110 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
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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
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
Optimal regulators for a class of nonlinear stochastic systems
No full textWe consider a class of nonlinear stochastic systems with square-root nonlinearities appearing in the diffusion terms. The optimal control problems with indefinite quadratic criteria in both finite and infinite horizon are formulated and solved in an explicit closed form. It turns out that all optimal controls are of an affine state-feedback form, despite the fact that the system is nonlinear. We use the method of completion of squares and new types of Riccati differential and algebraic equations to find the solutions. An application to the problem of optimal investment in a market with a stochastic interest rate is given
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 textEvaluating Alzheimer’s disease progression by modeling crosstalk network disruption
No full textAβ, tau and P-tau have been widely accepted as reliable markers for Alzheimer’s disease (AD). The crosstalk between these markers forms a complex network. AD may induce the integral variation and disruption of the network. The aim of this study was to develop a novel mathematic model based on a simplified crosstalk network to evaluate the disease progression of AD. The integral variation of the network is measured by three integral disruption parameters. The robustness of network is evaluated by network disruption probability. Presented results show that network disruption probability has a good linear relationship with Mini Mental State Examination (MMSE). The proposed model combined with Support vector machine (SVM) achieves a relative high 10-fold cross-validated performance in classification of AD vs normal and mild cognitive impairment (MCI) vs normal (95% accuracy, 95% sensitivity, 95% specificity for AD vs normal; 90% accuracy, 94% sensitivity, 83% specificity for MCI vs normal). This research evaluates the progression of AD and facilitates AD early diagnosis
Robust risk-sensitive control
No full textWe introduce a risk-sensitive generalization of the mixed (Formula presented.) control problem for linear stochastic systems with additive noise. Two criteria of exponential-quadratic form are used to generalise the usual quadratic criteria. The solutions are found in a linear state-feedback form for both the finite and the infinite horizon formulations in terms of coupled Riccati differential and algebraic equations. A change of measures for both criteria and completion of squares method is used to derive the solutions, and explicit sufficient conditions for the admissibility of controls are derived. An application to the problem of robust portfolio control in a market with random interest rate subject to a disturbance is also given
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