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Diploma thesis Errors in MRI methods for measuring diffusion coefficients a study of measurement of diffusion NMR methods, specifies the location, causes, origination diffusion coefficients. The main function of the program is to simulate changes parameters measurement of diffusion coefficients and allows for example only one gradient or runs down gradient pulses.

Characterization of the pore structure is a crucial part in themanufacturing of porous media used for purification of biologicalpharmaceuticals. This project took place at Cytiva in Uppsala and aimedat optimizing a newly developed method in pore structurecharacterization called size-exclusion quantification NMR (SEQ-NMR). Bymeasuring with diffusion NMR on a polymer solution before and afterequilibration with a material of interest the pore structure of thematerial can be determined. This project aimed at reducing the durationof a SEQ-NMR experiment while examining the performance of the methodduring different conditions with the goal of making the methodapplicable for quality control procedures. The method was optimizedboth by simulations and by experimental diffusion NMR measurements. Itwas discovered that the performance of the method could be improved byhaving an optimal mixture of the polymer solution and duringexperiments distributing ten measurement points with linear spacing.With these parameters optimized the duration of the method could bereduced with 22 hours landing on a total duration of 8 hours. Theduration combined with the complexity of the method still makes themethod unsuitable for use in quality control of porous media. Despitethe small possibility of SEQ-NMR being a quality control method thisproject has proven the method to be both reproducible and sensitive.

Specific ion effects, identified for more than hundred years, play an important role in a wide range of phenomena and applications. Several mechanisms such as direct ion interaction with molecules have been suggested to explain these effects, but quantitative experimental evidence remains scarce. Electrophoretic NMR (eNMR) has been emerging as a very powerful tool for studying molecular association and ionic transport in a variety of systems. Yet its potential in studying specific ion effect has been unexplored. In this thesis, eNMR was in part developed further as an analytical method and was in part used as one of the main techniques to study ions interacting with macromolecules in aqueous and non-aqueous solutions. The complexation of a large group of cations with poly ethylene oxide (PEO) in methanol was studied with eNMR. The binding of monovalent ions was demonstrated not to follow the Hofmeister order; multivalent cations except barium all showed negligible complexation. As a unifying feature, only cations with surface charge density below a threshold value were able to bind suggesting that ion solvation is critical. The binding mechanism was examined in greater detail for K+ and Ba2+ with oligomeric PEO of different chain lengths. Those two cations exhibited different binding mechanisms. K+ was found to bind to PEO by having at least 6 repeating units wrap around it while retaining the polymer flexibility. On the other hand, Ba2+ (and, to some extent, (BaAnion)+) needs a slightly shorter section to bind, but the molecular dynamics at the binding site slow considerably. The binding of anions with poly (N-isopropylacrylamide) in water was quantified at low salt concentration with eNMR and the binding affinity, though very weak, followed the Hofmeister order. This result indicates the non-electrostatic nature of this specific ion effects. The increase of binding strength with salt concentration is well described by a Langmuir isotherm. The specific ion binding to a protein, bovine serum albumin (BSA), was also studied at pH values where BSA has either net positive and negative charges. Our results show that anions have the same binding affinity irrespective of the surface charge while the binding strength of cations is reversed with the change in net surface charge. This indicates different binding mechanisms for cations and anions. The ionization of cellobiose in alkaline solutions was measured quantitatively by eNMR. The results show a two-step deprotonation process with increasing alkaline strength. Supported by results from 1H-13C HSQC NMR and MD simulation, ionization was proposed to be responsible for the improved solubility of cellulose in alkaline solution. eNMR was also used to characterize the effective charge of tetramethylammonium ions in a variety of solvents. In solvents of high polarity, the results agree well with predictions based on Onsager’s limiting law but for nonpolar solvents deviations were found that were attributed to ion pair formation. / <p>QC 20170216</p>

Developments in Multivariate DOSY processing and Pure Shift NMR, authored by Adam Colbourne and submitted for the degree of Doctor of Philosophy in the Faculty of Engineering and Physical Sciences at the University of Manchester, 26th February 2014. The theme of this thesis is resolution; the separation of overlapping, entangled information in NMR spectroscopy data. The ability to resolve the features of a dataset is important because it greatly simplifies, or even makes possible, the interpretation of those features to yield information. Here, methods developed to increase resolving power in two different areas of NMR spectroscopy are described; these areas are so-called 'pure shift' or δ-resolved NMR and diffusion-ordered spectroscopy (DOSY). Pure shift NMR aims to reduce the overlap of the signals present in an NMR spectrum by collapsing the multiplet structure caused by spin-spin coupling. There are a variety of methods for achieving this, each of which has its pros and cons. A homo-nuclear decoupling scheme originated by K. Zangger and H. Sterk is implemented in its most recent form to decouple the F1 and F2 dimensions of the 2D NOESY experiment individually. The application of covariance processing to allow the removal of all the multiplet structure from data produced by these singly decoupled experiments is demonstrated and the results discussed. Full experimental homo-nuclear decoupling of 2D NMR is discussed and demonstrated with the TOCSY experiment using a combination of Bax's constant time decoupling scheme in F1 and Zangger-Sterk decoupling in F2. DOSY is strictly a catch-all term for the data processing applied to pulsed field gradient NMR data to extract information on the diffusion of chemical species, but is widely accepted as referring to the combination of the two. Applied to mixtures, DOSY is a powerful tool that can allow the separation of the spectra of the mixture components; this greatly simplifies the process of interpreting mixture NMR data. However, DOSY processing struggles where signals from different, but similarly diffusing chemical species overlap; one is faced with the problem of separating similar, overlapping exponentials in noisy data. Standard DOSY processing schemes can be described as univariate or multivariate with respect to the way in which they handle DOSY data; the former analyses the data a single frequency at a time, the latter tries to untangle the whole dataset at once. Multivariate processing schemes are better suited to resolving overlap in DOSY data, because they use all of the information available, the counter point being that too much information causes them to break down. SCORE is one such algorithm. Research into constraining and augmenting SCORE is presented, leading into a discussion of the potential application of prior knowledge of the DOSY dataset. While exploring the application of prior knowledge, it was realised that the differences between the spectra extracted by SCORE could be used to separate mixture components in a general manner. The presented OUTSCORE algorithm uses information from both the spectra and diffusion dimensions of DOSY data to separate components almost an order of magnitude more similarly diffusing than was previously possible. Finally, a hybrid processing scheme termed LOCODOSY is reported, that breaks a dataset down into smaller sections for individual multivariate analysis before recombination of the results; circumventing the problem of having too much or too little data in any one analysis. The LOCODOSY processing scheme is demonstrated on both the SCORE and OUTSCORE algorithms.

Title: Investigation of matter transport by means of PFG NMR Author: Mikuláš Peksa Department of low temperature physics Supervisor: doc. RNDr. Jan Lang, Ph.D. Assistant Supervisor: RNDr. Milan Kočiřík, CSc. (ÚFCH JH AV ČR) Abstract: Estimation of transport-structural parameters such as porosity, tortuosity and surface-to-volume ratio of pores in beds of glass beads is the main goal of this study. These parameters were estimated for 5 samples with different distributions of sizes. The second goal is to probe a possibility to use the same approach to describe the self-diffusion in water solution of LiCl confined in two porous materials based on Al2O3 and glass, respectively. The last goal is the measurement of self-diffusion of water molecules in mesoporous geopolymeric material. Its capability of water transport at long scales have been documented. The measurements of apparent self-diffusion coefficients by means of NMR spectroscopy with pulsed field gradients was major methodology of this work. Keywords: porous material, porosity, tortuosity, self-diffusion, NMR

Porous materials or a porous media can be encountered in our everyday life, both in industrial and household systems and in the nature. Generally speaking all solid and semisolid materials are porous to some degree e.g. different dense rock types, plastics etc. Porous materials are constantly finding more and more applications, both in industry and research. Many commercially important process in the industry utilize porous media e.g. flow of fluids through porous media for separation process and porous catalyst supports. This has strongly contributed to the development of porous media with controlled properties, which can be utilized for understanding the behavior of liquids confined in the material, and the morphology of these synthetic materials.This thesis work brings some insight and understanding of porous materials i.e. Controlled Pore Glass (CPG). Report also contains a brief explanation of Nuclear Magnetic Resonance (NMR) spectroscopy, diffusion NMR and other techniques such as Mercury porosimetry.The first part of the thesis is focused on determining the required amount of liquid i.e. octanol needed to achieve full pore saturation for different CPGs with varying pore sizes. This was achieved by taking into account that the transverse relaxation time T2 is sensitive in the ms-ns of motional correlation times, and that there are physical factors in porous material which affect the T2. Second part, diffusion NMR is used to study self-diffusion of octanol confined in CPG, thus bringing some insight on mass transfer limitations within porous systems. The report present results obtained from experiments with NMR and Diffusion NMR, discusses the issues that can arise when investigating porous materials and suggest solutions.

Ionic liquids are continuously finding more and more applications, both in research and in the industry. Many attempts have been made to find parameters that could be used to describe all ionic liquid systems. Five years ago a Japanese group applied the work of Gutmann on ionic liquids to use ionic association to describe solvation effects. The group calculated ionic association from conductivity and diffusion measurements. This report presents a direct approach through electrophoretic NMR to measure ionic association in ionic liquids.  The report contains a brief introduction to ionic liquids and their properties as well as a short explanation of Nuclear Magnetic Resonance (NMR) spectroscopy, diffusion NMR and a more detailed explanation of electrophoretic NMR (eNMR). Experimental setups, taken from previous work by the NMR group at Physical Chemistry KTH, have been modified to allow for measurements in ionic liquid systems. The report discusses the issues that can arise when measuring eNMR in ionic liquids and suggests solutions. The method developed is principally built upon experiments on 1-butyl-3-methyl-imidazolium trifluoroacetate and is directly applicable to other ionic liquid systems. For more viscous systems than the one investigated here, slight changes will need to be made, as explained in the report.  In order to evaluate the method developed during the project the degree of association for 1-butyl-3-methyl-imidazolium trifluoroacetate has been calculated from experimental results and results in similar values as reported by Tokuda et al.. Furthermore, the temperature variation due to Joule heating during a complete eNMR experiment was also investigated by observing change in chemical shift.

PNIPAM (poly(N-Isopropylacrylamide)) is a well-known thermoresponsive polymer. Dissolved in water, it shows a structural change at 32 oC, above which the polymer folds together, and a phase separation occurs. The temperature where the polymer changes structure is known as the LCST (Lower Critical Solution Temperature), and can be modified by adding certain salts to the solution [1]. The mechanism by which the ionic components of the salts affect the LCST is not yet completely understood. The purpose of this master thesis is to study this mechanism. In order to investigate the mechanism, a combination of diffusion NMR and electrophoretic NMR was used, giving the effective charge per molecule which is directly proportional to the grade of association of ions to the polymer. The salts tested were: NaCl, NaClO4, NaSO4, NaI, NaSCN and CaCl2 from which the ClO4-, SCN-, and I- ions, as well as Cl- ions from CaCl2, were found to bind to PNIPAM.

The purpose of this thesis was to investigate how crown ethers behave and interact with different cations and to optimise the setup of the electrophoretic NMR. To get a good electrophoretic NMR measurement the electrophoretic phase shift needs to be big. To increase the phase shift some parameters needed to be adjusted, parameters such as the concentration of crown ether and cation, the duration of magnetic field gradient pulse δ, the magnetic field gradient strength g, the diffusion time Δ and the applied voltage V. The main focus then put on crown ethers 15-crown-5 and 18-crown-6. The cations used were lithium (Li), sodium (Na), potassium (K), caesium (Cs), calcium (Ca) and barium (Ba). The effective charge was obtained by using pulsed gradient NMR to derive the diffusion coefficient and electrophoretic NMR to get the electrophoretic mobility. These data were used to calculate the equilibrium constant of the formed complex. The outcome of the investigation: the affinity for 18-crown-6 was in the following order barium &gt; potassium &gt; caesium &gt; sodium &gt; calcium &gt; lithium and for 15-crown-5 barium &gt; sodium &gt; calcium &gt;  caesium &gt;  potassium &gt; lithium.