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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

Rheo-NMR studies of macromolecules : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Physics at Massey University, Palmerston North, New Zealand

Kakubayashi, Motoko January 2008 (has links)
In this thesis, the effects of simple shear flow on macromolecular structure and interactions are investigated in detail via a combination of Nuclear Magnetic Resonance (NMR) spectroscopy and rheology, namely Rheo-NMR. A specially designed NMR couette shear cell and benchtop shear cell, developed in-house, demonstrated that the direct measurement of the above phenomena is possible. First, to determine whether the shear cells were creating simple shear flow, results were reproduced from literature studies of liquid crystal systems which report shear effects on: Cetyl Trimethyl Ammonium Bromide (CTAB) in deuterium oxide, and Poly(gamma-benzyl-L-glutamate) (PBLG) in m-cresol. Next, the possible conformational changes to protein structure brought about by shear were investigated by applying shear to Bovine -lactogobulin ( -Lg). As the protein was sheared, a small, irreversible conformational change was observed by means of one-dimensional and two-dimensional 1H NMR with reasonable reproducibility. However, no observable change was detected by means of light scattering. A large conformational change was observed after shearing a destabilized -Lg sample containing 10% Trifluoroethanol (TFE) (v/v). From an NMR point of view, the sheared state was similar to the structure of -Lg containing large amounts of -helices and, interestingly, similar to the structure of -Lg containing -sheet amyloid fibrils. Gel electrophoresis tests suggested that the changes were caused by hydrophobic interactions. Unfortunately, this proved to be difficult to reproduce. The effect of shear on an inter-macromolecular interaction was investigated by applying shear during an enzyme reaction of pectin methylesterase (PME) on pectin. Experimental method and analysis developments are described in detail. It was observed that under the conditions studied, shear does not interfere with the de-esterification of pectin with two types of PME, which have different action mechanisms at average shear rates up to 1570 s-1.
192

Ultrastructure of the Primary Cell Wall of Softwood Fibres Studied using Dynamic FT-IR Spectroscopy

Stevanic Srndovic, Jasna January 2008 (has links)
<p>The primary cell wall is a complex multipolymer system whose composite structure has been mostly determined from chemical and biochemical studies. Although the primary cell wall serves a central role, with regard to the connective properties of fibres, knowledge about the interactions among the polymers, when it comes to the mechanical properties, is very limited. The physical properties of the polymers, i.e. their elastic and viscous deformations, as well as the ultrastructure of the polymers, i.e. the interactions among the polymers in the outer fibre wall layers that lead to this behaviour, are still not fully understood.</p><p>The aim of this study was to examine how the different wood polymers, viz. lignin, protein, pectin, xyloglucan and cellulose, interact in the outer fibre wall layers of the spruce wood tracheid. The initial objective was to separate an enriched primary cell wall material from a first stage TMP, by means of screening and centri-cleaning. From this material, consisting of the primary cell wall (P) and outer secondary cell wall (S1) materials, thin sheets were prepared and analysed using a number of different analytical methods. The major measuring technique used was dynamic Fourier transform infra-red (FT-IR) spectroscopy in combination with dynamic 2D FT-IR spectroscopy. This technique is based on the detection of small changes in molecular absorption that occur when a sinusoidally stretched sample undergoes low strain. The molecular groups affected by the stretching respond in a specific way, depending on their environment, while the unaffected molecular groups provide no response to the dynamic spectra, by producing no elastic or viscous signals. Moreover, the dynamic 2D FT-IR spectroscopy provides useful information about various intermolecular and intramolecular interactions, which influence the reorientability of functional groups in a polymer material.</p><p>Measurements of the primary cell wall material, using dynamic FT-IR spectroscopy, indicated that strong interactions exist among lignin, protein and pectin, as well as among cellulose, xyloglucan and pectin in this particular layer. This was in contrast to the secondary cell wall, where interactions of cellulose with glucomannan and of xylan with lignin were dominant. It was also indicated that the most abundant crystalline cellulose in the primary cell wall of spruce wood fibres is the cellulose Iβ allomorph, which was also in contrast to the secondary cell wall, where the cellulose Iα allomorph is more dominant. The presence of strong interactions among the polymers in the primary cell wall and, especially, the relatively high content of pectin and protein, showed that there is a very good possibility of selectively attacking these polymers in the primary cell wall. The first selective reaction chosen was a low degree of sulphonation, applied by an impregnation pretreatment of chips with a very low charge of sodium sulfite (Na2SO3). This selective reaction caused some structural modification of the lignin, a weakening of the interactions between lignin;pectin, lignin;protein and pectin;protein, as well as an increased softening of the sulphonated primary cell wall material, when compared to the unsulphonated primary cell wall material. All this resulted in an increased swelling ability of the material.</p>
193

Spectroscopic data and multivariate analysis : tools to study genetic perturbations in poplar trees

Wiklund, Susanne January 2007 (has links)
In our society in the 21st century one of the greatest challenges is to provide raw materials to the industry in a sustainable way. This requires increased use of renewable raw materials such as wood. Wood is widely used in pulp, paper and textile industries and ongoing research efforts aim to extend the use of wood in e.g. liquid biofuels and green chemicals. At Umeå Plant Science Center (UPSC) poplar trees are used as model systems to study wood formation. The objective is to understand the function of the genes underlying the wood forming process. This knowledge could result in improved chemical and physical wood properties suitable for different industrial processes. This will in turn meet the demands for a sustainable development. This thesis presents tools and strategies to unravel information regarding genetic perturbations in poplar trees by the use of nuclear magnetic resonance (NMR) spectroscopy and multivariate analysis (MVA). Furthermore, gas chromatography/mass spectrometry (GC/MS) is briefly discussed in this context. Multivariate methods to find patterns and trends in NMR data have been used for more than 30 years. In the beginning MVA was applied in pattern recognition studies in order to characterize chemical structures with different ligands and in different solvents. Today, the multivariate methods have developed and the research have changed focus towards the study of biofluids from plant extracts, urine, blood plasma, saliva etc. NMR spectra of biofluids can contain thousands of resonances, originating from hundreds of different compounds. This type of complex data can be hard to summarize and interpret without appropriate tools and require sophisticated strategies for data evaluation. Related fields of research are rapidly growing and are here referred to as metabolomics. Five different research projects are presented which includes analysis of poplar samples where macromolecules such as pectin and also small molecules such as metabolites were analysed by high resolution magic angle spinning (HR/MAS) NMR spectroscopy, 1H-13C HSQC NMR and GC/MS. The discussion topics include modelling of metabolomic time dependencies in combination with genetic variation, validation of orthogonal projections to latent structures (OPLS) models, selection of putative biomarkers related to genetic modification from OPLS-discriminant analysis (DA) models, measuring one of the main components found in the primary cell-walls of poplar i.e. pectin, the use of Fourier transformed two-dimensional (2D) NMR data in OPLS modelling and model complexity in a PLS model.
194

Effect Of Natural Polysaccharides On The Integrity And Texture Of Sugar Based Matrices In Three Dimensional Printing

Baydemir, Tuncay 01 January 2003 (has links) (PDF)
Three dimensional printing (3DP) is one of the most important solid freeform fabrication (SFF) methods that can produce any material with desired 3D shape by using suitable powder-binder formulations. It differs from the standard molding operations in that it can produce a complicated shapes by a software driven instrument in a laminated fashion and the cost is lower. This method can be applied in a very wide area including drug release operations, biomaterial production especially for bone fixation, prototype production for all purposes, wound dressing etc. It can also be used in obtaining edible objects by using natural polysaccharides with water based binders. In this study, it is aimed to understand the gelling behaviour of some of the gelling materials, which are alginates, pectins and carageenans, and effect of various factors on the production of confectionary objects by means of 3DP process. Effect of multivalent cations, especially Ca2+ ion, on the gelling behaviour of these materials are investigated. The egg-box structure obtained between the polymer segments increases the water holding capacity of the materials and much more chewy structures can be obtained. The molecular changes are followed by Fourier Transform infrared spectroscopy (FTIR). In 3DP applications, the composition of powder and binder, pH, temperature, relative humidity (RH) and machine parameters are important factors affecting the texture of the final object. The texture of the produced specimens is examined by using a texture analyzer and maximum force values are given as g/cm at failure. Alginate and carrageenans are found to be more effective in obtaining chewy textures with Ca2+ ion content in sugar based matrices and optimization of machine parameters are performed to obtain a higher resolution on the specimens.
195

Rheo-NMR studies of macromolecules : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Physics at Massey University, Palmerston North, New Zealand

Kakubayashi, Motoko January 2008 (has links)
In this thesis, the effects of simple shear flow on macromolecular structure and interactions are investigated in detail via a combination of Nuclear Magnetic Resonance (NMR) spectroscopy and rheology, namely Rheo-NMR. A specially designed NMR couette shear cell and benchtop shear cell, developed in-house, demonstrated that the direct measurement of the above phenomena is possible. First, to determine whether the shear cells were creating simple shear flow, results were reproduced from literature studies of liquid crystal systems which report shear effects on: Cetyl Trimethyl Ammonium Bromide (CTAB) in deuterium oxide, and Poly(gamma-benzyl-L-glutamate) (PBLG) in m-cresol. Next, the possible conformational changes to protein structure brought about by shear were investigated by applying shear to Bovine -lactogobulin ( -Lg). As the protein was sheared, a small, irreversible conformational change was observed by means of one-dimensional and two-dimensional 1H NMR with reasonable reproducibility. However, no observable change was detected by means of light scattering. A large conformational change was observed after shearing a destabilized -Lg sample containing 10% Trifluoroethanol (TFE) (v/v). From an NMR point of view, the sheared state was similar to the structure of -Lg containing large amounts of -helices and, interestingly, similar to the structure of -Lg containing -sheet amyloid fibrils. Gel electrophoresis tests suggested that the changes were caused by hydrophobic interactions. Unfortunately, this proved to be difficult to reproduce. The effect of shear on an inter-macromolecular interaction was investigated by applying shear during an enzyme reaction of pectin methylesterase (PME) on pectin. Experimental method and analysis developments are described in detail. It was observed that under the conditions studied, shear does not interfere with the de-esterification of pectin with two types of PME, which have different action mechanisms at average shear rates up to 1570 s-1.
196

Rheo-NMR studies of macromolecules : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Physics at Massey University, Palmerston North, New Zealand

Kakubayashi, Motoko January 2008 (has links)
In this thesis, the effects of simple shear flow on macromolecular structure and interactions are investigated in detail via a combination of Nuclear Magnetic Resonance (NMR) spectroscopy and rheology, namely Rheo-NMR. A specially designed NMR couette shear cell and benchtop shear cell, developed in-house, demonstrated that the direct measurement of the above phenomena is possible. First, to determine whether the shear cells were creating simple shear flow, results were reproduced from literature studies of liquid crystal systems which report shear effects on: Cetyl Trimethyl Ammonium Bromide (CTAB) in deuterium oxide, and Poly(gamma-benzyl-L-glutamate) (PBLG) in m-cresol. Next, the possible conformational changes to protein structure brought about by shear were investigated by applying shear to Bovine -lactogobulin ( -Lg). As the protein was sheared, a small, irreversible conformational change was observed by means of one-dimensional and two-dimensional 1H NMR with reasonable reproducibility. However, no observable change was detected by means of light scattering. A large conformational change was observed after shearing a destabilized -Lg sample containing 10% Trifluoroethanol (TFE) (v/v). From an NMR point of view, the sheared state was similar to the structure of -Lg containing large amounts of -helices and, interestingly, similar to the structure of -Lg containing -sheet amyloid fibrils. Gel electrophoresis tests suggested that the changes were caused by hydrophobic interactions. Unfortunately, this proved to be difficult to reproduce. The effect of shear on an inter-macromolecular interaction was investigated by applying shear during an enzyme reaction of pectin methylesterase (PME) on pectin. Experimental method and analysis developments are described in detail. It was observed that under the conditions studied, shear does not interfere with the de-esterification of pectin with two types of PME, which have different action mechanisms at average shear rates up to 1570 s-1.
197

Rheo-NMR studies of macromolecules : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Physics at Massey University, Palmerston North, New Zealand

Kakubayashi, Motoko January 2008 (has links)
In this thesis, the effects of simple shear flow on macromolecular structure and interactions are investigated in detail via a combination of Nuclear Magnetic Resonance (NMR) spectroscopy and rheology, namely Rheo-NMR. A specially designed NMR couette shear cell and benchtop shear cell, developed in-house, demonstrated that the direct measurement of the above phenomena is possible. First, to determine whether the shear cells were creating simple shear flow, results were reproduced from literature studies of liquid crystal systems which report shear effects on: Cetyl Trimethyl Ammonium Bromide (CTAB) in deuterium oxide, and Poly(gamma-benzyl-L-glutamate) (PBLG) in m-cresol. Next, the possible conformational changes to protein structure brought about by shear were investigated by applying shear to Bovine -lactogobulin ( -Lg). As the protein was sheared, a small, irreversible conformational change was observed by means of one-dimensional and two-dimensional 1H NMR with reasonable reproducibility. However, no observable change was detected by means of light scattering. A large conformational change was observed after shearing a destabilized -Lg sample containing 10% Trifluoroethanol (TFE) (v/v). From an NMR point of view, the sheared state was similar to the structure of -Lg containing large amounts of -helices and, interestingly, similar to the structure of -Lg containing -sheet amyloid fibrils. Gel electrophoresis tests suggested that the changes were caused by hydrophobic interactions. Unfortunately, this proved to be difficult to reproduce. The effect of shear on an inter-macromolecular interaction was investigated by applying shear during an enzyme reaction of pectin methylesterase (PME) on pectin. Experimental method and analysis developments are described in detail. It was observed that under the conditions studied, shear does not interfere with the de-esterification of pectin with two types of PME, which have different action mechanisms at average shear rates up to 1570 s-1.
198

Rheo-NMR studies of macromolecules : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Physics at Massey University, Palmerston North, New Zealand

Kakubayashi, Motoko January 2008 (has links)
In this thesis, the effects of simple shear flow on macromolecular structure and interactions are investigated in detail via a combination of Nuclear Magnetic Resonance (NMR) spectroscopy and rheology, namely Rheo-NMR. A specially designed NMR couette shear cell and benchtop shear cell, developed in-house, demonstrated that the direct measurement of the above phenomena is possible. First, to determine whether the shear cells were creating simple shear flow, results were reproduced from literature studies of liquid crystal systems which report shear effects on: Cetyl Trimethyl Ammonium Bromide (CTAB) in deuterium oxide, and Poly(gamma-benzyl-L-glutamate) (PBLG) in m-cresol. Next, the possible conformational changes to protein structure brought about by shear were investigated by applying shear to Bovine -lactogobulin ( -Lg). As the protein was sheared, a small, irreversible conformational change was observed by means of one-dimensional and two-dimensional 1H NMR with reasonable reproducibility. However, no observable change was detected by means of light scattering. A large conformational change was observed after shearing a destabilized -Lg sample containing 10% Trifluoroethanol (TFE) (v/v). From an NMR point of view, the sheared state was similar to the structure of -Lg containing large amounts of -helices and, interestingly, similar to the structure of -Lg containing -sheet amyloid fibrils. Gel electrophoresis tests suggested that the changes were caused by hydrophobic interactions. Unfortunately, this proved to be difficult to reproduce. The effect of shear on an inter-macromolecular interaction was investigated by applying shear during an enzyme reaction of pectin methylesterase (PME) on pectin. Experimental method and analysis developments are described in detail. It was observed that under the conditions studied, shear does not interfere with the de-esterification of pectin with two types of PME, which have different action mechanisms at average shear rates up to 1570 s-1.
199

Rheo-NMR studies of macromolecules : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Physics at Massey University, Palmerston North, New Zealand

Kakubayashi, Motoko January 2008 (has links)
In this thesis, the effects of simple shear flow on macromolecular structure and interactions are investigated in detail via a combination of Nuclear Magnetic Resonance (NMR) spectroscopy and rheology, namely Rheo-NMR. A specially designed NMR couette shear cell and benchtop shear cell, developed in-house, demonstrated that the direct measurement of the above phenomena is possible. First, to determine whether the shear cells were creating simple shear flow, results were reproduced from literature studies of liquid crystal systems which report shear effects on: Cetyl Trimethyl Ammonium Bromide (CTAB) in deuterium oxide, and Poly(gamma-benzyl-L-glutamate) (PBLG) in m-cresol. Next, the possible conformational changes to protein structure brought about by shear were investigated by applying shear to Bovine -lactogobulin ( -Lg). As the protein was sheared, a small, irreversible conformational change was observed by means of one-dimensional and two-dimensional 1H NMR with reasonable reproducibility. However, no observable change was detected by means of light scattering. A large conformational change was observed after shearing a destabilized -Lg sample containing 10% Trifluoroethanol (TFE) (v/v). From an NMR point of view, the sheared state was similar to the structure of -Lg containing large amounts of -helices and, interestingly, similar to the structure of -Lg containing -sheet amyloid fibrils. Gel electrophoresis tests suggested that the changes were caused by hydrophobic interactions. Unfortunately, this proved to be difficult to reproduce. The effect of shear on an inter-macromolecular interaction was investigated by applying shear during an enzyme reaction of pectin methylesterase (PME) on pectin. Experimental method and analysis developments are described in detail. It was observed that under the conditions studied, shear does not interfere with the de-esterification of pectin with two types of PME, which have different action mechanisms at average shear rates up to 1570 s-1.
200

Rheo-NMR studies of macromolecules : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Physics at Massey University, Palmerston North, New Zealand

Kakubayashi, Motoko January 2008 (has links)
In this thesis, the effects of simple shear flow on macromolecular structure and interactions are investigated in detail via a combination of Nuclear Magnetic Resonance (NMR) spectroscopy and rheology, namely Rheo-NMR. A specially designed NMR couette shear cell and benchtop shear cell, developed in-house, demonstrated that the direct measurement of the above phenomena is possible. First, to determine whether the shear cells were creating simple shear flow, results were reproduced from literature studies of liquid crystal systems which report shear effects on: Cetyl Trimethyl Ammonium Bromide (CTAB) in deuterium oxide, and Poly(gamma-benzyl-L-glutamate) (PBLG) in m-cresol. Next, the possible conformational changes to protein structure brought about by shear were investigated by applying shear to Bovine -lactogobulin ( -Lg). As the protein was sheared, a small, irreversible conformational change was observed by means of one-dimensional and two-dimensional 1H NMR with reasonable reproducibility. However, no observable change was detected by means of light scattering. A large conformational change was observed after shearing a destabilized -Lg sample containing 10% Trifluoroethanol (TFE) (v/v). From an NMR point of view, the sheared state was similar to the structure of -Lg containing large amounts of -helices and, interestingly, similar to the structure of -Lg containing -sheet amyloid fibrils. Gel electrophoresis tests suggested that the changes were caused by hydrophobic interactions. Unfortunately, this proved to be difficult to reproduce. The effect of shear on an inter-macromolecular interaction was investigated by applying shear during an enzyme reaction of pectin methylesterase (PME) on pectin. Experimental method and analysis developments are described in detail. It was observed that under the conditions studied, shear does not interfere with the de-esterification of pectin with two types of PME, which have different action mechanisms at average shear rates up to 1570 s-1.

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