Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Wettability”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources
PubMed1986

Liquid penetration as a method of assessing the wettability and surface energy of pharmaceutical powders.

The use of a liquid penetration technique to assess the wettability and surface energy of a series of barbiturates, including the use of bicomponent systems, has been critically evaluated. Values of apparent contact angles (theta) obtained using the Washburn relationship (1921) and the Carli & Simioni correction (1979) were found to reflect the practically derived wettability of the powders. Values of gamma c obtained from modified Zisman plots and from Neumann's equation of state did not realistically describe the surface energies of the powders. The nature of alcohol-water mixtures has been examined to assist elucidation of the theoretical problems associated with the technique and to offer a possible explanation for the inadequacies of the surface energy results.

Barbiturates↗
PubMed1983

Influence of substratum wettability on attachment of freshwater bacteria to solid surfaces.

We studied the attachment of a number of freshwater bacteria from River Sowe, Coventry, England, to test substrata. The attachment of each organism to hydrophobic and hydrophilic surfaces was evaluated, and further studies evaluated the attachment of selected isolates to a number of substrata with a range of water wettabilities. The wettability of each substratum was determined by contact angle measurements and was expressed as the work of adhesion (W(A)). No generic pattern of attachment to the test surfaces was found, although the majority of the organisms isolated showed a preference for the hydrophobic surface. A more detailed study of selected isolates showed a relationship between W(A) and number of attached cells. Each bacterium attached in maximum numbers to a surface that was characteristic of that organism and that had a W(A) between 75 and 105 mJ m.

Journal Article↗
PubMed2003

Controlling wettability by light: illuminating the molecular mechanism.

The functionalisation of a surface with an organic monolayer containing photoactive moieties such as the azobenzene chromophore opens an elegant route for controlling its wettability by light. In this paper we investigate the microscopic origin of the macroscopic change in wettability upon photo-induced cis-trans isomerization of a copolymeric diphenyl-diazene Langmuir-Blodgett monolayer. Polarised UV-Vis and FTIR spectroscopy have been used to monitor the orientational order of various functional groups, Atomic Force Microscopy and Imaging Ellipsometry is employed for the quantification of the surface roughness and morphology, contact angle and surface potential measurements are carried out for a characterisation of the polar ordering. The data analysis is further supported by semi-empirical and ab-initio calculations of the molecular dipole moments and the normal IR-modes of the fluorinated chromophore. The combination of all these techniques provides a detailed molecular picture. The data suggest that changes in the projection of the dipole moment onto the surface normal caused by isomerization of the azobenzene are responsible for the observed changes in the surface energy. This knowledge allowed us to predict guidelines for the synthesis of molecules in order to maximize the wetting contrast upon photo-irradiation.

Journal Article↗
PubMed2001

The role of surface wettability on hepatocyte adhesive interactions and function.

In this paper the effect of surface wettability on hepatocyte morphology and function was studied, using clean and octadecylsylane (ODS)-coated glass as a model for hydrophilic and hydrophobic surfaces, respectively. C3A cells--a hepatoblastoma cell line, and freshly obtained porcine hepatocytes were cultured for a short-time period of up to 4 days on the above substrata. Hepatocyte adhesive interactions were characterized monitoring the initial cell attachment, the overall cell morphology, the formation of focal adhesions, and actin filaments. Since hepatocytes showed a clear tendency for homotypic adhesion on ODS, specific E-cadherin staining was used to visualize the intercellular contacts by immunofluorescence microscopy. Additionally, functional assays were carried out to monitor proliferation, metabolic activity, and albumin synthesis of C3A cells. It could be shown that both C3A cells and normal porcine hepatocytes spread better on hydrophilic glass; spreading being accompanied by the development of pronounced actin stress fibers and focal adhesion contacts. In contrast, on hydrophobic substrata predominant cell-cell interactions took place which led to intense E-cadherin staining in the intercellular contacts of porcine hepatocytes but not in C3A cells. On the other hand, metabolic activity and growth of C3A cells were reduced on hydrophobic ODS, but albumin synthesis was similar on both surfaces. It was concluded that the wettability of materials has a strong influence on the attachment and morphology of hepatocytes while the influence of surface properties on the functional activity of hepatocytes still remains to be elucidated.

Albumins↗
PubMed1990

Wettability of polymers by mucin aqueous solutions.

The wettability of poly(methyl methacrylate) and polyethylene by water and aqueous mucin solutions have been studied by sessile drop and under-water captive air bubble contact angles, respectively. From the sessile drop and octane under-water contact angles the polymer-water interfaces have been characterized in terms of works of adhesion and acid-base (polar) interactions. A large water-air contact angle hysteresis observed with poly(methyl methacrylate) surfaces has been attributed to side-chain beta relaxations of polymer ester methyl groups. The wettabilities of the polymers by mucin aqueous solutions have been studied as a function of protein concentration and related to the surface tensions. A positive slope of adhesion tension vs surface tension line, characteristic of polar surfaces, was found with poly(methyl methacrylate). By contrast, a change in the slope, explained as a change in mucin relative adsorption densities at solid/liquid and solid/vapour interfaces, was observed with polyethylene. This adhesion tension behavior appeared to be in agreement with previous data we have published concerning the quantity and state of mucin which are adsorbed to polymers characterized by different surface properties.

Adhesiveness↗
PubMed1999

[Determination of active components in caoyiguang wettable powder by reversed-phase high performance liquid chromatography].

The Caoyiguang wettable powder is composed of two active components, synergists and other additives. The active components, bensulfuron methyl (Londax) and metolachlor (Dual), in 15.5% Caoyiguang wettable powder were determined by reversed phase high performance liquid chromatographic method simultaneously. The ZORBAX SB-C18 column (4.6 mm i.d. x 250 mm, 5 microns) and acidic mixture of methanol and water as mobile phase were used. The results showed that the recoveries were 98.1%-102.6%, and the coefficients of variation were 0.4%-0.8%. The method has been used to determine samples with satisfactory results.

English Abstract↗
PubMed1991

[Wettability and accuracy of reproduction of impression materials].

Traditional elastomeric impression materials, four recently developed "hydrophilic" silicones and a hydrocolloid have been tested for their accuracy of reproduction by use of indirect measurements via plaster dies and for their wettability by means of the sessile drop method. The new silicones are reproducing the original model as exactly as the traditional elastomers. The impression techniques have a stronger influence on the results than the impression materials. Although the new silicones are more hydrophilic than the traditional elastomers, they do not reach the wettability of a hydrocolloid. The results of the indirect measurements and the results of the contact angle measurements are corresponding to the results of other investigations and to literature data of bubble counts of plaster dies made of different impression materials.

Dental Impression Materials↗
PubMedDate not supplied

Wettability of nonaqueous elastomeric impression materials.

The wettability of eight nonaqueous elastomeric impression materials was studied by comparing their contact angles. The materials included three polyethers (one of which was light activated), three hydrophilic poly(vinyl siloxanes), one conventional poly(vinyl siloxane), and one poly(vinyl siloxane) putty. Extracted teeth were prepared to approximate the roughness of a tooth preparation. Contact angles were measured at different time intervals after the start of mixing but were not shown to be significant. The nonhydrophilic poly(vinyl siloxane) materials and the poly(vinyl siloxane) putty were found to be significantly less wettable.

Analysis of Variance↗
PubMed1993

Initial comfort and surface wettability: a comparison between different contact lens materials.

A clinical investigation was performed to compare the initial comfort and surface wettability of the Novalens (Ocu-Tec), ENVISION (Polymer Technology Corporation) and D3X4 (Wesley-Jessen). Fifteen subjects were randomly fit with each one of these three lens materials. Initial comfort was significantly better with the D3X4 lens; no significant difference was found between the two rigid lens materials. No significant difference in lens surface wettability was found between the three materials.

Adult↗
PubMed2005

AFM study of mineral wettability with reservoir oils.

Wettability plays a key role in determining fluid distributions and consequently the multiphase flow and transport in petroleum reservoirs. Many crude oils have polar organic components that collect at oil-water interfaces and can adsorb onto the mineral surface if the brine film breaks, rendering the medium oil-wet or mixed-wet. Mica and silica surfaces have been aged with brine and crude oils to induce oil component adsorption. Bulk oil is eventually replaced by water in these experiments by washing with common solvents without ever drying the mineral surface. The organic deposit on the mineral surface is studied by atomic force microscopy in the tapping mode under water. Drying the surface during the removal of bulk oil induces artifacts; it is essential to keep the surface wet at all times before atomic force microscopy or contact angle measurement. As the mean thickness of the organic deposit increases, the oil-water contact angle increases. The organic deposits left behind after extraction of oil by common aromatic solvents used in core studies, such as toluene and decalin, are thinner than those left behind by non-aromatic solvents, such as cyclohexane. The force of adhesion with a probe sphere for minerals aged with just the asphaltene fraction is similar to that of the whole oil. The force of adhesion for the minerals aged with just the resin fraction is the highest of all SARA (saturates, aromatics, resins, and asphaltenes) fractions.

Adsorption↗
PubMed2005

Variations of wettability and protein adsorption on solid siliceous carriers grafted with poly(N-isopropylacrylamide).

Poly(N-isopropylacrylamide), a thermally responsive polymer, was end-grafted to mercaptopropyl derivatives of silica gel, plane glass sheets and glass capillary tubing by free radical polymerization of the monomer in 1,4-dioxane at 100 degrees C. The polymer monolayer attached to the glass carriers provided them with thermally controlled wettability registered by two independent methods: direct measurements of the water contact angle and capillary rise. The water contact angle changed from 54+/-3 degrees to 68+/-3 degrees in the temperature range from 20 to 50 degrees C. The polymer grafting to silica gel (pore diameter 100 A, particle size 5 microm) resulted in 15-30-fold reduction in protein adsorption on the carrier at 35 degrees C. Adsorption isotherms of myoglobin indicate completely different characters of the protein adsorption to silica gel and its polyNIPAM-grafted derivative. Cooling of the grafted carrier containing adsorbed myoglobin to 9 degrees C led to a partial release of the protein to the contacting solution, whereas heating of the system to 35 degrees C resulted in reversible binding of the protein. Adsorption of myoglobin on polyNIPAM-coated silica was ca. 2-fold higher at 35 than at 9 degrees C, most probably due to steric repulsion displayed by the swollen copolymer at the lower temperature.

Acrylamides↗
PubMed2003

Effect of geometric structure and surface wettability of glidant on tablet hardness.

The aim of this study is to investigate the effect of geometric structure and surface wettability of glidant on tablet hardness. Geometric structure is defined, in this work, as three-dimensional structure such as porosity, particle size and specific surface area. A variety of silica was incorporated in direct compressive fillers as glidant and mixed powder was compressed in single punch tablet machine with and without 0.5 wt.% magnesium stearate. Flowability of mixed powder was evaluated with Carr's index measurement. In the case of unlubricated compression, tablet hardness decreased as a function of additional concentration of silica. Reduction rate directly depended on surface coverage of silica over filler surface and hydrophobicity. Since surface coverage is related to geometric structure, it can be concluded that structural influence plays an important role to determine tablet hardness. While, in the case of lubricated compression, either water adsorption amount or geometric structure effects on tablet hardness. Increase of tablet hardness was observed only when hydrophilic porous and small size nonporous silica were added. All the other silica had deleterious effect on tablet hardness and in particular hydrophobicity strongly reduced tablet hardness.

Adsorption↗
PubMed1996

Quantitative porosity profiles and wettability contrast visualisation in sandstone by CPMG imaging.

CPMG imaging is applied to the visualisation of porosity and wetting heterogeneities in water saturated sandstone samples at 0.1 T. Porosity profiles from NMR imaging are in agreement within 1% with the standard core analysis. T2 calculated profiles show a factor greater than two between water-wet and oil-wet samples; thus, wettability contrast can be easily visualised.

Magnetic Resonance Imaging↗
PubMed1995

Microbial attachment on orthodontic appliances: I. Wettability and early pellicle formation on bracket materials.

The objectives of this study were to investigate the wettability of orthodontic bracket material surfaces and the composition of salivary films adsorbed onto them after 30 and 60 minutes in vivo exposure. Specimens from stainless steel, fiber-reinforced polycarbonate, and polycrystalline alumina bracket manufacturing raw materials were subjected to (a) contact angle measurements with a homologous series of liquids, (b) micro multiple internal reflection Fourier transform infrared spectroscopy (microMIR FTIR) for the characterization of the molecular composition of the in vivo adsorbed groups, and (c) incident light optical microscopy of the acquired films. The highest critical surface tension was obtained from stainless steel (40.8 +/- 0.4 dynes/cm) followed by polycarbonate (32.8 +/- 1.3 dynes/cm) and alumina (29.0 +/- 0.9 dynes/cm), suggesting a higher potential for increased plaque-retaining capacity for the stainless steel brackets. Accordingly, the total work of adhesion and its polar and nonpolar components were consistent with the surface tension ranking. The nonpolar component of the work of adhesion was higher than its polar counterpart for all materials tested, implying a possible higher attachment prevalence for those microorganisms using dispersive forces, such as van der Waals forces, as the predominant attachment mechanism to surfaces. Qualitative and quantitative variations were observed in the adsorbed films after 30 and 60 minutes intraoral exposure that may reflect the influence of the surface properties of these substrates on the structure of the pellicle formed in vivo.

Adhesiveness↗
PubMedDate not supplied

Osteoblast adhesion on poly(L-lactic acid)/polystyrene demixed thin film blends: effect of nanotopography, surface chemistry, and wettability.

Biomaterial surface characteristics are critical cues that regulate cell function. We produced a novel series of poly(l-lactic acid) (PLLA) and polystyrene demixed nanotopographic films to provide nonbiological cell-stimulating cues. The increase in PLLA weight fraction (phi) in blend solutions resulted in topography changes in spin-cast films from pit-dominant to island-dominant morphologies having nanoscale depth or height (3-29 nm). Lower molecular weight PLLA segregated to the top surface of demixed films, as observed by X-ray photoelectron spectroscopy and secondary ion mass spectroscopy (SIMS). For phi > or = 0.5, the topmost film layer was predominantly filled with PLLA (>96% by SIMS at 20-A depth). Nanotextured substrata stimulated osteoblastic cell adhesion to a greater degree than did flat PLLA (phi = 1), and this effect was more pronounced for nanoisland (phi = 0.7 and 0.9) relative to nanopit topographies (phi = 0.5). Demixed films having relatively lower water contact angles generally enhanced cell adhesion and spreading. Our results reveal that cell adhesion is affected by surface chemistry, topography, and wettability simultaneously and that nanotextured surfaces may be utilized in regulating cell adhesion.

Adhesiveness↗
PubMed2006

Topography printing to locally control wettability.

This paper reports a new patterning method, which utilizes NaOH to facilitate the irreversible binding between the PDMS stamp and substrates and subsequent cohesive mechanical failure to transfer the PDMS patterns. Our method shows high substrate tolerance and can be used to "print" various PDMS geometries on a wide range of surfaces, including Si100, glass, gold, polymers, and patterned SU8 photoresist. Using this technique, we are able to locally change the wettability of substrate surfaces by printing well-defined PDMS architectures on the patterned SU8 photoresist. It is possible to generate differential wetting and dewetting properties in microchannels and in the PDMS printed area, respectively.

Adsorption↗
PubMed2005

Light-induced surface wettability of a tethered DNA base.

We show that the DNA base thymine and other uracil derivatives, when alkylated with a hydrocarbon chain and assembled at a gold interface, dimerize when subjected to UV irradiation. The process is robust and reversible and is accompanied by a substantial decrease in wettability as well as a marked decrease in acidity constant when the dimer is formed. There is a concerted molecular reorientation that accompanies photodimerization, with the dimer displaying a marked affinity for the gold surface. The spatial requirements for this reorganization are satisfied during dimerization by the reduction in intermolecular distance that occurs when the cyclobutane ring is formed between adjacent bases. The structural changes observed here for a tethered DNA base provide a direct route for exploring reactions, in two dimensions, that are of central interest in biology.

DNA↗
PubMed2005

Motion of a drop on a solid surface due to a wettability gradient.

The hydrodynamic force experienced by a spherical-cap drop moving on a solid surface is obtained from two approximate analytical solutions and used to predict the quasi-steady speed of the drop in a wettability gradient. One solution is based on approximation of the shape of the drop as a collection of wedges, and the other is based on lubrication theory. Also, asymptotic results from both approximations for small contact angles, as well as an asymptotic result from lubrication theory that is good when the length scale of the drop is large compared with the slip length, are given. The results for the hydrodynamic force also can be used to predict the quasi-steady speed of a drop sliding down an incline.

Hydrodynamics↗