Suitable Matrices Research Articles

Separation of DNA fragments in hydroxylated poly(dimethylacrylamide) copolymers

The novel polymer matrices reported here are low-viscosity sieving media for DNA capillary electrophoresis. This new family of matrices comprises copolymers of N,N-dimethylacrylamide with different monomers which increase polymer hydrophilicity. All these new copolymers self-coat on fused-silica capillaries. Resolution, peak spacing and peak width were the parameters taken into account to assess the influence of polymer structure on separation selectivity and efficiency. This work demonstrates that the performance of polydimethylacrylamide (PDMA) can be improved through copolymerization with hydrophilic monomers. The improvement is related to the efficiency parameter. The new copolymers, due to their low viscosity high sieving capacity and ability to suppress EOF, represent a better alternative to PDMA and are suitable replaceable matrices for capillary and microchip electrophoresis.

Prolonged storage of ‘Karuthacolomban’ mango by modified atmosphere packaging at low temperature

SummaryMature ‘Karuthacolomban’ mangoes were sealed in low-density polyethylene (LDPE) bags to create modified atmosphere (MA) conditions and stored at 13°C and 94% r.h. The effect of potassium permanganate impregnated bricks as ethylene scavengers and activated granular charcoal as carbon dioxide scavengers on extending the storage life of mango was examined. The in-package concentrations of oxygen, carbon dioxide and ethylene, and changes in physico-chemical properties during storage were determined. Storage was terminated at different intervals, and the fruits were allowed to ripen naturally under ambient conditions. The optimum storage period was determined based on the visual quality rating (VQR) and disease index (DI) of the ripened fruits. The physico-chemical and sensory properties of the ripened fruits subjected to MA storage were determined and compared with the fruits packaged in perforated LDPE bags. In-package oxygen, carbon dioxide and ethylene concentrations were 2.3%, 6.2% and 0.24 mg kg–1, respectively, in packages containing the scavengers on day 21 in storage. These corresponding concentrations in the packages were 7.5%, 11.7% and 0.8 mg kg–1, respectively, in the absence of scavengers on day 21 in storage. The fruits packaged with scavengers had lower percent weight loss and minimum changes in physico-chemical properties compared with the fruits packaged without scavengers. The modified atmosphere created in LDPE was effective in delaying ripening of ‘Karuthacolomban’ mangoes up to 16 d; ripening was further delayed up to 21 d in the presence of scavengers. Physico-chemical and sensory properties, VQR and DI of MA stored mango after ripening were similar to those packaged in perforated LDPE bags. Therefore, packaging of ‘Karuthacolomban’ mango in 0.05 mm LDPE bags of 1:1 surface area to weight ratio (cm2g–1) with 50 ml of saturated potassium permanganate absorbed onto suitable porous matrices and 2 g of activated granular charcoal could be recommended to increase storage life at 13°C.

EXACT NUMBER OF MOSAIC PATTERNS IN CELLULAR NEURAL NETWORKS

This work investigates mosaic patterns for the one-dimensional cellular neural networks with various boundary conditions. These patterns can be formed by combining the basic patterns. The parameter space is partitioned so that the existence of basic patterns can be determined for each parameter region. The mosaic patterns can then be completely characterized through formulating suitable transition matrices and boundary-pattern matrices. These matrices generate the patterns for the interior cells from the basic patterns and indicate the feasible patterns for the boundary cells. As an illustration, we elaborate on the cellular neural networks with a general 1 × 3 template. The exact number of mosaic patterns will be computed for the system with the Dirichlet, Neumann and periodic boundary conditions respectively. The idea in this study can be extended to other one-dimensional lattice systems with finite-range interaction.

Evaluation of nanostructured composite collagen--chitosan matrices for tissue engineering.

The development of suitable three-dimensional matrices for the maintenance of cellular viability and differentiation is critical for applications in tissue engineering and cell biology. The structure and composition of the extracellular matrix (ECM) has been shown to modulate cell behavior with respect to shape, movement, proliferation, and differentiation. Although collagen and chitosan have separately been proposed as in vitro ECM materials, the influence of chitosan--collagen composite matrices on cell morphology, differentiation, and function is not well studied. To this end, gel matrices of different proportions of collagen and chitosan were examined ultrastructurally and characterized for their ability to regulate cellular activity. A three-chamber system with circulating hydraulic fluids was used to evaluate the gel stability under fluid force. Results indicated that overall matrix integrity increased with the proportion of chitosan. Scanning electron microscopy indicated that the addition of chitosan greatly influences ultrastructure and changes collagen fiber cross-linking, reinforcing the structure and increasing pore size. K562 cells cultured in three-dimensional gels were examined for cell proliferation and differentiation. Although cell proliferation was inhibited with an increasing proportion of chitosan, cell function based on cytokine-release was greatly augmented. Results suggest that a hybrid chitosan--collagen matrix may have potential biological and mechanical benefits for use as a cellular scaffold.

PLI logic for multiple-valued functions

Properties of transformation matrices for multiple-valued-input binary-output PLI logic are discussed. It is shown that some of PLI logic transformations for Boolean functions are still applicable for multiple-valued-input binary functions with appropriate coding and new matrix functions. Fast algorithms of suitable PLI transformation matrices are shown and their complexity analysis is discussed.

Photogeneration of Silver Particles in PVA Fibers and Films

Fibers and films prepared from blends of poly(vinyl alcohol) and poly(acrylic acid) were found to be suitable matrices for the solid-state photoreduction of silver ions in the presence of air. Fast generation of nanometer-sized silver crystallites was observed when fibers of polymer blends crosslinked with dimethyl sulfoxide were irradiated with 350 nm light. Optical determinations of the formation kinetics were carried out using thin films of noncrosslinked as well as lightly and heavily crosslinked polymer blends. Small Ag clusters were detected initially, which were stable in the dark but transformed into larger metal particles upon further illumination. Both formation processes occurred only under high light intensity illumination and the kinetic data were inconsistent with monophotonic mechanisms.

Balanced systems of primitive idempotents in matrix algebras

The article develops the concept of balanced -systems of idempotents in associative semisimple finite-dimensional algebras over the field of complex numbers this was introduced by the author as a generalization of the concept of combinatorial -schemes, which in this context corresponds to the case of commutative algebras. Balanced 2-systems are considered consisting of primitive idempotents in the matrix algebra , known as -systems. It is proved that -systems are unique and it is shown that there are no -systems with or . The -systems having 2-transitive automorphism subgroup , odd, are classified. The (4,2)- and (6,3)-systems are classified. A balanced basis is constructed in the algebras , . Connections are established between conference matrices and -systems, and between suitable matrices and -systems.

Functionalized silk-based biomaterials for bone formation.

Silks are being reassessed as biomaterial scaffolds due to their unique mechanical properties, opportunities for genetic tailoring of structure and thus function, and recent studies clarifying biocompatibility. We report on the covalent decoration of silk films with integrin recognition sequences (RGD) as well as parathyroid hormone (PTH, 1-34 amino acids) and a modified PTH 1-34 (mPTH) involved in the induction of bone formation. Osteoblast-like cell (Saos-2) responses to the decorated silk films indicate that the proteins serve as suitable bone-inducing matrices. Osteoblast-like cell adhesion was significantly increased on RGD and PTH compared to plastic, mPTH, and the control peptide RAD. At 2 weeks of culture, message levels of alkaline phosphatase were similar on all substrates, but by 4 weeks, alkaline phosphatase mRNA was greatest on RGD. At 2 weeks of culture, alpha 1(I) procollagen mRNA was elevated on silk, RGD, RAD, and PTH, and hardly detectable on mPTH and plastic. However, by 4 weeks RGD demonstrated the highest level compared to the other substrates. Osteocalcin message levels detected by RT-PCR were greatest on RGD at both time points. Calcification was also significantly elevated on RGD compared to the other substrates with an increase in number and size of the mineralized nodules in culture. Thus, RGD covalently decorated silk appears to stimulate osteoblast-based mineralization in vitro.

Modified atmosphere packaging of ‘Kolikuttu’ bananas at low temperature

SummaryMature `Kolikuttu' bananas were packed under modified atmosphere (M.A.) conditions using low density polyethylene (LDPE) bags and stored at 14°C and 94% r.h. The effect of ethylene scavengers on storage life of banana was examined. The in-package concentrations of oxygen, carbon dioxide and ethylene were measured during storage. Percentage weight loss, changes in firmness, total soluble solids (TSS), pH and sugar: acid during storage were also determined. Based on the in-package gaseous composition, the optimum storage period was defined. After termination of storage, bananas were allowed to ripen naturally, and the physico-chemical properties of ripened banana were analysed. `Kolikuttu' bananas could be packed in LDPE (0.075 mm) and stored at 14°C and 94% r.h. for 24.d. Storage life could be further extended up to 30.d by using ethylene scavengers. Physico-chemical properties of M.A. stored banana after ripening were similar to those held under ambient conditions. Therefore, packaging of `Kolikuttu' banana as individual hands in LDPE (0.075.mm) bags of 1:1 surface to weight ratio (cm2 g-1) with 50 ml of saturated potassium permanganate absorbed onto suitable porous matrices could be recommended to increase storage lifeat 14°C.

Non-symmetrical factorial discriminant analysis for symbolic objects

In this paper we propose a generalization of the factorial discriminant analysis (FDA) to complex data structures named Symbolic Objects. We assume that the a priori classes are defined by an equal number of intention symbolic objects. The paper proposes a three-step discrimination procedure. Symbolic data are coded in suitable numerical matrices, coded variables are transformed into canonical variables, symbolic objects are visualized building maximum covering area rectangles, with respect to the canonical variables. Referring to the graphical representation, geometrical rules are proposed in order to assign new objects to a a priori class on the basis of proximity measures. Copyright © 1999 John Wiley & Sons, Ltd.

From the Bethe Ansatz to the Gessel-Viennot theorem

We state and prove several theorems that demonstrate how the coordinate Bethe Ansatz for the eigenvectors of suitable transfer matrices of a generalized inhomogeneous, five-vertex model on the square lattice, given certain conditions hold, is equivalent to the Gessel-Viennot determinant for the number of configurations ofN non-intersecting directed lattice paths, or vicious walkers, with various boundary conditions. Our theorems are sufficiently general to allow generalisation to any regular planar lattice.

Minimization properties and short recurrences

Two algorithms characterized by a short recurrence as well as a minimization property in the energy norm are derived by choosing suitable preconditioning matrices for certain step-dependent preconditioned conjugate Krylov subspace (CKS) algorithms. It is shown that the two methods are also equivalent to two special truncated generalized CG algorithms. Therefore, it is possible to state a minimization property for truncated generalized CG algorithms in a k-dimensional space. Numerical comparison with other generalized CG algorithms requiring the same amount of storage shows that the derived methods are competitive and for certain problems faster.

In vitro evaluation of biodegradable ε-caprolactone-co- d, l-lactide/silica xerogel composites containing toremifene citrate

Poly(ε-caprolactone-co- d,l-lactide) polymers were blended with toremifene citrate or with toremifene citrate impregnated silica xerogel in order to develop a controlled release formulation. The copolymers were synthesized by bulk polymerization and characterized by nuclear magnetic resonance, size exclusion chromatography and differential scanning calorimetry analyses. The in vitro release of toremifene citrate, an antiestrogenic compound, and silica was carried out in simulated body fluid (pH 7.4) containing 0.5 wt% sodium dodecylsulphate at 34°C. The in vitro release studies indicate that the release flux of toremifene citrate increases with increasing weight fraction of caprolactone in the copolymer. Silica xerogel had a minor enhancing effect on the release rate of toremifene citrate. Copolymers containing larger amounts of d,l-lactide (PLA–CL20 and PLA–CL40 copolymers) were not suitable matrices for the delivery of toremifene citrate in a controlled manner because of the burst effect. The fraction of toremifene citrate released from PLA–CL80 matrix increased with the increasing loading of toremifene citrate. The results of the study indicate that the in vitro release of toremifene citrate can be adjusted by varying the polymer composition and also the initial drug loading.

An alternative system of structural invariants of quadruples of matrices

The equivalence relation between time-invariant linear dynamical systems deduced from the action of the group consisting of all basis changes, state feedback and output injection transformations is considered. An alternative complete system of structural invariants is presented. Discrete invariants in this system are the ranks of suitable matrices, generalizing the numerical invariants obtained for pairs of matrices under block-similarity. The continuous invariants are characterized in terms of the rank of a matrix.

Matrix optimization for matrix-assisted laser desorption/ionization mass spectrometry of oligosaccharides from human milk.

Neutral and acidic oligosaccharides from human milk were analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI/MS). These experiments require suitable matrices; their selection and particularly their preparation protocols must be optimized. Important criteria are sensitivity, reproducibility, tolerance against impurities and resolution over a wide mass range. For analytical investigations of these oligosaccharides, containing labile fucosylated and sialylated components, another property of a matrix becomes a significant factor, namely the influence on ion stability and the extent of (metastable) fragmentation. The experience gained with the MALDI/MS of neutral and acidic oligosaccharides is summarized taking into account different intentions of measurement and typical problems, such as impurities after enzymatic treatment. For a rapid screening of an oligosaccharide sample, superior results were obtained with a new preparation technique using 5-chloro-2-mercaptobenzothiazole (CMBT) as the first layer for 2,5-dihydroxybenzoic acid. For structural analysis by post-source decay, CMBT as the first layer for 3-aminoquinoline is a favoured preparation protocol, because extensive fragmentation is achieved. For acidic oligosaccharides, a special preparation protocol makes it possible to determine the number of sialic acids by inducing highly effective cationization. Matrix-assisted laser desorption/ionization mass spectrometry; matrices; oligosaccharides; post-source decay.

High Performance, Light weight Thermoplastic/Rare Earth Alloy Magnets

ABSTRACTWe report progress on our exploratory research on surface modification of magnetic NdFeB fillers, characterization of suitable magnetic rare earth alloy powders and high-performance polymer matrices, processability, and properties of novel thermoplastic/NdFeB magnets. The results suggest that blending liquid crystal polymer (LCP) with a high-thermoplastic polymer such as polyphenylene sulfide (PPS) provides the required balance of properties. These properties include superior magneto-mechanical performance, minimal melt viscosity at optimal NdFeB volume loading, enhanced thermal stability, high stiffness, high strength, improved dimensional stability, and excellent chemical resistance; making the thermoplastics magnets suitable for use in high temperature and aggressive environments where commercial polymer-bonded magnets are not useable.

Electrosynthetic immobilisation of proteins for bioanalysis

Use of electrosynthetic methodology allows the production of hen egg-white lysozyme (HEWL) either mononitrated at tyrosine 23 or bisnitrated at tyrosines 20 and 23, but never nitrated at tyrosine 53. This is a different sequence from that obtained by the chemical nitrating agent tetranitromethane, and when reduced by dithionite, the selectively modified enzyme can be anchored at pH 5 via the unique aromatic amino group to magnetic beads or other suitable matrices. HEWL so immobilised loses less than 10% of cell-wall lytic activity compared with the approximately 50% loss of activity when immobilised by conventional methodology at pH 9 via essentially random reaction at lysine residues and other functionalities which are nucleophilic at this pH. This result offers promise as a general method for selective protein immobilisation in biosensors and similar applications. © 1998 John Wiley & Sons, Ltd.

Primitivity of Positive Matrix Pairs: Algebraic Characterization, Graph Theoretic Description, and 2D Systems Interpretation

In this paper the primitivity of a positive matrix pair (A,B) is introduced as a strict positivity constraint on the asymptotic behavior of the associated two-dimensional (2D) state model. The state evolution is first considered under the assumption of periodic initial conditions. In this case the system evolves according to a one-dimensional (1D) state updating equation, described by a block circulant matrix. Strict positivity of the asymptotic dynamics is equivalent to the primitivity of the circulant matrix, a property that can be restated as a set of conditions on the spectra of $A + e^{i \omega} B$, for suitable real values of $\omega$. The theory developed in this context provides a foundation whose analytical ideas may be generalized to nonperiodic initial conditions. To this purpose the spectral radius and the maximal modulus eigenvalues of the matrices $e^{i \theta} A + e^{i \omega} B$, $\theta$ and $\omega \in \hbox{{\bbb R}},$ are related to the characteristic polynomial of the pair (A,B) as well as to the structure of the graphs associated with A and B and to the factorization properties of suitable integer matrices. A general description of primitive positive matrix pairs is finally derived, including both spectral and combinatorial conditions on the pair.

Wall transient heat flow using time-domain analysis

If values of ambient temperature and room temperature are known at hourly intervals, the heat flow to or from the room at some specified time can be computed in terms of the values of recent temperatures and heat flows, weighted by values of a series of N wall transfer coefficients, b k, or c k, and d k, ( k = 0 to N). These coefficients have hitherto been found by frequency domain methods. It is shown here that they can be evaluated using elementary time domain solutions for wall heat flow. A multi-layer wall with surface films representing radiant and convective exchange is discussed. Using suitable transmission matrices, solutions for the steady-progressive and transient temperature profiles through the wall are derived. The value of N and the wall d k values follow immediately from the wall decay times of the transient solution, together with the choice of 1 hour as time interval. Using a development of Fourier analysis, the steady-progressive and transient solutions are combined so as to provide the time-domain solution for the response to an imposed ramp in ambient or room temperature. Combination of three such ramps forms a triangular temperature pulse of excitation and the infinite series of wall response factors—hourly values of heat flow at and after the temperature peak—serve to describe the response of the wall when excited by such a pulse. The values of b k and c k follow from the response factors. The procedure is illustrated numerically.

Optical systems expressed in terms of fractional Fourier transforms

In this study, by means of the matrix method it has been shown that any optical system parameterized by a transfer matrix A B C D can be represented in the form of fractional Fourier transforms (FRFTs), if suitable additional matrices are introduced into the system. Both nondegenerate and degenerate cases have been considered and some examples have been given to illustrate the results.