Adhesion

Most industrially applied polymer resins and composites have low surface free energy and lack polar functional groups on their surface, resulting in inherently poor adhesion properties. A strong research momentum to understand polymer adhesion in the last decade has been motivated by the growing needs of the automotive and aerospace industries for better adhesion of components and surface coatings. This paper reviews the recent research efforts on polymer adhesion with a special focus on adhesion mechanisms. It starts with an introduction to adhesion with explanatory notes on adhesion phenomena. Recent research on the adhesion mechanisms of mechanical coupling, chemical bonding and thermodynamic adhesion is then discussed. The area of adhesion promoters is reviewed with the focus on plasma and chemical treatments, along with direct methods for adhesion measurement. The topics of polymer blends and reactive polymerization are considered and the interactions with adhesion mechanisms are reported. The concluding section provides recommendations regarding future research on the contentious aspects of currently accepted adhesion mechanisms and on strategies for enhancing polymer adhesion strength.

Microbially mediated oxidation of Mn(II) to Mn oxides have been demonstrated in previous studies, however, the mechanisms of bacteria how to dissolve and oxidize using a solid Mn(II) origin are poorly understood. In this study, we examined the role of extracellular polymeric substances (EPS) from P. putida strain MnB1 in enhancing dissolution of natural rhodochrosite. The results showed that P. putida strain MnB1 cell can effectively dissolve and oxidize natural rhodochrosite to generate Mn oxides, and EPS were found to play an important role in increasing dissolution of natural rhodochrosite. Compared with EPS-free treatment, dissolution rate of natural rhodochrosite in the presence of bacterial EPS was significantly increased with decreasing initial pH and increasing EPS concentration, ionic strength and rhodochrosite dosage (p < 0.05). The fourier-transform infrared spectroscopy (FTIR) analysis implies that the functional groups like N-H, C=O and C-H in EPS contributed to the dissolution of natural rhodochrosite. This study is helpful for understanding the mechanisms of the formation of biogenic Mn oxides using a solid Mn(II) origin.

We investigate the adhesion of PBT on aluminum using density functional theory-based calculations. The geometric structure of the PBT monomer is first relaxed then an aluminum atom is connected to the monomer in different orientations. We calculate their total energies and determine the orientation that gives the strongest binding between the monomer and the aluminum atom. Binding is strongest when the Al connects linearly with the carbonyl oxygen in the ester group. We present binding mechanisms and total energy relationships for the different orientations.

Green algae of the genus Ulva (syn. Enteromorpha) are common, green macroalgae found throughout the world in the upper intertidal zone of seashores and as a fouling organism on a variety of man-made structures including ships' hulls. Adhesion of motile spores is achieved via the secretion of an adhesive, which is present in spores in highly condensed form within membrane-bound vesicles. The adhesive is initially liquid and displays a hydrogel-like behavior on release. It then starts to undergo ''curing reactions,'' becoming progressively less soluble with time in anionic detergents, less sensitive to proteolysis, and less viscoelastic, which suggests that extensive cross-linking occurs. Spores also become progressively more difficult to detach from a surface. However, the nature of this adhesive curing process is totally unknown. In the present article we have tested the hypothesis that thiol cross-linking may be involved. We show that nontoxic concentrations of the thiol-capping reagent (Ellman's reagent) or thiol-reducing agent (dithiothreitol) effectively inhibit the time-dependent development of adhesive spore strength after attachment to a surface. Furthermore, we show by SDS-PAGE immunoblot analysis of extracted adhesive proteins that the major adhesive antigen retains solubility in the presence of these reagents, after release from spores, which suggests that cross-linking had been inhibited.

Cellulose nanofibers with a size range of 5–100 nm have the potential to be a low cost renewable material that has application in a range of products. However, current chemical methods to produce crystalline nanofibers suffer from low yields and high chemical costs, while mechanical methods require high energy costs. Methods to lower the energy costs of the mechanical methods have not been well documented in the literature. A bleached softwood kraft pulp was processed using a mechanical dispersion mill and a homogenizer to produce cellulose nanofibers. Two different commercial enzymes were used to pretreat the wood fibers before the mechanical treatments. The resulting nanofibers were characterized by light microscopy, atomic force microscopy, and inverse gas chromatography. Results indicate that the dispersion mill does not affect the overall pulp fiber fibrillation, but does help prepare the sample for the homogenizer. Most fibrillation occurs after three passes through the homogenizer. The enzyme pretreatment has little effect on the size of the fibers, but does allow for higher solids to pass through the homogenizer without clogging. The dispersion component of surface energy of the resulting nanofibrils is impacted by the type of enzyme used. The measurement of acid–base properties proved to be challenging using current IGC experimental protocols.

Polyethlene terephthalate films were surface-modified with polyethylene oxide (18 500 g/mol) using a solution technique described previously. These films were investigated for their resistance to bacterial adhesion. Three bacterial strains most commonly associated with implant infections, Staphylococcus epidermidis, Staphylococcus aureus and Pseudomonas aeruginosa, were cultured in tryptic soya broth, human plasma and human serum on the polymeric substrates. Significant reductions (between 70 and 95%) in adherent bacteria were observed on the polyethylene oxide-modified substrates compared to the untreated control polyethylene terephthalate.

Sox2 has yet to be determined. Sox2 can act synergistically with Oct3/4 in vitro to activate Oct-Sox enhancers, which regulate the expression of pluripotent stem cellspecific genes, including Nanog, Oct3/4 and Sox2 itself. These findings suggest that Sox2 is required by ES cells for its Oct-Sox enhancer activity. Using inducible Sox2-null mouse ES cells, we show that Sox2 is dispensable for the activation of these Oct-Sox enhancers. In contrast, we demonstrate that Sox2 is necessary for regulating multiple transcription factors that affect Oct3/4 expression and that the forced expression of Oct3/4 rescues the pluripotency of Sox2-null ES cells. These results indicate that the essential function of Sox2 is to stabilize ES cells in a pluripotent state by maintaining the requisite level of Oct3/4 expression.

In order to develop an advanced polymer based package technology to obtain small and flexible medical implants, diffusion barriers are essential to protect electronic chips and components for corrosion caused by leaching of body fluids. These barriers need also to stop diffusion of harmful products such as Cu from the device into the body. Furthermore, the barrier layers need to be biocompatible, biostable, compatible with all process steps of the package fabrication and sterilization. Parylene is under investigation as candidate barrier material. WVTR tests are performed to characterize diffusion of water through the Parylene layer. Adhesion tests of Parylene-C on various substrates are performed and if needed adhesion promotion treatments are optimized, since good adhesion is crucial for corrosion prevention. Dedicated corrosion tests have shown that 5um Parylene-C is protecting Cu lines for corrosion at 70°C for at least 170 hours, more testing needs to be performed. Cell culture test have shown that Cu diffusion is not sufficiently stopped by 5um Parylene-C or-N, a thicker Parylene layer or a combination with other barriers might be essential. Also dedicated cell culture protocols with non-adherent cell types will have to be developed to perform reliable tests on these hydrophobic and cytophobic barrier layers.

Type 1 fimbriae are surface organelles on Escherichia coli, which mediate specific binding to D-mannosecontaining structures. These fimbriae are heteropolymers composed of a major building element, the FimA protein, and small amounts of the FimF, FimG and FJmH proteins. The FimH protein is uniquely responsible for the D-mannose receptor binding. In this work data are presented which indicate that the major subunit of type 1 fimbriae is dispensable for D-mannose-specific binding. A recombinant strain was studied which harboured an insertional deletion in the fimA gene, and was thereby unable to produce type 1 fimbriae; however, it was still able to express a D-mannose-binding phenotype. However, the deletion resulted in a 25-fold reduction of the adhesive potential, as measured by binding to D-mannosecoated Sepharose beads. Serological and specific receptor binding evidence is presented that suggests that the FimH adhesin is capable of being exposed on the bacterial surface without being an integral part of the fimbriae. . 'For correspondence. Tel. 42 884066; Fax 45 932809.

Objective: To determine the anticandidal activities of Salvia officinalis L. (S. officinalis) essential oil against Candida albicans (C. albicans) and the inhibitory effects on the adhesion of C. albicans to polymethyl methacrylate (PMMA) resin surface. Methods: Disc diffusion method was first used to test the anticandidal activities of the S. officinalis L. essential oil against the reference strain (ATCC 90028) and 2 clinical strains of C. albicans. Then the minimal inhibitory concentration (MIC) and minimal lethal concentration (MLC) were determined by modified membrane method. The adhesion of C. albicans to PMMA resin surface was assessed after immersion with S. officinalis L. essential oil at various concentrations of 1伊MIC, 0.5伊MIC and 0.25伊MIC at room temperature for 30 min. One-way ANOVA was used to compare the Candida cell adhesion with the pretreatment agents and Tukey's test was used for multiple comparisons. Results: S. officinalis L. essential oil exhibited anticandidal activity against all strains of C. albicans with inhibition zone ranging from 40.5 mm to 19.5 mm. The MIC and MLC of the oil were determined as 2.780 g/L against all test strains. According to the effects on C. albicans adhesion to PMMA resin surface, it was found that immersion in the essential oil at concentrations of 1伊MIC (2.780 g/L), 0.5伊MIC (1.390 g/L) and 0.25伊MIC (0.695 g/L) for 30 min significantly reduced the adhesion of all 3 test strains to PMMA resin surface in a dose dependent manner (P<0.05). Conclusions: S. officinalis L. essential oil exhibited anticandidal activities against C. albicans and had inhibitory effects on the adhesion of the cells to PMMA resin surface. With further testing and development, S. officinalis essential oil may be used as an antifungal denture cleanser to prevent candidal adhesion and thus reduce the risk of candida-associated denture stomatitis.

Transdermal drug delivery systems (TDDS), also known as ''patches,'' are dosage forms designed to deliver a therapeutically effective amount of drug across a patient's skin. The adhesive of the transdermal drug delivery system is critical to the safety, efficacy and quality of the product. In the Drug Quality Reporting System (DQRS), the United States Food and Drug Administration (FDA) has received numerous reports of ''adhesion lacking'' for transdermal drug delivery systems. This article provides an overview of types of transdermals, their anatomy, the role of adhesion, the possible adhesion failure modes and how adhesion can be measured. Excerpts from FDA reports on the lack of adhesion of transdermal system products are presented. Pros and cons of in vitro techniques, such as peel adhesion, tack and shear strength, in vivo techniques used to evaluate adhesive properties are discussed. To see a decrease in ''adhesion lacking'' reports, adhesion needs to become an important design parameter and suitable methods need to be available to assess quality and in vivo performance. This article provides a framework for further discussion and scientific work to improve transdermal adhesive performance.

A procedure to increase the adhesion of block styrene-butadiene-styrene (SBS) rubber consisting of the reactive grafting with maleic anhydride (MA) in the presence of an organic peroxide radical initiator is proposed. The in uence of the reactive grafting on the surface properties of SBS has been studied with special emphasis on the improvement of the adhesion to polyurethane adhesive. The grafting of MA onto SBS was carried out in the presence of different concentrations of 2,5-dimethyl-2,5-di(tertbutyl peroxy) hexane (DBPH) as initiator to generate oxygen radicals by thermal decomposition, which induce the grafting reaction. The modi cation process was performed in the molten state using a Brabender mixer to premix the reactants and a hot press to initiate the functionalizing reaction. ATR-IR and XPS spectroscopies were employed to verify the grafting of MA on SBS. The changes in wettability on the modi ed SBS rubber were determined by contact angle measurements. Adhesion properties were evaluated from T-peel tests of SBS rubber/ polyurethane adhesive joints. Reasonable extents of MA grafting on SBS were obtained (evidenced by the presence of a weak carbonyl vibration at 1700 cm ¡1 in the ATR-IR spectra and by the carbon-oxygen band at a binding energy of 287.0 eV in the XPS spectra). The higher the DBPH amount, the higher the MA amount grafted onto the SBS surface. The maximum grafting level was obtained using 2 wt% MA. Grafted species seemed to be mainly concentrated on the surface of the SBS-molded sheets. The wettability of the modi ed rubber increased with respect to the original polymer, new carbon-oxygen moieties were created and the C/ O ratio increased. A noticeable enhancement in peel strength values was observed, which was ascribed to the creation of interfacial interactions between the polyurethane and the SBS rubber surfaces.

Biofilms have been of considerable interest in the context of food hygiene. Of special significance is the ability of microorganisms to attach and grow on food and food-contact surfaces under favourable conditions. Biofilm formation is a dynamic process and different mechanisms are involved in their attachment and growth. Extracellular polymeric substances play an important role in the attachment and colonization of microorganisms to food-contact surfaces. Various techniques have been adopted for the proper study and understanding of biofilm attachment and control. If the microorganisms from food-contact surfaces are not completely removed, they may lead to biofilm formation and also increase the biotransfer potential. Therefore, various preventive and control strategies like hygienic plant lay-out and design of equipment, choice of materials, correct use and selection of detergents and disinfectants coupled with physical methods can be suitably applied for controlling biofilm formation on food-contact surfaces. In addition, bacteriocins and enzymes are gaining importance and have an unique potential in the food industry for the effective biocontrol and removal of biofilms. These newer biocontrol strategies are considered important for the maintenance of biofilm-free systems, for quality and safety of foods.

There is no consensus in the literature regarding the potential toxicity of universal dental adhesives (UDA). Being used in close proximity to the pulp, their biocompatibility should be an important factor in dental research. The aim of the present study was to evaluate the biocompatibility of UDA in an in vitro model. The study was performed using a monocyte/macrophage peripheral blood SC cell line (ATCC CRL-9855) on four specific UDA, namely: All-Bond Universal (Bisco); CLEARFIL Universal Bond Quick (Kuraray); G-Premio BOND (GC); Single Bond Universal (3M ESPE). The cytotoxicity of the investigated UDA was measured using the XTT colorimetric assay. The genotoxicity of the analyzed compounds was evaluated using an alkaline version of the comet assay. Furthermore, flow cytometry (FC) apoptosis detection was performed using the FITC Annexin V Apoptosis Detection Kit I. FC cell-cycle arrest assessment was performed using propidium iodide staining. The study observed significant differ...

Continuous composite processes such as thermoplastic automated tow placement are based on fusion bonding or healing of thermoplastic matrix. A good understanding of interdiffusion and crystallization, the main phenomena at the interface, is important. In order to investigate self-bonding in PEEK (Poly-ether-ether-ketone) and then in the same matrix reinforced by carbon fibers, a new experimental device has been developed allowing to prepare short-time welded samples which were then mechanically characterized using a wedge double cantilever beam test. The corresponding data on mode I critical strain energy release rate as function of processing conditions clearly show that both interdiffusion across the interface and crystallization are key parameters for the strengthening of the interface. Thermal modeling has also been developed and explains the importance of the interface cooling curve for healing.  2005 Elsevier SAS. All rights reserved.

The kelch motif was discovered as a sixfold tandem element in the sequence of the Drosophila kelch ORF1 protein. The repeated kelch motifs predict a conserved tertiary structure, a β-propeller. This module appears in many different polypeptide contexts and contains multiple potential protein–protein contact sites. Members of this growing superfamily are present throughout the cell and extracellularly and have diverse activities. In this review, we discuss current information concerning the structural organization of kelch repeat proteins, their biological roles and the molecular basis of their action.

For some twenty years the marine coatings industry has been intrigued by polymer surfaces with low adhesion to other materials, especially to the biological glues used by marine organisms. Polymers with fouling release surfaces have been made from sundry materials, and their resistance to marine fouling in both static and dynamic tests has been evaluated in the world's oceans. Although the polymer surface property most frequently correlated with bioadhesion is its critical surface tension (), resistance to fouling is also influenced by other bulk and surface properties of the polymer. This paper reviews the types of bonding associated with polymeric materials used in fouling resistant coatings, describes the removal process in terms of fracture mechanics, and discusses the importance of surface energy, elastic modulus and coating thickness in the release of biofoulants.

Background: Common measures of adherence to prescribed medications derived from administrative databases reflect both patients’ and physicians’ behavior, even if the measures are often interpreted as reflecting only the patient&#39;s adherence. Adherence to inhaled corticosteroids (ICSs) has been shown to be low among patients with asthma. Objective: To develop a new measure of patients’ adherence adjusted for prescription patterns and to evaluate the extent to which the low use of ICSs in asthma is due to patients’ nonadherent or suboptimal prescribing practices. Methods: The new measure of adherence, called the proportion of prescribed days covered (PPDC), is defined as the ratio of the total days’ supply dispensed to the total days’ supply prescribed during the study period. The PPDC is a modification of an existing adherence measure, the proportion of days covered (PDC). The PPDC and PDC for ICSs, therapy that should be prescribed for chronic daily use to patients with persisten...

Background: In recent years consumers, due to the growing interest for functional foods, have put particularly attention on products enriched with probiotic lactic acid bacteria for their ability to give human benefit by their assumption. Microorganisms to be considered as probiotic should be able to survive to gastrointestinal juices and colonize the intestinal tract to provide benefits to human health.

The aim of the study consisted of the in vitro investigation of novel LAB strains, isolated during cheesemaking and ripening of Caciocavallo cheese, and on their probiotic potential for food application.

Methods: In order to select potential probiotic bacteria, LAB isolates were preliminarily screened for their survival to simulated gastro-intestinal transitand assayed for other activities of probiotic and functional interest. Thanks to promising attitude as potential probiotics, four strains were tested to evaluate their adhesion ability on Caco-2 cell lines used as intestinal cell model.

Microbiological data were analysed by one-way analysis of variance (ANOVA). Comparisons of means were carried out using post-hoc Tukey’s test. For vitro adhesion experiments, statistical significance was evaluated by Kruskal-Wallis test for equal medians.

Results: Twenty-five LAB, presumptively identified as Lactobacillus spp., were isolated from cheese during 60 days of ripening and screened for their survival to simulated gastrointestinal transit. Sixteen isolates that showed a survival rate ≥85% were identifiedas 10 different profiles of Lb. paracasei subsp. paracasei. The 10 strains tolerated high concentration of bile salts by Minimal Inhibitory Concentration and growth rate assays and showed susceptibility or moderate susceptibility against antibiotics of human and veterinary importance, except for the resistanceto the class of aminoglycoside antibiotics. Eight out 10 strains showed in vitro cholesterol-lowering ability, whereas all strains showed antioxidant activity of their cell-free supernatants. Moreover, the four strains with highest survival to simulated gastrointestinal transit showed the ability to adhere to Caco-2 cells.

Conclusion: The results suggest that some strains may be effective probiotics to be use as tool to design probiotic dairy products after confirmation probiotic activities in further in vivo studies. Findings of the present study suggest that four strains showed good or strong adherent ability on Caco-2 cell monolayer, that is one of prerequisite that probiotic bacteria must have to perform their functional properties.

Keywords: adhesion, antioxidant activity, bile salts, cholesterol assimilation, dairy products, gastrointestinal resistance, probiotic lactobacilli.

Hyperphosphorylated forms of the microtubule-associated protein (MAP) tau accumulate in Alzheimer's disease and related tauopathies and are thought to have an important role in neurodegeneration. However, the mechanisms through which phosphorylated tau induces neurodegeneration have remained elusive. Here, we show that tau-induced neurodegeneration is associated with accumulation of filamentous actin (F-actin) and the formation of actin-rich rods in Drosophila and mouse models of tauopathy. Importantly, modulating F-actin levels genetically leads to dramatic modification of tau-induced neurodegeneration. The ability of tau to interact with F-actin in vivo and in vitro provides a molecular mechanism for the observed phenotypes. Finally, we show that the Alzheimer's disease-linked human β-amyloid protein (Aβ) synergistically enhances the ability of wild-type tau to promote alterations in the actin cytoskeleton and neurodegeneration. These findings raise the possibility that a direct interaction between tau and actin may be a critical mediator of tau-induced neurotoxicity in Alzheimer's disease and related disorders.

Glass polyalkenoate cements (GPCs) have been used in dentistry for over 40 years. These novel bioactive materials are the result of a reaction between a finely ground glass (base) and a polymer (acid), usually poly(acrylic acid) (PAA), in the presence of water. This article reviews the types of PAA used as reagents (including how they vary by molar mass, molecular weight, concentration, polydispersity and content) and the way that they control the properties of the conventional GPCs (CGPCs) formulated from them. The article also considers the effect of PAA on the clinical performance of CGPCs, including biocompatibility, rheological and mechanical properties, adhesion, ion release, acid erosion and clinical durability. The review has critically evaluated the literature and clarified the role that the polyacid component of CGPCs plays in setting and maturation. This review will lead to an improved understanding of the chemistry and properties of the PAA phase which will lead to further innovation in the glass-based cements field.

The surfaces of inorganic substrates containing hydroxyl groups can be adapted to a variety of physical and chemical requirements by reaction with cyclic azasilanes. The moderately-strained ring structure of cyclic azasilanes containing adjacent Si and N atoms, along with the high oxophilicity of silicon, enables the high reactivity towards available hydroxyl groups on all siliceous surfaces investigated, including amorphous silica and borosilicate glass. The reaction occurs quantitatively at room temperature, requires no catalyst and has no byproducts. This investigation looks specifically at the reaction kinetics by means of DRIFT spectroscopy and quantifies extent of reaction by TGA. The less sterically-hindered the Si-N bond, the faster the reaction occurs. In all cases, the reaction is essentially complete in less than one minute. This study provides the first confirmation that the rate and extent of reaction without catalysis or byproducts of cyclic azasilanes conforms to the Sharpless requirements for "click chemistry" and can be deemed "click chemistry for surfaces."

Nickel thin films of various thicknesses deposited on lithium fluoride single crystals have been strained to study the effect of steps on the buckling phenomenon. In these experiments, the nanometer-scale steps result from the emergence process of dislocations coming from the substrate and piling-up at the film/substrate interface. The coated specimens were investigated by in situ atomic force microscopy. It is shown that the buckling phenomenon preferentially occurs just above the step structures in compression tests, while no buckling takes place in tension. From elastic energy consideration, it is concluded that the main effect of substrate plasticity is to strongly modify the critical stress for buckling, with no significant result on the adhesion properties.

Collagen remodelling by fibroblasts has a crucial role in organizing tissue structures that are essential to motility during wound repair, development and regulation of cell growth. However, the mechanism of collagen fibre movement in threedimensional (3D) matrices is not understood. Here, we show that fibroblast lamellipodia extend along held collagen fibres, bind, and retract them in a 'hand-over-hand' cycle, involving α2β1 integrin. Wild-type fibroblasts move collagen fibres three to four times farther per cycle than fibroblasts lacking myosin II-B (myosin II-B −/−). Similarly, myosin II-B −/− fibroblasts contract 3D collagen gels threefold less than controls. On twodimensional (2D) substrates, however, rates of collagen bead and cell movement are not affected by loss of myosin II-B. Green fluorescent protein (GFP)-tagged myosin II-B, but not II-A, restores normal function in knockout cells and localizes to cell processes, whereas myosin II-A is more centrally located. Additionally, GFP-myosin II-B moves out to the periphery and back during handover hand fibre movement, whereas on 2D collagen, myosin II-B is more centrally distributed. Thus, we suggest that cyclic myosin II-B assembly and contraction in lamellipodia power 3D fibre movements. Remodelling of extracellular matrix proteins is critical to the organization of tissues and organs; therefore, it is important to understand the cellular and molecular steps in single collagen fibre movement. Surprisingly, cell motility on glass and other 2D substrates is not necessarily relevant to the movement of fibres in 3D matrices. There is limited overlap between the proteins localized to 3D matrix contacts and those at 2D adhesions 1,2. Furthermore, the morphology of fibroblasts in a 3D collagen matrix bears little resemblance to their morphology on a 2D collagen-coated surface 3,4. Thus, there is a fundamentally different mode of motility on 3D fibres compared with 2D surfaces 5. Carefully orchestrated movements of actin and myosin underlie most cellular motile processes 6-8. This motile machinery forms the cortical cytoskeleton. Upon binding extracellular matrix proteins, integrin receptors initiate a complex signalling cascade culminating in the

Background: Longer travel time to the dialysis unit creates a substantial burden for many patients. This study evaluated the effect of self-reported 1-way travel time to hemodialysis on mortality, health-related quality of life (HR-QOL), adherence, withdrawal from dialysis therapy, hospitalization, and transplantation.

Background The possibility of using microbes to maintain health, and to prevent or treat disease is a topic as old as microbiology. The research of novel probiotic strains is important in order to satisfy the increasing request of the market and to obtain functional products in which the probiotic cultures are more active and with better probiotic characteristics than those already present on the market. Aim of the study In this study, the probiotic potential of Lactobacillus strains isolated from Italian elderly human faeces was investigated. Methods The Lactobacillus strains were identified and examined for resistance to gastric acidity and bile toxicity, adhesion to HT-29 cells, antimicrobial activities, antibiotic susceptibility and plasmid profile. Survival of the strains through human intestine was examined in a 3 months human feeding trial.

This review article describes the fundamental principles of atomic force spectroscopy (AFS) and how this technique became a useful tool to investigate adhesion forces. AFS is a technique derived from atomic force microscopy (AFM) and can determine, at every location of the sample surface, the dependence of the interaction on the probe-sample distance. AFS provides valuable information, at the nano-scale, such as, for example: (i) how the magnitude of the adhesion force depends on long-and short-range interactions and (ii) the tip-sample contact area. An overview about the theory and experiments with local force spectroscopy, force imaging spectroscopy, chemical force microscopy and colloidal probe technique is presented. The many applications of the AFS technique for probing surface interactions open up new possibilities to evaluate adhesion, an important characteristic of materials.

In this study, we aimed to determine the prevalence of Toxoplasma gondii antibodies and identify risk factors associated with this infection in sheep from the southern region of Bahia state. Between February and December 2010, 795 sheep from 31 farms located in nine municipalities were tested. We found seroprevalence of 30.2% (240/795), with titers of 64 (38.3%), 256 (34.2%), 1,024 (18.3%), and 4,096 (9.2%) by Indirect Fluorescent Antibody Test (IFAT). Seropositive sheep were detected in all farms sampled. Univariate statistical analysis detected association between T. gondii seropositivity and the variables age, use of fresh food mainly, water source, stocking rate, production system, presence and number of cats on the farm, and transit of cats (p < 0.05). In the logistic regression model, transit of cats (p = 0.001), production system (p = 0.007), and age (p = 0.027) were identified as risk factors associated with T. gondii infection.

This study aims to investigate the adhesion phenomena between glass and composite materials, which-if they work in synergy-can increase the performance of glass structures, as regard both structural elements and the manufacture of joints. The experimental programme consisted of shear traction tests on all samples: glass-glass singlelap shear adhesion, glass-GFRP double-lap shear adhesion and glass-SRP shear adhesion. Different types of adhesive and various interface geometries were also tested to evaluate the ultimate force and identify fracture patterns with different bonding lengths. It was possible to identify the effective bonding length for each type of resin used to prepare test samples, by taking fracture load and average peel stress into account. Bonding length variations were also recorded. This enabled the values of bonding length to be verified analytically. Based on experimental results, a formula for the evaluation of delamination resistance and the optimal bonding length is proposed.

We report eight novel members of the superfamily of human G protein-coupled receptors (GPCRs) found by searches in the human genome databases, termed GPR97, GPR110, GPR111, GPR112, GPR113, GPR114, GPR115 and GPR116. Phylogenetic analysis shows that these are additional members of a family of GPCRs with long N-termini, previously termed EGF-7TM, LNB-7TM, B2 or LN-7TM. Five of the receptors form their own phylogenetic cluster, while three others form a cluster with the previously reported HE6 and GPR56 (TM7XN1). All the receptors have a GPS domain in their N-terminus and long Ser/Thr-rich regions forming mucin-like stalks. GPR113 has a hormone binding domain and one EGF domain. GPR112 has over 20 Ser/Thr repeats and a pentraxin domain. GPR116 has two immunoglobulin-like repeats and a SEA box. We found several human EST sequences for most of the receptors showing di¡erential expression patterns, which may indicate that some of these receptors participate in reproductive functions while others are more likely to have a role in the immune system.

Eggs of 23 Characiformes and eight Siluriformes, belonging to nine families with diverse reproductive behaviour, were ultrastructurally analysed. The migratory species exhibited non-adhesive eggs, whereas, most of the sedentary species presented some degree of egg adhesiveness. Among the Characiformes, non-adhesive eggs showed zona radiata with pore-canals or a fibrillar net at the surface; weakly adhesive eggs presented only zona radiata with pore-canals while adhesive eggs exhibited zona radiata with apparatus like globules, filaments, villi or honeycomb-like pores depending on the systematic group. The ‘jelly’ coat is strongly related to the Siluriformes eggs apparently without relationship with adhesiveness. A micropylar disc was present in adhesive eggs of a few species of both Characiformes and Siluriformes. Some patterns were characteristic of the animal pole, others of the vegetal pole, and others were common to both poles. The radial ridges converging to the micropyle in Astyanax bimaculatus lacustris appear to be related to fertilization. In general, egg surface structures in the Characiformes varied according to the genus, whereas all Siluriformes showed a similar egg surface pattern, regardless of the group analysed. Multivariate analysis allowed the identification of eight clusters among the Characiformes and three among the Siluriformes showing relationships between reproductive style and egg characteristics. It is suggested that egg surface and adhesiveness may be related to reproductive patterns and to phylogenesis.

Objectives. The purpose of this study was to investigate the effect of different surface treatments on the bond strength () of repaired, aged resin composites (ARC). Methods. Forty blocks of Filtek Z250 TM (Z2) and Filtek Supreme TM (SU) were made, stored in deionized water for 9 days, and randomly assigned to different surface treatment groups: hydrofluoric acid etching (HA), abrasion using a coarse diamond bur (AB), sandblasting with alumina particles (AO), and silica coating (SC). The average roughness (Ra) of the treated surfaces was measured with a profilometer. An adhesive system (SB-Adper Single Bond Plus TM), a silane (SI) or a combination of both (SI + SB) were applied after each surface treatment. The blocks were restored with the same composite (RC) and cut to produce bars that were turned into dumbbell-shaped specimens (0.5 mm 2) using a precision grinding machine. The specimens (n = 30) were tested in tension to fracture and the microtensile bond strength () values were calculated (MPa). Data were analyzed using three-way ANOVA/Tukey test (˛= 0.05) and Weibull statistics. Results. AO and SC produced similar Ra values, which were greater than the value produced by HA. The values were statistically influenced by the type of RC (p < 0.0001), by the surface treatment (p < 0.0001) and by the surface coating (p < 0.0001). Treating the surface of Z2 with SC + SB produced the greatest m value. Significance. AO and SC produced the greatest values, irrespective of the primer (SI, SB or SI + SB) used. Yet, the RC microstructure influenced the mean values, which were greater for Z2 than for SU. The HA should not be used for repairing ARC.

rescuing collapsed replication forks. In contrast, uncontrolled HR can lead to chromosome translocations, loss of heterozygosity, and deletion of repetitive sequences. Controlled HR is particularly important for the preservation of repetitive sequences of the ribosomal gene (rDNA) cluster. Here we show that recombinational repair of a DSB in rDNA in Saccharomyces cerevisiae involves the transient relocalization of the lesion to associate with the recombination machinery at an extranucleolar site. The nucleolar exclusion of Rad52 recombination foci entails Mre11 and Smc5-Smc6 complexes and depends on Rad52 SUMO (small ubiquitin-related modifier) modification. Remarkably, mutations that abrogate these activities result in the formation of Rad52 foci within the nucleolus and cause rDNA hyperrecombination and the excision of extrachromosomal rDNA circles. Our study also suggests a key role of sumoylation for nucleolar dynamics, perhaps in the compartmentalization of nuclear activities.

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 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.

Growth of ice on surfaces poses a challenge for both organisms and for devices that come into contact with liquids below the freezing point. Resistance of some organisms to ice formation and growth, either in subtidal environments (e.g. Antarctic anchor ice), or in environments with moisture and cold air (e.g. plants, intertidal) begs examination of how this is accomplished. Several factors may be important in promoting or mitigating ice formation. As a start, here we examine the effect of surface texture alone. We tested four candidate surfaces, inspired by hard-shelled marine invertebrates and constructed using a three-dimensional printing process. We screened biological and artificial samples for ice formation and accretion in submerged conditions using previous methods, and developed a new test to examine ice formation from surface droplets as might be encountered in environments with moist, cold air. It appears surface texture plays only a small role in delaying the onset of ice formation: a stripe feature (corresponding to patterning found on valves of blue mussels, Mytilus edulis, or on the spines of the Antarctic sea urchin Sterechinus neumayeri) slowed ice formation an average of 25% compared to a grid feature (corresponding to patterning found on sub-polar butterclams, Saxidomas nuttalli). The geometric dimensions of the features have only a small (∼6%) effect on ice formation. Surface texture affects ice formation, but does not explain by itself the large variation in ice formation and species-specific ice resistance observed in other work. This suggests future examination of other factors, such as material elastic properties and surface coatings, and their interaction with surface pattern.

In this work the effects of both the substrate surface condition and the adhesive properties on single-lap aluminium joint resistance were analysed. The aluminium sheets were mechanically treated with two abrasive surfaces evaluating the induced roughness; four different resins were used in adhesion tests. Moreover, wettability tests were performed in order to evaluate the effect of the abovementioned parameters on the substrate/adhesive interaction. A design of experiments was defined in order to quantify the effect of the considered factors and their correlation.

Copper migration continues to be an important consideration in new and emerging interconnect technologies. As line dimensions shrink and new low k materials are introduced into the integrated circuit (IC) structure, the danger of electrical failure due to copper migration increases. The search for better barriers and new copper alloys that resist migration is being sought. Important considerations for copper migration are the adhesion characteristics, which add to the electrical failure phenomenon and also help determine the survivability of the metallic layers in the IC build up process. To understand the survivability issues, we have employed a combination of experimental and modeling studies to determine how the combination of metallic layers may interact. Both the experimental tests and the modeling have been found to be consistent and simple molecular models can be used to predict gross failure trends. These studies have directed us toward newer barrier and copper alloys layers that should be useful in the next generation.

For high-temperature usage (200 C and above) such as in certain supersonic aircraft structures, the adhesives used are either bismaleimides or polyimides, generally supplied as films, with or without a carrier. Other adhesives, such as modified epoxies, can also be used up to 200 C.

Chemical etching is an established and popular method of increasing the adhesion to such materials as polyethylene. Ultra-high-molecular-weight polyethylene (UHMWPE) fibers are exceptional candidates for composite materials except for their poor adhesion• In this research, the bulk, surface and adhesive properties of as-received and chromic acid etched UHMWPE fibers have been examined, The fiber tensile properties, surface chemistry and wettability have been characterized. The adhesion of epoxy has been characterized by the interfacial shear strength of a droplet microbond• The more than six-fold increase in interracial shear strength observed in this work is related to the etching process. The removal of an oxygen-rich weak boundary layer, surface roughening and oxidation of the UHMWPE contribute to the enhanced adhesion.