviated the large pH fluctuations and promoted NO 2 - -N to rapidly use by ANAMMOX bacteria, effectively inhibiting the activity of NOB. After 95d of running, the nitrogen removal rate increased from the initial 0.21kg/(m 3 ·d) to 3.1kg/(m 3 ·d). FISH analyses further demonstrated that AOB and ANAMMOX bacteria acquired efficient enrichment in the corresponding zone. Thus, this type of integrative reactor may create the environments needed for the partial nitritation-ANAMMOX processing. Copyright © 2017 Elsevier Ltd. All rights reserved.

Decoding Structural Properties of a Partially Unfolded Protein Substrate: En Route to Chaperone Binding

Science.gov (United States)

Nagpal, Suhani; Tiwari, Satyam; Mapa, Koyeli; Thukral, Lipi

2015-01-01

Many proteins comprising of complex topologies require molecular chaperones to achieve their unique three-dimensional folded structure. The E.coli chaperone, GroEL binds with a large number of unfolded and partially folded proteins, to facilitate proper folding and prevent misfolding and aggregation. Although the major structural components of GroEL are well defined, scaffolds of the non-native substrates that determine chaperone-mediated folding have been difficult to recognize. Here we performed all-atomistic and replica-exchange molecular dynamics simulations to dissect non-native ensemble of an obligate GroEL folder, DapA. Thermodynamics analyses of unfolding simulations revealed populated intermediates with distinct structural characteristics. We found that surface exposed hydrophobic patches are significantly increased, primarily contributed from native and non-native β-sheet elements. We validate the structural properties of these conformers using experimental data, including circular dichroism (CD), 1-anilinonaphthalene-8-sulfonic acid (ANS) binding measurements and previously reported hydrogen-deutrium exchange coupled to mass spectrometry (HDX-MS). Further, we constructed network graphs to elucidate long-range intra-protein connectivity of native and intermediate topologies, demonstrating regions that serve as central “hubs”. Overall, our results implicate that genomic variations (or mutations) in the distinct regions of protein structures might disrupt these topological signatures disabling chaperone-mediated folding, leading to formation of aggregates. PMID:26394388

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

Directory of Open Access Journals (Sweden)

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.

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

Interfacial evaluation and hydrophobicity of multi-functional Ni-nanopowder/epoxy composites for self-sensing and actuation

International Nuclear Information System (INIS)

Park, Joung-Man; Wang, Zuo-Jia; Kwon, Dong-Jun; Jang, Jung-Hoon; DeVries, K Lawrence

2010-01-01

Electrical and interfacial properties of Ni-nanopowder/epoxy composites were investigated for self-sensing and actuation. Contact resistance and electrical resistivity were measured using a micro-specimen with a gradient grid of electrical contact on its length. The specimens' self-sensing characteristics were monitored reasonably well under applied cyclic loading. Actuation in an electromagnetic field was evaluated by measurement of induced strain for three wavefunction voltages, i.e. sine, triangular and square. Due to the presence of hydrophobic domains on the heterogeneous surface, the static contact angle of Ni-nanopowder/epoxy composites exhibited hydrophobicity. The specimens responded well in both self-sensing and actuation tests, in electromagnetic fields, due to the intrinsic metallic property of Ni-nanopowder. Displacement of the actuator was evaluated to attain optimum performance as functions of wave type, frequency and voltage. The strain response followed the shape of the applied voltages better, and was much smoother and less erratic for applied voltages with sine and triangular waveforms than it was for voltages with a rectangular waveform. This is attributed to the sudden changes in voltage in the latter case. Such self-sensing and actuation, in conductive Ni-nanopowder/epoxy composites, might find uses in multi-functional composite devices such as biomimetic and micro-size generators

Scattering Studies of Hydrophobic Monomers in Liposomal Bilayers: An Expanding Shell Model of Monomer Distribution

International Nuclear Information System (INIS)

Richter, Andrew; Dergunov, Sergey; Ganus, Bill; Thomas, Zachary; Pingali, Sai Venkatesh; Urban, Volker S.; Liu, Yun; Porcar, Lionel; Pinkhassik, Eugene

2011-01-01

Hydrophobic monomers partially phase separate from saturated lipids when loaded into lipid bilayers in amounts exceeding a 1:1 monomer/lipid molar ratio. This conclusion is based on the agreement between two independent methods of examining the structure of monomer-loaded bilayers. Complete phase separation of monomers from lipids would result in an increase in bilayer thickness and a slight increase in the diameter of liposomes. A homogeneous distribution of monomers within the bilayer would not change the bilayer thickness and would lead to an increase in the liposome diameter. The increase in bilayer thickness, measured by the combination of small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS), was approximately half of what was predicted for complete phase separation. The increase in liposome diameter, measured by dynamic light scattering (DLS), was intermediate between values predicted for a homogeneous distribution and complete phase separation. Combined SANS, SAXS, and DLS data suggest that at a 1.2 monomer/lipid ratio approximately half of the monomers are located in an interstitial layer sandwiched between lipid sheets. These results expand our understanding of using self-assembled bilayers as scaffolds for the directed covalent assembly of organic nanomaterials. In particular, the partial phase separation of monomers from lipids corroborates the successful creation of nanothin polymer materials with uniform imprinted nanopores. Pore-forming templates do not need to span the lipid bilayer to create a pore in the bilayer-templated films.

Thin film oxygen partial pressure sensor

Science.gov (United States)

Wortman, J. J.; Harrison, J. W.; Honbarrier, H. L.; Yen, J.

1972-01-01

The development is described of a laboratory model oxygen partial pressure sensor using a sputtered zinc oxide thin film. The film is operated at about 400 C through the use of a miniature silicon bar. Because of the unique resistance versus temperature relation of the silicon bar, control of the operational temperature is achieved by controlling the resistance. A circuit for accomplishing this is described. The response of sputtered zinc oxide films of various thicknesses to oxygen, nitrogen, argon, carbon dioxide, and water vapor caused a change in the film resistance. Over a large range, film conductance varied approximately as the square root of the oxygen partial pressure. The presence of water vapor in the gas stream caused a shift in the film conductance at a given oxygen partial pressure. A theoretical model is presented to explain the characteristic features of the zinc oxide response to oxygen.

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

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

Molecular and supramolecular characterization of Ni(II)/losartan hydrophobic nanoprecipitate

Science.gov (United States)

Nascimento, Lorrayne O.; Goulart, Pedro P.; Correa, Jéssyca L.; Abrishamkar, Afshin; Da Silva, Jeferson G.; Mangrich, Antonio S.; de França, Amanda A.; Denadai, Ângelo M. L.

2014-09-01

In this work, a contribution to understanding of the formation of metal(II)/losartan hydrophobic nanoprecipitate is reported. A Ni(II)/Los system was prepared and characterized in solid state and in solution. Solubility studies confirmed the formation of hydrophobic precipitate. Obtained spectroscopic data suggest a sort of coordination between tetrazolic ring as well as OH, and a D4h geometry around the nickel cation. Thermodynamic studies demonstrated that complexation is a stepwise process, with equal enthalpic and entropic contributions for free energy of complexation. DLS and zeta potential titrations indicate the formation of stable nanoparticles of size and charge dependent on the molar ratio. Finally, rheological studies demonstrate a Bingham plastic behavior for Ni(II)/Los suspension.

Effect of hydrophobic paints coating for tritium reduction in concrete materials

International Nuclear Information System (INIS)

Edao, Y.; Fukada, S.; Nishimura, Y.; Katayama, K.; Takeishi, T.; Hatano, Y.; Taguchi, A.

2012-01-01

Highlights: ► Effects of hydrophobic paint coating in tritium transport are investigated. ► Two kinds of paints, acrylic-silicon resin and epoxy resin are used. ► The hydrophobic paints are effective to reduce tritium permeation. ► The effect of tritium reduction of epoxy paint is higher than that of silicon. - Abstract: The effects of hydrophobic paint coating on a concrete material of cement paste on the tritium transport are investigated. The cement paste is coated with two kinds of paints, acrylic-silicon resin paint and epoxy resin paint. We investigated the amount of tritium trapped in the samples exposed to tritiated water vapor by means of sorption and release. It was found that both the hydrophobic paints could reduce effectively tritium permeation during 50 days exposure of tritiated water vapor. The effect of tritium reduction of the epoxy paint was higher than that of silicon while the amount of tritium trapped in the epoxy paint was larger than that of silicon due to difference of the structure. Based on an analysis of a diffusion model, the rate-determining step of tritium migration through cement paste coated with the paints is diffusion through the paints respectively. It was found that tritium was easy to penetrate through silicon because there were many pores or voids in the silicon comparatively. In the case of tritium released from the epoxy paint, it is considered that tritium diffusion in epoxy is slow due to retardation by isotope exchange reaction to water included in epoxy paint.

Conservation of Monuments by a Three-Layered Compatible Treatment of TEOS-Nano-Calcium Oxalate Consolidant and TEOS-PDMS-TiO2 Hydrophobic/Photoactive Hybrid Nanomaterials

Directory of Open Access Journals (Sweden)

Chrysi Kapridaki

2018-04-01

Full Text Available In the conservation of monuments, research on innovative nanocomposites with strengthening, hydrophobic and self-cleaning properties have attracted the interest of the scientific community and promising results have been obtained as a result. In this study, stemming from the need for the compatibility of treatments in terms of nanocomposite/substrate, a three-layered compatible treatment providing strengthening, hydrophobic, and self-cleaning properties is proposed. This conservation approach was implemented treating lithotypes and mortars of different porosity and petrographic characteristics with a three-layered treatment comprising: (a a consolidant, tetraethoxysilane (TEOS-nano-Calcium Oxalate; (b a hydrophobic layer of TEOS-polydimethylsiloxane (PDMS; and (c a self-cleaning layer of TiO2 nanoparticles from titanium tetra-isopropoxide with oxalic acid as hole-scavenger. After the three-layered treatment, the surface hydrophobicity was improved due to PDMS and nano-TiO2 in the interface substrate/atmosphere, as proven by the homogeneity and the Si–O–Ti hetero-linkages of the blend protective/self-cleaning layers observed by Scanning Electron Microscope (SEM, Transmission Electron Microscope (TEM and Fourier-Transform Infrared Spectroscopy (FTIR. The aesthetic, microstructural, mechanical and permeabile compatibility of the majority of treated substrates ranged within acceptability limits. The improved photocatalytic activity, as proven by the total discoloration of methylene blue in the majority of cases, was attributed to the anchorage of TiO2, through the Si–O–Ti bonds to SiO2, in the interface with the atmosphere, thus enhancing photoactivation.

A patient with de-novo partial deletion of Xp (p11.4-pter) and partial duplication of 22q (q11.2-qter).

Science.gov (United States)

Armour, Christine M; McGowan-Jordan, Jean; Lawrence, Sarah E; Bouchard, Amélie; Basik, Mark; Allanson, Judith E

2008-01-01

We report on a girl with partial deletion of Xp and partial duplication of 22q. Family studies demonstrate that both the patient's mother and her nonidentical twin sister carry the corresponding balanced translocation; 46,X,t(X;22)(p11.4;q11.2). This girl has developmental delay, microcephaly, mild dysmorphisms and hearing loss but otherwise shows few of the features described in individuals with duplications of the long arm of chromosome 22. She does manifest characteristics, such as short stature and biochemical evidence of ovarian failure, which are seen in partial or complete Xp deletions and Turner's syndrome.

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.

Organic-Inorganic Hydrophobic Nanocomposite Film with a Core-Shell Structure

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Peng Liu

2016-12-01

Full Text Available A method to prepare novel organic-inorganic hydrophobic nanocomposite films was proposed by a site-specific polymerization process. The inorganic part, the core of the nanocomposite, is a ternary SiO2–Al2O3–TiO2 nanoparticles, which is grafted with methacryloxy propyl trimethoxyl silane (KH570, and wrapped by fluoride and siloxane polymers. The synthesized samples are characterized by transmission electron microscopy (TEM, Fourier transform infrared (FTIR spectrscopy, X-ray diffractometry (XRD, contact angle meter (CA, and scanning electron microscope (SEM. The results indicate that the novel organic-inorganic hydrophobic nanocomposite with a core-shell structure was synthesized successfully. XRD analysis reveals the nanocomposite film has an amorphous structure, and FTIR analysis indicates the nanoparticles react with a silane coupling agent (methacryloxy propyl trimethoxyl silane KH570. Interestingly, the morphology of the nanoparticle film is influenced by the composition of the core. Further, comparing with the film synthesized by silica nanoparticles, the film formed from SiO2–Al2O3–TiO2 nanoparticles has higher hydrophobic performance, i.e., the contact angle is greater than 101.7°. In addition, the TEM analysis reveals that the crystal structure of the particles can be changed at high temperatures.

Partial dynamical symmetries in quantal many-body systems

International Nuclear Information System (INIS)

Van Isacker, P.

2001-01-01

Partial dynamical symmetries are associated with Hamiltonians that are partially solvable. The determination of the properties of a quantal system of N interacting particles moving in an external potential requires the solution of the eigenvalue equation associated with a second-quantised Hamiltonian. In many situations of interest the Hamiltonian commutes with transformations that constitute a symmetry algebra G sym . This characteristic opens a way to find all analytically solvable Hamiltonians. The author gives a brief review of some recent developments

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

Engineered bacterial hydrophobic oligopeptide repeats in a synthetic yeast prion, [REP-PSI+

Directory of Open Access Journals (Sweden)

Fátima eGasset-Rosa

2015-04-01

Full Text Available The yeast translation termination factor Sup35p, by aggregating as the [PSI+] prion, enables ribosomes to read-through stop codons, thus expanding the diversity of the Saccharomyces cerevisiae proteome. Yeast prions are functional amyloids that replicate by templating their conformation on native protein molecules, then assembling as large aggregates and fibers. Prions propagate epigenetically from mother to daughter cells by fragmentation of such assemblies. In the N-terminal prion-forming domain, Sup35p has glutamine/asparagine-rich oligopeptide repeats (OPRs, which enable propagation through chaperone-elicited shearing. We have engineered chimeras by replacing the polar OPRs in Sup35p by up to five repeats of a hydrophobic amyloidogenic sequence from the synthetic bacterial prionoid RepA-WH1. The resulting hybrid, [REP-PSI+], i was functional in a stop codon read-through assay in S. cerevisiae; ii generates weak phenotypic variants upon both its expression or transformation into [psi-] cells; iii these variants correlated with high molecular weight aggregates resistant to SDS during electrophoresis; and iv according to fluorescence microscopy, the fusion of the prion domains from the engineered chimeras to the reporter protein mCherry generated perivacuolar aggregate foci in yeast cells. All these are signatures of bona fide yeast prions. As assessed through biophysical approaches, the chimeras assembled as oligomers rather than as the fibers characteristic of [PSI+]. These results suggest that it is the balance between polar and hydrophobic residues in OPRs what determines prion conformational dynamics. In addition, our findings illustrate the feasibility of enabling new propagation traits in yeast prions by engineering OPRs with heterologous amyloidogenic sequence repeats.

The Manipulation of Hydrophobicity in Catalyst Design for Applications of Aerobic Alcohols Oxidation and Electrocatalytic Water Oxidation

KAUST Repository

Chen, Batian

2016-05-17

Hydrophobicity is the generalized characteristic of non-polar substances that brings about their exclusion from aqueous phases. This property, entropic in its nature, drives key self-assembly and phase separation processes in water. Protein folding, the formation of DNA double helix, the existence of lipid bilayers and the wetting properties of leaf surfaces are all due to hydrophobic interactions. Inspired by Nature, we aimed to use hydrophobicity for creating novel and improved catalytic systems. (I) A number of fluorous amphiphilic star block-copolymers containing a tris(benzyltriazolylmethyl)amine motif have been prepared. These polymers assembled into well-defined nanostructures in water, and their mode of assembly could be controlled by changing the composition of the polymer. The polymers were used for enzyme-inspired catalysis of alcohol oxidation. (II) An enzyme-inspired catalytic system based on a rationally designed multifunctional surfactant was developed. The resulting micelles feature metal-binding sites and stable free radical moieties as well as fluorous pockets that attract and preconcentrate molecular oxygen. In the presence of copper ions, the micelles effect chemoselective aerobic alcohol oxidation under ambient conditions in water, a transformation that is challenging to achieve nonenzymatically. (III) Development of a facile means of photo/electrocatalytic water splitting is one of the main barriers to establishing of a solar hydrogen economy. Of the two half-reactions involved in splitting water into O2 and H2, water oxidation presents the most challenge due to its mechanistic complexity. A practical water oxidation catalyst must be highly active, yet inexpensive and indefinitely stable under harsh oxidative conditions. Here, I shall describe the synthesis of a library of molecular water oxidation catalysts based on the Co complex of tris(2-benzimidazolylmethyl)amine, (BimH)3. A wide range of catalysts differing in their electronic properties

Hydrophobic agglomeration of apatite fines induced by sodium oleate in aqueous solutions

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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

Enhanced washing durability of hydrophobic coating on cellulose fabric using polycarboxylic acids

International Nuclear Information System (INIS)

Huang Wenqi; Xing Yanjun; Yu Yunyi; Shang Songmin; Dai Jinjin

2011-01-01

Nine polycarboxylic acids were used to improve washing durability of hydrophobic cellulose fabric finished by sol-gel method. By simultaneous forming ester-bridge between cellulose and silica layer by ester bond, polycarboxylic acids could anchor silica coating onto cellulose fabric to strengthen the adhesion of organic-inorganic hybrid coating. The wettability of treated fabrics was characterized by water contact angle, spray test and hydrostatic pressure test. The results showed that all investigated polycarboxylic acids could improve the durability. The polycarboxylic acid with proper distance between terminal carboxylic acid groups and number of carboxylic acid groups showed the highest durability. 1,2,3,4-butanetetracarboxylic acid (BTCA) led to the best durability of hydrophobic cellulose fabric with water contact angle of 137.6 o (recovery percentage of 94.2%) after 30 washing times. The effect of BTCA on durability was characterized by scanning electron microscopy. This study demonstrated that the surface treatment using polycarboxylic acids and mixed organosilanes is a promising alternative for achieving durable hydrophobic fabrics.

Ions-induced nanostructuration: effect of specific ionic adsorption on hydrophobic polymer surfaces.

Science.gov (United States)

Siretanu, Igor; Chapel, Jean-Paul; Bastos-González, Delfi; Drummond, Carlos

2013-06-06

The effect of surface charges on the ionic distribution in close proximity to an interface has been extensively studied. On the contrary, the influence of ions (from dissolved salts) on deformable interfaces has been barely investigated. Ions can adsorb from aqueous solutions on hydrophobic surfaces, generating forces that can induce long-lasting deformation of glassy polymer films, a process called ion-induced polymer nanostructuration, IPN. We have found that this process is ion-specific; larger surface modifications are observed in the presence of water ions and hydrophobic and amphiphilic ions. Surface structuration is also observed in the presence of certain salts of lithium. We have used streaming potential and atomic force microscopy to study the effect of dissolved ions on the surface properties of polystyrene films, finding a good correlation between ionic adsorption and IPN. Our results also suggest that the presence of strongly hydrated lithium promotes the interaction of anions with polystyrene surfaces and more generally with hydrophobic polymer surfaces, triggering then the IPN process.

Wetting and other physical characteristics of polycarbonate surface textured using laser ablation

Energy Technology Data Exchange (ETDEWEB)

Yilbas, B.S., E-mail: bsyilbas@kfupm.edu.sa [ME Department, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Khaled, M. [CHEM Department, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Abu-Dheir, N.; Al-Aqeeli, N.; Said, S.A.M. [ME Department, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Ahmed, A.O.M. [CHEM Department, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Varanasi, K.K.; Toumi, Y.K. [Mechanical Engineering, Massachusetts Institute of Technology, Boston (United States)

2014-11-30

Highlights: • Laser causes micro/nano size pores and shallow fine-size cavities. • Crystallinity at surface is 18% after laser treatment increasing hydrophobicity. • Surface hydrophobicity improves after laser treatment. • Microhardness increases twofold after laser treatment process. • Residual stress is compressive and scratch hardness is 110 ± 11 MPa. • Optical transmittance reduces by 15% after laser treatment. - Abstract: Surface texturing of polycarbonate glass is carried out for improved hydrophobicity via controlled laser ablation at the surface. Optical and physical characteristics of the laser treated layer are examined using analytical tools including optical, atomic force, and scanning electron microscopes, Fourier transform infrared spectroscopy, and X-ray diffraction. Contact angle measurements are carried out to assess the hydrophobicity of the laser treated surface. Residual stress in the laser ablated layer is determined using the curvature method, and microhardnes and scratch resistance are analyzed using a micro-tribometer. Findings reveal that textured surfaces compose of micro/nano pores with fine cavities and increase the contact angle to hydrophobicity such a way that contact angles in the range of 120° are resulted. Crystallization of the laser treated surface reduces the optical transmittance by 15%, contributes to residual stress formation, and enhances the microhardness by twice the value of untreated polycarbonate surface. In addition, laser treatment improves surface scratch resistance by 40%.

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.

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.

Effect of temperature on the partial molar volume, isentropic compressibility and viscosity of DL-2-aminobutyric acid in water and in aqueous sodium chloride solutions

International Nuclear Information System (INIS)

Romero, Carmen M.; Rodríguez, Diana M.; Ribeiro, Ana C.F.; Esteso, Miguel A.

2017-01-01

Highlights: • Apparent volumes, apparent compressibilities, viscosities of DL-2-aminobutyric acid. • Effect of temperature on the values for these properties. • Hydrophobic and hydrophilic interactions and the effect of sodium chloride. - Abstract: Density, sound velocity and viscosity of DL-2-aminobutyric acid in water and in aqueous sodium chloride solutions have been measured at temperatures of (293.15, 298.15, 303.15, 308.15 and 313.15) K. The experimental results were used to determine the apparent molar volume and the apparent molar compressibility as a function of composition at these temperatures. The limiting values of both the partial molar volume and the partial molar adiabatic compressibility at infinite dilution of DL-2-aminobutyric acid in water and in aqueous sodium chloride solutions were determined at each temperature. The experimental viscosity values were adjusted by a least-squares method to a second order equation as proposed by Tsangaris-Martin to obtain the viscosity B coefficient which depends on the size, shape and charge of the solute molecule. The influence of the temperature on the behaviour of the selected properties is discussed in terms of both the solute hydration and the balance between hydrophobic and hydrophilic interactions between the acids and water, and the effect of the sodium chloride concentration.

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.

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 ...

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.

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.

Functionalized nanoscale oil bodies for targeted delivery of a hydrophobic drug

Energy Technology Data Exchange (ETDEWEB)

Chiang, Chung-Jen; Lin, Che-Chin; Lu, Tzu-Li; Wang, Hesin-Fu, E-mail: cjchiang@mail.cmu.edu.tw [Department of Medical Laboratory Science and Biotechnology, China Medical University, 91 Hsue-Shih Road, Taichung 40402, Taiwan (China)

2011-10-14

Effective formulations of hydrophobic drugs for cancer therapies are challenging. To address this issue, we have sought to nanoscale artificial oil bodies (NOBs) as an alternative. NOBs are lipid-based particles which consist of a central oil space surrounded by a monolayer of oleosin (Ole)-embedded phospholipids (PLs). Ole was first fused with the anti-HER2/neu affibody (Ole-ZH2), and the resulting hybrid protein was overproduced in Escherichia coli. ZH2-displayed NOBs were then assembled by sonicating the mixture containing plant oil, PLs, and isolated Ole-ZH2 in one step. To illustrate their usefulness, functionalized NOBs were employed to encapsulate a hydrophobic anticancer drug, Camptothecin (CPT). As a result, these CPT-loaded NOBs remained stable in serum and the release of CPT at the non-permissive condition exhibited a sustained and prolonged profile. Moreover, plain NOBs were biocompatible whereas CPT-loaded NOBs exerted a strong cytotoxic effect on HER2/neu-positive cells in vitro. Administration of xenograft nude mice with CPT-loaded NOBs also led to the regression of solid tumors in an effective way. Overall, the result indicates the potential of NOBs for targeted delivery of hydrophobic drugs.

Characterization of local hydrophobicity on sapphire (0001) surfaces in aqueous environment by colloidal probe atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Wada, Tomoya; Yamazaki, Kenji; Isono, Toshinari; Ogino, Toshio, E-mail: ogino-toshio-rx@ynu.ac.jp

2017-02-28

Highlights: • Local hydrophobicity of phase-separated sapphire (0001) surfaces was investigated. • These surfaces are featured by coexistence of hydrophilic and hydrophobic domains. • Each domain was characterized by colloidal probe atomic force microscopy in water. • Both domains can be distinguished by adhesive forces of the probe to the surfaces. • Characterization in aqueous environment is important in bio-applications of sapphire. - Abstract: Sapphire (0001) surfaces exhibit a phase-separation into hydrophobic and hydrophilic domains upon high-temperature annealing, which were previously distinguished by the thickness of adsorbed water layers in air using atomic force microscopy (AFM). To characterize their local surface hydrophobicity in aqueous environment, we used AFM equipped with a colloidal probe and measured the local adhesive force between each sapphire domain and a hydrophilic SiO{sub 2} probe surface, or a hydrophobic polystyrene one. Two data acquisition modes for statistical analyses were used: one is force measurements at different positions of the surface and the other repeated measurement at a fixed position. We found that adhesive force measurements using the polystyrene probe allow us to distinctly separate the hydrophilic and hydrophobic domains. The dispersion in the force measurement data at different positions of the surface is larger than that in the repeated measurements at a fixed position. It indicates that the adhesive force measurement is repeatable although their data dispersion for the measurement positions is relatively large. From these results, we can conclude that the hydrophilic and hydrophobic domains on the sapphire (0001) surfaces are distinguished by a difference in their hydration degrees.

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.

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.

Temporal Changes in Extracellular Polymeric Substances on Hydrophobic and Hydrophilic Membrane Surfaces in a Submerged Membrane Bioreactor

KAUST Repository

Matar, Gerald Kamil

2016-03-02

Membrane surface hydrophilic modification has always been considered to mitigating biofouling in membrane bioreactors (MBRs). Four hollow-fiber ultrafiltration membranes (pore sizes ∼0.1 μm) differing only in hydrophobic or hydrophilic surface characteristics were operated at a permeate flux of 10 L/m2.h in the same lab-scale MBR fed with synthetic wastewater. In addition, identical membrane modules without permeate production (0 L/m2.h) were operated in the same lab-scale MBR. Membrane modules were autopsied after 1, 10, 20 and 30 days of MBR operation, and total extracellular polymeric substances (EPS) accumulated on the membranes were extracted and characterized in detail using several analytical tools, including conventional colorimetric tests (Lowry and Dubois), liquid chromatography with organic carbon detection (LC-OCD), fluorescence excitation - emission matrices (FEEM), fourier transform infrared (FTIR) and confocal laser scanning microscope (CLSM). The transmembrane pressure (TMP) quickly stabilized with higher values for the hydrophobic membranes than hydrophilic ones. The sulfonated polysulfone (SPSU) membrane had the highest negatively charged membrane surface, accumulated the least amount of foulants and displayed the lowest TMP. The same type of organic foulants developed with time on the four membranes and the composition of biopolymers shifted from protein dominance at early stages of filtration (day 1) towards polysaccharides dominance during later stages of MBR filtration. Nonmetric multidimensional scaling of LC-OCD data showed that biofilm samples clustered according to the sampling event (time) regardless of the membrane surface chemistry (hydrophobic or hydrophilic) or operating mode (with or without permeate flux). These results suggest that EPS composition may not be the dominant parameter for evaluating membrane performance and possibly other parameters such as biofilm thickness, porosity, compactness and structure should be considered

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

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.)

Hydrophobic Hyflon® AD/PVDF membranes for butanol dehydration via pervaporation

KAUST Repository

Jalal, Taghreed; Bettahalli Narasimha, Murthy Srivatsa; Le, Ngoc Lieu; Nunes, Suzana Pereira

2015-01-01

Novel hydrophobic Hyflon® AD /PVDF membranes were developed and investigated for n-butanol dehydration via pervaporation. The coating protocols for thin defect-free Hyflon® AD selective layer on the PVDF support was optimized. Water and n-butanol transport was measured, analyzing the effect of operating conditions. The water flux through the newly developed membranes was higher than 150 g/m2.h with selectivity for water higher than 99 wt %. The focus was on the use of Hyflon® AD as the selective layer for n-butanol dehydration. The membrane application can be extended to other solvents, supporting an effective and simple method for dehydration with hydrophobic membranes.

Hydrophobic Hyflon® AD/PVDF membranes for butanol dehydration via pervaporation

KAUST Repository

Jalal, Taghreed

2015-10-21

Novel hydrophobic Hyflon® AD /PVDF membranes were developed and investigated for n-butanol dehydration via pervaporation. The coating protocols for thin defect-free Hyflon® AD selective layer on the PVDF support was optimized. Water and n-butanol transport was measured, analyzing the effect of operating conditions. The water flux through the newly developed membranes was higher than 150 g/m2.h with selectivity for water higher than 99 wt %. The focus was on the use of Hyflon® AD as the selective layer for n-butanol dehydration. The membrane application can be extended to other solvents, supporting an effective and simple method for dehydration with hydrophobic membranes.

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.

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...

Complex Formation and Liquid-Liquid Extraction in the Niobium(V) - 2,4-Dihydroxythiophenol - Hydrophobic Amines System

International Nuclear Information System (INIS)

Zalov, A.Z.

2015-01-01

The formation and solvent extraction of new ion-association complexes between anionic chelat of niobium(V) with 2,4-dihydroxy-thio-phenol (DHTP) and hydrophobic amines (HAs). The HAs were aniline (An), N-methyl-aniline (MAn), N,N-dimethylaniline (DAn). The optimum conditions for the extraction of mixed ligand complexes (MLC) (organic solvent, extraction time, acidity of the aqueous phase, concentration of reagents), some key constants (association constant (β), extraction constant (Kex)) and analytical characteristics were determined. The molar absorptivities of MLC were calculated ε =(3.5-3.9) * 10/sup 4/ L mol /sup -1/ cm/sup -1/ . The Beer law was applicable in the range of 2.2-100 μg/mL. (author)

Contrasting the beam interaction characteristics of selected lasers with a partially stabilized zirconia bio-ceramic

International Nuclear Information System (INIS)

Lawrence, J.

2002-01-01

Differences in the beam interaction characteristics of a CO 2 laser, a Nd:YAG laser, a high power diode laser (HPDL) and an excimer laser with a partially stabilized zirconia bio-ceramic have been studied. A derivative of Beer-Lambert's law was applied and the laser beam absorption lengths of the four lasers were calculated as 33.55x10 -3 cm for the CO 2 laser, 18.22x10 -3 cm for the Nd : YAG laser, 17.17x10 -3 cm for the HPDL and 8.41x10 -6 cm for the excimer laser. It was determined graphically that the fluence threshold values at which significant material removal was effected by the CO 2 laser, the Nd:YAG laser, the HPDL and the excimer laser were 52 J cm -2 , 97 J cm -2 , 115 J cm -2 and 0.48 J cm -2 , respectively. The thermal loading value for the CO 2 laser, the Nd : YAG laser, the HPDL and the excimer laser were calculated as being 1.55 kJ cm -3 , 5.32 kJ cm 3 , 6.69 kJ cm -3 and 57.04 kJ cm -3 , respectively. (author)

Hydrologic and water quality characteristics of a partially-flooded, abandoned underground coal mine

International Nuclear Information System (INIS)

Aljoe, W.W.

1994-01-01

The hydrologic and water quality characteristics of a partially flooded, abandoned underground coal mine near Latrobe, PA, were studied to support the development of techniques for in situ abatement of its acidic discharge. A quantitative understanding of the conditions affecting discharge flow was considered to be very important in this regard. Statistical analysis of hydrologic data collected at the site shows that the flow rate of the main discharge (a borehole that penetrates the mine workings just behind a set of portal seals) is a linear function of the height of the mine pool above the borehole outlet. Seepage through or around the portal seals is collected by a set of french drains whose discharge rate is largely independent of the mine pool elevation. This seepage was enhanced after a breakthrough that occurred during a period of unusually high pool levels. The mine pool recharge rate during winter is about 2.5 times greater than that of any other season; recharge rates during spring, summer, and fall are approximately equal. Mine pool and discharge water quality information, along with bromide tracer tests, suggest that the original main entries discharge primarily to the french drains, while the borehole carries the discharge from an unmonitored set of entries northwest of the mains. The water quality of the east french drain discharge may have been improved substantially after seepage through the alkaline materials used to construct the portal seals

FLUORESCENCE SPECTROSCOPIC STUDY OF THE FORMATION OF HYDROPHOBIC MICRODOMAINS IN AQUEOUS-SOLUTIONS OF POLY(ALKYLMETHYLDIALLYLAMMONIUM BROMIDES)

NARCIS (Netherlands)

YANG, YJ; Engberts, Jan B F N

The conformational state of poly(alkylmethyldiallylammonium bromides) was studied in aqueous solutions using pyrene as a fluorescence probe. The results are indicative for the formation of hydrophobic microdomains in the case of several copolymers which possess sufficiently hydrophobic alkyl side

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)

Fabrication and surface properties of hydrophobic barium sulfate aggregates based on sodium cocoate modification

Science.gov (United States)

Hu, Linna; Wang, Guangxiu; Cao, Rong; Yang, Chun; Chen, Xi

2014-10-01

Hydrophobic barium sulfate aggregates were fabricated by the direction of cocoate anions. At 30 °C, when the weight ratio of sodium cocoate to BaSO4 particles was 2.0 wt.%, the active ratio of the product reached 99.43% and the contact angle was greater than 120°. This method could not only simplify the complex modification process, but reduce energy consumption. The surface morphology, chemical structure and composition of BaSO4 aggregates were characterized by SEM, XRD, and FTIR. The results indicated that the as-synthesized BaSO4 particles were almond-liked and were composed of many interconnected nanoballs and that their surfaces were affected by cocoate anions. The adsorption of cocoate anions reversed the charge and weakened the surface polarity of BaSO4 particles, driving the formation of aggregates. And cocoate anions induced a change of the BaSO4 particles surface from hydrophilic to hydrophobic by a self-assembly and transformation process. Due to the self-assembled structure and the surface hydrophobicity, when adding the hydrophobic BaSO4 into PVC, the mechanical properties of PVC composite materials were significantly improved.

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.

Detection of Partial Demagnetization Fault in PMSMs Operating under Nonstationary Conditions

DEFF Research Database (Denmark)

Wang, Chao; Delgado Prieto, Miguel; Romeral, Luis

2016-01-01

Demagnetization fault detection of in-service Permanent Magnet Synchronous Machines (PMSMs) is a challenging task because most PMSMs operate under nonstationary circumstances in industrial applications. A novel approach based on tracking characteristic orders of stator current using Vold-Kalman F......Demagnetization fault detection of in-service Permanent Magnet Synchronous Machines (PMSMs) is a challenging task because most PMSMs operate under nonstationary circumstances in industrial applications. A novel approach based on tracking characteristic orders of stator current using Vold......-Kalman Filter is proposed to detect the partial demagnetization fault in PMSMs running at nonstationary conditions. Amplitude of envelope of the fault characteristic orders is used as fault indictor. Experimental results verify the superiority of the proposed method on partial demagnetization online fault...... detection of PMSMs under various speed and load conditions....

Automated Hydrophobic Interaction Chromatography Column Selection for Use in Protein Purification

Science.gov (United States)

Murphy, Patrick J. M.; Stone, Orrin J.; Anderson, Michelle E.

2011-01-01

In contrast to other chromatographic methods for purifying proteins (e.g. gel filtration, affinity, and ion exchange), hydrophobic interaction chromatography (HIC) commonly requires experimental determination (referred to as screening or "scouting") in order to select the most suitable chromatographic medium for purifying a given protein 1. The method presented here describes an automated approach to scouting for an optimal HIC media to be used in protein purification. HIC separates proteins and other biomolecules from a crude lysate based on differences in hydrophobicity. Similar to affinity chromatography (AC) and ion exchange chromatography (IEX), HIC is capable of concentrating the protein of interest as it progresses through the chromatographic process. Proteins best suited for purification by HIC include those with hydrophobic surface regions and able to withstand exposure to salt concentrations in excess of 2 M ammonium sulfate ((NH4)2SO4). HIC is often chosen as a purification method for proteins lacking an affinity tag, and thus unsuitable for AC, and when IEX fails to provide adequate purification. Hydrophobic moieties on the protein surface temporarily bind to a nonpolar ligand coupled to an inert, immobile matrix. The interaction between protein and ligand are highly dependent on the salt concentration of the buffer flowing through the chromatography column, with high ionic concentrations strengthening the protein-ligand interaction and making the protein immobile (i.e. bound inside the column) 2. As salt concentrations decrease, the protein-ligand interaction dissipates, the protein again becomes mobile and elutes from the column. Several HIC media are commercially available in pre-packed columns, each containing one of several hydrophobic ligands (e.g. S-butyl, butyl, octyl, and phenyl) cross-linked at varying densities to agarose beads of a specific diameter 3. Automated column scouting allows for an efficient approach for determining which HIC media

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

Adsorptive removal of hydrophobic organic compounds by carbonaceous adsorbents: a comparative study of waste-polymer-based, coal-based activated carbon, and carbon nanotubes.

Science.gov (United States)

Lian, Fei; Chang, Chun; Du, Yang; Zhu, Lingyan; Xing, Baoshan; Liu, Chang

2012-01-01

Adsorption of the hydrophobic organic compounds (HOCs) trichloroethylene (TCE), 1,3-dichlorobenzene (DCB), 1,3-dinitrobenzene (DNB) and gamma-hexachlorocyclohexane (HCH) on five different carbonaceous materials was compared. The adsorbents included three polymer-based activated carbons, one coal-based activated carbon (F400) and multiwalled carbon nanotubes (MWNT). The polymer-based activated carbons were prepared using KOH activation from waste polymers: polyvinyl chloride (PVC), polyethyleneterephthalate (PET) and tire rubber (TR). Compared with F400 and MWNT, activated carbons derived from PVC and PET exhibited fast adsorption kinetics and high adsorption capacity toward the HOCs, attributed to their extremely large hydrophobic surface area (2700 m2/g) and highly mesoporous structures. Adsorption of small-sized TCE was stronger on the tire-rubber-based carbon and F400 resulting from the pore-filling effect. In contrast, due to the molecular sieving effect, their adsorption on HCH was lower. MWNT exhibited the lowest adsorption capacity toward HOCs because of its low surface area and characteristic of aggregating in aqueous solution.

Adsorptive removal of hydrophobic organic compounds by carbonaceous adsorbents: A comparative study of waste-polymer-based,coal-based activated carbon, and carbon nanotubes

Institute of Scientific and Technical Information of China (English)

Fei Lian; Chun Chang; Yang Du; Lingyan Zhu; Baoshan Xing; Chang Liu

2012-01-01

Adsorption of the hydrophobic organic compounds (HOCs) trichloroethylene (TCE),1,3-dichlorobenzene (DCB),1,3-dinitrobenzene (DNB) and γ-hexachlorocyclohexane (HCH) on five different carbonaceous materials was compared.The adsorbents included three polymer-based activated carbons,one coal-based activated carbon (F400) and multiwalled carbon nanotubes (MWNT).The polymerbased activated carbons were prepared using KOH activation from waste polymers:polyvinyl chloride (PVC),polyethyleneterephthalate (PET) and tire rubber (TR).Compared with F400 and MWNT,activated carbons derived from PVC and PET exhibited fast adsorption kinetics and high adsorption capacity toward the HOCs,attributed to their extremely large hydrophobic surface area (2700 m2/g) and highly mesoporous structures.Adsorption of small-sized TCE was stronger on the tire-rubber-based carbon and F400 resulting from the pore-filling effect.In contrast,due to the molecular sieving effect,their adsorption on HCH was lower.MWNT exhibited the lowest adsorption capacity toward HOCs because of its low surface area and characteristic of aggregating in aqueous solution.

Spontaneous bilateral anterior partial in-the-bag intraocular lens dislocation following routine annual eye examination.

Science.gov (United States)

Ford, Joshua R; Werner, Liliana; Owen, Leah; Vasavada, Shail A; Crandall, Alan

2014-09-01

We present the case of an 81-year-old man with pseudoexfoliation syndrome (PXF) in whom spontaneous bilateral anterior partial in-the-bag intraocular lens (IOL) dislocation was diagnosed following a routine dilated examination that demonstrated only mild pseudophacodonesis with no evidence of subluxation. Uneventful cataract surgery with placement of single-piece hydrophobic acrylic posterior chamber IOLs had been performed in both eyes 7 years previously. Bilateral IOL repositioning with scleral fixation was performed to correct the dislocation. Postoperative examinations showed remarkable improvement in visual acuity and IOL stability. We hypothesize that zonular weakness secondary to PXF predisposed the patient to bilateral IOL partial dislocation. Pupil dilation in the setting of mild pseudophacodonesis at the time of routine examination may have been a precipitating factor. To our knowledge, bilateral IOL subluxation/dislocation has been described in a limited number of case reports. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

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

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.

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.

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.

Water around fullerene shape amphiphiles: A molecular dynamics simulation study of hydrophobic hydration

International Nuclear Information System (INIS)

Varanasi, S. R.; John, A.; Guskova, O. A.; Sommer, J.-U.

2015-01-01

Fullerene C 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 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 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

Dianxianning improved amyloid β-induced pathological characteristics partially through DAF-2/DAF-16 insulin like pathway in transgenic C. elegans.

Science.gov (United States)

Zhi, Dejuan; Wang, Dong; Yang, Wenqi; Duan, Ziyun; Zhu, Shuqian; Dong, Juan; Wang, Na; Wang, Ningbo; Fei, Dongqing; Zhang, Zhanxin; Wang, Xin; Wang, Meizhu; Li, Hongyu

2017-09-12

Dianxianning (DXN) is a traditional Chinese formula, and has been approved in China for treating epilepsy since 1996. Here anti-Alzheimer's disease activity of DXN has been reported. DXN improved AD-like symptoms of paralysis and 5-HT sensitivity of transgenic Aβ 1-42 C. elegans. In worms, DXN significantly increased Aβ monomers and decreased the toxic Aβ oligomers, thus reducing Aβ toxicity. DXN significantly suppressed the expression of hsp-16.2 induced by juglone, and up-regulated sod-3 expression. These results indicated that DXN increased stress resistance and protected C. elegans against oxidative stress. Furthermore, DXN could significantly promote DAF-16 nuclear translocation, but it did not activate SKN-1. The inhibitory effect of DXN on the Aβ toxicity was significantly reverted by daf-16 RNAi, rather than skn-1 RNAi or hsf-1 RNAi. These results indicated that DAF-16 is at least partially required for the anti-AD effect of DXN. In conclusion, DXN improved Aβ-induced pathological characteristics partially through DAF-2/DAF-16 insulin like pathway in transgenic worms. Together with our data obtained by Morris water maze test, the results showed that DXN markedly ameliorated cognitive performance impairment induced by scopolamine in mice. All the results support that DXN is a potential drug candidate to treat Alzheimer's diseases.

Structural and Mechanical Properties of Thin Films of Bovine Submaxillary Mucin versus Porcine Gastric Mucin on a Hydrophobic Surface in Aqueous Solutions

DEFF Research Database (Denmark)

Madsen, Jan Busk; Sotres, Javier; Pakkanen, Kirsi I.

2016-01-01

The structural and mechanical properties of thin films generated from two types of mucins, namely, bovine submaxillary mucin (BSM) and porcine gastric mucin (PGM) in aqueous environment were investigated with several bulk and surface analytical techniques. Both mucins generated hydrated films...... on hydrophobic polydimethylsiloxane (PDMS) surfaces from spontaneous adsorption arising from their amphiphilic characteristic. However, BSM formed more elastic films than PGM at neutral pH condition. This structural difference was manifested from the initial film formation processes to the responses to shear...

Fabrication of Hydrophobic Surface on Wood Veneer via Electroless Nickel Plating Combined with Chemical Corrosion

Directory of Open Access Journals (Sweden)

Zhaojun Tang

2015-12-01

Full Text Available Birch veneers were coated with Ni-P films by a combined process of KBH4 activation and electroless plating. The plated veneers were further chemically corroded to obtain hydrophobic surfaces on wood. The effect of chemical corrosion on the contact angle of the veneers was investigated. The hydrophobic veneers were characterized by X-ray photo electron spectroscopy (XPS, scanning electron microscopy (SEM, and X-ray diffraction (XRD. The surface contact angle of birch veneer before and after it was plated with Ni-P alloy coating was 41º and 121º, respectively. The contact angle reached 136.7º when the nickel-coated veneers were corroded in CuSO4 aqueous solution for 30 min. XPS analysis showed that Cu0 cluster doped with little CuO formed on the corroded surface of Ni-P alloy film after chemical corrosion. SEM and XRD showed that rough copper clusters formed on the surface of the wood veneer and revealed the reason of the surface hydrophobicity. This study provides a new pathway for fabricating hydrophobic wood.

Introduction to partial differential equations

CERN Document Server

Borthwick, David

2016-01-01

This modern take on partial differential equations does not require knowledge beyond vector calculus and linear algebra. The author focuses on the most important classical partial differential equations, including conservation equations and their characteristics, the wave equation, the heat equation, function spaces, and Fourier series, drawing on tools from analysis only as they arise.Within each section the author creates a narrative that answers the five questions: (1) What is the scientific problem we are trying to understand? (2) How do we model that with PDE? (3) What techniques can we use to analyze the PDE? (4) How do those techniques apply to this equation? (5) What information or insight did we obtain by developing and analyzing the PDE? The text stresses the interplay between modeling and mathematical analysis, providing a thorough source of problems and an inspiration for the development of methods.

Adsorption of IgG onto hydrophobic teflon. Differences between the F(ab) and F(c) domains

NARCIS (Netherlands)

Vermeer, AWP; Giacomelli, CE; Norde, W

2001-01-01

The effect of differences in the degree of hydrophobicity of protein patches/fragments on the adsorption behaviour of the protein is investigated. The adsorption isotherm of a monoclonal mouse anti-human immunoglobulin G (isotype 2b) onto hydrophobic Teflon particles is measured using a depletion

Engineering durable hydrophobic surfaces on porous alumina ceramics using in-situ formed inorganic-organic hybrid nanoparticles

NARCIS (Netherlands)

Gu, Jianqiang; Wang, Junwei; Li, Yanan; Xu, Xin; Chen, Chusheng; Winnubst, Louis

2017-01-01

Hydrophobic surfaces are required for a variety of applications owing to their water repellent and self-cleaning properties. In this work, we present a novel approach to prepare durable hydrophobic surfaces on porous ceramics. A polydimethylsiloxane (PDMS) film was applied to a porous alumina wafer,

Oil and gas pipelines with hydrophobic surfaces better equipped to deal with gas hydrate flow assurance issues

DEFF Research Database (Denmark)

Perfeldt, Christine Malmos; Sharifi, Hassan; von Solms, Nicolas

2015-01-01

Gas hydrate deposition can cause plugging in oil and gas pipelines with resultant flow assurance challenges. Presently, the energy industry uses chemical additives in order to manage hydrate formation, however these chemicals are expensive and may be associated with safety and environmental...... concerns. Here we show the effect of a hydrophobically coated surface on hydrate formation in the presence of an antifreeze protein type I (AFP I) and a biodegradable synthetic polymer (LuvicapBio) in a high pressure crystallizer setup. The hydrophobic surface increased the hydrate induction time...... crystallizer. This indicates that 10 to 14 times less KHI is needed in the presence of a hydrophobically coated surface. These experimental studies suggest that the use of hydrophobic surfaces or pipelines could serve as an alternative or additional flow assurance approach for gas hydration mitigation...

Molecular Theory and the Effects of Solute Attractive Forces on Hydrophobic Interactions.

Science.gov (United States)

Chaudhari, Mangesh I; Rempe, Susan B; Asthagiri, D; Tan, L; Pratt, L R

2016-03-03

The role of solute attractive forces on hydrophobic interactions is studied by coordinated development of theory and simulation results for Ar atoms in water. We present a concise derivation of the local molecular field (LMF) theory for the effects of solute attractive forces on hydrophobic interactions, a derivation that clarifies the close relation of LMF theory to the EXP approximation applied to this problem long ago. The simulation results show that change from purely repulsive atomic solute interactions to include realistic attractive interactions diminishes the strength of hydrophobic bonds. For the Ar-Ar rdfs considered pointwise, the numerical results for the effects of solute attractive forces on hydrophobic interactions are opposite in sign and larger in magnitude than predicted by LMF theory. That comparison is discussed from the point of view of quasichemical theory, and it is suggested that the first reason for this difference is the incomplete evaluation within LMF theory of the hydration energy of the Ar pair. With a recent suggestion for the system-size extrapolation of the required correlation function integrals, the Ar-Ar rdfs permit evaluation of osmotic second virial coefficients B2. Those B2's also show that incorporation of attractive interactions leads to more positive (repulsive) values. With attractive interactions in play, B2 can change from positive to negative values with increasing temperatures. This is consistent with the puzzling suggestions of decades ago that B2 ≈ 0 for intermediate cases of temperature or solute size. In all cases here, B2 becomes more attractive with increasing temperature.

Contribution of hydrophobic effect to the sorption of phenanthrene, 9-phenanthrol and 9, 10-phenanthrenequinone on carbon nanotubes.

Science.gov (United States)

Peng, Hongbo; Zhang, Di; Pan, Bo; Peng, Jinhui

2017-02-01

Polycyclic aromatic hydrocarbons (PAHs), with diverse sources and acute toxicity, are categorized as priority pollutants. Previous studies have stated that the hydrophobic effect controls PAH sorption, but no study has been conducted to quantify the exact contribution of the hydrophobic effect. Considering the well-defined structure of carbon nanotubes and their stable chemical composition in organic solvents, three multi-walled carbon nanotubes (MWCNTs) were selected as a model adsorbent. Phenanthrene (PHE) and its degradation intermediates 9-phenanthrol (PTR) and 9, 10-phenanthrenequinone (PQN) were used as model adsorbates. To quantify the contribution of the hydrophobic effect for these three chemicals, the effect of organic solvent (methanol and hexadecane) was investigated. Adsorption isotherms for PHE, PTR and PQN were well fitted by the Freundlich isotherm model. A positive relationship between adsorption affinities of these three chemicals and specific surface area (SSA) was observed in hexadecane but not in water or methanol. Other factors should be included other than SSA. Adsorption of PQN on MWCNTs with oxygen functional groups was higher than that on pristine MWCNTs due to π-π EDA interactions. The contribution of hydrophobic effect was 50%-85% for PHE, suggesting that hydrophobic effect was the predominant mechanism. This contribution was lower than 30% for PTR/PQN on functionalized MWCNTs. Hydrogen bonds control the adsorption of PTR, and π-π bonding interactions control PQN sorption after screening out the hydrophobic effect in hexadecane. Hydrophobic effect is the control mechanism for nonpolar chemicals, while functional groups of CNTs and solvent types control the adsorption of polar compounds. Extended work on quantifying the relationship between chemical structure and the contribution of the hydrophobic effect will provide a useful technique for PAH fate modeling. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

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®

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.

Nonlinear correlations in the hydrophobicity and average flexibility along the glycolytic enzymes sequences

Energy Technology Data Exchange (ETDEWEB)

Ciorsac, Alecu, E-mail: aleciorsac@yahoo.co [Politehnica University of Timisoara, Department of Physical Education and Sport, 2 P-ta Victoriei, 300006, Timisoara (Romania); Craciun, Dana, E-mail: craciundana@gmail.co [Teacher Training Department, West University of Timisoara, 4 Boulevard V. Pirvan, Timisoara, 300223 (Romania); Ostafe, Vasile, E-mail: vostafe@cbg.uvt.r [Department of Chemistry, West University of Timisoara, 16 Pestallozi, 300115, Timisoara (Romania); Laboratory of Advanced Researches in Environmental Protection, Nicholas Georgescu-Roegen Interdisciplinary Research and Formation Platform, 4 Oituz, Timisoara, 300086 (Romania); Isvoran, Adriana, E-mail: aisvoran@cbg.uvt.r [Department of Chemistry, West University of Timisoara, 16 Pestallozi, 300115, Timisoara (Romania); Laboratory of Advanced Researches in Environmental Protection, Nicholas Georgescu-Roegen Interdisciplinary Research and Formation Platform, 4 Oituz, Timisoara, 300086 (Romania)

2011-04-15

Research highlights: lights: We focus our study on the glycolytic enzymes. We reveal correlation of hydrophobicity and flexibility along their chains. We also reveal fractal aspects of the glycolytic enzymes structures and surfaces. The glycolytic enzyme sequences are not random. Creation of fractal structures requires the operation of nonlinear dynamics. - Abstract: Nonlinear methods widely used for time series analysis were applied to glycolytic enzyme sequences to derive information concerning the correlation of hydrophobicity and average flexibility along their chains. The 20 sequences of different types of the 10 human glycolytic enzymes were considered as spatial series and were analyzed by spectral analysis, detrended fluctuations analysis and Hurst coefficient calculation. The results agreed that there are both short range and long range correlations of hydrophobicity and average flexibility within investigated sequences, the short range correlations being stronger and indicating that local interactions are the most important for the protein folding. This correlation is also reflected by the fractal nature of the structures of investigated proteins.

Self-Assembly of Charged Amphiphilic Diblock Copolymers with Insoluble Blocks of Decreasing Hydrophobicity: From Kinetically Frozen Colloids to Macrosurfactants

Energy Technology Data Exchange (ETDEWEB)

M Jacquin; P Muller; H Cottet; O Theodoly

2011-12-31

We have investigated the self-assembly properties in aqueous solution of amphiphilic diblock copolymers with insoluble blocks of different hydrophobicity and demonstrated that the condition to obtain dynamic micelles is to design samples with insoluble blocks of low enough hydrophobicity. We focus here on results with new water-soluble amphiphilic diblock copolymers poly(diethyleneglycol ethylether acrylate)-b-poly(acrylic acid), or PDEGA-b-PAA. The physical characteristics of PDEGA-b-PAA micelles at high ionization have been determined by small angle neutron scattering (SANS). We show that PDEGA-b-PAA samples form micelles at thermodynamic equilibrium. The critical micelle concentrations (CMCs) decrease strongly with ionic strength and temperature due to a solvent quality decrease for, respectively, the corona and the core. This behavior of reversible aggregation is remarkable as compared to the behavior of kinetically frozen aggregation that has been widely observed with samples of similar architecture and different hydrophobic blocks, for example, poly(styrene)-b-poly(acrylic acid), PS-b-PAA, and poly(butyl acrylate)-b-poly(acrylic acid), PBA-b-PAA. We have measured the interfacial tension between water and the homopolymers PDEGA and PBA at, respectively, 3 and 20 mN/m at room temperature, which permits one to estimate the energy cost to extract a unimer from a micelle. The results are consistent with a micelle association that is fast for PDEGA-b-PAA and kinetically frozen PBA-b-PAA. Hence, PDEGA-b-PAA samples form a new system of synthetic charged macrosurfactant with unique properties of fast dynamic association, tunable charge, and water solubility even at temperatures and NaCl concentrations as high as 65 C and 1 M.

Hydrophobic perfluoro-silane functionalization of porous silicon photoluminescent films and particles

Energy Technology Data Exchange (ETDEWEB)

Rodriguez, C.; Laplace, P.; Gallach-Pérez, D.; Pellacani, P.; Martín-Palma, R.J. [Departamento de Física Aplicada e Instituto de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, 28049, Madrid (Spain); Torres-Costa, V. [Departamento de Física Aplicada e Instituto de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, 28049, Madrid (Spain); Centro de Microanálisis de Materiales, Universidad Autónoma de Madrid, 28049, Madrid (Spain); Ceccone, G. [European Commission, Joint Research Centre, Institute for Health and Consumer Protection, 21020, Ispra (Italy); Manso Silván, M., E-mail: miguel.manso@uam.es [Departamento de Física Aplicada e Instituto de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, 28049, Madrid (Spain)

2016-09-01

Highlights: • Hydrophobic functionalization of porous silicon structures. • Perfluorooctyl group binding confirmed by XPS. • Improved stability face to extreme oxidation conditions. • Perfluorooctyl functionalization compatible with photoluminescence of porous silicon particles. - Abstract: Luminescent structures based on semiconductor quantum dots (QDs) are increasingly used in biomolecular assays, cell tracking systems, and in-vivo diagnostics devices. In this work we have carried out the functionalization of porous silicon (PSi) luminescent structures by a perfluorosilane (Perfluoro-octyltriethoxysilane, PFOS) self assembly. The PFOS surface binding (traced by X-ray photoelectron spectroscopy) and photoluminescence efficiency were analyzed on flat model PSi. Maximal photoluminescence intensity was obtained from PSi layers anodized at 110 mA/cm{sup 2}. Resistance to hydroxylation was assayed in H{sub 2}O{sub 2}:ethanol solutions and evidenced by water contact angle (WCA) measurements. PFOS-functionalized PSi presented systematically higher WCA than untreated PSi. The PFOS functionalization was found to slightly improve the aging of the PSi particles in water giving rise to particles with longer luminescent life. Confirmation of PFOS binding to PSi particles was derived from FTIR spectra and the preservation of luminescence was observed by fluorescence microscopy. Such functionalization opens the possibility of promoting hydrophobic-hydrophobic interactions between biomolecules and fluorescent QD structures, which may enlarge their biomedical applications catalogue.

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

Formation and Mechanism of Superhydrophobic/Hydrophobic Surfaces Made from Amphiphiles through Droplet-Mediated Evaporation-Induced Self-Assembly.

Science.gov (United States)

Dong, Fangyuan; Zhang, Mi; Tang, Wai-Wa; Wang, Yi

2015-04-23

Superhydrophobic/hydrophobic surfaces have attracted wide attention because of their broad applications in various regions, including coating, textile, packaging, electronic devices, and bioengineering. Many studies have been focused on the fabrication of superhydrophobic/hydrophobic surfaces using natural materials. In this paper, superhydrophobic/hydrophobic surfaces were formed by an amphiphilic natural protein, zein, using electrospinning. Water contact angle (WCA) and scanning electron microscopy (SEM) were used to characterize the hydrophobicity and surface morphology of the electrospun structures. The highest WCA of the zein electrospun surfaces could reach 155.5 ± 1.4°. To further understand the mechanism of superhydrophobic surface formation from amphiphiles using electrospinning, a synthetic amphiphilic polymer was selected, and also, a method similar to electrospinning, spray drying, was tried. The electrospun amphiphilic polymer surface showed a high hydrophobicity with a WCA of 141.4 ± 0.7°. WCA of the spray-dried zein surface could reach 125.3 ± 2.1°. The secondary structures of the zein in the electrospun film and cast-dried film were studied using ATR-FTIR, showing that α-helix to β-sheet transformation happened during the solvent evaporation in the cast drying process but not in the electrospinning process. A formation mechanism was proposed on the basis of the orientation of the amphiphiles during the solvent evaporation of different fabrication methods. The droplet-based or jet-based evaporation during electrospinning and spray drying led to the formation of the superhydrophobic/hydrophobic surface by the accumulation of the hydrophobic groups of the amphiphiles on the surface, while the surface-based evaporation during cast drying led to the formation of the hydrophilic surface by the accumulation of the hydrophilic groups of the amphiphiles on the surface.

Layer-by-layer polyelectrolyte-polyester hybrid microcapsules for encapsulation and delivery of hydrophobic drugs.

Science.gov (United States)

Luo, Rongcong; Venkatraman, Subbu S; Neu, Björn

2013-07-08

A two-step process is developed to form layer-by-layer (LbL) polyelectrolyte microcapsules, which are able to encapsulate and deliver hydrophobic drugs. Spherical porous calcium carbonate (CaCO3) microparticles were used as templates and coated with a poly(lactic acid-co-glycolic acid) (PLGA) layer containing hydrophobic compounds via an in situ precipitation gelling process. PLGA layers that precipitated from N-methyl-2-pyrrolidone (NMP) had a lower loading and smoother surface than those precipitated from acetone. The difference may be due to different viscosities and solvent exchange dynamics. In the second step, the successful coating of multilayer polyelectrolytes poly(allylamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS) onto the PLGA coated CaCO3 microparticles was confirmed with AFM and ζ-potential studies. The release of a model hydrophobic drug, ibuprofen, from these hybrid microcapsules with different numbers of PAH/PSS layers was investigated. It was found that the release of ibuprofen decreases with increasing layer numbers demonstrating the possibility to control the release of ibuprofen with these novel hybrid microcapsules. Besides loading of hydrophobic drugs, the interior of these microcapsules can also be loaded with hydrophilic compounds and functional nanoparticles as demonstrated by loading with Fe3O4 nanoparticles, forming magnetically responsive dual drug releasing carriers.

Characteristics and degradation of chitosan/cellulose acetate microspheres with different model drugs

Science.gov (United States)

Zhou, Hui-yun; Chen, Xi-guang

2008-12-01

In this study, chitosan/cellulose acetate microspheres (CCAM) were prepared by W/O/W emulsification and solvent evaporation as a drug delivery system. The microspheres were spherical, free-flowing and non-aggregated. The CCAM had good flow and suspension ability. The loading efficiency of different model drugs increased with the increasing hydrophobicity of the drug. The loading efficiency of 6-mercaptopurine (6-MP) was more than 30% whereas that of ranitidine hydrochloride (RT) or acetaminophen (ACP) was only 10%. The pH values of solution affected the swelling ability of CCAM and the relative humidity had little effect on the characteristics of CCAM when it was not more than 75%. The CCAM system had a good effect on the controlled release of different model drugs. However, the release rate became slower with the increase of the hydrophobicity of drugs. The release rate of CCAM loaded with hydrophilic RT was almost 60% during 48 h and the release rate of CCAM loaded with hydrophobic drug of 6-MP was not more than 30%. In the meantime, the CCAM system was degradable in vitro and the degradation rate was faster in lysozyme solution than that in the medium of PBS. So the CCAM system was a degradable promising drug delivery system especially for hydrophobic drugs.

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...

Accumulation of dissolved gases at hydrophobic surfaces in water and sodium chloride solutions: Implications for coal flotation

Energy Technology Data Exchange (ETDEWEB)

Hampton, M.A.; Nguyen, A.V. [University of Queensland, Brisbane, Qld. (Australia). Division of Chemical Engineering

2009-08-15

Dissolved gases can preferentially accumulate at the hydrophobic solid-water interface as revealed by neutron reflectivity measurements. In this paper, atomic force microscopy (AFM) was used to examine accumulation of dissolved gases at a hydrophobic surface in water and sodium chloride solutions. The solvent-exchange method was used to artificially form gaseous domains accumulated at the interface suitable for AFM imaging. Smooth graphite surfaces were used as model surfaces to minimize the secondary effect of surface roughness on the imaging. The concentration of NaCl up to 1 M was found to have a negligible influence on the geometry and population of pre-existing nanobubbles, nanopancakes and nanobubble-nanopancake composites. The implications of the findings on coal flotation in saline water are discussed in terms of attraction between hydrophobic surfaces in water, bubble-particle attachment and hydrophobic coagulation between particles.

Raman study of lysozyme amyloid fibrils suspended on super-hydrophobic surfaces by shear flow

KAUST Repository

Moretti, Manola

2017-05-19

The shear flow generated at the rim of a drop evaporating on a micro-fabricated super-hydrophobic surface has been used to suspend and orient single/few lysozyme amyloid fibrils between two pillars for substrate-free characterization. Micro Raman spectroscopy performed on extended fibers evidenced a shift of the Amide I band main peak to the value attributed to β-sheet secondary structure, characteristic of the amyloid fibers. In addition, given the orientation sensitivity of the anisotropic molecule, the Raman signal of the main secondary structure was nicely enhanced for a fiber alignment parallel to the polarization direction of the laser. The substrate-free sample generated by this suspending technique is suitable for other structural analysis methods, where fiber crystals are investigated. It could be further employed for generation of arrays and patterns in a controllable fashion, where bio-compatible material is needed.

Raman study of lysozyme amyloid fibrils suspended on super-hydrophobic surfaces by shear flow

KAUST Repository

Moretti, Manola; Allione, Marco; Marini, Monica; Torre, Bruno; Giugni, Andrea; Limongi, Tania; Das, Gobind; Di Fabrizio, Enzo M.

2017-01-01

The shear flow generated at the rim of a drop evaporating on a micro-fabricated super-hydrophobic surface has been used to suspend and orient single/few lysozyme amyloid fibrils between two pillars for substrate-free characterization. Micro Raman spectroscopy performed on extended fibers evidenced a shift of the Amide I band main peak to the value attributed to β-sheet secondary structure, characteristic of the amyloid fibers. In addition, given the orientation sensitivity of the anisotropic molecule, the Raman signal of the main secondary structure was nicely enhanced for a fiber alignment parallel to the polarization direction of the laser. The substrate-free sample generated by this suspending technique is suitable for other structural analysis methods, where fiber crystals are investigated. It could be further employed for generation of arrays and patterns in a controllable fashion, where bio-compatible material is needed.

Interactions between nano-TiO2 and the oral cavity: Impact of nanomaterial surface hydrophilicity/hydrophobicity

International Nuclear Information System (INIS)

Teubl, Birgit J.; Schimpel, Christa; Leitinger, Gerd; Bauer, Bettina; Fröhlich, Eleonore; Zimmer, Andreas; Roblegg, Eva

2015-01-01

Highlights: • Hydrophilic as well as hydrophobic TiO 2 NPs agglomerated under oral physiological conditions. • Particles penetrated the upper and lower buccal epithelium, independent on the degree of hydrophilicity. • Most of the hydrophobic particles were found in vesicular structures, while hydrophilic particles were freely distributed in the cytoplasm. • Hydrophilic particles had a higher potential to trigger toxic effects (e.g., ROS) than hydrophobic particles. - Abstract: Titanium dioxide (TiO 2 ) nanoparticles are available in a variety of oral applications, such as food additives and cosmetic products. Thus, questions about their potential impact on the oro-gastrointestinal route rise. The oral cavity represents the first portal of entry and is known to rapidly interact with nanoparticles. Surface charge and size contribute actively to the particle–cell interactions, but the influence of surface hydrophilicity/hydrophobicity has never been shown before. This study addresses the biological impact of hydrophilic (NM 103, rutile, 20 nm) and hydrophobic (NM 104, rutile, 20 nm) TiO 2 particles within the buccal mucosa. Particle characterization was addressed with dynamic light scattering and laser diffraction. Despite a high agglomeration tendency, 10% of the particles/agglomerates were present in the nanosized range and penetrated into the mucosa, independent of the surface properties. However, significant differences were observed in intracellular particle localization. NM 104 particles were found freely distributed in the cytoplasm, whereas their hydrophobic counterparts were engulfed in vesicular structures. Although cell viability/membrane integrity was not affected negatively, screening assays demonstrated that NM 104 particles showed a higher potential to decrease the physiological mitochondrial membrane potential than NM 103, resulting in a pronounced generation of reactive oxygen species

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.

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

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

Characteristics of magnetic resonance imaging with partial flip angle and gradient field echo

International Nuclear Information System (INIS)

Hamada, Tatsumi; Uto, Tatsurou; Okafuji, Tatsumasa; Ookusa, Akihiko; Oonishi, Takuya; Mabuchi, Nobuhisa; Fujii, Kouichi; Yoshioka, Hiroyasu; Ishida, Osamu

1988-01-01

Characteristics of a magnetic resonance (MR) imaging pulse sequence with short repetition time (Tr), short echo time (Te), partial flip angle and gradient field echo, at 0.5 T, were studied. A series of sagittal images of the cerebrospinal region was obtained with varied Tr, Te and flip angle, signal intensities were measured by means of a region of interest (ROI) function, and optimal parameters to achieve maximum tissue contrast were found. Of the parameters flip angle had the greatest effect on tissue contrast. Flip angles less than 20 or more than 60 degrees were necessary to discriminate between spinal cord and cerebrospinal fluid. So called MR myelography was obtained with the flip angle of 15 degrees. Opposed and inphase images were obtained at the Te levels of 21 and 28 ms, respectively. Likewise, a series of transverse images of the abdomen with short Tr, short Te and varied flip angles was obtained in a breath-holding interval, and signal intensities of ROIs were measured. Maximum intensities of the liver, the spleen and perirenal fat were obtained at the flip angles of 40, 30 and 60 degrees, respectively. Although maximum intensity was found at the flip angle of 30 degrees for both of the renal cortex and medulla, the maximum contrast between the two tissues was obtained at the flip angles of 50-60 degrees. The image contrast obtained by these pulse sequences was also theoretically predictable, and so it is thought possible that flip angle, Tr and Te are manipulated to yield a desired contrast. (author)

Temporal lobe dual pathology in malignant migrating partial seizures in infancy.

Science.gov (United States)

Coppola, Giangennaro; Operto, Francesca Felicia; Auricchio, Gianfranca; D'Amico, Alessandra; Fortunato, Delia; Pascotto, Antonio

2007-06-01

A child had the characteristic clinical and EEG pattern of migrating partial seizures in infancy with left temporal lobe atrophy, hippocampal sclerosis and cortical-subcortical blurring. Seizures were drug-resistant, with recurring episodes of status epilepticus. The child developed microcephaly with arrest of psychomotor development. Focal brain lesions, in the context of migrating partial seizures, have not been previously reported.[Published with video sequences].

Comparative TEM study of bonded silicon/silicon interfaces fabricated by hydrophilic, hydrophobic and UHV wafer bonding

International Nuclear Information System (INIS)

Reznicek, A.; Scholz, R.; Senz, S.; Goesele, U.

2003-01-01

Wafers of Czochralski-grown silicon were bonded hydrophilically, hydrophobically and in ultrahigh vacuum (UHV) at room temperature. Wafers bonded hydrophilically adhere together by hydrogen bonds, those bonded hydrophobically by van der Waals forces and UHV-bonded ones by covalent bonds. Annealing the pre-bonded hydrophilic and hydrophobic wafer pairs in argon for 2 h at different temperatures increases the initially low bonding energy. UHV-bonded wafer pairs were also annealed to compare the results. Transmission electron microscopy (TEM) investigations show nano-voids at the interface. The void density depends on the initial bonding strength. During annealing the shape, coverage and density of the voids change significantly

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.

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.

Charge transfer and partial pinning at the contacts as the origin of a double dip in the transfer characteristics of graphene-based field-effect transistors

International Nuclear Information System (INIS)

Di Bartolomeo, Antonio; Giubileo, Filippo; Santandrea, Salvatore; Romeo, Francesco; Citro, Roberta; Schroeder, Thomas; Lupina, Grzegorz

2011-01-01

We discuss the origin of an additional dip other than the charge neutrality point observed in the transfer characteristics of graphene-based field-effect transistors with a Si/SiO 2 substrate used as the back-gate. The double dip is proved to arise from charge transfer between the graphene and the metal electrodes, while charge storage at the graphene/SiO 2 interface can make it more evident. Considering a different Fermi energy from the neutrality point along the channel and partial charge pinning at the contacts, we propose a model which explains all the features observed in the gate voltage loops. We finally show that the double dip enhanced hysteresis in the transfer characteristics can be exploited to realize graphene-based memory devices.

Facile fabrication of super-hydrophobic nano-needle arrays via breath figures method.

Science.gov (United States)

Kim, Jiseok; Lew, Brian; Kim, Woo Soo

2011-12-06

Super-hydrophobic surfaces which have been fabricated by various methods such as photolithography, chemical treatment, self-assembly, and imprinting have gained enormous attention in recent years. Especially 2D arrays of nano-needles have been shown to have super-hydrophobicity due to their sharp surface roughness. These arrays can be easily generated by removing the top portion of the honeycomb films prepared by the breath figures method. The hydrophilic block of an amphiphilic polymer helps in the fabrication of the nano-needle arrays through the production of well-ordered honeycomb films and good adhesion of the film to a substrate. Anisotropic patterns with water wettability difference can be useful for patterning cells and other materials using their selective growth on the hydrophilic part of the pattern. However, there has not been a simple way to generate patterns with highly different wettability. Mechanical stamping of the nano-needle array with a polyurethane stamp might be the simplest way to fabricate patterns with wettability difference. In this study, super-hydrophobic nano-needle arrays were simply fabricated by removing the top portion of the honeycomb films. The maximum water contact angle obtained with the nano-needle array was 150°. By controlling the pore size and the density of the honeycomb films, the height, width, and density of nano-needle arrays were determined. Anisotropic patterns with different wettability were fabricated by simply pressing the nano-needle array at ambient temperature with polyurethane stamps which were flexible but tough. Mechanical stamping of nano-needle arrays with micron patterns produced hierarchical super-hydrophobic structures.PACS: 05.70.Np, 68.55.am, 68.55.jm.

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

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

Corrosion resistance and long-term durability of super-hydrophobic nickel film prepared by electrodeposition process

International Nuclear Information System (INIS)

Khorsand, S.; Raeissi, K.; Ashrafizadeh, F.

2014-01-01

A super-hydrophobic nickel film with micro-nano structure was successfully fabricated by electrodeposition process. By controlling electrodeposition parameters and considering different storage times for the coatings in air, various nickel films with different wettability were fabricated. Surface morphology of nickel films was examined by means of scanning electron microscopy (SEM). The results showed that the micro-nano nickel film was well-crystallized and exhibited pine cone-like microstructure with nano-cone arrays randomly dispersed on each micro-protrusion. The wettability of the micro-nano nickel film varied from super-hydrophilicity (water contact angle 5.3°) to super-hydrophobicity (water contact angle 155.7°) by exposing the surface in air at room temperature. The corrosion resistance of the super-hydrophobic film was estimated by electrochemical impedance spectroscopy (EIS) and Tafel polarization measurements. The potentiodynamic curves revealed that the corrosion rate of superhydrophobic surface was only 0.16% of the bare copper substrate. Moreover, EIS measurements and appropriate equivalent circuit models revealed that the corrosion resistance of nickel films considerably improved with an increase in the hydrophobicity. The superhydrophobic surface also exhibited an excellent long-term durability in neutral 3.5 wt.% NaCl solution.

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.

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.

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.

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.

Relation between acid back-diffusion and luminal surface hydrophobicity in canine gastric mucosa: Effects of salicylate and prostaglandin

International Nuclear Information System (INIS)

Goddard, P.J.

1989-01-01

The stomach is thought to be protected from luminal acid by a gastric mucosal barrier that restricts the diffusion of acid into tissue. This study tested the hypothesis that the hydrophobic luminal surface of canine gastric mucosa incubated in Ussing chambers, impedes the back-diffusion of luminal acid into the tissue. Isolated sheets of mucosa were treated with cimetidine to inhibit spontaneous acid secretion, and incubated under conditions that prevented significant secretion of luminal bicarbonate. By measuring acid loss from the luminal compartment using the pH-stat technique, acid back-diffusion was continuously monitored; potential difference (PD) was measured as an index of tissue viability. Tissue luminal surface hydrophobicity was estimated by contact angle analysis at the end of each experiment. Addition of 16,16-dimethyl prostaglandin E 2 to the nutrient compartment enhanced luminal surface hydrophobicity, but did not reduce acid back-diffusion in tissues that maintained a constant PD. 10 mM salicylate at pH 4.00 in the luminal compartment reduced surface hydrophobicity, but this decrease did not occur if 1 ug/ml prostaglandin was present in the nutrient solution. Despite possessing relatively hydrophilic and relatively hydrophobic surface properties, respectively, acid back-diffusion in the absence of salicylate was not significantly different between these two groups. Neither group maintained a PD after incubation with salicylate. Lastly, radiolabeled salicylate was used to calculate the free (non-salicylate associated) acid loss in tissues incubated with salicylate and/or prostaglandin. No significant correlation was found between free acid back-diffusion and luminal surface hydrophobicity. These data do not support the hypothesis that acid back-diffusion in impeded by the hydrophobic surface presented by isolated canine gastric mucosa

Microshear bond strength of self-etching systems associated with a hydrophobic resin layer.

Science.gov (United States)

De Vito Moraes, André Guaraci; Francci, Carlos; Carvalho, Ceci Nunes; Soares, Silvio Peixoto; Braga, Roberto Ruggiero

2011-08-01

To evaluate in vitro the microshear bond strength of adhesive systems applied to dentin according to manufacturers' instructions, associated or not with a hydrophobic layer of unfilled resin. Six self-etching adhesives (Clearfil SE Bond, Kuraray Medical; AdheSE, Ivoclar Vivadent; Xeno III, Dentsply; I Bond, Heraeus-Kulzer; Bond Force, Tokuyama; Futurabond DC, Voco) were tested. The labial dentin of sixty bovine incisors was exposed, and the teeth were divided into two groups according to the application or not of an extra hydrophobic resin layer (Scotchbond Multi Purpose Plus, bottle 3). Six composite cylinders (Filtek Z250, 3M ESPE) were built up on each treated surface. Specimens were stored in distilled water at 37ºC for 24 h and then subjected to the microshear bond strength test in a universal testing machine at a crosshead speed of 0.5 mm/min. Microshear bond strength values were analyzed by 2-way ANOVA and Tukey's post-hoc test. Failure mode was determined using a stereomicroscope under 20X magnification. The application of the hydrophobic resin layer did not affect bond strength, except for AdheSE. However, the bond strengths with the hydrophobic layer were similar among the six tested systems (Clearfil: 17.1 ± 7.9; AdheSE: 14.5 ± 7.1; Xeno lll: 12.8 ± 7.7; I Bond: 9.5 ± 5.8; Bond Force: 17.5 ± 4.1; Futurabond: 7.7 ± 2.3). When used as recommended by the manufacturers, Bond Force presented statistically higher bond strength than AdheSE and I Bond (p AdheSE 1.6 ± 1.6; Xeno lll: 9.0 ± 3.8; I Bond: 3.0 ± 1.5; Bond Force: 14 ± 3.9; Futurabond: 8.8 ± 3.8). Failure mode was predominantly adhesive. The bond strength of the self-etching systems tested was not significantly affected by the application of a hydrophobic layer, but a significant improvement was observed in AdheSE.

Physicochemical characteristics and sensory acceptability of ready-to-eat sliced frozen roast beef with partial reduction of sodium chloride

Directory of Open Access Journals (Sweden)

Camila Vespúcio BIS

2016-01-01

Full Text Available Abstract Sodium chloride in meat products provides microbiological stability and desirable technological and sensory effects. Therefore, the reduction of this ingredient is a challenge for the meat industry. The objective of this study was to evaluate the physicochemical and sensory characteristics of ready-to-eat sliced frozen roast beef with partial replacement of sodium chloride by a commercial additive mostly composed of potassium chloride. The analyses performed were chemical composition, cooking yield and post defrosting loss, microbiological evaluation and sensory analysis. There was higher moisture content (p < 0.05 in the control treatment (without the presence of the replacement additive and all treatments were not different (p ≥ 0.05 in the cooking yield and in post-defrosting loss. The results of microbiological analysis are according to Brazilian Legislation. The sensory evaluation showed no difference between the control treatment and the T1 treatment (with the reduction of 35% of NaCl, while the T2 treatment (with reduction of 70% of NaCl had the lowest average values in all attributes. The study showed that the reduction of 35% NaCl for commercial additive, mostly composed of potassium chloride, in roast beef is feasible since no changes were observed in sensory and technological characteristics evaluated.

The Influence of Injection Timing on Performance Characteristics of Diesel Engine Using Jatropha Biodiesel with and without Partial Hydrogenation

Directory of Open Access Journals (Sweden)

Rizqon Fajar

2014-07-01

Full Text Available Experimental research has been conducted to investigate the effects of blend of hydrogenated and unhydrogenated Jatropha biodiesel with diesel fuel in volume ratio of 30:70 (B30 on combustion characteristics (BSFC, thermal efficiency and smoke emission of single cylinder diesel engine. In this experiment, engine speed was kept constant at 1,500, 2,500, and 3,500 rpm with maximum engine load at BMEP 5 bar and injection timings were varied. Experimental result showed that at engine speed 1,500 rpm, BSFC of B30 hydrogenated and unhydrogenated Jatropha biodiesel were higher than it of diesel fuel at all injection timings (10° to 18° BTDC. At the same condition, partial hydrogenated Jatropha biodiesel showed higher BSFC than unhydrogenated Jatropha biodiesel. However, the difference in BSFC became smaller for all fuels at engine speed 2,500 rpm and 3,500 rpm at all injection timing. Jatropha biodiesel with and without partial hydrogenation tend to have higher thermal efficiency compared with diesel fuel at all engine speed and injection timing. The best injection timings to operate B30 Jatropha biodiesel with and without hydrogenation were 14°, 18° and 24° BTDC at engine speed 1,500, 2,500, and 3,500 rpm respectively. This conclusion was deduced based on the minimum value of BSFC and the maximum value of thermal efficiency. Smoke emissions for all fuels were in the same level for all conditions.

Preparation and performance of Pt/PTFE/Foam SiC as a hydrophobic catalyst for LPCE

International Nuclear Information System (INIS)

He, Jianchao; Wang, Heyi; Xiao, Chengjian; Li, Jiamao; Chen, Ping; Hou, Jingwei

2016-01-01

Highlights: • A new type of foam material, Foam SiC with three-dimensional network structure, was chosen as the carrier of catalyst. • Foam SiC was hydrophobic treated by PTFE, and achieved a good hydrophobic property. • Pt/PTFE/Foam SiC was prepared by impregnation method with Pt-organic solution and gaseous phase reduction method. • The hydrophobic catalysts were packed with Dixon phosphor bronze gauze rings (about 3 mm × 3 mm) in LPCE system to test the catalytic performance. • The effect of different size of the catalyst on LPCE was been tested. - Abstract: Platinum catalysts supported on a composite of polytetrafluoroethylene (PTFE) and Foam SiC (Pt/PTFE/Foam SiC) have been proposed and prepared by an impregnation method. The as-prepared Pt/PTFE/Foam SiC was characterized by compression load testing, dynamic contact angle measurement, SEM, XRD, and TEM. The results show that the catalyst prepared by triple hydrophobic treatment had an initial contact angle of 134.2°, a good compression performance of 3.2 MPa, and platinum nanoparticles of 12.1 nm (average size). The catalytic activity of the catalyst was tested with different packing methods, reaction temperatures, and gas-liquid ratios. An excellent hydrogen isotope exchange performance was observed using a hydrophilic packing material-to-catalyst ratio of 25% and reaction temperature of 80 °C. Pt/PTFE/Foam SiC may be used as a hydrophobic catalyst for a water detritiation system (WDS) via a liquid-phase catalytic exchange process (LPCE).

Preparation and performance of Pt/PTFE/Foam SiC as a hydrophobic catalyst for LPCE

Energy Technology Data Exchange (ETDEWEB)

He, Jianchao; Wang, Heyi, E-mail: hywang@caep.cn; Xiao, Chengjian; Li, Jiamao; Chen, Ping; Hou, Jingwei

2016-12-15

Highlights: • A new type of foam material, Foam SiC with three-dimensional network structure, was chosen as the carrier of catalyst. • Foam SiC was hydrophobic treated by PTFE, and achieved a good hydrophobic property. • Pt/PTFE/Foam SiC was prepared by impregnation method with Pt-organic solution and gaseous phase reduction method. • The hydrophobic catalysts were packed with Dixon phosphor bronze gauze rings (about 3 mm × 3 mm) in LPCE system to test the catalytic performance. • The effect of different size of the catalyst on LPCE was been tested. - Abstract: Platinum catalysts supported on a composite of polytetrafluoroethylene (PTFE) and Foam SiC (Pt/PTFE/Foam SiC) have been proposed and prepared by an impregnation method. The as-prepared Pt/PTFE/Foam SiC was characterized by compression load testing, dynamic contact angle measurement, SEM, XRD, and TEM. The results show that the catalyst prepared by triple hydrophobic treatment had an initial contact angle of 134.2°, a good compression performance of 3.2 MPa, and platinum nanoparticles of 12.1 nm (average size). The catalytic activity of the catalyst was tested with different packing methods, reaction temperatures, and gas-liquid ratios. An excellent hydrogen isotope exchange performance was observed using a hydrophilic packing material-to-catalyst ratio of 25% and reaction temperature of 80 °C. Pt/PTFE/Foam SiC may be used as a hydrophobic catalyst for a water detritiation system (WDS) via a liquid-phase catalytic exchange process (LPCE).

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.

Growth of tin oxide thin films composed of nanoparticles on hydrophilic and hydrophobic glass substrates by spray pyrolysis technique

Energy Technology Data Exchange (ETDEWEB)

Paloly, Abdul Rasheed; Satheesh, M. [Nano Functional Materials Lab, Department of Physics, Cochin University of Science and Technology, Kochi 682022, Kerala (India); Martínez-Tomás, M. Carmen; Muñoz-Sanjosé, Vicente [Departamento de Física Aplicada y Electromagnetismo, Universitat de Valencia, c/Dr Moliner 50, Burjassot, Valencia 46100 (Spain); Rajappan Achary, Sreekumar [Nano Functional Materials Lab, Department of Physics, Cochin University of Science and Technology, Kochi 682022, Kerala (India); Bushiri, M. Junaid, E-mail: junaidbushiri@gmail.com [Nano Functional Materials Lab, Department of Physics, Cochin University of Science and Technology, Kochi 682022, Kerala (India)

2015-12-01

Highlights: • SnO{sub 2} thin films were grown on hydrophilic and hydrophobic glass substrates. • Samples on hydrophobic substrates are having comparatively larger lattice volume. • Films on hydrophobic substrates have larger particles and low density distribution. • Substrate dependent photoluminescence emission is observed and studied. • SnO{sub 2} thin films grown over hydrophobic substrates may find potential applications. - Abstract: In this paper, we have demonstrated the growth of tin oxide (SnO{sub 2}) thin films composed of nanoparticles on hydrophobic (siliconized) and hydrophilic (non-siliconized) glass substrates by using the spray pyrolysis technique. X-ray diffraction (XRD) analysis confirmed the formation of SnO{sub 2} thin films with tetragonal rutile-phase structure. Average particle size of nanoparticles was determined to be in the range of 3–4 nm measured from the front view images obtained by a field emission gun scanning electron microscope (FESEM), while the size of nanoparticle clusters, when present, were in the range of 11–20 nm. Surface morphology of SnO{sub 2} films grown over hydrophobic substrates revealed larger isolated particles which are less crowded compared to the highly crowded and agglomerated smaller particles in films on hydrophilic substrates. Blue shift in the band gap is observed in samples in which the average particle size is slightly larger than the exciton Bohr radius. Photoluminescence (PL) analysis of samples grown over hydrophobic substrates exhibited an intense defect level emission and a weak near band edge emission. The enhanced visible emission from these SnO{sub 2} thin films is attributed to lattice defects formed during the film growth due to the mismatch between the film and the hydrophobic substrate surface.

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

Oil field and freshwater isolates of Shewanella putrefaciens have lipopolysaccharide polyacrylamide gel profiles characteristic of marine bacteria

International Nuclear Information System (INIS)

Pickard, C.; Foght, J.M.; Pickard, M.A.; Westlake, D.W.S.

1993-01-01

The lipopolysaccharide structure of oil field and freshwater isolates of bacteria that reduce ferric iron, recently classified as strains of Shewanella putrefaciens, was analyzed using polyacrylamide gel electrophoresis and a lipopolysaccharide-specific silver-staining procedure. The results demonstrate that all the oil field and freshwater isolates examined exhibited the more hydrophobic R-type lipopolysaccharide, which has been found to be characteristic of Gram-negative marine bacteria. This hydrophobic lipopolysaccharide would confer an advantage on bacteria involved in hydrocarbon degradation by assisting their association with the surface of oil droplets. 15 refs., 1 fig

[Partial splenectomy in sickle cell disease].

Science.gov (United States)

Gutiérrez Díaz, A I; Svarch, E; Arencibia Núñez, A; Sabournin Ferrier, V; Machín García, S; Menendez Veitía, A; Ramón Rodriguez, L; Serrano Mirabal, J; García Peralta, T; López Martin, L G

2015-04-01

Total splenectomy in sickle cell disease is related to a high risk of fulminant sepsis and increased incidence of other events, which have not been reported in patients with partial splenectomy. In this study we examined the patients with sickle cell disease and partial splenectomy and compared the clinical and laboratory results with non-splenectomized patients. We studied 54 patients with sickle cell disease who underwent partial splenectomy in childhood from 1986 until 2011 at the Institute of Hematology and Immunology. They were compared with 54 non-splenectomized patients selected by random sampling with similar characteristics. Partial splenectomy was performed at a mean age of 4.1 years, with a higher frequency in homozygous hemoglobin S (70.4%), and the most common cause was recurrent splenic sequestration crisis. The most common postoperative complications were fever of unknown origin (14.8%) and acute chest syndrome (11.1%). After splenectomy there was a significant increase in leukocytes, neutrophils, and platelets, the latter two parameters remained significantly elevated when compared with non-splenectomized patients. There was no difference in the incidence of clinical events, except hepatic sequestration, which was more common in splenectomized patients. Partial splenectomy was a safe procedure in patients with sickle cell disease. There were no differences in the clinical picture in children splenectomized and non-splenectomized except the greater frequency of hepatic sequestration crisis in the first group. Copyright © 2013 Asociación Española de Pediatría. Published by Elsevier España, S.L.U. All rights reserved.

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.

Metal Enhanced Fluorescence on Super-Hydrophobic Clusters of Gold Nanoparticles

KAUST Repository

Battista, Edmondo; Coluccio, Maria Laura; Alabastri, Alessandro; Barberio, Marianna; Causa, Filippo; Netti, Paolo Antonio; Di Fabrizio, Enzo M.; Gentile, Francesco

2016-01-01

We used optical lithography, electroless deposition and deep reactive ion etching techniques to realize arrays of super-hydrophobic gold nanoparticles arranged in a hierarchical structure. At the micro-scale, silicon-micro pillars in the chip permit to manipulate and concentrate biological solutions, at the nano-scale, gold nanoparticles enable metal enhanced fluorescence (MEF) effects, whereby fluorescence signal of fluorophores in close proximity to a rough metal surface is amplified by orders of magnitude. Here, we demonstrated the device in the analysis of fluorescein derived gold-binding peptides (GBP-FITC). While super-hydrophobic schemes and MEF effects have been heretofore used in isolation, their integration in a platform may advance the current state of fluorescence-based sensing technology in medical diagnostics and biotechnology. This scheme may be employed in protein microarrays where the increased sensitivity of the device may enable the early detection of cancer biomarkers or other proteins of biomedical interest.

Metal Enhanced Fluorescence on Super-Hydrophobic Clusters of Gold Nanoparticles

KAUST Repository

Battista, Edmondo

2016-12-15

We used optical lithography, electroless deposition and deep reactive ion etching techniques to realize arrays of super-hydrophobic gold nanoparticles arranged in a hierarchical structure. At the micro-scale, silicon-micro pillars in the chip permit to manipulate and concentrate biological solutions, at the nano-scale, gold nanoparticles enable metal enhanced fluorescence (MEF) effects, whereby fluorescence signal of fluorophores in close proximity to a rough metal surface is amplified by orders of magnitude. Here, we demonstrated the device in the analysis of fluorescein derived gold-binding peptides (GBP-FITC). While super-hydrophobic schemes and MEF effects have been heretofore used in isolation, their integration in a platform may advance the current state of fluorescence-based sensing technology in medical diagnostics and biotechnology. This scheme may be employed in protein microarrays where the increased sensitivity of the device may enable the early detection of cancer biomarkers or other proteins of biomedical interest.

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.

Nonlinear correlations in the hydrophobicity and average flexibility along the glycolytic enzymes sequences

International Nuclear Information System (INIS)

Ciorsac, Alecu; Craciun, Dana; Ostafe, Vasile; Isvoran, Adriana

2011-01-01

Research highlights: → We focus our study on the glycolytic enzymes. → We reveal correlation of hydrophobicity and flexibility along their chains. → We also reveal fractal aspects of the glycolytic enzymes structures and surfaces. → The glycolytic enzyme sequences are not random. → Creation of fractal structures requires the operation of nonlinear dynamics. - Abstract: Nonlinear methods widely used for time series analysis were applied to glycolytic enzyme sequences to derive information concerning the correlation of hydrophobicity and average flexibility along their chains. The 20 sequences of different types of the 10 human glycolytic enzymes were considered as spatial series and were analyzed by spectral analysis, detrended fluctuations analysis and Hurst coefficient calculation. The results agreed that there are both short range and long range correlations of hydrophobicity and average flexibility within investigated sequences, the short range correlations being stronger and indicating that local interactions are the most important for the protein folding. This correlation is also reflected by the fractal nature of the structures of investigated proteins.

Hydrophobic, ductile, and transparent nanocellulose films with quaternary alkylammonium carboxylates on nanofibril surfaces.

Science.gov (United States)

Shimizu, Michiko; Saito, Tsuguyuki; Fukuzumi, Hayaka; Isogai, Akira

2014-11-10

Hydrophobic, ductile, and transparent nanocellulose films were prepared by casting and drying aqueous dispersions of 2,2,6,6-tetramethylpiperidine-1-oxyl-oxidized cellulose nanofibrils (TOCNs) with quaternary alkylammoniums (QAs) as counterions for the surface carboxylate groups. TOCN films with tetramethylammonium and tetraethylammonium carboxylates showed high optical transparencies, strain-to-failure values (14-22%), and work-of-fracture values (20-27 MJ m(-3)). The ductility of these films was likely caused by the alkyl chains of the QA groups densely covering the TOCN surfaces and being present at the interfaces between the TOCN elements in the films. The water contact angle of the TOCN-QA films increased to ∼100° by introducing tetra(n-butyl)ammonium groups as counterions. Thus, TOCN film properties can be controlled by changing the chemical structure of the counterions from Na to QAs. The hydrophilic TOCN surfaces can be changed to hydrophobic simply and efficiently by the conversion from TOCN-Na to TOCN-QA, when TOCNs are used as nanofillers in hydrophobic polymer matrices.

Regulation of G-protein coupled receptor traffic by an evolutionary conserved hydrophobic signal.

Science.gov (United States)

Angelotti, Tim; Daunt, David; Shcherbakova, Olga G; Kobilka, Brian; Hurt, Carl M

2010-04-01

Plasma membrane (PM) expression of G-protein coupled receptors (GPCRs) is required for activation by extracellular ligands; however, mechanisms that regulate PM expression of GPCRs are poorly understood. For some GPCRs, such as alpha2c-adrenergic receptors (alpha(2c)-ARs), heterologous expression in non-native cells results in limited PM expression and extensive endoplasmic reticulum (ER) retention. Recently, ER export/retentions signals have been proposed to regulate cellular trafficking of several GPCRs. By utilizing a chimeric alpha(2a)/alpha(2c)-AR strategy, we identified an evolutionary conserved hydrophobic sequence (ALAAALAAAAA) in the extracellular amino terminal region that is responsible in part for alpha(2c)-AR subtype-specific trafficking. To our knowledge, this is the first luminal ER retention signal reported for a GPCR. Removal or disruption of the ER retention signal dramatically increased PM expression and decreased ER retention. Conversely, transplantation of this hydrophobic sequence into alpha(2a)-ARs reduced their PM expression and increased ER retention. This evolutionary conserved hydrophobic trafficking signal within alpha(2c)-ARs serves as a regulator of GPCR trafficking.

Prediction for human intelligence using morphometric characteristics of cortical surface: partial least square analysis.

Science.gov (United States)

Yang, J-J; Yoon, U; Yun, H J; Im, K; Choi, Y Y; Lee, K H; Park, H; Hough, M G; Lee, J-M

2013-08-29

A number of imaging studies have reported neuroanatomical correlates of human intelligence with various morphological characteristics of the cerebral cortex. However, it is not yet clear whether these morphological properties of the cerebral cortex account for human intelligence. We assumed that the complex structure of the cerebral cortex could be explained effectively considering cortical thickness, surface area, sulcal depth and absolute mean curvature together. In 78 young healthy adults (age range: 17-27, male/female: 39/39), we used the full-scale intelligence quotient (FSIQ) and the cortical measurements calculated in native space from each subject to determine how much combining various cortical measures explained human intelligence. Since each cortical measure is thought to be not independent but highly inter-related, we applied partial least square (PLS) regression, which is one of the most promising multivariate analysis approaches, to overcome multicollinearity among cortical measures. Our results showed that 30% of FSIQ was explained by the first latent variable extracted from PLS regression analysis. Although it is difficult to relate the first derived latent variable with specific anatomy, we found that cortical thickness measures had a substantial impact on the PLS model supporting the most significant factor accounting for FSIQ. Our results presented here strongly suggest that the new predictor combining different morphometric properties of complex cortical structure is well suited for predicting human intelligence. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

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

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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.

Hydrophobic silver nanoparticles trapped in lipid bilayers: Size distribution, bilayer phase behavior, and optical properties

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Bothun Geoffrey D

2008-11-01

Full Text Available Abstract Background Lipid-based dispersion of nanoparticles provides a biologically inspired route to designing therapeutic agents and a means of reducing nanoparticle toxicity. Little is currently known on how the presence of nanoparticles influences lipid vesicle stability and bilayer phase behavior. In this work, the formation of aqueous lipid/nanoparticle assemblies (LNAs consisting of hydrophobic silver-decanethiol particles (5.7 ± 1.8 nm embedded within 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC bilayers is demonstrated as a function of the DPPC/Ag nanoparticle (AgNP ratio. The effect of nanoparticle loading on the size distribution, bilayer phase behavior, and bilayer fluidity is determined. Concomitantly, the effect of bilayer incorporation on the optical properties of the AgNPs is also examined. Results The dispersions were stable at 50°C where the bilayers existed in a liquid crystalline state, but phase separated at 25°C where the bilayers were in a gel state, consistent with vesicle aggregation below the lipid melting temperature. Formation of bilayer-embedded nanoparticles was confirmed by differential scanning calorimetry and fluorescence anisotropy, where increasing nanoparticle concentration suppressed the lipid pretransition temperature, reduced the melting temperature, and disrupted gel phase bilayers. The characteristic surface plasmon resonance (SPR wavelength of the embedded nanoparticles was independent of the bilayer phase; however, the SPR absorbance was dependent on vesicle aggregation. Conclusion These results suggest that lipid bilayers can distort to accommodate large hydrophobic nanoparticles, relative to the thickness of the bilayer, and may provide insight into nanoparticle/biomembrane interactions and the design of multifunctional liposomal carriers.

New nanostructured nickel–polymer nanohybrids with improved surface hydrophobicity and effect on the living cells adhesion

International Nuclear Information System (INIS)

Macko, Ján; Oriňak, Andrej; Oriňaková, Renáta; Muhmann, Christian; Petruš, Ondrej; Harvanová, Denisa

2015-01-01

Highlights: • Unique nanohybrid formed from nanostructured nickel covered with polymer layer in being introduced. • Polymer is spin-coated on nanostructured nickel surface. • Nanohybrid surface hydrophobicity extension has been observed. • Adhesion of the cells was studied at nanohybrid surface. • The cells growth was differently inhibited at nanohybrid surface. - Abstract: An intensive gain of surface hydrophobicity has been observed on the differently polar polymer layers spin-coated directly on the previously prepared nanostructured nickel surface to form nanohybrids. Nanostructured nickel layer has been prepared by electrochemical deposition to form polyhedral crystalline nanostructure. Surface morphology and homogeneity of a nanohybrid polymer layer have been monitored by TOF-SIMS and SEM methods. Hydrophobicity extension of nanohybrid surfaces increased nearly linearly with decreasing polarity of single polymers applied and maximum increase in hydrophobicity value obtained was 32%. Novel nanohybrid surfaces functionality has been tested on the different cells adhesion. The results showed cell adhesion followed with an inhibition of the living cells spreading and proliferation on declared nanostructured nickel–polymer nanohybrid surfaces. The maximum inhibition activity of nanohybrid surface against cells line has been observed in a case when polydimethylsiloxane was applied as surface polymeric layer. Preparation of this kind of surface is easy and inexpensive, with many proposed applications where hydrophobic surfaces are required. This also can tend as a model for the preparation of the surfaces with cell anti-adhesion and antimicrobial activity.

Nanostructured oxygen sensor--using micelles to incorporate a hydrophobic platinum porphyrin.

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Fengyu Su

Full Text Available Hydrophobic platinum(II-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorophenyl-porphyrin (PtTFPP was physically incorporated into micelles formed from poly(ε-caprolactone-block-poly(ethylene glycol to enable the application of PtTFPP in aqueous solution. Micelles were characterized using dynamic light scattering (DLS and atomic force microscopy (AFM to show an average diameter of about 140 nm. PtTFPP showed higher quantum efficiency in micellar solution than in tetrahydrofuran (THF and dichloromethane (CH₂Cl₂. PtTFPP in micelles also exhibited higher photostability than that of PtTFPP suspended in water. PtTFPP in micelles exhibited good oxygen sensitivity and response time. This study provided an efficient approach to enable the application of hydrophobic oxygen sensors in a biological environment.

Enhancing stability of industrial turbines using adjustable partial arc bearings

Science.gov (United States)

Chasalevris, Athanasios; Dohnal, Fadi

2016-09-01

The paper presents the principal of operation, the simulation and the characteristics of two partial-arc journal bearings of variable geometry and adjustable/controllable stiffness and damping properties. The proposed journals are supposed to consist of a scheme that enables the periodical variation of bearing properties. Recent achievements of suppressing rotor vibrations using plain circular journal bearings of variable geometry motivate the further extension of the principle to bearings of applicable geometry for industrial turbines. The paper describes the application of a partial-arc journal bearing to enhance stability of high speed industrial turbines. The proposed partial-arc bearings with adjustable/controllable properties enhance stability and they introduce stable margins in speeds much higher than the 1st critical.

[The effect of hydrophobicity of group A beta-hemolytic streptococcus in the process of adherence and biofilm production ].

Science.gov (United States)

2014-01-01

Bacterial cell hydrophobicity and adherence to a substrate are one of the most important factors in biofilm formation. Group A streptococcus is an unstable and low biofilm productor. Importance of biofilm production in streptococcal pathogenesis is still unknown. The aim of this study was to determine the impact of hydrophobicity and adherence on the biofilm production of group A streptococcal invasive and noninvasive isolates, and also to evaluate the stability of biofilm production in time function. Adherence, hydrophobicity and biofilm production were investigated in a total of 172 isolates divided into three groups: noninvasive, low invasive and highly invasive. Adher- ence to uncoated and laminin-coated microtiter plates and biofilm production after 12, 24 and 48 hours of incubation was determined using the method described by Stepanović et al. Hydrophobicity was measured using the MATH test by Rosenberg and SAT test by Lindhal. Correlation between adherence and biofilm produc- tion was detected in the group of noninvasive isolates. These isolates were stable biofilm productors during all three time periods of biofilm production. In the groups of invasive and noninvasive isolates no statistical correlation was detected among the analysed variables. The invasive isolates were un- stable biofilm productors. Noninvasive isolates were stable biofilm producers; as detected, they showed a direct correlation between adherence and biofilm production, and a negative impact of hydrophobicity on the biofilm production. Invasive isolates were unstable biofilm productors; it was observed that there was no correlation between adherence and hydrophobicity with biofilm production.

Structural characteristics of alkaline phosphatase from the moderately halophilic bacterium Halomonas sp. 593

International Nuclear Information System (INIS)

Arai, Shigeki; Yonezawa, Yasushi; Ishibashi, Matsujiro; Matsumoto, Fumiko; Adachi, Motoyasu; Tamada, Taro; Tokunaga, Hiroko; Blaber, Michael; Tokunaga, Masao; Kuroki, Ryota

2014-01-01

In order to clarify the structural basis of the halophilic characteristics of an alkaline phosphatase derived from the moderate halophile Halomonas sp. 593 (HaAP), the tertiary structure of HaAP was determined to 2.1 Å resolution by X-ray crystallography. The structural properties of surface negative charge and core hydrophobicity were shown to be intermediate between those characteristic of halophiles and non-halophiles, and may explain the unique functional adaptation to a wide range of salt concentrations. Alkaline phosphatase (AP) from the moderate halophilic bacterium Halomonas sp. 593 (HaAP) catalyzes the hydrolysis of phosphomonoesters over a wide salt-concentration range (1–4 M NaCl). In order to clarify the structural basis of its halophilic characteristics and its wide-range adaptation to salt concentration, the tertiary structure of HaAP was determined by X-ray crystallography to 2.1 Å resolution. The unit cell of HaAP contained one dimer unit corresponding to the biological unit. The monomer structure of HaAP contains a domain comprised of an 11-stranded β-sheet core with 19 surrounding α-helices similar to those of APs from other species, and a unique ‘crown’ domain containing an extended ‘arm’ structure that participates in formation of a hydrophobic cluster at the entrance to the substrate-binding site. The HaAP structure also displays a unique distribution of negatively charged residues and hydrophobic residues in comparison to other known AP structures. AP from Vibrio sp. G15-21 (VAP; a slight halophile) has the highest similarity in sequence (70.0% identity) and structure (C α r.m.s.d. of 0.82 Å for the monomer) to HaAP. The surface of the HaAP dimer is substantially more acidic than that of the VAP dimer (144 exposed Asp/Glu residues versus 114, respectively), and thus may enable the solubility of HaAP under high-salt conditions. Conversely, the monomer unit of HaAP formed a substantially larger hydrophobic interior comprising 329

Structural characteristics of alkaline phosphatase from the moderately halophilic bacterium Halomonas sp. 593

Energy Technology Data Exchange (ETDEWEB)

Arai, Shigeki; Yonezawa, Yasushi [Japan Atomic Energy Agency, 2-4 Shirakata-shirane, Tokai, Ibaraki 319-1195 (Japan); Ishibashi, Matsujiro [Faculty of Agriculture, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065 (Japan); Matsumoto, Fumiko; Adachi, Motoyasu; Tamada, Taro [Japan Atomic Energy Agency, 2-4 Shirakata-shirane, Tokai, Ibaraki 319-1195 (Japan); Tokunaga, Hiroko [Faculty of Agriculture, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065 (Japan); Blaber, Michael [Florida State University, 1115 West Call Street, Tallahassee, FL 32306-4300 (United States); Tokunaga, Masao [Faculty of Agriculture, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065 (Japan); Kuroki, Ryota, E-mail: kuroki.ryota@jaea.go.jp [Japan Atomic Energy Agency, 2-4 Shirakata-shirane, Tokai, Ibaraki 319-1195 (Japan)

2014-03-01

In order to clarify the structural basis of the halophilic characteristics of an alkaline phosphatase derived from the moderate halophile Halomonas sp. 593 (HaAP), the tertiary structure of HaAP was determined to 2.1 Å resolution by X-ray crystallography. The structural properties of surface negative charge and core hydrophobicity were shown to be intermediate between those characteristic of halophiles and non-halophiles, and may explain the unique functional adaptation to a wide range of salt concentrations. Alkaline phosphatase (AP) from the moderate halophilic bacterium Halomonas sp. 593 (HaAP) catalyzes the hydrolysis of phosphomonoesters over a wide salt-concentration range (1–4 M NaCl). In order to clarify the structural basis of its halophilic characteristics and its wide-range adaptation to salt concentration, the tertiary structure of HaAP was determined by X-ray crystallography to 2.1 Å resolution. The unit cell of HaAP contained one dimer unit corresponding to the biological unit. The monomer structure of HaAP contains a domain comprised of an 11-stranded β-sheet core with 19 surrounding α-helices similar to those of APs from other species, and a unique ‘crown’ domain containing an extended ‘arm’ structure that participates in formation of a hydrophobic cluster at the entrance to the substrate-binding site. The HaAP structure also displays a unique distribution of negatively charged residues and hydrophobic residues in comparison to other known AP structures. AP from Vibrio sp. G15-21 (VAP; a slight halophile) has the highest similarity in sequence (70.0% identity) and structure (C{sup α} r.m.s.d. of 0.82 Å for the monomer) to HaAP. The surface of the HaAP dimer is substantially more acidic than that of the VAP dimer (144 exposed Asp/Glu residues versus 114, respectively), and thus may enable the solubility of HaAP under high-salt conditions. Conversely, the monomer unit of HaAP formed a substantially larger hydrophobic interior

Performance of a Novel Hydrophobic Mesoporous Material for High Temperature Catalytic Oxidation of Naphthalene

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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.

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.

The Effect of Influent Characteristics and Operational Conditions over the Performance and Microbial Community Structure of Partial Nitritation Reactors

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Alejandro Rodriguez-Sanchez

2014-06-01

Full Text Available Nitrogen is a main contaminant of wastewater worldwide. Novel processes for nitrogen removal have been developed over the last several decades. One of these is the partial nitritation process. This process includes the oxidation of ammonium to nitrite without the generation of nitrate. The partial nitritation process has several advantages over traditional nitrification-denitrification processes for nitrogen removal from wastewaters. In addition, partial nitritation is required for anammox elimination of nitrogen from wastewater. Partial nitritation is affected by operational conditions and substances present in the influent, such as quinolone antibiotics. In this review, the impact that several operational conditions, such as temperature, pH, dissolved oxygen concentration, hydraulic retention time and solids retention time, have over the partial nitritation process is covered. The effect of quinolone antibiotics and other emerging contaminants are discussed. Finally, future perspectives for the partial nitritation process are commented upon.

Gibbs free energy of transfer of a methylene group on {UCON + (sodium or potassium) phosphate salts} aqueous two-phase systems: Hydrophobicity effects

International Nuclear Information System (INIS)

Silverio, Sara C.; Rodriguez, Oscar; Teixeira, Jose A.; Macedo, Eugenia A.

2010-01-01

The Gibbs free energy of transfer of a suitable hydrophobic probe can be regarded as a measure of the relative hydrophobicity of the different phases. The methylene group (CH 2 ) can be considered hydrophobic, and thus be a suitable probe for hydrophobicity. In this work, the partition coefficients of a series of five dinitrophenylated-amino acids were experimentally determined, at 23 o C, in three different tie-lines of the biphasic systems: (UCON + K 2 HPO 4 ), (UCON + potassium phosphate buffer, pH 7), (UCON + KH 2 PO 4 ), (UCON + Na 2 HPO 4 ), (UCON + sodium phosphate buffer, pH 7), and (UCON + NaH 2 PO 4 ). The Gibbs free energy of transfer of CH 2 units were calculated from the partition coefficients and used to compare the relative hydrophobicity of the equilibrium phases. The largest relative hydrophobicity was found for the ATPS formed by dihydrogen phosphate salts.

Interactions between nano-TiO{sub 2} and the oral cavity: Impact of nanomaterial surface hydrophilicity/hydrophobicity

Energy Technology Data Exchange (ETDEWEB)

Teubl, Birgit J.; Schimpel, Christa [Institute of Pharmaceutical Sciences, Department of Pharmaceutical Technology, University of Graz, 8010 (Austria); Leitinger, Gerd [Institute of Cell Biology, Histology and Embryology, Research Unit Electron Microscopic Techniques, Medical University of Graz, 8010 (Austria); Center for Medical Research, Medical University of Graz, 8010 (Austria); BioTechMed, Graz 8010 (Austria); Bauer, Bettina [Institute of Pharmaceutical Sciences, Department of Pharmaceutical Technology, University of Graz, 8010 (Austria); Fröhlich, Eleonore [Center for Medical Research, Medical University of Graz, 8010 (Austria); BioTechMed, Graz 8010 (Austria); Zimmer, Andreas [Institute of Pharmaceutical Sciences, Department of Pharmaceutical Technology, University of Graz, 8010 (Austria); BioTechMed, Graz 8010 (Austria); Roblegg, Eva, E-mail: eva.roblegg@uni-graz.at [Institute of Pharmaceutical Sciences, Department of Pharmaceutical Technology, University of Graz, 8010 (Austria); BioTechMed, Graz 8010 (Austria)

2015-04-09

Highlights: • Hydrophilic as well as hydrophobic TiO{sub 2} NPs agglomerated under oral physiological conditions. • Particles penetrated the upper and lower buccal epithelium, independent on the degree of hydrophilicity. • Most of the hydrophobic particles were found in vesicular structures, while hydrophilic particles were freely distributed in the cytoplasm. • Hydrophilic particles had a higher potential to trigger toxic effects (e.g., ROS) than hydrophobic particles. - Abstract: Titanium dioxide (TiO{sub 2}) nanoparticles are available in a variety of oral applications, such as food additives and cosmetic products. Thus, questions about their potential impact on the oro-gastrointestinal route rise. The oral cavity represents the first portal of entry and is known to rapidly interact with nanoparticles. Surface charge and size contribute actively to the particle–cell interactions, but the influence of surface hydrophilicity/hydrophobicity has never been shown before. This study addresses the biological impact of hydrophilic (NM 103, rutile, 20 nm) and hydrophobic (NM 104, rutile, 20 nm) TiO{sub 2} particles within the buccal mucosa. Particle characterization was addressed with dynamic light scattering and laser diffraction. Despite a high agglomeration tendency, 10% of the particles/agglomerates were present in the nanosized range and penetrated into the mucosa, independent of the surface properties. However, significant differences were observed in intracellular particle localization. NM 104 particles were found freely distributed in the cytoplasm, whereas their hydrophobic counterparts were engulfed in vesicular structures. Although cell viability/membrane integrity was not affected negatively, screening assays demonstrated that NM 104 particles showed a higher potential to decrease the physiological mitochondrial membrane potential than NM 103, resulting in a pronounced generation of reactive oxygen species.

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

The heterostructured AAO/CeO2 nanosystem fabricated by electrodeposition for charge storage and hydrophobicity

International Nuclear Information System (INIS)

He, Geping; Fan, Huiqing; Wang, Kaige; Yin, Hongfeng; Wu, Junjun

2013-01-01

Highlights: • Tilted cathode was adopted to fabricate PAAM during the second anodization. • AAO/CeO 2 nanosystem was prepared from PAAM by electrochemical deposition. • The larger the cathode intersection angle, the more the charges are stored in the system. • The system's hydrophobicity was improved by an increase in tilted cathode angle. • The optimum angle of the tilted cathode is 40° for charge storage and hydrophobicity. -- Abstract: Tilted cathode was adopted to prepare porous anodic alumina membrane (PAAM) during the second aluminum anodic oxidation (AAO). A heterostructured AAO/CeO 2 nanosystem was fabricated by filling CeO 2 into the PAAM by electrochemical deposition. The larger the intersection angle of the cathode, the more the charge storage of the fabricated system. A lower potential scan rate is beneficial to the electrochemical charge storage of the system. With the cathode intersection angle increasing, the hydrophobicity of the AAO/CeO 2 system is greatly improved. As the 40° is the optimum angle, the charge storage and hydrophobicity of the system increase with the increasing cathode intersection angle up to 40°. The AAO/CeO 2 system could be utilized in both charge storage and self-cleaning

Comparative videostroboscopic analysis after different external partial laryngectomies

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Mumović Gordana M.

2014-01-01

Full Text Available Background/Aim. After external partial laryngectomias, videostroborscopy is very usefull in evaluation of postoperative phonatory mehanisms showing the “slow motion” of the vibrations of the remaining laryngeal structures. The aim of this paper was to compare the videostroboscopic characteristics of the vibration and to establish the differences in the phonation mechanisms depending on the type of external partial laryngectomy performed. Methods. This prospective study was conducted during the period 2003-2009 at the Ear, Nose and Throat Clinic, Clinical Center of Vojvodina, Novi Sad, including 99 patients with laryngeal carcinoma, treated with open surgical approach using different types of vertical and horizontal partial laryngectomy. Videostroboscopy was used to analyse vibrations of the remaining laryngeal structures. Results. The dominant vibration structure after partial horizontal laryngectomy, chordectomy, frontolateral laryngectomy and three quarter laryngectomy was the remaining vocal fold, after hemilaryngectomy it was the false vocal fold and after subtotal and near total laryngectomy it was the arythenoid. In patients with supracricoid hemilaryngopharyngectomy performed, many different structures were involved in the vibration. After most of the partial laryngectomies, vibrations can be found in the reconstructed part of the defect. In both horizontal and vertical partial laryngectomies movements of the larynx during phonation were mostly medial, while in cricohyoidoglottopexies they were anterior-posterior. Most of the operated patients (72.7% had insufficient occlusion of the neoglottis during the phonation. Conclusion. Videostroboscopy is a useful method in examining the phonation mechanisms of reconstructed laryngeal structures after partial laryngectomy as well as in planning postoperative voice therapy.

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.

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.

Development of coal partial hydropyrolysis process

Energy Technology Data Exchange (ETDEWEB)

Hideaki Yabe; Takafumi Kawamura; Kohichiroh Gotoh; Akemitsu Akimoto [Nippon Steel Corporation, Chiba (Japan)

2005-07-01

Coal partial hydropyrolysis process aims at co-production of high yield of light oil such as BTX and naphthalene and synthesis gas from a low rank coal under a mild hydropyrolysis condition. The characteristic of this process is in the two-staged entrained hydropyrolysis reactor composed of the reformer and gasifier. This reactor arrangement gives us high heat efficiency of this process. So far, in order to evaluate the process concept a small-scale basic experiment and a 1t/day process development unit study were carried out. The experimental results showed that coal volatiles were partially hydrogenated to increase the light oil and hydrocarbon gases at the condition of partial hydropyrolysis such as pressure of 2-3MPa, temperature of 700-900{sup o}C and hydrogen concentration of 30-50%. This process has a possibility of producing efficiently and economically liquid and gas products as chemicals and fuel for power generation. As a further development in the period of 2003 to 2008, a 20t/day pilot plant study named ECOPRO (efficient co-production with coal flash hydropyrolysis technology) has been started to establish the process technologies for commercialization. 12 refs., 6 figs., 3 tabs.

Wave propagations of curvilinear motors driven by partially laminated piezoelectric actuators

International Nuclear Information System (INIS)

Smithmaitrie, Pruittikorn; Suybangdum, Panumas; Muensit, Supasarote; Tzou, Horn-Sen

2008-01-01

A piezoelectric arc stator is the key component delivering driving actions to an ultrasonic curvilinear motor. The arc stator drives the rotor along the arc structure to any specific angular position. Usually conventional stators in ultrasonic motors are fully bounded with piezoelectric patch actuators. To reduce production costs while maintaining similar driving characteristics, an arc stator partially bonded with piezoelectric actuators is proposed and its dynamic characteristics are analyzed in this study. The effect of actuator locations on the wave propagation is investigated. Both analytical and finite element results demonstrate similar dynamic responses. That is, the response of the wave propagation depends on specific locations of piezoelectric actuators. One of the two configurations investigated shows that the partially laminated piezoelectric actuator pattern can also generate rather steady traveling waves on the stator with consistent wave amplitude. This implies that the partially laminated actuator technique could be an alternative actuator pattern to the fully laminated actuators in the design of ultrasonic curvilinear motors or other finite-length ultrasonic motors

Engineering of the E. coli Outer Membrane Protein FhuA to overcome the Hydrophobic Mismatch in Thick Polymeric Membranes

Directory of Open Access Journals (Sweden)

Fioroni Marco

2011-03-01

Full Text Available Abstract Background Channel proteins like the engineered FhuA Δ1-159 often cannot insert into thick polymeric membranes due to a mismatch between the hydrophobic surface of the protein and the hydrophobic surface of the polymer membrane. To address this problem usually specific block copolymers are synthesized to facilitate protein insertion. Within this study in a reverse approach we match the protein to the polymer instead of matching the polymer to the protein. Results To increase the FhuA Δ1-159 hydrophobic surface by 1 nm, the last 5 amino acids of each of the 22 β-sheets, prior to the more regular periplasmatic β-turns, were doubled leading to an extended FhuA Δ1-159 (FhuA Δ1-159 Ext. The secondary structure prediction and CD spectroscopy indicate the β-barrel folding of FhuA Δ1-159 Ext. The FhuA Δ1-159 Ext insertion and functionality within a nanocontainer polymeric membrane based on the triblock copolymer PIB1000-PEG6000-PIB1000 (PIB = polyisobutylene, PEG = polyethyleneglycol has been proven by kinetic analysis using the HRP-TMB assay (HRP = Horse Radish Peroxidase, TMB = 3,3',5,5'-tetramethylbenzidine. Identical experiments with the unmodified FhuA Δ1-159 report no kinetics and presumably no insertion into the PIB1000-PEG6000-PIB1000 membrane. Furthermore labeling of the Lys-NH2 groups present in the FhuA Δ1-159 Ext channel, leads to controllability of in/out flux of substrates and products from the nanocontainer. Conclusion Using a simple "semi rational" approach the protein's hydrophobic transmembrane region was increased by 1 nm, leading to a predicted lower hydrophobic mismatch between the protein and polymer membrane, minimizing the insertion energy penalty. The strategy of adding amino acids to the FhuA Δ1-159 Ext hydrophobic part can be further expanded to increase the protein's hydrophobicity, promoting the efficient embedding into thicker/more hydrophobic block copolymer membranes.

Engineering of the E. coli outer membrane protein FhuA to overcome the hydrophobic mismatch in thick polymeric membranes.

Science.gov (United States)

Muhammad, Noor; Dworeck, Tamara; Fioroni, Marco; Schwaneberg, Ulrich

2011-03-17

Channel proteins like the engineered FhuA Δ1-159 often cannot insert into thick polymeric membranes due to a mismatch between the hydrophobic surface of the protein and the hydrophobic surface of the polymer membrane. To address this problem usually specific block copolymers are synthesized to facilitate protein insertion. Within this study in a reverse approach we match the protein to the polymer instead of matching the polymer to the protein. To increase the FhuA Δ1-159 hydrophobic surface by 1 nm, the last 5 amino acids of each of the 22 β-sheets, prior to the more regular periplasmatic β-turns, were doubled leading to an extended FhuA Δ1-159 (FhuA Δ1-159 Ext). The secondary structure prediction and CD spectroscopy indicate the β-barrel folding of FhuA Δ1-159 Ext. The FhuA Δ1-159 Ext insertion and functionality within a nanocontainer polymeric membrane based on the triblock copolymer PIB(1000)-PEG(6000)-PIB(1000) (PIB = polyisobutylene, PEG = polyethyleneglycol) has been proven by kinetic analysis using the HRP-TMB assay (HRP = Horse Radish Peroxidase, TMB = 3,3',5,5'-tetramethylbenzidine). Identical experiments with the unmodified FhuA Δ1-159 report no kinetics and presumably no insertion into the PIB(1000)-PEG(6000)-PIB(1000) membrane. Furthermore labeling of the Lys-NH(2) groups present in the FhuA Δ1-159 Ext channel, leads to controllability of in/out flux of substrates and products from the nanocontainer. Using a simple "semi rational" approach the protein's hydrophobic transmembrane region was increased by 1 nm, leading to a predicted lower hydrophobic mismatch between the protein and polymer membrane, minimizing the insertion energy penalty. The strategy of adding amino acids to the FhuA Δ1-159 Ext hydrophobic part can be further expanded to increase the protein's hydrophobicity, promoting the efficient embedding into thicker/more hydrophobic block copolymer membranes.

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.

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.

Selective radiolabeling and isolation of the hydrophobic membrane-binding domain of human erythrocyte acetylcholinesterase

International Nuclear Information System (INIS)

Roberts, W.L.; Rosenberry, T.L.

1986-01-01

The hydrophobic, membrane-binding domain of purified human erythrocyte acetylcholinesterase was labeled with the photoactivated reagent 3-(trifluoromethyl)-3-(m-[ 125 I]iodophenyl)diazirine. The radiolabel was incorporated when the enzyme was prepared in detergent-free aggregates, in detergent micelles, or in phospholipid liposomes, but the highest percentage of labeling occurred in the detergent-free aggregates. Papain digestion of the enzyme released the hydrophobic domain, and polyacrylamide gel electrophoresis in sodium dodecyl sulfate or gel exclusion chromatography demonstrated that the label was localized exclusively in the cleaved hydrophobic domain fragment. This fragment was purified in a three-step procedure. Digestion was conducted with papain attached to Sepharose CL-4B, and the supernatant was adsorbed to acridinium affinity resin to remove the hydrophilic enzyme fragment. The nonretained fragment associated with Triton X-100 micelles was then chromatographed on Sepharose CL-6B, and finally detergent was removed by chromatography on Sephadex LH-60 in an ethanol-formic acid solvent. The fragment exhibited an apparent molecular weight of 3100 on the Sephadex LH-60 column when compared with peptide standards. However, amino acid analysis of the purified fragment revealed only 1 mol each of histidine and glycine per mole of fragment in contrast to the 25-30 mole of amino acids expected on the basis of the molecular weight estimate. This result suggests a novel non-amino acid structure for the hydrophobic domain of human erythrocyte acetylcholinesterase

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)

Hydrophobic nanoparticles promote lamellar to inverted hexagonal transition in phospholipid mesophases.

Science.gov (United States)

Bulpett, Jennifer M; Snow, Tim; Quignon, Benoit; Beddoes, Charlotte M; Tang, T-Y D; Mann, Stephen; Shebanova, Olga; Pizzey, Claire L; Terrill, Nicholas J; Davis, Sean A; Briscoe, Wuge H

2015-12-07

This study focuses on how the mesophase transition behaviour of the phospholipid dioleoyl phosphatidylethanolamine (DOPE) is altered by the presence of 10 nm hydrophobic and 14 nm hydrophilic silica nanoparticles (NPs) at different concentrations. The lamellar to inverted hexagonal phase transition (Lα-HII) of phospholipids is energetically analogous to the membrane fusion process, therefore understanding the Lα-HII transition with nanoparticulate additives is relevant to how membrane fusion may be affected by these additives, in this case the silica NPs. The overriding observation is that the HII/Lα boundaries in the DOPE p-T phase diagram were shifted by the presence of NPs: the hydrophobic NPs enlarged the HII phase region and thus encouraged the inverted hexagonal (HII) phase to occur at lower temperatures, whilst hydrophilic NPs appeared to stabilise the Lα phase region. This effect was also NP-concentration dependent, with a more pronounced effect for higher concentration of the hydrophobic NPs, but the trend was less clear cut for the hydrophilic NPs. There was no evidence that the NPs were intercalated into the mesophases, and as such it was likely that they might have undergone microphase separation and resided at the mesophase domain boundaries. Whilst the loci and exact roles of the NPs invite further investigation, we tentatively discuss these results in terms of both the surface chemistry of the NPs and the effect of their curvature on the elastic bending energy considerations during the mesophase transition.

Molecular dynamics simulations study of nano bubble attachment at hydrophobic surfaces

Energy Technology Data Exchange (ETDEWEB)

Jin, Jiaqi; Dang, Liem X.; Miller, Jan D.

2018-01-01

Bubble attachment phenomena are examined using Molecular Dynamics Simulations (MDS) for the first time. The simulation involves a nitrogen nano bubble containing 906 nitrogen molecules in a water phase with 74,000 water molecules at molybdenite surfaces. During a simulation period of 1 ns, film rupture and displacement occurs. The attached nanobubble at the hydrophobic molybdenite face surface results in a contact angle of about 90º. This spontaneous attachment is due to a “water exclusion zone” at the molybdenite face surface and can be explained by a van der Waals (vdW) attractive force, as discussed in the literature. In contrast, the film is stable at the hydrophilic quartz (001) surface and the bubble does not attach. Contact angles determined from MD simulations are reported, and these results agree well with experimental and MDS sessile drop results. In this way, film stability and bubble attachment are described with respect to interfacial water structure for surfaces of different polarity. Interfacial water molecules at the hydrophobic molybdenite face surface have relatively weak interactions with the surface when compared to the hydrophilic quartz (001) surface, as revealed by the presence of a 3 Å “water exclusion zone” at the molybdenite/water interface. The molybdenite armchair-edge and zigzag-edge surfaces show a comparably slow process for film rupture and displacement when compared to the molybdenite face surface, which is consistent with their relatively weak hydrophobic character.

Cast Partial Denture versus Acrylic Partial Denture for Replacement of Missing Teeth in Partially Edentulous Patients

Directory of Open Access Journals (Sweden)

Pramita Suwal

2017-03-01

Full Text Available Aim: To compare the effects of cast partial denture with conventional all acrylic denture in respect to retention, stability, masticatory efficiency, comfort and periodontal health of abutments. Methods: 50 adult partially edentulous patient seeking for replacement of missing teeth having Kennedy class I and II arches with or without modification areas were selected for the study. Group-A was treated with cast partial denture and Group-B with acrylic partial denture. Data collected during follow-up visit of 3 months, 6 months, and 1 year by evaluating retention, stability, masticatory efficiency, comfort, periodontal health of abutment. Results: Chi-square test was applied to find out differences between the groups at 95% confidence interval where p = 0.05. One year comparison shows that cast partial denture maintained retention and stability better than acrylic partial denture (p< 0.05. The masticatory efficiency was significantly compromising from 3rd month to 1 year in all acrylic partial denture groups (p< 0.05. The comfort of patient with cast partial denture was maintained better during the observation period (p< 0.05. Periodontal health of abutment was gradually deteriorated in all acrylic denture group (p

Hydrophobic treatment on polymethylmethacrylate surface by nanosecond-pulse DBDs in CF4 at atmospheric pressure

International Nuclear Information System (INIS)

Zhang, Cheng; Zhou, Yang; Shao, Tao; Xie, Qing; Xu, Jiayu; Yang, Wenjin

2014-01-01

Highlights: • Increase in hydrophobicity on PMMA is achieved after the DBD treatment in CF 4 , and the water contact angle can increase from 68° to 100° after treatment. • Nanosecond-pulse DBD is used for the surface treatment and the power density is about 114.8 mW/cm 2 . • The effects of applied voltage, CF 4 flow, and time on plasma treatment are investigated. • Plasma treatment causes morphological change, significantly increases the roughness of the surface, and introduces fluorine-containing groups into the polymethylmethacrylate surface. • Hydrophobic behavior of the treated PMMA surface is slightly affected by the aging effect. - Abstract: Nanosecond-pulse dielectric barrier discharge (DBD) can provide non-thermal plasmas with extremely high energy and high density, which can result in a series of complicated physical and chemical reactions in the surface treatment of polymers. Therefore, in this paper, hydrophobic treatment of polymethylmethacrylate (PMMA) surface is conducted by nanosecond-pulse DBD in carbon tetrafluoride (CF 4 ) at atmospheric pressure. Investigations on surface morphology and chemical composition before and after the DBD treatment in CF 4 are conducted with the contact angle measurement, atomic force microscope, Fourier transform infrared spectroscopy, and X-ray photoelectron spectrometer. The effects of the applied voltage, CF 4 flow rate, and treatment time on the hydrophobic modification are studied. Results show that the contact angles of the treated PMMA surface increases with the applied voltage, and it could be greatly affected by the CF 4 flow rate and the treatment time. The water contact angle can increase from 68° to 100° after the treatment. Furthermore, both surface morphology and chemical composition of the PMMA samples are changed. Both the increase of the surface roughness and the occurrence of fluorine-containing functional groups on the PMMA surface treated by DBD in CF 4 lead to the hydrophobicity

Development of surface wettability characteristics for enhancing pool boiling heat transfer

International Nuclear Information System (INIS)

Kim, Moo Hwan; Jo, Hang Jin

2010-05-01

For several centuries, many boiling experiments have been conducted. Based on literature survey, the characteristic of heating surface in boiling condition played as an important role which mainly influenced to boiling performance. Among many surface factor, the fact that wettability effect is significant to not only the enhancement of critical heat flux(CHF) but also the nucleate boiling heat transfer is also supported by other kinds of boiling experiments. In this regard, the excellent boiling performance (a high CHF and heat transfer performance) in pool boiling could be achieved through some favorable surface modification which satisfies the optimized wettability condition. To find the optimized boiling condition, we design the special heaters to examine how two materials, which have different wettability (e.g. hydrophilic and hydrophobic), affect the boiling phenomena. The special heaters have hydrophobic dots on hydrophilic surface. The contact angle of hydrophobic surface is 120 .deg. to water at the room temperature. The contact angle of hydrophilic surface is 60 .deg. at same conditions. To conduct the experiment with new surface condition, we developed new fabrication method and design the pool boiling experimental apparatus. Through this facility, we can the higher CHF on pattern surface than that on hydrophobic surface, and the higher boiling heat transfer performance on pattern surface than that on hydrophilic surface. Based on this experimental results, we concluded that we proposed new heating surface condition and surface fabrication method to realize the best boiling condition by modified heating surface condition

Thermodynamic analysis of ANS binding to partially unfolded α-lactalbumin: correlation of endothermic to exothermic changeover with formation of authentic molten globules.

Science.gov (United States)

Kim, Ki Hyung; Yun, Soi; Mok, K H; Lee, E K

2016-09-01

A fluorescent reporter, 8-anilino-1-naphthalene sulfonic acid (ANS), can serve as a reference molecule for conformational transition of a protein because its aromatic carbons have strong affinity with hydrophobic cores of partially unfolded molten globules. Using a typical calcium-binding protein, bovine α-lactalbumin (BLA), as a model protein, we compared the ANS binding thermodynamics to the decalcified (10 mM EDTA treated) apo-BLA at two representative temperatures: 20 and 40 °C. This is because the authentic molten globule is known to form more heavily at an elevated temperature such as 40 °C. Isothermal titration calorimetry experiments revealed that the BLA-ANS interactions at both temperatures were entropy-driven, and the dissociation constants were similar on the order of 10(-4)  M, but there was a dramatic changeover in the binding thermodynamics from endothermic at 20 °C to exothermic at 40 °C. We believe that the higher subpopulation of authentic molten globules at 40 °C than 20 °C would be responsible for the results, which also indicate that weak binding is sufficient to alter the ANS binding mechanisms. We expect that the thermodynamic properties obtained from this study would serve as a useful reference for investigating the binding of other hydrophobic ligands such as oleic acid to apo-BLA, because oleic acid is known to have tumor-selective cytotoxicity when complexed with partially unfolded α-lactalbumin. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Comparing complete and partial classification for identifying customers at risk

NARCIS (Netherlands)

Bloemer, J.M.M.; Brijs, T.; Swinnen, S.P.; Vanhoof, K.

2003-01-01

This paper evaluates complete versus partial classification for the problem of identifying customers at risk. We define customers at risk as customers reporting overall satisfaction, but these customers also possess characteristics that are strongly associated with dissatisfied customers. This

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.

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.

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.

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...

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...

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.

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.

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

Effect of surface hydrophobicity on the dynamics of water at the nanoscale confinement: A molecular dynamics simulation study

International Nuclear Information System (INIS)

Choudhury, Niharendu

2013-01-01

Highlights: • We present atomistic MD simulation of water confined between two paraffin-like plates. • Effect of plate hydrophobicity on the confined water dynamics is investigated. • Diffusivity of confined water is calculated from mean squared displacements. • Rotational dynamics of the confined water has bimodal nature of relaxation. • Monotonic dependence of translational and rotational dynamics on hydrophobicity. - Abstract: We present detailed molecular dynamics simulations of water in and around a pair of plates immersed in water to investigate the effect of degree of hydrophobicity or hydrophilicity of the plates on dynamics of water confined between the two plates. The nature of the plate has been tuned from hydrophobic to hydrophilic and vice versa by varying plate-water dispersion interaction. Analyses of the translational dynamics as performed by calculating mean squared displacements of the confined water reveal a monotonically decreasing trend of the diffusivity with increasing hydrophilicity of the plates. Orientational dynamics of the confined water also follows the same monotonic trend. Although orientational time constant almost does not change with the increase of plate-water dispersion interaction in the hydrophobic regime corresponding to the smaller plate-water attraction, it changes considerably in the hydrophilic regime corresponding to larger plate-water dispersion interactions

Comparison of hydrophobic and hydrophilic intraocular lens in preventing posterior capsule opacification after cataract surgery

Science.gov (United States)

Zhao, Yang; Yang, Ke; Li, Jiaxin; Huang, Yang; Zhu, Siquan

2017-01-01

Abstract Background: Posterior capsular opacification (PCO) is a common long-term complication of cataract surgery. Intraocular lens design and material have been implicated in influencing the development of PCO. This study evaluated the association of hydrophobic and hydrophilic intraocular lenses on preventing PCO. Methods: Medline, Cochrane, EMBASE, and Google Scholar databases were searched until August 3, 2016, using the following search terms: cataract, posterior capsule opacification, and intraocular lens. Eligible studies included randomized controlled trials (RCTs), retrospective, and cohort studies. Results: Eleven studies were included in the study with a total of 889 eyes/patients. The overall analysis revealed that hydrophobic intraocular lenses were associated with lower Nd:YAG laser capsulotomy rates than hydrophilic lenses [odds ratio (OR) = 0.38, 95% confidence interval (95% CI) = 0.16–0.91, P = .029]. Hydrophobic intraocular lenses were also associated with lower subjective PCO score (diff. in means: −1.32, 95% CI = −2.39 to −0.25, P = .015) and estimated PCO score (diff. in means: −2.23; 95% CI, −3.80 to −0.68, P = .005) as compared with hydrophilic lenses. Objective PCO score was similar between lens types. (diff. in means: −0.075; 95% CI, −0.18 to 0.035; P = .182). Pooled analysis found that visual acuity was similar between hydrophobic and hydrophilic intraocular lenses (diff. in means: −0.016; 95% CI, −0.041 to 0.009, P = .208). Conclusion: In general, PCO scores and the rate of Nd:YAG laser capsulotomy were influenced by intraocular lens biomaterial. Lens made of hydrophobic biomaterial were overall superior in lowering the PCO score and the Nd:YAG laser capsulotomy rate, but not visual acuity. PMID:29095259

Effect of spatial distribution of wax and PEG-isocyanate on the morphology and hydrophobicity of starch films.

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Muscat, Delina; Adhikari, Raju; Tobin, Mark J; McKnight, Stafford; Wakeling, Lara; Adhikari, Benu

2014-10-13

This study proposes a novel method for improving surface hydrophobicity of glycerol plasticized high amylose (HAG) films. We used polyethylene glycol isocyanate (PEG-iso) crosslinker to link HAG and three natural waxes (beeswax, candelilla wax and carnauba wax) to produce HAG+wax+PEG-iso films. The spatial distributions of wax and PEG-iso across the thickness of these films were determined using Synchrotron-based Fourier transform infrared spectroscopy. The hydrophobicity and surface morphology of the films were determined using contact angle (CA) and scanning electron microscopic measurements, respectively. The distribution patterns of wax and the PEG-iso across the thickness of the film, and the nature of crystalline patterns formed on the surface of these films were found to be the key factors affecting surface hydrophobicity. The highest hydrophobicity (CA >90°) was created when the PEG-iso was primarily distributed in the interior of the films and a hierarchical circular pinnacle structure of solidified wax was formed on the surface. Copyright © 2014 Elsevier Ltd. All rights reserved.

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.

Influence of oxygen partial pressure on the characteristics of human hepatocarcinoma cells.

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Trepiana, Jenifer; Meijide, Susana; Navarro, Rosaura; Hernández, M Luisa; Ruiz-Sanz, José Ignacio; Ruiz-Larrea, M Begoña

2017-08-01

Most of the in vitro studies using liver cell lines have been performed under atmospheric oxygen partial pressure (21% O 2 ). However, the oxygen concentrations in the liver and cancer cells are far from this value. In the present study, we have evaluated the influence of oxygen on 1) the tumor cell lines features (growth, steady-state ROS levels, GSH content, activities of antioxidant enzymes, p66 Shc and SOD expressions, metalloproteinases secretion, migration, invasion, and adhesion) of human hepatocellular carcinoma cell lines, and b) the response of the cells to an oxidant stimulus (aqueous leaf extract of the V. baccifera plant species). For this purpose, three hepatocarcinoma cell lines with different p53 status, HepG2 (wild-type), Huh7 (mutated), and Hep3B (deleted), were cultured (6-30 days) under atmospheric (21%) and more physiological (8%) pO 2 . Results showed that after long-term culturing at 8% versus 21% O 2 , the cellular proliferation rate and the steady-state levels of mitochondrial O 2 - were unaffected. However, the intracellular basal ROS levels were higher independently of the characteristics of the cell line. Moreover, the lower pO 2 was associated with lower glutathione content, the induction of p66 Shc and Mn-SOD proteins, and increased SOD activity only in HepG2. This cell line also showed a higher migration rate, secretion of active metalloproteinases, and a faster invasion. HepG2 cells were more resistant to the oxidative stress induced by V. baccifera. Results suggest that the long-term culturing of human hepatoma cells at a low, more physiological pO 2 induces antioxidant adaptations that could be mediated by p53, and may alter the cellular response to a subsequent oxidant challenge. Data support the necessity of validating outcomes from studies performed with hepatoma cell cultures under ambient O 2 . Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

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.

Effects of copper ions on the characteristics of egg white gel induced by strong alkali.

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Shao, Yaoyao; Zhao, Yan; Xu, Mingsheng; Chen, Zhangyi; Wang, Shuzhen; Tu, Yonggang

2017-09-01

This study investigated the effects of copper ions on egg white (EW) gel induced by strong alkali. Changes in gel characteristics were examined through texture profile analysis, scanning electron microscopy (SEM), and chemical methods. The value of gel strength reached its maximum when 0.1% copper ions was added. However, the lowest cohesiveness values were observed at 0.1%. The springiness of gel without copper ions was significantly greater than the gel with copper ions added. SEM results illustrated that the low concentration of copper ions contributes to a dense and uniform gel network, and an open matrix was formed at 0.4%. The free and total sulphhydryl group content in the egg white protein gel significantly decreased with the increased copper. The increase of copper ions left the contents of ionic and hydrogen bonds basically unchanged, hydrophobic interaction presented an increasing trend, and the disulfide bond exhibited a completely opposite change. The change of surface hydrophobicity proved that the main binding force of copper induced gel was hydrophobic interaction. However, copper ions had no effect on the protein component of the gels. Generally, a low level of copper ions facilitates protein-protein association, which is involved in the characteristics of gels. Instead, high ionic strength had a negative effect on gels induced by strong alkali. © 2017 Poultry Science Association Inc.

Effect of CHF3 Plasma Treatment on the Characteristics of SiCOH Low-k Film

International Nuclear Information System (INIS)

Xing Zhenyu; Ye Chao; Yuan Jing; Xu Yijun; Ning Zhaoyuan

2009-01-01

The characteristics of SiCOH low dielectric constant film treated by a trifluromethane (CHF 3 ) electron cyclotron resonance (ECR) plasma was investigated. The flat-band voltage V FB and leakage current of the Cu/SiCOH/Si structure, and the hydrophobic property of the SiCOH film were obtained by the measurements of capacitance-voltage, current-voltage and water contact angle. The structures of the SiCOH film were also analyzed by Fourier transform infrared spectroscopy and atomic force microscopy. The CHF 3 plasma treatment of the SiCOH film led to a reduction in both the flat-band voltage V FB shift and leakage current of the Cu/SiCOH/Si structure, a decrease in surface roughness, and a deterioration of the hydrophobic property. The changes in the film's characteristics were related to the formation of Si-F bond, the increase in Si-OH bond, and the C:F deposition at the surface of the SiCOH film.

2-Formyl-komarovicine promotes adiponectin production in human mesenchymal stem cells through PPARγ partial agonism.

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Ahn, Sungjin; Lee, Moonyoung; An, Seungchan; Hyun, Sooyeol; Hwang, Jiho; Lee, Jongkook; Noh, Minsoo

2018-03-01

Adiponectin is a major adipocytokine secreted from mammalian adipocytes. Relatively low expression of adiponectin is associated with various human metabolic diseases and some cancers. Adiponectin-secreting compounds have therapeutic potential for these diseases. Adipogenesis of human bone marrow-mesenchymal stem cells (hBM-MSCs) has been used as a phenotypic assay to find adiponectin secreting compounds. In a phytochemical library screen, 2-formyl-komarovicine, 1-(quinolin-8-yl)-1,3,4,9-tetrahydro-2H-pyrido[3,4-b]indole-2-carbaldehyde, isolated from Nitraria komarovii was identified as a potential adiponectin-secreting compound. To validate the results of the impure phytochemical, we synthesized 2-formyl-komarovicine. The synthetic 2-formyl-komarovicine significantly promoted adiponectin production during adipogenesis in hBM-MSCs. In a target identification experiment, 2-formyl-komarovicine bound to peroxisome proliferator-activated receptor γ (PPARγ) in a concentration-dependent manner. Notably, 2-formyl-komarovicine competitively inhibited the adiponectin-promoting activity of a full PPARγ agonist, troglitazone, in hBM-MSCs, which is a pharmacological feature of a partial agonist. The ligand-docking model showed that 2-formyl-komarovicine interacted with the hydrophobic pocket of the PPARγ ligand-binding domain, but lacked an interaction to stabilize helix H12, which is one of the major binding themes of PPARγ partial agonists. We concluded that 2-formyl-komarovicine provides a novel pharmacophore for PPARγ partial agonists to increase adiponectin production. Copyright © 2018 Elsevier Ltd. All rights reserved.

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.

Characteristic of nitrous oxide production in partial denitrification process with high nitrite accumulation.

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Du, Rui; Peng, Yongzhen; Cao, Shenbin; Wang, Shuying; Niu, Meng