The Experts below are selected from a list of 10374 Experts worldwide ranked by ideXlab platform
Keun-hyeung Lee - One of the best experts on this subject based on the ideXlab platform.
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Selective and Sensitive Detection of Heavy Metal Ions in 100% Aqueous Solution and Cells with a Fluorescence Chemosensor Based on Peptide Using Aggregation-Induced Emission
Analytical Chemistry, 2016Co-Authors: Lok Nath Neupane, Heon Joo Park, Keun-hyeung LeeAbstract:A fluorescent peptidyl chemosensor for the detection of heavy metal ions in aqueous solution as well as in cells was synthesized on the basis of the peptide receptor for the metal ions using an aggregation-induced emission fluorophore. The peptidyl chemosensor (1) bearing tetraphenylethylene fluorophore showed an exclusively selective turn-on response to Hg2+ among 16 metal ions in aqueous buffered solution containing NaCl. The peptidyl chemosensor complexed Hg2+ ions and then aggregated in aqueous buffered solution, resulting in the significant enhancement (OFF-On) of emissions at around 470 nm. The fluorescent sensor showed a highly sensitive response to Hg2+, and about 1.0 equiv of Hg2+ was enough for the saturation of the emission intensity change. The detection limit (5.3 nM, R2 = 0.99) of 1 for Hg2+ ions was lower than the maximum Allowable Level of Hg2+ in drinking water by EPA. Moreover, the peptidyl chemosensor penetrated live cells and detected intracellular Hg2+ ions by the turn-on response.
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Highly sensitive and selective detection of Al(III) ions in aqueous buffered solution with fluorescent peptide-based sensor.
Bioorganic & Medicinal Chemistry Letters, 2016Co-Authors: Gi Won Hwang, Keun-hyeung LeeAbstract:Abstract A fluorescent sensor based on a tripeptide (SerGluGlu) with a dansyl fluorophore detected selectively Al(III) among 16 metal ions in aqueous buffered solutions without any organic cosolvent. The peptide-based sensor showed a highly sensitive turn on response to aluminium ion with high binding affinity (1.84 × 104 M−1) in aqueous buffered solutions. The detection limit (230 nM, 5.98 ppb) of the peptide-based sensor was much lower than the maximum Allowable Level (7.41 μM) of aluminium ions in drinking water demanded by EPA. The binding mode of the peptide sensor with aluminium ions was characterized using ESI mass spectrometry, NMR titration, and pH titration experiments.
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Efficient ensemble system based on the copper binding motif for highly sensitive and selective detection of cyanide ions in 100% aqueous solutions by fluorescent and colorimetric changes.
Analytical Chemistry, 2015Co-Authors: Kwan Ho Jung, Keun-hyeung LeeAbstract:A peptide-based ensemble for the detection of cyanide ions in 100% aqueous solutions was designed on the basis of the copper binding motif. 7-Nitro-2,1,3-benzoxadiazole-labeled tripeptide (NBD-SSH, NBD-SerSerHis) formed the ensemble with Cu2+, leading to a change in the color of the solution from yellow to orange and a complete decrease of fluorescence emission. The ensemble (NBD-SSH–Cu2+) sensitively and selectively detected a low concentration of cyanide ions in 100% aqueous solutions by a colorimetric change as well as a fluorescent change. The addition of cyanide ions instantly removed Cu2+ from the ensemble (NBD-SSH–Cu2+) in 100% aqueous solutions, resulting in a color change of the solution from orange to yellow and a “turn-on” fluorescent response. The detection limits for cyanide ions were lower than the maximum Allowable Level of cyanide ions in drinking water set by the World Health Organization. The peptide-based ensemble system is expected to be a potential and practical way for the detection ...
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Recyclable Hypersensitive Fluorescent Dipeptidyl Chemosensor Based on Silica Nanoparticles Using Signal Amplification for the Detection of Hg(II) and Cu(II) in Aqueous Solutions
Bulletin of The Korean Chemical Society, 2015Co-Authors: Songyi Han, Kwan Ho Jung, Lok Nath Neupane, Ponnaboina Thirupathi, Keun-hyeung LeeAbstract:Silica nanoparticles (SiNPs) were synthesized for the detection of heavy metal ions by conjugating a dipeptidyl fluorescent chemosensor (DPN) into the SiNPs using a click reaction. Among the 14 metal ions tested, SiNPs conjugated with DPN (DPNSi) showed sensitive responses toward Hg(II) and Cu(II) ions in aqueous solutions. The detection limits of DPNSi were determined to be 3.8 and 16.5 nM for Hg(II) and Cu(II) ions, respectively, in aqueous solutions. Moreover, the sensitivity of DPNSi to Hg(II) ions was significantly higher than that of DPN. DPNSi was sufficiently sensitive for monitoring the maximum Allowable Level of Hg(II) and Cu(II) ions in drinking water demanded by the Environmental Protection Agency (EPA). DPNSi could be recycled for the detection and removal of toxic mercury ions in aqueous solutions by regeneration with glutathione.
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Highly sensitive colorimetric detection of HgII and CuII in aqueous solutions: from amino acids toward solid platforms
The Analyst, 2015Co-Authors: Joo-young Park, Lok Nath Neupane, Keun-hyeung LeeAbstract:A chemosensor (NBD-H) based on an amino acid with 7-nitro-2,1,3-benzoxadiazole was used for selective detection of HgII and CuII among 15 metal ions in aqueous solutions by a colorimetric change. NBD-H sensitively differentiated HgII and CuII in aqueous solutions by a color change; a pink color for HgII and an orange color for CuII. NBD-H showed nanomolar detection limits for HgII (176 nM, R2 = 0.996) and CuII (163 nM, R2 = 0.996). The detection limit for CuII was much lower than the maximum Allowable Level of CuII in drinking water recommended by the U.S. EPA. The binding mode study showed that deprotonation of the NH group of NBD-H played a critical role in the binding and sensing of metal ions. NBD-H immobilized on PEG-PS resin maintained the potent binding affinity and sensing ability for the metal ions. The resin with NBD-H was recyclable for the detection of metal ions in 100% aqueous solutions.
Geoffrey R Walker - One of the best experts on this subject based on the ideXlab platform.
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saidi constrained economic planning and utilization of central storage in rural distribution networks
IEEE Systems Journal, 2019Co-Authors: A Narimani, Ghavameddin Nourbakhsh, Ali Arefi, Gerard Ledwich, Geoffrey R WalkerAbstract:This paper forms a framework for allocating a central electric energy storage (EES) in discrete communities, forming as segmentations along the rural feeders, where the installation of cross connects are not economic or even feasible. In this framework, EESs that centrally can be installed in each community are owned and operated by an aggregator/retailer, trading bidirectional energy transactions with both the grid and the customers. The objective is to find optimum investment in storage capacity in rural feeders for minimum annual energy purchase cost using energy arbitrage opportunities, while maintaining an Allowable Level of system average interruption duration index (SAIDI). As a part of EES sizing and siting optimization in this approach, annual hourly network data are utilized for charge/discharge scheduling and constraint, and for system reliability assessment—using the k-means clustering technique. This method is applied to a rural network in Queensland, Australia, and the results are examined to show the effectiveness of this method.
Toshiyuki Okano - One of the best experts on this subject based on the ideXlab platform.
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Necessary accuracy for early reflections in sound field auralization
Journal of the Acoustical Society of America, 1993Co-Authors: Toshiyuki OkanoAbstract:Necessary accuracy for early reflection Levels was investigated in order to derive criteria to verify the accuracy of a sound field simulator. Early reflections are the most important in controlling the subjective impression of a room’s sound field. The accuracy of the sound field simulator depends primarily on the accuracy of early reflections. The just‐noticeable Level difference (jnld) of early reflections defines the maximum of Allowable Level difference between real and simulated reflections. Also, the masked threshold Level (MTL) of early reflections defines the Level of the smallest reflections which a simulator should generate. However, jnld and MTL of early reflections depend on the sound field’s configuration. It is desirable that criteria are independent of the configuration of the sound field. The jnld and MTL were measured for lateral and ceiling reflections in various types of rooms with simulated sound fields. Measured jnlds and MTLs were converted into the difference in objective parameter...
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Necessary accuracy for early reflections in sound field auralization
Journal of the Acoustical Society of America, 1993Co-Authors: Toshiyuki OkanoAbstract:Necessary accuracy for early reflection Levels was investigated in order to derive criteria to verify the accuracy of a sound field simulator. Early reflections are the most important in controlling the subjective impression of a room’s sound field. The accuracy of the sound field simulator depends primarily on the accuracy of early reflections. The just‐noticeable Level difference (jnld) of early reflections defines the maximum of Allowable Level difference between real and simulated reflections. Also, the masked threshold Level (MTL) of early reflections defines the Level of the smallest reflections which a simulator should generate. However, jnld and MTL of early reflections depend on the sound field’s configuration. It is desirable that criteria are independent of the configuration of the sound field. The jnld and MTL were measured for lateral and ceiling reflections in various types of rooms with simulated sound fields. Measured jnlds and MTLs were converted into the difference in objective parameter...
Armen Saghatelyan - One of the best experts on this subject based on the ideXlab platform.
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Studying DDTs in agricultural soils of selected rural communities of Armenia
Acta Geochimica, 2019Co-Authors: Garegin Tepanosyan, L. Sahakyan, O. Belyaeva, M. Beglaryan, D. Pipoyan, Anna Hovhannisyan, Armen SaghatelyanAbstract:To study organochlorine pesticides and organophosphorus pesticides contents and assess pesticide-induced health risk in Armenia, the contents of pesticides were determined in 252 soil samples taken from relatively large plots of agricultural land in 25 rural communities. The results showed that only ∑DDT contents were detected in 39 out of 252 soil samples. The identified contents of ∑DDT mainly consisted of pp′-DDE, suggesting historical use. 6 out of 12 rural communities are characterized by the presence of former pesticide storehouses site. The excesses versus Maximum Acceptable Concentration were observed in 26 out of 39 samples and ranges from 1.03 to 464.9 times. The health risk assessment showed that non-carcinogenic risk is below the Allowable Level (HQ
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Studying DDTs in agricultural soils of selected rural communities of Armenia
Acta Geochimica, 2019Co-Authors: Garegin Tepanosyan, L. Sahakyan, O. Belyaeva, M. Beglaryan, D. Pipoyan, Anna Hovhannisyan, Armen SaghatelyanAbstract:To study organochlorine pesticides and organophosphorus pesticides contents and assess pesticide-induced health risk in Armenia, the contents of pesticides were determined in 252 soil samples taken from relatively large plots of agricultural land in 25 rural communities. The results showed that only ∑DDT contents were detected in 39 out of 252 soil samples. The identified contents of ∑DDT mainly consisted of pp′-DDE, suggesting historical use. 6 out of 12 rural communities are characterized by the presence of former pesticide storehouses site. The excesses versus Maximum Acceptable Concentration were observed in 26 out of 39 samples and ranges from 1.03 to 464.9 times. The health risk assessment showed that non-carcinogenic risk is below the Allowable Level (HQ < 1). However, the carcinogenic risk is above the Allowable Level of < 10−4 in all cases when ∑DDT is detected. Of all studied rural communities, the presence of observed ∑DDT and associated risk to the local population was detected mainly in the majority of sampling sites in Jrashen (Ararat region), Aramus (Kotayq region) and Khanjyan (Armavir region). Therefore, special attention should be given to the riskiest rural communities and risk reduction measures are needed to reduce or eliminate observed carcinogenic health effect.
Adrian Bejan - One of the best experts on this subject based on the ideXlab platform.
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The transient response of vascular composites cooled with grids and radial channels
International Journal of Heat and Mass Transfer, 2009Co-Authors: K.-m. Wang, Sylvie Lorente, Adrian BejanAbstract:Abstract Here we develop vasculatures for smart materials with volumetric cooling capability under time-varying conditions. The objective is for the vascularized composite to survive without coolant flow such that its peak temperature does not overshoot the maximum Allowable Level. The transient performance of four vasculatures is reported: grids (G) and radial channels (R), and two flow directions, inlet in the center (I) and outlet in the center (O). Designs with outlet in the center offer short response times when the Be number is smaller than 10 9 . Configurations with outlet in the center offer short heat removal times and small hot volume fractions.
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Transient cooling response of smart vascular materials for self-cooling
Journal of Applied Physics, 2009Co-Authors: J. Lee, Sylvie Lorente, Adrian BejanAbstract:Here we report the transient cooling performance of a body vascularized with tree-shaped channels supplied with coolant, which flows from one side of the body to the other. The vasculature consists of trees that alternate with upside down trees. Heat is generated volumetrically through the body at t=0. A time delay td separates the start of the flow of coolant from the start of heating. Three-dimensional simulations of conduction and convection in the solid-fluid composite show the formation and evolution of hot spots in the material. If the delay is not short enough, the maximum temperature of the body overshoots the maximum Allowable Level. The paper shows how to design the cooling delay time such that the hot-spot temperature does not exceed the safe Level represented by the maximum temperature in the limit of steady state operation. The critical delay time is determined as a function of the applied pressure difference and the complexity of the dendritic flow architecture.Here we report the transient cooling performance of a body vascularized with tree-shaped channels supplied with coolant, which flows from one side of the body to the other. The vasculature consists of trees that alternate with upside down trees. Heat is generated volumetrically through the body at t=0. A time delay td separates the start of the flow of coolant from the start of heating. Three-dimensional simulations of conduction and convection in the solid-fluid composite show the formation and evolution of hot spots in the material. If the delay is not short enough, the maximum temperature of the body overshoots the maximum Allowable Level. The paper shows how to design the cooling delay time such that the hot-spot temperature does not exceed the safe Level represented by the maximum temperature in the limit of steady state operation. The critical delay time is determined as a function of the applied pressure difference and the complexity of the dendritic flow architecture.