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Nature organizes cellulose, a linear polysaccharide of D-glucose and an important component of plants and trees, into intricate structures with twists in the trunks of trees, microfibrils within cell walls, and at the nanoscale. Manipulating the hierarchical organization of materials requires control down to the molecular level. In computational models cellulose nanocrystals twist, and Quantum Mechanical...
Molecular Mechanics, Hartree–Fock, and semi-empirical geometry optimizations were carried out on cellulose oligomers and crystallites with and without water solvation. The intramolecular bonding is visualized with the Delocalized Molecular Orbitals (DLMOs). Internal coordinates were relaxed and the structures were gradient optimized for cellulose oligomers composed of 4, 10, 12, 14, 19, and 65 glucose...
Structural changes in cellulose fibers were elucidated for carboxymethylated fibers and fibers that are oxidized by periodate and chlorite. Non-fibrillated and partially fibrillated softwood, kraft fibers (SKF, m-SKF) were carboxymethylated to investigate the contribution of the S1 layer to the swollen fiber structures. Carboxymethylated non-fibrillated fibers (CMF) form balloon-like structures as...
Atomic force microscopy (AFM), tapping mode atomic force microscopy (TM-AFM) and transmission electron microscopy (TEM) have been used to image the cell wall, ultrathin sections of whole cells and cellulose microfibrils prepared from the green alga Micrasterias denticulata. Measurements of the microfibril dimensions are in agreement with earlier observations carried out by electron microscopy. Images...
Recent studies in pole placement have investigated the degree of flexibility available when feedback is constrained to constant gains on the output variables of a linear system. This paper uses pencil theory to provide a structural basis for determining the available degree of flexibility in choosing coefficients of the closed-loop characteristic equation of an output feedback system. Previous results...
An algorithm for computing the canonical form of a singular pencil is presented. This algorithm, which is based on well known linear algebra techniques, offers efficiency and error analysis advantages over previous algorithms presented by Thorp and Gantmacher. These results are useful in exposing the structure of linear multivariable systems.
A completely general algebraic method for converting a set of linear differential equations that describe a multivariable system to the standard state equation model is considered. The entire procedure is developed in a straight forward manner so that each aspect of the algorithm is simplistic in nature as well as efficient when implemented on a digital computer. An example is presented to illustrate...
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