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At least 289 records · Page 16Linked to original sources
PubMed1977

Preliminary trials against Biomphalaria glabrata of a new molluscicide formulation: geletin granules containing Bayluscide wettable powder.

Tests were conducted with gelatin granules containing Bayluscide (niclosamide) w.p., 23-3% w/w a.i. Granules rendered a simulated field habitat (banana drain) lethal to Biomphalaria glabrata for 40 days when applied at a rate calculated to give 5 mg/1 in the water. At this dose, Bayluscide e.c. was effective for 8-12 days. Granules exposed to various combinations of natural or simulated tropical climatic factors for up to 56 days gave variable kills of snails, apparently unrelated to the factors tested. The rate at which the molluscicide was released from the granules was affected by climatic factors: high temperatures and low humidities slowed the rate, probably by hardening the granules; rainfall and high humidities accelerated the rate, probably by softening or disintegrating the granules. There was no apparent loss of molluscicidal activity in granules exposed for 56 days to various combinations of climatic factors. The results suggest that this formulation may be applied during droughts to temporary habitats when these are dry and accessible. The molluscicide would then be released at the unpredictable start of the next wet season and kill any snails which survive the drought by aestivation.

Animals↗
PubMed2005

Slip behavior in liquid films on surfaces of patterned wettability: comparison between continuum and molecular dynamics simulations.

We investigate the behavior of the slip length in Newtonian liquids subject to planar shear bounded by substrates with mixed boundary conditions. The upper wall, consisting of a homogenous surface of finite or vanishing slip, moves at a constant speed parallel to a lower stationary wall, whose surface is patterned with an array of stripes representing alternating regions of no shear and finite or no slip. Velocity fields and effective slip lengths are computed both from molecular dynamics (MD) simulations and solution of the Stokes equation for flow configurations either parallel or perpendicular to the stripes. Excellent agreement between the hydrodynamic and MD results is obtained when the normalized width of the slip regions, a/sigma greater than or approximately equal O (10) , where sigma is the (fluid) molecular diameter characterizing the Lennard-Jones interaction. In this regime, the effective slip length increases monotonically with a/sigma to a saturation value. For a/sigma less than or approximately O (10) and transverse flow configurations, the nonuniform interaction potential at the lower wall constitutes a rough surface whose molecular scale corrugations strongly reduce the effective slip length below the hydrodynamic results. The translational symmetry for longitudinal flow eliminates the influence of molecular scale roughness; however, the reduced molecular ordering above the wetting regions of finite slip for small values of a/sigma increases the value of the effective slip length far above the hydrodynamic predictions. The strong correlation between the effective slip length and the liquid structure factor representative of the first fluid layer near the patterned wall illustrates the influence of molecular ordering effects on slip in noninertial flows.

Journal Article↗
PubMed1986

Complement deposition from human sera on silicon surfaces studied in situ by ellipsometry. The influence of surface wettability.

Organic material deposition from human sera on silicon dioxide surfaces was studied in situ by means of ellipsometry, an optical method for quantification of thin organic films. The deposition of organic material from sera was followed continuously for 2 h on hydrophobic and hydrophilic silicon surfaces. Both types of surfaces adsorbed organic material and the additional incubation with anti-C3 resulted in further deposition of organic material indicating the presence of C3 in the organic layers. Addition of EDTA in serum or heat inactivation resulted in a decrease of the amount of organic material deposited on the hydrophobic surface as well as in a lack of subsequent anti-C3 deposition on both hydrophilic and hydrophobic surfaces. Preadsorption with immunoglobulin G on the surfaces caused a pronounced increase of the deposition of material from serum as well as of subsequent anti-C3 deposition. Both effects were absent if EDTA was present in the serum. Our results indicate that complement activation and deposition occur by incubation of human sera on hydrophobic and hydrophilic silicon dioxide surfaces, which are two surfaces with very simple and well-defined chemical composition. The degree of the reversibility of the deposition of immunoglobulin G was furthermore larger on hydrophilic silicon.

Complement Activation↗
PubMed1985

Assessment of the wettability and surface energy of a pharmaceutical powder by liquid penetration.

The use of a technique involving the assessment of the rate of penetration of a liquid into powder beds has been critically evaluated as a method for characterizing the wetting and surface energy of a hydrophobic powder (amylobarbitone). The choice of the perfect wetting liquid has been assessed, and the possible use and value of extrapolation techniques to indicate the theoretical result for water have been explored. Values of 99.5 and 102.8 obtained for the contact angle, and 25.7 and 26.9 mNm-1 for the critical surface energy, were the best estimates obtainable by this technique. Previously reported limitations of the Washburn equation have been considered.

Amobarbital↗
PubMed1999

Switchable tackiness and wettability of a liquid crystalline polymer

The spreading velocity of liquids on the surface of a liquid crystalline polymer can be tremendously affected by a slight temperature change. Indeed, a bulk transition between a highly ordered smectic and an isotropic phase induces a sharp change from a rigid to a soft behavior, with consequent effects on the tack properties of the liquid crystalline polymer and on the dewetting dynamics of a liquid on its surface.

Journal Article↗
PubMed1975

Influence of substrate wettability on the attachment of marine bacteria to various surfaces.

The effect of the initial substrate surface condition, as indicated by the critical surface tension for wetting, on the rate of attachment of marine bacteria to a variety of solid surfaces has been measured. The techniques used to determine the number of bacteria attached per unit surface area were a lipopolysaccharide test utilizing Limulus lysate and direct examination of the surface by scanning electron microscopy. The results obtained by the two techniques are compared and their significance to the control of microbiological slime film formation (microfouling) is discussed.

Journal Article↗
PubMed2005

Dynamics of beta1-integrins in living fibroblasts--effect of substratum wettability.

The dynamics of integrin receptors mobility was studied in living human fibroblasts using fluorescence-labeled beta(1)-integrin monoclonal antibodies. Time-lapse image series were obtained by confocal laser scanning microscopy when cells were adhering on model hydrophilic (clean glass) and hydrophobic (octadecyl-silanized; i.e., ODS) surfaces coated with fibronectin. Direct measurements showed approximately twice-higher velocity of integrins on glass compared to ODS, and these velocities varied in different zones of the cells. A kinetic model and algorithm for quantification of images was developed, and the analysis identified three receptor populations on glass: immobilized (82.76% of all), slow (4.16%), and fast (13.08%), while, on ODS, only two were identified: immobilized (83.36%) and fast (16.64%). Fast integrins in the peripheral zone of cells have maximal velocities of 0.353 +/- 0.02 mum/min (n = 48, four cells) on hydrophilic and 0.218 +/- 0.02 mum/min (n = 30, three cells) on hydrophobic substrata. The slow population has a velocity of 0.114 mum/min (n = 48, four cells). Further analyses show that these velocities also differ significantly in the peripheral and middle zones of cells in a substrate-dependent fashion. A well-defined circular motion of receptors around the cell center expressed mainly on hydrophobic substrata was monitored and quantified as well.

Algorithms↗
PubMed2000

Effect of the wettability characteristics of polyethylene glycol derivatives on the drug release of wax matrices.

The purpose of the present work was to study the relationship between the physicochemical characteristics of different polyethylene glycol aqueous solutions and the kinetics of potassium chloride release from wax matrix samples containing polyethylene glycol derivatives. Potassium chloride was embedded into thermosoftening matrix material to produce a sustained-release dosage form. Potassium chloride release was measured by the rotating paddle method of USP 23 and the dissolution process was characterized by a modified Nernst equation. Physicochemical characteristics--surface tension, dynamic contact angle, viscosity--of the polyethylene glycol aqueous solutions were also determined. The results indicate that the adhesion tension of surfactant containing aqueous solutions has a decisive impact on the prediction of the potassium chloride release rate from wax matrices.

Adhesiveness↗