scholarly journals Recovery of Spores from Thermophilic Dairy Bacilli and Effects of Their Surface Characteristics on Attachment to Different Surfaces

2007 ◽  
Vol 74 (3) ◽  
pp. 731-737 ◽  
Author(s):  
R. B. Seale ◽  
S. H. Flint ◽  
A. J. McQuillan ◽  
P. J. Bremer
Keyword(s):  
Milk Powder ◽  
Surface Characteristics ◽  
Phase System ◽  
Simple Relationship ◽  
Two Phase ◽  
Manufacturing Line ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Spore Adherence ◽  
And Control

ABSTRACT Spores from four Geobacillus spp. were isolated from a milk powder manufacturing line in New Zealand. Liquid sporulation media produced spore yields of ∼107 spores ml−1; spores were purified using a two-phase system created with polyethylene glycol 4000 and 3 M phosphate buffer. The zeta potentials of the spores from the four isolates ranged from −10 to −20 mV at neutral pH, with an isoelectric point between pH 3 and 4. Through contact angle measurements, spores were found to be hydrophilic and had relative hydrophobicity values of 10 to 40%, as measured by the microbial adhesion to hexadecane assay. The most hydrophilic spore isolate with the smallest negative charge attached in the highest numbers to Thermanox and stainless steel (1 × 104 spores cm−2), with fewer spores attaching to glass (3 × 103 spores cm−2). However, spores produced by the other three strains attached in similar numbers (P > 0.05) to all substrata (∼1 × 103 spores cm−2), indicating that there was no simple relationship between individual physicochemical interactions and spore adherence. Therefore, surface modifications which limit the attachment of one strain may not be effective for all stains, and control regimens need to be devised with reference to the characteristics of the particular strains of concern.

scholarly journals Surface properties and color stability of an acrylic resin combined with an antimicrobial polymer

2013 ◽  
Vol 42 (4) ◽  
pp. 237-242 ◽  
Author(s):  
Ana Carolina Pero ◽  
Jaqueline Ignárcio ◽  
Gabriela Giro ◽  
Danny Omar Mendoza-Marin ◽  
André Gustavo Paleari ◽  
...  
Keyword(s):  
Surface Properties ◽  
Color Stability ◽  
Acrylic Resin ◽  
Surface Characteristics ◽  
National Bureau ◽  
Color Changes ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Color Data ◽  
Student’S T

INTRODUCTION: The occurrence of stomatitis is common since the surface characteristics of the dentures may act as reservoirs for microorganisms and have the potential to support biofilm formation. PURPOSE: To assess the surface properties (wettability/roughness) and color stability of an acrylic resin combined with the antimicrobial polymer poly (2-tert-butylaminoethyl) methacrylate (PTBAEMA). MATERIAL AND METHOD: Thirty disc-shaped specimens of an acrylic resin (Lucitone 550) were divided into three groups: 0% (control); 5% and 10% PTBAEMA. Surface roughness values (Ra) were measured using a profilometer and wettability was determined through contact angle measurements using a goniometer and deionized water as a test liquid. Color data were measured with a spectrophotometer. Kruskal-Wallis and Dunn's test were used to compare roughness values. Wettability data were analyzed using ANOVA and Tukey's test. Color data were compared using the Student's t-test and ∆E values were classified according to the National Bureau of Standards (NBS). All statistical analyses were performed considering α=.05. RESULT: Significant differences (p<.05) were detected among the groups for roughness, wettability and color stability. According to the NBS, the color changes obtained in the 5% and 10% PTBAEMA groups were "appreciable" and "much appreciable", respectively. CONCLUSION: It could be concluded that PTBAEMA incorporation in an acrylic resin increased the roughness and wettability of surfaces and produced color changes with clinical relevance.

scholarly journals Resole Resin as Sizing Agent for Aramid Fibres

2001 ◽  
Vol 10 (5) ◽  
pp. 096369350101000 ◽  
Author(s):  
J. Bousoulas ◽  
P. A. Tarantili ◽  
A. G. Andreopoulos
Keyword(s):  
Adhesive Bonding ◽  
Chemical Reactivity ◽  
Surface Characteristics ◽  
Fibre Surface ◽  
Phenolic Resins ◽  
Pull Out ◽  
Angle Measurements ◽  
Aramid Fibres ◽  
Contact Angle Measurements ◽  
Epoxy Matrices

A comparative study was made in order to evaluate the interfacial characteristics of treated aramid fibres and epoxy resins. Surface treatment by coating with phenolic resins was performed using the following two systems: a) alkaline aqueous solution of resole resin and b) solution of novolac resin containing hexamethylene-tetramine as cross-linking agent. After these treatments, the modified aramid fibres were used for the preparation of reinforced epoxy specimens. The flexural properties of these specimens were determined and the results were discussed taking into consideration the surface characteristics of the modified fibres, as derived from pull-out tests and contact angle measurements. It was shown that both coatings are adequate to promote interfacial adhesive bonding to epoxy matrices due to the chemical reactivity of phenolic resins to the epoxy matrix as well as to their affinity with the aramid fibre surface. Resole appeared more efficient than novolac as it produces uniform continuous films, shows increased reactivity due to its higher hydroxyl content and can be easily processed because it is soluble in alkaline water solutions.

scholarly journals Epoxy Resin Composites with Surface Modified Aramid Fibres

2000 ◽  
Vol 9 (2) ◽  
pp. 096369350000900 ◽  
Author(s):  
G. Rallis ◽  
P. A. Tarantili ◽  
A. G. Andreopoulos
Keyword(s):  
Epoxy Resin ◽  
Adhesive Bonding ◽  
Surface Characteristics ◽  
Angle Measurements ◽  
Aramid Fibres ◽  
Contact Angle Measurements ◽  
Epoxy Resin Coating ◽  
Additional Support ◽  
Surface Modified ◽  
Epoxy Matrices

Surface modified aramid fibres, after treatment in oxygen plasma and coating with novolac resin, were used for the preparation of reinforced epoxy specimens. The flexural properties of these specimens were determined and the results are discussed taking into consideration the surface characteristics of the modified fibres, as derived from pullout tests and contact angle measurements. Micrographs were also made to provide an additional support to the experimental data of this work. It was shown that both investigated techniques for modifying aramid fibres are adequate to promote their interfacial adhesive bonding to epoxy matrices due to the surface roughness and chemical affinity to the epoxy resin. Coating with novolac seemed a very interesting process since it is a simple and cheap technique and does not affect the fibre integrity.

scholarly journals Preparation and characterization of new hydrogels based on poly(vinyl alcohol)/phosphoester — chondroitin sulphate

2013 ◽  
Vol 11 (3) ◽  
pp. 446-456
Author(s):  
Tachita Vlad-Bubulac ◽  
Diana Serbezeanu ◽  
Ana-Maria Oprea ◽  
Ionela-Daniela Carja ◽  
Corneliu Hamciuc ◽  
...  
Keyword(s):  
Vinyl Alcohol ◽  
Chondroitin Sulphate ◽  
Moisture Sorption ◽  
Kinetic Studies ◽  
Surface Characteristics ◽  
Poly Vinyl Alcohol ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Ft Ir

AbstractAbstract New polymer hydrogels based on partially phosphorylated poly(vinyl alcohol) (PVA/Phosphoester) have been prepared. Fourier transform infrared spectroscopy (FT-IR) was employed to confirm PVA/Phosphoester formation. Contact angle measurements were performed to evaluate the surface characteristics of the hydrogels. The PVA/Phosphoester hydrogels were co-networked with Chondroitin sulfate (CS) in various ratios by chemical crosslinking. The synthetic-natural mixed resulted semi-IPN hydrogels were structurally and morphologically investigated by ATR — FT-IR spectroscopy and scanning electron microscopy, respectively. The swelling behavior and dynamic moisture sorption capacity of the PVA/Phosphoester (p-methyl-phenyl phosphonic dichloride) (P3)-CS semi-IPN hydrogels were followed. It was found that the performance of the semi-IPN hydrogels was influenced by the CS. By kinetic studies, it has been shown that the swelling processes occurred by an anomalous transport mechanism. Graphical abstract

R-ATRP of Acrylamide under the Action of Copper Complex System in Aqueous Two-Phase

2013 ◽  
Vol 652-654 ◽  
pp. 430-434 ◽  
Author(s):  
Kai Liu ◽  
Ya Feng Cao ◽  
Yuan Li ◽  
Zhao Li Liu ◽  
Feng Zhi Tan
Keyword(s):  
Monomer Concentration ◽  
Monomer Conversion ◽  
Control Agent ◽  
Experimental Result ◽  
Polymerization Temperature ◽  
Phase System ◽  
Optimum Conditions ◽  
Two Phase ◽  
Dispersing Agent ◽  
And Control

Polyacrylamide (PAM) was synthesized by combining reverse atom transfer radical polymerization (R-ATRP) with aqueous two-phase polymerization. In aqueous two-phase system, polyethylene glycol 20000 (PEG20000) is used as dispersing agent, potassium persulfate (KPS) and Cu(en)2+are used as initiator and control agent, respectively. In this paper the effect of monomer concentration, the amount of Cu(en)2+, reaction temperature, the ratio of Cu(Ⅱ), and ethylenediamine (en) were investigated. The experimental result shows the optimum conditions are as follows: m(AM)∶m(PEG)=1∶1, the monomer concentration is 10%, n(AM)∶n(CuCl2•2H2O)∶n(en)∶n(KPS)=3000∶10∶20∶1, polymerization time is 6 h, and polymerization temperature is 45°C. Under these conditions, the monomer conversion is 91.5%，the linear correlation coefficient is 0.9911.

Water Repellent Cellulose Nanofibers by Acetylation

2011 ◽  
Vol 332-334 ◽  
pp. 209-212 ◽  
Author(s):  
Alireza Shakeri ◽  
Mehdi Joonobi
Keyword(s):  
Contact Angle ◽  
Cellulose Nanofibers ◽  
Surface Characteristics ◽  
Water Repellent ◽  
High Pressure Homogenization ◽  
X Ray ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Isolation Methods ◽  
Mechanical Isolation

Kenaf nanofibers (NF) were isolated from the kenaf pulp using mechanical isolation methods (refining with super grounding and high pressure homogenization). The kenaf NF were acetylated to produce hydrophobic NF. FTIR results displayed a successful acetylation of the NF. X-ray analysis exhibited that the acetylation process reduced the crystallinity of kenaf NF but also that isolation to NF leads to higher crystallinity than corresponding micro-sized fibers. The contact angle measurements indicated that the acetylation treatment changed the surface characteristics of the kenaf NF from hydrophilic to more hydrophobic.

Spreading Characteristics of Monolayer Lubricant Films on Surfaces With Lube Textures

2005 ◽  
Vol 127 (1) ◽  
pp. 164-170 ◽  
Author(s):  
Hedong Zhang ◽  
Yasunaga Mitsuya ◽  
Natsuko Fukuoka ◽  
Kenji Fukuzawa
Keyword(s):  
Diffusion Coefficients ◽  
Surface Characteristics ◽  
Disk Surface ◽  
Ultraviolet Rays ◽  
Monolayer Film ◽  
Magnetic Disk ◽  
Surface Energies ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Lubricant Films

In this paper, we investigate the effect of lube textures from the viewpoint of lubricant spreading. Lube textures, designating a patterned distribution of bonding strength between lubricant molecules and disk surface, were formed by irradiating ultraviolet rays through a stripe-patterned mask onto a magnetic disk surface which was partially coated with one-monolayer film of perfluoropolyether. Surface characteristics of the lube textures were evaluated by surface energies ascertained from contact angle measurements. Spreading of the lubricant film was measured by scanning microellipsometry on the striped lube textures in the directions parallel and perpendicular to the stripes. The thickness-dependent diffusion coefficients extracted from the spreading profiles show that lubricant spreading in the regime of film thickness less than 0.2 nm is faster along the stripes, indicating the possibility of controlling the behavior of lubricant films with lube textures.

scholarly journals Expression of a Fungal Hydrophobin in the Saccharomyces cerevisiae Cell Wall: Effect on Cell Surface Properties and Immobilization

2002 ◽  
Vol 68 (7) ◽  
pp. 3385-3391 ◽  
Author(s):  
Tiina Nakari-Setälä ◽  
Joana Azeredo ◽  
Mariana Henriques ◽  
Rosário Oliveira ◽  
José Teixeira ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Wall ◽  
Cell Surface ◽  
Surface Properties ◽  
Hydrophobic Interactions ◽  
Surface Characteristics ◽  
Yeast Cells ◽  
Phase System ◽  
Two Phase ◽  
Cell Surface Properties

ABSTRACT The aim of this work was to modify the cell surface properties of Saccharomyces cerevisiae by expression of the HFBI hydrophobin of the filamentous fungus Trichoderma reesei on the yeast cell surface. The second aim was to study the immobilization capacity of the modified cells. Fusion to the Flo1p flocculin was used to target the HFBI moiety to the cell wall. Determination of cell surface characteristics with contact angle and zeta potential measurements indicated that HFBI-producing cells are more apolar and slightly less negatively charged than the parent cells. Adsorption of the yeast cells to different commercial supports was studied. A twofold increase in the binding affinity of the hydrophobin-producing yeast to hydrophobic silicone-based materials was observed, while no improvement in the interaction with hydrophilic carriers could be seen compared to that of the parent cells. Hydrophobic interactions between the yeast cells and the support are suggested to play a major role in attachment. Also, a slight increase in the initial adsorption rate of the hydrophobin yeast was observed. Furthermore, due to the engineered cell surface, hydrophobin-producing yeast cells were efficiently separated in an aqueous two-phase system by using a nonionic polyoxyethylene detergent, C12-18EO5.

Spreading Characteristics of Monolayer Lubricant Film on Surfaces With Lube Textures

2003 ◽  
Author(s):  
Hedong Zhang ◽  
Yasunaga Mitsuya ◽  
Natsuko Fukuoka ◽  
Kenji Fukuzawa
Keyword(s):  
Diffusion Coefficients ◽  
Surface Characteristics ◽  
Disk Surface ◽  
Nonuniform Distribution ◽  
Lubricant Film ◽  
Ultraviolet Rays ◽  
Monolayer Film ◽  
Surface Energies ◽  
Angle Measurements ◽  
Contact Angle Measurements

In this paper, from the viewpoint of lubricant spreading, we investigate the effect of lube textures which mean a nonuniform distribution of bonding strength between lubricant molecules and the disk surface. Lube textures were formed by irradiating ultraviolet rays through a stripe-patterned mask onto a magnetic disk surface which was partially coated with one-monolayer film of perfluoropolyether. Surface characteristics of the lube textures were evaluated by surface energies ascertained from contact angle measurements. Spreading of the lubricant film was measured by scanning microellipsometry on the striped lube textures in the directions parallel and perpendicular to the stripes. The thickness-dependent diffusion coefficients extracted from the spreading profiles show that lubricant spreading in the regime of film thickness less than 0.2 nm is faster along the stripes, indicating the possibility of controlling the behavior of a lubricant film with lube textures.

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