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PubMed2003

Folpet permeation through nitrile gloves.

The aim of this study was to investigate whether two different brands of unsupported and unlined nitrile gloves protected against aqueous emulsions of a Folpet wettable powder (50% Folpet) using an ASTM type-I-PTC 600 permeation cell at 30.0 +/- 0.1 degrees C held in a shaking water bath. An analytical method to determine Folpet using the internal standard method was first developed based on gas chromatography-mass spectrometry (GC-MS), and gas chromatography-electron capture detection (GC-ECD). A novel pyrolysis GC-ECD technique that quantified the thermal degradation product phthalimide had pg sensitivity suitable to detect the trace amounts of Folpet that permeated. The on-column conversion was (68.0 +/- 9.5) percent at 170 degrees C over the folpet injected mass range of 3 to 148 pg. The challenge solution in the permeation cell was 1.4 mg/mL aqueous emulsion of Folpet wettable powder, and 2-propanol was the collection solvent. After evaporation of the collection solvent, the time weighted average rate of permeation of Folpet through SafeSkin nitrile (an exams type of glove) after 8 hours was (42.1 +/- 2.9) ng/cm(2)/min compared with (2.04 +/- 0.69) ng/cm(2)/min for the Sol-Vex nitrile (industrial chemical resistant), the latter being about 21 times more protective and also near the limits of detection. The respective values after 4 hours of exposure were (28.4 +/- 1.2) and (0.65 +/- 0.36) ng/cm(2)/min. Diagnostic reflectance infrared minima of both challenge and collection sides of the gloves showed small changes in wave number and intensity values after 8 hours of exposure, with Folpet being detected in dried spots on the challenge side. GC-ECD-based permeation and IR reflectance data indicated high chemical resistance of the Sol-Vex gloves to an aqueous emulsion of Folpet.

Chromatography, Gas↗
PubMed2000

Formulation of activated charcoal for per os administration to addicted subjects.

The objective of this work was to develop a galenic form of activated charcoal appropriate for the needs of clinical toxicology. To preserve the adsorption capacity of charcoal, we developed an extemporaneous preparation of activated charcoal intended for clinical toxicology. To improve the wettability of activated charcoal, we used densification by wet granulation. The presence of a viscosity agent is necessary to ensure the homogeneity of the suspension and its adhesiveness on gastric mucous membrane. Five formulations with different viscosity agents were prepared, and their adsorption capacity, wettability, viscosity, and adhesiveness were studied.

Adhesiveness↗
PubMed1999

Improved dissolution behavior of fenbufen by spherical crystallization.

Fenbufen is an analgesic, antipyretic and anti-inflammatory drug that is characterized by poor water solubility, a defect increased by very low wettability. Poor water solubility, particularly at low pH, could decrease absorption in the upper part of the gastrointestinal tract, which would be inconvenient for good bioavailability. Different spherical crystallization processes have been considered as methods to improve fenbufen dissolution behavior. A two-solvent system, in the presence of a bridging liquid, is the only method capable of producing spherical fenbufen crystals. In a first step, fenbufen solubility was considered in different solvents. The drug crystals formed were typically needle shaped. This characteristic was considered as a favorable parameter to obtain spherical crystals. After the selection of the best fenbufen solvent, several ratios of solvent (S)-nonsolvent (NS) (tetrahydrofuran [THF]-demineralized water) were studied. The addition of a bridging liquid (isopropyl acetate) improved spherical crystallization. The results from this method were reproducible batch to batch. The spherical crystals obtained showed a clear improvement in dissolution capacity, probably due to better wettability. Dissolution studies were then carried out on these spherical crystals stored for 1 month at different relative humidities (RHs). The dissolution profiles remained unchanged.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2002

Physico-mechanical characterization of policosanol, a novel hypocholesterolemic drug.

As part of the formulation studies of policosanol, a new hypocholesterolemic drug, a physico-mechanical characterization was developed. Thermal analysis, using differential scanning calorimetry was used to evaluate the purity of policosanol from batch to batch and, also, the particle size distribution. The degree of wettability of policosanol was studied by measuring the contact angle and solubility in different solvents. The compressibility and cohesion of particles were evaluated using a profile of compression forces, ranging between 6.5 kN and 39.0 kN. Also, other properties such as flow properties, true density, and tapped and bulk density were measured. The industrial batches of policosanol that were studied show an adequate purity and a uniform distribution of the particle sizes. Policosanol shows good flow properties, compressibility, and cohesion as well as a low solubility in the majority of the solvents used in the pharmaceutical industry, and its solubility in water or in aqueous solutions was, mainly, null. The wettability of policosanol in the different solvents shows the following order: methylene chloride > ethanol > acetone >> water.

Anticholesteremic Agents↗
PubMed2001

Expression of liver-specific functions by rat hepatocytes seeded in treated poly(lactic-co-glycolic) acid biodegradable foams.

Techniques of liver replacement would benefit patients awaiting donor livers and may be a substitute for transplantation in patients whose livers can regenerate. Poly(lactic-co-glycolic acid) (PLGA) copolymers are biodegradable and have been shown to be useful as scaffolds for seeding and culturing various types of cells. In this study, foam disks were prepared from PLGA (lactic-to-glycolic mole ratio of 85:15) by lyophilization of benzene (5% w/v) solutions. These disks were then used as scaffolds for rat hepatocyte culture. Foams were coated with either a type I collagen gel (0.1% w/v), coated with gelatin (5% w/v), or treated with oxygen plasma (25 W, 90 s) to modify their surface chemistry and wettability. The disks were then seeded with rat hepatocytes (10(6)/mL) and cultured for a period of 2 weeks. All surface treatments resulted in increased hydrophilicity, the greatest being obtained by collagen treatment (contact angle < 10 degrees ), and a minimal decrease in void fraction (5%). DNA content after a 2-week culture period increased proportionally with the wettability of the treated foam surface. Urea synthesis in untreated foams averaged 15.3 +/- 2.3 microg/h/microg DNA, which was significantly higher than that for controls, whereas gelatin and collagen treated foams exhibited urea synthetic rates below the control levels at all times. The DNA content decreased significantly by about 50% between days 1 and 12. PLGA foams, treated and untreated, represent a promising scaffold for scaling up hepatocyte cultures.

Animals↗
PubMedDate not supplied

Effect of culture substrates and fibroblast growth factor addition on the proliferation and differentiation of rat bone marrow stromal cells.

This study is an investigation of the proliferation and differentiation of bone marrow stromal cells (BMSCs) on film substrates with different surface properties. Films of noncharged polymers with several water wettabilities; cell culture plates coated with collagen type I or IV, gelatin, or basic fibroblast growth factor (bFGF); and glass were used. BMSCs isolated from rat bone marrow were cultured on the various substrates in medium with dexamethasone [Dex(+)] or without dexamethasone [Dex(-)] to assess cell proliferation and differentiation. The number of proliferated BMSCs depended on the water wettability of substrates, although the cell number was greater in Dex(-) medium than in Dex(+) medium. Protein-coated substrates exhibited a high proliferation rate compared with noncoated substrates. Alkaline phosphatase (ALP) activity increased with increasing cell number, whereas ALP activity per cell correlated well with cell number. When cultured in Dex(+) medium containing bFGF or on culture plates coated with bFGF, BMSC proliferation tended toward enhancement with an increase in the amount of bFGF added in solution form, whereas it did not depend on the amount of bFGF in coated form. On the other hand, ALP activity and calcium content of BMSCs became maximal with bFGF coated at about 1 x 10(3) to 2 x 10(3) ng, in contrast to bFGF in solution form. Irrespective of the amount of bFGF, ALP activity and calcium content levels for bFGF in coated form were higher than for bFGF in solution form. It is concluded that the type of culture substrate and the manner of addition of bFGF affect the proliferation and differentiation of BMSCs.

Adsorption↗
PubMed1992

Oral toxicity, formulation effects, and field performance of flufenoxuron against the German cockroach (Dictyoptera: Blattellidae).

Laboratory and field studies on the benzoylphenyl urea (BPU) chitin synthetase inhibitor flufenoxuron (DPX EY-059) showed great potential for its use in suppressing infestations of German cockroach, Blattella germanica (L.). When fed continuously to fifth (last) instars, the LC50 of flufenoxuron was estimated at 0.82 ppm (95% FL, 0.76-0.87 ppm). A rating scale specific for BPU effects was developed and shown to be positively correlated with the insect's exposure to concentration of flufenoxuron. Manipulating the particle size of wettable powder formulations of flufenoxuron significantly altered their activity in contact bioassays. Larger particles (volume mean diameter, 12.2 mu; range, 10-20 mu) were more active. Field trials in multifamily housing with this wettable powder formulation at 0.033 and 0.066% (AI) achieved high level (greater than 80%) population suppression within 8 wk of treatment. The potential for the use of flufenoxuron in B. germanica management programs is discussed.

Animals↗
PubMed2002

Minimum cuticular conductance and cuticle features of Picea abies and Pinus cembra needles along an altitudinal gradient in the Dolomites (NE Italian Alps).

Winter desiccation is believed to contribute to stress in coniferous trees growing at the treeline because cuticular conductance increases with altitude. To test whether winter desiccation occurs in high-altitude conifers of the Dolomites (NE Italian Alps), we measured minimum cuticular conductance (g(min)), needle wettability (contact angle) and cuticle thickness in Picea abies (L.) Karst. and Pinus cembra L. needles from December to August. Samples were collected from adult trees along an altitudinal gradient from valley bottom (1050 m a.s.l.) to the treeline (2170 m a.s.l.). The treeline site is one of the highest in the area and is characterized by a generally low wind exposure. Altitude had no effect on g(min) in either species. In P. abies, large seasonal variations in g(min) were recorded but no changes were related to needle age class. Pinus cembra had a low g(min) and appeared to be efficient in reducing needle water losses. There was a significant increase in g(min) with needle aging in P. cembra growing at low altitude that could be related to a shorter needle longevity compared with P. abies. High contact angles (> 110-120 ) suggested the presence of tubular epicuticular waxes on needles of both species. Contact angles were higher (low wettability) in high-altitude needles than in low-altitude needles. By the end of winter, there was no difference in contact angles between needles in the windward and leeward positions. Wax structures transformed toward planar shapes as demonstrated by the decrease in contact angle from winter to summer. In both species, the cuticle was thicker in needles of high-altitude trees than in needles of low-altitude trees and there was no correlation between g(min) and cuticle thickness. Because desiccation resistance did not decrease with altitude in either species, we conclude that they are not susceptible to winter desiccation at the tree line.

Altitude↗
PubMed1990

How important are lens oxygen ratings? They are one of many performance factors.

To prevent corneal edema in most patients, contact lenses must transmit oxygen to the following minimum degree: (a) in daily wear, 24.1 x 10(-9) (cm x ml O2)/(s x ml x mm Hg), and (b) in extended wear, 34.3 x 10(-9) (cm x ml O2)/(s x ml x mm Hg). High Dk/L ratings are particularly important for patients wearing extended wear lenses and for those with exceptionally high corneal oxygen demand. Nevertheless, it is well known that other lens performance properties can be compromised by manipulating material or design parameters to increase the Dk/L rating. Increasing the Dk/L of hydrogel lenses, for example, may lead to problems such as fragility, dehydration, and corneal adherence. Similarly, high-Dk/L, rigid gas-permeable lenses may exhibit poor surface wettability and flexural resistance, base curve radius changes, and possible corneal adherence. Because such problems can compromise visual acuity, affect ease of handling, or decrease comfort, nonoxygen factors may exert a stronger influence on successful lens wear than high oxygen transmissibility alone for most patients. Among the nonoxygen factors important for contact lens wear are good movement, surface wettability, resistance to deposit buildup, and flexural resistance. Clinicians must consider these properties, along with oxygen transmission ratings, when fitting patients with contact lenses. Lenses that exhibit good overall performance, in my view, provide the greatest probability of successful wear.

Contact Lenses↗
PubMed1986

Contact lens surface changes after exposure to surfactant and abrasive cleaning procedures.

Proper lens maintenance is required if contact lens wear is to be successful. Poor compliance or inadequate cleaning may lead to contact lens failures and potentially damage to the eye. With phase contrast microscopy, we addressed the effect of cleaning systems on the physical integrity of a surface-modified lens--the Silcon contact lens. Several cleaners were evaluated for their ability to clean Silcon lenses with minimal damage to the lens surface. The data demonstrated that: all cleaning techniques alter the surface appearance; scratches develop more readily on lenses received with surface irregularities; wettability does not correlate with the extent of surface scratching; recommended cleaning procedures do not directly alter the wettability of the contact lens material; and phase contrast microscopy may be a useful addition to laboratory quality control.

Contact Lenses↗
PubMed2005

Effect of patterned slip on micro- and nanofluidic flows.

We consider the flow of a Newtonian fluid in a nano- or microchannel with walls that have patterned variations in slip length. We formulate a set of equations to describe the effects on an incompressible Newtonian flow of small variations in slip and solve these equations for slow flows. We test these equations using molecular dynamics simulations of flow between two walls which have patterned variations in wettability. Good qualitative agreement and a reasonable degree of quantitative agreement is found between the theory and molecular dynamics simulations. The results of both analyses show that patterned wettability can be used to induce complex variations in flow. Finally we discuss the implications of our results for the design of microfluidic mixers using slip.

Journal Article↗
PubMed2006

Wetting of rings on a nanopatterned surface: a lattice model study.

We perform mean-field density functional theory calculations on a lattice model to study the wetting of a solid substrate decorated with a ring pattern of nanoscale dimensions. We have found three different liquid morphologies on the substrate: a ring morphology where the liquid covers the pattern, a bulge morphology where a droplet is forming on one side of the ring, and a morphology where the liquid forms a cap spanning the nonwetting disk inside the pattern. We investigate the relative stability of these morphologies as a function of the ring size, wall-fluid interaction, and temperature. The results found are in very good agreement with experiments and calculations performed on similar systems at a micrometer length scale. The bulge morphology has also been observed in Monte Carlo simulations of the lattice model. Our results show that (i) morphologies of wetting patterns previously observed on a much larger (microm) scale can also form on a nm length scale, (ii) whether or not this happens depends crucially on the size of the wettable pattern, and (iii) the wettable ring may only be partially wet by the bulge morphology of the fluid. This morphology is a result of a spontaneously broken symmetry in the system.

Journal Article↗
PubMed2006

Periodic habitat loss alters the competitive coexistence between brown trout and bullheads in a small stream over 34 years.

1. Changes in the population density of juvenile sea trout Salmo trutta L. and bullheads Cottus gobio L. were compared in a small stream over 34 years. Both species have a similar diet and obviously live in the same general habitat. Habitat loss was most marked in seven summer droughts: severest in 1976, 1983, 1984, 1995, and less severe but followed by autumn droughts in 1969, 1989 and 1993. The contrasting effects of habitat loss on the two species were examined. 2. For both species, the Ricker curvilinear model significantly fit (P < 0.001) the relationship between initial egg density and survivor density for successive life stages, even though egg densities were much lower for bullheads than trout. These analyses provided evidence for density-dependent population regulation and also identified extreme outliers, most being for year-classes affected by summer droughts. 3. The variable effects of changes in habitable area (= % wettable area in sampling section) were quantified by using the residuals, each residual being the absolute value expressed as a percentage of the expected value from the Ricker curve. Significant relationships between the residuals and habitable area showed that habitat loss had a marked effect on survivor density, this being negative for 0+ and 1+ trout, and positive for 0+, 1+ and 2+/3+ bullheads. 4. Therefore, during periods of habitat loss in the summer months, bullhead density increased at the expense of trout density. Low flows and a decrease in wettable area were associated with a marked reduction in habitat quality for drift-feeding trout and an increase in habitat quality, and perhaps also quantity, for benthic-feeding bullheads. This case study shows that, during a major perturbation, the relationship between the densities of two species can change markedly in favour of the less numerous species. The competitive coexistence between the two species is therefore a dynamic process that changes through time with periodic changes in the environment.

Animals↗
PubMed2005

MHP1, a Magnaporthe grisea hydrophobin gene, is required for fungal development and plant colonization.

Fungal hydrophobins are implicated in cell morphogenesis and pathogenicity in several plant pathogenic fungi including the rice blast fungus Magnaporthe grisea. A cDNA clone encoding a hydrophobin (magnaporin, MHP1) was isolated from a cDNA library constructed from rice leaves infected by M. grisea. The MHP1 codes for a typical fungal hydrophobin of 102 amino acids containing eight cysteine residues spaced in a conserved pattern. Hydropathy analysis of amino acids revealed that MHP1 belongs to the class II group of hydrophobins. The amino acid sequence of MHP1 exhibited about 20% similarity to MPG1, an M. grisea class I hydrophobin. Expression of MHP1 was highly induced during plant colonization and conidiation, but could hardly be detected during mycelial growth. Transformants in which MHP1 was inactivated by targeted gene replacement showed a detergent wettable phenotype, but were not altered in wettability with water. mhp1 mutants also exhibited pleiotropic effects on fungal morphogenesis, including reduction in conidiation, conidial germination, appressorium development and infectious growth in host cells. Furthermore, conidia of mhp1 mutants were defective in their cellular organelles and rapidly lose viability. As a result, mhp1 mutants exhibited a reduced ability to infect and colonize a susceptible rice cultivar. These phenotypes were recovered by re-introduction of an intact copy of MHP1. Taken together, these results indicate that MHP1 has essential roles in surface hydrophobicity and infection-related fungal development, and is required for pathogenicity of M. grisea.

Amino Acid Sequence↗
PubMed1976

The granulation of binary mixtures: the effects of the properties of the component powders on granules.

Sulphanilamide and citric acid individually and in various proportions with lactose, have been granulated by massing and screening. There was an optimum blend, that produced granules of maximum mean size and strength, for each binary system examined. The proportion of the components of this optimal blend was dependent on the physical properties of the second component in a mixture with lactose. Results from three systems, lactose:boric acid, lactose:sulphanilamide and lactose:citric acid indicate that although part dissolution of powder during granulation is a factor affecting granule properties, in some systems other physical properties of the second component may become dominant. It is suggested that the combined effect of cohesiveness and wettability of the powders may make the major contribution to granule strength with the sulphanilamide systems. The ultimate mean granule size produced is determined by the wettability or solubiluty of the powders, or both, in all cases examined. The great affinity of citric acid for aqueous binder solution was the dominant factor determining the properties of granules prepared from lactose:citric acid mixtures.

Boric Acids↗
PubMed1997

Self-Assembly of Mesoscale Objects into Ordered Two-Dimensional Arrays

Regular arrays of topologically complex, millimeter-scale objects were prepared by self-assembly, with the shapes of the assembling objects and the wettability of their surfaces determining the structure of the arrays. The system was composed of solid objects floating at the interface between perfluorodecalin and water and interacting by lateral capillary forces; patterning of the wettability of the surfaces of the objects directs these forces. Self-assembly results from minimization of the interfacial free energy of the liquid-liquid interface. Calculations suggest that this strategy for self-assembly can be applied to objects on a micrometer scale.

Journal Article↗
PubMed1982

Field evaluation of the microbial insecticide Bacillus thuringiensis serotype H-14 against floodwater mosquitoes.

Four experimental formulations of the microbial insecticide Bacillus thuringiensis var. israelensis (serotype H-14) were evaluated in the field against larvae of the floodwater mosquitoes Aedes nigromaculis and Psorophora columbiae with ground and aerial application methods. The formulations included ABG-6108D (Abbott Laboratories, North Chicago, Ill.), a wettable powder containing about 400 IU/mg, Sandoz 402-WDC (Sadoz, Inc., Homestead, Fla.), a flowable concentrate containing 600 IU/mg, and two wettable powder formulations of Bactimos (Biochem Products, Montchanin, Del.), one with 3,000 IU/mg and the other with 6,000 IU/mg. Trials against both species indicated they were similar in susceptibility to B. thuringiensis var. israelensis (serotype H-14), and that by using ground application methods, populations of second and third instars could be reduced by 83 to 100% with ABG-6108 and Sandoz 402-WDC at 0.56 to 1.12 kg/ha and with Bactimos (6,000 IU/mg) at 0.44 kg/ha. When applied aerially, approximately two to three times the ground rates had to be used to obtain similar population reductions. Fourth instars were difficult to control, requiring approximately 1.5 to 2 times the rates required for the earlier instars to obtain 80 to 100% reductions. However, these rates were not sufficient to obtain adequate control if larvae were late fourth instars.

Aedes↗
PubMed1996

Pseudomonas fluorescens adhesion and transport through porous media are affected by lipopolysaccharide composition.

The objectives of this work were (i) to use transposon mutagenesis to produce mutants of Pseudomonas fluorescens that were altered in adhesion ability and transport through porous media and (ii) to identify the alterations in surface characteristics that were responsible for the changes in attachment. Mutants of P. fluorescens were generated with TnphoA, which enabled identification of mutants that were altered in surface proteins. Transposon mutants were screened for alterations in adhesion ability by attachment assays on hydrophobic polystyrene and water-wettable polystyrene. Four TnphoA mutants with increased adhesion to the hydrophobic surface and decreased adhesion to the water-wettable surface were obtained. Transport of the strains through porous media was evaluated by passing suspensions of each mutant and the parent through columns containing quartz sand and determining the number of cells retained in the columns. The mutants all demonstrated increased adhesion and retention in the columns. Southern analysis demonstrated two types of mutants with separate transposon insertion sites. Polyacrylamide gel electrophoresis of the strains demonstrated that the O antigen on the lipopolysaccharide was either attenuated or absent. Lack of this polysaccharide, and the consequent increased exposure of the lipid moiety of the lipopolysaccharide, is probably responsible for the increase in adhesion to the hydrophobic substrata and retention in the sand column. This work combined with previous studies of attachment of P. fluorescens demonstrates that more than one type of polymer can mediate the adhesion of this organism to nonbiological surfaces.

Bacterial Adhesion↗