Controlling the layout of elasticity in materials provides new opportunities for generating various functionalities such as shape-morphing capability, large stretchability, and elastic softening for aeronautics, drug delivery, soft robotics, and stretchable electronics applications. Recently, techniques building upon kirigami principles, the Japanese art of paper cutting, have been considered an effective strategy to control stiffness and deformation of materials by systemically integrating cut patterns into inextensible sheets. The performance of kirigami-inspired materials relies primarily on geometric features defined by cut patterns rather than chemistry of constituents, which can enable high compatibility with diverse material sets across a wide range of length scales. However, kirigami has been relatively unexplored to control adhesion and current challenges such as the intrinsic trade-off between high deformability and load-bearing capacity limits applications that require large shape change and structural strength. This thesis demonstrates that the kirigami approach is a powerful tool to control interfacial properties of adhesive films, and that composite approaches in kirigami-inspired material can overcome the deformation-strength trade-off. The kirigami principle is applied to adhesives to control adhesion through arrays of linear cut patterns (Chapter 2). The spatial layout of elasticity in the kirigami-inspired adhesive enhances adhesion over homogeneous adhesive systems and generates anisotropic adhesion. The utility of the proposed adhesive design criteria is further extended to complex non-linear cut patterns (Chapter 3). These non-linear patterns significantly enhance adhesion relative to linear patterns in adhesives and unpatterned films, while also enabling easy release and spatial control of adhesion across a sheet. The enhancement enabled by cut geometry remains effective in diverse adhesives, on various surfaces, and in wet and dry conditions. The adhesion dependence on cut geometry is further investigated to understand how arrays of sub-patterns adjacent to primary non-linear patterns affect adhesion performance (Chapter 4). Kirigami composites are also developed to overcome the trade-off between large deformability and load-bearing capacity (Chapter 5). A composite architecture is developed consisting of low melting point metal alloys incorporated into patterned elastomeric layers. This composite approach shows the ability to rapidly morph into complex, load-bearing shapes, while achieving reversibility and self-healing capability through phase change driven by embedded heaters. The utility of the multi-functional composite is demonstrated through a multimodal morphing drone which transforms from a ground to air vehicle and an underwater morphing machine which can be reversibly deployed to collect cargo. This thesis is then summarized by discussing key findings, contributions, and future perspectives (Chapter 6). / Doctor of Philosophy / Controlling stiffness across a material sheet provides new opportunities for emerging fields such as soft robotics and stretchable electronics. Recently, a technique based on kirigami principles, the Japanese art of paper cutting, has gained interest as an effective strategy for designing materials. This kirigami technique provides intriguing possibilities to create tunable and highly functional materials by adding cuts (e.g. controlling material geometry) without changing chemistry. This kirigami technique is also compatible with diverse materials from extremely small (e.g. nanoscale) to large scales (e.g. over millimeters to even beyond). However, engineered kirigami has been mostly used for creating deformable electronics and stretchable films. Further, although it makes the material soft and stretchable, it can reduce load-bearing capacity and strength. In this thesis, kirigami is utilized to engineer adhesives with unique properties and create multi-functional morphing materials that overcome extensibility-loading-bearing trade-offs. Inspired by the kirigami concept, an array of linear cut patterns is integrated into an adhesive strip, and adhesion is measured (Chapter 2). The kirigami adhesive shows stronger adhesion over an unpatterned adhesive, and it also shows high adhesion in one direction but low adhesion in the other direction. The utility of the adhesive design criteria is then extended to complex non-linear cut patterns (Chapter 3). This enables enhanced adhesion, easy release, spatial control of adhesion, and rapidly customized adhesive properties through a digital fabrication approach. The adhesion is strongly controlled by the cut size and density, thus this kirigami technique is applicable to diverse adhesives, on various surfaces, and in wet and dry conditions. The effects of non-linear patterns on adhesion are studied in further detail (Chapter 4). Diverse arrays of sub-patterns around original non-linear patterns are demonstrated to control the adhesion performance. Following the adhesion work in previous chapters, shape-changing materials are studied. Here, a kirigami approach is used to develop multi-functional, morphing composites (Chapter 5). The composite shows the ability to change into complex shapes while support loads through hard metal alloys and kirigami-inspired soft encapsulating layers, while achieving reversibility and self-healing capability through the phase change between solid and liquid states by an embedded heater. The utility of the multi-functional composite is demonstrated through a morphing drone which transforms from a ground to air vehicle and an underwater morphing machine which can be reversibly deployed to collect cargo. This thesis is then summarized by discussing key findings, contributions, and future perspectives (Chapter 6).

Loblolly pine (Pinus taeda L) is the leading Southern (USA) pine, in terms of acres planted (Fortson et al.,1996). Since commercial forest acreage is predicted to remain fairly constant over the next 50 years, productivity must be increased if the South is going to meet a larger share of the nation'­s timber supply needs (Gjerstad and Barber, 1987). Hardwoods have been shown to have a consistent negative growth impact on pines, and uncontrolled hardwoods continue to compete aggressively with pines throughout a rotation, especially when hardwoods remain in the pine canopy. Competing vegetation can be efficiently controlled by herbicides, which need to be formulated either in-can or in-tank to allow them to perform optimally. Adjuvants have proven essential to increasing the efficacy of herbicides, due to their ability to consistently improve the performance of the basic pesticide product. There are, broadly speaking, two routes by which adjuvants can do this. The first is the minimization of off target deposition and second, by the maximization of the herbicidal effect once it is placed on the target ( Reeves, 1989). The major contributors to off- target deposition and retention are drift, in-flight volatilization, droplet shatter, bounce or runoff, washoff, and removal by wind. These losses result in pesticides never reaching the target or achieving only transitory deposition. There are two basic methods of maximizing the effect of the pesticide once it is on the target. The first is to improve coverage by the spray solution, which can be accomplished by lowering the surface tension of the spray with surfactant materials. The second is by improving the penetration or uptake into the target. Organosilicone surfactants can reduce the surface tension of aqueous pesticides far below that which is possible with nonsilicone surfactants, resulting in efficient wetting of even the most hydrophobic leaf surfaces. Additionally, by virtue of their low surface tension, these adjuvants can significantly increase the uptake of active chemicals directly into the plant via stomatal infiltration ( Stevens et al., 1991). Triclopyr ([(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid) has been found to be an effective herbicide for hardwood control. Its two commercial formulations, a triethylamine (TEA) salt (Garlon 3A) and a butoxyethyl ester ( Garlon 4 ), vary considerably in their acceptability. The current ester formulation has two undesirable characteristics. One is that all ester formulations, regardless of chain length, have some volatility which is usually more than that of water-soluble salts. The second is that the current ester formulation utilizes a kerosene solvent which is known to cause rapid foliar necrosis (possibly inhibiting herbicide translocation) and is a suspected carcinogen ( Zedaker et al., 1995). In most applications, the ester formulation has been more efficacious than the amine formulation on both an equal active ingredient basis and on an equal cost basis. Research had demonstrated a potential to enhance the uptake of triclopyr through the use of organosilicones; however, significant problems still existed. It was found that the commercial TEA formulation of triclopyr (Garlon 3A) was "antagonistic" to the organosilicone surfactant Silwet L-77. To take full advantage of the properties of organosilicones, the antagonistic co-formulants of Garlon 3A needed to be removed or replaced, the best surfactant formulation identified, and a cost-effective concentration of the surfactant(s) needed to be found. To do this adequately required that both physico-chemical processes and biological processes be studied. The relevant physico-chemical processes involved in a formulation's effect on spray impaction on the target plant include adhesion, reflection, retention and run-off. The important biological processes include the uptake and translocation of the herbicide into the plant. The objectives of this study were: to evaluate the influence of formulation, active ingredient concentration, droplet size and leaf surface (adaxial vs. abaxial) on contact phytotoxicity, adhesion and retention to Acer rubrum, Liquidambar styraciflua and Quercus rubra by triclopyr formulations containing organosilicone surfactants and mixtures of silicone plus conventional surfactants. The adhesion and retention studies also evaluated the influence of leaf angle. Further objectives were to evaluate the influence of formulation and active ingredient concentration on spray retention by the adaxial and abaxial leaf surface of the selected species under field and track-sprayer conditions and to determine whether leaf characteristics (wax character and leaf angle ) could explain adhesion / retention. Garlon 4, Garlon 3A and Triclopyr TEA + sequestrant (each at 0.32%, 1.6% and 3.2% ae) plus various concentrations of the surfactants Polyglycol 26-2, Rhodasurf DA-630, Surfadone LP-100, Silwet L-77 and Silwet 408, were tested for contact phytotoxicity, adhesion and retention on the adaxial and abaxial leaf surfaces of sweetgum, red oak and red maple. Little or no contact phytotoxicity was observed with any formulation applied to the adaxial surface within 6 hours; some phytotoxicity was noted within 24 hours. Abaxial surface treatments showed much greater contact phytotoxicity. Contact phytotoxicity was caused by (1) increasing concentrations of stock triclopyr products, and (2) the influence of the organosilicone surfactants. However, these results were very species dependent. Conclusions made from the contact phytotoxicity study were: if the droplet size becomes too big, then efficacy will be reduced; increasing the concentration of active ingredient above a certain limit will not increase efficacy, and may in fact reduce it; the addition of the organosilicone surfactants Silwet L-77 and Silwet 408 delayed and reduced phytotoxicity in red oak ( the most susceptible species to contact phytotoxicity), and to a lesser extent in red maple, but increased the rate in sweetgum. Major influences on adhesion were: droplet size ( increasing droplet size decreased adhesion); adaxial/abaxial leaf surface (abaxial adhesion less than adaxial); product concentration (increasing product concentration increased adhesion); leaf angle (increasing leaf angle decreased adhesion); and addition of surfactants (variable adhesion). All new formulations gave greater adhesion than the commercial formulations, with Triclopyr TEA plus sequestrant plus n-octyl pyrrolidone plus Silwet 408 giving, overall, the greatest adhesion. Increasing product concentration gave greater adhesion. Increasing droplet size and angle of impact reduced adhesion. The adaxial leaf surface showed higher adhesion than the abaxial leaf surface. Adhesion was higher on sweetgum, followed by red oak, with red maple being the most difficult species to get formulations to adhere to. Whereas increasing product concentration improves adhesion, the lowest contact phytotoxicity result would be from lowering product concentration. Looking at both sets of results, the best product concentration of those studied would then be 1.6% ae as this can provide high adhesion, while still enabling us to choose a formulation which gives minimal contact phytotoxicity. In the laboratory, formulation had no significant effect on retention. However, there are other considerations which affect retention that need to be kept in mind. It was observed that droplets containing organosilicone could impact an already wetted surface and still adhere or be retained, whereas those droplets not containing any organosilicone surfactant would bounce quite a distance on impact with a pre-wetted surface. Impaction with an already wetted surface was not part of this study, and therefore was not studied quantitatively. Also, formulations containing organosilicone surfactants provide greater "wrap-around" to the lower surface ( Forster and Zabkiewicz, 1998), which is of great benefit when stomata are only on the abaxial surface, as is the case with these species. Concentration and leaf angle also had no significant effect on retention. Droplet size was significant, with retention decreasing with increasing droplet size. Retention by the adaxial surface was significantly higher than retention by the abaxial surface. There was no significant difference overall between sweetgum and red oak, but retention by red maple was significantly lower. Spray retention by the adaxial and abaxial leaf surfaces of the three tree species was also characterized in a field experiment conducted on a right of way site in North Anna, Virginia, USA. Amine ( Garlon 3A) formulations of triclopyr combined with Silwet 408, and the commercial triclopyr ester formulation, Garlon 4, were applied using a Radiarc sprayer equipped with 0.508 mm nozzles (approx. 1000 um droplets) applying 140 l/ha. The addition of the organosilicone surfactant Silwet 408 to the amine formulation gave the same total deposition as the commercial ester formulation, Garlon 4, while enhancing the abaxial retention as a percentage of total deposition. Thus the addition of organosilicone surfactant may have the ability to enhance herbicide uptake via the abaxial leaf surface, and therefore enhance efficacy. Field trial results showed that the alcohol ethoxylate, DA6, is not an essential component of the triclopyr amine / Silwet 408 formulation, in terms of retention. The field trial application was also simulated on sweetgum, using a track-sprayer at the NZ Forest Research Institute Ltd. As in the field trial, the addition of Silwet 408 to triclopyr amine greatly enhanced abaxial retention as a percentage of total deposition, compared to that of Garlon 4. However, the track-sprayer results were very different from the field results, with amounts of adaxial and abaxial retention and total deposition much lower. In agreement with published literature, it was found that the micro-roughness of the leaf surface can be used as a guide to explain adhesion results. The difference among trees in terms of leaf angles appeared to be much less important in explaining retention. / Master of Science

Integrin recycling has been generally assumed to be important for cell migration but the trafficking pathways and the molecules regulating integrin trafficking remain poorly characterized. Furthermore, little is known about the activation status of endocytosed integrins and how it affects the recycling of these receptors. It is likely that FA-engaged integrins will follow different trafficking pathways than bulk integrins and here I sought to study the endocytic fate of this particular integrin pool using the MT-induced FA disassembly assay. I found that integrins previously resident at FAs travel through different Rab compartments after FA disassembly and that their return to the plasma membrane is Rab11- and Src-dependent. Strikingly, I unveiled new functions for FAK and Src family kinases in this process by showing that these kinases are critical to keep integrins active during endocytic trafficking. This finding is unprecedented since it was not known whether endocytosed integrins were kept active during their trafficking. Interestingly, reassembly of FAs from endocytosed integrin occurred preferentially at the leading edge of migrating cells suggesting that integrins are trafficked in a polarized fashion. Furthermore, the recycling of integrins from the Rab11-positive compartment to the plasma membrane is a long-range transport implying the existence of a MT motor committed to this task. Consistently, I identified that a kinesin-II motor, Kif3AC, is engaged in this process. My work establishes a FAK- and Src family kinases-based mechanism for integrin "adhesion memory" during endocytic trafficking and identifies a direct link between FA disassembly and reassembly through an endocytic recycling pathway involving Rab5 and Rab11 and a kinesin-II family member.

Abstract not available

Thesis (Ph. D. in Cancer Biology)--Vanderbilt University, May 2007. / Title from title screen. Includes bibliographical references.

Cell adhesion to extracellular matrices (ECM) is essential to numerous physiological and pathological processes. Cell adhesion is initiated by binding of the transmembrane integrin family of receptors to an ECM ligand such as fibronectin (FN). Once bound, integrins cluster together and form focal adhesions (FA). FAs serve as structural links and signal transduction elements between the cell and its extracellular environment. While a great deal of progress has been made in identifying the biochemical components that comprise focal adhesions and the roles they play in migration, cell spreading, and signaling, the contributions of these proteins to mechanical interactions between the cell and its environment remain poorly understood. A FA adhesion protein of particular importance is vinculin. When localized to focal adhesions, vinculin forms a ternary complex with talin and 1-integrin. This 1-integrin-talin-vinculin complex plays a central role in the regulation of FA assembly and cell spreading and migration. Nevertheless, the specific contribution to adhesive force generation of the 1-integrin-talin-vinculin complex remains poorly understood. The objective of this project was to analyze the role of vinculin in the cell adhesion strengthening process. Our central hypothesis is that vinculin modulates adhesion strength via regulating the size and/or composition of the integrin-talin-vinculin complex. We used a novel combination of biochemical reagents and engineering techniques along with quantitative and sensitive adhesion strength measurements to provide new insights into how the structure of vinculin contributes to cell adhesion strength.

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 5 uppsatser.

Thesis (Ph. D.)--Ohio State University, 2007.

Orientador: Mônica Barbosa de Melo / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-20T09:58:06Z (GMT). No. of bitstreams: 1 Cruz_PedroRodriguesSousada_M.pdf: 4934964 bytes, checksum: 906273ac9e66e4d8efa634ae942458bf (MD5) Previous issue date: 2012 / Resumo: As doenças falciformes são...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: Sickle cell diseases are...Note: The complete abstract is available with the full electronic document / Mestrado / Genetica Animal e Evolução / Mestre em Genética e Biologia Molecular

Cell adhesion to the extracellular matrix is mediated by the integrin family of adhesion receptors. Integrin receptor engagement initiates the formation of multimolecular protein complexes, termed integrin adhesion complexes (IACs), at the cell membrane. IACs are complex signalling hubs that are enriched in tyrosine-based phosphorylation events and form a mechanochemical connection between integrin receptors and the actin cytoskeleton. Dysregulation of individual IAC components has been reported to influence a wide range of biological processes that contribute to disease. Literature-curated and proteomic analyses of IACs have revealed an unanticipated molecular complexity of IACs in a variety of experimental contexts; however, a global consensus view of the composition of IACs, and a description of how the complex network of interactions in IACs influences global cell function, is currently lacking. Here, multiple existing and new proteomic datasets detailing the protein composition of IACs were analysed to identify a systems-level description of IACs and to enable interrogation of IAC structure, topology and dynamics. Quantitative IAC proteomes derived from multiple cell types were integrated to generate a 2,412-protein ‘meta-adhesome’ database of proteins enriched to fibronectin-induced IACs. To investigate the putative functional adhesion landscape in an objective manner, the meta-adhesome was analysed using a combination of hierarchical clustering, gene ontology and interaction network analyses. An emergent property of the meta-adhesome was the definition of a consensus adhesome: 60 proteins commonly identified from IAC datasets that likely represent an IAC protein core composition. The consensus adhesome highlights how integrins connect to actin via multiple pathways and consists of both canonical and underappreciated IAC components. To investigate the robustness of the IAC network, the effects of pharmacological perturbation of the key IAC kinases FAK and Src on IACs were examined. FAK activity was inhibited with the small molecule inhibitor AZ13256675, and mass spectrometry-based protein quantification revealed that IAC protein composition was unaffected upon FAK inhibition. Moreover, IAC composition was also insensitive to Src inhibition using AZD0530 and to simultaneous FAK and Src inhibition. In contrast, phosphorylation of IAC components, cell migration and cell proliferation were reduced upon FAK and/or Src inhibition. These data suggest that IAC protein composition is robust to perturbation of key kinases, while flux of signals propagated through IACs via phosphorylation is kinase dependent. To examine IAC dynamics, the composition of IACs during IAC assembly and IAC disassembly were examined in the context of the meta-adhesome and consensus adhesome using IAC proteomic datasets. These analyses revealed the temporal dynamics of specific functional protein modules at IACs and detailed the compositional dynamics of the core cell adhesion machinery. In summary, these studies describe both a systems-level and a reductionist view of the IAC proteome, investigate the effects of kinase inhibition on IAC composition and chart IAC dynamics during their assembly and disassembly. These data demonstrate the usefulness of the meta-adhesome and consensus adhesome for future analyses of IAC proteomes.