The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Ronei J Poppi - One of the best experts on this subject based on the ideXlab platform.
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detection of malathion in food peels by surface enhanced raman imaging spectroscopy and multivariate curve resolution
Analytica Chimica Acta, 2015Co-Authors: Carlos Diego L De Albuquerque, Ronei J PoppiAbstract:An analytical methodology was developed for detection of malathion in the peels of tomatoes and Damson plums by surface-enhanced Raman imaging spectroscopy and multivariate curve resolution. To recover the pure spectra and the distribution mapping of the analyzed surfaces, non-negative matrix factorization (NMF), multivariate curve calibration methods with alternating least squares (MCR-ALS) and MCR with weighted alternating least square (MCR-WALS) were utilized. Error covariance matrices were estimated to evaluate the structure of the error over all the data. For the tomato data, NMF-ALS and MCR-ALS presented excellent spectral recovery even in the absence of initial knowledge of the pesticide spectrum. For the Damson plum data, owing to heteroscedastic noise, MCR-WALS produced better results. This methodology enabled detection below to the maximum residue limit permitted for this pesticide. This approach can be implemented for in situ monitoring because it is fast and does not require extensive manipulation of samples, making its use feasible for other fruits and pesticides as well.
R.c. Muir - One of the best experts on this subject based on the ideXlab platform.
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flight activity of the Damson hop aphid phorodon humuli
Annals of Applied Biology, 2005Co-Authors: C.a.m. Campbell, R.c. MuirAbstract:Flight activity of Phorodon humuli was monitored using suction traps, laboratory studies and mark and recapture experiments. Emigrants were trapped as they flew from a Myrobalan (Prunus cerasifera) hedge and among dwarf hops (Humulus lupulus). Daily flight curves were bimodal with 69% and 38% of emigrants caught in the morning peak near Myrobalan and among hops, respectively. The median period of flight activity was from 2 h after sunrise until 30 min before sunset. The lower temperature for flight was 13.5°C in the field and 14.9°C for take off in the laboratory. Variations in wind speed had little effect on flight activity explaining <2.5% of the total variance among insect counts. The percentage of emigrants on hop declined exponentially with time. The relationship, y = 10.9(±2.0) + 64.3(±2.3) x 0.92(±0.01) t where t= daylight hours (standard error in parentheses), explained 98.3% of the variance. Hence, 62% of new arrivals flew within 1 day of arrival and 79% within 2 days. Similar numbers arrived as departed at 08:30, 10:30 and 12:30 h, but at 14:30 h twice as many arrived than departed and at 16:30 h, the accumulation was threefold. Daily flight curves of return migrants and males leaving hop were bimodal with 70% and 80%, respectively, trapped in the earlier peak. In the field, the median lower temperature for flight was 13.2°C for return migrants and a nonsignificantly different 12.8°C for males. The mean temperature for take off by return migrants was 15.7°C in the laboratory.
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Flight activity of the Damson–hop aphid, Phorodon humuli.
Annals of Applied Biology, 2005Co-Authors: C.a.m. Campbell, R.c. MuirAbstract:Flight activity of Phorodon humuli was monitored using suction traps, laboratory studies and mark and recapture experiments. Emigrants were trapped as they flew from a Myrobalan (Prunus cerasifera) hedge and among dwarf hops (Humulus lupulus). Daily flight curves were bimodal with 69% and 38% of emigrants caught in the morning peak near Myrobalan and among hops, respectively. The median period of flight activity was from 2 h after sunrise until 30 min before sunset. The lower temperature for flight was 13.5°C in the field and 14.9°C for take off in the laboratory. Variations in wind speed had little effect on flight activity explaining
Carlos Diego L De Albuquerque - One of the best experts on this subject based on the ideXlab platform.
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detection of malathion in food peels by surface enhanced raman imaging spectroscopy and multivariate curve resolution
Analytica Chimica Acta, 2015Co-Authors: Carlos Diego L De Albuquerque, Ronei J PoppiAbstract:An analytical methodology was developed for detection of malathion in the peels of tomatoes and Damson plums by surface-enhanced Raman imaging spectroscopy and multivariate curve resolution. To recover the pure spectra and the distribution mapping of the analyzed surfaces, non-negative matrix factorization (NMF), multivariate curve calibration methods with alternating least squares (MCR-ALS) and MCR with weighted alternating least square (MCR-WALS) were utilized. Error covariance matrices were estimated to evaluate the structure of the error over all the data. For the tomato data, NMF-ALS and MCR-ALS presented excellent spectral recovery even in the absence of initial knowledge of the pesticide spectrum. For the Damson plum data, owing to heteroscedastic noise, MCR-WALS produced better results. This methodology enabled detection below to the maximum residue limit permitted for this pesticide. This approach can be implemented for in situ monitoring because it is fast and does not require extensive manipulation of samples, making its use feasible for other fruits and pesticides as well.
Zhenjie Zhang - One of the best experts on this subject based on the ideXlab platform.
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demonstration of Damson differential privacy for analysis of large data
International Conference on Parallel and Distributed Systems, 2012Co-Authors: Marianne Winslett, Yin Yang, Zhenjie ZhangAbstract:We demonstrate Damson, a novel and powerful tool for publishing the results of biomedical research with strong privacy guarantees. Damson is developed based on the theory of differential privacy, which ensures that the adversary cannot infer the presence or absence of any individual from the published results, even with substantial background knowledge. Damson supports a variety of analysis tasks that are common in biomedical studies, including histograms, marginals, data cubes, classification, regression, clustering, and ad-hoc selection-counts. Additionally, Damson contains an effective query optimization engine, which obtains high accuracy for analysis results, while minimizing the privacy costs of performing such analysis.
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ICPADS - Demonstration of Damson: Differential Privacy for Analysis of Large Data
2012 IEEE 18th International Conference on Parallel and Distributed Systems, 2012Co-Authors: Marianne Winslett, Yin Yang, Zhenjie ZhangAbstract:We demonstrate Damson, a novel and powerful tool for publishing the results of biomedical research with strong privacy guarantees. Damson is developed based on the theory of differential privacy, which ensures that the adversary cannot infer the presence or absence of any individual from the published results, even with substantial background knowledge. Damson supports a variety of analysis tasks that are common in biomedical studies, including histograms, marginals, data cubes, classification, regression, clustering, and ad-hoc selection-counts. Additionally, Damson contains an effective query optimization engine, which obtains high accuracy for analysis results, while minimizing the privacy costs of performing such analysis.
Kenji Nomiya - One of the best experts on this subject based on the ideXlab platform.
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Encapsulation of Anion/Cation in the Central Cavity of Tetrameric Polyoxometalate, Composed of Four Trititanium(IV)-Substituted α-Dawson Subunits, Initiated by Protonation/Deprotonation of the Bridging Oxygen Atoms on the Intramolecular Surface
Inorganic Chemistry, 2011Co-Authors: Yoshitaka Sakai, Shuji Ohta, Yukihiro Shintoyo, Yuhki Taguchi, Shoko Yoshida, Satoshi Matsunaga, Yusuke Matsuki, Kenji NomiyaAbstract:Preparation and structural characterization of a novel polyoxometalate (POM), [(P2W15Ti3O60.5)4(NH4)]35-1, i.e., an encapsulated NH4+ cation species in the central cavity of a tetramer (called the Dawson tetramer) constituted by trititanium(IV)-substituted α-Dawson POM substructure, are described. POM 1 was synthesized by several different methods and unequivocally characterized by complete elemental analysis, thermogravimetric and differential thermal analysis (TG/DTA), FTIR spectroscopy, solution (15N{1H}, 31P, 183W) NMR spectroscopy, and X-ray crystallography. First, POM 1 was synthesized by a reaction of NH4Cl in aqueous solution with a precursor, which was derived by thermal treatment of a monomeric triperoxotitanium(IV)-substituted Dawson POM, [α-1,2,3-P2W15(TiO2)3O56(OH)3]9-2, for 3 h in an electric furnace at 200 °C. The encapsulated NH4+ cation in 1 was confirmed by 15N{1H} NMR measurement and X-ray crystallography. As another synthesis of 1, a direct exchange of the Cl– anion encapsulated in [{α...
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encapsulation of anion cation in the central cavity of tetrameric polyoxometalate composed of four trititanium iv substituted α dawson subunits initiated by protonation deprotonation of the bridging oxygen atoms on the intramolecular surface
Inorganic Chemistry, 2011Co-Authors: Yoshitaka Sakai, Shuji Ohta, Yukihiro Shintoyo, Yuhki Taguchi, Shoko Yoshida, Satoshi Matsunaga, Yusuke Matsuki, Kenji NomiyaAbstract:Preparation and structural characterization of a novel polyoxometalate (POM), [(P2W15Ti3O60.5)4(NH4)]35-1, i.e., an encapsulated NH4+ cation species in the central cavity of a tetramer (called the Dawson tetramer) constituted by trititanium(IV)-substituted α-Dawson POM substructure, are described. POM 1 was synthesized by several different methods and unequivocally characterized by complete elemental analysis, thermogravimetric and differential thermal analysis (TG/DTA), FTIR spectroscopy, solution (15N{1H}, 31P, 183W) NMR spectroscopy, and X-ray crystallography. First, POM 1 was synthesized by a reaction of NH4Cl in aqueous solution with a precursor, which was derived by thermal treatment of a monomeric triperoxotitanium(IV)-substituted Dawson POM, [α-1,2,3-P2W15(TiO2)3O56(OH)3]9-2, for 3 h in an electric furnace at 200 °C. The encapsulated NH4+ cation in 1 was confirmed by 15N{1H} NMR measurement and X-ray crystallography. As another synthesis of 1, a direct exchange of the Cl– anion encapsulated in [{α...
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Relation among the 2:2-, 1:1- and 1:2-type complexes of hafnium(IV)/zirconium(IV) with mono-lacunary α2-Dawson polyoxometalate ligands: Synthesis and structure of the 2:2-type complexes [{α2-P2W17O61M(μ-OH)(H2O)}2]14− (M = Hf, Zr)
Inorganica Chimica Acta, 2010Co-Authors: Yoshio Saku, Yoshitaka Sakai, Kenji NomiyaAbstract:Abstract The synthesis and characterization of di-nuclear HfIV and ZrIV complexes (the Dawson 2:2-type complexes) sandwiched between 2 mono-lacunary α2-Dawson polyoxometalate (POM) ligands, i.e., (Me2NH2)14[{α2-P2W17O61Hf(μ-OH)(H2O)}2]·17H2O (Me2NH2-1) and (Me2NH2)14[{α2-P2W17O61Zr(μ-OH)(H2O)}2]·16H2O (Me2NH2-2) are described. [Note: the moieties of their polyoxoanions are abbreviated simply as 1 and 2, respectively.] A pair of HfIV- and ZrIV-containing POMs belonging to the same family were herein isolated as dimethylammonium salts and were unambiguously characterized by complete elemental analysis, in addition to potassium analysis, TG/DTA, FTIR, single-crystal X-ray structure analysis, and solid-state (31P CPMAS) and solution (31P and 183W) NMR spectroscopy. Polyoxoanions 1 and 2 were isostructural with each other. The central [M2(μ-OH)2(H2O)2]6+ (M = Hf, Zr) cation unit was composed of 2 polyhedral M units, which were linked through 2 μ-OH groups and contained 1 water molecule coordinated to each metal center. Since the mono-lacunary Dawson POM acts as an oxygen-donor quadridentate ligand, the Hf and Zr centers are 7-coordinate. The Dawson 2:2-type complexes were converted to the Dawson 1:2-type complexes [M(α2-P2W17O61)2]16− (M = Hf, Zr), or vice versa, in solution under appropriate conditions. Also, the Dawson 2:2-type complex can be reversibly converted to the 1:1-type complex under the pH-dependent conditions. The Dawson 2:2-type POMs 1 and 2 can be compared with the recently reported, Keggin 2:2-type POMs, i.e., [M2(μ-OH)2(H2O)2]6+ (M = Hf, Zr) complexes sandwiched between 2 mono-lacunary α-Keggin POM ligands.
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Syntheses, molecular structures and pH-dependent monomer–dimer equilibria of Dawson α2-monotitanium(IV)-substituted polyoxometalates
Dalton Transactions, 2008Co-Authors: Shoko Yoshida, Yoshitaka Sakai, Hideyuki Murakami, Kenji NomiyaAbstract:The preparation and structural characterization of a novel, solid Bronsted acid based on Dawson α2-monotitanium(IV)-substituted polyoxometalates (POMs) are described. The free-acid form of the POM, i.e., 13H+-heteropolyacid with the formula H13[1b]·55H2O DH-1 (1b = [(α2-P2W17TiO61)(α2-P2W17TiO61H)(μ-O)]13−), was prepared by passing an aqueous solution containing a potassium salt precursor, K14[1a]·17H2O DK-1 (1a = [(α2-P2W17TiO61)2(μ-O)]14−), through a cation-exchange resin column. Compound DK-1 was obtained by a stoichiometric reaction of mono-lacunary Dawson POM [α2-P2W17O61]10− with Ti(SO4)2 in an aqueous solution. [Note: the abbreviations D, M, K and H stand for dimer, monomer, potassium salt and free-acid form, respectively.] Compounds DK-1 and DH-1 were characterized by using complete elemental analysis, thermogravimetric (TG) and differential thermal analysis (DTA), FTIR, solution (31P and 183W) NMR spectroscopy, pH-varied 31P NMR spectroscopy, solid-state 31P CPMAS NMR, X-ray crystallography and acidity measurements in an organic solvent with a Hammett indicator for DH-1. The monomeric form, K8[α2-P2W17TiO62]·18H2O MK-1, was derived from DK-1. The molecular structure of 1b was composed of a dimer connected through one Ti–O–Ti bond between two α2-mono-TiIV-substituted Dawson POM subunits. BVS (bond valence sum) calculation showed that one oxygen atom (O(60A)) in one of the two Dawson subunits was protonated, therefore the two subunits were unequivalent. On the other hand, the molecular structure of 1a was a Ti–O–Ti bonding dimer of two equivalent Dawson subunits. The pH-varied 31P NMR spectra of DK-1 and DH-1 in aqueous solutions showed that the monomer at pH 7.0, the dimer at pH 1.0–3.0, and the mono-protonated species of the dimer at pH 0.5 were the predominant species in the solutions. The Hammett acidity constant (H0) of DH-1 in CH3CN (−2.87) was estimated to be almost the same as that of homo-Dawson heteropolyacid H6[P2W18O62]·17H2O (−2.77).
