Advanced metal laminates have experienced rapid development in functional engineering application... more Advanced metal laminates have experienced rapid development in functional engineering applications. In this study, copper/aluminium metal laminates were produced by the roll bonding technique at 430°C with a critical 40% rolling reduction and sintering treatment was applied at 450°C. Interface development of the samples was examined using scanning electron microscopy and the distribution of the metallic elements and the subsequent chemical phase formation in the interfacial region was investigated by x-ray mapping. It was found that movement of the copper atoms occurred at a faster diffusion rate into the aluminium region and resulted in a shift of the interface boundary. Growth rate of the interface was determined and its relationship with sintering time was formulated. Development of the metallic phases in the interfacial area of the metal laminates was observed and determined.
An empirical relationship between the grain diameter of ternary nitride coatings and the nitrogen... more An empirical relationship between the grain diameter of ternary nitride coatings and the nitrogen deposition pressure was formulated in the present study. A linear relationship was established between the reciprocals of the square roots of the grain diameter of the coatings and the nitrogen deposition pressure. It was further confirmed that the equation parameter, rn, of the empirical relationship was linearly proportional to the primary sputter yield of the coating materials. With defined discharge conditions and sputter characteristics of the target materials. the values of m, for different coatings can be calculated and the grain size of the coating structure at different nitrogen deposition pressures can be determined. Volume 29 -2005 The papers included in this volume of Materials Forum are based on the presentations delivered at the "3rd International Conference on Advanced Materials Processing (ICAMP3)" that was held between 29 November and 1 December 2004 in Melbourne. This conference covers most aspects of advanced materials and the processes by which they are produced. Particular emphasis is placed on lightweight alloys (magnesium, aluminium and low-cost titanium), nanostructured materials and composites, powder metallurgy, thermomechanical processing, surface engineering, processing-micro structure-property relationships, advanced ceramics, biomaterials, energy and fuel cells. All invited and contributed papers were subject to the usual independent peer review process. We would like to take this opportunity to sincerely thank the reviewers who carefully reviewed each manuscript and provided the authors with constructive criticism. The publication of these papers would not be possible without their help.
Adhesives are an essential class of industrial polymers with applications ranging from pressure-s... more Adhesives are an essential class of industrial polymers with applications ranging from pressure-sensitive adhesives to hot-melt adhesives used for repairing conveyor belts in mines. The composition and homogeneity of a polyamide-based hot-melt adhesive (HMA) was revealed with attenuated total reflection (ATR)-FTIR and solid-state NMR spectroscopy. Analysis of the polyamide shows that it is obtained through sustainable manufacturing based on dimer acids. ATR-FTIR showed incorporation of an abrasion-resistant additive on the surface of the HMA but was unsuitable for other additives such as carbon black or an antistatic agent. Quantitative 13 C NMR spectroscopy revealed heterogeneity in the distribution of an antistatic agent in the HMA, which was supported by observations with differential scanning calorimetry (DSC). 1 H NMR relaxation and two-dimensional wideline separation (2D-WISE) NMR revealed differences in the molecular dynamics of functional groups in the polyamide resin and the additives dispersed in the resin matrix. 1 H T 2 relaxation revealed that the molecular mobility of the least mobile and moderately mobile components increased with increasing temperature and antistatic agent content. 2D-WISE NMR revealed a phase separation in the base resin matrix and plasticization of the whole sample at very high antistatic agent content. 1 H T 2 relaxation showed possible correlations with mechanical properties such as Young's modulus and Shore A hardness and weaker correlations with adhesive properties such as T-peel strength. This shows the suitability of NMR to assist product innovation through the design of better-performing HMAs or of HMAs for application in different climatic conditions. † Electronic supplementary information (ESI) available: Sample preparation, ATR-FTIR, and 1 H and 13 C NMR spectra with detailed signal assignment, NMR probe temperature calibration, 1 H NMR relaxation detailed data treatment, 2D-WISE spectra, scanning electron microscope images, thermogravimetric analysis, X-ray diffraction, differential scanning calorimetry, mechanical and adhesive tests. See
An oil painting by Claude Monet, Port-Goulphar, Belle-Ile 1887 ~collection of the Art Gallery of ... more An oil painting by Claude Monet, Port-Goulphar, Belle-Ile 1887 ~collection of the Art Gallery of New South Wales!, was examined to determine both the identity of the pigments used by the artist in this painting and his technique of mixing colors and laying paint on the canvas. The extremely complex construction of the painting was revealed by optical microscopy, scanning electron microscopy ~SEM!, energy dispersive X-ray analysis ~EDS!, and X-ray mapping ~XRM! analysis of cross sections of paint flakes excised from damaged regions of Port-Goulphar, Belle-Ile. Nine different pigments were found on the painting. Many of the identified colors were modern pigments that became available only late in the 19th century as a result of scientific advances in pigment chemistry. Although similar colors were available in a natural mineral form, they lacked the vivid color of their manufactured counterparts. The use of these new synthetic metallic oxide colors by Monet accounts for the brilliance of his paintings. In addition, a separation between successive paint layers was observed in some areas of paint chip cross sections, indicating that oil-based paint was applied to paint that had dried, and consequently, Port-Goulphar, Belle-Ile was painted over a long period of time. This observation is contrary to the general perception of Monet's technique of painting freely and quickly.
Dietary fiber like konjac glucomannan (KGM) is important in maintaining good human health. There ... more Dietary fiber like konjac glucomannan (KGM) is important in maintaining good human health. There is no established method for quantifying the average degree of acetylation DA of this polysaccharide. Polysaccharides are notoriously difficult to dissolve. In this study, KGM could not be fully dissolved in common solvents and was characterized in the solid state. ATR-FTIR spectroscopy enabled a fast qualitative assessment of acetylation, selective to the outer layer of KGM particles, and identifying excipients like magnesium stearate. Average DA was quantified for the first time with solid-state 13 C NMR in KGM: semi-quantitative measurements on the same arbitrary scale by cross polarization (1 to 2 days) were calibrated with a few longer single-pulse excitation measurements (approximately 1 week). DA values ranged from 4 to 8% of the hexoses in the backbone, in agreement with previously reported values. This method could be used for quality control and standardization of KGM products.
The discoloring interaction between the artist's pigments cadmium yellow and the copper-containin... more The discoloring interaction between the artist's pigments cadmium yellow and the copper-containing malachite, an interaction that is conjectured to cause black spotting in oil paintings of the 19th and early 20th centuries, was examined using X-ray mapping and scatter diagram analysis. The application of these coupled techniques confirmed that copper sulfide phases were produced during discoloration reaction. Scatter diagram analysis indicated that two copper sulfide stoichiometries ~CuS and Cu 3 S 2 ! were present as reaction products where previously only crystalline CuS ~covellite! had been identified by X-ray diffraction. The results demonstrate the potential of X-ray mapping coupled with scatter diagram analysis for the identification of both crystalline and X-ray amorphous phases produced by such complex heterogeneous interactions and their applicability to the investigation of interactions of artists' pigments.
An empirical equation of the hardness of ternary nitride coatings and the nitrogen deposition pre... more An empirical equation of the hardness of ternary nitride coatings and the nitrogen deposition pressure was formulated in the present study. A linear relationship was established between the coating hardness and the reciprocal of the square root of nitrogen pressure. The primary sputter yield of the coating materials was found to contain a linear relationship with the minimum hardness value, H 0 , of the empirical equation but showed no effect on the rate of hardness increase, mH. With defined discharge conditions and sputter yields of the target materials, the values of mH and Ho can be calculated and the hardness of a coating produced at a specified nitrogen deposition pressure can be theoretically detennined.
Nanoindentation testing was used to determine the hardness, elastic modulus and plasticity parame... more Nanoindentation testing was used to determine the hardness, elastic modulus and plasticity parameter of three newly developed ternary nitride coatings with nano-sized grains. With decreasing nitrogen deposition pressure, grain diameter of the coatings decreases that leads to both higher nanohardness and elastic modulus with conservation of satisfactory values of plasticity characteristic.
Polynuclear heterobimetallic coordination cages in which different metal cations are connected wi... more Polynuclear heterobimetallic coordination cages in which different metal cations are connected within a ligand scaffold are known to adopt a variety of polyhedral architectures, many of which display interesting functions. Within the extensive array of coordination cages incorporating Fe(II) centres reported so far, the majority contain low-spin (LS) Fe(II), with high-spin (HS) Fe(II) being less common. Herein, we present the synthesis and characterisation of a new tetradecanuclear heterobimetallic [Fe8Pd6L8](BF4]28 (1) cubic cage utilising the metalloligand approach. Use of the tripodal tris-imidazolimine derivative (2) permitted the formation of the tripodal HS Fe(II) metalloligand [FeL](BF4)2·CH3OH (3) that was subsequently used to form the coordination cage 1. Magnetic and structural analyses gave insight into the manner in which the HS environment of the metalloligand was transferred into the cage architecture along with the structural changes that accompanied its occupancy of ...
An empirical relationship between the grain diameter of ternary nitride coatings and the nitrogen... more An empirical relationship between the grain diameter of ternary nitride coatings and the nitrogen deposition pressure was formulated in the present study. A linear relationship was established between the reciprocals of the square roots of the grain diameter of the coatings and the nitrogen deposition pressure. It was further confirmed that the equation parameter, rn, of the empirical relationship was linearly proportional to the primary sputter yield of the coating materials. With defined discharge conditions and sputter characteristics of the target materials. the values of m, for different coatings can be calculated and the grain size of the coating structure at different nitrogen deposition pressures can be determined.
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Herein, we report the synthesis and characterization of a chemosensor, 5-(diethylamino)-2-(2,3-di... more Herein, we report the synthesis and characterization of a chemosensor, 5-(diethylamino)-2-(2,3-dihydro-1H-perimidin-2-yl)phenol (HL), synthesized from a condensation between 4-(diethylamino)salicylaldehyde and 1,8-diaminonaphthalene. Upon investigation of the sensing properties of HL, it was found that this sensor may be employed for simple yet efficient detection of Cu 2+ in aqueous methanol solutions. The selective and ratiometric response to Cu 2+ yielded an outstandingly low limit of detection of 3.7 nM by spectrophotometry and is also useful as a naked-eye sensor from 2.5 μM. The system was studied by spectrophotometric pH titrations to determine Cu 2+ binding constants and complex speciation. Binding of Cu 2+ to HL occurs in 1:1 stoichiometry, in good agreement with high-resolution electrospray ionization mass spectrometry (ESI-HRMS) results, Cu 2+ titrations, and Job's plot experiments, while the coordination geometry was tentatively assigned as square pyramidal by spectroscopic studies.
Extracellular matrices (ECMs) are often used in reconstructive surgery to enhance tissue regenera... more Extracellular matrices (ECMs) are often used in reconstructive surgery to enhance tissue regeneration and remodeling. Sutures and staples are currently used to fix ECMs to tissue although they can be invasive devices. Other sutureless and less invasive techniques, such as photochemical tissue bonding, cannot be coupled to ECMs because of their intrinsic opacity to light. We succeeded in fabricating a biocompatible and adhesive device that is based on ovine forestomach matrix (OFM) and a chitosan adhesive. The natural opacity of the OFM has been overcome by adding the adhesive into the matrix that allows for the light to effectively penetrate through it. The OFM-chitosan device is semitransparent (attenuation length ~ 106 µm) and can be photoactivated by green light to bond to tissue. This device does not require sutures or staples and guarantees a bonding strength of ~ 23 kPa. A new semitransparent and biocompatible bandage has been successfully fabricated and characterized for sutu...
Advanced materials (Deerfield Beach, Fla.), Jan 30, 2016
A fibrous herringbone-modified helicoidal architecture is identified within the exocuticle of an ... more A fibrous herringbone-modified helicoidal architecture is identified within the exocuticle of an impact-resistant crustacean appendage. This previously unreported composite microstructure, which features highly textured apatite mineral templated by an alpha-chitin matrix, provides enhanced stress redistribution and energy absorption over the traditional helicoidal design under compressive loading. Nanoscale toughening mechanisms are also identified using high-load nanoindentation and in situ transmission electron microscopy picoindentation.
Nature creates multifunctional composite materials by assembling organic and inorganic constituen... more Nature creates multifunctional composite materials by assembling organic and inorganic constituents into complex hierarchical structures [1]. The ability to precisely control the phase, morphology, and local distribution of components has resulted in a number of unique biological materials that exhibit a wide range of mechanical properties. One such structure is the raptorial appendage (dactyl club) of Odontodactylus scyllarus, a species of stomatopod (marine crustacean). The dactyl club is a multiphase bio-composite material that exhibits exceptional damage tolerance from high energy loading events. Here we examine and quantify the local distribution of elements within the dactyl club by means of XRM and quantitative EDS. We identify distinct phases, which are then correlated with ultrastructural and mechanical analyses to derive structure-function relationships as well as provide insight into the formation of an impact-resistant natural material.
Analytical and bioanalytical chemistry, Jan 14, 2015
Chitosan, being antimicrobial and biocompatible, is attractive as a cell growth substrate. To imp... more Chitosan, being antimicrobial and biocompatible, is attractive as a cell growth substrate. To improve cell attachment, arginine-glycine-aspartic acid-serine (RGDS) peptides were covalently grafted to chitosan films, through the widely used coupling agents 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC-HCl) and N-hydroxysuccinimide (NHS), via the carboxylic acid function of the RGDS molecule. The grafting reaction was monitored, for the first time, in real time using free-solution capillary electrophoresis (CE). This enabled fast separation and determination of the peptide and all other reactants in one separation with no sample preparation. Covalent RGDS peptide grafting onto the chitosan film surface was demonstrated using solid-state NMR of swollen films. CE indicated that oligomers of RGDS, not simply RGDS, were grafted on the film, with a likely hyperbranched structure. To assess the functional properties of the grafted films, cell growth was compared on control and peptide-...
New methods for manufacturing alloy composites have been used to produce a number of wear parts f... more New methods for manufacturing alloy composites have been used to produce a number of wear parts for the mining industry. The use of composites incorporating white cast iron and steel permit brittle and wear resistant materials to be used in applications where moderate impact conditions are encountered. Analysis of the alloy composite interfaces has provided an enhanced understanding of the bonding mechanisms between the white cast iron and the steel and has also permitted further improvements in the manufacturing techniques. Analysis methods used to examine the interfacial features include quantitative x-ray mapping (QXRM) and electron beam backscattered diffraction (EBSD) mapping. Examples of successful field trials include mineral sands dredging and wear parts for heavy earthmoving equipment.
Nanoindentation testing was used to determine the hardness, elastic modulus and plasticity parame... more Nanoindentation testing was used to determine the hardness, elastic modulus and plasticity parameter of three newly developed ternary nitride coatings with nano-sized grains. With decreasing nitrogen deposition pressure, grain diameter of the coatings decreases that leads to both higher nanohardness and elastic modulus with conservation of satisfactory values of plasticity characteristic.
Advanced metal laminates have experienced rapid development in functional engineering application... more Advanced metal laminates have experienced rapid development in functional engineering applications. In this study, copper/aluminium metal laminates were produced by the roll bonding technique at 430°C with a critical 40% rolling reduction and sintering treatment was applied at 450°C. Interface development of the samples was examined using scanning electron microscopy and the distribution of the metallic elements and the subsequent chemical phase formation in the interfacial region was investigated by x-ray mapping. It was found that movement of the copper atoms occurred at a faster diffusion rate into the aluminium region and resulted in a shift of the interface boundary. Growth rate of the interface was determined and its relationship with sintering time was formulated. Development of the metallic phases in the interfacial area of the metal laminates was observed and determined.
An empirical relationship between the grain diameter of ternary nitride coatings and the nitrogen... more An empirical relationship between the grain diameter of ternary nitride coatings and the nitrogen deposition pressure was formulated in the present study. A linear relationship was established between the reciprocals of the square roots of the grain diameter of the coatings and the nitrogen deposition pressure. It was further confirmed that the equation parameter, rn, of the empirical relationship was linearly proportional to the primary sputter yield of the coating materials. With defined discharge conditions and sputter characteristics of the target materials. the values of m, for different coatings can be calculated and the grain size of the coating structure at different nitrogen deposition pressures can be determined. Volume 29 -2005 The papers included in this volume of Materials Forum are based on the presentations delivered at the "3rd International Conference on Advanced Materials Processing (ICAMP3)" that was held between 29 November and 1 December 2004 in Melbourne. This conference covers most aspects of advanced materials and the processes by which they are produced. Particular emphasis is placed on lightweight alloys (magnesium, aluminium and low-cost titanium), nanostructured materials and composites, powder metallurgy, thermomechanical processing, surface engineering, processing-micro structure-property relationships, advanced ceramics, biomaterials, energy and fuel cells. All invited and contributed papers were subject to the usual independent peer review process. We would like to take this opportunity to sincerely thank the reviewers who carefully reviewed each manuscript and provided the authors with constructive criticism. The publication of these papers would not be possible without their help.
Adhesives are an essential class of industrial polymers with applications ranging from pressure-s... more Adhesives are an essential class of industrial polymers with applications ranging from pressure-sensitive adhesives to hot-melt adhesives used for repairing conveyor belts in mines. The composition and homogeneity of a polyamide-based hot-melt adhesive (HMA) was revealed with attenuated total reflection (ATR)-FTIR and solid-state NMR spectroscopy. Analysis of the polyamide shows that it is obtained through sustainable manufacturing based on dimer acids. ATR-FTIR showed incorporation of an abrasion-resistant additive on the surface of the HMA but was unsuitable for other additives such as carbon black or an antistatic agent. Quantitative 13 C NMR spectroscopy revealed heterogeneity in the distribution of an antistatic agent in the HMA, which was supported by observations with differential scanning calorimetry (DSC). 1 H NMR relaxation and two-dimensional wideline separation (2D-WISE) NMR revealed differences in the molecular dynamics of functional groups in the polyamide resin and the additives dispersed in the resin matrix. 1 H T 2 relaxation revealed that the molecular mobility of the least mobile and moderately mobile components increased with increasing temperature and antistatic agent content. 2D-WISE NMR revealed a phase separation in the base resin matrix and plasticization of the whole sample at very high antistatic agent content. 1 H T 2 relaxation showed possible correlations with mechanical properties such as Young's modulus and Shore A hardness and weaker correlations with adhesive properties such as T-peel strength. This shows the suitability of NMR to assist product innovation through the design of better-performing HMAs or of HMAs for application in different climatic conditions. † Electronic supplementary information (ESI) available: Sample preparation, ATR-FTIR, and 1 H and 13 C NMR spectra with detailed signal assignment, NMR probe temperature calibration, 1 H NMR relaxation detailed data treatment, 2D-WISE spectra, scanning electron microscope images, thermogravimetric analysis, X-ray diffraction, differential scanning calorimetry, mechanical and adhesive tests. See
An oil painting by Claude Monet, Port-Goulphar, Belle-Ile 1887 ~collection of the Art Gallery of ... more An oil painting by Claude Monet, Port-Goulphar, Belle-Ile 1887 ~collection of the Art Gallery of New South Wales!, was examined to determine both the identity of the pigments used by the artist in this painting and his technique of mixing colors and laying paint on the canvas. The extremely complex construction of the painting was revealed by optical microscopy, scanning electron microscopy ~SEM!, energy dispersive X-ray analysis ~EDS!, and X-ray mapping ~XRM! analysis of cross sections of paint flakes excised from damaged regions of Port-Goulphar, Belle-Ile. Nine different pigments were found on the painting. Many of the identified colors were modern pigments that became available only late in the 19th century as a result of scientific advances in pigment chemistry. Although similar colors were available in a natural mineral form, they lacked the vivid color of their manufactured counterparts. The use of these new synthetic metallic oxide colors by Monet accounts for the brilliance of his paintings. In addition, a separation between successive paint layers was observed in some areas of paint chip cross sections, indicating that oil-based paint was applied to paint that had dried, and consequently, Port-Goulphar, Belle-Ile was painted over a long period of time. This observation is contrary to the general perception of Monet's technique of painting freely and quickly.
Dietary fiber like konjac glucomannan (KGM) is important in maintaining good human health. There ... more Dietary fiber like konjac glucomannan (KGM) is important in maintaining good human health. There is no established method for quantifying the average degree of acetylation DA of this polysaccharide. Polysaccharides are notoriously difficult to dissolve. In this study, KGM could not be fully dissolved in common solvents and was characterized in the solid state. ATR-FTIR spectroscopy enabled a fast qualitative assessment of acetylation, selective to the outer layer of KGM particles, and identifying excipients like magnesium stearate. Average DA was quantified for the first time with solid-state 13 C NMR in KGM: semi-quantitative measurements on the same arbitrary scale by cross polarization (1 to 2 days) were calibrated with a few longer single-pulse excitation measurements (approximately 1 week). DA values ranged from 4 to 8% of the hexoses in the backbone, in agreement with previously reported values. This method could be used for quality control and standardization of KGM products.
The discoloring interaction between the artist's pigments cadmium yellow and the copper-containin... more The discoloring interaction between the artist's pigments cadmium yellow and the copper-containing malachite, an interaction that is conjectured to cause black spotting in oil paintings of the 19th and early 20th centuries, was examined using X-ray mapping and scatter diagram analysis. The application of these coupled techniques confirmed that copper sulfide phases were produced during discoloration reaction. Scatter diagram analysis indicated that two copper sulfide stoichiometries ~CuS and Cu 3 S 2 ! were present as reaction products where previously only crystalline CuS ~covellite! had been identified by X-ray diffraction. The results demonstrate the potential of X-ray mapping coupled with scatter diagram analysis for the identification of both crystalline and X-ray amorphous phases produced by such complex heterogeneous interactions and their applicability to the investigation of interactions of artists' pigments.
An empirical equation of the hardness of ternary nitride coatings and the nitrogen deposition pre... more An empirical equation of the hardness of ternary nitride coatings and the nitrogen deposition pressure was formulated in the present study. A linear relationship was established between the coating hardness and the reciprocal of the square root of nitrogen pressure. The primary sputter yield of the coating materials was found to contain a linear relationship with the minimum hardness value, H 0 , of the empirical equation but showed no effect on the rate of hardness increase, mH. With defined discharge conditions and sputter yields of the target materials, the values of mH and Ho can be calculated and the hardness of a coating produced at a specified nitrogen deposition pressure can be theoretically detennined.
Nanoindentation testing was used to determine the hardness, elastic modulus and plasticity parame... more Nanoindentation testing was used to determine the hardness, elastic modulus and plasticity parameter of three newly developed ternary nitride coatings with nano-sized grains. With decreasing nitrogen deposition pressure, grain diameter of the coatings decreases that leads to both higher nanohardness and elastic modulus with conservation of satisfactory values of plasticity characteristic.
Polynuclear heterobimetallic coordination cages in which different metal cations are connected wi... more Polynuclear heterobimetallic coordination cages in which different metal cations are connected within a ligand scaffold are known to adopt a variety of polyhedral architectures, many of which display interesting functions. Within the extensive array of coordination cages incorporating Fe(II) centres reported so far, the majority contain low-spin (LS) Fe(II), with high-spin (HS) Fe(II) being less common. Herein, we present the synthesis and characterisation of a new tetradecanuclear heterobimetallic [Fe8Pd6L8](BF4]28 (1) cubic cage utilising the metalloligand approach. Use of the tripodal tris-imidazolimine derivative (2) permitted the formation of the tripodal HS Fe(II) metalloligand [FeL](BF4)2·CH3OH (3) that was subsequently used to form the coordination cage 1. Magnetic and structural analyses gave insight into the manner in which the HS environment of the metalloligand was transferred into the cage architecture along with the structural changes that accompanied its occupancy of ...
An empirical relationship between the grain diameter of ternary nitride coatings and the nitrogen... more An empirical relationship between the grain diameter of ternary nitride coatings and the nitrogen deposition pressure was formulated in the present study. A linear relationship was established between the reciprocals of the square roots of the grain diameter of the coatings and the nitrogen deposition pressure. It was further confirmed that the equation parameter, rn, of the empirical relationship was linearly proportional to the primary sputter yield of the coating materials. With defined discharge conditions and sputter characteristics of the target materials. the values of m, for different coatings can be calculated and the grain size of the coating structure at different nitrogen deposition pressures can be determined.
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Herein, we report the synthesis and characterization of a chemosensor, 5-(diethylamino)-2-(2,3-di... more Herein, we report the synthesis and characterization of a chemosensor, 5-(diethylamino)-2-(2,3-dihydro-1H-perimidin-2-yl)phenol (HL), synthesized from a condensation between 4-(diethylamino)salicylaldehyde and 1,8-diaminonaphthalene. Upon investigation of the sensing properties of HL, it was found that this sensor may be employed for simple yet efficient detection of Cu 2+ in aqueous methanol solutions. The selective and ratiometric response to Cu 2+ yielded an outstandingly low limit of detection of 3.7 nM by spectrophotometry and is also useful as a naked-eye sensor from 2.5 μM. The system was studied by spectrophotometric pH titrations to determine Cu 2+ binding constants and complex speciation. Binding of Cu 2+ to HL occurs in 1:1 stoichiometry, in good agreement with high-resolution electrospray ionization mass spectrometry (ESI-HRMS) results, Cu 2+ titrations, and Job's plot experiments, while the coordination geometry was tentatively assigned as square pyramidal by spectroscopic studies.
Extracellular matrices (ECMs) are often used in reconstructive surgery to enhance tissue regenera... more Extracellular matrices (ECMs) are often used in reconstructive surgery to enhance tissue regeneration and remodeling. Sutures and staples are currently used to fix ECMs to tissue although they can be invasive devices. Other sutureless and less invasive techniques, such as photochemical tissue bonding, cannot be coupled to ECMs because of their intrinsic opacity to light. We succeeded in fabricating a biocompatible and adhesive device that is based on ovine forestomach matrix (OFM) and a chitosan adhesive. The natural opacity of the OFM has been overcome by adding the adhesive into the matrix that allows for the light to effectively penetrate through it. The OFM-chitosan device is semitransparent (attenuation length ~ 106 µm) and can be photoactivated by green light to bond to tissue. This device does not require sutures or staples and guarantees a bonding strength of ~ 23 kPa. A new semitransparent and biocompatible bandage has been successfully fabricated and characterized for sutu...
Advanced materials (Deerfield Beach, Fla.), Jan 30, 2016
A fibrous herringbone-modified helicoidal architecture is identified within the exocuticle of an ... more A fibrous herringbone-modified helicoidal architecture is identified within the exocuticle of an impact-resistant crustacean appendage. This previously unreported composite microstructure, which features highly textured apatite mineral templated by an alpha-chitin matrix, provides enhanced stress redistribution and energy absorption over the traditional helicoidal design under compressive loading. Nanoscale toughening mechanisms are also identified using high-load nanoindentation and in situ transmission electron microscopy picoindentation.
Nature creates multifunctional composite materials by assembling organic and inorganic constituen... more Nature creates multifunctional composite materials by assembling organic and inorganic constituents into complex hierarchical structures [1]. The ability to precisely control the phase, morphology, and local distribution of components has resulted in a number of unique biological materials that exhibit a wide range of mechanical properties. One such structure is the raptorial appendage (dactyl club) of Odontodactylus scyllarus, a species of stomatopod (marine crustacean). The dactyl club is a multiphase bio-composite material that exhibits exceptional damage tolerance from high energy loading events. Here we examine and quantify the local distribution of elements within the dactyl club by means of XRM and quantitative EDS. We identify distinct phases, which are then correlated with ultrastructural and mechanical analyses to derive structure-function relationships as well as provide insight into the formation of an impact-resistant natural material.
Analytical and bioanalytical chemistry, Jan 14, 2015
Chitosan, being antimicrobial and biocompatible, is attractive as a cell growth substrate. To imp... more Chitosan, being antimicrobial and biocompatible, is attractive as a cell growth substrate. To improve cell attachment, arginine-glycine-aspartic acid-serine (RGDS) peptides were covalently grafted to chitosan films, through the widely used coupling agents 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC-HCl) and N-hydroxysuccinimide (NHS), via the carboxylic acid function of the RGDS molecule. The grafting reaction was monitored, for the first time, in real time using free-solution capillary electrophoresis (CE). This enabled fast separation and determination of the peptide and all other reactants in one separation with no sample preparation. Covalent RGDS peptide grafting onto the chitosan film surface was demonstrated using solid-state NMR of swollen films. CE indicated that oligomers of RGDS, not simply RGDS, were grafted on the film, with a likely hyperbranched structure. To assess the functional properties of the grafted films, cell growth was compared on control and peptide-...
New methods for manufacturing alloy composites have been used to produce a number of wear parts f... more New methods for manufacturing alloy composites have been used to produce a number of wear parts for the mining industry. The use of composites incorporating white cast iron and steel permit brittle and wear resistant materials to be used in applications where moderate impact conditions are encountered. Analysis of the alloy composite interfaces has provided an enhanced understanding of the bonding mechanisms between the white cast iron and the steel and has also permitted further improvements in the manufacturing techniques. Analysis methods used to examine the interfacial features include quantitative x-ray mapping (QXRM) and electron beam backscattered diffraction (EBSD) mapping. Examples of successful field trials include mineral sands dredging and wear parts for heavy earthmoving equipment.
Nanoindentation testing was used to determine the hardness, elastic modulus and plasticity parame... more Nanoindentation testing was used to determine the hardness, elastic modulus and plasticity parameter of three newly developed ternary nitride coatings with nano-sized grains. With decreasing nitrogen deposition pressure, grain diameter of the coatings decreases that leads to both higher nanohardness and elastic modulus with conservation of satisfactory values of plasticity characteristic.
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Papers by richard wuhrer