18 results on '"Duplat D"'
Search Results
2. Aroma analysis of fresh and preserved onions and leek by dual solid-phase microextraction–liquid extraction and gas chromatography–mass spectrometry
- Author
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Mondy, N, Duplat, D, Christides, J.P, Arnault, I, and Auger, J
- Published
- 2002
- Full Text
- View/download PDF
3. The influence of particle size distribution and shell imperfections on the Plasmon resonance of Au and Ag nanoshells
- Author
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Mann, D., Nascimento-Duplat, D., Keul, H., Möller, M., Verheijen, M.A., Xu, M., Urbach, H.P., Adam, A.J.L., Buskens, P., Mann, D., Nascimento-Duplat, D., Keul, H., Möller, M., Verheijen, M.A., Xu, M., Urbach, H.P., Adam, A.J.L., and Buskens, P.
- Abstract
Au and Ag nanoshells are of interest for a wide range of applications. The plasmon resonance of such nanoshells is the property of interest and can be tuned in a broad spectral regime, ranging from the ultraviolet to the mid-infrared. To date, a large number of manuscripts have been published on the optics of such nanoshells. Few of these, however, address the effect of particle size distribution and metal shell imperfections on the plasmon resonance. Both are inherent to the chemical synthesis of metal nanoshells and therefore to a large extent unavoidable. It is of vital importance to understand their effect on the plasmon resonance, since this determines the scope and limitations of the technology and may have a direct impact on the application of such particles. Here, we elucidate the effect of particle size distribution and imperfections in the metal shell on the plasmon resonance of Au and Ag nanoshells. The size of the polystyrene core and the thickness of the Au and Ag shells are systematically varied to study their influence on the plasmon resonance, and the results are compared to values obtained through optical simulations using extended Mie theory and finite element method. Discrepancies between theory and practice are studied in detail and discussed extensively. Quantitative information on the minimum thickness of the metal shell, which is required to realize a satisfactory plasmon resonance of a metal nanoshell, is provided for Au and Ag.
- Published
- 2017
4. The Influence of Particle Size Distribution and Shell Imperfections on the Plasmon Resonance of Au and Ag Nanoshells
- Author
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Mann, Daniel (author), Nascimento Duplat, D. (author), Keul, Helmut (author), Möller, Martin (author), Verheijen, Marcel (author), Xu, M. (author), Urbach, Paul (author), Adam, A.J.L. (author), Buskens, Pascal (author), Mann, Daniel (author), Nascimento Duplat, D. (author), Keul, Helmut (author), Möller, Martin (author), Verheijen, Marcel (author), Xu, M. (author), Urbach, Paul (author), Adam, A.J.L. (author), and Buskens, Pascal (author)
- Abstract
Au and Ag nanoshells are of interest for a wide range of applications. The plasmon resonance of such nanoshells is the property of interest and can be tuned in a broad spectral regime, ranging from the ultraviolet to the mid-infrared. To date, a large number of manuscripts have been published on the optics of such nanoshells. Few of these, however, address the effect of particle size distribution and metal shell imperfections on the plasmon resonance. Both are inherent to the chemical synthesis of metal nanoshells and therefore to a large extent unavoidable. It is of vital importance to understand their effect on the plasmon resonance, since this determines the scope and limitations of the technology and may have a direct impact on the application of such particles. Here, we elucidate the effect of particle size distribution and imperfections in the metal shell on the plasmon resonance of Au and Ag nanoshells. The size of the polystyrene core and the thickness of the Au and Ag shells are systematically varied to study their influence on the plasmon resonance, and the results are compared to values obtained through optical simulations using extended Mie theory and finite element method. Discrepancies between theory and practice are studied in detail and discussed extensively. Quantitative information on the minimum thickness of the metal shell, which is required to realize a satisfactory plasmon resonance of a metal nanoshell, is provided for Au and Ag., ImPhys/Optics
- Published
- 2016
- Full Text
- View/download PDF
5. An aerotransported radar design
- Author
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Alves S., A. M. P., primary, Duplat, D. N., additional, and Hernandez-Figueroa, H. E., additional
- Published
- 2009
- Full Text
- View/download PDF
6. Identification of calconectin, a calcium-binding protein specifically expressed by the mantle ofPinctada margaritifera
- Author
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Duplat, D., primary, Puisségur, M., additional, Bédouet, L., additional, Rousseau, M., additional, Boulzaguet, H., additional, Milet, C., additional, Sellos, D., additional, Van Wormhoudt, A., additional, and Lopez, E., additional
- Published
- 2006
- Full Text
- View/download PDF
7. Identification of calconectin, a calcium-binding protein specifically expressed by the mantle of Pinctada margaritifera
- Author
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Duplat, D., Puisségur, M., Bédouet, L., Rousseau, M., Boulzaguet, H., Milet, C., Sellos, D., Van Wormhoudt, A., and Lopez, E.
- Published
- 2006
- Full Text
- View/download PDF
8. The Role of Macrophytes in the Retention of Phosphorus in the River Thame, England
- Author
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House, W. A., primary, Duplat, D., additional, Denison, F. H., additional, Henville, P., additional, Dawson, F. H., additional, Cooper, D. M., additional, and May, L., additional
- Published
- 2001
- Full Text
- View/download PDF
9. Aerotransported radar antenna for oil spills monitoring antennas and propagation.
- Author
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Alves, A. M. P., Duplat, D. N., de Oliveira, L. P., and Hernandez-Figueroa, H. E.
- Published
- 2010
10. Multicenter international assessment of a SARS-CoV-2 RT-LAMP test for point of care clinical application.
- Author
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Lu S, Duplat D, Benitez-Bolivar P, León C, Villota SD, Veloz-Villavicencio E, Arévalo V, Jaenes K, Guo Y, Cicek S, Robinson L, Peidis P, Pearson JD, Woodgett J, Mazzulli T, Ponce P, Restrepo S, González JM, Bernal A, Guevara-Suarez M, Pardee K, Cevallos VE, González C, and Bremner R
- Subjects
- Canada, Humans, Molecular Diagnostic Techniques, Nucleic Acid Amplification Techniques, Point-of-Care Systems, RNA, Viral analysis, RNA, Viral genetics, Sensitivity and Specificity, COVID-19 diagnosis, SARS-CoV-2 genetics
- Abstract
Continued waves, new variants, and limited vaccine deployment mean that SARS-CoV-2 tests remain vital to constrain the coronavirus disease 2019 (COVID-19) pandemic. Affordable, point-of-care (PoC) tests allow rapid screening in non-medical settings. Reverse-transcription loop-mediated isothermal amplification (RT-LAMP) is an appealing approach. A crucial step is to optimize testing in low/medium resource settings. Here, we optimized RT-LAMP for SARS-CoV-2 and human β-actin, and tested clinical samples in multiple countries. "TTTT" linker primers did not improve performance, and while guanidine hydrochloride, betaine and/or Igepal-CA-630 enhanced detection of synthetic RNA, only the latter two improved direct assays on nasopharygeal samples. With extracted clinical RNA, a 20 min RT-LAMP assay was essentially as sensitive as RT-PCR. With raw Canadian nasopharygeal samples, sensitivity was 100% (95% CI: 67.6% - 100%) for those with RT-qPCR Ct values ≤ 25, and 80% (95% CI: 58.4% - 91.9%) for those with 25 < Ct ≤ 27.2. Highly infectious, high titer cases were also detected in Colombian and Ecuadorian labs. We further demonstrate the utility of replacing thermocyclers with a portable PoC device (FluoroPLUM). These combined PoC molecular and hardware tools may help to limit community transmission of SARS-CoV-2., Competing Interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: Y.G., S.C., and K.P. are co-inventors of the PLUM reader and co-founders of LSK Technologies, Inc. No other commercial declarations are relevant to this study. This does not alter our adherence to PLOS ONE policies on sharing data and materials.
- Published
- 2022
- Full Text
- View/download PDF
11. Protecting patches in colloidal synthesis of Au semishells.
- Author
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Mann D, Voogt S, van Zandvoort R, Keul H, Möller M, Verheijen M, Nascimento-Duplat D, Xu M, Urbach HP, Adam AJ, and Buskens P
- Abstract
Protecting groups are commonly applied in multi-step molecular syntheses to protect one or multiple functional groups from reacting. After the reaction, they are removed from the molecule. In full analogy to this concept, we report the practical and scalable colloidal synthesis of Au semishells using polyphenylsiloxane protecting patches to prevent part of the surface of polystyrene nanoparticles from being covered with Au. After Au deposition, the patches are removed yielding Au semishells. We anticipate that this strategy can be extended to the synthesis of other types of non-centrosymmetric nanoparticles.
- Published
- 2017
- Full Text
- View/download PDF
12. The Influence of Particle Size Distribution and Shell Imperfections on the Plasmon Resonance of Au and Ag Nanoshells.
- Author
-
Mann D, Nascimento-Duplat D, Keul H, Möller M, Verheijen M, Xu M, Urbach HP, Adam AJL, and Buskens P
- Abstract
Au and Ag nanoshells are of interest for a wide range of applications. The plasmon resonance of such nanoshells is the property of interest and can be tuned in a broad spectral regime, ranging from the ultraviolet to the mid-infrared. To date, a large number of manuscripts have been published on the optics of such nanoshells. Few of these, however, address the effect of particle size distribution and metal shell imperfections on the plasmon resonance. Both are inherent to the chemical synthesis of metal nanoshells and therefore to a large extent unavoidable. It is of vital importance to understand their effect on the plasmon resonance, since this determines the scope and limitations of the technology and may have a direct impact on the application of such particles. Here, we elucidate the effect of particle size distribution and imperfections in the metal shell on the plasmon resonance of Au and Ag nanoshells. The size of the polystyrene core and the thickness of the Au and Ag shells are systematically varied to study their influence on the plasmon resonance, and the results are compared to values obtained through optical simulations using extended Mie theory and finite element method. Discrepancies between theory and practice are studied in detail and discussed extensively. Quantitative information on the minimum thickness of the metal shell, which is required to realize a satisfactory plasmon resonance of a metal nanoshell, is provided for Au and Ag.
- Published
- 2017
- Full Text
- View/download PDF
13. Coupling proteomics and transcriptomics for the identification of novel and variant forms of mollusk shell proteins: a study with P. margaritifera.
- Author
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Berland S, Marie A, Duplat D, Milet C, Sire JY, and Bédouet L
- Subjects
- Amino Acid Sequence, Animals, Databases, Genetic, Kinesins chemistry, Molecular Sequence Data, Mollusca, Proteins genetics, Sequence Alignment, Gene Expression Profiling, Proteins chemistry, Proteomics
- Abstract
Shell matrix proteins from Pinctada margaritifera were characterized by combining proteomics analysis of shell organic extracts and transcript sequences, both obtained from the shell-forming cell by using the suppression subtractive hybridization method (SSH) and from an expressed sequence tag (EST) database available from Pinctada maxima mantle tissue. Some of the identified proteins were homologues to proteins reported in other mollusk shells, namely lysine-rich matrix proteins (KRMPs), shematrins and molluscan prismatic and nacreous layer 88 kDa (MPN88). Sequence comparison within and among Pinctada species pointed to intra- and interspecies variations relevant to polymorphism and to evolutionary distance, respectively. In addition, a novel shell matrix protein, linkine was identified. BLAST analysis of the peptide sequences obtained from the shell of P. margaritifera against the EST database revealed the presence of additional proteins: two proteins similar to the Pif97 protein that was identified in the shell of P. fucata, a chitinase-like protein previously identified in Crassostrea gigas, two chitin-binding proteins, and two incomplete sequences of proteins unknown so far in mollusk shells. Combining proteomics and transcriptomics analysis we demonstrate that all these proteins, including linkine, are addressed to the shell. Retrieval of motif-forming sequences, such as chitin-binding, with functional annotation from several peptides nested in the shell could indicate protein involvement in shell patterning., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2011
- Full Text
- View/download PDF
14. Low molecular weight molecules of oyster nacre induce mineralization of the MC3T3-E1 cells.
- Author
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Rousseau M, Boulzaguet H, Biagianti J, Duplat D, Milet C, Lopez E, and Bédouet L
- Subjects
- Animals, Cell Line, Collagen Type I biosynthesis, Complex Mixtures chemistry, Core Binding Factor Alpha 1 Subunit biosynthesis, Mice, Molecular Weight, Osteoblasts cytology, Osteopontin biosynthesis, Time Factors, Calcification, Physiologic drug effects, Cell Differentiation drug effects, Complex Mixtures pharmacology, Osteoblasts metabolism, Osteogenesis drug effects, Pinctada chemistry
- Abstract
The nacre layer from the pearl oyster shell is considered as a promising osteoinductive biomaterial. Nacre contains one or more signal molecules capable of stimulating bone formation. The identity and the mode of action of these molecules on the osteoblast differentiation were analyzed. Water-soluble molecules from nacre were fractionated according to dialysis, solvent extraction, and reversed-phase HPLC. The activity of a fraction composed of low molecular weight molecules in the mineralization of the MC3T3-E1 extracellular matrix was investigated. Mineralization of the preosteoblast cells was monitored according to alizarin red staining, Raman spectroscopy, scanning electron microscopy, and quantitative RT-PCR. Molecules isolated from nacre, ranging from 50 to 235 Da, induced a red alizarin staining of the preosteoblasts extracellular matrix after 16 days of culture. Raman spectroscopy demonstrated the presence of hydroxyapatite (HA) in samples treated with these molecules. Scanning electron microscopy pictures showed at the surface of the treated cells the occurrence of clusters of spherical particles resembling to HA. The treatment of cells with nacre molecules accelerated expression of collagen I and increased the mRNA expression of Runx2 and osteopontin. This study indicated that the nacre molecules efficient in bone cell differentiation are certainly different from proteins, and could be useful for in vivo bone repair., (Copyright 2007 Wiley Periodicals, Inc.)
- Published
- 2008
- Full Text
- View/download PDF
15. The effect of molecules in mother-of-pearl on the decrease in bone resorption through the inhibition of osteoclast cathepsin K.
- Author
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Duplat D, Gallet M, Berland S, Marie A, Dubost L, Rousseau M, Kamel S, Milet C, Brazier M, Lopez E, and Bédouet L
- Subjects
- Animals, Bone Resorption pathology, Cathepsin K, Cells, Cultured, Osteoclasts pathology, Rabbits, Bone Resorption physiopathology, Bone Resorption prevention & control, Cathepsins antagonists & inhibitors, Extracellular Matrix Proteins administration & dosage, Materials Testing, Osteoclasts drug effects, Ostreidae chemistry
- Abstract
This study evaluates the effect of the mother-of-pearl (nacre) organic matrix on mammalian osteoclast activity and on cathepsin K protease. Rabbit osteoclasts were cultured on bovine cortical bone slices in the presence of water-soluble molecules extracted from nacre of the pearl oyster Pinctada margaritifera. Osteoclast resorption activity was determined by quantification of the resorption surface area on bovine bone slices. Papain and cathepsin K, B and L inhibition tests were performed in the presence of the nacre water-soluble extracts. The active crude extract was fractionated by dialysis and reversed-phase high-performance liquid chromatography before electrospray mass spectrometry analysis of inhibitory fractions. The water-soluble molecules extracted from nacre decreased bone resorption without jeopardizing osteoclast survival. The hydrolytic activity of cysteine proteinases was reduced when the enzymes were incubated with the nacre water-soluble molecules. Trending towards characterization of the molecules involved, it appears that cathepsin K inhibitors remain in different nacre water-soluble organic matrix subfractions, composed of low molecular weight molecules. Mollusk shell nacre contains molecules capable of reducing osteoclast bone resorption activity by inhibiting cathepsin K, giving a new facet of the bioactivity of nacre as bone biomaterial.
- Published
- 2007
- Full Text
- View/download PDF
16. Proteomics analysis of the nacre soluble and insoluble proteins from the oyster Pinctada margaritifera.
- Author
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Bédouet L, Marie A, Dubost L, Péduzzi J, Duplat D, Berland S, Puisségur M, Boulzaguet H, Rousseau M, Milet C, and Lopez E
- Subjects
- Amino Acid Sequence, Amino Acids analysis, Animals, Chromatography, Liquid veterinary, Hydrogen-Ion Concentration, Mass Spectrometry veterinary, Molecular Sequence Data, Pinctada chemistry, Pinctada genetics, Proteins chemistry, Proteins isolation & purification, Proteome chemistry, Proteome isolation & purification, Solubility, Water chemistry, Pinctada physiology, Proteins analysis, Proteome analysis, Proteomics methods
- Abstract
Shell nacre is laid upon an organic cell-free matrix, part of which, paradoxically, is water soluble and displays biological activities. Proteins in the native shell also constitute an insoluble network and offer a model for studying supramolecular organization as a means of self-ordering. Consequently, difficulties are encountered in extraction and purification strategies for protein characterization. In this work, water-soluble proteins and the insoluble conhiolin residue of the nacre of Pinctada margaritifera matrix were analyzed via a proteomics approach. Two sequences homologous to nacre matrix proteins of other Pinctada species were identified in the water-soluble extract. One of them is known as a fundamental component of the insoluble organic matrix of nacre. In the conchiolin, the insoluble residue, four homologs of Pinctada nacre matrix proteins were found. Two of them were the same as the molecules characterized in the water-soluble extract. Results established that soluble and insoluble proteins of the nacre organic matrix share constitutive material. Surprisingly, a peptide in the conchiolin residue was found homologous to a prismatic matrix protein of Pinctada fucata, suggesting that prismatic and nacre matrices may share common proteins. The insoluble properties of shell matrix proteins appear to arise from structural organization via multimerization. The oxidative activity, found in the water-soluble fraction of the nacre matrix, is proposed as a leading process in the transformation of transient soluble proteins into the insoluble network of conchiolin during nacre growth.
- Published
- 2007
- Full Text
- View/download PDF
17. Heterogeneity of proteinase inhibitors in the water-soluble organic matrix from the oyster nacre.
- Author
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Bédouet L, Duplat D, Marie A, Dubost L, Berland S, Rousseau M, Milet C, and Lopez E
- Subjects
- Animals, Cathepsin B antagonists & inhibitors, Cathepsin L, Cathepsins antagonists & inhibitors, Chromatography, Liquid veterinary, Cysteine Endopeptidases, Cysteine Proteinase Inhibitors chemistry, Cysteine Proteinase Inhibitors isolation & purification, Cysteine Proteinase Inhibitors pharmacology, Endopeptidase K antagonists & inhibitors, Molecular Weight, Papain antagonists & inhibitors, Protease Inhibitors isolation & purification, Protease Inhibitors pharmacology, Spectrometry, Mass, Electrospray Ionization veterinary, Water chemistry, Pinctada chemistry, Protease Inhibitors chemistry
- Abstract
We extracted proteinase inhibitors from the nacre of the oyster Pinctada margaritifera with water. Mixing the nacre powder with water for 20 h led to a water-soluble fraction [0.24% (wt/wt) of nacre]. After dialysis of the water-soluble matrix through 6- to 8-kDa and 0.5-kDa membranes, the proteinase inhibitors were divided into low and high molecular weight fractions that contained inhibitors of papain, bovine cathepsin B, and human cathepsin L. We studied the heterogeneity of the inhibitors after separating the low molecular weight fraction according to charge and hydrophobicity. After multistep purification, mass spectrometry analysis revealed that a potent inhibitory fraction contained several molecules. This observation demonstrates the difficulties encountered in attempting to isolate individual metabolites from the complex mixture of molecules present in nacre matrix. Interestingly, the low molecular weight fraction contained specific inhibitors that could discern between cathepsin B and cathepsin L. The nacre organic inhibitors were active against several cysteine proteinases, yet they were more specific in relation to serine proteinases, because only proteinase K was inhibited. These results demonstrate, for the first time, the presence of active proteinase inhibitors in the mollusc shell, and it is possible that these inhibitors may play a role in either protection of proteins involved in shell formation or in defense against parasites, or both.
- Published
- 2007
- Full Text
- View/download PDF
18. Identification of low molecular weight molecules as new components of the nacre organic matrix.
- Author
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Bédouet L, Rusconi F, Rousseau M, Duplat D, Marie A, Dubost L, Le Ny K, Berland S, Péduzzi J, and Lopez E
- Subjects
- Animals, Chromatography, High Pressure Liquid, Dialysis, Spectrometry, Mass, Electrospray Ionization, Calcium Carbonate chemistry, Glycine chemistry, Peptides analysis, Pinctada chemistry
- Abstract
Nacre of Pinctada margaritifera displays a number of interesting biological activities on bone, mainly concentrated in a water-soluble organic matrix representing 0.24% of the nacre weight. Dialysis of that matrix through 8 kDa and 1 kDa cut-off membranes showed that 60% of it is made of small molecules of molecular masses below 1 kDa. Reversed-phase high-performance liquid chromatography of the small molecule fractions and subsequent electrospray ionization mass spectrometric analysis of 19 fractions thereof indicated the presence of at least 110 different molecules, in the range 100 Da-700 Da. Evidence for aggregate-forming properties of the small molecules was given. Amino acid analysis revealed that most of the small molecules were not peptides and tandem mass spectrometric gas-phase fragmentations clearly indicated a structural relationship between several molecules. Intriguingly, differences of a single Dalton between mono-charged ions peaks were observed. Further, approximately 40 analytes could be arranged in a ladder-like manner with mass spaces of 57 Da. Some of the water-soluble peptide sequences obtained after MS/MS fragmentation revealed that the 57 Da shift corresponds to the repetition of glycine residues. Furthermore, the exchange of glycine against alanine explains the 14 Da shift observed between some peptides. These data show for the first time that small molecules, especially peptides, are prevalent components of nacre. The molecular species described in this report might have a functional role in nacre.
- Published
- 2006
- Full Text
- View/download PDF
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