The Experts below are selected from a list of 192 Experts worldwide ranked by ideXlab platform
Milos V. Novotny - One of the best experts on this subject based on the ideXlab platform.
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Matrix-assisted laser desorption/ionization mass spectrometry of neutral and acidic oligosaccharides with collision-induced dissociation
Carbohydrate Research, 1998Co-Authors: Yehia Mechref, Andrew G. Baker, Milos V. NovotnyAbstract:Abstract Using ribonuclease B and human α 1 -acid glycoprotein (AGP) as model glycoproteins, matrix-assisted laser desorption/ionization (MALDI) mass spectrometry with collision-induced dissociation (CID) is validated here as an effective tool for oligosaccharide sequencing. The spectra acquired for high-mannose and complex oligosaccharide structures show characteristic fragments resulting from cleavages of the glycosidic bonds and a few cross-ring cleavages. Esterification of the sialic acid residues is essential in stabilizing the acidic N -linked oligosaccharides. An important Analytical Feature observed in all acquired spectra is the occurrence of cleavages on the same antenna up to the branching point, as deduced from the absence of fragmentation due to the simultaneous cleavages on two or more antennas.
Hong Qun Luo - One of the best experts on this subject based on the ideXlab platform.
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An ultrasensitive and selective fluorescence assay for Sudan I and III against the influence of Sudan II andIV
Biosensors & bioelectronics, 2012Co-Authors: Sheng Tian Huang, Ling Feng Yang, Hong Qun LuoAbstract:Abstract We report on an ultrasensitive and selective fluorescence assay for Sudan I and III against the influence of Sudan II and IV based on ligand exchange mechanism. Calcein as a fluorescence indicator and Sudan I–IV as model analytes were employed to investigate the Analytical Feature of this assay platform. Results show that the fluorescence of calcein can be efficiently quenched by Cu(II). When the ligand exchange reaction proceeds, calcein is deprived of Cu(II) by Sudan I and III, resulting in the fluorescence recovery of calcein. However, the ligand exchange reaction does not happen in the presence of Sudan II or IV due to the 2-methyl steric effects, which is favorable for selective determination of Sudan I and III against the influence of Sudan II and IV. It was found that the fluorescence enhancement efficiency (FEE) against the concentration of Sudan ( c Sudan , nmol L −1 ) shows a linear relationship. The calibration equations are FEE Sudan I =0.0032 c Sudan I −0.02613, and FEE Sudan III =0.0033 c Sudan III −0.02467 over the corresponding linear range of 11.25–2078.29 and 9.44–1035.78 nmol L −1 with the correlation coefficients ( R 2 ) of 0.9984 and 0.9955, respectively. And the detection limits (3 σ /slope) are calculated to be 211.3 and 208.5 pmol L −1 for Sudan I and III, respectively, showing ultralow detection limit. The Sudan dye in a commercial chilli powder sample was assayed with satisfactory results.
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Fast and sensitive dye-sensor based on fluorescein/reduced graphene oxide complex.
The Analyst, 2012Co-Authors: Sheng Tian Huang, Yan Shi, Hong Qun LuoAbstract:We report on a fast, sensitive, label-free, and general dye-sensor platform for synthetic organic dyes detection by competitive adsorption on reduced graphene oxide (rGO) against a fluorescent dye (FD). Fluorescein (Fl) as fluorescence indicator and a cationic dye methylene blue (MB) as model analyte were employed to investigate the Analytical Feature of this assay platform. An anionic dye sunset yellow FCF (SY) was chosen as a comparison analyte to test the generality of this strategy. Results show that rGO can bind Fl and quench the fluorescence by fluorescence resonance energy transfer (FRET), while MB can displace Fl quickly from the Fl/rGO complex by competitive adsorption, inducing the fluorescence recovery which provides a quantitative readout for MB. Besides, this design was simply based on the competitive adsorption of rGO between dye and FD, and can be generally applied to other dyes for label-free detection. The fluorescence enhancement efficiency (FEE) is proportional to the dye concentration over the range of 7.60–420.00 ng mL−1 MB and 7.28–400.25 ng mL−1 SY, respectively. The linear regression equations were calculated as FEEMB = 0.0192cMB − 0.3103 for MB and FEESY = 0.0142 cSY − 0.0427 for SY, with the detection limits of 1.03 and 1.15 ng mL−1, respectively. The MB in waste water and SY in an orange-flavored sports drink sample were assayed with satisfactory results.
Akos Vertes - One of the best experts on this subject based on the ideXlab platform.
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Laser microprobe mass spectrometry of quaternary phosphonium salts: Direct versus matrix-assisted laser desorption.
Journal of the American Society for Mass Spectrometry, 1993Co-Authors: J. Claereboudt, Magda Claeys, Herman J. Geise, Renaat Gijbels, Akos VertesAbstract:The use of laser microprobe mass spectrometry (LMMS) for the structural characterization of thermolabile quaternary phosphonium salts has been evaluated. A comparison has been made between LM mass spectra obtained by direct analysis of “neat” organic salts and the corresponding “matrix-assisted” LM mass spectra. Main limitations of LMMS for the direct analysis of neat organic salts (i.e., no matrix) result from (1) formation of artifact ions that originate from thermal degradation and surface recombination reactions and (2) poor shot-to-shot reproducibility of the spectra. Dilution of the organic salts in a suitable, UV-absorbing matrix (e.g., nicotinic acid) significantly enhances the quality of the LM mass spectra. Improvements are: (1) an increase of the ion yield of preformed cations, (2) reduction or elimination of thermal decomposition and other deleterious surface reactions, and (3) a much better shot-to-shot spectral reproducibility. An interesting Analytical Feature is that these LM mass spectra, which contain only a few matrix peaks, can be obtained for subnanogram amounts of sample. The results also show that triphenylphosphonium salts with polycyclic aromatic substituents can be used as “molecular thermometers” to probe both the temperatures experienced by the sample molecules during the laser-induced desorption ionization process and the internal energies of the desorbed ion species. In this way, quaternary phosphonium salts can be used for evaluating whether improvements have been achieved by applying different sample treatments. Comparison of four different matrices (i.e., nicotinic acid, ammonium chloride, glycerol, and 3-nitrobenzylalcohol) indicates that the effectiveness of a matrix to reduce thermal degradation and to decrease the internal energies of the ions depends on the UV-absorption characteristics and the volatilization/sublimation temperature of the matrix material.
Yehia Mechref - One of the best experts on this subject based on the ideXlab platform.
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Matrix-assisted laser desorption/ionization mass spectrometry of neutral and acidic oligosaccharides with collision-induced dissociation
Carbohydrate Research, 1998Co-Authors: Yehia Mechref, Andrew G. Baker, Milos V. NovotnyAbstract:Abstract Using ribonuclease B and human α 1 -acid glycoprotein (AGP) as model glycoproteins, matrix-assisted laser desorption/ionization (MALDI) mass spectrometry with collision-induced dissociation (CID) is validated here as an effective tool for oligosaccharide sequencing. The spectra acquired for high-mannose and complex oligosaccharide structures show characteristic fragments resulting from cleavages of the glycosidic bonds and a few cross-ring cleavages. Esterification of the sialic acid residues is essential in stabilizing the acidic N -linked oligosaccharides. An important Analytical Feature observed in all acquired spectra is the occurrence of cleavages on the same antenna up to the branching point, as deduced from the absence of fragmentation due to the simultaneous cleavages on two or more antennas.
Eini Nieminen - One of the best experts on this subject based on the ideXlab platform.
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Combining spatial prioritization and expert knowledge facilitates effectiveness of large-scale mire protection process in Finland
Biological Conservation, 2020Co-Authors: Santtu Kareksela, Kaisu Aapala, A. Alanen, Tuomas Haapalehto, Janne S. Kotiaho, Joona Lehtomäki, Niko Leikola, Ninni Mikkonen, Atte Moilanen, Eini NieminenAbstract:Abstract Conservation resource allocation involves a complex set of considerations including species, habitats, connectivity, local to global biodiversity objectives, alternative protection and restoration actions, while requiring cost-efficiency and effective implementation. We present a national scale spatial conservation prioritization analysis for complementing the network of protected mires in Finland. We show how spatial prioritization coupled with regional targets and expert knowledge can facilitate structured decision-making. In our application, discussion between experts was structured around the prioritization model enabling integration of quantitative analysis with expert knowledge. The used approach balances requirements of many biodiversity Features over large landscapes, while aiming at a cost-effective solution. As a special Analytical Feature, mire complexes were defined prior to prioritization to form hydrologically functional planning units, including also their drained parts that require restoration for the planning unit to remain or potentially increase in value. This enabled selection of mires where restoration effort is supporting and benefitting from the core mire areas of high conservation value. We found that a key to successful implementation was early on structured co-producing between analysts, mire experts, and decision-makers. This allowed effective multidirectional knowledge transfer and evaluation of trade-offs related to the focal conservation decisions. Quantitative trade-off information was seen especially helpful by the stakeholders to decide how to follow the analysis results. Overall, we illustrate a realistic and applicable spatial conservation prioritization case supporting real world conservation decision-making. The introduced approach can be applied globally to increase effectiveness of large-scale protection and management planning of the diverse wetland ecosystem complexes.