The Experts below are selected from a list of 390 Experts worldwide ranked by ideXlab platform
M.e.r. Shanahan - One of the best experts on this subject based on the ideXlab platform.
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instrumented end notched flexure crack propagation and process zone monitoring part ii data reduction and experimental
International Journal of Solids and Structures, 2013Co-Authors: Michal K. Budzik, Julien Jumel, M.e.r. Shanahan, Ben N SalemAbstract:A mode II instrumented end notched flexure three point bending (ENF) adhesion test is described. The adhesive joint consists of two aluminium alloy (AW7075-T6) plates bonded with a structural epoxy adhesive (Hysol® EA 9395™). Strain gauges are attached to the outer surface (backface) of the substrates in the lengthwise direction to measure local surface strain during crack propagation. Simultaneously, load/displacement measurements are performed. Two cases were investigated. The first was static: the joint was loaded below the crack propagation threshold. In the second, applied load above the threshold led to crack propagation. The former test confirmed the predicted load transfer mechanism between bonded and unbonded parts of the joint. In the second case, the crack front process zone was revealed in situ in mode II, we believe for the first time. These new results permitted validation of simple or refined analytical/numerical models including those of the cohesive zone. In addition, the backface strain gauge monitoring technique exhibited unexpected mode I contributions, quantitatively evaluated. Finally, R-curves are presented, as estimated with various standard models and compared with that postulated, where the process zone is accounted for.
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Instrumented end notched flexure – Crack propagation and process zone monitoring Part II: Data reduction and experimental
International Journal of Solids and Structures, 2013Co-Authors: Michal K. Budzik, Julien Jumel, N. Ben Salem, M.e.r. ShanahanAbstract:A mode II instrumented end notched flexure three point bending (ENF) adhesion test is described. The adhesive joint consists of two aluminium alloy (AW7075-T6) plates bonded with a structural epoxy adhesive (Hysol® EA 9395™). Strain gauges are attached to the outer surface (backface) of the substrates in the lengthwise direction to measure local surface strain during crack propagation. Simultaneously, load/displacement measurements are performed. Two cases were investigated. The first was static: the joint was loaded below the crack propagation threshold. In the second, applied load above the threshold led to crack propagation. The former test confirmed the predicted load transfer mechanism between bonded and unbonded parts of the joint. In the second case, the crack front process zone was revealed in situ in mode II, we believe for the first time. These new results permitted validation of simple or refined analytical/numerical models including those of the cohesive zone. In addition, the backface strain gauge monitoring technique exhibited unexpected mode I contributions, quantitatively evaluated. Finally, R-curves are presented, as estimated with various standard models and compared with that postulated, where the process zone is accounted for.
Julien Jumel - One of the best experts on this subject based on the ideXlab platform.
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instrumented end notched flexure crack propagation and process zone monitoring part ii data reduction and experimental
International Journal of Solids and Structures, 2013Co-Authors: Michal K. Budzik, Julien Jumel, M.e.r. Shanahan, Ben N SalemAbstract:A mode II instrumented end notched flexure three point bending (ENF) adhesion test is described. The adhesive joint consists of two aluminium alloy (AW7075-T6) plates bonded with a structural epoxy adhesive (Hysol® EA 9395™). Strain gauges are attached to the outer surface (backface) of the substrates in the lengthwise direction to measure local surface strain during crack propagation. Simultaneously, load/displacement measurements are performed. Two cases were investigated. The first was static: the joint was loaded below the crack propagation threshold. In the second, applied load above the threshold led to crack propagation. The former test confirmed the predicted load transfer mechanism between bonded and unbonded parts of the joint. In the second case, the crack front process zone was revealed in situ in mode II, we believe for the first time. These new results permitted validation of simple or refined analytical/numerical models including those of the cohesive zone. In addition, the backface strain gauge monitoring technique exhibited unexpected mode I contributions, quantitatively evaluated. Finally, R-curves are presented, as estimated with various standard models and compared with that postulated, where the process zone is accounted for.
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Instrumented end notched flexure – Crack propagation and process zone monitoring Part II: Data reduction and experimental
International Journal of Solids and Structures, 2013Co-Authors: Michal K. Budzik, Julien Jumel, N. Ben Salem, M.e.r. ShanahanAbstract:A mode II instrumented end notched flexure three point bending (ENF) adhesion test is described. The adhesive joint consists of two aluminium alloy (AW7075-T6) plates bonded with a structural epoxy adhesive (Hysol® EA 9395™). Strain gauges are attached to the outer surface (backface) of the substrates in the lengthwise direction to measure local surface strain during crack propagation. Simultaneously, load/displacement measurements are performed. Two cases were investigated. The first was static: the joint was loaded below the crack propagation threshold. In the second, applied load above the threshold led to crack propagation. The former test confirmed the predicted load transfer mechanism between bonded and unbonded parts of the joint. In the second case, the crack front process zone was revealed in situ in mode II, we believe for the first time. These new results permitted validation of simple or refined analytical/numerical models including those of the cohesive zone. In addition, the backface strain gauge monitoring technique exhibited unexpected mode I contributions, quantitatively evaluated. Finally, R-curves are presented, as estimated with various standard models and compared with that postulated, where the process zone is accounted for.
Michal K. Budzik - One of the best experts on this subject based on the ideXlab platform.
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instrumented end notched flexure crack propagation and process zone monitoring part ii data reduction and experimental
International Journal of Solids and Structures, 2013Co-Authors: Michal K. Budzik, Julien Jumel, M.e.r. Shanahan, Ben N SalemAbstract:A mode II instrumented end notched flexure three point bending (ENF) adhesion test is described. The adhesive joint consists of two aluminium alloy (AW7075-T6) plates bonded with a structural epoxy adhesive (Hysol® EA 9395™). Strain gauges are attached to the outer surface (backface) of the substrates in the lengthwise direction to measure local surface strain during crack propagation. Simultaneously, load/displacement measurements are performed. Two cases were investigated. The first was static: the joint was loaded below the crack propagation threshold. In the second, applied load above the threshold led to crack propagation. The former test confirmed the predicted load transfer mechanism between bonded and unbonded parts of the joint. In the second case, the crack front process zone was revealed in situ in mode II, we believe for the first time. These new results permitted validation of simple or refined analytical/numerical models including those of the cohesive zone. In addition, the backface strain gauge monitoring technique exhibited unexpected mode I contributions, quantitatively evaluated. Finally, R-curves are presented, as estimated with various standard models and compared with that postulated, where the process zone is accounted for.
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Instrumented end notched flexure – Crack propagation and process zone monitoring Part II: Data reduction and experimental
International Journal of Solids and Structures, 2013Co-Authors: Michal K. Budzik, Julien Jumel, N. Ben Salem, M.e.r. ShanahanAbstract:A mode II instrumented end notched flexure three point bending (ENF) adhesion test is described. The adhesive joint consists of two aluminium alloy (AW7075-T6) plates bonded with a structural epoxy adhesive (Hysol® EA 9395™). Strain gauges are attached to the outer surface (backface) of the substrates in the lengthwise direction to measure local surface strain during crack propagation. Simultaneously, load/displacement measurements are performed. Two cases were investigated. The first was static: the joint was loaded below the crack propagation threshold. In the second, applied load above the threshold led to crack propagation. The former test confirmed the predicted load transfer mechanism between bonded and unbonded parts of the joint. In the second case, the crack front process zone was revealed in situ in mode II, we believe for the first time. These new results permitted validation of simple or refined analytical/numerical models including those of the cohesive zone. In addition, the backface strain gauge monitoring technique exhibited unexpected mode I contributions, quantitatively evaluated. Finally, R-curves are presented, as estimated with various standard models and compared with that postulated, where the process zone is accounted for.
Tetsuo Nagano - One of the best experts on this subject based on the ideXlab platform.
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development of a highly specific rhodamine based fluorescence probe for hypochlorous acid and its application to real time imaging of phagocytosis
Journal of the American Chemical Society, 2007Co-Authors: Suguru Kenmoku, Hirotatsu Kojima, Yasuteru Urano, Tetsuo NaganoAbstract:The tetramethylrhodamine (TMR) fluorophore is a useful platform for fluorescence probes, being applicable, for example, to biological investigations utilizing fluorescence microscopy, owing to its excellent photochemical properties in aqueous media. We have developed new TMR derivatives that show different dependences of their behavior upon the environment. Among them, HMTMR showed unique characteristics, and its putative spirocyclic structure was confirmed by X-ray crystallography. Utilizing this discovery, we have established a strategy to modulate the fluorescence of TMR by regulating the spirocyclization, and we have obtained a new fluorescence probe that can detect hypochlorous acid specifically. This probe, HySOx, can work in 99.9% aqueous solution at pH 7.4 and was confirmed to be able to detect hypochlorous acid being generated inside phagosomes in real time. HySOx is tolerant to autoxidation and photobleaching under bioimaging conditions. Regulation of the spirocyclization of rhodamines, as we de...
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Development of a highly specific rhodamine-based fluorescence probe for hypochlorous acid and its application to real-time imaging of phagocytosis
Journal of the American Chemical Society, 2007Co-Authors: Suguru Kenmoku, Hirotatsu Kojima, Yasuteru Urano, Tetsuo NaganoAbstract:The tetramethylrhodamine (TMR) fluorophore is a useful platform for fluorescence probes, being applicable, for example, to biological investigations utilizing fluorescence microscopy, owing to its excellent photochemical properties in aqueous media. We have developed new TMR derivatives that show different dependences of their behavior upon the environment. Among them, HMTMR showed unique characteristics, and its putative spirocyclic structure was confirmed by X-ray crystallography. Utilizing this discovery, we have established a strategy to modulate the fluorescence of TMR by regulating the spirocyclization, and we have obtained a new fluorescence probe that can detect hypochlorous acid specifically. This probe, HySOx, can work in 99.9% aqueous solution at pH 7.4 and was confirmed to be able to detect hypochlorous acid being generated inside phagosomes in real time. HySOx is tolerant to autoxidation and photobleaching under bioimaging conditions. Regulation of the spirocyclization of rhodamines, as we describe here, provides a new approach to the rational development of novel fluorescence probes.
Suzana Ferreiradias - One of the best experts on this subject based on the ideXlab platform.
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esterification activity and operational stability of candida rugosa lipase immobilized in polyurethane foams in the production of ethyl butyrate
Biochemical Engineering Journal, 2010Co-Authors: P Pirescabral, M M R Da Fonseca, Suzana FerreiradiasAbstract:Abstract Ethyl butyrate is a fruity flavor ester widely used in food and pharmaceutical products. The synthesis of ethyl butyrate in n-hexane, catalyzed by Candida rugosa lipase immobilized in two hydrophilic polyurethane foams (“HYPOL FHP 2002” and “HYPOL FHP 5000”) was performed. In this study, the effects of (i) the immobilization supports, (ii) the initial substrate concentrations and (iii) the water content of the system, on the activity and operational stability of C. rugosa lipase in both foams, during the esterification in continuous packed-bed reactor (PBR) and in repeated batches, were investigated. When low substrate concentrations were used, no deactivation was observed for both biocatalysts, along the continuous 30-d PBR operation. Conversely, under high substrate concentrations, a fast deactivation of the biocatalysts was observed. In consecutive batches, the deactivation was faster for the lipase in the less hydrophilic foam (“FHP 5000”) with a half-life of 53 h against 170.3 h for the other counterpart. Water molecules in the microenvironment did not present a deactivation effect on the biocatalysts. The low operational stability can be ascribed to the inhibitory effect of ethanol, which tends to accumulate inside the foams.
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synthesis of ethyl butyrate in organic media catalyzed by candida rugosa lipase immobilized in polyurethane foams a kinetic study
Biochemical Engineering Journal, 2009Co-Authors: P Pirescabral, M M R Da Fonseca, Suzana FerreiradiasAbstract:A kinetic study on the synthesis of ethyl butyrate in n-hexane, catalyzed by Candida rugosa lipase immobilized in two hydrophilic polyurethane foams (“HYPOL FHP 2002” and “HYPOL FHP 5000”) was performed. With the “FHP5000” foams, esterification rates and conversion were always higher than those obtained with “FHP2002”. For both immobilized preparations, BA did not cause any inhibition on the enzymatic activity, in the range of concentration tested (0.078–0.7 M) at an initial ethanol concentration of 0.105 M. Michaelis–Menten kinetics was observed: a plateau being reached at the initial bulk BA concentration of 0.40 M and 0.45 M, corresponding to microenvironmental concentrations of 0.851 M and 0.329 M, respectively with the lipase in “FHP2002” and “FHP5000” foams. Inhibition by EtOH was observed for initial bulk concentrations higher than 0.15 M, corresponding to microenvironmental concentrations of 0.426 M and 0.256 M, for the lipase in “FHP2002” and “FHP5000” foams, respectively. Kinetic data could be well described by the substrate-inhibition model, considering the initial bulk or microenvironmental ethanol concentrations as inhibitory. © 2008 Elsevier B.V. All rights reserved.
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response surface modeling of glycerolysis catalyzed by candida rugosa lipase immobilized in different polyurethane foams for the production of partial glycerides
Journal of Molecular Catalysis B-enzymatic, 2003Co-Authors: Suzana Ferreiradias, Ana Cristina Correia, M M R Da FonsecaAbstract:Abstract Monoglycerides (MG) and diglycerides (DG) are the most widely used emulsifiers in food and pharmaceutical industries. In this study, MG and DG were produced by inter-esterification of refined olive residue oil with glycerol (glycerolysis), in n -hexane, catalyzed by Candida rugosa lipase immobilized in different biocompatible hydrophilic polyurethane foams, A and B. These foams, with aquaphilicities of 3.7 and 2.8, were prepared with a toluene diisocyanate (“Hypol FHP 2002™”) and a diphenylmethane diisocyanate (“Hypol FHP X4300 TM ”) pre-polymer, respectively. Response surface methodology was used for modeling the reaction, as a function of the molar ratio glycerol/triglycerides (Gly/TG, 0.5–2.0) and the initial water activity ( a w ) of the biocatalyst (A, 0.24–0.91; B, 0.37–0.91). Experiments were carried out following a central composite rotatable design. With lipase in foam A, production of MG and DG could be described by first order polynomials. With foam B, MG and DG production could be fitted to concave and flat surfaces, described by a second and a first orders polynomials, respectively. The best productions of MG and DG were achieved with the lipase in the less hydrophilic foam, B: at 24 h reaction time, 32% (w/w) MG and 18% (w/w) DG were obtained, when the initial a w of the biocatalyst was 0.83, with a Gly/TG of 1.