A fast algorithm for solving diagonally dominant symmetric pentadiagonal Toeplitz systems

Banded Toeplitz systems of linear equations arise in many application areas and have been well studied in the past. Recently, significant advancement has been made in algorithm development of fast parallel scalable methods to solve tridiagonal Toeplitz problems. In this paper we will derive a new algorithm for solving symmetric pentadiagonal Toeplitz systems of linear equations based upon a technique used in [J.M. McNally, L.E. Garey, R.E. Shaw, A split-correct parallel algorithm for solving tri-diagonal symmetric Toeplitz systems, Int. J. Comput. Math. 75 (2000) 303-313] for tridiagonal Toeplitz systems. A common example which arises in natural quintic spline problems will be used to demonstrate the algorithm’s effectiveness. Finally computational results and comparisons will be presented.     

Development of an optimized feeding technology for dairy cows

We have previously reported on MB-1, a designer protein with potential application in animal nutrition. Having a high content of selected essential amino acids, MB-1 should provide limiting nutrients for animals and promote growth and production. However, the protein was found to have marginal conformational and proteolytic stability, and, thus, strategies for stabilizing MB-1 were elaborated. We discuss the synthesis of MB-1-Cys dimer, a protein with an intermolecular disulfide bridge. This mutant was exposed to Pronase E protease preparation as well as to proteases extracted from ruminal microbes. It was found that in both cases, MB-1-Cys dimer had a better resistance to proteolytic degradation than MB-1. Denaturation and hydrophobic dye binding studies revealed that this enhanced stability was not owing to conformational stabilization, but rather to changes in surface exposure as a consequence of dimerization. In particular, it was found that binding of ANSA to MB-1-Cys dimer was comparable to that observed for native, compact, natural proteins. We discuss the implications of these results for the design of transgenic protein production systems.     

Conformational control of HCl co-transporter: imidazole functionalised isophthalamide vs. 2,6-dicarboxamidopyridine

Replacement of the central isophthalamide core in a synthetic HCl receptor, with a 2,6-dicarboxamidopyridine, leads to a more preorganised molecular structure that exhibits higher chloride affinity and membrane transport flux.     

Melt‐compounded nanocomposites of titanium dioxide atomic‐layer‐deposition‐coated polyamide and polystyrene powders

Polyamide and polystyrene particles were coated with titanium dioxide films by atomic layer deposition (ALD) and then melt‐compounded to form polymer nanocomposites. The rheological properties of the ALD‐created nanocomposite materials were characterized with a melt flow indexer, a melt flow spiral mould, and a rotational rheometer. The results suggest that the melt flow properties of polyamide nanocomposites were markedly better than those of pure polyamide and polystyrene nanocomposites. Such behavior was shown to originate in an uncontrollable decrease in the polyamide molecular weight, likely affected by a high thin‐film impurity content, as shown in gel permeation chromatography (GPC) and scanning electron microscope (SEM) equipped with an energy‐dispersive spectrometer. Transmission electron microscope image showed that a thin film grew on both studied polymer particles, and that subsequent melt‐compounding was successful, producing well dispersed ribbon‐like titanium dioxide with the titanium dioxide filler content ranging from 0.06 to 1.12 wt%. Even though we used nanofillers with a high aspect ratio, they had only a minor effect on the tensile and flexural properties of the polystyrene nanocomposites. The mechanical behavior of polyamide nanocomposites was more complex because of the molecular weight degradation. Our approach here to form polymeric nanocomposites is one way to tailor ceramic nanofillers and form homogenous polymer nanocomposites with minimal work‐related risks in handling powder form nanofillers. However, further research is needed to gauge the commercial potential of ALD‐created nanocomposite materials. Copyright © 2011 John Wiley & Sons, Ltd.     

Infrared matrix isolation study of the thermal and photochemical reactions of ozone with dimethylcadmium

The matrix isolation technique has been combined with infrared spectroscopy and theoretical calculations to explore the reaction of (CH(3))(2)Cd with O(3) over a range of time scales and upon irradiation. During twin jet deposition, multiple novel product species were observed along with several stable "late" products. Following annealing of these matrices to 35 K, absorptions due to two novel product species increased in intensity. In addition, new bands appeared, indicating the formation of an additional product. Subsequent UV irradiation destroyed several of the initial products and produced a new photoproduct. On the basis of (18)O and (16,18)O spectroscopic data and theoretical calculations, the novel intermediates H(3)COCdCH(3), H(3)CCdCH(2)OH, H(3)COCdOOCH(3), and H(3)CCdCHO were identified. Merged jet deposition led to a number of stable "late" products, including H(2)CO, CH(3)OH, and C(2)H(6), identifications that were confirmed by (18)O substitution. Mechanistic inferences for this reaction are discussed.     

A communication-less parallel algorithm for tridiagonal Toeplitz systems

Diagonally dominant tridiagonal Toeplitz systems of linear equations arise in many application areas and have been well studied in the past. Modern interest in numerical linear algebra is often focusing on solving classic problems in parallel. In McNally [Fast parallel algorithms for tri-diagonal symmetric Toeplitz systems, MCS Thesis, University of New Brunswick, Saint John, 1999], an m processor Split & Correct algorithm was presented for approximating the solution to a symmetric tridiagonal Toeplitz linear system of equations. Nemani [Perturbation methods for circulant-banded systems and their parallel implementation, Ph.D. Thesis, University of New Brunswick, Saint John, 2001] and McNally (2003) adapted the works of Rojo [A new method for solving symmetric circulant tri-diagonal system of linear equations, Comput. Math. Appl. 20 (1990) 61–67], Yan and Chung [A fast algorithm for solving special tri-diagonal systems, Computing 52 (1994) 203–211] and McNally et al. [A split-correct parallel algorithm for solving tri-diagonal symmetric Toeplitz systems, Internat. J. Comput. Math. 75 (2000) 303–313] to the non-symmetric case. In this paper we present relevant background from these methods and then introduce an m processor scalable communication-less approximation algorithm for solving a diagonally dominant tridiagonal Toeplitz system of linear equations.