scholarly journals Going Out on a Limb: How Investigation of the Anoline Adhesive System Can Enhance Our Understanding of Fibrillar Adhesion

2019 ◽  
Vol 59 (1) ◽  
pp. 61-69 ◽  
Author(s):  
Austin M Garner ◽  
Michael C Wilson ◽  
Anthony P Russell ◽  
Ali Dhinojwala ◽  
Peter H Niewiarowski
Keyword(s):  
Materials Science ◽  
Adhesive System ◽  
Model Organisms ◽  
Adhesive Systems ◽  
Synthetic Adhesives ◽  
Adhesive Pads ◽  
And Performance ◽  
Fibril Morphology ◽  
Fibrillar Adhesion ◽  
Adhesive Performance

Abstract The remarkable ability of geckos to adhere to a wide-variety of surfaces has served as an inspiration for hundreds of studies spanning the disciplines of biomechanics, functional morphology, ecology, evolution, materials science, chemistry, and physics. The multifunctional properties (e.g., self-cleaning, controlled releasability, reversibility) and adhesive performance of the gekkotan adhesive system have motivated researchers to design and fabricate gecko-inspired synthetic adhesives of various materials and properties. However, many challenges remain in our attempts to replicate the properties and performance of this complex, hierarchical fibrillar adhesive system, stemming from fundamental, but unanswered, questions about how fibrillar adhesion operates. Such questions involve the role of fibril morphology in adhesive performance and how the gekkotan adhesive apparatus is utilized in nature. Similar fibrillar adhesive systems have, however, evolved independently in two other lineages of lizards (anoles and skinks) and potentially provide alternate avenues for addressing these fundamental questions. Anoles are the most promising group because they have been the subject of intensive ecological and evolutionary study for several decades, are highly speciose, and indeed are advocated as squamate model organisms. Surprisingly, however, comparatively little is known about the morphology, performance, and properties of their convergently-evolved adhesive arrays. Although many researchers consider the performance of the adhesive system of Anolis lizards to be less accomplished than its gekkotan counterpart, we argue here that Anolis lizards are prime candidates for exploring the fundamentals of fibrillar adhesion. Studying the less complex morphology of the anoline adhesive system has the potential to enhance our understanding of fibril morphology and its relationship to the multifunctional performance of fibrillar adhesive systems. Furthermore, the abundance of existing data on the ecology and evolution of anoles provides an excellent framework for testing hypotheses about the influence of habitat microstructure on the performance, behavior, and evolution of lizards with subdigital adhesive pads.

scholarly journals Stick or Slip: Adhesive Performance of Geckos and Gecko-Inspired Synthetics in Wet Environments

2019 ◽  
Vol 59 (1) ◽  
pp. 214-226 ◽  
Author(s):  
Alyssa Y Stark ◽  
Christopher T Mitchell
Keyword(s):  
Adhesive System ◽  
Natural System ◽  
Contact Structures ◽  
Principal Mechanism ◽  
Synthetic Adhesives ◽  
Decision Making Behavior ◽  
The Tropics ◽  
Gecko Adhesion ◽  
Adhesive Performance

Abstract The gecko adhesive system has inspired hundreds of synthetic mimics principally focused on replicating the strong, reversible, and versatile properties of the natural system. For geckos native to the tropics, versatility includes the need to remain attached to substrates that become wet from high humidity and frequent rain. Paradoxically, van der Waals forces, the principal mechanism responsible for gecko adhesion, reduce to zero when two contacting surfaces separate even slightly by entrapped water layers. A series of laboratory studies show that instead of slipping, geckos maintain and even improve their adhesive performance in many wet conditions (i.e., on wet hydrophobic substrates, on humid substrates held at low temperatures). The mechanism for this is not fully clarified, and likely ranges in scale from the chemical and material properties of the gecko’s contact structures called setae (e.g., setae soften and change surface confirmation when exposed to water), to their locomotor biomechanics and decision-making behavior when encountering water on a substrate in their natural environment (e.g., some geckos tend to run faster and stop more frequently on misted substrates than dry). Current work has also focused on applying results from the natural system to gecko-inspired synthetic adhesives, improving their performance in wet conditions. Gecko-inspired synthetic adhesives have also provided a unique opportunity to test hypotheses about the natural system in semi-natural conditions replicated in the laboratory. Despite many detailed studies focused on the role of water and humidity on gecko and gecko-inspired synthetic adhesion, there remains several outstanding questions: (1) what, if any, role does capillary or capillary-like adhesion play on overall adhesive performance of geckos and gecko-inspired synthetics, (2) how do chemical and material changes at the surface and in the bulk of gecko setae and synthetic fibrils change when exposed to water, and what does this mean for adhesive performance, and (3) how much water do geckos encounter in their native environment, and what is their corresponding behavioral response? This review will detail what we know about gecko adhesion in wet environments, and outline the necessary next steps in biological and synthetic system investigations.

Paper 3: The Future of Packaging Adhesives

1966 ◽  
Vol 181 (5) ◽  
pp. 61-68 ◽  
Author(s):  
C. A. Smith
Keyword(s):  
High Speed ◽  
Adhesive System ◽  
Solid Content ◽  
Design Stage ◽  
Adhesive Systems ◽  
Joint Activities ◽  
Synthetic Materials ◽  
Cellulose Acetates ◽  
Synthetic Adhesives ◽  
Hot Melt

Varying requirements necessitate numerous assembly processes, although all need fluidity which is achieved by a solid being dissolved or dispensed in fluid, or melted. A common adhesive base is a polymer, and more general dispersions are based on polyvinyl acetates; but where speed of assembly and special surfaces are needed, hot melt adhesives are used. Starch pastes and dextrines being ‘natural’ aqueous adhesives are used mainly for bonding non-synthetic porous materials. With the development of cellulose acetates, plastics, polythene, etc., and the introduction of improved machinery, synthetic adhesives became necessary. In view of the fact that hot-melt application appears to be the norm for modern packaging, applications of this type only have been enlarged upon in this paper. As it is essential that adhesive be applied with minimum waste and at a speed regulated to the packaging line there are two main types of applicator, namely, the nozzle type which applies a continuous bead of cement on to a moving web of material and the wheel type which applies a line or pattern of adhesive on to intermittently passing articles by means of a rotating transfer wheel. To arrive at the monetary expenditure it is usual to estimate in terms of milage of seam inches of bond per pound or cost per package unit. Whereas the actual amount of hot melt purchased is usable as an adhesive because it is all solid (although it does yield varying milage), in liquid adhesives the solid content, expressed as a percentage of the total volume, can be quite low. A more important cost factor is the effect of the adhesive system on the production rate of the packaging line—greater efficiency and output offset slightly higher costs. Speed packaging by fully automatic cartoning machines has been introduced and there is a trend for the package to be built around the product, involving joint activities of converter, machinery manufacturer, and adhesive manufacturer all at the same time. This era necessitates high-speed packaging machines together with complete adhesive systems for bonding natural and synthetic materials at high speed. It can be concluded that future packaging adhesives must be fast-setting, have the ability to bond synthetic materials, be automatically fed and applied, be able to withstand exacting service conditions, and adhesive systems must be introduced at the design stage of a new package.

scholarly journals The same but different: setal arrays of anoles and geckos indicate alternative approaches to achieving similar adhesive effectiveness

2020 ◽  
Author(s):  
Austin M. Garner ◽  
Michael C. Wilson ◽  
Caitlin Wright ◽  
Anthony P. Russell ◽  
Peter H. Niewiarowski ◽  
...  
Keyword(s):  
Functional Morphology ◽  
Empirical Work ◽  
Field Configuration ◽  
Clinal Variation ◽  
Adhesive Systems ◽  
Adhesive Pads ◽  
The Difference ◽  
Biological Adhesive ◽  
Pattern Of Variation ◽  
Adhesive Performance

AbstractThe functional morphology of squamate fibrillar adhesive systems has been extensively investigated and has indirectly and directly influenced the design of synthetic counterparts. Not surprisingly, the structure and geometry of exemplar fibrils (setae) have been the subject of the bulk of the attention in such research, although variation in setal morphology along the length of subdigital adhesive pads has been implicated in the effective functioning of these systems. Adhesive setal field configuration has been described for several geckos, but that of the convergent Anolis lizards, comprised of morphologically simpler fibrils, remains largely unexplored. Here we examine setal morphology along the proximodistal axis of the digits of Anolis equestris and compare our findings to those for a model gecko, Gekko gecko. Consistent with previous work, we found that the setae of A. equestris are generally thinner, shorter, and present at higher densities than those of G. gecko and terminate in a single spatulate tip. Contrastingly, the setae of G. gecko are hierarchically branched in structure and carry hundreds of spatulate tips. Although the splitting of contacts into multiple smaller tips is predicted to increase the adhesive performance of a fiber compared to an unbranched one, we posited that the adhesive performance of G. gecko and A. equestris would be relatively similar when the configuration of the setal fields of each was accounted for. We found that, as in geckos, setal morphology of A. equestris follows a predictable pattern along the proximodistal axis of the pad, although there are several critical differences in the configuration of the setal fields of these two groups. Most notably, the pattern of variation in setal length of A. equestris is effectively opposite to that exhibited by G. gecko. This difference in clinal variation mirrors the difference in the direction in which the setal fields of anoles and geckos are peeled from the substrate, consistent with the hypothesis that biomechanical factors are the chief determinants of these patterns of variation. Future empirical work, however, is needed to validate this. Our findings introduce Anolis lizards as an additional source of inspiration for bio-inspired design and set the stage for comparative studies investigating the functional morphology of these convergent adhesive apparatuses. Such investigations will lead to an enhanced understanding of the interactions between form, function, and environment of fibril-based biological adhesive systems.

Innovative Adhesive Systems for Dental Giomer Restorations

2018 ◽  
Vol 69 (10) ◽  
Author(s):  
Ioana Hodisan ◽  
Cristina Prejmerean ◽  
Tinca Buruiana ◽  
Doina Prodan ◽  
Loredana Colceriu ◽  
...  
Keyword(s):  
Acrylic Acid ◽  
Itaconic Acid ◽  
Adhesive System ◽  
Adhesive Systems ◽  
Substantial Agreement ◽  
Dye Penetration ◽  
Strong Adhesion ◽  
Innovative Materials ◽  
Dental Applications

The aim of this work was to reduce microleakage in giomer restorations by using innovative materials in both adhesive systems and light-cured dental giomer. Two adhesive systems with different primers were investigated. The innovative compounds in the primers were acrylic acid (AA)/itaconic acid (IA) copolymer modified with methacrylic groups and AA/IA/N-acryloyl-L-leucine copolymer grafted with methacrylic groups. In addition, the investigated new giomer G contains a pre-reacted glass based on the latter copolymer. The commercial Beautifil II giomer and the FL-Bond II adhesive system were used for comparison. Microleakage was evaluated by determining the scores and percentages of dye penetration lengths after thermocycling of a series of light-cured dental giomer restorations performed on 42 premolars extracted for orthodontic reasons. A lower microleakage value was recorded for the adhesive system containing the AA/IA/N-acryloyl-L-leucine copolymer grafted with methacrylic groups than for the commercial adhesive, which was in substantial agreement with SEM and AFM investigations. In this case, remarkable dentin sealing and a strong adhesion at the giomer restoration�tooth interface was observed, and the innovative adhesive was proven to be promising for dental applications.

The Effectiveness of Multimedia and Activity-Based Supplemental Teaching Resources in Materials Science Education

2012 ◽  
Vol 1472 ◽  
Author(s):  
Deborah A. Day ◽  
Eeman Abbasi ◽  
Brian Liang ◽  
Satish Bhat ◽  
Scott DeMeo ◽  
...  
Keyword(s):  
Science Education ◽  
Teaching Methods ◽  
Materials Science ◽  
Teaching Resources ◽  
Specific Content ◽  
9Th Grade ◽  
Digital Stories ◽  
Educational Videos ◽  
And Performance ◽  
Science Classes

ABSTRACTA comparative study investigating the integration of supplemental teaching resources in materials science education was developed for the purpose of determining the effectiveness of teaching strategies. Digital stories created by students, excerpts from the Nova Making Stuff documentaries, YouTube educational videos and student generated demo-kits were used as part of the investigation whereby two 9th grade science classes (n~26) were evaluated. Each participant in the study received one period (40-min) of a traditional lesson on Materials Science including specific content, vocabulary, and a pre- and post- lesson assessment. Additionally, the students in each class participated in a 30-min supplemental component, e.g. video or activity-based demonstration using aforementioned kits or video compilation. Pre- and post- evaluations (e.g. open-ended and likert questions) were administered to all of the participants. As hypothesized, the students’ feedback and performance on assessment activities reveal that the use of multimedia and activity-based resources may be equally effective teaching methods as traditional methods.

scholarly journals Hydropower, Geothermal, and Ocean Energy

MRS Bulletin ◽  
2008 ◽  
Vol 33 (4) ◽  
pp. 389-395 ◽  
Author(s):  
Ralph E.H. Sims
Keyword(s):  
Renewable Energy ◽  
Large Scale ◽  
New Technologies ◽  
Materials Science ◽  
Development Stage ◽  
Design Development ◽  
Ocean Energy ◽  
Improve Design ◽  
And Performance ◽  
Improve Reliability

AbstractSome forms of renewable energy have long contributed to electricity generation, whereas others are just emerging. For example, large-scale hydropower is a mature technology generating about 16% of global electricity, and many smaller scale systems are also being installed worldwide. Future opportunities to improve the technology are limited but include upgrading of existing plants to gain greater performance efficiencies and reduced maintenance. Geothermal energy, widely used for power generation and direct heat applications, is also mature, but new technologies could improve plant designs, extend their lifetimes, and improve reliability. By contrast, ocean energy is an emerging renewable energy technology. Design, development, and testing of a myriad of devices remain mainly in the research and development stage, with many opportunities for materials science to improve design and performance, reduce costly maintenance procedures, and extend plant operating lifetimes under the harsh marine environment.

Abstract 371: Down Regulation of ECM Genes Laminin and Collagen IV Lead to Preserved Cardiac Function With Age and Increased Lifespan in Drosophila

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Ayla O Sessions
Keyword(s):  
Diastolic Dysfunction ◽  
High Speed ◽  
Current Model ◽  
Collagen Iv ◽  
Model Systems ◽  
Model Organisms ◽  
Heart Tube ◽  
Ecm Remodeling ◽  
Intercalated Discs ◽  
And Performance

Increased deposition of extracellular matrix (ECM) is observed in all advanced age heart failure patients, but current model systems are complex and slow to age. To investigate the effect of extracellular remodeling on mechanical function in genetically tractable, rapidly aging, and simple model organisms, we employed Drosophila melanogaster, which has a simple trilayered heart tube. We found that two common wildtype strains of Drosophila, i.e. yellow-white (yw) and white-1118 (w1118), exhibit different cytoskeletal and ECM remodeling with age. Using a recently developed nanoindentation method to measure cardiomyocyte stiffness and high speed optical imaging to assess contractility of intact Drosophila hearts, we found that yw flies had stiffer intercalated discs (ICD) and exhibited diastolic dysfunction with age. On the other hand, w1118 flies had a shorter lifespan compared to yw, did not exhibit ICD stiffening, had a less severe diastolic dysfunction, and showed an increase in ECM layer thickness between ventral muscle (VM) and cardiomyocyte (CM) layers of the heart tube. To modulate ECM and assess its effect in the aged w1118 flies, we knocked-down ECM genes LamininA and Viking (homologous to Collagen IV). Both ECM KD genotypes exhibited diastolic dilation with increased fractional shortening at adult (1wk) and aged (5wk) time points. The LamininA KD resulted in decreased cardiomyocyte stiffness correlating with increased relaxation velocities in adult flies and preservation of shortening and relaxation velocities in aged flies over controls. However, both the LamininA and Collagen IV KD flies experienced a basal increase in the decoupling of their cardiomyocytes as determined by heart period variance and % fibrillar heart-beats. These conductance issues were not enough to counteract the increased cardiac output and performance with age, and the Collagen IV KD outlived controls by 1.5 weeks median survival and the LamininA KD by 3 weeks. This suggests that the cell-ECM contacts in the basement membrane are intimately tied not only to the coupling of the cardiomyocytes of the Drosophila heart tube but also to cytoskeletal remodeling, but perhaps different ECM proteins have different mechanisms for interacting with the cardiomyocyte cytoskeleton.

scholarly journals Quantitative evaluation of microleakage in class V cavities using one-bottle and self-etching adhesive systems

2004 ◽  
Vol 18 (3) ◽  
pp. 253-259 ◽  
Author(s):  
Fabiana Mantovani Gomes França ◽  
Flávio Henrique Baggio Aguiar ◽  
Alex José Souza dos Santos ◽  
José Roberto Lovadino
Keyword(s):  
Methylene Blue ◽  
In Vitro Study ◽  
Adhesive System ◽  
Acid Etching ◽  
Single Bond ◽  
Adhesive Systems ◽  
Class V ◽  
Bonding System ◽  
Root Dentin

The aim of this in vitro study was to evaluate quantitatively the microleakage in class V cavities restored with one-bottle and self-etching adhesive systems with and without previous acid etching. Two one-bottle adhesive systems (Single Bond and Prime & Bond 2.1) and one self-etching adhesive system (Clearfil Mega Bond) were used in this study. One hundred and twenty sound human premolar teeth were randomly divided into 6 groups, and 20 class V restorations were prepared in the root dentin to test each bonding system. Each bonding system was used with and without acid etching. Specimens were prepared, dyed with 2% methylene blue, sectioned, triturated, and evaluated with an absorbance spectrophotometer test in order to quantify the infiltrated dye. Results were statistically evaluated by ANOVA and Tukey-Kramer test. No statistically significant differences were found among the adhesive systems when no etching agent was used. However, the Single Bond adhesive system showed statistically significant lower microleakage means than Clearfil Mega Bond and Prime & Bond 2.1 when 37% phosphoric acid was used. Single Bond and Clearfil Mega Bond adhesive systems presented similar behavior when the manufacturers' instructions were followed.

scholarly journals Morphology and thickness of the diffusion of resin through demineralized or unconditioned dentinal matrix

2002 ◽  
Vol 16 (2) ◽  
pp. 115-120 ◽  
Author(s):  
César Augusto Galvão Arrais ◽  
Marcelo Giannini
Keyword(s):  
Adhesive System ◽  
Adhesive Systems ◽  
Hybrid Layer ◽  
Human Teeth ◽  
Bonding Agents ◽  
Mean Values ◽  
Dentin Bonding ◽  
Occlusal Surfaces ◽  
The One ◽  
Bonding Systems

The formation of a hybrid layer is the main bonding mechanism of current dentin-bonding systems. This study evaluated the morphology and thickness of the resin-infiltrated dentinal layer after the application of adhesive systems. The dentin-bonding agents were evaluated on flat dentinal preparations confected on the occlusal surfaces of human teeth. The test specimens were prepared and inspected under scanning electron microscopy at a magnification of X 2,000. The adhesive systems were responsible for different hybrid layer thicknesses (p < 0.05), and the mean values were: for Scotchbond MP Plus (SM), 7.41 ± 1.24mum; for Single Bond (SB), 5.55 ± 0.82mum; for Etch & Prime 3.0 (EP), 3.86 ± 1.17mum; and for Clearfil SE Bond (CB), 1.22 ± 0.45mum. The results suggest that the conventional three-step adhesive system (SM) was responsible for the thickest hybrid layer, followed by the one-bottle adhesive (SB). The self-etching adhesives, EP and CB, produced the formation of the thinnest hybrid layers.

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