Matrix Condensation Research Articles

Analysis of shear wall with openings using super elements

The box system that consists of reinforced concrete walls and slabs is adopted for many high-rise apartment buildings recently constructed. In an apartment building, shear walls may have one or more openings for functional reasons. Some researches on the analysis of shear wall with openings were performed, but some restrictions prevent those research results from being applied to the practical analysis and design procedure. It is necessary to use fine mesh finite element models for an accurate analysis of a box system structure with openings. But it would take a significant amount of computational time and memory if the entire building structure were subdivided into a finer mesh. An efficient analysis method that can be used regardless of the number, size and location of openings is proposed in this study. The analysis method uses super elements developed using the matrix condensation technique. Static and dynamic analyses of example structures having various types of openings were performed to verify the efficiency and accuracy of the proposed method. The analyses of example structures demonstrated that the proposed method can be used for the analysis of a shear wall structure with openings. Outstanding accuracy in analysis could be achieved with drastically reduced computational time and memory.

Mitochondrial respiratory control is lost during growth factor deprivation.

The ability of cells to maintain a bioenergetically favorable ATP/ADP ratio confers a tight balance between cellular events that consume ATP and the rate of ATP production. However, after growth factor withdrawal, the cellular ATP/ADP ratio declines. To investigate these changes, mitochondria from growth factor-deprived cells isolated before the onset of apoptosis were characterized in vitro. Mitochondria from growth factor-deprived cells have lost their ability to undergo matrix condensation in response to ADP, which is accompanied by a failure to perform ADP-coupled respiration. At the time of analysis, mitochondria from growth factor-deprived cells were not depleted of cytochrome c and cytochrome c-dependent respiration was unaffected, demonstrating that the inhibition of the respiratory rate is not due to loss of cytochrome c. Agents that disrupt the mitochondrial outer membrane, such as digitonin, or maintain outer membrane exchange of adenine nucleotide, such as Bcl-x(L), restored ADP-dependent control of mitochondrial respiration. Together, these data suggest that the regulation of mitochondrial outer membrane permeability contributes to respiratory control.

Efficient siesmic analysis of building structures with added viscoelastic dampers

Conventional analysis methods for building structures with added viscoelastic dampers, such as direct integration, complex mode superposition, and modal strain energy method, were compared, and a procedure based on rigid diaphragm assumption and matrix condensation technique was proposed for application in the preliminary analysis and design stages. The results from the various analysis methods with and without the matrix condensation were compared, in view of both accuracy and efficiency. According to the eigenvalue analysis the major vibration modes were mostly preserved after the matrix condensation. It was also found that the matrix condensation technique applied to dynamic analysis of a structure with added viscoelastic dampers provided quite accurate results in significantly reduced time, regardless of the plan shape and the location of the viscoelastic dampers.

Efficient seismic analysis of high-rise building structures with the effects of floor slabs

Box system structures, composed of only reinforced concrete walls and slabs, have been recently adopted for many high-rise apartment buildings. Commercial software such as ETABS, commonly used for the analysis of high-rise apartment buildings, assumes a rigid diaphragm for floor slabs. The flexural stiffness of slabs is generally ignored in the analysis. This assumption may be reasonable for the analysis of framed structures. In box system structures like apartment buildings, however, the floor slabs may have a significant influence on the lateral response of the structures. If the flexural stiffness of slabs in a box system structure is totally ignored, the lateral stiffness may be significantly underestimated. In reality, the cracked section property of a slab will determine the amount of its flexural stiffness that will be included in the analysis. In order to include the flexural stiffness of slabs, the slab needs to be modeled with plate elements. If the slab is subdivided into many plate elements while keeping each shear wall with a large element (as generally modeled with commercial software), the compatibility condition will not be satisfied at the interface of the slab and the shear wall. To enforce the compatibility condition at the interface, a fictitious beam is introduced. It would cost a significant amount of analysis time and computer memory to model the floor slab with many subdivided plate elements in every floor of a high-rise building. In this study, an efficient method is proposed to analyze high-rise box system structures considering the effects of floor slabs. The proposed method will reduce computational time and memory in the analysis by using the substructuring technique and matrix condensation.

Role of Mitochondria and Caspases in Vitamin D-mediated Apoptosis of MCF-7 Breast Cancer Cells

Vitamin D(3) compounds are currently in clinical trials for human breast cancer and offer an alternative approach to anti-hormonal therapies for this disease. 1alpha,25-Dihydroxyvitamin D(3) (1alpha,25(OH)(2)D(3)), the active form of vitamin D(3), induces apoptosis in breast cancer cells and tumors, but the underlying mechanisms are poorly characterized. In these studies, we focused on the role of caspase activation and mitochondrial disruption in 1alpha,25(OH)(2)D(3)-mediated apoptosis in breast cancer cells (MCF-7) in vitro. The effect of 1alpha,25(OH)(2)D(3) on MCF-7 cells was compared with that of tumor necrosis factor alpha, which induces apoptosis via a caspase-dependent pathway. Our major findings are that 1alpha,25(OH)(2)D(3) induces apoptosis in MCF-7 cells by disruption of mitochondrial function, which is associated with Bax translocation to mitochondria, cytochrome c release, and production of reactive oxygen species. Moreover, we show that Bax translocation and mitochondrial disruption do not occur after 1alpha,25(OH)(2)D(3) treatment of a MCF-7 cell clone selected for resistance to 1alpha,25(OH)(2)D(3)-mediated apoptosis. These mitochondrial effects of 1alpha,25(OH)(2)D(3) do not require caspase activation, since they are not blocked by the cell-permeable caspase inhibitor z-Val-Ala-Asp-fluoromethylketone. Although caspase inhibition blocks 1alpha,25(OH)(2)D(3)-mediated events downstream of mitochondria such as poly(ADP-ribose) polymerase cleavage, external display of phosphatidylserine, and DNA fragmentation, MCF-7 cells still execute apoptosis in the presence of z-Val-Ala-Asp-fluoromethylketone, indicating that the commitment to 1alpha,25(OH)(2)D(3)-mediated cell death is caspase-independent.

Infrared matrix isolation study of the reaction of CrCl2O2 with (CH3)2O and (CH3)2CO

Matrix isolation has been combined with infrared spectroscopy to study the reaction chemistry of CrCl2O2 with (CH3)2O and (CH3)2CO. Very similar results were obtained with twin jet and room temperature merged jet deposition, indicating that the initial product forms on the surface of the matrix during deposition, not in the deposition lines prior to matrix condensation. The initial product in both systems was identified as the 1:1 complex between the two reagents, with a structure in which the oxygen atom of the base donates electron density to the Cr center. A number of perturbed vibrational modes of both subunits were observed; for the bases, these modes were vibrations involving the oxygen atom. Hg arc irradiation of the CrCl2O2·O(CH3)2 complex led to growth of a secondary product that is tentatively identified as Cl2CrO(OCH3)2. The CrCl2O2·OC(CH3)2 complex was not photosensitive, and no rearrangements were observed.

High-frequency transfer function model of the vocal tract sections using FEM matrix condensation and transfer matrix techniques

Using numerical tools such as the Finite Element Method (FEM) for acoustical modeling of the vocal tract would require a huge number of nodes and elements. In this paper, the matrix condensation and transfer matrix techniques [A. Craggs, J. Sound Vib. 132, 393–402 (1989)] adapted to a three-dimensional model of the vocal tract section analysis will be introduced and discussed. Using these new FEM techniques, which use only the nodes at the input and output of the structure, the transfer function can be computed with a very small matrix comparing to standard FEM. The second goal of this research is to attempt to discover some geometrical parameters which could influence the transfer function. This investigation could be useful to make a new electrical vocal tract model which would consist of cascade transfer functions controlled by parameters. The study of the transfer functions will be carried out in low and high frequencies. [Work partly supported by Japanese CREST project.]

Formulation of a super-element for the dynamic problem of a cracked plate

On the formulation of a super-element for the dynamic problem of a cracked plate, a geometric series of similar elements is designed. This group of elements is generated layer by layer, approaching infinitely small size around the point of singularity. The relations between similar elements for the stiffness matrix and the mass matrix are established. The concept of matrix condensation is applied to formulate the super-element by using these relationships. This method presents a feasible approach to the solution of the cracked problem with an arbitrary order of stress singularity. The method is computationally economical. Copyright © 1998 John Wiley & Sons, Ltd.

A fully automatic 3-D analysis tool for expansion chamber mufflers

The matrix condensation technique in conjunction with the substructuring principle has been previously used to model complex commercial automotive mufflers. Though complete 3-D finite element modelling is partially eliminated, it still requires the nodal-coordinate data and connectivity data of the elements forming the segment of each substructure. It also demands the connectivity of the degrees of freedom left after matrix condensation. Thus, the data preparation phase is tedious and cannot be claimed to be simple. Moreover, the existing FEM code requires the user to have a knowledge of acoustic theory and finite element modelling. This paper describes a way to completely eliminate the data preparation phase. Given the geometric dimensions of the muffler as input, the muffler performance is obtained as the output. The results obtained are compared with analytical and experimental results for simple as well as extended-tube expansion chambers, with or without an offset.

Binding of injected laminin to developing kidney glomerular mesangial matrices and basement membranes in vivo.

During glomerular development, subendothelial and -epithelial basement membrane layers fuse to produce the glomerular basement membrane (GBM) shared by endothelial cells and epithelial podocytes. As glomeruli mature, additional basement membrane derived from podocytes is spliced into the fused GBM and loose mesangial matrices condense. The mechanisms for GBM fusion, splicing, and mesangial matrix condensation are not known but might involve intermolecular bond formation between matrix molecules. To test for laminin binding sites, we intravenously injected mouse laminin containing alpha1-, beta1-, and gamma1-chains into 2-day-old rats. Kidneys were immunolabeled for fluorescence and electron microscopy with domain-specific rat anti-mouse laminin monoclonal antibodies (MAbs), which recognized only mouse and not endogenous rat laminin. Intense labeling for injected laminin was found in mesangial matrices and weaker labeling was seen in GBMs of maturing glomeruli. These patterns persisted for at least 2 weeks after injection. In control newborns receiving sheep IgG, no binding of injected protein was observed and laminin did not bind adult rat glomeruli. To assess which molecular domains might mediate binding to immature glomeruli, three proteolytic laminin fragments were affinity-isolated by MAbs and injected into newborns. These failed to bind glomeruli, presumably owing to enzymatic digestion of binding domains. Alternatively, stable incorporation may require multivalent laminin binding. We conclude that laminin binding sites are transiently present in developing glomeruli and may be functionally important for GBM assembly and mesangial matrix condensation.

MODELLING OF MULTI-BEARING ROTOR SYSTEMS INCORPORATING AN ACTIVE JOURNAL BEARING

A complete mathematical model for a multi-bearing rotor system incorporating a newly developed active journal bearing has been presented. Both a non-linear model and a general linearization method have been developed. The system configuration parameters (the relative positions of the bearings) were expressed explicitly in the equations of motion. Therefore it is convenient to carry out dynamic analysis of the rotor system in either the rotating speed domain or the system configuration parameter domain. The Guyan matrix condensation technique has been adopted to reduce the number of equations in the equations of motion. The mathematical model developed has been used in predicting the critical speeds, thresholds of instability and unbalance response of a multi-bearing rotor system.

SUBSTRUCTURAL IDENTIFICATION OF BRIDGE

The purpose of this paper is to use the seismic response data of one 5-span continuous box-girder bridge to identify the dynamic characteristics of the system from different earthquake loading. The spectral finite element method was used by considering the flexural wave in beam to form the dynamic stiffness matrix of the substructure. Through matrix condensation the interior nodal displacement can be expressed in terms of the boundary nodal displacements. The identification was performed by using the recorded nodal displacement of the bridge to identify the EI-value and damping factor η of the substructure. Three seismic event data sets were used from the bridge strong motion instrumentation array. It is found that the identified EI-values are very stable even for different intensity of earthquake loading while the damping value may change from seismic event to event.

Differential Effects of 1,25-Dihydroxyvitamin D3 and Tetradecanoylphorbol Acetate on Cell Cycle and Apoptosis of MCF-7 Cells and a Vitamin D3-Resistant Variant

1,25-Dihydroxyvitamin D3 (1,25-(OH)2D3), the active form of vitamin D3, and tetradecanoylphorbol acetate (TPA) are potent negative growth regulators of breast cancer cells. In this study, we compared the mechanism of action of these two compounds in MCF-7 cells and a vitamin D3-resistant variant (MCF-7D3Res). In parental MCF-7 cells, 1,25-(OH)2D3 induced morphological and biochemical markers of apoptosis (chromatin and nuclear matrix condensation and DNA fragmentation), whereas TPA induced growth arrest without apoptosis. Both 1,25-(OH)2D3 and TPA independently up-regulated the vitamin D receptor, p21, and the hypophosphorylated form of retinoblastoma (Rb) protein. The growth regulatory effects of 1,25-(OH)2D3 and TPA did not correlate with induction of p53 protein expression. When both compounds were added simultaneously, synergistic effects on MCF-7 cell number were observed, and cell cycle regulatory proteins were down-regulated. The MCF-7D3Res cells, which are not sensitive to 1,25-(OH)2D3, were growth inhibited by TPA, and TPA partially sensitized MCF-7D3Res cells to the growth inhibitory effects of 1,25-(OH)2D3. In MCF-7D3Res cells, 1,25-(OH)2D3 treatment had minimal effects on p21 or Rb protein expression, whereas TPA down-regulated Rb protein and transiently up-regulated p21. These studies indicate dissociation between the pathways triggered by 1,25-(OH)2D3 and TPA, which mediate growth regulation in MCF-7 cells. Because both compounds induce growth arrest, but only 1,25-(OH)2D3 mediates apoptosis, we conclude that cell cycle arrest is not sufficient to trigger cell death of MCF-7 cells, and that 1,25-(OH)2D3 generates distinct signals which lead to induction of apoptosis in breast cancer cells.

Differential effects of 1,25-dihydroxyvitamin D3 and tetradecanoylphorbol acetate on cell cycle and apoptosis of MCF-7 cells and a vitamin D3-resistant variant.

1,25-Dihydroxyvitamin D3 (1,25-(OH)2D3), the active form of vitamin D3, and tetradecanoylphorbol acetate (TPA) are potent negative growth regulators of breast cancer cells. In this study, we compared the mechanism of action of these two compounds in MCF-7 cells and a vitamin D3-resistant variant (MCF-7D3Res). In parental MCF-7 cells, 1,25-(OH)2D3 induced morphological and biochemical markers of apoptosis (chromatin and nuclear matrix condensation and DNA fragmentation), whereas TPA induced growth arrest without apoptosis. Both 1,25-(OH)2D3 and TPA independently up-regulated the vitamin D receptor, p21, and the hypophosphorylated form of retinoblastoma (Rb) protein. The growth regulatory effects of 1,25-(OH)2D3 and TPA did not correlate with induction of p53 protein expression. When both compounds were added simultaneously, synergistic effects on MCF-7 cell number were observed, and cell cycle regulatory proteins were down-regulated. The MCF-7D3Res cells, which are not sensitive to 1,25-(OH)2D3, were growth inhibited by TPA, and TPA partially sensitized MCF-7D3Res cells to the growth inhibitory effects of 1,25-(OH)2D3. In MCF-7D3Res cells, 1,25-(OH)2D3 treatment had minimal effects on p21 or Rb protein expression, whereas TPA down-regulated Rb protein and transiently up-regulated p21. These studies indicate dissociation between the pathways triggered by 1,25-(OH)2D3 and TPA, which mediate growth regulation in MCF-7 cells. Because both compounds induce growth arrest, but only 1,25-(OH)2D3 mediates apoptosis, we conclude that cell cycle arrest is not sufficient to trigger cell death of MCF-7 cells, and that 1,25-(OH)2D3 generates distinct signals which lead to induction of apoptosis in breast cancer cells.

FTIR spectroscopic investigation of matrix-isolated isomerization and decomposition products of ionized acetone: generation and characterization of 1-propen-2-ol

An electron bombardment – matrix isolation apparatus was used to generate and isolate products from acetone isomerization and decomposition for infrared spectroscopic examination. Bombardment of a dilute acetone/argon gas mixture (1:400) above a 12 K matrix isolation substrate leads to the direct observation of neutral fragmentation and isomerization products. A major product is 1-propen-2-ol, the enolic tautomer of acetone, whose IR absorption spectrum, and that of its perdeutero analog, are interpreted with the aid of ab initio computations. The observation of matrix-isolated decomposition products of acetone such as acetyl radicals, ketene, methane, and CH3• is interpreted in terms of ion and neutral decomposition processes occurring in the gas phase above the matrix surface and during matrix condensation. The detection of matrix-isolated 1-propen-2-ol is consistent with a process involving acetone ionization, isomerization, neutralization, and stabilization, an approach that may have general utility in the generation of other thermodynamically unfavourable neutral isomers of organic molecules. Keywords: enol, isomerization, acetone, infrared, ionization, 1-propen-2-ol.

Structural investigation of ormosils with potential as host photonic materials

Class II ormosils in the systems: methyl, propyl, vinyl and phenyl silicates have been structurally investigated for their suitability as photonic materials and this paper is a precis of many data. From visible and near-infrared spectroscopy these ormosils have: (i) intrinsic optical windows in the visible and at 1.06, 1.3 and 1.55 μ m and (ii) low residual water, despite being synthesised at only 60° C. The residual water can be expelled under vacuum. Solid state29 Si nuclear magnetic resonance spectroscopy shows that matrix condensation increases as the organic content of the matrix is increased; this is accompanied by a decrease in BET surface area.

Nuclear Matrix Condensation and c- myc and c- fos Expression Are Specifically Altered in Cultured Rat Hepatocytes after Exposure to Cyproterone Acetate and Phenobarbital

Regenerative or hyperplastic growth promotes carcinogenesis and can be induced by many nongenotoxic carcinogens. The mitogenic potential of the rodent liver tumor promoters, cyproterone acetate and phenobarbital was investigated in primary rat hepatocyte cultures. Two premitotic markers were analyzed, the expression of two immediate-early genes (c- fos and c- myc) and the decrease in the nuclear quinacrine dihydrochloride fluorescence indicative for a G 0-G 1 cell cycle shift. C- fos expression and decrease in nuclear fluorescence could be induced by both chemicals, phenobarbital being the lesser potent, whereas c- myc expression was only inducible by cyproterone acetate. In situ hybridization with c- myc revealed that both chemicals enhanced c- myc mRNA levels in individual cells, however the number of responding hepatocytes was increased by cyproterone acetate only. The chemical-induced premitotic changes in hepatocytes were highly specific in terms of affected genes and ploidy levels of responding hepatocytes.

Infinitely small element for the dynamic problem of a cracked beam

A super element formulated by using an infinitely small element for analyzing the dynamic behavior of a cracked beam is proposed. It is based on the concept of matrix condensation, using the characteristic properties of the stiffness for the plane elements. A group of infinitely small elements is generated layer by layer around the point of singularity. The subelement around the crack tip can be subdivided to be arbitrarily small to model the stress singularity with sufficient accuracy. The construction of a super element using this approach does not involve special treatment. Therefore, the present method can also be applied to any kind of singularity problems.

Dynamic reliability of large frames

This paper presents a stochastic finite element method (SFEM) for the reliability analysis of dynamically loaded large frames. This is facilitated by the computation of the sensitivity of dynamic response to the randomness in the dynamic excitation as well as in structural properties, by applying the chain rule of differentiation to the deterministic analysis. Since such computation requires large amounts of memory and computational time, matrix condensation is incorporated in SFEM for structures with a large number of degrees of freedom. The computation of response sensitivity and variability is formulated in the context of stiffness and mass matrix condensation. A numerical example with a six-story frame is used to illustrate the proposed method.

Maturation of dense core granules in wild type and mutant Tetrahymena thermophila.

Tetrahymena thermophila, a ciliated protozoan, has a well-developed pathway of regulated secretion from dense core granules called mucocysts. Since exocytosis-defective mutants are available, steps in the biogenesis of dense core granules and their fusion with the plasma membrane may be resolved genetically. To describe the steps in biochemical terms, we have generated antisera against mucocyst content proteins. One antiserum is directed against a calcium binding protein, p40, that is released on stimulation of exocytosis. p40 is shown to associate with an insoluble matrix in mature mucocysts. In addition, the antiserum recognizes a larger protein, p60, that is soluble, is not found in mature mucocysts and is not released on stimulation. Pulse-chase experiments support a precursor-product relationship between p60 and p40. Using these proteins as markers, two mutant Tetrahymena strains defective in exocytosis have been shown to accumulate the putative precursor p60 in organelles that can be distinguished from one another and from wild type mucocysts on the basis of density. The kinetics of appearance of insoluble p40 and the mutant phenotypes suggest a model of mucocyst maturation in which sorting precedes matrix condensation.