Search results for "Matrix"
showing 10 items of 3205 documents
The Hermitian part of a Rickart involution ring, I
2014
Rickart *-rings may be considered as a certain abstraction of the rings B(H) of bounded linear operators of a Hilbert space H. In 2006, S. Gudder introduced and studied a certain ordering (called the logical order) of self-adjoint Hilbert space operators; the set S(H) of these operators, which is a partial ring, may be called the Hermitian part of B(H). The new order has been further investigated also by other authors. In this first part of the paper, an abstract analogue of the logical order is studied on certain partial rings that approximate the Hermitian part of general *-rings; the special case of Rickart *-rings is postponed to the next part.
Physico-chemical state influences in vitro release profile of curcumin from pectin beads
2014
International audience; Curcumin is a polyphenolic compound with diverse effects interesting to develop health benefit products but its formulation in functional foods or in food supplement is hampered by its poor water solubility and susceptibility to alkaline conditions, light, oxidation and heat. Encapsulation of curcumin could be a mean to overcome these difficulties. In this paper, curcumin was encapsulated by ionotropic gelation method in low methoxyl pectin beads associated with different surfactants: Solutol®, Transcutol® and sodium caseinate. After encapsulation, physico-chemical properties of encapsulated curcumin such as its solubility, physical state, tautomeric forms and encaps…
Cultivation of primmorphs from the marine sponge Suberites domuncula: morphogenetic potential of silicon and iron.
2002
Abstract Marine demosponges (phylum Porifera) are rich sources for potent bioactive compounds. With the establishment of the primmorph system from sponges, especially from Suberites domuncula , the technology to cultivate sponge cells in vitro improved considerably. This progress was possible after the elucidation that sponges are provided with characteristic metazoan cell adhesion receptors and extracellular matrix molecules which allow their cells a positioning in a complex organization pattern. This review summarizes recent data on the cultivation of sponges in aquaria and—with main emphasis—of primmorphs in vitro. It is outlined that silicon and Fe(+++) contribute substantially to the f…
Response of the oxygen sensor NreB to air in vivo: Fe-S-containing NreB and apo-NreB in aerobically and anaerobically growing Staphylococcus carnosus.
2009
ABSTRACT The sensor kinase NreB from Staphylococcus carnosus contains an O 2 -sensitive [4Fe-4S] 2+ cluster which is converted by O 2 to a [2Fe-2S] 2+ cluster, followed by complete degradation and formation of Fe-S-less apo-NreB. NreB·[2Fe-2S] 2+ and apoNreB are devoid of kinase activity. NreB contains four Cys residues which ligate the Fe-S clusters. The accessibility of the Cys residues to alkylating agents was tested and used to differentiate Fe-S-containing and Fe-S-less NreB. In a two-step labeling procedure, accessible Cys residues in the native protein were first labeled by iodoacetate. In the second step, Cys residues not labeled in the first step were alkylated with the fluorescent…
Bioadhesive Matrix Tablets Loaded with Lipophilic Nanoparticles as Vehicles for Drugs for Periodontitis Treatment: Development and Characterization
2019
Periodontitis treatment is usually focused on the reduction or eradication of periodontal pathogens using antibiotics against anaerobic bacteria, such as metronidazole (MTR). Moreover, recently the correlation between periodontal diseases and overexpression of reactive oxygen species (ROS) led to the introduction of antioxidant biomolecules in therapy. In this work, bioadhesive buccal tablets, consisting of a hydrophilic matrix loaded with metronidazole and lipophilic nanoparticles as a vehicle of curcumin, were developed. Curcumin (CUR)-loaded nanostructured lipid carriers (NLC) were prepared using glycyrrhetic acid, hexadecanol, isopropyl palmitate and Tween®
An Iterative Approach to Dynamic Elastic-Plastic Analysis
1998
The step-by-step analysis of structures constituted by elastic-plastic finite elements, subjected to an assigned loading history, is here considered. The structure may possess dynamic and/or not dynamic degrees-of-freedom. As it is well-known, at each step of analysis the solution of a linear complementarity problem is required. An iterative method devoted to solving the relevant linear complementarity problem is presented. It is based on the recursive solution of a linear complementarity, problem in which the constraint matrix is block-diagonal and deduced from the matrix of the original linear complementarity problem. The convergence of the procedure is also proved. Some particular cases …
Wavelet-like bases for thin-wire integral equations in electromagnetics
2005
AbstractIn this paper, wavelets are used in solving, by the method of moments, a modified version of the thin-wire electric field integral equation, in frequency domain. The time domain electromagnetic quantities, are obtained by using the inverse discrete fast Fourier transform. The retarded scalar electric and vector magnetic potentials are employed in order to obtain the integral formulation. The discretized model generated by applying the direct method of moments via point-matching procedure, results in a linear system with a dense matrix which have to be solved for each frequency of the Fourier spectrum of the time domain impressed source. Therefore, orthogonal wavelet-like basis trans…
Normalizing biproportional methods
2002
International audience; Biproportional methods are used to update matrices: the projection of a matrix Z to give it the column and row sums of another matrix is R Z S, where R and S are diagonal and secure the constraints of the problem (R and S have no signification at all because they are not identified). However, normalizing R or S generates important mathematical difficulties: it amounts to put constraints on Lagrange multipliers, non negativity (and so the existence of the solution) is not guaranteed at equilibrium or along the path to equilibrium.
New methods for analysing colour texture based on the Karhunen–Loeve transform and quantification
2004
In this article, we offer an original study on the analysis of the texture of colour images based on Local Linear Transforms (LLT). Our colour approach is based on the separability of the data which reduces the number of texture parameters. We also propose the extension of Run Lengths (RL) and Co-occurrence Matrixes (CM) to colour images. In this respect, two different ways were explored (data merging and quantification). We finally present a comparative study showing the efficiency of the first method (LLT) as well as the complementary nature of the other methods (RL, CM).
Proteoglycan occurrence in gastrolith of the crayfish Cherax quadricarinatus (Malacostraca: Decapoda).
2012
14 pages; International audience; Biomineralized structures are hybrid composites formed and stabilized by the close interaction of the organic and the inorganic phases. Crayfish are good models for studying biomineralization because they develop, in a molting-mineralization cycle, semi-spherical mineralized structures referred to as gastroliths. The organic matrix of these structures consists of proteins, polysaccharides, and lipids. Chitin is the main polysaccharide and is concentrically arranged as fibrous chitin-protein lamellar structures. Although several proteins and low-molecular weight phosphorylated components have been reported to be involved in gastrolith mineralization, the occ…