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You searched for subject:(lipid compression). Showing records 1 – 3 of 3 total matches.

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University of Kansas

1. Beaven, Andrew H. On Bilayer Deformation Energetics With and Without Gramicidin A Channel.

Degree: PhD, Chemistry, 2017, University of Kansas

Lipid membranes are not simply passive barriers. Embedded proteins are coupled to the membrane and can deform the surrounding bilayer, which incurs an energetic penalty. To minimize these penalties, proteins are known to tilt, aggregate, and experience major conformation changes. The degree to which the protein is influenced by the bilayer is dependent on the bilayer material properties and protein-bilayer coupling strength, for example. In this dissertation, the effects of bilayer material properties and protein-bilayer coupling are detailed using gramicidin A channel. This simple channel experiences one major conformational change, its transmembrane dimerization, which produces a bilayer deformation if the bilayer and dimer do not have the same hydrophobic lengths. Herein, molecular dynamics simulations are used to describe bilayer material properties, channel-bilayer coupling, and general lipid energetics with and without gramicidin A. Advisors/Committee Members: Im, Wonpil (advisor), Thompson, Ward H (advisor), Deeds, Eric J (cmtemember), Kuczera, Krzysztof (cmtemember), Rivera, Mario (cmtemember).

Subjects/Keywords: Biophysics; Physical chemistry; gramicidin A; lipid bending; lipid compression; lipid energetics; molecular dynamics

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APA (6th Edition):

Beaven, A. H. (2017). On Bilayer Deformation Energetics With and Without Gramicidin A Channel. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/25998

Chicago Manual of Style (16th Edition):

Beaven, Andrew H. “On Bilayer Deformation Energetics With and Without Gramicidin A Channel.” 2017. Doctoral Dissertation, University of Kansas. Accessed October 22, 2019. http://hdl.handle.net/1808/25998.

MLA Handbook (7th Edition):

Beaven, Andrew H. “On Bilayer Deformation Energetics With and Without Gramicidin A Channel.” 2017. Web. 22 Oct 2019.

Vancouver:

Beaven AH. On Bilayer Deformation Energetics With and Without Gramicidin A Channel. [Internet] [Doctoral dissertation]. University of Kansas; 2017. [cited 2019 Oct 22]. Available from: http://hdl.handle.net/1808/25998.

Council of Science Editors:

Beaven AH. On Bilayer Deformation Energetics With and Without Gramicidin A Channel. [Doctoral Dissertation]. University of Kansas; 2017. Available from: http://hdl.handle.net/1808/25998


The Ohio State University

2. Zulkurnain, Musfirah. Crystallization of Lipids under High Pressure for Food Texture Development.

Degree: PhD, Food Science and Technology, 2017, The Ohio State University

In recent years, high pressure treatment of food has become increasingly important in food industry. Thermodynamically, high pressure can accelerate phase transition by increasing melting temperature of lipids. The objectives of this study were to crystallize fats under high pressure with controlled thermal conditions and to study the effects of processing (pressure, maximum temperature under pressure (Tmax), holding time and pulsing) and product (fat composition and salt addition) parameters on kinetics of crystallization, physical and structural properties of model fats. The feasibility of crystallizing a binary fat mixture of fully hydrogenated soybean oil (FHSBO) at 30% w/w with soybean oil was investigated by cooling the melt under high pressure under controlled thermal conditions. Using face-centered central composite design, the influence of process parameters (pressure, maximum temperature under pressure (Tmax), holding time and pulsing) on rheological and oil binding capacity of the model fat was evaluated. Among the parameters investigated, pressure (100-600 MPa) and Tmax (70-90 ºC) influenced storage modulus (G’), yield stress and percent oil loss of the sample. Under controlled pressure-thermal conditions, a single compression cycle with 10 min holding time was sufficient to impart a significant texture improvement compared to atmospheric crystallization at 30 min. Subsequently, the effect of high pressure (100-600 MPa) on the onset of crystallization during adiabatic compression or subsequent isobaric cooling was studied over various maximum product temperature (Tmax; 70, 80 or 90 ºC). At low pressure level, when crystallization temperature (Tc) was below Tmax, crystallization was observed under isobaric cooling. Increase in pressure increased Tc resulting in decreased induction time and reduction in microstructure size. At high pressure level (P>300 MPa), increase in Tc above Tmax resulted in crystallization during rapid adiabatic compression which decreased induction time and formed high number of small crystals. Finally, the effect of solid mass fraction (10, 20, and 30% w/w FHSBO) and addition of salt (1% w/w) in the model fats on their kinetics and crystallization behaviors were studied for different pressure levels (0.1, 100, 300, 600 MPa) at an initial temperature of 75 ºC. Using thermometry approach, phase diagrams of model fats were established. Induction time of all model fats significantly (p<0.05) reduced when onset of crystallization observed during adiabatic compression at 600 MPa instead of isobaric cooling at lower pressure levels. Increase in solid mass fraction increased crystallization temperature and reduced induction time. Results shows microstructure size increased with increase in solid mass fraction in high pressure crystallized samples but the opposite effect in control samples. Addition of salt reduced crystal size, increased solid fat content (SFC) and shear storage modulus (G’) of the high pressure crystallized samples. This effect was prominent with reduction in solid mass… Advisors/Committee Members: Balasubramaniam, VM (Advisor), Maleky, Farnaz (Advisor).

Subjects/Keywords: Food Science; high pressure crystallization, lipid crystallization, hydrostatic pressure, adiabatic compression, isobaric cooling, microstructure, nanostructure, small angle X-ray scattering, polymorphism, salt, thermometry

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APA (6th Edition):

Zulkurnain, M. (2017). Crystallization of Lipids under High Pressure for Food Texture Development. (Doctoral Dissertation). The Ohio State University. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=osu1500557652861233

Chicago Manual of Style (16th Edition):

Zulkurnain, Musfirah. “Crystallization of Lipids under High Pressure for Food Texture Development.” 2017. Doctoral Dissertation, The Ohio State University. Accessed October 22, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500557652861233.

MLA Handbook (7th Edition):

Zulkurnain, Musfirah. “Crystallization of Lipids under High Pressure for Food Texture Development.” 2017. Web. 22 Oct 2019.

Vancouver:

Zulkurnain M. Crystallization of Lipids under High Pressure for Food Texture Development. [Internet] [Doctoral dissertation]. The Ohio State University; 2017. [cited 2019 Oct 22]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1500557652861233.

Council of Science Editors:

Zulkurnain M. Crystallization of Lipids under High Pressure for Food Texture Development. [Doctoral Dissertation]. The Ohio State University; 2017. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1500557652861233


University of Florida

3. Bhase, Hrishikesh. Formation of Calcium Phosphate Crystals under Lipid Monolayers.

Degree: MS, Chemistry, 2010, University of Florida

This study looks at the precipitation of calcium phosphate crystals at phospholipid Langmuir monolayers. Urinary stones are commonly composed of an inorganic component, calcium phosphate, or calcium oxalate and an organic matrix of lipids, carbohydrates, and proteinaceous matter. Hyperoxaluria, elevated oxalate concentration in the kidney, is a condition frequently associated with individuals suffering from kidney stones. This condition causes the breakdown of membranes and creates free radicals at the cellular surface. Once free radicals are generated, lipid peroxidation begins to occur which further leads to the hydrolysis of phospholipids. Hydrolysis can also be caused by an enzyme called phospholipase A2, which hydrolyzes the sn-2 position of a phospholipid. Two of the products at the cell surface when hydrolysis occurs are a single chain lysolipid and also a fatty acid. In this study, products of lipid hydrolysis are examined for their effect on calcium phosphate precipitation using Langmuir monolayers as model lipid membrane assemblies. Brewster angle microscopy is employed to monitor the calcium phosphate crystals which appear as a bright spots at the air/water interface. Crystal precipitation was monitored at monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), palmitic acid (PA), the binary mixture of DPPC:PA, and DPPC:22-carbon chain lysophospholipid (22:0 Lyso PC) and the ternary mixture of DPPC: PA: lyso PC in liquid condensed (LC) and liquid expanded (LE) phases. It is found that a ternary mixture of DPPC and its hydrolysis products, a lysolipid and a fatty acid, cause a significant increase in heterogeneous calcium phosphate precipitation when compared to DPPC alone. It is demonstrated that the fatty acid PA generated during lipid hydrolysis causes a significant increase in the extent of heterogeneous nucleation of calcium phosphate from supersaturated solutions. The results imply a possible link between break down of phospholipid into its hydrolysis products and calcium phosphate precipitation. We also studied a ternary mixture using Dipalmitoylphosphatidylcholine (DPPC), arachidic acid (AA), and a 22-carbon chain lysophospholipid (22:0:Lyso PC) to see the effect of chain length of fatty acid on calcium phosphate precipitation. It was observed that only the short chain fatty acid generated during lipid hydrolysis causes a significant increase in the extent of heterogeneous nucleation of calcium phosphate. ( en ) Advisors/Committee Members: Talham, Daniel R. (committee chair), Young, Vaneica Y. (committee member), Williams, Kathryn R. (committee member).

Subjects/Keywords: Calcium; Calcium phosphates; Crystals; Fatty acids; Hydrolysis; Image compression; Isotherms; Lipids; Monomolecular films; Phosphates; acid, angle, brewster, calcium, cell, crstals, dppc, fatty, hydrolysis, kidney, lipid, membrane, microscope, monolayer, phosphate, stones

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Bhase, H. (2010). Formation of Calcium Phosphate Crystals under Lipid Monolayers. (Masters Thesis). University of Florida. Retrieved from http://ufdc.ufl.edu/UFE0042332

Chicago Manual of Style (16th Edition):

Bhase, Hrishikesh. “Formation of Calcium Phosphate Crystals under Lipid Monolayers.” 2010. Masters Thesis, University of Florida. Accessed October 22, 2019. http://ufdc.ufl.edu/UFE0042332.

MLA Handbook (7th Edition):

Bhase, Hrishikesh. “Formation of Calcium Phosphate Crystals under Lipid Monolayers.” 2010. Web. 22 Oct 2019.

Vancouver:

Bhase H. Formation of Calcium Phosphate Crystals under Lipid Monolayers. [Internet] [Masters thesis]. University of Florida; 2010. [cited 2019 Oct 22]. Available from: http://ufdc.ufl.edu/UFE0042332.

Council of Science Editors:

Bhase H. Formation of Calcium Phosphate Crystals under Lipid Monolayers. [Masters Thesis]. University of Florida; 2010. Available from: http://ufdc.ufl.edu/UFE0042332

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