62 research outputs found
Elucidating the structures of ionic clusters, from ion-water complexes to ion-biomolecule-water complexes
No full text"The competition and cooperation between various noncovalent interactions in hydrated ions and hydrated ion-biomolecule systems are systematically characterized and examined using infrared spectroscopy and various theoretical approaches.
The Multiple Channel InfraRed PhotoDissociation spectroscopy (MC-IRPD) method is further developed and applied to argon-tagged hydrated alkali cation systems, M+(H2O)nAr (M = Li, Na, K, Rb, Cs; n = 3-5) with simultaneous monitoring of the [Ar] and [Ar+H2O] fragmentation channels. The comparison between spectral features in the two channels and corresponding energy analyses provide definitive spectral assignments of the stable structural conformers and substantial insights of hydration mechanism of the cations. Results revealed that smaller cations (Li+ and Na+), with higher charge density, prefer to form structural configurations with extended linear networks of hydrogen bonds. Larger cations (Rb+ and Cs+), with lower charge density, prefer to generate configurations with cyclic hydrogen-bonded water subunits. It appears that K+ is somewhat unique with very simple (and predominantly) single structural conformers. This has led to the suggestion that K+ can ""move"" easily in or through biological systems, concealing its identity as an ion, under the ""appearance"" or disguise as a water molecule.
Indole is used as tractable model to study the hydration structures of biomolecules as well as the interplay of non-covalent interactions within ion-biomolecule-water complexes. With three potential binding sites: above the six- or five-member ring, and the N-H group, the competition between π and hydrogen bond interactions involves multiple locations. Electrostatic interactions from monovalent cations are in direct competition with hydrogen bonding interactions, as structural configurations involving both direct cation-indole interactions and cation-water-indole bridging interactions (π-hydrogen bond) were observed. The different charge densities of Na+/K+ give rise to different structural conformers at the same level of hydration. Infrared spectra with parallel Density Function Theory (DFT) calculations and Gibbs free energy calculations revealed rich structural insights of Na+/K+(Indole)(H2O)3-6 cluster ion complexes. Isotopic (H/D) analyses were applied to decouple the spectral features originating from the OH and NH stretches. Results showed no evidence of direct interaction between water and NH group of indole (via a σ-hydrogen bond) at current levels of hydration with the incorporation of cations, however π-hydrogen bonding interactions were ubiquitous at hydration levels between two and five.
Density Functional Theory based ab initio Molecular Dynamics simulations (DFT-MD) are applied to analyze the anharmonic coupling of O-H stretching modes and large amplitude intermolecular rocking modes in the water-nitrite complex system (H2O)-(NO2)-. MD simulated spectra reproduced earlier IR-IR double resonance spectra of water-nitrite remarkably well. Thorough analyses of dynamic trajectories revealed two distinct dynamic patterns, large amplitude symmetric rocking motion and asymmetric rocking motion, which yield completely different spectral features. Systematic application of autocorrelation functions, using Fourier transforms, of chosen dynamic parameters provided unambiguous assignments of both overall infrared spectra and motion-specific infrared spectra. DFT-MD simulations are proved to be a promising and powerful alternative tool in studying systems with anharmonic couplings, considering its reasonable computational cost, easy accessibility and sufficient accuracy."Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2017-08-01The student, Haochen Ke, accepted the attached license on 2015-06-22 at 10:10.The student, Haochen Ke, submitted this Dissertation for approval on 2015-06-22 at 10:32.This Dissertation was approved for publication on 2015-06-24 at 08:34.DSpace SAF Submission Ingestion Package generated from Vireo submission #8299 on 2015-09-29 at 15:05:17Made available in DSpace on 2015-09-29T21:02:53Z (GMT). No. of bitstreams: 2
KE-DISSERTATION-2015.pdf: 7621406 bytes, checksum: de27a80bdc961ba662c38480e72b4606 (MD5)
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Previous issue date: 2015-06-24Embargo set by: Seth Robbins for item 89533
Lift date: 2017-09-29T21:03:28Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 89533
Lift date: 2017-09-29T21:08:35Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemLimited Restriction Lifted for Item 89533 on 2017-09-30T09:15:18Z
Experimental study of rare-gases excimer VUV system and H2 Lyman-bands calibration
No full textAn electron impact rare gas excimer vacuum ultra-violet experimental system is custom-designed and tested using an argon and H2 mixture. An electron flooding system, i.e. filament, is used as the hot electron source. A SiNx membrane is applied as the entrance foil separating the high vacuum chamber and the test gas chamber. A Custom-designed UV photon intensifier together with high-resolution CCD detector is used to increase the spectrum resolution up to three orders of magnitude higher than previous study. The experimental setting yields sufficiently highly resolved spectrum that could be analyzed in detail. H2 Lyman-bands are used for the spectrum calibration. A Diatomic code is applied as a simulation reference which is proved to be insufficient for accurate calibration. A Comprehensive calibration using experimental spectrum, diatomic simulation and an H2 Atlas is performed, and the result shows that the scaling of the spectrometer and detector is off by 0.08 nm, which is a reasonable number for low resolution spectrometer systems.Item withdrawn by Mark Zulauf ([email protected]) on 2012-04-20T15:15:11Z
Item was in collections:
University of Illinois Theses & Dissertations (ID: 1)
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Effects Of Multiple Argon Tagging In Alkali Metal M+h2oarn And M+d2oarn Studied By Irpd Spectroscopy
No full textMade available in DSpace on 2014-09-17T16:55:33Z (GMT). No. of bitstreams: 3
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Previous issue date: 2014-06-19Made available in DSpace on 2015-04-14T18:37:53Z (GMT). No. of bitstreams: 4
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Previous issue date: 2014-06-1
Structures Of Hydrated Alkali Metal Cations, M+(h2o)nar (m = Li, Na, K, Rb And Cs, N = 3-5), Using Infrared Photodissociation Spectroscopy And Thermodynamic Analysis
No full textAlkali metal cations play vital roles in chemical and biochemical systems. Lithium is widely used in psychiatric treatment of manic states and bipolar disorder; Sodium and potassium are essential elements, having major biological roles as electrolytes, balancing osmotic pressure on body cells and assisting the electroneurographic signal transmission; Rubidium has seen increasing usage as a supplementation for manic depression and depression treatment; Cesium doped compounds are used as essential catalysts in chemical production and organic synthesis. Since hydrated alkali metal cations are ubiquitous and the basic form of the alkali metal cations in chemical and biochemical systems, their structural and thermodynamic properties serve as the foundation for modeling more complex chemical and biochemical processes, such as ion transport and ion size-selectivity of ionophores and protein channels.
By combining mass spectrometry and infrared photodissociation spectroscopy, we have characterized the structures and thermodynamic properties of the hydrated alkali metal cations, i.e. M(HO)Ar, (M = Li, Na, K, Rb and Cs, n = 3-5). Ab initio calculations and RRKM-EE (evaporative ensemble) calculations were used to assist in the spectral assignments and thermodynamic analysis.
Results showed that the structures of hydrated alkali metal cations were determined predominantly by the competition between non-covalent interactions, i.e. the water---water hydrogen bonding interactions and the water---cation electrostatic interactions. This balance, however, is very delicate and small changes, i.e. different cations, different levels of hydration and different effective temperatures clearly impact the balance.Made available in DSpace on 2014-09-17T16:55:08Z (GMT). No. of bitstreams: 3
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Previous issue date: 2014-06-1
Xinhua Zou shi xiao yi zhai yi shu /
No full textImprint date from preface.[1-7] Du shu ou shi : 8 juan -- [8-9] Wu yun lun : 2 juan -- [10] Zhuan xu li kao : 2 juan -- [11-12] Wen : 3 juan Shi hong ya ke shi shi wen.Mode of access: Internet
Effect of magnetite nanoparticles on methanogenic degradation of <i>p</i>-cresol in anaerobic membrane bioreactor
No full textAnaerobic membrane bioreactor (AnMBR) is a promising technology to treat phenolic wastewater. Conductive materials such as magnetite and granular activated carbon have been reported to be capable of improving anaerobic digestion by facilitating direct interspecies electron transfer (DIET). This research first investigated the effect of magnetite on the treatment of synthetic p-cresol (a relative abundant compound in phenolic wastewater) wastewater in a lab-scale AnMBR. Magnetite increased the reactor stability, permitted higher p-cresol loading rate in the AnMBR, and reduced the fouling potential of supernatant of the mixed liquor. Activities of dehydrogenase and F420 were significantly increased and this may have contributed to the enhanced reactor performance. Magnetite supplement did not have a substantial influence on the soluble microbial products (SMPs) concentration compared to the stage without magnetite whereas extracellular polymeric substances (EPS) concentration significantly increased with magnetite supplement. Reduced fouling potential of the supernatant of the mixed liquor may be attributed to the decrease of protein content in SMPs in the stage with magnetite supplement. Second, the effect of magnetite on the methanogenic degradation pathway of p-cresol was studied, in which the rate limiting step was the conversion of intermediate compound benzoate. Moreover, magnetite increased the maximum substrate degradation rate of all the chosen intermediates as well as the accumulative methane production. Batch test using inoculum adapted to magnetite failed to yield faster substrate degradation rate in comparison with the batch test using non-adapted inoculum. This may be ascribed to the loss of biomass when magnetite was removed from the collected sludge because magnetite and DIET-based microorganisms were closely associated and shaking manually was not sufficient for microorganisms to detach from the magnetite. Since magnetite nanoparticles enhanced reactor performance and stability as well as reduced fouling potential of the supernatant of the mixed liquor, potential commercial application of magnetite nanoparticles in AnMBR may permit shorter hydraulic retention time (HRT) and higher flux, which can lead to higher treatment capacity and lower operational costs. Further research should investigate the effect of potential magnetite corrosion on the reactor performance, the effect of magnetite on fouling potential of the mixed liquor, and likely loss of biomass in case of magnetite removal and methods to remove magnetite with as little loss of biomass as possible.Civil Engineerin
The rise of the piano art in China
No full textThis thesis focuses on the emergence, development and characteristics of the piano art in China. Piano art as one of the kind of art have been developed in China for about one century, but its development was very tangled and complicated. The author divides the whole process of the development of the piano art in China into four important phases. It focuses on the period from the first contact of piano art with China until the current period of apparent presperity. The thesis does not exclude the period of the Cultural Revolution, but it handles the political issues only marginally
Evaluation of cleaner production options in dyeing and printing industry: Using combination weighting method
No full textPiezoelectric ceramic-polymer composite for energy storage and harvesting applications
No full textRecently, the application of piezoelectric materials in energy storage and energy harvesting has received considerable attention. Among them, piezoelectric ceramic-polymer composites have good dielectric and piezoelectric properties as well as high flexibility, thus making them an outstanding candidate in energy-related applications. In this study, we investigated the preparation and electromechanical properties and simulations of the composites: 1. PbTiO3-PVDF composites with 70% ceramic powder; 2. the design of a two-degree-of-freedom (2-DOF) cantilever beam energy harvester and the optimization of the design by COMSOL simulation; 3. PVDF/Al2O3 thick films, and three layers of pure PVDF/Composite/pure PVDF composite, and the evaluation for energy storage application.
PVDF composite with 70 vol% PbTiO3 showed d33 of 45 pC/N. 2-DOF cantilever with micro-fiber composite (MFC) sheet could generate power of 1.08 mW and output voltage of 28 V. Multilayer composite PVDF thick films with Al2O3 fillers showed recovery energy density of 1.08 J/cm2 and efficiency of 71%.M.S.Includes bibliographical reference
Instability, adiabaticity and controlling effects of external fields for the dark state in a heteronuclear atom-tetramer conversion system
No full textWe study the formation of stable heteronuclear tetramers from ultracold atoms via two different paths by generalized Raman adiabatic passage. The dynamical instability and adiabaticity of the dark state are investigated. The regions for the appearance of dynamical instability are analytically obtained and the adiabatic evolution is studied by adiabatic fidelity. Moreover, the effects of the external field parameters on the conversion efficiency are investigated, and a comparison is also drawn between the two different paths.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000342033100014&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701OpticsPhysics, Atomic, Molecular & ChemicalSCI(E)[email protected]; [email protected]
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