FP-GR-INJECTIVE MODULES

In this paper, we give some characterizations of FP-grinjective R-modules and graded right R-modules of FP-gr-injective dimension at most n. We study the existence of FP-gr-injective envelopes and FP-gr-injective covers. We also prove that (1) (⊥gr-FI, gr-FI) is a hereditary cotorsion theory if and only if R is a left gr-coherent ring, (2) If R is right gr-coherent with FP-gr-id(RR) ≤ n, then (gr-FIn, gr-F n⊥) is a perfect cotorsion theory, (3) (⊥gr-FIn, gr-FIn) is a cotorsion theory, where gr-FI denotes the class of all FP-gr-injective left R-modules, gr-FIn is the class of all graded right R-modules of FP-gr-injective dimension at most n. Some applications are given

TRIANGULAR MATRIX REPRESENTATIONS OF SKEW MONOID RINGS

Let R be a ring and S a u.p.-monoid. Assume that there is a monoid homomorphism &#945; : S &#8594; Aut (R). Suppose that &#945; is weakly&#12288;rigid and lR(Ra) is pure as a left ideal of R for every element a &#8712; R. Then the skew monoid ring R*S induced by &#945; has the same triangulating dimension as R. Furthermore, if R is a PWP ring, then so is R*S.</p

Radial Spokes-A Snapshot of the Motility Regulation, Assembly, and Evolution of Cilia and Flagella

Propulsive forces generated by cilia and flagella are used in events that are critical for the thriving of diverse eukaryotic organisms in their environments. Despite distinctive strokes and regulations, the majority of them adopt the 9+2 axoneme that is believed to exist in the last eukaryotic common ancestor. Only a few outliers have opted for a simpler format that forsakes the signature radial spokes and the central pair apparatus, although both are unnecessary for force generation or rhythmicity. Extensive evidence has shown that they operate as an integral system for motility control. Recent studies have made remarkable progress on the radial spoke. This review will trace how the new structural, compositional, and evolutional insights pose significant implications on flagella biology and, conversely, ciliopathy

Synthesis and Structure-Property Relationship of Phosphonium Polymers

In Chapter 1, recent advances in thermally stable polymers and polyectrolytes are reviewed, with an emphasis on elucidating the extent to which structural variations influence thermal stability. Specific polymers such as polybenzimidazoles, polyimides and phosphonium polyelectrolytes (PELs) were selected to illustrate how properties can be tuned through modification of side chain, main chain and functional group composition. Recent development on PPELs are a particular emphasis in this chapter, and this serves as an introduction to the state-of-the-art prior to work conducted in the current dissertation. The work presented in Chapters 2 and 3 is centered on structure-property relationship studies employing PELs that were prepared via condensation polymerization. The properties of PELs were evaluated in an effort to assess the influence of both side chain and main chain composition. The influence of side chain was examined by comparing properties of a series of PELs having hydrophobic octyloxy side chains to those of structural analogues lacking the side chains. The influence exerted by backbone flexibility/length of spacer between charges was revealed by comparing properties of two series of polymers with a variable number of methylene units between phosphonium charge-bearing sites. Side chain composition and spacing between phosphonium units lead to noteworthy influence on thermal stability, glass transition and crystallinity. The molecular structure of PELs also correlates with trends in film morphology and critical surface energy of PEL dip-cast films. Sensitivity of morphology to humidity or water in the casting solvent was observed. The relationship between side chain and spacer on bactericidal activity against Staphylococcus aureus and Escherichia coli was assessed. Supramolecular assembly of films via layer-by-layer deposition of PELs alternating with anionic polythiophene derivative layers was also undertaken. The linearity of film growth, amount of material deposited in each bilayer, polycation:polyanion ratio and film roughness all show noteworthy trends that depend on both the presence/absence of side chains and on spacing between ionic centers. Chapters 4 and 5 detail work on a series of phosphonium-containing covalent organic frameworks (COFs) (P1-P4) prepared via copolymerization of 1,4-diacetylbenze and bis(4-acetylphenyl)diphenylphosphonium bromide in various ratios. The influence of COF composition on thermal stability, alkaline stability, char yield, water uptake, specific surface area, and CO2 affinity was assessed in this work. The phosphonium COFs show good thermal stability with Td,5% up to 435 °C. Increasing the phosphonium content (50%) leads to concomitantly better alkaline stability upon challenging the material in 6 M NaOH(aq) at 65 °C for 120 h. The specific surface areas estimated by BET for the materials are in the range of 3-63 m2/g. Decreasing phosphonium content leads to larger specific areas due to a more open-structure solid. P3, in which 33% of monomers comprise a phosphonium moiety, exhibited the highest CO2 affinity

Popularizing Nutrition Education to Improve Student Nutrition Literacy

Health is an eternal theme for mankind. The World Health Organization (1986) defines health as a state of physical, mental, and social wellbeing of the individual. Nutrition is one of the major external determinants of human health. The concept of “nutrition literacy” was first raised by Tenhave et al. (1997) in their article titled “Literacy Assessment in a Cardiovascular Nutrition Education Setting.” Silk et al. (2008) defined nutrition literacy as the degree to which individuals have the capacity to obtain, process, and understand nutrition information and skills needed in order to make appropriate nutrition decisions. Adequate nutrition literacy is beneficial for the individual obtaining correct dietary information, improving their dietary patterns and preventing chronic diseases

Long-Range Side Chain-Main Chain Hydrogen Bonds: A Molecular Signature of the TIM Barrel Architecture: A Dissertation

The hydrophobic effect and hydrogen bonding interactions have long been considered to be the dominant forces in protein folding. However, the contribution of hydrogen bonds to stabilizing proteins has been difficult to clarify. As the intramolecular hydrogen bonds are formed in place of hydrogen bonds with solvent during folding, measures of stability fail to give a significant change in free energy. Previous studies on hydrogen bonding interactions have shown that they are only marginally important. Three long-range side chain-main chain hydrogen bonds have been found in the alpha subunit of tryptophan synthase (αTS), a (βα)8TIM barrel protein. These long-range noncovalent interactions connect either the N-terminus of one β-strand with the C-terminus of the succeeding and anti-parallel α-helix (F19-D46 and I97-D124) or the N-terminus of an α-helix with the C-terminus of the succeeding β-strand (A103-D130). By analogy, these interactions are designated as βα- or αβ-hairpin clamps. Surprisingly, the removal of any one of these clamp interactions, by replacement of the aspartic acid with alanine, results in significantly decreased thermodynamic stability for the native state and a substantial loss of secondary structure. When compared to several other side chain-side chain and short-range side chain-main chain interactions in αTS, these hairpin clamps clearly play a unique role in the structure and stability of αTS. The generality of these observations for βα-hairpin clamps in TIM barrel proteins was tested by experimental analysis of the clamps in a pair of homologous indole-3-glycerol phosphate synthase (IGPS) TIM barrels of low sequence identity. The results suggest that only the subset of conserved βα-hairpin clamps with hydrogen bond length less than 2.80 Å make substantive contributions to stability and/or structure. Those clamps with longer hydrogen bonds make modest contributions to stability and structure, similar to other types of side chain-main chain or side chain-side chain hydrogen bonds. The role of these clamps in defining the structures of the super-family of TIM barrel proteins was examined by a survey of 71 TIM barrel proteins from the structural database. Conserved features of βα-hairpin clamps are consistent with a 4-fold symmetry, with a predominance of main chain amide hydrogen bond donors near the N-terminus of the odd-number β-strands and side chain hydrogen bond acceptors in the loops between the subsequent α-helices and even-numbered β-strands. In this configuration, the clamps provide an N-terminal cap to odd-number β- strands in the β-barrel. Taken together, these findings suggest that βα-hairpin clamps are a vestigial signature of the fundamental βαβ building block for the (βα)8 motif and an integral part of the basic TIM barrel architecture. The relative paucity of βα-hairpin clamps remaining in TIM barrel structures and their variable contributions to stability imply that other determinants for structure and stability of the barrel have evolved to render a subset of the clamp interactions redundant. Distinct sequence preferences for the partners in the βα-hairpin clamps and the neighboring segments may be useful in enhancing algorithms for structure prediction and for engineering stability in TIM barrel proteins