Per-Spectral Characterizations of Bicyclic Networks

Spectral techniques are used for the study of several network properties: community detection, bipartition, clustering, design of highly synchronizable networks, and so forth. In this paper, we investigate which kinds of bicyclic networks are determined by their per-spectra. We find that the permanental spectra cannot determine sandglass graphs in general. When we restrict our consideration to connected graphs or quadrangle-free graphs, sandglass graphs are determined by their permanental spectra. Furthermore, we construct countless pairs of per-cospectra bicyclic networks

Elucidating the Role of Physiochemical Properties on Gas Transport in Ionic Liquids and Porous Liquids for Carbon Dioxide Separations

The rising concentration of atmospheric carbon dioxide to unprecedented levels has prompted global initiatives to reduce carbon emissions from anthropogenic sources. However, technologies to support these initiatives are somewhat limited and are not the most economically advantageous for cost to capture ratios. Current strategies using liquid amines are corrosive and have a significant thermal penalty for regeneration. There is a need for a passive, efficient approach for carbon dioxide sequestration. Rather than harnessing a chemical reaction, which requires added energy to release carbon dioxide and reuse the sorbent, other materials that operate by a mechanism of physical interactions will be explored.Membranes are a low energy alternative for gas separations but require thoughtful design to circumvent the inherent permeability-selectivity tradeoff. To mitigate this effect, ionic liquids (ILs) were functionalized to enhance carbon dioxide selectivity between gases of interest. Cations were designed to reduce cation-anion interactions and increase free volume in efforts to enhance permeability, but gains were minimized due to increased viscosity of the new ILs. New relationships between fractional free volume and gas solubility were examined.Mixed matrix mediums have recently gained prominence for their ability to bridge the gap between permeability and selectivity. Ionic liquid absorbents are adept at selectively separating light gases, while porous adsorbents with large surface areas have high capacities at low partial pressures. Porous liquids are a new class of fluid sorbents that combine the positive attributes of both components. Through judicious selection of the liquid and dispersed colloidal solid, permanent cavities can be achieved in the liquid phase. A porous liquid was created using zeolitic imidazolate framework nanocrystals incorporated into a bulky ionic liquid. The composite exhibited distinct enhancements in both gas solubility and selectivity.In situ Fourier transform infrared spectroscopy measurements were conducted to investigate the mode of carbon dioxide absorption in the porous liquids. While the liquid phase remains relatively unchanged, incorporation of carbon dioxide leads to slight structural fluctuations in the porous solid and liquid. The presence of both dissolved and gaseous carbon dioxide was detected, and preliminary quantitation was completed

A Small Chaperone Improves Folding and Routing of Rhodopsin Mutants Linked to Inherited Blindness

The autosomal dominant form of retinitis pigmentosa (adRP) is a blindness-causing conformational disease largely linked to mutations of rhodopsin. Molecular simulations coupled to the graph-based protein structure network (PSN) analysis and in vitro experiments were conducted to determine the effects of 33 adRP rhodopsin mutations on the structure and routing of the opsin protein. The integration of atomic and subcellular levels of analysis was accomplished by the linear correlation between indices of mutational impairment in structure network and in routing. The graph-based index of structural perturbation served also to divide the mutants in four clusters, consistent with their differences in subcellular localization and responses to 9-cis retinal. The stability core of opsin inferred from PSN analysis was targeted by virtual screening of over 300,000 anionic compounds leading to the discovery of a reversible orthosteric inhibitor of retinal binding more effective than retinal in improving routing of three adRP mutants

Discrete Mathematics and Symmetry

Some of the most beautiful studies in Mathematics are related to Symmetry and Geometry. For this reason, we select here some contributions about such aspects and Discrete Geometry. As we know, Symmetry in a system means invariance of its elements under conditions of transformations. When we consider network structures, symmetry means invariance of adjacency of nodes under the permutations of node set. The graph isomorphism is an equivalence relation on the set of graphs. Therefore, it partitions the class of all graphs into equivalence classes. The underlying idea of isomorphism is that some objects have the same structure if we omit the individual character of their components. A set of graphs isomorphic to each other is denominated as an isomorphism class of graphs. The automorphism of a graph will be an isomorphism from G onto itself. The family of all automorphisms of a graph G is a permutation group

Synthesis and Characterization of Mussel Adhesive Peptides

Mussels, marine organisms, attach to underwater surfaces by making a byssus, which is an extra-corporeal bundle of tiny tendons attached distally to a foreign surface and proximally by insertion of the root into the byssal retractor muscles. The interaction exterior of byssus and marine surface is an adhesive plaque that contains different proportion of five mytilus edulis adhesive proteins (mefp-1 to 5). Relatively high contains of Lys, L-3,4-dihydroxyphenylalanine (DOPA), trans-4-hydroxyproline, and trans-2,3-cis-3,4-dihydroxyproline formulates MAPs as an adhesive protein. Derivation of synthetic bio-adhesives from MAPs have been limited due to fairly unsuccessful synthesize adhesive polypeptides and poor yield in extraction from biological source. In this study, syntheses of mussel adhesive protein analogues have been performed. Several oligomers and polymers were synthesized with the comibation of bicyclic dipeptide building blocks, DOPA, Lys and Tyr. Use of bicyclic dipeptide building block has advantage over use of Hyp and Ser as former is expensive and latter needs side chain protection. Molecular structure, mass and size of these polymers were characterized using various techniques like NMR, MALDI, and GPC. The adhesive property of these polymers was tested using DOSY NMR experiment and AFM spectroscopy. Results obtained using AFM shows adhesion of poly-Lys-Bic-Tyr to graphite surface. These results open up a wide area in which finely tuned adhesive synthetic bio-polymers can be synthesized

Synthesis and Characterization of Mussel Adhesive Peptides

Mussels, marine organisms, attach to underwater surfaces by making a byssus, which is an extra-corporeal bundle of tiny tendons attached distally to a foreign surface and proximally by insertion of the root into the byssal retractor muscles. The interaction exterior of byssus and marine surface is an adhesive plaque that contains different proportion of five mytilus edulis adhesive proteins (mefp-1 to 5). Relatively high contains of Lys, L-3,4-dihydroxyphenylalanine (DOPA), trans-4-hydroxyproline, and trans-2,3-cis-3,4-dihydroxyproline formulates MAPs as an adhesive protein. Derivation of synthetic bio-adhesives from MAPs have been limited due to fairly unsuccessful synthesize adhesive polypeptides and poor yield in extraction from biological source. In this study, syntheses of mussel adhesive protein analogues have been performed. Several oligomers and polymers were synthesized with the comibation of bicyclic dipeptide building blocks, DOPA, Lys and Tyr. Use of bicyclic dipeptide building block has advantage over use of Hyp and Ser as former is expensive and latter needs side chain protection. Molecular structure, mass and size of these polymers were characterized using various techniques like NMR, MALDI, and GPC. The adhesive property of these polymers was tested using DOSY NMR experiment and AFM spectroscopy. Results obtained using AFM shows adhesion of poly-Lys-Bic-Tyr to graphite surface. These results open up a wide area in which finely tuned adhesive synthetic bio-polymers can be synthesized

Effects of multi-functional additives during foam extrusion of wheat gluten materials

To broaden the range in structures and properties, and therefore the applicability of sustainable foams based on wheat gluten expanded with ammonium-bicarbonate, we show here how three naturally ocurring multifunctional additives affect their properties. Citric acid yields foams with the lowest density (porosity of similar to 50%) with mainly closed cells. Gallic acid acts as a radical scavenger, yielding the least crosslinked/ aggregated foam. The use of a low amount of this acid yields foams with the highest uptake of the body-fluid model substance (saline, similar to 130% after 24 hours). However, foams with genipin show a large and rapid capillary uptake (50% in one second), due to their high content of open cells. The most dense and stiff foam is obtained with one weight percent genipin, which is also the most crosslinked. Overall, the foams show a high energy loss-rate under cyclic compression (84-92% at 50% strain), indicating promising cushioning behaviour. They also show a low compression set, indicating promising sealability. Overall, the work here provides a step towards using protein biofoams as a sustainable alternative to fossil-based plastic/rubber foams in applications where absorbent and/or mechanical properties play a key role

Novel Bioplastics and biocomposites from Vegetable Oils

Polymeric materials have been prevalent in our everyday lives for quite a long time. Most of today's polymeric materials are derived from nonrenewable petroleum-based feedstocks. Instabilities in the regions where petroleum is drilled, along with an increased demand in petroleum, have driven the price of crude oil to record high prices. This, in effect, increases the price of petroleum-based polymeric materials, which has caused a heightened awareness of renewable alternatives for polymeric feedstocks. Cellulose, starch, proteins and natural oils have all been examined as possible polymeric feedstocks. Natural oils are commercially available on a large scale and are relatively cheap. It is projected that the U.S. alone will produce 21 billion pounds of soybean oil in the period 2008/2009. Natural oils also have the advantages of inherent biodegradability, low toxicity, high purity and ready availability. Most natural oils possess a triglyceride structure as shown in Figure 1. Most natural oils have a unique distribution of fatty acid side chains, along with varying degrees of unsaturation per triglyceride. Common fatty acid side chains in naturally occurring oils are palmitic acid (C16:0), a 16 carbon fatty acid with no unsaturation; stearic acid (C18:0), an 18 carbon fatty acid with no unsaturation; oleic acid (C18:1), an 18 carbon fatty acid with one double bond; linoleic acid (C18:2), an 18 carbon fatty acid with two double bonds; and linolenic acid (C18:3), an 18 carbon fatty acid with three double bonds. Of course, there are other fatty acids with varying degrees of unsaturation, but their abundance is usually minimal. All of the unsaturated fatty acids mentioned have naturally occurring cis double bonds, which is common for most unsaturated fatty acids. In addition, the afore mentioned fatty acids have the first double bond at the position of carbon 9 (C9), followed by carbon 12 (C12), if there are two degrees of unsaturation, then at carbon 15 (C15), if there are three degrees of unsaturation. In addition, the double bonds are not in conjugation. Table 1 gives the fatty acid make-up of linseed oil. It can be seen that linseed oil has an average of 6.0 double bonds per triglyceride. Its fatty acid content consists of 5.4% palmitic acid (C16:0), 3.5% stearic acid (C18:0), 19% oleic acid (C18:1), 24 % linoleic acid (C18:2) and 47% linolenic (C18:3). Table 1 also gives the fatty acid composition and varying degrees of unsaturation for various other naturally-occurring natural vegetable oils. The regions of unsaturation in natural oils allow for interesting polymer chemistry to take place. Some of this interesting polymer science, however, involves chemical modification of the regions of unsaturation. Acrylated epoxidized soybean oil (AESO) is prepared by epoxidation of the double bonds, followed by ring opening with acrylic acid. The resulting oil has both acrylate groups and hydroxyl groups. Wool and colleagues have further reacted the hydroxyl groups within the oil with maleic anhydride to produce maleated acrylated epoxidized soybean oil (MAESO). The MAESO has been copolymerized with styrene free radically to produce promising thermosetting sheet molding resins. Petrovi? and co-workers have directly ring opened the epoxidized oil to produce polyols that produce promising polyurethanes through condensation polymerization with diisocyanates. Our group's work initially focused on direct cationic copolymerization of the double bonds or conjugated double bonds of natural oils with monomers, such as styrene and divinylbenzene, to produce promising thermosetting resins. The only modification of the oils that was carried out in these studies was conjugation of the double bonds to enhance the reactivity of the oil. This work has been expanded recently with the incorporation of glass fiber to produce promising composites. We have also explored thermal polymerization techniques to make novel thermosets. This dissertation is divided into four chapters. The first chapter discusses the synthesis and characterization of biobased thermosets prepared by the free radical polymerization of conjugated linseed oil with commercially available monomers. The second chapter covers the synthesis and characterization of a chemically modified castor oil and its copolymerization with cyclooctene via ring opening metathesis polymerization (ROMP). The third chapter looks at the ROMP of a commercially available vegetable oil containing an unsaturated bicyclic moiety with dicyclopentadiene (DCPD) and characterization of the resulting materials. The fourth chapter discusses the reinforcement of a ROMP resin using short glass fibers to make composite materials