The Experts below are selected from a list of 8291988 Experts worldwide ranked by ideXlab platform
Paul D. Beer - One of the best experts on this subject based on the ideXlab platform.
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a halogen bonding bis triazolium rotaxane for halide selective anion recognition
Chemistry: A European Journal, 2015Co-Authors: Benjamin R Mullaney, Benjamin E Partridge, Paul D. BeerAbstract:A systematic study on the anion-binding properties of acyclic halogen- and hydrogen-bonding bis-triazolium carbazole receptors is described. The halide-binding potency of halogen-bonding bis-iodotriazolium carbazole receptors was found to be far superior to their hydrogen-bonding bis-triazolium-based analogues. This led to the synthesis of a mixed halogen- and hydrogen-bonding rotaxane host containing a bis-iodotriazolium carbazole axle component. The rotaxane's anion recognition properties, determined by (1)H NMR titration experiments in a competitive aqueous solvent mixture, demonstrated the preorganised halogen-bonding interlocked host cavity to be halide-selective, with a strong binding affinity for bromide.
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Halogen bonding in water results in enhanced anion recognition in acyclic and rotaxane hosts
Nature Chemistry, 2014Co-Authors: Matthew J. Langton, Sean W. Robinson, Igor Marques, Vítor Félix, Paul D. BeerAbstract:Halogen bonding (XB), the attractive interaction between an electron-deficient halogen atom and a Lewis base, has undergone a dramatic development as an intermolecular force analogous to hydrogen bonding (HB). However, its utilization in the solution phase remains underdeveloped. Furthermore, the design of receptors capable of strong and selective recognition of anions in water remains a significant challenge. Here we demonstrate the superiority of halogen bonding over hydrogen bonding for strong anion binding in water, to the extent that halide recognition by a simple acyclic mono-charged receptor is achievable. Quantification of iodide binding by rotaxane hosts reveals the strong binding by the XB-rotaxane is driven exclusively by favourable enthalpic contributions arising from the halogen-bonding interactions, whereas weaker association with the HB-rotaxanes is entropically driven. These observations demonstrate the unique nature of halogen bonding in water as a strong alternative interaction to the ubiquitous hydrogen bonding in molecular recognition and assembly. The ability to achieve strong molecular recognition in water is a key challenge for supramolecular chemistry. Now, halogen bonding — the attractive interaction between an electron-deficient halogen atom and a Lewis base — has been shown to be superior to hydrogen bonding for strong anion binding in water. Ripple image: © PhotoDisc/Getty Images.
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iodide induced shuttling of a halogen and hydrogen bonding two station rotaxane
Angewandte Chemie, 2014Co-Authors: Antonio Caballero, Laura Swan, Fabiola Zapata, Paul D. BeerAbstract:The first example of utilizing halogen-bonding anion recognition to facilitate molecular motion in an interlocked structure is described. A halogen-bonding and hydrogen-bonding bistable rotaxane is prepared and demonstrated to undergo shuttling of the macrocycle component from the hydrogen-bonding station to the halogen-bonding station upon iodide recognition. In contrast, chloride-anion binding reinforces the macrocycle to reside at the hydrogen-bonding station.
Masahiro Yamamoto - One of the best experts on this subject based on the ideXlab platform.
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Study on Patch Bonding for Recovery of Damaged Carbon Fiber Reinforced Thermoplastics Subjected to Four-Point Bending Load
Journal of Materials Science Research, 2013Co-Authors: Kiyotaka Obunai, Rei Yamagishi, Koichi Ozaki, Tadao Fukuta, Masahiro YamamotoAbstract:The purpose of this study is to investigate the fracture behavior and repairability of carbon fiber reinforced thermoplastics (CFRTP). At first, four-point bending tests were conducted to characterize the bending characteristics of fabricated CFRTP. The test results show that local delamination first appeared when the applied bending strain was 2.0%. When the bending strain reached 2.5%, the failure of the fiber due to local buckling was observed at the compression side of the specimen. Secondly, the effect of patch bonding on the bending strength and flexural modulus was also evaluated. Test results showed that damaged specimen could be repaired by bonding of an appropriate patch layer. Patch bonding at the compression side was more effective than at the tension side. The flexural modulus of a repaired specimen was estimated by the laminate beam model.
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Study on Patch Bonding for Recovery of Damaged Carbon Fiber Reinforced Thermoplastics by Four-Point Bending Method
2013Co-Authors: Kiyotaka Obunai, Rei Yamagishi, Koichi Ozaki, Tadao Fukuta, Masahiro YamamotoAbstract:The purpose of this study is to investigate the fracture behavior and repairability of carbon fiber reinforced thermoplastics (CFRTP). At first, four-point bending tests were conducted to characterize the bending characteristics of fabricated CFRTP. The test results show that local delamination first appeared when the applied bending strain was 2.0%. When the bending strain reached 2.5%, the failure of the fiber due to local buckling was observed at the compression side of the specimen. Secondly, the effect of patch bonding on the bending strength and flexural modulus was also evaluated. Test results showed that damaged specimen could be repaired by bonding of an appropriate patch layer. Patch bonding at the compression side was more effective than at the tension side. The flexural modulus of a repaired specimen was estimated by the laminate beam model.
J. Quiñones - One of the best experts on this subject based on the ideXlab platform.
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Diffusion bonding of alumina to steel using soft copper interlayer
Journal of Materials Science, 1992Co-Authors: A. Ureña, J. M. Gómez Salazar, J. QuiñonesAbstract:The diffusion bonding of a low steel to alumina has been studied in the present work. Thin foils of a soft metal (copper) were used to reduce the effects of the residual stresses produced in the joint by thermal expansion mismatch. The strength of the joint was found to be influenced by the bonding parameters, but principally by the oxygen content both on the surface and in the copper matrix. The diffusion bonds have been mechanically tested using a three-point bending test. Maximum bending strengths of 100 MPa were achieved by using a 0.1 mm copper foil, and bonding in a oxidizing atmosphere ( P _O _2=10_4Pa). SEM and EDS investigations have shown the presence of reaction products in the copper-alumina interface which controls the mechanical properties of the joint.
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Diffusion bonding of alumina to steel using soft copper interlayer
Journal of Materials Science, 1992Co-Authors: A. Ureña, J. M. Gómez Salazar, J. QuiñonesAbstract:The diffusion bonding of a low steel to alumina has been studied in the present work. Thin foils of a soft metal (copper) were used to reduce the effects of the residual stresses produced in the joint by thermal expansion mismatch. The strength of the joint was found to be influenced by the bonding parameters, but principally by the oxygen content both on the surface and in the copper matrix. The diffusion bonds have been mechanically tested using a three-point bending test. Maximum bending strengths of 100 MPa were achieved by using a 0.1 mm copper foil, and bonding in a oxidizing atmosphere ( P _O _2=10_4Pa). SEM and EDS investigations have shown the presence of reaction products in the copper-alumina interface which controls the mechanical properties of the joint.
Kiyotaka Obunai - One of the best experts on this subject based on the ideXlab platform.
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Study on Patch Bonding for Recovery of Damaged Carbon Fiber Reinforced Thermoplastics Subjected to Four-Point Bending Load
Journal of Materials Science Research, 2013Co-Authors: Kiyotaka Obunai, Rei Yamagishi, Koichi Ozaki, Tadao Fukuta, Masahiro YamamotoAbstract:The purpose of this study is to investigate the fracture behavior and repairability of carbon fiber reinforced thermoplastics (CFRTP). At first, four-point bending tests were conducted to characterize the bending characteristics of fabricated CFRTP. The test results show that local delamination first appeared when the applied bending strain was 2.0%. When the bending strain reached 2.5%, the failure of the fiber due to local buckling was observed at the compression side of the specimen. Secondly, the effect of patch bonding on the bending strength and flexural modulus was also evaluated. Test results showed that damaged specimen could be repaired by bonding of an appropriate patch layer. Patch bonding at the compression side was more effective than at the tension side. The flexural modulus of a repaired specimen was estimated by the laminate beam model.
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Study on Patch Bonding for Recovery of Damaged Carbon Fiber Reinforced Thermoplastics by Four-Point Bending Method
2013Co-Authors: Kiyotaka Obunai, Rei Yamagishi, Koichi Ozaki, Tadao Fukuta, Masahiro YamamotoAbstract:The purpose of this study is to investigate the fracture behavior and repairability of carbon fiber reinforced thermoplastics (CFRTP). At first, four-point bending tests were conducted to characterize the bending characteristics of fabricated CFRTP. The test results show that local delamination first appeared when the applied bending strain was 2.0%. When the bending strain reached 2.5%, the failure of the fiber due to local buckling was observed at the compression side of the specimen. Secondly, the effect of patch bonding on the bending strength and flexural modulus was also evaluated. Test results showed that damaged specimen could be repaired by bonding of an appropriate patch layer. Patch bonding at the compression side was more effective than at the tension side. The flexural modulus of a repaired specimen was estimated by the laminate beam model.
Gregory A Voth - One of the best experts on this subject based on the ideXlab platform.
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actin filament remodeling by actin depolymerization factor cofilin
Proceedings of the National Academy of Sciences of the United States of America, 2010Co-Authors: Jim Pfaendtner, Enrique M De La Cruz, Gregory A VothAbstract:We investigate, using molecular dynamics, how the severing protein, actin depolymerization factor (ADF)/cofilin, modulates the structure, conformational dynamics, and mechanical properties of actin filaments. The actin and cofilactin filament bending stiffness and corresponding persistence lengths obtained from all-atom simulations are comparable to values obtained from analysis of thermal fluctuations in filament shape. Filament flexibility is strongly affected by the nucleotide-linked conformation of the actin subdomain 2 DNase-I binding loop and the filament radial mass density distribution. ADF/cofilin binding between subdomains 1 and 3 of a filament subunit triggers reorganization of subdomain 2 of the neighboring subunit such that the DNase-I binding loop (DB-loop) moves radially away from the filament. Repositioning of the neighboring subunit DB-loop significantly weakens subunit interactions along the long-pitch helix and lowers the filament bending rigidity. Lateral filament contacts between the hydrophobic loop and neighboring short-pitch helix monomers in native filaments are also compromised with cofilin binding. These works provide a molecular interpretation of biochemical solution studies documenting the disruption of filament subunit interactions and also reveal the molecular basis of actin filament allostery and its linkage to ADF/cofilin binding.
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Actin filament remodeling by actin depolymerization factor/cofilin
Proceedings of the National Academy of Sciences of the United States of America, 2010Co-Authors: Jim Pfaendtner, Enrique M De La Cruz, Gregory A VothAbstract:We investigate, using molecular dynamics, how the severing protein, actin depolymerization factor (ADF)/cofilin, modulates the structure, conformational dynamics, and mechanical properties of actin filaments. The actin and cofilactin filament bending stiffness and corresponding persistence lengths obtained from all-atom simulations are comparable to values obtained from analysis of thermal fluctuations in filament shape. Filament flexibility is strongly affected by the nucleotide-linked conformation of the actin subdomain 2 DNase-I binding loop and the filament radial mass density distribution. ADF/cofilin binding between subdomains 1 and 3 of a filament subunit triggers reorganization of subdomain 2 of the neighboring subunit such that the DNase-I binding loop (DB-loop) moves radially away from the filament. Repositioning of the neighboring subunit DB-loop significantly weakens subunit interactions along the long-pitch helix and lowers the filament bending rigidity. Lateral filament contacts between the hydrophobic loop and neighboring short-pitch helix monomers in native filaments are also compromised with cofilin binding. These works provide a molecular interpretation of biochemical solution studies documenting the disruption of filament subunit interactions and also reveal the molecular basis of actin filament allostery and its linkage to ADF/cofilin binding.
