The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Jaswinder Sharma - One of the best experts on this subject based on the ideXlab platform.
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addressable morphology control of silica structures by manipulating the Reagent Addition time
RSC Advances, 2014Co-Authors: Panos G Datskos, Jihua Chen, Jaswinder SharmaAbstract:The current synthesis strategies focus on Addition of all Reagents together. Herein, we demonstrate the effect of Reagent Addition time on the final morphology of colloidal silica structures without changing the actual reaction conditions, and utilize this effect to synthesize silica rods with addressable diameter control.
Robert T Kennedy - One of the best experts on this subject based on the ideXlab platform.
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label free screening of enzyme inhibitors at femtomole scale using segmented flow electrospray ionization mass spectrometry
Analytical Chemistry, 2012Co-Authors: Shuwen Sun, Thomas R. Slaney, Robert T KennedyAbstract:Droplet-based microfluidics is an attractive platform for screening and optimizing chemical reactions. Using this approach, it is possible to reliably manipulate nanoliter volume samples and perform operations such as Reagent Addition with high precision, automation, and throughput. Most studies using droplet microfluidics have relied on optical techniques to detect the reaction; however, this requires engineering color or fluorescence change into the reaction being studied. In this work, we couple electrospray ionization mass spectrometry (ESI-MS) to nanoliter scale segmented flow reactions to enable direct (label-free) analysis of reaction products. The system is applied to a screen of inhibitors for cathepsin B. In this approach, solutions of test compounds (including three known inhibitors) are arranged as an array of nanoliter droplets in a tube segmented by perfluorodecalin. The samples are pumped through a series of tees to add enzyme, substrate (peptides), and quenchant. The resulting reaction mix...
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Push-pull perfusion sampling with segmented flow for high temporal and spatial resolution in vivo chemical monitoring.
Analytical chemistry, 2011Co-Authors: Thomas R. Slaney, Jing Nie, Neil D. Hershey, Prasanna Thwar, Jennifer J. Linderman, Mark A. Burns, Robert T KennedyAbstract:Low-flow push-pull perfusion is a sampling method that yields better spatial resolution than competitive methods like microdialysis. Because of the low flow rates used (50 nL/min), it is challenging to use this technique at high temporal resolution which requires methods of collecting, manipulating, and analyzing nanoliter samples. High temporal resolution also requires control of Taylor dispersion during sampling. To meet these challenges, push-pull perfusion was coupled with segmented flow to achieve in vivo sampling at 7 s temporal resolution at 50 nL/min flow rates. By further miniaturizing the probe inlet, sampling with 200 ms resolution at 30 nL/min (pull only) was demonstrated in vitro. Using this method, L-glutamate was monitored in the striatum of anesthetized rats. Up to 500 samples of 6 nL each were collected at 7 s intervals, segmented by an immiscible oil and stored in a capillary tube. The samples were assayed offline for L-glutamate at a rate of 15 samples/min by pumping them into a Reagent Addition tee fabricated from Teflon where Reagents were added for a fluorescent enzyme assay. Fluorescence of the resulting plugs was monitored downstream. Microinjection of 70 mM potassium in physiological buffered saline evoked l-glutamate concentration transients that had an average maxima of 4.5 ± 1.1 μM (n = 6 animals, 3-4 injections each) and rise times of 22 ± 2 s. These results demonstrate that low-flow push-pull perfusion with segmented flow can be used for high temporal resolution chemical monitoring and in complex biological environments.
Sanjeev Kumar - One of the best experts on this subject based on the ideXlab platform.
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effect of Reagent Addition rate and temperature on synthesis of gold nanoparticles in microemulsion route
Industrial & Engineering Chemistry Research, 2011Co-Authors: Girish Muralidharan, Lakshmanan Subramanian, Sravan Kumar Nallamuthu, Venugopal Santhanam, Sanjeev KumarAbstract:Nanoparticle synthesis in a microemulsion route is typically controlled by changing the water to surfactant ratio, concentration of precursors, and/or concentration of micelles. The experiments carried out in this work with chloroauric acid and hydrazine hydrate as precursors in water/AOT-Brij30/isooctane microemulsions show that the Reagent Addition rate can also be used to tune the size of stable spherical gold nanoparticles to some extent. The particle size goes through a minimum with variation in feed Addition rate. The increase in particle size with an increase in reaction temperature is in agreement with an earlier report. A population balance model is used to interpret the experimental findings. The reduced extent of nucleation at low feed Addition rates and suppression of nucleation due to the finite rate of mixing at higher Addition rates produce a minimum in particle size. The increase in particle size at higher reaction temperatures is explained through an increase in fusion efficiency of micelles which dissipates supersaturation; increase in solubility is shown to play an insignificant role. The moderate polydispersity of the synthesized particles is due to the continued nucleation and growth of particles. The polydispersity of micelle sizes by itself plays a minor role.
Panos G Datskos - One of the best experts on this subject based on the ideXlab platform.
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addressable morphology control of silica structures by manipulating the Reagent Addition time
RSC Advances, 2014Co-Authors: Panos G Datskos, Jihua Chen, Jaswinder SharmaAbstract:The current synthesis strategies focus on Addition of all Reagents together. Herein, we demonstrate the effect of Reagent Addition time on the final morphology of colloidal silica structures without changing the actual reaction conditions, and utilize this effect to synthesize silica rods with addressable diameter control.
Ted E Woodburn - One of the best experts on this subject based on the ideXlab platform.
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effect of Addition of surface active agent on the viscosity of a high concentration slurry of a low rank british coal in water
Fuel Processing Technology, 2000Co-Authors: Zeki Aktas, Ted E WoodburnAbstract:Abstract Coal–water mixtures (CWM) are concentrated suspensions of coal particles in water. The rheological properties of CWM depend on a number of factors such as the type of coal, the solid content and its size distribution, the temperature, the pH and the presence of electrolytes and chemical additives. The slurry viscosity was influenced significantly by initial surfactant loading, the particle size distribution and the ash content of the feeds. CWS of up to 60% prepared from Bickershaw coal samples with low ash contents (4.0% and 6.86%) could be produced at acceptable viscosities in the presence of a non-ionic surfactant, Triton X-405. To produce pumpable slurries with more than 60% solid, it will be necessary first to achieve a significant level of demineralisation, and to use high levels of Reagent Addition. The viscosities of the slurries with low ash content were significantly reduced by the surfactant Addition which also altered the rheological characters of these slurries from non-Newtonian towards Newtonian fluids. However, sample containing very fine particles with a high ash content (24.5%) showed non-Newtonian behaviour even in the presence of Reagent.
