Effect of Morphologically Controlled Hematite Nanoparticles on the Properties of Fly Ash Blended Cement

Several types of hematite nanoparticles (α-Fe2O3) have been investigated for their effects on the structure and properties of fly ash (FA) blended cement. All synthesized nanoparticles were found to be of spherical shape, but of different particle sizes ranging from 10 to 195 nm depending on the surfactant used in their preparation. The cement hydration with time showed 1.0% α-Fe2O3 nanoparticles are effective accelerators for FA blended cement. Moreover, adding α-Fe2O3 nanoparticles in FA blended cement enhanced the compressive strength and workability of cement. Nanoparticle size and size distribution were important for optimal filling of various size of pores within the cement structure.This research was funded by The Thailand Science Research and Innovation (TSRI) cooperated with Siam Research and Innovation Co., Ltd., Thailand, for the “Research and Researcher for Industry (RRI) Fund”, contract number PHD 59I0071, which provides for Pantharee Kongsat for her Ph.D. study and research. Open Access fees paid for in whole or in part by the University of Oklahoma Libraries.Ye

การพัฒนาแหล่งท่องเที่ยวประเภทชายหาดในจังหวัดภูเก็ต เพื่อการท่องเที่ยวอย่างยั่งยืน กรณีศึกษา หาดป่าตอง หาดกะตะ หาดกระรน

Thesis (M.B.A., Hospitality and Tourism Management)--Prince of Songkla University, 200

Molecular modelling of B-barrel outer membrane proteins

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Molecular modelling of beta-barrel outer membrane proteins

In Gram-negative bacteria, the Outer membrane (OM) acts as a first barrier to screen unwanted compounds whilst enabling ions and very small solutes to diffuse into the cell. Most of nutrients and essential ions are effectively transported across a membrane via the outer membrane proteins (OMPs). The water-filled β- barrel OMPs are called porins. These pores are classified into two groups, non- specific and substrate-specific porins. Each of them has different mechanisms to facilitate its substrate translocation. To reveal the process of substrate permeation and selectivity in microscopic detail, molecular dynamics (MD) simulations and applications were performed in this thesis. The studies in this thesis focus on a series of classical porins. These proteins share similar feature where extracellular loop(s) (generally loop 3 (L3)) is folded into the middle of the pore and act as a constriction site which is important for substrate specificity and selectivity. The studies firstly concentrate on the structural properties and dynamics of the general trimeric porins, OmpC and OmpF whose sequences share 60% identity. OmpC and OmpF are found to have similar mechanism of latching loop (L2) to maintain trimeric stability. The smaller pore size allows OmpC to be more cation-selective than OmpF. Additionally, the major driving force for cation permeation in both porins is not from electrostatic properties. This differs from the phosphate-selective porin, trimeric OprP, where a phosphate diffusion depends on electrostatic interactions with positively charged pore-lining residues. The charge brush-like behavior of interior Arg and Lys residues plays a major role in phosphate selectivity. Also, the free energy profiles (PMF) reveal two key regions that are important for differentiating phosphate from other anions. The brush-like mechanism of OprP were also implanted to the simplified model pores in order to determine the possibility of transferring phosphate-selective properties of OprP to a model which may be useful for future design of nanopores. It is found that the duplication of functional residues and pore cavity can turn a model into the highly phosphate-selective pore. Importantly, the phosphate-binding affinity is dependent on the ability of the pore to interfere and occupy the hydration shell of a translocating phosphate where such ability can be maximized by an increase in sidechain flexibility. In case of uptake of more complex substrates, OpdK also employs a constriction site to select its substrate, aromatic vanillate (VNL) with total charge of -1. Unlike ion-specific porins, the free VNL is attracted by polar and aromatic interactions and sequentially directed through the periplasmic vestibule by charged residues insides the pore. The correct orientation of VNL on arrival is crucial for OpdK to recognize and enable the permeation process.</p

Molecular modelling of beta-barrel outer membrane proteins

In Gram-negative bacteria, the Outer membrane (OM) acts as a first barrier to screen unwanted compounds whilst enabling ions and very small solutes to diffuse into the cell. Most of nutrients and essential ions are effectively transported across a membrane via the outer membrane proteins (OMPs). The water-filled β- barrel OMPs are called porins. These pores are classified into two groups, non- specific and substrate-specific porins. Each of them has different mechanisms to facilitate its substrate translocation. To reveal the process of substrate permeation and selectivity in microscopic detail, molecular dynamics (MD) simulations and applications were performed in this thesis. The studies in this thesis focus on a series of classical porins. These proteins share similar feature where extracellular loop(s) (generally loop 3 (L3)) is folded into the middle of the pore and act as a constriction site which is important for substrate specificity and selectivity. The studies firstly concentrate on the structural properties and dynamics of the general trimeric porins, OmpC and OmpF whose sequences share 60% identity. OmpC and OmpF are found to have similar mechanism of latching loop (L2) to maintain trimeric stability. The smaller pore size allows OmpC to be more cation-selective than OmpF. Additionally, the major driving force for cation permeation in both porins is not from electrostatic properties. This differs from the phosphate-selective porin, trimeric OprP, where a phosphate diffusion depends on electrostatic interactions with positively charged pore-lining residues. The charge brush-like behavior of interior Arg and Lys residues plays a major role in phosphate selectivity. Also, the free energy profiles (PMF) reveal two key regions that are important for differentiating phosphate from other anions. The brush-like mechanism of OprP were also implanted to the simplified model pores in order to determine the possibility of transferring phosphate-selective properties of OprP to a model which may be useful for future design of nanopores. It is found that the duplication of functional residues and pore cavity can turn a model into the highly phosphate-selective pore. Importantly, the phosphate-binding affinity is dependent on the ability of the pore to interfere and occupy the hydration shell of a translocating phosphate where such ability can be maximized by an increase in sidechain flexibility. In case of uptake of more complex substrates, OpdK also employs a constriction site to select its substrate, aromatic vanillate (VNL) with total charge of -1. Unlike ion-specific porins, the free VNL is attracted by polar and aromatic interactions and sequentially directed through the periplasmic vestibule by charged residues insides the pore. The correct orientation of VNL on arrival is crucial for OpdK to recognize and enable the permeation process.</p

Effects of dietary inclusion of palm kernel cake on nutrient utilization, rumen fermentation characteristics and microbial populations of goats fed Paspalum plicatulum hay-based diet

To investigate the effects of inclusion of palm kernel cake (PKC) in the diets on intake, digestibility, rumen fermentationcharacteristics, nitrogen balance and microbial N supply, five goats (initial BW = 20±1 kg) were randomly assigned to a55 Latin square design to receive five diets, T1 = concentrate with 15% PKC, T2 = 25% PKC, T3 = 35% PKC, T4 = 45% PKCand T5 = 55% PKC, of dietary dry matter, respectively. Plicatulum hay was offered ad libitum as the roughage. A metabolismtrial lasted for 21 days during which live weight changes and feed intakes were measured. Based on this experiment, therewere no significant differences (p>0.05) among treatment groups regarding dry matter (DM) intake and digestion coefficientsof DM, organic matter, crude protein, neutral detergent fiber and acid detergent fiber, except in T4 and T5 (45 and 55% PKC)which had lower (p0.05), however the concentration of total volatile fatty acids and protozoal populations were slightly lower forgoats fed inclusion of 45-55% PKC as compared with other treatments. Based on this experiment, it could be concluded thatthe optimal level of PKC in concentrate should be 15-35% for goats fed with plicatulum hay and that it may be an effectivemeans of exploiting the use of local feed resources for goat production

Biomimetic design of a brush-like nanopore: simulation studies.

Combining a high degree of selectivity and nanoscale dimensions, biological pores are attractive potential components for nanotechnology devices and applications. Biomimetic design will facilitate production of stable synthetic nanopores with defined functionality. Bacterial porins offer a good source of possible templates for such nanopores as they form stable, selective pores in lipid bilayers. Molecular dynamics simulations have been used to design simple model nanopores with permeation free energy profiles that can be made to mimic a template protein, the OprP porin, which forms pores selective for anions. In particular, we explored the effects of varying the nature of pore-lining groups on free energy profiles for phosphate and chloride ions along the pore axis and the total charge of the permeation pathway of the pore. Cationic side chains lining the model nanopore are required to model the local detail of the OprP permeation landscape, whereas the total charge contributes to its magnitude. These studies indicate that a locally accurate biomimetic design has captured the essentials of the structure/function relationship of the parent protein