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Sample records for modified mortar adhesion

  1. Quantitative microstructure analysis of polymer-modified mortars.

    PubMed

    Jenni, A; Herwegh, M; Zurbriggen, R; Aberle, T; Holzer, L

    2003-11-01

    Digital light, fluorescence and electron microscopy in combination with wavelength-dispersive spectroscopy were used to visualize individual polymers, air voids, cement phases and filler minerals in a polymer-modified cementitious tile adhesive. In order to investigate the evolution and processes involved in formation of the mortar microstructure, quantifications of the phase distribution in the mortar were performed including phase-specific imaging and digital image analysis. The required sample preparation techniques and imaging related topics are discussed. As a form of case study, the different techniques were applied to obtain a quantitative characterization of a specific mortar mixture. The results indicate that the mortar fractionates during different stages ranging from the early fresh mortar until the final hardened mortar stage. This induces process-dependent enrichments of the phases at specific locations in the mortar. The approach presented provides important information for a comprehensive understanding of the functionality of polymer-modified mortars.

  2. Research on Waste FRP Fiber Reinforced Adhesive Mortar

    NASA Astrophysics Data System (ADS)

    Feng, Y. C.; Zhao, F. Q.

    2017-01-01

    The use of FRP in industry results in large amount of waste FRP. If not treated properly, it will pollute the environment. In our study, waste FRP powder was used in mortar to substitute part of sand in mortar. The use of short waste FRP fibre can further increase the mechanical strength. The Waste FRP fibre reinforced adhesive mortar was prepared with the material proportioning: cement-sand ratio 1:2, polymer 8% (cement based ), waste FRP fibre 3% (based on the total solids ). The performance of the mortar conforms to JCT 547-2005 with excellent adhesive characteristics.

  3. Characterization of Incorporation the Glass Waste in Adhesive Mortar

    NASA Astrophysics Data System (ADS)

    Santos, D. P.; Azevedo, A. R. G.; Hespanhol, R. L.; Alexandre, J.

    Ehe search for reuse generated waste in urban centers, intending to preserve natural resources, has remained fairly constant, both in context of preventing exploitation of resources as the emplacement of waste on the environment. Glass waste glass created a serious environmental problem, mainly because of inconsistency of its flows. Ehe use of this product as a mineral additive, finely ground, cement replacement and aggregate is a promising direction for recycling. This work aims to study the influence of glass waste from cutting process in adhesive mortar, replacing part of cement. Ehe glass powder is used replacing Portland cement at 10, 15 and 20% by mass. Ehe produced mortars will be evaluated its performance in fresh and hardened states through tests performed in laboratory. Ehe selected feature is indicated by producers of additive and researchers to present good results when used as adhesive mortar.

  4. Characteristics of Ceramic Fiber Modified Asphalt Mortar.

    PubMed

    Wan, Jiuming; Wu, Shaopeng; Xiao, Yue; Liu, Quantao; Schlangen, Erik

    2016-09-21

    Ceramic fiber, with a major composition of Al₂O₃ and SiO₂, has advantages of stability at relatively high temperature, big specific surface area and resistance to external mechanical vibration. It has the potential contribution of improving the rutting resistance and temperature sensitivity of modified asphalt binder by proper modification design. In this research, ceramic fiber was introduced into both pen 60/80 and pen 80/100 asphalt binder by different weight ratios. An asphalt penetration test, softening point test, ductility test and dynamic viscoelastic behavior were conducted to characterize and predict the ceramic fiber modified asphalt mortar (CFAM). Research results indicated that the ceramic fiber has a great effect on reinforcement of asphalt, which makes the asphalt stiffer so that the asphalt can only undertake less strain under the same stress. The heat insulation effect of the ceramic fiber will improve the temperature stability. Complex modulus and phase angle results indicate that the ceramic fiber can significantly enhance the high temperature resistance of soft binder.

  5. Characteristics of Ceramic Fiber Modified Asphalt Mortar

    PubMed Central

    Wan, Jiuming; Wu, Shaopeng; Xiao, Yue; Liu, Quantao; Schlangen, Erik

    2016-01-01

    Ceramic fiber, with a major composition of Al2O3 and SiO2, has advantages of stability at relatively high temperature, big specific surface area and resistance to external mechanical vibration. It has the potential contribution of improving the rutting resistance and temperature sensitivity of modified asphalt binder by proper modification design. In this research, ceramic fiber was introduced into both pen 60/80 and pen 80/100 asphalt binder by different weight ratios. An asphalt penetration test, softening point test, ductility test and dynamic viscoelastic behavior were conducted to characterize and predict the ceramic fiber modified asphalt mortar (CFAM). Research results indicated that the ceramic fiber has a great effect on reinforcement of asphalt, which makes the asphalt stiffer so that the asphalt can only undertake less strain under the same stress. The heat insulation effect of the ceramic fiber will improve the temperature stability. Complex modulus and phase angle results indicate that the ceramic fiber can significantly enhance the high temperature resistance of soft binder. PMID:28773908

  6. Thermal and electrical behavior of nano-modified cement mortar

    NASA Astrophysics Data System (ADS)

    Exarchos, D. A.; Dalla, P. T.; Tragazikis, I. K.; Alafogianni, P.; Barkoula, N.-M.; Paipetis, A. S.; Dassios, K. G.; Matikas, T. E.

    2014-04-01

    This research aims in characterizing modified cement mortar with carbon nanotubes (CNTs) that act as nanoreinforcements leading to the development of innovative materials possessing multi-functionality and smartness. Such multifunctional properties include enhanced mechanical behavior, electrical and thermal conductivity, and piezo-electric characteristics. The effective thermal properties of the modified nano-composites were evaluated using IR Thermography. The electrical resistivity was measured with a contact test method using a custom made apparatus and applying a known D.C. voltage. To eliminate any polarization effects the specimens were dried in an oven before testing. In this work, the thermal and electrical properties of the nano-modified materials were studied by nondestructively monitoring their structural integrity in real time using the intrinsic multi-functional properties of the material as damage sensors.

  7. Solid state NMR and LVSEM studies on the hardening of latex modified tile mortar systems

    SciTech Connect

    Rottstegge, J.; Arnold, M.; Herschke, L.; Glasser, G.; Wilhelm, M.; Spiess, H.W. . E-mail: spiess@mpip-mainz.mpg.de; Hergeth, W.D.

    2005-12-15

    Construction mortars contain a broad variety of both inorganic and organic additives beside the cement powder. Here we present a study of tile mortar systems based on portland cement, quartz, methyl cellulose and different latex additives. As known, the methyl cellulose stabilizes the freshly prepared cement paste, the latex additive enhances final hydrophobicity, flexibility and adhesion. Measurements were performed by solid state nuclear magnetic resonance (NMR) and low voltage scanning electron microscopy (LVSEM) to probe the influence of the latex additives on the hydration, hardening and the final tile mortar properties. While solid state NMR enables monitoring of the bulk composition, scanning electron microscopy affords visualization of particles and textures with respect to their shape and the distribution of the different phases. Within the alkaline cement paste, the poly(vinyl acetate) (VAc)-based latex dispersions stabilized by poly(vinyl alcohol) (PVA) were found to be relatively stable against hydrolysis. The influence of the combined organic additives methyl cellulose, poly(vinyl alcohol) and latexes stabilized by poly(vinyl alcohol) on the final silicate structure of the cement hydration products is small. But even small amounts of additives result in an increased ratio of ettringite to monosulfate within the final hydrated tile mortar as monitored by {sup 27}Al NMR. The latex was found to be adsorbed to the inorganic surfaces, acting as glue to the inorganic components. For similar latex water interfaces built up by poly(vinyl alcohol), a variation in the latex polymer composition results in modified organic textures. In addition to the networks of the inorganic cement and of the latex, there is a weak network build up by thin polymer fibers, most probably originating from poly(vinyl alcohol). Besides the weak network, polymer fibers form well-ordered textures covering inorganic crystals such as portlandite.

  8. Evaluation of Toluene Adsorption Performance of Mortar Adhesives Using Porous Carbon Material as Adsorbent.

    PubMed

    Wi, Seunghwan; Chang, Seong Jin; Jeong, Su-Gwang; Lee, Jongki; Kim, Taeyeon; Park, Kyung-Won; Lee, Dong Ryeol; Kim, Sumin

    2017-07-26

    Porous carbon materials are advantageous in adsorbing pollutants due to their wide range of specific surface areas, pore diameter, and pore volume. Among the porous carbon materials in the current study, expanded graphite, xGnP, xGnP C-300, xGnP C-500, and xGnP C-750 were prepared as adsorbent materials. Brunauer-Emmett-Teller (BET) analysis was conducted to select the adsorbent material through the analysis of the specific surface area, pore size, and pore volume of the prepared porous carbon materials. Morphological analysis using SEM was also performed. The xGnP C-500 as adsorbent material was applied to a mortar adhesive that is widely used in the installation of interior building materials. The toluene adsorption performances of the specimens were evaluated using 20 L small chamber. Furthermore, the performance of the mortar adhesive, as indicated by the shear bond strength, length change rate, and water retention rate, was analyzed according to the required test method specified in the Korean standards. It was confirmed that for the mortar adhesives prepared using the xGnP C-500 as adsorbent material, the toluene adsorption performance was excellent and satisfied the required physical properties.

  9. Evaluation of Toluene Adsorption Performance of Mortar Adhesives Using Porous Carbon Material as Adsorbent

    PubMed Central

    Chang, Seong Jin; Jeong, Su-Gwang; Lee, Jongki; Kim, Taeyeon; Park, Kyung-Won; Lee, Dong Ryeol; Kim, Sumin

    2017-01-01

    Porous carbon materials are advantageous in adsorbing pollutants due to their wide range of specific surface areas, pore diameter, and pore volume. Among the porous carbon materials in the current study, expanded graphite, xGnP, xGnP C-300, xGnP C-500, and xGnP C-750 were prepared as adsorbent materials. Brunauer–Emmett–Teller (BET) analysis was conducted to select the adsorbent material through the analysis of the specific surface area, pore size, and pore volume of the prepared porous carbon materials. Morphological analysis using SEM was also performed. The xGnP C-500 as adsorbent material was applied to a mortar adhesive that is widely used in the installation of interior building materials. The toluene adsorption performances of the specimens were evaluated using 20 L small chamber. Furthermore, the performance of the mortar adhesive, as indicated by the shear bond strength, length change rate, and water retention rate, was analyzed according to the required test method specified in the Korean standards. It was confirmed that for the mortar adhesives prepared using the xGnP C-500 as adsorbent material, the toluene adsorption performance was excellent and satisfied the required physical properties. PMID:28773214

  10. Adhesives from modified soy protein

    DOEpatents

    Sun, Susan; Wang, Donghai; Zhong, Zhikai; Yang, Guang

    2008-08-26

    The, present invention provides useful adhesive compositions having similar adhesive properties to conventional UF and PPF resins. The compositions generally include a protein portion and modifying ingredient portion selected from the group consisting of carboxyl-containing compounds, aldehyde-containing compounds, epoxy group-containing compounds, and mixtures thereof. The composition is preferably prepared at a pH level at or near the isoelectric point of the protein. In other preferred forms, the adhesive composition includes a protein portion and a carboxyl-containing group portion.

  11. Effect of the pre-treatment and the aggregate content on the adhesion strength of repair mortars on Miocene porous limestone

    NASA Astrophysics Data System (ADS)

    Szemerey-Kiss, Balázs; Török, Ákos

    2016-04-01

    The adhesion between porous limestone and newly prepared repair mortars are crucial in the preservation of historic stone structures. Besides mechanical compatibility other matches such as chemical composition and porosity are also essential, but the current research focuses on the adhesion strength of repair mortars that are used in the restoration of Hungarian porous limestone. 8 mortars (4 commercial and 4 specially prepared) were selected for the tests. Mortars with different amount of aggregate were prepared and caste to stone surface. The stone substrate was highly porous Miocene limestone. The strength was tested by standardized pull-out tests which method is commonly used for concrete testing. The limestone surfaces were either used in their natural conditions or were pre-treated (pre-wetting). The strength of the stone/mortar bond was tested. The failure mechanism was documented and various failure modes were identified. Strength test results suggest that especially pre-treatment influences strongly the pull-out strength at mortar/stone interface. Increasing aggregate content also reduces pull out strength of tested repair mortars, but at various rates depending on the mortar type. The financial support of OTKA post-doctoral grant to BSZK (reference number is: PD 112-955) and National Research, Development and Innovation (NKFI) Fund to ÁT (ref. no. K 116532) are appreciated.

  12. Evaluation of the contact angle and frost resistance of hydrophobised heat-insulating mortars with polystyrene

    NASA Astrophysics Data System (ADS)

    Barnat-Hunek, Danuta; Łagód, Grzegorz; Klimek, Beata

    2017-07-01

    The aim of the research presented in the paper was to evaluate the feasibility of using hydrophobic preparation based on organosilicon compounds for surface protection on the heat-insulating mortars modified with polystyrene. The work discusses issues related to wettability, absorptivity and frost resistance of the surface layer of mortars. The experimental part pertains to the physical and mechanical properties of polystyrene-modified mortars and the influence of hydrophobic preparation on the contact angle and frost resistance. The frost resistance of mortars was examined following 25 cycles of freezing and thawing. The contact angle of light mortars (θw) was determined before and after the tests of frost resistance, in the function of time using a single measurement liquid. This provided a basis for calculating the surface free energy with Neumann method, characterizing the wettability and adhesion of mortars under normal conditions and with damages resulting from frost weathering. The structure of mortars and the adhesion of lightweight aggregate to cement paste were presented by means of scanning electron microscopy. The studies enabled to determine the hydrophobisation efficiency of heat-insulating mortars with polystyrene. The obtained results confirmed the possibility of producing heat-insulating mortars modified with polystyrene along with proper surface protection against moisture and frost.

  13. The effect of different surfactants/plastisizers on the electrical behavior of CNT nano-modified cement mortars

    NASA Astrophysics Data System (ADS)

    Dalla, P. T.; Alafogianni, P.; Tragazikis, I. K.; Exarchos, D. A.; Dassios, K.; Barkoula, N.-M.; Matikas, T. E.

    2015-03-01

    Cement-based materials have in general low electrical conductivity. Electrical conductivity is the measure of the ability of the material to resist the passage of electrical current. The addition of a conductive admixture such as Multi-Walled Carbon Nanotubes (MWCNTs) in a cement-based material increases the conductivity of the structure. This research aims to characterize nano-modified cement mortars with MWCNT reinforcements. Such nano-composites would possess smartness and multi-functionality. Multifunctional properties include electrical, thermal and piezo-electric characteristics. One of these properties, the electrical conductivity, was measured using a custom made apparatus that allows application of known D.C. voltage on the nano-composite. In this study, the influence of different surfactants/plasticizers on CNT nano-modified cement mortar specimens with various concentrations of CNTs (0.2% wt. cement CNTs - 0.8% wt. cement CNTs) on the electrical conductivity is assessed.

  14. Doxycycline-encapsulated nanotube-modified dentin adhesives.

    PubMed

    Feitosa, S A; Palasuk, J; Kamocki, K; Geraldeli, S; Gregory, R L; Platt, J A; Windsor, L J; Bottino, M C

    2014-12-01

    This article presents details of fabrication, biological activity (i.e., anti-matrix metalloproteinase [anti-MMP] inhibition), cytocompatibility, and bonding characteristics to dentin of a unique doxycycline (DOX)-encapsulated halloysite nanotube (HNT)-modified adhesive. We tested the hypothesis that the release of DOX from the DOX-encapsulated nanotube-modified adhesive can effectively inhibit MMP activity. We incorporated nanotubes, encapsulated or not with DOX, into the adhesive resin of a commercially available bonding system (Scotchbond Multi-Purpose [SBMP]). The following groups were tested: unmodified SBMP (control), SBMP with nanotubes (HNT), and DOX-encapsulated nanotube-modified adhesive (HNT+DOX). Changes in degree of conversion (DC) and microtensile bond strength were evaluated. Cytotoxicity was examined on human dental pulp stem cells (hDPSCs). To prove the successful encapsulation of DOX within the adhesives-but, more important, to support the hypothesis that the HNT+DOX adhesive would release DOX at subantimicrobial levels-we tested the antimicrobial activity of synthesized adhesives and the DOX-containing eluates against Streptococcus mutans through agar diffusion assays. Anti-MMP properties were assessed via β-casein cleavage assays. Increasing curing times (10, 20, 40 sec) led to increased DC values. There were no statistically significant differences (p > .05) in DC within each increasing curing time between the modified adhesives compared to SBMP. No statistically significant differences in microtensile bond strength were noted. None of the adhesives eluates were cytotoxic to the human dental pulp stem cells. A significant growth inhibition of S. mutans by direct contact illustrates successful encapsulation of DOX into the experimental adhesive. More important, DOX-containing eluates promoted inhibition of MMP-1 activity when compared to the control. Collectively, our findings provide a solid background for further testing of encapsulated MMP

  15. Urea modified cottonseed protein adhesive for wood composite products

    USDA-ARS?s Scientific Manuscript database

    Cottonseed protein has the potential to be used as renewable and environmentally friendly adhesives in wood products industry. However, the industry application was limited by its low mechanical properties, low water resistance and viscosity. In this work, urea modified cottonseed protein adhesive w...

  16. Investigation of modified cottonseed protein adhesives for wood composites

    USDA-ARS?s Scientific Manuscript database

    Several modified cottonseed protein isolates were studied and compared to corresponding soy protein isolates for their adhesive properties when bonded to wood composites. Modifications included treatments with alkali, guanidine hydrochloride, sodium dodecyl sulfate (SDS), and urea. Wood composites...

  17. Doxycycline-Encapsulated Nanotube-Modified Dentin Adhesives

    PubMed Central

    Feitosa, S.A.; Palasuk, J.; Kamocki, K.; Geraldeli, S.; Gregory, R.L.; Platt, J.A.; Windsor, L.J.; Bottino, M.C.

    2014-01-01

    This article presents details of fabrication, biological activity (i.e., anti–matrix metalloproteinase [anti-MMP] inhibition), cytocompatibility, and bonding characteristics to dentin of a unique doxycycline (DOX)–encapsulated halloysite nanotube (HNT)–modified adhesive. We tested the hypothesis that the release of DOX from the DOX-encapsulated nanotube-modified adhesive can effectively inhibit MMP activity. We incorporated nanotubes, encapsulated or not with DOX, into the adhesive resin of a commercially available bonding system (Scotchbond Multi-Purpose [SBMP]). The following groups were tested: unmodified SBMP (control), SBMP with nanotubes (HNT), and DOX-encapsulated nanotube-modified adhesive (HNT+DOX). Changes in degree of conversion (DC) and microtensile bond strength were evaluated. Cytotoxicity was examined on human dental pulp stem cells (hDPSCs). To prove the successful encapsulation of DOX within the adhesives—but, more important, to support the hypothesis that the HNT+DOX adhesive would release DOX at subantimicrobial levels—we tested the antimicrobial activity of synthesized adhesives and the DOX-containing eluates against Streptococcus mutans through agar diffusion assays. Anti-MMP properties were assessed via β-casein cleavage assays. Increasing curing times (10, 20, 40 sec) led to increased DC values. There were no statistically significant differences (p > .05) in DC within each increasing curing time between the modified adhesives compared to SBMP. No statistically significant differences in microtensile bond strength were noted. None of the adhesives eluates were cytotoxic to the human dental pulp stem cells. A significant growth inhibition of S. mutans by direct contact illustrates successful encapsulation of DOX into the experimental adhesive. More important, DOX-containing eluates promoted inhibition of MMP-1 activity when compared to the control. Collectively, our findings provide a solid background for further testing of

  18. New processable modified polyimide resins for adhesive and matrix applications

    NASA Technical Reports Server (NTRS)

    Landman, D.

    1985-01-01

    A broad product line of bismaleimide modified epoxy adhesives which are cured by conventional addition curing methods is described. These products fill a market need for 232 C (450 F) service adhesives which are cured in a manner similar to conventional 177 C (350 F) epoxy adhesives. The products described include film adhesives, pastes, and a primer. Subsequent development work has resulted in a new bismaleimide modified epoxy resin which uses a unique addition curing mechanism. This has resulted in products with improved thermomechanical properties compared to conventional bismaleimide epoxy resins. A film adhesive, paste, and matrix resin for composites using this new technology are described. In all cases, the products developed are heat cured by using typical epoxy cure cycles i.e., 1 hour at 177 C (350 F) followed by 2 hours postcure at 246 C (475 F).

  19. Adhesive and morphological characteristics of surface chemically modified polytetrafluoroethylene films

    NASA Astrophysics Data System (ADS)

    Hopp, B.; Kresz, N.; Kokavecz, J.; Smausz, T.; Schieferdecker, H.; Döring, A.; Marti, O.; Bor, Z.

    2004-01-01

    In the present paper, we report an experimental determination of adhesive and topographic characteristics of chemically modified surface of polytetrafluoroethylene (PTFE) films. The surface chemistry was modified by ArF excimer laser irradiation in presence of triethylene-tetramine photoreagent. The applied laser fluence was varied in the range of 0.4-9 mJ/cm 2, and the number of laser pulses incident on the same area was 1500. To detect the changes in the adhesive features of the treated Teflon samples, we measured receding contact angle for distilled water and adhesion strength, respectively. It was found that the receding contact angle decreased from 96° to 30-37° and the adhesion strength of two-component epoxy glue to the treated sample surface increased from 0.03 to 9 MPa in the applied laser fluence range. Additionally, it was demonstrated that the adhesion of human cells to the modified Teflon samples is far better than to the untreated ones. The contact mode and pulsed force mode atomic force microscopic investigations of the treated samples demonstrated that the measured effective contact area of the irradiated films does not differ significantly from that of the original films, but the derived adhesion force is stronger on the modified samples than on the untreated ones. Hence, the increased adhesion of the treated Teflon films is caused by the higher surface energy.

  20. Modified Surface Having Low Adhesion Properties to Mitigate Insect Residue Adhesion

    NASA Technical Reports Server (NTRS)

    Wohl, Christopher J., Jr. (Inventor); Smith, Joseph G., Jr. (Inventor); Siochi, Emilie J. (Inventor); Penner, Ronald K. (Inventor)

    2016-01-01

    A process to modify a surface to provide reduced adhesion surface properties to mitigate insect residue adhesion. The surface may include the surface of an article including an aircraft, an automobile, a marine vessel, all-terrain vehicle, wind turbine, helmet, etc. The process includes topographically and chemically modifying the surface by applying a coating comprising a particulate matter, or by applying a coating and also topographically modifying the surface by various methods, including but not limited to, lithographic patterning, laser ablation and chemical etching, physical vapor phase deposition, chemical vapor phase deposition, crystal growth, electrochemical deposition, spin casting, and film casting.

  1. RGD modified polymers: biomaterials for stimulated cell adhesion and beyond.

    PubMed

    Hersel, Ulrich; Dahmen, Claudia; Kessler, Horst

    2003-11-01

    Since RGD peptides (R: arginine; G: glycine; D: aspartic acid) have been found to promote cell adhesion in 1984 (Cell attachment activity of fibronectin can be duplicated by small synthetic fragments of the molecule, Nature 309 (1984) 30), numerous materials have been RGD functionalized for academic studies or medical applications. This review gives an overview of RGD modified polymers, that have been used for cell adhesion, and provides information about technical aspects of RGD immobilization on polymers. The impacts of RGD peptide surface density, spatial arrangement as well as integrin affinity and selectivity on cell responses like adhesion and migration are discussed.

  2. Adhesion Molecule-Modified Biomaterials for Neural Tissue Engineering

    PubMed Central

    Rao, Shreyas S.; Winter, Jessica O.

    2009-01-01

    Adhesion molecules (AMs) represent one class of biomolecules that promote central nervous system regeneration. These tethered molecules provide cues to regenerating neurons that recapitulate the native brain environment. Improving cell adhesive potential of non-adhesive biomaterials is therefore a common goal in neural tissue engineering. This review discusses common AMs used in neural biomaterials and the mechanism of cell attachment to these AMs. Methods to modify materials with AMs are discussed and compared. Additionally, patterning of AMs for achieving specific neuronal responses is explored. PMID:19668707

  3. Polyimide adhesives - Modified with ATBN and silicone elastomers

    NASA Technical Reports Server (NTRS)

    St. Clair, A. K.; St. Clair, T. L.; Ezzell, S. A.

    1984-01-01

    A series of studies evaluating the effects of added elastomers on the properties of a high-temperature addition polyimide adhesive is reviewed. First, thermoset polyimides containing various butadiene/acrylonitrile and silicone elastomers were synthesized either as physical polybends or by chemically reacting the elastomers directly onto the polymer backbone. The modified adhesive resins were characterized for thermomechanical properties, fracture toughness and adhesive strength. A second series of elastomer-containing polyimides was also prepared in order to study the effects of the elastomer chain length on polymer properties. Aromatic amine-terminated silicone rubbers with repeat units varying from n = 10 to 105 were reacted onto the polyimide backbone, and the resulting polymers were characterized for their adhesive properties.

  4. Osteoblastlike cell adhesion on titanium surfaces modified by plasma nitriding.

    PubMed

    da Silva, Jose Sandro Pereira; Amico, Sandro Campos; Rodrigues, Almir Olegario Neves; Barboza, Carlos Augusto Galvao; Alves, Clodomiro; Croci, Alberto Tesconi

    2011-01-01

    The aim of this study was to evaluate the characteristics of various titanium surfaces modified by cold plasma nitriding in terms of adhesion and proliferation of rat osteoblastlike cells. Samples of grade 2 titanium were subjected to three different surface modification processes: polishing, nitriding by plasma direct current, and nitriding by cathodic cage discharge. To evaluate the effect of the surface treatment on the cellular response, the adhesion and proliferation of osteoblastlike cells (MC3T3) were quantified and the results were analyzed by Kruskal-Wallis and Friedman statistical tests. Cellular morphology was observed by scanning electron microscopy. There was more MC3T3 cell attachment on the rougher surfaces produced by cathodic cage discharge compared with polished samples (P < .05). Plasma nitriding improves titanium surface roughness and wettability, leading to osteoblastlike cell adhesion.

  5. Effect of dentine conditioning on adhesion of resin-modified glass ionomer adhesives.

    PubMed

    Hamama, H H; Burrow, M F; Yiu, C

    2014-06-01

    The aim of this study was to investigate the use of phosphoric acid as a surface treatment compared to traditional conditioning agents to dentine bonded with resin-modified glass ionomer (RMGIC) adhesives. Forty human molars were utilized in microtensile bond strength testing, while another 16 were used for evaluation of the bonded interface with scanning electron microscopy. Three RMGIC adhesives were evaluated: Fuji Bond LC (GC Corp); Riva Bond LC (SDI Ltd); and Ketac N100 (3M-ESPE). Surface treatments were 37% phosphoric acid (5 s) or 25-30% polyacrylic acid (PAA) (10 s), or the manufacturer's method - Fuji Bond LC: Cavity Conditioner (20% PAA + 3% AlCl3 10 s) or Ketac N100 primer: Ketac Nano priming agent (15 s). Teeth were finished with 600-grit SiC paper, surfaces treated and bonded with RMGIC adhesive and stored in distilled water for 24 h then subjected to microtensile bond strength testing. Two-way analysis of variance (ANOVA) revealed adhesion was affected by the 'type of RMGIC adhesive' and 'method of dentine surface treatment' (p < 0.05). The microtensile bond strength of Ketac N100 primer groups was lower than Fuji Bond LC and Riva Bond LC (p < 0.05). For RMGIC adhesives a brief etch with phosphoric acid does not adversely effect short-term bond strengths, but is no better than traditional conditioning with PAA. © 2014 Australian Dental Association.

  6. Modifying Matrix Materials to Increase Wetting and Adhesion

    NASA Technical Reports Server (NTRS)

    Zhong, Katie

    2011-01-01

    In an alternative approach to increasing the degrees of wetting and adhesion between the fiber and matrix components of organic-fiber/polymer matrix composite materials, the matrix resins are modified. Heretofore, it has been common practice to modify the fibers rather than the matrices: The fibers are modified by chemical and/or physical surface treatments prior to combining the fibers with matrix resins - an approach that entails considerable expense and usually results in degradation (typically, weakening) of fibers. The alternative approach of modifying the matrix resins does not entail degradation of fibers, and affords opportunities for improving the mechanical properties of the fiber composites. The alternative approach is more cost-effective, not only because it eliminates expensive fiber-surface treatments but also because it does not entail changes in procedures for manufacturing conventional composite-material structures. The alternative approach is best described by citing an example of its application to a composite of ultra-high-molecular- weight polyethylene (UHMWPE) fibers in an epoxy matrix. The epoxy matrix was modified to a chemically reactive, polarized epoxy nano-matrix to increase the degrees of wetting and adhesion between the fibers and the matrix. The modification was effected by incorporating a small proportion (0.3 weight percent) of reactive graphitic nanofibers produced from functionalized nanofibers into the epoxy matrix resin prior to combining the resin with the UHMWPE fibers. The resulting increase in fiber/matrix adhesion manifested itself in several test results, notably including an increase of 25 percent in the maximum fiber pullout force and an increase of 60-65 percent in fiber pullout energy. In addition, it was conjectured that the functionalized nanofibers became involved in the cross linking reaction of the epoxy resin, with resultant enhancement of the mechanical properties and lower viscosity of the matrix.

  7. Endothelial cell migration on surfaces modified with immobilized adhesive peptides.

    PubMed

    Kouvroukoglou, S; Dee, K C; Bizios, R; McIntire, L V; Zygourakis, K

    2000-09-01

    Endothelial cell (EC) migration has been studied on aminophase surfaces with covalently bound RGDS and YIGSRG cell adhesion peptides. The fluorescent marker dansyl chloride was used to quantify the spatial distribution of the peptides on the modified surfaces. Peptides appeared to be distributed in uniformly dispersed large clusters separated by areas of lower peptide concentrations. We employed digital time-lapse video microscopy and image analysis to monitor EC migration on the modified surfaces and to reconstruct the cell trajectories. The persistent random walk model was then applied to analyze the cell displacement data and compute the mean root square speed, the persistence time, and the random motility coefficient of EC. We also calculated the time-averaged speed of cell locomotion. No differences in the speed of cell locomotion on the various substrates were noted. Immobilization of the cell adhesion peptides (RGDS and YIGSRG), however, significantly increased the persistence of cell movement and, thus, the random motility coefficient. These results suggest that immobilization of cell adhesion peptides on the surface of implantable biomaterials may lead to enhanced endothelization rates.

  8. 21 CFR 872.3480 - Polyacrylamide polymer (modified cationic) denture adhesive.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Polyacrylamide polymer (modified cationic) denture... polymer (modified cationic) denture adhesive. (a) Identification. A polyacrylamide polymer (modified cationic) denture adhesive is a device composed of polyacrylamide polymer (modified cationic) intended...

  9. 21 CFR 872.3480 - Polyacrylamide polymer (modified cationic) denture adhesive.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Polyacrylamide polymer (modified cationic) denture... polymer (modified cationic) denture adhesive. (a) Identification. A polyacrylamide polymer (modified cationic) denture adhesive is a device composed of polyacrylamide polymer (modified cationic) intended...

  10. 21 CFR 872.3480 - Polyacrylamide polymer (modified cationic) denture adhesive.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Polyacrylamide polymer (modified cationic) denture... polymer (modified cationic) denture adhesive. (a) Identification. A polyacrylamide polymer (modified cationic) denture adhesive is a device composed of polyacrylamide polymer (modified cationic) intended to...

  11. 21 CFR 872.3480 - Polyacrylamide polymer (modified cationic) denture adhesive.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Polyacrylamide polymer (modified cationic) denture... polymer (modified cationic) denture adhesive. (a) Identification. A polyacrylamide polymer (modified cationic) denture adhesive is a device composed of polyacrylamide polymer (modified cationic) intended to...

  12. 21 CFR 872.3480 - Polyacrylamide polymer (modified cationic) denture adhesive.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Polyacrylamide polymer (modified cationic) denture... polymer (modified cationic) denture adhesive. (a) Identification. A polyacrylamide polymer (modified cationic) denture adhesive is a device composed of polyacrylamide polymer (modified cationic) intended to...

  13. Doxycycline-loaded nanotube-modified adhesives inhibit MMP in a dose-dependent fashion.

    PubMed

    Palasuk, Jadesada; Windsor, L Jack; Platt, Jeffrey A; Lvov, Yuri; Geraldeli, Saulo; Bottino, Marco C

    2017-09-30

    This article evaluated the drug loading, release kinetics, and matrix metalloproteinase (MMP) inhibition of doxycycline (DOX) released from DOX-loaded nanotube-modified adhesives. DOX was chosen as the model drug, since it is the only MMP inhibitor approved by the U.S. Food and Drug Administration. Drug loading into the nanotubes was accomplished using DOX solution at distinct concentrations. Increased concentrations of DOX significantly improved the amount of loaded DOX. The modified adhesives were fabricated by incorporating DOX-loaded nanotubes into the adhesive resin of a commercial product. The degree of conversion (DC), Knoop microhardness, DOX release kinetics, antimicrobial, cytocompatibility, and anti-MMP activity of the modified adhesives were investigated. Incorporation of DOX-loaded nanotubes did not compromise DC, Knoop microhardness, or cell compatibility. Higher concentrations of DOX led to an increase in DOX release in a concentration-dependent manner from the modified adhesives. DOX released from the modified adhesives did not inhibit the growth of caries-related bacteria, but more importantly, it did inhibit MMP-1 activity. The loading of DOX into the nanotube-modified adhesives did not compromise the physicochemical properties of the adhesives and the released levels of DOX were able to inhibit MMP activity without cytotoxicity. Doxycycline released from the nanotube-modified adhesives inhibited MMP activity in a concentration-dependent fashion. Therefore, the proposed nanotube-modified adhesive may hold clinical potential as a strategy to preserve resin/dentin bond stability.

  14. Adhesion of single crystals on modified surfaces in crystallization fouling

    NASA Astrophysics Data System (ADS)

    Mayer, Moriz; Augustin, Wolfgang; Scholl, Stephan

    2012-12-01

    In crystallization fouling it has been observed that during a certain initial phase the fouling is formed by a non-uniform layer consisting of a population of single crystals. These single crystals are frequently formed by inverse soluble salts such as CaCO3. During heterogeneous nucleation and heterogeneous growth an interfacial area between the crystal and the heat transfer surface occurs. The development of this interfacial area is the reason for the adhesion of each single crystal and of all individual crystals, once a uniform layer has been built up. The emerging interfacial area is intrinsic to the heterogeneous nucleation of crystals and can be explained by the thermodynamic principle of the minimum of the Gibbs free energy. In this study CaCO3 crystals were grown heterogeneously on untreated and on modified surfaces inside a flow channel. An untreated stainless steel (AISI 304) surface was used as a reference. Following surface modifications were investigated: enameled and electropolished stainless steel as well as diamond-like-carbon based coatings on stainless steel substrate. The adhesion was measured through a novel measurement technique using a micromanipulator to shear off single crystals from the substrate which was fixed to a spring table inside a SEM.

  15. Examination of adhesive penetration in modified wood using fluorescence microscopy

    Treesearch

    Jermal G. Chandler; Rishawn L. Brandon; Charles R. Frihart

    2005-01-01

    Adhesive bonding takes place when an adhesive undergoes the conversion from liquid to solid. The liquid properties are needed for the adhesive to fully wet the bonding substance, and the solid properties are needed for the strength required for the union of the final product. The mobility of an adhesive depends heavily on its own physical and chemical properties and...

  16. Copolyimide Surface Modifying Agents for Particle Adhesion Mitigation

    NASA Technical Reports Server (NTRS)

    Wohl, Christopher J.; Connell, John W.

    2011-01-01

    Marine biofouling, insect adhesion on aircraft surfaces, microbial contamination of sterile environments, and particle contamination all present unique challenges for which researchers have adopted an array of mitigation strategies. Particulate contamination is of interest to NASA regarding exploration of the Moon, Mars, asteroids, etc.1 Lunar dust compromised seals, clogged filters, abraded visors and space suit surfaces, and was a significant health concern during the Apollo missions.2 Consequently, NASA has instituted a multi-faceted approach to address dust including use of sacrificial surfaces, active mitigation requiring the use of an external energy source, and passive mitigation utilizing materials with an intrinsic resistance to surface contamination. One passive mitigation strategy is modification of a material s surface energy either chemically or topographically. The focus of this paper is the synthesis and evaluation of novel copolyimide materials with surface modifying agents (SMA, oxetanes) enabling controlled variation of surface chemical composition.

  17. Antibacterial Adhesion of Polymethyl Methacrylate Modified by Borneol Acrylate.

    PubMed

    Sun, Xueli; Qian, Zhiyong; Luo, Lingqiong; Yuan, Qipeng; Guo, Ximin; Tao, Lei; Wei, Yen; Wang, Xing

    2016-10-07

    Polymethyl methacrylate (PMMA) is a widely used biomaterial. But there is still a challenge facing its unwanted bacterial adhesion, because the subsequent biofilm formation usually leads to failure of related implants. Herein, we present a borneol-modified PMMA based on a facile and effective stereochemical strategy, generating antibacterial copolymer named as P(MMA-co-BA). It was synthesized by free radical polymerization and studied with different ratio between methyl methacrylate (MMA) and borneol acrylate (BA) monomers. NMR, GPC and EA etc. were used to confirm their chemical features. Their films were challenged with Escherichia coli (Gram-negative) and Bacillus subtilis (Gram-positive), showing a BA content-dependent antibacterial performance. The minimum effective dose should be 10%. Then in vivo subcutaneous implantations in mice demonstrated their biocompatibilities through routine histotomy and HE staining. Therefore, P(MMA-co-BA)s not only exhibited their unique antibacterial character, but also suggested a potential for the safe usage of borneol-modified PMMA frame and devices for further implantation.

  18. Bacterial adhesion to polyvinylamine-modified nanocellulose films.

    PubMed

    Henschen, Jonatan; Larsson, Per A; Illergård, Josefin; Ek, Monica; Wågberg, Lars

    2017-03-01

    Cellulose nanofibril (CNF) materials have been widely studied in recent years and are suggested for a wide range of applications, e.g., medical and hygiene products. One property not very well studied is the interaction between bacteria and these materials and how this can be controlled. The current work studies how bacteria adhere to different CNF materials modified with polyelectrolyte multilayers. The tested materials were TEMPO-oxidized to have different surface charges, periodate-oxidized to vary the water interaction and hot-pressed to alter the surface structure. Then, multilayers were constructed using polyvinylamine (PVAm) and polyacrylic acid. Both the material surface charge and water interaction affect the amount of polymer adsorbed to the surfaces. Increasing the surface charge decreases the adsorption after the first PVAm layer, possibly due to conformational changes. Periodate-oxidized and crosslinked films have low initial polymer adsorptions; the decreased swelling prevents polymer diffusion into the CNF micropore structure. Microscopic analysis after incubating the samples with bacterial suspensions show that only the materials with the lowest surface charge enable bacteria to adhere to the surface because, when adsorbing up to 5 layers PVAm/PAA, the increased anionic surface charge appears to decrease the net surface charge. Both the amounts of PVAm and PAA influence the net surface charge and thus the bacterial adhesion. The structure generated by the hot-pressing of the films also strongly increases the number of bacteria adhering to the surfaces. These results indicate that the bacterial adhesion to CNF materials can be tailored using polyelectrolyte multilayers on different CNF substrates.

  19. Bacterial adhesion to orthopaedic implant materials and a novel oxygen plasma modified PEEK surface.

    PubMed

    Rochford, E T J; Poulsson, A H C; Salavarrieta Varela, J; Lezuo, P; Richards, R G; Moriarty, T F

    2014-01-01

    Despite extensive use of polyetheretherketone (PEEK) in biomedical applications, information about bacterial adhesion to this biomaterial is limited. This study investigated Staphylococcus aureus and Staphylococcus epidermidis adhesion to injection moulded and machined PEEK OPTIMA(®) using a custom-built adhesion chamber with medical grade titanium and Thermanox for comparison. Additionally, bacterial adhesion to a novel oxygen plasma modified PEEK was also investigated in both a pre-operative model in physiological saline, and additionally in a post-operative model in human blood plasma. In the pre-operative model, the rougher machined PEEK had a significantly greater number of adherent bacteria compared to injection moulded PEEK. Bacterial adhesion to titanium and Thermanox was similar. Oxygen plasma surface modification of PEEK did not lead to a significant change in bacterial adhesion in the pre-operative contamination model, despite observed changes in surface characteristics. In the post-operative contamination model, S. aureus adhesion was increased from 5×10(5) CFU cm(-2) to approximately 1.3×10(7) CFU cm(-2) on the modified surfaces due to differential protein adhesion during the conditioning period. However, S. epidermidis adhesion to modified PEEK was less than to unmodified PEEK in the post-operative model. These results illustrate the importance of testing bacterial adhesion of several strains in both a pre-operative and post-operative, clinically relevant bacterial contamination model.

  20. ELEVATED TEMPERATURE RESISTANT MODIFIED EPOXIDE RESIN ADHESIVES FOR METALS

    DTIC Science & Technology

    composed of Epon 1001 resin, Plyophen 5023, and dicyandiamide as the curing agent. Al dust was used as the reinforcing filler. The adhesive was cured at...to the development of the following formula (parts by weight): 33 Epon 1001 + 67 Polyophen 5023 + 100 Al dust + 6 dicyandiamide . Higher Epon 1001...or curing without dicyandiamide reduced adhesive shear strength, especially at room temperature.

  1. Adhesion Improvement of Zirconium Coating on Polyurethane Modified by Plasmas

    NASA Astrophysics Data System (ADS)

    Gao, Yi; Hao, Xiaofei; Liu, Jiwei

    2016-02-01

    In order to improve the adhesion of the middle frequency magnetic sputtered zirconium coating on a polyurethane film, an anode layer source was used to pretreat the polyurethane film with nitrogen and oxygen ions. SEMs and AFM roughness profiles of treated samples and the contrast groups were obtained. Besides, XPS survey spectrums and high resolution spectrums were also investigated. The adhesion test revealed that ion bombardment could improve the adhesion to the polyurethane coating substrate. A better etching result of oxygen ions versus nitrogen predicts a higher bonding strength of zirconium coating on polyurethane and, indeed, the highest bonding strengths are for oxygen ion bombardment upto 13.3 MPa. As demonstrated in X-ray photoelectron spectroscopy, the oxygen ion also helps to introduce more active groups, and, therefore, it achieves a high value of adhesion strength.

  2. Preparation and characterization of phenol-formaldehyde adhesives modified with enzymatic hydrolysis lignin.

    PubMed

    Jin, Yanqiao; Cheng, Xiansu; Zheng, Zuanbin

    2010-03-01

    Phenol-formaldehyde (PF) adhesives modified with enzymatic hydrolysis lignin (EHL) were synthesized by a one-step process. The phenol component of the PF adhesives was partially substituted by EHL extracted from the residues of cornstalks used to produce bio-ethanol. The EHL-PF adhesives were used to prepare plywoods by hot-pressing. The pH value, viscosity, solid content, free phenol content, free formaldehyde content and brominable substance content of EHL-PF resins were investigated. The bonding strengths of the plywoods were determined, and the influences of the replacement percentage of phenol by EHL (a) and the NaOH content (b) on the properties of the adhesives were investigated. The results showed that the performance of the modified adhesives and the plywoods glued with them almost met the Chinese National Standard (GB/T 14732-2006) for first grade plywood when 20 wt% of the phenol was replaced by EHL.

  3. [Effect of surface modified nano-diamond on viscosity of dental adhesives].

    PubMed

    Luo, Juan; Liang, Jie; Hu, Ai-yun; Liu, Xue-heng

    2012-06-01

    Different surface modified ultrafine-diamond (UFD) was added into dental adhesives as filler ,then the influence of dental adhesive properties was observed. The main matrix of dental adhesive was high polymer resin. Different content of non-modified UFD(n-UFD) or modified UFD(m-UFD) were added into dental adhesives, then the viscosity of materials were measured. The data was processed with SPSS17.0 software package. The viscosity of dental adhesives was decreased when the proportion of UFD was less than 0.1wt%, especially when it was 0.1wt%; but was significantly improved when the proportion was more than 0.1wt%. The effect of UFD and surface-modified UFD on the viscosity was significantly different. The results show that silane coupling was chemically-grafted on the surface of UFD, the dispersion and stability of UFD in ethanol was improved; And a quantity of UFD with special content could reduce the viscosity of dental adhesives and improve the flowability obviously. The m-UFD was superior to n-UFD.

  4. An Investigation of the Oxide Adhesion and Growth Characteristics on Platinum Modified Aluminide Coatings.

    DTIC Science & Technology

    1986-09-01

    AD-A75 35 N INVESTIGTION OF THE OXIDE DESION AUD GROWTH 1/1CHARRCTERISTICS ON PLATINUM MODIFIED ALUMINIDE COATINGS (U) NAVAL POSTGRADUATE SCHOOL...ADHESION AND GROWTH CHARACTERISTICS ON PLATINUM M1ODIFIED ALUMINIDE COATINGS ’"PERSONAL AUTHOR(S) Farrell, M.1argaret Shannon 𔃽j TYP/ OF REPORT 3b TIME...SUBJECT TERMS (Continue on reverse if necessary and identfy by block number) GROUP SUB-GROUP Turbine Blade Coatings ; Platinum Aluminides ;Oxide Adhesion

  5. Chitosan scaffold modified with D-(+) raffinose and enriched with thiol-modified gelatin for improved osteoblast adhesion.

    PubMed

    Galli, C; Parisi, L; Elviri, L; Bianchera, A; Smerieri, A; Lagonegro, P; Lumetti, S; Manfredi, E; Bettini, R; Macaluso, G M

    2016-02-02

    The aim of the present study was to investigate whether chitosan-based scaffolds modified with D-(+) raffinose and enriched with thiol-modified gelatin could selectively improve osteoblast adhesion and proliferation. 2, 3 and 4.5% chitosan films were prepared. Chitosan suitability for tissue engineering was confirmed by protein adsorption assay. Scaffolds were incubated with a 2.5 mg ml(-1) BSA solution and the decrease of protein content in the supernatants was measured by spectrophotometry. Chitosan films were then enriched with thiol-modified gelatin and their ability to bind BSA was also measured. Then, 2% chitosan discs with or without thiol-modified gelatin were used as culture substrates for MC3T3-E1 cells. After 72 h cells were stained with trypan blue or with calcein AM and propidium iodide for morphology, viability and proliferation assays. Moreover, cell viability was measured at 48, 72, 96 and 168 h to obtain a growth curve. Chitosan films efficiently bound and retained BSA proportionally to the concentration of chitosan discs. The amount of protein retained was higher on chitosan enriched with thiol-modified gelatin. Moreover, chitosan discs allowed the adhesion and the viability of cells, but inhibited their proliferation. The functionalization of chitosan with thiol-modified gelatin enhanced cell spreading and proliferation. Our data confirm that chitosan is a suitable material for tissue engineering. Moreover, our data show that the enrichment of chitosan with thiol-modified gelatin enhances its biological properties.

  6. Reducing composite restoration polymerization shrinkage stress through resin modified glass-ionomer based adhesives.

    PubMed

    Naoum, S J; Mutzelburg, P R; Shumack, T G; Thode, Djg; Martin, F E; Ellakwa, A E

    2015-12-01

    The aim of this study was to determine whether employing resin modified glass-ionomer based adhesives can reduce polymerization contraction stress generated at the interface of restorative composite adhesive systems. Five resin based adhesives (G Bond, Optibond-All-in-One, Optibond-Solo, Optibond-XTR and Scotchbond-Universal) and two resin modified glass-ionomer based adhesives (Riva Bond-LC, Fuji Bond-LC) were analysed. Each adhesive was applied to bond restorative composite Filtek-Z250 to opposing acrylic rods secured within a universal testing machine. Stress developed at the interface of each adhesive-restorative composite system (n = 5) was calculated at 5-minute intervals over 6 hours. The resin based adhesive-restorative composite systems (RBA-RCS) demonstrated similar interface stress profiles over 6 hours; initial rapid contraction stress development (0-300 seconds) followed by continued contraction stress development ≤0.02MPa/s (300 seconds - 6 hours). The interface stress profile of the resin modified glass-ionomer based adhesive-restorative composite systems (RMGIBA-RCS) differed substantially to the RBA-RCS in several ways. Firstly, during 0-300 seconds the rate of contraction stress development at the interface of the RMGIBA-RCS was significantly (p < 0.05) lower than at the interface of the RBA-RCS. Secondly, at 300 seconds and 6 hours the interface contraction stress magnitude of the RMGIBA-RCS was significantly (p < 0.05) lower than the stress of all assessed RBA-RCS. Thirdly, from 300 seconds to 6 hours both the magnitude and rate of interface stress of the RMGIBA-RCS continued to decline over the 6 hours from the 300 seconds peak. The use of resin modified glass-ionomer based adhesives can significantly reduce the magnitude and rate of polymerization contraction stress developed at the interface of adhesive-restorative composite systems. © 2015 Australian Dental Association.

  7. Modified Phenylethynyl Containing Imides for Secondary Bonding: Non-Autoclave, Low Temperature Processable Adhesives

    NASA Technical Reports Server (NTRS)

    Dezern, James F. (Technical Monitor); Chang, Alice C.

    1999-01-01

    As part of a program to develop structural adhesives for high performance aerospace applications, research continued on the development of modified phenylethynyl containing imides, LaRC(trademark)MPEIs. In previous reports, the polymer properties were controlled by varying the molecular weight, the amount of branching, and the phenylethynyl content and by blending with low molecular weight materials. This research involves changing the flexibility in the copolyimide backbone of the branched, phenylethynyl terminated adhesives. These adhesives exhibit excellent processability at pressures as low as 15 psi and temperatures as low as 288 C. The Ti/Ti lap shear specimens are processable in an autoclave or a temperature programmable oven under a vacuum bag at 288-300 C without external pressure. The cured polymers exhibit high mechanical properties and excellent solvent resistance. The chemistry and properties of these adhesives are presented.

  8. Injectable Dopamine-Modified Poly(ethylene glycol) Nanocomposite Hydrogel with Enhanced Adhesive Property and Bioactivity

    PubMed Central

    2015-01-01

    A synthetic mimic of mussel adhesive protein, dopamine-modified four-armed poly(ethylene glycol) (PEG-D4), was combined with a synthetic nanosilicate, Laponite (Na0.7+(Mg5.5Li0.3Si8)O20(OH)4)0.7–), to form an injectable naoncomposite tissue adhesive hydrogel. Incorporation of up to 2 wt % Laponite significantly reduced the cure time while enhancing the bulk mechanical and adhesive properties of the adhesive due to strong interfacial binding between dopamine and Laponite. The addition of Laponite did not alter the degradation rate and cytocompatibility of PEG-D4 adhesive. On the basis of subcutaneous implantation in rat, PEG-D4 nanocomposite hydrogels elicited minimal inflammatory response and exhibited an enhanced level of cellular infiltration as compared to Laponite-free samples. The addition of Laponite is potentially a simple and effective method for promoting bioactivity in a bioinert, synthetic PEG-based adhesive while simultaneously enhancing its mechanical and adhesive properties. PMID:25222290

  9. Conformational analysis of a modified RGD adhesive sequence.

    PubMed

    Triguero, Jordi; Zanuy, David; Alemán, Carlos

    2017-02-01

    The conformational preferences of the Arg-GlE-Asp sequence, where GlE is an engineered amino acid bearing a 3,4-ethylenedioxythiophene (EDOT) ring as side group, have been determined combining density functional theory calculations with a well-established conformational search strategy. Although the Arg-GlE-Asp sequence was designed to prepare a conducting polymer-peptide conjugate with excellent electrochemical and bioadhesive properties, the behavior of such hybrid material as adhesive biointerface is improvable. Results obtained in this work prove that the bioactive characteristics of the parent Arg-Gly-Asp sequence become unstable in Arg-GlE-Asp because of both the steric hindrance caused by the EDOT side group and the repulsive interactions between the oxygen atoms belonging to the backbone amide groups and the EDOT side group. Detailed analyses of the conformational preferences identified in this work have been used to re-engineer the Arg-GlE-Asp sequence for the future development of a new electroactive conjugate with improved bioadhesive properties. The preparation of this new conjugate is in progress. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

  10. Adhesion

    MedlinePlus

    ... the intestines, adhesions can cause partial or complete bowel obstruction . Adhesions inside the uterine cavity, called Asherman syndrome , ... 1. Read More Appendicitis Asherman syndrome Glaucoma Infertility Intestinal obstruction Review Date 4/5/2016 Updated by: Irina ...

  11. Adhesions

    MedlinePlus

    Adhesions are bands of scar-like tissue. Normally, internal tissues and organs have slippery surfaces so they can shift easily as the body moves. Adhesions cause tissues and organs to stick together. They ...

  12. Anti-proteolytic property and bonding durability of mussel adhesive protein-modified dentin adhesive interface.

    PubMed

    Fang, Hui; Li, Quan-Li; Han, Min; Mei, May Lei; Chu, Chun Hung

    2017-10-01

    To evaluate the effect of mussel adhesive protein (MAP) on collagenase activity, dentin collagen degradation and microtensile dentin bond strength (μTBS). Three groups were designed: 1. experimental group: treated with MAP; 2. positive control: treated with GM6001 (collagenase-inhibitor); 3. negative control: treated with distilled water (DW). For collagenase activity, Clostridiopeptidase-A was added to each group (n=5), and collagenase activity was assessed by colorimetric assay. For dentin collagen degradation, thirty dentin slabs were allocated to the three above groups (n=10). Dentin collagen degradation was evaluated by measuring released hydroxyproline by colorimetric assay after being incubated in Clostridiopeptidase-A for 7 days. For microtensile bond strength, sixty human third molars with flat dentin surfaces were etched by phosphoric acid and then assigned to the three above groups (n=20). An etch-and-rinse adhesive system was applied to all three groups as stated in standard clinic protocol. The test of μTBS was performed before and after thermocycling and collagenase challenge. The collagenase activities (nmol/min/mg) in the group of MAP was significantly less inactive compared to the group of GM6001 and DW (MAP0.06), the value of μTBSs after thermocycling and collagenase challenge was significantly greater in the group of MAP and GM6001 compared to the group of DW (MAP, GM6000>DW, p<0.001). MAP inhibits collagenase activity, prevents dentin collagen degradation, and delays the deterioration of the dentin bonding of composite restoration over time. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  13. In vitro evaluation of tissue adhesives composed of hydrophobically modified gelatins and disuccinimidyl tartrate

    NASA Astrophysics Data System (ADS)

    Matsuda, Miyuki; Taguchi, Tetsushi

    2012-12-01

    The effect of the hydrophobic group content in gelatin on the bonding strength of novel tissue-penetrating tissue adhesives was evaluated. The hydrophobic groups introduced into gelatin were the saturated hexanoyl, palmitoyl, and stearoyl groups, and the unsaturated oleoyl group. A collagen casing was employed as an adherend to model soft tissue for the in vitro determination of bonding strength of tissue adhesives composed of various hydrophobically modified gelatins and disuccinimidyl tartrate. The adhesive composed of stearoyl-modified gelatin (7.4% stearoyl; 10Ste) and disuccinimidyl tartrate showed the highest bonding strength. The bonding strength of the adhesives decreased as the degree of substitution of the hydrophobic groups increased. Cell culture experiments demonstrated that fluorescein isothiocyanate-labeled 10Ste was integrated onto the surface of smooth muscle cells and showed no cytotoxicity. These results suggest that 10Ste interacted with the hydrophobic domains of collagen casings, such as hydrophobic amino acid residues and cell membranes. Therefore, 10Ste-disuccinimidyl tartrate is a promising adhesive for use in aortic dissection.

  14. Adhesion mapping of chemically modified and poly(ethylene oxide)-grafted glass surfaces

    PubMed Central

    Jogikalmath, G.; Stuart, J.K.; Pungor, A.; Hlady, V.

    2012-01-01

    Two-dimensional mapping of the adhesion pull-off forces was used to study the origin of surface heterogeneity in the grafted poly(ethylene oxide) (PEO) layer. The variance of the pull-off forces measured over the μm-sized regions after each chemical step of modifying glass surfaces was taken to be a measure of the surface chemical heterogeneity. The attachment of γ-glycidoxypropyltrimethoxy silane (GPS) to glass decreased the pull-off forces relative to the clean glass and made the surface more uniform. The subsequent hydrolysis of the terminal epoxide groups resulted in a larger surface heterogeneity which was modeled by two populations of the terminal hydroxyl groups, each with its own distribution of adhesion forces and force variance. The activation of the hydroxyls with carbonyldiimmidazole (CDI) healed the surface and lowered its adhesion, however, the force variance remained rather large. Finally, the grafting of the α,ω-diamino poly(ethyleneoxide) chains to the CDI-activated glass largely eliminated adhesion except at a few discrete regions. The adhesion on the PEO grafted layer followed the Poisson distribution of the pull-off forces. With the exception of the glass surface, a correlation between the water contact angles and the mean pull-off forces measured with the Si3N4 tip surfaces was found for all modified glass surfaces. PMID:22267896

  15. Increased endothelial cell adhesion on plasma modified nanostructured polymeric and metallic surfaces for vascular stent applications.

    PubMed

    Pareta, Rajesh A; Reising, Alexander B; Miller, Tiffany; Storey, Dan; Webster, Thomas J

    2009-06-15

    Techniques to regenerate the vasculature have risen considerably over the last few decades due to the increased clinical diagnosis of artery narrowing and blood vessel blockage. Although initially re-establishing blood flow, current small diameter vascular regenerative materials often eventually cause thrombosis and restenosis due to a lack of initial endothelial cell coverage on such materials. The objective of this in vitro study was to evaluate commonly used vascular materials (specifically, polyethylene terephthalate, polytetrafluoroethylene, polyvinyl chloride, polyurethane, nylon, commercially pure titanium, and a titanium alloy (Ti6Al4V)) modified using an ionic plasma deposition (IPD) process and a nitrogen ion implantation plasma deposition (NIIPD) process. Such surface modifications have been previously shown to create nanostructured surface features which mimic the natural nanostructured surface features of blood vessels. The modified and unmodified surfaces were characterized by scanning electron microscopy, atomic force microscopy and surface energy measurements. Furthermore, in vitro endothelial cell adhesion tests (a key first step for vascular material endothelialization) demonstrated increased endothelial cell adhesion on many modified (with IPD and NIIPD + IPD) compared to unmodified samples. In general, endothelial cell adhesion increased with nanoroughness and surface energy but demonstrated a decreased endothelial cell adhesion trend after an optimal coating surface energy value was reached. Thus, results from this study provided materials and a versatile surface modification process that can potentially increase endothelialization faster than current unmodified (conventional) polymer and metallic vascular materials.

  16. The effect of elastomer chain length on properties of silicone-modified polyimide adhesives

    NASA Technical Reports Server (NTRS)

    St.clair, A. K.; St.clair, T. L.; Ezzell, S.

    1981-01-01

    A series of polyimides containing silicone elastomers was synthesized in order to study the effects of the elastomer chain length on polymer properties. The elastomer with repeat units varying from n=10 to 105 was chemically reacted into the backbone of an addition polyimide oligomer via reactive aromatic amine groups. Glass transition temperatures of the elastomer and polyimide phases were observed by torsional braid analysis. The elastomer-modified polyimides were tested as adhesives for bonding titanium in order to determine their potential for aerospace applications. Adhesive lap shear tests were performed before and after aging bonded specimens at elevated temperatures.

  17. An in vitro bacterial adhesion assessment of surface-modified medical-grade PVC.

    PubMed

    Asadinezhad, Ahmad; Novák, Igor; Lehocký, Marián; Sedlarík, Vladimir; Vesel, Alenka; Junkar, Ita; Sáha, Petr; Chodák, Ivan

    2010-06-01

    Medical-grade polyvinyl chloride was surface modified by a multistep physicochemical approach to improve bacterial adhesion prevention properties. This was fulfilled via surface activation by diffuse coplanar surface barrier discharge plasma followed by radical graft copolymerization of acrylic acid through surface-initiated pathway to render a structured high density brush. Three known antibacterial agents, bronopol, benzalkonium chloride, and chlorhexidine, were then individually coated onto functionalized surface to induce biological properties. Various modern surface probe techniques were employed to explore the effects of the modification steps. In vitro bacterial adhesion and biofilm formation assay was performed. Escherichia coli strain was found to be more susceptible to modifications rather than Staphylococcus aureus as up to 85% reduction in adherence degree of the former was observed upon treating with above antibacterial agents, while only chlorhexidine could retard the adhesion of the latter by 50%. Also, plasma treated and graft copolymerized samples were remarkably effective to diminish the adherence of E. coli.

  18. Bio-active molecules modified surfaces enhanced mesenchymal stem cell adhesion and proliferation.

    PubMed

    Mobasseri, Rezvan; Tian, Lingling; Soleimani, Masoud; Ramakrishna, Seeram; Naderi-Manesh, Hossein

    2017-01-29

    Surface modification of the substrate as a component of in vitro cell culture and tissue engineering, using bio-active molecules including extracellular matrix (ECM) proteins or peptides derived ECM proteins can modulate the surface properties and thereby induce the desired signaling pathways in cells. The aim of this study was to evaluate the behavior of human bone marrow mesenchymal stem cells (hBM-MSCs) on glass substrates modified with fibronectin (Fn), collagen (Coll), RGD peptides (RGD) and designed peptide (R-pept) as bio-active molecules. The glass coverslips were coated with fibronectin, collagen, RGD peptide and R-peptide. Bone marrow mesenchymal stem cells were cultured on different substrates and the adhesion behavior in early incubation times was investigated using scanning electron microscopy (SEM) and confocal microscopy. The MTT assay was performed to evaluate the effect of different bio-active molecules on MSCs proliferation rate during 24 and 72 h. Formation of filopodia and focal adhesion (FA) complexes, two steps of cell adhesion process, were observed in MSCs cultured on bio-active molecules modified coverslips, specifically in Fn coated and R-pept coated groups. SEM image showed well adhesion pattern for MSCs cultured on Fn and R-pept after 2 h incubation, while the shape of cells cultured on Coll and RGD substrates indicated that they might experience stress condition in early hours of culture. Investigation of adhesion behavior, as well as proliferation pattern, suggests R-peptide as a promising bio-active molecule to be used for surface modification of substrate in supporting and inducing cell adhesion and proliferation.

  19. Effects of delayed polymerization time and bracket manipulation on orthodontic resin modified glass ionomer adhesive

    NASA Astrophysics Data System (ADS)

    Gilbert, Danielle Wiggins

    This study examined the effect of varying delayed polymerization times in combination with bracket manipulation on shear bond strength (SBS), degree of conversion (DC), and adhesive remnant index (ARI) score when using a resin modified glass ionomer (RMGI) adhesive. Specimens were divided into three groups of clinically relevant delay times (0.5, 2, and 4-min) to simulate the delay that frequently occurs between bracket placement and manipulation and subsequent light curing. Based on an analysis of variance (alpha=.05), the SBS was not significantly different between the three groups. While one of the goals of this study was to be the first study to quantify DC of RMGI using Raman microspectroscopy, several challenges, including weak peak signal with and without fluorescence, were encountered and as a result, DC could not be determined. A significant difference (p<0.05) in ARI score was detected between the 0.5-min and 4.0-min delay groups with more adhesive remaining on the bracket with increasing delay time. A Spearman correlation between SBS and ARI indicated no positive association between SBS and ARI measures across delay times. The results of this study suggest that clinically relevant delay times of 0.5, 2, and 4-min do not negatively impact the SBS of a RMGI adhesive. However, with increasing delay time, the results suggest that more adhesive might remain on the bracket during debonding. With more adhesive remaining on the bracket, this could be beneficial in that less adhesive needs to be removed from enamel by grinding at the time of bracket removal when orthodontic treatment is completed.

  20. Adhesion force interactions between cyclopentane hydrate and physically and chemically modified surfaces.

    PubMed

    Aman, Zachary M; Sloan, E Dendy; Sum, Amadeu K; Koh, Carolyn A

    2014-12-07

    Interfacial interactions between liquid-solid and solid-solid phases/surfaces are of fundamental importance to the formation of hydrate deposits in oil and gas pipelines. This work establishes the effect of five categories of physical and chemical modification to steel on clathrate hydrate adhesive force: oleamide, graphite, citric acid ester, nonanedithiol, and Rain-X anti-wetting agent. Hydrate adhesive forces were measured using a micromechanical force apparatus, under both dry and water-wet surface conditions. The results show that the graphite coating reduced hydrate-steel adhesion force by 79%, due to an increase in the water wetting angle from 42 ± 8° to 154 ± 7°. Two chemical surface coatings (nonanedithiol and the citric acid ester) induced rapid hydrate growth in the hydrate particles; nonanedithiol increased hydrate adhesive force by 49% from the baseline, while the citric acid ester coating reduced hydrate adhesion force by 98%. This result suggests that crystal growth may enable a strong adhesive pathway between hydrate and other crystalline structures, however this effect may be negated in cases where water-hydrocarbon interfacial tension is minimised. When a liquid water droplet was placed on the modified steel surfaces, the graphite and citric acid ester became less effective at reducing adhesive force. In pipelines containing a free water phase wetting the steel surface, chemical or physical surface modifications alone may be insufficient to eliminate hydrate deposition risk. In further tests, the citric acid ester reduced hydrate cohesive forces by 50%, suggesting mild activity as a hybrid anti-agglomerant suppressing both hydrate deposition and particle agglomeration. These results demonstrate a new capability to develop polyfunctional surfactants, which simultaneously limit the capability for hydrate particles to aggregate and deposit on the pipeline wall.

  1. Research of Adhesion Bonds Between Gas-Thermal Coating and Pre-Modified Base

    NASA Astrophysics Data System (ADS)

    Kovalevskaya, Z.; Zaitsev, K.; Klimenov, V.

    2016-08-01

    Nature of adhesive bonds between gas-thermal nickel alloy coating and carbon steel base was examined using laser profilometry, optical metallography, transmission and scanning electron microscopy. The steel surface was plastically pre-deformed by an ultrasonic tool. Proved that ultrasound pre-treatment modifies the steel surface. Increase of dislocation density and formation of sub micro-structure are base elements of surface modification. While using high-speed gas-flame, plasma and detonation modes of coatings, surface activation occurs and durable adhesion is formed. Ultrasonic pre-treatment of base material is effective when sprayed particles and base material interact through physical-chemical bond formation. Before applying high-speed gas flame and plasma sprayed coatings, authors recommend ultrasonic pretreatment, which creates periodic wavy topography with a stroke of 250 microns on the steel surface. Before applying detonation sprayed coatings, authors recommend ultrasound pretreatment that create modified surface with a uniform micro-topography.

  2. Hydrophobic and high adhesive polyaniline layer of rectangular microtubes fabricated by a modified interfacial polymerization

    NASA Astrophysics Data System (ADS)

    Zhou, Chuanqiang; Gong, Xiangxiang; Qu, Yun; Han, Jie

    2016-08-01

    A modified interfacial polymerization of aniline is developed to fabricate hydrophobic and adhesive polyaniline (PANI) layer of rectangular microtubes on the glass substrate. The modified method uses pentanol as an organic medium to dissolve aniline monomer, with the water film of oxidant and surfactant on the glass substrate as water phase. The effects of some synthetic parameters (such as monomer concentration, alcohol molecular structure and surfactant type) on the morphology of PANI layer are studied for better understanding the fabrication of PANI nanostructures on the film. The alcohol molecular structure plays key role for the supermolecular assembly of PANI chains into nanostructures, while the surfactant may direct the array and deposition of these nanostructures on the glass substrate. The formation reason of PANI rectangular sub-microtubes is roughly interpreted according to our previous works. Wettability experiment indicates that the as-prepared PANI layer exhibits excellent hydrophobicity and high adhesive properties to water drop.

  3. Parachute mortar design.

    NASA Technical Reports Server (NTRS)

    Pleasants, J. E.

    1973-01-01

    Mortars are used as one method for ejecting parachutes into the airstream to decelerate spacecraft and aircraft pilot escape modules and to effect spin recovery of the aircraft. An approach to design of mortars in the class that can accommodate parachutes in the 20- to 55-foot-diameter size is presented. Parachute deployment considerations are discussed. Comments are made on the design of a power unit, mortar tube, cover, and sabot. Propellant selection and breech characteristics and size are discussed. A method of estimating hardware weights and reaction load is presented. In addition, some aspects of erodible orifices are given as well as comments concerning ambient effects on performance. This paper collates data and experience from design and flight qualification of four mortar systems, and provides pertinent estimations that should be of interest on programs considering parachute deployment.

  4. Parachute mortar design.

    NASA Technical Reports Server (NTRS)

    Pleasants, J. E.

    1973-01-01

    Mortars are used as one method for ejecting parachutes into the airstream to decelerate spacecraft and aircraft pilot escape modules and to effect spin recovery of the aircraft. An approach to design of mortars in the class that can accommodate parachutes in the 20- to 55-foot-diameter size is presented. Parachute deployment considerations are discussed. Comments are made on the design of a power unit, mortar tube, cover, and sabot. Propellant selection and breech characteristics and size are discussed. A method of estimating hardware weights and reaction load is presented. In addition, some aspects of erodible orifices are given as well as comments concerning ambient effects on performance. This paper collates data and experience from design and flight qualification of four mortar systems, and provides pertinent estimations that should be of interest on programs considering parachute deployment.

  5. Bacterial adhesion measurements on soft contact lenses using a Modified Vortex Device and a Modified Robbins Device.

    PubMed

    Schultz, C L; Pezzutti, M R; Silor, D; White, R

    1995-09-01

    S. marcescens 8100 and P. aeruginosa 15442 were used to study bacterial adhesion to hydrogel contact lenses which had not been worn. Bacterial removal from unworn lens materials was assessed with a calibrated vortex device modified with a digital rpm readout and fitted with a test tube attachment (MVD). The MVD, which relies on a whirlpool-like force to remove the bacteria, showed that bacteria adhered to the same degree to etafilcon A, vifilcon A and polymacon lenses under standardized conditions. Tracking the isoenzyme patterns of these bacterial species over time showed instability of S. marcescens upon repeated passage. This instability was not evident with P. aeruginosa. Bacterial adhesion of P. aeruginosa 15442, to human worn and unworn etafilcon A materials was determined with a Modified Robbins Device. The MRD was closed off at both ends stopping medium and bacterial movement after 1 h of fluid flow over the lens surface. The results show that immediately following this 1-h period more bacteria adhere to unworn contact lenses than to worn lenses. However, bacterial counts were equivalent on worn and unworn lenses following 5 h of static incubation.

  6. A modified microbial adhesion to hydrocarbons assay to account for the presence of hydrocarbon droplets.

    PubMed

    Zoueki, Caroline Warne; Tufenkji, Nathalie; Ghoshal, Subhasis

    2010-04-15

    The microbial adhesion to hydrocarbons (MATH) assay has been used widely to characterize microbial cell hydrophobicity and/or the extent of cell adhesion to hydrophobic liquids. The classical MATH assay involves spectrophotometric absorbance measurements of the initial and final cell concentrations in an aqueous cell suspension that has been contacted with a hydrocarbon liquid. In this study, microscopic examination of the aqueous cell suspension after contact with hexadecane or a hexadecane/toluene mixture revealed the presence of hydrocarbon droplets. The hydrocarbon droplets contributed to the absorbance values during spectrophotometric measurements and caused erroneous estimates of cell concentrations and extents of microbial adhesion. A modified MATH assay that avoids such artefacts is proposed here. In this modified assay, microscopic examination of the aqueous suspension and direct cell counts provides cell concentrations that are free of interference from hydrocarbon droplets. The presence of hydrocarbon droplets was noted in MATH assays performed with three bacterial strains, and two different hydrocarbons, at ionic strengths of 0.2 mM and 20 mM and pH 6. In these experiments, the formation of quasi-stable hydrocarbon droplets cannot be attributed to the presence of biosurfactants, or stabilization by biocolloids. The presence of surface potential at the hydrocarbon-water interface that was characterized by electrophoretic mobility of up to -1 and -2 microm cm/Vs, likely caused the formation of the quasi-stable hydrocarbon droplets that provided erroneous results using the classical MATH assay.

  7. Adhesion and proliferation of human endothelial cells on photochemically modified polytetrafluoroethylene.

    PubMed

    Gumpenberger, T; Heitz, J; Bäuerle, D; Kahr, H; Graz, I; Romanin, C; Svorcik, V; Leisch, F

    2003-12-01

    We studied the adhesion and proliferation of human endothelial cells on photochemically modified polytetrafluoroethylene samples. The polymer surfaces were modified by exposure to the ultraviolet light of a Xe(2)(*)-excimer lamp at a wavelength of 172 nm in an ammonia atmosphere. Treatment times were between 10 and 20 min. The endothelial cell density was determined 1, 3 and 8 days after seeding by image analysis. Surface modification of the samples resulted in a significant increase in the number of adhering cells and in the formation of a confluent cell layer after 3-8 days. The results were comparable than those obtained on polystyrene Petri dishes, which are used as standard substrates in cell cultivation. Thus modified PTFE appears to be a promising material for the fabrication of artificial vascular prostheses coated with endothelial cells.

  8. Cell Adhesion and Proliferation on Sulfonated and Non-Modified Chitosan Films.

    PubMed

    Martínez-Campos, Enrique; Civantos, Ana; Redondo, Juan Alfonso; Guzmán, Rodrigo; Pérez-Perrino, Mónica; Gallardo, Alberto; Ramos, Viviana; Aranaz, Inmaculada

    2016-09-15

    Three types of chitosan-based films have been prepared and evaluated: a non-modified chitosan film bearing cationizable aliphatic amines and two films made of N-sulfopropyl chitosan derivatives bearing both aliphatic amines and negative sulfonate groups at different ratios. Cell adhesion and proliferation on chitosan films of C2C12 pre-myoblastic cells and B16 cells as tumoral model have been tested. A differential cell behavior has been observed on chitosan films due to their different surface modification. B16 cells have shown lower vinculin expression when cultured on sulfonated chitosan films. This study shows how the interaction among cells and material surface can be modulated by physicochemical characteristics of the biomaterial surface, altering tumoral cell adhesion and proliferation processes.

  9. Preparation and characterization of PEG-modified polyurethane pressure-sensitive adhesives for transdermal drug delivery.

    PubMed

    Chen, Xuemei; Liu, Wei; Zhao, Yanbing; Jiang, Lingyu; Xu, Huibi; Yang, Xiangliang

    2009-06-01

    The purpose of this work was to develop novel pressure-sensitive adhesives (PSAs) for transdermal drug-delivery systems (TDDS) with proper adhesive properties, hydrophilicity, biocompatibility and high drug loading. Polyethyleneglycol-modified polyurethane PSAs (PEG-PU-PSAs) were synthesized by prepolymerization method with PEG-modified co-polyether and hexamethylene diisocyanate. The effects of reaction temperature, catalyst, ratios of NCO/OH, co-polyether composition, and chain extender were investigated. Drug loading was studied by using thiamazole (hydrophilic drug), diclofenac sodium (slightly hydrophilic drug), and ibuprofen (lipophilic drug) as model drugs. In vitro drug-release kinetics obtained with Franz diffusion cell and dialysis membrane. The results showed that when reaction temperature at 80 degrees C, weight percentage of stannous octoate as catalyst at 0.05%, ratio of NCO/OH at 2.0-2.2, ratio of PEG/polypropylene glycol (PPG)/polytetramethylene ether glycol (PTMG) at 30/25-30/50-55, and weight percentage of glycol as chain extender at 4.5%, PEGPU-PSAs synthesized performed well on adhesive properties. Actually, PEG on the main chain of the PU could improve the hydrophilicity of PSAs, whereas PPG and PTMG could offer proper adhesive properties. Skin compatibility test on volunteers indicated that PEG-PU-PSAs would not cause any skin irritations. All the model drugs had excellent stabilizations in PEG-PU-PSAs. In vitro drug-release kinetics demonstrated that the drug release depended on drug-loading level and solubility of the drug. These experimental results indicated that PEG-PU-PSAs have good potential for applications in TDDS.

  10. Cell adhesion on polytetrafluoroethylene modified by UV-irradiation in an ammonia atmosphere.

    PubMed

    Heitz, J; Svorcík, V; Bacáková, L; Rocková, K; Ratajová, E; Gumpenberger, T; Bäuerle, D; Dvoránková, B; Kahr, H; Graz, I; Romanin, C

    2003-10-01

    We report on the modification of polytetrafluoroethylene (PTFE) by exposure to the ultraviolet (UV) light of a Xe(2)*-excimer lamp at a wavelength of 172 nm in an ammonia atmosphere. Typical treatment times were up to 30 min. Subsequently, the samples were grafted with the amino acid alanine from an aqueous solution. The samples were characterized by means of optical transmission spectroscopy, laser-induced fluorescence and contact-angle measurements. We studied the adhesion of rat aortic smooth muscle cells (SMC) and mouse fibroblasts (3T3 cells) to the modified polymer samples using an in vitro technique, where the population density and spread of adhering cells is determined 24 h after seeding by image analysis. For both cell types the exposure of PTFE to UV-light in an ammonia atmosphere resulted in a significant increase in the number of adhering cells and in the size of their spreading area. The grafting with alanine enhanced this effect. Additional experiments with human endothelial cells (HEC) also demonstrated improved adhesion to modified PTFE. Thus, PTFE modified by our method appears to be a promising material for fabrication of artificial vascular prostheses and implants or for cultivation of skin substitutes.

  11. Domain decomposition methods for mortar finite elements

    SciTech Connect

    Widlund, O.

    1996-12-31

    In the last few years, domain decomposition methods, previously developed and tested for standard finite element methods and elliptic problems, have been extended and modified to work for mortar and other nonconforming finite element methods. A survey will be given of work carried out jointly with Yves Achdou, Mario Casarin, Maksymilian Dryja and Yvon Maday. Results on the p- and h-p-version finite elements will also be discussed.

  12. Delamination Damage Analyses of FRP Composite Spar Wingskin Joints with Modified Elliptical Adhesive Load Coupler Profile

    NASA Astrophysics Data System (ADS)

    Panigrahi, S. K.; Pradhan, B.

    2008-11-01

    Three-dimensional non-linear finite element analyses (FEA) for delamination damage onset and its growth in Graphite Fiber Reinforced Plastic (GFRP) composite Spar Wingskin Joints (SWJ) with modified elliptical adhesive load coupler profile for varied ratios of base width to height of the spar have been presented in this paper. Both in-plane and out-of-plane normal and shear stress variations on the interfacial surface of the wingskin between the spar and the wingskin have been evaluated. Coupled stress failure criterion has been used to predict the locations of initiation of failures due to delamination induced damages. Based on the stress and delamination damage analyses, suitable geometry of the modified elliptical adhesive load coupler profile of the SWJ has been recommended. The delamination damage has been observed to be initiated from the toe-end of the interfacial surface of the spar and the wingskin of the SWJ. Subsequently, the delamination propagations have also been studied by calculating the individual and the total Mode of Strain Energy Release Rate (SERR) along the delamination front using Modified Crack Closure Integral (MCCI) technique based on Linear Elastic Fracture Mechanics (LEFM) approach. It is seen that SERR variations along the delamination front i.e. across the width of the SWJ are not uniform. Therefore, a straight delamination front may grow into a curved delamination front as the delamination propagates. Also, it is found that Mode I SERR ( G I) governs the delamination propagation predominantly for the SWJ. Accordingly, suitable delamination arresting mechanism has been suggested.

  13. Corneal epithelial cell adhesion and growth on EGF-modified aminated PDMS.

    PubMed

    Klenkler, Bettina J; Dwivedi, Dhruva; West-Mays, Judith A; Sheardown, Heather

    2010-06-01

    Growth factor tethering has significant potential to mediate cellular responses in biomaterials and tissue engineering. We have previously demonstrated that epidermal growth factor (EGF) can be tethered to polydimethylsiloxane (PDMS) substrates and that these surfaces promoted interactions with human corneal epithelial cells in vitro. The goal of the current work was to better understand the specific effects of the tethered growth factor on the cells. The EGF was reacted with a homobifunctional N-hydroxysuccinimide (NHS) polyethylene glycol (PEG) derivative, and then bound to allyamine plasma-modified PDMS. Human corneal epithelial cells were seeded on the surfaces and cultured in serum-free medium for periods of up to 5 days. Cell growth was monitored and quantified by trypsinization and counting with a Coulter counter. Expression of matrix proteins and alpha(6)-integrins was assessed by immunostaining and confocal microscopy. A centrifugation assay was used to determine cell adhesion under an applied detachment force. Binding of EGF was found to significantly increase cell numbers and coverage across the surfaces at 5 days of culture in vitro. Immunofluorescence experiments indicate increased expression of fibronectin, laminin, and alpha(6)-integrins on the EGF-modified surfaces, and expression is localized at the cell-material interface as observed by confocal microscopy. In accordance with these results, the highest quantity of adherent cells is found on the EGF-modified subtrates at 5 days of culture. The results provide initial evidence that binding of EGF may be used to improve the epithelialization of and the adhesion of the cells on a polymeric artificial cornea device.

  14. Characterization of antibacterial and adhesion properties of chitosan-modified glass ionomer cement.

    PubMed

    Ibrahim, Marrwa A; Neo, Jennifer; Esguerra, Roxanna J; Fawzy, Amr S

    2015-10-01

    The aim is to investigate the effect of modifying the liquid phase of a conventional glass ionomer restorative material with different chitosan volume contents on the antibacterial properties and adhesion to dentin. The liquids of commercially available restorative glass ionomer cements (GIC) were modified with chitosan (CH) solutions at different volume contents (5%, 10%, 25%, and 50%). The GIC powders were mixed with the unmodified and the CH-modified liquids at the desired powder/liquid (P/L) ratio. For the characterization of the antibacterial properties, Streptococcus mutans biofilms were formed on GIC discs and characterized by scanning electron microscope (SEM), confocal microscopy, colony forming unit (CFU) count, and cell viability assay (MTS). The unmodified and CH-modified GICs were bonded to dentin surfaces and the micro-tensile bond strength (µTBs) was evaluated and the interface was investigated by SEM. Modification with CH solutions enhanced the antibacterial properties against S. mutans in terms of resistance to biofilm formation, CFU count, and MTS assay. Generally, significant improvement in the antibacterial properties was found with the increase in the CH volume content. Modification with 25% and 50% CH adversely affected the µTBs with predominant cohesive failure in the GIC. However, no difference was found between the control and the 5% and 10% CH-modified specimens. Incorporation of acidic solutions of chitosan in the polyacrylic acid liquid of GIC at v/v ratios of 5-10% improved the antibacterial properties of conventional glass ionomer cement against S. mutans without adversely affecting its bonding to dentin surface. © The Author(s) 2015.

  15. Adhesion-dependent negative friction coefficient on chemically modified graphite at the nanoscale

    NASA Astrophysics Data System (ADS)

    Deng, Zhao; Smolyanitsky, Alex; Li, Qunyang; Feng, Xi-Qiao; Cannara, Rachel J.

    2012-12-01

    From the early tribological studies of Leonardo da Vinci to Amontons’ law, friction has been shown to increase with increasing normal load. This trend continues to hold at the nanoscale, where friction can vary nonlinearly with normal load. Here we present nanoscale friction force microscopy (FFM) experiments for a nanoscale probe tip sliding on a chemically modified graphite surface in an atomic force microscope (AFM). Our results demonstrate that, when adhesion between the AFM tip and surface is enhanced relative to the exfoliation energy of graphite, friction can increase as the load decreases under tip retraction. This leads to the emergence of an effectively negative coefficient of friction in the low-load regime. We show that the magnitude of this coefficient depends on the ratio of tip-sample adhesion to the exfoliation energy of graphite. Through both atomistic- and continuum-based simulations, we attribute this unusual phenomenon to a reversible partial delamination of the topmost atomic layers, which then mimic few- to single-layer graphene. Lifting of these layers with the AFM tip leads to greater deformability of the surface with decreasing applied load. This discovery suggests that the lamellar nature of graphite yields nanoscale tribological properties outside the predictive capacity of existing continuum mechanical models.

  16. Adhesion-dependent negative friction coefficient on chemically modified graphite at the nanoscale.

    PubMed

    Deng, Zhao; Smolyanitsky, Alex; Li, Qunyang; Feng, Xi-Qiao; Cannara, Rachel J

    2012-12-01

    From the early tribological studies of Leonardo da Vinci to Amontons' law, friction has been shown to increase with increasing normal load. This trend continues to hold at the nanoscale, where friction can vary nonlinearly with normal load. Here we present nanoscale friction force microscopy (FFM) experiments for a nanoscale probe tip sliding on a chemically modified graphite surface in an atomic force microscope (AFM). Our results demonstrate that, when adhesion between the AFM tip and surface is enhanced relative to the exfoliation energy of graphite, friction can increase as the load decreases under tip retraction. This leads to the emergence of an effectively negative coefficient of friction in the low-load regime. We show that the magnitude of this coefficient depends on the ratio of tip-sample adhesion to the exfoliation energy of graphite. Through both atomistic- and continuum-based simulations, we attribute this unusual phenomenon to a reversible partial delamination of the topmost atomic layers, which then mimic few- to single-layer graphene. Lifting of these layers with the AFM tip leads to greater deformability of the surface with decreasing applied load. This discovery suggests that the lamellar nature of graphite yields nanoscale tribological properties outside the predictive capacity of existing continuum mechanical models.

  17. Void-free wafer-level adhesive bonding utilizing modified poly (diallyl phthalate)

    NASA Astrophysics Data System (ADS)

    Zhong, Fang; Dong, Tao; Yong, He; Yan, Su; Wang, Kaiying

    2013-12-01

    A new thermosetting polymer, modified poly (diallyl phthalate) (PDAP), is used as intermediate layer to realize a void-free wafer-level transfer bonding, in which the bonding interface contains patterned metal. Through glass-silicon bonding experiments, bonding defects are easily recognized with light microscopy. Three typical defect types are identified as: uneven flow defect, particle defect and bubble defect. The processing parameters, such as bonding pressure, pre-baking temperature, polymer thickness and coating conditions, have been optimized based on analysis of the defect formation. The optimized conditions have yielded a void-free wafer-level adhesive bonding. Then, the die shearing test indicates a good bonding strength. Additionally, the transfer bonding process is applied in SOI-silicon bonding as a practical example of MEMS fabrication.

  18. Testing of Mortar Systems

    DTIC Science & Technology

    2010-03-11

    Measure chamber pressure through the use of external piezoelectric or copper- crusher gauges. The use of such gauges requires a mortar cannon/barrel...tube tapped to receive the gauges. If such a tube cannot be obtained, use other methods, such as strain gages or internal copper- crusher gauges to...measure chamber pressure. Refer to ITOP 3-2-810. Note: When employing external crusher gauges, it is important not to replace used gauges with new

  19. Properties of Cement Mortar Produced from Mixed Waste Materials with Pozzolanic Characteristics

    PubMed Central

    Yen, Chi-Liang; Tseng, Dyi-Hwa; Wu, Yue-Ze

    2012-01-01

    Abstract Waste materials with pozzolanic characteristics, such as sewage sludge ash (SSA), coal combustion fly ash (FA), and granulated blast furnace slag (GBS), were reused as partial cement replacements for making cement mortar in this study. Experimental results revealed that with dual replacement of cement by SSA and GBS and triple replacement by SSA, FA, and GBS at 50% of total cement replacement, the compressive strength (Sc) of the blended cement mortars at 56 days was 93.7% and 92.9% of the control cement mortar, respectively. GBS had the highest strength activity index value and could produce large amounts of CaO to enhance the pozzolanic activity of SSA/FA and form calcium silicate hydrate gels to fill the capillary pores of the cement mortar. Consequently, the Sc development of cement mortar with GBS replacement was better than that without GBS, and the total pore volume of blended cement mortars with GBS/SSA replacement was less than that with FA/SSA replacement. In the cement mortar with modified SSA and GBS at 70% of total cement replacement, the Sc at 56 days was 92.4% of the control mortar. Modifying the content of calcium in SSA also increased its pozzolanic reaction. CaCl2 accelerated the pozzolanic activity of SSA better than lime did. Moreover, blending cement mortars with GBS/SSA replacement could generate more monosulfoaluminate to fill capillary pores. PMID:22783062

  20. Surface characteristics of acrylic modified polysulfone membranes improves renal proximal tubule cell adhesion and spreading.

    PubMed

    Teo, Jeremy Choon Meng; Ng, Roderica Rui Ge; Ng, Chee Ping; Lin, Alex Wei Haw

    2011-05-01

    Current polyvinylpyrrolidone-modified polysulfone (PVP-PSU) membranes in haemodialysers do not facilitate the attachment and proliferation of renal proximal tubule cells (RPTCs). For bioartificial kidney (BAK) development expensive extracellular matrices are employed to ensure the PVP-PSU membranes can serve as a substrate for RPTCs. In this study we modified PSU using an acrylic monomer (am-PSU) and polymerization using ultraviolet irradiation. We demonstrated that on adjusting the PSU or acrylic content of the membranes the wettability and surface chemistry were altered, and this affected the amount of fibronectin (Fn) that was adsorbed onto the membranes. Using an integrin blocking assay we ascertained that Fn is an important extracellular matrix component that mediates RPTC attachment. The amount of Fn adsorbed also led to different bioresponses of RPTCs, which were evaluated using attachment and proliferation assays and qualitative quantification of vinculin, focal adhesion kinase, zonula occludens and Na(+)/K(+) ATPase. Our optimized membrane, am-PSU1 (21.4% C-O groups, 19.1% PVP-PSU; contact angle 71.5-80.80, PVP-PSU: 52.4-67.50), supports a confluent monolayer of RPTCs and prevents creatinine and inulin diffusion from the apical to the basal side, meeting the requirements for application in BAKs. However, further in vivo evaluation to assess the full functionality of RPTCs on am-PSU1 is required. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  1. Protein Modifiers Generally Provide Limited Improvement in Wood Bond Strength of Soy Flour Adhesives

    Treesearch

    Charles R. Frihart; Linda Lorenz

    2013-01-01

    Soy flour adhesives using a polyamidoamine-epichlorohydrin (PAE) polymeric coreactant are used increasingly as wood adhesives for interior products. Although these adhesives give good performance, higher bond strength under wet conditions is desirable. Wet strength is important for accelerated tests involving the internal forces generated by the swelling of wood and...

  2. Effect of chemomechanical caries removal on bonding of resin-modified glass ionomer cement adhesives to caries-affected dentine.

    PubMed

    Hamama, Hhh; Yiu, Cky; Burrow, M F

    2015-06-01

    This study evaluated the effect of: (1) chemomechanical caries removal (CMCR); (2) dentine surface treatments and (3) dentine substrates on adhesion of resin-modified glass ionomer cement (RMGIC) adhesives. One hundred and twenty permanent molars exhibiting moderate cavitation on the occlusal surface into dentine were used. Seventy-five carious molars were used for bond strength testing; the remaining 45 for micromorphological evaluation of the bonded interface. Caries was excavated with NaOCl-based CMCR (Carisolv), enzyme-based CMCR (Papacarie), or conventional rotary caries removal methods. Dentine surface treatment was performed using 37% phosphoric acid, 25-30% PAA or 20% PAA + 3% AlCl3 . Three-way ANOVA revealed that all three factors 'caries removal methods', 'dentine surface treatments' and 'dentine substrates' did not significantly affect bond strength (p > 0.05). Scanning electron microscopy micrographs showed that the acid-base resistant layer was thicker in caries-affected dentine compared to sound dentine. NaOCl- and enzyme-based CMCR methods have no adverse effect on adhesion of RMGIC adhesives to sound and caries-affected dentine. Dentine surface treatment with 37% phosphoric acid for 5 s has no negative effect on bonding of RMGIC adhesives to dentine compared with using polyacrylic acid for 10 s. RMGIC adhesives bonded well to both sound and caries-affected dentine. © 2015 Australian Dental Association.

  3. Erythrocyte adhesion is modified by alterations in cellular tonicity and volume.

    PubMed

    Wandersee, Nancy J; Punzalan, Rowena C; Rettig, Michael P; Kennedy, Michael D; Pajewski, Nicholas M; Sabina, Richard L; Paul Scott, J; Low, Philip S; Hillery, Cheryl A

    2005-11-01

    We tested the hypothesis that dehydration-induced alterations in red blood cell (RBC) membrane organisation or composition contribute to sickle cell adhesion in sickle cell disease (SCD). To examine the role of RBC hydration in adhesion to the subendothelial matrix protein thrombospondin-1 (TSP), normal and sickle RBCs were incubated in buffers of varying tonicity and tested for adhesion to immobilised TSP under flow conditions. Sickle RBCs exhibited a decrease in TSP binding with increasing cell hydration (P<0.005), suggesting that cellular dehydration may contribute to TSP adhesion. Consistent with this hypothesis, normal RBCs showed an increase in TSP adhesion with increasing dehydration (P<0.01). Furthermore, increased TSP adhesion of normal RBCs could also be induced by isotonic dehydration using nystatin-sucrose buffers. Finally, TSP adhesion of both sickle RBCs and dehydrated normal RBCs was inhibited by the anionic polysaccharides, chondroitin sulphate A and high molecular weight dextran sulphate, but not by competitors of CD47-, band 3-, or RBC phosphatidylserine-mediated adhesion. More importantly, we found increased adhesion of nystatin-sucrose dehydrated normal mouse RBCs to kidney capillaries following re-infusion in vivo. In summary, these findings demonstrate that changes in hydration can significantly impact adhesion, causing normal erythrocytes to display adhesive properties similar to those of sickle cells and vice versa.

  4. Adhesion and removal kinetics of Bacillus cereus biofilms on Ni-PTFE modified stainless steel.

    PubMed

    Huang, Kang; McLandsborough, Lynne A; Goddard, Julie M

    2016-01-01

    Biofilm control remains a challenge to food safety. A well-studied non-fouling coating involves codeposition of polytetrafluoroethylene (PTFE) during electroless plating. This coating has been reported to reduce foulant build-up during pasteurization, but opportunities remain in demonstrating its efficacy in inhibiting biofilm formation. Herein, the initial adhesion, biofilm formation, and removal kinetics of Bacillus cereus on Ni-PTFE-modified stainless steel (SS) are characterized. Coatings lowered the surface energy of SS and reduced biofilm formation by > 2 log CFU cm(-2). Characterization of the kinetics of biofilm removal during cleaning demonstrated improved cleanability on the Ni-PTFE coated steel. There was no evidence of biofilm after cleaning by either solution on the Ni-PTFE coated steel, whereas more than 3 log and 1 log CFU cm(-2) of bacteria remained on the native steel after cleaning with water and an alkaline cleaner, respectively. This work demonstrates the potential application of Ni-PTFE non-fouling coatings on SS to improve food safety by reducing biofilm formation and improving the cleaning efficiency of food processing equipment.

  5. Loss of modifier of cell adhesion reveals a pathway leading to axonal degeneration.

    PubMed

    Chen, Qi; Peto, Charles A; Shelton, G Diane; Mizisin, Andrew; Sawchenko, Paul E; Schubert, David

    2009-01-07

    Axonal dysfunction is the major phenotypic change in many neurodegenerative diseases, but the processes underlying this impairment are not clear. Modifier of cell adhesion (MOCA) is a presenilin binding protein that functions as a guanine nucleotide exchange factor for Rac1. The loss of MOCA in mice leads to axonal degeneration and causes sensorimotor impairments by decreasing cofilin phosphorylation and altering its upstream signaling partners LIM kinase and p21-activated kinase, an enzyme directly downstream of Rac1. The dystrophic axons found in MOCA-deficient mice are associated with abnormal aggregates of neurofilament protein, the disorganization of the axonal cytoskeleton, and the accumulation of autophagic vacuoles and polyubiquitinated proteins. Furthermore, MOCA deficiency causes an alteration in the actin cytoskeleton and the formation of cofilin-containing rod-like structures. The dystrophic axons show functional abnormalities, including impaired axonal transport. These findings demonstrate that MOCA is required for maintaining the functional integrity of axons and define a model for the steps leading to axonal degeneration.

  6. Adhesion of Poly(phenylene sulfide) Resin with Polymeric Film of Triazine Thiol on Aluminum Surface Modified by Anodic Oxidation.

    PubMed

    Chung, Eun Hyuk; Jang, Eun Kyung; Hong, Tae Eun; Kim, Jong Pil; Kim, Hyun Gyu; Jin, Jong Sung; Hyun, Myung Ho; Shin, Dong Su; Bae, Jong-Seong; Jeong, Euh Duck

    2015-01-01

    Various surface modifications have been applied to improve the adhesion properties of aluminum for the cap plate and sealing quality of electrolyte on Li ion batteries. In this study, we have tried to find the effective condition for the polymerization of triazine thiols (TT) on modified aluminum surfaces by anodic aluminum oxide. Characterization of polymerized films on aluminum was explored by scanning electron microscopy, X-ray photoelectron spectroscopy, and secondary ion mass spectroscopy analysis. Scanning electron microscopy results reveal that meaningful roughness was formed on aluminum surfaces by anodic oxidation. Secondary ion mass spectroscopy analysis results represent that the peel strength was found to depend on film thickness and the composition of the adhesion layer. As a result, Al/PPS (polyphenylene sulfide) resin assemblies developed in this study have superior adhesive property. Therefore, these assemblies might be a viable candidate for a sealing technique for Li ion batteries.

  7. [Therapeutic evaluation of the polylactic acid gel (PLA-G) used for preventing skin flap adhesion in modified radical mastectomy].

    PubMed

    Chen, Guojing; Liu, Tao

    2013-12-01

    The present preliminary study was to observe the feasibility of the use of polylactic acid gel (PLA-G) in modified radical mastectomy and the ability of the PLA-G in the prevention of flap adhesion after operation. Sixty-eight patients were diagnosed with breast cancer, and received modified radical mastectomy from Jan. 2004 to Dec. 2006. The patients were divided randomly into a treatment group and a control group (with 34 cases each). The PLA-G was used under the surface of the auxiliary operative wound in the treatment group, and nothing was used in the control group. The wound healing, the wound complication, the amount of drainage solution, the indwelling time of the drainage tube and the auxiliary skin adhesion were evaluated after operation in both groups. There were no statistical difference on wound healing between the first intension (29:27) and the second intention (5:7), and the wound dehiscence after taking the stitches out (0:0) between the two intensions, the hematoma (0:1) and the effusion of the wound (5:6), and the flap necrosis (1:2) between two groups. There were also no statistical difference on the amount of drainage solution per day (6 +/- 3) and indwelling time of the drainage tube (6 +/- 4) after operation between the two groups (P > 0.5). After the operation, the case load with no flap adhesion in the treatment group was significant higher compared with the control group (22:8). The case load with complete acquired skin flap adhesion in the treatment group was visibly lower than in the control group (3:19), which proved that there was a significant statistical difference between the two groups (P < 0.05). This study suggested that the using of PLA-G in the breast cancer modified radical mastectomy could prevent skin flap adhesion without any harmful effects in the wound healing.

  8. Promotion of initial cell adhesion on trisuccinimidyl citrate-modified nickel-free high-nitrogen stainless steel.

    PubMed

    Sasaki, Makoto; Inoue, Motoki; Katada, Yasuyuki; Taguchi, Tetsushi

    2013-04-01

    The surface of nickel-free high-nitrogen stainless steel (HNS) was modified with a citric acid-based cross-linker, trisuccinimidyl citrate (TSC), to promote initial cell adhesion in external skeletal fixation pins. The remaining active ester groups on TSC-immobilized HNS reacted with the amino groups of serum proteins. The immobilized serum proteins formed cell recognition sites to promote the initial cell adhesion immediately after cell seeding. The amount of fibronectin, which is a typical cell adhesion protein, immobilized on the TSC-immobilized HNS surface was threefold greater than on the original HNS after only 15 min. The fibroblastic cell culture experiments showed that the initial cell adhesion was significantly enhanced on the TSC-immobilized HNS compared with the original HNS at 3 h. Furthermore, the cell adhesion activity of the TSC-immobilized HNS continued to promote cell proliferation even at 7 days. Therefore, TSC-immobilized HNS may enable the rapid integration of soft tissues through its reaction with the patient's serum proteins and extracellular proteins around the surgical site.

  9. Improvement of adhesion and proliferation of mouse embryonic stem cells cultured on ozone/UV surface-modified substrates.

    PubMed

    Kasai, Kohei; Kimura, Yuka; Miyata, Shogo

    2017-09-01

    Culturing pluripotent stem cells effectively requires feeder cell layers or cell adhesion matrix coating. However, the feeder cell layers or animal-derived factors have to be removed to apply the pluripotent stem cells as resources for regenerative medicine. To enable xeno-free culture conditions, we focused on the UV/ozone surface treatment technique for polystyrene cell culture substrates to improve the adhesion and proliferation of pluripotent stem cells. In this study, as a fundamental research for the feeder- and matrix coating-free culture system for embryonic stem cells (ESCs), mouse ESCs were cultured on UV/ozone-modified polystyrene substrates without feeder layers. We observed that UV/ozone surface-modified polystyrene substrates made it possible to culture mESCs under feeder-free conditions without any chemical treatment for the substrates. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. The effect of modified polysialic acid based hydrogels on the adhesion and viability of primary neurons and glial cells.

    PubMed

    Haile, Yohannes; Berski, Silke; Dräger, Gerald; Nobre, Andrè; Stummeyer, Katharina; Gerardy-Schahn, Rita; Grothe, Claudia

    2008-04-01

    In this study we present the enzymatic and biological analysis of polysialic acid (polySia) based hydrogel in terms of its degradation and cytocompatibility. PolySia based hydrogel is completely degradable by endosialidase enzyme which may avoid second surgery after tissue recovery. Viability assay showed that soluble components of polySia hydrogel did not cause any toxic effect on cultured Schwann cells. Moreover, green fluorescence protein transfected neonatal and adult Schwann cells, neural stem cells and dorsal root ganglionic cells (unlabelled) were seeded on polySia hydrogel modified with poly-L-lysine (Pll), poly-L-ornithine-laminin (porn-laminin) or collagen. Water soluble tetrazolium salt assay revealed that modification of the hydrogel significantly improved cell adhesion and viability. These results infer that polySia based scaffolds in combination with cell adhesion molecules and cells genetically modified to express growth factors would potentially be promising alternative in reconstructive therapeutic strategies.

  11. NMR relaxometry study of plaster mortar with polymer additives

    SciTech Connect

    Jumate, E.; Manea, D.; Moldovan, D.; Fechete, R.

    2013-11-13

    The cement mixed with water forms a plastic paste or slurry which stiffness in time and finally hardens into a resistant stone. The addition of sand aggregates, polymers (Walocel) and/or calcium carbonate will modify dramatically the final mortar mechanic and thermal properties. The hydration processes can be observed using the 1D NMR measurements of transverse T{sub 2} relaxation times distributions analysed by a Laplace inversion algorithm. These distributions were obtained for mortar pasta measured at 2 hours after preparation then at 3, 7 and 28 days after preparation. Multiple components are identified in the T{sub 2} distributions. These can be associated with the proton bounded chemical or physical to the mortar minerals characterized by a short T{sub 2} relaxation time and to water protons in pores with three different pore sizes as observed from SEM images. The evaporation process is faster in the first hours after preparation, while the mortar hydration (bonding of water molecules to mortar minerals) can be still observed after days or months from preparation. Finally, the mechanic resistance was correlated with the transverse T{sub 2} relaxation rates corresponding to the bound water.

  12. Effects of modifying the adhesive composition on the bond strength of orthodontic brackets.

    PubMed

    Bishara, Samir E; Ajlouni, Raed; Laffoon, John; Warren, John

    2002-10-01

    In an attempt to save chair time during bonding, metal brackets have been precoated with the adhesive material. Although the adhesive used on the precoated brackets is basically similar in composition to that used for bonding uncoated brackets, there are differences in the percentages of the various ingredients incorporated in the material. These changes are intended to enhance specific clinical properties. The purpose of this study was to determine whether modifications in the composition of the adhesives, used on precoated and uncoated metal brackets, affect their shear bond strengths during the first half hour after bonding. This is the time span when the initial arch wires are ligated. Sixty freshly extracted human molars were bonded with three different compositions of the same basic adhesive. The teeth were mounted in phenolic rings. An occlusogingival load was applied to the brackets producing a shear force at the bracket-tooth interface utilizing a Zwick Universal Test Machine. Analysis of variance was used to compare the three adhesives. Significance was predetermined at < or =.05 level of confidence. The present findings indicated that the shear bond strengths of the various modifications of the adhesive used on two different precoated metal brackets were not significantly different (F-ratio = .729 and P = .407) from those obtained with the conventional adhesive used on uncoated brackets. The mean values for the shear bond strengths of the two precoated brackets were: APC = 5.1+/-1.7 MPa and APC II = 4.9+/-2.1 MPa. The shear bond strength for the conventional adhesive used on the uncoated brackets was = 5.7+/-2.4 MPa. All bracket/adhesive combinations tested provided clinically acceptable shear bond forces within the first 30 minutes after initial bonding.

  13. Effect of surface wettability and topography on the adhesion of osteosarcoma cells on plasma-modified polystyrene.

    PubMed

    Dowling, Denis P; Miller, Ian S; Ardhaoui, Malika; Gallagher, William M

    2011-09-01

    Biomaterials interact with the biological environment at their surface, making accurate biophysical characterization of the surface crucially important for understanding subsequent biological effects. In this study, the surface of polystyrene (PS) was systematically altered in order to determine the effect of plasma treatment and surface roughness on cell adhesion and spreading. Surfaces with water contact angle from hydrophilic (12°) to superhydrophobic (155°) were obtained through a combination of modifying surface roughness (R (a)), the deposition of siloxane coatings and the fluorination of the PS surface. R (a) values in the range of 19-2365 nm were obtained by grinding the PS surface. The nanometer-thick siloxane coatings were deposited using an atmospheric pressure plasma system, while the fluorination of the PS was carried out using a low-pressure radio frequency (RF) plasma. The siloxane coatings were obtained using a liquid poly(dimethylsiloxane) precursor that was nebulized into helium or helium/oxygen plasmas. Water contact angles in the range of 12-122° were obtained with these coatings. Cell adhesion studies were carried out using human MG63 osteosarcoma cells. It was observed that higher polymer surface roughness enhanced cell adhesion, but had a negative effect on cell spreading. Optimum cell adhesion was observed at ∼64° for the siloxane coatings, with a decrease in adhesion observed for the more hydrophilic and hydrophobic coatings. This decrease in cell adhesion with an increase in hydrophobicity was also observed for the fluorinated PS surfaces with water contact angles in the range of 110-155°.

  14. Molecular design of bioconjugated cell adhesion peptide with a water-soluble polymeric modifier for enhancement of antimetastatic effect.

    PubMed

    Yamamoto, Yoko; Tsutsumi, Yasuo; Mayumi, Tadanori

    2002-04-01

    The adhesive interaction of tumor cells with various components of the extracellular matrix (ECM), such as laminin and fibronectin appears to play a crucial role in tumor metastasis. It has been reported that adhesive peptides, such as Tyr-Ile-Gly-Ser-Arg (YIGSR) in laminin and Arg-Gly-Asp (RGD), inhibited adhesion and invasion of various tumor cells to ECM in vitro, and exhibited inhibitory effects on pulmonary metastasis of B16-BL6 melanoma cells in mice. However, large doses of these peptides were required for significant anti-metastatic effects in vivo, probably due to their rapid degradation by various peptidases and their rapid excretion from the blood into the urine. To overcome these problems, the development of an appropriate drug delivery system (DDS) is required to improve in vivo stability and prolong plasma half-lives. Several strategies such as peptide-cyclization and D-amino acid substation have been reported to improve stability in blood by inhibiting enzymatic degradation. However, even these approaches have proven insufficient to overcome rapid renal clearance from the circulation. On the other hand, bioconjugation with water-soluble polymeric modifiers could markedly prolong the plasma half-lives by not only increasing peptidase resistance but also impeding renal excretion. In addition, it is possible to strictly control the in vivo pharmacokinetics of a peptide by introducing functional molecules with targeting or slow release capacities to the polymeric modifier. In this review we demonstrate with reference to our recent studies that bioconjugation of adhesive peptides with the appropriate polymeric modifier can enhance antimetastatic activity and may facilitate therapeutic use.

  15. Surface characterization and adhesion of oxygen plasma-modified LARC-TPI

    NASA Technical Reports Server (NTRS)

    Chin, J. W.; Wightman, J. P.

    1992-01-01

    LARC-TPI, an aromatic thermoplastic polyimide, was exposed to an oxygen plasma as a surface pretreatment for adhesive bonding. Chemical and physical changes which occurred in the polyimide surface as a result of the plasma treatment were investigated using X-ray photoelectron spectroscopy (XPS), infrared reflection-absorption spectroscopy (IR-RAS), contact-angle analysis, ellipsometry, and high resolution SEM. A 180-deg peel test with an acrylate-based pressure sensitive adhesive as a flexible adherent was utilized to study the interactions of the plasma-treated polyimide surface with other polymeric materials. The surface characterization and adhesion testing results showed that the oxygen plasma treatment, while creating a more hydrophilic, polar surface, also caused chain scission, resulting in the formation of a weak boundary layer which inhibited adhesion.

  16. Rapidly in situ forming adhesive hydrogel based on a PEG-maleimide modified polypeptide through Michael addition.

    PubMed

    Zhou, Yalin; Nie, Wei; Zhao, Jin; Yuan, Xiaoyan

    2013-10-01

    Polyethylene glycol-maleimide modified ε-polylysine (EPL-PEG-MAL) with a unique comb-shaped structure was designed and used as a novel crosslinker for thiolated chitosan (CSS). Novel polysaccharide/polypeptide bionic hydrogels based on CSS and EPL-PEG-MAL could form rapidly in situ within 1 min via Michael addition under physiological conditions. Rheological studies showed that introduction of PEG can dramatically improve the storage modulus (G') of the hydrogels and the optimal hydrogel system showed superior G' of 1,614 Pa. The maximum adhesion strength reached 148 kPa, six times higher than that of fibrin glue. Cytotoxicity test indicated that the hydrogel is nontoxic toward growth of L929 cells. Gelation time, swelling ratio, storage modulus and adhesion strength of the hydrogels can be modulated by the content of PEG-maleimide, CSS concentration and molar ratio of maleimide group to thiol group. Benefiting from the fast gelation behaviors, desirable mechanical properties, relatively high adhesive performance and no cytotoxicity, these hydrogels have the potential applications as promising biomaterials for tissue adhesion and sealing.

  17. Modified alginate and gelatin cross-linked hydrogels for soft tissue adhesive.

    PubMed

    Yuan, Liu; Wu, Yu; Fang, Jun; Wei, Xiaojuan; Gu, Qisheng; El-Hamshary, Hany; Al-Deyab, Salem S; Morsi, Yosry; Mo, Xiumei

    2017-02-01

    Soft tissue adhesives made from natural hydrogel are attractive in clinical applications due to their excellent properties, such as high water content, good biocompatibility, low immune, good biodegradability. Hydrogels derived from natural polysaccharides and proteins are ideal components for soft tissue adhesive since they resemble the extracellular matrices of the tissue composed of various sugar and amino acids-based macromolecules. In this paper, a series of novel tissue adhesives mixed by aldehyde sodium alginate (ASA) with amino gelatin (AG) were developed and characterized. The effect of aldehyde content in ASA and amino group content in AG on the properties of ASA/AG cross-linked hydrogel was measured. The results showed the gelling time, swelling behavior and the bonding strength of the hydrogel can be tuned by varying the content of aldehyde groups in ASA and the content of amino groups in AG. The gelation time could be controlled within 4-18 min. When the aldehyde content of ASA is 75.24% and the amino content of AG is 0.61 mmol/g, the hydrogel almost has the adhesive strength equal to the commercially available adhesive fibrin glue. So, this tunable ASA/AG hydrogels in this study could be a promising candidate as soft tissue adhesive and have a wide range of biomedical applications.

  18. Polymer films with surfaces unmodified and modified by non-thermal plasma as new substrates for cell adhesion.

    PubMed

    Borges, A M G; Benetoli, L O; Licínio, M A; Zoldan, V C; Santos-Silva, M C; Assreuy, J; Pasa, A A; Debacher, N A; Soldi, V

    2013-04-01

    The surface properties of biomaterials, such as wettability, polar group distribution, and topography, play important roles in the behavior of cell adhesion and proliferation. Gaseous plasma discharges are among the most common means to modify the surface of a polymer without affecting its properties. Herein, we describe the surface modification of poly(styrene) (PS) and poly(methyl methacrylate) (PMMA) films using atmospheric pressure plasma processing through exposure to a dielectric barrier discharge (DBD). After treatment the film surface showed significant changes from hydrophobic to hydrophilic as the water contact angle decreasing from 95° to 37°. All plasma-treated films developed more hydrophilic surfaces compared to untreated films, although the reasons for the change in the surface properties of PS and PMMA differed, that is, the PS showed chemical changes and in the case of PMMA they were topographical. Excellent adhesion and cell proliferation were observed in all films. In vitro studies employing flow cytometry showed that the proliferation of L929 cells was higher in the film formed by a 1:1 mixture of PS/PMMA, which is consistent with the results of a previous study. These findings suggest better adhesion of L929 onto the 1:1 PS/PMMA modified film, indicating that this system is a new candidate biomaterial for tissue engineering. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Properties of Cement Mortar by Use of Hot-Melt Polyamides as Substitute for Fine Aggregate

    PubMed Central

    Yuan, Xiongzhou; Xu, Weiting; Sun, Wei; Xing, Feng; Wang, Weilun

    2015-01-01

    This paper presents an experimental study on use of hot-melt polyamide (HMP) to prepare mortar specimens with improved crack healing and engineering properties. The role of HMP in the crack repairing of cement mortar subjected to several rounds of heat treatment was investigated. Compatibility between HMP and hydraulic cement was investigated through X-ray diffraction (XRD) and Fourier transform infrared spectra (FTIR) technology. Mortar specimens were prepared using standard cement mortar mixes with HMP at 1%, 3% and 5% (by volume) for fine aggregate substitute. After curing for 28 days, HMP specimens were subjected to heating at temperature of 160 °C for one, two, and three days and then natural cooling down to ambient temperature. Mechanical and durability properties of the heated HMP mortars were evaluated and compared with those of the corresponding mortars without heating. The microscopic observation of the interfacial transition zone (ITZ) of HMP mortar was conducted through environmental scanning electron microscopy (ESEM). Results reveal that incorporation of HMP improves the workability of the HMP/cement binder while leading to decrease in compressive strength and durability. The heated HMP mortars after exposure to heating for one, two, and three days exhibit no obvious change in compressive strength while presenting notable increase in flexural strength and durability compared with the corresponding mortars without heating. The XRD, FTIR and ESEM analyses indicate that no obvious chemical reaction occurs between HMP and hydraulic cement, and thus the self-repairing for interfacial micro-crack in HMP/cement composite system is ascribed to the physical adhesion of HMP to cement matrix rather than the chemical bonding between them.

  20. Novel epoxy-silicone thermolytic transparent packaging adhesives chemical modified by ZnO nanowires for HB LEDs

    NASA Astrophysics Data System (ADS)

    He, Ying; Wang, Jun-An; Pei, Chang-Long; Song, Ji-Zhong; Zhu, Di; Chen, Jie

    2010-10-01

    A novel high transparent thermolytic epoxy-silicone for high-brightness light-emitting diode (HB-LED) is introduced, which was synthesized by polymerization using silicone matrix via diglycidyl ether bisphenol-A epoxy resin (DGEBA) as reinforcing agent, and filling ZnO nanowires to modify thermal conductivity and control refractive index of the hybrid material. The interactions of ZnO nanowires with polymers are mediated by the ligands attached to the nanoparticles. Thus, the ligands markedly influence the properties of ZnO nanowires/epoxy-silicone composites. The refractive indices of the prepared hybrid adhesives can be tuned by the ZnO nanowires from 1.4711 to 1.5605. Light transmittance can be increased by 20% from 80 to 95%. The thermal conductivity of the transparent packaging adhesives is 0.89-0.90 W/mK.

  1. Moessbauer and adhesion study of ion beam-modified Fe-PTFE interfaces

    NASA Astrophysics Data System (ADS)

    Ingemarsson, P. Anders; Ericsson, Tore; Wappling, Roger; Possnert, Goran

    Conversion electron Moessbauer spectroscopy was used to study ion beam-induced effects at Fe-PTFE thin film interfaces and to relate these effects to accompanying modifications in adhesion. Irradiation with 16 MeV S-32(3+) ions to doses in the range between 5 x 10 to the 11th and 2 x 10 to the 14th ions/sq cm was carried out before or after deposition of thin Fe-57 layers. For both pre- and post-bombardment, a substantial adhesion enhancement was observed. Associated with this were significant changes in the Moessbauer spectra indicating the formation of Fe-C and Fe-F compounds. This compound formation can be associated with the observed improvement in thin film adhesion.

  2. Microtopography of metal surfaces influence fibroblast growth by modifying cell shape, cytoskeleton, and adhesion.

    PubMed

    Meredith, David O; Eschbach, Lukas; Riehle, Mathis O; Curtis, Adam S G; Richards, Robert G

    2007-11-01

    Stainless Steel (SS), titanium (cpTi), and Ti-6Al-7Nb (TAN) are frequently used metals in fracture fixation, which contact not only bone, but also soft tissue. In previous soft tissue cytocompatibility studies, TAN was demonstrated to inhibit cell growth in its "standard" micro-roughened state. To elucidate a possible mechanism for this inhibition, cell area, shape, adhesion, and cytoskeletal integrity was studied. Only minor changes in spreading were observed for cells on electropolished SS, cpTi, and TAN. Cells on "standard" cpTi were similarly spread in comparison with electropolished cpTi and TAN, although the topography influenced the cell periphery and also resulted in lower numbers and shorter length of focal adhesions. On "standard" microrough TAN, cell spreading was significantly lower than all other surfaces, and cell morphology differed by being more elongated. In addition, focal adhesion numbers and mean length were significantly lower on standard TAN than on all other surfaces, with 80% of the measured adhesions below a 2-microm threshold. Focal adhesion site location and maturation and microtubule integrity were compromised by the presence of protruding beta-phase microspikes found solely on the surface of standard TAN. This led us to propose that the impairment of focal adhesion numbers, maturation (length), and cell spreading to a possibly sufficient threshold observed on standard TAN blocks cell cycle progress and eventually cell growth on the surface. We believe, as demonstrated with standard cpTi and TAN, that a difference in surface morphology is influential for controlling cell behavior on implant surfaces.

  3. Epithelial cell morphology and adhesion on diamond films deposited and chemically modified by plasma processes.

    PubMed

    Rezek, Bohuslav; Ukraintsev, Egor; Krátká, Marie; Taylor, Andrew; Fendrych, Frantisek; Mandys, Vaclav

    2014-09-01

    The authors show that nanocrystalline diamond (NCD) thin films prepared by microwave plasma enhanced chemical vapor deposition apparatus with a linear antenna delivery system are well compatible with epithelial cells (5637 human bladder carcinoma) and significantly improve the cell adhesion compared to reference glass substrates. This is attributed to better adhesion of adsorbed layers to diamond as observed by atomic force microscopy (AFM) beneath the cells. Moreover, the cell morphology can be adjusted by appropriate surface treatment of diamond by using hydrogen and oxygen plasma. Cell bodies, cytoplasmic rims, and filopodia were characterized by Peakforce AFM. Oxidized NCD films perform better than other substrates under all conditions (96% of cells adhered well). A thin adsorbed layer formed from culture medium and supplemented with fetal bovine serum (FBS) covered the diamond surface and played an important role in the cell adhesion. Nevertheless, 50-100 nm large aggregates formed from the RPMI medium without FBS facilitated cell adhesion also on hydrophobic hydrogenated NCD (increase from 23% to 61%). The authors discuss applicability for biomedical uses.

  4. Platelet adhesion to commercial and modified polymer materials in animals under psychological stress and in a no-stress condition.

    PubMed

    Barbucci, Rolando; Lamponi, Stefania; Aloisi, Anna Maria

    2002-05-01

    It is well known that stressful stimuli change blood functions and that protein and platelet parameters are altered in humans and animals subjected to stress. We have examined the influence of psychological stress on the morphological responses of platelets on commercially available materials [polyester (VP), fluoropassivated polyester (VPF), non-woven benzylic ester of hyaluronic acid (Hyaff11)] and on materials synthesised (PUPA) and/or surface modified by sulphation (Hyaff11S) or by immobilisation of the anticoagulant molecules heparin and sulphated hyaluronic acid (PUPA-Heparin, PUPA-HyalS, HyalS-PET). Moreover, the anticoagulant activity (i.e. thrombin inactivation) of the materials was analysed. In the no-stress condition, the surfaces with a low degree of platelet adhesion were Hyaff11S, HyalS-PET, PUPA-Heparin and PUPA-HyalS. Hyaff11, PET and PUPA had the highest number of adherent platelets within the series. VP and VPF exhibited an intermediate behaviour. The exposure of animals to stress induced a dramatic change in platelet number and morphology on PET, HyalS-PET, PUPA, PUPA-HyalS and Hyaff11: there was a higher degree of platelet adhesion, increased platelet spreading and the appearance of pseudopodia. In VP, VPF, Hyaff11S and PUPA-Heparin, there were no changes in platelet adhesion in stress conditions with respect to the no-stress condition; the latter two materials, the only ones able to prolong thrombin time, had a very low number of adherent platelets.

  5. In vitro investigation of antioxidant, anti-Inflammatory, and antiplatelet adhesion properties of genistein-modified poly(ethersulfone)/poly(vinylpyrrolidone) hemodialysis membranes.

    PubMed

    Chang, Teng; DeFine, Linda; Alexander, Thomas; Kyu, Thein

    2015-04-01

    Hemocompatibility of genistein-modified poly(ethersulfone)/poly(vinylpyrrolidone) (PES/PVP) hemodialysis (HD) membranes has been investigated in vitro with emphasis on evaluation of cell viability, antioxidant, anti-inflammatory, and antiplatelet adhesion properties. Genistein modified PES/PVP membranes reveal significant reduction of the reactive oxygen species and also considerable suppression of interleukin-1β and tumor necrosis factor-α levels in whole blood, but to a lesser extent ininterleukin-6. The incorporation of PVP into the HD membrane reduces platelet adhesion by virtue of its hydrophilicity. Of particular importance is that platelet adhesion of the genistein modified membranes declines noticeably at low concentrations of genistein for about 5-10%, beyond which it raises the number of adhered platelets. The initial decline in the platelet adhesion is attributable to genistein's ability to inhibit intercellular and/or vascular cell adhesion, whereas the reversal of this adhesion trend with further increase of genistein loading is ascribed to the inherent hydrophobicity of the genistein modified HD membrane.

  6. Ionically cross-linked hyaluronic acid: wetting, lubrication, and viscoelasticity of a modified adhesion barrier gel

    PubMed Central

    Vorvolakos, Katherine; Isayeva, Irada S; Luu, Hoan-My Do; Patwardhan, Dinesh V; Pollack, Steven K

    2011-01-01

    Hyaluronic acid (HA), in linear or cross-linked form, is a common component of cosmetics, personal care products, combination medical products, and medical devices. In all cases, the ability of the HA solution or gel to wet surfaces and/or disrupt and lubricate interfaces is a limiting feature of its mechanism of action. We synthesized ferric ion–cross-linked networks of HA based on an adhesion barrier, varied the degree of cross-linking, and performed wetting goniometry, viscometry, and dynamic mechanical analysis. As cross-linking increases, so do contact angle, viscosity, storage modulus, and loss modulus; thus, wetting and lubrication are compromised. These findings have implications in medical device materials, such as adhesion barriers and mucosal drug delivery vehicles. PMID:22915924

  7. Water transfer properties and shrinkage in lime-based rendering mortars

    NASA Astrophysics Data System (ADS)

    Arizzi, A.; Cultrone, G.

    2012-04-01

    Rendering is the practice of covering a wall or a building façade with one or more layers of mortar, with the main aim to protect the masonry structure against weathering. The render applied must show high flexibility, good adhesion and compatibility with the support (i.e. stone, brick) and, overall, it should be characterised by low water absorption and high water vapour permeability. Water (in the solid, liquid and vapour state) is one of the main factors that drive construction materials to deterioration. Therefore, to evaluate the quality and durability of a rendering mortar, thus ensuring its protective function in the masonry structure, it is fundamental to assess the behaviour of this mortar towards water. Mortars were elaborated with a calcitic dry hydrated lime, a calcareous aggregate, a pozzolan, a lightweight aggregate, a water-retaining agent and a plasticiser. Four types of lime mortars were prepared, in which the binder-to-aggregate ratios were 1:3, 1:4, 1:6 and 1:9 by weight, whilst the pozzolan was kept at 10% of the lime (by mass) and the total admixtures proportion was less than 2% of the total mass. The influence of the characteristics of mortars pore system on the amount of water absorbed and the kinetics of absorption was investigated by means of: free water absorption and drying; capillary uptake; water permeability; water vapour permeability. Interesting deductions can be made from the values of water and water vapour permeability found for mortars: the former increases exponentially with the sand volume of the mortar, whilst the latter increases almost exponentially with the initial water content added to the mortar mixes during their elaboration. However, the relationship obtained between porosity of mortars and permeability values is not really clear. This finding suggests that the permeability of a material cannot be estimated on the basis of its porosity as it can be made for the capillary uptake and free water absorption. Another

  8. Pore size distribution of OPC and SRPC mortars in presence of chlorides

    SciTech Connect

    Suryavanshi, A.K.; Scantlebury, J.D.; Lyon, S.B.

    1995-07-01

    The pore structure of chloride-free ordinary portland cement (OPC) and sulphate resistant portland cement (SRPC) mortars are compared with the corresponding mortars with NaCl and CaCl{sub 2} added during mixing. In both OPC and SRPC mortars the addition of chlorides reduced the total accessible pore volumes compared to the corresponding chloride-free mortars. Also, in the presence of chlorides, the number of coarse pores were increased. These changes in the pore structure are believed to be due to dense calcium silicate hydrate (C-S-H) gel morphology formed in the presence of chlorides. The SRPC showed greater changes in pore structures than the OPC with equivalent amounts of chlorides added. This may be due to the lower chloride binding capacity of the SRPC and hence the higher availability of free chlorides to modify the gel morphology.

  9. Improvement of metal and tissue adhesion on surface-modified parylene C.

    PubMed

    Wahjudi, Paulin N; Oh, Jin H; Salman, Salam O; Seabold, Jason A; Rodger, Damien C; Tai, Yu-Chong; Thompson, Mark E

    2009-04-01

    A general method for chemical surface functionalization of parylene C [PC, (para-CH2-C6H3Cl-CH2-)n] films is reported. Friedel-Crafts acylation is used to activate the surface of the PC film, and the resulting carbonyl groups are then used to form a range of different organic functional groups to the surface of the parylene film, including alcohol, imine, thiol, phthalimide, amine, and maleimide. The presence of these functional groups on the parylene surface was confirmed by Fourier transform infrared spectroscopy. Static water drop contact angle measurements were also used to demonstrate the changes in hydrophilicity of the PC film surface, consistent with each of the surface modifications. Enhanced metal (gold) adhesion was achieved by anchoring a thiol group onto the acylated surface of PC film. Acylation of parylene with 2-chloropropionyl chloride gave a surface bound chloropropionyl group. Grafting of poly-N-isopropylacrylamide (pNIPAM) onto the chloropropionyl substituted PC film via atom transfer radical polymerization (ATRP) was carried out. The grafted pNIPAM on the parylene surface leads to temperature-dependent cellular tissue adhesion on the PC film.

  10. Minimally modified low-density lipoprotein induces monocyte adhesion to endothelial connecting segment-1 by activating β1 integrin

    PubMed Central

    Shih, Peggy T.; Elices, Mariano J.; Fang, Zhuang T.; Ugarova, Tatiana P.; Strahl, Dana; Territo, Mary C.; Frank, Joy S.; Kovach, Nicholas L.; Cabanas, Carlos; Berliner, Judith A.; Vora, Devendra K.

    1999-01-01

    We have shown previously that treatment of human aortic endothelial cells (HAECs) with minimally modified low-density lipoprotein (MM-LDL) induces monocyte but not neutrophil binding. This monocyte binding was not mediated by endothelial E-selectin, P-selectin, vascular cell adhesion molecule-I, or intercellular adhesion molecule-I, suggesting an alternative monocyte-specific adhesion molecule. We now show that moncytic α4β1 integrins mediate binding to MM-LDL-treated endothelial cells. We present data suggesting that the expression of the connecting segment-1 (CS-1) domain of fibronectin (FN) is induced on the apical surface of HAEC by MM-LDL and is the endothelial α4β1 ligand in MM-LDL-treated cells. Although the levels of CS-1 mRNA and protein were not increased, we show that MM-LDL treatment causes deposition of FN on the apical surface by activation of β1integrins, particularly those associated with α5 integrins.Activation of β1 by antibody 8A2 also induced CS-1-mediated monocyte binding. Confocal microscopy demonstrated the activated β1 and CS-1colocalize in concentrated filamentous patches on the apical surface of HAEC. Both anti-CS-1 and an antibody to activated β1 showed increased staining on the luminal endothelium of human coronary lesions with active monocyte entry. These results suggest the importance of these integrin ligand interactions in human atherosclerosis. J. Clin. Invest. 103:613–625 (1999) PMID:10074478

  11. New modified polyetheretherketone membrane for liver cell culture in biohybrid systems: adhesion and specific functions of isolated hepatocytes.

    PubMed

    De Bartolo, L; Morelli, S; Rende, M; Gordano, A; Drioli, E

    2004-08-01

    There has been growing interest in innovative materials with physico-chemical properties that provide improved blood/cell compatibility. We propose new polymeric membranes made of modified polyetheretherketone (PEEK-WC) as materials with potential for use in biohybrid devices. PEEK-WC exhibits high chemical, thermal stability and mechanical resistance. Owing to its lack of crystallinity this polymer can be used for preparing membranes with cheap and flexible methods. We compared the properties of PEEK-WC membranes to polyurethane membranes prepared using the same phase inverse technique and commercial membranes. The physico-chemical properties of the membranes were characterised by contact angle measurements. The different parameters acid (gamma+), base (gamma-) and Lifshitz-van der Waals (gammaLW) of the surface free energy were calculated according to Good-van Oss's model. We evaluated the cytocompatibility of PEEK-WC membranes by culturing hepatocytes isolated from rat liver. Cell adhesion and metabolic behaviour in terms of ammonia elimination, urea synthesis and protein synthesis were evaluated during the first days of culture. Liver cells adhered and formed three-dimensional aggregates on the most tested membranes. PEEK-WC membranes promoted hepatocyte adhesion most effectively. Urea synthesis, ammonia elimination and protein synthesis improved significantly when cells adhered to PEEK-WC membrane. The considerable metabolic activities of cells cultured on this membrane confirmed the good structural and physico-chemical properties of the PEEK-WC membrane that could be a promising biomaterial for cell culture in biohybrid devices.

  12. Rapid and efficient assembly of functional silicone surfaces protected by PEG: cell adhesion to peptide-modified PDMS.

    PubMed

    Mikhail, Andrew S; Ranger, Jill J; Liu, Lihua; Longenecker, Ryan; Thompson, David B; Sheardown, Heather D; Brook, Michael A

    2010-01-01

    While silicone elastomers generally have excellent biomaterials properties, their hydrophobicity can elicit undesired local biological responses through adsorption and denaturation of proteins. Surface-bound poly(ethylene glycol) (PEG) can ameliorate the situation by preventing contact between the external biology and the silicone elastomer. It is further possible to manipulate the biocompatibility of the surface by linking peptides, proteins or other biological entities to the PEG. Previous synthetic approaches to PEG-protected surfaces are compromised by issues of reproducibility. We describe two rapid and efficient approaches to silicone surface modification by PEG-linked adhesion peptides that overcome this problem: SiH groups are introduced throughout a silicone elastomer during elastomer synthesis or only at the surface after cure; then, in either case, protein-repellent PEG brushes at the surface are introduced by hydrosilylation to give surfaces that can be stored for extensive periods of time without degradation. Activation of the free alcohol with an NSC group followed by immediate conjugation to relevant biological molecules occurs in high yields, as shown for RGDS and GYRGDS. High surface grafting density of the peptides was demonstrated using radiolabeling techniques. Biological activity was demonstrated by a 5-fold increase in cell adhesion on the peptide-modified surfaces when compared to unmodified PDMS control surfaces.

  13. Cell adhesion and growth on surfaces modified by plasma and ion implantation

    NASA Astrophysics Data System (ADS)

    Araujo, W. W. R.; Teixeira, F. S.; da Silva, G. N.; Salvadori, D. M. F.; Salvadori, M. C.

    2014-04-01

    In this study, we show and discuss the results of the interaction of living CHO (Chinese Hamster Ovary) cells, in terms of adhesion and growth on glass, SU-8 (epoxi photoresist), PDMS (polydimethylsiloxane), and DLC (hydrogen free diamond-like carbon) surfaces. Glass, SU-8, and DLC but not PDMS showed to be good surfaces for cell growth. DLC surfaces were treated by oxygen plasma (DLC-O) and sulfur hexafluoride plasma (DLC-F). After 24 h of cell culture, the number of cells on DLC-O was higher than on DLC-F surface. SU-8 with silver implanted, creating nanoparticles 12 nm below the surface, increased significantly the number of cells per unit area.

  14. Assessment of tolerance to multistresses and in vitro cell adhesion in genetically modified Lactobacillus plantarum 590.

    PubMed

    Liu, Haiyan; Xu, Wentao; Luo, Yunbo; Tian, Hongtao; Wang, Hongxin; Guo, Xing; Yuan, Yanfang; Huang, Kunlun

    2011-03-01

    Lactobacillus plantarum (Lp) is a lactic acid bacterium that has many excellent traits that meet the needs of industrial production. Genetically modified (GM) Lp590 was obtained from Lp that was modified by the insertion of the gene nisI, which can confer resistance to nisin and play a role as a bio-preservative. Here, explorations were made to assess the safety of GM Lp590 and establish an in vitro evaluation model. The ability of Lp590 to tolerate both environmental stresses (such as temperatures ranging from 52 to 4 °C, or exposure to ethanol, oxygen, and osmotic stresses) and gastrointestinal transit was assessed. Lp590 showed a tolerance to 4 °C and ethanol (20%) within a period of 240 min that was similar to Lp. Notably, Lp590 can tolerate higher temperature (52 °C) and higher levels of H(2)O(2) (2%) and NaCl (4.0 M) than Lp. In contrast, Lp590 has the same gastrointestinal transit tolerance as Lp. In addition, Lp590 can adhere to Caco-2 cells, and it has no adverse effect on the cell membrane in vitro. These results indicate that GM Lp590 has many desirable biological characteristics and has good prospects for industrial applications. A useful and comprehensive exploration has been undertaken to establish a new in vitro evaluation model for genetically modified microorganisms (GMMs).

  15. Medium-density particleboards from modified rice husks and soybean protein concentrate-based adhesives.

    PubMed

    Ciannamea, Emiliano M; Stefani, Pablo M; Ruseckaite, Roxana A

    2010-01-01

    The main goal of this work was to evaluate the technical feasibility of using rice husk (RH) as wood substitute in the production of environmentally sound medium-density particleboards using adhesives from soybean protein concentrate (SPC). Chemical modification of rice husk with sodium hydroxide and sodium hydroxide followed by hydrogen peroxide (bleaching) were undertaken to evaluate the effect of such treatments on the composition and topology of rice husk and the performance of produced panels. Both treatments were efficient in partially eliminating hemicelluloses, lignin and silica from RH, as evidenced by thermo-gravimetric analysis (TGA). Scanning electron microscopy observations suggested that alkaline treatment resulted in a more damaged RH substrate than bleaching. The dependence of mechanical properties (modulus of rupture, modulus of elasticity, and internal bond) and the physical properties (water absorption and thickness swelling) on chemical treatments performed on both, rice husk and SPC was studied. Bleached-rice husk particleboards bonded with alkaline-treated soybean protein concentrate displayed the best set of final properties. Particleboards with this formulation met the minimum requirements of internal bond, modulus of elasticity and modulus of rupture recommended by the US Standard ANSI/A208.1 specifications for M1, MS and M2-grade medium-density particleboards, but failed to achieve the thickness swelling value recommended for general use panels. This limitation of soybean protein concentrate-bonded rice husk particleboards was counterbalanced by the advantage of being formaldehyde-free which makes them a suitable alternative for indoor applications.

  16. Adhesion, Proliferation and Migration of NIH/3T3 Cells on Modified Polyaniline Surfaces

    PubMed Central

    Rejmontová, Petra; Capáková, Zdenka; Mikušová, Nikola; Maráková, Nela; Kašpárková, Věra; Lehocký, Marián; Humpolíček, Petr

    2016-01-01

    Polyaniline shows great potential and promises wide application in the biomedical field thanks to its intrinsic conductivity and material properties, which closely resemble natural tissues. Surface properties are crucial, as these predetermine any interaction with biological fluids, proteins and cells. An advantage of polyaniline is the simple modification of its surface, e.g., by using various dopant acids. An investigation was made into the adhesion, proliferation and migration of mouse embryonic fibroblasts on pristine polyaniline films and films doped with sulfamic and phosphotungstic acids. In addition, polyaniline films supplemented with poly (2-acrylamido-2-methyl-1-propanesulfonic) acid at various ratios were tested. Results showed that the NIH/3T3 cell line was able to adhere, proliferate and migrate on the pristine polyaniline films as well as those films doped with sulfamic and phosphotungstic acids; thus, utilization of said forms in biomedicine appears promising. Nevertheless, incorporating poly (2-acrylamido-2-methyl-1-propanesulfonic) acid altered the surface properties of the polyaniline films and significantly affected cell behavior. In order to reveal the crucial factor influencing the surface/cell interaction, cell behavior is discussed in the context of the surface energy of individual samples. It was clearly demonstrated that the lesser the difference between the surface energy of the sample and cell, the more cyto-compatible the surface is. PMID:27649159

  17. The relationship between cellular adhesion and surface roughness for polyurethane modified by microwave plasma radiation.

    PubMed

    Keshel, Saeed Heidari; Azhdadi, S Neda Kh; Asefnejad, Azadeh; Asefnezhad, Azadeh; Sadraeian, Mohammad; Montazeri, Mohamad; Biazar, Esmaeil

    2011-01-01

    Surface modification of medical polymers is carried out to improve biocompatibility. In this study, conventional polyurethane was exposed to microwave plasma treatment with oxygen and argon gases for 30 seconds and 60 seconds. Attenuated total reflection Fourier transform infrared spectra investigations of irradiated samples indicated the presence of functional groups. Atomic force microscope images of samples irradiated with inert and active gases indicated the nanometric topography of the sample surfaces. Samples irradiated by oxygen plasma indicated high roughness compared with those irradiated by inert plasma for the different lengths of time. In addition, surface roughness increased with time, which can be due to a reduction of contact angle of samples irradiated by oxygen plasma. Contact angle analysis indicated a reduction in samples irradiated with both types of plasma. However, samples irradiated with oxygen plasma indicated lower contact angle compared with those irradiated by argon plasma. Cellular investigations with unrestricted somatic stem cells showed better adhesion, cell growth, and proliferation among samples radiated by oxygen plasma for longer than for normal samples.

  18. The relationship between cellular adhesion and surface roughness in polystyrene modified by microwave plasma radiation

    PubMed Central

    Biazar, Esmaeil; Heidari, Majid; Asefnezhad, Azadeh; Montazeri, Naser

    2011-01-01

    Background: Surface modification of medical polymers can improve biocompatibility. Pure polystyrene is hydrophobic and cannot provide a suitable environment for cell cultures. The conventional method for surface modification of polystyrene is treatment with plasma. In this study, conventional polystyrene was exposed to microwave plasma treatment with oxygen and argon gases for 30, 60, and 180 seconds. Methods and results: Attenuated total reflection Fourier transform infrared spectra investigations of irradiated samples indicated clearly the presence of functional groups. Atomic force microscopic images of samples irradiated with inert and active gases indicated nanometric surface topography. Samples irradiated with oxygen plasma showed more roughness (31 nm) compared with those irradiated with inert plasma (16 nm) at 180 seconds. Surface roughness increased with increasing duration of exposure, which could be due to reduction of the contact angle of samples irradiated with oxygen plasma. Contact angle analysis showed reduction in samples irradiated with inert plasma. Samples irradiated with oxygen plasma showed a lower contact angle compared with those irradiated by argon plasma. Conclusion: Cellular investigations with unrestricted somatic stem cells showed better adhesion, cell growth, and proliferation for samples radiated by oxygen plasma with increasing duration of exposure than those of normal samples. PMID:21698084

  19. In vitro analysis of riboflavin-modified, experimental, two-step etch-and-rinse dentin adhesive: Fourier transform infrared spectroscopy and micro-Raman studies.

    PubMed

    Daood, Umer; Swee Heng, Chan; Neo Chiew Lian, Jennifer; Fawzy, Amr S

    2015-06-26

    To modify two-step experimental etch-and-rinse dentin adhesive with different concentrations of riboflavin and to study its effect on the bond strength, degree of conversion, along with resin infiltration within the demineralized dentin substrate, an experimental adhesive-system was modified with different concentrations of riboflavin (m/m, 0, 1%, 3%, 5% and 10%). Dentin surfaces were etched with 37% phosphoric acid, bonded with respective adhesives, restored with restorative composite-resin, and sectioned into resin-dentin slabs and beams to be stored for 24 h or 9 months in artificial saliva. Micro-tensile bond testing was performed with scanning electron microscopy to analyse the failure of debonded beams. The degree of conversion was evaluated with Fourier transform infrared spectroscopy (FTIR) at different time points along with micro-Raman spectroscopy analysis. Data was analyzed with one-way and two-way analysis of variance followed by Tukey's for pair-wise comparison. Modification with 1% and 3% riboflavin increased the micro-tensile bond strength compared to the control at 24 h and 9-month storage with no significant differences in degree of conversion (P<0.05). The most predominant failure mode was the mixed fracture among all specimens except 10% riboflavin-modified adhesive specimens where cohesive failure was predominant. Raman analysis revealed that 1% and 3% riboflavin adhesives specimens showed relatively higher resin infiltration. The incorporation of riboflavin in the experimental two-step etch-and-rinse adhesive at 3% (m/m) improved the immediate bond strengths and bond durability after 9-month storage in artificial saliva without adversely affecting the degree of conversion of the adhesive monomers and resin infiltration.

  20. In vitro analysis of riboflavin-modified, experimental, two-step etch-and-rinse dentin adhesive: Fourier transform infrared spectroscopy and micro-Raman studies

    PubMed Central

    Daood, Umer; Swee Heng, Chan; Neo Chiew Lian, Jennifer; Fawzy, Amr S

    2015-01-01

    To modify two-step experimental etch-and-rinse dentin adhesive with different concentrations of riboflavin and to study its effect on the bond strength, degree of conversion, along with resin infiltration within the demineralized dentin substrate, an experimental adhesive-system was modified with different concentrations of riboflavin (m/m, 0, 1%, 3%, 5% and 10%). Dentin surfaces were etched with 37% phosphoric acid, bonded with respective adhesives, restored with restorative composite–resin, and sectioned into resin–dentin slabs and beams to be stored for 24 h or 9 months in artificial saliva. Micro-tensile bond testing was performed with scanning electron microscopy to analyse the failure of debonded beams. The degree of conversion was evaluated with Fourier transform infrared spectroscopy (FTIR) at different time points along with micro-Raman spectroscopy analysis. Data was analyzed with one-way and two-way analysis of variance followed by Tukey's for pair-wise comparison. Modification with 1% and 3% riboflavin increased the micro-tensile bond strength compared to the control at 24 h and 9-month storage with no significant differences in degree of conversion (P<0.05). The most predominant failure mode was the mixed fracture among all specimens except 10% riboflavin-modified adhesive specimens where cohesive failure was predominant. Raman analysis revealed that 1% and 3% riboflavin adhesives specimens showed relatively higher resin infiltration. The incorporation of riboflavin in the experimental two-step etch-and-rinse adhesive at 3% (m/m) improved the immediate bond strengths and bond durability after 9-month storage in artificial saliva without adversely affecting the degree of conversion of the adhesive monomers and resin infiltration. PMID:25257880

  1. Investigation of the oxide adhesion and growth characteristics on platinum-modified aluminide coatings. Master's thesis

    SciTech Connect

    Farrell, M.S.

    1986-09-01

    The operating environment for superalloy blades and vanes in gas turbine engines has necessitated the developed of alloy coatings to achieve satisfactory resistance of the metal to oxidation and hot corrosion. Aluminide coatings were initially developed to meet this need. Recently it was shown that platinum additions significantly improve the oxidation resistance of these aluminide coatings. The effects of pre-aluminizing surface smoothness and coating structure for both platinum modified and unmodified aluminide coatings on IN-738 in a cyclic oxidation environment at 1100 C were examined. Weight change measurements were used to determine the coating oxide scale adherence characteristics and to quantify the cyclic oxidation behavior of the various coating structures.

  2. Enhanced biocompatibility and wound healing properties of biodegradable polymer-modified allyl 2-cyanoacrylate tissue adhesive.

    PubMed

    Lee, Young Ju; Son, Ho Sung; Jung, Gyeong Bok; Kim, Ji Hye; Choi, Samjin; Lee, Gi-Ja; Park, Hun-Kuk

    2015-06-01

    As poly L-lactic acid (PLLA) is a polymer with good biocompatibility and biodegradability, we created a new tissue adhesive (TA), pre-polymerized allyl 2-cyanoacrylate (PACA) mixed with PLLA in an effort to improve biocompatibility and mechanical properties in healing dermal wound tissue. We determined optimal mixing ratios of PACA and PLLA based on their bond strengths and chemical structures analyzed by the thermal gravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopy. In vitro biocompatibility of the PACA/PLLA was evaluated using direct- and indirect-contact methods according to the ISO-10993 cytotoxicity test for medical devices. The PACA/PLLA have similar or even better biocompatibility than those of commercially available cyanoacrylate (CA)-based TAs such as Dermabond® and Histoacryl®. The PACA/PLLA were not different from those exposed to Dermabond® and Histoacryl® in Raman spectra when biochemical changes of protein and DNA/RNA underlying during cell death were compared utilizing Raman spectroscopy. Histological analysis revealed that incised dermal tissues of rats treated with PACA/PLLA showed less inflammatory signs and enhanced collagen formation compared to those treated with Dermabond® or Histoacryl®. Of note, tissues treated with PACA/PLLA were stronger in the tensile strength compared to those treated with the commercially available TAs. Therefore, taking all the results into consideration, the PACA/PLLA we created might be a clinically useful TA for treating dermal wounds. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Evaluation of the bond strength of different adhesive agents to a resin-modified calcium silicate material (TheraCal LC).

    PubMed

    Karadas, Muhammed; Cantekin, Kenan; Gumus, Husniye; Ateş, Sabit Melih; Duymuş, Zeynep Yesil

    2016-09-01

    This study evaluated the bond strength of different adhesive agents to TheraCal LC and mineral trioxide aggregate (MTA) and examined the morphologic changes of these materials with different surface treatments. A total of 120 specimens, 60 of MTA Angelus (AMTA), and 60 of TheraCal LC, were prepared and divided into six subgroups according to the adhesive agent used; these agents included Scotchbond Multipurpose, Clearfil SE Bond, Clearfil Protect Bond, Clearfil S(3) Bond, OptiBond All-in-One, and G-aenial Bond. After application of adhesive agents, Filtek Z250 composite resin was placed onto the specimens. Shear bond strengths were measured using a universal testing machine, followed by examination of the fractured surfaces. The surface changes of the specimens were observed using scanning electron microscopy. Data were compared by two-way analysis of variance. Although no significant differences were found among the bond strengths of different adhesives to AMTA (p = 0.69), a significant difference was found in terms of bond strengths of different adhesives to the TheraCal LC surface (p < 0.001). The total-etch adhesive system more strongly bonded to TheraCal LC compared to the bond with other adhesives. TheraCal LC bonded significantly more strongly than AMTA regardless of the adhesive agents tested. Resin-modified calcium silicate showed higher bond strength than AMTA in terms of the composite bond to these materials with different bonding systems. On the other hand, the highest shear bond-strength values were found for composite bonds with the combination of TheraCal LC and the total-etch adhesive system. SCANNING 38:403-411, 2016. © 2015 Wiley Periodicals, Inc.

  4. Simple Analysis of Historical Lime Mortars

    ERIC Educational Resources Information Center

    Pires, Joa~o

    2015-01-01

    A laboratory experiment is described in which a simple characterization of a historical lime mortar is made by the determination of its approximate composition by a gravimetric method. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) are also used for the qualitative characterization of the lime mortar components. These…

  5. Simple Analysis of Historical Lime Mortars

    ERIC Educational Resources Information Center

    Pires, Joa~o

    2015-01-01

    A laboratory experiment is described in which a simple characterization of a historical lime mortar is made by the determination of its approximate composition by a gravimetric method. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) are also used for the qualitative characterization of the lime mortar components. These…

  6. The effects of surface chemistry and adsorbed proteins on monocyte/macrophage adhesion to chemically modified polystyrene surfaces.

    PubMed

    Shen, M; Horbett, T A

    2001-12-05

    Monocytes and macrophages play critical roles in inflammatory responses to implanted biomaterials. Monocyte adhesion may lead to macrophage activation and the foreign body response. We report that surface chemistry, preadsorbed proteins, and adhesion time all play important roles during monocyte adhesion in vitro. The surface chemistry of tissue culture polystyrene (TCPS), polystyrene, Primaria, and ultra low attachment (ULA) used for adhesion studies was characterized by electron spectroscopy for chemical analysis. Fibrinogen adsorption measured by (125)I-labeled fibrinogen was the lowest on ULA, higher on TCPS, and the highest on polystyrene or Primaria. Monocyte adhesion on protein preadsorbed surfaces for 2 h or 1 day was measured with a lactate-dehydrogenase method. Monocyte adhesion decreased over time. The ability of preadsorbed proteins to modulate monocyte adhesion was surface dependent. Adhesion was the lowest on ULA, higher and similar on TCPS or polystyrene, and the highest on Primaria. Monocyte adhesion on plasma or fibrinogen adsorbed surfaces correlated positively and linearly to the amount of adsorbed fibrinogen. Preadsorbed fibronectin, immunoglobulin G, plasma, or serum also promoted adhesion compared with albumin preadsorbed or uncoated surfaces. Overall, biomaterial surface chemistry, the type and amount of adsorbed proteins, and adhesion time all affected monocyte adhesion in vitro. Copyright 2001 John Wiley & Sons, Inc. J Biomed Mater Res 57: 336-345, 2001

  7. Comparative of fibroblast and osteoblast cells adhesion on surface modified nanofibrous substrates based on polycaprolactone.

    PubMed

    Sharifi, Fereshteh; Irani, Shiva; Zandi, Mojgan; Soleimani, Masoud; Atyabi, Seyed Mohammad

    2016-12-01

    One of the determinant factors for successful bioengineering is to achieve appropriate nano-topography and three-dimensional substrate. In this research, polycaprolactone (PCL) nano-fibrous mat with different roughness modified with O2 plasma was fabricated via electrospinning. The purpose of this study was to evaluate the effect of plasma modification along with surface nano-topography of mats on the quality of human fibroblast (HDFs) and osteoblast cells (OSTs)-substrate interaction. Surface properties were studied using scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle, Fourier-transformation infrared spectroscopy. We evaluated mechanical properties of fabricated mats by tensile test. The viability and proliferation of HDFs and OSTs on the substrates were followed by 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT). Mineralization of the substrate was determined by alizarin red staining method and calcium content of OSTs was determined by calcium content kit. Cells morphology was studied by SEM analysis. The results revealed that the plasma-treated electrospun nano-fibrous substrate with higher roughness was an excellent designed substrate. A bioactive topography for stimulating proliferation of HDFs and OSTs is to accelerate the latter's differentiation time. Therefore, the PCL substrate with high density and major nano-topography were considered as a bio-functional and elegant bio-substrate for tissue regeneration applications.

  8. Novel silsesquioxane mixture-modified high elongation polyurethane with reduced platelet adhesion

    NASA Astrophysics Data System (ADS)

    Tao, William; Zhou, Hongyang; Zhang, Yan; Li, Gang

    2008-02-01

    We have successfully synthesized a kind of novel silsesquioxane mixture that can be used to modify the surface of biomaterial polyurethane (PU) for the purpose of making silsesquioxane/PU as low-price and high-quality biomaterial. HPLC, FTIR and 29Si NMR are used to characterize as-synthesized silsesquioxane mixture. XPS figure and SEM images show the silsesquioxane particles really self-assemble on the PU surface. Contact angle measurements verify that there is a large hysteresis loop, which relates to low- and high-surface free energy component on the surface. Platelet adsorption at 90 min of PU/silsesquioxane mixture is lower than that of poly(tetrafluoroethylene) (PTFE) and PU (two-way ANOVA, p < 0.05). Furthermore, SEM images show "island" morphologic pattern with Cooper grades I platelet adsorption morphology on the smooth PU/silsesquioxane surface, and mechanic test shows that the samples with silsesquioxane mixture can increase mechanic property of PU. On the basis of these results, we conclude that this kind of nanocomposite has promise for application in biomaterials.

  9. Glass-modified stress waves for adhesion measurement of ultra thin films for device applications

    NASA Astrophysics Data System (ADS)

    Gupta, Vijay; Kireev, Vassili; Tian, Jun; Yoshida, Hiroshi; Akahoshi, Haruo

    2003-08-01

    Laser-generated stress wave profiles with rarefaction shocks (almost zero post-peak decay times) have been uncovered in different types of glasses and presented in this communication. The rise time of the pulses was found to increase with their amplitude, with values reaching as high as 50 ns. This is in contrast to measurements in other brittle crystalline solids where pulses with rise times of 1 -2 ns and post-peak decay times of 16 -20 ns were recorded. The formation of rarefaction shock is attributed to the increased compressibility of glasses with increasing pressures. This was demonstrated using a one-dimensional nonlinear elastic wave propagation model in which the wave speed was taken as a function of particle velocity. The technological importance of these pulses in measuring the tensile strength of very thin film interfaces is demonstrated by using a previously developed laser spallation experiment in which a laser-generated compressive stress pulse in the substrate reflects into a tensile wave from the free surface of the film and pries off its interface at a threshold amplitude. Because of the rarefaction shock, glass-modified waves allow generation of substantially higher interfacial tensile stress amplitudes compared with those with finite post-peak decay profiles. Thus, for the first time, tensile strengths of very strong and ultra thin film interfaces can be measured. Results presented here indicate that interfaces of 185-nm-thick films, and with strengths as high as 2.7 GPa, can be measured. Thus, an important advance has been made that should allow material optimization of ultra thin layer systems that may form the basis of future MEMS-based microelectronic, mechanical and clinical devices.

  10. Bond strength between composite resin and resin modified glass ionomer using different adhesive systems and curing techniques.

    PubMed

    Boruziniat, Alireza; Gharaei, Samineh

    2014-03-01

    To evaluate bond strength between RMGI and composite using different adhesive systems and curing techniques. Sixty prepared samples of RMGI were randomly divided into six groups according to adhesive systems (total-etch, two-step self-etch and all-in-one) and curing techniques (co-curing and pre-curing). In co-curing technique, the adhesive systems were applied on uncured RMGI samples and co-cured together. In the pre-curing technique, before application of adhesive systems, the RMGI samples were cured. Composite layers were applied and shear bond strength was measured. Two samples of each group were evaluated by SEM. Failure mode was determined by streomicroscope. Both curing methods and adhesive systems had significant effect on bond strength (P-value < 0.05). There was an interaction between two factors (P-value <0.05). Both self-etch adhesives had significantly higher shear bond strength than the total-etch adhesive (P-value <0.05). The co-curing technique improved the bond strength in self-etch adhesives, but decreased the bond strength in total-etch adhesive (P-value<0.05). The application of self-etch adhesive systems and co-curing technique can improve the bond strength between the RMGI and composite.

  11. Detrimental effects of cement mortar and fly ash mortar on asthma progression.

    PubMed

    Cho, Ara; Jang, Hong-Seok; Roh, Yoon Seok; Park, Hee Jin; Talha, A F S M; So, Seung-Young; Lim, Chae Woong; Kim, Bumseok

    2013-11-01

    Currently, concrete additive materials are used worldwide to improve properties of concrete production and to reduce the total cost of the materials used in the concrete. However, the effects of exposure to various gases emitted from mortar mixed with additive materials are poorly understood. To evaluate the pattern of gas emission from cement mortar and additives, the emission levels of gas including ammonia (NH3) and volatile organic compounds (VOCs) were measured from two different mortar types, Ordinary Portland Cement (OPC), and OPC with fly ash on various time points after manufacture. On days 1, 3, 10 and 30 after manufacture, moderate concentrations of NH3 (4, 9, 12 and 5 ppm) were measured in OPC mortar (24h, 150 mm × 150 mm × 50 mm), whereas higher concentrations of NH3 (73, 55, 20 and 5 ppm) were measured in OPC mortar with fly ash (24h, 150 mm × 150 mm × 50 mm). Furthermore, the concentration of VOCs was more than 10 ppm on 1, 3, and 10 days of age in OPC and OPC with fly ash mortars. To examine the mortars' allergic effects on the respiratory system, mice were sensitized with ovalbumin (OVA) and divided into four groups: normal, asthma control, OPC mortar and OPC mortar with fly ash. The mice were housed in corresponding group cage for 10 days with OVA challenges to induce asthma. Histopathologically, increased infiltration of lymphocytes was observed in the lung perivascular area of mice housed in OPC mortar and OPC mortar with fly ash cages compared to lungs of asthma control mice. Moreover, severe bronchial lumen obstruction and increased hypertrophy of bronchial epithelial cells (p<0.05) were observed in the OPC mortar with fly ash group compared to OPC mortar or asthma control groups. Lungs of the two mortar groups generally expressed higher levels of genes related with asthma, including IL-4, eotaxin and epidermal growth factor (EGF) compared to lungs of asthma control mice. Additionally, the OPC mortar with fly ash group showed higher

  12. rFN/Cad-11-modified collagen type II biomimetic interface promotes the adhesion and chondrogenic differentiation of mesenchymal stem cells.

    PubMed

    Dong, Shiwu; Guo, Hongfeng; Zhang, Yuan; Li, Zhengsheng; Kang, Fei; Yang, Bo; Kang, Xia; Wen, Can; Yan, Yanfei; Jiang, Bo; Fan, Yujiang

    2013-11-01

    Properties of the cell-material interface are determining factors in the successful function of cells for cartilage tissue engineering. Currently, cell adhesion is commonly promoted through the use of polypeptides; however, due to their lack of complementary or modulatory domains, polypeptides must be modified to improve their ability to promote adhesion. In this study, we utilized the principle of matrix-based biomimetic modification and a recombinant protein, which spans fragments 7-10 of fibronectin module III (heterophilic motif) and extracellular domains 1-2 of cadherin-11 (rFN/Cad-11) (homophilic motif), to modify the interface of collagen type II (Col II) sponges. We showed that the designed material was able to stimulate cell proliferation and promote better chondrogenic differentiation of rabbit mesenchymal stem cells (MSCs) in vitro than both the FN modified surfaces and the negative control. Further, the Col II/rFN/Cad-11-MSCs composite stimulated cartilage formation in vivo; the chondrogenic effect of Col II alone was much less significant. These results suggested that the rFN/Cad-11-modified collagen type II biomimetic interface has dual biological functions of promoting adhesion and stimulating chondrogenic differentiation. This substance, thus, may serve as an ideal scaffold material for cartilage tissue engineering, enhancing repair of injured cartilage in vivo.

  13. rFN/Cad-11-Modified Collagen Type II Biomimetic Interface Promotes the Adhesion and Chondrogenic Differentiation of Mesenchymal Stem Cells

    PubMed Central

    Guo, Hongfeng; Zhang, Yuan; Li, Zhengsheng; Kang, Fei; Yang, Bo; Kang, Xia; Wen, Can; Yan, Yanfei; Jiang, Bo; Fan, Yujiang

    2013-01-01

    Properties of the cell-material interface are determining factors in the successful function of cells for cartilage tissue engineering. Currently, cell adhesion is commonly promoted through the use of polypeptides; however, due to their lack of complementary or modulatory domains, polypeptides must be modified to improve their ability to promote adhesion. In this study, we utilized the principle of matrix-based biomimetic modification and a recombinant protein, which spans fragments 7–10 of fibronectin module III (heterophilic motif ) and extracellular domains 1–2 of cadherin-11 (rFN/Cad-11) (homophilic motif ), to modify the interface of collagen type II (Col II) sponges. We showed that the designed material was able to stimulate cell proliferation and promote better chondrogenic differentiation of rabbit mesenchymal stem cells (MSCs) in vitro than both the FN modified surfaces and the negative control. Further, the Col II/rFN/Cad-11-MSCs composite stimulated cartilage formation in vivo; the chondrogenic effect of Col II alone was much less significant. These results suggested that the rFN/Cad-11-modified collagen type II biomimetic interface has dual biological functions of promoting adhesion and stimulating chondrogenic differentiation. This substance, thus, may serve as an ideal scaffold material for cartilage tissue engineering, enhancing repair of injured cartilage in vivo. PMID:23919505

  14. Study on the structural evolution of modified phenol formaldehyde resin adhesive for the high-temperature bonding of graphite

    NASA Astrophysics Data System (ADS)

    Wang, Jigang; Jiang, Nan; Guo, Quangui; Liu, Lang; Song, Jinren

    2006-01-01

    A novel adhesive for carbon materials composed of phenol-formaldehyde resin, boron carbide and fumed silica, was prepared. The adhesive property of graphite joints bonded by the above adhesive treated at high-temperatures was tested. Results showed that the adhesive was found to have outstanding high-temperature bonding properties for graphite. The adhesive structure was dense and uniform even after the graphite joints were heat-treated at 1500 °C. Bonding strength was 17.1 MPa. The evolution of adhesive structure was investigated. The results indicated that the addition of the secondary additive, fumed silica, improved the bonding performance greatly. Borosilicate phase with better stability was formed during the heat-treatment process, and the volume shrinkage was restrained effectively, which was responsible for the satisfactory high-temperature bonding performance of graphite.

  15. Use of cactus in mortars and concrete

    SciTech Connect

    Chandra, S.; Eklund, L.; Villarreal, R.R.

    1998-01-01

    Natural polymers have been used in ancient times to improve the durability of lime-based mortars and concretes. The natural polymers used were locally available. In this work, cactus extract from Mexico has been tested in a Portland cement mortar. It is seen that cactus extract increases the plasticity of the mortar and improves water absorption and freeze-salt resistance. Calcium hydroxide produced by Portland cement hydration interacts with the components of cactus extract, polysaccharides or proteins, and forms complexes. It affects the crystallization process. Painting of the concrete with this extract has also shown improved water resistance.

  16. Modeling and numerical simulation of interior ballistic processes in a 120mm mortar system

    NASA Astrophysics Data System (ADS)

    Acharya, Ragini

    by using a high-resolution Godunov-type shock-capturing approach was used where the discretization is done directly on the integral formulation of the conservation laws. A linearized approximate Riemann Solver was modified in this work for the two-phase flows to compute fully non-linear wave interactions and to directly provide upwinding properties in the scheme. An entropy fix based on Harten-Heyman method was used with van Leer flux limiter for total variation diminishing. The three dimensional effects were simulated by incorporating an unsplit multi-dimensional wave propagation method, which accounted for discontinuities traveling in both normal and oblique coordinate directions. For each component, the predicted pressure-time traces showed significant pressure wave phenomena, which closely simulated the measured pressure-time traces obtained at PSU. The pressure-time traces at the breech-end of the mortar tube were obtained at Aberdeen Test Center with 0, 2, and 4 charge increments. The 3D-MIB code was also used to simulate the effect of flash tube vent-hole pattern on the pressure-wave phenomenon in the ignition cartridge. A comparison of the pressure difference between primer-end and projectile-end locations of the original and modified ignition cartridges with each other showed that the early-phase pressure-wave phenomenon can be significantly reduced with the modified pattern. The flow property distributions predicted by the 3D-MIB for 0, 2, and 4 charge increment cases as well the projectile dynamics predictions provided adequate validation of theory by experiments.

  17. Five-year clinical evaluation of 300 teeth restored with porcelain laminate veneers using total-etch and a modified self-etch adhesive system.

    PubMed

    Aykor, Arzu; Ozel, Emre

    2009-01-01

    This study evaluated the long-term clinical performance of porcelain laminate veneers luted with hybrid composite in combination with total-etch and self-etch adhesive systems. The study was performed on 30 patients ranging in age between 28 and 54 years. Ten veneers were performed per patient in the maxillary arch. In Group 1, 150 teeth were treated with porcelain veneers, using a total-etch adhesive system (Scotchbond Multi-Purpose Plus, 3M ESPE). In Group 2, 150 teeth were bonded with a self-etch adhesive system (AdheSE, Ivoclar-Vivadent). All the veneers were luted with a light-cured hybrid composite (Z100, 3M ESPE). The patients were recalled after 1, 2 and 5 years. Modified United States Public Health Service (USPHS) criteria were utilized to evaluate the porcelain laminate veneers in terms of marginal adaptation, cavo-surface marginal discoloration, secondary caries, postoperative sensitivity, satisfaction with restoration shade and gingival tissue response. Data were analyzed using the Chi-Square test (p < 0.05). There was no statistically significant difference between the total-etch and self-etch groups in terms of USPHS criteria (p > 0.05). Porcelain veneers exhibited successful clinical performance with both total-etch and two-step self-etch adhesives at the end of five-years.

  18. Energy absorption at high strain rate of glass fiber reinforced mortars

    NASA Astrophysics Data System (ADS)

    Fenu, Luigi; Forni, Daniele; Cadoni, Ezio

    2015-09-01

    In this paper, the dynamic behaviour of cement mortars reinforced with glass fibers was studied. The influence of the addition of glass fibers on energy absorption and tensile strength at high strain-rate was investigated. Static tests in compression, in tension and in bending were first performed. Dynamic tests by means of a Modified Hopkinson Bar were then carried out in order to investigate how glass fibers affected energy absorption and tensile strength at high strain-rate of the fiber reinforced mortar. The Dynamic Increase Factor (DIF) was finally evaluated.

  19. Recycled sand in lime-based mortars.

    PubMed

    Stefanidou, M; Anastasiou, E; Georgiadis Filikas, K

    2014-12-01

    The increasing awareness of the society about safe guarding heritage buildings and at the same time protecting the environment promotes strategies of combining principles of restoration with environmentally friendly materials and techniques. Along these lines, an experimental program was carried out in order to investigate the possibility of producing repair, lime-based mortars used in historic buildings incorporating secondary materials. The alternative material tested was recycled fine aggregates originating from mixed construction and demolition waste. Extensive tests on the raw materials have been performed and mortar mixtures were produced using different binding systems with natural, standard and recycled sand in order to compare their mechanical, physical and microstructure properties. The study reveals the improved behavior of lime mortars, even at early ages, due to the reaction of lime with the Al and Si constituents of the fine recycled sand. The role of the recycled sand was more beneficial in lime mortars rather than the lime-pozzolan or lime-pozzolan-cement mortars as a decrease in their performance was recorded in the latter cases due to the mortars' structure.

  20. Systems toxicology-based assessment of the candidate modified risk tobacco product THS2.2 for the adhesion of monocytic cells to human coronary arterial endothelial cells.

    PubMed

    Poussin, Carine; Laurent, Alexandra; Peitsch, Manuel C; Hoeng, Julia; De Leon, Hector

    2016-01-02

    Alterations of endothelial adhesive properties by cigarette smoke (CS) can progressively favor the development of atherosclerosis which may cause cardiovascular disorders. Modified risk tobacco products (MRTPs) are tobacco products developed to reduce smoking-related risks. A systems biology/toxicology approach combined with a functional in vitro adhesion assay was used to assess the impact of a candidate heat-not-burn technology-based MRTP, Tobacco Heating System (THS) 2.2, on the adhesion of monocytic cells to human coronary arterial endothelial cells (HCAECs) compared with a reference cigarette (3R4F). HCAECs were treated for 4h with conditioned media of human monocytic Mono Mac 6 (MM6) cells preincubated with low or high concentrations of aqueous extracts from THS2.2 aerosol or 3R4F smoke for 2h (indirect treatment), unconditioned media (direct treatment), or fresh aqueous aerosol/smoke extracts (fresh direct treatment). Functional and molecular investigations revealed that aqueous 3R4F smoke extract promoted the adhesion of MM6 cells to HCAECs via distinct direct and indirect concentration-dependent mechanisms. Using the same approach, we identified significantly reduced effects of aqueous THS2.2 aerosol extract on MM6 cell-HCAEC adhesion, and reduced molecular changes in endothelial and monocytic cells. Ten- and 20-fold increased concentrations of aqueous THS2.2 aerosol extract were necessary to elicit similar effects to those measured with 3R4F in both fresh direct and indirect exposure modalities, respectively. Our systems toxicology study demonstrated reduced effects of an aqueous aerosol extract from the candidate MRTP, THS2.2, using the adhesion of monocytic cells to human coronary endothelial cells as a surrogate pathophysiologically relevant event in atherogenesis.

  1. Use of polypropylene fibers coated with nano-silica particles into a cementitious mortar

    SciTech Connect

    Coppola, B. Di Maio, L.; Scarfato, P.; Incarnato, L.

    2015-12-17

    Fiber reinforced cementitious composite (FRCC) materials have been widely used during last decades in order to overcome some of traditional cementitious materials issues: brittle behaviour, fire resistance, cover spalling, impact strength. For composite materials, fiber/matrix bond plays an important role because by increasing fiber/matrix interactions is possible to increase the behaviour of the entire material. In this study, in order to improve fiber to matrix adhesion, two chemical treatments of polypropylene fibers were investigated: alkaline hydrolysis and nano-silica sol-gel particles deposition. Treatmtents effect on fibers morphology and mechanical properties was investigated by scanning electron microscopy (SEM) and tensile tests. SEM investigations report the presence of spherical nano-silica particles on fiber surface, in the case of sol-gel process, while alkaline hydrolysis leads to an increase of fibers roughness. Both treatments have negligible influence on fibers mechanical properties confirming the possibility of their use in a cementitious mortar. Pullout tests were carried out considering three embedded length of fibers in mortar samples (10, 20 and 30 mm, respectively) showing an increase of pullout energy for treated fibers. The influence on fiber reinforced mortar mechanical properties was investigated by three-point flexural tests on prismatic specimens considering two fibers length (15 and 30 mm) and two fibers volume fractions (0.50 and 1.00 %). A general increase of flexural strength over the reference mix was achieved and an overall better behaviour is recognizable for mortars containing treated fibers.

  2. Use of polypropylene fibers coated with nano-silica particles into a cementitious mortar

    NASA Astrophysics Data System (ADS)

    Coppola, B.; Di Maio, L.; Scarfato, P.; Incarnato, L.

    2015-12-01

    Fiber reinforced cementitious composite (FRCC) materials have been widely used during last decades in order to overcome some of traditional cementitious materials issues: brittle behaviour, fire resistance, cover spalling, impact strength. For composite materials, fiber/matrix bond plays an important role because by increasing fiber/matrix interactions is possible to increase the behaviour of the entire material. In this study, in order to improve fiber to matrix adhesion, two chemical treatments of polypropylene fibers were investigated: alkaline hydrolysis and nano-silica sol-gel particles deposition. Treatmtents effect on fibers morphology and mechanical properties was investigated by scanning electron microscopy (SEM) and tensile tests. SEM investigations report the presence of spherical nano-silica particles on fiber surface, in the case of sol-gel process, while alkaline hydrolysis leads to an increase of fibers roughness. Both treatments have negligible influence on fibers mechanical properties confirming the possibility of their use in a cementitious mortar. Pullout tests were carried out considering three embedded length of fibers in mortar samples (10, 20 and 30 mm, respectively) showing an increase of pullout energy for treated fibers. The influence on fiber reinforced mortar mechanical properties was investigated by three-point flexural tests on prismatic specimens considering two fibers length (15 and 30 mm) and two fibers volume fractions (0.50 and 1.00 %). A general increase of flexural strength over the reference mix was achieved and an overall better behaviour is recognizable for mortars containing treated fibers.

  3. Enhancing the versatility of alternate current biosusceptometry (ACB) through the synthesis of a dextrose-modified tracer and a magnetic muco-adhesive cellulose gel.

    PubMed

    Martins, Murillo L; Calabresi, Marcos F; Quini, Caio; Matos, Juliana F; Miranda, José R A; Saeki, Margarida J; Bordallo, Heloisa N

    2015-03-01

    Alternate Current Biosusceptometry (ACB) is a promising bio-magnetic method, radiation free and easily performed used for gastric emptying exams. Due to development on its sensitivity level, interesting nature, noninvasiveness and low cost it has attracted a lot of attention. In this work, magnetic nanoparticles of Mn-Zn ferrite as well as dextrose-modified nanoparticles were synthesized to be used as possible tracers in ACB gastric emptying exams. In addition, a magnetic muco-adhesive gel was obtained by modifying the ferrite nanoparticles with cellulose. Based on in-vivo tests in rats, we show that the pure ferrite nanoparticles, whose isoelectric point was found to be at pH=3.2, present a great sensitivity to pH variations along the gastrointestinal tract, while the reduction of the isoelectric point by the dextrose modification leads to suitable nanoparticles for rapid gastric emptying examinations. On the other hand, the in-vivo tests show that the muco-adhesive cellulose gel presents substantial stomach adhesion and is a potential drug delivery system easily traceable by the ACB system.

  4. Characterization of historical mortars in Jordan

    NASA Astrophysics Data System (ADS)

    Gomez-Heras, M.; Arce, I.; Lopez-Arce, P.; Alvarez de Buergo, M.; Fort, R.

    2012-04-01

    This paper presents the petrographic and mineralogical characterization of mortars from different archaeological sites in Jordan which encompass Nabatean, Late-Antique and Early Islamic (Umayyad) sites, in some cases offering a sequence of different period mortars from the same building. These sites include the Nabataean city of Petra, the Late Antique town of Umm al Jimal and the castle of Qasr Al Hallabat. These mortars were produced with different raw materials and manufacturing technologies, which are reflected on distinctive variations of mineralogy, texture and crystal size and aggregates composition (including volcanic ashes, ceramic fragments, burnt organic material) size and their puzzolanic properties. As a consequence these mortars present different physical properties and reveal nowadays very different states of conservation. There is a dramatic change in mortar properties between those manufactured in pre-Islamic period and those from early Islamic - Ummayad times with a general trend in which these last ones present coarser crystal and aggregate sizes with less puzzolanic aggregates that result in less durable mortars. All of this reflects changes in the different stages of production of the mortar, from the use of either hydraulic, lime putty or slaked lime and the selection of aggregates to the application techniques (polishing). This reflects the evolution of building technology that took place in this area during early Islamic period and how petrological information can shed light on historical interpretation of building technologies. Research funded by AECID (PCI A/032184/10), GEOMATERIALES (S2009/MAT-16) and MCU (Analisis y Documentación de tipología arquitectónica y técnicas constructivas en el periodo de transición Bizantino-Omeya en Jordania)

  5. Mortar characterization study of unreinforced hollow clay tile masonry

    SciTech Connect

    Butala, M.B.

    1992-09-14

    This report presents the results of an investigation of mortar removed from existing hollow clay tile masonry walls in buildings located at the Oak Ridge Y-12 Plant. Primary purpose of this investigation was to evaluate the properties of existing mortar and provide a similar specification for the mortar to be used in construction of test specimens and test walls for the Hollow Clay Tile Wall Test Program. A mortar characterization study of mortar samples removed from walls in four buildings, 9207, 9206, 9204-2 and 9212 was performed by Testwell Craig Materials Consultants (TCMC) under subcontract to Martin Marietta Energy Systems, Inc (MMES). The mortar samples were collected by MMES and analyzed by TCMC in accordance with applicable ASTM standards. Petrographical and chemical analyses were performed. From the results of this investigation a mortar mix was prepared to resemble the properties of existing mortar.

  6. Immobilization of IFR salt wastes in mortar

    SciTech Connect

    Fischer, D.F.; Johnson, T.R.

    1988-01-01

    Portland cement-base mortars are being considered for immobilizing chloride salt wastes produced by the fuel cycles of Integral Fast Reactors (IFR). The IFR is a sodium-cooled fast reactor with metal alloy fuels. It has a close-coupled fuel cycle in which fission products are separated from the actinides in an electrochemical cell operating at 500/degree/C. This cell has a liquid cadmium anode in which the fuels are dissolved and a liquid salt electrolyte. The salt will be a mixture of either lithium, potassium, and sodium chlorides or lithium, calcium, barium, and sodium chlorides. One method being considered for immobilizing the treated nontransuranic salt waste is to disperse the salt in a portland cement-base mortar that will be sealed in corrosion-resistant containers. For this application, the grout must be sufficiently fluid that it can be pumped into canister-molds where it will solidify into a strong, leach-resistant material. The set times must be longer than a few hours to allow sufficient time for processing, and the mortar must reach a reasonable compressive strength (/approximately/7 MPa) within three days to permit handling. Because fission product heating will be high, about 0.6 W/kg for a mortar containing 10% waste salt, the effects of elevated temperatures during curing and storage on mortar properties must be considered.

  7. Extended interaction of β1 integrin subunit-deficient cells (GD25) with surfaces modified with fibronectin-derived peptides: culture optimization, adhesion and cytokine panel studies

    PubMed Central

    Waldeck, Heather; Kao, Weiyuan John

    2008-01-01

    The modification of biomaterials with extracellular matrix-mimicking factors to influence the cellular response through mainly integrin-mediated signaling is a common technique. The inherent limitations of antibody-inhibition studies necessitate the use of complementary methods to block integrin function to confirm cell–surface interaction. In this study, we employed a β1 integrin-deficient cell line, GD25, to investigate the role of β1 subunit in cell adhesion and subsequent cytokine (granulocyte macrophage colony stimulating factor, interleukin (IL)-1α, IL-1β, IL-6, granulocyte macrophage colony stimulating factor -1, regulated upon activation, normal T-cell expressed, and secreted, tumor necrosis factor-α) release kinetics in the presence of tissue culture polystyrene (TCPS) and semi-interpenetrating polymer networks (sIPN) modified with fibronectin (FN)-mimic peptides (RGD, PHSRN). Culture conditions (i.e. seeding density, medium, serum supplementation) were optimized for long-term observation. Differences in cell adhesion, cell viability and cytokine release behavior were dependent on the presence of the β1 integrin subunit, FN, sIPN cast method and peptide identity. By comparing two complementary techniques for assaying integrin function, we observed both similarities (i.e. decreased adhesion to FN-absorbed TCPS and increased IL-1β release at 96 h) and differences (i.e. no difference in adhesion or IL-1β release in the presence of sIPN surfaces) when the function of the β1 subunit was blocked in cell adhesion and signaling in the presence of biomaterials. PMID:18514047

  8. Interfacial nanoleakage and bonding of self-adhesive systems cured with a modified-layering technique to dentin of weakened roots.

    PubMed

    Mobarak, E; Seyam, R

    2013-01-01

    The purpose of the study was to evaluate the nanoleakage and bond strength of different self adhesive systems cured with a modified-layering technique (MLT) to dentin of weakened roots. Twenty-one maxillary incisors were decoronated and then root canals were instrumented and obturated with the cold lateral compaction technique. Weakened roots were simulated by flaring root canals until only 1 mm dentin thickness remained. Teeth were distributed into three groups. The canals were backfilled with Vertise Flow (VF group), a self-adhering system, following a modified-layering technique using two light-transmitting posts, sizes 6 and 3. DT Light Post size 2 was cemented using the same material. Remaining roots were prepared and cured in the same way as the VF group. However, in the TS/MF group, Clearfil Tri-S Bond (TS) adhesive and Clearfil Majesty Flow (MF) composite were used, while in the ED/PF group, ED primer II (ED)/Panavia F2.0 (PF) were used. After one week of storage, each root was sectioned to obtain six slices (two slices from each root third: coronal, middle and apical) of 0.9 ± 0.1 mm thickness. Interfacial nanoleakage expression was analyzed using a field emission scanning electron microscope (FEG-SEM), and the micro push-out bond strength (μPOBS) was measured at different root regions. Modes of failure were also determined using SEM. Data were statistically analyzed using two-way analysis of variance with repeated measures and Tukey post hoc test (p≤0.05). With MLT, all adhesive systems showed nanoleakage. For μPOBS, there was a statistically significant effect for adhesive systems (p<0.001) but not for root region (p<0.64) or for their interaction (p=0.99). Tukey post hoc test revealed that the bond strength of the VF group was significantly higher than the TS/MF and ED/PF groups for all root regions. All of the tested self-adhesive systems cured using MLT had slight nanoleakage and were not sensitive to root regional differences. Self

  9. 46. DETAIL VIEW OF THE MORTAR BOXES, STAMP BATTERIES AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    46. DETAIL VIEW OF THE MORTAR BOXES, STAMP BATTERIES AND AMALGAMATION TABLES. NOTE FULTON IRON WORKS, SAM FRANCISCO 1908 STAMPED INTO THE MORTAR BOX. ALSO NOTE THE DIES RESTING ON THE OUTSIDE OF THE MORTAR BOX BY THE SECOND STAMP BATTERY FROM THE CAMERA POSITION. - Standard Gold Mill, East of Bodie Creek, Northeast of Bodie, Bodie, Mono County, CA

  10. Wood : adhesives

    Treesearch

    A.H. Conner

    2001-01-01

    This chapter on wood adhesives includes: 1) Classification of wood adhesives 2) Thermosetting wood adhesives 3) Thermoplastic adhesives, 4) Wood adhesives based on natural sources 5) Nonconventional bonding of wood 6) Wood bonding.

  11. The Viking mortar - Design, development, and flight qualification.

    NASA Technical Reports Server (NTRS)

    Brecht, J. P.; Pleasants, J. E.; Mehring, R. D.

    1973-01-01

    Approximately 25,400 ft above the local surface of Mars, a radar height sensor fires the Viking mortar, which ejects a 53-ft D sub o disk-gap-band (DGB) parachute. The parachute decelerates and stabilizes the Viking lander sufficiently for the terminal engine system to take over and effect a soft landing. The general design and environmental requirements for the mortar system are presented; various illustrations of the mortar components and how the mortar system functions also are presented. Primary emphasis is placed on manufacturing, developing, and qualification testing of the mortar system.

  12. The Viking mortar - Design, development, and flight qualification.

    NASA Technical Reports Server (NTRS)

    Brecht, J. P.; Pleasants, J. E.; Mehring, R. D.

    1973-01-01

    Approximately 25,400 ft above the local surface of Mars, a radar height sensor fires the Viking mortar, which ejects a 53-ft D sub o disk-gap-band (DGB) parachute. The parachute decelerates and stabilizes the Viking lander sufficiently for the terminal engine system to take over and effect a soft landing. The general design and environmental requirements for the mortar system are presented; various illustrations of the mortar components and how the mortar system functions also are presented. Primary emphasis is placed on manufacturing, developing, and qualification testing of the mortar system.

  13. In vitro Evaluation of Stainless Steel Crowns cemented with Resin-modified Glass Ionomer and Two New Self-adhesive Resin Cements

    PubMed Central

    Shashibhushan, KK; Poornima, P; Reddy, VV Subba

    2016-01-01

    Aims To assess and compare the retentive strength of two dual-polymerized self-adhesive resin cements (RelyX U200, 3M ESPE & SmartCem2, Dentsply Caulk) and a resin-modified glass ionomer cement (RMGIC; RelyX Luting 2, 3M ESPE) on stainless steel crown (SSC). Materials and methods Thirty extracted teeth were mounted on cold cured acrylic resin blocks exposing the crown till the cemento-enamel junction. Pretrimmed, precontoured SSC was selected for a particular tooth. Standardized tooth preparation for SSC was performed by single operator. The crowns were then luted with either RelyX U200 or SmartCem2 or RelyX Luting 2 cement. Retentive strength was tested using Instron universal testing machine. The retentive strength values were recorded and calculated by the formula: Load/Area. Statistical analysis One-way analysis of variance was used for multiple comparisons followed by post hoc Tukey’s test for groupwise comparisons. Unpaired t-test was used for intergroup comparisons. Results RelyX U200 showed significantly higher retentive strength than rest of the two cements (p < 0.001). No significant difference was found between the retentive strength of SmartCem2 and RelyX Luting 2 (p > 0.05). Conclusion The retentive strength of dual-polymerized self-adhesive resin cements was better than RMGIC, and RelyX U200 significantly improved crown retention when compared with SmartCem2 and RelyX Luting 2. How to cite this article Pathak S, Shashibhushan KK, Poornima P, Reddy VVS. In vitro Evaluation of Stainless Steel Crowns cemented with Resin-modified Glass Ionomer and Two New Self-adhesive Resin Cements. Int J Clin Pediatr Dent 2016;9(3):197-200. PMID:27843249

  14. Marginal microleakage of resin-modified glass-ionomer and composite resin restorations: effect of using etch-and-rinse and self-etch adhesives.

    PubMed

    Khoroushi, Maryam; Karvandi, Tayebeh Mansouri; Kamali, Bentolhoda; Mazaheri, Hamid

    2012-01-01

    Previous studies have shown that dental adhesives increase the bond strength of resin-modified glass-ionomer (RMGI) restorative materials to dentin. This in vitro study has evaluated the effect of etch-and-rinse and self-etch bonding systems v/s cavity conditioner, and in comparison to similar composite resin restorations on maintaining the marginal sealing of RMGI restorations. 98 rectangular cavities (2.5×3×1.5 mm) were prepared on buccal and palatal aspects of 49 human maxillary premolars, randomly divided into 7 groups (N=14). The cavities in groups 1, 2 and 3 were restored using a composite resin (APX). The cavities in groups 4, 5, 6 and 7 were restored using a resin-modified glass-ionomer (Fuji II LC). Before restoring, adhesive systems (Optibond FL = OFL, three-step etch-and-rinse; One Step Plus = OSP, two-step etch-and-rinse; Clearfil Protect Bond = CPB, two-step self-etch) were used as bonding agents in groups 1-6 as follow: OFL in groups 1 and 4, OSP in groups 2 and 5, and CPB in groups 3 and 6, respectively. The specimens in group 7 were restored with GC cavity conditioner and Fuji II LC. All the specimens were thermo-cycled for 1000 cycles. Microleakage scores were determined using dye penetration method. Statistical analyzes were carried out with Kruskal-Wallis and Mann-Whitney U tests (α=0.05). There were significant differences in microleakage scores at both enamel and dentinal margins between the study groups (P<0.05). The lowest microleakage scores at enamel and dentin margins of RMGI restorations were observed in group 6. Use of two-step self-etch adhesive, prior to restoring cervical cavities with RMGIC, seems to be more efficacious than the conventional cavity conditioner in decreasing marginal microleakage.

  15. Use of Modified Polysaccharide 4DryField® PH for Adhesion Prevention and Hemostasis in Gynecological Surgery: A Two-Center Observational Study by Second-Look Laparoscopy

    PubMed Central

    Korell, Matthias; Ziegler, Nicole; De Wilde, Rudy Leon

    2016-01-01

    Purpose. This study evaluates both scopes of 4DryField PH, certified for adhesion prevention and hemostasis, in patients undergoing surgery for various and severe gynecological disorders. Methods. This is a two-institutional study. Adhesion prevention efficacy was evaluated using video documentation of first-look laparoscopies (FLL) and second-look laparoscopies (SLL); other patient data were analyzed retrospectively. Twenty patients with various disorders were evaluated, 4 assigned to a uterus pathology, 10 to endometriosis, and 6 to an adhesion disease group. Nine patients received 4DryField primarily for hemostasis and 11 solely for adhesion prevention. Nineteen patients had SLL after 5 to 12 weeks and one after 13 months. Results. At FLL with 4DryField, immediate hemostasis could be achieved in diffuse bleeding. At SLL, effective adhesion prevention was observed in 18 of all 20 women, with only 2 revealing major adhesions. In particular, only 1 of the 6 women with adhesion disease as predominant disorder showed major adhesions at SLL. Conclusions. Modified polysaccharide 4DryField is not only effective in diffuse bleeding. In this cohort with extensive surgery for various gynecological pathologies, 4DryField showed effective adhesion prevention as confirmed at SLL, too. Its use as premixed gel is a convenient variant for treatment of large peritoneal wounds. PMID:26904672

  16. ASR potential of quartz based on expansion values and microscopic characteristics of mortar bars

    NASA Astrophysics Data System (ADS)

    Stastna, Aneta; Sachlova, Sarka; Kuchynova, Marketa; Pertold, Zdenek; Prikryl, Richard

    2016-04-01

    The alkali-silica reaction (ASR) is one of the most damaging factors for concrete structures. Different analytical techniques are used to quantify ASR potential of aggregates. The accelerated mortar bar test (ASTM C1260) in combination with the petrographic examination of aggregates by microscopic techniques belongs to the frequently employed methods. Such a methodical approach enables quantification of the ASR potential, based on the expansion values of accelerated mortar bars; and also to identify deleterious components in aggregates. In this study, the accelerated mortar bar test (ASTM C1260) was modified and combined with the scanning electron microscopy of polished sections prepared from mortar bars. The standard 14-day test period of mortar bars was prolonged to 1-year. ASR potential of aggregates was assessed based on expansion values (both 14-day and 1-year) of mortar bars and microscopic analysis of ASR products (alkali silica gels, microcracks, dissolution gaps) detected in the sections. Different varieties of quartz-rich rocks including chert, quartz meta-greywacke, three types of quartzite and pegmatite were used as aggregate. Only quartz from pegmatite was assessed to be non reactive (14-day expansion of 0.08%, 1-year expansion of 1.25%). Aggregate sections exhibited minor ASR products even after 1-year of mortar bar immersion in 1 M NaOH. Expansion values of the rest of samples exceeded the limit of 0.10% after 14-day test period indicating aggregates as reactive. The highest ASR potential was detected in mortar bars containing chert (14-day expansion of 0.55%, 1-year expansion of 2.70%) and quartz meta-greywacke (14-day expansion of 0.46%, 1-year expansion of 2.41%). The high ASR potential was explained by presence of cryptocrystalline matrix in significant volumes (24 - 65 vol%). Influence of the lengths of the immersion in the alkaline solution was observed mainly in the microstructure of the cement paste and on the extension of ASR products. The

  17. Measuring the colour of rendering mortars

    NASA Astrophysics Data System (ADS)

    Govaerts, Yves; Meulebroeck, Wendy; Verdonck, Ann; de Bouw, Michael

    2014-05-01

    When restoring decorative mortar layers on historic façades, professionals need to determine the colour of these finishes in order to select an appropriate repair mortar. Currently, the appearance of these renders is only assessed from a subjective point of view. To match with the aesthetic aspects of the façade, contractors must constantly adjust their repair mortar composition to avoid a patchwork of different colours, which is detrimental for heritage. This time-consuming (trial-and-error) methodology can be excluded by evaluating `colour' with an objective numerical approach. The challenge of the research was to define and evaluate optimal material dependent boundary conditions for measuring the colour of nonhomogeneous mortars. Four samples with different scale of heterogeneity were measured by two spectrocolorimeters, both with a diffuse illumination geometry. The results were plotted in CIE-L*a*b* colour space. By calculating the colour difference (ΔE*), the influence of measuring with or without specular component was evaluated. We discovered the minimal number of measuring points depends on the scale of heterogeneity and the aperture area. The less homogeneous the mortar sample is and the smaller the aperture area, the more unique measuring points are required. Therefore, it is recommended to choose an aperture head of 25 mm or more to reduce the number of measurements, making your work time-efficient. However, in order to obtain accurate measurements on site, a portable optical spectrum analyser can be used with a 6 mm-diameter aperture, a viewing angle of 10°, SCI mode, illumination source D65, considering a minimum of 15 unique measuring points.

  18. Congeneric bio-adhesive mussel foot proteins designed by modified prolines revealed a chiral bias in unnatural translation.

    PubMed

    Larregola, Maud; Moore, Shannon; Budisa, Nediljko

    2012-05-18

    Chiral bias in the unnatural translation and 'sticky' mussel proteins. The residue-specific in vivo incorporation of hydroxylated amino acids as well as other synthetic analogs, such as fluoroprolines, emerges as the method of choice for recombinant synthesis of Pro-rich mussel adhesive protein congeners. Chemical diversifications introduced in this way provide a general route towards bio-adhesive congeners endowed with properties not developed by natural evolution. Most importantly, we have found that the co-translational incorporation of (4R)-, and (4S)-hyroxylated and fluorinated analogs into mussel proteins presented a chiral bias: the expressed protein was only detectable in samples incubated with analogs with (4R)-substituents. Possible relationship of these stereochemical preferences for (4R)-stereoisomers in the translation to intracellular tRNA concentrations, ribosomal editing and proofreading or structural effects such as preorganization remains to be addressed in future studies. These studies will generally provide a mechanistic framework for the flexibility of the translational machinery and establish the boundaries of the unnatural translation.

  19. Abdominal Adhesions

    MedlinePlus

    ... Syndrome The Digestive System & How it Works Abdominal Adhesions What are abdominal adhesions? Abdominal adhesions are bands of fibrous tissue that ... or stool through the intestines. What causes abdominal adhesions? Abdominal surgery is the most frequent cause of ...

  20. Effect of resin-modified glass-ionomer cement lining and composite layering technique on the adhesive interface of lateral wall

    PubMed Central

    AZEVEDO, Larissa Marinho; CASAS-APAYCO, Leslie Carol; VILLAVICENCIO ESPINOZA, Carlos Andres; WANG, Linda; NAVARRO, Maria Fidela de Lima; ATTA, Maria Teresa

    2015-01-01

    Interface integrity can be maintained by setting the composite in a layering technique and using liners. Objective The aim of this in vitro study was to verify the effect of resin-modified glass-ionomer cement (RMGIC) lining and composite layering technique on the bond strength of the dentin/resin adhesive interface of lateral walls of occlusal restorations. Material and Methods Occlusal cavities were prepared in 52 extracted sound human molars, randomly assigned into 4 groups: Group 2H (control) – no lining + two horizontal layers; Group 4O: no lining + four oblique layers; Group V-2H: RMGIC lining (Vitrebond) + two horizontal layers; and Group V-4O: RMGIC lining (Vitrebond) + four oblique layers. Resin composite (Filtek Z250, 3M ESPE) was placed after application of an adhesive system (Adper™ Single Bond 2, 3M ESPE) dyed with a fluorescent reagent (Rhodamine B) to allow confocal microscopy analysis. The teeth were stored in deionized water at 37oC for 24 hours before being sectioned into 0.8 mm slices. One slice of each tooth was randomly selected for Confocal Laser Scanning Microscopy (CLSM) analysis. The other slices were sectioned into 0.8 mm x 0.8 mm sticks to microtensile bond strength test (MPa). Data were analyzed by two-way ANOVA and Fisher’s test. Results There was no statistical difference on bond strength among groups (p>0.05). CLSM analysis showed no significant statistical difference regarding the presence of gap at the interface dentin/resin among groups. Conclusions RMGIC lining and composite layering techniques showed no effect on the microtensile bond strength and gap formation at the adhesive interface of lateral walls of high C-factor occlusal restorations. PMID:26221927

  1. Adhesive interactions with wood

    Treesearch

    Charles R. Frihart

    2004-01-01

    While the chemistry for the polymerization of wood adhesives has been studied systematically and extensively, the critical aspects of the interaction of adhesives with wood are less clearly understood. General theories of bond formation need to be modified to take into account the porosity of wood and the ability of chemicals to be absorbed into the cell wall....

  2. Development of low weight self-levelling mortars

    NASA Astrophysics Data System (ADS)

    Padilla, A.; Panama, I.; Toledo, A.; Flores, A.

    2015-01-01

    This work shows the development of self levelling mortars, using micro bubbles based on aluminium silicate with a density of 0.25 g/cm3. Mortars formulations are composed by 8 different components in order to achieve properties balance between fresh and solid state. The mean objective is development light weight mortars with high fluidity and compression strength using micro bubbles and some additives. Formulations were designed employing Taguchi DOE of 8 variables and 3 states. Result analysis according to Taguchi method lets indentify the preponderant effect of each variable on the cited properties. Several formulations reached fluidity higher than 250%, with compression strength around 100 kg/cm2 and a low volumetric weigh. Obtained volumetric weights are 20% less than commercial self levelling mortars weight. Finally some relations are presented such: as relation water/cement with fluidity, and micro bubble content versus mortars volumetric weight, and finally compression strength versus the volumetric weight of mortars.

  3. CAD/CAM monolithic restorations and full-mouth adhesive rehabilitation to restore a patient with a past history of bulimia: the modified three-step technique.

    PubMed

    Vailati, Francesca; Carciofo, Sylvain

    2016-01-01

    Due to an increasing awareness about dental erosion, many clinicians would like to propose treatments even at the initial stages of the disease. However, when the loss of tooth structure is visible only to the professional eye, and it has not affected the esthetics of the smile, affected patients do not usually accept a full-mouth rehabilitation. Reducing the cost of the therapy, simplifying the clinical steps, and proposing noninvasive adhesive techniques may promote patient acceptance. In this article, the treatment of an ex-bulimic patient is illustrated. A modified approach of the three-step technique was followed. The patient completed the therapy in five short visits, including the initial one. No tooth preparation was required, no anesthesia was delivered, and the overall (clinical and laboratory) costs were kept low. At the end of the treatment, the patient was very satisfied from a biologic and functional point of view.

  4. Tissue-engineered endothelial cell layers on surface-modified Ti for inhibiting in vitro platelet adhesion

    NASA Astrophysics Data System (ADS)

    Wang, Xiupeng; He, Fupo; Li, Xia; Ito, Atsuo; Sogo, Yu; Maruyama, Osamu; Kosaka, Ryo; Ye, Jiandong

    2013-06-01

    A tissue-engineered endothelial layer was prepared by culturing endothelial cells on a fibroblast growth factor-2 (FGF-2)-l-ascorbic acid phosphate magnesium salt n-hydrate (AsMg)-apatite (Ap) coated titanium plate. The FGF-2-AsMg-Ap coated Ti plate was prepared by immersing a Ti plate in supersaturated calcium phosphate solutions supplemented with FGF-2 and AsMg. The FGF-2-AsMg-Ap layer on the Ti plate accelerated proliferation of human umbilical vein endothelial cells (HUVECs), and showed slightly higher, but not statistically significant, nitric oxide release from HUVECs than on as-prepared Ti. The endothelial layer maintained proper function of the endothelial cells and markedly inhibited in vitro platelet adhesion. The tissue-engineered endothelial layer formed on the FGF-2-AsMg-Ap layer is promising for ameliorating platelet activation and thrombus formation on cardiovascular implants.

  5. Sulfate and acid resistant concrete and mortar

    DOEpatents

    Liskowitz, J.W.; Wecharatana, M.; Jaturapitakkul, C.; Cerkanowicz, A.E.

    1998-06-30

    The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction and other applications, which hardenable mixtures demonstrate significant levels of acid and sulfate resistance while maintaining acceptable compressive strength properties. The acid and sulfate hardenable mixtures of the invention containing fly ash comprise cementitious materials and a fine aggregate. The cementitous materials may comprise fly ash as well as cement. The fine aggregate may comprise fly ash as well as sand. The total amount of fly ash in the hardenable mixture ranges from about 60% to about 120% of the total amount of cement, by weight, whether the fly ash is included as a cementious material, fine aggregate, or an additive, or any combination of the foregoing. In specific examples, mortar containing 50% fly ash and 50% cement in cementitious materials demonstrated superior properties of corrosion resistance. 6 figs.

  6. Sulfate and acid resistant concrete and mortar

    DOEpatents

    Liskowitz, John W.; Wecharatana, Methi; Jaturapitakkul, Chai; Cerkanowicz, deceased, Anthony E.

    1998-01-01

    The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction and other applications, which hardenable mixtures demonstrate significant levels of acid and sulfate resistance while maintaining acceptable compressive strength properties. The acid and sulfate hardenable mixtures of the invention containing fly ash comprise cementitious materials and a fine aggregate. The cementitous materials may comprise fly ash as well as cement. The fine aggregate may comprise fly ash as well as sand. The total amount of fly ash in the hardenable mixture ranges from about 60% to about 120% of the total amount of cement, by weight, whether the fly ash is included as a cementious material, fine aggregate, or an additive, or any combination of the foregoing. In specific examples, mortar containing 50% fly ash and 50% cement in cementitious materials demonstrated superior properties of corrosion resistance.

  7. Wood adhesion and adhesives

    Treesearch

    Charles R. Frihart

    2005-01-01

    An appreciation of rheology, material science, organic chemistry, polymer science, and mechanics leads to better understanding of the factors controlling the performance of the bonded assemblies. Given the complexity of wood as a substrate, it is hard to understand why some wood adhesives work better than other wood adhesives, especially when under the more severe...

  8. Reliability Estimates for Flawed Mortar Projectile Bodies

    DTIC Science & Technology

    2009-12-01

    Monte Carlo simulations were used to estimate reliability. Measured distributions of wall thickness, defect rate, material strength, and applied loads...element analysis Case study Monte Carlo simulation a b s t r a c t The Army routinely screens mortar projectiles for defects in safety-critical parts. In...of a safety-critical failure. Limit state functions and Monte Carlo simulations were used to estimate reliability. Measured distributions of wall

  9. Laboratory Characterization of Type N Mortar

    DTIC Science & Technology

    2009-03-01

    All of these velocity determinations were made under atmospheric conditions, i.e., no prestress of any kind was applied to the specimens. The tests...Cell Instrumentation Stand Concrete Sample To perform a RTE test, a static high-pressure triaxial test (HPTX) device (Figure 2) was used. This device...satura- tion. Materials such as concrete and mortar can continue to gain strength with increasing pressure until all of the air porosity in the

  10. Smart multifunctional cement mortar containing graphite nanoplatelet

    NASA Astrophysics Data System (ADS)

    Du, Hongjian; Quek, Ser Tong; Pang, Sze Dai

    2013-04-01

    The piezoresistivity-based strain sensing ability of cementitious composites containing graphite nanoplatelet (GNP) is investigated in this paper. GNP offers the advantages of ease of processing, excellent mechanical and electrical properties at a very low cost compared to carbon nanotubes and carbon nano-fibers. Cement mortar with 0%, 1.2%, 2.4%, 3.6% and 4.8% of GNP (by volume of composite) were cast. The electrical resistance of the specimens was measured by both the two- and four-probe methods using direct current (DC). The effect of polarization was characterized and the percolation threshold was experimentally found to be between 2.4% and 3.6% of GNP based on both accelerated and normal drying specimens. The assumption of Ohmic material was tested with varying current and found to be valid for current < 0.01mA and 0.5mA for four- and two-probe methods respectively. The piezoresistive effect was demonstrated by comparing the gage factors of mortars with GNP vs plain mortar under cyclic loading in compression at 3 strain levels. At low strains, the high gage factor is believed to stem from both the effect of the imperfect interfaces around the GNP and the piezoresistivity of the GNP; at higher strains, the gage factor is likely to be attributed to the piezoresistivity of the GNP and it is still 1-2 orders of magnitude larger than the gage factor arising from geometric changes.

  11. Biomimetic modified clinical-grade POSS-PCU nanocomposite polymer for bypass graft applications: a preliminary assessment of endothelial cell adhesion and haemocompatibility.

    PubMed

    Solouk, Atefeh; Cousins, Brian G; Mirahmadi, Fereshteh; Mirzadeh, Hamid; Nadoushan, Mohammad Reza Jalali; Shokrgozar, Mohammad Ali; Seifalian, Alexander M

    2015-01-01

    To date, there are no small internal diameter (<5mm) vascular grafts that are FDA approved for clinical use due to high failure rates from thrombosis and unwanted cell proliferation. The ideal conditions to enhance bioengineered grafts would be the blood contacting lumen of the bypass graft fully covered by endothelial cells (ECs). As a strategy towards this aim, we hypothesized that by immobilising biomolecules on the surface of the polyhedral oligomeric silsesquioxane-poly(carbonate-urea)urethane (POSS-PCU) nanocomposite polymers, which contain binding sites and ligands for cell surface receptors similar to extracellular matrix (ECM) will positively influence the attachment and proliferation of ECs. Since, the surface of POSS-PCU is inert and not directly suitable for immobilisation of biomolecules, plasma graft polymerisation is a suitable method to modify the surface properties ready for immobilisation and biofunctionalisation. POSS-PCU was activated by plasma treatment in air/O2 to from hydroperoxides (-OH, -OOH), and then carboxylated via plasma polymerisation of a 30% acrylic acid solution (Poly-AA) using a two-step plasma treatment (TSPT) process. Collagen type I, a major component of ECM, was covalently immobilised to mimic the ECM structures to ECs (5mg/ml) using a two-step chemical reaction using EDC chemistry. Successful immobilisation of poly-AA and collagen on to the nanocomposites was confirmed using Toluidine Blue staining and the Bradford assay. Un-treated POSS-PCU served as a simple control. The impact of collagen grafting on the physical, mechanical and biological properties of POSS-PCU was evaluated via contact angle (θ) measurements, scanning electron microscopy (SEM), atomic force microscopy (AFM), dynamic mechanical thermal analysis (DMTA), ECs adhesion and proliferation followed by platelet adhesion and haemolysis ratio (HR) tests. Poly-AA content on each of the plasma treated nanocomposite films increased on Low, Med and High samples due

  12. Quick chip assay using locked nucleic acid modified epithelial cell adhesion molecule and nucleolin aptamers for the capture of circulating tumor cells

    PubMed Central

    Maremanda, Nihal G.; Roy, Kislay; Kanwar, Rupinder K.; Shyamsundar, Vidyarani; Ramshankar, Vijayalakshmi; Krishnamurthy, Arvind; Krishnakumar, Subramanian; Kanwar, Jagat R.

    2015-01-01

    The role of circulating tumor cells (CTCs) in disease diagnosis, prognosis, monitoring of the therapeutic efficacy, and clinical decision making is immense and has attracted tremendous focus in the last decade. We designed and fabricated simple, flat channel microfluidic devices polydimethylsiloxane (PDMS based) functionalized with locked nucleic acid (LNA) modified aptamers (targeting epithelial cell adhesion molecule (EpCAM) and nucleolin expression) for quick and efficient capture of CTCs and cancer cells. With optimized flow rates (10 μl/min), it was revealed that the aptamer modified devices offered reusability for up to six times while retaining optimal capture efficiency (>90%) and specificity. High capture sensitivity (92%) and specificity (100%) was observed in whole blood samples spiked with Caco-2 cells (10–100 cells/ml). Analysis of blood samples obtained from 25 head and neck cancer patients on the EpCAM LNA aptamer functionalized chip revealed that an average count of 5 ± 3 CTCs/ml of blood were captured from 22/25 samples (88%). EpCAM intracellular domain (EpICD) immunohistochemistry on 9 oral squamous cell carcinomas showed the EpICD positivity in the tumor cells, confirming the EpCAM expression in CTCs from head and neck cancers. These microfluidic devices also maintained viability for in vitro culture and characterization. Use of LNA modified aptamers provided added benefits in terms of cost effectiveness due to increased reusability and sustainability of the devices. Our results present a robust, quick, and efficient CTC capture platform with the use of simple PDMS based devices that are easy to fabricate at low cost and have an immense potential in cancer diagnosis, prognosis, and therapeutic planning. PMID:26487896

  13. Synthesis and characterization of biodegradable cationic poly(propylene fumarate-co-ethylene glycol) copolymer hydrogels modified with agmatine for enhanced cell adhesion.

    PubMed

    Tanahashi, Kazuhiro; Jo, Seongbong; Mikos, Antonios G

    2002-01-01

    We synthesized positively charged biodegradable hydrogels by cross-linking of agmatine-modified poly(ethylene glycol)-tethered fumarate (Agm-PEGF) and poly(propylene fumarate-co-ethylene glycol) (P(PF-co-EG)) to investigate the effect of the guanidino groups of the agmatine on hydrogel swelling behavior and smooth muscle cell adhesion to the hydrogels. The weight swelling ratio of these hydrogels at pH 7.0 increased from 279 +/- 4 to 306 +/- 7% as the initial Agm-PEGF content increased from 0 to 200 mg/g of P(PF-co-EG), respectively. The diffusional exponents, n, during the initial phase of water uptake were independent of the initial Agm-PEGF content and were determined to be 0.66 +/- 0.08, 0.71 +/- 0.07, and 0.60 +/- 0.05 for respective initial Agm-PEGF contents of 0, 100, and 200 mg/g. The heat of fusion of water present in the hydrogels increased from 214 +/- 11 to 254 +/- 4 J/g as the initial Agm-PEGF content increased from 0 to 200 mg/g. The number of adherent smooth muscle cells increased dose-dependently from 15 +/- 6 to 75 +/- 7% of the initial seeding density as the initial Agm-PEGF content increased from 0 to 200 mg/g. These results suggest that the incorporation of the guanidino groups of agmatine into P(PF-co-EG) hydrogels increases the hydrogel free water content and the total water content of the hydrogels and also enhances cell adhesion to the hydrogels.

  14. Combination of a self-etching adhesive and a resin-modified glass ionomer: effect of water and saliva contamination on bond strength to dentin.

    PubMed

    Dursun, Elisabeth; Attal, Jean-Pierre

    2011-10-01

    Because studies have shown that adherence to dentin of resin-modified glass ionomers (RMGI) can be improved by surface treatment with a self-etching adhesive (SEA), the purpose of this in vitro study was to evaluate the water and saliva tolerance of this combination before and after application of SEA. Seventy cylinders of an RMGI (Fuji II LC) were bonded to the dentin of human teeth: 10 without any surface treatment, 10 after polyalkenoic acid conditioning, 10 after application of SEA, 10 after application of SEA on water contaminated dentin, 10 after application of SEA on saliva contaminated dentin, 10 on water contaminated light-cured SEA, and 10 on saliva contaminated light-cured SEA. The shear bond strength (SBS) was determined in a universal testing machine and the site of bond failure recorded. A Kruskal-Wallis test was performed followed by Games-Howell post-hoc pairwise comparison tests on the SBS results (p < 0.05), and a chi-square test was used for the fractographic analysis (p < 0.05). The lowest SBS was obtained without conditioning (5 ± 1 MPa). Polyalkenoic acid improved SBS (8 ± 2 MPa) and SEA increased it very significantly (15 ± 2 MPa), even in the case of water contamination (16 ± 2 MPa before application of SEA, 21 ± 4 MPa after application of SEA), or saliva contamination (20 ± 7 MPa before application of SEA, 19 ± 6 MPa after application of SEA). The group bonded without conditioning resulted in only adhesive fractures, showing a statistically significant difference from the other groups. SEA in association with the Fuji II LC RMGI increased the SBS very significantly, even in the case of water or saliva contamination.

  15. Effects of additional nanosilica of compressive strength on mortar

    NASA Astrophysics Data System (ADS)

    Retno Setiati, N.

    2017-07-01

    The use of nanosilica as one of the innovations in concrete technology has developed very rapidly. Some research mentioned that nanosilica obtained from the synthesis process silica sand is a type of material that is as pozolan when added to the concrete mix, so as to accelerate the hydration process in concrete. With the addition of nanosilica into the concrete mix, the compressive strength of the concrete can be increased and it has a high durability. This study aims to determine the effect from the addition of nanosilica on mechanical properties of concrete. Laboratory testing is conducted by making the mortar test specimen size of 50 mm x 50 mm x 50 mm. The material used is composed of silica sand, nanosilica, gravel, superplasticizer, cement, and water. Nanosilica percentage amount is added as much as 5, 10, and 15% by weight of cement. Testing of mechanical properties such as compressive strength mortar done at age 3, 7, 14, and 28 days. Based on the analysis and discussion obtained that at 28 days, mortar with the addition of 5% and 15% nanosilica has the compressive strength of 23 MPa. Addition nanosilika into the mortar to improve the mechanical properties by increasing the compressive strength of mortar. The compressive strength of mortar with the addition of 10% nanosilica is 19 MPa. The increase in compressive strength of mortar with the addition of 5% and 15% nano silica is 21% larger than the mortar with the addition of 10% nanosilica and without nanosilica. Nanosilica addition of more than 10% can cause agglomeration when mixed into the mortar so that the impact on the compressive strength of mortar.

  16. Biocompatible Adhesives

    DTIC Science & Technology

    1991-03-01

    pressure sensitive elastomer, polyisobutylene. with water soluble adhesives such as carboxy methyl ceiiulose, pectin and gelatin for adhesion to... cellulose and nylon films, were most often used in 180 peel adhesion tests on the adhesives. Films were cast on one substrate and the other was moistened...irritation. 4. Peel adhesion to hydrated cellulose , nylon and cotton cloth substrates was satisfactory. So too was the peel adhesion as a function of

  17. Epithelial cell adhesion molecule independent capture of non-small lung carcinoma cells with peptide modified microfluidic chip.

    PubMed

    Pu, Kefeng; Li, Chunlin; Zhang, Nengpan; Wang, Hui; Shen, Wenjiang; Zhu, Yimin

    2017-03-15

    Circulating tumor cells (CTCs) present in the blood of patients with non-hematological cancers are accessible sources for diagnosis and monitoring of cancers. By the aid of the ability of the anti-EpCAM antibody to recognize the epithelial cells, microsystem-based technologies provide robust means for effectively detecting CTCs in vitro. Considering the EpCAM expression is down-regulated during epithelial-mesenchymal transition (EMT) process, the amount of CTCs detected based on anti-EpCAM antibody is underestimated. In our study, the A549 cells targeting peptide (A-1 peptide), as the substitute of anti-EpCAM antibody, was introduced to microfluidic chip to capture A549 cells. Our results showed that both epithelial-like and mesenchymal-like A549 cells could efficiently be captured by the A-1 peptide modified microfluidic chip, and the capture efficiency for epithelial-like cells is comparable to that captured by the EpCAM antibody. Thus, we concluded that the peptide could be a better supplement to the EpCAM antibody for capturing CTCs in microfluidic system with broader spectrum.

  18. Effect of Rebonding on the Bond Strength of Orthodontic Tubes: A Comparison of Light Cure Adhesive and Resin-Modified Glass Ionomer Cement In Vitro

    PubMed Central

    Aleksiejunaite, Monika; Sidlauskas, Antanas

    2017-01-01

    The purpose of this study was to determine the impact of different enamel preparation procedures and compare light cure composite (LCC) and resin-modified glass ionomer (RMGI) on the bond strength of orthodontic metal tubes rebonded to the enamel. Twenty human molars were divided into two groups (n = 10). Tubes were bonded using LCC (Transbond XT) in group 1 and RMGI (Fuji Ortho LC) in group 2. The tubes in each group were bonded following manufacturers' instructions (experiment I) and then debonded using testing machine. Then, the same brackets were sandblasted and rebonded twice. Before the first rebonding, the enamel was cleaned using carbide bur (experiment II) and before second rebonding, it was cleaned using carbide bur and soda blasted (experiment III). Mann–Whitney and Wilcoxon signed-rank tests showed no significant difference between RMGI and LCC bond strengths in case of normal bonding and rebonding, when enamel was cleaned using carbide bur before rebonding. Enamel soda blasting before rebonding significantly increased RMGI tensile bond strength value compared to LLC (p < 0.05). LCC and RMGI (especially RMGI) provide sufficient bond strengths for rebonding of molar tubes, when residual adhesive from previous bonding is removed and enamel soda blasted. PMID:28386279

  19. TCam-2 Seminoma Cells Exposed to Egg-Derived Microenvironment Modify Their Shape, Adhesive Pattern and Migratory Behaviour: A Molecular and Morphometric Analysis

    PubMed Central

    Ferranti, Francesca; D’Anselmi, Fabrizio; Caruso, Maria; Lei, Vittorio; Dinicola, Simona; Pasqualato, Alessia; Cucina, Alessandra; Palombo, Alessandro; Ricci, Giulia; Catizone, Angela; Bizzarri, Mariano

    2013-01-01

    Seminoma is one of the most common Testicular Germ Cell Tumours that originates during embryonic development due to an alteration of the local niche that in turn results in a delayed or blocked differentiation of Primordial Germ Cells. The block of differentiation is actually a common way to develop cancer disease as postulated by the "embryonic rest theory of cancer". In agreement with this theory different studies have demonstrated that embryonic cues display the capacity of reprogramming aggressive cancer cells towards a less aggressive phenotype. Herein we investigate the ability of a culture medium added with 10% egg albumen (EW, Egg White) to modulate seminoma cell phenotype and behaviour, by ensuring a proper set of morphogenetic signals. We chose to use the TCam-2 seminoma cell line that has been established as the only available cell line, obtained from a primary testicular seminoma. EW is able to: 1) modify TCam-2 cell spreading rate and cell-substrate adhesion without affecting proliferation and survival indexes; 2) modulate TCam-2 actin distribution pattern increasing cortical localization of actin filaments; 3) increase TCam-2 cell-cell junction capability; 4) decrease both chemo-sensitive and collective TCam-2 migratory behaviour. According to these observations morphometric fractal analysis revealed the ability of EW to increase Circularity and Solidity parameters and, consequently, to decrease Fractal dimension. Prompted by these observations we hypothesize that EW treatment could rescue, at least in part, the neoplastic-metastatic behaviour of seminoma cells. PMID:24098438

  20. TCam-2 seminoma cells exposed to egg-derived microenvironment modify their shape, adhesive pattern and migratory behaviour: a molecular and morphometric analysis.

    PubMed

    Ferranti, Francesca; D'Anselmi, Fabrizio; Caruso, Maria; Lei, Vittorio; Dinicola, Simona; Pasqualato, Alessia; Cucina, Alessandra; Palombo, Alessandro; Ricci, Giulia; Catizone, Angela; Bizzarri, Mariano

    2013-01-01

    Seminoma is one of the most common Testicular Germ Cell Tumours that originates during embryonic development due to an alteration of the local niche that in turn results in a delayed or blocked differentiation of Primordial Germ Cells. The block of differentiation is actually a common way to develop cancer disease as postulated by the "embryonic rest theory of cancer". In agreement with this theory different studies have demonstrated that embryonic cues display the capacity of reprogramming aggressive cancer cells towards a less aggressive phenotype. Herein we investigate the ability of a culture medium added with 10% egg albumen (EW, Egg White) to modulate seminoma cell phenotype and behaviour, by ensuring a proper set of morphogenetic signals. We chose to use the TCam-2 seminoma cell line that has been established as the only available cell line, obtained from a primary testicular seminoma. EW is able to: 1) modify TCam-2 cell spreading rate and cell-substrate adhesion without affecting proliferation and survival indexes; 2) modulate TCam-2 actin distribution pattern increasing cortical localization of actin filaments; 3) increase TCam-2 cell-cell junction capability; 4) decrease both chemo-sensitive and collective TCam-2 migratory behaviour. According to these observations morphometric fractal analysis revealed the ability of EW to increase Circularity and Solidity parameters and, consequently, to decrease Fractal dimension. Prompted by these observations we hypothesize that EW treatment could rescue, at least in part, the neoplastic-metastatic behaviour of seminoma cells.

  1. Changes in focal adhesion kinase expression in rats with collagen-induced arthritis and efficacy of intervention with disease modifying anti-rheumatic drugs alone or in combination.

    PubMed

    Gao, Hui-Ying; Luo, Jing; Li, Xiao-Feng; Lv, Qian; Wen, Hong-Yan; Song, Qing-Zhen; Zhao, Wen-Peng; Zhao, Xiang-Cong; Zhang, Ting-Ting; Zhang, Si-Yu; Zhi, Jian-Ming

    2015-01-01

    Focal adhesion kinase (FAK) is known to promote the proliferation, migration and survival of synovial cells and plays an important role in the occurrence, development and pathological process of rheumatoid arthritis (RA). The aim of the present study was to observe FAK changes in synovial cells of rats with collagen-induced arthritis (CIA) and after intervention with disease modifying anti-rheumatic drugs (DMARDs) alone or in combination in a CIA female SD rat model induced by collagen type II. The rats were randomized to 8 groups: normal control group, CIA model control group, methotrexate (MTX, 0.9 mg/kg/w) group, cyclophosphamide (CTX, 24 mg/kg/3 w) group, leflunomide (LEF, 1.2 mg/kg/d) group, MTX + CTX group, LEF + CTX group, and MTX + LEF group. They were intervened with DMARDs alone or in combination for six weeks. The experiment lasted a total of 9 weeks in vivo. Articular inflammation was measured during the process of drug intervention in terms of the degree of swelling degree in the right hind foot using a venire caliper. All animals were sacrificed by breaking the neck after 9 weeks. Then, the ankle was fixed, decalcified, embedded, and HE stained, and prepared into slices to observe pathological changes in the synovial tissue. FAK expression in synovial cells was assayed by immunohistochemistry and the mean optical density (OD) value was measured using the HPIAS-2000 image analysis system. It was found that FAK expression was negative in normal control group, positive in CIA model control group, and decreased in the three DMARD combination treatment groups significantly as compared with that in the three single-drug groups (P < 0.05). FAK expression in LEF + CTX group or MTX + CTX group decreased more significantly than that in MTX + LEF group (P < 0.05), and there was no statistically significant difference between LEF + CTX and MTX + CTX groups. The arthritis index and pathological change in the synovial tissue in LEF + CTX group or MTX + CTX group

  2. 120MM Mortar MIL-STD-1660 Tests

    DTIC Science & Technology

    1994-07-01

    AD-A285 065 FINAL REPORT JULY 1994 REPORT NO. 91-18 120MM MORTAR MIL- STD - 1660 TESTS 94-309 󈧷 Prepared for: Dist.iviiior Unlimited I I U.S. Army...Inidude Securt Ciassificz ion) 120MM Mortar MIL- STD - i660 Tests 12- PERSONAL AUTHOR IS) William R. Meyer ~13a. TYPE OF REPORT 13b. TINE COVERED 14...Armnament Re- earch, Development and Engineering Center (ARDEC), SMCAR-AEP, to conduct MIL- STD - 1660 tests on 120M,\\M mortar rounds on wooden p~allets

  3. Shear bond strength evaluation of resin composite bonded to three different liners: TheraCal LC, Biodentine, and resin-modified glass ionomer cement using universal adhesive: An in vitro study

    PubMed Central

    Deepa, Velagala L; Dhamaraju, Bhargavi; Bollu, Indira Priyadharsini; Balaji, Tandri S

    2016-01-01

    Aims: To compare and evaluate the bonding ability of resin composite (RC) to three different liners: TheraCal LC™ (TLC), a novel resin-modified (RM) calcium silicate cement, Biodentine™ (BD), and resin-modified glass ionomer cement (RMGIC) using an universal silane-containing adhesive and characterizing their failure modes. Materials and Methods: Thirty extracted intact human molars with occlusal cavity (6-mm diameter and 2-mm height) were mounted in acrylic blocks and divided into three groups of 10 samples each based on the liner used as Group A (TLC), Group B (BD), and Group C (RMGIC). Composite post of 3 mm diameter and 3 mm height was then bonded to each sample using universal adhesive. Shear bond strength (SBS) analysis was performed at a cross-head speed of 1 mm/min. Statistical Analysis Used: Statistical analysis was performed with one-way analysis of variance (ANOVA) and post hoc test using Statistical Package for the Social Sciences (SPSS) version 20. Results: No significant difference was observed between group A and group C (P = 0.573) while group B showed the least bond strength values with a highly significant difference (P = 0.000). The modes of failure were predominantly cohesive in Groups A and B (TLC and BD) while RMGIC showed mixed and adhesive failures. Conclusions: Hence, this present study concludes that the bond strength of composite resin to TLC and RMGIC was similar and significantly higher than that of BD following application of universal adhesive. PMID:27099425

  4. A chemometric approach to the characterisation of historical mortars

    SciTech Connect

    Rampazzi, L. . E-mail: laura.rampazzi@uninsubria.it; Pozzi, A.; Sansonetti, A.; Toniolo, L.; Giussani, B.

    2006-06-15

    The compositional knowledge of historical mortars is of great concern in case of provenance and dating investigations and of conservation works since the nature of the raw materials suggests the most compatible conservation products. The classic characterisation usually goes through various analytical determinations, while conservation laboratories call for simple and quick analyses able to enlighten the nature of mortars, usually in terms of the binder fraction. A chemometric approach to the matter is here undertaken. Specimens of mortars were prepared with calcitic and dolomitic binders and analysed by Atomic Spectroscopy. Principal Components Analysis (PCA) was used to investigate the features of specimens and samples. A Partial Least Square (PLS1) regression was done in order to predict the binder/aggregate ratio. The model was applied to historical mortars from the churches of St. Lorenzo (Milan) and St. Abbondio (Como). The accordance between the predictive model and the real samples is discussed.

  5. 63. BUILDING NO. 1301, ORDNANCE FACILITY (MORTAR POWDER BUILDING), INTERIOR, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    63. BUILDING NO. 1301, ORDNANCE FACILITY (MORTAR POWDER BUILDING), INTERIOR, LOOKING SOUTHEAST DOWN SCREENED WALKWAY ON NORTHWEST SIDE. - Picatinny Arsenal, State Route 15 near I-80, Dover, Morris County, NJ

  6. 9. DETAIL OF DECORATIVE MORTAR AND COBBLESTONE WORK ON TYPICAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. DETAIL OF DECORATIVE MORTAR AND COBBLESTONE WORK ON TYPICAL POST ON UPSTREAM PARAPET WALL OF UPPER EMBANKMENT. VIEW TO SOUTH. - Boise Project, Deer Flat Embankments, Lake Lowell, Nampa, Canyon County, ID

  7. Use of microorganism to improve the strength of cement mortar

    SciTech Connect

    Ghosh, P.; Mandal, S. . E-mail: sarojmandal2001@yahoo.co.in; Chattopadhyay, B.D.; Pal, S.

    2005-10-01

    This study describes a method of strength improvement of cement-sand mortar by the microbiologically induced mineral precipitation. A thermophilic anaerobic microorganism is incorporated at different cell concentrations with the mixing water. The study showed that a 25% increase in 28 day compressive strength of cement mortar was achieved with the addition of about 10{sup 5} cell/ml of mixing water. The strength improvement is due to growth of filler material within the pores of the cement-sand matrix as shown by the scanning electron microscopy. The modification in pore size distribution and total pore volume of cement-sand mortar due to such growth is also noted. E. coli microorganisms were also used in the cement mortar for comparison, but no improvement in strength was observed.

  8. New System of Shrinkage Measurement through Cement Mortars Drying

    PubMed Central

    Morón, Carlos; Saiz, Pablo; Ferrández, Daniel; García-Fuentevilla, Luisa

    2017-01-01

    Cement mortar is used as a conglomerate in the majority of construction work. There are multiple variants of cement according to the type of aggregate used in its fabrication. One of the major problems that occurs while working with this type of material is the excessive loss of moisture during cement hydration (setting and hardening), known as shrinkage, which provokes a great number of construction pathologies that are difficult to repair. In this way, the design of a new sensor able to measure the moisture loss of mortars at different age levels is useful to establish long-term predictions concerning mortar mass volume loss. The purpose of this research is the design and fabrication of a new capacitive sensor able to measure the moisture of mortars and to relate it with the shrinkage. PMID:28272297

  9. Development of spraying agent for reducing drying shrinkage of mortar

    NASA Astrophysics Data System (ADS)

    Fujiwara, Hiromi; Maruoka, Masanori; Liu, Lingling

    2017-02-01

    Mortar used to repair is sometimes exposed to drying state in early ages after construction and a few days later water is sprayed frequently on the surface of the mortar in order to prevent cracks. This research studied on shrinkage characteristic of mortar subjected to drying conditions like this. The result showed that the water spraying on the mortar after initial drying did not have any effect to prevent shrinkage, but increased. And it also showed when various chemical agents are mixed and used in watersprayingit had the prevention effect on shrinkage. This report was to understand this kind of phenomenon and clarify the mechanism. In addition, based on the results, the new spraying agent was developed to reduce drying shrinkage.

  10. 7. Detail, beaded mortar joint, stepped wingwall coping at the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Detail, beaded mortar joint, stepped wingwall coping at the east portal of Tunnel 18, 135mm lens with electronic flash fill. - Southern Pacific Railroad Natron Cutoff, Tunnel No. 18, Milepost 410, Dorris, Siskiyou County, CA

  11. Modulation of marrow stromal osteoblast adhesion on biomimetic oligo[poly(ethylene glycol) fumarate] hydrogels modified with Arg-Gly-Asp peptides and a poly(ethyleneglycol) spacer.

    PubMed

    Shin, Heungsoo; Jo, Seongbong; Mikos, Antonios G

    2002-08-01

    Novel oligo[poly(ethylene glycol) fumarate] (OPF) hydrogels functionalized with cell adhesion peptides were prepared, and the effects of incorporated peptide density and macromolecular structure of hydrogels on attachment and morphology of marrow stromal cells (MSCs) were evaluated. Poly(ethylene glycol) (PEG; number average molecular weight of 930, 2860, and 6090) was used to synthesize OPF. A model peptide, Gly-Arg-Gly-Asp (GRGD), was incorporated into OPF hydrogels after being coupled to acrylated PEG of molecular weight 3400. The increase of incorporated peptide concentration enhanced MSC attachment to OPF hydrogels of PEG of molecular weight of 930 and 2860. However, the number of attached MSCs to OPF hydrogels of PEG (molecular weight 6090) remained constant regardless of the peptide density. The length of PEG in OPF also influenced cell attachment. When 1 micromole peptide/g hydrogel was incorporated into the OPF hydrogels, the degree of cell attachment at 12 h relative to the initial seeding density was 93.9 +/- 5.9%, 64.7 +/- 8.2%, and 9.3 +/- 6.6% for OPF hydrogels prepared with PEG of molecular weights of 930, 2860, and 6090, respectively. However, the crosslinking density of hydrogels did not significantly affect cell attachment. The interaction was sequence specific, in that MSC attachment to GRGD-modified hydrogels was competitively inhibited when cells were incubated in the presence of 0.5 mM soluble GRGD before cell seeding. These results suggest that we can modulate MSC attachment to OPF hydrogels by altering the peptide density and the molecular structure of OPF hydrogels.

  12. Effects of Arg-Gly-Asp-modified elastin-like polypeptide on pseudoislet formation via up-regulation of cell adhesion molecules and extracellular matrix proteins.

    PubMed

    Lee, Kyeong-Min; Jung, Gwon-Soo; Park, Jin-Kyu; Choi, Seong-Kyoon; Jeon, Won Bae

    2013-03-01

    Extracellular matrix (ECM) plays an important role in controlling the β-cell morphology, survival and insulin secretary functions. An RGD-modified elastin-like polypeptide (RGD-ELP), TGPG[VGRGD(VGVPG)(6)](20)WPC, has been reported previously as a bioactive matrix. In this study, to investigate whether RGD-ELP affects β-cell growth characteristics and insulin secretion, β-TC6 cells were cultured on the RGD-ELP coatings prepared via thermally induced phase transition. On RGD-ELP, β-TC6 cells clustered into an islet-like architecture with high cell viability. Throughout 7days' culture, the proliferation rate of the cells within a pseudoislet was similar to that of monolayer culture. Under high glucose (25mM), β-TC6 pseudoislets showed up-regulated insulin gene expression and exhibited glucose-stimulated insulin secretion. Importantly, the mRNA and protein abundances of cell adhesion molecules (CAM) E-cadherin and connexin-36 were much higher in pseudoislets than in monolayer cells. The siRNA-mediated inhibition of E-cadherin or connexin-36 expression severely limited pseudoislet formation. In addition, the mRNA levels of collagen types I and IV, fibronectin and laminin were significantly elevated in pseudoislets. The results suggest that RGD-ELP promotes pseudoislet formation via up-regulation of the CAM and ECM components. The functional roles of RGD-ELP are discussed in respect of its molecular composition. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  13. Cast adhesive polyelectrolyte complex particle films of unmodified or maltose-modified poly(ethyleneimine) and cellulose sulphate: fabrication, film stability and retarded release of zoledronate.

    PubMed

    Torger, Bernhard; Vehlow, David; Urban, Birgit; Salem, Samaa; Appelhans, Dietmar; Müller, Martin

    2013-12-01

    The bone therapeutic drug zoledronate (ZOL) was loaded at and released by polyelectrolyte complex (PEC) particle films composed of either pure poly(ethyleneimine) (PEI) or maltose-modified poly(ethyleneimine) (PEI-M) and oppositely charged cellulose sulfate attached to model germanium (Ge) substrates by solution casting. Dispersions of colloidally stable polyelectrolyte complex (PEC) particles in the size range 11-141 nm were obtained by mixing PEI or PEI-M, CS and ZOL in defined stoichiometric ratios. TRANS-FTIR spectroscopy was used to determine the stability of the PEC films against detachment, in-situ-ATR-FTIR spectroscopy for the ZOL loss in the PEC film and UV-VIS spectroscopy for the ZOL enrichment of the release medium. Films of casted ZOL/CS/PEI-M or ZOL/CS/PEI particles were stable in contact to water, while films of the pure drug (ZOL) and of the binary systems ZOL/PEI-M or ZOL/PEI were not stable against detachment. Retarded releases of ZOL from various PEC films compared to the pure drug film were observed. The molecular weight of PEI showed a considerable effect on the initial burst (IB) of ZOL. No significant effect of the maltose modification of PEI-25 K on IB could be found. Generally, after one day the ZOL release process was finished for all measured ZOL/PEC samples and residual amounts of 0-30% were obtained. Surface adhesive drug loaded PEC particles are promising drug delivery systems to supply and release a defined amount of bone therapeutics and to functionalize bone substitution materials.

  14. Carbon fiber reinforced mortar as an electrical contact material for cathodic protection

    SciTech Connect

    Fu, X.; Chung, D.D.L.

    1995-05-01

    For a joint between old plain mortar and new mortar (which serves as an electrical contact material for cathodic protection of steel-reinforced old mortar), short carbon fiber addition to the new mortar was found to decrease both the contact resistivity and the new mortar`s volume resistivity. Whether the new mortar contained fibers or not, the contact resistance was higher than the new mortar`s volume resistance perpendicular to the contact and was lower than the new mortar`s volume resistance parallel to the contact. In the presence of latex, the volume resistivity was 3.1 {times} 10{sup 5}, 1.4 {times} 10{sup 3} and 1.2 {times} 10{sup 2} {Omega}{center_dot}cm and the contact resistivity was 5.9 {times} 10{sup 6}, 2.7 {times} 10{sup 5} and 2.6 {times} 10{sup 4} {Omega}{center_dot}cm{sup 2} at fiber contents of 0, 0.53 and 1.1 vol.% respectively. Latex addition alone to the new mortar increased slightly both contact resistivity and new mortar`s volume resistivity. All resistivities increased very slightly with curing age.

  15. Flight qualification of mortar-actuated parachute deployment systems

    NASA Technical Reports Server (NTRS)

    Pleasants, J. E.

    1975-01-01

    A brief discussion outlines background of mortar use in parachute deployment systems. A description of the system operation is presented. Effects of the environment on performance are discussed as well as the instrumentation needed to assess this performance. Power unit qualification and lot qualification for shear pins and cartridges is delineated. Functional mortar system tests are described. Finally, bridle deployment and parachute deployment are discussed.

  16. Properties of wastepaper sludge in geopolymer mortars for masonry applications.

    PubMed

    Yan, Shiqin; Sagoe-Crentsil, Kwesi

    2012-12-15

    This paper presents the results of an investigation into the use of wastepaper sludge in geopolymer mortar systems for manufacturing construction products. The investigation was driven by the increasing demand for reuse options in paper-recycling industry. Both fresh and hardened geopolymer mortar properties are evaluated for samples incorporating dry wastepaper sludge, and the results indicate potential end-use benefits in building product manufacture. Addition of wastepaper sludge to geopolymer mortar reduces flow properties, primarily due to dry sludge absorbing water from the binder mix. The average 91-day compressive strength of mortar samples incorporating 2.5 wt% and 10 wt% wastepaper sludge respectively retained 92% and 52% of the reference mortar strength. However, contrary to the normal trend of increasing drying shrinkage with increasing paper sludge addition to Portland cement matrices, the corresponding geopolymer drying shrinkage decreased by 34% and 64%. Equally important, the water absorption of hardened geopolymer mortar decreased with increasing paper sludge content at ambient temperatures, providing good prospects of overall potential for wastepaper sludge incorporation in the production of building and masonry elements. The results indicate that, despite its high moisture absorbance due to the organic matter and residual cellulose fibre content, wastepaper sludge appears compatible with geopolymer chemistry, and hence serves as a potential supplementary additive to geopolymer cementitious masonry products. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Anti-adhesive characteristics of CHF{sub 3}/O{sub 2} and C{sub 4}F{sub 8}/O{sub 2} plasma-modified silicon molds for nanoimprint lithography

    SciTech Connect

    Lee, Jaemin; Lee, Junmyung; Lee, Hyun Woo; Kwon, Kwang-Ho

    2015-09-15

    The anti-adhesive characteristics of a plasma-modified silicon mold surface for nanoimprint lithography are presented. Both CHF{sub 3}/O{sub 2} and C{sub 4}F{sub 8}/O{sub 2} plasma were used to form an anti-adhesive layer on silicon mold surfaces. The gas mixing ratios of CHF{sub 3}/O{sub 2} and C{sub 4}F{sub 8}/O{sub 2} were experimentally changed between 0% and 80% to optimize the plasma conditions to obtain a low surface energy of the silicon mold. The plasma characteristics were examined by optical emission spectroscopy (OES). In order to investigate the changes in surface energy and surface chemistry of the anti-adhesive layer during repeated demolding cycles, contact angle measurements and X-ray photoelectron spectroscopy (XPS) were performed on the plasma-modified silicon mold surface. Simultaneously, the surface morphology of the demolded resists was evaluated by field-emission scanning electron microscope (FE-SEM) in order to examine the effect of the anti-adhesive layers on the duplicated patterns of the resists. It was observed that the anti-adhesive layer formed by CHF{sub 3}/O{sub 2} plasma treatment was worn out more easily during repeated demolding cycles than the film formed by C{sub 4}F{sub 8}/O{sub 2} plasma treatment, because CHF{sub 3}/O{sub 2} gas plasma formed a thinner plasma-polymerized film over the same plasma treatment time.

  18. Properties of microcement mortar with nano particles

    NASA Astrophysics Data System (ADS)

    Alimeneti, Narasimha Reddy

    Carbon nanotubes (CNT) and Carbon nanofibers (CNF) are one of the toughest and stiffest materials in the world presently with extreme properties yet to be discovered in terms of elastic modulus and tensile strength. Due to the advanced properties of these materials they are being used in almost all fields of science at nanolevel and are being used in construction industry recently for improvement of material properties. Microcement is fine ground cement which as half the particle size of ordinary Portland cement. In this research the behavior of cement mortar of micro cement with the addition of nanoparticles is studied. Due to high aspect ratio and strong van der Waal forces between the particles of CNT and CNF, they agglomerate and form bundles when mixed with water, sonication method is used to mix nanoparticles with few drops of surfactant and super plasticizer. Mechanical properties such as compressive strength and flexural strength with CNT and CNF composites are examined and compared with control samples. 0.1% and 0.05 % of nanoparticles (both CNT and CNF) by the weight of cement are used in this research and 0.8% of super plasticizer by weight of cement was also used along with 0.4, 0.45 and 0.50 water cement ratios for making specimens for compression test. The compressive strength results are not satisfactory as there was no constant increase in strength with all the composites, however strength of few nanocomposites increased by a good percentage. 0.5 water cement ratio cement mortar had compressive strength of 7.15 ksi (49.3 MPa), whereas sample with 0.1% CNT showed 8.38 ksi (57.8 MPa) with 17% increase in strength after 28 days. Same trend was followed by 0.4 water cement ratio as the compressive strength of control sample was 8.89 ksi (61.3 MPa), with 0.05% of CNT strength increased to 10.90 ksi (75.2 MPa) with 23% increase in strength. 0.4 water cement ratio was used for flexural tests including 0.1%, 0.05% of CNT and 0.1%, 0.05% of CNF with 0

  19. Micro- and meso-scale pore structure in mortar in relation to aggregate content

    SciTech Connect

    Gao, Yun; De Schutter, Geert; Ye, Guang

    2013-10-15

    Mortar is often viewed as a three-phase composite consisting of aggregate, bulk paste, and an interfacial transition zone (ITZ). However, this description is inconsistent with experimental findings because of the basic assumption that larger pores are only present within the ITZ. In this paper, we use backscattered electron (BSE) imaging to investigate the micro- and meso-scale structure of mortar with varying aggregate content. The results indicate that larger pores are present not only within the ITZ but also within areas far from aggregates. This phenomenon is discussed in detail based on a series of analytical calculations, such as the effective water binder ratio and the inter-aggregate spacing. We developed a modified computer model that includes a two-phase structure for bulk paste. This model interprets previous mercury intrusion porosimetry data very well. -- Highlights: •Based on BSE, we examine the HCSS model. •We develop the HCSS-DBLB model. •We use the modified model to interpret the MIP data.

  20. Study of sticky rice-lime mortar technology for the restoration of historical masonry construction.

    PubMed

    Yang, Fuwei; Zhang, Bingjian; Ma, Qinglin

    2010-06-15

    Replacing or repairing masonry mortar is usually necessary in the restoration of historical constructions, but the selection of a proper mortar is often problematic. An inappropriate choice can lead to failure of the restoration work, and perhaps even further damage. Thus, a thorough understanding of the original mortar technology and the fabrication of appropriate replacement materials are important research goals. Many kinds of materials have been used over the years in masonry mortars, and the technology has gradually evolved from the single-component mortar of ancient times to hybrid versions containing several ingredients. Beginning in 2450 BCE, lime was used as masonry mortar in Europe. In the Roman era, ground volcanic ash, brick powder, and ceramic chip were added to lime mortar, greatly improving performance. Because of its superior properties, the use of this hydraulic (that is, capable of setting underwater) mortar spread, and it was adopted throughout Europe and western Asia. Perhaps because of the absence of natural materials such as volcanic ash, hydraulic mortar technology was not developed in ancient China. However, a special inorganic-organic composite building material, sticky rice-lime mortar, was developed. This technology was extensively used in important buildings, such as tombs, in urban constructions, and even in water conservancy facilities. It may be the first widespread inorganic-organic composite mortar technology in China, or even in the world. In this Account, we discuss the origins, analysis, performance, and utility in historic preservation of sticky rice-lime mortar. Mortar samples from ancient constructions were analyzed by both chemical methods (including the iodine starch test and the acid attack experiment) and instrumental methods (including thermogravimetric differential scanning calorimetry, X-ray diffraction, Fourier transform infrared, and scanning electron microscopy). These analytical results show that the ancient masonry

  1. Elastomer-toughened polyimide adhesives

    NASA Technical Reports Server (NTRS)

    Saint Clair, A. K.; Saint Clair, T. L.

    1980-01-01

    A study has been conducted to determine the effects of added elastomers on the Tg, thermal stability, adhesive strength, and fracture toughness of LARC-13, a high-temperature addition polyimide adhesive. Various butadiene/acrylonitrile and silicone elastomers were incorporated into the polyimide resin (1) as physical polyblends, and (2) by chemically reacting the elastomers with the polyimide backbone. Adhesive single lap-shear and T-peel strengths were measured before and after aging at elevated temperature. A tapered double-cantilever beam specimen was used to determine the fracture toughness of the elastomer-modified polyimide adhesives.

  2. Sulfur-free lignins from alkaline pulping tested in mortar for use as mortar additives.

    PubMed

    Nadif, A; Hunkeler, D; Käuper, P

    2002-08-01

    Sulfur-free lignin, obtained through the acid precipitation of black liquor from the soda pulping process, has been tested as water reducer in mortar. It has also been compared to existing commercial additives such as naphthalene sulfonates and lignosulfonates. The ash content and sugar content of these lignins are low in comparison to lignosulfonates, conferring on them higher purity. A procedure for small scale testing derived from the industrial norms SN-EN196 and ASTM (Designation C230-90) is presented. Specifically, all the sulfur-free lignins tested improved the flow of the mortar. Selected flax lignins performed better than lignosulfonates though still less than naphthalene sulfonates. Furthermore, certain hemp lignins gave comparable results to the lignosulfonates. Overall, the straw lignin prepared herein is comparable in performance to commercially available lignins, such as Organocell, Alcell and Curan 100. The plant from which the lignin was isolated, and the process of the pulp mill are the primary influences on the performance of the lignin.

  3. Use of rubble from building demolition in mortars.

    PubMed

    Corinaldesi, V; Giuggiolini, M; Moriconi, G

    2002-01-01

    Because of increasing waste production and public concerns about the environment, it is desirable to recycle materials from building demolition. If suitably selected, ground, cleaned and sieved in appropriate industrial crushing plants, these materials can be profitably used in concrete. Nevertheless, the presence of masonry instead of concrete rubble is particularly detrimental to the mechanical performance and durability of recycled-aggregate concrete and the same negative effect is detectable when natural sand is replaced by fine recycled aggregate fraction. An alternative use of both masonry rubble and fine recycled material fraction could be in mortars. These could contain either recycled instead of natural sand or powder obtained by bricks crushing as partial cement substitution. In particular, attention is focused on the modification that takes place when either polypropylene or stainless steel fibers are added to these mortars. Polypropylene fibers are added in order to reduce shrinkage of mortars, stainless steel fibers for improving their flexural strength. The combined use of polypropylene fibers and fine recycled material from building demolition could allow the preparation of mortars showing good performance, in particular when coupled with bricks. Furthermore, the combined use of stainless steel fibers and mortars containing brick powder seems to be an effective way to guarantee a high flexural strength.

  4. Mortar radiocarbon dating: preliminary accuracy evaluation of a novel methodology.

    PubMed

    Marzaioli, Fabio; Lubritto, Carmine; Nonni, Sara; Passariello, Isabella; Capano, Manuela; Terrasi, Filippo

    2011-03-15

    Mortars represent a class of building and art materials that are widespread at archeological sites from the Neolithic period on. After about 50 years of experimentation, the possibility to evaluate their absolute chronology by means of radiocarbon ((14)C) remains still uncertain. With the use of a simplified mortar production process in the laboratory environment, this study shows the overall feasibility of a novel physical pretreatment for the isolation of the atmospheric (14)CO(2) (i.e., binder) signal absorbed by the mortars during their setting. This methodology is based on the assumption that an ultrasonic attack in liquid phase isolates a suspension of binder carbonates from bulk mortars. Isotopic ((13)C and (14)C), % C, X-ray diffractometry (XRD), and scanning electron microscopy (SEM) analyses were performed to characterize the proposed methodology. The applied protocol allows suppression of the fossil carbon (C) contamination originating from the incomplete burning of the limestone during the quick lime production, providing unbiased dating for "laboratory" mortars produced operating at historically adopted burning temperatures.

  5. Oyster shell as substitute for aggregate in mortar.

    PubMed

    Yoon, Hyunsuk; Park, Sangkyu; Lee, Kiho; Park, Junboum

    2004-06-01

    Enormous amounts of oyster shell waste have been illegally disposed of at oyster farm sites along the southern coast of Korea. In this study to evaluate the possibility of recycling this waste for use as a construction material, the mechanical characteristics of pulverized oyster shell were investigated in terms of its potential utilization as a substitute for the aggregates used in mortar. The unconfined compressive strengths of various soil mortar specimens, with varying blending ratios of cement, water and oyster shell, were evaluated by performing unconfined compression tests, and the results were compared with the strengths of normal cement mortar made with sand. In addition, the effect of organic chemicals on the hardening of concrete was evaluated by preparing ethyl-benzene-mixed mortar specimens. The long-term strength improvement resulting from the addition of fly ash was also examined by performing unconfined compression tests on specimens with fly-ash content. There was no significant reduction in the compressive strength of the mortars containing small oyster shell particles instead of sand. From these test data, the possible application of oyster shells in construction materials could be verified, and the change in the strength parameters according to the presence of organic compounds was also evaluated.

  6. Long-term dentin retention of etch-and-rinse and self-etch adhesives and a resin-modified glass ionomer cement in non-carious cervical lesions.

    PubMed

    van Dijken, Jan W V; Pallesen, Ulla

    2008-07-01

    The aim of this study was to evaluate the clinical long-term retention to dentin of seven adhesive systems. A total of 270 Class V restorations of four etch-and-rinse, one self-etch adhesive system and a resin-modified glass ionomer cement were placed in non-carious cervical lesions without intentional enamel involvement. The restorations were evaluated at baseline, 6, 12, 18, and 24 months and then every year during a 13-year follow-up. Dentin bonding efficiency was determined by the percentage of lost restorations. During the 13 years, 215 restorations could be evaluated. The cumulative loss rate at 13 years was 53.0%, with significant different failures rates for the different systems varying between 35.6 and 86.8%. Four systems fulfilled the ADA 18-month full acceptance retention criteria. Two systems showed at 18 months and earlier high debonding rates. The annual failure rates for the etch-and-rinse systems were Optibond 3.1%, Permagen 13.0%, Scotchbond MP 4.8%, Syntac classic 2.8%; for the self-etch system P&S 4.4%; and the resin-modified glass ionomer cement Vitremer 2.7%. It can be concluded that all systems showed a continuous degradation of the bond with a wide variation, which was independent of the adhesion strategy. Three bonding systems showed a cumulative failure rate after 13 years between 36 and 41% with the best retention for the resin-modified glass ionomer cement and a four-step etch-and-rinse system.

  7. Durability of Waste Glass Flax Fiber Reinforced Mortar

    NASA Astrophysics Data System (ADS)

    Aly, M.; Hashmi, M. S. J.; Olabi, A. G.; Messeiry, M.

    2011-01-01

    The main concern for natural fibre reinforced mortar composites is the durability of the fibres in the alkaline environment of cement. The composites may undergo a reduction in strength as a result of weakening of the fibres by a combination of alkali attack and fibre mineralisation. In order to enhance the durability of natural fiber reinforced cement composites several approaches have been studied including fiber impregnation, sealing of the matrix pore system and reduction of matrix alkalinity through the use of pozzolanic materials. In this study waste glass powder was used as a pozzolanic additive to improve the durability performance of flax fiber reinforced mortar (FFRM). The durability of the FFRM was studied by determining the effects of ageing in water and exposure to wetting and drying cycles; on the microstructures and flexural behaviour of the composites. The mortar tests demonstrated that the waste glass powder has significant effect on improving the durability of FFRM.

  8. Influence of Pore Structure on Compressive Strength of Cement Mortar

    PubMed Central

    Zhao, Haitao; Xiao, Qi; Huang, Donghui

    2014-01-01

    This paper describes an experimental investigation into the pore structure of cement mortar using mercury porosimeter. Ordinary Portland cement, manufactured sand, and natural sand were used. The porosity of the manufactured sand mortar is higher than that of natural sand at the same mix proportion; on the contrary, the probable pore size and threshold radius of manufactured sand mortar are finer. Besides, the probable pore size and threshold radius increased with increasing water to cement ratio and sand to cement ratio. In addition, the existing models of pore size distribution of cement-based materials have been reviewed and compared with test results in this paper. Finally, the extended Bhattacharjee model was built to examine the relationship between compressive strength and pore structure. PMID:24757414

  9. Durability of waste glass flax fiber reinforced mortar

    SciTech Connect

    Aly, M.; Hashmi, M. S. J.; Olabi, A. G.; Messeiry, M.

    2011-01-17

    The main concern for natural fibre reinforced mortar composites is the durability of the fibres in the alkaline environment of cement. The composites may undergo a reduction in strength as a result of weakening of the fibres by a combination of alkali attack and fibre mineralisation. In order to enhance the durability of natural fiber reinforced cement composites several approaches have been studied including fiber impregnation, sealing of the matrix pore system and reduction of matrix alkalinity through the use of pozzolanic materials. In this study waste glass powder was used as a pozzolanic additive to improve the durability performance of flax fiber reinforced mortar (FFRM). The durability of the FFRM was studied by determining the effects of ageing in water and exposure to wetting and drying cycles; on the microstructures and flexural behaviour of the composites. The mortar tests demonstrated that the waste glass powder has significant effect on improving the durability of FFRM.

  10. Effects of moisture on ultrasound propagation in cement mortar

    NASA Astrophysics Data System (ADS)

    Ju, Taeho; Li, Shuaili; Achenbach, Jan; Qu, Jianmin

    2015-03-01

    In concrete structures, moisture is often a major cause of chemically related degradations such as alkaline-silica reaction. To develop ultrasonic nondestructive evaluation techniques for monitoring such chemical degradations, it is necessary to understand how moisture affects the propagation of ultrasound in concrete. To this end, the objective of this paper is to experimentally determine the correlation between the moisture content in cement mortar and ultrasonic wave propagation. Specifically, effects of moisture on the ultrasonic phase velocity and attenuation are examined. It is found that, for the cement mortar samples considered in this study, moisture has negligible effect on the ultrasonic phase velocity. However, moisture can significantly increase the attenuation of ultrasound in cement mortar even in the sub-MHz frequency range.

  11. Various mortars for anti-fouling purposes in marine environments

    SciTech Connect

    Kanematsu, Hideyuki; Masuda, Tomoka; Miura, Yoko; Kuroda, Daisuke; Hirai, Nobumitsu; Yokoyama, Seiji

    2014-02-20

    The antifouling properties for some mortars with steel making slags were investigated by real marine immersion tests and a unique laboratory acceleration tests with a specially devised biofilm acceleration reactors. Mortars mixed with steel making slags containing abundant iron elements tended to form biofilm and also bifouling. The two kinds of biofilm formation tests were used in this study. Real immersion in marine environments and laboratory test with a specially devised biofilm acceleration reactor. The former evaluated the biofouling characteristics more properly, while the latter did the biofilm formation characteristics more effectively.

  12. Ancient mortars from Cape Verde: mineralogical and physical characterization

    NASA Astrophysics Data System (ADS)

    Rocha, Fernando; Costa, Cristiana; Velosa, Ana; Quintela, Ana; Terroso, Denise; Marques, Vera

    2014-05-01

    Times and locations of different building constructions means different knowledge, habits, different construction methods and materials. The study and safeguarding of the architectural heritage takes nowadays a progressive importance as a vehicle for transmission of cultures and history of nations. The coatings are of great importance in the durability of a building due to the protective role of the masonry. The compatibility between the materials with which they are executed (masonry, mortar and grout settlement) promotes the proper functioning of the wall and a consequent increase in durability. Therefore, it becomes important to study and characterize the mortar coating of buildings to know its characteristics and to use compatible materials in the rehabilitation and maintenance of buildings. This study aims to characterize the chemical, physical, mechanical and mineralogical mortar samples collected in buildings in three islands of Cape Verde, for the conservation, rehabilitation and preservation of them. The collected samples belong to buildings constructed in the end of XIX century and in the beginning of XX century. In order to characterize the mortar samples some tests was made, such as X-Ray Diffraction, X- Ray Fluorescence, acid attack and mechanical strength. The samples were divided into three groups depending on origin; so we have a first group collected on the island of Santiago, the second on the island of Saint Vincent and the third on the island of Santo Antao. The samples are all carbonated, but Santiago samples have a lower carbonates content. In terms of insoluble residue (from the acid attack) it was concluded that the samples have similar value ranging from 9 to 26%. The compressive strength of the mortars have a range between 1.36 and 4.55 MPa, which is related to the presence of more binder in samples with higher resistance. The chemical and mineralogical analyzes showed that these consist of lime mortars (binder), natural pozzolan and

  13. Various mortars for anti-fouling purposes in marine environments

    NASA Astrophysics Data System (ADS)

    Kanematsu, Hideyuki; Masuda, Tomoka; Miura, Yoko; Hirai, Nobumitsu; Kuroda, Daisuke; Yokoyama, Seiji

    2014-02-01

    The antifouling properties for some mortars with steel making slags were investigated by real marine immersion tests and a unique laboratory acceleration tests with a specially devised biofilm acceleration reactors. Mortars mixed with steel making slags containing abundant iron elements tended to form biofilm and also bifouling. The two kinds of biofilm formation tests were used in this study. Real immersion in marine environments and laboratory test with a specially devised biofilm acceleration reactor. The former evaluated the biofouling characteristics more properly, while the latter did the biofilm formation characteristics more effectively.

  14. Abdominal Adhesions

    MedlinePlus

    ... Adhesions 1 Ward BC, Panitch A. Abdominal adhesions: current and novel therapies. Journal of Surgical Research. 2011;165(1):91–111. Seek Help for ... and how to participate, visit the NIH Clinical Research Trials and You website ... Foundation for Functional Gastrointestinal Disorders 700 West Virginia ...

  15. Design of Inorganic Polymer Mortar from Ferricalsialic and Calsialic Slags for Indoor Humidity Control

    PubMed Central

    Kamseu, Elie; Lancellotti, Isabella; Sglavo, Vincenzo M.; Modolo, Luca; Leonelli, Cristina

    2016-01-01

    Amorphous silica and alumina of metakaolin are used to adjust the bulk composition of black (BSS) and white (WSS) steel slag to prepare alkali-activated (AAS) mortars consolidated at room temperature. The mix-design also includes also the addition of semi-crystalline matrix of river sand to the metakaolin/steel powders. The results showed that high strength of the steel slag/metakaolin mortars can be achieved with the geopolymerization process which was particularly affected by the metallic iron present into the steel slag. The corrosion of the Fe particles was found to be responsible for porosity in the range between 0.1 and 10 µm. This class of porosity dominated (~31 vol %) the pore network of B compared to W samples (~16 vol %). However, W series remained with the higher cumulative pore volume (0.18 mL/g) compared to B series, with 0.12 mL/g. The maximum flexural strength was 6.89 and 8.51 MPa for the W and B series, respectively. The fracture surface ESEM observations of AAS showed large grains covered with the matrix assuming the good adhesion bonds between the gel-like geopolymer structure mixed with alkali activated steel slag and the residual unreacted portion. The correlation between the metallic iron/Fe oxides content, the pore network development, the strength and microstructure suggested the steel slag's significant action into the strengthening mechanism of consolidated products. These products also showed an interesting adsorption/desorption behavior that suggested their use as coating material to maintain the stability of the indoor relative humidity. PMID:28773529

  16. 62. BUILDING NO. 1301, ORDNANCE FACILITY (MORTAR POWDER BUILDING), LOOKING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    62. BUILDING NO. 1301, ORDNANCE FACILITY (MORTAR POWDER BUILDING), LOOKING AT NORTHWEST FACADE. ACCESS TO ROOF ALLOWS MAINTENANCE OF VENTILATION EQUIPMENT WHICH IS PLACED OUTSIDE BUILDING TO MINIMIZE EXPLOSION HAZARD. NO. 2 VISIBLE ON WALL OF BUILDING STANDS FOR EXPLOSION HAZARD WITH FRAGMENTATION. - Picatinny Arsenal, State Route 15 near I-80, Dover, Morris County, NJ

  17. Seismic augmentation of acoustic monitoring of mortar fire

    NASA Astrophysics Data System (ADS)

    Anderson, Thomas S.

    2007-10-01

    The US Army Corps of Engineers Research and Development Center participated in a joint ARL-NATO TG-53 field experiment and data collect at Yuma Proving Ground, AZ in early November 2005. Seismic and acoustic signatures from both muzzle blasts and impacts of small arms fire and artillery were recorded using 7 seismic arrays and 3 acoustic arrays. Arrays comprised of 12 seismic and 12 acoustic sensors each were located from 700 m to 18 km from gun positions. Preliminary analysis of signatures attributed to 60mm, 81mm, 120 mm mortars recorded at a seismic-acoustic array 1.1 km from gun position are presented. Seismic and acoustic array f-k analysis is performed to detect and characterize the source signature. Horizontal seismic data are analyzed to determine efficacy of a seismic discriminant for mortar and artillery sources. Rotation of North and East seismic components to radial and transverse components relative to the source-receiver path provide maximum surface wave amplitude on the transverse component. Angles of rotation agree well with f-k analysis of both seismic and acoustic signals. The spectral energy of the rotated transverse surface wave is observable on the all caliber of mortars at a distance of 1.1 km and is a reliable source discriminant for mortar sources at this distance. In a step towards automation, travel time stencils using local seismic and acoustic velocities are applied to seismic data for analysis and determination of source characteristics.

  18. Do Schools Still Need Brick-and-Mortar Libraries?

    ERIC Educational Resources Information Center

    Johnson, Doug; Mastrion, Keith

    2009-01-01

    Do all schools need brick-and-mortar libraries? In this article, Johnson and Mastrion share their contradictory thoughts to the question. Johnson says some schools don't need library facilities or programs or librarians. These schools' teachers and administrators: (1) feel no need for a collaborative learning space; (2) feel the ability to process…

  19. Modeling the thermal characteristics of masonry mortar containing recycled materials

    NASA Astrophysics Data System (ADS)

    Laney, Morgan Gretchen

    As the building industry in the United States rapidly expands, the reuse of recycled demolition waste aggregates is becoming increasingly more important. Currently, the building industry is the largest consumer of natural resources. The constant use of raw virgin aggregate is resulting in depleting resources, lack of space for landfills, increasing costs, and heightened levels of pollution. The use of these recycled aggregates in building envelopes and the study of thermal properties are becoming a popular area of research in order to improve building energy usage. The construction of Zero Energy Buildings (ZEB) is encouraged by the United States government as a result of the unresolved finite resources and environmental pollution. The focus of this research is on the impact of using recycled demolition waste aggregates on thermal properties, including specific heat capacity and thermal conductivity, in masonry mortar applications. The new forms of aggregate were analyzed for efficiency and practical utilization in construction in seven locations across the United States by embedding the new material into the building envelope of a strip mall mercantile build model from the National Renewable Energy Laboratory (NREL) in the EnergyPlus Building Energy Simulation Program (BESP). It was determined that the recycled aggregate mortar mixtures performed as well as or better than the traditional mortar mix. Opportunities for future research in recycled aggregate mortar mixtures exist in a regional analysis, a regional recycled aggregate cost analysis, and a life cycled cost analysis (LCCA).

  20. Low Carbon Footprint mortar from Pozzolanic Waste Material

    NASA Astrophysics Data System (ADS)

    Mehmannavaz, Taha; Mehman navaz, Hossein Ali; Moayed Zefreh, Fereshteh; Aboata, Zahra

    2017-04-01

    Nowadays, Portland cement clinker leads to emission of CO2 into the atmosphere and therefore causes greenhouse effect. Incorporating of Palm Oil Fuel Ash (POFA) and Pulverized Fuel Ash (PFA) as partial cement replacement materials into mix of low carbon mortar decreases the amount of cement use and reduces high dependence on cements compared to ordinary mortar. The result of this research supported use of the new concept in preparing low carbon mortar for industrial constructions. Strength of low carbon mortar with POFA and PFA replacement in cement was affected and changed by replacing percent finesse, physical and chemical properties and pozzolanic activity of these wastes. Waste material replacement instead of Ordinary Portland Cement (OPC) was used in this study. This in turn was useful for promoting better quality of construction and innovative systems in construction industry, especially in Malaysia. This study was surely a step forward to achieving quality products which were affordable, durable and environmentally friendly. Disposing ash contributes to shortage of landfill space in Malaysia. Besides, hazard of ash might be another serious issue for human health. The ash disposal area also might create a new problem, which is the area's sedimentation and erosion.

  1. Workability and strength of lignite bottom ash geopolymer mortar.

    PubMed

    Sathonsaowaphak, Apha; Chindaprasirt, Prinya; Pimraksa, Kedsarin

    2009-08-30

    In this paper, the waste lignite bottom ash from power station was used as a source material for making geopolymer. Sodium silicate and sodium hydroxide (NaOH) were used as liquid for the mixture and heat curing was used to activate the geopolymerization. The fineness of bottom ash, the liquid alkaline/ash ratio, the sodium silicate/NaOH ratio and the NaOH concentration were studied. The effects of the additions of water, NaOH and napthalene-based superplasticizer on the workability and strength of the geopolymer mortar were also studied. Relatively high strength geopolymer mortars of 24.0-58.0 MPa were obtained with the use of ground bottom ash with 3% retained on sieve no. 325 and mean particle size of 15.7 microm, using liquid alkaline/ash ratios of 0.429-0.709, the sodium silicate/NaOH ratios of 0.67-1.5 and 7.5-12.5M NaOH. The incorporation of water improved the workability of geopolymer mortar more effectively than the use of napthalene-based superplasticizer with similar slight reduction in strengths. The addition of NaOH solution slightly improves the workability of the mix while maintaining the strength of the geopolymer mortars.

  2. 2. VIEW, LOOKING FROM THE NORTHEAST. THESE THREE CONCRETE MORTAR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. VIEW, LOOKING FROM THE NORTHEAST. THESE THREE CONCRETE MORTAR BLOCKS WERE FOR THE MILL'S 3-STAMP BATTERIES ERECTED IN 1903, NORTH OF THE TWO 1901 BATTERIES WHICH WERE MOUNTED ON WOODEN TIMBERS - Wilbur-Womble Mill, Southern Edge Of Salt Spring Valley, Copperopolis, Calaveras County, CA

  3. Comparing the Environmental Impacts of Alkali Activated Mortar and Traditional Portland Cement Mortar using Life Cycle Assessment

    NASA Astrophysics Data System (ADS)

    Matheu, P. S.; Ellis, K.; Varela, B.

    2015-11-01

    Since the year 1908 there has been research into the use alkali activated materials (AAM) in order to develop cementitious materials with similar properties to Ordinary Portland Cement. AAMs are considered green materials since their production and synthesis is not energy intensive. Even though AAMs have a high compressive strength, the average cost of production among other issues limits its feasibility. Previous research by the authors yielded a low cost AAM that uses mine tailings, wollastonite and ground granulated blast furnace slag (GGBFS). This mortar has an average compressive strength of 50MPa after 28 days of curing. In this paper the software SimaPro was used to create a product base cradle to gate Life Cycle Assessment (LCA). This compared the environmental impact of the AAM mortar to an Ordinary Portland Cement mortar (PCHM) with similar compressive strength. The main motivation for this research is the environmental impact of producing Ordinary Portland Cement as compared to alkali activated slag materials. The results of this LCA show that the Alkali Activated Material has a lower environmental impact than traditional Portland cement hydraulic mortar, in 10 out of 12 categories including Global Warming Potential, Ecotoxicity, and Smog. Areas of improvement and possible future work were also discovered with this analysis.

  4. Adhesion of nitrile rubber to UV-assisted surface chemical modified PET fabric, part II: Interfacial characterization of MDI grafted PET

    NASA Astrophysics Data System (ADS)

    Razavizadeh, Mahmoud; Jamshidi, Masoud

    2016-08-01

    Fiber to rubber adhesion is an important subject in rubber industry. It is well known that surface treatment (i.e. physical, mechanical and chemical) is an effective method to improve interfacial bonding of fibers and/or fabrics to rubbers. UV irradiation is an effective method which has been used to increase fabric-rubber interfacial interactions. In this research UV assisted chemical modification of PET fabrics was used to increase PET to nitrile rubber (NBR) adhesion. Nitrile rubber is a perfect selection as fuel and oil resistant rubber. However it has weak bonding to PET fabric. For this purpose PET fabric was carboxylated under UV irradiation and then methylenediphenyl diisocyanate (MDI) was grafted on carboxylated PET. The chemical composition of the fabric before and after surface treatment was investigated by X-ray photoelectron spectroscopy (XPS). The sectional morphology of the experimental PET fibers and the interface between rubber compound and PET fabric was studied using scanning electron microscope (SEM). The morphology and structure of the product were analyzed by an energy dispersive X-ray spectrometer (EDX). FTIR-ATR and H NMR analysis were used to assess surface modifications on the PET irradiated fabrics.

  5. Chemical composition influence of cement based mortars on algal biofouling

    NASA Astrophysics Data System (ADS)

    Estelle, Dalod; Alexandre, Govin; Philippe, Grosseau; Christine, Lors; René, Guyonnet; Denis, Damidot

    2013-04-01

    The main cause of building-facade biodegradation is the growth of microorganisms. This phenomenon depends on several parameters such as the geographical situation, the environmental conditions and the surface state of the substrate. Several researches have been devoted to the study of the effect of porosity and roughness on the biofouling of stones and mortars. However, none of them have addressed the influence of the mortar chemistry on the microorganism growth kinetic. The main objective of this study is to highlight the influence of the mortar chemistry in relationship with its physical properties on biological weathering. Earlier work showed a good resistance of Calcium Aluminate Cements to biodeterioration by acidogenic bacteria (Thiobacillus) and fungi (Alternaria alternata, Aspergillus Niger and Coniosporium uncinatum). In order to characterize the influence of the mortar chemistry on biofouling, two Portland cements and two alumina cements are used. Among micro-organisms able to grow, green algae are most involved in the aesthetic deterioration of facades. Indeed, they can colonize any type of media and can be a source of nutrients for other micro-organisms such as fungi. The green algae Klebsormidium flaccidum is chosen because of its representativeness. It is indeed the species the most frequently identified and isolated from samples taken on sites. The biofouling kinetic is followed on samples exposed outdoor and on samples tested in a laboratory bench which consists in spraying an algae culture on mortar specimens. The results obtained by in situ trials are compared with the results obtained on the laboratory bench. The microorganism growth kinetic is measured by image analysis. To improve the detection of algae on the surface of the cementitious samples, the raw image is converted in the YIQ color space. Y, I and Q correspond respectively to luminance, in-phase, and quadrature. On the Q channel, the areas covered by algae and the areas of clean mortar

  6. Natural Underwater Adhesives.

    PubMed

    Stewart, Russell J; Ransom, Todd C; Hlady, Vladimir

    2011-06-01

    The general topic of this review is protein-based underwater adhesives produced by aquatic organisms. The focus is on mechanisms of interfacial adhesion to native surfaces and controlled underwater solidification of natural water-borne adhesives. Four genera that exemplify the broad range of function, general mechanistic features, and unique adaptations are discussed in detail: blue mussels, acorn barnacles, sandcastle worms, and freshwater caddisfly larva. Aquatic surfaces in nature are charged and in equilibrium with their environment, populated by an electrical double layer of ions as well as adsorbed natural polyelectrolytes and microbial biofilms. Surface adsorption of underwater bioadhesives likely occurs by exchange of surface bound ligands by amino acid sidechains, driven primarily by relative affinities and effective concentrations of polymeric functional groups. Most aquatic organisms exploit modified amino acid sidechains, in particular phosphorylated serines and hydroxylated tyrosines (dopa), with high-surface affinity that form coordinative surface complexes. After delivery to the surfaces as a fluid, permanent natural adhesives solidify to bear sustained loads. Mussel plaques are assembled in a manner superficially reminiscent of in vitro layer-by-layer strategies, with sequentially delivered layers associated through Fe(dopa)(3) coordination bonds. The adhesives of sandcastle worms, caddisfly larva, and barnacles may be delivered in a form somewhat similar to in vitro complex coacervation. Marine adhesives are secreted, or excreted, into seawater that has a significantly higher pH and ionic strength than the internal environment. Empirical evidence suggests these environment triggers could provide minimalistic, fail-safe timing mechanisms to prevent premature solidification (insolubilization) of the glue within the secretory system, yet allow rapid solidification after secretion. Underwater bioadhesives are further strengthened by secondary covalent

  7. Natural Underwater Adhesives

    PubMed Central

    Stewart, Russell J.; Ransom, Todd C.; Hlady, Vladimir

    2011-01-01

    The general topic of this review is protein-based underwater adhesives produced by aquatic organisms. The focus is on mechanisms of interfacial adhesion to native surfaces and controlled underwater solidification of natural water-borne adhesives. Four genera that exemplify the broad range of function, general mechanistic features, and unique adaptations are discussed in detail: blue mussels, acorn barnacles, sandcastle worms, and freshwater caddisfly larva. Aquatic surfaces in nature are charged and in equilibrium with their environment, populated by an electrical double layer of ions as well as adsorbed natural polyelectrolytes and microbial biofilms. Surface adsorption of underwater bioadhesives likely occurs by exchange of surface bound ligands by amino acid sidechains, driven primarily by relative affinities and effective concentrations of polymeric functional groups. Most aquatic organisms exploit modified amino acid sidechains, in particular phosphorylated serines and hydroxylated tyrosines (dopa), with high-surface affinity that form coordinative surface complexes. After delivery to the surfaces as a fluid, permanent natural adhesives solidify to bear sustained loads. Mussel plaques are assembled in a manner superficially reminiscent of in vitro layer-by-layer strategies, with sequentially delivered layers associated through Fe(dopa)3 coordination bonds. The adhesives of sandcastle worms, caddisfly larva, and barnacles may be delivered in a form somewhat similar to in vitro complex coacervation. Marine adhesives are secreted, or excreted, into seawater that has a significantly higher pH and ionic strength than the internal environment. Empirical evidence suggests these environment triggers could provide minimalistic, fail-safe timing mechanisms to prevent premature solidification (insolubilization) of the glue within the secretory system, yet allow rapid solidification after secretion. Underwater bioadhesives are further strengthened by secondary covalent

  8. Adhesion of bile-adapted Bifidobacterium strains to the HT29-MTX cell line is modified after sequential gastrointestinal challenge simulated in vitro using human gastric and duodenal juices.

    PubMed

    de los Reyes-Gavilán, Clara G; Suárez, Adolfo; Fernández-García, María; Margolles, Abelardo; Gueimonde, Miguel; Ruas-Madiedo, Patricia

    2011-06-01

    According to the FAO/WHO, in vitro criteria for selection of probiotics for food application consist of testing survival when confronted with gastrointestinal tract (GIT) challenge and the ability to colonize the colon. We used a model that simulated GIT transit using sequential immersion in gastric and duodenal juices of human origin to evaluate survival of bile-adapted Bifidobacterium strains. Bifidobacterium animalis tolerated gastric juice, whereas Bifidobacterium longum showed poor survival under these conditions. In contrast, B. animalis strains were more sensitive to duodenal juice than B. longum. The percentage of survival after GIT transit simulation (GITTS), determined both by plate counts and fluorescent probes, was significantly higher for bile-adapted strains than for corresponding parental ones. This suggests that use of bile-adapted strains is a suitable approach for increasing survival of bifidobacteria under the harsh conditions of the upper GIT. However, the bile resistance phenotype was not related to improvement of adhesion capacity, after GITTS, of the intestinal cell line HT29-MTX which constitutively produces mucus. This work shows that sequential GITTS with human juices modified the in vitro adhesion properties of the strains challenged with colonocyte-like cells.

  9. Utilization of ground waste seashells in cement mortars for masonry and plastering.

    PubMed

    Lertwattanaruk, Pusit; Makul, Natt; Siripattarapravat, Chalothorn

    2012-11-30

    In this research, four types of waste seashells, including short-necked clam, green mussel, oyster, and cockle, were investigated experimentally to develop a cement product for masonry and plastering. The parameters studied included water demand, setting time, compressive strength, drying shrinkage and thermal conductivity of the mortars. These properties were compared with those of a control mortar that was made of a conventional Portland cement. The main parameter of this study was the proportion of ground seashells used as cement replacement (5%, 10%, 15%, or 20% by weight). Incorporation of ground seashells resulted in reduced water demand and extended setting times of the mortars, which are advantages for rendering and plastering in hot climates. All mortars containing ground seashells yielded adequate strength, less shrinkage with drying and lower thermal conductivity compared to the conventional cement. The results indicate that ground seashells can be applied as a cement replacement in mortar mixes and may improve the workability of rendering and plastering mortar.

  10. Plastic shrinkage of mortars with shrinkage reducing admixture and lightweight aggregates studied by neutron tomography

    SciTech Connect

    Wyrzykowski, Mateusz; Trtik, Pavel; Münch, Beat; Weiss, Jason; Vontobel, Peter; Lura, Pietro

    2015-07-15

    Water transport in fresh, highly permeable concrete and rapid water evaporation from the concrete surface during the first few hours after placement are the key parameters influencing plastic shrinkage cracking. In this work, neutron tomography was used to determine both the water loss from the concrete surface due to evaporation and the redistribution of fluid that occurs in fresh mortars exposed to external drying. In addition to the reference mortar with a water to cement ratio (w/c) of 0.30, a mortar with the addition of pre-wetted lightweight aggregates (LWA) and a mortar with a shrinkage reducing admixture (SRA) were tested. The addition of SRA reduced the evaporation rate from the mortar at the initial stages of drying and reduced the total water loss. The pre-wetted LWA released a large part of the absorbed water as a consequence of capillary pressure developing in the fresh mortar due to evaporation.

  11. Filler effect of fine particle sand on the compressive strength of mortar

    NASA Astrophysics Data System (ADS)

    Jaturapitakkul, Chai; Tangpagasit, Jatuphon; Songmue, Sawang; Kiattikomol, Kraiwood

    2011-04-01

    The river sand, which is a non-pozzolanic material, was ground into 3 different particle sizes. Portland cement type I was replaced by the ground river sands at 10wt%-40wt% of binder to cast mortar. Compressive strengths of mortar were investigated and the filler effect of different fine particles of sand on the compressive strength of mortar was evaluated. The results show that the compressive strength of mortar contributed from the filler effect of smaller particles is higher than that of the coarser ones. The difference in compressive strength of mortar tends to be greater as the difference in ground river sand fineness increases. The results also suggest that ASTM C618 specification is not practically suitable for specifying pozzolan in concrete since the strength activity index of mortar containing ground river sand (high crystalline phase) with 33.8wt% of particles retained on a 45-μm sieve can pass the strength requirement.

  12. Behavior of gypsum-based mortars with silica fume at high temperatures

    NASA Astrophysics Data System (ADS)

    Krejsová, Jitka; Doleželová, Magdaléna; Vimmrová, Alena

    2017-07-01

    The influence of high temperatures on the ternary and binary gypsum-based mortars is described. The gypsum-based mortar with ternary binder, composed from gypsum, hydrated lime and silica fume and mortar with binary binder, composed from gypsum and hydrated lime only were exposed to the temperatures from 50°C to 1000°C and their physical and mechanical properties were investigated. The comparison of ternary mortars and mortars without silica fume was carried out. The results were also compared with the results obtained from previous testing of gypsum-based pastes without sand. It was found, that gypsum-based mortars have better stability than gypsum-based materials without sand. Ternary materials have better volume stability than materials without pozzolan (about 5 % at 1000 °C).

  13. Effect of some biotic factors on microbially-induced calcite precipitation in cement mortar.

    PubMed

    Al-Salloum, Yousef; Abbas, H; Sheikh, Q I; Hadi, S; Alsayed, Saleh; Almusallam, Tarek

    2017-02-01

    Sporosarcina pasteurii, a common soil bacterium has been tested for microbial treatment of cement mortar. The present study also seeks to investigate the effects of growth medium, bacterial concentration and different buffers concerning the preparation of bacterial suspensions on the compressive strength of cement mortar. Two growth media, six different suspensions and two bacterial concentrations were used in the study. The influence of growth medium on calcification efficiency of S. pasteurii was insignificant. Significant improvement in the compressive as well as the tensile strength of cement mortar was observed. Microbial mineral precipitation visualized by Scanning Electron Microscopy (SEM) shows fibrous material that increased the strength of cement mortar. Formation of thin strands of fillers observed through SEM micrographs improves the pore structure, impermeability and thus the compressive as well as the tensile strengths of the cement mortar. The type of substrate and its molarity have a significant influence on the strength of cement mortar.

  14. Strength, porosity, and chloride resistance of mortar using the combination of two kinds of pozzolanic materials

    NASA Astrophysics Data System (ADS)

    Rukzon, Sumrerng; Chindaprasirt, Prinya

    2013-08-01

    This article presents a study on the resistance to chloride penetration, corrosion, porosity, and strength of mortar containing fine fly ash (FA), ground rice husk-bark ash (RB), and ground bagasse ash (BA). Ordinary Portland cement (CT) was blended with a single pozzolan and two pozzolans. Strength, porosity, rapid chloride penetration, immersion, and corrosion tests were performed to characterize the mortar. Test results showed that the use of ternary blends of CT, FA, and RB or BA decreased the porosity of the mortar, as compared with binary blended mortar containing CT and RB or BA. The resistance to chloride penetration of the mortar improved substantially with partial replacement of CT with FA, RB, and BA. The use of ternary blends of CT, FA and RB or BA produced the mortar with good strength and resistance to chloride penetration. The resistance to chloride penetration was higher with an increase in the replacement level due to the reduced calcium hydroxide.

  15. Claudin-5 regulates blood-brain barrier permeability by modifying brain microvascular endothelial cell proliferation, migration, and adhesion to prevent lung cancer metastasis.

    PubMed

    Ma, Shun-Chang; Li, Qi; Peng, Jia-Yi; Zhouwen, Jian-Long; Diao, Jin-Fu; Niu, Jian-Xing; Wang, Xi; Guan, Xiu-Dong; Jia, Wang; Jiang, Wen-Guo

    2017-09-29

    To investigate the roles of Claudin-5 (CLDN5) in regulating the permeability of the blood-brain barrier (BBB) during lung cancer brain metastasis. By silencing and overexpressing the CLDN5 gene in human brain vascular endothelial (hCMEC/D3) cells, we demonstrated the attenuation of cell migration ability and CLDN5's significant positive role in cell proliferation in CLDN5-overexpressing hCMEC/D3 cells and observed the opposite result in the CLDN5 knockdown group. The reinforced CLDN5 expression reduced the paracellular permeability of hCMEC/D3 cells and decreased the invasion of lung adenocarcinoma A549 cells. Overall, 1685 genes were found to be differentially expressed between the CLDN5-overexpressing cells and the control cells using the Affymetrix Human Transcriptome Array 2.0 (HTA 2.0), and the function of these genes was determined by Gene Ontology and pathway analyses. The possible biological functions of the 1685 genes include cell proliferation, adhesion molecules, and the Jak-STAT, PI3K-Akt, Wnt, and Notch signaling pathways. The identified sets of mRNAs that were specific to CLDN5-overexpressing hCMEC/D3 cells were verified by a qRT-PCR experiment. CLDN5 regulates the permeability of BBB by regulating the proliferation, migration, and permeability of hCMEC/D3 cells, especially through the cell adhesion molecule signaling pathway, to enhance the function of the tight junctions, which was involved in reducing the formation of lung cancer brain metastasis. © 2017 John Wiley & Sons Ltd.

  16. 120-MM Cargo Mortar Bombs-Complying with the Modern Battlefield Needs

    DTIC Science & Technology

    2001-04-01

    1 ISRAEL MILITARY INDUSTRIES LTD. (I.M.I.) Ammunition Group 120-MM CARGO MORTAR BOMBS - COMPLYING WITH THE MODERN BATTLEFIELD NEEDS Presented by Ltc...MM Cargo Mortar Bombs -Complying with the Modern Battlefield Needs Contract Number Grant Number Program Element Number Author(s) Eis, Mottie...Ammunition Group 120-MM CARGO MORTAR BOMB M971 MODE OF OPERATION FUZE FUNCTIONING EXPULSION OF PAYLOAD GAS-GENERATOR FUNCTIONINGDIESPERSION OF

  17. A three-level BDDC algorithm for Mortar discretizations

    SciTech Connect

    Kim, H.; Tu, X.

    2007-12-09

    In this paper, a three-level BDDC algorithm is developed for the solutions of large sparse algebraic linear systems arising from the mortar discretization of elliptic boundary value problems. The mortar discretization is considered on geometrically non-conforming subdomain partitions. In two-level BDDC algorithms, the coarse problem needs to be solved exactly. However, its size will increase with the increase of the number of the subdomains. To overcome this limitation, the three-level algorithm solves the coarse problem inexactly while a good rate of convergence is maintained. This is an extension of previous work, the three-level BDDC algorithms for standard finite element discretization. Estimates of the condition numbers are provided for the three-level BDDC method and numerical experiments are also discussed.

  18. Compressive strength of concrete and mortar containing fly ash

    DOEpatents

    Liskowitz, J.W.; Wecharatana, M.; Jaturapitakkul, C.; Cerkanowicz, A.E.

    1998-12-29

    The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention includes a method for predicting the compressive strength of such a hardenable mixture, which is very important for planning a project. The invention also relates to hardenable mixtures comprising cement and fly ash which can achieve greater compressive strength than hardenable mixtures containing only concrete over the time period relevant for construction. In a specific embodiment, a formula is provided that accurately predicts compressive strength of concrete containing fly ash out to 180 days. In other specific examples, concrete and mortar containing about 15% to 25% fly ash as a replacement for cement, which are capable of meeting design specification required for building and highway construction, are provided. Such materials can thus significantly reduce construction costs. 33 figs.

  19. Compressive strength of concrete and mortar containing fly ash

    DOEpatents

    Liskowitz, John W.; Wecharatana, Methi; Jaturapitakkul, Chai; Cerkanowicz, deceased, Anthony E.

    1998-01-01

    The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention includes a method for predicting the compressive strength of such a hardenable mixture, which is very important for planning a project. The invention also relates to hardenable mixtures comprising cement and fly ash which can achieve greater compressive strength than hardenable mixtures containing only concrete over the time period relevant for construction. In a specific embodiment, a formula is provided that accurately predicts compressive strength of concrete containing fly ash out to 180 days. In other specific examples, concrete and mortar containing about 15% to 25% fly ash as a replacement for cement, which are capable of meeting design specification required for building and highway construction, are provided. Such materials can thus significantly reduce construction costs.

  20. Compressive strength of concrete and mortar containing fly ash

    DOEpatents

    Liskowitz, J.W.; Wecharatana, M.; Jaturapitakkul, C.; Cerkanowicz, A.E.

    1997-04-29

    The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention includes a method for predicting the compressive strength of such a hardenable mixture, which is very important for planning a project. The invention also relates to hardenable mixtures comprising cement and fly ash which can achieve greater compressive strength than hardenable mixtures containing only concrete over the time period relevant for construction. In a specific embodiment, a formula is provided that accurately predicts compressive strength of concrete containing fly ash out to 180 days. In other specific examples, concrete and mortar containing about 15% to 25% fly ash as a replacement for cement, which are capable of meeting design specifications required for building and highway construction, are provided. Such materials can thus significantly reduce construction costs. 33 figs.

  1. Compressive strength of concrete and mortar containing fly ash

    DOEpatents

    Liskowitz, John W.; Wecharatana, Methi; Jaturapitakkul, Chai; Cerkanowicz, deceased, Anthony E.

    1997-01-01

    The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention includes a method for predicting the compressive strength of such a hardenable mixture, which is very important for planning a project. The invention also relates to hardenable mixtures comprising cement and fly ash which can achieve greater compressive strength than hardenable mixtures containing only concrete over the time period relevant for construction. In a specific embodiment, a formula is provided that accurately predicts compressive strength of concrete containing fly ash out to 180 days. In other specific examples, concrete and mortar containing about 15% to 25% fly ash as a replacement for cement, which are capable of meeting design specifications required for building and highway construction, are provided. Such materials can thus significantly reduce construction costs.

  2. Ancient gypsum mortars from Cyprus: characterization and reinvention

    NASA Astrophysics Data System (ADS)

    Theodoridou, M.; Ioannou, I.

    2012-04-01

    Mortars with various binding materials have been used across different pre-historic and historic periods to meet several construction applications, such as jointing masonry blocks, finishing walls and isolating water bearing structures. In the framework of an ongoing research programme (NEA ΥΠOΔOMH/NEKΥΠ/0308/17) funded by the Cyprus Research Promotion Foundation, the Republic of Cyprus and the European Union Regional Development Fund, 25 samples of gypsum mortars from different archaeological sites in Cyprus were collected and characterized following a systematic analytical approach. Petrographic observations of thin sections were carried out using polarizing optical microscope. Scanning electron microscopy equipped with energy dispersive X-ray microanalyser (SEM-EDX) was used to examine the microstructure and texture of the mortar samples and to determine semi-quantitatively the chemical composition and interface of their binders. X-ray diffraction (XRD) was performed to identify the main mineral crystalline phases of the specimens' binder and aggregates. Thermal analyses (TG/DTA) were used as a further confirmation of the material composition. The pore structure and volume of the ancient mortars were also determined by mercury intrusion porosimetry (MIP) analysis. Last but not least, a portable drilling resistance measurement system (DRMS) was used for micro-destructive assessment of the mechanical state of the samples. The results confirmed the predominant presence of hydrous calcium sulphate in all samples. Calcite was also found both in the binder and aggregates. Small proportions of SiO2 were also detected. The common ratio of binder to aggregates was 1:2.5. MIP showed porosity values between 14-48% and real densities between 1-1.7 g/cm3. The average pore diameters were smaller in the case of mortars with lower porosity. The use of DRMS indicated lower resistance to drilling for the case of joint mortars (as opposed to analysed gypsum plasters). This

  3. Leachability of regulated metals from cement-mortar linings

    SciTech Connect

    Guo, Q.; Toomuluri, P.J.; Eckert, J.O. Jr.

    1998-03-01

    A laboratory study was conducted to test the leachability of regulated metals from cement-mortar linings inside drinking water pipes. Faucet water of known quality was introduced in the test pipes and maintained in static, pressurized conditions for extended periods of time. Water samples were frequently drawn from the pipes and tested for metals and other water quality parameters during the test periods. Significant amounts of barium, cadmium, and chromium leached out from the cement-mortar linings in two of the three test pipes during the first 14 days of water stagnation. Barium and chromium continued to leach out at detectable levels as the pipes were subsequently refilled. The authors recommend that the water industry be selective in choosing cement for lining pipes.

  4. Studies on degradation of lime mortars in atmospheric simulation chambers

    SciTech Connect

    Martinez-Ramirez, S.; Puertas, F.; Blanco-Varela, M.T.; Thompson, G.E.

    1997-05-01

    It is well known that the presence of pollution increases the degradation of some building materials. In order to understand the influence of individual pollutants as well as the role of oxidants and water in lime mortar degradation, those materials have been exposed in atmospheric simulation chambers. According to the pollutants used in the chambers (NO, NO{sub 2} and SO{sub 2}), NO{sub 2}{sup {minus}} and NO{sub 3}{sup {minus}} or SO{sub 3}{sup 2{minus}} and SO{sub 4}{sup 2{minus}} have been analyzed and related with the reaction between the lime mortar and the pollutant. The reactivity order of the different pollutant (NO, NO{sub 2} and SO{sub 2}), in presence and absence of water and/or oxidant has been determined.

  5. Nonconforming mortar element methods: Application to spectral discretizations

    NASA Technical Reports Server (NTRS)

    Maday, Yvon; Mavriplis, Cathy; Patera, Anthony

    1988-01-01

    Spectral element methods are p-type weighted residual techniques for partial differential equations that combine the generality of finite element methods with the accuracy of spectral methods. Presented here is a new nonconforming discretization which greatly improves the flexibility of the spectral element approach as regards automatic mesh generation and non-propagating local mesh refinement. The method is based on the introduction of an auxiliary mortar trace space, and constitutes a new approach to discretization-driven domain decomposition characterized by a clean decoupling of the local, structure-preserving residual evaluations and the transmission of boundary and continuity conditions. The flexibility of the mortar method is illustrated by several nonconforming adaptive Navier-Stokes calculations in complex geometry.

  6. Characterization and restoration of historic Rosendale cement mortars for the purpose of restoration

    NASA Astrophysics Data System (ADS)

    Hart, Stephanie Anne

    Mortar was a very common building material in today's historic sites. Before Portland cement was manufactured at a global level, Rosendale cement was commonly used in these mortars. Over time, these mortars in historic sites have begun to break down and wear away. With Rosendale cement in production again, measures can be taken to restore and repair the historic mortars. However, little testing has been done to establish durability of modern Rosendale cement mortars. This presentation highlights the common mix techniques used at the time, and undergoes experiments to establish general properties and predict future durability. Six different mortar mixes were tested with varying cement content and using various lime additions. Properties observed include compressive strength, absorption, porosity, permeability, and bond strength. Ion chromatography was used on seawater-soaked samples to determine how the Rosendale cement mortar would react with the seawater. Relationships between these properties were also addressed. It was found that cement content played a large role in compressive strength, while lime content had an effect on bond strength. Ion chromatography was used on seawater-soaked samples to determine how the Rosendale cement mortar would react with the seawater. Magnesium sulfates, and chloride were taken up into the mortars, indicating that Rosendale would be venerable to salt attack.

  7. Influence of aggregate type and chemical admixtures on frost resistance of lightweight mortars

    NASA Astrophysics Data System (ADS)

    Klimek, Beata; Widomski, Marcin K.; Barnat-Hunek, Danuta

    2017-07-01

    The aim of studies presented in this paper covered analyses of type of lightweight aggregate as well as aeration and hydrophobic admixtures influence on absorbability and frost resistance of heat-insulating mortars applied in the energy-efficient construction. In the presented research, expanded perlite (EP) and expanded clay aggregate (ceramsite) were used as lightweight aggregates. The measurements of the basic mechanical and physical characteristics of tested mortars were performed, including, inter alia, compressive and flexural tensile strength, density, effective (open) and total porosity, absorbability, thermal conductivity as well as frost resistance after 25 cycles of freezing and thawing. Substitution of some part of sand fraction by the lightweight aggregates, expanded clay aggregate or perlite, resulted in changes in physical properties of the tested mortars. The observed decrease in density (specific weight), coefficient of heat transport and strength parameters were simultaneously accompanied by the increase in absorbability. Researches concerning frost resistance of mortars containing ceramsite and perlite showed the improved frost resistance of mortar utilizing perlite. Most of the tested mortars shoved satisfactory frost resistance, only samples of mortar containing ceramsite and aeration admixture were destroyed. The significant influence of aerating admixture on frost resistance of mortars was determined. Hydrophobic siloxanes addition failed to adequately protect the mortars against frost erosion, regardless the type of applied aggregate.

  8. Analysis of main parameters affecting substrate/mortar contact area through tridimensional laser scanner.

    PubMed

    Stolz, Carina M; Masuero, Angela B

    2015-10-01

    This study assesses the influence of the granulometric composition of sand, application energy and the superficial tension of substrates on the contact area of rendering mortars. Three substrates with distinct wetting behaviors were selected and mortars were prepared with different sand compositions. Characterization tests were performed on fresh and hardened mortars, as well as the rheological characterization. Mortars were applied to substrates with two different energies. The interfacial area was then digitized with 3D scanner. Results show that variables are all of influence on the interfacial contact in the development area. Furthermore, 3D laser scanning proved to be a good method to contact area measurement.

  9. Adsorption of cesium on cement mortar from aqueous solutions.

    PubMed

    Volchek, Konstantin; Miah, Muhammed Yusuf; Kuang, Wenxing; DeMaleki, Zack; Tezel, F Handan

    2011-10-30

    The adsorption of cesium on cement mortar from aqueous solutions was studied in series of bench-scale tests. The effects of cesium concentration, temperature and contact time on process kinetics and equilibrium were evaluated. Experiments were carried out in a range of initial cesium concentrations from 0.0103 to 10.88 mg L(-1) and temperatures from 278 to 313 K using coupons of cement mortar immersed in the solutions. Non-radioactive cesium chloride was used as a surrogate of the radioactive (137)Cs. Solution samples were taken after set periods of time and analyzed by inductively coupled plasma mass spectroscopy. Depending on the initial cesium concentration, its equilibrium concentration in solution ranged from 0.0069 to 8.837 mg L(-1) while the respective surface concentration on coupons varied from 0.0395 to 22.34 μg cm(-2). Equilibrium test results correlated well with the Freundlich isotherm model for the entire test duration. Test results revealed that an increase in temperature resulted in an increase in adsorption rate and a decrease in equilibrium cesium surface concentration. Among several kinetic models considered, the pseudo-second order reaction model was found to be the best to describe the kinetic test results in the studied range of concentrations. The adsorption activation energy determined from Arrhenius equation was found to be approximately 55.9 kJ mol(-1) suggesting that chemisorption was the prevalent mechanism of interaction between cesium ions and cement mortar.

  10. Properties of Cement Mortar Containing Rubber Ash as Sand Replacement

    NASA Astrophysics Data System (ADS)

    Syamir Senin, Mohamad; Shahidan, Shahiron; Syazani Leman, Alif; Izzati Raihan Ramzi Hannan, Nurul

    2016-11-01

    Discarded scrap tyres have become one of the major environmental problems nowadays. There has been increasing public worry about the mining of natural resources in recent years. In order to minimize the consumption of natural resources, rubber ash has been postulated as a potential material for partial replacement of sand in concrete materials especially for applications which are subjected to impact and vibration such as road and bridge construction. Thus, it contributes to the development of the construction industry in a sustainable way. This paper mainly emphasizes on the use of rubber ash from waste tyres in cement mortar. 100mm cubic specimens were produced by adding rubber ash volume ratios of 0%, 3%, 5% and 7% as sand replacement in M30 quality cement mortar. A compressive stress test and a density test were conducted at the end of 7, 14, and 28 days. The result shows that 5% is the optimum value for sand replacement in the cement mortar. Therefore, rubber ash is acceptable to be used as sand replacement.

  11. Cement-mortar pipes as a source of aluminum

    SciTech Connect

    Berend, K.; Trouwborst, T.

    1999-07-01

    In 1996 in Curacao, acute aluminum (Al) intoxication sickened patients in a dialysis center that used tap water to prepare dialysate. The mortality rate was 32%. A new factory-lined cement-mortar water distribution pipe had recently been installed. It is known that substantial amounts of barium, cadmium, and chromium can leach from cement-mortar linings. This article shows that high concentrations of Al can leach from cement mortars for at least two years in soft, aggressive water. The newly installed pipe, cement containing four times as much Al as usual, corrosive water, the high pH and temperature of the water, long residence time, and perhaps the corrosion inhibitor polyphosphate may have promoted this leaching. Certification of cements used to line water pipes is warranted. Central water treatment plants must distribute noncorrosive water, especially plants that use membrane desalination or other reverse osmosis or nanofiltration processes. Dialysis units should be promptly informed of any impending change in water treatment that might increase the Al content of tap water and also of any accidental pollution of the water distributed. Dialysis centers should always practice extended purification of tap water used for dialysate. Although Al as a risk factor for Alzheimer`s disease in the general population is still debated, there is no doubt that Al causes dialysis encephalopathy.

  12. Fatigue behaviour analysis for the durability prequalification of strengthening mortars

    NASA Astrophysics Data System (ADS)

    Bocca, P.; Grazzini, A.; Masera, D.

    2011-07-01

    An innovative laboratory procedure used as a preliminary design stage for the pre-qualification of strengthening mortars applied to historical masonry buildings is described. In the analysis of the behaviour of masonry structures and their constituent materials, increasing importance has been assumed by the study of the long-term evolution of deformation and mechanical characteristics, which may be affected by both loading and environmental conditions. Through static and fatigue tests on mixed specimens historical brick-reinforced mortar it has been possible to investigate the durability of strengthening materials, in order to select, from a range of alternatives, the most suitable for the historical masonry. Cyclic fatigue stress has been applied to accelerate the static creep and to forecast the corresponding creep behaviour of the historical brick-strengthening mortar system under static long-time loading. This methodology has proved useful in avoiding the errors associated with materials that are not mechanically compatible and guarantees the durability of strengthening work. The experimental procedure has been used effectively in the biggest restoration building site in Europe, the Royal Palace of Venaria, and it is in progress of carrying out at the Special Natural Reserve of the Sacro Monte di Varallo, in Piedmont (Italy).

  13. The Interfacial Transition Zone in Alkali-Activated Slag Mortars

    NASA Astrophysics Data System (ADS)

    San Nicolas, Rackel; Provis, John

    2015-12-01

    The interfacial transition zone (ITZ) is known to strongly influence the mechanical and transport properties of mortars and concretes. This paper studies the ITZ between siliceous (quartz) aggregates and alkali activated slag binders in the context of mortar specimens. Backscattered electron images (BSE) generated in an environmental scanning electron microscope (ESEM) are used to identify unreacted binder components, reaction products and porosity in the zone surrounding aggregate particles, by composition and density contrast. X-ray mapping is used to exclude the regions corresponding to the aggregates from the BSE image of the ITZ, thus enabling analysis of only the binder phases, which are segmented into binary images by grey level discrimination. A distinct yet dense ITZ region is present in the alkali-activated slag mortars, containing a reduced content of unreacted slag particles compared to the bulk binder. The elemental analysis of this region shows that it contains a (C,N)-A-S-H gel which seems to have a higher content of Na (potentially deposited through desiccation of the pore solution) and a lower content of Ca than the bulk inner and outer products forming in the main binding region. These differences are potentially important in terms of long-term concrete performance, as the absence of a highly porous interfacial transition zone region is expected to provide a positive influence on the mechanical and transport properties of alkali-activated slag concretes.

  14. The Yield Behaviour of a Structural Adhesive Under Complex Loading

    DTIC Science & Technology

    1998-09-01

    adhesive FM73, based upon the Modified Drucker - Prager / Cap Plasticity model. This yield function was selected based on experiments on a test specimen...6 2.7 Modified Drucker - Prager /Cap Plasticity Model ...................................................... 7 3. FM73 ADHESIVE TESTING... adhesive yield function studies. Drucker - Prager [8,9,10] and modified Drucker - Prager /Cap Plasticity [8,9,10] yield criteria were also investigated as

  15. The genetically modified polysialylated form of neural cell adhesion molecule-positive cells for potential treatment of X-linked adrenoleukodystrophy.

    PubMed

    Jang, Jiho; Kim, Han-Soo; Kang, Joon Won; Kang, Hoon-Chul

    2013-01-01

    Cell transplantation of myelin-producing exogenous cells is being extensively explored as a means of remyelinating axons in X-linked adrenoleukodystrophy. We determined whether 3,3',5-Triiodo-L-thyronine (T3) overexpresses the ABCD2 gene in the polysialylated (PSA) form of neural cell adhesion molecule (NCAM)-positive cells and promotes cell proliferation and favors oligodendrocyte lineage differentiation. PSA-NCAM+ cells from newborn Sprague-Dawley rats were grown for five days on uncoated dishes in defined medium with or without supplementation of basic fibroblast growth factor (bFGF) and/or T3. Then, PSA-NCAM+ spheres were prepared in single cells and transferred to polyornithine/fibronectin-coated glass coverslips for five days to determine the fate of the cells according to the supplementation of these molecules. T3 responsiveness of ABCD2 was analyzed using real-time quantitative polymerase chain reaction, the growth and fate of cells were determined using 5-bromo-2-deoxyuridine incorporation and immunocytochemistry, respectively. Results demonstrated that T3 induces overexpression of the ABCD2 gene in PSA-NCAM+ cells, and can enhance PSA-NCAM+ cell growth in the presence of bFGF, favoring an oligodendrocyte fate. These results may provide new insights into investigation of PSA-NCAM+ cells for therapeutic application to X-linked adrenoleukodystrophy.

  16. Compatibility between silorane adhesive and simplified methacrylate-based adhesive systems.

    PubMed

    D'Alpino, Paulo Henrique Perlatti; de Farias, Natália Coelho; Silva, Marília Santos; de Goes, Mario Fernando; González, Alejandra Hortencia Miranda; Di Hipólito, Vinicius

    2013-01-01

    The purpose of this study was to evaluate the impact of replacing P90 primer with simplified adhesive systems (with a conventional, two-step adhesive or a self-etching, one-step adhesive) on bond strength to dentin in Class I restorations. The interfaces were also analyzed using confocal microscopy by adding a fluorophore to the adhesive components and SEM using silver nitrate for nanoleakage investigation. X-ray diffraction (XRD) characterized the chemical interaction of the adhesives. Failure mode and nanoleakage varied among groups. Characteristic micromorphology and higher nanoleakage were noted for silorane combinations. On the other hand, no signs of phase crystallization in the silorane adhesive combinations were noted. Replacing the silorane primer with simplified adhesives proved successful as the modified systems provided bonding to dentin comparable to that of the unmodified silorane systems. However, the dedicated adhesive exhibited signs of degradation immediately after application, which may impact the longevity of restorations in short periods.

  17. MBG-Modified β-TCP Scaffold Promotes Mesenchymal Stem Cells Adhesion and Osteogenic Differentiation via a FAK/MAPK Signaling Pathway.

    PubMed

    Liu, Yutong; Ma, Yifan; Zhang, Jing; Xie, Qing; Wang, Zi; Yu, Shuang; Yuan, Yuan; Liu, Changsheng

    2017-09-13

    The β-TCP scaffold has been widely used as a bone graft substitute, but the traditional PMMA molding method-induced undesirable mechanical strength and poor interconnectivity still have not been addressed until now. In this study, a MBG-based PU foam templating method was developed to fabricate β-TCP scaffolds with desirable microtopography. The MBG gel, as both binder and modifier, prepared by a modified sol-gel method with controlled viscosity is incorporated with β-TCP powder and thereafter is impregnated into PU foam. The resultant hybrid scaffolds exhibited interconnected macropores (200-500 μm) and distinctive micropores (0.2-1.5 μm), especially for the TCP/25MBG (with 25 wt % content MBG). As expected, the compression strength of β-TCP/MBG composite scaffolds was enhanced with increasing MBG content, and TCP/50MBG (with 50 wt % content MBG) exhibited almost 100-fold enhancement compared to the pure β-TCP. Intriguingly, the cell affinity and osteogenic capacity of rBMSCs were also dramatically improved the best on TCP/25MBG. Further investigation found that the subtle, grainy-like microtopography, not the chemical composition, of the TCP/25MBG favored the adsorption of Fn and expression of integrin α5β1 and further facilitated FA formation and the expression of p-FAK, following activation of the MAPK/ERK signaling pathway and ultimately upregulated expression of osteogenic genes. Further in vivo experiments confirmed the promoted osteogenesis of TCP/25MBG in vivo. The results suggest that such a novel MBG-based PU foam templating method offers new guidance to construct hierarchically porous scaffolds, and the prepared MBG-modified β-TCP scaffold will have great potential for future use in bone tissue regeneration.

  18. Polyimide adhesives

    NASA Technical Reports Server (NTRS)

    Progar, D. J.; Bell, V. L.; Stclair, T. L. (Inventor)

    1977-01-01

    A process was developed for preparing aromatic polyamide acids for use as adhesives by reacting an aromatic dianhydride to an approximately equimolar amount of an aromatic diamine in a water or lower alkanol miscible ether solvent. The polyamide acids are converted to polyimides by heating to the temperature range of 200 - 300 C. The polyimides are thermally stable and insoluble in ethers and other organic solvents.

  19. Adhesive plasters

    DOEpatents

    Holcombe, Jr., Cressie E.; Swain, Ronald L.; Banker, John G.; Edwards, Charlene C.

    1978-01-01

    Adhesive plaster compositions are provided by treating particles of Y.sub.2 O.sub.3, Eu.sub.2 O.sub.3, Gd.sub.2 O.sub.3 or Nd.sub.2 O.sub.3 with dilute acid solutions. The resulting compositions have been found to spontaneously harden into rigid reticulated masses resembling plaster of Paris. Upon heating, the hardened material is decomposed into the oxide, yet retains the reticulated rigid structure.

  20. Avirulent K88 (F4)+ Escherichia coli strains constructed to express modified enterotoxins protect young piglets from challenge with a virulent enterotoxigenic Escherichia coli strain that expresses the same adhesion and enterotoxins.

    PubMed

    Santiago-Mateo, Kristina; Zhao, Mojun; Lin, Jun; Zhang, Weiping; Francis, David H

    2012-10-12

    Virulence of enterotoxigenic Escherichia coli (ETEC) is associated with fimbrial adhesins and enterotoxins such as heat-labile (LT) and/or heat-stable (ST) enterotoxins. Previous studies using a cell culture model suggest that exclusion of ETEC from attachment to epithelial cells requires expression of both an adhesin such as K88 (F4) fimbriae, and LT. To test the ability of non-pathogenic E. coli constructs to exclude virulent ETEC sufficiently to prevent clinical disease, we utilized a piglet ETEC challenge model. Thirty-nine 5-day-old piglets were inoculated with a placebo (control), or with either of the three K88(+)E. coli strains isogenic with regard to modified LT expression: 8017 (pBR322 plasmid vector control), non-toxigenic mutant 8221 (LT(R192G)) in pBR322, or 8488, with the LT gene fused to the STb gene in pBR322 (LT(R192G)-STb). Piglets were challenged with virulent ETEC Strain 3030-2 (K88(+)/LT/STb) 24h post-inoculation. K88ac receptor-positive piglets in the control group developed diarrhea and became dehydrated 12-24h post-challenge. Piglets inoculated with 8221 or 8488 did not exhibit clinical signs of ETEC disease; most piglets inoculated with 8017 showed diarrhea. Control pigs exhibited significant weight loss, increased blood total protein, and higher numbers of colony-forming units of 3030-2 E. coli in washed ileum and jejunum than treated pigs. This study shows for the first time that pre-inoculation with an avirulent strain expressing adhesive fimbriae and a non-toxic form of LT provides significant short term protection from challenge with a virulent ETEC strain that expresses the same fimbrial adhesion and enterotoxin.

  1. Influence of recycled fine aggregates on the resistance of mortars to magnesium sulfate attack

    SciTech Connect

    Lee, Seung-Tae

    2009-08-15

    The influence of recycled fine aggregates, which had been reclaimed from field-demolished concretes, on the resistance of mortar specimens to magnesium sulfate attack was investigated. Mortar specimens were prepared with recycled fine aggregates at different replacement levels (0%, 25%, 50%, 75% and 100% of natural fine aggregate by mass). The mortar specimens were exposed to 4.24% magnesium sulfate solution for about 1 year at ambient temperature, and regularly monitored for visual appearance, compressive strength loss and expansion. Additionally, in order to identify products of magnesium sulfate attack, mortar samples incorporating 0%, 25% and 100% replacement levels of the recycled fine aggregates were examined by X-ray diffraction (XRD) technique. Experimental results confirmed that the use of recycled fine aggregates up to a maximum 50% replacement level is effective under severe magnesium sulfate environment, irrespective of type of recycled fine aggregates. However, the worse performance was observed in mortar specimens incorporating 100% replacement level. It was found that the water absorption of recycled fine aggregates affected deterioration of mortar specimens, especially at a higher replacement level. XRD results indicated that the main cause of deterioration of the mortar specimens was primarily due to the formation of gypsum and thaumasite by magnesium sulfate attack. In addition, it appeared that the conversion of C-S-H into M-S-H by the attack probably influenced mechanical deterioration of mortar specimens with recycled fine aggregates.

  2. Influence of Chloride-Ion Adsorption Agent on Chloride Ions in Concrete and Mortar.

    PubMed

    Peng, Gai-Fei; Feng, Nai-Qian; Song, Qi-Ming

    2014-04-30

    The influence of a chloride-ion adsorption agent (Cl agent in short), composed of zeolite, calcium aluminate hydrate and calcium nitrite, on the ingress of chloride ions into concrete and mortar has been experimentally studied. The permeability of concrete was measured, and the chloride ion content in mortar was tested. The experimental results reveal that the Cl agent could adsorb chloride ions effectively, which had penetrated into concrete and mortar. When the Cl agent was used at a dosage of 6% by mass of cementitious materials in mortar, the resistance to the penetration of chloride ions could be improved greatly, which was more pronounced when a combination of the Cl agent and fly ash or slag was employed. Such an effect is not the result of the low permeability of the mortar, but might be a result of the interaction between the Cl agent and the chloride ions penetrated into the mortar. There are two possible mechanisms for the interaction between the Cl agent and chloride ion ingress. One is the reaction between calcium aluminate hydrate in the Cl agent and chloride ions to form Friedel's salt, and the other one is that calcium aluminate hydrate reacts with calcium nitrite to form AFm during the early-age hydration of mortar and later the NO₂(-) in AFm is replaced by chloride ions, which then penetrate into the mortar, also forming Friedel's salt. More research is needed to confirm the mechanisms.

  3. Influence of Chloride-Ion Adsorption Agent on Chloride Ions in Concrete and Mortar

    PubMed Central

    Peng, Gai-Fei; Feng, Nai-Qian; Song, Qi-Ming

    2014-01-01

    The influence of a chloride-ion adsorption agent (Cl agent in short), composed of zeolite, calcium aluminate hydrate and calcium nitrite, on the ingress of chloride ions into concrete and mortar has been experimentally studied. The permeability of concrete was measured, and the chloride ion content in mortar was tested. The experimental results reveal that the Cl agent could adsorb chloride ions effectively, which had penetrated into concrete and mortar. When the Cl agent was used at a dosage of 6% by mass of cementitious materials in mortar, the resistance to the penetration of chloride ions could be improved greatly, which was more pronounced when a combination of the Cl agent and fly ash or slag was employed. Such an effect is not the result of the low permeability of the mortar, but might be a result of the interaction between the Cl agent and the chloride ions penetrated into the mortar. There are two possible mechanisms for the interaction between the Cl agent and chloride ion ingress. One is the reaction between calcium aluminate hydrate in the Cl agent and chloride ions to form Friedel’s salt, and the other one is that calcium aluminate hydrate reacts with calcium nitrite to form AFm during the early-age hydration of mortar and later the NO2− in AFm is replaced by chloride ions, which then penetrate into the mortar, also forming Friedel’s salt. More research is needed to confirm the mechanisms. PMID:28788625

  4. Alkali-silica reaction and pore solution composition in mortars in sea water

    SciTech Connect

    Kawamura, Mitsunori; Takeuchi, Katsunobu

    1996-12-01

    The promotion of expansion of mortars containing a reactive aggregate in 1N NaCl solution at 38 C was attributed to a rise of OH{sup {minus}} ion concentration in the pore solution in the mortars. However, it is ambiguous whether the promotion of expansion of mortars in sea water at a room temperature can be explained in the same way as in NaCl solution at an elevated temperature. This study aims at pursuing the expansion behavior of mortars containing a reactive aggregate relating it to their pore solution composition and the extent of alkali-silica reaction occurring within reactive grains. The alkali-silica reaction in mortars in sea water and 0.5 1N NaCl solution at 20 C appears to progress differently from that in mortars in 1N NaCl solution at an elevated temperature of 38 C. The promotion of expansion of mortars in sea water at 20 C was found to be responsible for an effect of Cl{sup {minus}} ions in the alkali-silica reaction at early stages of immersion. Only when OH{sup {minus}} ion concentration in the pore solution was relatively high, NaCl and sea water could accelerate the alkali-silica reaction in mortars at 20 C.

  5. Adhesive organ regeneration in Macrostomum lignano.

    PubMed

    Lengerer, Birgit; Hennebert, Elise; Flammang, Patrick; Salvenmoser, Willi; Ladurner, Peter

    2016-06-02

    Flatworms possess pluripotent stem cells that can give rise to all cell types, which allows them to restore lost body parts after injury or amputation. This makes flatworms excellent model systems for studying regeneration. In this study, we present the adhesive organs of a marine flatworm as a simple model system for organ regeneration. Macrostomum lignano has approximately 130 adhesive organs at the ventral side of its tail plate. One adhesive organ consists of three interacting cells: one adhesive gland cell, one releasing gland cell, and one modified epidermal cell, called an anchor cell. However, no specific markers for these cell types were available to study the regeneration of adhesive organs. We tested 15 commercially available lectins for their ability to label adhesive organs and found one lectin (peanut agglutinin) to be specific to adhesive gland cells. We visualized the morphology of regenerating adhesive organs using lectin- and antibody staining as well as transmission electron microscopy. Our findings indicate that the two gland cells differentiate earlier than the connected anchor cells. Using EdU/lectin staining of partially amputated adhesive organs, we showed that their regeneration can proceed in two ways. First, adhesive gland cell bodies are able to survive partial amputation and reconnect with newly formed anchor cells. Second, adhesive gland cell bodies are cleared away, and the entire adhesive organ is build anew. Our results provide the first insights into adhesive organ regeneration and describe ten new markers for differentiated cells and tissues in M. lignano. The position of adhesive organ cells within the blastema and their chronological differentiation have been shown for the first time. M. lignano can regenerate adhesive organs de novo but also replace individual anchor cells in an injured organ. Our findings contribute to a better understanding of organogenesis in flatworms and enable further molecular investigations of cell

  6. Corrosion Sensor for Monitoring the Service Condition of Chloride-Contaminated Cement Mortar

    PubMed Central

    Lu, Shuang; Ba, Heng-Jing

    2010-01-01

    A corrosion sensor for monitoring the corrosion state of cover mortar was developed. The sensor was tested in cement mortar, with and without the addition of chloride to simulate the adverse effects of chloride-contaminated environmental conditions on concrete structures. In brief, a linear polarization resistance method combined with an embeddable reference electrode was utilized to measure the polarization resistance (Rp) using built-in sensor electrodes. Subsequently, electrochemical impedance spectroscopy in the frequency range of 1 kHz to 50 kHz was used to obtain the cement mortar resistance (Rs). The results show that the polarization resistance is related to the chloride content and Rs; ln (Rp) is linearly related to the Rs values in mortar without added chloride. The relationships observed between the Rp of the steel anodes and the resistance of the surrounding cement mortar measured by the corrosion sensor confirms that Rs can indicate the corrosion state of concrete structures. PMID:22319347

  7. Corrosion sensor for monitoring the service condition of chloride-contaminated cement mortar.

    PubMed

    Lu, Shuang; Ba, Heng-Jing

    2010-01-01

    A corrosion sensor for monitoring the corrosion state of cover mortar was developed. The sensor was tested in cement mortar, with and without the addition of chloride to simulate the adverse effects of chloride-contaminated environmental conditions on concrete structures. In brief, a linear polarization resistance method combined with an embeddable reference electrode was utilized to measure the polarization resistance (Rp) using built-in sensor electrodes. Subsequently, electrochemical impedance spectroscopy in the frequency range of 1 kHz to 50 kHz was used to obtain the cement mortar resistance (Rs). The results show that the polarization resistance is related to the chloride content and Rs; ln (Rp) is linearly related to the Rs values in mortar without added chloride. The relationships observed between the Rp of the steel anodes and the resistance of the surrounding cement mortar measured by the corrosion sensor confirms that Rs can indicate the corrosion state of concrete structures.

  8. Amination of black liquor and the application in the ready-mixed wet mortar.

    PubMed

    Zheng, Dafeng; Zheng, Tao; Chen, Ran; Li, Xiaokang; Qiu, Xueqing

    2017-02-28

    In order to extend the application of black liquor (BL), amino group was introduced in lignin through Mannich reaction. The structure of the aminated black liquor (ABL) was characterized with FT-IR, elemental analysis, the zeta potential and the inherent viscosity. The foam generated by ABL was more stable, for the surface tension was lower. The results of the mortar test indicated that the water-retention rate of the fresh mortar incorporated with 0.3 wt% ABL was 89.1%; the consistency loss was about 39.7% after 4 h. When the dosage was less than 0.3 wt%, ABL could increase the bond strength of the hardened mortars. The results showed that ABL could be used as an effective ready-mixed wet mortar admixture. This study not only provided a new method to develop new mortar admixture, but also alleviated the pollution of BL.

  9. [Study on the traditional lime mortar from the memorial archway in the southern Anhui province].

    PubMed

    Wei, Guo-Feng; Sun, Sheng; Wang, Cheng-Xing; Zhang, Bing-Jian; Chen, Xi-Min

    2013-07-01

    The traditional lime mortar was investigated by means of scanning electron microscope (SEM), X-ray diffractometry and Fourier transform infrared spectrometry (FTIR). The results show that the mortar from the memorial archway in the southern Anhui province was the organic-inorganic composite materials composed of lime with tung oil or sticky rice. It was found that the excellent performance of the tung oil-lime mortar can be explained by the compact lamellar organic-inorganic composite structure that was produced by carbonization reaction of lime, cross-linking reactions of tung oil and oxygen and complexing reaction of Ca2+ and -COO-. The compact micro-structure of sticky rice-lime mortar, which was produced due to carbonation process of lime controlled by amylopectin, should be the cause of the good performance of this kind of organic-inorganic mortar.

  10. Cathodic protection of steel reinforced concrete facilitated by using carbon fiber reinforced mortar or concrete

    SciTech Connect

    Hou, J.; Chung, D.D.L.

    1997-05-01

    Due to the decrease in volume electrical resistivity associated with carbon fiber addition (0.35 vol.%) to concrete (embedding steel rebar), concrete containing carbon fibers and silica fume reduced by 18% the driving voltage required for cathodic protection compared to plain concrete, and by 28% compared to concrete with silica fume. Due to the decrease in resistivity associated with carbon fiber addition (1.1 vol.%) to mortar, overlay (embedding titanium wires for electrical contacts to steel reinforced concrete) in the form of mortar containing carbon fibers and latex reduced by the 10% the driving voltage required for cathodic protection, compared to plain mortar overlay. In spite of the low resistivity of mortar overlay with carbon fibers, cathodic protection required multiple metal electrical contacts embedded in the mortar at a spacing of 11 cm or less.

  11. Mechanical resilience and cementitious processes in Imperial Roman architectural mortar

    SciTech Connect

    Jackson, Marie D.; Landis, Eric N.; Brune, Philip F.; Vitti, Massimo; Chen, Heng; Li, Qinfei; Kunz, Martin; Wenk, Hans -Rudolf; Monteiro, Paulo J. M.; Ingraffea, Anthony R.

    2014-12-15

    The pyroclastic aggregate concrete of Trajan’s Markets (110 CE), now Museo Fori Imperiali in Rome, has absorbed energy from seismic ground shaking and long-term foundation settlement for nearly two millenia while remaining largely intact at the structural scale. The scientific basis of this exceptional service record is explored through computed tomography of fracture surfaces and synchroton X-ray microdiffraction analyses of a reproduction of the standardized hydrated lime–volcanic ash mortar that binds decimeter-sized tuff and brick aggregate in the conglomeratic concrete. The mortar reproduction gains fracture toughness over 180 d through progressive coalescence of calcium–aluminum-silicate–hydrate (C-A-S-H) cementing binder with Ca/(Si+Al) ≈ 0.8–0.9 and crystallization of strätlingite and siliceous hydrogarnet (katoite) at ≥90 d, after pozzolanic consumption of hydrated lime was complete. Platey strätlingite crystals toughen interfacial zones along scoria perimeters and impede macroscale propagation of crack segments. In the 1,900 year old mortar, C-A-S-H has low Ca/(Si+Al) ≈ 0.45–0.75. Dense clusters of 2- to 30-µm strätlingite plates further reinforce interfacial zones, the weakest link of modern cement-based concrete, and the cementitious matrix. These crystals formed during long-term autogeneous reaction of dissolved calcite from lime and the alkali-rich scoriae groundmass, clay mineral (halloysite), and zeolite (phillipsite and chabazite) surface textures from the Pozzolane Rosse pyroclastic flow, erupted from the nearby Alban Hills volcano. The clast-supported conglomeratic fabric of the concrete presents further resistance to fracture propagation at the structural scale.

  12. Mechanical resilience and cementitious processes in Imperial Roman architectural mortar.

    PubMed

    Jackson, Marie D; Landis, Eric N; Brune, Philip F; Vitti, Massimo; Chen, Heng; Li, Qinfei; Kunz, Martin; Wenk, Hans-Rudolf; Monteiro, Paulo J M; Ingraffea, Anthony R

    2014-12-30

    The pyroclastic aggregate concrete of Trajan's Markets (110 CE), now Museo Fori Imperiali in Rome, has absorbed energy from seismic ground shaking and long-term foundation settlement for nearly two millenia while remaining largely intact at the structural scale. The scientific basis of this exceptional service record is explored through computed tomography of fracture surfaces and synchroton X-ray microdiffraction analyses of a reproduction of the standardized hydrated lime-volcanic ash mortar that binds decimeter-sized tuff and brick aggregate in the conglomeratic concrete. The mortar reproduction gains fracture toughness over 180 d through progressive coalescence of calcium-aluminum-silicate-hydrate (C-A-S-H) cementing binder with Ca/(Si+Al) ≈ 0.8-0.9 and crystallization of strätlingite and siliceous hydrogarnet (katoite) at ≥ 90 d, after pozzolanic consumption of hydrated lime was complete. Platey strätlingite crystals toughen interfacial zones along scoria perimeters and impede macroscale propagation of crack segments. In the 1,900-y-old mortar, C-A-S-H has low Ca/(Si+Al) ≈ 0.45-0.75. Dense clusters of 2- to 30-µm strätlingite plates further reinforce interfacial zones, the weakest link of modern cement-based concrete, and the cementitious matrix. These crystals formed during long-term autogeneous reaction of dissolved calcite from lime and the alkali-rich scoriae groundmass, clay mineral (halloysite), and zeolite (phillipsite and chabazite) surface textures from the Pozzolane Rosse pyroclastic flow, erupted from the nearby Alban Hills volcano. The clast-supported conglomeratic fabric of the concrete presents further resistance to fracture propagation at the structural scale.

  13. Mechanical resilience and cementitious processes in Imperial Roman architectural mortar

    DOE PAGES

    Jackson, Marie D.; Landis, Eric N.; Brune, Philip F.; ...

    2014-12-15

    The pyroclastic aggregate concrete of Trajan’s Markets (110 CE), now Museo Fori Imperiali in Rome, has absorbed energy from seismic ground shaking and long-term foundation settlement for nearly two millenia while remaining largely intact at the structural scale. The scientific basis of this exceptional service record is explored through computed tomography of fracture surfaces and synchroton X-ray microdiffraction analyses of a reproduction of the standardized hydrated lime–volcanic ash mortar that binds decimeter-sized tuff and brick aggregate in the conglomeratic concrete. The mortar reproduction gains fracture toughness over 180 d through progressive coalescence of calcium–aluminum-silicate–hydrate (C-A-S-H) cementing binder with Ca/(Si+Al) ≈more » 0.8–0.9 and crystallization of strätlingite and siliceous hydrogarnet (katoite) at ≥90 d, after pozzolanic consumption of hydrated lime was complete. Platey strätlingite crystals toughen interfacial zones along scoria perimeters and impede macroscale propagation of crack segments. In the 1,900 year old mortar, C-A-S-H has low Ca/(Si+Al) ≈ 0.45–0.75. Dense clusters of 2- to 30-µm strätlingite plates further reinforce interfacial zones, the weakest link of modern cement-based concrete, and the cementitious matrix. These crystals formed during long-term autogeneous reaction of dissolved calcite from lime and the alkali-rich scoriae groundmass, clay mineral (halloysite), and zeolite (phillipsite and chabazite) surface textures from the Pozzolane Rosse pyroclastic flow, erupted from the nearby Alban Hills volcano. The clast-supported conglomeratic fabric of the concrete presents further resistance to fracture propagation at the structural scale.« less

  14. Mechanical resilience and cementitious processes in Imperial Roman architectural mortar

    PubMed Central

    Landis, Eric N.; Brune, Philip F.; Vitti, Massimo; Chen, Heng; Li, Qinfei; Kunz, Martin; Wenk, Hans-Rudolf; Monteiro, Paulo J. M.; Ingraffea, Anthony R.

    2014-01-01

    The pyroclastic aggregate concrete of Trajan’s Markets (110 CE), now Museo Fori Imperiali in Rome, has absorbed energy from seismic ground shaking and long-term foundation settlement for nearly two millenia while remaining largely intact at the structural scale. The scientific basis of this exceptional service record is explored through computed tomography of fracture surfaces and synchroton X-ray microdiffraction analyses of a reproduction of the standardized hydrated lime–volcanic ash mortar that binds decimeter-sized tuff and brick aggregate in the conglomeratic concrete. The mortar reproduction gains fracture toughness over 180 d through progressive coalescence of calcium–aluminum-silicate–hydrate (C-A-S-H) cementing binder with Ca/(Si+Al) ≈ 0.8–0.9 and crystallization of strätlingite and siliceous hydrogarnet (katoite) at ≥90 d, after pozzolanic consumption of hydrated lime was complete. Platey strätlingite crystals toughen interfacial zones along scoria perimeters and impede macroscale propagation of crack segments. In the 1,900-y-old mortar, C-A-S-H has low Ca/(Si+Al) ≈ 0.45–0.75. Dense clusters of 2- to 30-µm strätlingite plates further reinforce interfacial zones, the weakest link of modern cement-based concrete, and the cementitious matrix. These crystals formed during long-term autogeneous reaction of dissolved calcite from lime and the alkali-rich scoriae groundmass, clay mineral (halloysite), and zeolite (phillipsite and chabazite) surface textures from the Pozzolane Rosse pyroclastic flow, erupted from the nearby Alban Hills volcano. The clast-supported conglomeratic fabric of the concrete presents further resistance to fracture propagation at the structural scale. PMID:25512521

  15. Microwave evaluation of accelerated chloride ingress in mortar

    NASA Astrophysics Data System (ADS)

    Hu, C.; Case, T.; Castle, M.; Zoughi, R.; Kurtis, K.

    2001-04-01

    Corrosion of steel in reinforced concrete structures can be induced by the presence of chloride ions near the steel/concrete interface. To show the potential of microwave nondestructive testing techniques for evaluating chloride ingress, 8″×8″×8″ mortar specimens with different mixture designs were prepared. To accelerate chloride ingress, they were exposed to cyclical wet/dry conditions, where the wet condition included exposure to salt bath. A complete discussion of the results will be presented in this paper.

  16. Neutron and gamma attenuation in polyethylene and PVC mortars

    SciTech Connect

    Abdul-Majid, S.; Abulfaraj, W.H.; Othman, F. )

    1991-01-01

    Concrete is a basic building material widely used in radiation shielding. As water in ordinary concrete is only {approximately}6% by weight, fast neutrons undergo a medium to poor moderation process. Special types of mortar were developed in which polyethylene ((CH{sub 2})n) or PVC ((CH{sub 2}-CH-Cl)n) pellets were used instead of coarse aggregates in ordinary concrete. Both of these polymers are rich in hydrogen and carbon moderator atoms. Preparation methods and resulting material properties are discussed.

  17. Surface energy and viscoelasticity influence caramel adhesiveness.

    PubMed

    Wagoner, Ty B; Foegeding, Edward Allen

    2017-08-26

    Adhesion is an important textural attribute that directs consumer eating patterns and behaviors and can be a negative attribute during food processing. The objectives of this study were to modify caramel formulation and compare adhesion to different materials to quantify the influence of surface energetics and viscoelasticity on caramel adhesiveness. Mechanical adhesion was viewed in the context of pressure sensitive tack theory, where adhesion is controlled by viscoelasticity of the adhesive material and the surface energy relationship of material and probe. Caramel samples varied in total amount of fat and protein, and mechanical adhesion was measured using a series of materials with total surface energies of 39.7-53.2 mJ/m(2) . Adhesiveness decreased as fat and protein content increased, with a significant effect of total surface energy. Viscoelasticity was modeled using creep recovery data fit to a four-element Burger mechanistic model. Burger model parameters representing retarded elasticity correlated strongly with adhesiveness. The results suggest two zones of adhesion based on formulation, one driven by both surface energy relationships-most notably dispersive and total surface energy-and viscoelasticity, and the other driven solely by viscoelasticity. Relationships between mechanical properties and adhesion have been explored but are still not well understood, and could aid in the design of food products with a controlled level of adhesion. The results of this study indicate the importance of considering material surface energy when measuring mechanical adhesion or texture profile analysis. Understanding the relationships between viscoelastic behavior and adhesion can be used to make inferences on perceived texture. © 2017 Wiley Periodicals, Inc.

  18. Adhesion and Cohesion

    PubMed Central

    von Fraunhofer, J. Anthony

    2012-01-01

    The phenomena of adhesion and cohesion are reviewed and discussed with particular reference to dentistry. This review considers the forces involved in cohesion and adhesion together with the mechanisms of adhesion and the underlying molecular processes involved in bonding of dissimilar materials. The forces involved in surface tension, surface wetting, chemical adhesion, dispersive adhesion, diffusive adhesion, and mechanical adhesion are reviewed in detail and examples relevant to adhesive dentistry and bonding are given. Substrate surface chemistry and its influence on adhesion, together with the properties of adhesive materials, are evaluated. The underlying mechanisms involved in adhesion failure are covered. The relevance of the adhesion zone and its importance with regard to adhesive dentistry and bonding to enamel and dentin is discussed. PMID:22505913

  19. Dual-Mode Adhesive Pad

    NASA Technical Reports Server (NTRS)

    Hartz, Leslie

    1994-01-01

    Tool helps worker grip and move along large, smooth structure with no handgrips or footholds. Adheres to surface but easily released by actuating simple mechanism. Includes handle and segmented contact-adhesive pad. Bulk of pad made of soft plastic foam conforming to surface of structure. Each segment reinforced with rib. In sticking mode, ribs braced by side catches. In peeling mode, side catches retracted, and segmented adhesive pad loses its stiffness. Modified versions useful in inspecting hulls of ships and scaling walls in rescue operations.

  20. Dual-Mode Adhesive Pad

    NASA Technical Reports Server (NTRS)

    Hartz, Leslie

    1994-01-01

    Tool helps worker grip and move along large, smooth structure with no handgrips or footholds. Adheres to surface but easily released by actuating simple mechanism. Includes handle and segmented contact-adhesive pad. Bulk of pad made of soft plastic foam conforming to surface of structure. Each segment reinforced with rib. In sticking mode, ribs braced by side catches. In peeling mode, side catches retracted, and segmented adhesive pad loses its stiffness. Modified versions useful in inspecting hulls of ships and scaling walls in rescue operations.

  1. Effect of copolymer latexes on physicomechanical properties of mortar containing high volume fly ash as a replacement material of cement.

    PubMed

    Negim, El-Sayed; Kozhamzharova, Latipa; Gulzhakhan, Yeligbayeva; Khatib, Jamal; Bekbayeva, Lyazzat; Williams, Craig

    2014-01-01

    This paper investigates the physicomechanical properties of mortar containing high volume of fly ash (FA) as partial replacement of cement in presence of copolymer latexes. Portland cement (PC) was partially replaced with 0, 10, 20, 30 50, and 60% FA. Copolymer latexes were used based on 2-hydroxyethyl acrylate (2-HEA) and 2-hydroxymethylacrylate (2-HEMA). Testing included workability, setting time, absorption, chemically combined water content, compressive strength, and scanning electron microscopy (SEM). The addition of FA to mortar as replacement of PC affected the physicomechanical properties of mortar. As the content of FA in the concrete increased, the setting times (initial and final) were elongated. The results obtained at 28 days of curing indicate that the maximum properties of mortar occur at around 30% FA. Beyond 30% FA the properties of mortar reduce and at 60% FA the properties of mortar are lower than those of the reference mortar without FA. However, the addition of polymer latexes into mortar containing FA improved most of the physicomechanical properties of mortar at all curing times. Compressive strength, combined water, and workability of mortar containing FA premixed with latexes are higher than those of mortar containing FA without latexes.

  2. Effect of Copolymer Latexes on Physicomechanical Properties of Mortar Containing High Volume Fly Ash as a Replacement Material of Cement

    PubMed Central

    Kozhamzharova, Latipa; Gulzhakhan, Yeligbayeva; Bekbayeva, Lyazzat; Williams, Craig

    2014-01-01

    This paper investigates the physicomechanical properties of mortar containing high volume of fly ash (FA) as partial replacement of cement in presence of copolymer latexes. Portland cement (PC) was partially replaced with 0, 10, 20, 30 50, and 60% FA. Copolymer latexes were used based on 2-hydroxyethyl acrylate (2-HEA) and 2-hydroxymethylacrylate (2-HEMA). Testing included workability, setting time, absorption, chemically combined water content, compressive strength, and scanning electron microscopy (SEM). The addition of FA to mortar as replacement of PC affected the physicomechanical properties of mortar. As the content of FA in the concrete increased, the setting times (initial and final) were elongated. The results obtained at 28 days of curing indicate that the maximum properties of mortar occur at around 30% FA. Beyond 30% FA the properties of mortar reduce and at 60% FA the properties of mortar are lower than those of the reference mortar without FA. However, the addition of polymer latexes into mortar containing FA improved most of the physicomechanical properties of mortar at all curing times. Compressive strength, combined water, and workability of mortar containing FA premixed with latexes are higher than those of mortar containing FA without latexes. PMID:25254256

  3. NEUTRON RADIOGRAPHY MEASUREMENT OF SALT SOLUTION ABSORPTION IN MORTAR.

    PubMed

    Lucero, Catherine L; Spragg, Robert P; Bentz, Dale P; Hussey, Daniel S; Jacobson, David L; Weiss, W Jason

    2017-01-01

    Some concrete pavements in the US have recently exhibited premature joint deterioration. It is hypothesized that one component of this damage can be attributed to a reaction that occurs when salt-laden water is absorbed in the concrete and reacts with the matrix. This study examines the absorption of CaCl2 solution in mortar via neutron imaging. Mortar specimens were prepared with water to cement ratios, (w/c), of 0.36, 0.42 and 0.50 by mass and exposed to chloride solutions with concentrations ranging from 0 % to 29.8 % by mass. Depth of fluid penetration and moisture content along the specimen length were determined for 96 h after exposure. At high salt concentration (29.8 %), the sorption rate decreased by over 80 % in all samples. Along with changes in surface tension and viscosity, CaCl2 reacts with the cement paste to produce products (Friedel's salt, Kuzel's salt, or calcium oxychloride) that block pores and reduce absorption.

  4. Differentiating seawater and groundwater sulfate attack in Portland cement mortars

    SciTech Connect

    Santhanam, Manu . E-mail: manus@iitm.ac.in; Cohen, Menashi; Olek, Jan

    2006-12-15

    The study reported in this article deals with understanding the physical, chemical and microstructural differences in sulfate attack from seawater and groundwater. Portland cement mortars were completely immersed in solutions of seawater and groundwater. Physical properties such as length, mass, and compressive strength were monitored periodically. Thermal analysis was used to study the relative amounts of phases such as ettringite, gypsum, and calcium hydroxide, and microstructural studies were conducted by scanning electron microscopy. Portland cement mortars performed better in seawater solution compared to groundwater solution. The difference in performance could be attributed to the reduction in the quantity of the expansive attack products (gypsum and ettringite). The high Cl concentration of seawater could have played an important role by binding the C{sub 3}A to form chloroaluminate compounds, such as Friedel's salt (detected in the microstructural studies), and also by lowering the expansive potential of ettringite. Furthermore, the thicker layer of brucite forming on the specimens in seawater could have afforded better protection against ingress of the solution than in groundwater.

  5. Compatibility study and adaption of stone repair mortars for the Lede stone (Belgium)

    NASA Astrophysics Data System (ADS)

    De Kock, T.; Vandevoorde, D.; Boone, M. A.; Dewanckele, J.; De Boever, W.; Lanzón, M.; De Schutter, G.; Van Hoorebeke, L.; Jacobs, P.; Cnudde, V.

    2012-04-01

    One of the main historic building materials in northern Belgium is the Lede stone. This arenaceous limestone from Lutetian age was excavated in the region of Ghent and Brussels and was transported northwards by main rivers such as the Scheldt and Zenne. Thanks to this natural transport route, the stone in also found in many cities which lie abroad the excavation area, such as Antwerp (Belgium) and various cities in the Netherlands (Breda, Zierikzee, …). Due to its dominant occurrence in our cultural heritage, it is frequently subjected to restoration and renovation works. Depending on the degree of decay, most frequent stone operations are cleaning, healing with mortar or replacing it by (often exotic) fresh blocks. Originally, this limestone has a greenish-gray colour, but when being exposed to atmospheric conditions it acquires a yellowish to rusty coloured patina. The origin of the latter is most likely the oxidation of glauconite minerals which are present in a few percent in the stone. In addition, the stone often demonstrates black crust formation due to sulphation. Cleaning of the stone often results in an excess removal of this black gypsum crusts and patina, thus exposing deeper parts of the stone which appear more greenish-gray again. When the stone is subsequently healed by adding repair mortar to damaged parts, the question rises which mortar colour is more appropriate. The choice of repair mortar is greatly depending on commercial aspects. When handling entire facades on monuments, a mineral mortar based on ZnCl is most often applied in Belgium. The big advantage of this mortar is its fast curing. Three colour types have been developed for the Lede stone in specific. However, the hardness of this mortar is sometimes in conflict with reversibility. For the handling of individual sculptures some conservators choose for the application of (hydraulic) lime mortars. The advantage of using such mortars is their high compatibility and reversibility. The

  6. Use of limestone obtained from waste of the mussel cannery industry for the production of mortars

    SciTech Connect

    Ballester, Paloma; Marmol, Isabel; Morales, Julian; Sanchez, Luis . E-mail: luis-sanchez@uco.es

    2007-04-15

    Various types of cement-SiO{sub 2}-CaCO{sub 3} mortar were prepared by replacing quarry limestone aggregate with limestone obtained as a by-product from waste of the mussel cannery industry. The CaCO{sub 3} aggregate consists mainly of elongated prismatic particles less than 4 {mu}m long rather than of the rounded particles of smaller size (2-6 {mu}m) obtained with quarry limestone. The mechanical and structural properties of the mortars were found to be influenced by aggregate morphology. Setting of the different types of mortar after variable curing times was evaluated by scanning electron microscopy (SEM), thermogravimetric analysis (TG) and mercury intrusion porosimetry (MIP) techniques. Mortars with a high content in mussel shell limestone exhibited a more packed microstructure, which facilitates setting of cement and results in improved mortar strength. The enhanced mechanical properties of the new mortars allow the cement content in the final mortar composition to be decreased and production costs to be reduced as a result.

  7. Carbonation and pH in mortars manufactured with supplementary cementitious materials

    SciTech Connect

    McPolin, D.O.; Basheer, P.A.M.; Long, A.E.

    2009-05-15

    An investigation of carbonation in mortars and methods of measuring the degree of carbonation and pH change is presented. The mortars were manufactured using ordinary portland cement, pulverized fuel ash, ground granulated blast-furnace slag, metakaolin, and microsilica. The mortars were exposed to a carbon dioxide-rich environment (5% CO{sub 2}) to accelerate carbonation. The resulting carbonation was measured using phenolphthalein indicator and thermogravimetric analysis. The pH of the pore fluid and a powdered sample, extracted from the mortar, was measured to give an accurate indication of the actual pH of the concrete. The pH of the extracted powder mortar sample was found to be similar to the pH of the pore fluid expressed from the mortars. The thermogravimetric analysis suggested two distinct regions of transport of CO{sub 2} within mortar, a surface region where convection was prevalent and a deeper region where diffusion was dominant. The use of microsilica has been shown to decrease the rate of carbonation, while pulverized fuel ash and ground granulated blast-furnace slag have a detrimental effect on carbonation. Metakaolin has little effect on carbonation.

  8. Combined Effects of Non-Conforming Fly Ash and Recycled Masonry Aggregates on Mortar Properties.

    PubMed

    Torres-Gómez, Ana Isabel; Ledesma, Enrique F; Otero, Rocio; Fernández, José Maria; Jiménez, José Ramón; de Brito, Jorge

    2016-08-25

    This work evaluates the effects of using non-conforming fly ash (Nc-FA) generated in a thermoelectric power plant as filler material for mortars made with natural sand (NA) and recycled sand from masonry waste (FRMA). The incorporation of powdered recycled masonry filler (R-MF) is also tested as an alternative to siliceous filler (Si-F). Three families of mortars were designed to study: the effect of replacing Si-F with Nc-FA on mortars made with NA; the effect of replacing Si-F with Nc-FA on mortars made with 50% of NA and 50% of FRMA; and the effect of replacing Si-F with R-MF on mortars made with NA and FRMA. Replacing Si-F with Nc-FA is a viable alternative that increases the mechanical strength, the workability and durability properties and decreases the shrinkage. The use of FRMA and Nc-FA improved the mechanical strength of mortars, and it slightly increased the shrinkage. The replacement of Si-F with R-MF on mortars made with FRMA is not a good alternative, because it has a negative impact on all of the properties tested. This work can help both to reduce cement and natural resources' consumption and to increase the recycling rate of Nc-FA and FRMA.

  9. Combined Effects of Non-Conforming Fly Ash and Recycled Masonry Aggregates on Mortar Properties

    PubMed Central

    Torres-Gómez, Ana Isabel; Ledesma, Enrique F.; Otero, Rocio; Fernández, José Maria; Jiménez, José Ramón; de Brito, Jorge

    2016-01-01

    This work evaluates the effects of using non-conforming fly ash (Nc-FA) generated in a thermoelectric power plant as filler material for mortars made with natural sand (NA) and recycled sand from masonry waste (FRMA). The incorporation of powdered recycled masonry filler (R-MF) is also tested as an alternative to siliceous filler (Si-F). Three families of mortars were designed to study: the effect of replacing Si-F with Nc-FA on mortars made with NA; the effect of replacing Si-F with Nc-FA on mortars made with 50% of NA and 50% of FRMA; and the effect of replacing Si-F with R-MF on mortars made with NA and FRMA. Replacing Si-F with Nc-FA is a viable alternative that increases the mechanical strength, the workability and durability properties and decreases the shrinkage. The use of FRMA and Nc-FA improved the mechanical strength of mortars, and it slightly increased the shrinkage. The replacement of Si-F with R-MF on mortars made with FRMA is not a good alternative, because it has a negative impact on all of the properties tested. This work can help both to reduce cement and natural resources’ consumption and to increase the recycling rate of Nc-FA and FRMA. PMID:28773849

  10. Resistance of biofilm-covered mortars to microbiologically influenced deterioration simulated by sulfuric acid exposure

    SciTech Connect

    Soleimani, Sahar Isgor, O. Burkan Ormeci, Banu

    2013-11-15

    Following the reported success of biofilm applications on metal surfaces to inhibit microbiologically influenced corrosion, effectiveness and sustainability of E. coli DH5α biofilm on mortar surface to prevent microbiologically influenced concrete deterioration (MICD) are investigated. Experiments simulating microbial attack were carried out by exposing incrementally biofilm-covered mortar specimens to sulfuric acid solutions with pH ranging from 3 to 6. Results showed that calcium concentration in control reactors without biofilm was 23–47% higher than the reactors with biofilm-covered mortar. Formation of amorphous silica gel as an indication of early stages of acid attack was observed only on the control mortar specimens without biofilm. During acidification, the biofilm continued to grow and its thickness almost doubled from ∼ 30 μm before acidification to ∼ 60 μm after acidification. These results demonstrated that E. coli DH5α biofilm was able to provide a protective and sustainable barrier on mortar surfaces against medium to strong sulfuric acid attack. -- Highlights: •Effectiveness of E.coli DH5α biofilm to prevent MICD was studied. •Conditions that lead to MICD were simulated by chemical acidification. •Biofilm-covered mortar specimens were exposed to sulfuric acid solutions. •The presence of biofilm helped reduce the chemically-induced mortar deterioration. •Biofilm remained alive and continued to grow during the acidification process.

  11. Modeling Adhesive Anchors in a Discrete Element Framework

    PubMed Central

    Marcon, Marco; Vorel, Jan; Ninčević, Krešimir; Wan-Wendner, Roman

    2017-01-01

    In recent years, post-installed anchors are widely used to connect structural members and to fix appliances to load-bearing elements. A bonded anchor typically denotes a threaded bar placed into a borehole filled with adhesive mortar. The high complexity of the problem, owing to the multiple materials and failure mechanisms involved, requires a numerical support for the experimental investigation. A reliable model able to reproduce a system’s short-term behavior is needed before the development of a more complex framework for the subsequent investigation of the lifetime of fasteners subjected to various deterioration processes can commence. The focus of this contribution is the development and validation of such a model for bonded anchors under pure tension load. Compression, modulus, fracture and splitting tests are performed on standard concrete specimens. These serve for the calibration and validation of the concrete constitutive model. The behavior of the adhesive mortar layer is modeled with a stress-slip law, calibrated on a set of confined pull-out tests. The model validation is performed on tests with different configurations comparing load-displacement curves, crack patterns and concrete cone shapes. A model sensitivity analysis and the evaluation of the bond stress and slippage along the anchor complete the study. PMID:28786964

  12. Modeling Adhesive Anchors in a Discrete Element Framework.

    PubMed

    Marcon, Marco; Vorel, Jan; Ninčević, Krešimir; Wan-Wendner, Roman

    2017-08-08

    In recent years, post-installed anchors are widely used to connect structural members and to fix appliances to load-bearing elements. A bonded anchor typically denotes a threaded bar placed into a borehole filled with adhesive mortar. The high complexity of the problem, owing to the multiple materials and failure mechanisms involved, requires a numerical support for the experimental investigation. A reliable model able to reproduce a system's short-term behavior is needed before the development of a more complex framework for the subsequent investigation of the lifetime of fasteners subjected to various deterioration processes can commence. The focus of this contribution is the development and validation of such a model for bonded anchors under pure tension load. Compression, modulus, fracture and splitting tests are performed on standard concrete specimens. These serve for the calibration and validation of the concrete constitutive model. The behavior of the adhesive mortar layer is modeled with a stress-slip law, calibrated on a set of confined pull-out tests. The model validation is performed on tests with different configurations comparing load-displacement curves, crack patterns and concrete cone shapes. A model sensitivity analysis and the evaluation of the bond stress and slippage along the anchor complete the study.

  13. Recycling red mud from the production of aluminium as a red cement-based mortar.

    PubMed

    Yang, Xiaojie; Zhao, Jianfeng; Li, Haoxin; Zhao, Piqi; Chen, Qin

    2017-01-01

    Current management for red mud is insufficient and a new method is needed. A series of experiments have been carried out to develop a new approach for effective management of red mud. Mortars without or with 3%, 6% and 9% red mud were prepared and their fresh and hardened properties were measured to access the possibility of recycling the red mud in the production of red cement-based mortar. The mechanisms corresponding to their mechanical performance variations were explored by X-ray powder diffraction and scanning electron microscopy. The results show that the fresh mortars with red mud present an increase of viscosity as compared with the control. However, little difference is found when the content of red mud is altered. It also can be seen that red mud increases flow time and reduces the slump flow of the mortar. Meanwhile, it is found that mortar with red mud is provided with higher air content. Red mud is eligible to adjust the decorative mortar colour. Compressive strength of mortar is improved when less than 6% red mud is added. However, overall it has a slightly negative effect on tensile bond strength. It decreases the Ca(OH)2 content and densifies the microstructure of hardened paste. The heavy metal concentrations in leachates of mortars with red mud are much lower than the values required in the standard, and it will not do harm to people's health and the environment. These results are important to recycle and effectively manage red mud via the production of red cement-based mortar.

  14. AMS radiocarbon dating of mortar: The case study of the medieval UNESCO site of Modena

    NASA Astrophysics Data System (ADS)

    Carmine, Lubritto; Caroselli, Marta; Lugli, Stefano; Marzaioli, Fabio; Nonni, Sara; Marchetti Dori, S.; Terrasi, Filippo

    2015-10-01

    The carbon dioxide contributing to binder formation during the set of a lime mortar reflects the atmospheric 14C content at the time of construction of a building. For this reason, the 14C dating of mortars is used with increasing frequencies in archaeological and architectural research. Mortars, however, may also contain carbonaceous contaminants potentially affecting radiocarbon dating. The Centre for Isotopic Research on Cultural and Environmental heritage (CIRCE) of the Second University of Naples (SUN) has recently obtained some promising results in mortar radiocarbon dating thanks to the development of a procedure (i.e. CryoSoniC/Cryo2SoniC) aiming to eliminate exogenous C contamination that may occur in a mortar. The construction history of the UNESCO World Heritage Site of Modena (Italy) is still controversial and represents a challenging case study for the application of absolute dating methodologies for different reasons. From the point of view of 14C dating, for example, given the high percentage of carbonate aggregates composing these samples, Modena mortars represent an experimental test particularly indicative of exogenous carbon sources suppression ensuring methodology accuracy. In this paper several AMS Radiocarbon dates were carried out on lime lumps with the aim to: (i) verify procedure accuracy by a comparison of the results obtainable from lime lumps dated after different treatments (i.e. bulk lime lumps vs. CryoSoniC purified lime lumps); (ii) compare different building phases absolute chronology for the medieval UNESCO site of Modena, with that assumed by historical sources in order to assess preliminary the 14C dating feasibility for of the site. Historical temporal constraints and mortar clustering, based on petrography, have been applied to define a temporal framework of the analyzed structure. Moreover, a detailed petrographic characterization of mortars was used both as a preliminary tool for the choice of samples and to infer about the

  15. Use of ruggedness testing to develop an inter-laboratory testing protocol for mortar-cement mortar

    SciTech Connect

    Ponce, L.G.; Klingner, R.E.; Melander, J.M.

    1999-07-01

    In 1996, ASTM approved a specification for a new product, called mortar cement, intended for use in applications requiring masonry with high tensile bond strength. An inter-laboratory testing program is planned; the objectives will include the determination of intra-and inter-laboratory coefficients of variation of bond-wrench results for that product. Prior to conducting the inter-laboratory testing program, it is necessary to set the test procedures and variables to be used. Some of those procedures (such as the precise control of flow, the use of jigs, templates and drop hammers to construct prisms, and bag curing), have already been found to reduce the variability of bond-wrench results, are included in ASTM C1329-96, Standard Specification for Mortar Cement, and ASTM C1357-96, Standard Test Methods for Evaluating Bond Strength, and will be used in the inter-laboratory study. However, other test procedures must still be established. To do so, and prior to the inter-laboratory study, a pilot ruggedness study was conducted; the objective was to determine which additional factors should be controlled during the inter-laboratory study. In this paper, the conduct and results of that ruggedness study are presented and discussed in the light of current bond-wrench testing procedures, and specific changes are recommended to ASTM bond-wrench testing standards.

  16. Hybrid fiber-reinforcement in mortar and concrete

    NASA Astrophysics Data System (ADS)

    Lawler, John Steven

    Performance of concrete and mortar is improved through use of discontinuous fibers because of the resulting fundamental changes in the failure mechanism. The role a specific type of fiber plays in this process is governed by the material and geometry of the fibers, the fiber-matrix bond and the matrix properties. Blending fiber types exhibiting complementary and additive properties in the composite is a means for maximizing the potential of fibers for the reinforcement of concrete. The specific blend pursued in this investigation is a combination of steel or PVA microfibers, that interact with developing cracks, and steel macrofibers, which become crucial once cracks develop. The objective of this investigation is to explore the mechanisms by which fibers interact with the composite matrix and to provide a rigorous characterization of performance achievable with hybrid reinforced concrete. The role of micro- and macrofibers in the failure of mortar is examined using Subregion Scanning Computer Vision. The fracture process occurs in three stages: microcrack formation, microcrack coalescence and finally the formation of macrocracks. Closely spaced microfibers bridge coalesced microcracks. This increases performance up to and around the peak load by delaying the initiation of macrocracking. Once macrocracks develop, macrofibers are most effective at imparting ductility to the composite. Hybrid reinforcing fibers reduce the water permeability of cracked mortar, which has implications for durability, through the induction of multiple cracking. An innovative method for measuring cracked permeability in uniaxial tension under load is presented. The workability of macro- and microfiber hybrids in concrete is governed by the high surface area of the microfibers. A mix design procedure is presented to determine the optimum paste volume to efficiently achieve the best flow and cohesion properties. The relationships between workability, fiber dispersion, and mechanical

  17. A pulsed field gradient and NMR imaging investigations of the water retention mechanism by cellulose ethers in mortars

    SciTech Connect

    Patural, Laetitia; Porion, Patrice; Van Damme, Henri; Govin, Alexandre; Grosseau, Philippe; Ruot, Bertrand; Deves, Olivier

    2010-09-15

    The study presented in this paper is devoted to improve the knowledge on the influence of cellulose ethers (CE) on the freshly-mixed mortars water retention. Indeed, this crucial property is the most important imparted by these polysaccharides. One of the assumptions proposed to explain this phenomenon is that CE acts as diffusion barrier to the water. To test this hypothesis, the CE effect on the self-diffusion coefficient of water in solution and on the water mobility between two fresh cement pastes was studied by Nuclear Magnetic Resonance. CE does not significantly modify the water self-diffusion coefficient in CE solution or in admixed cement pastes. Moreover the interdiffusion imaging experiments demonstrated that the water diffusion at the paste/paste interface is not affected by the presence of cellulosic admixture.

  18. Mineralogical and microstructural studies of mortars from the bath complex of the Roman villa rustica near Mosnje (Slovenia)

    SciTech Connect

    Kramar, Sabina; Zalar, Vesna; Urosevic, Maja; Mauko, Alenka; Mirtic, Breda; Lux, Judita; Mladenovic, Ana

    2011-11-15

    This study deals with the characterization of mortars collected from bath complex of the Roman villa rustica from an archeological site near Mosnje (Slovenia). The mortar layers of the mosaics, wall paintings and mortar floors were investigated. A special aggregate consisting of brick fragments was present in the mortars studied. The mineralogical and petrographic compositions of the mortars were determined by means of optical microscopy, X-ray powder diffraction and FTIR spectroscopy. Analysis of aggregate-binder interfaces using SEM-EDS revealed various types of reactivity rims. In order to assess the hydraulic characteristics of the mortars, the acid-soluble fractions were determined by ICP-OES. Furthermore, the results of Hg-porosimetry and gas sorption isotherms showed that mortars with a higher content of brick fragments particles exhibited a higher porosity and a greater BET surface area but a lower average pore diameter compared to mortars lacking this special aggregate. - Highlights: {yields} Mineral and microstructural characterizations of brick-lime mortars. {yields} Hydraulic character of mortars in Roman baths complex. {yields} Reaction rims were observed around brick fragments and dolomitic grains. {yields} Higher content of brick particles yielded a higher BET surface area. {yields} Addition of brick particles increased porosity and diminished pore size diameter.

  19. Biomimetic adhesive materials containing cyanoacryl group for medical application.

    PubMed

    Jo, Sueng Hwan; Sohn, Jeong Sun

    2014-10-17

    For underwater adhesives with biocompatible and more flexible bonds using biomimetic adhesive groups, DOPA-like adhesive molecules were modified with cyanoacrylates to obtain different repeating units and chain length copolymers. The goal of this work is to copy the mechanisms of underwater bonding to create synthetic water-borne underwater medical adhesives through blending of the modified DOPA and a triblock copolymer (PEO-PPO-PEO) for practical application to repair wet living tissues and bones, and in turn, to use the synthetic adhesives to test mechanistic hypotheses about the natural adhesive. The highest values in stress and modulus of the biomimetic adhesives prepared in wet state were 165 kPa and 33 MPa, respectively.

  20. Thermo-mechanical properties of polyester mortar using recycled PET

    SciTech Connect

    Rebeiz, K.S.; Craft, A.P.

    1997-07-01

    The thermo-mechanical properties of polyester mortar (PM) using unsaturated polyester resins based on recycled PET are investigated in this paper (the recycled PET waste is mainly obtained from used plastic beverage bottles). The use of recycled PET in PM formulation is important because it helps produce good quality PM at a relatively low cost, save energy and alleviate an environmental problem posed by plastic wastes. PM construction applications include the repair of dams, piers, runways, bridges and other structures. Test results show that the effective use of PM overlays on portland cement concrete slabs is best achieved by utilizing flexible resins with low modulus and high elongation capacity at failure. The use of flexible resins in PM production is especially important in situations involving large thermal movements.

  1. Supramolecular adhesives to hard surfaces: adhesion between host hydrogels and guest glass substrates through molecular recognition.

    PubMed

    Takashima, Yoshinori; Sahara, Taiga; Sekine, Tomoko; Kakuta, Takahiro; Nakahata, Masaki; Otsubo, Miyuki; Kobayashi, Yuichiro; Harada, Akira

    2014-10-01

    Supramolecular materials based on host-guest interactions should exhibit high selectivity and external stimuli-responsiveness. Among various stimuli, redox and photo stimuli are useful for its wide application. An external stimuli-responsive adhesive system between CD host-gels (CD gels) and guest molecules modified glass substrates (guest Sub) is focused. Here, the selective adhesion between host gels and guest substrates where adhesion depends on molecular complementarity is reported. Initially, it is thought that adhesion of a gel material onto a hard material might be difficult unless many guest molecules modified linear polymers immobilize on the surface of hard materials. However, reversible adhesion of the CD gels is observed by dissociating and re-forming inclusion complex in response to redox and photo stimuli.

  2. Comparing the use of sewage sludge ash and glass powder in cement mortars.

    PubMed

    Chen, Zhen; Poon, Chi Sun

    2016-09-23

    This study explored the suitability of using sewage sludge ash (SSA) and mixed-colored glass powder (MGP) as construction materials in cement mortars. Positive findings from this study may help promote the recycling of waste SSA and MGP in construction works. The results indicated that the SSA decreased while MGP improved the mortar workability. The SSA exhibited very low pozzolanic activity, but the cement mortar prepared with 20% SSA yielded strength values slightly superior to those of the glass mortars due to its water absorption ability. MGP can serve as a pozzolan and when 20% of cement was replaced by MGP, apparent compressive strength gains were found at later curing ages. The SSA could be used to mitigate ASR expansion while the MGP was superior in resisting drying shrinkage.

  3. Effects of surfactants on the properties of mortar containing styrene/methacrylate superplasticizer.

    PubMed

    Negim, El-Sayed; Kozhamzharova, Latipa; Khatib, Jamal; Bekbayeva, Lyazzat; Williams, Craig

    2014-01-01

    The physical and mechanical properties of mortar containing synthetic cosurfactants as air entraining agent are investigated. The cosurfactants consist of a combination of 2% dodecyl benzene sodium sulfonate (DBSS) and either 1.5% polyvinyl alcohol (PVA) or 1.5% polyoxyethylene glycol monomethyl ether (POE). Also these cosurfactants were used to prepare copolymers latex: styrene/butyl methacrylate (St/BuMA), styrene/methyl methacrylate (St/MMA), and styrene/glycidyl methacrylate (St/GMA), in order to study their effects on the properties of mortar. The properties of mortar examined included flow table, W/C ratio, setting time, water absorption, compressive strength, and combined water. The results indicate that the latex causes improvement in mortar properties compared with cosurfactants. Also polymer latex containing DBSS/POE is more effective than that containing DBSS/PVA.

  4. Effects of mineral additions on durability and physico-mechanical properties of mortar

    NASA Astrophysics Data System (ADS)

    Logbi, A.; Kriker, A.; Snisna, Z.

    2017-02-01

    This paper consists of an experimental study of the effect of some mineral admixtures on the properties of mortar. Blast furnace Slag of El-Hadjar, natural pozzolan of Beni saf and limestone of Ghardaia, all from Algeria, are crushed in high fineness and incorporated in the cement with different contents (15 % 20 % and 10%) respectively, in order to perform the physico-mechanical characteristics and durability of the mortar. The replacement of cement by 15% of natural pozzolan, or 20% of the Blast furnace Slag improves the mechanical performances of mortar in early and long ages than the mortar without additions, but 10% of limestone fillers have a positive effect only at early age. For durability the three additions have developed a beneficial effect on mechanical resistance under the free aquifers water, while their effects are different on capillary absorption.

  5. Effects of Surfactants on the Properties of Mortar Containing Styrene/Methacrylate Superplasticizer

    PubMed Central

    Negim, El-Sayed; Kozhamzharova, Latipa; Khatib, Jamal; Bekbayeva, Lyazzat; Williams, Craig

    2014-01-01

    The physical and mechanical properties of mortar containing synthetic cosurfactants as air entraining agent are investigated. The cosurfactants consist of a combination of 2% dodecyl benzene sodium sulfonate (DBSS) and either 1.5% polyvinyl alcohol (PVA) or 1.5% polyoxyethylene glycol monomethyl ether (POE). Also these cosurfactants were used to prepare copolymers latex: styrene/butyl methacrylate (St/BuMA), styrene/methyl methacrylate (St/MMA), and styrene/glycidyl methacrylate (St/GMA), in order to study their effects on the properties of mortar. The properties of mortar examined included flow table, W/C ratio, setting time, water absorption, compressive strength, and combined water. The results indicate that the latex causes improvement in mortar properties compared with cosurfactants. Also polymer latex containing DBSS/POE is more effective than that containing DBSS/PVA. PMID:24955426

  6. Mineralogical characterization of rendering mortars from decorative details of a baroque building in Kozuchow (SW Poland)

    SciTech Connect

    Bartz, W.; Filar, T.

    2010-01-15

    Optical microscopic observations, scanning electron microscopy and microprobe with energy dispersive X-ray analysis, X-ray diffraction and differential thermal/thermogravimetric analysis allowed detailed characterization of rendering mortars from decorative details (figures of Saints) of a baroque building in Kozuchow (Lubuskie Voivodship, Western Poland). Two separate coats of rendering mortars have been distinguished, differing in composition of their filler. The under coat mortar has filler composed of coarse-grained siliceous sand, whereas the finishing one has much finer grained filler, dominated by a mixture of charcoal and Fe-smelting slag, with minor amounts of quartz grains. Both mortars have air-hardening binder composed of gypsum and micritic calcite, exhibiting microcrystalline structure.

  7. Field and laboratory determination of a poly(vinyl/vinylidene chloride) additive in brick mortar.

    PubMed

    Law, S L; Newman, J H; Ptak, F L

    1990-02-01

    A polymerized vinyl/vinylidene chloride additive, used in brick mortar during the 60s and 70s, is detected at the building site by the field method, which employs a commercially available chloride test strip. The field test results can then be verified by the laboratory methods. In one method, total chlorine in the mortar is determined by an oxygen-bomb method and the additive chloride is determined by difference after water-soluble chlorides have been determined on a separate sample. In the second method, the polymerized additive is extracted directly from the mortar with tetrahydrofuran (THF). The difference in weight before and after extraction of the additive gives the weight of additive in the mortar. Evaporation of the THF from the extract leaves a thin film of the polymer, which gives an infrared "fingerprint" spectrum characteristic of the additive polymer.

  8. Tracing formation and durability of calcite in a Punic-Roman cistern mortar (Pantelleria Island, Italy).

    PubMed

    Dietzel, Martin; Schön, Frerich; Heinrichs, Jens; Deditius, Artur P; Leis, Albrecht

    2016-01-01

    Ancient hydraulic lime mortar preserves chemical and isotopic signatures that provide important information about historical processing and its durability. The distribution and isotopic composition of calcite in a mortar of a well-preserved Punic-Roman cistern at Pantelleria Island (Italy) was used to trace the formation conditions, durability, and individual processing periods of the cistern mortar. The analyses of stable carbon and oxygen isotopes of calcite revealed four individual horizons, D, E, B-1 and B-2, of mortar from the top to the bottom of the cistern floor. Volcanic and ceramic aggregates were used for the production of the mortar of horizons E/D and B-1/B-2, respectively. All horizons comprise hydraulic lime mortar characterized by a mean cementation index of 1.5 ± 1, and a constant binder to aggregate ratio of 0.31 ± 0.01. This suggests standardized and highly effective processing of the cistern. The high durability of calcite formed during carbonation of slaked lime within the matrix of the ancient mortar, and thus the excellent resistance of the hydraulic lime mortar against water, was documented by (i) a distinct positive correlation of δ(18)Ocalcite and δ(13)Ccalcite; typical for carbonation through a mortar horizon, (ii) a characteristic evolution of δ(18)Ocalcite and δ(13)Ccalcite through each of the four mortar horizons; lighter follow heavier isotopic values from upper to lower part of the cistern floor, and (iii) δ(18)Ocalcite varying from -10 to -5 ‰ Vienna Pee Dee belemnite (VPDB). The range of δ(18)Ocalcite values rule out recrystallization and/or neoformation of calcite through chemical attack of water stored in cistern. The combined studies of the chemical composition of the binder and the isotopic composition of the calcite in an ancient mortar provide powerful tools for elucidating the ancient techniques and processing periods. This approach helps to evaluate the durability of primary calcite and demonstrates the

  9. Effect of dry deposition of pollutants on the degradation of lime mortars with sepiolite

    SciTech Connect

    Martinez-Ramirez, S.; Thompson, G.E.; Puertas, F.; Blanco-Varela, M.T.

    1998-01-01

    The behavior of lime mortars containing sepiolite or sepiolite plus pentaclorophenol in atmospheric simulation chambers has been studied. The pollutant gases used in this study have been NO, NO{sub 2}, and SO{sub 2}. The studies have been done in wet and dry conditions as well as with and without ozone. In the case of NO and NO{sub 2}, the aggressive agent would be HNO{sub 3}, which reacts with lime mortar binder CaCO{sub 3}, producing Ca(NO{sub 3}){sub 2} formation. On this process, the influence of the presence of an oxidant as well as water has been studied. The catalyst effect of the oxidation is known to be accelerated by water presence, so mortars exposed to NO + O{sub 3} + H{sub 2}O and NO{sub 2} + O{sub 3} + H{sub 2}O environments undergo a greater salts formation than those exposed to the rest of he aggressive media. The three mortars` behaviors are similar and independent of their composition, producing small amount of salts in every case. When SO{sub 2} is the gas used, the aggressive agent of mortar will be H{sub 2}SO{sub 4} that reacts with mortar binder, CaCO{sub 3} to produce calcium sulfate in the form of gypsum. Oxidant and/or water influence has been studied, and the (SO{sub 2} + O{sub 3} + H{sub 2}O) chamber was found to be the one with greater aggressivity to mortars. However, in these conditions, sepiolite presence within the mortars delayed gypsum formation.

  10. Inhibition of bacterial and leukocyte adhesion under shear stress conditions by material surface chemistry.

    PubMed

    Patel, Jasmine D; Ebert, Michael; Stokes, Ken; Ward, Robert; Anderson, James M

    2003-01-01

    Biomaterial-centered infections, initiated by bacterial adhesion, persist due to a compromised host immune response. Altering implant materials with surface modifying endgroups (SMEs) may enhance their biocompatibility by reducing bacterial and inflammatory cell adhesion. A rotating disc model, which generates shear stress within physiological ranges, was used to characterize adhesion of leukocytes and Staphylococcus epidermidis on polycarbonate-urethanes and polyetherurethanes modified with SMEs (polyethylene oxide, fluorocarbon and dimethylsiloxane) under dynamic flow conditions. Bacterial adhesion in the absence of serum was found to be mediated by shear stress and surface chemistry, with reduced adhesion exhibited on materials modified with polydimethylsiloxane and polyethylene oxide SMEs. In contrast, bacterial adhesion was enhanced on materials modified with fluorocarbon SMEs. In the presence of serum, bacterial adhesion was primarily neither material nor shear dependent. However, bacterial adhesion in serum was significantly reduced to < or = 10% compared to adhesion in serum-free media. Leukocyte adhesion in serum exhibited a shear dependency with increased adhesion occurring in regions exposed to lower shear-stress levels of < or = 7 dyne/cm2. Additionally, polydimethylsiloxane and polyethylene oxide SMEs reduced leukocyte adhesion on polyether-urethanes. In conclusion, these results suggest that surface chemistry and shear stress can mediate bacterial and cellular adhesion. Furthermore, materials modified with polyethylene oxide SMEs are capable of inhibiting bacterial adhesion, consequently minimizing the probability of biomaterial-centered infections.

  11. Concretes and mortars with waste paper industry: Biomass ash and dregs.

    PubMed

    Martínez-Lage, Isabel; Velay-Lizancos, Miriam; Vázquez-Burgo, Pablo; Rivas-Fernández, Marcos; Vázquez-Herrero, Cristina; Ramírez-Rodríguez, Antonio; Martín-Cano, Miguel

    2016-10-01

    This article describes a study on the viability of using waste from the paper industry: biomass boiler ash and green liquor dregs to fabricate mortars and concretes. Both types of ash were characterized by obtaining their chemical and mineralogical composition, their organic matter content, granulometry, adsorption and other common tests for construction materials. Seven different mortars were fabricated, one for reference made up of cement, sand, and water, three in which 10, 20, or 30% of the cement was replaced by biomass ash, and three others in which 10, 20, or 30% of the cement was replaced with dregs. Test specimens were fabricated with these mortars to conduct flexural and compression tests. Flexural strength is reduced for all the mortars studied. Compressive strength increases for the mortars fabricated with biomass ash and decreases for the mortar with dregs. Finally, 5 concretes were made, one of them as a reference (neither biomass ash nor dregs added), two of them with replacements of 10 and 20% of biomass ash instead of cement and another two with replacements of 10 and 20% of dregs instead of cement. The compressive and tensile splitting strength increase when a 10% of ash is replaced and decrease in all the other cases. The modulus of elasticity always decreases.

  12. Utilization of recycled glass derived from cathode ray tube glass as fine aggregate in cement mortar.

    PubMed

    Ling, Tung-Chai; Poon, Chi-Sun

    2011-08-30

    Rapid advances in the electronic industry led to an excessive amount of early disposal of older electronic devices such as computer monitors and old televisions (TV) before the end of their useful life. The management of cathode ray tubes (CRT), which have been a key component in computer monitors and TV sets, has become a major environmental problem worldwide. Therefore, there is a pressing need to develop sustainable alternative methods to manage hazardous CRT glass waste. This study assesses the feasibility of utilizing CRT glass as a substitute for natural aggregates in cement mortar. The CRT glass investigated was an acid-washed funnel glass of dismantled CRT from computer monitors and old TV sets. The mechanical properties of mortar mixes containing 0%, 25%, 50%, 75% and 100% of CRT glass were investigated. The potential of the alkali-silica reaction (ASR) and leachability of lead were also evaluated. The results confirmed that the properties of the mortar mixes prepared with CRT glass was similar to that of the control mortar using sand as fine aggregate, and displayed innocuous behaviour in the ASR expansion test. Incorporating CRT glass in cement mortar successfully prevented the leaching of lead. We conclude that it is feasible to utilize CRT glass in cement mortar production.

  13. The Effect of Mortar Grade and Thickness on the Impact Resistance of Ferrocement Slab

    NASA Astrophysics Data System (ADS)

    Che Muda, Zakaria; Syamsir, Agusril; Nasharuddin Mustapha, Kamal; Sulleman, Sorefan; Beddu, Salmia; Thiruchelvam, Sivadass; Ismail, Firas B.; Usman, Fathoni; Liyana Mohd Kamal, Nur; Ashraful Alam, Md; Birima, Ahmed H.; Itam, Zarina; Zaroog, O. S.

    2016-03-01

    This paper investigate the effect of the thickness and mesh spacing on the impact of ferrocement for the concrete slab of 300mm × 300mm size reinforced subjected to low impact projectile test. A self-fabricated drop-weight impact test rig with a steel ball weight of 1.236 kg drop at height of 150 mm, 350mm, and 500mm has been used in this research work. The objective of this research is to study the relationship of impact resistance of ferrocement against the mortar grade and slab thickness. There is a good linear correlation between impact resistance of ferrocement against the mortar grade and the thickness of ferrocement slab. The first and ultimate crack impact resistance of mortar grade 43 (for 40 mm thick slab with mesh reinforcement) are 1.60 times and 1.53 times respectively against the mortar grade 17 slab (of same thickness with mesh reinforcement). The first and ultimate crack impact resistance for 40 mm thick slab (mortar grade 43 with mesh reinforcement) are 3.55 times and 4.49 times respectively against the 20 mm thick slab (of same mortar grade with mesh reinforcement).

  14. Study on compressive strength of self compacting mortar cubes under normal & electric oven curing methods

    NASA Astrophysics Data System (ADS)

    Prasanna Venkatesh, G. J.; Vivek, S. S.; Dhinakaran, G.

    2017-07-01

    In the majority of civil engineering applications, the basic building blocks were the masonry units. Those masonry units were developed as a monolithic structure by plastering process with the help of binding agents namely mud, lime, cement and their combinations. In recent advancements, the mortar study plays an important role in crack repairs, structural rehabilitation, retrofitting, pointing and plastering operations. The rheology of mortar includes flowable, passing and filling properties which were analogous with the behaviour of self compacting concrete. In self compacting (SC) mortar cubes, the cement was replaced by mineral admixtures namely silica fume (SF) from 5% to 20% (with an increment of 5%), metakaolin (MK) from 10% to 30% (with an increment of 10%) and ground granulated blast furnace slag (GGBS) from 25% to 75% (with an increment of 25%). The ratio between cement and fine aggregate was kept constant as 1: 2 for all normal and self compacting mortar mixes. The accelerated curing namely electric oven curing with the differential temperature of 128°C for the period of 4 hours was adopted. It was found that the compressive strength obtained from the normal and electric oven method of curing was higher for self compacting mortar cubes than normal mortar cube. The cement replacement by 15% SF, 20% MK and 25%GGBS obtained higher strength under both curing conditions.

  15. A Study on the Properties of Carbon Black Mortar Using Granulated Blast Furnace Slag and Polymer.

    PubMed

    Jang, Hong-Seok; Jeon, Ui-Hyeon; So, Seung-Young

    2015-11-01

    White Portland Cement (WPC) and inorganic pigment have been used in colored concrete, but there are some physical problems such as increases in efflorescence, and poor workability and low economics. The aim of this study was to investigate the effects of GBFS and polymer (methyl cellulose) on the physical properties of carbon black mortar. For this purpose, a flow test, compressive strength test and color evaluation and was carried out on cement mortar mixed with polymer by changing the proportion of cement and ratio of GBFS. The results show that the addition of polymer influences significantly the color value efficiency in colored mortar. This is due to the reduction of overall amount of micro pore. This polymer films prevent the transport of soluble calcium towards the surface, and decreases efflorescence. And the flow of colored mortar was increased in proportion to the addition rate of the GBFS. In addition the strength of colored mortars with GBFS at the long-term aged (after 28 days) was higher than that of the general WPC mortar, although its strength was developed slowly at the early ages.

  16. Compressive and flexural strength of expanded perlite aggregate mortar subjected to high temperatures

    NASA Astrophysics Data System (ADS)

    Zulkifeli, Muhamad Faqrul Hisham bin Mohd; Saman@Hj Mohamed, Hamidah binti Mohd

    2017-08-01

    Work on thermal resistant of outer structures of buildings is one of the solution to reduce death, damages and properties loss in fire cases. Structures protected with thermal resistant materials can delay or avoid failure and collapse during fire. Hence, establishment of skin cladding with advance materials to protect the structure of buildings is a necessary action. Expanded perlite is a good insulation material which can be used as aggregate replacement in mortar. This study is to study on mortar mechanical properties of flexural and compressive strength subjected to elevated temperatures using expanded perlite aggregate (EPA). This study involved experimental work which was developing mortar with sand replacement by volume of 0%, 10%, 20%, 30% and 40% of EPA and cured for 56 days. The mortars then exposed to 200°C, 400 °C, 700 °C and 1000 °C. Flexural and compressive strength of the mortar were tested. The tests showed that there were increased of flexural and compressive strength at 200°C, and constantly decreased when subjected to 400°C, 700°C and 1000 °C. There were also variation of strengths at different percentages of EPA replacement. Highest compressive strength and flexural strength recorded were both at 200 °C with 65.52 MPa and 21.34 MPa respectively. The study conclude that by using EPA as aggregate replacement was ineffective below elevated temperatures but increased the performance of the mortar at elevated temperatures.

  17. Durability of Structural Adhesively Bonded Systems.

    DTIC Science & Technology

    1986-01-01

    define the specific yield criterion. Rather than the classical Von-Mises and Drucker - Prager criteria, a modified yield criterion is used in this work...f STAN[DAR[DS iqg A . .e,’- *..’,,. oA- i..-. * in.. .. * .. n..-. . . . .. ., Ck N DURABILITY OF STRUCTURAL I 0 ADHESIVELY BONDED SYSTEMS c-.. by 0...Release: Distribution Unlimited 6 0- 26 DURABILITY OF STRUCTURAL ADHESIVELY -BONDED SYSTEMS by 0. Ishai, G. Yaniv and P. Bar-Yoseph December 1985

  18. Use of Artificial Neural Network for the Simulation of Radon Emission Concentration of Granulated Blast Furnace Slag Mortar.

    PubMed

    Jang, Hong-Seok; Xing, Shuli; Lee, Malrey; Lee, Young-Keun; So, Seung-Young

    2016-05-01

    In this study, an artificial neural networks study was carried out to predict the quantity of radon of Granulated Blast Furnace Slag (GBFS) cement mortar. A data set of a laboratory work, in which a total of 3 mortars were produced, was utilized in the Artificial Neural Networks (ANNs) study. The mortar mixture parameters were three different GBFS ratios (0%, 20%, 40%). Measurement radon of moist cured specimens was measured at 3, 10, 30, 100, 365 days by sensing technology for continuous monitoring of indoor air quality (IAQ). ANN model is constructed, trained and tested using these data. The data used in the ANN model are arranged in a format of two input parameters that cover the cement, GBFS and age of samples and, an output parameter which is concentrations of radon emission of mortar. The results showed that ANN can be an alternative approach for the predicting the radon concentration of GBFS mortar using mortar ingredients as input parameters.

  19. Dentin-enamel adhesives in pediatric dentistry: an update.

    PubMed

    García-Godoy, Franklin; Donly, Kevin J

    2015-01-01

    Adhesives and composite technology have made composite resins and polyacid-modified resin-based composites (compomers) very popular as materials to restore primary and permanent anterior and posterior teeth. More conservative preparations can be performed that maintain more tooth structure due to the adhesive properties of the adhesives used with composites and compomers. Meticulous care in the placement of adhesives and, subsequently, resin-based composites and compomers is necessary to produce long-term satisfactory results. The purpose of this paper is to update the current status in regards to dentin-enamel adhesives in primary teeth.

  20. Thermal Characterization of Adhesive

    NASA Technical Reports Server (NTRS)

    Spomer, Ken A.

    1999-01-01

    The current Space Shuttle Reusable Solid Rocket Motor (RSRM) nozzle adhesive bond system is being replaced due to obsolescence. Down-selection and performance testing of the structural adhesives resulted in the selection of two candidate replacement adhesives, Resin Technology Group's Tiga 321 and 3M's EC2615XLW. This paper describes rocket motor testing of these two adhesives. Four forty-pound charge motors were fabricated in configurations that would allow side by side comparison testing of the candidate replacement adhesives and the current RSRM adhesives. The motors provided an environment where the thermal performance of adhesives in flame surface bondlines was compared. Results of the FPC testing show that: 1) The phenolic char depths on radial bond lines is approximately the same and vary depending on the position in the blast tube regardless of which adhesive was used; 2) The adhesive char depth of the candidate replacement adhesives is less than the char depth of the current adhesives; 3) The heat-affected depth of the candidate replacement adhesives is less than the heat-affected depth of the current adhesives; and 4) The ablation rates for both replacement adhesives are slower than that of the current adhesives.

  1. The increase of compressive strength of natural polymer modified concrete with Moringa oleifera

    NASA Astrophysics Data System (ADS)

    Susilorini, Rr. M. I. Retno; Santosa, Budi; Rejeki, V. G. Sri; Riangsari, M. F. Devita; Hananta, Yan's. Dianaga

    2017-03-01

    Polymer modified concrete is one of some concrete technology innovations to meet the need of strong and durable concrete. Previous research found that Moringa oleifera can be applied as natural polymer modifiers into mortars. Natural polymer modified mortar using Moringa oleifera is proven to increase their compressive strength significantly. In this resesearch, Moringa oleifera seeds have been grinded and added into concrete mix for natural polymer modified concrete, based on the optimum composition of previous research. The research investigated the increase of compressive strength of polymer modified concrete with Moringa oleifera as natural polymer modifiers. There were 3 compositions of natural polymer modified concrete with Moringa oleifera referred to previous research optimum compositions. Several cylinder of 10 cm x 20 cm specimens were produced and tested for compressive strength at age 7, 14, and, 28 days. The research meets conclusions: (1) Natural polymer modified concrete with Moringa oleifera, with and without skin, has higher compressive strength compared to natural polymer modified mortar with Moringa oleifera and also control specimens; (2) Natural polymer modified concrete with Moringa oleifera without skin is achieved by specimens contains Moringa oleifera that is 0.2% of cement weight; and (3) The compressive strength increase of natural polymer modified concrete with Moringa oleifera without skin is about 168.11-221.29% compared to control specimens

  2. Adhesive and Elastic Properties of DOPA-Containing Hydrogels

    NASA Astrophysics Data System (ADS)

    Webber, Rebecca; Shull, Ken; Messersmith, Phillip; Madhav, Priti

    2001-03-01

    It was recently determined that L-3,4-dihydroxyphenylalanine (DOPA) is primarily responsible for both the adhesion and crosslinking that occurs in mussel adhesive proteins (MAPs). In wet environments, MAPs form strong adhesive bonds to a large variety of substrates, making DOPA-modified polymers very interesting for adhesion studies. Polymer materials modified from or modeled after DOPA have large potential as biomedical adhesives and as adhesives in aqueous environments. The mechanical and adhesive properties of a DOPA-containing hydrogel were tested using an axisymmetric adhesion test modified from the method of Johnson, Kendall and Roberts. In accordance with this technique, a rigid, hemispherical indenter was brought into contact with hydrogel samples, generating load and displacement data. In addition, images were taken of the contact between the sample and indenter. Using the collected data and images, the adhesive properties of the material were calculated. Separate experiments were conducted in conditions of varying humidity and aqueous environments in order to determine any changes in the adhesive behavior of the hydrogel. Data resulting from experiments in each type of environment will be presented.

  3. Understanding Marine Mussel Adhesion

    PubMed Central

    Roberto, Francisco F.

    2007-01-01

    In addition to identifying the proteins that have a role in underwater adhesion by marine mussels, research efforts have focused on identifying the genes responsible for the adhesive proteins, environmental factors that may influence protein production, and strategies for producing natural adhesives similar to the native mussel adhesive proteins. The production-scale availability of recombinant mussel adhesive proteins will enable researchers to formulate adhesives that are water-impervious and ecologically safe and can bind materials ranging from glass, plastics, metals, and wood to materials, such as bone or teeth, biological organisms, and other chemicals or molecules. Unfortunately, as of yet scientists have been unable to duplicate the processes that marine mussels use to create adhesive structures. This study provides a background on adhesive proteins identified in the blue mussel, Mytilus edulis, and introduces our research interests and discusses the future for continued research related to mussel adhesion. PMID:17990038

  4. Understanding Marine Mussel Adhesion

    SciTech Connect

    H. G. Silverman; F. F. Roberto

    2007-12-01

    In addition to identifying the proteins that have a role in underwater adhesion by marine mussels, research efforts have focused on identifying the genes responsible for the adhesive proteins, environmental factors that may influence protein production, and strategies for producing natural adhesives similar to the native mussel adhesive proteins. The production-scale availability of recombinant mussel adhesive proteins will enable researchers to formulate adhesives that are waterimpervious and ecologically safe and can bind materials ranging from glass, plastics, metals, and wood to materials, such as bone or teeth, biological organisms, and other chemicals or molecules. Unfortunately, as of yet scientists have been unable to duplicate the processes that marine mussels use to create adhesive structures. This study provides a background on adhesive proteins identified in the blue mussel, Mytilus edulis, and introduces our research interests and discusses the future for continued research related to mussel adhesion.

  5. Enzymatic degradation of adhesive-dentin interfaces produced by mild self-etch adhesives.

    PubMed

    De Munck, Jan; Mine, Atsushi; Van den Steen, Philippe E; Van Landuyt, Kirsten L; Poitevin, André; Opdenakker, Ghislain; Van Meerbeek, Bart

    2010-10-01

    Endogenous matrix metalloproteinases (MMPs) released by adhesive procedures may degrade collagen in the hybrid layer and so compromise the bonding effectiveness of etch-and-rinse adhesives. In this study, endogenous enzymatic degradation was evaluated for several simplified self-etch adhesives. In addition, primers were modified by adding two MMP inhibitors: chlorhexidine, a commonly used disinfectant, but also a non-specific MMP inhibitor; and SB-3CT, a specific inhibitor of MMP-2 and MMP-9. Gelatin zymography of fresh human dentin powder was used to identify the enzymes released by the adhesives. Micro-tensile bond strength (μTBS) testing was used to assess the mechanical properties of resin-dentin interfaces over time. In none of the experimental groups treated with the mild self-etch adhesives was MMP-2 and/or MMP-9 identified. Also, no difference in the μTBS was measured for the inhibitor-modified and the control inhibitor-free adhesives after 6 months of water storage. It is concluded that in contrast to etch-and-rinse adhesives, the involvement of endogenous MMP-2 and MMP-9 in the bond-degradation process is minimal for mild self-etch adhesives.

  6. Parallel 3D Mortar Element Method for Adaptive Nonconforming Meshes

    NASA Technical Reports Server (NTRS)

    Feng, Huiyu; Mavriplis, Catherine; VanderWijngaart, Rob; Biswas, Rupak

    2004-01-01

    High order methods are frequently used in computational simulation for their high accuracy. An efficient way to avoid unnecessary computation in smooth regions of the solution is to use adaptive meshes which employ fine grids only in areas where they are needed. Nonconforming spectral elements allow the grid to be flexibly adjusted to satisfy the computational accuracy requirements. The method is suitable for computational simulations of unsteady problems with very disparate length scales or unsteady moving features, such as heat transfer, fluid dynamics or flame combustion. In this work, we select the Mark Element Method (MEM) to handle the non-conforming interfaces between elements. A new technique is introduced to efficiently implement MEM in 3-D nonconforming meshes. By introducing an "intermediate mortar", the proposed method decomposes the projection between 3-D elements and mortars into two steps. In each step, projection matrices derived in 2-D are used. The two-step method avoids explicitly forming/deriving large projection matrices for 3-D meshes, and also helps to simplify the implementation. This new technique can be used for both h- and p-type adaptation. This method is applied to an unsteady 3-D moving heat source problem. With our new MEM implementation, mesh adaptation is able to efficiently refine the grid near the heat source and coarsen the grid once the heat source passes. The savings in computational work resulting from the dynamic mesh adaptation is demonstrated by the reduction of the the number of elements used and CPU time spent. MEM and mesh adaptation, respectively, bring irregularity and dynamics to the computer memory access pattern. Hence, they provide a good way to gauge the performance of computer systems when running scientific applications whose memory access patterns are irregular and unpredictable. We select a 3-D moving heat source problem as the Unstructured Adaptive (UA) grid benchmark, a new component of the NAS Parallel

  7. Parallel 3D Mortar Element Method for Adaptive Nonconforming Meshes

    NASA Technical Reports Server (NTRS)

    Feng, Huiyu; Mavriplis, Catherine; VanderWijngaart, Rob; Biswas, Rupak

    2004-01-01

    High order methods are frequently used in computational simulation for their high accuracy. An efficient way to avoid unnecessary computation in smooth regions of the solution is to use adaptive meshes which employ fine grids only in areas where they are needed. Nonconforming spectral elements allow the grid to be flexibly adjusted to satisfy the computational accuracy requirements. The method is suitable for computational simulations of unsteady problems with very disparate length scales or unsteady moving features, such as heat transfer, fluid dynamics or flame combustion. In this work, we select the Mark Element Method (MEM) to handle the non-conforming interfaces between elements. A new technique is introduced to efficiently implement MEM in 3-D nonconforming meshes. By introducing an "intermediate mortar", the proposed method decomposes the projection between 3-D elements and mortars into two steps. In each step, projection matrices derived in 2-D are used. The two-step method avoids explicitly forming/deriving large projection matrices for 3-D meshes, and also helps to simplify the implementation. This new technique can be used for both h- and p-type adaptation. This method is applied to an unsteady 3-D moving heat source problem. With our new MEM implementation, mesh adaptation is able to efficiently refine the grid near the heat source and coarsen the grid once the heat source passes. The savings in computational work resulting from the dynamic mesh adaptation is demonstrated by the reduction of the the number of elements used and CPU time spent. MEM and mesh adaptation, respectively, bring irregularity and dynamics to the computer memory access pattern. Hence, they provide a good way to gauge the performance of computer systems when running scientific applications whose memory access patterns are irregular and unpredictable. We select a 3-D moving heat source problem as the Unstructured Adaptive (UA) grid benchmark, a new component of the NAS Parallel

  8. Evaluation of sulfate resistance of cement mortars containing black rice husk ash.

    PubMed

    Chatveera, B; Lertwattanaruk, P

    2009-03-01

    In this paper, black rice husk ashes (BRHAs), which are agrowastes from an electricity generating power plant and a rice mill, were ground and used as a partial cement replacement. The durability of mortars under sulfate attack including expansion and compressive strength loss were investigated. For parametric study, BRHA were used as a Portland cement Type 1 replacement at the levels of 0%, 10%, 30%, and 50% by weight of binder. The water-to-binder ratios were 0.55 and 0.65. For the durability of mortar exposed to sulfate attack, 5% sodium sulfate (Na2SO4) and magnesium sulfate (MgSO4) solutions were used. As a result, when increasing the percentage replacement of BRHA, the expansion and compressive strength loss of mortar decreased. At the replacement levels of 30% and 50% of BRHA, the expansion of the mortars was less than those mixed with sulfate-resistant cement. However, the expansion of the mortars exposed to Na2SO4 was more than those exposed to MgSO4. Increasing the replacement level of BRHA tends to reduce the compressive strength loss of mortars exposed to Na2SO4 attack. In contrary, under MgSO4 attack, when increasing the replacement level of BRHA, the compressive strength loss increases from 0% to 50% in comparison to Portland cement mortar. Results show that ground BRHA can be applied as a pozzolanic material to concrete and also improve resistance to sodium sulfate attack, but it can impair resistance to magnesium sulfate attack.

  9. Assessing the effects of UVA photocatalysis on soot-coated TiO2-containing mortars.

    PubMed

    De la Rosa, José M; Miller, Ana Z; Pozo-Antonio, J Santiago; González-Pérez, José A; Jiménez-Morillo, Nicasio T; Dionisio, Amelia

    2017-12-15

    The deposition of soot on building surfaces darkens their colour and leads to undesirable black crusts, which are one of the most serious problems on the conservation of built cultural heritage. As a preventive strategy, self-cleaning systems based on the use of titanium dioxide (TiO2) coatings have been employed on building materials for degrading organic compounds deposited on building surfaces, improving their durability and performance. In this study, the self-cleaning effect of TiO2-containing mortars coated with diesel soot has been appraised under laboratory conditions. The mortar samples were manufactured using lime putty and two different doses of TiO2 (2.5% and 5%). The lime mortars were then coated with diesel engine soot and irradiated with ultraviolet A (UVA) illumination for 30days. The photocatalytic efficiency was evaluated by visual inspection, field emission scanning electron microscopy (FESEM) and colour spectrophotometry. Changes in the chemical composition of the soot particles (including persistent organic pollutants) were assessed by analytical pyrolysis (Py-GC/MS) and solid state (13)C NMR spectroscopy. The FESEM and colour spectrophotometry revealed that the soot-coated TiO2-containing mortars promoted a self-cleaning effect after UVA irradiation. The combination of analytical pyrolysis and (13)C solid state NMR showed that the UVA irradiation caused the cracking of polycyclic aromatic structures and n-alkyl compounds of the diesel soot and its transformation into methyl polymers. Our findings also revealed that the inclusion of TiO2 in the lime mortar formulations catalysed these transformations promoting the self-cleaning of the soot-stained mortars. The combined action of TiO2 and UVA irradiation is a promising proxy to clean lime mortars affected by soot deposition. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Material properties of hollow clay tile and existing mortar characterization study

    SciTech Connect

    Butala, M.B.; Jones, W.D.

    1993-10-01

    Several Buildings at the Department of Energy (DOE) Oak Ridge Y-12 Plant were constructed (circa 1950) using unreinforced hollow clay tile (UHCT) masonry walls, which act as shear walls to resist lateral forces. A comprehensive test program, managed by the Center for Natural Phenomena Engineering (CNPE) of Martin Marietta Energy Systems, Inc. (MMES), is under way to determine material properties of existing hollow clay tile walls that will be used to help determine the structural strength of those buildings. This paper presents the results of several types of material property tests of 4-in.- and 8-in.-thick hollow clay tiles. These tests include determination of weight, size, void area, net area and gross area, initial rate of absorption, absorption, modules of rupture, splitting tensile strength, and compressive strength. The tests were performed on old, reclaimed tiles and new tiles. A total of 336 tiles were tested. The stress-strain relationship for 40 specimens was also obtained. All testing was performed in accordance with ASTM standards and procedures developed by CNPE. This paper also presents the results of an investigation of mortar removed from the existing walls. The mortar characterization study was performed by Testwell Craig Materials Consultants (TCMC) under subcontract to MMES. Petrographic and chemical investigations were conducted on 18 mortar samples removed from four buildings at the plant. The primary purpose of the investigations was to evaluate the properties of existing mortar and provide a similar specification for the mortar to be used for construction of test specimens and test walls for the test program. The study showed variability in the mortars among buildings and among different locations within a building; it was concluded that an average mortar mix conforming to ASTM type N proportioned by volume of Portland cement, hydrated lime, and Tennessee river sand would be used to conduct further laboratory studies of masonry assemblages.

  11. High-performance therapeutic quercetin-doped adhesive for adhesive-dentin interfaces.

    PubMed

    Yang, Hongye; Li, Kang; Yan, Huiyi; Liu, Siying; Wang, Yake; Huang, Cui

    2017-08-15

    Almost half of dental restorations have failed in less than 10 years, and approximately 60% of practice time has been consumed to replace these dental restorations. As such, contemporary dentin adhesives should be modified to treat secondary caries and prevent the degradation of adhesive-dentin interfaces. To achieve this goal, we developed a versatile therapeutic adhesive in the present study by incorporating quercetin, which is a naturally derived plant extract, into a commercial adhesive at three concentrations (100, 500 and 1000 µg/mL). An unmodified adhesive served as a control. The antibacterial ability on Streptococcus mutans biofilm, conversion degree, microtensile bond strength, failure modes, in situ zymography, nanoleakage expression and cytotoxicity of quercetin-doped adhesive were comprehensively evaluated. Results showed that the quercetin-doped adhesive (500 µg/mL) preserved its bonding properties against collagenase ageing and inhibited the growth of S. mutans biofilm. Efficient bonding interface sealing ability, matrix metalloproteinase inhibition and acceptable biocompatibility were also achieved. Thus, a simple, safe and workable strategy was successfully developed to produce therapeutic adhesives for the extension of the service life of adhesive restorations.

  12. Properties of mortars made by uncalcined FGD gypsum-fly ash-ground granulated blast furnace slag composite binder

    SciTech Connect

    Zhong Shiyun; Ni Kun; Li Jinmei

    2012-07-15

    Highlights: Black-Right-Pointing-Pointer The mortar with uncalcined FGD gypsum has suitable workability. Black-Right-Pointing-Pointer The strength of mortar with uncalcined FGD gypsum is higher than that of mortar without uncalcined FGD gypsum. Black-Right-Pointing-Pointer The dry shrinkage of mortar with uncalcined FGD gypsum is lower than that of mortar without uncalcined FGD gypsum. Black-Right-Pointing-Pointer The leaching of sulfate ion of mortar is studied. - Abstract: A series of novel mortars were developed from composite binder of uncalcined FGD gypsum, fly ash (FA) and ground granulated blast furnace slag (GGBFS) for the good utilization of flue gas desulphurization (FGD) gypsum. At a fixed ratio (20%) of GGBFS to the composite binder, keeping consistency of the mortar between 9.5 and 10.0 cm, the properties of the composite mortar were studied. The results show that higher water/binder (W/B) is required to keep the consistency when increasing the percentage of FGD gypsum. No obvious influences of the W/B and content of FGD gypsum on the bleeding of paste were observed which keeps lower than 2% under all experimental conditions tried. The highest compressive and flexural strengths (ratio is 20% FGD gypsum, 20% GGBFS and 60% FA) are 22.6 and 4.3 MPa at 28 days, respectively. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results indicate that massive ettringite crystals and C-S-H gels exist in the hydration products. At 90 days the mortars with FGD gypsum is dramatically smaller drying shrinkage (563-938 micro strain) than that without FGD gypsum (about 2250 micro strain). The release of the SO{sub 4}{sup 2-} from the mortar was analyzed, indicating that the dissolution of sulfate increases with FGD gypsum. The concentration of SO{sub 4}{sup 2-} releasing from the mortar with 10% FGD gypsum is almost equal to that obtained from the mortar without FGD gypsum. The release of SO{sub 4}{sup 2-} from the mortar with 20% FGD gypsum is 9200 mg

  13. Chapter 9:Wood Adhesion and Adhesives

    Treesearch

    Charles R. Frihart

    2013-01-01

    The recorded history of bonding wood dates back at least 3000 years to the Egyptians (Skeist and Miron 1990, River 1994a), and adhesive bonding goes back to early mankind (Keimel 2003). Although wood and paper bonding are the largest applications for adhesives, some of the fundamental aspects leading to good bonds are not fully understood. Better understanding of these...

  14. Evaluation of nitric and acetic acid resistance of cement mortars containing high-volume black rice husk ash.

    PubMed

    Chatveera, B; Lertwattanaruk, P

    2014-01-15

    This paper presents the performance of cement mortar containing black rice husk ash (BRHA) under nitric and acetic acid attacks. The BRHA, collected from an electrical generating power plant that uses rice husk as fuel, was ground using a grinding machine. The compressive strength loss, weight loss, and expansion of mortars under nitric and acetic acid attack were investigated. The test results of BRHA properties in accordance with the ASTM C 618 standard found that the optimal grinding time was 4 h as this achieved a Blaine fineness of 5370 cm(2)/g. For parametric study, BRHA were used as a Portland cement Type 1 replacement at the levels of 0%, 10%, 20%, 30%, 40%, and 50% by weight of binder. The water-to-binder ratios were 0.55, 0.60, and 0.65. From test results, when the percentage replacements of BRHA in cement increased, it was observed that the strength loss and weight loss of mortars containing BRHA under acetic acid attack were higher than those of the mortars against nitric acid attack. It was found that, of the various BHRA mortars, the strength loss and weight loss due to nitric and acetic acid attacks were the lowest in the mortar with 10% BRHA replacement. For 10%, 20% and 30% BRHA replacements, the rate of expansion of the BRHA mortar decreased when compared with the control mortar. For the mortars with other percentage replacements of BRHA, the rate of expansion increased. Furthermore, the effective water-to-binder ratios of control and BRHA mortars were the primary factor for determining the durability of mortar mixed with BRHA. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Effects of the restoration mortar on chalk stone buildings

    NASA Astrophysics Data System (ADS)

    Ion, R. M.; Teodorescu, S.; Ştirbescu, R. M.; Dulamă, I. D.; Şuică-Bunghez, I. R.; Bucurică, I. A.; Fierăscu, R. C.; Fierscu, I.; Ion, M. L.

    2016-06-01

    The monument buildings as components of cultural heritage are exposed to degradation of surfaces and chemical and mechanical degradation, often associated to soiling and irreversible deterioration of the building. In many conservative and restorative works, a cement-based mortar was used without knowing all the adverse effects of this material on the building. This paper deals with the study of the effects of natural cement used in restorative works in the particular case of the Basarabi-Murfatlar Churches Ensemble. Cement-based materials exposed to sulfate present in the chalk stone - gypsum (CaSO4.2H2O), can induce signs of deterioration, due to ettringite ([Ca3Al (OH)612H2O]2(SO4)32H2O) or thaumasite (Ca3[Si(OH)612H2O](CO3)SO4) formation. These phases contribute to strain within the material, inducing expansion, strength loss, spalling and severe degradation. Several combined techniques (XRD, EDXRF, ICP-AES, SEM, EDS, sulphates content, FT-IR and Raman analysis were carried out to put into evidence the effects of them on the building walls.

  16. Influence of Rubber Size on Properties of Crumb Rubber Mortars

    PubMed Central

    Yu, Yong; Zhu, Han

    2016-01-01

    Studies on the properties and applications of rubber cement-based materials are well documented. The sizes of rubbers used in these materials varied. However, information about the effects of rubber size on the properties of rubber cement-based materials, especially pore structure, mechanical strengths, and drying shrinkage properties, remains limited. Three groups of rubber with major particle sizes of 2–4 mm, 1–3 mm, and 0–2 mm were selected in this study. This paper presents experimental studies on the effects of rubber size on the consistency, fresh density, pore structure, mechanical properties, and drying shrinkage properties of crumb rubber mortars (CRMs). Results demonstrated that the consistency and fresh density of CRMs decreased with the rubber size. As to the pore structure, the total pore volume increased with the decrease of the rubber size. By contrast, the influence of the rubber size on the mesopore (<50 nm) volume is not as significant as that of the rubber content. The mechanical properties of CRMs decreased with the rubber size. Low rubber stiffness and large pore volumes, especially those of small sized rubbers, contribute to the reduction of CRMs strength. The drying shrinkage of CRM increases as the rubber size decreases. The influences of rubber size on capillary tension are not significant. Thus, the shrinkage increases with the decrease of rubber size mainly because of its function in the deformation modulus reduction of CRMs. PMID:28773649

  17. Influence of Rubber Size on Properties of Crumb Rubber Mortars.

    PubMed

    Yu, Yong; Zhu, Han

    2016-06-29

    Studies on the properties and applications of rubber cement-based materials are well documented. The sizes of rubbers used in these materials varied. However, information about the effects of rubber size on the properties of rubber cement-based materials, especially pore structure, mechanical strengths, and drying shrinkage properties, remains limited. Three groups of rubber with major particle sizes of 2-4 mm, 1-3 mm, and 0-2 mm were selected in this study. This paper presents experimental studies on the effects of rubber size on the consistency, fresh density, pore structure, mechanical properties, and drying shrinkage properties of crumb rubber mortars (CRMs). Results demonstrated that the consistency and fresh density of CRMs decreased with the rubber size. As to the pore structure, the total pore volume increased with the decrease of the rubber size. By contrast, the influence of the rubber size on the mesopore (<50 nm) volume is not as significant as that of the rubber content. The mechanical properties of CRMs decreased with the rubber size. Low rubber stiffness and large pore volumes, especially those of small sized rubbers, contribute to the reduction of CRMs strength. The drying shrinkage of CRM increases as the rubber size decreases. The influences of rubber size on capillary tension are not significant. Thus, the shrinkage increases with the decrease of rubber size mainly because of its function in the deformation modulus reduction of CRMs.

  18. Rheological studies on pressure-sensitive silicone adhesives and drug-in-adhesive layers as a means to characterise adhesive performance.

    PubMed

    Ho, Kwong Yat; Dodou, Kalliopi

    2007-03-21

    Pressure-sensitive adhesives are viscoelastic polymers used in the formulation of transdermal patches that allow attachment of a patch onto the skin. Established criteria exist that correlate viscoelastic parameters with adhesive performance. In this study, fulfillment of the adhesive performance criteria was examined using two silicone adhesives with different tack properties. The viscoelastic parameters of high and low tack silicone adhesives (BIO-PSA High Tack 7-4302 and BIO-PSA Low Tack 7-4102) were determined and compared with the criteria described by Chu and Dahlquist. Drug-in-adhesive layers were prepared using the high tack adhesive combined with nortriptyline HCl or paracetamol. The effect of drug addition on the viscoelastic properties of the adhesive was examined. The high tack adhesive showed congruence with the established criteria although with a modified range of viscoelastic moduli to that described by Chu. Examination of the low tack adhesive showed that it did not possess the appropriate viscoelastic properties for bonding onto the skin. The addition of the drugs into the high tack adhesive caused a concentration-dependent increase in its cohesive strength. This effect was independent of the physicochemical properties of the drugs tested.

  19. Quantitative sensing of corroded steel rebar embedded in cement mortar specimens using ultrasonic testing

    NASA Astrophysics Data System (ADS)

    Owusu Twumasi, Jones; Le, Viet; Tang, Qixiang; Yu, Tzuyang

    2016-04-01

    Corrosion of steel reinforcing bars (rebars) is the primary cause for the deterioration of reinforced concrete structures. Traditional corrosion monitoring methods such as half-cell potential and linear polarization resistance can only detect the presence of corrosion but cannot quantify it. This study presents an experimental investigation of quantifying degree of corrosion of steel rebar inside cement mortar specimens using ultrasonic testing (UT). A UT device with two 54 kHz transducers was used to measure ultrasonic pulse velocity (UPV) of cement mortar, uncorroded and corroded reinforced cement mortar specimens, utilizing the direct transmission method. The results obtained from the study show that UPV decreases linearly with increase in degree of corrosion and corrosion-induced cracks (surface cracks). With respect to quantifying the degree of corrosion, a model was developed by simultaneously fitting UPV and surface crack width measurements to a two-parameter linear model. The proposed model can be used for predicting the degree of corrosion of steel rebar embedded in cement mortar under similar conditions used in this study up to 3.03%. Furthermore, the modeling approach can be applied to corroded reinforced concrete specimens with additional modification. The findings from this study show that UT has the potential of quantifying the degree of corrosion inside reinforced cement mortar specimens.

  20. Lime-pozzolana mortars in Roman catacombs: composition, structures and restoration

    SciTech Connect

    Sanchez-Moral, Sergio; Soler, Vicente; Garcia-Guinea, Javier

    2005-08-01

    Analyses of microsamples collected from Roman catacombs and samples of lime-pozzolana mortars hardened in the laboratory display higher contents in carbonated binder than other subaerial Roman monuments. The measured environmental data inside the Saint Callistus and Domitilla catacombs show a constant temperature of 15-17 deg C, a high CO{sub 2} content (1700 to 3500 ppm) and a relative humidity close to 100%. These conditions and particularly the high CO{sub 2} concentration speed-up the lime calcitization roughly by 500% and reduce the cationic diffusion to form hydrous calcium aluminosilicates. The structure of Roman catacomb mortars shows (i) coarser aggregates and thicker beds on the inside, (ii) thin, smoothed, light and fine-grained external surfaces with low content of aggregates and (iii) paintings and frescoes on the outside. The observed high porosity of the mortars can be attributed to cracking after drying linked with the high binder content. Hardened lime lumps inside the binder denote low water/mortar ratios for slaking. The aggregate tephra pyroclasts rich in aluminosilicate phases with accessorial amounts of Ba, Sr, Rb, Cu and Pb were analysed through X-ray diffraction (XRD), electron microprobe analysis (EMPA) and also by environmental scanning electron microscopy (ESEM) to identify the size and distribution of porosity. Results support procedures using local materials, special mortars and classic techniques for restoration purposes in hypogeal backgrounds.

  1. Effects of magnesium sulfate concentration on the sulfate resistance of mortars with and without silica fume

    SciTech Connect

    Tuerker, F.; Akoez, F.; Koral, S.; Yuezer, N.

    1997-02-01

    An investigation was carried out on the resistance of mortars to magnesium sulfate attack. Experiments were carried out on portland cement (PC) and portland cement-silica fume (PC-SF) mortars. Mortars were immersed in magnesium sulfate solutions after 28 days of lime-saturated water curing. Concentrations were 1900, 13,000 and 52,000 mg/L as SO{sub 4}{sup {minus}2} solutions. A number of physical and mechanical properties were determined at different periods of exposure up to 300 days. For the first 28 days of exposure, some improvements of mortar properties in magnesium sulfate environment were observed. This is the early stage of sulfate attack. Thereafter, negative changes of the properties indicate a transition stage. Deterioration process of mortars was retarded by the presence of silica fume. After the transition stage, negative changes of physical properties accelerate, indicating the later stage. Compressive and flexural strength properties showed different response to magnesium sulfate attack at later stage. Only in 52,000 mg/L concentration, all the measured properties showed clear negative changes.

  2. Coupled Effect of Elevated Temperature and Cooling Conditions on the Properties of Ground Clay Brick Mortars

    NASA Astrophysics Data System (ADS)

    Ali Abd El Aziz, Magdy; Abdelaleem, Salh; Heikal, Mohamed

    2013-12-01

    When a concrete structure is exposed to fire and cooling, some deterioration in its chemical resistivity and mechanical properties takes place. This deterioration can reach a level at which the structure may have to be thoroughly renovated or completely replaced. In this investigation, four types of cement mortars, ground clay bricks (GCB)/sand namely 0/3, 1/2, 2/1 and 3/0, were used. Three different cement contents were used: 350, 400 and 450 kg/m3. All the mortars were prepared and cured in tap water for 3 months and then kept in laboratory atmospheric conditions up to 6 months. The specimens were subjected to elevated temperatures up to 700°C for 3h and then cooled by three different conditions: water, furnace, and air cooling. The results show that all the mortars subjected to fire, irrespective of cooling mode, suffered a significant reduction in compressive strength. However, the mortars cooled in air exhibited a relativity higher reduction in compressive strength rather than those water or furnace cooled. The mortars containing GCB/sand (3/0) and GCB/sand (1/2) exhibited a relatively higher thermal stability than the others.

  3. Immobilization in cement mortar of chromium removed from water using titania nanoparticles.

    PubMed

    Husnain, Ahmed; Qazi, Ishtiaq Ahmed; Khaliq, Wasim; Arshad, Muhammad

    2016-05-01

    Because of the high toxicity of chromium, particularly as Cr (VI), it is removed from industrial effluents before their discharge into water bodies by a variety of techniques, including adsorption. Ultimate disposal of the sludge or the adsorbate, however, is a serious problem. While titania, in nanoparticle form, serves as a very good adsorbent for chromium, as an additive, it also helps to increase the compressive strength of mortar and concrete. Combining these two properties of the material, titania nanoparticles were used to adsorb chromium and then added to mortar up to a concentration of 20% by weight. The compressive strength of the resulting mortar specimens that replaced 15% of cement with chromium laden titania showed an improved strength than that without titania, thus confirming that this material had positive effect on the mortar strength. Leachate tests using the Toxicity Characteristics Leaching Procedure (TCLP) confirmed that the mortar sample chromium leachate was well within the permissible limits. The proposed technique thus offers a safe and viable method for the ultimate disposal of toxic metal wastes, in general, and those laden waste chromium, in particular.

  4. Acoustic Behavior of Subfloor Lightweight Mortars Containing Micronized Poly (Ethylene Vinyl Acetate) (EVA)

    PubMed Central

    Brancher, Luiza R.; Nunes, Maria Fernanda de O.; Grisa, Ana Maria C.; Pagnussat, Daniel T.; Zeni, Mára

    2016-01-01

    This paper aims to contribute to acoustical comfort in buildings by presenting a study about the polymer waste micronized poly (ethylene vinyl acetate) (EVA) to be used in mortars for impact sound insulation in subfloor systems. The evaluation method included physical, mechanical and morphological properties of the mortar developed with three distinct thicknesses designs (3, 5, and 7 cm) with replacement percentage of the natural aggregate by 10%, 25%, and 50% EVA. Microscopy analysis showed the surface deposition of cement on EVA, with preservation of polymer porosity. The compressive creep test estimated long-term deformation, where the 10% EVA sample with a 7 cm thick mortar showed the lowest percentage deformation of its height. The impact noise test was performed with 50% EVA samples, reaching an impact sound insulation of 23 dB when the uncovered slab was compared with the 7 cm thick subfloor mortar. Polymer waste addition decreased the mortar compressive strength, and EVA displayed characteristics of an influential material to intensify other features of the composite. PMID:28787851

  5. Mechanical Properties of Epoxy Resin Mortar with Sand Washing Waste as Filler.

    PubMed

    Yemam, Dinberu Molla; Kim, Baek-Joong; Moon, Ji-Yeon; Yi, Chongku

    2017-02-28

    The objective of this study was to investigate the potential use of sand washing waste as filler for epoxy resin mortar. The mechanical properties of four series of mortars containing epoxy binder at 10, 15, 20, and 25 wt. % mixed with sand blended with sand washing waste filler in the range of 0-20 wt. % were examined. The compressive and flexural strength increased with the increase in epoxy and filler content; however, above epoxy 20 wt. %, slight change was seen in strength due to increase in epoxy and filler content. Modulus of elasticity also linearly increased with the increase in filler content, but the use of epoxy content beyond 20 wt. % decreased the modulus of elasticity of the mortar. For epoxy content at 10 wt. %, poor bond strength lower than 0.8 MPa was observed, and adding filler at 20 wt. % adversely affected the bond strength, in contrast to the mortars containing epoxy at 15, 20, 25 wt. %. The results indicate that the sand washing waste can be used as potential filler for epoxy resin mortar to obtain better mechanical properties by adding the optimum level of sand washing waste filler.

  6. Neutron attenuation characteristics of polyethylene, polyvinyl chloride, and heavy aggregate concrete and mortars.

    PubMed

    Abdul-Majid, S; Othman, F

    1994-03-01

    Polyethylene and polyvinyl chloride pellets were introduced into concrete to improve its neutron attenuation characteristics while several types of heavy coarse aggregates were used to improve its gamma ray attenuation properties. Neutron and gamma ray attenuation were studied in concrete samples containing coarse aggregates of barite, pyrite, basalt, hematite, and marble as well as polyethylene and polyvinyl chloride pellets in narrow-beam geometry. The highest neutron attenuation was shown by polyethylene mortar, followed by polyvinyl chloride mortar; barite and pyrite concrete showed higher gamma ray attenuation than ordinary concrete. Broad-beam and continuous (infinite) medium geometries were used to study the neutron attenuation of samples containing polymers at different concentrations with and without heavy aggregates, the fitting equations were established, and from these the neutron removal coefficients were deduced. In a radiation field of neutrons and gamma rays, the appropriate concentration of polymer and heavy aggregate can be selected to give the optimum total dose attenuation depending on the relative intensities of each type of radiation. This would give much better design flexibility over ordinary concrete. The compressive strength tests performed on mortar and concrete samples showed that their value, in general, decreases as polymer concentration increases and that the polyvinyl chloride mortar showed higher values than the polyethylene mortar. For general construction purposes, the compression strength was considered acceptable in these samples.

  7. Acoustic Behavior of Subfloor Lightweight Mortars Containing Micronized Poly (Ethylene Vinyl Acetate) (EVA).

    PubMed

    Brancher, Luiza R; Nunes, Maria Fernanda de O; Grisa, Ana Maria C; Pagnussat, Daniel T; Zeni, Mára

    2016-01-15

    This paper aims to contribute to acoustical comfort in buildings by presenting a study about the polymer waste micronized poly (ethylene vinyl acetate) (EVA) to be used in mortars for impact sound insulation in subfloor systems. The evaluation method included physical, mechanical and morphological properties of the mortar developed with three distinct thicknesses designs (3, 5, and 7 cm) with replacement percentage of the natural aggregate by 10%, 25%, and 50% EVA. Microscopy analysis showed the surface deposition of cement on EVA, with preservation of polymer porosity. The compressive creep test estimated long-term deformation, where the 10% EVA sample with a 7 cm thick mortar showed the lowest percentage deformation of its height. The impact noise test was performed with 50% EVA samples, reaching an impact sound insulation of 23 dB when the uncovered slab was compared with the 7 cm thick subfloor mortar. Polymer waste addition decreased the mortar compressive strength, and EVA displayed characteristics of an influential material to intensify other features of the composite.

  8. Use of waste brick as a partial replacement of cement in mortar.

    PubMed

    Naceri, Abdelghani; Hamina, Makhloufi Chikouche

    2009-08-01

    The aim of this study is to investigate the use of waste brick as a partial replacement for cement in the production of cement mortar. Clinker was replaced by waste brick in different proportions (0%, 5%, 10%, 15% and 20%) by weight for cement. The physico-chemical properties of cement at anhydrous state and the hydrated state, thus the mechanical strengths (flexural and compressive strengths after 7, 28 and 90 days) for the mortar were studied. The microstructure of the mortar was investigated using scanning electron microscopy (SEM), the mineralogical composition (mineral phases) of the artificial pozzolan was investigated by the X-ray diffraction (XRD) and the particle size distributions was obtained from laser granulometry (LG) of cements powders used in this study. The results obtained show that the addition of artificial pozzolan improves the grinding time and setting times of the cement, thus the mechanical characteristics of mortar. A substitution of cement by 10% of waste brick increased mechanical strengths of mortar. The results of the investigation confirmed the potential use of this waste material to produce pozzolanic cement.

  9. Use of waste brick as a partial replacement of cement in mortar

    SciTech Connect

    Naceri, Abdelghani Hamina, Makhloufi Chikouche

    2009-08-15

    The aim of this study is to investigate the use of waste brick as a partial replacement for cement in the production of cement mortar. Clinker was replaced by waste brick in different proportions (0%, 5%, 10%, 15% and 20%) by weight for cement. The physico-chemical properties of cement at anhydrous state and the hydrated state, thus the mechanical strengths (flexural and compressive strengths after 7, 28 and 90 days) for the mortar were studied. The microstructure of the mortar was investigated using scanning electron microscopy (SEM), the mineralogical composition (mineral phases) of the artificial pozzolan was investigated by the X-ray diffraction (XRD) and the particle size distributions was obtained from laser granulometry (LG) of cements powders used in this study. The results obtained show that the addition of artificial pozzolan improves the grinding time and setting times of the cement, thus the mechanical characteristics of mortar. A substitution of cement by 10% of waste brick increased mechanical strengths of mortar. The results of the investigation confirmed the potential use of this waste material to produce pozzolanic cement.

  10. Strength and Density of Geopolymer Mortar Cured at Ambient Temperature for Use as Repair Material

    NASA Astrophysics Data System (ADS)

    Warid Wazien, A. Z.; Bakri Abdullah, Mohd Mustafa Al; Abd. Razak, Rafiza; Mohd Remy Rozainy, M. A. Z.; Faheem Mohd Tahir, Muhammad

    2016-06-01

    Geopolymers produced by synthesizing aluminosilicate source materials with an alkaline activator solution promised an excellent properties akin to the existing construction material. This study focused on the effect of various binder to sand ratio on geopolymer mortar properties. Mix design of geopolymer mortar was produced using NaOH concentration of 12 molars, ratio of fly ash/alkaline activator and ratio Na2SiO3/NaOH of 2.0 and 2.5 respectively. Samples subsequently ware cured at ambient temperature. The properties of geopolymer mortar were analysed in term of compressive strength and density at different period which are on the 3rd and 7th day of curing. Experimental results revealed that the addition of sand slightly increase the compressive strength of geopolymer. The optimum compressive strength obtained was up to 31.39 MPa on the 7th day. The density of geopolymer mortar was in the range between 2.0 g/cm3 to 2.23 g/cm3. Based on this findings, the special properties promoted by geopolymer mortar display high potential to be implemented in the field of concrete patch repair.

  11. PH dependent adhesive peptides

    DOEpatents

    Tomich, John; Iwamoto, Takeo; Shen, Xinchun; Sun, Xiuzhi Susan

    2010-06-29

    A novel peptide adhesive motif is described that requires no receptor or cross-links to achieve maximal adhesive strength. Several peptides with different degrees of adhesive strength have been designed and synthesized using solid phase chemistries. All peptides contain a common hydrophobic core sequence flanked by positively or negatively charged amino acids sequences.

  12. Functionally Graded Adhesives

    DTIC Science & Technology

    2009-11-01

    ASTM 907-05. Standard Terminology of Adhesives. West Conshohocken, PA, May 2005. 4. 3M Scotch-Grip Nitrile High Performance Rubber & Gasket Adhesive...distribution is unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT The goal of this project was to increase rubber to metal adhesion in Army materials using...1 Figure 2. Steel and rubber

  13. Techniques for application of tissue adhesive for corneal perforations.

    PubMed

    Erdey, R A; Lindahl, K J; Temnycky, G O; Aquavella, J V

    1991-06-01

    We describe a modified technique of using cyanoacrylate adhesive to seal corneal perforations. Easily performed at the slit lamp, its advantages over previously described methods include a smooth, contoured collagen surface overlying the adhesive, which is easily wet by the tear film. Even greater comfort and protection are provided by the addition of a hydrophilic bandage lens or collagen shield.

  14. Nondestructive testing of adhesive bonds by nuclear quadrupole resonance method

    NASA Technical Reports Server (NTRS)

    Hewitt, R. R.

    1971-01-01

    Inert, strain sensitive tracer, cuprous oxide, added to polymeric adhesive ensures sufficiently large signal to noise ratio in NQR system output. Method is successful, provided that RF-transparent structural materials are used between modified adhesive and probe of NQR spectrometer.

  15. Metal-Filled Adhesives Amenable To X-Ray Inspection

    NASA Technical Reports Server (NTRS)

    Hermansen, Ralph D.; Sutherland, Thomas H.; Predmore, Roamer

    1994-01-01

    Adhesive joints between metal parts made amenable to nondestructive radiographic inspection by incorporating radiopaque fillers that increase x-ray contrasts of joints. Adhesives can be epoxies, urethanes, acrylics, phenolics, or silicones, with appropriate curing agents and with such modifiers as polysulfides, polyamides, or butadiene rubbers.

  16. The Impact of Involvement in Mortar Board Senior Honor Society on Lifelong Views of Civic Engagement and Leadership

    ERIC Educational Resources Information Center

    Turner, Daniel James

    2012-01-01

    This study examines the impact that involvement in Mortar Board National Senior Honor Society has on lifelong views of civic engagement and leadership. Mortar Board Senior Honor Society is a collegiate honor society established in 1918 that recognizes students for their outstanding contributions to their college or university community in the…

  17. Properties, characterization, and decay of sticky rice–lime mortars from the Wugang Ming dynasty city wall (China)

    SciTech Connect

    Xiao, Ya; Fu, Xuan; Gu, Haibing; Gao, Feng; Liu, Shaojun

    2014-04-01

    Urgent restoration of the Wugang Ming dynasty city wall brings about the need for a study of the formulation and properties of mortars. In the present paper, mortar samples from the Wugang Ming dynasty city wall were characterized in a combination of sheet polarized light optical microscopy, scanning electron microscopy with X-ray energy dispersive spectrometer, thermogravimetric/differential scanning calorimetry, X-ray powder diffraction, Fourier transform infrared spectroscopy, and inductively coupled plasma emission spectroscopy. Results show that mortars are mainly built up from inorganic calcium carbonate based organic–inorganic hybrid material with a small amount of sticky rice, which plays a crucial role in forming dense and compact microstructure of mortars and effectively hindering penetration of water and air into mortars. Analysis of decayed products shows that the detrimental soluble salts originates from ambient environment. - Highlights: • Mortars used in the Wugang city wall are a calcium carbonate-sticky rice hybrid bonding material. • Carbonation processing is extremely slow due to dense and compact microstructure of mortars. • Decying of mortars results from the appearance of soluble salt from ambient environment.

  18. Adhesion Control between Resist and Photomask Blank

    NASA Astrophysics Data System (ADS)

    Kurihara, Masaaki; Hatakeyama, Sho; Yoshida, Kouji; Abe, Makoto; Totsukawa, Daisuke; Morikawa, Yasutaka; Mohri, Hiroshi; Hoga, Morihisa; Hayashi, Naoya; Ohtani, Hiroyuki; Fujihira, Masamichi

    2009-06-01

    Most problems in photomask fabrication such as pattern collapse, haze, and cleaning damage are related to the behavior of surfaces and interfaces of resists, opaque layers, and quartz substrates. Therefore, it is important to control the corresponding surface and interface energies in photomask fabrication processes. In particular, adhesion analysis in microscopic regions is strongly desirable to optimize material and process designs in photomask fabrication. We applied the direct peeling (DP) method with a scanning probe microscope (SPM) tip and measured the adhesion of resist patterns on Cr and quartz surfaces for photomask process optimization. We also studied the effect of tip shape on the reproducibility of adhesion measurements and the dependence of collapse behavior on the resist profile. We measured lateral forces between the resulting collapsed resist pillar and the Cr or the quartz surface before and after the sliding and related these observed lateral forces to the static and kinetic frictional forces, respectively. We also studied the effect of surface modification of the Cr and quartz surfaces with silanization reagents on adhesion measured with the DP method. Resist adhesion could be controlled by surface modification using silanes. We also discuss the relationship between the adhesion observed with the DP method and the properties of the modified surfaces including water contact angles and local adhesive forces measured from force-distance curves with an SPM.

  19. Mini-review: barnacle adhesives and adhesion.

    PubMed

    Kamino, Kei

    2013-01-01

    Barnacles are intriguing, not only with respect to their importance as fouling organisms, but also in terms of the mechanism of underwater adhesion, which provides a platform for biomimetic and bioinspired research. These aspects have prompted questions regarding how adult barnacles attach to surfaces under water. The multidisciplinary and interdisciplinary nature of the studies makes an overview covering all aspects challenging. This mini-review, therefore, attempts to bring together aspects of the adhesion of adult barnacles by looking at the achievements of research focused on both fouling and adhesion. Biological and biochemical studies, which have been motivated mainly by understanding the nature of the adhesion, indicate that the molecular characteristics of barnacle adhesive are unique. However, it is apparent from recent advances in molecular techniques that much remains undiscovered regarding the complex event of underwater attachment. Barnacles attached to silicone-based elastomeric coatings have been studied widely, particularly with respect to fouling-release technology. The fact that barnacles fail to attach tenaciously to silicone coatings, combined with the fact that the mode of attachment to these substrata is different to that for most other materials, indicates that knowledge about the natural mechanism of barnacle attachment is still incomplete. Further research on barnacles will enable a more comprehensive understanding of both the process of attachment and the adhesives used. Results from such studies will have a strong impact on technology aimed at fouling prevention as well as adhesion science and engineering.

  20. Understanding adhesive dentistry.

    PubMed

    Burrow, Michael

    2010-03-01

    This review paper firstly provides an outline of the development of resin-based adhesives. A simple classification method is described based on whether an acid etching agent requiring a washing and drying step is used. These systems are called etch and rinse systems. The other adhesives that do not have the washing and drying steps are referred to as self-etching adhesives. The advantages and disadvantages of these groups of adhesives are discussed. Methods of adhering to the tooth surface are provided, especially where the resin-based adhesive reliability is difficult to control.

  1. Mechanical behavior of mortars containing sewage sludge ash (SSA) and Portland cements with different tricalcium aluminate content

    SciTech Connect

    Monzo, J.; Paya, J.; Borrachero, M.V.; Peris-Mora, E.

    1999-01-01

    The influence of sewage sludge ash (SSA) on cement mortars strength has been studied. To evaluate better the increase of strength compared to control mortar, relative compressive strength gain (CSGr) and flexural strength gain (FSGr) were calculated. The experience shows that SSA behaves as an active material, producing an increase of compressive strength compared to control mortar, probably due to pozzolanic properties of SSA. It can be emphasized that high sulfur content of SSA (12.4%) does not seem to have influence on compressive strength of mortars containing SSA. When CSGr of mortars containing different types of cements are compared, no clear correlation is observed between CSGr and C{sub 3}A content in cement.

  2. Effect of various superplasticizers on rheological properties of cement paste and mortars

    SciTech Connect

    Masood, I.; Agarwal, S.K. )

    1994-01-01

    The effect of eight commercial superplasticizers including one developed from Cashew Nut Shell Liquid (CNSL) at CBRI on the rheological properties viz. viscosity and flow of cement paste and mortars have been investigated. The viscosity measurements have been made at various shear rates (5--100 rpm). It is found that at higher rates (100 rpm) even with the low concentration of superplasticizers (0.1), the viscosity of the cement paste is more or less the same as that obtained with 0.6 % dosages of SPs at lesser shear rates. The effect of split addition (delayed addition) of superplasticizers on viscosity of cement paste and 1:3 cement sand mortar have also been studied. A decrease in viscosity due to split addition has been observed in the cement paste and there is an increase of 15--20 % in flow of mortars.

  3. Preparation and Characterization of New Geopolymer-Epoxy Resin Hybrid Mortars

    PubMed Central

    Colangelo, Francesco; Roviello, Giuseppina; Ricciotti, Laura; Ferone, Claudio; Cioffi, Raffaele

    2013-01-01

    The preparation and characterization of metakaolin-based geopolymer mortars containing an organic epoxy resin are presented here for the first time. The specimens have been prepared by means of an innovative in situ co-reticulation process, in mild conditions, of commercial epoxy based organic resins and geopolymeric slurry. In this way, geopolymer based hybrid mortars characterized by a different content of normalized sand (up to 66% in weight) and by a homogeneous dispersion of the organic resin have been obtained. Once hardened, these new materials show improved compressive strength and toughness in respect to both the neat geopolymer and the hybrid pastes since the organic polymer provides a more cohesive microstructure, with a reduced amount of microcracks. The microstructural characterization allows to point out the presence of an Interfacial Transition Zone similar to that observed in cement based mortars and concretes. A correlation between microstructural features and mechanical properties has been studied too. PMID:28811418

  4. Effect of Mineral Admixtures on Resistance to Sulfuric Acid Solution of Mortars with Quaternary Binders

    NASA Astrophysics Data System (ADS)

    Makhloufi, Zoubir; Bederina, Madani; Bouhicha, Mohamed; Kadri, El-Hadj

    This research consists to study the synergistic action of three mineral additions simultaneously added to the cement. This synergistic effect has a positive effect on the sustainability of limestone mortars. Tests were performed on mortars based on crushed limestone sand and manufactured by five quaternary binders (ordinary Portland cement and CPO mixed simultaneously with filler limestone, blast-furnace and natural pozzolan). The purpose of this research was to identify the resistance of five different mortars to the solution of sulfuric acid. Changes in weight loss and compressive strength measured at 30, 60, 90, 120 and 180 days for each acid solution were studied. We followed up on the change in pH of the sulfuric acid solution at the end of each month up to 180 days.

  5. Mechanical interaction between historical brick and repair mortar: experimental and numerical tests

    NASA Astrophysics Data System (ADS)

    Bocca, P.; Grazzini, A.; Masera, D.; Alberto, A.; Valente, S.

    2011-07-01

    An innovative laboratory procedure, developed at the Non Destructive Testing Laboratory of the Politecnico di Torino, as a preliminary design stage for the pre-qualification of repair mortars applied to historical masonry buildings is described. Tested repair mortars are suitable for new dehumidified plaster in order to stop the rising damp effects by capillary action on historical masonry walls. Long-term plaster delamination occurs frequently as a consequence of not compatible mechanical characteristics of mortar. Preventing this phenomenon is the main way to increase the durability of repair work. In this direction, it is useful to analyse, through the cohesive crack model, the evolutionary phenomenon of plaster delamination. The parameters used in the numerical simulation of experimental tests are able to characterize the mechanical behaviour of the interface. It is therefore possible to predict delamination in problems with different boundary conditions.

  6. Use of olive biomass fly ash in the preparation of environmentally friendly mortars.

    PubMed

    Cruz-Yusta, Manuel; Mármol, Isabel; Morales, Julián; Sánchez, Luis

    2011-08-15

    The incorporation of fly ash from olive biomass (FAOB) combustion in cogeneration plants into cement based mortars was explored by analyzing the chemical composition, mineralogical phases, particle size, morphology, and IR spectra of the resulting material. Pozzolanic activity was detected and found to be related with the presence of calcium aluminum silicates phases. The preparation of new olive biomass fly ash content mortars is effective by replacing either CaCO(3) filler or cement with FAOB. In fact, up to 10% of cement can be replaced without detracting from the mechanical properties of a mortar. This can provide an alternative way to manage the olive biomass fly ash as waste produced in thermal plants and reduce cement consumption in the building industry, and hence an economically and environmentally attractive choice.

  7. Mechanical properties of the rust layer induced by impressed current method in reinforced mortar

    SciTech Connect

    Care, S. Nguyen, Q.T.

    2008-08-15

    This paper describes the mechanical effects of rust layer formed in reinforced mortar through accelerated tests of corrosion. The morphological and physico-chemical properties (composition, structures) of the corrosion system were characterized at different stages by using optical microscope and scanning electron microscope coupled with energy dispersive spectroscopy. The corrosion pattern was mainly characterized by a rust layer confined at the interface between the steel and the mortar. Expansion coefficient of rust products was determined from the rust thickness and the Faraday's law. Furthermore, in order to understand the mechanical effects of corrosion on the damage of mortar, displacement field measurements were obtained by using digital image correlation. An analytical model (hollow cylinder subjected to inner and outer pressures) was used with a set of experimental data to deduce the time of cracking and the order of magnitude of the mechanical properties of the rust layer.

  8. Influence of curing temperature on cement hydration and mechanical strength development of fly ash mortars

    SciTech Connect

    Maltais, Y.; Marchand, J.

    1997-07-01

    The influence of fly ash and curing temperature on cement hydration and compressive strength development of mortars was investigated. Test parameters included type of fly ash (two different Class F fly ashes were tested), the level of cement replacement (10, 20 and 30% by mass), and curing temperature (20 C and 40 C). The mortar physical and microstructural properties were determined by means of thermal analyses, compressive strength measurements and SEM observations. Test results confirm that fly ash tends to increase significantly the rate of cement hydration at early age. Data also demonstrate that an elevation of the curing temperature reduces the long-term compressive strength of the reference mortar mixture. In contrast, an increase of the curing temperature seems to have no detrimental effect on the long-term compressive strength of the fly ash mixtures.

  9. Keratin film ablation for the fabrication of brick and mortar skin structure using femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Haq, Bibi Safia; Khan, Hidayat Ullah; Dou, Yuehua; Alam, Khan; Attaullah, Shehnaz; Zari, Islam

    2015-09-01

    The patterning of thin keratin films has been explored to manufacture model skin surfaces based on the "bricks and mortar" view of the relationship between keratin and lipids. It has been demonstrated that laser light is capable of preparing keratin-based "bricks and mortar" wall structure as in epidermis, the outermost layer of the human skin. "Bricks and mortar" pattern in keratin films has been fabricated using an ArF excimer laser (193 nm wavelength) and femtosecond laser (800 and 400 nm wavelength). Due to the very low ablation threshold of keratin, femtosecond laser systems are practical for laser processing of proteins. These model skin structures are fabricated for the first time that will help to produce potentially effective moisturizing products for the protection of skin from dryness, diseases and wrinkles.

  10. Formation of cement mortar with incineration municipal solid waste bottom ash

    NASA Astrophysics Data System (ADS)

    Jun, Ng Hooi; Abdullah, Mohd Mustafa Al Bakri; Hussin, Kamarudin; Jin, Tan Soo

    2017-04-01

    Product of incineration municipal solid waste bottom ash was substitute to Portland cement in construction industry. This study investigated the changes of bottom ash in Portland cement by chemical and mineralogical testing. Various substitution of bottom ash (10%, 20%, 30%, and 40%) to Portland cement was investigated. The main purpose was to clarify the mechanisms behind the formation of the cement mortar with bottom ash particles. The result indicated that the chemical and mineralogical of the cement mortar incorporating bottom ash was not significantly changed with the substitution of 10-40% bottom ash. However, the use of bottom ash minimizes the main composition of cement mortar. Overall, it was found that there is significant potential to increase the utilization of bottom ash.

  11. Properties of Mortars with Partial and Total Replacement of Conventional Aggregate by Waste Construction

    NASA Astrophysics Data System (ADS)

    Cerqueira, N. A.; Choe, D.; Alexandre, J.; Azevedo, A. R. G.; Xavier, C. G.; Souza, V. B.

    Environmental problems related to waste construction (RCC) permeate from the extraction of raw materials to its final disposal. The use of RCC in masses ceramics, concrete and mortar has been appointed as an important contribution. This work you assess the physical and mechanical properties of mortars with partial replacements (25% and 50%) of conventional aggregate for construction waste (RCC) come from a building of reinforced concrete structure and walls ceramic blocks. The mortars were tested to study their behavior fresh (consistency index and entrained air content) and solid (tensile strength in bending, compression strength and water absorption). The results approve of the use of the RCC, being limited to the grinding capacity of the same to a particle size that is interesting to the substitution of natural aggregates.

  12. Influence of bicarbonate ions on the deterioration of mortar bars in sulfate solutions

    SciTech Connect

    Kunther, W.; Lothenbach, B.; Scrivener, K.

    2013-02-15

    This work investigates the influence of bicarbonate ions on the deterioration of cementitious material exposed to sulfate ions. Mortars based on a CEM I and on a CEM III/B cement were investigated. Experimental investigations were compared to thermodynamic modeling and phase characterization to understand the differences in deterioration. The presence of bicarbonate ions significantly reduced the expansion of the CEM I mortars. Thermodynamic modeling showed that at high concentrations of bicarbonate ettringite and gypsum become unstable. Microstructural characterization combined with information from thermodynamic modeling suggests that conditions of high supersaturation with respect to ettringite are unlikely in the samples exposed in solutions containing bicarbonate. Consequently, expansive forces are not generated by the crystallization pressure of ettringite. There was little expansion of the CEM III/B sample even in the sodium sulfate solution. In the bicarbonate solution this mortar showed a highly leached zone at the surface in which calcite was observed.

  13. Performance Characteristics of Waste Glass Powder Substituting Portland Cement in Mortar Mixtures

    NASA Astrophysics Data System (ADS)

    Kara, P.; Csetényi, L. J.; Borosnyói, A.

    2016-04-01

    In the present work, soda-lime glass cullet (flint, amber, green) and special glass cullet (soda-alkaline earth-silicate glass coming from low pressure mercury-discharge lamp cullet and incandescent light bulb borosilicate glass waste cullet) were ground into fine powders in a laboratory planetary ball mill for 30 minutes. CEM I 42.5N Portland cement was applied in mortar mixtures, substituted with waste glass powder at levels of 20% and 30%. Characterisation and testing of waste glass powders included fineness by laser diffraction particle size analysis, specific surface area by nitrogen adsorption technique, particle density by pycnometry and chemical analysis by X-ray fluorescence spectrophotometry. Compressive strength, early age shrinkage cracking and drying shrinkage tests, heat of hydration of mortars, temperature of hydration, X-ray diffraction analysis and volume stability tests were performed to observe the influence of waste glass powder substitution for Portland cement on physical and engineering properties of mortar mixtures.

  14. Stability Analysis of a mortar cover ejected at various Mach numbers and angles of attack

    NASA Astrophysics Data System (ADS)

    Schwab, Jane; Carnasciali, Maria-Isabel; Andrejczyk, Joe; Kandis, Mike

    2011-11-01

    This study utilized CFD software to predict the aerodynamic coefficient of a wedge-shaped mortar cover which is ejected from a spacecraft upon deployment of its Parachute Recovery System (PRS). Concern over recontact or collision between the mortar cover and spacecraft served as the impetus for this study in which drag and moment coefficients were determined at Mach numbers from 0.3 to 1.6 at 30-degree increments. These CFD predictions were then used as inputs to a two-dimensional, multi-body, three-DoF trajectory model to calculate the relative motion of the mortar cover and spacecraft. Based upon those simulations, the study concluded a minimal/zero risk of collision with either the spacecraft or PRS. Sponsored by Pioneer Aerospace.

  15. Numerical Simulation of the Freeze-Thaw Behavior of Mortar Containing Deicing Salt Solution.

    PubMed

    Esmaeeli, Hadi S; Farnam, Yaghoob; Bentz, Dale P; Zavattieri, Pablo D; Weiss, Jason

    2017-02-01

    This paper presents a one-dimensional finite difference model that is developed to describe the freeze-thaw behavior of an air-entrained mortar containing deicing salt solution. A phenomenological model is used to predict the temperature and the heat flow for mortar specimens during cooling and heating. Phase transformations associated with the freezing/melting of water/ice or transition of the eutectic solution from liquid to solid are included in this phenomenological model. The lever rule is used to calculate the quantity of solution that undergoes the phase transformation, thereby simulating the energy released/absorbed during phase transformation. Undercooling and pore size effects are considered in the numerical model. To investigate the effect of pore size distribution, this distribution is considered using the Gibbs-Thomson equation in a saturated mortar specimen. For an air-entrained mortar, the impact of considering pore size (and curvature) on freezing was relatively insignificant; however the impact of pore size is much more significant during melting. The fluid inside pores smaller than 5 nm (i.e., gel pores) has a relatively small contribution in the macroscopic freeze-thaw behavior of mortar specimens within the temperature range used in this study (i.e., +24 °C to -35 °C), and can therefore be neglected for the macroscopic freeze-thaw simulations. A heat sink term is utilized to simulate the heat dissipation during phase transformations. Data from experiments performed using a low-temperature longitudinal guarded comparative calorimeter (LGCC) on mortar specimens fully saturated with various concentration NaCl solutions or partially saturated with water is compared to the numerical results and a promising agreement is generally obtained.

  16. Properties of Portland cement mortars incorporating high amounts of oil-fuel ashes

    SciTech Connect

    Paya, J.; Borrachero, M.V.; Monzo, J.; Bonilla, M.

    1999-06-01

    The residue of oil-fuel burned at the electrical power plant of Grao de Castellon (Spain) has been incorporated in Portland cement mortar and concrete. The used oil-fuel ash (OFA) had a high percentage of magnesium compounds because of magnesium oxide addition for removing slag and ashes from boilers and pipes. Several studies had been carried out on stabilization of toxic metals also occurring in oil-fuel ashes (particularly vanadium and nickel), by mixing with coal fly ashes and cement. In this case, the presence of magnesium compounds in the composition of the studied oil-fuel ashes could alter the mechanical and chemical properties of the cement matrix in fresh and hardened mortar and concrete. The authors present here the chemical, physical and mineralogical characterization of oil-fuel ashes and the behavior of Portland cement mortars incorporating high amounts of these oil-fuel ashes. The study includes workability, water demand, setting time, expansion and compressive strength developments. Preliminary results demonstrate a high absorption of water by oil-fuel ash particles, which promotes an increase in the water/cement ratio for a given workability. Acceleration of Portland cement/oil-fuel ash particles, which promotes an increase in the water/cement ratio for a given workability. Acceleration of Portland cement/oil-fuel ash pastes setting times was observed, due to the presence of carbonates. On the other hand, no significant expansion in specimens due to the presence of magnesium compounds was detected and, consequently, mechanical properties of hardened mortars containing oil-fuel ashes did not decrease with curing time. Compressive strengths for mortars containing OFA were much lower, however, than control mortar samples.

  17. Mortar and artillery variants classification by exploiting characteristics of the acoustic signature

    NASA Astrophysics Data System (ADS)

    Hohil, Myron E.; Grasing, David; Desai, Sachi; Morcos, Amir

    2007-10-01

    Feature extraction methods based on the discrete wavelet transform and multiresolution analysis facilitate the development of a robust classification algorithm that reliably discriminates mortar and artillery variants via acoustic signals produced during the launch/impact events. Utilizing acoustic sensors to exploit the sound waveform generated from the blast for the identification of mortar and artillery variants. Distinct characteristics arise within the different mortar variants because varying HE mortar payloads and related charges emphasize concussive and shrapnel effects upon impact employing varying magnitude explosions. The different mortar variants are characterized by variations in the resulting waveform of the event. The waveform holds various harmonic properties distinct to a given mortar/artillery variant that through advanced signal processing techniques can employed to classify a given set. The DWT and other readily available signal processing techniques will be used to extract the predominant components of these characteristics from the acoustic signatures at ranges exceeding 2km. Exploiting these techniques will help develop a feature set highly independent of range, providing discrimination based on acoustic elements of the blast wave. Highly reliable discrimination will be achieved with a feed-forward neural network classifier trained on a feature space derived from the distribution of wavelet coefficients, frequency spectrum, and higher frequency details found within different levels of the multiresolution decomposition. The process that will be described herein extends current technologies, which emphasis multi modal sensor fusion suites to provide such situational awareness. A two fold problem of energy consumption and line of sight arise with the multi modal sensor suites. The process described within will exploit the acoustic properties of the event to provide variant classification as added situational awareness to the solider.

  18. Ultrasonic nondestructive characterization of mortars by the width of the resonances

    NASA Astrophysics Data System (ADS)

    Bita, H.; Faiz, B.; Moudden, A.; Lotfi, H.; Ouacha, El H.

    2017-03-01

    In this work, we study the width of the resonances of the ultrasound waves reflection coefficient backscattered by a plane structure of the mortar. We establish the relationship between this width with two parameters which are widely used in non-destructive characterization of cementitious materials namely the velocity and attenuation. Monitoring the hydration of three solutions of mortars produced with different sizes of sand grains shows that the experimental results confirmed the theoretical predictions. Linear correlations are established between the width of resonance and the two ultrasonic parameters.

  19. Steelmaking slag as aggregate for mortars: effects of particle dimension on compression strength.

    PubMed

    Faraone, Nicola; Tonello, Gabriele; Furlani, Erika; Maschio, Stefano

    2009-11-01

    The present paper reports on the results of some experiments obtained from the production, hydration and subsequent measurement of the mechanical properties of several mortars prepared using a commercial CII/B-LL Portland cement, steelmaking slag, superplasticizer and water. Relevant parameters for the mortar preparation are the weight ratios of cement/water, the weight ratio superplasticizer/cement and between fine and granulated coarse particles. It has been demonstrated that optimisation of such parameters leads to the production of materials with mechanical properties suitable for civil engineering applications. Moreover, materials with improved compressive strength can be prepared by the use of slag containing extensive amounts of large particles.

  20. Study on the Carbonation Behavior of Cement Mortar by Electrochemical Impedance Spectroscopy

    PubMed Central

    Dong, Biqin; Qiu, Qiwen; Xiang, Jiaqi; Huang, Canjie; Xing, Feng; Han, Ningxu

    2014-01-01

    A new electrochemical model has been carefully established to explain the carbonation behavior of cement mortar, and the model has been validated by the experimental results. In fact, it is shown by this study that the electrochemical impedance behavior of mortars varies in the process of carbonation. With the cement/sand ratio reduced, the carbonation rate reveals more remarkable. The carbonation process can be quantitatively accessed by a parameter, which can be obtained by means of the electrochemical impedance spectroscopy (EIS)-based electrochemical model. It has been found that the parameter is a function of carbonation depth and of carbonation time. Thereby, prediction of carbonation depth can be achieved. PMID:28788452

  1. Study on the Carbonation Behavior of Cement Mortar by Electrochemical Impedance Spectroscopy.

    PubMed

    Dong, Biqin; Qiu, Qiwen; Xiang, Jiaqi; Huang, Canjie; Xing, Feng; Han, Ningxu

    2014-01-03

    A new electrochemical model has been carefully established to explain the carbonation behavior of cement mortar, and the model has been validated by the experimental results. In fact, it is shown by this study that the electrochemical impedance behavior of mortars varies in the process of carbonation. With the cement/sand ratio reduced, the carbonation rate reveals more remarkable. The carbonation process can be quantitatively accessed by a parameter, which can be obtained by means of the electrochemical impedance spectroscopy (EIS)-based electrochemical model. It has been found that the parameter is a function of carbonation depth and of carbonation time. Thereby, prediction of carbonation depth can be achieved.

  2. Finite Element Analysis of Crack-Path Selection in a Brick and Mortar Structure

    NASA Astrophysics Data System (ADS)

    Sarrafi-Nour, Reza; Manoharan, Mohan; Johnson, Curtis A.

    Many natural composite materials rely on organized architectures that span several length scales. The structures of natural shells such as nacre (mother-of-pearl) and conch are prominent examples of such organizations where the calcium carbonate platelets, the main constituent of natural shells, are held together in an organized fashion within an organic matrix. At one or multiple length scales, these organized arrangements often resemble a brick-and-mortar structure, with calcium carbonate platelets acting as bricks connected through the organic mortar phase.

  3. Use of glazed ceramic waste as additive in mortar and the mathematical modelling of its strength.

    PubMed

    Altin, Zehra Gulten; Erturan, Seyfettin; Tepecik, Abdulkadir

    2008-04-01

    This study investigated the reusability of waste material from the tile manufacturing industry as an alternative material to natural pozzolan trass. Yield strength values of mortar made from Portland cement (CEM 142.5), were measured by adding glazed ceramic waste and trass at various weight ratios (5 to 40%). The test results proved that the strength values at 2, 7, and 28 days gave good results for concentrations of waste materials less than 5-10% in the cement. A decrease in strength was observed at higher concentrations. Mathematical modelling results showed a logarithmic correlation between the mortar strength and weight fraction of cement.

  4. Use of sewage sludge ash (SSA)-cement admixtures in mortars

    SciTech Connect

    Monzo, J.; Paya, J.; Borrachero, M.V.; Corcoles, A.

    1996-09-01

    The chemical composition of sewage sludge ash (SSA) and their sized fractions are studied; some differences in chemical composition are observed. SEM studies show irregular shape of SSA particles and sized fractions, this shape has a decisive influence on workability of mortars. The effect of replacing 15% of portland cement by SSA and their sized fractions: coarse (SSAC) and medium (SSAM) obtained by sieving on compressive (R{sub c}) and flexural (R{sub f}) strength of mortars was investigated. The study reveals an enhancement of strength when ashes are used, due to probably, pozzolanic properties of SSA.

  5. Effect of the Paper Industry Residue on Properties in the Fresh Mortar

    NASA Astrophysics Data System (ADS)

    Azevedo, A. R. G.; Alexandre, J.; Vieira, C. M. F.; Xavier, C. G.; Zanelato, E. B.; Oliveira, L. I. V.

    The problem of solid was te gene rati on not only restricts construction, the industrial sector in general is a major contributor in this regard. Sol id waste can be of domestic or industrial origin, hence arises a major problem, which are the quantitative generated. The objective of this study is the evaluation and characterization of the incorporation of waste from paper industry in mortars at different levels (0% 5%, 10%, 15% , 20%, 25% and 30%), according properties in the fresh state as consistency index, entrained air content and water retention. It can be said that levels from 20% incorporation in lime, mortar produce very workability.

  6. Enhanced affordable methods for assessment of material characteristics and consolidation effects on stone and mortar

    NASA Astrophysics Data System (ADS)

    Drdacky, M.; Slizkova, Z.

    2012-04-01

    In situ considerate testing of surface cohesion of historic stone and mortar materials suffers from a lack of suitable affordable non-destructive methods. The problem is mainly important for assessment of surface degradation characteristics and/or evaluation of effectiveness of consolidation treatment of degraded historic materials. The paper presents two innovations of simple testing methods which provide reliable data on material cohesion and water uptake. The so called "Scotch Tape Test" or peeling test has been introduced into the field of conservation for testing the cohesion qualities of historic materials mainly stone and renders in sixties without any standards or reliably verified recommendations for the above mentioned application in the conservation practice. Licentious use without adequate knowledge and sufficient understanding leads to non-comparable and non-reproducible as well as in many cases incorrect and severely biased results and assessments. Therefore, the authors after a research and comparative testing have established limits for its application, reliable procedures and a "standard" protocol for testing of cohesion characteristics of brittle and quasi brittle materials mainly mortars and stones. This article presents a detailed analysis of the peeling test procedures, and suggests recommendations for performing peeling tests and for evaluating the obtained results. Also in situ testing of material water uptake is a very basic and indispensable technique in conservation practice and it correlates significantly with some other material characteristics. The capillary properties of porous materials can be measured in situ using a Karsten tube and modified tools or methods which are quite cumbersome, and cannot be performed on inclined surfaces, e.g. vaults or ceilings. There are other difficulties with Karsten tube measurements, e.g. problems with fixing a heavy glass tube on vertical surfaces, a need for two operators, and soiling of the surface

  7. Adhesion of Dental Materials to Tooth Structure

    NASA Astrophysics Data System (ADS)

    Mitra, Sumita B.

    2000-03-01

    The understanding and proper application of the principles of adhesion has brought forth a new paradigm in the realm of esthetic dentistry. Modern restorative tooth procedures can now conserve the remaining tooth-structure and also provide for the strengthening of the tooth. Adhesive restorative techniques call for the application and curing of the dental adhesive at the interface between the tooth tissue and the filling material. Hence the success of the restoration depends largely on the integrity of this interface. The mechanism of adhesion of the bonding materials to the dental hard tissue will be discussed in this paper. There are four main steps that occur during the application of the dental adhesive to the oral hard tissues: 1) The first step is the creation of a microstructure in the tooth enamel or dentin by means of an acidic material. This can be through the application of a separate etchant or can be accomplished in situ by the adhesive/primer. This agent has to be effective in removing or modifying the proteinaceous “smear” layer, which would otherwise act as a weak boundary layer on the surface to be bonded. 2) The primer/adhesive must then be able to wet and penetrate the microstructure created in the tooth. Since the surface energies of etched enamel and that of etched dentin are different finding one material to prime both types of dental tissues can be quite challenging. 3) The ionomer types of materials, particularly those that are carboxylate ion-containing, can chemically bond with the calcium ions of the hydroxyapatite mineral. 4) Polymerization in situ allows for micromechanical interlocking of the adhesive. The importance of having the right mechanical properties of the cured adhesive layer and its role in absorbing and dissipating stresses encountered by a restored tooth will also be discussed.

  8. Adaptation and radiographic evaluation of four adhesive systems.

    PubMed

    Opdam, N J; Roeters, F J; Verdonschot, E H

    1997-09-01

    The purpose of this study was to compare microleakage, gap formation, thickness of the adhesive layer and its radiographic appearance associated with four adhesive restorative procedures for class I cavities. Adhesive systems with easy handling characteristics were selected for the restoration of class I cavities in extracted third molars. Bitewing radiographs were taken of each tooth and four observers were asked to assess the presence of the adhesive layer. Microleakage, gap width and the thickness of the adhesive layer of each restoration were measured upon sectioning of the teeth. Microleakage in the experimental restorations was minimal. The thickness of the adhesive layers and gap formation varied among different adhesive systems. The adhesive system with self-etching primer produced the highest percentage gap-free restorations. Thick adhesive layers could be detected on the radiograph. ROC analysis of the results validates the diagnosis from the radiograph. The four restorative systems performed well in the prevention of microleakage. The use of a resin modified glass-ionomer cement base did not prevent gap formation compared with the all-etch bonding systems used in this study. The presence of an adhesive layer contributed to the prevention of gap formation, independently of the bonding system used. Thick adhesive layers could be detected on the radiograph.

  9. Addition polyimide adhesives containing ATBN and silicone elastomers

    NASA Technical Reports Server (NTRS)

    Saint Clair, A. K.; Saint Clair, T. L.

    1981-01-01

    A study was conducted to determine the effects of added elastomers on the thermal stability, adhesive strength, and fracture toughness of LARC-13, a high-temperature addition polyimide adhesive. Various butadiene/acrylonitrile and silicon elastomers were incorporated into the polyimide resin either as physical polyblends, or by chemically reacting the elastomers with the polyimide backbone. Adhesive single lap-shear and T-peel strengths were measured before and after ageing at elevated temperature. A tapered double-cantilever beam specimen was used to determine the fracture toughness of the elastomer-modified polyimide adhesives.

  10. Addition polyimide adhesives containing ATBN and silicone elastomers

    NASA Technical Reports Server (NTRS)

    Saint Clair, A. K.; Saint Clair, T. L.

    1981-01-01

    A study was conducted to determine the effects of added elastomers on the thermal stability, adhesive strength, and fracture toughness of LARC-13, a high-temperature addition polyimide adhesive. Various butadiene/acrylonitrile and silicon elastomers were incorporated into the polyimide resin either as physical polyblends, or by chemically reacting the elastomers with the polyimide backbone. Adhesive single lap-shear and T-peel strengths were measured before and after ageing at elevated temperature. A tapered double-cantilever beam specimen was used to determine the fracture toughness of the elastomer-modified polyimide adhesives.

  11. Poly(acrylic acid) grafted montmorillonite as novel fillers for dental adhesives: synthesis, characterization and properties of the adhesive.

    PubMed

    Solhi, Laleh; Atai, Mohammad; Nodehi, Azizollah; Imani, Mohammad; Ghaemi, Azadeh; Khosravi, Kazem

    2012-04-01

    This work investigates the graft polymerization of acrylic acid onto nanoclay platelets to be utilized as reinforcing fillers in an experimental dental adhesive. Physical and mechanical properties of the adhesive and its shear bond strength to dentin are studied. The effect of the modification on the stability of the nanoparticle dispersion in the dilute adhesive is also investigated. Poly(acrylic acid) (PAA) was grafted onto the pristine Na-MMT nanoclay (Cloisite(®) Na(+)) through the free radical polymerization of acylic acid in an aqueous media. The resulting PAA-g-nanoclay was characterized using FTIR, TGA and X-ray diffraction (XRD). The modified nanoclays were added to an experimental dental adhesive in different concentrations and the morphology of the nanoclay layers in the photocured adhesive matrix was studied using TEM and XRD. Shear bond strength of the adhesives containing different filler contents was tested on the human premolar teeth. The stability of nanoclay dispersion in the dilute adhesive was also studied using a separation analyzer. The results were then statistically analyzed and compared. The results confirmed the grafting reaction and revealed a partially exfoliated structure for the PAA-g-nanoclay. Incorporation of 0.2 wt.% of the modified nanoclay into the experimental adhesive provided higher shear bond strength. The dispersion stability of the modified nanoparticles in the dilute adhesive was also enhanced more than 25 times. Incorporation of the modified particles as reinforcing fillers into the adhesive resulted in higher mechanical properties. The nanofiller containing bonding agent also showed higher shear bond strength due to the probable interaction of the carboxylic acid functional groups on the surface of the modified particles with hydroxyapatite of dentin. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  12. Evaluation of adhesive penetration of wood fibre by nanoindentation and microscopy

    Treesearch

    Christopher G. Hunt; Joseph E. Jakes; Warren Grigsby

    2010-01-01

    Adhesives used in wood products sometimes infiltrate, or diffuse into the solid material of, wood cell walls, potentially modifying their properties. These changes in cell wall properties are likely to impact the performance of adhesive bonds. While adhesive infiltration has been observed by multiple methods, the effect on cell wall properties is not well understood....

  13. Application of honeymoon cold-set adhesive systems for structural end joints in North America

    Treesearch

    Roland E. Kreibich; Richard W. Hemingway; William T. Nearn

    1993-01-01

    High quality, structural end joints can be cold-set at mill speed using a two-component honeymoon adhesive system composed of southern pine bark or pecan shell membrane tannin and a modified, commercially available. phenol-resorcinol-formaldehyde resin. Adhesive costs of a fully waterproof glueline are approximately $0.60/lb. of applied adhesive mix compared to $0.80/...

  14. Single-Phase Photo-Cross-Linkable Bioinspired Adhesive for Precise Control of Adhesion Strength.

    PubMed

    Harper, Tristan; Slegeris, Rimantas; Pramudya, Irawan; Chung, Hoyong

    2017-01-18

    obtained from a 1:1 weight ratio of polymer:solvent in water on a Mylar film surface. As a single-phase system, the synthesized terpolymer is very convenient to use, and its adhesion strength can be easily modified by UV light. Additionally, the terpolymer's high water compatibility makes it ideally suited for application in the biomedical field.

  15. The adhesive strength and initial viscosity of denture adhesives.

    PubMed

    Han, Jian-Min; Hong, Guang; Dilinuer, Maimaitishawuti; Lin, Hong; Zheng, Gang; Wang, Xin-Zhi; Sasaki, Keiichi

    2014-11-01

    To examine the initial viscosity and adhesive strength of modern denture adhesives in vitro. Three cream-type denture adhesives (Poligrip S, Corect Cream, Liodent Cream; PGS, CRC, LDC) and three powder-type denture adhesives (Poligrip Powder, New Faston, Zanfton; PGP, FSN, ZFN) were used in this study. The initial viscosity was measured using a controlled-stress rheometer. The adhesive strength was measured according to ISO-10873 recommended procedures. All data were analyzed independently by one-way analysis of variance combined with a Student-Newman-Keuls multiple comparison test at a 5% level of significance. The initial viscosity of all the cream-type denture adhesives was lower than the powder-type adhesives. Before immersion in water, all the powder-type adhesives exhibited higher adhesive strength than the cream-type adhesives. However, the adhesive strength of cream-type denture adhesives increased significantly and exceeded the powder-type denture adhesives after immersion in water. For powder-type adhesives, the adhesive strength significantly decreased after immersion in water for 60 min, while the adhesive strength of the cream-type adhesives significantly decreased after immersion in water for 180 min. Cream-type denture adhesives have lower initial viscosity and higher adhesive strength than powder type adhesives, which may offer better manipulation properties and greater efficacy during application.

  16. Improved Osteoblast and Chondrocyte Adhesion and Viability by Surface-Modified Ti6Al4V Alloy with Anodized TiO2 Nanotubes Using a Super-Oxidative Solution

    PubMed Central

    Beltrán-Partida, Ernesto; Moreno-Ulloa, Aldo; Valdez-Salas, Benjamín; Velasquillo, Cristina; Carrillo, Monica; Escamilla, Alan; Valdez, Ernesto; Villarreal, Francisco

    2015-01-01

    Titanium (Ti) and its alloys are amongst the most commonly-used biomaterials in orthopedic and dental applications. The Ti-aluminum-vanadium alloy (Ti6Al4V) is widely used as a biomaterial for these applications by virtue of its favorable properties, such as high tensile strength, good biocompatibility and excellent corrosion resistance. TiO2 nanotube (NTs) layers formed by anodization on Ti6Al4V alloy have been shown to improve osteoblast adhesion and function when compared to non-anodized material. In his study, NTs were grown on a Ti6Al4V alloy by anodic oxidation for 5 min using a super-oxidative aqueous solution, and their in vitro biocompatibility was investigated in pig periosteal osteoblasts and cartilage chondrocytes. Scanning electron microscopy (SEM), energy dispersion X-ray analysis (EDX) and atomic force microscopy (AFM) were used to characterize the materials. Cell morphology was analyzed by SEM and AFM. Cell viability was examined by fluorescence microscopy. Cell adhesion was evaluated by nuclei staining and cell number quantification by fluorescence microscopy. The average diameter of the NTs was 80 nm. The results demonstrate improved cell adhesion and viability at Day 1 and Day 3 of cell growth on the nanostructured material as compared to the non-anodized alloy. In conclusion, this study evidences the suitability of NTs grown on Ti6Al4V alloy using a super-oxidative water and a short anodization process to enhance the adhesion and viability of osteoblasts and chondrocytes. The results warrant further investigation for its use as medical implant materials. PMID:28787976

  17. Improved Osteoblast and Chondrocyte Adhesion and Viability by Surface-Modified Ti6Al4V Alloy with Anodized TiO₂ Nanotubes Using a Super-Oxidative Solution.

    PubMed

    Beltrán-Partida, Ernesto; Moreno-Ulloa, Aldo; Valdez-Salas, Benjamín; Velasquillo, Cristina; Carrillo, Monica; Escamilla, Alan; Valdez, Ernesto; Villarreal, Francisco

    2015-03-02

    Titanium (Ti) and its alloys are amongst the most commonly-used biomaterials in orthopedic and dental applications. The Ti-aluminum-vanadium alloy (Ti6Al4V) is widely used as a biomaterial for these applications by virtue of its favorable properties, such as high tensile strength, good biocompatibility and excellent corrosion resistance. TiO₂ nanotube (NTs) layers formed by anodization on Ti6Al4V alloy have been shown to improve osteoblast adhesion and function when compared to non-anodized material. In his study, NTs were grown on a Ti6Al4V alloy by anodic oxidation for 5 min using a super-oxidative aqueous solution, and their in vitro biocompatibility was investigated in pig periosteal osteoblasts and cartilage chondrocytes. Scanning electron microscopy (SEM), energy dispersion X-ray analysis (EDX) and atomic force microscopy (AFM) were used to characterize the materials. Cell morphology was analyzed by SEM and AFM. Cell viability was examined by fluorescence microscopy. Cell adhesion was evaluated by nuclei staining and cell number quantification by fluorescence microscopy. The average diameter of the NTs was 80 nm. The results demonstrate improved cell adhesion and viability at Day 1 and Day 3 of cell growth on the nanostructured material as compared to the non-anodized alloy. In conclusion, this study evidences the suitability of NTs grown on Ti6Al4V alloy using a super-oxidative water and a short anodization process to enhance the adhesion and viability of osteoblasts and chondrocytes. The results warrant further investigation for its use as medical implant materials.

  18. Desmosomal adhesion in vivo.

    PubMed

    Berika, Mohamed; Garrod, David

    2014-02-01

    Desmosomes are intercellular junctions that provide strong adhesion or hyper-adhesion in tissues. Here, we discuss the molecular and structural basis of this with particular reference to the desmosomal cadherins (DCs), their isoforms and evolution. We also assess the role of DCs as regulators of epithelial differentiation. New data on the role of desmosomes in development and human disease, especially wound healing and pemphigus, are briefly discussed, and the importance of regulation of the adhesiveness of desmosomes in tissue dynamics is considered.

  19. The effects of different types of nano-silicon dioxide additives on the properties of sludge ash mortar.

    PubMed

    Luo, Huan-Lin; Chang, Wei-Che; Lin, Deng-Fong

    2009-04-01

    To improve the drawbacks caused by the sludge ash replacement in mortar, the previous studies have shown that the early strength and durability of sludge ash/cement mortar are improved by adding nano-silicon dioxide (nano-SiO2) to mortar. In this article, three types of nano-SiO2--SS, HS, and SP (manufacturer code names)--were applied to sludge ash/cement mixture to make paste or mortar specimens. The object is to further extend the recycle of the sludge ash by determining the better type of nano-SiO2 additive to improve properties of sludge ash/ cement paste or mortar. The cement was replaced by 0, 10, 20, and 30% of sludge ash, and 0 and 2% of nano-SiO2 additives were added to the sludge ash paste or mortar specimens. Tests such as setting time, compressive strength, scanning electron microscopy, X-ray diffraction, nuclear magnetic resonance, and thermogravimetric analysis/differential thermal analysis were performed in this study. Test results show that nano-SiO2 additives can not only effectively increase the hydration product (calcium silicate hydrate [C-S-H] gel), but also make the crystal structure denser. Among the three types of nano-SiO2 additive, the SS type can best improve the properties of sludge ash/cement paste or mortar, followed by the SP and HS types.

  20. Experimental Study of the Possibility to Make a Mortar with Ternary Sand (Natural and Artificial Fine Aggregates)

    NASA Astrophysics Data System (ADS)

    Baali, L.; Naceri, A.; Rahmouni, Z.; Mehidi, M. W. Noui

    This experimental study investigates the possibility to make a mortar with a ternary sand (natural and artificial fine aggregates). This method is utilized to correct the particle size distribution of various sands used in mortar. For this investigation, three sands have been used: a dune sand (DS), a slag sand (SS), and brick sand (BS) at different proportions in mortar. After crushing, the artificial fine aggregate (blast furnace slag and waste brick fine aggregate) was sifted in order to use it as fine aggregate. The effect of the quality and grain size distribution of natural fine aggregate (i.e., DS) and artificial fine aggregates (i.e., SS and BS) on the physical properties of ternary sand confected (density, porosity, fineness modulus, equivalent sand, particle size distribution, water absorption) and properties of fresh and hardened mortar were analysed. In the same way for this study, the physical properties and chemical compositions of DS, SS, BS and cement were investigated. The results obtained show that the mechanical strength on mortar depends of the nature and particle size distribution of sand studied. The reuse of this recycled material (slag blast furnace and waste brick) in the industry would contribute to the protection of the environment. This study shows the potential of this method to make mortar with ternary sand (natural and artificial fine aggreagates) in order to improve the physical properties of sand. Utilising natural and artificial fine aggregates to produce quality mortar should yield significant environmental benefits.

  1. Cytotoxicity of Dental Adhesives In Vitro

    PubMed Central

    Koulaouzidou, Elisabeth A.; Helvatjoglu-Antoniades, Maria; Palaghias, George; Karanika-Kouma, Artemis; Antoniades, Dimitrios

    2009-01-01

    Objectives The purpose of this study was to evaluate the cytotoxic effect of six dental adhesives (Admira Bond, Clearfil Liner Bond 2V, ED Primer II, Fuji Bond LC, Gluma Comfort Bond, and NanoBond) applied to cell cultures. Methods The experiments were performed on two cell lines, rat pulp cells (RPC-C2A) and human lung fibroblasts (MRC5). Samples of the adhesives were light-cured and placed in culture medium for 24 hours. The extraction media was applied on the RPC-C2A and the MRC5 cells. Complete medium was used as a control. Cytotoxicity was evaluated with a modified sulforhodamine B (SRB) assay after 24 hours of exposure. Results The cell survival of RPC-C2A cells exposed to Fuji Bond LC, NanoBond, Clearfil Liner Bond 2V, ED Primer II, Admira Bond and Gluma Comfort Bond was 73%, 67%, 50%, 20%, 18% and 5% respectively, relative to the cell survival with the control medium. In the MRC5 cell line, the relative survival was 98%, 80%, 72%, 41%, 19% and 7% after exposure to NanoBond, Fuji Bond LC, Clearfil Liner Bond 2V, ED Primer II, Admira Bond and Gluma Comfort Bond, respectively. Conclusions Different types of dental adhesives showed different cytotoxic effects on cells in vitro. The self-etch adhesives were superior in terms of cytotoxicity. The different cytotoxic effects of dental adhesives should be considered when selecting an appropriate adhesive for operative restorations. PMID:19262725

  2. Adhesives, silver amalgam.

    PubMed

    1995-09-01

    The most recent advancement in silver amalgam is use of resin formulations to bond metal to tooth both chemically &/or physically, Since, historically, amalgam has been used successfully without adhesion to tooth, obvious clinical question is: Why is bonding now desirable? Two major clinical reasons to bond are: (1) Adhesive can increase fracture resistance of amalgam restored teeth & decrease cusp fractures; & (2) Seal provided by adhesive can greatly decrease, & often eliminate post-operative sensitivity. Following report summarizes CRA laboratory study of shear bond strength & sealing capability of 23 commercial adhesives used to bond 2 types of silver amalgam to tooth structure.

  3. Reversible Thermoset Adhesives

    NASA Technical Reports Server (NTRS)

    Mac Murray, Benjamin C. (Inventor); Tong, Tat H. (Inventor); Hreha, Richard D. (Inventor)

    2016-01-01

    Embodiments of a reversible thermoset adhesive formed by incorporating thermally-reversible cross-linking units and a method for making the reversible thermoset adhesive are provided. One approach to formulating reversible thermoset adhesives includes incorporating dienes, such as furans, and dienophiles, such as maleimides, into a polymer network as reversible covalent cross-links using Diels Alder cross-link formation between the diene and dienophile. The chemical components may be selected based on their compatibility with adhesive chemistry as well as their ability to undergo controlled, reversible cross-linking chemistry.

  4. Adhesion at metal interfaces

    NASA Technical Reports Server (NTRS)

    Banerjea, Amitava; Ferrante, John; Smith, John R.

    1991-01-01

    A basic adhesion process is defined, the theory of the properties influencing metallic adhesion is outlined, and theoretical approaches to the interface problem are presented, with emphasis on first-principle calculations as well as jellium-model calculations. The computation of the energies of adhesion as a function of the interfacial separation is performed; fully three-dimensional calculations are presented, and universality in the shapes of the binding energy curves is considered. An embedded-atom method and equivalent-crystal theory are covered in the framework of issues involved in practical adhesion.

  5. Elastic-plastic analysis of crack in ductile adhesive joint

    SciTech Connect

    Ikeda, Toru; Miyazaki, Noriyuki; Yamashita, Akira; Munakata, Tsuyoshi

    1995-11-01

    The fracture of a crack in adhesive is important to the structural integrity of adhesive structures and composite materials. Though the fracture toughness of a material should be constant according to fracture mechanics, it is said that the fracture toughness of a crack in an adhesive joint depends on the bond thickness. In the present study, the elastic-plastic stress analyses of a crack in a thin adhesive layer are performed by the combination of the boundary element method and the finite element method. The effect of adhesive thickness on the J-integral, the Q`-factor which is a modified version of the Q-factor, and the crack tip opening displacement (CTOD) are investigated. It is found from the analyses that the CTOD begins to decrease at very thin bond thickness, the Q`-factor being almost constant. The decrease of the fracture toughness at very thin adhesive layer is expected by the present analysis.

  6. Intrinsic adhesion force of lubricants to steel surface.

    PubMed

    Lee, Jonghwi

    2004-09-01

    The intrinsic adhesion forces of lubricants and other pharmaceutical materials to a steel surface were quantitatively compared using Atomic Force Microscopy (AFM). A steel sphere was attached to the tip of an AFM cantilever, and its adhesion forces to the substrate surfaces of magnesium stearate, sodium stearyl fumarate, lactose, 4-acetamidophenol, and naproxen were measured. Surface roughness varied by an order of magnitude among the materials. However, the results clearly showed that the two lubricants had about half the intrinsic adhesion force as lactose, 4-acetamidophenol, and naproxen. Differences in the intrinsic adhesion forces of the two lubricants were insignificant. The lubricant molecules were unable to cover the steel surface during AFM measurements. Intrinsic adhesion force can slightly be modified by surface treatment and compaction, and its tip-to-tip variation was not greater than its difference between lubricants and other pharmaceutical particles. This study provides a quantitative fundamental basis for understanding adhesion related issues.

  7. Removal of graffiti from the mortar by using Q-switched Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Sanjeevan, Poologanathan; Klemm, Agnieszka J.; Klemm, Piotr

    2007-08-01

    This paper presents part of the larger study on microstructural features of mortars and it's effects on laser cleaning process. It focuses on the influence of surface roughness, porosity and moisture content of mortars on the removal of graffiti by Nd:YAG laser. The properties of this laser are as follows: wavelength ( λ) 1.06 μm, energy: 500 mJ per pulse, pulse duration: 10 ns. The investigation shows that the variation of laser fluence with the number of pulses required for the laser cleaning can be divided into two zones, namely effective zone and ineffective zone. There is a linear relationship observed between number of pulses required for laser cleaning and the laser fluence in the effective zone, while the number of pulses required for the laser cleaning is almost constant even though the laser fluence increases in the ineffective zone. Moreover, surface roughness, porosity and moisture content of mortar samples have influence on the laser cleaning process. The effect of these parameters become however negligible at the high level of laser fluence. The number of pulses required for the laser cleaning is low for smooth surface or less porous mortar. Furthermore, the wetness of the samples facilitates the cleaning process.

  8. Application of AMDS mortar as a treatment agent for arsenic in subsurface environment

    NASA Astrophysics Data System (ADS)

    Choi, J.; Lee, H.; Choi, U. K.; Yang, I. J.

    2014-12-01

    Among the treatment technologies available for As in soil and groundwater, adsorption or precipitation using acid mine drainage (AMD) sludge has become a promised technique because of high efficiency, inexpensiveness and simple to handling. The adsorbents were prepared by addition of Cement, Joomoonjin sand, fly ash, and Ca(OH)2 to air dry AMD sludge. In this work, the adsorption of As (III) and As (V) on AMDS mortar has been studied as a function of kinetic, pH, and initial arsenic concentration. Results of batch study showed that 75-90% of both As (III) and As (V) were removed at pH 7. Arsenic adsorption capacities were the highest at neutral pH condition and the adsorption equilibrium time reached in 7 days using AMDS mortar. Additionally, the adsorption kinetic process is expressed well by pseudo-second-order model. The adsorption capacities of AMDS mortar for As(III) and As(V) were found 19.04 and 30.75 mg g-1, respectively. The results of As (III) adsorption isotherms were fitted well to the Freundlich model. Moreover, As (V) adsorption isotherms were fitted well to the Langmuir model rather than Freundlich model. Based on experimental results in this study, we could conclude that AMDS mortar can be effectively used for arsenic removal agent from subsurface environment.

  9. Advanced mortar coatings for cultural heritage protection. Durability towards prolonged UV and outdoor exposure.

    PubMed

    Pino, F; Fermo, P; La Russa, M; Ruffolo, S; Comite, V; Baghdachi, J; Pecchioni, E; Fratini, F; Cappelletti, G

    2016-10-01

    In the present work, two kinds of hybrid polymeric-inorganic coatings containing TiO2 or SiO2 particles and prepared starting from two commercial resins (Alpha®SI30 and Bluesil®BP9710) were developed and applied to two kinds of mortars (an air-hardening calcic lime mortar [ALM] and a natural hydraulic lime mortar [HLM]) to achieve better performances in terms of water repellence and consequently damage resistance. The two pure commercial resins were also applied for comparison purposes. Properties of the coated materials and their performance were studied using different techniques such as contact angle measurements, capillary absorption test, mercury intrusion porosimetry, surface free energy, colorimetric measurements and water vapour permeability tests. Tests were also performed to determine the weathering effects on both the commercial and the hybrid coatings in order to study their durability. Thus, exposures to UV radiation, to UV radiation/condensed water cycles and to a real polluted atmospheric environment have been performed. The effectiveness of the hybrid SiO2 based coating was demonstrated, especially in the case of the HLM mortar.

  10. On the role of hydrophobic Si-based protective coatings in limiting mortar deterioration.

    PubMed

    Cappelletti, G; Fermo, P; Pino, F; Pargoletti, E; Pecchioni, E; Fratini, F; Ruffolo, S A; La Russa, M F

    2015-11-01

    In order to avoid both natural and artificial stone decay, mainly due to the interaction with atmospheric pollutants (both gases such as NOx and SO2 and particulate matter), polymeric materials have been widely studied as protective coatings enable to limit the penetration of fluids into the bulk material. In the current work, an air hardening calcic lime mortar (ALM) and a natural hydraulic lime mortar (HLM) were used as substrates, and commercially available Si-based resins (Alpha®SI30 and Silres®BS16) were adopted as protective agents to give hydrophobicity features to the artificial stones. Surface properties of coatings and their performance as hydrophobic agents were studied using different techniques such as contact angle measurements, capillary absorption test, mercury intrusion porosimetry, surface free energy, colorimetric measurements and water vapour permeability tests. Finally, some exposure tests to UV radiation and to real polluted atmospheric environments (a city centre and an urban background site) were carried out during a wintertime period (when the concentrations of the main atmospheric pollutants are higher) in order to study the durability of the coating systems applied. The effectiveness of the two commercial resins in reducing salt formation (sulphate and nitrate), induced by the interaction of the mortars with the atmospheric pollutants, was demonstrated in the case of the HLM mortar. Graphical Abstract ᅟ.

  11. Submicroscopic Deformation in Cement Paste and Mortar at High Load Rates

    DTIC Science & Technology

    1988-08-15

    Composites: Strain Rate Effects on Fracture, S. Mindess and S. P. Shah, Eds., Materials Research Society Symposia Proceedings, Vol. 64, 1986, pp. 167-180. 3...Strength, and the Compressive Strength of Mortar," Bonding in Cementitious Composites, S. Mindess and S. P. Shah, Eds., Materials Research Society

  12. Experimental study of the mechanical stabilization of electric arc furnace dust using fluid cement mortars.

    PubMed

    Ledesma, E F; Jiménez, J R; Ayuso, J; Fernández, J M; Brito, J de

    2017-03-15

    This article shows the results of an experimental study carried out in order to determine the maximum amount of electric arc furnace dust (EAFD) that can be incorporated into fluid cement-based mortars to produce mechanically stable monolithic blocks. The leaching performance of all mixes was studied in order to classify them according to the EU Council Decision 2003/33/EC. Two mortars were used as reference and three levels of EAFD incorporation were tested in each of the reference mortars. As the incorporation ratio of EAFD/cement increases, the mechanical strength decreases. This is due to the greater EAFD/cement and water/cement ratios, besides the presence of a double-hydrated hydroxide of Ca and Zn (CaZn2(OH)6·2H2O) instead of the portlandite phase (Ca(OH)2) in the mixes made with EAFD, as well as non-hydrated tricalcium silicate. A mass ratio of 2:1 (EAFD: cement-based mortar) can be added maintaining a stable mechanical strength. The mechanical stabilization process also reduced the leaching of metals, although it was not able to reduce the Pb concentration below the limit for hazardous waste. The high amount of EAFD mechanically stabilized in this experimental study can be useful to reduce the storage volume required in hazardous waste landfills.

  13. Is There a requirement for Heavy Mortars in Airland Battle Future (ALB- F)

    DTIC Science & Technology

    1990-03-09

    ineffective the heavy mortars are in a fast -moving battle fought at the NTC, if they managed to get into the fight at all. Reports indicate that the heavy...Army Operational Concept," Final Draft, U.S. Army Combined Arms Center, Fort Leavenworth, KS. 10 January 1989. Forword . 2. Ibid. pp. D1-D3. 3. Ibid

  14. Tactical Means to Stow Super-Caliber Tailfins of a Developmental Flight-Controlled Mortar

    DTIC Science & Technology

    2011-08-01

    Developmental Flight- Controlled Mortar CHRISTIAN A VALLEDOR MENTOR: JOHN CONDON GUIDANCE TECHNOLOGIES BRANCH, LETHALITY DIVISION WEAPONS AND MATERIALS...Materials Research Directorate,Guidance Technologies Branch, Lethality Division ,Aberdeen Proving Ground,MD,21005 8. PERFORMING ORGANIZATION REPORT NUMBER... photosensitive polymer using a stereolithography 3-D printing process. This process resulted in highly accurate prototypes with physical properties close to

  15. Characterization of Mechanical and Bactericidal Properties of Cement Mortars Containing Waste Glass Aggregate and Nanomaterials

    PubMed Central

    Sikora, Pawel; Augustyniak, Adrian; Cendrowski, Krzysztof; Horszczaruk, Elzbieta; Rucinska, Teresa; Nawrotek, Pawel; Mijowska, Ewa

    2016-01-01

    The recycling of waste glass is a major problem for municipalities worldwide. The problem concerns especially colored waste glass which, due to its low recycling rate as result of high level of impurity, has mostly been dumped into landfills. In recent years, a new use was found for it: instead of creating waste, it can be recycled as an additive in building materials. The aim of the study was to evaluate the possibility of manufacturing sustainable and self-cleaning cement mortars with use of commercially available nanomaterials and brown soda-lime waste glass. Mechanical and bactericidal properties of cement mortars containing brown soda-lime waste glass and commercially available nanomaterials (amorphous nanosilica and cement containing nanocrystalline titanium dioxide) were analyzed in terms of waste glass content and the effectiveness of nanomaterials. Quartz sand is replaced with brown waste glass at ratios of 25%, 50%, 75% and 100% by weight. Study has shown that waste glass can act as a successful replacement for sand (up to 100%) to produce cement mortars while nanosilica is incorporated. Additionally, a positive effect of waste glass aggregate for bactericidal properties of cement mortars was observed. PMID:28773823

  16. Suitable classification of mortars from ancient Roman and Renaissance frescoes using thermal analysis and chemometrics.

    PubMed

    Tomassetti, Mauro; Marini, Federico; Campanella, Luigi; Positano, Matteo; Marinucci, Francesco

    2015-01-01

    Literature on mortars has mainly focused on the identification and characterization of their components in order to assign them to a specific historical period, after accurate classification. For this purpose, different analytical techniques have been proposed. Aim of the present study was to verify whether the combination of thermal analysis and chemometric methods could be used to obtain a fast but correct classification of ancient mortar samples of different ages (Roman era and Renaissance). Ancient Roman frescoes from Museo Nazionale Romano (Terme di Diocleziano, Rome, Italy) and Renaissance frescoes from Sistine Chapel and Old Vatican Rooms (Vatican City) were analyzed by thermogravimetry (TG) and differential thermal analysis (DTA). Principal Component analysis (PCA) on the main thermal data evidenced the presence of two clusters, ascribable to the two different ages. Inspection of the loadings allowed to interpret the observed differences in terms of the experimental variables. PCA allowed differentiating the two kinds of mortars (Roman and Renaissance frescoes), and evidenced how the ancient Roman samples are richer in binder (calcium carbonate) and contain less filler (aggregate) than the Renaissance ones. It was also demonstrated how the coupling of thermoanalytical techniques and chemometric processing proves to be particularly advantageous when a rapid and correct differentiation and classification of cultural heritage samples of various kinds or ages has to be carried out. Graphical abstractPCA analysis of TG data allows differentiating mortar samples from different ages (Roman era and Renaissance).

  17. Determination of Chlorinated Solvent Sorption by Porous Material—Application to Trichloroethene Vapor on Cement Mortar

    PubMed Central

    Musielak, Marion; Brusseau, Mark L.; Marcoux, Manuel; Morrison, Candice; Quintard, Michel

    2014-01-01

    Experiments have been performed to investigate the sorption of trichloroethene (TCE) vapor by concrete material or, more specifically, the cement mortar component. Gas-flow experiments were conducted using columns packed with small pieces of cement mortar obtained from the grinding of typical concrete material. Transport and retardation of TCE at high vapor concentrations (500 mg L−1) was compared to that of a non-reactive gas tracer (Sulfur Hexafluoride, SF6). The results show a large magnitude of retardation (retardation factor = 23) and sorption (sorption coefficient = 10.6 cm3 g−1) for TCE, compared to negligible sorption for SF6. This magnitude of sorption obtained with pollutant vapor is much bigger than the one obtained for aqueous-flow experiments conducted for water-saturated systems. The considerable sorption exhibited for TCE under vapor-flow conditions is attributed to some combination of accumulation at the air-water interface and vapor-phase adsorption, both of which are anticipated to be significant for this system given the large surface area associated with the cement mortar. Transport of both SF6 and TCE was simulated successfully with a two-region physical non-equilibrium model, consistent with the dual-medium structure of the crushed cement mortar. This work emphasizes the importance of taking into account sorption phenomena when modeling transport of volatile organic compounds through concrete material, especially in regard to assessing vapor intrusion. PMID:25530647

  18. The Shock Hugoniot Properties of Cement Paste & Mortar up to 18 GPa

    NASA Astrophysics Data System (ADS)

    Tsembelis, K.; Proud, W. G.; Willmott, G. R.; Cross, D. L. A.

    2004-07-01

    A series of plate impact experiments was performed on cement paste and mortar. Longitudinal stresses were measured using embedded manganin stress gauges up to ca. 18 GPa. Data are then compared to those obtained in previous studies on concrete varied on aggregate size using a plate reverberation technique and velocity interferometry.

  19. Modeling Heat and Moisture Transport in Steam-Cured Mortar: Application to Aashto Type Vi Beams.

    PubMed

    Hernández-Bautista, E; Sandoval-Torres, S; de J Cano-Barrita, P F; Bentz, D P

    2017-10-01

    During steam curing of concrete, temperature and moisture gradients are developed, which are difficult to measure experimentally and can adversely affect the durability of concrete. In this research, a model of cement hydration coupled to moisture and heat transport was used to simulate the process of steam curing of mortars with water-to-cement (w/c) ratios by mass of 0.30 and 0.45, considering natural convection boundary conditions in mortar and concrete specimens of AASHTO Type VI beams. The primary variables of the model were moisture content, temperature, and degree of hydration. Moisture content profiles of mortar specimens (40 mm in diameter and 50 mm in height) were measured by magnetic resonance imaging. The degree of hydration was obtained by mass-based measurements of loss on ignition to 1000 °C. The results indicate that the model correctly simulates the moisture distribution and degree of hydration in mortar specimens. Application of the model to the steam curing of an AASHTO Type VI beam indicates temperature differences (between the surface and the center) higher than 20 °C during the cooling stage, and internal temperatures higher than 70 °C that may compromise the durability of the concrete.

  20. Properties of mortars made by uncalcined FGD gypsum-fly ash-ground granulated blast furnace slag composite binder.

    PubMed

    Zhong, Shiyun; Ni, Kun; Li, Jinmei

    2012-07-01

    A series of novel mortars were developed from composite binder of uncalcined FGD gypsum, fly ash (FA) and ground granulated blast furnace slag (GGBFS) for the good utilization of flue gas desulphurization (FGD) gypsum. At a fixed ratio (20%) of GGBFS to the composite binder, keeping consistency of the mortar between 9.5 and 10.0 cm, the properties of the composite mortar were studied. The results show that higher water/binder (W/B) is required to keep the consistency when increasing the percentage of FGD gypsum. No obvious influences of the W/B and content of FGD gypsum on the bleeding of paste were observed which keeps lower than 2% under all experimental conditions tried. The highest compressive and flexural strengths (ratio is 20% FGD gypsum, 20% GGBFS and 60% FA) are 22.6 and 4.3 MPa at 28 days, respectively. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results indicate that massive ettringite crystals and C-S-H gels exist in the hydration products. At 90 days the mortars with FGD gypsum is dramatically smaller drying shrinkage (563-938 micro strain) than that without FGD gypsum (about 2250 micro strain). The release of the SO(4)(2-) from the mortar was analyzed, indicating that the dissolution of sulfate increases with FGD gypsum. The concentration of SO(4)(2-) releasing from the mortar with 10% FGD gypsum is almost equal to that obtained from the mortar without FGD gypsum. The release of SO(4)(2-) from the mortar with 20% FGD gypsum is 9200 mg·m(-2), which is lower than that from the mortar with 95% cement clinker and 5% FGD gypsum.

  1. Binder characterisation of mortars used at different ages in the San Lorenzo church in Milan

    SciTech Connect

    Bertolini, Luca Carsana, Maddalena Gastaldi, Matteo Lollini, Federica Redaelli, Elena

    2013-06-15

    The paper describes a study on the mortars of the basilica of San Lorenzo in Milan, which was carried out to support an archaeological study aimed at dating and documenting the construction techniques used throughout the centuries. The church, which was founded between the 4th and 5th century, at the end of the period when Milan was the capital of the Roman Empire, was subjected in time to extensions, collapses and reconstructions that lasted until the Renaissance period and even later on. Thanks to the good state of conservation, San Lorenzo church is a collection of materials and construction techniques throughout a period of more than a millennium. Mortars were investigated in order to compare the binders used for structural elements built in different historical ages. From an archaeological study, samples of mortars attributed to the late Roman period, the Middle Ages and the Renaissance were available. The binder of each sample was separated by the aggregates and it was characterised on the basis of X-ray diffraction analysis, thermogravimetric analysis and scanning electron microscopy. Constituents of the binder were identified and their origin is discussed in order to investigate if they could be attributed to the original composition of the binder or to possible alteration in time due to atmospheric pollution. Results show that, even though the binder is mainly based on magnesian lime, there are significant differences in the microstructure of the binding matrix used in mortars ascribed to the different historical periods. In the Roman period, in correspondence of the structural elements that required higher strength, also hydraulic cocciopesto mortars were detected. Gypsum was found in most samples, which was maybe added intentionally. - Highlights: • Binders of mortars of San Lorenzo church in Milan were investigated. • Roman, Middle Ages and Renaissance samples were studied by XRD, TG and SEM. • Magnesian-lime binders containing silico

  2. A bioinspired wet/dry microfluidic adhesive for aqueous environments.

    PubMed

    Majumder, Abhijit; Sharma, Ashutosh; Ghatak, Animangsu

    2010-01-05

    A pressure-sensitive, nonreacting and nonfouling adhesive which can perform well both in air and underwater is very desirable because of its potential applications in various settings such as biomedical, marine, and automobile. Taking a clue from nature that many natural adhesive pads have complex structures underneath the outer adhesive layer, we have prepared thin elastic adhesive films with subsurface microstructures using PDMS (poly(dimethylsiloxane)) and investigated their performance underwater. The presence of embedded structure enhances the energy of adhesion considerably both in air and underwater. Furthermore, filling the channels with liquid of suitable surface tension modifies the internal stress profile, resulting into significant enhancement in adhesive performance. As this increase in adhesion is mediated by mechanics and not by surface chemistry, the presence of water does not alter its performance much. For the same reason, this adhesion mechanism works with both hydrophobic and hydrophilic surfaces. The adhesive can be reused because of its elastic surface. Moreover, unlike many other present-day adhesives, its performance does not decrease with time.

  3. The Rejuvenating Effect in Hot Asphalt Recycling by Mortar Transfer Ratio and Image Analysis.

    PubMed

    Wang, Fusong; Wang, Zipeng; Li, Chao; Xiao, Yue; Wu, Shaopeng; Pan, Pan

    2017-05-24

    Using a rejuvenator to improve the performance of asphalt pavement is an effective and economic way of hot asphalt recycling. This research analyzes the rejuvenating effect on aged asphalt by means of a Mortar Transfer Ratio (MTR) test, which concerns the ratio of asphalt mortar that moves from recycled aggregates (RAP aggregates) to fresh added aggregates when aged asphalt is treated with a regenerating agent and comes into contact with fresh aggregates. The proposed MTR test analyzes the regeneration in terms of the softening degree on aged asphalt when the rejuvenator is applied. The covered area ratio is studied with an image analyzing tool to understand the possibility of mortar transferring from RAP aggregates to fresh aggregates. Additionally, a micro-crack closure test is conducted and observed through a microscope. The repairing ability and diffusion characteristics of micro-cracks can therefore be analyzed. The test results demonstrate that the proposed mortar transfer ratio is a feasible way to evaluate rejuvenator diffusion during hot recycling. The mortar transfer ratio and uncovered area ratio on fresh aggregates are compatible, and can be used to quantify the contribution of the rejuvenator. Within a certain temperature range, the diffusing effect of the rejuvenator is better when the diffusing temperature is higher. The diffusion time of the rejuvenator is optimum when diffusion occurs for 4-8 h. When the rejuvenator is properly applied, the rough and cracking surface can be repaired, resulting in better covered aggregates. The micro-closure analysis visually indicates that rejuvenators can be used to repair the RAP aggregates during hot recycling.

  4. The Rejuvenating Effect in Hot Asphalt Recycling by Mortar Transfer Ratio and Image Analysis

    PubMed Central

    Wang, Fusong; Wang, Zipeng; Li, Chao; Xiao, Yue; Wu, Shaopeng; Pan, Pan

    2017-01-01

    Using a rejuvenator to improve the performance of asphalt pavement is an effective and economic way of hot asphalt recycling. This research analyzes the rejuvenating effect on aged asphalt by means of a Mortar Transfer Ratio (MTR) test, which concerns the ratio of asphalt mortar that moves from recycled aggregates (RAP aggregates) to fresh added aggregates when aged asphalt is treated with a regenerating agent and comes into contact with fresh aggregates. The proposed MTR test analyzes the regeneration in terms of the softening degree on aged asphalt when the rejuvenator is applied. The covered area ratio is studied with an image analyzing tool to understand the possibility of mortar transferring from RAP aggregates to fresh aggregates. Additionally, a micro-crack closure test is conducted and observed through a microscope. The repairing ability and diffusion characteristics of micro-cracks can therefore be analyzed. The test results demonstrate that the proposed mortar transfer ratio is a feasible way to evaluate rejuvenator diffusion during hot recycling. The mortar transfer ratio and uncovered area ratio on fresh aggregates are compatible, and can be used to quantify the contribution of the rejuvenator. Within a certain temperature range, the diffusing effect of the rejuvenator is better when the diffusing temperature is higher. The diffusion time of the rejuvenator is optimum when diffusion occurs for 4–8 h. When the rejuvenator is properly applied, the rough and cracking surface can be repaired, resulting in better covered aggregates. The micro-closure analysis visually indicates that rejuvenators can be used to repair the RAP aggregates during hot recycling. PMID:28772935

  5. Influence of the titanium dioxide addition in matrix formulation on the radwaste-mortar matrix characteristics

    SciTech Connect

    Peric, A.D.

    1996-08-01

    The rutile form of titanium dioxide (TiO{sub 2}) was added to mortar matrix preparations with to improve the mechanical and physico-chemical characteristics of the radwaste-mortar matrix mixtures, in particular the leach-rate of the immobilized radionuclide. The final solidified radwaste form was made with high water-to-cement ratio (0.36) for easy leaching of the immobilized radionuclide, {sup 137}Cs. TiO{sub 2} was added to the mortar formulation, replacing the appropriate amount of cement, in the amounts of 1, 2, 5, 8 and 10 weight percents of total cement weight. In the highly basic environment of the mortar (pH {approx_equal} 12), the titanium will form a HTiO-type membrane, which is semipermeable and selective for the cations like Cs{sup +} in the pH range above 5.5. Only the rutile form of TiO{sub 2} was observed in the prospected radwaste mortar mixture samples, using X-ray Fluorescence Spectrometry. Nevertheless, {sup 137}Cs leach-rate for the matrix formulations prepared with TiO{sub 2} was notably lower than the normally prepared (TiO{sub 2} free) samples. Furthermore, the mechanical strength of the samples prepared with TiO{sub 2} was higher than that of the TiO{sub 2}-free samples, and the correlation between the mechanical strength and TiO{sub 2} content appears to be exponential over the composition range explored here. Improvement of the physico-chemical properties of the titanium prepared formulations, is a topic of further investigations.

  6. Instant acting adhesive system

    NASA Technical Reports Server (NTRS)

    Davis, T. R.; Haines, R. C.

    1971-01-01

    Adhesive developes 80 percent of minimum bond strength of 250 psi less than 30 sec after activation is required. Adhesive is stable, handles easily, is a low toxic hazard, and is useful in industrial and domestic prototype bonding and clamping operations.

  7. Soy protein adhesives

    Treesearch

    Charles R. Frihart

    2010-01-01

    In the quest to manufacture and use building materials that are more environmentally friendly, soy adhesives can be an important component. Trees fix and store carbon dioxide in the atmosphere. After the trees are harvested, machinery converts the wood into strands, which are then bonded together with adhesives to form strandboard, used in constructing long-lasting...

  8. Fly and bottom ashes from biomass combustion as cement replacing components in mortars production: rheological behaviour of the pastes and materials compression strength.

    PubMed

    Maschio, Stefano; Tonello, Gabriele; Piani, Luciano; Furlani, Erika

    2011-10-01

    In the present research mortar pastes obtained by replacing a commercial cement with the equivalent mass of 5, 10, 20 and 30 wt.% of fly ash or bottom ash from fir chips combustion, were prepared and rheologically characterized. It was observed that the presence of ash modifies their rheological behaviour with respect to the reference blend due to the presence, in the ashes, of KCl and K2SO4 which cause precipitation of gypsum and portlandite during the first hydration stages of the pastes. Hydrated materials containing 5 wt.% of ash display compression strength and absorption at 28 d of same magnitude as the reference composition; conversely, progressive increase of ash cause a continuous decline of materials performances. Conversely, samples tested after 180 d display a marked decline of compression strength, as a consequence of potassium elution and consequent alkali-silica reaction against materials under curing.

  9. Tissue adhesives in otorhinolaryngology

    PubMed Central

    Schneider, Gerlind

    2011-01-01

    The development of medical tissue adhesives has a long history without finding an all-purpose tissue adhesive for clinical daily routine. This is caused by the specific demands which are made on a tissue adhesive, and the different areas of application. In otorhinolaryngology, on the one hand, this is the mucosal environment as well as the application on bones, cartilage and periphery nerves. On the other hand, there are stressed regions (skin, oral cavity, pharynx, oesophagus, trachea) and unstressed regions (middle ear, nose and paranasal sinuses, cranial bones). But due to the facts that adhesives can have considerable advantages in assuring surgery results, prevention of complications and so reduction of medical costs/treatment expenses, the search for new adhesives for use in otorhinolaryngology will be continued intensively. In parallel, appropriate application systems have to be developed for microscopic and endoscopic use. PMID:22073094

  10. LARC-13 adhesive development

    NASA Technical Reports Server (NTRS)

    Hill, S. G.; Sheppard, C. H.; Johnson, J. C.

    1980-01-01

    A LARC-13 type adhesive system was developed and property data obtained that demonstrated improved thermomechanical properties superior to base LARC-13 adhesive. An improved adhesive for 589 K (600 F) use was developed by physical or chemical modification of LARC-13. The adhesive was optimized for titanium and composite bonding, and a compatible surface preparation for titanium and composite substrates was identified. The data obtained with the improved adhesive system indicated it would meet the 589 K (600 F) properties desired for application on space shuttle components. Average titanium lap shear data were: (1) 21.1 MPa (3355 psi) at RT, (2) 13.0 MPa (1881 psi) at 600 F, and (3) 16.4 MPa (2335) after aging 125 hours at 600 F and tested at 600 F.

  11. Improving adhesion of seasonings to crackers with hydrocolloid solutions.

    PubMed

    Armstrong, Matthew E; Barringer, Sheryl A

    2013-11-01

    Food powders were applied on crackers that had been coated using water, oil, emulsion, sucrose, or hydrocolloid solutions. The hydrocolloids that were used include gellan gum, kappa-carrageenan, methylcellulose, gum karaya, gum tragacanth, gum arabic, guar gum, modified starch, and maltodextrin. Solutions of similar hydrophobicity to the powder gave the greatest adhesion. NaCl, barbecue (BBQ), ranch, and sour cream & onion (SC&O) seasoning showed greatest adhesion with water, cheese powder with an emulsion of 12.5% to 25% oil, and cocoa powder with oil. For NaCl, BBQ, ranch, and SC&O seasoning, hydrocolloids improved the adhesion over using water alone, with gellan gum providing the greatest adhesion. Hydrocolloid structural differences, including the presence or absence of branching, substitution of sugar units, and molecular weight affect water binding and thickening of the hydrocolloid spray that seemed to be significant factors affecting adhesion of powders to the target surface. For cheese powder, hydrocolloids were capable of replacing the oil within an emulsion while improving or maintaining the same level of adhesion, with gum arabic providing the greatest adhesion. For cocoa powder, hydrocolloid solutions were ineffective adhesives due to differences in hydrophilicity that result in insolubility. The effect of hydrocolloid concentration on adhesion was dependent both on the hydrocolloid type and the concentration that is sprayable, with 0.5% being the optimum concentration for most gums. Adhesion using sucrose solutions was determined by particle size and relative hydrophobicity. Increasing sucrose concentration decreased adhesion of smaller particles, but increased adhesion of larger particles. Adhesion of NaCl significantly increased with decreasing NaCl size using oil, water, and sucrose solutions.

  12. Coatings for rubber bonding and paint adhesion

    NASA Astrophysics Data System (ADS)

    Boulos, M. S.; Petschel, M.

    1997-08-01

    Conversion coatings form an important base for the adhesion of paint to metal substrates and for the bonding of rubber to metal parts. Four types of conversion coatings were assessed as base treatments for the bonding of rubber to steel and for the corrosion protection of metal substrates under paint: amorphous iron phosphate, heavy zinc phosphate, and three types of modified zinc phosphates that utilized one or more metal cations in addition to zinc. When applied, these conversion coatings formed a thin film over the metal substrate that was characterized by scanning electron microscopy, x-ray diffraction, and chemical methods. The performance of the coatings was assessed using physical methods such as dry adhesion, conical mandrel, impact, and stress adhesion for the rubber-bonded parts, and by corrosion resistance methods such as humidity, salt spray, and cyclic corrosion. Coating characterization and performance were correlated.

  13. Cyanoacrylate Adhesives in Eye Wounds.

    DTIC Science & Technology

    EYE, *WOUNDS AND INJURIES), (*ADHESIVES, EYE), (*ACRYLIC RESINS, ADHESIVES), CORNEA , HEALING, TISSUES(BIOLOGY), TOLERANCES(PHYSIOLOGY), NECROSIS, SURGICAL SUPPLIES, STRENGTH(PHYSIOLOGY), SURGERY, THERAPY

  14. Germinant-Enhanced Decontamination of Bacillus Spores Adhered to Iron and Cement-Mortar Drinking Water Infrastructures

    PubMed Central

    Muhammad, Nur; Heckman, Lee; Rice, Eugene W.; Hall, John

    2012-01-01

    Germination was evaluated as an enhancement to decontamination methods for removing Bacillus spores from drinking water infrastructure. Germinating spores before chlorinating cement mortar or flushing corroded iron was more effective than chlorinating or flushing alone. PMID:22267659

  15. Study on Strength of Hybrid Mortar Synthesis with Epoxy Resin, Fly Ash and Quarry Dust Under Extreme Conditions

    NASA Astrophysics Data System (ADS)

    Sudheer, P.; Muni Reddy, M. G., Dr.; Adiseshu, S., Dr.

    2017-08-01

    Blend and characterization of Bisphenol-A diglycidyl ether based thermosetting polymer mortar comprising an epoxy resin, Fly ash and Quarry dust are presented here for the strength study. The specimens have been prepared by means of an innovative process in Extreme conditions of commercial epoxy resin, Fly ash and Quarry dust based paste. In this way, thermosetting based hybrid mortars characterized by a different contents of normalized Fly ash and Quarry dust by a homogeneous distribution of the resin have been attained. Once hardened, these new composite materials show improved compressive strength and toughness in respect to both the Fly ash and Rock sand pastes since the Resin provides a more cohesive microstructure, with a reduced number of micro cracks. The micro structural characterization allows pointing out the presence of an Interfacial Transition Zone similar to that observed in cement based mortars. A correlation between micro-structural features and mechanical properties of the mortar has also been studied in Extreme conditions.

  16. Influence of Binders and Lightweight Aggregates on the Properties of Cementitious Mortars: From Traditional Requirements to Indoor Air Quality Improvement

    PubMed Central

    Pierpaoli, Mattia

    2017-01-01

    Innovative and multifunctional mortars for renders and panels were manufactured using white photocatalytic and non-photocatalytic cement as binder. Unconventional aggregates, based on lightweight materials with high specific surface and adsorbent properties, were adopted in order to investigate the possible ability to passively improve indoor air quality. The reference mortar was manufactured with traditional calcareous sand. Results show that even if the mechanical properties of mortars with unconventional aggregates generally decrease, they remain acceptable for application as render. The innovative mortars were able to passively improve indoor air quality in terms of transpirability (70% higher), moisture buffering ability (65% higher) and depolluting capacity (up to 75% higher) compared to traditional ones under the current test conditions. PMID:28829382

  17. Influence of Binders and Lightweight Aggregates on the Properties of Cementitious Mortars: From Traditional Requirements to Indoor Air Quality Improvement.

    PubMed

    Giosuè, Chiara; Pierpaoli, Mattia; Mobili, Alessandra; Ruello, Maria Letizia; Tittarelli, Francesca

    2017-08-22

    Innovative and multifunctional mortars for renders and panels were manufactured using white photocatalytic and non-photocatalytic cement as binder. Unconventional aggregates, based on lightweight materials with high specific surface and adsorbent properties, were adopted in order to investigate the possible ability to passively improve indoor air quality. The reference mortar was manufactured with traditional calcareous sand. Results show that even if the mechanical properties of mortars with unconventional aggregates generally decrease, they remain acceptable for application as render. The innovative mortars were able to passively improve indoor air quality in terms of transpirability (70% higher), moisture buffering ability (65% higher) and depolluting capacity (up to 75% higher) compared to traditional ones under the current test conditions.

  18. Germinant-enhanced decontamination of Bacillus spores adhered to iron and cement-mortar drinking water infrastructures.

    PubMed

    Szabo, Jeffrey G; Muhammad, Nur; Heckman, Lee; Rice, Eugene W; Hall, John

    2012-04-01

    Germination was evaluated as an enhancement to decontamination methods for removing Bacillus spores from drinking water infrastructure. Germinating spores before chlorinating cement mortar or flushing corroded iron was more effective than chlorinating or flushing alone.

  19. Scanning electron microscopic investigations of fresh mortars: Well-defined water-filled layers adjacent to sand grains

    SciTech Connect

    Diamond, S. Kjellsen, K.O.

    2008-04-15

    SEM examinations are reported of freshly-mixed and early age mortar specimens prepared by fast freezing in liquid nitrogen followed by epoxy impregnation, and of companion specimens of early aged mortars prepared conventionally. Freshly-mixed mortars reveal complex features that appear to influence subsequent development of the hardened state microstructure. In particular, layers of entirely water-filled space a few micrometers thick are found adjacent to many of the sand grain surfaces. After a few hours sparse deposits of calcium hydroxide crystals (and later C-S-H) are found within these layers, but the layers persist as recognizable features for at least 12 h. The layers are identically recognizable in both fast-frozen and conventionally-prepared specimens. Another feature found in freshly-mixed mortars is the existence of patchy local areas of sparsely-packed and other areas of densely-packed cement particles.

  20. Staphylococcus epidermidis adhesion on hydrophobic and hydrophilic textured biomaterial surfaces.

    PubMed

    Xu, Li-Chong; Siedlecki, Christopher A

    2014-06-01

    It is of great interest to use nano- or micro-structured surfaces to inhibit microbial adhesion and biofilm formation and thereby to prevent biomaterial-associated infection, without modification of the surface chemistry or bulk properties of the materials and without use of the drugs. Our previous study showed that a submicron textured polyurethane surface can inhibit staphylococcal bacterial adhesion and biofilm formation. To further understand the effect of the geometry of textures on bacterial adhesion as well as the underlying mechanism, in this study, submicron and micron textured polyurethane surfaces featuring ordered arrays of pillars were fabricated and modified to have different wettabilities. All the textured surfaces were originally hydrophobic and showed significant reductions in Staphylococcus epidermidis RP62A adhesion in phosphate buffered saline or 25% platelet poor plasma solutions under shear, as compared to smooth surfaces. After being subjected to an air glow discharge plasma treatment, all polyurethane surfaces were modified to hydrophilic, and reductions in bacterial adhesion on surfaces were subsequently found to be dependent on the size of the patterns. The submicron patterned surfaces reduced bacterial adhesion, while the micron patterned surfaces led to increased bacterial adhesion. The extracellular polymeric substances (EPS) from the S. epidermidis cell surfaces were extracted and purified, and were coated on a glass colloidal surface so that the adhesion force and separation energy in interactions of the EPS and the surface could be measured by colloidal probe atomic force microscopy. These results were consistent with the bacterial adhesion observations. Overall, the data suggest that the increased surface hydrophobicity and the decreased availability of the contact area contributes to a reduction in bacterial adhesion to the hydrophobic textured surfaces, while the availability of the contact area is the primary determinant factor

  1. Accelerator mass spectrometry 14C dating of lime mortars: Methodological aspects and field study applications at CIRCE (Italy)

    NASA Astrophysics Data System (ADS)

    Marzaioli, Fabio; Nonni, Sara; Passariello, Isabella; Capano, Manuela; Ricci, Paola; Lubritto, Carmine; De Cesare, Nicola; Eramo, Giacomo; Quirós Castillo, Juan Antonio; Terrasi, Filippo

    2013-01-01

    Centre for Isotopic Research on Cultural and Environmental heritage (CIRCE) has, recently, obtained some promising results in testing the feasibility of mortar radiocarbon dating by means of an ad hoc developed purification procedure (CryoSoniC: Cryobraking, Sonication, Centrifugation) applied to a series of laboratory mortars. Observed results encouraged CryoSoniC accuracy evaluation on genuine mortars sampled from archeological sites of known or independently constrained age (i.e., other 14C dates on different materials). In this study, some 14C measurements performed on genuine mortars will be discussed and compared with independently estimated (i.e., radiocarbon/archaeometrical dating) absolute chronologies of two Spanish sites. Observed results confirm the agreement of the CryoSoniC mortar dates with the archaeological expectations for both examined cases. Several authors reported the possibility of obtaining accurate radiocarbon dates of mortar matrices by analyzing lime lumps: binder-related particles of different sizes exclusively composed of calcium carbonate. In this paper, preliminary data for the absolute chronology reconstruction of the Basilica of the cemetery complex of Ponte della Lama (Canosa di Puglia, Italy) based on lime lumps will also be discussed. Dating accuracy will be quantified by comparing 14C data on mortar lime lumps from a funerary inscription of known age found near the Basilica, in the same study site. For this site, a comparison between absolute chronologies performed by bulk and CryoSoniC purified lime lumps, and charcoal incased in mortars (when found) will also be discussed. Observed results for this site provide evidence of how bulk lime lump dating may introduce systematic overestimations of the analyzed sample while CryoSoniC purification allows accurate dating.

  2. The Market Gate of Miletus: damages, material characteristics and the development of a compatible mortar for restoration

    NASA Astrophysics Data System (ADS)

    Siegesmund, Siegfried; Middendorf, Bernhard

    2008-12-01

    The indoor exhibit of the Market Gate of Miletus is unique for an archaeological monument. The reconstruction of the gate was done in such a way that most marble fragments were removed leaving cored marble columns 3-4 cm in thickness. These cored columns were mounted on a steel construction and filled with different mortars or filled with specially shaped blocks of brick combined with mortar. All the missing marble elements were replaced by copies made of a Portland cement based concrete, which is compositionally similar to the original building materials. During the Second World War the monument was heavily damaged by aerial bombardment. For 2 years the Market Gate of Miletus was exposed to weathering, because a brick wall protecting the gate was also destroyed. The deterioration phenomena observed are microcracks, macroscopic fractures, flaking, sugaring, greying, salt efflorescence, calcitic-sinter layers and iron oxide formation etc. The rapid deterioration seems to be due to indoor atmospheric effects, and also by a combination of incompatible materials (e.g. marble, steel, mortar, concrete, bricks etc.). Compatible building materials like mortars or stone replacing materials have to be developed for the planned restoration. The requirements for restoration mortars are chemical-mineralogical and physical-mechanical compatibilities with the existing building materials. In detail this means that the mortar should ensure good bonding properties, adapted strength development and not stain the marble when in direct contact. The favoured mortar was developed with a hydraulic binder based on iron-free white cement and pozzolana based on activated clay. A special limestone and quartz sand mixture was used as an aggregate. The cement was adjusted using chemical additives. Specially designed tests were applied extensively to prove whether the developed mortar is suitable for the restoration of this precious monument.

  3. Mussel adhesion - essential footwork.

    PubMed

    Waite, J Herbert

    2017-02-15

    Robust adhesion to wet, salt-encrusted, corroded and slimy surfaces has been an essential adaptation in the life histories of sessile marine organisms for hundreds of millions of years, but it remains a major impasse for technology. Mussel adhesion has served as one of many model systems providing a fundamental understanding of what is required for attachment to wet surfaces. Most polymer engineers have focused on the use of 3,4-dihydroxyphenyl-l-alanine (Dopa), a peculiar but abundant catecholic amino acid in mussel adhesive proteins. The premise of this Review is that although Dopa does have the potential for diverse cohesive and adhesive interactions, these will be difficult to achieve in synthetic homologs without a deeper knowledge of mussel biology; that is, how, at different length and time scales, mussels regulate the reactivity of their adhesive proteins. To deposit adhesive proteins onto target surfaces, the mussel foot creates an insulated reaction chamber with extreme reaction conditions such as low pH, low ionic strength and high reducing poise. These conditions enable adhesive proteins to undergo controlled fluid-fluid phase separation, surface adsorption and spreading, microstructure formation and, finally, solidification. © 2017. Published by The Company of Biologists Ltd.

  4. Cytotoxicity of denture adhesives.

    PubMed

    de Gomes, Pedro Sousa; Figueiral, Maria Helena; Fernandes, Maria Helena R; Scully, Crispian

    2011-12-01

    Ten commercially available denture adhesives, nine soluble formulations (six creams, three powders) and one insoluble product (pad), were analyzed regarding the cytotoxicity profile in direct and indirect assays using L929 fibroblast cells. In the direct assay, fibroblasts were seeded over the surface of a thick adhesive gel (5%, creams; 2.5%, powders and pad). In the indirect assay, cells were cultured in the presence of adhesive extracts prepared in static and dynamic conditions (0.5-2%, creams; 0.25-1%, powders and pad). Cell toxicity was assessed for cell viability/proliferation (MTT assay) and cell morphology (observation of the F-actin cytoskeleton organization by confocal laser scanning microscopy). Direct contact of the L929 fibroblasts with the thick adhesive gels caused no, or only a slight, decrease in cell viability/proliferation. The adhesive extracts (especially those prepared in dynamic conditions) caused significantly higher growth inhibition of fibroblasts and, in addition, caused dose- and time-dependent effects, throughout the 6-72 h exposure time. Also, dose-dependent effects on cell morphology, with evident disruption of the F-actin cytoskeleton organization, were seen in the presence of most adhesives. In conclusion, the adhesives possessed different degrees of cytotoxicity, but similar dose- and time-dependent biological profiles.

  5. Adhesive Bonding for Shelters

    DTIC Science & Technology

    1980-12-01

    weru uvaluated, the type of etch bath " sweetener " and the type of rinse\\water used. The type of etch bath " sweetener " was found to have a dramatic effect...EA9601NW Adhesives on 50521134 Bare Adherenas 39 13 Stress-Durability Behavior Sun-mary 40 14 Effect of Ltch Bath Sweetening Alloy on Interracial Durability...34"’ -,,• , •’• •"• " ,,,,, 9 Adhesive/Primer/Adherend Alloy/Surface Preparation Combinations Adherend OFPL Sweetening Rinse Adhesive:Primer Alloy Alloy

  6. Adhesion of Polymer Vesicles

    NASA Astrophysics Data System (ADS)

    Lin, John J.; Bates, Frank S.; Hammer, Daniel A.; Silas, James A.

    2005-07-01

    The adhesion and bending modulus of polybutadiene-poly(ethylene oxide) block copolymer vesicles made from a bidisperse mixture of polymers is measured using micropipette aspiration. The adhesion energy between biotinylated vesicles and avidin beads is modeled by incorporating the extension of the adhesive ligands above the surface brush of the vesicle according to the blob model of bidisperse polymer mixtures of Komura and Safran assuming the polymer brush at the surface of the vesicle is compact. The same model accurately reproduces the scaling of the bending modulus with polymer composition.

  7. Focal adhesions in osteoneogenesis

    PubMed Central

    Biggs, M.J.P; Dalby, M.J

    2010-01-01

    As materials technology and the field of tissue engineering advances, the role of cellular adhesive mechanisms, in particular the interactions with implantable devices, becomes more relevant in both research and clinical practice. A key tenet of medical device technology is to use the exquisite ability of biological systems to respond to the material surface or chemical stimuli in order to help develop next-generation biomaterials. The focus of this review is on recent studies and developments concerning focal adhesion formation in osteoneogenesis, with an emphasis on the influence of synthetic constructs on integrin mediated cellular adhesion and function. PMID:21287830

  8. [Endothelial cell adhesion molecules].

    PubMed

    Ivanov, A N; Norkin, I A; Puchin'ian, D M; Shirokov, V Iu; Zhdanova, O Iu

    2014-01-01

    The review presents current data concerning the functional role of endothelial cell adhesion molecules belonging to different structural families: integrins, selectins, cadherins, and the immunoglobulin super-family. In this manuscript the regulatory mechanisms and factors of adhesion molecules expression and distribution on the surface of endothelial cells are discussed. The data presented reveal the importance of adhesion molecules in the regulation of structural and functional state of endothelial cells in normal conditions and in pathology. Particular attention is paid to the importance of these molecules in the processes of physiological and pathological angiogenesis, regulation of permeability of the endothelial barrier and cell transmigration.

  9. Adhesive Contact Sweeper

    NASA Technical Reports Server (NTRS)

    Patterson, Jonathan D.

    1993-01-01

    Adhesive contact sweeper removes hair and particles vacuum cleaner leaves behind, without stirring up dust. Also cleans loose rugs. Sweeper holds commercially available spools of inverted adhesive tape. Suitable for use in environments in which air kept free of dust; optics laboratories, computer rooms, and areas inhabited by people allergic to dust. For carpets, best used in tandem with vacuum cleaner; first pass with vacuum cleaner removes coarse particles, and second pass with sweeper extracts fine particles. This practice extends useful life of adhesive spools.

  10. Effects of Blended-Cement Paste Chemical Composition Changes on Some Strength Gains of Blended-Mortars

    PubMed Central

    Kirgiz, Mehmet Serkan

    2014-01-01

    Effects of chemical compositions changes of blended-cement pastes (BCPCCC) on some strength gains of blended cement mortars (BCMSG) were monitored in order to gain a better understanding for developments of hydration and strength of blended cements. Blended cements (BC) were prepared by blending of 5% gypsum and 6%, 20%, 21%, and 35% marble powder (MP) or 6%, 20%, 21%, and 35% brick powder (BP) for CEMI42.5N cement clinker and grinding these portions in ball mill at 30 (min). Pastes and mortars, containing the MP-BC and the BP-BC and the reference cement (RC) and tap water and standard mortar sand, were also mixed and they were cured within water until testing. Experiments included chemical compositions of pastes and compressive strengths (CS) and flexural strengths (FS) of mortars were determined at 7th-day, 28th-day, and 90th-day according to TS EN 196-2 and TS EN 196-1 present standards. Experimental results indicated that ups and downs of silica oxide (SiO2), sodium oxide (Na2O), and alkali at MP-BCPCC and continuously rising movement of silica oxide (SiO2) at BP-BCPCC positively influenced CS and FS of blended cement mortars (BCM) in comparison with reference mortars (RM) at whole cure days as MP up to 6% or BP up to 35% was blended for cement. PMID:24587737

  11. Utilization of recycled cathode ray tubes glass in cement mortar for X-ray radiation-shielding applications.

    PubMed

    Ling, Tung-Chai; Poon, Chi-Sun; Lam, Wai-Shung; Chan, Tai-Po; Fung, Karl Ka-Lok

    2012-01-15

    Recycled glass derived from cathode ray tubes (CRT) glass with a specific gravity of approximately 3.0 g/cm(3) can be potentially suitable to be used as fine aggregate for preparing cement mortars for X-ray radiation-shielding applications. In this work, the effects of using crushed glass derived from crushed CRT funnel glass (both acid washed and unwashed) and crushed ordinary beverage container glass at different replacement levels (0%, 25%, 50%, 75% and 100% by volume) of sand on the mechanical properties (strength and density) and radiation-shielding performance of the cement-sand mortars were studied. The results show that all the prepared mortars had compressive strength values greater than 30 MPa which are suitable for most building applications based on ASTM C 270. The density and shielding performance of the mortar prepared with ordinary crushed (lead-free) glass was similar to the control mortar. However, a significant enhancement of radiation-shielding was achieved when the CRT glasses were used due to the presence of lead in the glass. In addition, the radiation shielding contribution of CRT glasses was more pronounced when the mortar was subject to a higher level of X-ray energy.

  12. Effects of blended-cement paste chemical composition changes on some strength gains of blended-mortars.

    PubMed

    Kirgiz, Mehmet Serkan

    2014-01-01

    Effects of chemical compositions changes of blended-cement pastes (BCPCCC) on some strength gains of blended cement mortars (BCMSG) were monitored in order to gain a better understanding for developments of hydration and strength of blended cements. Blended cements (BC) were prepared by blending of 5% gypsum and 6%, 20%, 21%, and 35% marble powder (MP) or 6%, 20%, 21%, and 35% brick powder (BP) for CEMI42.5N cement clinker and grinding these portions in ball mill at 30 (min). Pastes and mortars, containing the MP-BC and the BP-BC and the reference cement (RC) and tap water and standard mortar sand, were also mixed and they were cured within water until testing. Experiments included chemical compositions of pastes and compressive strengths (CS) and flexural strengths (FS) of mortars were determined at 7th-day, 28th-day, and 90th-day according to TS EN 196-2 and TS EN 196-1 present standards. Experimental results indicated that ups and downs of silica oxide (SiO2), sodium oxide (Na2O), and alkali at MP-BCPCC and continuously rising movement of silica oxide (SiO2) at BP-BCPCC positively influenced CS and FS of blended cement mortars (BCM) in comparison with reference mortars (RM) at whole cure days as MP up to 6% or BP up to 35% was blended for cement.

  13. Probing adhesion forces at the molecular scale

    SciTech Connect

    Thomas, R.C.; Houston, J.E.; Michalske, T.A.

    1996-12-31

    Measurements of adhesion forces at the molecular scale, such as those discussed here, are necessary to understand macroscopic boundary-layer behavior such as adhesion, friction, wear, lubrication, and many other important phenomena. The authors` recent interfacial force microscopy (IFM) studies have provided detailed information about the mechanical response of both self-assembled monolayer (SAM) films and the underlying substrates. In addition, they recently demonstrated that the IFM is useful for studying the chemical nature of such films. In this talk, the authors discuss a new method for studying surface interactions and chemical reactions using the IFM. To quantitatively measure the work of adhesion and bond energies between two organic thin films, they modify both a Au substrate and a Au probe with self-assembling organomercaptan molecules having either the same or different end groups (-CH{sub 3}, -NH{sub 2}, and -COOH), and then analyze the force-versus-displacement curves (force profiles) that result from the approach to contact of the two surfaces. Their results show that the magnitude of the adhesive forces measured between methyl-methyl interactions are in excellent agreement with van der Waals calculations using Lifshitz theory and previous experimentally determined values. Moreover, the measured peak adhesive forces scale as expected for van der Waals, hydrogen-bonding, and acid-base interactions.

  14. Role of cellular adhesions in tissue dynamics spectroscopy

    NASA Astrophysics Data System (ADS)

    Merrill, Daniel A.; An, Ran; Turek, John; Nolte, David

    2014-02-01

    Cellular adhesions play a critical role in cell behavior, and modified expression of cellular adhesion compounds has been linked to various cancers. We tested the role of cellular adhesions in drug response by studying three cellular culture models: three-dimensional tumor spheroids with well-developed cellular adhesions and extracellular matrix (ECM), dense three-dimensional cell pellets with moderate numbers of adhesions, and dilute three-dimensional cell suspensions in agarose having few adhesions. Our technique for measuring the drug response for the spheroids and cell pellets was biodynamic imaging (BDI), and for the suspensions was quasi-elastic light scattering (QELS). We tested several cytoskeletal chemotherapeutic drugs (nocodazole, cytochalasin-D, paclitaxel, and colchicine) on three cancer cell lines chosen from human colorectal adenocarcinoma (HT-29), human pancreatic carcinoma (MIA PaCa-2), and rat osteosarcoma (UMR-106) to exhibit differences in adhesion strength. Comparing tumor spheroid behavior to that of cell suspensions showed shifts in the spectral motion of the cancer tissues that match predictions based on different degrees of cell-cell contacts. The HT-29 cell line, which has the strongest adhesions in the spheroid model, exhibits anomalous behavior in some cases. These results highlight the importance of using three-dimensional tissue models in drug screening with cellular adhesions being a contributory factor in phenotypic differences between the drug responses of tissue and cells.

  15. Optical adhesive property study

    SciTech Connect

    Sundvold, P.D.

    1996-01-01

    Tests were performed to characterize the mechanical and thermal properties of selected optical adhesives to identify the most likely candidate which could survive the operating environment of the Direct Optical Initiation (DOI) program. The DOI system consists of a high power laser and an optical module used to split the beam into a number of channels to initiate the system. The DOI requirements are for a high shock environment which current military optical systems do not operate. Five candidate adhesives were selected and evaluated using standardized test methods to determine the adhesives` physical properties. EC2216, manufactured by 3M, was selected as the baseline candidate adhesive based on the test results of the physical properties.

  16. Adhesion of Lunar Dust

    NASA Technical Reports Server (NTRS)

    Walton, Otis R.

    2007-01-01

    This paper reviews the physical characteristics of lunar dust and the effects of various fundamental forces acting on dust particles on surfaces in a lunar environment. There are transport forces and adhesion forces after contact. Mechanical forces (i.e., from rover wheels, astronaut boots and rocket engine blast) and static electric effects (from UV photo-ionization and/or tribo-electric charging) are likely to be the major contributors to the transport of dust particles. If fine regolith particles are deposited on a surface, then surface energy-related (e.g., van der Walls) adhesion forces and static-electric-image forces are likely to be the strongest contributors to adhesion. Some measurement techniques are offered to quantify the strength of adhesion forces. And finally some dust removal techniques are discussed.

  17. Adhesives for Aerospace

    NASA Technical Reports Server (NTRS)

    Meade, L. E.

    1985-01-01

    The industry is hereby challenged to integrate adhesive technology with the total structure requirements in light of today's drive into automation/mechanization. The state of the art of adhesive technology is fairly well meeting the needs of the structural designers, the processing engineer, and the inspector, each on an individual basis. The total integration of these needs into the factory of the future is the next collective hurdle to be achieved. Improved processing parameters to fit the needs of automation/mechanization will necessitate some changes in the adhesive forms, formulations, and chemistries. Adhesives have, for the most part, kept up with the needs of the aerospace industry, normally leading the rest of the industry in developments. The wants of the aerospace industry still present a challenge to encompass all elements, achieving a totally integrated joined and sealed structural system. Better toughness with hot-wet strength improvements is desired. Lower cure temperatures, longer out times, and improved corrosion inhibition are desired.

  18. Electrochemical deposition of conductive and adhesive polypyrrole-dopamine films

    PubMed Central

    Kim, Semin; Jang, Lindy K.; Park, Hyun S.; Lee, Jae Young

    2016-01-01

    Electrode surfaces have been widely modified with electrically conductive polymers, including polypyrrole (PPY), to improve the performance of electrodes. To utilize conductive polymers for electrode modification, strong adhesion between the polymer films and electrode substrates should be ensured with high electrical/electrochemical activities. In this study, PPY films were electrochemically polymerized on electrodes (e.g., indium tin oxide (ITO)) with dopamine as a bio-inspired adhesive molecule. Efficient and fast PPY electrodeposition with dopamine (PDA/PPY) was found; the resultant PDA/PPY films exhibited greatly increased adhesion strengths of up to 3.7 ± 0.8 MPa and the modified electrodes had electrochemical impedances two to three orders of magnitude lower than that of an unmodified electrode. This electrochemical deposition of adhesive and conductive PDA/PPY offers a facile and versatile electrode modification for various applications, such as biosensors and batteries. PMID:27459901

  19. Electrochemical deposition of conductive and adhesive polypyrrole-dopamine films.

    PubMed

    Kim, Semin; Jang, Lindy K; Park, Hyun S; Lee, Jae Young

    2016-07-27

    Electrode surfaces have been widely modified with electrically conductive polymers, including polypyrrole (PPY), to improve the performance of electrodes. To utilize conductive polymers for electrode modification, strong adhesion between the polymer films and electrode substrates should be ensured with high electrical/electrochemical activities. In this study, PPY films were electrochemically polymerized on electrodes (e.g., indium tin oxide (ITO)) with dopamine as a bio-inspired adhesive molecule. Efficient and fast PPY electrodeposition with dopamine (PDA/PPY) was found; the resultant PDA/PPY films exhibited greatly increased adhesion strengths of up to 3.7 ± 0.8 MPa and the modified electrodes had electrochemical impedances two to three orders of magnitude lower than that of an unmodified electrode. This electrochemical deposition of adhesive and conductive PDA/PPY offers a facile and versatile electrode modification for various applications, such as biosensors and batteries.

  20. Electrochemical deposition of conductive and adhesive polypyrrole-dopamine films

    NASA Astrophysics Data System (ADS)

    Kim, Semin; Jang, Lindy K.; Park, Hyun S.; Lee, Jae Young

    2016-07-01

    Electrode surfaces have been widely modified with electrically conductive polymers, including polypyrrole (PPY), to improve the performance of electrodes. To utilize conductive polymers for electrode modification, strong adhesion between the polymer films and electrode substrates should be ensured with high electrical/electrochemical activities. In this study, PPY films were electrochemically polymerized on electrodes (e.g., indium tin oxide (ITO)) with dopamine as a bio-inspired adhesive molecule. Efficient and fast PPY electrodeposition with dopamine (PDA/PPY) was found; the resultant PDA/PPY films exhibited greatly increased adhesion strengths of up to 3.7 ± 0.8 MPa and the modified electrodes had electrochemical impedances two to three orders of magnitude lower than that of an unmodified electrode. This electrochemical deposition of adhesive and conductive PDA/PPY offers a facile and versatile electrode modification for various applications, such as biosensors and batteries.

  1. Improvement of mechanical properties of fiber reinforced mortar using a linear optimization method

    NASA Astrophysics Data System (ADS)

    Kočí, V.; Černý, R.

    2017-02-01

    A linear optimization method is applied to improve mechanical properties of fiber reinforced cement mortar. Since this method is preferably used in other scientific disciplines, few preconditions are taken into account in advance, in order to accommodate it to the specifics related to building materials design. Defining physical limitations and accelerating the optimization process, the target values of optimization are reached in 21 days after 3 optimization steps. Within this relatively short time span, the compressive and bending strengths of fiber reinforced cement mortar increase from 36.9 to 52.2 MPa and from 9.1 to 10.1 MPa, respectively, while identical components are used. The improvements are achieved after preparation of only nine different mixtures, which is a very small number confirming the effectivity of this method in the field of building materials design.

  2. A hybrid mortar virtual element method for discrete fracture network simulations

    NASA Astrophysics Data System (ADS)

    Benedetto, Matías Fernando; Berrone, Stefano; Borio, Andrea; Pieraccini, Sandra; Scialò, Stefano

    2016-02-01

    The most challenging issue in performing underground flow simulations in Discrete Fracture Networks (DFN) is to effectively tackle the geometrical difficulties of the problem. In this work we put forward a new application of the Virtual Element Method combined with the Mortar method for domain decomposition: we exploit the flexibility of the VEM in handling polygonal meshes in order to easily construct meshes conforming to the traces on each fracture, and we resort to the mortar approach in order to "weakly" impose continuity of the solution on intersecting fractures. The resulting method replaces the need for matching grids between fractures, so that the meshing process can be performed independently for each fracture. Numerical results show optimal convergence and robustness in handling very complex geometries.

  3. Effect of a micro-copolymer addition on the thermal conductivity of fly ash mortars

    PubMed Central

    Durán-Herrera, A.; Campos-Dimas, J. K.; Valdez-Tamez, P.L.; Bentz, D. P.

    2015-01-01

    In this study, a copolymer composed of hollow spherical particles with an average particle size of 90 µm was evaluated as a lightweight aggregate in Portland cement-fly ash mortars to improve the thermal conductivity (k) of the composite. Mortars were produced for three different water/binder ratios by mass (w/b), 0.4, 0.5 and 0.6. Optimized proportions were obtained for a minimum target compressive strength of 35 kgf/cm2 (3.4 MPa) according to the requirements of Mexican standards for non-structural masonry units. Thermal conductivity was determined for dry and saturated samples through the transient plane technique with average results of 0.16 W/(m·K) and 0.31 W/(m·K), respectively. These values represent an increment of 23 % and a reduction of 33 %, respectively, in comparison to an efficient Portland cement-based commercially available thermal insulator. PMID:27453717

  4. Properties of Roman bricks and mortars used in Serapis temple in the city of Pergamon

    SciTech Connect

    Ozkaya, Ozlem Aslan; Boeke, Hasan

    2009-09-15

    Serapis temple, which was constructed in the Roman period in the city of Pergamon (Bergama/Turkey), is one of the most important monuments of the world heritage. In this study, the characteristics of bricks and mortars used in the temple have been determined in order to define the necessary characteristics of the intervention materials, which will be used in the conservation works of the temple. Several analyses were carried out to determine their basic physical properties, raw material compositions, mineralogical and microstructural properties using X-ray diffraction, Scanning Electron Microscope and a Thermo Gravimetric Analyzer. Analysis results indicated that the mortars are stiff, compact and hydraulic due to the use of natural pozzolanic aggregates. The Roman bricks are of low density, high porosity and were produced from raw materials containing calcium poor clays fired at low temperatures.

  5. Processing of Sugarcane Bagasse ash and Reactivity of Ash-blended Cement Mortar

    NASA Astrophysics Data System (ADS)

    Ajay, Goyal; Hattori, Kunio; Ogata, Hidehiko; Ashraf, Muhammad

    Sugarcane bagasse ash (SCBA), a sugar-mill waste, has the potential of a partial cement replacement material if processed and obtained under controlled conditions. This paper discusses the reactivity of SCBA obtained by control burning of sugarcane bagasse procured from Punjab province of India. X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were employed to ascertain the amorphousness and morphology of the minerals ash particles. Destructive and non-destructive tests were conducted on SCBA-blended mortar specimens. Ash-blended cement paste specimens were analyzed by XRD, thermal analysis, and SEM methods to evaluate the hydration reaction of SCBA with cement. Results showed that the SCBA processed at 600°C for 5 hours was reactive as ash-blended mortar specimens with up to 15% substitution of cement gave better strength than control specimens.

  6. Dynamic tensile fracture of mortar at ultra-high strain-rates

    NASA Astrophysics Data System (ADS)

    Erzar, B.; Buzaud, E.; Chanal, P.-Y.

    2013-12-01

    During the lifetime of a structure, concrete and mortar may be exposed to highly dynamic loadings, such as impact or explosion. The dynamic fracture at high loading rates needs to be well understood to allow an accurate modeling of this kind of event. In this work, a pulsed-power generator has been employed to conduct spalling tests on mortar samples at strain-rates ranging from 2 × 104 to 4 × 104 s-1. The ramp loading allowed identifying the strain-rate anytime during the test. A power law has been proposed to fit properly the rate-sensitivity of tensile strength of this cementitious material over a wide range of strain-rate. Moreover, a specimen has been recovered damaged but unbroken. Micro-computed tomography has been employed to study the characteristics of the damage pattern provoked by the dynamic tensile loading.

  7. Strengthening of Existing Bridge Structures for Shear and Bending with Carbon Textile-Reinforced Mortar

    PubMed Central

    Herbrand, Martin; Classen, Martin; Kueres, Dominik; Hegger, Josef

    2017-01-01

    Increasing traffic loads and changes in code provisions lead to deficits in shear and flexural capacity of many existing highway bridges. Therefore, a large number of structures are expected to require refurbishment and strengthening in the future. This projection is based on the current condition of many older road bridges. Different strengthening methods for bridges exist to extend their service life, all having specific advantages and disadvantages. By applying a thin layer of carbon textile-reinforced mortar (CTRM) to bridge deck slabs and the webs of pre-stressed concrete bridges, the fatigue and ultimate strength of these members can be increased significantly. The CTRM layer is a combination of a corrosion resistant carbon fiber reinforced polymer (CFRP) fabric and an efficient mortar. In this paper, the strengthening method and the experimental results obtained at RWTH Aachen University are presented. PMID:28925962

  8. Comparative investigation of corrosion resistance of steel reinforcement in alinite and Portland cement mortars

    SciTech Connect

    Kostogloudis, G.C.; Kalogridis, D.; Ftikos, C.; Malami, C.; Georgali, B.; Kaloidas, V.

    1998-07-01

    The corrosion resistance of steel-reinforced mortar specimens made from alinite cement was investigated using ordinary Portland cement (OPC) specimens as reference. The specimens were prepared and exposed in three different environments: continuous exposure in tap water, interrupted exposure in tap water, and interrupted exposure in 3.5% NaCl solution. The steel weight loss and the half cell potential were measured vs. exposure time, up to the age of 12 months. Pore solution extraction and analysis and porosity determination were also performed. In continuous exposure in tap water, alinite cement provided adequate protection against corrosion. In interrupted exposure in tap water, a higher corrosion was observed for alinite cement compared to OPC. In the case of interrupted exposure in 3.5% NaCl solution, the simultaneous action of free chlorides and oxygen resulted in the depassivation of steel reinforcing bars in alinite and Portland cement mortars, and led to severe corrosion effect.

  9. Characterization of methacrylated polysaccharides in combination with amine-based monomers for application in mortar.

    PubMed

    Mignon, Arn; Devisscher, Dries; Vermeulen, Jolien; Vagenende, Maxime; Martins, José; Dubruel, Peter; De Belie, Nele; Van Vlierberghe, Sandra

    2017-07-15

    Smart pH-responsive superabsorbent polymers (SAPs) could be useful for self-healing of cracks in mortar. They will swell minimally during the alkaline conditions of mixing, leading to only small macro-pores but will swell stronger with a lower pH when water enters the cracks. As such, polysaccharides (alginate, chitosan and agarose) were methacrylated and cross-linked with amine-based monomers (dimethylaminoethyl methacrylate and dimethylaminopropyl methacrylamide) to induce a varying pH-sensitivity. These materials showed a strong cross-linking efficiency and induced moisture uptake capacities up to 122% at 95% relative humidity with a negligible hysteresis. Additionally, interesting pH-responsive swelling capacities were obtained, especially for SAPs based on chitosan and agarose with values up to 110gwater/gSAP. Most of these materials showed limited hydrolysis in cement filtrate solutions, making them very promising for use in mortar. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Epithelial adhesive junctions

    PubMed Central

    Capaldo, Christopher T.; Farkas, Attila E.

    2014-01-01

    Epithelial adhesive cell-to-cell contacts contain large, plasma membrane-spanning multiprotein aggregates that perform vital structural and signaling functions. Three prominent adhesive contacts are the tight junction, adherens junction, and the desmosome. Each junction type has unique cellular functions and a complex molecular composition. In this review, we comment on recent and exciting advances in our understanding of junction composition and function. PMID:24592313

  11. Adhesion to porcelain and metal.

    PubMed

    Bertolotti, Raymond L

    2007-04-01

    Some compelling clinical benefits of porcelain and metal adhesion are presented. Current concepts for metal adhesion are reviewed, including modifications of metal surface and resin chemistry. Porcelain adhesion is reviewed, including little-known methods that use silane but no hydrofluoric acid etching. Clinical protocols for use of metal and porcelain adhesives are presented.

  12. Cohesion and Adhesion with Proteins

    Treesearch

    Charles R. Frihart

    2016-01-01

    With increasing interest in bio-based adhesives, research on proteins has expanded because historically they have been used by both nature and humans as adhesives. A wide variety of proteins have been used as wood adhesives. Ancient Egyptians most likely used collagens tobond veneer to wood furniture, then came casein (milk), blood, fish scales, and soy adhesives, with...

  13. Many Roles of Wood Adhesives

    Treesearch

    Charles R. Frihart

    2014-01-01

    Although wood bonding is one of the oldest applications of adhesives, going back to early recorded history (1), some aspects of wood bonds are still not fully understood. Most books in the general area of adhesives and adhesion do not cover wood bonding. However, a clearer understanding of wood bonding and wood adhesives can lead to improved products. This is important...

  14. Practical aspects of the use of phosphate binding materials in refractory mixtures, mortars and putties

    NASA Technical Reports Server (NTRS)

    Soltysik, B.; Pawelek, A.; Witkowska, E.

    1983-01-01

    Phosphate binders, particularly acidic phosphates of Al and Cr, are used for binding Al silicate refractories used for lining of burners, SiC refractories, and refractory mortars. The binders have apparent d. 2.13-2.18 g/cu cm, porosity 21.4-23.8%, compressive strength 223 71 kg/ sq cm, total shrinkage 0.2-0.8%, and refractoriness 1240 deg.

  15. Advances in Telemetry Capability as Demonstrated on an Affordable Precision Mortar

    DTIC Science & Technology

    2012-06-01

    mortar that allowed the guidance, navigation, and control ( GNC ) system to be effectively analyzed. The first is a technique for the real-time...guidance, navigation, and control ( GNC ) system to be effectively analyzed. The first is a technique for the real-time integration and extraction of GPS...introduction of a GPS receiver and GNC subsections in later tests created new telemetry challenges. This paper presents three of the techniques

  16. Petrographic microscope investigation of mortar and ceramic technologies for the conservation of the built heritage

    NASA Astrophysics Data System (ADS)

    Pavia, S.; Caro, S.

    2007-07-01

    Polarised-light (or petrographic) microscopy has been widely applied to heritage materials to assess composition and diagnose damage. However, instead, this paper focuses on the petrographic investigation of brick and mortar technologies for the production of quality repair materials compatible with their adjacent fabrics. Furthermore, the paper relates production technologies to the physical properties of the materials fabricated, and thus their final quality and durability. According to Cesare Brandi´s theory of compatibility (the 20th century architect on whose work modern conservation theory and practice are largely based) existing historic materials should be replaced with their equivalent. This paper demonstrates that polarised-light microscopy provides data on the origin and nature of raw materials, and processing parameters such as blending, mixing, firing, calcination and slaking, and how these relate to the quality of the final product. In addition, this paper highlights the importance of production technologies as these directly impact the physical properties of the materials fabricated and thus determine their final quality and durability. In this context, the paper investigates mortar calcination and slaking, two important operations in the manufacture of building limes that govern the reactivity, shrinkage and water retention of a lime binder which will impact mortar's properties such as workability, plasticity and carbonation speed, and these in turn will determine the ease of execution, durability and strength of a lime mortar. Petrographic analysis also provides evidence of ceramic technology including identification of local or foreign production and processing parameters such as sieving, blending, mixing and firing. A petrographic study of the ceramic matrix coupled to the diagnosis of mineral phases formed during firing allows to quantify sintering and vitrification and thus determine firing temperatures. Finally, certain features of the raw

  17. Effects of lithium salts on ASR gel composition and expansion of mortars

    SciTech Connect

    Kawamura, Mitsunori; Fuwa, Hirohito

    2003-06-01

    Suppression of alkali-silica reaction (ASR) expansion in mortar and concrete by the addition of lithium salts has been confirmed by some workers. It has been revealed that lithium hydroxide tended to reduce the reaction between sodium or potassium hydroxide and reactive silica, and that the ASR gel incorporating lithium was less expansive. However, it has not been reported how the addition of a lithium salt influenced the composition of the ASR gel. The calcium in ASR gel is considered to play an important role in the expansion of the gel. Thus, it is significant to characterize ASR gel composition in mortars containing lithium salts by BSE-EDS analysis. This study aims to discuss the mechanisms of suppression of ASR expansion in mortar by lithium salts from the viewpoint of ASR gel composition. The average CaO/SiO{sub 2} ratio in ASR gels decreased with increasing amount of added lithium salts. It should be noted that the extent of variations in the CaO/SiO{sub 2} ratio in ASR gels significantly decreased with increasing amount of lithium salts. The addition of relatively small amounts of LiOH and Li{sub 2}CO{sub 3} resulted in increased expansion. We also obtained an unexpected result that ASR gels became homogeneous with respect to their CaO contents at high dosage levels. However, the reduction in average CaO/SiO{sub 2} ratios and the homogenization in the CaO content of ASR gels due to the addition of lithium salts may not be related to the expansion of mortars.

  18. A fictitious domain/mortar element method for fluid-structure interaction

    NASA Astrophysics Data System (ADS)

    Baaijens, Frank P. T.

    2001-04-01

    A new method for the computational analysis of fluid-structure interaction of a Newtonian fluid with slender bodies is developed. It combines ideas of the fictitious domain and the mortar element method by imposing continuity of the velocity field along an interface by means of Lagrange multipliers. The key advantage of the method is that it circumvents the need for complicated mesh movement strategies common in arbitrary Lagrangian-Eulerian (ALE) methods, usually used for this purpose. Copyright

  19. An Investigation at Low Speed of the Spin Instability of Mortar-Shell Tails

    NASA Technical Reports Server (NTRS)

    Bird, John D.; Lichtenstein, Jacob H.

    1957-01-01

    An investigation was made in the Langley stability tunnel to study the influence of number of fins, fin shrouding, and fin aspect ratio on the spin instability of mortar-shell tail surfaces. It was found that the 12-fin tails tested spun less rapidly throughout the angle-of-yaw range than did the 6-fin tails and that fin shrouding reduced the spin encountered by a large amount.

  20. Genistein Modified Polymer Blends for Hemodialysis Membranes

    NASA Astrophysics Data System (ADS)

    Chang, Teng; Kyu, Thein; Define, Linda; Alexander, Thomas

    2012-02-01

    A soybean-derived phytochemical called genistein was used as a modifying agent to polyether sulfone/polyvinyl pyrrolidone (PES/PVP) blends to produce multi-functional hemodialysis membranes. With the aid of phase diagrams of PES/PVP/genistein blends, asymmetric porous membranes were fabricated by coagulating in non-solvent. Both unmodified and genistein modified PES/PVP membranes were shown to be non-cytotoxic to the blood cells. Unmodified PES/PVP membranes were found to reduce reactive oxygen species (ROS) levels, whereas the genistein modified membranes exhibited suppression for ˜60% of the ROS levels. Also, the genistein modified membranes revealed significant suppression of pro-inflammatory cytokines: IL-1β, IL-6, and TNF-α. Moreover, addition of PVP to PES showed the reduced trend of platelet adhesion and then leveled off. However, the modified membranes exhibited suppression of platelet adhesion at low genistein loading, but beyond 15 wt%, the platelet adhesion level rised up.

  1. Rheology of Carbon Fibre Reinforced Cement-Based Mortar

    SciTech Connect

    Banfill, Phillip F. G.; Starrs, Gerry; McCarter, W. John

    2008-07-07

    Carbon fibre reinforced cement based materials (CFRCs) offer the possibility of fabricating 'smart' electrically conductive materials. Rheology of the fresh mix is crucial to satisfactory moulding and fresh CFRC conforms to the Bingham model with slight structural breakdown. Both yield stress and plastic viscosity increase with increasing fibre length and volume concentration. Using a modified Viskomat NT, the concentration dependence of CFRC rheology up to 1.5% fibre volume is reported.

  2. Assessment and prediction of drying shrinkage cracking in bonded mortar overlays

    SciTech Connect

    Beushausen, Hans Chilwesa, Masuzyo

    2013-11-15

    Restrained drying shrinkage cracking was investigated on composite beams consisting of substrate concrete and bonded mortar overlays, and compared to the performance of the same mortars when subjected to the ring test. Stress development and cracking in the composite specimens were analytically modeled and predicted based on the measurement of relevant time-dependent material properties such as drying shrinkage, elastic modulus, tensile relaxation and tensile strength. Overlay cracking in the composite beams could be very well predicted with the analytical model. The ring test provided a useful qualitative comparison of the cracking performance of the mortars. The duration of curing was found to only have a minor influence on crack development. This was ascribed to the fact that prolonged curing has a beneficial effect on tensile strength at the onset of stress development, but is in the same time not beneficial to the values of tensile relaxation and elastic modulus. -- Highlights: •Parameter study on material characteristics influencing overlay cracking. •Analytical model gives good quantitative indication of overlay cracking. •Ring test presents good qualitative indication of overlay cracking. •Curing duration has little effect on overlay cracking.

  3. Application of nanoindentation testing to study of the interfacial transition zone in steel fiber reinforced mortar

    SciTech Connect

    Wang Xiaohui Jacobsen, Stefan; He Jianying; Zhang Zhiliang; Lee, Siaw Foon; Lein, Hilde Lea

    2009-08-15

    The characteristics of the profiles of elastic modulus and hardness of the steel fiber-matrix and fiber-matrix-aggregate interfacial zones in steel fiber reinforced mortars have been investigated by using nanoindentation and Scanning Electron Microscopy (SEM), where two sets of parameters, i.e. water/binder ratio and content of silica fume were considered. Different interfacial bond conditions in the interfacial transition zones (ITZ) are discussed. For sample without silica fume, efficient interfacial bonds across the steel fiber-matrix and fiber-matrix-aggregate interfaces are shown in low water/binder ratio mortar; while in high water/binder ratio mortar, due to the discontinuous bleeding voids underneath the fiber, the fiber-matrix bond is not very good. On the other hand, for sample with silica fume, the addition of 10% silica fume leads to no distinct presence of weak ITZ in the steel fiber-matrix interface; but the effect of the silica fume on the steel fiber-matrix-aggregate interfacial zone is not obvious due to voids in the vicinity of steel fiber.

  4. Comparative Effect of Bio-waste Ashes on Strength Properties of Cement Mortar

    NASA Astrophysics Data System (ADS)

    Ajay, Goyal; Hattori, Kunio; Ogata, Hidehiko; Ashraf, Muhammad; Ahmed, Mohamed Anwar

    Biomass fuels produce about 400 million tonnes of ashes as waste material. This paper discusses the pozzolanic character of bio-waste ashes obtained from dry tree leaves (AML), Korai grass (KRI) and Tifton grass (TFT). Ashes were obtained by control incineration of the wastes at 600°C for 5 hours and mortar specimens were prepared by substituting cement with 10, 20 and 30% ash. Strength development of ash-blended mortar specimens was evaluated by conducting destructive tests as well as non-destructive tests till 91 days. X-ray diffraction, scanning electron microscopic and thermo-gravimetric techniques were used to analyze the influence of ash substitution on strength properties of blended-mortar. Pozzolanic reactivity of AML- and KRI-ash was confirmed, but TFT-ash did not show enough reactivity. Overall results confirmed that up to 20% substitution of cement can be made with AML- or KRI-ash with strength approaching 90% of that of control.

  5. Strength and Durability Performance of Alkali-Activated Rice Husk Ash Geopolymer Mortar

    PubMed Central

    Kim, Yun Yong; Lee, Byung-Jae; Saraswathy, Velu

    2014-01-01

    This paper describes the experimental investigation carried out to develop the geopolymer concrete based on alkali-activated rice husk ash (RHA) by sodium hydroxide with sodium silicate. Effect on method of curing and concentration of NaOH on compressive strength as well as the optimum mix proportion of geopolymer mortar was investigated. It is possible to achieve compressive strengths of 31 N/mm2 and 45 N/mm2, respectively for the 10 M alkali-activated geopolymer mortar after 7 and 28 days of casting when cured for 24 hours at 60°C. Results indicated that the increase in curing period and concentration of alkali activator increased the compressive strength. Durability studies were carried out in acid and sulfate media such as H2SO4, HCl, Na2SO4, and MgSO4 environments and found that geopolymer concrete showed very less weight loss when compared to steam-cured mortar specimens. In addition, fluorescent optical microscopy and X-ray diffraction (XRD) studies have shown the formation of new peaks and enhanced the polymerization reaction which is responsible for strength development and hence RHA has great potential as a substitute for ordinary Portland cement concrete. PMID:25506063

  6. Monitoring accelerated carbonation on standard Portland cement mortar by nonlinear resonance acoustic test

    NASA Astrophysics Data System (ADS)

    Eiras, J. N.; Kundu, T.; Popovics, J. S.; Monzó, J.; Borrachero, M. V.; Payá, J.

    2015-03-01

    Carbonation is an important deleterious process for concrete structures. Carbonation begins when carbon dioxide (CO2) present in the atmosphere reacts with portlandite producing calcium carbonate (CaCO3). In severe carbonation conditions, C-S-H gel is decomposed into silica gel (SiO2.nH2O) and CaCO3. As a result, concrete pore water pH decreases (usually below 10) and eventually steel reinforcing bars become unprotected from corrosion agents. Usually, the carbonation of the cementing matrix reduces the porosity, because CaCO3 crystals (calcite and vaterite) occupy more volume than portlandite. In this study, an accelerated carbonation-ageing process is conducted on Portland cement mortar samples with water to cement ratio of 0.5. The evolution of the carbonation process on mortar is monitored at different levels of ageing until the mortar is almost fully carbonated. A nondestructive technique based on nonlinear acoustic resonance is used to monitor the variation of the constitutive properties upon carbonation. At selected levels of ageing, the compressive strength is obtained. From fractured surfaces the depth of carbonation is determined with phenolphthalein solution. An image analysis of the fractured surfaces is used to quantify the depth of carbonation. The results from resonant acoustic tests revealed a progressive increase of stiffness and a decrease of material nonlinearity.

  7. Sustainability, Eco-Point and Engineering Performance of Different Workability OPC Fly-Ash Mortar Mixes

    PubMed Central

    Razi, Putri Zulaiha; Abdul Razak, Hashim; Khalid, Nur Hafizah A.

    2016-01-01

    This study investigates the engineering performance and CO2 footprint of mortar mixers by replacing Portland cement with 10%, 20%, 40% and 60% fly ash, a common industrial waste material. Samples of self-compacting mortar (SCM) were prepared with four different water/binder ratios and varying dosages of superplasticizer to give three ranges of workability, i.e., normal, high and self-compacting mortar mix. The engineering performance was assessed in term of compressive strength after designated curing periods for all mixes. CO2 footprint was the environmental impact indicator of each production stage. The optimum mix obtained was at 10% replacement rate for all mixes. Total production emission reduced by 56% when the fly ash replacement rate increased from 0% to 60% (maximum). This is translated to a reduction of 80% in eco-points (assuming that the energy consumption rate of production with 0% fly ash is at 100%). Such re-utilization is encouraged since it is able to reduce possible soil toxicity due to sulfur leaching by 5% to 27% and landfill area by 15% to 91% on average. PMID:28773465

  8. Sustainability, Eco-Point and Engineering Performance of Different Workability OPC Fly-Ash Mortar Mixes.

    PubMed

    Razi, Putri Zulaiha; Abdul Razak, Hashim; Khalid, Nur Hafizah A

    2016-05-06

    This study investigates the engineering performance and CO₂ footprint of mortar mixers by replacing Portland cement with 10%, 20%, 40% and 60% fly ash, a common industrial waste material. Samples of self-compacting mortar (SCM) were prepared with four different water/binder ratios and varying dosages of superplasticizer to give three ranges of workability, i.e., normal, high and self-compacting mortar mix. The engineering performance was assessed in term of compressive strength after designated curing periods for all mixes. CO₂ footprint was the environmental impact indicator of each production stage. The optimum mix obtained was at 10% replacement rate for all mixes. Total production emission reduced by 56% when the fly ash replacement rate increased from 0% to 60% (maximum). This is translated to a reduction of 80% in eco-points (assuming that the energy consumption rate of production with 0% fly ash is at 100%). Such re-utilization is encouraged since it is able to reduce possible soil toxicity due to sulfur leaching by 5% to 27% and landfill area by 15% to 91% on average.

  9. A Study on the Use of Mortar Utama Cement Type 420 as Concrete Admixture

    NASA Astrophysics Data System (ADS)

    Asrullah; Mulyadi, A.

    2017-06-01

    This research was conducted at laboratory scale in the form of experiment for the purpose to know the value of concrete strength by using Mortar Utama Cement Type 420 as concrete mixing additive. The concrete mixing method being used was SNI 03-2834-2000. The concrete quality being used was K 250, K 300 and K 350. Additions of Mortar Utama Cement were for 5%, 10%, 15% and 20% of cement weight. The strength was tested on the 3rd, 14th, 21st and 28th days of concrete making. According to the test result, it can be concluded that the highest strength of concrete for K 250 with 5% addition was 275.09 Kg/cm2, for K 300 with 5% addition was 325.32 kg/cm2, while for K 350 with 5% addition was 368.48 kg/cm2. Additions of Mortar Utama cement type 420 were able to influence the strength of concrete with simple linear regression model for K 250: Y = -2.005X + 272.7 with R2 = 0.757, for K 300: Y = -3.061X + 328.3 with R2 = 0.731, and for K 350:Y = -3.114X + 362.5 with R2 = 0.785.

  10. Effects of carbonation on the pore structure of non-hydraulic lime mortars

    SciTech Connect

    Lawrence, Robert M. . E-mail: mike@cc-w.co.uk; Mays, Timothy J.; Rigby, Sean P.; Walker, Peter; D'Ayala, Dina

    2007-07-15

    The pore structures of carbonated non-hydraulic lime mortars made with a range of different aggregates and concentrations of lime have been determined using mercury intrusion porosimetry (MIP). MIP data have been correlated with scanning electron microscopy images and other porosity data. During carbonation there is an increase in pore volume in the {approx} 0.1 {mu}m pore diameter range across all mortar types which is attributed to the transformation of portlandite to calcite. Also there is a monotonic increase in the volumes of pores with diameters below 0.03 {mu}m. A model is proposed for the changes in pore structure caused by carbonation. This attributes the increase in the volume of sub 0.03 {mu}m pores to the attachment of calcite crystals to the surface of aggregate particles, and in some cases to the surface of portlandite crystals. This phenomenon may explain the continuing presence of portlandite in mortars that, apparently, have fully carbonated.

  11. Biofouling on mortar mixed with steel slags in a laboratory biofilm reactor

    NASA Astrophysics Data System (ADS)

    Sano, K.; Masuda, T.; Kanematsu, H.; Yokoyama, S.; Hirai, N.; Ogawa, A.; Kougo, T.; Yamazaki, K.; Tanaka, T.

    2017-01-01

    The slag produced as by-product in steel-making processes is utilized for various purpose due to its special qualities. Bacteria or other microorganisms generally form the biofilm. They are formed at the interface between materials and water environment by the action of bacteria. Biofilm can cause various problems. Therefore, the control of biofilm formation is needed. In this study, we focused on the application of slag to marine environments and carried out a research on biofouling of mortars mixed with various iron/steel slags through marine immersion and laboratory scale experiments. In this research, we dealt with various mortars. In some cases, iron/steel slags were mixed into mortars. In the laboratory scale research, we observed biofilm formation at the surfaces of sample specimens. As for marine immersion, we carried out the field experiments in summer and winter. Both results were compared. As for laboratory scale experiment, the tap water and artificial sea-water were used. And after the immersion, the specimens were measured and observed by a low vacuum SEM-EDX and the anti-fouling properties were analyzed and discussed. From these results, we confirmed that the biofouling became remarkable with the dissolved iron. Therefore, biofilm formation can be controlled by the concentration of iron/steel slags.

  12. Strength and durability performance of alkali-activated rice husk ash geopolymer mortar.

    PubMed

    Kim, Yun Yong; Lee, Byung-Jae; Saraswathy, Velu; Kwon, Seung-Jun

    2014-01-01

    This paper describes the experimental investigation carried out to develop the geopolymer concrete based on alkali-activated rice husk ash (RHA) by sodium hydroxide with sodium silicate. Effect on method of curing and concentration of NaOH on compressive strength as well as the optimum mix proportion of geopolymer mortar was investigated. It is possible to achieve compressive strengths of 31 N/mm(2) and 45 N/mm(2), respectively for the 10 M alkali-activated geopolymer mortar after 7 and 28 days of casting when cured for 24 hours at 60°C. Results indicated that the increase in curing period and concentration of alkali activator increased the compressive strength. Durability studies were carried out in acid and sulfate media such as H2SO4, HCl, Na2SO4, and MgSO4 environments and found that geopolymer concrete showed very less weight loss when compared to steam-cured mortar specimens. In addition, fluorescent optical microscopy and X-ray diffraction (XRD) studies have shown the formation of new peaks and enhanced the polymerization reaction which is responsible for strength development and hence RHA has great potential as a substitute for ordinary Portland cement concrete.

  13. Visualizing and quantifying adhesive signals

    PubMed Central

    Sabouri-Ghomi, Mohsen; Wu, Yi; Hahn, Klaus; Danuser, Gaudenz

    2008-01-01

    Understanding the structural adaptation and signaling of adhesion sites in response to mechanical stimuli requires in situ characterization of the dynamic activation of a large number of adhesion components. Here, we review high resolution live cell imaging approaches to measure forces, assembly and interaction of adhesion components, and the activation of adhesion-mediated signals. We conclude by outlining computational multiplexing as a framework for the integration of these data into comprehensive models of adhesion signaling pathways. PMID:18586481

  14. Acoustic emission analysis: A test method for metal joints bonded by adhesives

    NASA Technical Reports Server (NTRS)

    Brockmann, W.; Fischer, T.

    1978-01-01

    Acoustic emission analysis is applied to study adhesive joints which had been subjected to mechanical and climatic stresses, taking into account conditions which make results applicable to adhesive joints used in aerospace technology. Specimens consisting of the alloy AlMgSi0.5 were used together with a phenolic resin adhesive, an epoxy resin modified with a polyamide, and an epoxy resin modified with a nitrile. Results show that the acoustic emission analysis provides valuable information concerning the behavior of adhesive joints under load and climatic stresses.

  15. Surface modification of an epoxy resin with polyamines and polydopamine: Adhesion toward electroless deposited copper

    NASA Astrophysics Data System (ADS)

    Schaubroeck, David; Mader, Lothar; Dubruel, Peter; Vanfleteren, Jan

    2015-10-01

    In this paper the influence of the epoxy roughness, surface modifications and ELD (electroless copper deposition) temperatures on the adhesive strength of the copper is studied. Good adhesion at low roughness values is targeted due to their applicability in high density electronic circuits. Roughened epoxy surfaces are modified with adsorbed polyamines, polydopamine and polyamines grafted to polydopamine. Next the, adhesive strength of ELD copper is determined with peel strength measurements and the interphases are examined with SEM (scanning electron microscopy). Polydopamine and polyamines grafted to polydopamine can lead to increased adhesive strength at lower roughness values compared to the non-modified samples at specific plating temperatures.

  16. Complement C3 participation in monocyte adhesion to different surfaces.

    PubMed Central

    McNally, A K; Anderson, J M

    1994-01-01

    As part of an ongoing investigation into the role of the monocyte/macrophage in biocompatibility, a major goal is to identify the adhesion mechanisms that initiate and promote the observed in vivo morphologic progression of monocyte-to-macrophage-to-foreign body giant cell on biomaterials. We have exploited differently modified polystyrenes, specific component-depleted sera, and monoclonal antibodies (mAbs) to leukocyte integrins to ask what adhesion mechanisms mediate human blood monocyte adhesion to different surfaces in vitro. Preliminary findings are that monocyte interactions with fluorinated, siliconized, nitrogenated, and oxygenated surfaces are reduced by 50-100% when complement component C3-depleted serum is used for adsorption; reductions vary with material surface properties. Adhesion is restored on all surfaces when C3-depleted serum is replenished with purified C3. Monocyte adhesion to serum-adsorbed surfaces is inhibited by mAbs to the leukocyte integrin beta subunit, CD18 (mAbs 60.3 and MHM23), and partially inhibited by a mAb to the alpha subunit, CD11b (mAb 60.1), suggesting adhesive interactions between adsorbed C3bi (the hemolytically inactive form of the C3b fragment) and the leukocyte integrin CD11b/CD18. However, adsorbed fibrinogen reduces the effectiveness of these mAbs, indicating that alternative adhesion mechanisms may operate depending on the propensities of critical adhesion-mediating components to be adsorbed onto different surfaces. Images PMID:7937848

  17. Flexibilized copolyimide adhesives

    NASA Technical Reports Server (NTRS)

    Progar, Donald J.; St.clair, Terry L.

    1988-01-01

    Two copolyimides, LARC-STPI and STPI-LARC-2, with flexible backbones were processed and characterized as adhesives. The processability and adhesive properties were compared to those of a commercially available form of LARC-TPI. Lap shear specimens were fabricated using adhesive tape prepared from each of the three polymers. Lap shear tests were performed at room temperature, 177 C, and 204 C before and after exposure to water-boil and to thermal aging at 204 C for up to 1000 hours. The three adhesive systems possess exceptional lap shear strengths at room temperature and elevated temperatures both before and after thermal exposure. LARC-STPI, because of its high glass transition temperature provided high lap shear strengths up to 260 C. After water-boil, LARC-TPI exhibited the highest lap shear strengths at room temperature and 177 C, whereas the LARC-STPI retained a higher percentage of its original strength when tested at 204 C. These flexible thermoplastic copolyimides show considerable potential as adhesives based on this study and because of the ease of preparation with low cost, commercially available materials.

  18. Platelet Adhesion under Flow

    PubMed Central

    Ruggeri, Zaverio M.

    2011-01-01

    Platelet adhesive mechanisms play a well-defined role in hemostasis and thrombosis, but evidence continues to emerge for a relevant contribution to other pathophysiological processes including inflammation, immune-mediated responses to microbial and viral pathogens, and cancer metastasis. Hemostasis and thrombosis are related aspects of the response to vascular injury, but the former protects from bleeding after trauma while the latter is a disease mechanism. In either situation, adhesive interactions mediated by specific membrane receptors support the initial attachment of single platelets to cellular and extracellular matrix constituents of the vessel wall and tissues. In the subsequent steps of thrombus growth and stabilization, adhesive interactions mediate platelet to platelet cohesion (aggregation) and anchoring to the fibrin clot. A key functional aspect of platelets is their ability to circulate in a quiescent state surveying the integrity of the inner vascular surface, coupled to a prompt reaction wherever alterations are detected. In many respects, therefore, platelet adhesion to vascular wall structures, to one another or to other blood cells are facets of the same fundamental biological process. The adaptation of platelet adhesive functions to the effects of blood flow is the main focus of this review. PMID:19191170

  19. Adhesion and wetting: Similarities and differences

    SciTech Connect

    Shanahan, M.E.R. )

    1991-10-01

    This article examines what is understood about adhesion and wetting both from the historical and scientific perspectives. Topics covered include mechanical adhesion, specific adhesion, chemical adhesion, adhesion by diffusion, the adsorption or wetting theory, bulk adhesion, the rheological theory, hysteresis effects in rubber adhesion, and hysteresis of wetting.

  20. Reduction of postoperative adhesion development.

    PubMed

    Diamond, Michael P

    2016-10-01

    Despite use of meticulous surgical techniques, and regardless of surgical access via laparotomy or laparoscopy, postoperative adhesions develop in the vast majority of women undergoing abdominopelvic surgery. Such adhesions represent not only adhesion reformation at sites of adhesiolysis, but also de novo adhesion formation at sites of surgical procedures. Application of antiadhesion adjuvants compliment the benefits of meticulous surgical techniques, providing an opportunity to further reduce postoperative adhesion development. Improved understanding of the pathophysiology of adhesion development and distinguishing variations in the molecular biologic mechanisms from adhesion-free peritoneal repair represent future opportunities to improve the reduction of postoperative adhesions. Optimization of the reduction of postoperative adhesions will likely require identification of unique, personalized approaches in each individual, representing interindividual variation in peritoneal repair processes. Copyright © 2016 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.