PVA matches human liver in needle-tissue interaction.

Science.gov (United States)

de Jong, Tonke L; Pluymen, Loes H; van Gerwen, Dennis J; Kleinrensink, Gert-Jan; Dankelman, Jenny; van den Dobbelsteen, John J

2017-05-01

Medical phantoms can be used to study needle-tissue interaction and to train medical residents. The purpose of this research is to study the suitability of polyvinyl alcohol (PVA) as a liver tissue mimicking material in terms of needle-tissue interaction. Insertions into ex-vivo human livers were used for reference. Six PVA samples were created by varying the mass percentage of PVA to water (4m% and 7m%) and the number of freeze-thaw cycles (1, 2 and 3 cycles, 16hours of freezing at -19°C, 8hours of thawing). The inner needle of an 18 Gauge trocar needle with triangular tip was inserted 13 times into each of the samples, using an insertion velocity of 5 mm/s. In addition, 39 insertions were performed in two ex-vivo human livers. Axial forces on the needle were captured during insertion and retraction and characterized by friction along the needle shaft, peak forces, and number of peak forces per unit length. The concentration of PVA and the number of freeze-thaw cycles both influenced the mechanical interaction between needle and specimen. Insertions into 4m% PVA phantoms with 2 freeze-thaw cycles were comparable to human liver in terms of estimated friction along the needle shaft and the number of peak forces. Therefore, these phantoms are considered to be suitable liver mimicking materials for image-guided needle interventions. The mechanical properties of PVA hydrogels can be influenced in a controlled manner by varying the concentration of PVA and the number of freeze-thaw cycles, to mimic liver tissue characteristics. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hardwiring stem cell communication through tissue structure

Science.gov (United States)

Xin, Tianchi; Greco, Valentina; Myung, Peggy

2016-01-01

Adult stem cells across diverse organs self-renew and differentiate to maintain tissue homeostasis. How stem cells receive input to preserve tissue structure and function largely relies on their communication with surrounding cellular and non-cellular elements. As such, how tissues are organized and patterned not only reflects organ function but also inherently hardwires networks of communication between stem cells and their environment to direct tissue homeostasis and injury repair. This review highlights how different methods of stem cell communication reflect the unique organization and function of diverse tissues. PMID:26967287

Hardwiring Stem Cell Communication through Tissue Structure.

Science.gov (United States)

Xin, Tianchi; Greco, Valentina; Myung, Peggy

2016-03-10

Adult stem cells across diverse organs self-renew and differentiate to maintain tissue homeostasis. How stem cells receive input to preserve tissue structure and function largely relies on their communication with surrounding cellular and non-cellular elements. As such, how tissues are organized and patterned not only reflects organ function, but also inherently hardwires networks of communication between stem cells and their environment to direct tissue homeostasis and injury repair. This review highlights how different methods of stem cell communication reflect the unique organization and function of diverse tissues. Copyright © 2016 Elsevier Inc. All rights reserved.

Molecular Interaction of Bone Marrow Adipose Tissue with Energy Metabolism.

Science.gov (United States)

Suchacki, Karla J; Cawthorn, William P

2018-01-01

The last decade has seen a resurgence in the study of bone marrow adipose tissue (BMAT) across diverse fields such as metabolism, haematopoiesis, skeletal biology and cancer. Herein, we review the most recent developments of BMAT research in both humans and rodents, including the distinct nature of BMAT; the autocrine, paracrine and endocrine interactions between BMAT and various tissues, both in physiological and pathological scenarios; how these interactions might impact energy metabolism; and the most recent technological advances to quantify BMAT. Though still dwarfed by research into white and brown adipose tissues, BMAT is now recognised as endocrine organ and is attracting increasing attention from biomedical researchers around the globe. We are beginning to learn the importance of BMAT both within and beyond the bone, allowing us to better appreciate the role of BMAT in normal physiology and disease.

Numerical Cerebrospinal System Modeling in Fluid-Structure Interaction.

Science.gov (United States)

Garnotel, Simon; Salmon, Stéphanie; Balédent, Olivier

2018-01-01

Cerebrospinal fluid (CSF) stroke volume in the aqueduct is widely used to evaluate CSF dynamics disorders. In a healthy population, aqueduct stroke volume represents around 10% of the spinal stroke volume while intracranial subarachnoid space stroke volume represents 90%. The amplitude of the CSF oscillations through the different compartments of the cerebrospinal system is a function of the geometry and the compliances of each compartment, but we suspect that it could also be impacted be the cardiac cycle frequency. To study this CSF distribution, we have developed a numerical model of the cerebrospinal system taking into account cerebral ventricles, intracranial subarachnoid spaces, spinal canal and brain tissue in fluid-structure interactions. A numerical fluid-structure interaction model is implemented using a finite-element method library to model the cerebrospinal system and its interaction with the brain based on fluid mechanics equations and linear elasticity equations coupled in a monolithic formulation. The model geometry, simplified in a first approach, is designed in accordance with realistic volume ratios of the different compartments: a thin tube is used to mimic the high flow resistance of the aqueduct. CSF velocity and pressure and brain displacements are obtained as simulation results, and CSF flow and stroke volume are calculated from these results. Simulation results show a significant variability of aqueduct stroke volume and intracranial subarachnoid space stroke volume in the physiological range of cardiac frequencies. Fluid-structure interactions are numerous in the cerebrospinal system and difficult to understand in the rigid skull. The presented model highlights significant variations of stroke volumes under cardiac frequency variations only.

Coordinated development of muscles and tendon-like structures: early interactions in the Drosophila leg

Directory of Open Access Journals (Sweden)

cedric esoler

2016-02-01

Full Text Available The formation of the musculoskeletal system is a remarkable example of tissue assembly. In both vertebrates and invertebrates, precise connectivity between muscles and skeleton (or exoskeleton via tendons or equivalent structures is fundamental for movement and stability of the body. The molecular and cellular processes underpinning muscle formation are well established and significant advances have been made in understanding tendon development. However, the mechanisms contributing to proper connection between these two tissues have received less attention. Observations of coordinated development of tendons and muscles suggest these tissues may interact during the different steps in their development. There is growing evidence that, depending on animal model and muscle type, these interactions can take place from progenitor induction to the final step of the formation of the musculoskeletal system. Here we briefly review and compare the mechanisms behind muscle and tendon interaction throughout the development of vertebrates and Drosophila before going on to discuss our recent findings on the coordinated development of muscles and tendon-like structures in Drosophila leg. By altering apodeme formation (the functional Drosophila equivalent of tendons in vertebrates during the early steps of leg development, we affect the spatial localisation of subsequent myoblasts. These findings provide the first evidence of the developmental impact of early interactions between muscle and tendon-like precursors, and confirm the appendicular Drosophila muscle system as a valuable model for studying these processes.

Multiphase poroelastic finite element models for soft tissue structures

International Nuclear Information System (INIS)

Simon, B.R.

1992-01-01

During the last two decades, biological structures with soft tissue components have been modeled using poroelastic or mixture-based constitutive laws, i.e., the material is viewed as a deformable (porous) solid matrix that is saturated by mobile tissue fluid. These structures exhibit a highly nonlinear, history-dependent material behavior; undergo finite strains; and may swell or shrink when tissue ionic concentrations are altered. Give the geometric and material complexity of soft tissue structures and that they are subjected to complicated initial and boundary conditions, finite element models (FEMs) have been very useful for quantitative structural analyses. This paper surveys recent applications of poroelastic and mixture-based theories and the associated FEMs for the study of the biomechanics of soft tissues, and indicates future directions for research in this area. Equivalent finite-strain poroelastic and mixture continuum biomechanical models are presented. Special attention is given to the identification of material properties using a porohyperelastic constitutive law ans a total Lagrangian view for the formulation. The associated FEMs are then formulated to include this porohyperelastic material response and finite strains. Extensions of the theory are suggested in order to include inherent viscoelasticity, transport phenomena, and swelling in soft tissue structures. A number of biomechanical research areas are identified, and possible applications of the porohyperelastic and mixture-based FEMs are suggested. 62 refs., 11 figs., 3 tabs

Multilayered phantoms with tunable optical properties for a better understanding of light/tissue interactions

Science.gov (United States)

Roig, Blandine; Koenig, Anne; Perraut, François; Piot, Olivier; Vignoud, Séverine; Lavaud, Jonathan; Manfait, Michel; Dinten, Jean-Marc

2015-03-01

Light/tissue interactions, like diffuse reflectance, endogenous fluorescence and Raman scattering, are a powerful means for providing skin diagnosis. Instrument calibration is an important step. We thus developed multilayered phantoms for calibration of optical systems. These phantoms mimic the optical properties of biological tissues such as skin. Our final objective is to better understand light/tissue interactions especially in the case of confocal Raman spectroscopy. The phantom preparation procedure is described, including the employed method to obtain a stratified object. PDMS was chosen as the bulk material. TiO2 was used as light scattering agent. Dye and ink were adopted to mimic, respectively, oxy-hemoglobin and melanin absorption spectra. By varying the amount of the incorporated components, we created a material with tunable optical properties. Monolayer and multilayered phantoms were designed to allow several characterization methods. Among them, we can name: X-ray tomography for structural information; Diffuse Reflectance Spectroscopy (DRS) with a homemade fibered bundle system for optical characterization; and Raman depth profiling with a commercial confocal Raman microscope for structural information and for our final objective. For each technique, the obtained results are presented and correlated when possible. A few words are said on our final objective. Raman depth profiles of the multilayered phantoms are distorted by elastic scattering. The signal attenuation through each single layer is directly dependent on its own scattering property. Therefore, determining the optical properties, obtained here with DRS, is crucial to properly correct Raman depth profiles. Thus, it would be permitted to consider quantitative studies on skin for drug permeation follow-up or hydration assessment, for instance.

Neoproteoglycans in tissue engineering

Science.gov (United States)

Weyers, Amanda; Linhardt, Robert J.

2014-01-01

Proteoglycans, comprised of a core protein to which glycosaminoglycan chains are covalently linked, are an important structural and functional family of macromolecules found in the extracellular matrix. Advances in our understanding of biological interactions have lead to a greater appreciation for the need to design tissue engineering scaffolds that incorporate mimetics of key extracellular matrix components. A variety of synthetic and semisynthetic molecules and polymers have been examined by tissue engineers that serve as structural, chemical and biological replacements for proteoglycans. These proteoglycan mimetics have been referred to as neoproteoglycans and serve as functional and therapeutic replacements for natural proteoglycans that are often unavailable for tissue engineering studies. Although neoproteoglycans have important limitations, such as limited signaling ability and biocompatibility, they have shown promise in replacing the natural activity of proteoglycans through cell and protein binding interactions. This review focuses on the recent in vivo and in vitro tissue engineering applications of three basic types of neoproteoglycan structures, protein–glycosaminoglycan conjugates, nano-glycosaminoglycan composites and polymer–glycosaminoglycan complexes. PMID:23399318

The strength of a calcified tissue depends in part on the molecular structure and organization of its constituent mineral crystals in their organic matrix

Science.gov (United States)

Landis, W. J.

1995-01-01

High-voltage electron-microscopic tomographic (3D) studies of the ultrastructural interaction between mineral and organic matrix in a variety of calcified tissues reveal different crystal structural and organizational features in association with their respective organic matrices. In brittle or weak pathologic or ectopic calcifications, including examples of osteogenesis imperfecta, calciphylaxis, calcergy, and dermatomyositis, hydroxyapatite crystals occur in various sizes and shapes and are oriented and aligned with respect to collagen in a manner which is distinct from that found in normal calcified tissues. A model of collagen-mineral interaction is proposed which may account for the observed crystal structures and organization. The results indicate that the ultimate strength, support, and other mechanical properties provided by a calcified tissue are dependent in part upon the molecular structure and arrangement of its constituent mineral crystals within their organic matrix.

Halide peroxidase in tissues that interact with bacteria in the host squid Euprymna scolopes.

Science.gov (United States)

Small, A L; McFall-Ngai, M J

1999-03-15

An enzyme with similarities to myeloperoxidase, the antimicrobial halide peroxidase in mammalian neutrophils, occurs abundantly in the light organ tissue of Euprymna scolopes, a squid that maintains a beneficial association with the luminous bacterium Vibrio fischeri. Using three independent assays typically applied to the analysis of halide peroxidase enzymes, we directly compared the activity of the squid enzyme with that of human myeloperoxidase. One of these methods, the diethanolamine assay, confirmed that the squid peroxidase requires halide ions for its activity. The identification of a halide peroxidase in a cooperative bacterial association suggested that this type of enzyme can function not only to control pathogens, but also to modulate the interactions of host animals with their beneficial partners. To determine whether the squid peroxidase functions under both circumstances, we examined its distribution in a variety of host tissues, including those that typically interact with bacteria and those that do not. Tissues interacting with bacteria included those that have specific cooperative associations with bacteria (i.e., the light organ and accessory nidamental gland) and those that have transient nonspecific interactions with bacteria (i.e., the gills, which clear the cephalopod circulatory system of invading microorganisms). These bacteria-associated tissues were compared with the eye, digestive gland, white body, and ink-producing tissues, which do not typically interact directly with bacteria. Peroxidase enzyme assays, immunocytochemical localization, and DNA-RNA hybridizations showed that the halide-dependent peroxidase is consistently expressed in high concentration in tissues that interact bacteria. Elevated levels of the peroxidase were also found in the ink-producing tissues, which are known to have enzymatic pathways associated with antimicrobial activity. Taken together, these data suggest that the host uses a common biochemical response to

Laser tissue interactions: an update for otolaryngology

Science.gov (United States)

Reinisch, Lou

2000-05-01

We review the laser, characteristics of laser light, the delivery of laser light, pulse lengths and laser tissue interactions. We review these parameters and how they have changed over the history of the laser and how we expect them to change in the future. This survey of laser use is targeted to the otolaryngologist. Very little background in lasers is necessary to follow the discussion. This is intended to introduce and reintroduce laser technology.

Recombinant heparan sulfate for use in tissue engineering applications

DEFF Research Database (Denmark)

Whitelock, J.; Ma, J.L.; Davies, N.

2008-01-01

Background: Heparan sulfate (HS) is an important component of many extracellular matrices that interacts with mitogens and morphogens to guide and control tissue and organ development. These interactions are controlled by its structure, which varies when produced by different cell types and diffe......Background: Heparan sulfate (HS) is an important component of many extracellular matrices that interacts with mitogens and morphogens to guide and control tissue and organ development. These interactions are controlled by its structure, which varies when produced by different cell types...

Matrix metalloproteinase-10/TIMP-2 structure and analyses define conserved core interactions and diverse exosite interactions in MMP/TIMP complexes.

Science.gov (United States)

Batra, Jyotica; Soares, Alexei S; Mehner, Christine; Radisky, Evette S

2013-01-01

Matrix metalloproteinases (MMPs) play central roles in vertebrate tissue development, remodeling, and repair. The endogenous tissue inhibitors of metalloproteinases (TIMPs) regulate proteolytic activity by binding tightly to the MMP active site. While each of the four TIMPs can inhibit most MMPs, binding data reveal tremendous heterogeneity in affinities of different TIMP/MMP pairs, and the structural features that differentiate stronger from weaker complexes are poorly understood. Here we report the crystal structure of the comparatively weakly bound human MMP-10/TIMP-2 complex at 2.1 Å resolution. Comparison with previously reported structures of MMP-3/TIMP-1, MT1-MMP/TIMP-2, MMP-13/TIMP-2, and MMP-10/TIMP-1 complexes offers insights into the structural basis of binding selectivity. Our analyses identify a group of highly conserved contacts at the heart of MMP/TIMP complexes that define the conserved mechanism of inhibition, as well as a second category of diverse adventitious contacts at the periphery of the interfaces. The AB loop of the TIMP N-terminal domain and the contact loops of the TIMP C-terminal domain form highly variable peripheral contacts that can be considered as separate exosite interactions. In some complexes these exosite contacts are extensive, while in other complexes the AB loop or C-terminal domain contacts are greatly reduced and appear to contribute little to complex stability. Our data suggest that exosite interactions can enhance MMP/TIMP binding, although in the relatively weakly bound MMP-10/TIMP-2 complex they are not well optimized to do so. Formation of highly variable exosite interactions may provide a general mechanism by which TIMPs are fine-tuned for distinct regulatory roles in biology.

Fluid-structure interaction including volumetric coupling with homogenised subdomains for modeling respiratory mechanics.

Science.gov (United States)

Yoshihara, Lena; Roth, Christian J; Wall, Wolfgang A

2017-04-01

In this article, a novel approach is presented for combining standard fluid-structure interaction with additional volumetric constraints to model fluid flow into and from homogenised solid domains. The proposed algorithm is particularly interesting for investigations in the field of respiratory mechanics as it enables the mutual coupling of airflow in the conducting part and local tissue deformation in the respiratory part of the lung by means of a volume constraint. In combination with a classical monolithic fluid-structure interaction approach, a comprehensive model of the human lung can be established that will be useful to gain new insights into respiratory mechanics in health and disease. To illustrate the validity and versatility of the novel approach, three numerical examples including a patient-specific lung model are presented. The proposed algorithm proves its capability of computing clinically relevant airflow distribution and tissue strain data at a level of detail that is not yet achievable, neither with current imaging techniques nor with existing computational models. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Nanoscale tissue engineering: spatial control over cell-materials interactions

Science.gov (United States)

Wheeldon, Ian; Farhadi, Arash; Bick, Alexander G.; Jabbari, Esmaiel; Khademhosseini, Ali

2011-01-01

Cells interact with the surrounding environment by making tens to hundreds of thousands of nanoscale interactions with extracellular signals and features. The goal of nanoscale tissue engineering is to harness the interactions through nanoscale biomaterials engineering in order to study and direct cellular behaviors. Here, we review the nanoscale tissue engineering technologies for both two- and three-dimensional studies (2- and 3D), and provide a holistic overview of the field. Techniques that can control the average spacing and clustering of cell adhesion ligands are well established and have been highly successful in describing cell adhesion and migration in 2D. Extension of these engineering tools to 3D biomaterials has created many new hydrogel and nanofiber scaffolds technologies that are being used to design in vitro experiments with more physiologically relevant conditions. Researchers are beginning to study complex cell functions in 3D, however, there is a need for biomaterials systems that provide fine control over the nanoscale presentation of bioactive ligands in 3D. Additionally, there is a need for 2- and 3D techniques that can control the nanoscale presentation of multiple bioactive ligands and the temporal changes in cellular microenvironment. PMID:21451238

Nanoscale tissue engineering: spatial control over cell-materials interactions

International Nuclear Information System (INIS)

Wheeldon, Ian; Farhadi, Arash; Bick, Alexander G; Khademhosseini, Ali; Jabbari, Esmaiel

2011-01-01

Cells interact with the surrounding environment by making tens to hundreds of thousands of nanoscale interactions with extracellular signals and features. The goal of nanoscale tissue engineering is to harness these interactions through nanoscale biomaterials engineering in order to study and direct cellular behavior. Here, we review two- and three-dimensional (2- and 3D) nanoscale tissue engineering technologies, and provide a holistic overview of the field. Techniques that can control the average spacing and clustering of cell adhesion ligands are well established and have been highly successful in describing cell adhesion and migration in 2D. Extension of these engineering tools to 3D biomaterials has created many new hydrogel and nanofiber scaffold technologies that are being used to design in vitro experiments with more physiologically relevant conditions. Researchers are beginning to study complex cell functions in 3D. However, there is a need for biomaterials systems that provide fine control over the nanoscale presentation of bioactive ligands in 3D. Additionally, there is a need for 2- and 3D techniques that can control the nanoscale presentation of multiple bioactive ligands and that can control the temporal changes in the cellular microenvironment. (topical review)

Interactive classification and content-based retrieval of tissue images

Science.gov (United States)

Aksoy, Selim; Marchisio, Giovanni B.; Tusk, Carsten; Koperski, Krzysztof

2002-11-01

We describe a system for interactive classification and retrieval of microscopic tissue images. Our system models tissues in pixel, region and image levels. Pixel level features are generated using unsupervised clustering of color and texture values. Region level features include shape information and statistics of pixel level feature values. Image level features include statistics and spatial relationships of regions. To reduce the gap between low-level features and high-level expert knowledge, we define the concept of prototype regions. The system learns the prototype regions in an image collection using model-based clustering and density estimation. Different tissue types are modeled using spatial relationships of these regions. Spatial relationships are represented by fuzzy membership functions. The system automatically selects significant relationships from training data and builds models which can also be updated using user relevance feedback. A Bayesian framework is used to classify tissues based on these models. Preliminary experiments show that the spatial relationship models we developed provide a flexible and powerful framework for classification and retrieval of tissue images.

Interaction of a pulsed alexandrite laser with hard and soft biological tissue

Science.gov (United States)

Paterson, Lorna M.; Dickinson, Mark R.; King, Terence A.; Watts, David C.

1994-02-01

An alexandrite laser has been used in the fixed-Q and Q-switched modes, at the fundamental and frequency doubled wavelengths on a selection of hard and soft tissue. In an investigation into the potential use of the laser for the removal of deep lying lesions such as cutaneous vascular lesions and tatoos, studies have been carried out to characterize the depth and extent of the laser/tissue interaction in samples of tissue which greatly absorb the 750 nm radiation. The interaction of the laser radiation with extracted teeth was investigated looking at healthy enamel and dentine, and caries. Surface profile measurements of the enamel and dentine before and after irradiation show little physical effect of the laser irradiation, whereas caries appear to be ablated.

X- and γ-ray interaction characteristics of Griffith, Alderson, Frigerio, Goodman and Rossi tissue substitutes

International Nuclear Information System (INIS)

Singh, V. P.; Badiger, N. M.; Vega C, H. R.

2015-10-01

Detailed information of radiation interaction, exposure and dose delivery to tissue substitutes is necessary for various branches of radiation physics. In the present investigation X- and γ-ray interaction characteristics of some tissue substitutes such as Griffith, Alderson, Frigerio, Goodman and Rossi have been studied and compared with standard tissues. Effective atomic numbers and air-kerma have been computed using mass attenuation coefficients and mass energy-absorption coefficients, respectively. Energy-absorption buildup factors for photon energy 0.015 to 15 MeV up to 40 mean free path were calculated using G-P fitting method. These investigations provide further information on the X- and γ-ray interaction of tissue substitutes for various applications in radiation physics and medical physics. (Author)

X- and γ-ray interaction characteristics of Griffith, Alderson, Frigerio, Goodman and Rossi tissue substitutes

Energy Technology Data Exchange (ETDEWEB)

Singh, V. P.; Badiger, N. M. [Karnatak University, Department of Physics, Dharwad-580003, Karnataka (India); Vega C, H. R., E-mail: kudphyvps@rediffmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico)

2015-10-15

Detailed information of radiation interaction, exposure and dose delivery to tissue substitutes is necessary for various branches of radiation physics. In the present investigation X- and γ-ray interaction characteristics of some tissue substitutes such as Griffith, Alderson, Frigerio, Goodman and Rossi have been studied and compared with standard tissues. Effective atomic numbers and air-kerma have been computed using mass attenuation coefficients and mass energy-absorption coefficients, respectively. Energy-absorption buildup factors for photon energy 0.015 to 15 MeV up to 40 mean free path were calculated using G-P fitting method. These investigations provide further information on the X- and γ-ray interaction of tissue substitutes for various applications in radiation physics and medical physics. (Author)

Disease related tissue damage and subsequent changes in fillet structure

DEFF Research Database (Denmark)

of the fish and subsequent a reduction in price. Despite this, the impact of infectious diseases on the meat quality and the mechanisms behind are poorly investigated. Wound repair is a dynamic, interactive response to tissue injury that involves a complex interaction and cross talk of various cell types......, extracellular matrix molecules, soluble mediators and cytokines. In order to describe the molecular mechanisms and processes of wound repair, a panel of genes covering immunological factors and tissue regeneration were used to measure changes at the mRNA level following mechanical tissue damage in rainbow trout...... (Oncorhynchus mykiss). Needle disrupted muscle tissue was sampled at different time points and subject to real-time RT-PCR for measuring the expression of the genes IL-1β, IL-8, IL-10, TGF-β, Myostatin-1ab, MMP-2, CTGF, Collagen-1α, VEGF, iNOS, Arg-2 and FGF. The results showed an initial phase with up...

The epithelial-mesenchymal interactions: insights into physiological and pathological aspects of oral tissues.

Science.gov (United States)

Santosh, Arvind Babu Rajendra; Jones, Thaon Jon

2014-03-17

In the human biological system, the individual cells divide and form tissues and organs. These tissues are hetero-cellular. Basically any tissue consists of an epithelium and the connective tissue. The latter contains mainly mesenchymally-derived tissues with a diversified cell population. The cell continues to grow and differentiate in a pre-programmed manner using a messenger system. The epithelium and the mesenchymal portion of each tissue have two different origins and perform specific functions, but there is a well-defined interaction mechanism, which mediates between them. Epithelial mesenchymal interactions (EMIs) are part of this mechanism, which can be regarded as a biological conversation between epithelial and mesenchymal cell populations involved in the cellular differentiation of one or both cell populations. EMIs represent a process that is essential for cell growth, cell differentiation and cell multiplication. EMIs are associated with normal physiological processes in the oral cavity, such as odontogenesis, dentino-enamel junction formation, salivary gland development, palatogenesis, and also pathological processes, such as oral cancer. This paper focuses the role EMIs in odontogenesis, salivary gland development, palatogenesis and oral cancer.

Electrical circuit modeling and analysis of microwave acoustic interaction with biological tissues.

Science.gov (United States)

Gao, Fei; Zheng, Qian; Zheng, Yuanjin

2014-05-01

Numerical study of microwave imaging and microwave-induced thermoacoustic imaging utilizes finite difference time domain (FDTD) analysis for simulation of microwave and acoustic interaction with biological tissues, which is time consuming due to complex grid-segmentation and numerous calculations, not straightforward due to no analytical solution and physical explanation, and incompatible with hardware development requiring circuit simulator such as SPICE. In this paper, instead of conventional FDTD numerical simulation, an equivalent electrical circuit model is proposed to model the microwave acoustic interaction with biological tissues for fast simulation and quantitative analysis in both one and two dimensions (2D). The equivalent circuit of ideal point-like tissue for microwave-acoustic interaction is proposed including transmission line, voltage-controlled current source, envelop detector, and resistor-inductor-capacitor (RLC) network, to model the microwave scattering, thermal expansion, and acoustic generation. Based on which, two-port network of the point-like tissue is built and characterized using pseudo S-parameters and transducer gain. Two dimensional circuit network including acoustic scatterer and acoustic channel is also constructed to model the 2D spatial information and acoustic scattering effect in heterogeneous medium. Both FDTD simulation, circuit simulation, and experimental measurement are performed to compare the results in terms of time domain, frequency domain, and pseudo S-parameters characterization. 2D circuit network simulation is also performed under different scenarios including different sizes of tumors and the effect of acoustic scatterer. The proposed circuit model of microwave acoustic interaction with biological tissue could give good agreement with FDTD simulated and experimental measured results. The pseudo S-parameters and characteristic gain could globally evaluate the performance of tumor detection. The 2D circuit network

Structural Variation and Uniformity among Tetraloop-Receptor Interactions and Other Loop-Helix Interactions in RNA Crystal Structures

Science.gov (United States)

Wu, Li; Chai, Dinggeng; Fraser, Marie E.; Zimmerly, Steven

2012-01-01

Tetraloop-receptor interactions are prevalent structural units in RNAs, and include the GAAA/11-nt and GNRA-minor groove interactions. In this study, we have compiled a set of 78 nonredundant loop-helix interactions from X-ray crystal structures, and examined them for the extent of their sequence and structural variation. Of the 78 interactions in the set, only four were classical GAAA/11-nt motifs, while over half (48) were GNRA-minor groove interactions. The GNRA-minor groove interactions were not a homogeneous set, but were divided into five subclasses. The most predominant subclass is characterized by two triple base pair interactions in the minor groove, flanked by two ribose zipper contacts. This geometry may be considered the “standard” GNRA-minor groove interaction, while the other four subclasses are alternative ways to form interfaces between a minor groove and tetraloop. The remaining 26 structures in the set of 78 have loops interacting with mostly idiosyncratic receptors. Among the entire set, a number of sequence-structure correlations can be identified, which may be used as initial hypotheses in predicting three-dimensional structures from primary sequences. Conversely, other sequence patterns are not predictive; for example, GAAA loop sequences and GG/CC receptors bind to each other with three distinct geometries. Finally, we observe an example of structural evolution in group II introns, in which loop-receptor motifs are substituted for each other while maintaining the larger three-dimensional geometry. Overall, the study gives a more complete view of RNA loop-helix interactions that exist in nature. PMID:23152878

Matrix metalloproteinase-10/TIMP-2 structure and analyses define conserved core interactions and diverse exosite interactions in MMP/TIMP complexes.

Directory of Open Access Journals (Sweden)

Jyotica Batra

Full Text Available Matrix metalloproteinases (MMPs play central roles in vertebrate tissue development, remodeling, and repair. The endogenous tissue inhibitors of metalloproteinases (TIMPs regulate proteolytic activity by binding tightly to the MMP active site. While each of the four TIMPs can inhibit most MMPs, binding data reveal tremendous heterogeneity in affinities of different TIMP/MMP pairs, and the structural features that differentiate stronger from weaker complexes are poorly understood. Here we report the crystal structure of the comparatively weakly bound human MMP-10/TIMP-2 complex at 2.1 Å resolution. Comparison with previously reported structures of MMP-3/TIMP-1, MT1-MMP/TIMP-2, MMP-13/TIMP-2, and MMP-10/TIMP-1 complexes offers insights into the structural basis of binding selectivity. Our analyses identify a group of highly conserved contacts at the heart of MMP/TIMP complexes that define the conserved mechanism of inhibition, as well as a second category of diverse adventitious contacts at the periphery of the interfaces. The AB loop of the TIMP N-terminal domain and the contact loops of the TIMP C-terminal domain form highly variable peripheral contacts that can be considered as separate exosite interactions. In some complexes these exosite contacts are extensive, while in other complexes the AB loop or C-terminal domain contacts are greatly reduced and appear to contribute little to complex stability. Our data suggest that exosite interactions can enhance MMP/TIMP binding, although in the relatively weakly bound MMP-10/TIMP-2 complex they are not well optimized to do so. Formation of highly variable exosite interactions may provide a general mechanism by which TIMPs are fine-tuned for distinct regulatory roles in biology.

Mechanotransduction mechanisms in growing spherically structured tissues

Science.gov (United States)

Littlejohns, Euan; Dunlop, Carina M.

2018-04-01

There is increasing experimental interest in mechanotransduction in multi-cellular tissues as opposed to single cells. This is driven by a growing awareness of the importance of physiologically relevant three-dimensional culture and of cell–cell and cell–gel interactions in directing growth and development. The paradigm biophysical technique for investigating tissue level mechanobiology in this context is to grow model tissues in artificial gels with well-defined mechanical properties. These studies often indicate that the stiffness of the encapsulating gel can significantly alter cellular behaviours. We demonstrate here potential mechanisms linking tissue growth with stiffness-mediated mechanotransduction. We show how tissue growth in gel systems generates points at which there is a significant qualitative change in the cellular stress and strain experienced. We show analytically how these potential switching points depend on the mechanical properties of the constraining gel and predict when they will occur. Significantly, we identify distinct mechanisms that act separately in each of the stress and strain fields at different times. These observations suggest growth as a potential physical mechanism coupling gel stiffness with cellular mechanotransduction in three-dimensional tissues. We additionally show that non-proliferating areas, in the case that the constraining gel is soft compared with the tissue, will expand and contract passively as a result of growth. Central compartment size is thus seen to not be a reliable indicator on its own for growth initiation or active behaviour.

Biology of Bone Tissue: Structure, Function, and Factors That Influence Bone Cells.

Science.gov (United States)

Florencio-Silva, Rinaldo; Sasso, Gisela Rodrigues da Silva; Sasso-Cerri, Estela; Simões, Manuel Jesus; Cerri, Paulo Sérgio

2015-01-01

Bone tissue is continuously remodeled through the concerted actions of bone cells, which include bone resorption by osteoclasts and bone formation by osteoblasts, whereas osteocytes act as mechanosensors and orchestrators of the bone remodeling process. This process is under the control of local (e.g., growth factors and cytokines) and systemic (e.g., calcitonin and estrogens) factors that all together contribute for bone homeostasis. An imbalance between bone resorption and formation can result in bone diseases including osteoporosis. Recently, it has been recognized that, during bone remodeling, there are an intricate communication among bone cells. For instance, the coupling from bone resorption to bone formation is achieved by interaction between osteoclasts and osteoblasts. Moreover, osteocytes produce factors that influence osteoblast and osteoclast activities, whereas osteocyte apoptosis is followed by osteoclastic bone resorption. The increasing knowledge about the structure and functions of bone cells contributed to a better understanding of bone biology. It has been suggested that there is a complex communication between bone cells and other organs, indicating the dynamic nature of bone tissue. In this review, we discuss the current data about the structure and functions of bone cells and the factors that influence bone remodeling.

Pre-set extrusion bioprinting for multiscale heterogeneous tissue structure fabrication.

Science.gov (United States)

Kang, Donggu; Ahn, Geunseon; Kim, Donghwan; Kang, Hyun-Wook; Yun, Seokhwan; Yun, Won-Soo; Shim, Jin-Hyung; Jin, Songwan

2018-06-06

Recent advances in three-dimensional bioprinting technology have led to various attempts in fabricating human tissue-like structures. However, current bioprinting technologies have limitations for creating native tissue-like structures. To resolve these issues, we developed a new pre-set extrusion bioprinting technique that can create heterogeneous, multicellular, and multimaterial structures simultaneously. The key to this ability lies in the use of a precursor cartridge that can stably preserve a multimaterial with a pre-defined configuration that can be simply embedded in a syringe-based printer head. The multimaterial can be printed and miniaturized through a micro-nozzle without conspicuous deformation according to the pre-defined configuration of the precursor cartridge. Using this system, we fabricated heterogeneous tissue-like structures such as spinal cords, hepatic lobule, blood vessels, and capillaries. We further obtained a heterogeneous patterned model that embeds HepG2 cells with endothelial cells in a hepatic lobule-like structure. In comparison with homogeneous and heterogeneous cell printing, the heterogeneous patterned model showed a well-organized hepatic lobule structure and higher enzyme activity of CYP3A4. Therefore, this pre-set extrusion bioprinting method could be widely used in the fabrication of a variety of artificial and functional tissues or organs.

Structural changes in connective tissues caused by a moderate laser heating

International Nuclear Information System (INIS)

Bagratashvili, Viktor N; Bagratashvili, N V; Sviridov, A P; Shakh, G Sh; Ignat'eva, Natalia Yu; Lunin, Valery V; Grokhovskaya, T E; Averkiev, S V

2002-01-01

The structural changes in adipose and fibrous tissues caused by 2- and 3-W IR laser irradiation are studied by the methods of IR and Raman spectroscopy and differential scanning calorimetry. It is shown that heating of fibrous tissue samples to 50 0 C and adipose tissue samples to 75 0 C by IR laser radiation changes the supramolecular structure of their proteins and triacylglycerides, respectively, without the intramolecular bond breaking. Heating of fibrous tissue to 70 0 C and adipose tissue to 90 - 110 0 C leads to a partial reversible denaturation of proteins and to oxidation of fats.

Tissue-specific interactions between nuclear proteins and the aminopeptidase N promoter

DEFF Research Database (Denmark)

Kärnström, U; Sjöström, H; Norén, O

1991-01-01

Aminopeptidase N/CD13 is a metallopeptidase found in many tissues. Aminopeptidase N activity is high in the small intestinal mucosa, moderate in the liver, and low in the spleen. Using DNase I footprinting and electrophoretic mobility shift assays with nuclear extracts from these tissues, three cis...... elements (DF, LF-B1, UF) were identified in the aminopeptidase N promoter. The DF region (-53 to -30) interacts with the ubiquitously expressed transcription factor Sp1. The LF-B1 region (-85 to -58) interacts with the liver transcription factor LF-B1 (HNF-1) which was detected as well in nuclei from small...... intestinal mucosa. The UF region (-112 to -90) interacts with nuclear factors which seem to be expressed differentially in the liver and the small intestine. Transfection of promoter deletions into HepG2 cells showed that the LF-B1 region is necessary for high expression of the aminopeptidase N gene in liver...

Topology of RNA-RNA interaction structures

DEFF Research Database (Denmark)

Andersen, Jørgen Ellegaard; Huang, Fenix Wenda; Penner, Robert

2012-01-01

Abstract The topological filtration of interacting RNA complexes is studied, and the role is analyzed of certain diagrams called irreducible shadows, which form suitable building blocks for more general structures. We prove that, for two interacting RNAs, called interaction structures, there exist...

Matrix metalloproteinase-10 (MMP-10) interaction with tissue inhibitors of metalloproteinases TIMP-1 and TIMP-2: binding studies and crystal structure.

Science.gov (United States)

Batra, Jyotica; Robinson, Jessica; Soares, Alexei S; Fields, Alan P; Radisky, Derek C; Radisky, Evette S

2012-05-04

Matrix metalloproteinase 10 (MMP-10, stromelysin-2) is a secreted metalloproteinase with functions in skeletal development, wound healing, and vascular remodeling; its overexpression is also implicated in lung tumorigenesis and tumor progression. To understand the regulation of MMP-10 by tissue inhibitors of metalloproteinases (TIMPs), we have assessed equilibrium inhibition constants (K(i)) of putative physiological inhibitors TIMP-1 and TIMP-2 for the active catalytic domain of human MMP-10 (MMP-10cd) using multiple kinetic approaches. We find that TIMP-1 inhibits the MMP-10cd with a K(i) of 1.1 × 10(-9) M; this interaction is 10-fold weaker than the inhibition of the similar MMP-3 (stromelysin-1) catalytic domain (MMP-3cd) by TIMP-1. TIMP-2 inhibits the MMP-10cd with a K(i) of 5.8 × 10(-9) M, which is again 10-fold weaker than the inhibition of MMP-3cd by this inhibitor (K(i) = 5.5 × 10(-10) M). We solved the x-ray crystal structure of TIMP-1 bound to the MMP-10cd at 1.9 Å resolution; the structure was solved by molecular replacement and refined with an R-factor of 0.215 (R(free) = 0.266). Comparing our structure of MMP-10cd·TIMP-1 with the previously solved structure of MMP-3cd·TIMP-1 (Protein Data Bank entry 1UEA), we see substantial differences at the binding interface that provide insight into the differential binding of stromelysin family members to TIMP-1. This structural information may ultimately assist in the design of more selective TIMP-based inhibitors tailored for specificity toward individual members of the stromelysin family, with potential therapeutic applications.

The epithelial-mesenchymal interactions: insights into physiological and pathological aspects of oral tissues

Directory of Open Access Journals (Sweden)

Arvind Babu Rajendra Santosh

2014-03-01

Full Text Available In the human biological system, the individual cells divide and form tissues and organs. These tissues are hetero-cellular. Basically any tissue consists of an epithelium and the connective tissue. The latter contains mainly mesenchymally-derived tissues with a diversified cell population. The cell continues to grow and differentiate in a pre-programmed manner using a messenger system. The epithelium and the mesenchymal portion of each tissue have two different origins and perform specific functions, but there is a well-defined interaction mechanism, which mediates between them. Epithelial mesenchymal interactions (EMIs are part of this mechanism, which can be regarded as a biological conversation between epithelial and mesenchymal cell populations involved in the cellular differentiation of one or both cell populations. EMIs represent a process that is essential for cell growth, cell differentiation and cell multiplication. EMIs are associated with normal physiological processes in the oral cavity, such as odontogenesis, dentino-enamel junction formation, salivary gland development, palatogenesis, and also pathological processes, such as oral cancer. This paper focuses the role EMIs in odontogenesis, salivary gland development, palatogenesis and oral cancer.

LATIS3D The Gold Standard for Laser-Tissue-Interaction Modeling

CERN Document Server

London, R A; Gentile, N A; Kim, B M; Makarewicz, A M; Vincent, L; Yang, Y B

2000-01-01

The goal of this LDRD project has been to create LATIS3D--the world's premier computer program for laser-tissue interaction modeling. The development was based on recent experience with the 2D LATIS code and the ASCI code, KULL. With LATIS3D, important applications in laser medical therapy were researched including dynamical calculations of tissue emulsification and ablation, photothermal therapy, and photon transport for photodynamic therapy. This project also enhanced LLNL's core competency in laser-matter interactions and high-energy-density physics by pushing simulation codes into new parameter regimes and by attracting external expertise. This will benefit both existing LLNL programs such as ICF and SBSS and emerging programs in medical technology and other laser applications.

LATIS3D: The Gold Standard for Laser-Tissue-Interaction Modeling

International Nuclear Information System (INIS)

London, R.A.; Makarewicz, A.M.; Kim, B.M.; Gentile, N.A.; Yang, Y.B.; Brlik, M.; Vincent, L.

2000-01-01

The goal of this LDRD project has been to create LATIS3D--the world's premier computer program for laser-tissue interaction modeling. The development was based on recent experience with the 2D LATIS code and the ASCI code, KULL. With LATIS3D, important applications in laser medical therapy were researched including dynamical calculations of tissue emulsification and ablation, photothermal therapy, and photon transport for photodynamic therapy. This project also enhanced LLNL's core competency in laser-matter interactions and high-energy-density physics by pushing simulation codes into new parameter regimes and by attracting external expertise. This will benefit both existing LLNL programs such as ICF and SBSS and emerging programs in medical technology and other laser applications

Fluid Structure Interaction for Hydraulic Problems

International Nuclear Information System (INIS)

Souli, Mhamed; Aquelet, Nicolas

2011-01-01

Fluid Structure interaction plays an important role in engineering applications. Physical phenomena such as flow induced vibration in nuclear industry, fuel sloshing tank in automotive industry or rotor stator interaction in turbo machinery, can lead to structure deformation and sometimes to failure. In order to solve fluid structure interaction problems, the majority of numerical tests consists in using two different codes to separately solve pressure of the fluid and structural displacements. In this paper, a unique code with an ALE formulation approach is used to implicitly calculate the pressure of an incompressible fluid applied to the structure. The development of the ALE method as well as the coupling in a computational structural dynamic code, allows to solve more large industrial problems related to fluid structure coupling. (authors)

An Error Analysis of Structured Light Scanning of Biological Tissue

DEFF Research Database (Denmark)

Jensen, Sebastian Hoppe Nesgaard; Wilm, Jakob; Aanæs, Henrik

2017-01-01

This paper presents an error analysis and correction model for four structured light methods applied to three common types of biological tissue; skin, fat and muscle. Despite its many advantages, structured light is based on the assumption of direct reflection at the object surface only......, statistical linear model based on the scan geometry. As such, scans can be corrected without introducing any specially designed pattern strategy or hardware. We can effectively reduce the error in a structured light scanner applied to biological tissue by as much as factor of two or three........ This assumption is violated by most biological material e.g. human skin, which exhibits subsurface scattering. In this study, we find that in general, structured light scans of biological tissue deviate significantly from the ground truth. We show that a large portion of this error can be predicted with a simple...

The dorsal skinfold chamber: window into the dynamic interaction of biomaterials with their surrounding host tissue

Directory of Open Access Journals (Sweden)

MW Laschke

2011-09-01

Full Text Available The implantation of biomaterials into the human body has become an indispensable part of almost all fields of modern medicine. Accordingly, there is an increasing need for appropriate approaches, which can be used to evaluate the suitability of different biomaterials for distinct clinical indications. The dorsal skinfold chamber is a sophisticated experimental model, which has been proven to be extremely valuable for the systematic in vivo analysis of the dynamic interaction of small biomaterial implants with the surrounding host tissue in rats, hamsters and mice. By means of intravital fluorescence microscopy, this chronic model allows for repeated analyses of various cellular, molecular and microvascular mechanisms, which are involved in the early inflammatory and angiogenic host tissue response to biomaterials during the initial 2-3 weeks after implantation. Therefore, the dorsal skinfold chamber has been broadly used during the last two decades to assess the in vivo performance of prosthetic vascular grafts, metallic implants, surgical meshes, bone substitutes, scaffolds for tissue engineering, as well as for locally or systemically applied drug delivery systems. These studies have contributed to identify basic material properties determining the biocompatibility of the implants and vascular ingrowth into their surface or internal structures. Thus, the dorsal skinfold chamber model does not only provide deep insights into the complex interactions of biomaterials with the surrounding soft tissues of the host but also represents an important tool for the future development of novel biomaterials aiming at an optimisation of their biofunctionality in clinical practice.

Some considerations on the dynamic structure-soil-structure interactions analysis

International Nuclear Information System (INIS)

Matthees, W.

1979-01-01

A mixed method has been developed for the approximate analysis of soil-structure or structure-soil-structure interaction problems due to earthquakes. In order to produce comparable results of interaction problems as well as for shallow and for deep soils due to the same earthquake excitation (accelerogram) situated always at the lower bedrock boundary, the analysis is performed in two steps: 1) Calculation of the complex transfer function and the response of the upper interior boundary of a layered soil-system which is connected at its top to a soil-structure-system, using the one-dimensional deconvolution. 2) By making a complete interaction analysis of the surface soil-structure-system using the interior boundary excitation of the calculated response from step 1. The depth of the soil-structure-system must be chosen large enough to exclude interaction effects down to the layered soil-system's interior boundary. (orig.)

Fluid-structure interaction of submerged structures

International Nuclear Information System (INIS)

Tang, H.T.; Becker, E.B.; Taylor, L.M.

1979-01-01

The purpose of the paper is to investigate fluid-structure interaction (FSI) of submerged structures in a confined fluid-structure system. Our particular interest is the load experienced by a rigid submerged structure subject to a pressure excitation in a fluid domain bounded by a structure which is either flexible or rigid. The objective is to see whether the load experienced by the submerged structure will be influenced by its confinement conditions. This investigation is intended to provide insight into the characteristics of FSI and answer the question as to whether one can obtain FSI independent data by constructing a small scale rigid submerged structure inside a flexible fluid-structure system. (orig.)

[Lasers in dentistry. Part B--Interaction with biological tissues and the effect on the soft tissues of the oral cavity, the hard tissues of the tooth and the dental pulp].

Science.gov (United States)

Moshonov, J; Stabholz, A; Leopold, Y; Rosenberg, I; Stabholz, A

2001-10-01

The interaction of laser energy with target tissue is mainly determined by two non operator-dependent factors: the specific wavelength of the laser and the optical properties of the target tissues. Power density, energy density, pulse repetition rate, pulse duration and the mode of energy transferring to the tissue are dictated by the clinician. Combination of these factors enables to control optimal response for the clinical application. Four responses are described when the laser beam hits the target tissue: reflection, absorption, transmission and scattering. Three main mechanisms of interaction between the laser and the biological tissues exist: photothermic, photoacoustic and photochemical. The effect of lasers on the soft tissues of the oral cavity is based on transformation of light energy into thermal energy which, in turn heats the target tissue to produce the desirable effect. In comparison to the scalpel used in surgical procedures, the laser beam is characterized by tissue natural sterility and by minimum bleeding during the surgical procedures due to blood vessels welding. The various effects achieved by the temperature elevation during the laser application on the soft tissue are: I. coagulation and hemostasis II. tissue sterilization III. tissue welding IV. incision and excision V. ablation and vaporization Ablation and melting are the two basic modalities by which the effect of lasers on the hard tissues of the tooth is produced. When discussing the effect of laser on dental hard tissues, the energy absorption in the hydroxyapatite plays a major role in addition to its absorption in water. When laser energy is absorbed in the water of the hard tissues, a rapid volume expansion of the evaporating water occurs as a result of a substantial temperature elevation in the interaction site. Microexplosions are produced causing hard tissue disintegration. If pulp temperatures are raised beyond 5 degrees C level, damage to the dental pulp is irreversible

Community Structure Analysis of Gene Interaction Networks in Duchenne Muscular Dystrophy.

Directory of Open Access Journals (Sweden)

Tejaswini Narayanan

Full Text Available Duchenne Muscular Dystrophy (DMD is an important pathology associated with the human skeletal muscle and has been studied extensively. Gene expression measurements on skeletal muscle of patients afflicted with DMD provides the opportunity to understand the underlying mechanisms that lead to the pathology. Community structure analysis is a useful computational technique for understanding and modeling genetic interaction networks. In this paper, we leverage this technique in combination with gene expression measurements from normal and DMD patient skeletal muscle tissue to study the structure of genetic interactions in the context of DMD. We define a novel framework for transforming a raw dataset of gene expression measurements into an interaction network, and subsequently apply algorithms for community structure analysis for the extraction of topological communities. The emergent communities are analyzed from a biological standpoint in terms of their constituent biological pathways, and an interpretation that draws correlations between functional and structural organization of the genetic interactions is presented. We also compare these communities and associated functions in pathology against those in normal human skeletal muscle. In particular, differential enhancements are observed in the following pathways between pathological and normal cases: Metabolic, Focal adhesion, Regulation of actin cytoskeleton and Cell adhesion, and implication of these mechanisms are supported by prior work. Furthermore, our study also includes a gene-level analysis to identify genes that are involved in the coupling between the pathways of interest. We believe that our results serve to highlight important distinguishing features in the structural/functional organization of constituent biological pathways, as it relates to normal and DMD cases, and provide the mechanistic basis for further biological investigations into specific pathways differently regulated

Biology of Bone Tissue: Structure, Function, and Factors That Influence Bone Cells

Directory of Open Access Journals (Sweden)

Rinaldo Florencio-Silva

2015-01-01

Full Text Available Bone tissue is continuously remodeled through the concerted actions of bone cells, which include bone resorption by osteoclasts and bone formation by osteoblasts, whereas osteocytes act as mechanosensors and orchestrators of the bone remodeling process. This process is under the control of local (e.g., growth factors and cytokines and systemic (e.g., calcitonin and estrogens factors that all together contribute for bone homeostasis. An imbalance between bone resorption and formation can result in bone diseases including osteoporosis. Recently, it has been recognized that, during bone remodeling, there are an intricate communication among bone cells. For instance, the coupling from bone resorption to bone formation is achieved by interaction between osteoclasts and osteoblasts. Moreover, osteocytes produce factors that influence osteoblast and osteoclast activities, whereas osteocyte apoptosis is followed by osteoclastic bone resorption. The increasing knowledge about the structure and functions of bone cells contributed to a better understanding of bone biology. It has been suggested that there is a complex communication between bone cells and other organs, indicating the dynamic nature of bone tissue. In this review, we discuss the current data about the structure and functions of bone cells and the factors that influence bone remodeling.

Evaluation of Tissue Interactions with Mechanical Elements of a Transscleral Drug Delivery Device

Directory of Open Access Journals (Sweden)

Jeffrey T. Borenstein

2012-03-01

Full Text Available The goal of this work was to evaluate tissue-device interactions due to implantation of a mechanically operated drug delivery system onto the posterior sclera. Two test devices were designed and fabricated to model elements of the drug delivery device—one containing a free-spinning ball bearing and the other encasing two articulating gears. Openings in the base of test devices modeled ports for drug passage from device to sclera. Porous poly(tetrafluoroethylene (PTFE membranes were attached to half of the gear devices to minimize tissue ingrowth through these ports. Test devices were sutured onto rabbit eyes for 10 weeks. Tissue-device interactions were evaluated histologically and mechanically after removal to determine effects on device function and changes in surrounding tissue. Test devices were generally well-tolerated during residence in the animal. All devices encouraged fibrous tissue formation between the sclera and the device, fibrous tissue encapsulation and invasion around the device, and inflammation of the conjunctiva. Gear devices encouraged significantly greater inflammation in all cases and a larger rate of tissue ingrowth. PTFE membranes prevented tissue invasion through the covered drug ports, though tissue migrated in through other smaller openings. The torque required to turn the mechanical elements increased over 1000 times for gear devices, but only on the order of 100 times for membrane-covered gear devices and less than 100 times for ball bearing devices. Maintaining a lower device profile, minimizing microscale motion on the eye surface and covering drug ports with a porous membrane may minimize inflammation, decreasing the risk of damage to surrounding tissues and minimizing disruption of device operation.

EPRI research on soil-structure interaction

International Nuclear Information System (INIS)

Tang, H.T.

1986-01-01

The paper briefly discusses the background of soil-structure interaction research and identifies the nuclear industry's need for a realistic, experimentally qualified soil-structure interaction analysis methodology for nuclear power plant design to reduce excessive conservatism and stabilize the licensing process. EPRI research and joint research efforts between EPRI and Niagara Mohawk Power Corporation, Taiwan Power Company, and the Japanese Century Research Institute for Electric Power Industry are outlined. As a result of these and other research efforts, improvement in soil-structure interactions methodologies is being realized

A Review on the 3D Printing of Functional Structures for Medical Phantoms and Regenerated Tissue and Organ Applications

Directory of Open Access Journals (Sweden)

Kan Wang

2017-10-01

Full Text Available Medical models, or “phantoms,” have been widely used for medical training and for doctor-patient interactions. They are increasingly used for surgical planning, medical computational models, algorithm verification and validation, and medical devices development. Such new applications demand high-fidelity, patient-specific, tissue-mimicking medical phantoms that can not only closely emulate the geometric structures of human organs, but also possess the properties and functions of the organ structure. With the rapid advancement of three-dimensional (3D printing and 3D bioprinting technologies, many researchers have explored the use of these additive manufacturing techniques to fabricate functional medical phantoms for various applications. This paper reviews the applications of these 3D printing and 3D bioprinting technologies for the fabrication of functional medical phantoms and bio-structures. This review specifically discusses the state of the art along with new developments and trends in 3D printed functional medical phantoms (i.e., tissue-mimicking medical phantoms, radiologically relevant medical phantoms, and physiological medical phantoms and 3D bio-printed structures (i.e., hybrid scaffolding materials, convertible scaffolds, and integrated sensors for regenerated tissues and organs.

Multiscale mechanics of hierarchical structure/property relationships in calcified tissues and tissue/material interfaces

International Nuclear Information System (INIS)

Katz, J. Lawrence; Misra, Anil; Spencer, Paulette; Wang, Yong; Bumrerraj, Sauwanan; Nomura, Tsutomu; Eppell, Steven J.; Tabib-Azar, Massood

2007-01-01

This paper presents a review plus new data that describes the role hierarchical nanostructural properties play in developing an understanding of the effect of scale on the material properties (chemical, elastic and electrical) of calcified tissues as well as the interfaces that form between such tissues and biomaterials. Both nanostructural and microstructural properties will be considered starting with the size and shape of the apatitic mineralites in both young and mature bovine bone. Microstructural properties for human dentin and cortical and trabecular bone will be considered. These separate sets of data will be combined mathematically to advance the effects of scale on the modeling of these tissues and the tissue/biomaterial interfaces as hierarchical material/structural composites. Interfacial structure and properties to be considered in greatest detail will be that of the dentin/adhesive (d/a) interface, which presents a clear example of examining all three material properties, (chemical, elastic and electrical). In this case, finite element modeling (FEA) was based on the actual measured values of the structure and elastic properties of the materials comprising the d/a interface; this combination provides insight into factors and mechanisms that contribute to premature failure of dental composite fillings. At present, there are more elastic property data obtained by microstructural measurements, especially high frequency ultrasonic wave propagation (UWP) and scanning acoustic microscopy (SAM) techniques. However, atomic force microscopy (AFM) and nanoindentation (NI) of cortical and trabecular bone and the dentin-enamel junction (DEJ) among others have become available allowing correlation of the nanostructural level measurements with those made on the microstructural level

Cell-biomaterial mechanical interaction in the framework of tissue engineering: insights, computational modeling and perspectives.

Science.gov (United States)

Sanz-Herrera, Jose A; Reina-Romo, Esther

2011-01-01

Tissue engineering is an emerging field of research which combines the use of cell-seeded biomaterials both in vitro and/or in vivo with the aim of promoting new tissue formation or regeneration. In this context, how cells colonize and interact with the biomaterial is critical in order to get a functional tissue engineering product. Cell-biomaterial interaction is referred to here as the phenomenon involved in adherent cells attachment to the biomaterial surface, and their related cell functions such as growth, differentiation, migration or apoptosis. This process is inherently complex in nature involving many physico-chemical events which take place at different scales ranging from molecular to cell body (organelle) levels. Moreover, it has been demonstrated that the mechanical environment at the cell-biomaterial location may play an important role in the subsequent cell function, which remains to be elucidated. In this paper, the state-of-the-art research in the physics and mechanics of cell-biomaterial interaction is reviewed with an emphasis on focal adhesions. The paper is focused on the different models developed at different scales available to simulate certain features of cell-biomaterial interaction. A proper understanding of cell-biomaterial interaction, as well as the development of predictive models in this sense, may add some light in tissue engineering and regenerative medicine fields.

High-speed photography of plasma during excimer laser-tissue interaction

International Nuclear Information System (INIS)

Murray, Andrea K; Dickinson, Mark R

2004-01-01

During high fluence laser-tissue interaction, ablation of tissue occurs, debris is removed from the ablation site and is then ejected at high velocity. This debris may be observed as a combination of luminous plasma and non-luminous plume, both of which have the potential to shield the ablation site. This study examined the role of ablation debris in shielding the tissue and determined its effects on the ablation rate over a range of laser pulse energies, pulse repetition rates and pulse numbers for dentine; the velocity differences between hard and soft tissues were also examined. High-speed photography was carried out at up to 1 x 10 8 frames per second. A maximum velocity of 2.58 ± 0.52 x 10 4 m s -1 was recorded for dentine debris within the first 10 ns following ejection. The maximum duration of tissue shielding due to a single pulse, determined by attenuation of a probe beam, was found to be ∼7 ms, ∼80 μs of which was due to luminous plasma and the remainder due to the non-luminous plume

Macrophage migration inhibitory factor is involved in ectopic endometrial tissue growth and peritoneal-endometrial tissue interaction in vivo: a plausible link to endometriosis development.

Directory of Open Access Journals (Sweden)

Halima Rakhila

Full Text Available Pelvic inflammation is a hallmark of endometriosis pathogenesis and a major cause of the disease's symptoms. Abnormal immune and inflammatory changes may not only contribute to endometriosis-major symptoms, but also contribute to ectopic endometrial tissue growth and endometriosis development. A major pro-inflammatory factors found elevated in peritoneal fluid of women with endometriosis and to be overexpressed in peritoneal fluid macrophages and active, highly vascularized and early stage endometriotic lesions, macrophage migration inhibitory factor (MIF appeared to induce angiogenic and inflammatory and estrogen producing phenotypes in endometriotic cells in vitro and to be a possible therapeutic target in vivo. Using a mouse model where MIF-knock out (KO mice received intra-peritoneal injection of endometrial tissue from MIF-KO or syngeneic wild type (WT mice and vice versa, our current study revealed that MIF genetic depletion resulted in a marked reduction ectopic endometrial tissue growth, a disrupted tissue structure and a significant down regulation of the expression of major inflammatory (cyclooxygenease-2, cell adhesion (αv and β3 integrins, survival (B-cell lymphoma-2 and angiogenic (vascular endothelial cell growth factors relevant to endometriosis pathogenesis, whereas MIF add-back to MIF-KO mice significantly restored endometriosis-like lesions number and size. Interestingly, cross-experiments revealed that MIF presence in both endometrial and peritoneal host tissues is required for ectopic endometrial tissue growth and pointed to its involvement in endometrial-peritoneal interactions. This study provides compelling evidence for the role of MIF in endometriosis development and its possible interest for a targeted treatment of endometriosis.

Macrophage migration inhibitory factor is involved in ectopic endometrial tissue growth and peritoneal-endometrial tissue interaction in vivo: a plausible link to endometriosis development.

Science.gov (United States)

Rakhila, Halima; Girard, Karine; Leboeuf, Mathieu; Lemyre, Madeleine; Akoum, Ali

2014-01-01

Pelvic inflammation is a hallmark of endometriosis pathogenesis and a major cause of the disease's symptoms. Abnormal immune and inflammatory changes may not only contribute to endometriosis-major symptoms, but also contribute to ectopic endometrial tissue growth and endometriosis development. A major pro-inflammatory factors found elevated in peritoneal fluid of women with endometriosis and to be overexpressed in peritoneal fluid macrophages and active, highly vascularized and early stage endometriotic lesions, macrophage migration inhibitory factor (MIF) appeared to induce angiogenic and inflammatory and estrogen producing phenotypes in endometriotic cells in vitro and to be a possible therapeutic target in vivo. Using a mouse model where MIF-knock out (KO) mice received intra-peritoneal injection of endometrial tissue from MIF-KO or syngeneic wild type (WT) mice and vice versa, our current study revealed that MIF genetic depletion resulted in a marked reduction ectopic endometrial tissue growth, a disrupted tissue structure and a significant down regulation of the expression of major inflammatory (cyclooxygenease-2), cell adhesion (αv and β3 integrins), survival (B-cell lymphoma-2) and angiogenic (vascular endothelial cell growth) factors relevant to endometriosis pathogenesis, whereas MIF add-back to MIF-KO mice significantly restored endometriosis-like lesions number and size. Interestingly, cross-experiments revealed that MIF presence in both endometrial and peritoneal host tissues is required for ectopic endometrial tissue growth and pointed to its involvement in endometrial-peritoneal interactions. This study provides compelling evidence for the role of MIF in endometriosis development and its possible interest for a targeted treatment of endometriosis.

Wnt/Yes-Associated Protein Interactions During Neural Tissue Patterning of Human Induced Pluripotent Stem Cells.

Science.gov (United States)

Bejoy, Julie; Song, Liqing; Zhou, Yi; Li, Yan

2018-04-01

Human induced pluripotent stem cells (hiPSCs) have special ability to self-assemble into neural spheroids or mini-brain-like structures. During the self-assembly process, Wnt signaling plays an important role in regional patterning and establishing positional identity of hiPSC-derived neural progenitors. Recently, the role of Wnt signaling in regulating Yes-associated protein (YAP) expression (nuclear or cytoplasmic), the pivotal regulator during organ growth and tissue generation, has attracted increasing interests. However, the interactions between Wnt and YAP expression for neural lineage commitment of hiPSCs remain poorly explored. The objective of this study is to investigate the effects of Wnt signaling and YAP expression on the cellular population in three-dimensional (3D) neural spheroids derived from hiPSCs. In this study, Wnt signaling was activated using CHIR99021 for 3D neural spheroids derived from human iPSK3 cells through embryoid body formation. Our results indicate that Wnt activation induces nuclear localization of YAP and upregulates the expression of HOXB4, the marker for hindbrain/spinal cord. By contrast, the cells exhibit more rostral forebrain neural identity (expression of TBR1) without Wnt activation. Cytochalasin D was then used to induce cytoplasmic YAP and the results showed the decreased HOXB4 expression. In addition, the incorporation of microparticles in the neural spheroids was investigated for the perturbation of neural patterning. This study may indicate the bidirectional interactions of Wnt signaling and YAP expression during neural tissue patterning, which have the significance in neurological disease modeling, drug screening, and neural tissue regeneration.

Calculation of the kinetics of heating and structural changes in the cartilaginous tissue under the action of laser radiation

International Nuclear Information System (INIS)

Sobol', E N; Kitai, M S

1998-01-01

A theoretical model is developed for the calculation of the temperature fields and determination of the size of a zone with structural changes in the cartilaginous tissue. The model is based on a simultaneous analysis of the heat and mass transfer processes and it takes into account the bulk absorption of laser radiation by the tissue, surface evaporation of water, and temperature dependences of the diffusion coefficients. It is assumed that under the influence of a phase transition between free and bound water, caused by heating of the cartilage to 70 0 C, the proteoglycans of the cartilage matrix become mobile and, as a result of such mass transfer, structural changes are induced in the cartilaginous tissue causing relaxation of stresses or denaturation. It is shown that the maximum temperature is then reached not on the irradiated surface but at some distance from it, and that the size of the zones of structural changes (denaturation depth) depends strongly on the energy density of the laser radiation and its wavelength, on the duration of the irradiation, and on the cartilage thickness. This model makes it possible to calculate the temperature fields and the depth of structural changes in laser-induced relaxation of stresses and changes in the shape of the cartilaginous tissue. (interaction of laser radiation with matter)

INTERACTION OF LASER RADIATION WITH MATTER: Calculation of the kinetics of heating and structural changes in the cartilaginous tissue under the action of laser radiation

Science.gov (United States)

Sobol', E. N.; Kitai, M. S.

1998-07-01

A theoretical model is developed for the calculation of the temperature fields and determination of the size of a zone with structural changes in the cartilaginous tissue. The model is based on a simultaneous analysis of the heat and mass transfer processes and it takes into account the bulk absorption of laser radiation by the tissue, surface evaporation of water, and temperature dependences of the diffusion coefficients. It is assumed that under the influence of a phase transition between free and bound water, caused by heating of the cartilage to 70°C, the proteoglycans of the cartilage matrix become mobile and, as a result of such mass transfer, structural changes are induced in the cartilaginous tissue causing relaxation of stresses or denaturation. It is shown that the maximum temperature is then reached not on the irradiated surface but at some distance from it, and that the size of the zones of structural changes (denaturation depth) depends strongly on the energy density of the laser radiation and its wavelength, on the duration of the irradiation, and on the cartilage thickness. This model makes it possible to calculate the temperature fields and the depth of structural changes in laser-induced relaxation of stresses and changes in the shape of the cartilaginous tissue.

Analysis of opto-thermal interaction of porcine stomach tissue with 808-nm laser for endoscopic submucosal dissection

Directory of Open Access Journals (Sweden)

Seongjun Kim

2015-11-01

Full Text Available In endoscopic submucosal dissection (ESD, the narrow gastrointestinal space can cause difficulty in surgical interventions. Tissue ablation apparatuses with high-power CO2 lasers or Nd:YAG lasers have been developed to facilitate endoscopic surgical procedures. We studied the interaction of 808-nm laser light with a porcine stomach tissue, with the aim of developing a therapeutic medical device that can remove lesions at the gastrointestinal wall by irradiating a near-infrared laser light incorporated in an endoscopic system. The perforation depths at the porcine fillet and the stomach tissues linearly increased in the range of 2–8 mm in proportion to the laser energy density of 63.7–382 kJ/cm2. Despite the distinct structural and compositional difference, the variation of the perforation depth between the stomach and the fillet was not found at 808-nm wavelength in our measurement. We further studied the laser–tissue interaction by changing the concentration of the methyl blue solution used conventionally as a submucosal fluidic cushion (SFC in ESD procedures. The temperature of the mucosal layer increased more rapidly at higher concentration of the methyl blue solution, because of enhanced light absorption at the SFC layer. The insertion of the SFC would protect the muscle layer from thermal damage. We confirmed that more effective laser treatment should be enabled by tuning the opto-thermal properties of the SFC. This study can contribute to the optimization of the driving parameters for laser incision techniques as an alternative to conventional surgical interventions.

Non-linear soil-structure interaction

International Nuclear Information System (INIS)

Wolf, J.P.

1984-01-01

The basic equation of motion to analyse the interaction of a non-linear structure and an irregular soil with the linear unbounded soil is formulated in the time domain. The contribution of the unbounded soil involves convolution integrals of the dynamic-stiffness coefficients in the time domain and the corresponding motions. As another possibility, a flexibility formulation fot the contribution of the unbounded soil using the dynamic-flexibility coefficients in the time domain, together with the direct-stiffness method for the structure and the irregular soil can be applied. As an example of a non-linear soil-structure-interaction analysis, the partial uplift of the basemat of a structure is examined. (Author) [pt

Functional Attachment of Soft Tissues to Bone: Development, Healing, and Tissue Engineering

Science.gov (United States)

Lu, Helen H.; Thomopoulos, Stavros

2014-01-01

Connective tissues such as tendons or ligaments attach to bone across a multitissue interface with spatial gradients in composition, structure, and mechanical properties. These gradients minimize stress concentrations and mediate load transfer between the soft and hard tissues. Given the high incidence of tendon and ligament injuries and the lack of integrative solutions for their repair, interface regeneration remains a significant clinical challenge. This review begins with a description of the developmental processes and the resultant structure-function relationships that translate into the functional grading necessary for stress transfer between soft tissue and bone. It then discusses the interface healing response, with a focus on the influence of mechanical loading and the role of cell-cell interactions. The review continues with a description of current efforts in interface tissue engineering, highlighting key strategies for the regeneration of the soft tissue–to-bone interface, and concludes with a summary of challenges and future directions. PMID:23642244

Structural requirements of research tissue banks derived from standardized project surveillance.

Science.gov (United States)

Herpel, E; Koleganova, N; Schreiber, B; Walter, B; Kalle, C V; Schirmacher, P

2012-07-01

Tissue banks constitute decisive and rate-limiting resource and technology platforms for basic and translational biomedical research, notably in the area of cancer. Thus, it is essential to plan and structure tissue banking and allocate resources according to research needs, but essential requirements are still incompletely defined. The tissue bank of the National Center of Tumor Diseases Heidelberg (NCT) was founded with the intention to provide tissues of optimal quality and to prioritize the realization of research projects. We analysed its structure and prospective project management registration as well as tracking records for all projects of the NCT tissue bank as of its start in 2005 in order to obtain information that may be relevant for tissue bank planning. All project proposals submitted to the NCT tissue bank (n = 681) were included in the study. For a detailed evaluation of provided services, only projects that were completed until July 2011 (n = 605) were analysed. For these 605 projects, NCT tissue bank provided 769 specific services. In all projects/services, we recorded project leader, type and amount of material provided, type of research (basic/translational), work load of project and project completion. Furthermore, all completed projects were tracked after 90 days according to a standard protocol to determine principal investigators' (PI) satisfaction and quality of the provided material. Until July 2011, 605 projects had been successfully completed as documented by material transfer agreement. Of the projects, 72.7 % addressed basic research, 22.3 % were translational research projects and 3 % concerned epidemiological research; 91 % (n = 546) concerned a single PI and the NTC tissue bank. For these projects, 769 specific services were provided. Of these services, 288 concerned providing formalin-fixed and paraffin-embedded (FFPE) tissue (extracts, full size sections), 126 providing fresh frozen materials (including fresh frozen

Reconfigurable microfluidic hanging drop network for multi-tissue interaction and analysis.

Science.gov (United States)

Frey, Olivier; Misun, Patrick M; Fluri, David A; Hengstler, Jan G; Hierlemann, Andreas

2014-06-30

Integration of multiple three-dimensional microtissues into microfluidic networks enables new insights in how different organs or tissues of an organism interact. Here, we present a platform that extends the hanging-drop technology, used for multi-cellular spheroid formation, to multifunctional complex microfluidic networks. Engineered as completely open, 'hanging' microfluidic system at the bottom of a substrate, the platform features high flexibility in microtissue arrangements and interconnections, while fabrication is simple and operation robust. Multiple spheroids of different cell types are formed in parallel on the same platform; the different tissues are then connected in physiological order for multi-tissue experiments through reconfiguration of the fluidic network. Liquid flow is precisely controlled through the hanging drops, which enable nutrient supply, substance dosage and inter-organ metabolic communication. The possibility to perform parallelized microtissue formation on the same chip that is subsequently used for complex multi-tissue experiments renders the developed platform a promising technology for 'body-on-a-chip'-related research.

Three-dimensional structure of brain tissue at submicrometer resolution

Energy Technology Data Exchange (ETDEWEB)

Saiga, Rino; Mizutani, Ryuta, E-mail: ryuta@tokai-u.jp [Department of Applied Biochemistry, Tokai University, Hiratsuka, Kanagawa 259-1292 (Japan); Inomoto, Chie; Takekoshi, Susumu; Nakamura, Naoya; Tsuboi, Akio; Osawa, Motoki [Tokai University School of Medicine, Isehara, Kanagawa 259-1193 (Japan); Arai, Makoto; Oshima, Kenichi; Itokawa, Masanari [Tokyo Metropolitan Institute of Medical Science, Setagaya, Tokyo 156-8506 (Japan); Uesugi, Kentaro; Takeuchi, Akihisa; Terada, Yasuko; Suzuki, Yoshio [Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), Sayo, Hyogo 679-5198 (Japan)

2016-01-28

Biological objects are composed of submicrometer structures such as cells and organelles that are essential for their functions. Here, we report on three-dimensional X-ray visualization of cells and organelles at resolutions up to 100 nm by imaging microtomography (micro-CT) equipped with Fresnel zone plate optics. Human cerebral tissue, fruit fly cephalic ganglia, and Escherichia coli bacteria labeled with high atomic-number elements were embedded in epoxy resin and subjected to X-ray microtomography at the BL37XU and BL47XU beamlines of the SPring-8 synchrotron radiation facility. The obtained results indicated that soft tissue structures can be visualized with the imaging microtomography.

Mechanics of needle-tissue interaction

NARCIS (Netherlands)

Roesthuis, Roy; van Veen, Youri; Jahya, Alex; Misra, Sarthak

2011-01-01

When a needle is inserted into soft tissue, interac- tion forces are developed at the needle tip and along the needle shaft. The needle tip force is due to cutting of the tissue, and the force along the needle shaft is due to friction between needle and tissue. In this study, the friction force is

Hybrid modelling of soil-structure interaction for embedded structures

International Nuclear Information System (INIS)

Gupta, S.; Penzien, J.

1981-01-01

The basic methods currently being used for the analysis of soil-structure interaction fail to properly model three-dimensional embedded structures with flexible foundations. A hybrid model for the analysis of soil-structure interaction is developed in this investigation which takes advantage of the desirable features of both the finite element and substructure methods and which minimizes their undesirable features. The hybrid model is obtained by partitioning the total soil-structure system into a nearfield and a far-field with a smooth hemispherical interface. The near-field consists of the structure and a finite region of soil immediately surrounding its base. The entire near-field may be modelled in three-dimensional form using the finite element method; thus, taking advantage of its ability to model irregular geometries, and the non-linear soil behavior in the immediate vicinity of the structure. (orig./WL)

Cation-π interactions in structural biology

OpenAIRE

Gallivan, Justin P.; Dougherty, Dennis A.

1999-01-01

Cation-pi interactions in protein structures are identified and evaluated by using an energy-based criterion for selecting significant sidechain pairs. Cation-pi interactions are found to be common among structures in the Protein Data Bank, and it is clearly demonstrated that, when a cationic sidechain (Lys or Arg) is near an aromatic sidechain (Phe, Tyr, or Trp), the geometry is biased toward one that would experience a favorable cation-pi interaction. The sidechain of Arg is more likely tha...

Extracellular matrix hydrogels from decellularized tissues: Structure and function.

Science.gov (United States)

Saldin, Lindsey T; Cramer, Madeline C; Velankar, Sachin S; White, Lisa J; Badylak, Stephen F

2017-02-01

Extracellular matrix (ECM) bioscaffolds prepared from decellularized tissues have been used to facilitate constructive and functional tissue remodeling in a variety of clinical applications. The discovery that these ECM materials could be solubilized and subsequently manipulated to form hydrogels expanded their potential in vitro and in vivo utility; i.e. as culture substrates comparable to collagen or Matrigel, and as injectable materials that fill irregularly-shaped defects. The mechanisms by which ECM hydrogels direct cell behavior and influence remodeling outcomes are only partially understood, but likely include structural and biological signals retained from the native source tissue. The present review describes the utility, formation, and physical and biological characterization of ECM hydrogels. Two examples of clinical application are presented to demonstrate in vivo utility of ECM hydrogels in different organ systems. Finally, new research directions and clinical translation of ECM hydrogels are discussed. More than 70 papers have been published on extracellular matrix (ECM) hydrogels created from source tissue in almost every organ system. The present manuscript represents a review of ECM hydrogels and attempts to identify structure-function relationships that influence the tissue remodeling outcomes and gaps in the understanding thereof. There is a Phase 1 clinical trial now in progress for an ECM hydrogel. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Numerical tool development of fluid-structure interactions for investigation of obstructive sleep apnea

Science.gov (United States)

Huang, Chien-Jung; White, Susan; Huang, Shao-Ching; Mallya, Sanjay; Eldredge, Jeff

2016-11-01

Obstructive sleep apnea (OSA) is a medical condition characterized by repetitive partial or complete occlusion of the airway during sleep. The soft tissues in the upper airway of OSA patients are prone to collapse under the low pressure loads incurred during breathing. The ultimate goal of this research is the development of a versatile numerical tool for simulation of air-tissue interactions in the patient specific upper airway geometry. This tool is expected to capture several phenomena, including flow-induced vibration (snoring) and large deformations during airway collapse of the complex airway geometry in respiratory flow conditions. Here, we present our ongoing progress toward this goal. To avoid mesh regeneration, for flow model, a sharp-interface embedded boundary method is used on Cartesian grids for resolving the fluid-structure interface, while for the structural model, a cut-cell finite element method is used. Also, to properly resolve large displacements, non-linear elasticity model is used. The fluid and structure solvers are connected with the strongly coupled iterative algorithm. The parallel computation is achieved with the numerical library PETSc. Some two- and three- dimensional preliminary results are shown to demonstrate the ability of this tool.

Soil-structure interaction including nonlinear soil

OpenAIRE

Gicev, Vlado

2008-01-01

There are two types of models of soil-structure system depending upon the rigidity of foundation: models with rigid and models with flexible foundation. Main features of the soil-structure interaction phenomenon: -wave scattering, -radiation damping, -reduction of the system frequencies. In this presentation, the influence of interaction on the development of nonlinear zones in the soil is studied.

Spiral-structured, nanofibrous, 3D scaffolds for bone tissue engineering.

Science.gov (United States)

Wang, Junping; Valmikinathan, Chandra M; Liu, Wei; Laurencin, Cato T; Yu, Xiaojun

2010-05-01

Polymeric nanofiber matrices have already been widely used in tissue engineering. However, the fabrication of nanofibers into complex three-dimensional (3D) structures is restricted due to current manufacturing techniques. To overcome this limitation, we have incorporated nanofibers onto spiral-structured 3D scaffolds made of poly (epsilon-caprolactone) (PCL). The spiral structure with open geometries, large surface areas, and porosity will be helpful for improving nutrient transport and cell penetration into the scaffolds, which are otherwise limited in conventional tissue-engineered scaffolds for large bone defects repair. To investigate the effect of structure and fiber coating on the performance of the scaffolds, three groups of scaffolds including cylindrical PCL scaffolds, spiral PCL scaffolds (without fiber coating), and spiral-structured fibrous PCL scaffolds (with fiber coating) have been prepared. The morphology, porosity, and mechanical properties of the scaffolds have been characterized. Furthermore, human osteoblast cells are seeded on these scaffolds, and the cell attachment, proliferation, differentiation, and mineralized matrix deposition on the scaffolds are evaluated. The results indicated that the spiral scaffolds possess porosities within the range of human trabecular bone and an appropriate pore structure for cell growth, and significantly lower compressive modulus and strength than cylindrical scaffolds. When compared with the cylindrical scaffolds, the spiral-structured scaffolds demonstrated enhanced cell proliferation, differentiation, and mineralization and allowed better cellular growth and penetration. The incorporation of nanofibers onto spiral scaffolds further enhanced cell attachment, proliferation, and differentiation. These studies suggest that spiral-structured nanofibrous scaffolds may serve as promising alternatives for bone tissue engineering applications. Copyright 2009 Wiley Periodicals, Inc.

Fundamental trends in fluid-structure interaction

CERN Document Server

Galdi, Giovanni P

2010-01-01

The interaction of a fluid with a solid body is a widespread phenomenon in nature, occurring at different scales and different applied disciplines. Interestingly enough, even though the mathematical theory of the motion of bodies in a liquid is one of the oldest and most classical problems in fluid mechanics, mathematicians have, only very recently, become interested in a systematic study of the basic problems related to fluid-structure interaction, from both analytical and numerical viewpoints. ""Fundamental Trends in Fluid-Structure Interaction"" is a unique collection of important papers wr

Artificial neural net system for interactive tissue classification with MR imaging and image segmentation

International Nuclear Information System (INIS)

Clarke, L.P.; Silbiger, M.; Naylor, C.; Brown, K.

1990-01-01

This paper reports on the development of interactive methods for MR tissue classification that permit mathematically rigorous methods for three-dimensional image segmentation and automatic organ/tumor contouring, as required for surgical and RTP planning. The authors investigate a number of image-intensity based tissue- classification methods that make no implicit assumptions on the MR parameters and hence are not limited by image data set. Similarly, we have trained artificial neural net (ANN) systems for both supervised and unsupervised tissue classification

Nonlinear dynamic analysis of framed structures including soil-structure interaction effects

International Nuclear Information System (INIS)

Mahmood, M.N.; Ahmed, S.Y.

2008-01-01

The role of oil-structure interaction on seismic behavior of reinforced concrete structures is investigated in this paper. A finite element approach has been adopted to model the interaction system that consists of the reinforced concrete plane frame, soil deposit and interface which represents the frictional between foundation of the structure and subsoil. The analysis is based on the elasto-plastic behavior of the frame members (beams and columns) that is defined by the ultimate axial force-bending moment interaction curve, while the cap model is adopted to govern the elasto-plastic behavior of the soil material. Mohr-Coulomb failure law is used to determine the initiation of slippage at the interface, while the separation is assumed to determine the initiation of slippage at the interface, while the separation is assumed to occur when the stresses at the interface becomes tension stresses. New-Mark's Predictor-Corrector algorithm is adopted for nonlinear dynamic analysis. The main aim of present work is to evaluate the sensitivity of structures to different behavior of the soil and interface layer when subjected to an earthquake excitation. Predicted results of the dynamic analysis of the interaction system indicate that the soil-structure interaction problem can have beneficial effects on the structural behavior when different soil models (elastic and elasto-plastic) and interface conditions (perfect bond and permitted slip)are considered. (author)

SSI [soil-structure interactions] and structural benchmarks

International Nuclear Information System (INIS)

Philippacopoulos, A.J.; Miller, C.A.; Costantino, C.J.; Graves, H.

1986-01-01

This paper presents the latest results of the ongoing program entitled, ''Standard Problems for Structural Computer Codes'', currently being worked on at BNL for the USNRC, Office of Nuclear Regulatory Research. During FY 1986, efforts were focussed on three tasks, namely, (1) an investigation of ground water effects on the response of Category I structures, (2) the Soil-Structure Interaction Workshop and (3) studies on structural benchmarks associated with Category I structures. The objective of the studies on ground water effects is to verify the applicability and the limitations of the SSI methods currently used by the industry in performing seismic evaluations of nuclear plants which are located at sites with high water tables. In a previous study by BNL (NUREG/CR-4588), it has been concluded that the pore water can influence significantly the soil-structure interaction process. This result, however, is based on the assumption of fully saturated soil profiles. Consequently, the work was further extended to include cases associated with variable water table depths. In this paper, results related to ''cut-off'' depths beyond which the pore water effects can be ignored in seismic calculations, are addressed. Comprehensive numerical data are given for soil configurations typical to those encountered in nuclear plant sites. These data were generated by using a modified version of the SLAM code which is capable of handling problems related to the dynamic response of saturated soils

"SP-G", a putative new surfactant protein--tissue localization and 3D structure.

Directory of Open Access Journals (Sweden)

Felix Rausch

Full Text Available Surfactant proteins (SP are well known from human lung. These proteins assist the formation of a monolayer of surface-active phospholipids at the liquid-air interface of the alveolar lining, play a major role in lowering the surface tension of interfaces, and have functions in innate and adaptive immune defense. During recent years it became obvious that SPs are also part of other tissues and fluids such as tear fluid, gingiva, saliva, the nasolacrimal system, and kidney. Recently, a putative new surfactant protein (SFTA2 or SP-G was identified, which has no sequence or structural identity to the already know surfactant proteins. In this work, computational chemistry and molecular-biological methods were combined to localize and characterize SP-G. With the help of a protein structure model, specific antibodies were obtained which allowed the detection of SP-G not only on mRNA but also on protein level. The localization of this protein in different human tissues, sequence based prediction tools for posttranslational modifications and molecular dynamic simulations reveal that SP-G has physicochemical properties similar to the already known surfactant proteins B and C. This includes also the possibility of interactions with lipid systems and with that, a potential surface-regulatory feature of SP-G. In conclusion, the results indicate SP-G as a new surfactant protein which represents an until now unknown surfactant protein class.

Replication and interaction of herpes simplex virus and human papillomavirus in differentiating host epithelial tissue

International Nuclear Information System (INIS)

Meyers, Craig; Andreansky, Samita S.; Courtney, Richard J.

2003-01-01

We have investigated the interactions and consequences of superinfecting and coreplication of human papillomavirus (HPV) and herpes simplex virus (HSV) in human epithelial organotypic (raft) culture tissues. In HPV-positive tissues, HSV infection and replication induced significant cytopathic effects (CPE), but the tissues were able to recover and maintain a certain degree of tissue integrity and architecture. HPV31b not only maintained the episomal state of its genomic DNA but also maintained its genomic copy number even during times of extensive HSV-induced CPE. E2 transcripts encoded by HPV31b were undetectable even though HPV31b replication was maintained in HSV- infected raft tissues. Expression of HPV31b oncogenes (E6 and E7) was also repressed but to a lesser degree than was E2 expression. The extent of CPE induced by HSV is dependent on the magnitude of HPV replication and gene expression at the time of HSV infection. During active HSV infection, HPV maintains its genomic copy number even though genes required for its replication were repressed. These studies provide new insight into the complex interaction between two common human sexually transmitted viruses in an in vitro system, modeling their natural host tissue in vivo

Interacting boson model with surface delta interaction between nucleons: Structure and interaction of bosons

International Nuclear Information System (INIS)

Druce, C.H.; Moszkowski, S.A.

1986-01-01

The surface delta interaction is used as an effective nucleon-nucleon interaction to investigate the structure and interaction of the bosons in the interacting boson model. We have obtained analytical expressions for the coefficients of a multipole expansion of the neutron-boson-proton-boson interaction for the case of degenerate orbits. A connection is made between these coefficients and the parameters of the interaction boson model Hamiltonian. A link between the latter parameters and the single boson energies is suggested

Interacting boson model with surface delta interaction between nucleons: Structure and interaction of bosons

Energy Technology Data Exchange (ETDEWEB)

Druce, C.H.; Moszkowski, S.A.

1986-01-01

The surface delta interaction is used as an effective nucleon-nucleon interaction to investigate the structure and interaction of the bosons in the interacting boson model. We have obtained analytical expressions for the coefficients of a multipole expansion of the neutron-boson-proton-boson interaction for the case of degenerate orbits. A connection is made between these coefficients and the parameters of the interaction boson model Hamiltonian. A link between the latter parameters and the single boson energies is suggested.

SOIL STRUCTURE INTERACTION EFFECTS ON MULTISTOREY R/C STRUCTURES

Directory of Open Access Journals (Sweden)

Muberra ESER AYDEMIR

2013-01-01

Full Text Available This paper addresses the behavior of multistorey structures considering soil structure interaction under earthquake excitation. For this purpose, sample 3, 6, 9 storey RC frames are designed based on Turkish Seismic Design Code and analyzed in time domain with incremental dynamic analysis. Strength reduction factors are investigated for generated sample plane frames for 64 different earthquake motions recorded on different site conditions such as rock, stiff soil, soft soil and very soft soil. According to the analysis result, strength reduction factors of sample buildings considering soil structure interaction are found to be almost always smaller than design strength reduction factors given in current seismic design codes, which cause an unsafe design and nonconservative design forces.

PSAIA – Protein Structure and Interaction Analyzer

Directory of Open Access Journals (Sweden)

Vlahoviček Kristian

2008-04-01

Full Text Available Abstract Background PSAIA (Protein Structure and Interaction Analyzer was developed to compute geometric parameters for large sets of protein structures in order to predict and investigate protein-protein interaction sites. Results In addition to most relevant established algorithms, PSAIA offers a new method PIADA (Protein Interaction Atom Distance Algorithm for the determination of residue interaction pairs. We found that PIADA produced more satisfactory results than comparable algorithms implemented in PSAIA. Particular advantages of PSAIA include its capacity to combine different methods to detect the locations and types of interactions between residues and its ability, without any further automation steps, to handle large numbers of protein structures and complexes. Generally, the integration of a variety of methods enables PSAIA to offer easier automation of analysis and greater reliability of results. PSAIA can be used either via a graphical user interface or from the command-line. Results are generated in either tabular or XML format. Conclusion In a straightforward fashion and for large sets of protein structures, PSAIA enables the calculation of protein geometric parameters and the determination of location and type for protein-protein interaction sites. XML formatted output enables easy conversion of results to various formats suitable for statistic analysis. Results from smaller data sets demonstrated the influence of geometry on protein interaction sites. Comprehensive analysis of properties of large data sets lead to new information useful in the prediction of protein-protein interaction sites.

Influence of nuclear interactions in body tissues on tumor dose in carbon-ion radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Inaniwa, T., E-mail: taku@nirs.go.jp; Kanematsu, N. [Medical Physics Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage-ku, Chiba 263-8555 (Japan); Tsuji, H.; Kamada, T. [Hospital, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan)

2015-12-15

Purpose: In carbon-ion radiotherapy treatment planning, the planar integrated dose (PID) measured in water is applied to the patient dose calculation with density scaling using the stopping power ratio. Since body tissues are chemically different from water, this dose calculation can be subject to errors, particularly due to differences in inelastic nuclear interactions. In recent studies, the authors proposed and validated a PID correction method for these errors. In the present study, the authors used this correction method to assess the influence of these nuclear interactions in body tissues on tumor dose in various clinical cases. Methods: Using 10–20 cases each of prostate, head and neck (HN), bone and soft tissue (BS), lung, liver, pancreas, and uterine neoplasms, the authors first used treatment plans for carbon-ion radiotherapy without nuclear interaction correction to derive uncorrected dose distributions. The authors then compared these distributions with recalculated distributions using the nuclear interaction correction (corrected dose distributions). Results: Median (25%/75% quartiles) differences between the target mean uncorrected doses and corrected doses were 0.2% (0.1%/0.2%), 0.0% (0.0%/0.0%), −0.3% (−0.4%/−0.2%), −0.1% (−0.2%/−0.1%), −0.1% (−0.2%/0.0%), −0.4% (−0.5%/−0.1%), and −0.3% (−0.4%/0.0%) for the prostate, HN, BS, lung, liver, pancreas, and uterine cases, respectively. The largest difference of −1.6% in target mean and −2.5% at maximum were observed in a uterine case. Conclusions: For most clinical cases, dose calculation errors due to the water nonequivalence of the tissues in nuclear interactions would be marginal compared to intrinsic uncertainties in treatment planning, patient setup, beam delivery, and clinical response. In some extreme cases, however, these errors can be substantial. Accordingly, this correction method should be routinely applied to treatment planning in clinical practice.

Topology optimization for acoustic-structure interaction problems

DEFF Research Database (Denmark)

Yoon, Gil Ho; Jensen, Jakob Søndergaard; Sigmund, Ole

2006-01-01

We propose a gradient based topology optimization algorithm for acoustic-structure (vibro-acoustic) interaction problems without an explicit interfacing boundary representation. In acoustic-structure interaction problems, the pressure field and the displacement field are governed by the Helmholtz...... to subdomain interfaces evolving during the optimization process. In this paper, we propose to use a mixed finite element formulation with displacements and pressure as primary variables (u/p formulation) which eliminates the need for explicit boundary representation. In order to describe the Helmholtz......-dimensional acoustic-structure interaction problems are optimized to show the validity of the proposed method....

Vitamin A, endocrine tissues and hormones: interplay and interactions

Directory of Open Access Journals (Sweden)

J Brossaud

2017-09-01

Full Text Available Vitamin A (retinol is a micronutrient critical for cell proliferation and differentiation. In adults, vitamin A and metabolites such as retinoic acid (RA play major roles in vision, immune and brain functions and tissue remodelling and metabolism. This review presents the physiological interactions of retinoids and endocrine tissues and hormonal systems. Two endocrine systems have been particularly studied. In the pituitary, retinoids target the corticotrophs with a possible therapeutic use in corticotropinomas. In the thyroid, retinoids interfere with iodine metabolism and vitamin A deficiency aggravates thyroid dysfunction caused by iodine-deficient diets. Retinoids use in thyroid cancer appears less promising than expected. Recent and still controversial studies investigated the relations between retinoids and metabolic syndrome. Indeed, retinoids contribute to pancreatic development and modify fat and glucose metabolism. However, more detailed studies are needed before planning any therapeutic use. Finally, retinoids probably play more minor roles in adrenal and gonads development and function apart from their major effects on spermatogenesis.

Structure of local interactions in complex financial dynamics.

Science.gov (United States)

Jiang, X F; Chen, T T; Zheng, B

2014-06-17

With the network methods and random matrix theory, we investigate the interaction structure of communities in financial markets. In particular, based on the random matrix decomposition, we clarify that the local interactions between the business sectors (subsectors) are mainly contained in the sector mode. In the sector mode, the average correlation inside the sectors is positive, while that between the sectors is negative. Further, we explore the time evolution of the interaction structure of the business sectors, and observe that the local interaction structure changes dramatically during a financial bubble or crisis.

Structural study of surfactant-dependent interaction with protein

Energy Technology Data Exchange (ETDEWEB)

Mehan, Sumit; Aswal, Vinod K., E-mail: vkaswal@barc.gov.in [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Kohlbrecher, Joachim [Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 PSI Villigen (Switzerland)

2015-06-24

Small-angle neutron scattering (SANS) has been used to study the complex structure of anionic BSA protein with three different (cationic DTAB, anionic SDS and non-ionic C12E10) surfactants. These systems form very different surfactant-dependent complexes. We show that the structure of protein-surfactant complex is initiated by the site-specific electrostatic interaction between the components, followed by the hydrophobic interaction at high surfactant concentrations. It is also found that hydrophobic interaction is preferred over the electrostatic interaction in deciding the resultant structure of protein-surfactant complexes.

An impedance function approach for soil-structure interaction analyses including structure-to-structure interaction effects

International Nuclear Information System (INIS)

Gantayat, A.; Kamil, H.

1981-01-01

The dynamic soil-structure and structure-to-structure interaction effects may be determined in one of the two ways: by modeling the entire soil-structure system by a finite-element model, or by using a frequency-dependent (or frequency-independent) impedance function approach. In seismic design of nuclear power plant structures, the normal practice is to use the first approach because of its simplicity and easy availability of computer codes to perform such analyses. However, in the finite-element approach, because of the size and cost restrictions, the three-dimensional behavior of the entire soil-structure system and the radiation damping in soil are only approximately included by using a two-dimensional finite-element mesh. In using the impedance function approach, the soil-structure analyses can be performed in four steps: (a) determination of the dynamic properties of the fixed base superstructure, (b) determination of foundation and structure impedance matrices and input motions, (c) evaluation of foundation motion, (d) analysis of the fixed base superstructure using computed foundation motion. (orig./RW)

Neutron interactions with biological tissue. Final report

International Nuclear Information System (INIS)

1998-01-01

This program was aimed at creating a quantitative physical description, at the micrometer and nanometer levels, of the physical interactions of neutrons with tissue through the ejected secondary charged particles. The authors used theoretical calculations whose input includes neutron cross section data; range, stopping power, ion yield, and straggling information; and geometrical properties. Outputs are initial and slowing-down spectra of charged particles, kerma factors, average values of quality factors, microdosimetric spectra, and integral microdosimetric parameters such as bar y F , bar y D , y * . Since it has become apparent that nanometer site sizes are also relevant to radiobiological effects, the calculations of event size spectra and their parameters were extended to these smaller diameters. This information is basic to radiological physics, radiation biology, radiation protection of workers, and standards for neutron dose measurement

Structure soil structure interaction effects: Seismic analysis of safety related collocated concrete structures

International Nuclear Information System (INIS)

Joshi, J.R.

2000-01-01

The Process, Purification and Stack Buildings are collocated safety related concrete shear wall structures with plan dimensions in excess of 100 feet. An important aspect of their seismic analysis was the determination of structure soil structure interaction (SSSI) effects, if any. The SSSI analysis of the Process Building, with one other building at a time, was performed with the SASSI computer code for up to 50 frequencies. Each combined model had about 1500 interaction nodes. Results of the SSSI analysis were compared with those from soil structure interaction (SSI) analysis of the individual buildings, done with ABAQUS and SASSI codes, for three parameters: peak accelerations, seismic forces and the in-structure floor response spectra (FRS). The results may be of wider interest due to the model size and the potential applicability to other deep soil layered sites. Results obtained from the ABAQUS analysis were consistently higher, as expected, than those from the SSI and SSSI analyses using the SASSI. The SSSI effect between the Process and Purification Buildings was not significant. The Process and Stack Building results demonstrated that under certain conditions a massive structure can have an observable effect on the seismic response of a smaller and less stiff structure

Cell and Tissue Engineering

CERN Document Server

2012-01-01

“Cell and Tissue Engineering” introduces the principles and new approaches in cell and tissue engineering. It includes both the fundamentals and the current trends in cell and tissue engineering, in a way useful both to a novice and an expert in the field. The book is composed of 13 chapters all of which are written by the leading experts. It is organized to gradually assemble an insight in cell and tissue function starting form a molecular nano-level, extending to a cellular micro-level and finishing at the tissue macro-level. In specific, biological, physiological, biophysical, biochemical, medical, and engineering aspects are covered from the standpoint of the development of functional substitutes of biological tissues for potential clinical use. Topics in the area of cell engineering include cell membrane biophysics, structure and function of the cytoskeleton, cell-extracellular matrix interactions, and mechanotransduction. In the area of tissue engineering the focus is on the in vitro cultivation of ...

Dynamic Soil-Structure-Interaction

DEFF Research Database (Denmark)

Kellezi, Lindita

1998-01-01

The aim of this thesis is to investigate and develop alternative methods of analyzing problems in dynamic soil-structure-interaction. The main focus is the major difficulty posed by such an analysis - the phenomenon of waves which radiate outward from the excited structures towards infinity....... In numerical calculations, only a finite region of the foundation metium is analyzed and something is done to prevent the outgoing radiating waves to reflect from the regions's boundary. The prosent work concerns itself with the study of such effects, using the finite element method, and artificial...... transmitting boundary at the edges of the computational mesh. To start with, an investigation of the main effects of the interaction phenomena is carried out employing a widely used model, considering dynamic stiffness of the unbounded soil as frequency independent. Then a complete description...

Computation of wave fields and soil structure interaction

International Nuclear Information System (INIS)

Lysmer, J.W.

1982-01-01

The basic message of the lecture is that the determination of the temporal and spatial variation of the free-field motions is the most important part of any soil-structure interaction analysis. Any interaction motions may be considered as small aberrations superimposed on the free-field motions. The current definition of the soil-structure interaction problem implies that superposition must be used, directly or indirectly, in any rational method of analysis of this problem. This implies that the use of nonlinear procedures in any part of a soil-structure interaction analysis must be questioned. Currently the most important part of the soil-structure interaction analysis, the free-field problem, cannot be solved by nonlinear methods. Hence, it does not seem reasonable to spend a large effort on trying to obtain nonlinear solutions for the interaction part of the problem. Even if such solutions are obtained they cannot legally be superimposed on the free-field motions to obtain the total motions of the structure. This of course does not preclude the possibility that such an illegal procedure may lead to solutions which are close enough for engineering purposes. However, further research is required to make a decision on this issue

Dynamic soil-structure interactions on embedded buildings

International Nuclear Information System (INIS)

Kobarg, J.; Werkle, H.; Henseleit, O.

1983-01-01

The dynamic soil-structure interaction on the horizontal seismic excitation is investigated on two typical embedded auxiliary buildings of a nuclear power plant. The structure and the soil are modelled by various analytical and numerical methods. Under the condition of the linear viscoelastic theory, i.e. soil characteristic constant in time and independent of strain, the interaction influences between a homogenous soil layer and a structure are analysied for the following parameters: 4) mathematical soil modells; 4) mathematical structure modells; 4) shear wave velocities; 3) embedment conditions; 4) earthquake time histories. (orig.) [de

Optimization of mathematical models for soil structure interaction

International Nuclear Information System (INIS)

Vallenas, J.M.; Wong, C.K.; Wong, D.L.

1993-01-01

Accounting for soil-structure interaction in the design and analysis of major structures for DOE facilities can involve significant costs in terms of modeling and computer time. Using computer programs like SASSI for modeling major structures, especially buried structures, requires the use of models with a large number of soil-structure interaction nodes. The computer time requirements (and costs) increase as a function of the number of interaction nodes to the third power. The added computer and labor cost for data manipulation and post-processing can further increase the total cost. This paper provides a methodology to significantly reduce the number of interaction nodes. This is achieved by selectively increasing the thickness of soil layers modeled based on the need for the mathematical model to capture as input only those frequencies that can actually be transmitted by the soil media. The authors have rarely found that a model needs to capture frequencies as high as 33 Hz. Typically coarser meshes (and a lesser number of interaction nodes) are adequate

Dynamic Analysis of Partially Embedded Structures Considering Soil-Structure Interaction in Time Domain

OpenAIRE

Mahmoudpour, Sanaz; Attarnejad, Reza; Behnia, Cambyse

2011-01-01

Analysis and design of structures subjected to arbitrary dynamic loadings especially earthquakes have been studied during past decades. In practice, the effects of soil-structure interaction on the dynamic response of structures are usually neglected. In this study, the effect of soil-structure interaction on the dynamic response of structures has been examined. The substructure method using dynamic stiffness of soil is used to analyze soil-structure system. A coupled model based on finite el...

Interaction of a gibberellin-induced factor with the upstream region of an alpha-amylase gene in rice aleurone tissue.

OpenAIRE

Ou-Lee, T M; Turgeon, R; Wu, R

1988-01-01

The interaction between the DNA sequences of an alpha-amylase (EC 3.2.1.1) gene and a tissue-specific factor induced in rice (Oryza sativa L.) aleurone tissue by gibberellin was studied. DNA mobility-shift during electrophoresis indicated that a 500-base-pair sequence (HS500) of a rice alpha-amylase genomic clone (OSamy-a) specifically interacted with a factor from gibberellin-induced rice aleurone tissue. The amount of complex formed between the HS500 DNA fragment and the gibberellin-induced...

Assessment of soil/structure interaction analysis procedures for nuclear power plant structures

International Nuclear Information System (INIS)

Young, G.A.; Wei, B.C.

1977-01-01

The paper presents an assessment of two state-of-the-art soil/structure interaction analysis procedures that are frequently used to provide seismic analyses of nuclear power plant structures. The advantages of large three-dimensional, elastic, discrete mass models and two-dimensional finite element models are compared. The discrete mass models can provide three-dimensional response capability with economical computer costs but only fair soil/structure interaction representation. The two-dimensional finite element models provide good soil/structure interaction representation, but cannot provide out-of-plane response. Three-dimensional finite element models would provide the most informative and complete analyses. For this model, computer costs would be much greater, but modeling costs would be approximately the same as those required for three-dimensional discrete mass models

Hyperfine structure analysis in magnetic resonance spectroscopy: from astrophysical measurements towards endogenous biosensors in human tissue

International Nuclear Information System (INIS)

Schroeder, L.; California Univ., Berkeley, CA; Lawrence Berkeley National Lab., Berkeley, CA

2007-01-01

The hyperfine interaction of two spins is a well studied effect in atomic systems. Magnetic resonance experiments demonstrate that the detectable dipole transitions are determined by the magnetic moments of the constituents and the external magnetic field. Transferring the corresponding quantum mechanics to molecular bound nuclear spins allows for precise prediction of NMR spectra obtained from metabolites in human tissue. This molecular hyperfine structure has been neglected so far in in vivo NMR spectroscopy but contains useful information, especially when studying molecular dynamics. This contribution represents a review of the concept of applying the Breit-Rabi formalism to coupled nuclear spins and discusses the immobilization of different metabolites in anisotropic tissue revealed by 1H NMR spectra of carnosine, phosphocreatine and taurine. Comparison of atomic and molecular spin systems allows for statements on the biological constraints for direct spin-spin interactions. Moreover, the relevance of hyperfine effects on the line shapes of multiplets of indirectly-coupled spin systems with more than two constituents can be predicted by analyzing quantum mechanical parameters. As an example, the superposition of eigenstates of the AMX system of adenosine 5'-triphosphate and its application for better quantification of 31P-NMR spectra will be discussed. (orig.)

[Hyperfine structure analysis in magnetic resonance spectroscopy: from astrophysical measurements towards endogenous biosensors in human tissue].

Science.gov (United States)

Schröder, Leif

2007-01-01

The hyperfine interaction of two spins is a well studied effect in atomic systems. Magnetic resonance experiments demonstrate that the detectable dipole transitions are determined by the magnetic moments of the constituents and the external magnetic field. Transferring the corresponding quantum mechanics to molecular bound nuclear spins allows for precise prediction of NMR spectra obtained from metabolites in human tissue. This molecular hyperfine structure has been neglected so far in in vivo NMR spectroscopy but contains useful information, especially when studying molecular dynamics. This contribution represents a review of the concept of applying the Breit-Rabi formalism to coupled nuclear spins and discusses the immobilization of different metabolites in anisotropic tissue revealed by 1H NMR spectra of carnosine, phosphocreatine and taurine. Comparison of atomic and molecular spin systems allows for statements on the biological constraints for direct spin-spin interactions. Moreover, the relevance of hyperfine effects on the line shapes of multiplets of indirectly-coupled spin systems with more than two constituents can be predicted by analyzing quantum mechanical parameters. As an example, the superposition of eigenstates of the A MX system of adenosine 5'-triphosphate and its application for better quantification of 31P-NMR spectra will be discussed.

Epithelial-Mesenchymal Interactions in Urinary Bladder and Small Intestine and How to Apply Them in Tissue Engineering.

Science.gov (United States)

Jerman, Urška Dragin; Kreft, Mateja Erdani; Veranič, Peter

2015-12-01

Reciprocal interactions between the epithelium and mesenchyme are essential for the establishment of proper tissue morphology during organogenesis and tissue regeneration as well as for the maintenance of cell differentiation. With this review, we highlight the importance of epithelial-mesenchymal cross talk in healthy tissue and further discuss its significance in engineering functional tissues in vitro. We focus on the urinary bladder and small intestine, organs that are often compromised by disease and are as such in need of research that would advance effective treatment or tissue replacement. To date, the understanding of epithelial-mesenchymal reciprocal interactions has enabled the development of in vitro biomimetic tissue equivalents that have provided many possibilities in treating defective, damaged, or even cancerous tissues. Although research of the past several years has advanced the field of bladder and small intestine tissue engineering, one must be aware of its current limitations in successfully and above all safely introducing tissue-engineered constructs into clinical practice. Special attention is in particular needed when treating cancerous tissues, as initially successful tumor excision and tissue reconstruction may later on result in cancer recurrence due to oncogenic signals originating from an altered stroma. Recent rather poor outcomes in pioneering clinical trials of bladder reconstructions should serve as a reminder that recreating a functional organ to replace a dysfunctional one is an objective far more difficult to reach than initially foreseen. When considering effective tissue engineering approaches for diseased tissues in humans, it is imperative to introduce animal models with dysfunctional or, even more importantly, cancerous organs, which would greatly contribute to predicting possible complications and, hence, reducing risks when translating to the clinic.

Analysis of Pumphouse RCC Frame Structure for Soil Structure Interaction

OpenAIRE

Mr A.S. Thombare; Prof. V.P. Kumbhar; Prof. A.H. Kumbhar

2016-01-01

When structure is built on ground some elements of structure are direct contact with soil. When loads are applied on structure internal forces are developed in both the structure as well as in soil. It results in deformation of both the components which are independent to each other. This are called soil structure interaction. The analysis is done by using (Bentley STAAD.Pro V8i Version 2007) software. The analysis carried out been pump house structure R.C.C. frame structure find ...

Experimental studies on interactions of radiation and cancer chemotherapeutic drugs in normal tissues and a solid tumour

International Nuclear Information System (INIS)

Maase, H. van der

1986-01-01

The interactions of radiation and seven cancer chemotherapeutic drugs have been investigated in four normal tissues and in a solid C 3 H mouse mammary carcinoma in vivo. The investigated drugs were adriamycin (ADM), bleomycin (BLM), cyclophosphamide (CTX), 5-fluorouracil (5-FU), methotrexate (MTX), mitomycin C (MM-C) and cis-diamminedichloroplatinum(II) (cis-DDP). The drugs enhanced the radiation response in most cases. However, signs of radioprotection was observed for CTX in skin and for MTX in haemopoietic tissue. The interval and the sequence of the two treatment modalities were of utmost importance for the normal tissue reactions. In general, the most serious interactions occurred when drugs were administered simultaneously with or a few hours before radiation. The radiation-modifying effect of the drugs deviated from this pattern in the haemopoietic tissue as the radiation response was most enhanced on drug administration 1-3 days after radiation. Enhancement of the radiation response was generally less pronounced in the tumour model than in the normal tissues. The combined drug-radiation effect was apparently less time-dependent in the tumour than in the normal tissues. (Auth.)

Dynamics of translational friction in needle-tissue interaction during needle insertion.

Science.gov (United States)

Asadian, Ali; Patel, Rajni V; Kermani, Mehrdad R

2014-01-01

In this study, a distributed approach to account for dynamic friction during needle insertion in soft tissue is presented. As is well known, friction is a complex nonlinear phenomenon. It appears that classical or static models are unable to capture some of the observations made in systems subjected to significant frictional effects. In needle insertion, translational friction would be a matter of importance when the needle is very flexible, or a stop-and-rotate motion profile at low insertion velocities is implemented, and thus, the system is repeatedly transitioned from a pre-sliding to a sliding mode and vice versa. In order to characterize friction components, a distributed version of the LuGre model in the state-space representation is adopted. This method also facilitates estimating cutting force in an intra-operative manner. To evaluate the performance of the proposed family of friction models, experiments were conducted on homogeneous artificial phantoms and animal tissue. The results illustrate that our approach enables us to represent the main features of friction which is a major force component in needle-tissue interaction during needle-based interventions.

Three-Dimensional Structural Aspects of Protein–Polysaccharide Interactions

Directory of Open Access Journals (Sweden)

Masamichi Nagae

2014-03-01

Full Text Available Linear polysaccharides are typically composed of repeating mono- or disaccharide units and are ubiquitous among living organisms. Polysaccharide diversity arises from chain-length variation, branching, and additional modifications. Structural diversity is associated with various physiological functions, which are often regulated by cognate polysaccharide-binding proteins. Proteins that interact with linear polysaccharides have been identified or developed, such as galectins and polysaccharide-specific antibodies, respectively. Currently, data is accumulating on the three-dimensional structure of polysaccharide-binding proteins. These proteins are classified into two types: exo-type and endo-type. The former group specifically interacts with the terminal units of polysaccharides, whereas the latter with internal units. In this review, we describe the structural aspects of exo-type and endo-type protein-polysaccharide interactions. Further, we discuss the structural basis for affinity and specificity enhancement in the face of inherently weak binding interactions.

Structural stability of interaction networks against negative external fields

Science.gov (United States)

Yoon, S.; Goltsev, A. V.; Mendes, J. F. F.

2018-04-01

We explore structural stability of weighted and unweighted networks of positively interacting agents against a negative external field. We study how the agents support the activity of each other to confront the negative field, which suppresses the activity of agents and can lead to collapse of the whole network. The competition between the interactions and the field shape the structure of stable states of the system. In unweighted networks (uniform interactions) the stable states have the structure of k -cores of the interaction network. The interplay between the topology and the distribution of weights (heterogeneous interactions) impacts strongly the structural stability against a negative field, especially in the case of fat-tailed distributions of weights. We show that apart from critical slowing down there is also a critical change in the system structure that precedes the network collapse. The change can serve as an early warning of the critical transition. To characterize changes of network structure we develop a method based on statistical analysis of the k -core organization and so-called "corona" clusters belonging to the k -cores.

Direct plasma interaction with living tissue

Science.gov (United States)

Fridman, Gregory

For some time, plasma has been used in medicine to cauterize or cut tissue using heat and mechanical energy. In the recent decade, some researchers around the world have started to investigate how gas jets that pass through thermal plasma can be employed in medicine. This thesis presents the first investigation of biomedical uses of non-thermal plasma discharge which comes in direct contact with living tissue. It is demonstrated that the direct application of non-thermal plasma in air can cause rapid deactivation of bacteria on surfaces of tissues without causing any visible tissue damage. Medical need for such a device is discussed. Construction and operation of various types of non-thermal plasma power supplies and many types of treatment electrodes are presented as well. Application of this plasma to living organisms is shown to be safe from both the electrical perspective and from the biological perspective. Biological safety is revealed through a series of differential skin toxicity trials on human cadaver tissue, live hairless mouse skin tissue, live pig skin tissue, and finally in an open wound model on pigs. Direct non-thermal plasma in air is shown to deactivate bacteria about 100 times faster than indirect application using jets. A series of experiments reveal that this effectiveness is due to the ability of direct discharge to bring charges to tissue surfaces. It is demonstrated that neither ultraviolet (UV) radiation nor neutral active species such as hydroxyl radicals or ozone produced in plasma are responsible for the main effect on bacteria. Although much additional work remains on establishing detailed mechanism by which charges from plasma achieve this effect, the work carried out in this thesis clearly demonstrates that direct application of non-thermal plasma in air can be a very useful tool in medicine.

Verification of an interaction model of an ultrasonic oscillatory system with periodontal tissues

Directory of Open Access Journals (Sweden)

V. A. Karpuhin

2014-01-01

Full Text Available Verification of an interaction model of an ultrasonic oscillatory system with biological tissues which was developed in COMSOL Multiphysics was carried out. It was shown that calculation results in COMSOL Multiphysics obtained using the “Finer” grid (the ratio of the grid step to a minimum transversal section area of the model ≤ 0.3 mm-1 best of all qualitatively and quantitatively corresponded to practical results. The average relative error of the obtained results in comparison with the experimental ones did not exceed 4.0%. Influence of geometrical parameters (thickness of load on electrical admittance of the ultrasonic oscillatory system interacting with biological tissues was investigated. It was shown that increase in thickness of load within the range from 0 to 95 mm led to decrease in calculated values of natural resonance frequency of longitudinal fluctuations and electrical admittance from 26,58 to 26,35 kHz and from 0,86 to 0,44 mS.

Cluster structures influenced by interaction with a surface.

Science.gov (United States)

Witt, Christopher; Dieterich, Johannes M; Hartke, Bernd

2018-05-30

Clusters on surfaces are vitally important for nanotechnological applications. Clearly, cluster-surface interactions heavily influence the preferred cluster structures, compared to clusters in vacuum. Nevertheless, systematic explorations and an in-depth understanding of these interactions and how they determine the cluster structures are still lacking. Here we present an extension of our well-established non-deterministic global optimization package OGOLEM from isolated clusters to clusters on surfaces. Applying this approach to intentionally simple Lennard-Jones test systems, we produce a first systematic exploration that relates changes in cluster-surface interactions to resulting changes in adsorbed cluster structures.

How to analyze Structure and Function in Tissue – based Diagnosis?

Directory of Open Access Journals (Sweden)

Klaus Kayser

2016-04-01

Full Text Available Background Tissue – based diagnosis (morphological analysis of human tissue judges, measures and interprets morphologic images which have been acquired from human tissue. It translates the findings into a diagnosis or description of biological functions. What are its principle algorithms and theoretical background? Theory Pathologists are used to distinguish between structure and function. Biological structures are ordered clusters of material (genes, nuclei, cells, organs, etc., which remain constant during the period of detection and observation. They are commonly embedded or appear in circumscribed spaces. These spaces are clearly separated from their environment (background. Functions are forces that act on structures. They modify their appearance, create and delete structures and their spatial relationship. The recognition of both structures and functions is dependent upon the observation time: Material that remains unchanged within the observation period is called structure, its changes between a series of observations a function. Derivatives Biological structures and functions should be interpreted in relation to the observation time. Functions can be considered structural gradients of time or of observation periods. Implementation The analysis of conventional stained histological slides reflects to a short non changeable observation time, which in reality cannot be repeated at different times on the same tissue. Acquired digital images such as virtual slides (VS offer the opportunity of simulating different observation times if object features are analyzed that reflect structural changes at different times. The measurement of immunohistochemal intensity levels performed on the same structure can be considered a time series of the binding or antigen – antibody process. The obtained frame of these measurements can be mapped on chemical significant descriptors such as Shannon’s and structural entropy, and their entropy flows. Material

Automated Detection of Connective Tissue by Tissue Counter Analysis and Classification and Regression Trees

Directory of Open Access Journals (Sweden)

Josef Smolle

2001-01-01

Full Text Available Objective: To evaluate the feasibility of the CART (Classification and Regression Tree procedure for the recognition of microscopic structures in tissue counter analysis. Methods: Digital microscopic images of H&E stained slides of normal human skin and of primary malignant melanoma were overlayed with regularly distributed square measuring masks (elements and grey value, texture and colour features within each mask were recorded. In the learning set, elements were interactively labeled as representing either connective tissue of the reticular dermis, other tissue components or background. Subsequently, CART models were based on these data sets. Results: Implementation of the CART classification rules into the image analysis program showed that in an independent test set 94.1% of elements classified as connective tissue of the reticular dermis were correctly labeled. Automated measurements of the total amount of tissue and of the amount of connective tissue within a slide showed high reproducibility (r=0.97 and r=0.94, respectively; p < 0.001. Conclusions: CART procedure in tissue counter analysis yields simple and reproducible classification rules for tissue elements.

Understanding Protein-Protein Interactions Using Local Structural Features

DEFF Research Database (Denmark)

Planas-Iglesias, Joan; Bonet, Jaume; García-García, Javier

2013-01-01

Protein-protein interactions (PPIs) play a relevant role among the different functions of a cell. Identifying the PPI network of a given organism (interactome) is useful to shed light on the key molecular mechanisms within a biological system. In this work, we show the role of structural features...... interacting and non-interacting protein pairs to classify the structural features that sustain the binding (or non-binding) behavior. Our study indicates that not only the interacting region but also the rest of the protein surface are important for the interaction fate. The interpretation...... to score the likelihood of the interaction between two proteins and to develop a method for the prediction of PPIs. We have tested our method on several sets with unbalanced ratios of interactions and non-interactions to simulate real conditions, obtaining accuracies higher than 25% in the most unfavorable...

Contribution of ultrasound forward scattering to tissue structure study

International Nuclear Information System (INIS)

Edee, M.K.

1987-12-01

In this paper, we show how to get useful information of tissue structure by merely interpreting some experimental graphs such as energy spectral density and autocorrelation function of an ultrasonic beam travelling through tissues. To support these interpretations, we needed just some well-known theorems rather than heavy and complicated mathematical equations, so we measured the dimensions of scatterers within specimens by using the graphical representation of autocorrelation function. We related these measurements to the scattered peaks which appear in energy density spectrum. The values we found were equal to those obtained from biologists within ∼ 15%. (author) 26 refs, 6 figs, tabs

Applications in soil-structure interactions. Final report, June 1979

International Nuclear Information System (INIS)

Jhaveri, D.P.

1979-01-01

Complex phenomenon of soil-structure interaction was assessed. Relationships between the characteristics of the earthquake ground motions, the local soil and geologic conditions, and the response of the structures to the ground motions were studied. (I) The use of the explicit finite-difference method to study linear elastic soil-structure interaction is described. A linear two-dimensional study of different conditions that influence the dynamic compliance and scattering properties of foundations is presented. (II) The FLUSH computer code was used to compute the soil-structure interaction during SIMQUAKE 1B, an experimental underground blast excitation of a 1/12-scale model of a nuclear containment structure. Evaluation was performed using transient excitation, applied to a finite-difference grid. Dynamic foundation properties were studied. Results indicate that the orientation and location of the source relative to the site and the wave environment at the site may be important parameters to be considered. Differences between the computed and experimental recorded responses are indicated, and reasons for the discrepancy are suggested. (III) A case study that examined structural and ground response data tabulated and catalogued from tests at the Nevada Test Site for its applicability to the soil-structure interaction questions of interest is presented. Description, methods, and evaluation of data on soil-structure interaction from forced vibration tests are presented. A two-dimensional finite-difference grid representing a relatively rigid structure resting on uniform ground was analyzed and monitored. Fourier spectra of monitored time histories were also evaluated and are presented. Results show clear evidence of soil-structure interaction and significant agreement with theory. 128 figures, 18 tables

Nonlinear seismic soil-structure interaction analysis of nuclear power plant structures

International Nuclear Information System (INIS)

Khanna, J.K.; Setlur, A.V.; Pathak, D.V.

1977-01-01

The heterogeneous and nonlinear soil medium and the detailed three-dimensional structure are synthesized to determine the seismic response to soil-structure systems. The approach is particularly attractive in a design office environment since it: a) leads to interactive motion at the soil-structure interface; b) uses existing public domain programs such as SAPIV, LUSH and FLUSH with marginal modifications; and c) meets current regulatory requirements for soil-structure interaction analysis. Past methods differ from each other depending on the approach adopted for soil and structure representations and procedures for solving the governing differential equations. Advantages and limitations of these methods are reviewed. In the current approach, the three-dimensional structure is represented by the dynamic characteristics of its fixed base condition. This representation is ideal when structures are designed to be within elastic range. An important criterion is the design of the nuclear power plant structures. Model damping coefficients are varied to reflect the damping properties of different structural component materials. The detailed structural model is systematically reduced to reflect important dynamic behavior with simultaneous storing of intermediate information for retrieval of detailed structural response. Validity of the approach has been established with simple numerical experiments. (Auth.)

Homologous structure-function relationships between native fibrocartilage and tissue engineered from MSC-seeded nanofibrous scaffolds.

Science.gov (United States)

Nerurkar, Nandan L; Han, Woojin; Mauck, Robert L; Elliott, Dawn M

2011-01-01

Understanding the interplay of composition, organization and mechanical function in load-bearing tissues is a prerequisite in the successful engineering of tissues to replace diseased ones. Mesenchymal stem cells (MSCs) seeded on electrospun scaffolds have been successfully used to generate organized tissues that mimic fibrocartilages such as the knee meniscus and the annulus fibrosus of the intervertebral disc. While matrix deposition has been observed in parallel with improved mechanical properties, how composition, organization, and mechanical function are related is not known. Moreover, how this relationship compares to that of native fibrocartilage is unclear. Therefore, in the present work, functional fibrocartilage constructs were formed from MSC-seeded nanofibrous scaffolds, and the roles of collagen and glycosaminoglycan (GAG) in compressive and tensile properties were determined. MSCs deposited abundant collagen and GAG over 120 days of culture, and these extracellular molecules were organized in such a way that they performed similar mechanical functions to their native roles: collagen dominated the tensile response while GAG was important for compressive properties. GAG removal resulted in significant stiffening in tension. A similar stiffening response was observed when GAG was removed from native inner annulus fibrosus, suggesting an interaction between collagen fibers and their surrounding extrafibrillar matrix that is shared by both engineered and native fibrocartilages. These findings strongly support the use of electrospun scaffolds and MSCs for fibrocartilage tissue engineering, and provide insight on the structure-function relations of both engineered and native biomaterials. Copyright © 2010 Elsevier Ltd. All rights reserved.

Assessment of soil-structure interaction effects based on simple modes

International Nuclear Information System (INIS)

Philippacopoulos, A.J.; Miller, C.A.

1983-01-01

Soil-structure interaction effects are investigated using a simple mathematical model which employs three degrees-of-freedom. The foundation is approximated by a homogeneous, isotropic, elastic half-space. Harmonic functions and a recorded earthquake are used to represent the free-field input motion. Variations of the response characteristics due to structural and interaction parameters are demonstrated. Response spectra are presented that display the magnitude of the maximum structural response for a range of fixed-base structural frequencies, interaction frequencies and damping. Conclusions are obtained regarding the behavior of the response of the soil-structure system. The findings reported herein can be used for the interpretation of the results of soil-structure interaction analyses of nuclear plant structures that are performed with available computer codes

Neighborhood structure effects on the Dynamic response of soil-structure interaction by harmonic analysis

Directory of Open Access Journals (Sweden)

Pan Dan-guang

2015-01-01

Full Text Available For realizing the variation of structural dynamic characteristics due to neighbor structure in buildings group, the surface structure is idealized as an equivalent single degree of freedom system with rigid base whose site consists of a single homogeneous layer. Based on the model, a equivalent method on the equivalent seismic excitation is proposed. Then, the differences of seismic response and equivalent seismic input between soil - structure interaction (SSI system and structure -soil-structure interaction (SSSI system are investigated by harmonic analysis. The numerical results show that dynamic responses would be underestimated in SSSI system when the forcing frequencies are close to the Natural frequency if the effects of neighborhood structure were ignored. Neighborhood structure would make the translational displacement increase and rocking vibration decrease. When establishing an effective seismic input, it is necessary to consider the impact of inertia interaction.

Convergence acceleration for partitioned simulations of the fluid-structure interaction in arteries

Science.gov (United States)

Radtke, Lars; Larena-Avellaneda, Axel; Debus, Eike Sebastian; Düster, Alexander

2016-06-01

We present a partitioned approach to fluid-structure interaction problems arising in analyses of blood flow in arteries. Several strategies to accelerate the convergence of the fixed-point iteration resulting from the coupling of the fluid and the structural sub-problem are investigated. The Aitken relaxation and variants of the interface quasi-Newton -least-squares method are applied to different test cases. A hybrid variant of two well-known variants of the interface quasi-Newton-least-squares method is found to perform best. The test cases cover the typical boundary value problem faced when simulating the fluid-structure interaction in arteries, including a strong added mass effect and a wet surface which accounts for a large part of the overall surface of each sub-problem. A rubber-like Neo Hookean material model and a soft-tissue-like Holzapfel-Gasser-Ogden material model are used to describe the artery wall and are compared in terms of stability and computational expenses. To avoid any kind of locking, high-order finite elements are used to discretize the structural sub-problem. The finite volume method is employed to discretize the fluid sub-problem. We investigate the influence of mass-proportional damping and the material model chosen for the artery on the performance and stability of the acceleration strategies as well as on the simulation results. To show the applicability of the partitioned approach to clinical relevant studies, the hemodynamics in a pathologically deformed artery are investigated, taking the findings of the test case simulations into account.

The Complex Interaction of Matrix Metalloproteinases in the Migration of Cancer Cells through Breast Tissue Stroma

Directory of Open Access Journals (Sweden)

Kerry J. Davies

2014-01-01

Full Text Available Breast cancer mortality is directly linked to metastatic spread. The metastatic cell must exhibit a complex phenotype that includes the capacity to escape from the primary tumour mass, invade the surrounding normal tissue, and penetrate into the circulation before proliferating in the parenchyma of distant organs to produce a metastasis. In the normal breast, cellular structures change cyclically in response to ovarian hormones leading to regulated cell proliferation and apoptosis. Matrix metalloproteinases (MMPs are a family of zinc dependent endopeptidases. Their primary function is degradation of proteins in the extracellular matrix to allow ductal progression through the basement membrane. A complex balance between matrix metalloproteinases and their inhibitors regulate these changes. These proteinases interact with cytokines, growth factors, and tumour necrosis factors to stimulate branching morphologies in normal breast tissues. In breast cancer this process is disrupted facilitating tumour progression and metastasis and inhibiting apoptosis increasing the life of the metastatic cells. This paper highlights the role of matrix metalloproteinases in cell progression through the breast stroma and reviews the complex relationships between the different proteinases and their inhibitors in relation to breast cancer cells as they metastasise.

Study on Human-structure Dynamic Interaction in Civil Engineering

Science.gov (United States)

Gao, Feng; Cao, Li Lin; Li, Xing Hua

2018-06-01

The research of human-structure dynamic interaction are reviewed. Firstly, the influence of the crowd load on structural dynamic characteristics is introduced and the advantages and disadvantages of different crowd load models are analyzed. Then, discussing the influence of structural vibration on the human-induced load, especially the influence of different stiffness structures on the crowd load. Finally, questions about human-structure interaction that require further study are presented.

A structure-based extracellular matrix expansion mechanism of fibrous tissue growth.

Science.gov (United States)

Kalson, Nicholas S; Lu, Yinhui; Taylor, Susan H; Starborg, Tobias; Holmes, David F; Kadler, Karl E

2015-05-20

Embryonic growth occurs predominately by an increase in cell number; little is known about growth mechanisms later in development when fibrous tissues account for the bulk of adult vertebrate mass. We present a model for fibrous tissue growth based on 3D-electron microscopy of mouse tendon. We show that the number of collagen fibrils increases during embryonic development and then remains constant during postnatal growth. Embryonic growth was explained predominately by increases in fibril number and length. Postnatal growth arose predominately from increases in fibril length and diameter. A helical crimp structure was established in embryogenesis, and persisted postnatally. The data support a model where the shape and size of tendon is determined by the number and position of embryonic fibroblasts. The collagen fibrils that these cells synthesise provide a template for postnatal growth by structure-based matrix expansion. The model has important implications for growth of other fibrous tissues and fibrosis.

Cellular structures in a system of interacting particles

International Nuclear Information System (INIS)

Lev, B.I.

2009-01-01

The general description of the formation of a cellular structure in the system of interacting particles is proposed. The analytical results for possible cellular structures in the usual colloidal systems, systems of particles immersed in a liquid crystal, and gravitational systems have been presented. It is shown that the formation of a cellular structure in all systems of interacting particles at different temperatures and concentrations of particles has the same physical nature

Fluid-structure interaction investigations for pipelines

International Nuclear Information System (INIS)

Altstadt, E.; Carl, H.; Weiss, R.

2003-12-01

In existing Nuclear Power Plants water hammers can occur in case of an inflow of sub-cooled water into pipes or other parts of the equipment, which are filled with steam or steam-water mixture. They also may appear as the consequence of fast valve closing or opening actions or of breaks in pipelines, with single phase or two-phase flow. In the latter case, shock waves in two-phase flow must be expected. In all cases, strong dynamic stresses are induced in the wall of the equipment. Further, the change of the momentum of the liquid motion and the deformation of the component due to the dynamic stresses generate high loads on the support structures of the component, in which the water hammer respectively the shock wave occurs. The influence of the fluid-structure interaction on the magnitude of the loads on pipe walls and support structures is not yet completely understood. In case of a dynamic load caused by a pressure wave, the stresses in pipe walls, especially in bends, are different from the static case. The propagating pressure wave may cause additional non-symmetric deformations which increase the equivalent stresses in comparison to the symmetric load created by a static inner pressure. On the other hand, fluid-structure interaction causes the structure to deform, which leads to a decrease of the resulting stresses. The lack of experimental data obtained at well defined geometric boundary conditions is a significant obstacle for the validation of codes which consider fluid-structure interaction. Furthermore, up to now the feedback from structural deformations to the fluid mechanics has not been fully implemented in existing calculation software codes. Therefore, at FZR a cold water hammer test facility (CWHTF) was designed and built up. (orig.)

An experimental study: evaluating the tissue structure of penis with 2D-ShearWave™ Elastography.

Science.gov (United States)

Qiao, X-H; Zhang, J-J; Gao, F; Li, F; Liu, Y; Xing, L-X; Du, L-F; Xing, J-F

2017-01-01

The aim of this study was to investigate the feasibility of two-dimensional-ShearWave™ Elastography (2D-SWE) on evaluating the change of tissue structure of penis. Twenty healthy male Sprague Dawley rats were divided into penis-developed group (PDG, 52 weeks) and penis-underdeveloped group (PUDG, 5 weeks). The ultrafast ultrasound device-Aixplorer® (SuperSonic Imagine) was used for 2D-SWE imaging of the penis, the measurement index was shear wave stiffness (SWS, kPa). All rat penises were cut off immediately after ultrasonic examination. After paraffin embedding, slicing and hematoxylin-eosin staining, the tissue structure of the penis was observed under light microscope. SWS of all rat penises were measured successfully. The results showed that SWS of PDG was significantly lower than PUDG (P=0.008). At the same time, the pathological results found that there were significant differences in the tissue structures (sinusoids, smooth muscle cells and fibrocytes) of the penises between the two groups. These results suggest that there are significant differences in SWS between different tissue structures of penis. 2D-SWE is expected to be used on the etiological diagnosis of erectile dysfunction by serving as a new noninvasive method of evaluating the change of tissue structure of penis.

Natural Polymer-Cell Bioconstructs for Bone Tissue Engineering.

Science.gov (United States)

Titorencu, Irina; Albu, Madalina Georgiana; Nemecz, Miruna; Jinga, Victor V

2017-01-01

The major goal of bone tissue engineering is to develop bioconstructs which substitute the functionality of damaged natural bone structures as much as possible if critical-sized defects occur. Scaffolds that mimic the structure and composition of bone tissue and cells play a pivotal role in bone tissue engineering applications. First, composition, properties and in vivo synthesis of bone tissue are presented for the understanding of bone formation. Second, potential sources of osteoprogenitor cells have been investigated for their capacity to induce bone repair and regeneration. Third, taking into account that the main property to qualify one scaffold as a future bioconstruct for bone tissue engineering is the biocompatibility, the assessments which prove it are reviewed in this paper. Forth, various types of natural polymer- based scaffolds consisting in proteins, polysaccharides, minerals, growth factors etc, are discussed, and interaction between scaffolds and cells which proved bone tissue engineering concept are highlighted. Finally, the future perspectives of natural polymer-based scaffolds for bone tissue engineering are considered. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Comparison of Experimental Models for Predicting Laser Tissue Interaction from 3.8-Micron Lasers

National Research Council Canada - National Science Library

Williams, Charles Melville

2004-01-01

The purpose of this study was to compare and contrast the effects of single 3.8-micron laser pulses in an in-vitro and in-vivo model of human skin and to demonstrate the efficacy of in-vitro laser tissue interaction models...

Study of the argyrophil structures of thymus connective tissue after exposure to X-rays

International Nuclear Information System (INIS)

Beletskij, V.K.; Beletskaya, L.V.; Akademiya Meditsinskikh Nauk SSSR, Moscow. Inst. Ehpidemiologii i Mikrobiologii)

1980-01-01

Studied are argyrophil structures of thymus connective tissue - histiocytes (appendiculate macrophages) and reticuline fibers after the bulk of lymphoid cells has migrated from the organ due to irradiation of animals with X-rays. 10 intact and 16 experimental guinea pigs subjected to the whole-body irradiation with X-rays in the dose of 1000-3000 rad have been used for investigations. It is shown that argyrophil stroma elements of thymus connective tissue, histiocytes and reticular cells, are rather resistant to X-rays and preserve their argyrophily property in the irradiation with high doses, as well as the epithelial cells of the organ. Paraplastic structures in irradiated animals are expressed more completely being demasked as a result of lymphocyte migration and death. The expressed hypertrophy and proliferation of reticular cells and appendiculate macrophages are probably the response to the alternative process in the organ tissues caused by irradiation. A close structural connection of reticular and epithelial tissues on the territory of both layers of thymus sections is noted

Reliability evaluation of containments including soil-structure interaction

International Nuclear Information System (INIS)

Pires, J.; Hwang, H.; Reich, M.

1985-12-01

Soil-structure interaction effects on the reliability assessment of containment structures are examined. The probability-based method for reliability evaluation of nuclear structures developed at Brookhaven National Laboratory is extended to include soil-structure interaction effects. In this method, reliability of structures is expressed in terms of limit state probabilities. Furthermore, random vibration theory is utilized to calculate limit state probabilities under random seismic loads. Earthquake ground motion is modeled by a segment of a zero-mean, stationary, filtered Gaussian white noise random process, represented by its power spectrum. All possible seismic hazards at a site, represented by a hazard curve, are also included in the analysis. The soil-foundation system is represented by a rigid surface foundation on an elastic halfspace. Random and other uncertainties in the strength properties of the structure, in the stiffness and internal damping of the soil, are also included in the analysis. Finally, a realistic reinforced concrete containment is analyzed to demonstrate the application of the method. For this containment, the soil-structure interaction effects on; (1) limit state probabilities, (2) structural fragility curves, (3) floor response spectra with probabilistic content, and (4) correlation coefficients for total acceleration response at specified structural locations, are examined in detail. 25 refs., 21 figs., 12 tabs

Prohibitin/annexin 2 interaction regulates fatty acid transport in adipose tissue

Science.gov (United States)

Salameh, Ahmad; Daquinag, Alexes C.; Staquicini, Daniela I.; An, Zhiqiang; Pasqualini, Renata; Kolonin, Mikhail G.

2016-01-01

We have previously identified prohibitin (PHB) and annexin A2 (ANX2) as proteins interacting on the surface of vascular endothelial cells in white adipose tissue (WAT) of humans and mice. Here, we demonstrate that ANX2 and PHB also interact in adipocytes. Mice lacking ANX2 have normal WAT vascularization, adipogenesis, and glucose metabolism but display WAT hypotrophy due to reduced fatty acid uptake by WAT endothelium and adipocytes. By using cell culture systems in which ANX2/PHB binding is disrupted either genetically or through treatment with a blocking peptide, we show that fatty acid transport efficiency relies on this protein complex. We also provide evidence that the interaction between ANX2 and PHB mediates fatty acid transport from the endothelium into adipocytes. Moreover, we demonstrate that ANX2 and PHB form a complex with the fatty acid transporter CD36. Finally, we show that the colocalization of PHB and CD36 on adipocyte surface is induced by extracellular fatty acids. Together, our results suggest that an unrecognized biochemical interaction between ANX2 and PHB regulates CD36-mediated fatty acid transport in WAT, thus revealing a new potential pathway for intervention in metabolic diseases. PMID:27468426

Interactive effects of warming, eutrophication and size structure: impacts on biodiversity and food-web structure.

Science.gov (United States)

Binzer, Amrei; Guill, Christian; Rall, Björn C; Brose, Ulrich

2016-01-01

Warming and eutrophication are two of the most important global change stressors for natural ecosystems, but their interaction is poorly understood. We used a dynamic model of complex, size-structured food webs to assess interactive effects on diversity and network structure. We found antagonistic impacts: Warming increases diversity in eutrophic systems and decreases it in oligotrophic systems. These effects interact with the community size structure: Communities of similarly sized species such as parasitoid-host systems are stabilized by warming and destabilized by eutrophication, whereas the diversity of size-structured predator-prey networks decreases strongly with warming, but decreases only weakly with eutrophication. Nonrandom extinction risks for generalists and specialists lead to higher connectance in networks without size structure and lower connectance in size-structured communities. Overall, our results unravel interactive impacts of warming and eutrophication and suggest that size structure may serve as an important proxy for predicting the community sensitivity to these global change stressors. © 2015 John Wiley & Sons Ltd.

Structure-Interaction Theory: Conceptual, Contextual and Strategic Influences on Human Communication

Directory of Open Access Journals (Sweden)

Стивен А Биби

2015-12-01

Full Text Available This paper addresses Structure-Interaction Theory (SIT, a theoretical framework that both describes communication messages as well as assists in making predictions about how human communication can be improved based on listener preferences for message structure or interaction. Communication messages may be characterized as existing on a continuum of structure-interaction. Communication structure is the inherent way information in a message is organized. A highly structured message is one in which the message is strategically organized using a planned arrangement of symbols to create meaning. Communication interaction is a way of viewing a message with give-and-take, less sustained “notes,” more change in note sequence and briefer notes. SIT seeks to provide a framework to assist communicators in appropriately adapting a message for maximum effectiveness. Although Structure-Interaction Theory newly articulated here, it is anchored in both classic ways of describing communication, such as rhetoric and dialectic (Aristotle, 1959, as well as more contemporary communication theories (Salem, 2012; Littlejohn & Foss, 2008. Specifically, the paper provides an overview of the theory and its conceptual assumptions, identifies how the theory can help explain and predict communication in several communication contexts (interpersonal, group, public communication, and suggests how SIT may help identify strategies to enhance human development. Structure-Interaction Theory is based on an assumption that a human communication message which is understood, achieves the intended effect of the communicator, and is ethical, requires an appropriate balance of two things: structure and interaction. Communication structure is the inherent way a message is constructed to provide a sustained direction to present information to another person. In linking structure and interaction to Aristotle’s description of messages, rhetoric is a more structured, sustained speech

A Kinome RNAi Screen in Drosophila Identifies Novel Genes Interacting with Lgl, aPKC, and Crb Cell Polarity Genes in Epithelial Tissues.

Science.gov (United States)

Parsons, Linda M; Grzeschik, Nicola A; Amaratunga, Kasun; Burke, Peter; Quinn, Leonie M; Richardson, Helena E

2017-08-07

In both Drosophila melanogaster and mammalian systems, epithelial structure and underlying cell polarity are essential for proper tissue morphogenesis and organ growth. Cell polarity interfaces with multiple cellular processes that are regulated by the phosphorylation status of large protein networks. To gain insight into the molecular mechanisms that coordinate cell polarity with tissue growth, we screened a boutique collection of RNAi stocks targeting the kinome for their capacity to modify Drosophila "cell polarity" eye and wing phenotypes. Initially, we identified kinase or phosphatase genes whose depletion modified adult eye phenotypes associated with the manipulation of cell polarity complexes (via overexpression of Crb or aPKC). We next conducted a secondary screen to test whether these cell polarity modifiers altered tissue overgrowth associated with depletion of Lgl in the wing. These screens identified Hippo, Jun kinase (JNK), and Notch signaling pathways, previously linked to cell polarity regulation of tissue growth. Furthermore, novel pathways not previously connected to cell polarity regulation of tissue growth were identified, including Wingless (Wg/Wnt), Ras, and lipid/Phospho-inositol-3-kinase (PI3K) signaling pathways. Additionally, we demonstrated that the "nutrient sensing" kinases Salt Inducible Kinase 2 and 3 ( SIK2 and 3 ) are potent modifiers of cell polarity phenotypes and regulators of tissue growth. Overall, our screen has revealed novel cell polarity-interacting kinases and phosphatases that affect tissue growth, providing a platform for investigating molecular mechanisms coordinating cell polarity and tissue growth during development. Copyright © 2017 Parsons et al.

Annotation of loci from genome-wide association studies using tissue-specific quantitative interaction proteomics

NARCIS (Netherlands)

Lundby, Alicia; Rossin, Elizabeth J.; Steffensen, Annette B.; Acha, Moshe Ray; Newton-Cheh, Christopher; Pfeufer, Arne; Lyneh, Stacey N.; Olesen, Soren-Peter; Brunak, Soren; Ellinor, Patrick T.; Jukema, J. Wouter; Trompet, Stella; Ford, Ian; Macfarlane, Peter W.; Krijthe, Bouwe P.; Hofman, Albert; Uitterlinden, Andre G.; Stricker, Bruno H.; Nathoe, Hendrik M.; Spiering, Wilko; Daly, Mark J.; Asselbergs, Ikea W.; van der Harst, Pim; Milan, David J.; de Bakker, Paul I. W.; Lage, Kasper; Olsen, Jesper V.

Genome-wide association studies (GWAS) have identified thousands of loci associated with complex traits, but it is challenging to pinpoint causal genes in these loci and to exploit subtle association signals. We used tissue-specific quantitative interaction proteomics to map a network of five genes

Numerically stable fluid–structure interactions between compressible flow and solid structures

KAUST Repository

Grétarsson, Jón Tómas

2011-04-01

We propose a novel method to implicitly two-way couple Eulerian compressible flow to volumetric Lagrangian solids. The method works for both deformable and rigid solids and for arbitrary equations of state. The method exploits the formulation of [11] which solves compressible fluid in a semi-implicit manner, solving for the advection part explicitly and then correcting the intermediate state to time tn+1 using an implicit pressure, obtained by solving a modified Poisson system. Similar to previous fluid-structure interaction methods, we apply pressure forces to the solid and enforce a velocity boundary condition on the fluid in order to satisfy a no-slip constraint. Unlike previous methods, however, we apply these coupled interactions implicitly by adding the constraint to the pressure system and combining it with any implicit solid forces in order to obtain a strongly coupled, symmetric indefinite system (similar to [17], which only handles incompressible flow). We also show that, under a few reasonable assumptions, this system can be made symmetric positive-definite by following the methodology of [16]. Because our method handles the fluid-structure interactions implicitly, we avoid introducing any new time step restrictions and obtain stable results even for high density-to-mass ratios, where explicit methods struggle or fail. We exactly conserve momentum and kinetic energy (thermal fluid-structure interactions are not considered) at the fluid-structure interface, and hence naturally handle highly non-linear phenomenon such as shocks, contacts and rarefactions. © 2011 Elsevier Inc.

Comparative laser-tissue interaction effects at 1.96 and 2.01 um of Cr; Tm:YAG laser

Science.gov (United States)

Pankratov, Michail M.; Perrault, Donald F., Jr.; Shapshay, Stanley M.; Pinto, Joseph F.; Esterowitz, Dina; Aretz, H. Thomas

1992-08-01

A pulsed spiking and nonspiking Cr; thulium (Tm):YAG flash lamp pumped laser operating at 1.96 and 2.01 μm was investigated in vitro in the clinically relevant power range for its basic laser-tissue interaction with soft, cartilaginous, and bone tissues. Some explanations of the differences and possible medical applications are discussed.

The mechanical properties of human adipose tissues and their relationships to the structure and composition of the extracellular matrix.

Science.gov (United States)

Alkhouli, Nadia; Mansfield, Jessica; Green, Ellen; Bell, James; Knight, Beatrice; Liversedge, Neil; Tham, Ji Chung; Welbourn, Richard; Shore, Angela C; Kos, Katarina; Winlove, C Peter

2013-12-01

Adipose tissue (AT) expansion in obesity is characterized by cellular growth and continuous extracellular matrix (ECM) remodeling with increased fibrillar collagen deposition. It is hypothesized that the matrix can inhibit cellular expansion and lipid storage. Therefore, it is important to fully characterize the ECM's biomechanical properties and its interactions with cells. In this study, we characterize and compare the mechanical properties of human subcutaneous and omental tissues, which have different physiological functions. AT was obtained from 44 subjects undergoing surgery. Force/extension and stress/relaxation data were obtained. The effects of osmotic challenge were measured to investigate the cellular contribution to tissue mechanics. Tissue structure and its response to tensile strain were determined using nonlinear microscopy. AT showed nonlinear stress/strain characteristics of up to a 30% strain. Comparing paired subcutaneous and omental samples (n = 19), the moduli were lower in subcutaneous: initial 1.6 ± 0.8 (means ± SD) and 2.9 ± 1.5 kPa (P = 0.001), final 11.7 ± 6.4 and 32 ± 15.6 kPa (P matrix fibers. These results suggest that subcutaneous AT has greater capacity for expansion and recovery from mechanical deformation than omental AT.

Earthquake response analysis considering structure-soil-structure interaction

International Nuclear Information System (INIS)

Shiomi, T.; Takahashi, K.; Oguro, E.

1981-01-01

This paper proposes a numerical method of earthquake response analysis considering the structure-soil-structure interaction between two adjacent buildings. In this paper an analytical study is presented in order to show some typical features of coupling effects of two reactor buildings of the BWR-type nuclear power plant. The technical approach is a kind of substructure method, which at first evaluates the compliance properties with the foundation-soil-foundation interaction and then uses the compliance in determining seismic responses of two super-structures during earthquake motions. For this purpose, it is assumed that the soil medium is an elastic half space for modeling and that the rigidity of any type of structures such as piping facilities connecting the adjacent buildings is negligible. The technical approach is mainly based on the following procedures. Supersturcture stiffness is calculated by using the method which has been developed in our laboratory based on the Thin-Wall Beam Theory. Soil stiffness is expressed by a matrix with 12 x 12 elements as a function of frequency, which is calculated using the soil compliance functions proposed in Dr. Tajimi's Theory. These stiffness values may be expressed by complex numbers for modeling the damping mechanism of superstructures. We can solve eigenvalue problems with frequency dependent stiffness and the large-scale matrix using our method which is based on condensing the matrix to the suitable size by Rayleigh-Ritz method. Earthquake responses can be solved in the frequency domain by Fourier Transform. (orig./RW)

Algebraic structure of open string interactions

International Nuclear Information System (INIS)

Ramond, P.; Rodgers, V.G.J.

1986-05-01

Starting from the gauge invariant equations of motion for the free open string we show how to generate interactions by analogy with Yang-Mills. We postulate Non-Abelian transformation laws acting on the fields of the gauge invariant free open string theory. By demanding algebraic closure we then derive a set of consistency requirements and show that they lead to the construction of the minimal interacting equations which contain no cubic terms away from the physical gauge. We present explicit solutions to lowest interacting order for both vertices and structure functions. 14 refs

Algebraic structure of open-string interactions

International Nuclear Information System (INIS)

Ramond, P.; Rodgers, V.G.J.

1986-01-01

Starting from the gauge-invariant equations of motion for the free open string we show how to generate interactions by analogy with the Yang-Mills system. We postulate non-Abelian transformation laws acting on the fields of the gauge-invariant free open-string theory. By demanding algebraic closure we then derive a set of consistency requirements and show that they lead to the construction of the minimal interacting equations which contain no cubic terms away from the physical gauge. We present explicit solutions to lowest interacting order for both vertices and structure functions

Interactive extraction of neural structures with user-guided morphological diffusion

KAUST Repository

Yong Wan,; Otsuna, H.; Chi-Bin Chien,; Hansen, C.

2012-01-01

Extracting neural structures with their fine details from confocal volumes is essential to quantitative analysis in neurobiology research. Despite the abundance of various segmentation methods and tools, for complex neural structures, both manual and semi-automatic methods are ine ective either in full 3D or when user interactions are restricted to 2D slices. Novel interaction techniques and fast algorithms are demanded by neurobiologists to interactively and intuitively extract neural structures from confocal data. In this paper, we present such an algorithm-technique combination, which lets users interactively select desired structures from visualization results instead of 2D slices. By integrating the segmentation functions with a confocal visualization tool neurobiologists can easily extract complex neural structures within their typical visualization workflow.

Interactive extraction of neural structures with user-guided morphological diffusion

KAUST Repository

Yong Wan,

2012-10-01

Extracting neural structures with their fine details from confocal volumes is essential to quantitative analysis in neurobiology research. Despite the abundance of various segmentation methods and tools, for complex neural structures, both manual and semi-automatic methods are ine ective either in full 3D or when user interactions are restricted to 2D slices. Novel interaction techniques and fast algorithms are demanded by neurobiologists to interactively and intuitively extract neural structures from confocal data. In this paper, we present such an algorithm-technique combination, which lets users interactively select desired structures from visualization results instead of 2D slices. By integrating the segmentation functions with a confocal visualization tool neurobiologists can easily extract complex neural structures within their typical visualization workflow.

Comparative Analyses of Tomato yellow leaf curl virus C4 Protein-Interacting Host Proteins in Healthy and Infected Tomato Tissues

Directory of Open Access Journals (Sweden)

Namgyu Kim

2016-10-01

Full Text Available Tomato yellow leaf curl virus (TYLCV, a member of the genus Begomovirus, is one of the most important viruses of cultivated tomatoes worldwide, mainly causing yellowing and curling of leaves with stunting in plants. TYLCV causes severe problems in sub-tropical and tropical countries, as well as in Korea. However, the mechanism of TYLCV infection remains unclear, although the function of each viral component has been identified. TYLCV C4 codes for a small protein involved in various cellular functions, including symptom determination, gene silencing, viral movement, and induction of the plant defense response. In this study, through yeast-two hybrid screenings, we identified TYLCV C4-interacting host proteins from both healthy and symptom-exhibiting tomato tissues, to determine the role of TYLCV C4 proteins in the infection processes. Comparative analyses of 28 proteins from healthy tissues and 36 from infected tissues showing interactions with TYLCV C4 indicated that TYLCV C4 mainly interacts with host proteins involved in translation, ubiquitination, and plant defense, and most interacting proteins differed between the two tissues but belong to similar molecular functional categories. Four proteins—two ribosomal proteins, S-adenosyl-L-homocysteine hydrolase, and 14-3-3 family protein—were detected in both tissues. Furthermore, the identified proteins in symptom-exhibiting tissues showed greater involvement in plant defenses. Some are key regulators, such as receptor-like kinases and pathogenesis-related proteins, of plant defenses. Thus, TYLCV C4 may contribute to the suppression of host defense during TYLCV infection and be involved in ubiquitination for viral infection.

Multi-physics fluid-structure interaction modelling software

CSIR Research Space (South Africa)

Malan, AG

2008-11-01

Full Text Available -structure interaction modelling software AG MALAN AND O OXTOBY CSIR Defence, Peace, Safety and Security, PO Box 395, Pretoria, 0001 Email: amalan@csir.co.za – www.csir.co.za Internationally leading aerospace company Airbus sponsored key components... of the development of the CSIR fl uid-structure interaction (FSI) software. Below are extracts from their evaluation of the devel- oped technology: “The fi eld of FSI covers a massive range of engineering problems, each with their own multi-parameter, individual...

Interaction between adipose tissue-derived mesenchymal stem cells and regulatory T-cells

OpenAIRE

Engela, Anja; Baan, Carla; Peeters, Anna; Weimar, Willem; Hoogduijn, Martin

2013-01-01

textabstractMesenchymal stem cells (MSCs) exhibit immunosuppressive capabilities, which have evoked interest in their application as cell therapy in transplant patients. So far it has been unclear whether allogeneic MSCs and host regulatory T-cells (Tregs) functionally influence each other. We investigated the interaction between both cell types using perirenal adipose tissue-derived MSCs (ASCs) from kidney donors and Tregs from blood bank donors or kidney recipients 6 months after transplant...

Structural Analysis of ‘key’ Interactions in Functional RNA Molecules

KAUST Repository

Chawla, Mohit

2018-04-01

The main objective of the thesis is to carry out structural bioinformatics study along with usage of advanced quantum chemical methods to look at the structural stability and energetics of RNA building blocks. The main focus of the work described here lies on understanding the reasons behind the intrinsic stability of key interactions in nucleic acids. Crystal structures of RNA molecules exhibit fascinating variety of non-covalent interactions, which play an important role in maintaining the three dimensional structures. An accurate atomic level description of these interactions in the structural building blocks of RNA is a key to understand the structure-function relationship in these molecules. An effort has been made to link the conclusions drawn from quantum chemical computations on RNA base pairs in wide biochemical context of their occurrence in RNA structures. The initial attention was on the impact of natural and non-natural modifications of the nucleic acid bases on the structure and stability of base pairs that they are involved in. In the remaining sections we cover other molecular interactions shaping nucleic acids, as the interaction between ribose and the bases, and the fluoride sensing riboswitch system in order to investigate structure and dynamics of nucleic acids at the atomic level and to gain insight into the physical chemistry behind.

Structural Analysis of ‘key’ Interactions in Functional RNA Molecules

KAUST Repository

Chawla, Mohit

2018-01-01

The main objective of the thesis is to carry out structural bioinformatics study along with usage of advanced quantum chemical methods to look at the structural stability and energetics of RNA building blocks. The main focus of the work described here lies on understanding the reasons behind the intrinsic stability of key interactions in nucleic acids. Crystal structures of RNA molecules exhibit fascinating variety of non-covalent interactions, which play an important role in maintaining the three dimensional structures. An accurate atomic level description of these interactions in the structural building blocks of RNA is a key to understand the structure-function relationship in these molecules. An effort has been made to link the conclusions drawn from quantum chemical computations on RNA base pairs in wide biochemical context of their occurrence in RNA structures. The initial attention was on the impact of natural and non-natural modifications of the nucleic acid bases on the structure and stability of base pairs that they are involved in. In the remaining sections we cover other molecular interactions shaping nucleic acids, as the interaction between ribose and the bases, and the fluoride sensing riboswitch system in order to investigate structure and dynamics of nucleic acids at the atomic level and to gain insight into the physical chemistry behind.

Mode Interaction in Structures - An Overview

DEFF Research Database (Denmark)

Byskov, Esben

2004-01-01

Abstract Koiter [1] was the first to formulate an asymptotic expansion to investigate postbuckling behavior and imperfection sensitivity of elastic structures. Since then, a large number of analyses of particular structures have appeared as well as some new expansions aimed at specific problems, ...... analyses must always be preferred because asymptotic expansions are obsolete. Keywords: stability, elastic, mode interaction....

Fluid-structure interaction and its effect on the performance of composite structures under air-blast loading

Directory of Open Access Journals (Sweden)

E Wang

2016-09-01

Full Text Available Three material systems: E-glass Vinyl-Ester (EVE composites, sandwich composites with EVE facesheet and monolithic foam core (2 different core thicknesses, and monolithic aluminum alloy plates, were subjected to shock wave loading to study their blast response and fluid-structure interaction behaviors. High-speed photography systems were utilized to obtain the real-time side-view and back face deformation images. A 3-D Digital Image Correlation (DIC technique was used to analyze the real-time back face displacement fields and subsequently obtain the characteristic fluid-structure interaction time. The reflected pressure profiles and the deflection of the back face center point reveal that the areal density plays an important role in the fluid-structure interaction. The predictions from Taylor's model (classical solution, does not consider the compressibility and model by Wang et al. (considers the compressibility were compared with the experimental results. These results indicated that the model by Wang et al. can predict the experimental results accurately, especially during the characteristic fluid-structure interaction time. Further study revealed that the fluid-structure interaction between the fluid and the sandwich composites cannot be simplified as the fluid-structure interaction between the fluid and the facesheet. Also, it was observed that the core thickness affects the fluid-structure interaction behavior of sandwich composites.

A combined structural dynamics approach identifies a putative switch in factor VIIa employed by tissue factor to initiate blood coagulation

DEFF Research Database (Denmark)

Olsen, Ole H; Rand, Kasper D; Østergaard, Henrik

2007-01-01

Coagulation factor VIIa (FVIIa) requires tissue factor (TF) to attain full catalytic competency and to initiate blood coagulation. In this study, the mechanism by which TF allosterically activates FVIIa is investigated by a structural dynamics approach that combines molecular dynamics (MD......) simulations and hydrogen/deuterium exchange (HX) mass spectrometry on free and TF-bound FVIIa. The differences in conformational dynamics from MD simulations are shown to be confined to regions of FVIIa observed to undergo structural stabilization as judged by HX experiments, especially implicating activation...... in the presence of TF or an active-site inhibitor. Based on MD simulations, a key switch of the TF-induced structural changes is identified as the interacting pair Leu305{163} and Phe374{225} in FVIIa, whose mutual conformations are guided by the presence of TF and observed to be closely linked to the structural...

Optical study on the dependence of breast tissue composition and structure on subject anamnesis

Science.gov (United States)

Taroni, Paola; Quarto, Giovanna; Pifferi, Antonio; Abbate, Francesca; Balestreri, Nicola; Menna, Simona; Cassano, Enrico; Cubeddu, Rinaldo

2015-07-01

Time domain multi-wavelength (635 to 1060 nm) optical mammography was performed on 200 subjects to estimate their average breast tissue composition in terms of oxy- and deoxy-hemoglobin, water, lipid and collagen, and structural information, as provided by scattering parameters (amplitude and power). Significant (and often marked) dependence of tissue composition and structure on age, menopausal status, body mass index, and use of oral contraceptives was demonstrated.

A sensitivity study of seismic structure-soil-structure interaction problems for nuclear power plants

International Nuclear Information System (INIS)

Matthees, W.; Magiera, G.

1982-01-01

A sensitivity study for the interaction effects of adjacent structures of nuclear power plants caused by horizontal seismic excitation has been performed. The key structural and soil parameters for linear and for nonlinear behaviour were varied within their applicable bandwidth. It has been shown that the interaction phenomena can contribute to the response of structures to such a large extent that it cannot be disregarded. (orig.)

Soil-structure interaction analysis of ZPR6 reactor facility

International Nuclear Information System (INIS)

Ma, D.C.; Ahmed, H.U.

1981-01-01

Due to the computer storage limitation and economic concern, the current practice of soil-structure interaction analysis is limited to two dimensional analysis. The 2-D plane strain finite element program, FLUSH, is one often most used program in the analysis. Seismic response of soil and basement can be determined very well by FLUSH. The response of the structure above ground level, however, is often underestimated. This is mainly due to the three dimensional characteristics of the structures. This paper describes a detailed soil-structure interaction analysis of a rectangular embedded structure in conjunction with FLUSH program. The objective of the analysis is to derive the mean interaction motions at the structure base and the soil dynamic forces exerted on the basement lateral walls. The base motions and lateral soil dynamic forces are the specified boundary conditions for the later 3-D building response analysis. (orig./RW)

The structure of weak interaction

International Nuclear Information System (INIS)

Zee, A.

1977-01-01

The effect of introducing righthanded currents on the structure of weak interaction is discussed. The ΔI=1/2 rule is in the spotlight. The discussion provides an interesting example in which the so-called Iizuka-Okubo-Zweing rule is not only evaded, but completely negated

Structure of the human chromosome interaction network.

Directory of Open Access Journals (Sweden)

Sergio Sarnataro

Full Text Available New Hi-C technologies have revealed that chromosomes have a complex network of spatial contacts in the cell nucleus of higher organisms, whose organisation is only partially understood. Here, we investigate the structure of such a network in human GM12878 cells, to derive a large scale picture of nuclear architecture. We find that the intensity of intra-chromosomal interactions is power-law distributed. Inter-chromosomal interactions are two orders of magnitude weaker and exponentially distributed, yet they are not randomly arranged along the genomic sequence. Intra-chromosomal contacts broadly occur between epigenomically homologous regions, whereas inter-chromosomal contacts are especially associated with regions rich in highly expressed genes. Overall, genomic contacts in the nucleus appear to be structured as a network of networks where a set of strongly individual chromosomal units, as envisaged in the 'chromosomal territory' scenario derived from microscopy, interact with each other via on average weaker, yet far from random and functionally important interactions.

Site response - a critical problem in soil-structure interaction analyses for embedded structures

International Nuclear Information System (INIS)

Seed, H.B.; Lysmer, J.

1986-01-01

Soil-structure interaction analyses for embedded structures must necessarily be based on a knowledge of the manner in which the soil would behave in the absence of any structure - that is on a knowledge and understanding of the spatial distribution of motions in the ground within the depth of embedment of the structure. The nature of these spatial variations is discussed and illustrated by examples of recorded motions. It is shown that both the amplitude of peak acceleration and the form of the acceleration response spectrum for earthquake motions will necessarily vary with depth and failure to take these variations into account may introduce an unwarranted degree of conservatism into the soil-structure interaction analysis procedure

A structural model for the flexural mechanics of nonwoven tissue engineering scaffolds.

Science.gov (United States)

Engelmayr, George C; Sacks, Michael S

2006-08-01

The development of methods to predict the strength and stiffness of biomaterials used in tissue engineering is critical for load-bearing applications in which the essential functional requirements are primarily mechanical. We previously quantified changes in the effective stiffness (E) of needled nonwoven polyglycolic acid (PGA) and poly-L-lactic acid (PLLA) scaffolds due to tissue formation and scaffold degradation under three-point bending. Toward predicting these changes, we present a structural model for E of a needled nonwoven scaffold in flexure. The model accounted for the number and orientation of fibers within a representative volume element of the scaffold demarcated by the needling process. The spring-like effective stiffness of the curved fibers was calculated using the sinusoidal fiber shapes. Structural and mechanical properties of PGA and PLLA fibers and PGA, PLLA, and 50:50 PGA/PLLA scaffolds were measured and compared with model predictions. To verify the general predictive capability, the predicted dependence of E on fiber diameter was compared with experimental measurements. Needled nonwoven scaffolds were found to exhibit distinct preferred (PD) and cross-preferred (XD) fiber directions, with an E ratio (PD/XD) of approximately 3:1. The good agreement between the predicted and experimental dependence of E on fiber diameter (R2 = 0.987) suggests that the structural model can be used to design scaffolds with E values more similar to native soft tissues. A comparison with previous results for cell-seeded scaffolds (Engelmayr, G. C., Jr., et al., 2005, Biomaterials, 26(2), pp. 175-187) suggests, for the first time, that the primary mechanical effect of collagen deposition is an increase in the number of fiber-fiber bond points yielding effectively stiffer scaffold fibers. This finding indicated that the effects of tissue deposition on needled nonwoven scaffold mechanics do not follow a rule-of-mixtures behavior. These important results underscore

Small molecule inhibitors target the tissue transglutaminase and fibronectin interaction.

Directory of Open Access Journals (Sweden)

Bakhtiyor Yakubov

Full Text Available Tissue transglutaminase (TG2 mediates protein crosslinking through generation of ε-(γ-glutamyl lysine isopeptide bonds and promotes cell adhesion through interaction with fibronectin (FN and integrins. Cell adhesion to the peritoneal matrix regulated by TG2 facilitates ovarian cancer dissemination. Therefore, disruption of the TG2-FN complex by small molecules may inhibit cell adhesion and metastasis. A novel high throughput screening (HTS assay based on AlphaLISA™ technology was developed to measure the formation of a complex between His-TG2 and the biotinylated FN fragment that binds TG2 and to discover small molecules that inhibit this protein-protein interaction. Several hits were identified from 10,000 compounds screened. The top candidates selected based on >70% inhibition of the TG2/FN complex formation were confirmed by using ELISA and bioassays measuring cell adhesion, migration, invasion, and proliferation. In conclusion, the AlphaLISA bead format assay measuring the TG2-FN interaction is robust and suitable for HTS of small molecules. One compound identified from the screen (TG53 potently inhibited ovarian cancer cell adhesion to FN, cell migration, and invasion and could be further developed as a potential inhibitor for ovarian cancer dissemination.

Structure-function analysis of STRUBBELIG, an Arabidopsis atypical receptor-like kinase involved in tissue morphogenesis.

Directory of Open Access Journals (Sweden)

Prasad Vaddepalli

Full Text Available Tissue morphogenesis in plants requires the coordination of cellular behavior across clonally distinct histogenic layers. The underlying signaling mechanisms are presently being unraveled and are known to include the cell surface leucine-rich repeat receptor-like kinase STRUBBELIG in Arabidopsis. To understand better its mode of action an extensive structure-function analysis of STRUBBELIG was performed. The phenotypes of 20 EMS and T-DNA-induced strubbelig alleles were assessed and homology modeling was applied to rationalize their possible effects on STRUBBELIG protein structure. The analysis was complemented by phenotypic, cell biological, and pharmacological investigations of a strubbelig null allele carrying genomic rescue constructs encoding fusions between various mutated STRUBBELIG proteins and GFP. The results indicate that STRUBBELIG accepts quite some sequence variation, reveal the biological importance for the STRUBBELIG N-capping domain, and reinforce the notion that kinase activity is not essential for its function in vivo. Furthermore, individual protein domains of STRUBBELIG cannot be related to specific STRUBBELIG-dependent biological processes suggesting that process specificity is mediated by factors acting together with or downstream of STRUBBELIG. In addition, the evidence indicates that biogenesis of a functional STRUBBELIG receptor is subject to endoplasmic reticulum-mediated quality control, and that an MG132-sensitive process regulates its stability. Finally, STRUBBELIG and the receptor-like kinase gene ERECTA interact synergistically in the control of internode length. The data provide genetic and molecular insight into how STRUBBELIG regulates intercellular communication in tissue morphogenesis.

Breast tissue classification using x-ray scattering measurements and multivariate data analysis

Science.gov (United States)

Ryan, Elaine A.; Farquharson, Michael J.

2007-11-01

This study utilized two radiation scatter interactions in order to differentiate malignant from non-malignant breast tissue. These two interactions were Compton scatter, used to measure the electron density of the tissues, and coherent scatter to obtain a measure of structure. Measurements of these parameters were made using a laboratory experimental set-up comprising an x-ray tube and HPGe detector. The breast tissue samples investigated comprise five different tissue classifications: adipose, malignancy, fibroadenoma, normal fibrous tissue and tissue that had undergone fibrocystic change. The coherent scatter spectra were analysed using a peak fitting routine, and a technique involving multivariate analysis was used to combine the peak fitted scatter profile spectra and the electron density values into a tissue classification model. The number of variables used in the model was refined by finding the sensitivity and specificity of each model and concentrating on differentiating between two tissues at a time. The best model that was formulated had a sensitivity of 54% and a specificity of 100%.

Breast tissue classification using x-ray scattering measurements and multivariate data analysis

Energy Technology Data Exchange (ETDEWEB)

Ryan, Elaine A; Farquharson, Michael J [School of Allied Health Sciences, City University, Charterhouse Square, London EC1M 6PA (United Kingdom)

2007-11-21

This study utilized two radiation scatter interactions in order to differentiate malignant from non-malignant breast tissue. These two interactions were Compton scatter, used to measure the electron density of the tissues, and coherent scatter to obtain a measure of structure. Measurements of these parameters were made using a laboratory experimental set-up comprising an x-ray tube and HPGe detector. The breast tissue samples investigated comprise five different tissue classifications: adipose, malignancy, fibroadenoma, normal fibrous tissue and tissue that had undergone fibrocystic change. The coherent scatter spectra were analysed using a peak fitting routine, and a technique involving multivariate analysis was used to combine the peak fitted scatter profile spectra and the electron density values into a tissue classification model. The number of variables used in the model was refined by finding the sensitivity and specificity of each model and concentrating on differentiating between two tissues at a time. The best model that was formulated had a sensitivity of 54% and a specificity of 100%.

Gelatin Scaffolds with Controlled Pore Structure and Mechanical Property for Cartilage Tissue Engineering.

Science.gov (United States)

Chen, Shangwu; Zhang, Qin; Nakamoto, Tomoko; Kawazoe, Naoki; Chen, Guoping

2016-03-01

Engineering of cartilage tissue in vitro using porous scaffolds and chondrocytes provides a promising approach for cartilage repair. However, nonuniform cell distribution and heterogeneous tissue formation together with weak mechanical property of in vitro engineered cartilage limit their clinical application. In this study, gelatin porous scaffolds with homogeneous and open pores were prepared using ice particulates and freeze-drying. The scaffolds were used to culture bovine articular chondrocytes to engineer cartilage tissue in vitro. The pore structure and mechanical property of gelatin scaffolds could be well controlled by using different ratios of ice particulates to gelatin solution and different concentrations of gelatin. Gelatin scaffolds prepared from ≥70% ice particulates enabled homogeneous seeding of bovine articular chondrocytes throughout the scaffolds and formation of homogeneous cartilage extracellular matrix. While soft scaffolds underwent cellular contraction, stiff scaffolds resisted cellular contraction and had significantly higher cell proliferation and synthesis of sulfated glycosaminoglycan. Compared with the gelatin scaffolds prepared without ice particulates, the gelatin scaffolds prepared with ice particulates facilitated formation of homogeneous cartilage tissue with significantly higher compressive modulus. The gelatin scaffolds with highly open pore structure and good mechanical property can be used to improve in vitro tissue-engineered cartilage.

Potato leafroll virus structural proteins manipulate overlapping, yet distinct protein interaction networks during infection.

Science.gov (United States)

DeBlasio, Stacy L; Johnson, Richard; Sweeney, Michelle M; Karasev, Alexander; Gray, Stewart M; MacCoss, Michael J; Cilia, Michelle

2015-06-01

Potato leafroll virus (PLRV) produces a readthrough protein (RTP) via translational readthrough of the coat protein amber stop codon. The RTP functions as a structural component of the virion and as a nonincorporated protein in concert with numerous insect and plant proteins to regulate virus movement/transmission and tissue tropism. Affinity purification coupled to quantitative MS was used to generate protein interaction networks for a PLRV mutant that is unable to produce the read through domain (RTD) and compared to the known wild-type PLRV protein interaction network. By quantifying differences in the protein interaction networks, we identified four distinct classes of PLRV-plant interactions: those plant and nonstructural viral proteins interacting with assembled coat protein (category I); plant proteins in complex with both coat protein and RTD (category II); plant proteins in complex with the RTD (category III); and plant proteins that had higher affinity for virions lacking the RTD (category IV). Proteins identified as interacting with the RTD are potential candidates for regulating viral processes that are mediated by the RTP such as phloem retention and systemic movement and can potentially be useful targets for the development of strategies to prevent infection and/or viral transmission of Luteoviridae species that infect important crop species. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cold crucible technique for interaction test of molten corium with structure

International Nuclear Information System (INIS)

Ha, Kwang Soon; An, Sang Mo; Min, Beong Tae; Kim, Hwan Yeol

2012-01-01

During a severe accident, the molten corium might interact with several structures in a nuclear power plant such as core peripheral structures, lower plenum, lower head vessel, and external structures of a reactor vessel. The interaction of the molten corium with the structure depends on the molten corium composition, temperature, structural materials, and environmental conditions such as pressure and humidity. For example, the interaction of a metallic molten corium containing metal uranium (U) and zirconium (Zr) with the oxidized steel structure (Fe 2O3 ) is affected by not only thermal ablation but oxidation reduction reaction because the oxidation quotients of the U and Zr are higher than that of Fe. KAERI set up an experimental facility and technique using a cold crucible melting method to verify the interaction mechanism between the metallic molten corium and structural materials. This technique includes the generation of the metallic melt, melt delivery, measurement of the interaction process, and post analyses after the test

Shaping tissues by balancing active forces and geometric constraints

Science.gov (United States)

Foolen, Jasper; Yamashita, Tadahiro; Kollmannsberger, Philip

2016-02-01

The self-organization of cells into complex tissues during growth and regeneration is a combination of physical-mechanical events and biochemical signal processing. Cells actively generate forces at all stages in this process, and according to the laws of mechanics, these forces result in stress fields defined by the geometric boundary conditions of the cell and tissue. The unique ability of cells to translate such force patterns into biochemical information and vice versa sets biological tissues apart from any other material. In this topical review, we summarize the current knowledge and open questions of how forces and geometry act together on scales from the single cell to tissues and organisms, and how their interaction determines biological shape and structure. Starting with a planar surface as the simplest type of geometric constraint, we review literature on how forces during cell spreading and adhesion together with geometric constraints impact cell shape, stress patterns, and the resulting biological response. We then move on to include cell-cell interactions and the role of forces in monolayers and in collective cell migration, and introduce curvature at the transition from flat cell sheets to three-dimensional (3D) tissues. Fibrous 3D environments, as cells experience them in the body, introduce new mechanical boundary conditions and change cell behaviour compared to flat surfaces. Starting from early work on force transmission and collagen remodelling, we discuss recent discoveries on the interaction with geometric constraints and the resulting structure formation and network organization in 3D. Recent literature on two physiological scenarios—embryonic development and bone—is reviewed to demonstrate the role of the force-geometry balance in living organisms. Furthermore, the role of mechanics in pathological scenarios such as cancer is discussed. We conclude by highlighting common physical principles guiding cell mechanics, tissue patterning and

Shaping tissues by balancing active forces and geometric constraints

International Nuclear Information System (INIS)

Foolen, Jasper; Yamashita, Tadahiro; Kollmannsberger, Philip

2016-01-01

The self-organization of cells into complex tissues during growth and regeneration is a combination of physical–mechanical events and biochemical signal processing. Cells actively generate forces at all stages in this process, and according to the laws of mechanics, these forces result in stress fields defined by the geometric boundary conditions of the cell and tissue. The unique ability of cells to translate such force patterns into biochemical information and vice versa sets biological tissues apart from any other material. In this topical review, we summarize the current knowledge and open questions of how forces and geometry act together on scales from the single cell to tissues and organisms, and how their interaction determines biological shape and structure. Starting with a planar surface as the simplest type of geometric constraint, we review literature on how forces during cell spreading and adhesion together with geometric constraints impact cell shape, stress patterns, and the resulting biological response. We then move on to include cell–cell interactions and the role of forces in monolayers and in collective cell migration, and introduce curvature at the transition from flat cell sheets to three-dimensional (3D) tissues. Fibrous 3D environments, as cells experience them in the body, introduce new mechanical boundary conditions and change cell behaviour compared to flat surfaces. Starting from early work on force transmission and collagen remodelling, we discuss recent discoveries on the interaction with geometric constraints and the resulting structure formation and network organization in 3D. Recent literature on two physiological scenarios—embryonic development and bone—is reviewed to demonstrate the role of the force-geometry balance in living organisms. Furthermore, the role of mechanics in pathological scenarios such as cancer is discussed. We conclude by highlighting common physical principles guiding cell mechanics, tissue patterning

Establishing Early Functional Perfusion and Structure in Tissue Engineered Cardiac Constructs.

Science.gov (United States)

Wang, Bo; Patnaik, Sourav S; Brazile, Bryn; Butler, J Ryan; Claude, Andrew; Zhang, Ge; Guan, Jianjun; Hong, Yi; Liao, Jun

2015-01-01

Myocardial infarction (MI) causes massive heart muscle death and remains a leading cause of death in the world. Cardiac tissue engineering aims to replace the infarcted tissues with functional engineered heart muscles or revitalize the infarcted heart by delivering cells, bioactive factors, and/or biomaterials. One major challenge of cardiac tissue engineering and regeneration is the establishment of functional perfusion and structure to achieve timely angiogenesis and effective vascularization, which are essential to the survival of thick implants and the integration of repaired tissue with host heart. In this paper, we review four major approaches to promoting angiogenesis and vascularization in cardiac tissue engineering and regeneration: delivery of pro-angiogenic factors/molecules, direct cell implantation/cell sheet grafting, fabrication of prevascularized cardiac constructs, and the use of bioreactors to promote angiogenesis and vascularization. We further provide a detailed review and discussion on the early perfusion design in nature-derived biomaterials, synthetic biodegradable polymers, tissue-derived acellular scaffolds/whole hearts, and hydrogel derived from extracellular matrix. A better understanding of the current approaches and their advantages, limitations, and hurdles could be useful for developing better materials for future clinical applications.

Affinity imaging mass spectrometry (AIMS): high-throughput screening for specific small molecule interactions with frozen tissue sections.

Science.gov (United States)

Yoshimi, T; Kawabata, S; Taira, S; Okuno, A; Mikawa, R; Murayama, S; Tanaka, K; Takikawa, O

2015-11-07

A novel screening system, using affinity imaging mass spectrometry (AIMS), has been developed to identify protein aggregates or organ structures in unfixed human tissue. Frozen tissue sections are positioned on small (millimetre-scale) stainless steel chips and incubated with an extensive library of small molecules. Candidate molecules showing specific affinity for the tissue section are identified by imaging mass spectrometry (IMS). As an example application, we screened over a thousand compounds against Alzheimer's disease (AD) brain tissue and identified several compounds with high affinity for AD brain sections containing tau deposits compared to age-matched controls. It should also be possible to use AIMS to isolate chemical compounds with affinity for tissue structures or components that have been extensively modified by events such as oxidation, phosphorylation, acetylation, aggregation, racemization or truncation, for example, due to aging. It may also be applicable to biomarker screening programs.

Fluid-structure interactions models, analysis and finite elements

CERN Document Server

Richter, Thomas

2017-01-01

This book starts by introducing the fundamental concepts of mathematical continuum mechanics for fluids and solids and their coupling. Special attention is given to the derivation of variational formulations for the subproblems describing fluid- and solid-mechanics as well as the coupled fluid-structure interaction problem. Two monolithic formulations for fluid-structure interactions are described in detail: the well-established ALE formulation and the modern Fully Eulerian formulation, which can effectively deal with problems featuring large deformation and contact. Further, the book provides details on state-of-the-art discretization schemes for fluid- and solid-mechanics and considers the special needs of coupled problems with interface-tracking and interface-capturing techniques. Lastly, advanced topics like goal-oriented error estimation, multigrid solution and gradient-based optimization schemes are discussed in the context of fluid-structure interaction problems.

Structure-function analysis of RBP-J-interacting and tubulin-associated (RITA) reveals regions critical for repression of Notch target genes.

Science.gov (United States)

Tabaja, Nassif; Yuan, Zhenyu; Oswald, Franz; Kovall, Rhett A

2017-06-23

The Notch pathway is a cell-to-cell signaling mechanism that is essential for tissue development and maintenance, and aberrant Notch signaling has been implicated in various cancers, congenital defects, and cardiovascular diseases. Notch signaling activates the expression of target genes, which are regulated by the transcription factor CSL (CBF1/RBP-J, Su(H), Lag-1). CSL interacts with both transcriptional corepressor and coactivator proteins, functioning as both a repressor and activator, respectively. Although Notch activation complexes are relatively well understood at the structural level, less is known about how CSL interacts with corepressors. Recently, a new RBP-J (mammalian CSL ortholog)-interacting protein termed RITA has been identified and shown to export RBP-J out of the nucleus, thereby leading to the down-regulation of Notch target gene expression. However, the molecular details of RBP-J/RITA interactions are unclear. Here, using a combination of biochemical/cellular, structural, and biophysical techniques, we demonstrate that endogenous RBP-J and RITA proteins interact in cells, map the binding regions necessary for RBP-J·RITA complex formation, and determine the X-ray structure of the RBP-J·RITA complex bound to DNA. To validate the structure and glean more insights into function, we tested structure-based RBP-J and RITA mutants with biochemical/cellular assays and isothermal titration calorimetry. Whereas our structural and biophysical studies demonstrate that RITA binds RBP-J similarly to the RAM (RBP-J-associated molecule) domain of Notch, our biochemical and cellular assays suggest that RITA interacts with additional regions in RBP-J. Taken together, these results provide molecular insights into the mechanism of RITA-mediated regulation of Notch signaling, contributing to our understanding of how CSL functions as a transcriptional repressor of Notch target genes. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Toolkit Design for Interactive Structured Graphics

National Research Council Canada - National Science Library

Bederson, Benjamin B; Grosjean, Jesse; Meyer, Jon

2003-01-01

.... We describe Jazz (a polylithic toolkit) and Piccolo (a monolithic toolkit), each of which we built to support interactive 2D structured graphics applications in general, and Zoomable User Interface applications in particular...

Hadronic interaction and structure of exotic nuclei

International Nuclear Information System (INIS)

Otsuka, Takaharu

2009-01-01

I will overview recent studies on the evolution of the shell structure in stable and exotic nuclei, and will show its relevance to hadronic interaction, including nuclear forces. This shell evolution is primarily due to the tensor force. The robust mechanism and some examples will be presented. Such examples include the disappearance of existing magic numbers and the appearance of new ones. The shell structure and existing limit of nuclei depend also on the three-body interaction in a specific way. I will sketch how the Δ-hole excitation induced three-body force (Fujita-Miyazawa force) modifies them. (author)

Comparison of micromorphometric testis tissue structures in antenatal fetuses and patients with congenital cryptorchidism

Directory of Open Access Journals (Sweden)

K. V. Bunkov

2015-01-01

Full Text Available Investigation of paired organs, testicles in particular, in the antenatal period as compared to congenital cryptorchidism in the context of interrelationship can objectively approach the consideration of the whole set of physiological and pathological processes in them, by taking into account histophysiological identity. The paper gives the results of micromorphometric examinations of the units of a communication system (cellular populations and the areas of parenchymatous and stromal structures (intertubular connective tissue, convoluted seminiferous tubules, and spermatogenic epithelium in two groups: 1 34 antenatal (ANT fetuses at 20–41 weeks' gestation and 2 46 children with congenital unilateral cryptorchidism (CR, in whom testis tissue biopsy specimens were examined at the age of 1 to 14 years. Determination of the similarity of micromorphometric structures (the number of cellular population in the intertubular connective tissue, convoluted seminiferous tubules, and the areas of intertubular connective tissue, spermatogenic epithelium, and capillary lumens was analyzed to discover an identity in the testes tissues of the ANT fetuses versus the children with congenital unilateral CR, by considering the position and site of testicles. The findings indicate that there are synchronous changes of individual similar structures between the right and left testicle during its natural descent into the scrotum in the ANT fetuses and in the patients with congenital CR, which is suggestive of the symmetry and relationship between the contralateral sex glands in different ontogenetic groups. This may testify that there are similar processes occurring between the testis tissues in the children with congenital CR and in the ANT fetuses. The findings may become a ground for further consideration of congenital CR in the context of not only the micromorphometry, but also functional activity of tests tissue structures when comparatively analyzing these

Principles of fluid-structure interaction

International Nuclear Information System (INIS)

Schumann, U.; Kernforschungszentrum Karlsruhe G.m.b.H.

1981-01-01

Fluid-structure interaction (FSI) is an important physical phenomenon which has attracted significant attention in nuclear reactor safety analysis. Here, simple explanations of the principle effects of FSI are given and illustrated by reference to numerical and experimental results. First, a very simple fluid-structure model is introduced which consists of a spring supported piston closing a fluid filled rigid pipe. The motion of the piston and the fluid is approximately described by one degree of freedom, respectively. Depending on the load frequency and material parameters one finds that the coupled system is characterized by virtual masses and stiffnesses or by the inverse properties which are termed virtual fluidities and compressibilities. Thus the two parts interact as if they are connected in series or in parallel. The two eigenfrequencies of the coupled system enclose the eigenfrequencies of the individual fluid and structure parts. Second, the great importance of Hamilton's principle for derivation of the coupled equations of motion is emphasized. From this principle upper and lower bounds for the effective density of a heterogeneous fluid-solid mixture are deduced. Continuum models for such mixtures contain a virtual density tensor. Finally, we discuss FSI for the case of a loss-of-coolant accident (LOCA) in a pressurized water reactor (PWR) in the first (subcooled) blowdown period. Here, the fluid imposes pressure loadings on internal structures like the core barrel and the motion of these structures influences the fluid motion. Recent experimental results obtained at the HDR are compared with numerical predictions of the FLUX 2-code. The fair agreement confirms that we have well understood the principal effects of FSI. (orig.) [de

Tissue specificity of the hormonal response in sex accessory tissues is associated with nuclear matrix protein patterns.

Science.gov (United States)

Getzenberg, R H; Coffey, D S

1990-09-01

The DNA of interphase nuclei have very specific three-dimensional organizations that are different in different cell types, and it is possible that this varying DNA organization is responsible for the tissue specificity of gene expression. The nuclear matrix organizes the three-dimensional structure of the DNA and is believed to be involved in the control of gene expression. This study compares the nuclear structural proteins between two sex accessory tissues in the same animal responding to the same androgen stimulation by the differential expression of major tissue-specific secretory proteins. We demonstrate here that the nuclear matrix is tissue specific in the rat ventral prostate and seminal vesicle, and undergoes characteristic alterations in its protein composition upon androgen withdrawal. Three types of nuclear matrix proteins were observed: 1) nuclear matrix proteins that are different and tissue specific in the rat ventral prostate and seminal vesicle, 2) a set of nuclear matrix proteins that either appear or disappear upon androgen withdrawal, and 3) a set of proteins that are common to both the ventral prostate and seminal vesicle and do not change with the hormonal state of the animal. Since the nuclear matrix is known to bind androgen receptors in a tissue- and steroid-specific manner, we propose that the tissue specificity of the nuclear matrix arranges the DNA in a unique conformation, which may be involved in the specific interaction of transcription factors with DNA sequences, resulting in tissue-specific patterns of secretory protein expression.

Pedagogical Interaction in High School, the Structural and Functional Model of Pedagogical Interaction

Science.gov (United States)

Semenova, Larissa A.; Kazantseva, Anastassiya I.; Sergeyeva, Valeriya V.; Raklova, Yekaterina M.; Baiseitova, Zhanar B.

2016-01-01

The study covers the problems of pedagogical technologies and their experimental implementation in the learning process. The theoretical aspects of the "student-teacher" interaction are investigated. A structural and functional model of pedagogical interaction is offered, which determines the conditions for improving pedagogical…

Effects of non-structural components and soil-structure interaction on the seismic response of framed structures

Science.gov (United States)

Ditommaso, Rocco; Auletta, Gianluca; Iacovino, Chiara; Nigro, Antonella; Carlo Ponzo, Felice

2017-04-01

In this paper, several nonlinear numerical models of reinforced concrete framed structures have been defined in order to evaluate the effects of non-structural elements and soil-structure interaction on the elastic dynamic behaviour of buildings. In the last few years, many and various studies have highlighted the significant effects derived from the interaction between structural and non-structural components on the main dynamic characteristics of a building. Usually, structural and non-structural elements act together, adding both masses and stiffness. The presence of infill panels is generally neglected in the design process of structural elements, although these elements can significantly increase the lateral stiffness of a structure leading to a modification in the dynamic properties. Particularly, at the Damage Limit State (where an elastic behaviour is expected), soil-structure interaction effects and non-structural elements may further affect the elastic natural period of buildings, changing the spectral accelerations compared with those provided by seismic codes in case of static analyses. In this work, a parametric study has been performed in order to evaluate the elastic fundamental period of vibration of buildings as a function of structural morphology (height, plan area, ratio between plan dimensions), infills presence and distribution and soil characteristics. Acknowledgements This study was partially funded by the Italian Department of Civil Protection within the project DPC-RELUIS 2016 - RS4 ''Seismic observatory of structures and health monitoring'' and by the "Centre of Integrated Geomorphology for the Mediterranean Area - CGIAM" within the Framework Agreement with the University of Basilicata "Study, Research and Experimentation in the Field of Analysis and Monitoring of Seismic Vulnerability of Strategic and Relevant Buildings for the purposes of Civil Protection and Development of Innovative Strategies of Seismic Reinforcement".

Prediction of protein–protein interactions: unifying evolution and structure at protein interfaces

International Nuclear Information System (INIS)

Tuncbag, Nurcan; Gursoy, Attila; Keskin, Ozlem

2011-01-01

The vast majority of the chores in the living cell involve protein–protein interactions. Providing details of protein interactions at the residue level and incorporating them into protein interaction networks are crucial toward the elucidation of a dynamic picture of cells. Despite the rapid increase in the number of structurally known protein complexes, we are still far away from a complete network. Given experimental limitations, computational modeling of protein interactions is a prerequisite to proceed on the way to complete structural networks. In this work, we focus on the question 'how do proteins interact?' rather than 'which proteins interact?' and we review structure-based protein–protein interaction prediction approaches. As a sample approach for modeling protein interactions, PRISM is detailed which combines structural similarity and evolutionary conservation in protein interfaces to infer structures of complexes in the protein interaction network. This will ultimately help us to understand the role of protein interfaces in predicting bound conformations

GPU-accelerated FDTD modeling of radio-frequency field-tissue interactions in high-field MRI.

Science.gov (United States)

Chi, Jieru; Liu, Feng; Weber, Ewald; Li, Yu; Crozier, Stuart

2011-06-01

The analysis of high-field RF field-tissue interactions requires high-performance finite-difference time-domain (FDTD) computing. Conventional CPU-based FDTD calculations offer limited computing performance in a PC environment. This study presents a graphics processing unit (GPU)-based parallel-computing framework, producing substantially boosted computing efficiency (with a two-order speedup factor) at a PC-level cost. Specific details of implementing the FDTD method on a GPU architecture have been presented and the new computational strategy has been successfully applied to the design of a novel 8-element transceive RF coil system at 9.4 T. Facilitated by the powerful GPU-FDTD computing, the new RF coil array offers optimized fields (averaging 25% improvement in sensitivity, and 20% reduction in loop coupling compared with conventional array structures of the same size) for small animal imaging with a robust RF configuration. The GPU-enabled acceleration paves the way for FDTD to be applied for both detailed forward modeling and inverse design of MRI coils, which were previously impractical.

Articular cartilage: from formation to tissue engineering.

Science.gov (United States)

Camarero-Espinosa, Sandra; Rothen-Rutishauser, Barbara; Foster, E Johan; Weder, Christoph

2016-05-26

Hyaline cartilage is the nonlinear, inhomogeneous, anisotropic, poro-viscoelastic connective tissue that serves as friction-reducing and load-bearing cushion in synovial joints and is vital for mammalian skeletal movements. Due to its avascular nature, low cell density, low proliferative activity and the tendency of chondrocytes to de-differentiate, cartilage cannot regenerate after injury, wear and tear, or degeneration through common diseases such as osteoarthritis. Therefore severe damage usually requires surgical intervention. Current clinical strategies to generate new tissue include debridement, microfracture, autologous chondrocyte transplantation, and mosaicplasty. While articular cartilage was predicted to be one of the first tissues to be successfully engineered, it proved to be challenging to reproduce the complex architecture and biomechanical properties of the native tissue. Despite significant research efforts, only a limited number of studies have evolved up to the clinical trial stage. This review article summarizes the current state of cartilage tissue engineering in the context of relevant biological aspects, such as the formation and growth of hyaline cartilage, its composition, structure and biomechanical properties. Special attention is given to materials development, scaffold designs, fabrication methods, and template-cell interactions, which are of great importance to the structure and functionality of the engineered tissue.

Sloshing, fluid-structure interaction and structural response due to shock and impact loads 1994. PVP-Vol. 272

International Nuclear Information System (INIS)

Ma, D.C.; Shin, Y.S.; Brochard, D.; Fujita, K.

1994-01-01

This volume is comprised of papers presented in two symposia at the 1994 ASME Pressure Vessels and Piping Conference. These sessions, sponsored by the Fluid-Structure Interaction and Seismic Engineering Technical Committees, provided a forum for the discussion of recent advances in sloshing, fluid-structure interaction, and structural dynamics produced by high energy excitations. The papers presented at the four technical sessions on Sloshing and Fluid-Structure Interaction represent a broad spectrum of fluid-structure systems: sloshing, fluid-structure interaction, and dynamic and seismic response of various fluid-structure systems such as reactor components, liquid storage tanks, submerged structures and piping systems, etc. The paper presented at the session on Structural Dynamics Produced by High-Energy Excitations cover underwater explosion effects on submerged structures, bubble loading phenomena, finite element mesh refinements on failure predictions, penetration and impact problems, and dynamic design of blast containment vessels. Also included are numerical analysis, design, and testing to understand difficult transient response phenomena. Separate abstracts were prepared for 24 papers in this volume

Dynamic Analysis of Partially Embedded Structures Considering Soil-Structure Interaction in Time Domain

Directory of Open Access Journals (Sweden)

Sanaz Mahmoudpour

2011-01-01

Full Text Available Analysis and design of structures subjected to arbitrary dynamic loadings especially earthquakes have been studied during past decades. In practice, the effects of soil-structure interaction on the dynamic response of structures are usually neglected. In this study, the effect of soil-structure interaction on the dynamic response of structures has been examined. The substructure method using dynamic stiffness of soil is used to analyze soil-structure system. A coupled model based on finite element method and scaled boundary finite element method is applied. Finite element method is used to analyze the structure, and scaled boundary finite element method is applied in the analysis of unbounded soil region. Due to analytical solution in the radial direction, the radiation condition is satisfied exactly. The material behavior of soil and structure is assumed to be linear. The soil region is considered as a homogeneous half-space. The analysis is performed in time domain. A computer program is prepared to analyze the soil-structure system. Comparing the results with those in literature shows the exactness and competency of the proposed method.

Laser-tissue interaction in tattoo removal by q-switched lasers.

Science.gov (United States)

Barua, Shyamanta

2015-01-01

Q-switched (QS) lasers are widely considered the gold standard for tattoo removal, with excellent clinical results, impressive predictability, and a good safety profile. The generation of giant pulses by the method of Q-switching is responsible for the unique laser-tissue interaction that is seen in tattoo removal by QS lasers. The QS lasers work by impaction and dissolution of the tattoo pigments. Mechanical fragmentation of the tattoo pigments encased in intracellular lamellated organelles followed by their phagocytosis by macrophages is thought to be the major event in the clearance of pigments by QS lasers. A few novel techniques have been tried in recent times to hasten the clearance of tattoo pigments.

Engineering characterization of ground motion. Task II: Soil structure interaction effects on structural response

Energy Technology Data Exchange (ETDEWEB)

Luco, J E; Wong, H L [Structural and Earthquake Engineering Consultants, Inc., Sierra Madre, CA (United States); Chang, C -Y; Power, M S; Idriss, I M [Woodward-Clyde Consultants, Walnut Creek, CA (United States)

1986-08-01

This report presents the results of part of a two-task study on the engineering characterization of earthquake ground motion for nuclear power plant design. The overall objective of this research program sponsored by the U.S. Nuclear Regulatory Commission (USNRC) is to develop recommendations for methods for selecting design response spectra or acceleration time histories to be used to characterize motion at the foundation level of nuclear power plants. Task I of the study, which is presented in Vol. 1 of NUREG/CR-3805, developed a basis for selecting design response spectra taking into account the characteristics of free-field ground motion found to be significant in causing structural damage. Task II incorporates additional considerations of effects of spatial variations of ground motions and soil-structure interaction on foundation motions and structural response. The results of Task II are presented in Vols. 2 through of NUREG/CR-3805 as follows: Vol. 2 effects of ground motion characteristics on structural response considering localized structural nonlinearities and soil-structure interaction effects; Vol. 3 observational data on spatial variations of earthquake ground motions; Vol. 4 soil-structure interaction effects on structural response; and Vol. 5, summary based on Tasks I and II studies. This report presents the results of the Vol. 4 studies.

Near-field electromagnetic holography for high-resolution analysis of network interactions in neuronal tissue.

Science.gov (United States)

Kjeldsen, Henrik D; Kaiser, Marcus; Whittington, Miles A

2015-09-30

Brain function is dependent upon the concerted, dynamical interactions between a great many neurons distributed over many cortical subregions. Current methods of quantifying such interactions are limited by consideration only of single direct or indirect measures of a subsample of all neuronal population activity. Here we present a new derivation of the electromagnetic analogy to near-field acoustic holography allowing high-resolution, vectored estimates of interactions between sources of electromagnetic activity that significantly improves this situation. In vitro voltage potential recordings were used to estimate pseudo-electromagnetic energy flow vector fields, current and energy source densities and energy dissipation in reconstruction planes at depth into the neural tissue parallel to the recording plane of the microelectrode array. The properties of the reconstructed near-field estimate allowed both the utilization of super-resolution techniques to increase the imaging resolution beyond that of the microelectrode array, and facilitated a novel approach to estimating causal relationships between activity in neocortical subregions. The holographic nature of the reconstruction method allowed significantly better estimation of the fine spatiotemporal detail of neuronal population activity, compared with interpolation alone, beyond the spatial resolution of the electrode arrays used. Pseudo-energy flow vector mapping was possible with high temporal precision, allowing a near-realtime estimate of causal interaction dynamics. Basic near-field electromagnetic holography provides a powerful means to increase spatial resolution from electrode array data with careful choice of spatial filters and distance to reconstruction plane. More detailed approaches may provide the ability to volumetrically reconstruct activity patterns on neuronal tissue, but the ability to extract vectored data with the method presented already permits the study of dynamic causal interactions

Some aspects of the interaction between systems- and structural reliability

International Nuclear Information System (INIS)

Schueller, G.K.; Schmitt, W.

1979-01-01

The purpose of this paper is to study the interaction between systems- and structural reliability analysis with reference to the design of structural components of LWR. Presently the evaluation of systems reliability is carried out apart from structural reliability analysis. Moreover, two basically different methodologies are used for analysis. While in systems analysis the simplified binary approach is still generally accepted, in structural reliability one has to resort to more sophisticated procedures to obtain realistic results. The interactive effect may be illustrated as follows: For example, the integrity of the primary circuit interacts with the integrity of the containment structure. This means that the probability of occurrence of the pipe rupture which may cause a LOCA and consequently leads to a build-up of temperature and pressure within the containment affects directly its structural reliability. The piping system, particularly the primary piping, in turn interacts with the protective system, which is part of the safety system. This piping structure is also subjected to various operational loading conditions. In a numerical example dealing with leakage probabilities of pipes it is shown how methods of structural reliability may be used to gain more insight in the estimation of failure rates of system components. (orig.)

Soil Structure Interaction Effect on High Rise and Low Rise Buildings

OpenAIRE

Divya Pathak; PAresh H. SHAH

2000-01-01

Effect of supporting soil on the response of structure has been analyzed in the present study. A low rise (G+ 5 storey) and a high rise (G+12 storey) building has been taken for the analysis. For both type of buildings, the response of building with and without consideration of soil structure interaction effect has been compared.Without interaction case is the case in which ends of the structure are assumed to be fixed while in interaction case, structure is assumed to be...

Density functional study of molecular interactions in secondary structures of proteins.

Science.gov (United States)

Takano, Yu; Kusaka, Ayumi; Nakamura, Haruki

2016-01-01

Proteins play diverse and vital roles in biology, which are dominated by their three-dimensional structures. The three-dimensional structure of a protein determines its functions and chemical properties. Protein secondary structures, including α-helices and β-sheets, are key components of the protein architecture. Molecular interactions, in particular hydrogen bonds, play significant roles in the formation of protein secondary structures. Precise and quantitative estimations of these interactions are required to understand the principles underlying the formation of three-dimensional protein structures. In the present study, we have investigated the molecular interactions in α-helices and β-sheets, using ab initio wave function-based methods, the Hartree-Fock method (HF) and the second-order Møller-Plesset perturbation theory (MP2), density functional theory, and molecular mechanics. The characteristic interactions essential for forming the secondary structures are discussed quantitatively.

Universality Classes of Interaction Structures for NK Fitness Landscapes

Science.gov (United States)

Hwang, Sungmin; Schmiegelt, Benjamin; Ferretti, Luca; Krug, Joachim

2018-02-01

Kauffman's NK-model is a paradigmatic example of a class of stochastic models of genotypic fitness landscapes that aim to capture generic features of epistatic interactions in multilocus systems. Genotypes are represented as sequences of L binary loci. The fitness assigned to a genotype is a sum of contributions, each of which is a random function defined on a subset of k ≤ L loci. These subsets or neighborhoods determine the genetic interactions of the model. Whereas earlier work on the NK model suggested that most of its properties are robust with regard to the choice of neighborhoods, recent work has revealed an important and sometimes counter-intuitive influence of the interaction structure on the properties of NK fitness landscapes. Here we review these developments and present new results concerning the number of local fitness maxima and the statistics of selectively accessible (that is, fitness-monotonic) mutational pathways. In particular, we develop a unified framework for computing the exponential growth rate of the expected number of local fitness maxima as a function of L, and identify two different universality classes of interaction structures that display different asymptotics of this quantity for large k. Moreover, we show that the probability that the fitness landscape can be traversed along an accessible path decreases exponentially in L for a large class of interaction structures that we characterize as locally bounded. Finally, we discuss the impact of the NK interaction structures on the dynamics of evolution using adaptive walk models.

TECHNICAL NOTES SEISMIC SOIL-STRUCTURE INTERACTION ...

African Journals Online (AJOL)

dell

SEISMIC SOIL-STRUCTURE INTERACTION AS A POTENTIAL TOOL FOR. ECONOMICAL ... ground motion at the interface with the rock. The soil can .... half space have an elastic modulus of E and a mass density of ρ . .... The trial solution to.

Modeling Protein Structures in Feed and Seed Tissues Using Novel Synchrotron-Based Analytical Technique

International Nuclear Information System (INIS)

Yu, P.

2008-01-01

Traditional 'wet' chemical analyses usually looks for a specific known component (such as protein) through homogenization and separation of the components of interest from the complex tissue matrix. Traditional 'wet' chemical analyses rely heavily on the use of harsh chemicals and derivatization, therefore altering the native feed protein structures and possibly generating artifacts. The objective of this study was to introduce a novel and non-destructive method to estimate protein structures in feed and seeds within intact tissues using advanced synchrotron-based infrared microspectroscopy (SFTIRM). The experiments were performed at the National Synchrotron Light Source in Brookhaven National Laboratory (US Dept. of Energy, NY). The results show that with synchrotron-based SFTIRM, we are able to localize relatively 'pure' protein without destructions of the feed and seed tissues and qualify protein internal structures in terms of the proportions and ratios of a-helix, β-sheet, random coil and β-turns on a relative basis using multi-peak modeling procedures. These protein structure profile (a-helix, β-sheet, etc.) may influence protein quality and availability in animals. Several examples of feed and seeds were provided. The implications of this study are that we can use this new method to compare internal protein structures between feeds and between seed verities. We can also use this method to detect heat-induced the structural changes of protein in feeds.

Neuron matters: electric activation of neuronal tissue is dependent on the interaction between the neuron and the electric field.

Science.gov (United States)

Ye, Hui; Steiger, Amanda

2015-08-12

In laboratory research and clinical practice, externally-applied electric fields have been widely used to control neuronal activity. It is generally accepted that neuronal excitability is controlled by electric current that depolarizes or hyperpolarizes the excitable cell membrane. What determines the amount of polarization? Research on the mechanisms of electric stimulation focus on the optimal control of the field properties (frequency, amplitude, and direction of the electric currents) to improve stimulation outcomes. Emerging evidence from modeling and experimental studies support the existence of interactions between the targeted neurons and the externally-applied electric fields. With cell-field interaction, we suggest a two-way process. When a neuron is positioned inside an electric field, the electric field will induce a change in the resting membrane potential by superimposing an electrically-induced transmembrane potential (ITP). At the same time, the electric field can be perturbed and re-distributed by the cell. This cell-field interaction may play a significant role in the overall effects of stimulation. The redistributed field can cause secondary effects to neighboring cells by altering their geometrical pattern and amount of membrane polarization. Neurons excited by the externally-applied electric field can also affect neighboring cells by ephaptic interaction. Both aspects of the cell-field interaction depend on the biophysical properties of the neuronal tissue, including geometric (i.e., size, shape, orientation to the field) and electric (i.e., conductivity and dielectricity) attributes of the cells. The biophysical basis of the cell-field interaction can be explained by the electromagnetism theory. Further experimental and simulation studies on electric stimulation of neuronal tissue should consider the prospect of a cell-field interaction, and a better understanding of tissue inhomogeneity and anisotropy is needed to fully appreciate the neural

Hyaluronan - a functional and structural sweet spot in the tissue microenvironment

Directory of Open Access Journals (Sweden)

James eMonslow

2015-05-01

Full Text Available Transition from homeostatic to reactive matrix remodeling is a fundamental adaptive tissue response to injury, inflammatory disease, fibrosis and cancer. Alterations in architecture, physical properties and matrix composition result in changes in biomechanical and biochemical cellular signaling. The dynamics of pericellular and extracellular matrices, including matrix protein, proteoglycan and glycosaminoglycan modification are continually emerging as essential regulatory mechanisms underlying cellular and tissue function. Nevertheless, the impact of matrix organization on inflammation and immunity in particular, and the consequent effects on tissue healing and disease outcome are arguably under-studied aspects of adaptive stress responses. Herein, we review how the predominant glycosaminoglycan hyaluronan (HA contributes to the structure and function of the tissue microenvironment. Specifically, we examine the evidence of HA degradation and the generation of biologically-active smaller HA fragments in pathological settings in vivo. We discuss how HA fragments versus nascent HA via alternate receptor-mediated signaling influence inflammatory cell recruitment and differentiation, resident cell activation, as well as tumor growth, survival and metastasis. Finally, we discuss how HA fragmentation impacts restoration of normal tissue function and pathological outcomes in disease.

An experimental study on soil-structure interaction effects

International Nuclear Information System (INIS)

Mita, Akira; Kumagai, Shigeru

1989-01-01

The soil-structure interaction effects play an important role in the earthquake response of large scale structures such as nuclear power plants. Recent decades, many experimental and analytical studies have been conducted. Even though sophisticated analytical tools are ready to use, complicated soil-structure interaction problems such as those with a complex geometry can not be solved yet. For such problems a laboratory experiment is a powerful alternative. In the laboratory experiment, a device to absorb the reflected waves is always necessary to be attached on the boundaries of the soil model to simulate the semi-infiniteness of the actual ground. But unfortunately absorbing devices currently available are far from satisfactory. In this paper, a new experimental method is employed for soil-structure interaction problems to simulate the semi-infiniteness of the actual ground. The present method utilizes the characteristics of transient response to an impulse load so that no special treatment on the boundaries of the soil model is required. This technique is applicable to a linear elastic system whose impulse response decreases to a small enough value before observing the reflected waves. (author)

Fluid/structure interaction in BERDYNE (Level 4)

International Nuclear Information System (INIS)

Fox, M.J.H.

1988-02-01

A fluid-structure interaction capability has been developed for Level 4 of the finite element dynamics code BERDYNE, as part of the BERSAFE structural analysis system. This permits analysis of small amplitude free or forced vibration of systems comprising elastic structural components and inviscid volumes of possibly compressible fluid. Free fluid surfaces under the influence of gravity may be present. The formulation chosen uses the rigid walled fluid modes, calculated in a preliminary stage, as a basis for description of the coupled system, providing symmetric system matrices for which efficient solution procedures are available. The inclusion of the fluid modal variables within the system matrices is carried out through the use of the BERDYNE 'substructuring' feature, which allows the inclusion of very general 'super-elements' among the normal structural elements. The program also has a seismic analysis capability, used for the analysis of fluid-structure systems subjected to a specified support acceleration time history. In this case analysis is carried out in terms of relative structural motions, but absolute fluid pressures. Application of the BERDYNE fluid/structure interaction capability to some simple test cases produced results in good agreement with results obtained by analytic or independent numerical techniques. Full instructions on the use of the facility will be included in the BERDYNE Level 4 documentation. Interim documentation for the pre-release version is available from the author. (author)

PCNA Structure and Interactions with Partner Proteins

KAUST Repository

Oke, Muse; Zaher, Manal S.; Hamdan, Samir

2018-01-01

Proliferating cell nuclear antigen (PCNA) consists of three identical monomers that topologically encircle double-stranded DNA. PCNA stimulates the processivity of DNA polymerase δ and, to a less extent, the intrinsically highly processive DNA polymerase ε. It also functions as a platform that recruits and coordinates the activities of a large number of DNA processing proteins. Emerging structural and biochemical studies suggest that the nature of PCNA-partner proteins interactions is complex. A hydrophobic groove at the front side of PCNA serves as a primary docking site for the consensus PIP box motifs present in many PCNA-binding partners. Sequences that immediately flank the PIP box motif or regions that are distant from it could also interact with the hydrophobic groove and other regions of PCNA. Posttranslational modifications on the backside of PCNA could add another dimension to its interaction with partner proteins. An encounter of PCNA with different DNA structures might also be involved in coordinating its interactions. Finally, the ability of PCNA to bind up to three proteins while topologically linked to DNA suggests that it would be a versatile toolbox in many different DNA processing reactions.

PCNA Structure and Interactions with Partner Proteins

KAUST Repository

Oke, Muse

2018-01-29

Proliferating cell nuclear antigen (PCNA) consists of three identical monomers that topologically encircle double-stranded DNA. PCNA stimulates the processivity of DNA polymerase δ and, to a less extent, the intrinsically highly processive DNA polymerase ε. It also functions as a platform that recruits and coordinates the activities of a large number of DNA processing proteins. Emerging structural and biochemical studies suggest that the nature of PCNA-partner proteins interactions is complex. A hydrophobic groove at the front side of PCNA serves as a primary docking site for the consensus PIP box motifs present in many PCNA-binding partners. Sequences that immediately flank the PIP box motif or regions that are distant from it could also interact with the hydrophobic groove and other regions of PCNA. Posttranslational modifications on the backside of PCNA could add another dimension to its interaction with partner proteins. An encounter of PCNA with different DNA structures might also be involved in coordinating its interactions. Finally, the ability of PCNA to bind up to three proteins while topologically linked to DNA suggests that it would be a versatile toolbox in many different DNA processing reactions.

Soil-structure interaction effects on the reliability evaluation of reactor containments

International Nuclear Information System (INIS)

Pires, J.; Hwang, H.; Reich, M.

1986-01-01

The probability-based method for the seismic reliability assessment of nuclear structures, which has been developed at Brookhaven National Laboratory (BNL), is extended to include the effects of soil-structure interaction. A reinforced concrete containment building is analyzed in order to examine soil-structure interaction effects on: (1) structural fragilities; (2) floor response spectra statistics; and (3) correlation coefficients for total acceleration responses at specified structural locations

On some structure-turbulence interaction problems

Science.gov (United States)

Maekawa, S.; Lin, Y. K.

1976-01-01

The interactions between a turbulent flow structure; responding to its excitation were studied. The turbulence was typical of those associated with a boundary layer, having a cross-spectral density indicative of convection and statistical decay. A number of structural models were considered. Among the one-dimensional models were an unsupported infinite beam and a periodically supported infinite beam. The fuselage construction of an aircraft was then considered. For the two-dimensional case a simple membrane was used to illustrate the type of formulation applicable to most two-dimensional structures. Both the one-dimensional and two-dimensional structures studied were backed by a cavity filled with an initially quiescent fluid to simulate the acoustic environment when the structure forms one side of a cabin of a sea vessel or aircraft.

Highlighting the nuances behind interaction of picosecond pulses with human skin: Relating distinct laser-tissue interactions to their potential in cutaneous interventions

Science.gov (United States)

Uzunbajakava, Natallia E.; Varghese, Babu; Botchkareva, Natalia V.; Verhagen, Rieko; Vogel, Alfred

2018-02-01

In recent years, several commercial systems relying on picosecond pulses have been introduced into the field of cutaneous interventions. In parallel with this development, a somewhat distinct research prototype also operating in the picosecond regime was described in literature. Albeit both market-available products and the investigational device employ laser beams of nearly the same pulse duration and were reported to cause laser-induced optical breakdown (LIOB), they are different in terms of wavelength, applied fluence, laser beam quality, optical architecture and related focusing optics, resulting in different histomorphological features (such as e.g. lesion size, location, expression of collagen). Understanding the differences between these systems in relation to implications for clinical results raises a need in highlighting the nuances behind interaction of picosecond pulses with biological tissue. To achieve this, we accentuate the interplay of irradiance levels of picosecond pulses in W/cm2 , absorption properties of a target tissue at a wavelength of a light source and resulting interaction mechanisms with biological object. We also relate these nuances to potential consequences for cutaneous interventions.

Fluid structure interaction in tube bundles

International Nuclear Information System (INIS)

Brochard, D.; Jedrzejewski, F.; Gibert, R.J.

1995-01-01

A lot of industrial components contain tube bundles immersed in a fluid. The mechanical analysis of such systems requires the study of the fluid structure interaction in the tube bundle. Simplified methods, based on homogenization methods, have been developed to analyse such phenomenon and have been validated through experimental results. Generally, these methods consider only the fluid motion in a plan normal to the bundle axis. This paper will analyse, in a first part, the fluid structure interaction in a tube bundle through a 2D finite element model representing the bundle cross section. The influence of various parameters like the bundle size, and the bundle confinement will be studied. These results will be then compared with results from homogenization methods. Finally, the influence of the 3D fluid motion will be investigated, in using simplified methods. (authors). 11 refs., 12 figs., 2 tabs

Process Machine Interactions Predicition and Manipulation of Interactions between Manufacturing Processes and Machine Tool Structures

CERN Document Server

Hollmann, Ferdinand

2013-01-01

This contributed volume collects the scientific results of the DFG Priority Program 1180 Prediction and Manipulation of Interactions between Structure and Process. The research program has been conducted during the years 2005 and 2012, whereas the primary goal was the analysis of the interactions between processes and structures in modern production facilities. This book presents the findings of the 20 interdisciplinary subprojects, focusing on different manufacturing processes such as high performance milling, tool grinding or metal forming. It contains experimental investigations as well as mathematical modeling of production processes and machine interactions. New experimental advancements and novel simulation approaches are also included.

A review of experimental soil-structure interaction damping

International Nuclear Information System (INIS)

Tsai, N.C.

1981-01-01

In soil-structure interaction analysis, the foundation soil is usually represented by impedance springs and dampers. The impedance damping includes the effect of both the material damping and the radiation damping. Because the impedance theory normally assumes a rigid structural base and an elastic bond between the soil and structure, it is generally held that the radiation damping has been overestimated by the theory. There are some published information on the dynamic tests of footings and structures that allow direct or indirect assessments of the validity of the analytical radiation damping. An overview of such information is presented here. Based on these limited test data, it is concluded that for horizontal soil-structure interaction analysis the analytical radiation damping alone is sufficient to represent the combined material and radiation damping in the field. On the other hand, for vertical analysis it appears that the theory may have overestimated the radiation damping and certain reduction is recommended. (orig.)

Advanced Seismic Fragility Modeling using Nonlinear Soil-Structure Interaction Analysis

Energy Technology Data Exchange (ETDEWEB)

Bolisetti, Chandu [Idaho National Lab. (INL), Idaho Falls, ID (United States); Coleman, Justin [Idaho National Lab. (INL), Idaho Falls, ID (United States); Talaat, Mohamed [Simpson-Gupertz & Heger, Waltham, MA (United States); Hashimoto, Philip [Simpson-Gupertz & Heger, Waltham, MA (United States)

2015-09-01

The goal of this effort is to compare the seismic fragilities of a nuclear power plant system obtained by a traditional seismic probabilistic risk assessment (SPRA) and an advanced SPRA that utilizes Nonlinear Soil-Structure Interaction (NLSSI) analysis. Soil-structure interaction (SSI) response analysis for a traditional SPRA involves the linear analysis, which ignores geometric nonlinearities (i.e., soil and structure are glued together and the soil material undergoes tension when the structure uplifts). The NLSSI analysis will consider geometric nonlinearities.

Development of soil-structure interaction analysis method (II) - Volume 1

International Nuclear Information System (INIS)

Chang, S. P.; Ko, H. M.; Park, H. K. and others

1994-02-01

This project includes following six items : free field analysis for the determination of site input motions, impedance analysis which simplifies the effects of soil-structure interaction by using lumped parameters, soil-structure interaction analysis including the material nonlinearity of soil depending on the level of strains, strong geometric nonlinearity due to the uplifting of the base, seismic analysis of underground structure such as varied pipes, seismic analysis of liquid storage tanks. Each item contains following contents respectively : state-of-the-art review on each item and data base construction on the past researches, theoretical review on the technology of soil-structure interaction analysis, proposing preferable technology and estimating the domestic applicability, proposing guidelines for evaluation of safety and analysis scheme

Influence of soil-structure interaction on floor response spectra

International Nuclear Information System (INIS)

Costantino, C.J.; Miller, C.A.; Curreri, J.R.

1985-01-01

A study was undertaken to investigate the influence of soil-structure interaction on floor response spectra developed in typical nuclear power plant structures. A horizontal earthquake time history, whose spectra envelops the Regulatory Guide 1.60 criteria and is scaled to a log peak acceleration, was used as input to structural models. Two different structural stick models were used, representing typical BWR and PWR facilities. By varying the structural and soil stiffness parameters, a wide range of system behaviors were investigated. Floor response spectra, required to assess equipment qualification, were of primary interest. It was found from a variation of parameter study that the interaction soil parameters, particularly radiation damping, greatly affect the nature of the calculated responses. 2 refs., 2 figs., 2 tabs

Influence of soil-structure interaction on floor response spectra

International Nuclear Information System (INIS)

Costantino, C.J.; Miller, C.A.; Curreri, J.R.

1985-01-01

A study was undertaken to investigate the influence of soil-structure interaction on floor response spectra developed in typical nuclear power plant structures. A horizontal earthquake time history, whose spectra envelops the Reg. Guide 1.60 criteria and is scaled to a 1 g peak acceleration, was used as input to structural models. Two different structural stick models were used, representing typical BWR and PWR facilities. By varying the structural and soil stiffness parameters, a wide range of system behaviors were investigated. Floor response spectra, required to assess equipment qualification, were of primary interest. It was found from a variation of parameter study that the interaction soil parameters, particularly radiation damping, greatly affect the nature of the calculated responses. (orig.)

Proton-neutron interaction and nuclear structure

International Nuclear Information System (INIS)

Casten, R.F.

1986-01-01

The pervasive role of the proton-neutron interaction in nuclear structure is discussed. Particular emphasis is given to its influence on the onset of collectivity and deformation, on intruder states, and on the evolution of subshell structure. The N/sub p/N/sub n/ scheme is outlined and some applications of it to collective model calculations and to nuclei far off stability are described. The concept of N/sub p/N/sub n/ multiplets is introduced. 32 refs., 20 figs

Quantitative image analysis reveals distinct structural transitions during aging in Caenorhabditis elegans tissues.

Directory of Open Access Journals (Sweden)

Josiah Johnston

2008-07-01

Full Text Available Aging is associated with functional and structural declines in many body systems, even in the absence of underlying disease. In particular, skeletal muscles experience severe declines during aging, a phenomenon termed sarcopenia. Despite the high incidence and severity of sarcopenia, little is known about contributing factors and development. Many studies focus on functional aspects of aging-related tissue decline, while structural details remain understudied. Traditional approaches for quantifying structural changes have assessed individual markers at discrete intervals. Such approaches are inadequate for the complex changes associated with aging. An alternative is to consider changes in overall morphology rather than in specific markers. We have used this approach to quantitatively track tissue architecture during adulthood and aging in the C. elegans pharynx, the neuromuscular feeding organ. Using pattern recognition to analyze aged-grouped pharynx images, we identified discrete step-wise transitions between distinct morphologies. The morphology state transitions were maintained in mutants with pharynx neurotransmission defects, although the pace of the transitions was altered. Longitudinal measurements of pharynx function identified a predictive relationship between mid-life pharynx morphology and function at later ages. These studies demonstrate for the first time that adult tissues undergo distinct structural transitions reflecting postdevelopmental events. The processes that underlie these architectural changes may contribute to increased disease risk during aging, and may be targets for factors that alter the aging rate. This work further demonstrates that pattern analysis of an image series offers a novel and generally accessible approach for quantifying morphological changes and identifying structural biomarkers.

Quantitative image analysis reveals distinct structural transitions during aging in Caenorhabditis elegans tissues.

Science.gov (United States)

Johnston, Josiah; Iser, Wendy B; Chow, David K; Goldberg, Ilya G; Wolkow, Catherine A

2008-07-30

Aging is associated with functional and structural declines in many body systems, even in the absence of underlying disease. In particular, skeletal muscles experience severe declines during aging, a phenomenon termed sarcopenia. Despite the high incidence and severity of sarcopenia, little is known about contributing factors and development. Many studies focus on functional aspects of aging-related tissue decline, while structural details remain understudied. Traditional approaches for quantifying structural changes have assessed individual markers at discrete intervals. Such approaches are inadequate for the complex changes associated with aging. An alternative is to consider changes in overall morphology rather than in specific markers. We have used this approach to quantitatively track tissue architecture during adulthood and aging in the C. elegans pharynx, the neuromuscular feeding organ. Using pattern recognition to analyze aged-grouped pharynx images, we identified discrete step-wise transitions between distinct morphologies. The morphology state transitions were maintained in mutants with pharynx neurotransmission defects, although the pace of the transitions was altered. Longitudinal measurements of pharynx function identified a predictive relationship between mid-life pharynx morphology and function at later ages. These studies demonstrate for the first time that adult tissues undergo distinct structural transitions reflecting postdevelopmental events. The processes that underlie these architectural changes may contribute to increased disease risk during aging, and may be targets for factors that alter the aging rate. This work further demonstrates that pattern analysis of an image series offers a novel and generally accessible approach for quantifying morphological changes and identifying structural biomarkers.

Articular soft tissue anatomy of the archosaur hip joint: Structural homology and functional implications.

Science.gov (United States)

Tsai, Henry P; Holliday, Casey M

2015-06-01

Archosaurs evolved a wide diversity of locomotor postures, body sizes, and hip joint morphologies. The two extant archosaurs clades (birds and crocodylians) possess highly divergent hip joint morphologies, and the homologies and functions of their articular soft tissues, such as ligaments, cartilage, and tendons, are poorly understood. Reconstructing joint anatomy and function of extinct vertebrates is critical to understanding their posture, locomotor behavior, ecology, and evolution. However, the lack of soft tissues in fossil taxa makes accurate inferences of joint function difficult. Here, we describe the soft tissue anatomies and their osteological correlates in the hip joint of archosaurs and their sauropsid outgroups, and infer structural homology across the extant taxa. A comparative sample of 35 species of birds, crocodylians, lepidosaurs, and turtles ranging from hatchling to skeletally mature adult were studied using dissection, imaging, and histology. Birds and crocodylians possess topologically and histologically consistent articular soft tissues in their hip joints. Epiphyseal cartilages, fibrocartilages, and ligaments leave consistent osteological correlates. The archosaur acetabulum possesses distinct labrum and antitrochanter structures on the supraacetabulum. The ligamentum capitis femoris consists of distinct pubic- and ischial attachments, and is homologous with the ventral capsular ligament of lepidosaurs. The proximal femur has a hyaline cartilage core attached to the metaphysis via a fibrocartilaginous sleeve. This study provides new insight into soft tissue structures and their osteological correlates (e.g., the antitrochanter, the fovea capitis, and the metaphyseal collar) in the archosaur hip joint. The topological arrangement of fibro- and hyaline cartilage may provide mechanical support for the chondroepiphysis. The osteological correlates identified here will inform systematic and functional analyses of archosaur hindlimb evolution and

Soil-structure interaction effects on containment fragilities and floor response spectra statistics

International Nuclear Information System (INIS)

Pires, J.; Reich, M.; Chokshi, N.C.

1987-01-01

The probability-based method for the reliability evaluation of nuclear structures developed at Brookhaven National Laboratory (BNL) is extended to include soil-structure interaction effects. A reinforced concrete containment is analyzed in order to investigate the soil-structure interaction effects on: structural fragilities; floor response spectra statistics and acceleration response correlations. To include the effect of soil flexibility on the reliability assessment the following two step approach is used. In the first step, the lumped parameter method for soil-structure interaction analysis is used together with a stick model representation of the structure in order to obtain the motions of the foundation plate. These motions, which include both translations and rotations of the foundation plate, are expressed in terms of the power-spectral density of the free-field ground excitation and the transfer function of the total acceleration response of the foundation. The second step involves a detailed finite element model of the structure subjected to the interaction motions computed from step one. Making use of the structural model and interaction motion the reliability analysis method yields the limit stat probabilities and fragility data for the structure

Nonelastic soil-structure interaction by BE- and FE-methods

International Nuclear Information System (INIS)

Hadjikov, L.; Dineva, P.; Rangelov, T.

1987-01-01

The main purpose of this paper is to study the soil-structure interaction for multilayered, nonlineary physically soil system with arbitrary geometric form of boundaries between the layers, accounting the topographic specifics on the free surface. The behaviour of the structure is described by the finite element method (FEM). For the description of the propagation of the seismic waves in the soil the boundary element method (BEM) is used. The numerical results for the behaviour of the soil-structure interaction for nuclear power plant on a real geological site are obtained. The influence of the nonelastic soil and structure properties and the influence of the topographic specifities of the geological region are investigated. (orig./HP)

Soil-structure interaction - an engineering evaluation

International Nuclear Information System (INIS)

Hadjian, A.H.

1976-01-01

The two methods of analysis for structure interaction, the impedance and the finite element methods, are reviewed with regard to their present capabilities to address the significant factors of the problem. The objective of the paper is to evaluate if an adequate engineering solution to the problem is provided by either approach. Questions related to the reduction of seismic motions with depth scattering of incident waves, the three-dimensionality of the real problem, soil damping, strain dependency of soil properties and the uncertainties associated with all of the above are discussed in sufficient detail. All conclusions made are based on referenced material. It appears that both methods as presently practised have not yet completely solved the problem, the impedance approach has come closer to addressing the more significant issues. Because of this finding, in addition to its simplicity and low cost, the impedance approach is the perfect engineering method for soil-structure interaction. (Auth.)

Fibrosis in connective tissue disease: the role of the myofibroblast and fibroblast-epithelial cell interactions

Science.gov (United States)

Krieg, Thomas; Abraham, David; Lafyatis, Robert

2007-01-01

Fibrosis, characterized by excessive extracellular matrix accumulation, is a common feature of many connective tissue diseases, notably scleroderma (systemic sclerosis). Experimental studies suggest that a complex network of intercellular interactions involving endothelial cells, epithelial cells, fibroblasts and immune cells, using an array of molecular mediators, drives the pathogenic events that lead to fibrosis. Transforming growth factor-β and endothelin-1, which are part of a cytokine hierarchy with connective tissue growth factor, are key mediators of fibrogenesis and are primarily responsible for the differentiation of fibroblasts toward a myofibroblast phenotype. The tight skin mouse (Tsk-1) model of cutaneous fibrosis suggests that numerous other genes may also be important. PMID:17767742

A multi-angular mass spectrometric view at cyclic nucleotide signaling proteins : Structure/function and protein interactions of cAMP- and cGMP-dependent protein kinase

NARCIS (Netherlands)

Scholten, A.

2006-01-01

The primary focus of this thesis is the two kinases PKA and PKG, cAMP and cGMP dependent protein kinase respectively. PKA and PKG are studied both at structure/function level as well as at the level of interaction with other proteins in tissue. Our primary methods are all based on mass spectrometry.

Analysis of fluid-structure interaction and structural respones of Chernobyl-4 reactor

International Nuclear Information System (INIS)

Wang, C.Y.; Pizzica, P.A.; Gvildys, J.; Spencer, B.W.

1989-01-01

The accident at Chernobyl-4 occurred during the running of a test to determine the turbogenerator's ability to provide in-house emergency power after shutting off its steam supply. The accident was the result of a large, destructive power excursion. This paper presents an analysis of the energetic events associated with the fuel failures, fuel-coolant thermal interactions, and the fluid-structure interaction

Dynamical soil-structure interactions: influence of soil behaviour nonlinearities

International Nuclear Information System (INIS)

Gandomzadeh, Ali

2011-01-01

The interaction of the soil with the structure has been largely explored the assumption of material and geometrical linearity of the soil. Nevertheless, for moderate or strong seismic events, the maximum shear strain can easily reach the elastic limit of the soil behavior. Considering soil-structure interaction, the nonlinear effects may change the soil stiffness at the base of the structure and therefore energy dissipation into the soil. Consequently, ignoring the nonlinear characteristics of the dynamic soil-structure interaction (DSSI) this phenomenon could lead to erroneous predictions of structural response. The goal of this work is to implement a fully nonlinear constitutive model for soils into a numerical code in order to investigate the effect of soil nonlinearity on dynamic soil structure interaction. Moreover, different issues are taken into account such as the effect of confining stress on the shear modulus of the soil, initial static condition, contact elements in the soil-structure interface, etc. During this work, a simple absorbing layer method based on a Rayleigh/Caughey damping formulation, which is often already available in existing Finite Element softwares, is also presented. The stability conditions of the wave propagation problems are studied and it is shown that the linear and nonlinear behavior are very different when dealing with numerical dispersion. It is shown that the 10 points per wavelength rule, recommended in the literature for the elastic media is not sufficient for the nonlinear case. The implemented model is first numerically verified by comparing the results with other known numerical codes. Afterward, a parametric study is carried out for different types of structures and various soil profiles to characterize nonlinear effects. Different features of the DSSI are compared to the linear case: modification of the amplitude and frequency content of the waves propagated into the soil, fundamental frequency, energy dissipation in

Aromatic-Aromatic Interactions in Biological System: Structure Activity Relationships

International Nuclear Information System (INIS)

Rajagopal, Appavu; Deepa, Mohan; Govindaraju, Munisamy

2016-01-01

While, intramolecular hydrogen bonds have attracted the greatest attention in studies of peptide conformations, the recognition that several other weakly polar interactions may be important determinants of folded structure has been growing. Burley and Petsko provided a comprehensive overview of the importance of weakly polar interactions, in shaping protein structures. The interactions between aromatic rings, which are spatially approximate, have attracted special attention. A survey of the proximal aromatic residue pairs in proteins, allowed Burley and Petsko to suggest that, “phenyl ring centroids are separated by a preferential distance of between 4.5 and 7 Å, and dihedral angles approximately 90° are most common”

Aromatic-Aromatic Interactions in Biological System: Structure Activity Relationships

Energy Technology Data Exchange (ETDEWEB)

Rajagopal, Appavu; Deepa, Mohan [Molecular Biophysics Unit, Indian Institute of Sciences-Bangalore, Karnataka (India); Govindaraju, Munisamy [Bio-Spatial Technology Research Unit, Department of Environmental Biotechnology, School of Environmental Sciences, Bharathidasan University, Tiruchirappalli, Tamil Nadu (India)

2016-02-26

While, intramolecular hydrogen bonds have attracted the greatest attention in studies of peptide conformations, the recognition that several other weakly polar interactions may be important determinants of folded structure has been growing. Burley and Petsko provided a comprehensive overview of the importance of weakly polar interactions, in shaping protein structures. The interactions between aromatic rings, which are spatially approximate, have attracted special attention. A survey of the proximal aromatic residue pairs in proteins, allowed Burley and Petsko to suggest that, “phenyl ring centroids are separated by a preferential distance of between 4.5 and 7 Å, and dihedral angles approximately 90° are most common”.

Modeling of soil-water-structure interaction

DEFF Research Database (Denmark)

Tang, Tian

as the developed nonlinear soil displacements and stresses under monotonic and cyclic loading. With the FVM nonlinear coupled soil models as a basis, multiphysics modeling of wave-seabed-structure interaction is carried out. The computations are done in an open source code environment, OpenFOAM, where FVM models...

Design and Structure-Function Characterization of 3D Printed Synthetic Porous Biomaterials for Tissue Engineering.

Science.gov (United States)

Kelly, Cambre N; Miller, Andrew T; Hollister, Scott J; Guldberg, Robert E; Gall, Ken

2018-04-01

3D printing is now adopted for use in a variety of industries and functions. In biomedical engineering, 3D printing has prevailed over more traditional manufacturing methods in tissue engineering due to its high degree of control over both macro- and microarchitecture of porous tissue scaffolds. However, with the improved flexibility in design come new challenges in characterizing the structure-function relationships between various architectures and both mechanical and biological properties in an assortment of clinical applications. Presently, the field of tissue engineering lacks a comprehensive body of literature that is capable of drawing meaningful relationships between the designed structure and resulting function of 3D printed porous biomaterial scaffolds. This work first discusses the role of design on 3D printed porous scaffold function and then reviews characterization of these structure-function relationships for 3D printed synthetic metallic, polymeric, and ceramic biomaterials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A strategy for tissue self-organization that is robust to cellular heterogeneity and plasticity.

Science.gov (United States)

Cerchiari, Alec E; Garbe, James C; Jee, Noel Y; Todhunter, Michael E; Broaders, Kyle E; Peehl, Donna M; Desai, Tejal A; LaBarge, Mark A; Thomson, Matthew; Gartner, Zev J

2015-02-17

Developing tissues contain motile populations of cells that can self-organize into spatially ordered tissues based on differences in their interfacial surface energies. However, it is unclear how self-organization by this mechanism remains robust when interfacial energies become heterogeneous in either time or space. The ducts and acini of the human mammary gland are prototypical heterogeneous and dynamic tissues comprising two concentrically arranged cell types. To investigate the consequences of cellular heterogeneity and plasticity on cell positioning in the mammary gland, we reconstituted its self-organization from aggregates of primary cells in vitro. We find that self-organization is dominated by the interfacial energy of the tissue-ECM boundary, rather than by differential homo- and heterotypic energies of cell-cell interaction. Surprisingly, interactions with the tissue-ECM boundary are binary, in that only one cell type interacts appreciably with the boundary. Using mathematical modeling and cell-type-specific knockdown of key regulators of cell-cell cohesion, we show that this strategy of self-organization is robust to severe perturbations affecting cell-cell contact formation. We also find that this mechanism of self-organization is conserved in the human prostate. Therefore, a binary interfacial interaction with the tissue boundary provides a flexible and generalizable strategy for forming and maintaining the structure of two-component tissues that exhibit abundant heterogeneity and plasticity. Our model also predicts that mutations affecting binary cell-ECM interactions are catastrophic and could contribute to loss of tissue architecture in diseases such as breast cancer.

Thermal interaction of short-pulsed laser focused beams with skin tissues

International Nuclear Information System (INIS)

Jiao Jian; Guo Zhixiong

2009-01-01

Time-dependent thermal interaction is developed in a skin tissue cylinder subjected to the irradiation of a train of short laser pulses. The skin embedded with a small tumor is stratified as three layers: epidermis, dermis and subcutaneous fat with different optical, thermal and physiological properties. The laser beam is focused to the tumor site by an objective lens for thermal therapy. The ultrafast radiation heat transfer of the focused beam is simulated by the transient discrete ordinates method. The transient Pennes bio-heat equation is solved numerically by the finite volume method with alternating direction implicit scheme. Emphasis is placed on the characterization of the focused beam propagation and absorption and the temperature rise in the focal spot. The effects of the focal spot size and location, the laser power, and the bio-heat equation are investigated. Comparisons with collimated irradiation are conducted. The focused beam can penetrate a greater depth and produce higher temperature rise at the target area, and thus reduce the possibility of thermal damage to the surrounding healthy tissue. It is ideal for killing cancerous cells and small tumors.

Thermal interaction of short-pulsed laser focused beams with skin tissues

Energy Technology Data Exchange (ETDEWEB)

Jiao Jian; Guo Zhixiong [Department of Mechanical and Aerospace Engineering, Rutgers, State University of New Jersey, Piscataway, NJ 08854 (United States)], E-mail: guo@jove.rutgers.edu

2009-07-07

Time-dependent thermal interaction is developed in a skin tissue cylinder subjected to the irradiation of a train of short laser pulses. The skin embedded with a small tumor is stratified as three layers: epidermis, dermis and subcutaneous fat with different optical, thermal and physiological properties. The laser beam is focused to the tumor site by an objective lens for thermal therapy. The ultrafast radiation heat transfer of the focused beam is simulated by the transient discrete ordinates method. The transient Pennes bio-heat equation is solved numerically by the finite volume method with alternating direction implicit scheme. Emphasis is placed on the characterization of the focused beam propagation and absorption and the temperature rise in the focal spot. The effects of the focal spot size and location, the laser power, and the bio-heat equation are investigated. Comparisons with collimated irradiation are conducted. The focused beam can penetrate a greater depth and produce higher temperature rise at the target area, and thus reduce the possibility of thermal damage to the surrounding healthy tissue. It is ideal for killing cancerous cells and small tumors.

Soil-structure interaction in nuclear power plants: a comparison of methods

International Nuclear Information System (INIS)

Wight, L.H.

1976-06-01

We performed an extensive parametric survey to analyze the differences between two methods of calculating soil-structure interaction. One method involves discretizing the soil-structure system and solving for the complete response with the LUSH computer code. The other method solves for the lumped mass structural response with Whitman soil springs. Twelve soil-structure interaction problems are solved by each of these methods. Representative results are presented and discussed. The debate within the nuclear industry in the United States over the relative merits of various methods of calculating soil-structure interaction has intensified over the last three years. The debate is largely the result of the U.S. Nuclear Regulatory Commission's position generally favoring the finite element approach. Certain sectors of the industry claim that this ruling is without technical basis, that it requires unnecessary expense, and that it inhibits the judgment of the analyst. We have addressed each of these points through lumped mass and finite element calculations on a set of twelve soil-structure interaction problems. The results of these calculations indicate some of the consequences of the choice of method

ERCOFTAC Symposium on Unsteady Separation in Fluid-Structure Interaction

CERN Document Server

Bottaro, Alessandro; Thompson, Mark

2016-01-01

This book addresses flow separation within the context of fluid-structure interaction phenomena. Here, new findings from two research communities focusing on fluids and structures are brought together, emphasizing the importance of a unified multidisciplinary approach. The book covers the theory, experimental findings, numerical simulations, and modeling in fluid dynamics and structural mechanics for both incompressible and compressible separated unsteady flows. There is a focus on the morphing of lifting structures in order to increase their aerodynamic and/or hydrodynamic performances, to control separation and to reduce noise, as well as to inspire the design of novel structures. The different chapters are based on contributions presented at the ERCOFTAC Symposium on Unsteady Separation in Fluid-Structure Interaction held in Mykonos, Greece, 17-21 June, 2013 and include extended discussions and new highlights. The book is intended for students, researchers and practitioners in the broad field of computatio...

Substructure method of soil-structure interaction analysis for earthquake loadings

Energy Technology Data Exchange (ETDEWEB)

Park, H. G.; Joe, Y. H. [Industrial Development Research Center, Univ. of Incheon, Incheon (Korea, Republic of)

1997-07-15

Substructure method has been preferably adopted for soil-structure interaction analysis because of its simplicity and economy in practical application. However, substructure method has some limitation in application and does not always give reliable results especially for embedded structures or layered soil conditions. The objective of this study to validate the reliability of the soil-structure interaction analysis results by the proposed substructure method using lumped-parameter model and suggest a method of seismic design of nuclear power plant structures with specific design conditions. In this study, theoretic background and modeling technique of soil-structure interaction phenomenon have been reviewed and an analysis technique based on substructure method using lumped-parameter model has been suggested. The practicality and reliability of the proposed method have been validated through the application of the method to the seismic analysis of the large-scale seismic test models. A technical guide for practical application and evaluation of the proposed method have been also provided through the various type parametric.

Structure, complexity and cooperation in parallel external chat interactions

DEFF Research Database (Denmark)

Grønning, Anette

2012-01-01

This article examines structure, complexity and cooperation in external chat interactions at the workplace in which one of the participants is taking part in multiple parallel conversations. The investigation is based on an analysis of nine chat interactions in a work-related context, with partic......This article examines structure, complexity and cooperation in external chat interactions at the workplace in which one of the participants is taking part in multiple parallel conversations. The investigation is based on an analysis of nine chat interactions in a work-related context...... focus is on “turn-taking organisation as the fundamental and generic aspect of interaction organisation” (Drew & Heritage, 1992, p. 25), including the use of turn-taking rules, adjacency pairs, and the importance of pauses. Even though the employee and the union members do not know one another...... and cannot see, hear, or touch one another, it is possible to detect an informal, pleasant tone in their interactions. This challenges the basically asymmetrical relationship between employee and customer, and one can sense a further level of asymmetry. In terms of medium, chat interactions exist via various...

Tissue engineering: state of the art in oral rehabilitation.

Science.gov (United States)

Scheller, E L; Krebsbach, P H; Kohn, D H

2009-05-01

More than 85% of the global population requires repair or replacement of a craniofacial structure. These defects range from simple tooth decay to radical oncologic craniofacial resection. Regeneration of oral and craniofacial tissues presents a formidable challenge that requires synthesis of basic science, clinical science and engineering technology. Identification of appropriate scaffolds, cell sources and spatial and temporal signals (the tissue engineering triad) is necessary to optimize development of a single tissue, hybrid organ or interface. Furthermore, combining the understanding of the interactions between molecules of the extracellular matrix and attached cells with an understanding of the gene expression needed to induce differentiation and tissue growth will provide the design basis for translating basic science into rationally developed components of this tissue engineering triad. Dental tissue engineers are interested in regeneration of teeth, oral mucosa, salivary glands, bone and periodontium. Many of these oral structures are hybrid tissues. For example, engineering the periodontium requires growth of alveolar bone, cementum and the periodontal ligament. Recapitulation of biological development of hybrid tissues and interfaces presents a challenge that exceeds that of engineering just a single tissue. Advances made in dental interface engineering will allow these tissues to serve as model systems for engineering other tissues or organs of the body. This review will begin by covering basic tissue engineering principles and strategic design of functional biomaterials. We will then explore the impact of biomaterials design on the status of craniofacial tissue engineering and current challenges and opportunities in dental tissue engineering.

Dissipative Structures At Laser-Solid Interactions

Science.gov (United States)

Nanai, Laszlo

1989-05-01

The questions which are discussed in this lecture refer to one of sections of laser-solid interactions, namely: to formation of different dissipative structures on the surface of metals and semiconductors when they are irradiated by intensive laser light in chemically active media (f.e.air). Some particular examples of the development at different spatial and time instabilities, periodic and stochastic structures, auto-wave processes are present-ed using testing materials vanadium metal and semiconducting V205 single crystals and light sources: cw and pulsed CO2 and YAG lasers.

Polymer structure-property requirements for stereolithographic 3D printing of soft tissue engineering scaffolds.

Science.gov (United States)

Mondschein, Ryan J; Kanitkar, Akanksha; Williams, Christopher B; Verbridge, Scott S; Long, Timothy E

2017-09-01

This review highlights the synthesis, properties, and advanced applications of synthetic and natural polymers 3D printed using stereolithography for soft tissue engineering applications. Soft tissue scaffolds are of great interest due to the number of musculoskeletal, cardiovascular, and connective tissue injuries and replacements humans face each year. Accurately replacing or repairing these tissues is challenging due to the variation in size, shape, and strength of different types of soft tissue. With advancing processing techniques such as stereolithography, control of scaffold resolution down to the μm scale is achievable along with the ability to customize each fabricated scaffold to match the targeted replacement tissue. Matching the advanced manufacturing technique to polymer properties as well as maintaining the proper chemical, biological, and mechanical properties for tissue replacement is extremely challenging. This review discusses the design of polymers with tailored structure, architecture, and functionality for stereolithography, while maintaining chemical, biological, and mechanical properties to mimic a broad range of soft tissue types. Copyright © 2017 Elsevier Ltd. All rights reserved.

A 3D bioprinting system to produce human-scale tissue constructs with structural integrity.

Science.gov (United States)

Kang, Hyun-Wook; Lee, Sang Jin; Ko, In Kap; Kengla, Carlos; Yoo, James J; Atala, Anthony

2016-03-01

A challenge for tissue engineering is producing three-dimensional (3D), vascularized cellular constructs of clinically relevant size, shape and structural integrity. We present an integrated tissue-organ printer (ITOP) that can fabricate stable, human-scale tissue constructs of any shape. Mechanical stability is achieved by printing cell-laden hydrogels together with biodegradable polymers in integrated patterns and anchored on sacrificial hydrogels. The correct shape of the tissue construct is achieved by representing clinical imaging data as a computer model of the anatomical defect and translating the model into a program that controls the motions of the printer nozzles, which dispense cells to discrete locations. The incorporation of microchannels into the tissue constructs facilitates diffusion of nutrients to printed cells, thereby overcoming the diffusion limit of 100-200 μm for cell survival in engineered tissues. We demonstrate capabilities of the ITOP by fabricating mandible and calvarial bone, cartilage and skeletal muscle. Future development of the ITOP is being directed to the production of tissues for human applications and to the building of more complex tissues and solid organs.

MR brain scan tissues and structures segmentation: local cooperative Markovian agents and Bayesian formulation

International Nuclear Information System (INIS)

Scherrer, B.

2008-12-01

Accurate magnetic resonance brain scan segmentation is critical in a number of clinical and neuroscience applications. This task is challenging due to artifacts, low contrast between tissues and inter-individual variability that inhibit the introduction of a priori knowledge. In this thesis, we propose a new MR brain scan segmentation approach. Unique features of this approach include (1) the coupling of tissue segmentation, structure segmentation and prior knowledge construction, and (2) the consideration of local image properties. Locality is modeled through a multi-agent framework: agents are distributed into the volume and perform a local Markovian segmentation. As an initial approach (LOCUS, Local Cooperative Unified Segmentation), intuitive cooperation and coupling mechanisms are proposed to ensure the consistency of local models. Structures are segmented via the introduction of spatial localization constraints based on fuzzy spatial relations between structures. In a second approach, (LOCUS-B, LOCUS in a Bayesian framework) we consider the introduction of a statistical atlas to describe structures. The problem is reformulated in a Bayesian framework, allowing a statistical formalization of coupling and cooperation. Tissue segmentation, local model regularization, structure segmentation and local affine atlas registration are then coupled in an EM framework and mutually improve. The evaluation on simulated and real images shows good results, and in particular, a robustness to non-uniformity and noise with low computational cost. Local distributed and cooperative MRF models then appear as a powerful and promising approach for medical image segmentation. (author)

Electronic structure and exchange interactions in GdB{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Baranovskiy, A., E-mail: andriy.baranovskiy@gmail.com; Grechnev, A.

2015-02-01

The electronic structure of the antiferromagnetic Shastry–Sutherland compound GdB{sub 4} has been analyzed with density functional theory and the all-electron full-potential linearized augmented-plane wave (FP-LAPW) code. Different magnetic configurations, including the realistic dimer one, have been considered. The exchange interactions were found to be J{sub 1}/k{sub B}=−12K and J{sub 2}/k{sub B}=−2–0.8K, where, J{sub 1} and J{sub 2} are the diagonal exchange interaction and the exchange interaction along the edges of a square, respectively. - Highlights: • Electronic structure of AFM Shastry–Sutherland compound GB{sub 4} is calculated. • The mechanism of exchange parameters evaluation within Heisenberg model is proposed. • Calculated exchange parameters are found to be in agreement with experimental data. • Higher-order exchange interactions are important for dimer structure stabilizing.

Simquake 3: Seismic interactions between building structures and rock-socketed foundations: Final report

International Nuclear Information System (INIS)

Howard, G.E.; Chitty, D.E.; Oleck, R.F.

1988-04-01

It has long been recognized that soil-structure interaction can significantly influence the earthquake response of massive structures such as nuclear power plant reactor buildings. The linear analysis methods that are widely used to model interaction phenomena can result in often unrecognized safety margins in design for earthquake excitation. Use of improved interaction models which capture nonlinear characteristics of interaction---such as energy dissipation and significant changes in stiffness---can provide realistic predictions of the earthquake loads imposed on nuclear power plant structures and equipment, supplying an improved basis for seismic design review. This report documents the results of a research effort investigating the soil-structure (or structure-media) interaction of reinforced concrete structures founded in backfilled rock sockets. The objectives of the research, which included field testing with semi-scale structural models, were: to examine the influence of the backfilled socket on structural dynamic response; and to develop an experimental data base for the benchmarking of computer simulation procedures

Applications of condensed matter understanding to medical tissues and disease progression: Elemental analysis and structural integrity of tissue scaffolds

Energy Technology Data Exchange (ETDEWEB)

Bradley, D.A., E-mail: d.a.bradley@surrey.ac.u [Centre for Nuclear and Radiation Physics, Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Farquharson, M.J. [Department of Radiography, School of Community and Health Sciences, City University, London (United Kingdom); Gundogdu, O. [Centre for Nuclear and Radiation Physics, Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Al-Ebraheem, Alia [Department of Radiography, School of Community and Health Sciences, City University, London (United Kingdom); Che Ismail, Elna [Centre for Nuclear and Radiation Physics, Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Kaabar, W., E-mail: w.kaabar@surrey.ac.u [Centre for Nuclear and Radiation Physics, Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Bunk, O. [Paul Scherrer Institute, CH-5232 Villigen (Switzerland); Pfeiffer, F. [Paul Scherrer Institute, CH-5232 Villigen (Switzerland); Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland); Falkenberg, G. [Hamburger Synchrotronstrahlungslabor HASYLAB at Deutsches Elektronensynchrotron DESY, Notkestr. 85, D-22603 Hamburg (Germany); Bailey, M. [Surrey Ion Beam Centre, Advanced Technology Institute, University of Surrey, Guildford GU2 7XH (United Kingdom)

2010-02-15

The investigations reported herein link tissue structure and elemental presence with issues of environmental health and disease, exemplified by uptake and storage of potentially toxic elements in the body, the osteoarthritic condition and malignancy in the breast and other soft tissues. Focus is placed on application of state-of-the-art ionizing radiation techniques, including, micro-synchrotron X-ray fluorescence (mu-SXRF) and particle-induced X-ray emission/Rutherford backscattering mapping (mu-PIXE/RBS), coherent small-angle X-ray scattering (cSAXS) and X-ray phase-contrast imaging, providing information on elemental make-up, the large-scale organisation of collagen and anatomical features of moderate and low atomic number media. For the particular situations under investigation, use of such facilities is allowing information to be obtained at an unprecedented level of detail, yielding new understanding of the affected tissues and the progression of disease.

Applications of condensed matter understanding to medical tissues and disease progression: Elemental analysis and structural integrity of tissue scaffolds

International Nuclear Information System (INIS)

Bradley, D.A.; Farquharson, M.J.; Gundogdu, O.; Al-Ebraheem, Alia; Che Ismail, Elna; Kaabar, W.; Bunk, O.; Pfeiffer, F.; Falkenberg, G.; Bailey, M.

2010-01-01

The investigations reported herein link tissue structure and elemental presence with issues of environmental health and disease, exemplified by uptake and storage of potentially toxic elements in the body, the osteoarthritic condition and malignancy in the breast and other soft tissues. Focus is placed on application of state-of-the-art ionizing radiation techniques, including, micro-synchrotron X-ray fluorescence (μ-SXRF) and particle-induced X-ray emission/Rutherford backscattering mapping (μ-PIXE/RBS), coherent small-angle X-ray scattering (cSAXS) and X-ray phase-contrast imaging, providing information on elemental make-up, the large-scale organisation of collagen and anatomical features of moderate and low atomic number media. For the particular situations under investigation, use of such facilities is allowing information to be obtained at an unprecedented level of detail, yielding new understanding of the affected tissues and the progression of disease.

Soil/Structure Interactions in Earthquakes

Science.gov (United States)

Ramey, G. W.; Moore, R. K.; Yoo, C. H.; Bush, Thomas D., Jr.; Stallings, J. M.

1986-01-01

In effort to improve design of Earthquake-resistant structures, mathematical study undertaken to simulate interactions among soil, foundation, and superstructure during various kinds of vibrational excitation. System modeled as three lumped masses connected vertically by springs, with lowest mass connected to horizontal vibrator (representing ground) through springs and dashpot. Behavior of springs described by elastic or elastoplastic force/deformation relationships. Relationships used to approximate nonlinear system behavior and soil/foundation-interface behavior.

Standard problems to evaluate soil structure interaction computer codes

International Nuclear Information System (INIS)

Miller, C.A.; Costantino, C.J.; Philippacopoulos, A.J.

1979-01-01

The seismic response of nuclear power plant structures is often calculated using lumped parameter methods. A finite element model of the structure is coupled to the soil with a spring-dashpot system used to represent the interaction process. The parameters of the interaction model are based on analytic solutions to simple problems which are idealizations of the actual problems of interest. The objective of the work reported in this paper is to compare predicted responses using the standard lumped parameter models with experimental data. These comparisons are shown to be good for a fairly uniform soil system and for loadings which do not result in nonlinear interaction effects such as liftoff. 7 references, 7 figures

Vorticity and turbulence effects in fluid structure interaction an application to hydraulic structure design

CERN Document Server

Brocchini, M

2006-01-01

This book contains a collection of 11 research and review papers devoted to the topic of fluid-structure interaction.The subject matter is divided into chapters covering a wide spectrum of recognized areas of research, such as: wall bounded turbulence; quasi 2-D turbulence; canopy turbulence; large eddy simulation; lake hydrodynamics; hydraulic hysteresis; liquid impacts; flow induced vibrations; sloshing flows; transient pipe flow and air entrainment in dropshaft.The purpose of each chapter is to summarize the main results obtained by the individual research unit through a year-long activity on a specific issue of the above list. The main feature of the book is to bring state of the art research on fluid structure interaction to the attention of the broad international community.This book is primarily aimed at fluid mechanics scientists, but it will also be of value to postgraduate students and practitioners in the field of fluid structure interaction.

The interplay between tissue growth and scaffold degradation in engineered tissue constructs

KAUST Repository

O’Dea, R. D.

2012-09-18

In vitro tissue engineering is emerging as a potential tool to meet the high demand for replacement tissue, caused by the increased incidence of tissue degeneration and damage. A key challenge in this field is ensuring that the mechanical properties of the engineered tissue are appropriate for the in vivo environment. Achieving this goal will require detailed understanding of the interplay between cell proliferation, extracellular matrix (ECM) deposition and scaffold degradation. In this paper, we use a mathematical model (based upon a multiphase continuum framework) to investigate the interplay between tissue growth and scaffold degradation during tissue construct evolution in vitro. Our model accommodates a cell population and culture medium, modelled as viscous fluids, together with a porous scaffold and ECM deposited by the cells, represented as rigid porous materials. We focus on tissue growth within a perfusion bioreactor system, and investigate how the predicted tissue composition is altered under the influence of (1) differential interactions between cells and the supporting scaffold and their associated ECM, (2) scaffold degradation, and (3) mechanotransduction-regulated cell proliferation and ECM deposition. Numerical simulation of the model equations reveals that scaffold heterogeneity typical of that obtained from μCT scans of tissue engineering scaffolds can lead to significant variation in the flow-induced mechanical stimuli experienced by cells seeded in the scaffold. This leads to strong heterogeneity in the deposition of ECM. Furthermore, preferential adherence of cells to the ECM in favour of the artificial scaffold appears to have no significant influence on the eventual construct composition; adherence of cells to these supporting structures does, however, lead to cell and ECM distributions which mimic and exaggerate the heterogeneity of the underlying scaffold. Such phenomena have important ramifications for the mechanical integrity of

Flocking transitions in confluent tissues.

Science.gov (United States)

Giavazzi, Fabio; Paoluzzi, Matteo; Macchi, Marta; Bi, Dapeng; Scita, Giorgio; Manning, M Lisa; Cerbino, Roberto; Marchetti, M Cristina

2018-04-25

Collective cell migration in dense tissues underlies important biological processes, such as embryonic development, wound healing and cancer invasion. While many aspects of single cell movements are now well established, the mechanisms leading to displacements of cohesive cell groups are still poorly understood. To elucidate the emergence of collective migration in mechanosensitive cells, we examine a self-propelled Voronoi (SPV) model of confluent tissues with an orientational feedback that aligns a cell's polarization with its local migration velocity. While shape and motility are known to regulate a density-independent liquid-solid transition in tissues, we find that aligning interactions facilitate collective motion and promote solidification, with transitions that can be predicted by extending statistical physics tools such as effective temperature to this far-from-equilibrium system. In addition to accounting for recent experimental observations obtained with epithelial monolayers, our model predicts structural and dynamical signatures of flocking, which may serve as gateway to a more quantitative characterization of collective motility.

3D MRI Modeling of Thin and Spatially Complex Soft Tissue Structures without Shrinkage: Lamprey Myosepta as an Example.

Science.gov (United States)

Wood, Bradley M; Jia, Guang; Carmichael, Owen; McKlveen, Kevin; Homberger, Dominique G

2018-05-12

3D imaging techniques enable the non-destructive analysis and modeling of complex structures. Among these, MRI exhibits good soft tissue contrast, but is currently less commonly used for non-clinical research than x-ray CT, even though the latter requires contrast-staining that shrinks and distorts soft tissues. When the objective is the creation of a realistic and complete 3D model of soft tissue structures, MRI data are more demanding to acquire and visualize and require extensive post-processing because they comprise non-cubic voxels with dimensions that represent a trade-off between tissue contrast and image resolution. Therefore, thin soft tissue structures with complex spatial configurations are not always visible in a single MRI dataset, so that standard segmentation techniques are not sufficient for their complete visualization. By using the example of the thin and spatially complex connective tissue myosepta in lampreys, we developed a workflow protocol for the selection of the appropriate parameters for the acquisition of MRI data and for the visualization and 3D modeling of soft tissue structures. This protocol includes a novel recursive segmentation technique for supplementing missing data in one dataset with data from another dataset to produce realistic and complete 3D models. Such 3D models are needed for the modeling of dynamic processes, such as the biomechanics of fish locomotion. However, our methodology is applicable to the visualization of any thin soft tissue structures with complex spatial configurations, such as fasciae, aponeuroses, and small blood vessels and nerves, for clinical research and the further exploration of tensegrity. This article is protected by copyright. All rights reserved. © 2018 Wiley Periodicals, Inc.

Thermal interaction in crusted melt jets with large-scale structures

Energy Technology Data Exchange (ETDEWEB)

Sugiyama, Ken-ichiro; Sotome, Fuminori; Ishikawa, Michio [Hokkaido Univ., Sapporo (Japan). Faculty of Engineering

1998-01-01

The objective of the present study is to experimentally observe thermal interaction which would be capable of triggering due to entrainment, or entrapment in crusted melt jets with `large-scale structure`. The present experiment was carried out by dropping molten zinc and molten tin of 100 grams, of which mass was sufficient to generate large-scale structures of melt jets. The experimental results show that the thermal interaction of entrapment type occurs in molten-zinc jets with rare probability, and the thermal interaction of entrainment type occurs in molten tin jets with high probability. The difference of thermal interaction between molten zinc and molten tin may attribute to differences of kinematic viscosity and melting point between them. (author)

Shaking table test and analysis of embedded structure soil interaction considering input motion

International Nuclear Information System (INIS)

Matsushima, Y.; Mizuno, H.; Machida, N.; Sato, K.; Okano, H.

1987-01-01

The dynamic interaction between soil and structure is decomposed into inertial interaction (II) and kinematic interaction (KI). II denotes the interaction due to inertial force applied on foundations. KI denotes the interaction of massless foundations subjected to seismic waves. Forced vibration tests by exciters are not enough to evaluate the complete soil-structure interaction due to the lack of KI. To clarify the effects of KI on the seismic response of structure, the authors intended to carry out shaking table tests of the interaction between the soil and the embedded structure. A method to decompose II and KI is introduced which reveals the construction of embedment effects. Finally, the authors discuss the validity of three kinds of simulation analyses, that is, two-dimensional, approximate three-dimensional and rigorous three-dimensional analyses, comparing with the test results

* Hierarchically Structured Electrospun Scaffolds with Chemically Conjugated Growth Factor for Ligament Tissue Engineering.

Science.gov (United States)

Pauly, Hannah M; Sathy, Binulal N; Olvera, Dinorath; McCarthy, Helen O; Kelly, Daniel J; Popat, Ketul C; Dunne, Nicholas J; Haut Donahue, Tammy Lynn

2017-08-01

The anterior cruciate ligament (ACL) of the knee is vital for proper joint function and is commonly ruptured during sports injuries or car accidents. Due to a lack of intrinsic healing capacity and drawbacks with allografts and autografts, there is a need for a tissue-engineered ACL replacement. Our group has previously used aligned sheets of electrospun polycaprolactone nanofibers to develop solid cylindrical bundles of longitudinally aligned nanofibers. We have shown that these nanofiber bundles support cell proliferation and elongation and the hierarchical structure and material properties are similar to the native human ACL. It is possible to combine multiple nanofiber bundles to create a scaffold that attempts to mimic the macroscale structure of the ACL. The goal of this work was to develop a hierarchical bioactive scaffold for ligament tissue engineering using connective tissue growth factor (CTGF)-conjugated nanofiber bundles and evaluate the behavior of mesenchymal stem cells (MSCs) on these scaffolds in vitro and in vivo. CTGF was immobilized onto the surface of individual nanofiber bundles or scaffolds consisting of multiple nanofiber bundles. The conjugation efficiency and the release of conjugated CTGF were assessed using X-ray photoelectron spectroscopy, assays, and immunofluorescence staining. Scaffolds were seeded with MSCs and maintained in vitro for 7 days (individual nanofiber bundles), in vitro for 21 days (scaled-up scaffolds of 20 nanofiber bundles), or in vivo for 6 weeks (small scaffolds of 4 nanofiber bundles), and ligament-specific tissue formation was assessed in comparison to non-CTGF-conjugated control scaffolds. Results showed that CTGF conjugation encouraged cell proliferation and ligament-specific tissue formation in vitro and in vivo. The results suggest that hierarchical electrospun nanofiber bundles conjugated with CTGF are a scalable and bioactive scaffold for ACL tissue engineering.

Three-Dimensional Bioprinting for Regenerative Dentistry and Craniofacial Tissue Engineering.

Science.gov (United States)

Obregon, F; Vaquette, C; Ivanovski, S; Hutmacher, D W; Bertassoni, L E

2015-09-01

Craniofacial tissues are organized with complex 3-dimensional (3D) architectures. Mimicking such 3D complexity and the multicellular interactions naturally occurring in craniofacial structures represents one of the greatest challenges in regenerative dentistry. Three-dimensional bioprinting of tissues and biological structures has been proposed as a promising alternative to address some of these key challenges. It enables precise manufacture of various biomaterials with complex 3D architectures, while being compatible with multiple cell sources and being customizable to patient-specific needs. This review describes different 3D bioprinting methods and summarizes how different classes of biomaterials (polymer hydrogels, ceramics, composites, and cell aggregates) may be used for 3D biomanufacturing of scaffolds, as well as craniofacial tissue analogs. While the fabrication of scaffolds upon which cells attach, migrate, and proliferate is already in use, printing of all the components that form a tissue (living cells and matrix materials together) to produce tissue constructs is still in its early stages. In summary, this review seeks to highlight some of the key advantages of 3D bioprinting technology for the regeneration of craniofacial structures. Additionally, it stimulates progress on the development of strategies that will promote the translation of craniofacial tissue engineering from the laboratory bench to the chair side. © International & American Associations for Dental Research 2015.

QCD Structure of Nuclear Interactions

Energy Technology Data Exchange (ETDEWEB)

Granados, Carlos [Florida Intl Univ., Miami, FL (United States)

2011-05-25

This dissertation investigated selected processes involving baryons and nuclei in hard scattering reactions. Through these processes, this work explored the constituent structure of baryons and the mechanisms through which the interactions between these constituents ultimately control the selected reactions. First, hard nucleon-nucleon elastic scattering was studied considering the quark exchange (QE) between the nucleons to be the dominant mechanism of interaction in the constituent picture. It was found that an angular asymmetry exhibited by proton-neutron (pn) elastic scattering data is explained within this framework if a quark-diquark picture dominates the nucleon's structure instead of a more traditional SU(6) model. The latter yields an asymmetry around 90 deg center of mass scattering with a sign opposite to what is experimentally observed. The second process is the hard breakup by a photon of a nucleon-nucleon system in light nuclei. Proton-proton (pp) and pn breakup in ³He, and double Δ-isobars production in deuteron breakup were analyzed in the hard rescattering model (HRM), which in conjunction with the QE mechanism provides a QCD description of the reaction. Cross sections for both channels in ³He photodisintegration were computed without the need of a fitting parameter. The results presented here for pp breakup show excellent agreement with recent experimental data. In double Δ-isobars production in deuteron breakup, HRM angular distributions for the two double Δ channels were compared to the pn channel and to each other. An important prediction from this study is that the Δ⁺⁺ Δ^- channel consistently dominates Δ⁺Δ⁰, which is in contrast with models that unlike the HRM consider a double Δ system in the initial state of the interaction. For such models both channels should have the same strength.

Boundary element method in dynamic interaction of structures with multilayers media

International Nuclear Information System (INIS)

Mihalache, N.; Poterasu, V.F.

1993-01-01

The paper presents the problems of dynamic interaction between the multilayers media and structure by means of B.E.M., using Green's functions. The structure considered by the authors as a particular problem concerns a reinforced concrete shear wall and soil foundation of three layers having different thickness and mechanical characteristics. The authors will present comparatively the stresses and the displacements in static and dynamic regime interaction response of the structure. Theoretical part of the paper presents: Green's functions for the multilayers media in dynamic regime, stiffness matrices, stresses and displacements in the multilayers media exprimed by means of the Green's functions induced by the shear and horizontal forces, computer program, consideration for dynamic, structure-foundation-multilayers soil foundation interaction. (author)

Effects of flexibility and soil-structure interaction on a completely buried structure with a heavily loaded roof system

International Nuclear Information System (INIS)

Chen, R.C.; Maryak, M.E.; Mulliken, J.S.

1993-01-01

A completely buried structure with a heavily loaded roof system has been analyzed for seismic forces. The seismic input was a site-specific spectrum shape anchored at 0.2g zero period acceleration in the horizontal directions, and the vertical input was prescribed at two thirds of the horizontal input. Models of the structure were developed to account for the flexibility of the base mat, walls, and roof, and were analyzed for the above seismic input with uncertainties in the soil properties considered. The results indicate that horizontal rigid body soil-structure interaction effects are negligible and the seismic amplifications are dominated by the soil-structure system natural frequencies. In addition, the analysis shows that the flexibility of the structure and soil-structure interaction cause considerable amplification of the vertical structural response of the facility's roof system. Finally it was shown that the computer program SASSI can be used to predict the soil-structure interaction responses of a completely buried structure

Discovering the structure of nerve tissue: Part 3: From Jan Evangelista Purkyně to Ludwig Mauthner.

Science.gov (United States)

Chvátal, Alexandr

2017-01-01

The previous works of Purkyně, Valentin, and Remak showed that the central and peripheral nervous systems contained not only nerve fibers but also cellular elements. The use of microscopes and new fixation techniques enabled them to accurately obtain data on the structure of nerve tissue and consequently in many European universities microscopes started to become widely used in histological and morphological studies. The present review summarizes important discoveries concerning the structure of neural tissue, mostly from vertebrates, during the period from 1838 to 1865. This review describes the discoveries of famous as well as less well-known scholars of the time, who contributed significantly to current understandings about the structure of neural tissue. The period is characterized by the first descriptions of different types of nerve cells and the first attempts of a cytoarchitectonic description of the spinal cord and brain. During the same time, the concept of a neuroglial tissue was introduced, first as a tissue for "gluing" nerve fibers, cells, and blood capillaries into one unit, but later some glial cells were described for the first time. Questions arose as to whether or not cells in ganglia and the central nervous system had the same morphological and functional properties, and whether nerve fibers and cell bodies were interconnected. Microscopic techniques started to be used for the examination of physiological as well as pathological nerve tissues. The overall state of knowledge was just a step away from the emergence of the concept of neurons and glial cells.

Time-domain soil-structure interaction analysis of nuclear facilities

International Nuclear Information System (INIS)

Coleman, Justin L.; Bolisetti, Chandrakanth; Whittaker, Andrew S.

2016-01-01

The Nuclear Regulatory Commission (NRC) regulation 10 CFR Part 50 Appendix S requires consideration of soil-structure interaction (SSI) in nuclear power plant (NPP) analysis and design. Soil-structure interaction analysis for NPPs is routinely carried out using guidance provided in the ASCE Standard 4-98 titled “Seismic Analysis of Safety-Related Nuclear Structures and Commentary”. This Standard, which is currently under revision, provides guidance on linear seismic soil-structure-interaction (SSI) analysis of nuclear facilities using deterministic and probabilistic methods. A new appendix has been added to the forthcoming edition of ASCE Standard 4 to provide guidance for time-domain, nonlinear SSI (NLSSI) analysis. Nonlinear SSI analysis will be needed to simulate material nonlinearity in soil and/or structure, static and dynamic soil pressure effects on deeply embedded structures, local soil failure at the foundation-soil interface, nonlinear coupling of soil and pore fluid, uplift or sliding of the foundation, nonlinear effects of gaps between the surrounding soil and the embedded structure and seismic isolation systems, none of which can be addressed explicitly at present. Appendix B of ASCE Standard 4 provides general guidance for NLSSI analysis but will not provide a methodology for performing the analysis. This paper provides a description of an NLSSI methodology developed for application to nuclear facilities, including NPPs. This methodology is described as series of sequential steps to produce reasonable results using any time-domain numerical code. These steps require some numerical capabilities, such as nonlinear soil constitutive models, which are also described in the paper.

An overset grid approach to linear wave-structure interaction

DEFF Research Database (Denmark)

Read, Robert; Bingham, Harry B.

2012-01-01

A finite-difference based approach to wave-structure interaction is reported that employs the overset approach to grid generation. A two-dimensional code that utilizes the Overture C++ library has been developed to solve the linear radiation problem for a floating body of arbitrary form. This sof......A finite-difference based approach to wave-structure interaction is reported that employs the overset approach to grid generation. A two-dimensional code that utilizes the Overture C++ library has been developed to solve the linear radiation problem for a floating body of arbitrary form...

Simulation of laser-tattoo pigment interaction in a tissue-mimicking phantom using Q-switched and long-pulsed lasers.

Science.gov (United States)

Ahn, K J; Kim, B J; Cho, S B

2017-08-01

Laser therapy is the treatment of choice in tattoo removal. However, the precise mechanisms of laser-tattoo pigment interactions remain to be evaluated. We evaluated the geometric patterns of laser-tattoo pigment particle interactions using a tattoo pigment-embedded tissue-mimicking (TM) phantom. A Q-switched (QS) neodymium-doped yttrium aluminum garnet laser was used at settings of 532-, 660-, and 1064-nm wavelengths, single-pulse and quick pulse-to-pulse treatment modes, and spot sizes of 4 and 7 mm. Most of the laser-tattoo interactions in the experimental conditions formed cocoon-shaped or oval photothermal and photoacoustic injury zones, which contained fragmented tattoo particles in various sizes depending on the conditions. In addition, a long-pulsed 755-nm alexandrite laser was used at a spot size of 6 mm and pulse widths of 3, 5, and 10 ms. The finer granular pattern of tattoo destruction was observed in TM phantoms treated with 3- and 5-ms pulse durations compared to those treated with a 10-ms pulse. We outlined various patterns of laser-tattoo pigment interactions in a tattoo-embedded TM phantom to predict macroscopic tattoo and surrounding tissue reactions after laser treatment for tattoo removal. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Micrometer scale guidance of mesenchymal stem cells to form structurally oriented large-scale tissue engineered cartilage.

Science.gov (United States)

Chou, Chih-Ling; Rivera, Alexander L; Williams, Valencia; Welter, Jean F; Mansour, Joseph M; Drazba, Judith A; Sakai, Takao; Baskaran, Harihara

2017-09-15

Current clinical methods to treat articular cartilage lesions provide temporary relief of the symptoms but fail to permanently restore the damaged tissue. Tissue engineering, using mesenchymal stem cells (MSCs) combined with scaffolds and bioactive factors, is viewed as a promising method for repairing cartilage injuries. However, current tissue engineered constructs display inferior mechanical properties compared to native articular cartilage, which could be attributed to the lack of structural organization of the extracellular matrix (ECM) of these engineered constructs in comparison to the highly oriented structure of articular cartilage ECM. We previously showed that we can guide MSCs undergoing chondrogenesis to align using microscale guidance channels on the surface of a two-dimensional (2-D) collagen scaffold, which resulted in the deposition of aligned ECM within the channels and enhanced mechanical properties of the constructs. In this study, we developed a technique to roll 2-D collagen scaffolds containing MSCs within guidance channels in order to produce a large-scale, three-dimensional (3-D) tissue engineered cartilage constructs with enhanced mechanical properties compared to current constructs. After rolling the MSC-scaffold constructs into a 3-D cylindrical structure, the constructs were cultured for 21days under chondrogenic culture conditions. The microstructure architecture and mechanical properties of the constructs were evaluated using imaging and compressive testing. Histology and immunohistochemistry of the constructs showed extensive glycosaminoglycan (GAG) and collagen type II deposition. Second harmonic generation imaging and Picrosirius red staining indicated alignment of neo-collagen fibers within the guidance channels of the constructs. Mechanical testing indicated that constructs containing the guidance channels displayed enhanced compressive properties compared to control constructs without these channels. In conclusion, using a novel

Fibrinogen-Related Proteins in Tissue Repair: How a Unique Domain with a Common Structure Controls Diverse Aspects of Wound Healing.

Science.gov (United States)

Zuliani-Alvarez, Lorena; Midwood, Kim S

2015-05-01

Significance: Fibrinogen-related proteins (FRePs) comprise an intriguing collection of extracellular molecules, each containing a conserved fibrinogen-like globe (FBG). This group includes the eponymous fibrinogen as well as the tenascin, angiopoietin, and ficolin families. Many of these proteins are upregulated during tissue repair and exhibit diverse roles during wound healing. Recent Advances: An increasing body of evidence highlights the specific expression of a number of FRePs following tissue injury and infection. Upon induction, each FReP uses its FBG domain to mediate quite distinct effects that contribute to different stages of tissue repair, such as driving coagulation, pathogen detection, inflammation, angiogenesis, and tissue remodeling. Critical Issues: Despite a high degree of homology among FRePs, each contains unique sequences that enable their diversification of function. Comparative analysis of the structure and function of FRePs and precise mapping of regions that interact with a variety of ligands has started to reveal the underlying molecular mechanisms by which these proteins play very different roles using their common domain. Future Directions: Fibrinogen has long been used in the clinic as a synthetic matrix serving as a scaffold or a delivery system to aid tissue repair. Novel therapeutic strategies are now emerging that harness the use of other FRePs to improve wound healing outcomes. As we learn more about the underlying mechanisms by which each FReP contributes to the repair response, specific blockade, or indeed potentiation, of their function offers real potential to enable regulation of distinct processes during pathological wound healing.

Bladder tissue engineering through nanotechnology.

Science.gov (United States)

Harrington, Daniel A; Sharma, Arun K; Erickson, Bradley A; Cheng, Earl Y

2008-08-01

The field of tissue engineering has developed in phases: initially researchers searched for "inert" biomaterials to act solely as replacement structures in the body. Then, they explored biodegradable scaffolds--both naturally derived and synthetic--for the temporary support of growing tissues. Now, a third phase of tissue engineering has developed, through the subcategory of "regenerative medicine." This renewed focus toward control over tissue morphology and cell phenotype requires proportional advances in scaffold design. Discoveries in nanotechnology have driven both our understanding of cell-substrate interactions, and our ability to influence them. By operating at the size regime of proteins themselves, nanotechnology gives us the opportunity to directly speak the language of cells, through reliable, repeatable creation of nanoscale features. Understanding the synthesis of nanoscale materials, via "top-down" and "bottom-up" strategies, allows researchers to assess the capabilities and limits inherent in both techniques. Urology research as a whole, and bladder regeneration in particular, are well-positioned to benefit from such advances, since our present technology has yet to reach the end goal of functional bladder restoration. In this article, we discuss the current applications of nanoscale materials to bladder tissue engineering, and encourage researchers to explore these interdisciplinary technologies now, or risk playing catch-up in the future.

A mechanical design principle for tissue structure and function in the airway tree.

Science.gov (United States)

LaPrad, Adam S; Lutchen, Kenneth R; Suki, Béla

2013-01-01

With every breath, the dynamically changing mechanical pressures must work in unison with the cells and soft tissue structures of the lung to permit air to efficiently traverse the airway tree and undergo gas exchange in the alveoli. The influence of mechanics on cell and tissue function is becoming apparent, raising the question: how does the airway tree co-exist within its mechanical environment to maintain normal cell function throughout its branching structure of diminishing dimensions? We introduce a new mechanical design principle for the conducting airway tree in which mechanotransduction at the level of cells is driven to orchestrate airway wall structural changes that can best maintain a preferred mechanical microenvironment. To support this principle, we report in vitro radius-transmural pressure relations for a range of airway radii obtained from healthy bovine lungs and model the data using a strain energy function together with a thick-walled cylinder description. From this framework, we estimate circumferential stresses and incremental Young's moduli throughout the airway tree. Our results indicate that the conducting airways consistently operate within a preferred mechanical homeostatic state, termed mechanical homeostasis, that is characterized by a narrow range of circumferential stresses and Young's moduli. This mechanical homeostatic state is maintained for all airways throughout the tree via airway wall dimensional and mechanical relationships. As a consequence, cells within the airway walls throughout the airway tree experience similar oscillatory strains during breathing that are much smaller than previously thought. Finally, we discuss the potential implications of how the maintenance of mechanical homeostasis, while facilitating healthy tissue-level alterations necessary for maturation, may lead to airway wall structural changes capable of chronic asthma.

A mechanical design principle for tissue structure and function in the airway tree.

Directory of Open Access Journals (Sweden)

Adam S LaPrad

Full Text Available With every breath, the dynamically changing mechanical pressures must work in unison with the cells and soft tissue structures of the lung to permit air to efficiently traverse the airway tree and undergo gas exchange in the alveoli. The influence of mechanics on cell and tissue function is becoming apparent, raising the question: how does the airway tree co-exist within its mechanical environment to maintain normal cell function throughout its branching structure of diminishing dimensions? We introduce a new mechanical design principle for the conducting airway tree in which mechanotransduction at the level of cells is driven to orchestrate airway wall structural changes that can best maintain a preferred mechanical microenvironment. To support this principle, we report in vitro radius-transmural pressure relations for a range of airway radii obtained from healthy bovine lungs and model the data using a strain energy function together with a thick-walled cylinder description. From this framework, we estimate circumferential stresses and incremental Young's moduli throughout the airway tree. Our results indicate that the conducting airways consistently operate within a preferred mechanical homeostatic state, termed mechanical homeostasis, that is characterized by a narrow range of circumferential stresses and Young's moduli. This mechanical homeostatic state is maintained for all airways throughout the tree via airway wall dimensional and mechanical relationships. As a consequence, cells within the airway walls throughout the airway tree experience similar oscillatory strains during breathing that are much smaller than previously thought. Finally, we discuss the potential implications of how the maintenance of mechanical homeostasis, while facilitating healthy tissue-level alterations necessary for maturation, may lead to airway wall structural changes capable of chronic asthma.

Interactive Hangman teaches amino acid structures and abbreviations

OpenAIRE

Pennington, BO; Sears, D; Clegg, DO

2014-01-01

© 2014 by The International Union of Biochemistry and Molecular Biology, 42(6):495-500, 2014. We developed an interactive exercise to teach students how to draw the structures of the 20 standard amino acids and to identify the one-letter abbreviations by modifying the familiar game of "Hangman." Amino acid structures were used to represent single letters throughout the game. To provide additional practice in identifying structures, hints to the answers were written in "amino acid sentences" f...

Soil-structure interaction in fuel handling building

International Nuclear Information System (INIS)

Elaidi, B.M.; Eissa, M.A.

1998-01-01

This paper presents an accurate three-dimensional seismic soil-structure interaction analysis for large structures. The method is applied to the fuel building in nuclear power plants. The analysis is performed numerically in the frequency domain and the responses are obtained by inverse Fourier transformation. The size of the structure matrices is reduced by transforming the equation of motion to the modal coordinate system. The soil is simulated as a layered media on top of viscoelastic half space. Soil impedance matrices are calculated from the principles of continuum mechanics and account for soil stiffness and energy dissipation. Effects of embedment on the field equations is incorporated through the scattering matrices or by simply scaling the soil impedance. Finite element methods are used to discretize the concrete foundation for the generation of the soil interaction matrices. Decoupling of the sloshing water in the spent fuel pools and the free-standing spent fuel racks is simulated. The input seismic motions are defined by three artificial time history accelerations. These input motions are generated to match the ground design basis response spectra and the target power spectral density function. The methods described in this paper can handle arbitrary foundation layouts, allows for large structural models, and accurately represents the soil impedance. Time history acceleration responses were subsequently used to generate floor response spectra at applicable damping values. (orig.)

Significance of structure–soil–structure interaction for closely spaced structures

International Nuclear Information System (INIS)

Roy, Christine; Bolourchi, Said; Eggers, Daniel

2015-01-01

Nuclear facilities typically consist of many closely spaced structures with different sizes and depths of embedment. Seismic response of each structure could be influenced by dynamic structure–soil–structure interaction (SSSI) behavior of adjacent closely spaced structures. This paper examines the impact of SSSI on the in-structure response spectra (ISRS) and peak accelerations of a light structure adjacent to a heavy structure and of a heavy structure adjacent to a similar heavy structure for several soil cases, foundation embedment depths, and separation distances. The impacts of a heavy surface or embedded structure on adjacent ground motions were studied. The analyses demonstrated the adjacent ground motions are sensitive to foundation embedment, soil profile, response frequency, and distance from the structure. Seismic responses of a light structure located near a heavy structure are calculated either by modeling both structures subjected to free field motions, or performing a cascade analysis by considering the light structure model subjected to modified ground motions due to the heavy structure. Cascade SSSI analyses are shown to adequately account for the effect of the heavy structure on the light structure without explicitly modeling both structures together in a single analysis. To further study the influence of SSSI behavior, this paper examines dynamic response of two adjacent heavy structures and compares this response to response of a single heavy structure neglecting adjacent structures. The SSSI responses of the two heavy structures are evaluated for varying soil conditions and structure separation distances using three-dimensional linear SSI analyses and considering anti-symmetry boundary conditions. The analyses demonstrate that the SSSI response of a light or a heavy structure can be influenced by the presence of a nearby heavy structure. Although this study considers linear analysis methodology, the conclusion of SSSI influences on dynamic

Soil-structure interaction analysis of NPP containments: substructure and frequency domain methods

International Nuclear Information System (INIS)

Venancio-Filho, F.; Almeida, M.C.F.; Ferreira, W.G.; De Barros, F.C.P.

1997-01-01

Substructure and frequency domain methods for soil-structure interaction are addressed in this paper. After a brief description of mathematical models for the soil and of excitation, the equations for dynamic soil-structure interaction are developed for a rigid surface foundation and for an embedded foundation. The equations for the frequency domain analysis of MDOF systems are provided. An example of soil-structure interaction analysis with frequency-dependent soil properties is given and examples of identification of foundation impedance functions and soil properties are presented. (orig.)

Generation of Earthquake Ground Motion Considering Local Site Effects and Soil-Structure Interaction Analysis of Ancient Structures

Energy Technology Data Exchange (ETDEWEB)

Kim, Jae Kwan; Lee, J. S.; Yang, T. S.; Cho, J. R.; R, H. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1997-09-01

In order to establish a correct correlation between them, mechanical characteristics of the ancient structures need to be investigated. Since sedimentary basins are preferred dwelling sites in ancient times, it is necessary to perform SSI analysis to derive correct correlation between the damage and ground motion intensity. Contents of Project are as follows: (1) Generation of stochastic earthquake ground motion considering source mechanism and site effects. (2) Analysis of seismic response of sedimentary basin. (3) Soil-structure interaction analysis of ancient structures (4) Investigation of dynamic response characteristics of ancient structure considering soil-structure interaction effects. A procedure is presented for generation of stochastic earthquake ground motion considering source mechanism and site effects. The simulation method proposed by Boore is used to generate the outcropping rock motion. The free field motion at the soil site is obtained by a convolution analysis. And for the study of wood structures, a nonlinear SDOF model is developed. The effects of soil-structure interaction on the behavior of the wood structures are found to be very minor. But the response can be significantly affected due to the intensity and frequency contents of the input motion. 13 refs., 6 tabs., 31 figs. (author)

Strategy elimination in games with interaction structures

NARCIS (Netherlands)

Witzel, A.; Apt, K.R.; Zvesper, J.A.

2009-01-01

We study games in the presence of an interaction structure, which allows players to communicate their preferences, assuming that each player initially only knows his own preferences. We study the outcomes of iterated elimination of strictly dominated strategies (IESDS) that can be obtained in any

Numerical study of coupled fluid-structure interaction for combustion system

NARCIS (Netherlands)

Khatir, Z.; Pozarlik, Artur Krzysztof; Cooper, R.K.; Watterson, J.W.; Kok, Jacobus B.W.

2007-01-01

The computation of fluid–structure interaction (FSI) problems requires solving simultaneously the coupled fluid and structure equations. A partitioned approach using a volume spline solution procedure is applied for the coupling of fluid dynamics and structural dynamics codes. For comparative study,

Biothermomechanical behavior of skin tissue

Institute of Scientific and Technical Information of China (English)

F.Xu; T.J.Lu; K.A.Seffen

2008-01-01

Advances in laser,microwave and similar tech nologies have led to recent developments of thermal treatments involving skin tissue.The effectiveness of these treatments is governed by the coupled thermal,mechanical,biological and neural responses of the affected tissue:a favorable interaction results in a procedure with relatively little pain and no lasting side effects.Currently,even though each behavioral facet is to a certain extent established and understood,none exists to date in the interdisciplinarv area.A highly interdisciplinary approach is required for studying the biothermomechanical behavior of skin,involving bioheat transfer.biomechanics and physiology.A comprehensive literature review penrtinent to the subject is presented in this paper,covering four subject areas:(a)skin structure,(b)skin bioheat transfer and thermal damage,(c)skin biomechanics,and(d)skin biothermomechanics.The major problems,issues,and topics for further studies are also outlined.This review finds that significant advances in each of these aspects have been achieved in recent years.Although focus is placed upon the biothermomechanical behavior of skin tissue,the fundamental concepts and methodologies reviewed in this paper may also be applicable for studying other soft tissues.

Universal structure of a strongly interacting Fermi gas

Energy Technology Data Exchange (ETDEWEB)

Kuhnle, Eva; Dyke, Paul; Hoinka, Sascha; Mark, Michael; Hu Hui; Liu Xiaji; Drummond, Peter; Hannaford, Peter; Vale, Chris, E-mail: cvale@swin.edu.au [ARC Centre of Excellence for Quantum Atom Optics, Swinburne University of Technology, Hawthorn 3122 (Australia)

2011-01-10

This paper presents studies of the universal properties of strongly interacting Fermi gases using Bragg spectroscopy. We focus on pair-correlations, their relationship to the contact C introduced by Tan, and their dependence on both the momentum and temperature. We show that short-range pair correlations obey a universal law, first derived by Tan through measurements of the static structure factor, which displays a universal scaling with the ratio of the contact to the momentum C/q. Bragg spectroscopy of ultracold {sup 6}Li atoms is employed to measure the structure factor for a wide range of momenta and interaction strengths, providing broad confirmation of this universal law. We show that calibrating our Bragg spectra using the f-sum rule leads to a dramatic improvement in the accuracy of the structure factor measurement. We also measure the temperature dependence of the contact in a unitary gas and compare our results to calculations based on a virial expansion.

Impact of soil-structure interaction on the probabilistic frequency variation of concrete structures

International Nuclear Information System (INIS)

Hadjian, A.H.; Hamilton, C.W.

1975-01-01

Earthquake response of equipment in nuclear power plants is characterized by floor response spectra. Since these spectra peak at the natural frequencies of the structure, it is important, both from safety and cost standpoints, to determine the degree of the expected variability of the calculated structural frequencies. A previous work is extended on the variability of the natural frequencies of structures due to the variations of concrete properties and a rigorous approach is presented to evaluate frequency variations based on the probability distributions of both the structural and soil parameters and jointly determine the distributions of the natural frequencies. It is assumed that the soil-structure interaction coefficients are normally distributed. With the proper choice of coordinates, the simultaneous random variations of both the structural properties and the interaction coefficients can be incorporated in the eigenvalue problem. The key methodology problem is to obtain the probability distribution of eigenvalues of matrices with random variable elements. Since no analytic relation exists between the eigenvalues and the elements, a numerical procedure had to be designed. It was found that the desired accuracy can be best achieved by splitting the joint variation into two parts: the marginal distribution of soil variations and the conditional distribution of structural variations at specific soil fractiles. Then after calculating the actual eigenvalues at judiciously selected paired values of soil and structure parameters, this information is recombined to obtain the desired cumulative distribution of natural frequencies

Generation of equipment response spectrum considering equipment-structure interaction

International Nuclear Information System (INIS)

Lee, Sang Hoon; Yoo, Kwang Hoon

2005-01-01

Floor response spectra for dynamic response of subsystem such as equipment, or piping in nuclear power plant are usually generated without considering dynamic interaction between main structure and subsystem. Since the dynamic structural response generally has the narrow-banded shapes, the resulting floor response spectra developed for various locations in the structure usually have high spectral peak amplitudes in the narrow frequency bands corresponding to the natural frequencies of the structural system. The application of such spectra for design of subsystems often leads to excessive design conservatisms, especially when the equipment frequency and structure are at resonance condition. Thus, in order to provide a rational and realistic design input for dynamic analysis and design of equipment, dynamic equipment-structure interaction (ESI) should be considered in developing equipment response spectrum which is particularly important for equipment at the resonance condition. Many analytical methods have been proposed in the past for developing equipment response spectra considering ESI. However, most of these methods have not been adapted to the practical applications because of either the complexities or the lack of rigorousness of the methods. At one hand, mass ratio among the equipment and structure was used as an important parameter to obtain equipment response spectra. Similarly, Tseng has also proposed the analytical method for developing equipment response spectra using mass ratio in the frequency domain. This method is analytically rigorous and can be easily validated. It is based on the dynamic substructuring method as applied to the dynamic soil-structure interaction (SSI) analysis, and can relatively easily be implemented for practical applications without to change the current dynamic analysis and design practice for subsystems. The equipment response spectra derived in this study are also based on Tseng's proposed method

An update on the Application of Nanotechnology in Bone Tissue Engineering.

Science.gov (United States)

Griffin, M F; Kalaskar, D M; Seifalian, A; Butler, P E

2016-01-01

Natural bone is a complex and hierarchical structure. Bone possesses an extracellular matrix that has a precise nano-sized environment to encourage osteoblasts to lay down bone by directing them through physical and chemical cues. For bone tissue regeneration, it is crucial for the scaffolds to mimic the native bone structure. Nanomaterials, with features on the nanoscale have shown the ability to provide the appropriate matrix environment to guide cell adhesion, migration and differentiation. This review summarises the new developments in bone tissue engineering using nanobiomaterials. The design and selection of fabrication methods and biomaterial types for bone tissue engineering will be reviewed. The interactions of cells with different nanostructured scaffolds will be discussed including nanocomposites, nanofibres and nanoparticles. Several composite nanomaterials have been able to mimic the architecture of natural bone. Bioceramics biomaterials have shown to be very useful biomaterials for bone tissue engineering as they have osteoconductive and osteoinductive properties. Nanofibrous scaffolds have the ability to provide the appropriate matrix environment as they can mimic the extracellular matrix structure of bone. Nanoparticles have been used to deliver bioactive molecules and label and track stem cells. Future studies to improve the application of nanomaterials for bone tissue engineering are needed.

Soil-structure Interaction in the Seismic Response of Coupled Wall-frame Structures on Pile Foundations

International Nuclear Information System (INIS)

Carbonari, S.; Dezi, F.; Leoni, G.

2008-01-01

This paper presents a study on the seismic response of coupled wall-frame structures founded on piles. A complete soil-structure interaction analysis is carried out with reference to a case study. Three different soils and seven real accelerograms are considered. Local site response analyses are performed in order to evaluate the incoming free-field motion at different depths and the ground motion amplifications. A numerical model, accounting for the pile-soil-pile interaction and for material and radiation damping, is used to evaluate the impedance matrix and the foundation input motion. The domain decomposition technique is adopted to perform time-domain seismic analyses introducing Lumped Parameter Models to take into account the impedance of the soil-structure system. Applications show that the rocking phenomena affect the behaviour of the structure by changing the base shear distribution within the wall and the frame and by increasing the structural displacements

Multispectral Enhancement Method to Increase the Visual Differences of Tissue Structures in Stained Histopathology Images

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Pinky A. Bautista

2012-01-01

Full Text Available In this paper we proposed a multispectral enhancement scheme in which the spectral colors of the stained tissue-structure of interest and its background can be independently modified by the user to further improve their visualization and color discrimination. The colors of the background objects are modified by transforming their N-band spectra through an NxN transformation matrix, which is derived by mapping the representative samples of their original spectra to the spectra of their target colors using least mean square method. On the other hand, the color of the tissue structure of interest is modified by modulating the transformed spectra with the sum of the pixel’s spectral residual-errors at specific bands weighted through an NxN weighting matrix; the spectral error is derived by taking the difference between the pixel’s original spectrum and its reconstructed spectrum using the first M dominant principal component vectors in principal component analysis. Promising results were obtained on the visualization of the collagen fiber and the non-collagen tissue structures, e.g., nuclei, cytoplasm and red blood cells (RBC, in a hematoxylin and eosin (H&E stained image.

Hydrogel-laden paper scaffold system for origami-based tissue engineering.

Science.gov (United States)

Kim, Su-Hwan; Lee, Hak Rae; Yu, Seung Jung; Han, Min-Eui; Lee, Doh Young; Kim, Soo Yeon; Ahn, Hee-Jin; Han, Mi-Jung; Lee, Tae-Ik; Kim, Taek-Soo; Kwon, Seong Keun; Im, Sung Gap; Hwang, Nathaniel S

2015-12-15

In this study, we present a method for assembling biofunctionalized paper into a multiform structured scaffold system for reliable tissue regeneration using an origami-based approach. The surface of a paper was conformally modified with a poly(styrene-co-maleic anhydride) layer via initiated chemical vapor deposition followed by the immobilization of poly-l-lysine (PLL) and deposition of Ca(2+). This procedure ensures the formation of alginate hydrogel on the paper due to Ca(2+) diffusion. Furthermore, strong adhesion of the alginate hydrogel on the paper onto the paper substrate was achieved due to an electrostatic interaction between the alginate and PLL. The developed scaffold system was versatile and allowed area-selective cell seeding. Also, the hydrogel-laden paper could be folded freely into 3D tissue-like structures using a simple origami-based method. The cylindrically constructed paper scaffold system with chondrocytes was applied into a three-ring defect trachea in rabbits. The transplanted engineered tissues replaced the native trachea without stenosis after 4 wks. As for the custom-built scaffold system, the hydrogel-laden paper system will provide a robust and facile method for the formation of tissues mimicking native tissue constructs.

Implementing a Loosely Coupled Fluid Structure Interaction Finite Element Model in PHASTA

Science.gov (United States)

Pope, David

Fluid Structure Interaction problems are an important multi-physics phenomenon in the design of aerospace vehicles and other engineering applications. A variety of computational fluid dynamics solvers capable of resolving the fluid dynamics exist. PHASTA is one such computational fluid dynamics solver. Enhancing the capability of PHASTA to resolve Fluid-Structure Interaction first requires implementing a structural dynamics solver. The implementation also requires a correction of the mesh used to solve the fluid equations to account for the deformation of the structure. This results in mesh motion and causes the need for an Arbitrary Lagrangian-Eulerian modification to the fluid dynamics equations currently implemented in PHASTA. With the implementation of both structural dynamics physics, mesh correction, and the Arbitrary Lagrangian-Eulerian modification of the fluid dynamics equations, PHASTA is made capable of solving Fluid-Structure Interaction problems.

Structural and energetic study of cation-π-cation interactions in proteins.

Science.gov (United States)

Pinheiro, Silvana; Soteras, Ignacio; Gelpí, Josep Lluis; Dehez, François; Chipot, Christophe; Luque, F Javier; Curutchet, Carles

2017-04-12

Cation-π interactions of aromatic rings and positively charged groups are among the most important interactions in structural biology. The role and energetic characteristics of these interactions are well established. However, the occurrence of cation-π-cation interactions is an unexpected motif, which raises intriguing questions about its functional role in proteins. We present a statistical analysis of the occurrence, composition and geometrical preferences of cation-π-cation interactions identified in a set of non-redundant protein structures taken from the Protein Data Bank. Our results demonstrate that this structural motif is observed at a small, albeit non-negligible frequency in proteins, and suggest a preference to establish cation-π-cation motifs with Trp, followed by Tyr and Phe. Furthermore, we have found that cation-π-cation interactions tend to be highly conserved, which supports their structural or functional role. Finally, we have performed an energetic analysis of a representative subset of cation-π-cation complexes combining quantum-chemical and continuum solvation calculations. Our results point out that the protein environment can strongly screen the cation-cation repulsion, leading to an attractive interaction in 64% of the complexes analyzed. Together with the high degree of conservation observed, these results suggest a potential stabilizing role in the protein fold, as demonstrated recently for a miniature protein (Craven et al., J. Am. Chem. Soc. 2016, 138, 1543). From a computational point of view, the significant contribution of non-additive three-body terms challenges the suitability of standard additive force fields for describing cation-π-cation motifs in molecular simulations.

Oligomeric protein structure networks: insights into protein-protein interactions

Directory of Open Access Journals (Sweden)

Brinda KV

2005-12-01

Full Text Available Abstract Background Protein-protein association is essential for a variety of cellular processes and hence a large number of investigations are being carried out to understand the principles of protein-protein interactions. In this study, oligomeric protein structures are viewed from a network perspective to obtain new insights into protein association. Structure graphs of proteins have been constructed from a non-redundant set of protein oligomer crystal structures by considering amino acid residues as nodes and the edges are based on the strength of the non-covalent interactions between the residues. The analysis of such networks has been carried out in terms of amino acid clusters and hubs (highly connected residues with special emphasis to protein interfaces. Results A variety of interactions such as hydrogen bond, salt bridges, aromatic and hydrophobic interactions, which occur at the interfaces are identified in a consolidated manner as amino acid clusters at the interface, from this study. Moreover, the characterization of the highly connected hub-forming residues at the interfaces and their comparison with the hubs from the non-interface regions and the non-hubs in the interface regions show that there is a predominance of charged interactions at the interfaces. Further, strong and weak interfaces are identified on the basis of the interaction strength between amino acid residues and the sizes of the interface clusters, which also show that many protein interfaces are stronger than their monomeric protein cores. The interface strengths evaluated based on the interface clusters and hubs also correlate well with experimentally determined dissociation constants for known complexes. Finally, the interface hubs identified using the present method correlate very well with experimentally determined hotspots in the interfaces of protein complexes obtained from the Alanine Scanning Energetics database (ASEdb. A few predictions of interface hot

Cell and tissue structural modifications in hibernating dormice

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Manuela Malatesta

2005-06-01

Full Text Available Abstract Tissues and cells of hibernating mammals undergo striking seasonal modifications of their activity through a quiescence-reactivation cycle. During winter, the temperature drastically decreases, the cell timing greatly slows down, the mitotic index sharply falls, DNA, RNA and protein synthesis are drastically reduced; however, upon arousal, all metabolic and physiological activities are quickly restored at the euthermic levels. The physiological, biochemical and behavioural aspects of hibernation have been extensively studied, but data on the morpho-functional relationships of cell and tissue components during the euthermia-hibernation-arousal cycle are rare. In this review, an overview of cell and tissue structural modifications so far reported in hibernating dormice is given and the possible role in the adaptation to the hypometabolic state as well as in the rapid resumption of activities upon arousal is discussed. Riassunto Modificazioni strutturali di cellule e tessuti in Gliridi ibernanti I tessuti e le cellule dei mammiferi ibernanti subiscono profonde modificazioni stagionali della loro attività attraverso un ciclo di quiescenza-riattivazione. Durante l'inverno, la temperatura corporea si abbassa a valori vicini a quelli ambientali, il ciclo cellulare rallenta, l'indice mitotico si riduce notevolmente e la sintesi di DNA, RNA e proteine è drasticamente ridotta. Tuttavia, al risveglio, tutte le attività metaboliche e fisiologiche sono rapidamente ristabilite ai livelli eutermici. Mentre gli aspetti fisiologici, biochimici e comportamentali dell'ibernazione sono stati ampiamenti studiati, i dati sulle relazioni morfo-funzionali dei componenti cellulari e tessutali durante il ciclo eutermia-ibernazione-risveglio sono piuttosto rari. In questo articolo vengono riassunte le attuali conoscenze sulle modificazioni strutturali di cellule e tessuti nei Gliridi ibernanti e viene discusso

Effect of tissue scaffold topography on protein structure monitored by fluorescence spectroscopy

NARCIS (Netherlands)

Portugal, C.A.M.; Truckenmüller, R.K.; Stamatialis, Dimitrios; Crespo, J.G.

2014-01-01

The impact of surface topography on the structure of proteins upon adhesion was assessed through non-invasive fluorescence monitoring. This study aimed at obtaining a better understanding about the role of protein structural status on cell–scaffold interactions. The changes induced upon adsorption

Creating Interactions between Tissue-Engineered Skeletal Muscle and the Peripheral Nervous System.

Science.gov (United States)

Smith, Alec S T; Passey, Samantha L; Martin, Neil R W; Player, Darren J; Mudera, Vivek; Greensmith, Linda; Lewis, Mark P

2016-01-01

Effective models of mammalian tissues must allow and encourage physiologically (mimetic) correct interactions between co-cultured cell types in order to produce culture microenvironments as similar as possible to those that would normally occur in vivo. In the case of skeletal muscle, the development of such a culture model, integrating multiple relevant cell types within a biomimetic scaffold, would be of significant benefit for investigations into the development, functional performance, and pathophysiology of skeletal muscle tissue. Although some work has been published regarding the behaviour of in vitro muscle models co-cultured with organotypic slices of CNS tissue or with stem cell-derived neurospheres, little investigation has so far been made regarding the potential to maintain isolated motor neurons within a 3D biomimetic skeletal muscle culture platform. Here, we review the current state of the art for engineering neuromuscular contacts in vitro and provide original data detailing the development of a 3D collagen-based model for the co-culture of primary muscle cells and motor neurons. The devised culture system promotes increased myoblast differentiation, forming arrays of parallel, aligned myotubes on which areas of nerve-muscle contact can be detected by immunostaining for pre- and post-synaptic proteins. Quantitative RT-PCR results indicate that motor neuron presence has a positive effect on myotube maturation, suggesting neural incorporation influences muscle development and maturation in vitro. The importance of this work is discussed in relation to other published neuromuscular co-culture platforms along with possible future directions for the field. © 2016 S. Karger AG, Basel.

Engineering systems for the generation of patterned co-cultures for controlling cell-cell interactions.

Science.gov (United States)

Kaji, Hirokazu; Camci-Unal, Gulden; Langer, Robert; Khademhosseini, Ali

2011-03-01

Inside the body, cells lie in direct contact or in close proximity to other cell types in a tightly controlled architecture that often regulates the resulting tissue function. Therefore, tissue engineering constructs that aim to reproduce the architecture and the geometry of tissues will benefit from methods of controlling cell-cell interactions with microscale resolution. We discuss the use of microfabrication technologies for generating patterned co-cultures. In addition, we categorize patterned co-culture systems by cell type and discuss the implications of regulating cell-cell interactions in the resulting biological function of the tissues. Patterned co-cultures are a useful tool for fabricating tissue engineered constructs and for studying cell-cell interactions in vitro, because they can be used to control the degree of homotypic and heterotypic cell-cell contact. In addition, this approach can be manipulated to elucidate important factors involved in cell-matrix interactions. Patterned co-culture strategies hold significant potential to develop biomimetic structures for tissue engineering. It is expected that they would create opportunities to develop artificial tissues in the future. This article is part of a Special Issue entitled Nanotechnologies - Emerging Applications in Biomedicine. 2010 Elsevier B.V. All rights reserved.

Human stem cell based corneal tissue mimicking structures using laser-assisted 3D bioprinting and functional bioinks.

Science.gov (United States)

Sorkio, Anni; Koch, Lothar; Koivusalo, Laura; Deiwick, Andrea; Miettinen, Susanna; Chichkov, Boris; Skottman, Heli

2018-07-01

There is a high demand for developing methods to produce more native-like 3D corneal structures. In the present study, we produced 3D cornea-mimicking tissues using human stem cells and laser-assisted bioprinting (LaBP). Human embryonic stem cell derived limbal epithelial stem cells (hESC-LESC) were used as a cell source for printing epithelium-mimicking structures, whereas human adipose tissue derived stem cells (hASCs) were used for constructing layered stroma-mimicking structures. The development and optimization of functional bioinks was a crucial step towards successful bioprinting of 3D corneal structures. Recombinant human laminin and human sourced collagen I served as the bases for the functional bioinks. We used two previously established LaBP setups based on laser induced forward transfer, with different laser wavelengths and appropriate absorption layers. We bioprinted three types of corneal structures: stratified corneal epithelium using hESC-LESCs, lamellar corneal stroma using alternating acellular layers of bioink and layers with hASCs, and finally structures with both a stromal and epithelial part. The printed constructs were evaluated for their microstructure, cell viability and proliferation, and key protein expression (Ki67, p63α, p40, CK3, CK15, collagen type I, VWF). The 3D printed stromal constructs were also implanted into porcine corneal organ cultures. Both cell types maintained good viability after printing. Laser-printed hESC-LESCs showed epithelial cell morphology, expression of Ki67 proliferation marker and co-expression of corneal progenitor markers p63α and p40. Importantly, the printed hESC-LESCs formed a stratified epithelium with apical expression of CK3 and basal expression of the progenitor markers. The structure of the 3D bioprinted stroma demonstrated that the hASCs had organized horizontally as in the native corneal stroma and showed positive labeling for collagen I. After 7 days in porcine organ cultures, the 3D bioprinted

A physiological model of the interaction between tissue bubbles and the formation of blood-borne bubbles under decompression

International Nuclear Information System (INIS)

Chappell, M A; Payne, S J

2006-01-01

Under decompression, bubbles can form in the human body, and these can be found both within the body tissues and the bloodstream. Mathematical models for the growth of both types of bubbles have previously been presented, but they have not been coupled together. This work thus explores the interaction between the growth of tissue and blood-borne bubbles under decompression, specifically looking at the extent to which they compete for the common resource of inert gas held in solution in the tissues. The influence of tissue bubbles is found to be significant for densities as low as 10 ml -1 for tissues which are poorly perfused. However, the effects of formation of bubbles in the blood are not found until the density of bubble production sites reaches 10 6 ml -1 . From comparison of the model predictions with experimental evidence for bubbles produced in animals and man under decompression, it is concluded that the density of tissue bubbles is likely to have a significant effect on the number of bubbles produced in the blood. However, the density of nucleation sites in the blood is unlikely to be sufficiently high in humans for the formation of bubbles in the blood to have a significant impact on the growth of the bubbles in the tissue

Dark matter self-interactions and small scale structure

Science.gov (United States)

Tulin, Sean; Yu, Hai-Bo

2018-02-01

We review theories of dark matter (DM) beyond the collisionless paradigm, known as self-interacting dark matter (SIDM), and their observable implications for astrophysical structure in the Universe. Self-interactions are motivated, in part, due to the potential to explain long-standing (and more recent) small scale structure observations that are in tension with collisionless cold DM (CDM) predictions. Simple particle physics models for SIDM can provide a universal explanation for these observations across a wide range of mass scales spanning dwarf galaxies, low and high surface brightness spiral galaxies, and clusters of galaxies. At the same time, SIDM leaves intact the success of ΛCDM cosmology on large scales. This report covers the following topics: (1) small scale structure issues, including the core-cusp problem, the diversity problem for rotation curves, the missing satellites problem, and the too-big-to-fail problem, as well as recent progress in hydrodynamical simulations of galaxy formation; (2) N-body simulations for SIDM, including implications for density profiles, halo shapes, substructure, and the interplay between baryons and self-interactions; (3) semi-analytic Jeans-based methods that provide a complementary approach for connecting particle models with observations; (4) merging systems, such as cluster mergers (e.g., the Bullet Cluster) and minor infalls, along with recent simulation results for mergers; (5) particle physics models, including light mediator models and composite DM models; and (6) complementary probes for SIDM, including indirect and direct detection experiments, particle collider searches, and cosmological observations. We provide a summary and critical look for all current constraints on DM self-interactions and an outline for future directions.

Nonlinear soil-structure interaction analysis of SIMQUAKE II. Final report

International Nuclear Information System (INIS)

Vaughan, D.K.; Isenberg, J.

1982-04-01

This report describes an analytic method for modeling of soil-structure interaction (SSI) for nuclear power plants in earthquakes and discusses its application to SSI analyses of SIMQUAKE II. The method is general and can be used to simulate a three-dimensional structural geometry, nonlinear site characteristics and arbitrary input ground shaking. The analytic approach uses the soil island concept to reduce SSI models to manageable size and cost. Nonlinear constitutive behavior of the soil is represented by the nonlinear, kinematic cap model. In addition, a debonding-rebonding soil-structure interface model is utilized to represent nonlinear effects which singificantly alter structural response in the SIMQUAKE tests. STEALTH, an explicit finite difference code, is used to perform the dynamic, soil-structure interaction analyses. Several two-dimensional posttest SSI analyses of model containment structures in SIMQUAKE II are performed and results compared with measured data. These analyses qualify the analytic method. They also show the importance of including debonding-rebonding at the soil-structure interface. Sensitivity of structural response to compaction characteristics of backfill material is indicated

The Contradictions and Compartmentalizing the Interactions between Integrated Business Structures: Aspect of Branding

Directory of Open Access Journals (Sweden)

Nifatova Olena M.

2017-04-01

Full Text Available The article is aimed at identifying contradictions and developing a compartmentalizing as to the interaction between integrated business structures, taking into consideration the branding approach to management. The main specific features and contradictions that arise in the process of integration in the domestic market of mergers and acquisitions have been allocated. The contradictions identified were systematized and substantiated at three economic levels: macro-, meso-, and microeconomic. A compartmentalizing of the business units interaction in a merge or an acquisition process has been proposed. This compartmentalizing takes account of the branding aspect through the introduction of «brands interaction» – cluster interaction, circular interaction, holding interaction, linear interaction, which enhances the scientific view of exploring the problem of business units interaction in the process of the formations becoming integrated. The development of a compartmentalizing as to the interaction between integrated business structures, taking into consideration the branding approach to management, would provide a more effective use of the fundamental nature of branding as synergistic force in terms of the system of integration of business structures at the current stage of development of the national economy. Further development of branding issues in this sphere will have a significant impact on the functioning of the integrated business structures with the participation of Ukrainian companies.

Embedment Effect test on soil-structure interaction

International Nuclear Information System (INIS)

Nasuda, Toshiaki; Akino, Kinji; Izumi, Masanori.

1991-01-01

A project consisting of laboratory test and field test has been conducted to clarify the embedment effect on soil-structure interaction. The objective of this project is to obtain the data for improving and preparing seismic analysis codes regarding the behavior of embedded reactor buildings during earthquakes. This project was planned to study the effect of soil-structure interaction using small size soil-structure models as well as the large scale models. The project was started in April, 1986, and is scheduled to end in March, 1994. The laboratory test models and field test models, and the measurement with accelerometers and others are described. As the interim results, the natural frequency and damping factor increased, and the amplitude decreased by the embedment of the test models. Some earthquakes were recorded in a soft rock site. The epicenters of the earthquakes occurred in 1989 are shown. The field tests were carried out in three sites. Two sites were used for the dynamic test with four test models having 8 m x 8 m plane size and 10 m height. One site was used for the static test with one concrete block as a specimen. Two models represent BWR type reactor buildings, and two models represent PWR type buildings. (K.I.)

Spatial transcriptomics: paving the way for tissue-level systems biology.

Science.gov (United States)

Moor, Andreas E; Itzkovitz, Shalev

2017-08-01

The tissues in our bodies are complex systems composed of diverse cell types that often interact in highly structured repeating anatomical units. External gradients of morphogens, directional blood flow, as well as the secretion and absorption of materials by cells generate distinct microenvironments at different tissue coordinates. Such spatial heterogeneity enables optimized function through division of labor among cells. Unraveling the design principles that govern this spatial division of labor requires techniques to quantify the entire transcriptomes of cells while accounting for their spatial coordinates. In this review we describe how recent advances in spatial transcriptomics open the way for tissue-level systems biology. Copyright © 2017 Elsevier Ltd. All rights reserved.

Interactive lung segmentation in abnormal human and animal chest CT scans

International Nuclear Information System (INIS)

Kockelkorn, Thessa T. J. P.; Viergever, Max A.; Schaefer-Prokop, Cornelia M.; Bozovic, Gracijela; Muñoz-Barrutia, Arrate; Rikxoort, Eva M. van; Brown, Matthew S.; Jong, Pim A. de; Ginneken, Bram van

2014-01-01

Purpose: Many medical image analysis systems require segmentation of the structures of interest as a first step. For scans with gross pathology, automatic segmentation methods may fail. The authors’ aim is to develop a versatile, fast, and reliable interactive system to segment anatomical structures. In this study, this system was used for segmenting lungs in challenging thoracic computed tomography (CT) scans. Methods: In volumetric thoracic CT scans, the chest is segmented and divided into 3D volumes of interest (VOIs), containing voxels with similar densities. These VOIs are automatically labeled as either lung tissue or nonlung tissue. The automatic labeling results can be corrected using an interactive or a supervised interactive approach. When using the supervised interactive system, the user is shown the classification results per slice, whereupon he/she can adjust incorrect labels. The system is retrained continuously, taking the corrections and approvals of the user into account. In this way, the system learns to make a better distinction between lung tissue and nonlung tissue. When using the interactive framework without supervised learning, the user corrects all incorrectly labeled VOIs manually. Both interactive segmentation tools were tested on 32 volumetric CT scans of pigs, mice and humans, containing pulmonary abnormalities. Results: On average, supervised interactive lung segmentation took under 9 min of user interaction. Algorithm computing time was 2 min on average, but can easily be reduced. On average, 2.0% of all VOIs in a scan had to be relabeled. Lung segmentation using the interactive segmentation method took on average 13 min and involved relabeling 3.0% of all VOIs on average. The resulting segmentations correspond well to manual delineations of eight axial slices per scan, with an average Dice similarity coefficient of 0.933. Conclusions: The authors have developed two fast and reliable methods for interactive lung segmentation in

Interaction of multiwalled carbon nanotube produces structural ...

African Journals Online (AJOL)

Abstract. Multiwalled carbon nanotube (MWCNT) has been found to produce structural changes in Calf Thymus-DNA (CT-DNA). The interaction or binding of the multi-walled carbon nanotubes (MWCNT) was investigated in order to discover if it brings about any significant changes of the DNA double helix using CD spectra ...

Centrifuge modelling of seismic soil structure interaction effects

International Nuclear Information System (INIS)

Ghosh, B.; Madabhushi, S.P.G.

2007-01-01

Proper understanding of the role of unbounded soil in the evaluation of dynamic soil structure interaction (SSI) problem is very important for structures used in the nuclear industry. In this paper, the results from a series of dynamic centrifuge tests are reported. These tests were performed on different types of soil stratifications supporting a rigid containment structure. Test results indicate that accelerations transmitted to the structure's base are dependent on the stiffness degradation in the supporting soil. Steady build up of excess pore pressure leads to softening of the soil, which decreases the shear modulus and shear strength and subsequently changes the dynamic responses. It is also shown that the presence of the structure reduces the translational component of the input base motion and induces rocking of the structure. The test results are compared with some standard formulae used for evaluating interaction in the various building codes. It was concluded that the dynamic shear modulus values used should be representative of the site conditions and can vary dramatically due to softening. Damping values used are still very uncertain and contain many factors, which cannot be accounted in the experiments. It is emphasized that simplified design processes are important to gain an insight into the behaviour of the physical mechanism but for a complete understanding of the SSI effects sophisticated methods are necessary to account for non-linear behaviour of the soil material

Ultrasound evidence of altered lumbar connective tissue structure in human subjects with chronic low back pain

Directory of Open Access Journals (Sweden)

Bouffard Nicole A

2009-12-01

Full Text Available Abstract Background Although the connective tissues forming the fascial planes of the back have been hypothesized to play a role in the pathogenesis of chronic low back pain (LBP, there have been no previous studies quantitatively evaluating connective tissue structure in this condition. The goal of this study was to perform an ultrasound-based comparison of perimuscular connective tissue structure in the lumbar region in a group of human subjects with chronic or recurrent LBP for more than 12 months, compared with a group of subjects without LBP. Methods In each of 107 human subjects (60 with LBP and 47 without LBP, parasagittal ultrasound images were acquired bilaterally centered on a point 2 cm lateral to the midpoint of the L2-3 interspinous ligament. The outcome measures based on these images were subcutaneous and perimuscular connective tissue thickness and echogenicity measured by ultrasound. Results There were no significant differences in age, sex, body mass index (BMI or activity levels between LBP and No-LBP groups. Perimuscular thickness and echogenicity were not correlated with age but were positively correlated with BMI. The LBP group had ~25% greater perimuscular thickness and echogenicity compared with the No-LBP group (ANCOVA adjusted for BMI, p Conclusion This is the first report of abnormal connective tissue structure in the lumbar region in a group of subjects with chronic or recurrent LBP. This finding was not attributable to differences in age, sex, BMI or activity level between groups. Possible causes include genetic factors, abnormal movement patterns and chronic inflammation.

Fluid structure interaction in piping systems

Energy Technology Data Exchange (ETDEWEB)

Svingen, Bjoernar

1996-12-31

The Dr. ing. thesis relates to an analysis of fluid structure interaction in piping systems in the frequency domain. The governing equations are the water hammer equations for the liquid, and the beam-equations for the structure. The fluid and structural equations are coupled through axial stresses and fluid continuity relations controlled by the contraction factor (Poisson coupling), and continuity and force relations at the boundaries (junction coupling). A computer program has been developed using the finite element method as a discretization technique both for the fluid and for the structure. This is made for permitting analyses of large systems including branches and loops, as well as including hydraulic piping components, and experiments are executed. Excitations are made in a frequency range from zero Hz and up to at least one thousand Hz. Frequency dependent friction is modelled as stiffness proportional Rayleigh damping both for the fluid and for the structure. With respect to the water hammer equations, stiffness proportional damping is seen as an artificial (bulk) viscosity term. A physical interpretation of this term in relation to transient/oscillating hydraulic pipe-friction is given. 77 refs., 72 figs., 4 tabs.

Emergence of structural patterns out of synchronization in networks with competitive interactions

Science.gov (United States)

Assenza, Salvatore; Gutiérrez, Ricardo; Gómez-Gardeñes, Jesús; Latora, Vito; Boccaletti, Stefano

2011-09-01

Synchronization is a collective phenomenon occurring in systems of interacting units, and is ubiquitous in nature, society and technology. Recent studies have enlightened the important role played by the interaction topology on the emergence of synchronized states. However, most of these studies neglect that real world systems change their interaction patterns in time. Here, we analyze synchronization features in networks in which structural and dynamical features co-evolve. The feedback of the node dynamics on the interaction pattern is ruled by the competition of two mechanisms: homophily (reinforcing those interactions with other correlated units in the graph) and homeostasis (preserving the value of the input strength received by each unit). The competition between these two adaptive principles leads to the emergence of key structural properties observed in real world networks, such as modular and scale-free structures, together with a striking enhancement of local synchronization in systems with no global order.

Fluid-Structure Interaction Mechanisms for Close-In Explosions

Directory of Open Access Journals (Sweden)

Andrew B. Wardlaw Jr.

2000-01-01

Full Text Available This paper examines fluid-structure interaction for close-in internal and external underwater explosions. The resulting flow field is impacted by the interaction between the reflected explosion shock and the explosion bubble. This shock reflects off the bubble as an expansion that reduces the pressure level between the bubble and the target, inducing cavitation and its subsequent collapse that reloads the target. Computational examples of several close-in interaction cases are presented to document the occurrence of these mechanisms. By comparing deformable and rigid body simulations, it is shown that cavitation collapse can occur solely from the shock-bubble interaction without the benefit of target deformation. Addition of a deforming target lowers the flow field pressure, facilitates cavitation and cavitation collapse, as well as reducing the impulse of the initial shock loading.

The extracellular matrix: Structure, composition, age-related differences, tools for analysis and applications for tissue engineering.

Science.gov (United States)

Kular, Jaspreet K; Basu, Shouvik; Sharma, Ram I

2014-01-01

The extracellular matrix is a structural support network made up of diverse proteins, sugars and other components. It influences a wide number of cellular processes including migration, wound healing and differentiation, all of which is of particular interest to researchers in the field of tissue engineering. Understanding the composition and structure of the extracellular matrix will aid in exploring the ways the extracellular matrix can be utilised in tissue engineering applications especially as a scaffold. This review summarises the current knowledge of the composition, structure and functions of the extracellular matrix and introduces the effect of ageing on extracellular matrix remodelling and its contribution to cellular functions. Additionally, the current analytical technologies to study the extracellular matrix and extracellular matrix-related cellular processes are also reviewed.

Next Generation Tissue Engineering of Orthopedic Soft Tissue-to-Bone Interfaces

Science.gov (United States)

Boys, Alexander J.; McCorry, Mary Clare; Rodeo, Scott; Bonassar, Lawrence J.; Estroff, Lara A.

2017-01-01

Soft tissue-to-bone interfaces are complex structures that consist of gradients of extracellular matrix materials, cell phenotypes, and biochemical signals. These interfaces, called entheses for ligaments, tendons, and the meniscus, are crucial to joint function, transferring mechanical loads and stabilizing orthopedic joints. When injuries occur to connected soft tissue, the enthesis must be re-established to restore function, but due to structural complexity, repair has proven challenging. Tissue engineering offers a promising solution for regenerating these tissues. This prospective review discusses methodologies for tissue engineering the enthesis, outlined in three key design inputs: materials processing methods, cellular contributions, and biochemical factors. PMID:29333332

Effect of soil–structure interaction on the reliability of reinforced concrete bridges

Directory of Open Access Journals (Sweden)

Kamel Bezih

2015-09-01

Full Text Available In the design of reinforced concrete (RC bridges, the random and nonlinear behavior of soil may lead to insufficient reliability levels. For this reason, it is necessary to take into account the variability of soil properties which can significantly affect the bridge behavior regarding ultimate and serviceability limit states. This study investigates the failure probability for existing reinforced concrete bridges due to the effects of interaction between the soil and the structure. In this paper, a coupled reliability–mechanical approach is developed to study the effect of soil–structure interaction for RC bridges. The modeling of this interaction is incorporated into the mechanical model of RC continuous beams, by considering nonlinear elastic soil stiffness. The reliability analysis highlights the large importance of soil–structure interaction and shows that the structural safety is highly sensitive to the variability of soil properties, especially when the nonlinear behavior of soil is considered.

Numerical procedure for fluid-structure interaction with structure displacements limited by a rigid obstacle

Directory of Open Access Journals (Sweden)

Yakhlef O.

2017-06-01

Full Text Available A fixed point algorithmis proposed to solve a fluid-structure interaction problem with the supplementary constraint that the structure displacements are limited by a rigid obstacle. Fictitious domain approach with penalization is used for the fluid equations. The surface forces from the fluid acting on the structure are computed using the fluid solution in the structure domain. The continuity of the fluid and structure velocities is imposed through the penalization parameter. The constraint of non-penetration of the elastic structure into the rigid obstacle is treated weakly. A convex constrained optimization problem is solved in order to get the structure displacements. Numerical results are presented.

Soil-structure interaction Vol.3. Influence of ground water

Energy Technology Data Exchange (ETDEWEB)

Costantino, C J

1986-04-01

This study has been performed for the Nuclear Regulatory Commission (NRC) by the Structural Analysis Division of Brookhaven National Laboratory (BNL). The study was conducted during the fiscal year 1965 on the program entitled 'Benchmarking of Structural Engineering Problems' sponsored by NRC. The program considered three separate but complementary problems, each associated with the soil-structure interaction (551) phase of the seismic response analysis of nuclear plant facilities. The reports, all entitled Soil-Structure Interaction, are presented in three separate volumes, namely: Vol. 1 Influence of Layering by AJ Philippacopoulos, Vol. 2 Influence of Lift-Off by C.A. Miller, Vol. 3 Influence of Ground Water by C.J. Costantino. The two problems presented in Volumes 2 and 3 were conducted at the City University of New York (CUNY) under subcontract to BNL. This report, Volume 3 of the report, presents a summary of the first year's effort on the subject of the influence of foundation ground water on the SSI phenomenon. A finite element computer program was developed for the two-phased formulation of the combined soil-water problem. This formulation is based on the Biot dynamic equations of motion for both the solid and fluid phases of a typical soil. Frequency dependent interaction coefficients were generated for the two-dimensional plane problem of a rigid surface footing moving against a saturated linear soil. The results indicate that interaction coefficients are significantly modified as compared to the comparable values for a dry soil, particularly for the rocking mode of response. Calculations were made to study the impact of the modified interaction coefficients on the response of a typical nuclear reactor building. The amplification factors for a stick model placed atop a dry and saturated soil were computed. It was found that pore water caused the rocking response to decrease and translational response to increase over the frequency range of interest, as

Control-structure interaction in precision pointing servo loops

Science.gov (United States)

Spanos, John T.

1989-01-01

The control-structure interaction problem is addressed via stability analysis of a generic linear servo loop model. With the plant described by the rigid body mode and a single elastic mode, structural flexibility is categorized into one of three types: (1) appendage, (2) in-the-loop minimum phase, and (3) in-the-loop nonminimum phase. Closing the loop with proportional-derivative (PD) control action and introducing sensor roll-off dynamics in the feedback path, stability conditions are obtained. Trade studies are conducted with modal frequency, modal participation, modal damping, loop bandwidth, and sensor bandwidth treated as free parameters. Results indicate that appendage modes are most likely to produce instability if they are near the sensor rolloff, whereas in-the-loop modes are most dangerous near the loop bandwidth. The main goal of this paper is to provide a fundamental understanding of the control-structure interaction problem so that it may benefit the design of complex spacecraft and pointing system servo loops. In this framework, the JPL Pathfinder gimbal pointer is considered as an example.

Calculation methods of Structure-Soil-Structure Interaction (3SI) for embedded buildings: Application to NUPEC tests

International Nuclear Information System (INIS)

Clouteau, D.; Broc, D.; Devesa, G.; Guyonvarh, V.; Massin, P.

2012-01-01

This work aims at improving and validating methods coupling Finite Element (FE) and Boundary Element (BE) Methods in the context of Soil-Structure Interaction (SSI) and Structure-Soil-Structure Interaction (3SI) tests performed by NUPEC on mock-up structures built on an unmade ground. Several cases have been tested: single and juxtaposed buildings, shallow and embedded foundations, with various loading conditions: forced and natural seismic loadings. The numerical simulations of forced vibration tests are in good agreement with the results of the NUPEC experiments in the case of two embedded buildings either in terms of amplitude and resonance. The numerical simulation of seismic response tests by FEM and BEM allows for a proper choice of the 'reference point' where the computed and the experimental displacements coincide. A parametric analysis of Structure-Soil-Structure Interaction carried out by the FEM has allowed to determine the influence of some parameters on SSI. Most of them like the position of the building in the excavation, the direction of the load, the quality of the contact between the sidewalls of the buildings and the soil for embedded foundations, do not show to have a strong influence on the dynamic system behaviour, which is mainly governed by the stiffness of the first soil layer. As far as 3SI is concerned, this paper shows that when the cross interaction has a small effect on the building response in the case of surface foundations, it has a strong influence in the case of embedded foundations with an important decrease of the response at the top of the buildings. (authors)

Storage Conditions of Skin Affect Tissue Structure and Subsequent in vitro Percutaneous Penetration

DEFF Research Database (Denmark)

Nielsen, Jesper Bo; Plasencia Gil, Maria Inés; Sørensen, Jens Ahm

2011-01-01

fluorescence microscopy) and in vitro percutaneous penetration of caffeine under four different storage conditions using skin samples from the same donors: fresh skin, skin kept at -20°C for 3 weeks (with or without the use of polyethylene glycol) and at -80°C. Our results show a correlation between increasing...... permeation of caffeine and tissue structural damage caused by the storage conditions, most so after skin storage at -80°C. The presented approach, which combines imaging techniques with studies on percutaneous penetration, enables the link between tissue damage at selected depths and penetration...

Esau's Plant anatomy: meristems, cells, and tissues of the plant body : their structure, function, and development

National Research Council Canada - National Science Library

Evert, Ray Franklin; Esau, Katherine; Eichhorn, Susan E

2006-01-01

... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Body of a Vascular Plant Is Composed of Three Tissue Systems . . . . . . . . . . . . . . . . . . . . . Structurally Stem, Leaf, and Root Differ Primarily...

Ontogenesis of muscle and adipose tissues and their interactions in ruminants and other species.

Science.gov (United States)

Bonnet, M; Cassar-Malek, I; Chilliard, Y; Picard, B

2010-07-01

The lean-to-fat ratio, that is, the relative masses of muscle and adipose tissue, is a criterion for the yield and quality of bovine carcasses and meat. This review describes the interactions between muscle and adipose tissue (AT) that may regulate the dynamic balance between the number and size of muscle v. adipose cells. Muscle and adipose tissue in cattle grow by an increase in the number of cells (hyperplasia), mainly during foetal life. The total number of muscle fibres is set by the end of the second trimester of gestation. By contrast, the number of adipocytes is never set. Number of adipocytes increases mainly before birth until 1 year of age, depending on the anatomical location of the adipose tissue. Hyperplasia concerns brown pre-adipocytes during foetal life and white pre-adipocytes from a few weeks after birth. A decrease in the number of secondary myofibres and an increase in adiposity in lambs born from mothers severely underfed during early pregnancy suggest a balance in the commitment of a common progenitor into the myogenic or adipogenic lineages, or a reciprocal regulation of the commitment of two distinct progenitors. The developmental origin of white adipocytes is a subject of debate. Molecular and histological data suggested a possible transdifferentiation of brown into white adipocytes, but this hypothesis has now been challenged by the characterization of distinct precursor cells for brown and white adipocytes in mice. Increased nutrient storage in fully differentiated muscle fibres and adipocytes, resulting in cell enlargement (hypertrophy), is thought to be the main mechanism, whereby muscle and fat masses increase in growing cattle. Competition or prioritization between adipose and muscle cells for the uptake and metabolism of nutrients is suggested, besides the successive waves of growth of muscle v. adipose tissue, by the inhibited or delayed adipose tissue growth in bovine genotypes exhibiting strong muscular development. This

Functional structural motifs for protein-ligand, protein-protein, and protein-nucleic acid interactions and their connection to supersecondary structures.

Science.gov (United States)

Kinjo, Akira R; Nakamura, Haruki

2013-01-01

Protein functions are mediated by interactions between proteins and other molecules. One useful approach to analyze protein functions is to compare and classify the structures of interaction interfaces of proteins. Here, we describe the procedures for compiling a database of interface structures and efficiently comparing the interface structures. To do so requires a good understanding of the data structures of the Protein Data Bank (PDB). Therefore, we also provide a detailed account of the PDB exchange dictionary necessary for extracting data that are relevant for analyzing interaction interfaces and secondary structures. We identify recurring structural motifs by classifying similar interface structures, and we define a coarse-grained representation of supersecondary structures (SSS) which represents a sequence of two or three secondary structure elements including their relative orientations as a string of four to seven letters. By examining the correspondence between structural motifs and SSS strings, we show that no SSS string has particularly high propensity to be found interaction interfaces in general, indicating any SSS can be used as a binding interface. When individual structural motifs are examined, there are some SSS strings that have high propensity for particular groups of structural motifs. In addition, it is shown that while the SSS strings found in particular structural motifs for nonpolymer and protein interfaces are as abundant as in other structural motifs that belong to the same subunit, structural motifs for nucleic acid interfaces exhibit somewhat stronger preference for SSS strings. In regard to protein folds, many motif-specific SSS strings were found across many folds, suggesting that SSS may be a useful description to investigate the universality of ligand binding modes.

Seismic soil structure interaction: analysis and centrifuge model studies

International Nuclear Information System (INIS)

Finn, W.D.L.; Ledbetter, R.H.; Beratan, L.L.

1985-01-01

A method for non-linear dynamic effective stress analysis is introduced which is applicable to soil-structure interaction problems. Full interaction including slip between structure and foundation is taken into account and the major factors are included which must be considered when computing dynamic soil response. An experimental investigation was conducted using simulated earthquake tests on centrifuged geotechnical models in order to obtain prototype response data of foundation soils carrying both surface and embedded structures and to validate the dynamic effective stress analysis. Horizontal and vertical accelerations were measured at various points on structures and in the sand foundation. Seismically-induced pore water pressure changes were also measured at various locations in the foundation. Computer plots of the data were obtained while the centrifuge was in flight and representative samples are presented. The results show clearly the pronounced effect that increasing pore water pressures have on dynamic response. It is demonstrated that a coherent picture of dynamic response of soil-structure systems is provided by dynamic effective stress non-linear analysis. Based on preliminary results, it appears that the pore water pressure effects can be predicted

Seismic soil-structure interaction: Analysis and centrifuge model studies

International Nuclear Information System (INIS)

Finn, W.D.L.; Ledbetter, R.H.; Beratan, L.L.

1986-01-01

A method for nonlinear dynamic effective stress analysis applicable to soil-structure interaction problems is introduced. Full interaction including slip between structure and foundation is taken into account and the major factors that must be considered when computing dynamic soil response are included. An experimental investigation using simulated earthquake tests on centrifuged geotechnical models was conducted to obtain prototype response data of foundation soils carrying both surface and embedded structures and to validate the dynamic effective stress analysis. The centrifuge tests were conducted in the Geotechnical Centrifuge at Cambridge University, England. Horizontal and vertical accelerations were measured at various points on structures and in the sand foundation. Seismically induced pore water pressure changes were also measured at various locations in the foundation. Computer plots of the data were obtained while the centrifuge was in flight and representative samples are presented. The results clearly show the pronounced effect of increasing pore water pressures on dynamic response. It is demonstrated that a coherent picture of dynamic response of soil-structure systems is provided by dynamic effective stress nonlinear analysis. On the basis of preliminary results, it appears that the effects of pore water pressure can be predicted. (orig.)

Soil-structure interaction analysis by finite element methods - state-of-the-art

International Nuclear Information System (INIS)

Seed, H.B.; Lysmer, J.

1977-01-01

Analyses of soil-structure interaction effects during earthquakes for nuclear power plant structures are usually made by one of two methods-either by means of an idealized complete interaction analysis involving consideration of a compatible variation of motion in the structure and the adjacent soil, or by means of an inertial interaction analysis in which the motions in the adjacent soil are assumed to be the same at all points above the foundation depth. For embedded structures, consideration of the variation of motions with depth is essential if adequate evaluations of soil and structural response are to be obtained without undue conservatism. The finite element analysis procedure is particularly well suited for evaluating the response of embedded structures since it can readily provide consideration of the variation of soil characteristics with depth, the different non-linear deformation and energy absorbing capacities of the various soil strata, the variation of motions with depth in accordance with the general principles of engineering mechanics, the three-dimensional nature of the problem and the effects of adjacent structures on each other. (Auth.)

Tissue bionics: examples in biomimetic tissue engineering

Energy Technology Data Exchange (ETDEWEB)

Green, David W [Bone and Joint Research Group, Developmental Origins of Health and Disease, General Hospital, University of Southampton, SO16 6YD (United Kingdom)], E-mail: Hindoostuart@googlemail.com

2008-09-01

Many important lessons can be learnt from the study of biological form and the functional design of organisms as design criteria for the development of tissue engineering products. This merging of biomimetics and regenerative medicine is termed 'tissue bionics'. Clinically useful analogues can be generated by appropriating, modifying and mimicking structures from a diversity of natural biomatrices ranging from marine plankton shells to sea urchin spines. Methods in biomimetic materials chemistry can also be used to fabricate tissue engineering scaffolds with added functional utility that promise human tissues fit for the clinic.

Tissue bionics: examples in biomimetic tissue engineering

International Nuclear Information System (INIS)

Green, David W

2008-01-01

Many important lessons can be learnt from the study of biological form and the functional design of organisms as design criteria for the development of tissue engineering products. This merging of biomimetics and regenerative medicine is termed 'tissue bionics'. Clinically useful analogues can be generated by appropriating, modifying and mimicking structures from a diversity of natural biomatrices ranging from marine plankton shells to sea urchin spines. Methods in biomimetic materials chemistry can also be used to fabricate tissue engineering scaffolds with added functional utility that promise human tissues fit for the clinic

Simple preparation of plant epidermal tissue for laser microdissection and downstream quantitative proteome and carbohydrate analysis

Directory of Open Access Journals (Sweden)

Christian eFalter

2015-03-01

Full Text Available The outwardly directed cell wall and associated plasma membrane of epidermal cells represent the first layers of plant defense against intruding pathogens. Cell wall modifications and the formation of defense structures at sites of attempted pathogen penetration are decisive for plant defense. A precise isolation of these stress-induced structures would allow a specific analysis of regulatory mechanism and cell wall adaption. However, methods for large-scale epidermal tissue preparation from the model plant Arabidopsis thaliana, which would allow proteome and cell wall analysis of complete, laser-microdissected epidermal defense structures, have not been provided. We developed the adhesive tape – liquid cover glass technique for simple leaf epidermis preparation from A. thaliana, which is also applicable on grass leaves. This method is compatible with subsequent staining techniques to visualize stress-related cell wall structures, which were precisely isolated from the epidermal tissue layer by laser microdissection coupled to laser pressure catapulting. We successfully demonstrated that these specific epidermal tissue samples could be used for quantitative downstream proteome and cell wall analysis. The development of the adhesive tape – liquid cover glass technique for simple leaf epidermis preparation and the compatibility to laser microdissection and downstream quantitative analysis opens new possibilities in the precise examination of stress- and pathogen-related cell wall structures in epidermal cells. Because the developed tissue processing is also applicable on A. thaliana, well-established, model pathosystems that include the interaction with powdery mildews can be studied to determine principal regulatory mechanisms in plant-microbe interaction with their potential outreach into crop breeding.

Reconstruction of structure and function in tissue engineering of solid organs: Toward simulation of natural development based on decellularization.

Science.gov (United States)

Zheng, Chen-Xi; Sui, Bing-Dong; Hu, Cheng-Hu; Qiu, Xin-Yu; Zhao, Pan; Jin, Yan

2018-04-27

Failure of solid organs, such as the heart, liver, and kidney, remains a major cause of the world's mortality due to critical shortage of donor organs. Tissue engineering, which uses elements including cells, scaffolds, and growth factors to fabricate functional organs in vitro, is a promising strategy to mitigate the scarcity of transplantable organs. Within recent years, different construction strategies that guide the combination of tissue engineering elements have been applied in solid organ tissue engineering and have achieved much progress. Most attractively, construction strategy based on whole-organ decellularization has become a popular and promising approach, because the overall structure of extracellular matrix can be well preserved. However, despite the preservation of whole structure, the current constructs derived from decellularization-based strategy still perform partial functions of solid organs, due to several challenges, including preservation of functional extracellular matrix structure, implementation of functional recellularization, formation of functional vascular network, and realization of long-term functional integration. This review overviews the status quo of solid organ tissue engineering, including both advances and challenges. We have also put forward a few techniques with potential to solve the challenges, mainly focusing on decellularization-based construction strategy. We propose that the primary concept for constructing tissue-engineered solid organs is fabricating functional organs based on intact structure via simulating the natural development and regeneration processes. Copyright © 2018 John Wiley & Sons, Ltd.

Smoothed particle hydrodynamics modelling in continuum mechanics: fluid-structure interaction

Directory of Open Access Journals (Sweden)

Groenenboom P. H. L.

2009-06-01

Full Text Available Within this study, the implementation of the smoothed particle hydrodynamics (SPH method solving the complex problem of interaction between a quasi-incompressible fluid involving a free surface and an elastic structure is outlined. A brief description of the SPH model for both the quasi-incompressible fluid and the isotropic elastic solid is presented. The interaction between the fluid and the elastic structure is realised through the contact algorithm. The results of numerical computations are confronted with the experimental as well as computational data published in the literature.

Direct methods of soil-structure interaction analysis for earthquake loadings

International Nuclear Information System (INIS)

Yun, J. B.; Kim, J. M.; Kim, Y. S. and others

1993-07-01

The objectives of this study are to review the methods of soil- structure interaction system analysis, particularly the direct method, and to carry out the blind prediction analysis of the Forced Vibration Test(FVT) before backfill in the course of Hualien LSST project. The scope and contents of this study are as follows : theoretical review on soil-structure interaction analysis methods, free-field response analysis methods, modelling methods of unbounded exterior region, hualien LSST FVT blind prediction analysis before backfill. The analysis results are found to be very well compared with the field test results

Structure-function relationships in soft tissue mechanics: Examining how the micro-scale architecture of biochemical constituents effects health

Science.gov (United States)

Schultz, David Sheldon

Countless debilitating pathologies exhibit symptoms that result from altered mechanical behavior of soft tissue. Therefore, it is of clinical and economic importance to mechanically evaluate soft tissues and attribute degenerative changes to alterations in structural constituents. The studies presented here focus on the annulus fibrosus and the sclera. Failure in these tissues is common and catastrophic. The annulus fibrosus may fail, resulting in herniation and nerve impingement, or the disc may degenerate over time, resulting in reduced mobility and pain. Similarly, the sclera may degenerate over time with intraocular pressure spurring creep behavior that distends the eye beyond its ideal shape. This causes myopic vision and puts patients at risk of macular degeneration and retinal detachment. These two tissues share a common structural role as the outer wall of a pressure vessel. Also, they are made of strikingly similar constituents, primarily consisting of water, type I collagen, glycosaminoglycans and elastin. The microstructure of these tissues, however, is very different. The annulus fibrosus is representative of an anisotropic tissue. Its well-organized fibril structure was analyzed via polarization modulated second harmonic microscopy in order to characterize fibril architecture. Structurally relevant biochemical constituents were quantified with biochemical assays. Morphologically healthy annulus tended to have a more highly organized microstructure and tended to absorb more strain energy when subject to a tensile load cycle. Given the strong correlation between fibril organization and select mechanical properties, predictive models will likely benefit from a characterization of fibril continuity and orientation coherence. The sclera is representative of an isotropic tissue. Its less-organized fibril structure has evolved to sustain biaxial plane stress. In the sclera, collagen content and associated crosslinks were primary determinants of stiffness

Fabrication of three-dimensional poly(ε-caprolactone) scaffolds with hierarchical pore structures for tissue engineering

Energy Technology Data Exchange (ETDEWEB)

Zhang, Qingchun [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Luo, Houyong [State Key Laboratory of Bioreactor Engineering, School of Bioengineering, East China University of Science and Technology, Shanghai 200237 (China); Zhang, Yan [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zhou, Yan [State Key Laboratory of Bioreactor Engineering, School of Bioengineering, East China University of Science and Technology, Shanghai 200237 (China); Ye, Zhaoyang, E-mail: zhaoyangye@ecust.edu.cn [State Key Laboratory of Bioreactor Engineering, School of Bioengineering, East China University of Science and Technology, Shanghai 200237 (China); Tan, Wensong [State Key Laboratory of Bioreactor Engineering, School of Bioengineering, East China University of Science and Technology, Shanghai 200237 (China); Lang, Meidong, E-mail: mdlang@ecust.edu.cn [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China)

2013-05-01

The physical properties of tissue engineering scaffolds such as microstructures play important roles in controlling cellular behaviors and neotissue formation. Among them, the pore size stands out as a key determinant factor. In the present study, we aimed to fabricate porous scaffolds with pre-defined hierarchical pore sizes, followed by examining cell growth in these scaffolds. This hierarchical porous microstructure was implemented via integrating different pore-generating methodologies, including salt leaching and thermal induced phase separation (TIPS). Specifically, large (L, 200–300 μm), medium (M, 40–50 μm) and small (S, < 10 μm) pores were able to be generated. As such, three kinds of porous scaffolds with a similar porosity of ∼ 90% creating pores of either two (LS or MS) or three (LMS) different sizes were successfully prepared. The number fractions of different pores in these scaffolds were determined to confirm the hierarchical organization of pores. It was found that the interconnectivity varied due to the different pore structures. Besides, these scaffolds demonstrated similar compressive moduli under dry and hydrated states. The adhesion, proliferation, and spatial distribution of human fibroblasts within the scaffolds during a 14-day culture were evaluated with MTT assay and fluorescence microscopy. While all three scaffolds well supported the cell attachment and proliferation, the best cell spatial distribution inside scaffolds was achieved with LMS, implicating that such a controlled hierarchical microstructure would be advantageous in tissue engineering applications. Highlights: ► The scaffolds with dual-pore and triple-pore structures were fabricated. ► Triple-pore structure had better interconnectivity than dual-pore structures. ► Better cell migration and distribution were found on the triple-pore structures. ► The medium pore size (45–50 μm) was appropriate for cell migration. ► Scaffolds with triple-pore structure

ERP evidence on the interaction between information structure and emotional salience of words.

Science.gov (United States)

Wang, Lin; Bastiaansen, Marcel; Yang, Yufang; Hagoort, Peter

2013-06-01

Both emotional words and words focused by information structure can capture attention. This study examined the interplay between emotional salience and information structure in modulating attentional resources in the service of integrating emotional words into sentence context. Event-related potentials (ERPs) to affectively negative, neutral, and positive words, which were either focused or nonfocused in question-answer pairs, were evaluated during sentence comprehension. The results revealed an early negative effect (90-200 ms), a P2 effect, as well as an effect in the N400 time window, for both emotional salience and information structure. Moreover, an interaction between emotional salience and information structure occurred within the N400 time window over right posterior electrodes, showing that information structure influences the semantic integration only for neutral words, but not for emotional words. This might reflect the fact that the linguistic salience of emotional words can override the effect of information structure on the integration of words into context. The interaction provides evidence for attention-emotion interactions at a later stage of processing. In addition, the absence of interaction in the early time window suggests that the processing of emotional information is highly automatic and independent of context. The results suggest independent attention capture systems of emotional salience and information structure at the early stage but an interaction between them at a later stage, during the semantic integration of words.

Modelling organs, tissues, cells and devices using Matlab and Comsol multiphysics

CERN Document Server

Dokos, Socrates

2017-01-01

This book presents a theoretical and practical overview of computational modeling in bioengineering, focusing on a range of applications including electrical stimulation of neural and cardiac tissue, implantable drug delivery, cancer therapy, biomechanics, cardiovascular dynamics, as well as fluid-structure interaction for modelling of organs, tissues, cells and devices. It covers the basic principles of modeling and simulation with ordinary and partial differential equations using MATLAB and COMSOL Multiphysics numerical software. The target audience primarily comprises postgraduate students and researchers, but the book may also be beneficial for practitioners in the medical device industry.

Interaction and the structures of coal

Science.gov (United States)

Opaprakasit, Pakorn

The origin of a decrease in the amount of soluble material from coal upon a reflux treatment has been investigated in an attempt to obtain insight into the nature of the interaction in the macromolecular network structure of coal. This decrease in the extractable material is a result of an increase in the amount of physical cross-links associated with secondary interactions. The alternate possibility of covalent cross-link formation by ether linkage was found to be unlikely because the coal hydroxyl content remains unchanged upon heat treatment. The functional groups responsible for forming these physical cross-links and their contents vary from coal to coal with coal rank. Carboxylate/cation complexes, similar to those found in ionomers, dominate in low rank coal. In high rank coal, the clusters involving pi-cation interactions were observed. Both mechanisms seem to play a role in mid rank coals. These physical cross-links are responsible for a lowering of the extraction yield of coal, but are disrupted by a treatment with acid solution, resulting in an increase in the extraction yield. As a consequence, the cross-links in coal structure should be classified into two types; a "permanent" covalent cross-link, which break under extreme conditions such as chemical reaction and pyrolysis, and "reversible" cross-links, largely associated with ionomer-like structure and pi-cation interactions. The interaction between a "magic" solvent of N-methylpyrollidone and carbon disulfide (NMP/CS2) and its role in the unusual extractability enhancement of Upper Freeport coal has also been investigated. The results strongly suggest that NMP/CS2 mixed solvents form complexes with cations. These mixed solvents are capable of forming a solid complex with cations from NaOH and some simple salts, such as NaCl and LiCl. Given that Upper Freeport coal contains a large amount of mineral matter, it is not surprising that these types of complexes could be formed in the present of the mixed

Interaction Deep Excavation Adjacent Structure Numerical Two and Three Dimensional Modeling

International Nuclear Information System (INIS)

Abdallah, M.; Chehade, F. H.; Chehade, W.; Fawaz, A.

2011-01-01

Urban development often requires the construction of deep excavations near to buildings or other structures. We have to study complex material structure interactions where we should take into consideration several particularities. In this paper, we perform a numerical modeling with the finite element method, using PLAXIS software, of the interaction deep excavation-diaphragm wall-soil-structure in the case of non linear soil behavior. We focus our study on a comparison of the results given respectively by two and three dimensional modelings. This allows us to give some recommendations concerning the validity of twodimensional study. We perform a parametric study according to the initial loading on the structure and the struts number. (author)

The differentiation of malignant and benign human breast tissue at surgical margins and biopsy using x-ray interaction data and Bayesian classification

International Nuclear Information System (INIS)

Mersov, A.; Mersov, G.; Al-Ebraheem, A.; Cornacchi, S.; Gohla, G.; Lovrics, P.; Farquharson, M.J.

2014-01-01

Worldwide, about 1.3 million women are diagnosed with breast cancer annually with an estimated 465,000 deaths. Accordingly, there is a need for high accuracy and speed in diagnosis of lesions suspected of being cancerous. This study assesses the interaction data collected from low energy x-rays within breast tissue samples. Trace element concentrations are assessed using x-ray fluorescence, as well as electron density, and molecular structure which are examined using incoherent and coherent scatter, respectively. Our work to date has shown that such data can provide a quantitative measure of certain tissue characterising parameters and hence, through appropriate modelling, could be used to classify samples for uses such as surgical margin detection and biopsy examination. The parameters used in this study for comparing the normal and tumour tissue sample populations are: levels of elements Ca, Cu, Fe, Br, Zn, Rb, K; the area, FWHM and amplitude from peaks fitted to the coherent scatter profile that are associated with fat, fibre and water content; the ratio of the Compton and coherent scatter peak area, FWHM and amplitude from the incoherent scatter profile. The novelty of the approach to this work lies in the fact that the classification process does not rely on one source of data but combines several measurements, the data from which in this application are modelled using a method based on Bayesian classification. The reliability of the classifications was assessed by its application to diagnostically known data that was not itself included in the thresholds determination. The results of the classification of over 70 breast tissue samples will be presented in this study. Bayesian modelling was carried out using selected significant parameters for classification resulting in 71% of normal tissue samples (n=35) and 66% of tumour tissue samples (n=35) being correctly classified when using all the samples. Bayesian classification using the same variables on all

Fluid-structure interaction with pipe-wall viscoelasticity during water hammer

NARCIS (Netherlands)

Keramat, A.; Tijsseling, A.S.; Hou, Q.; Ahmadi, A.

2011-01-01

Fluid-structure interaction (FSI) due to water hammer in a pipeline which has viscoelastic wall behaviour is studied. Appropriate governing equations are derived and numerically solved. In the numerical implementation of the hydraulic and structural equations, viscoelasticity is incorporated using

Fluid-structure interaction with pipe-wall viscoelasticity during water hammer

NARCIS (Netherlands)

Keramat, A.; Tijsseling, A.S.; Hou, Q.; Ahmadi, A.

2012-01-01

Fluid–structure interaction (FSI) due to water hammer in a pipeline which has viscoelastic wall behaviour is studied. Appropriate governing equations are derived and numerically solved. In the numerical implementation of the hydraulic and structural equations, viscoelasticity is incorporated using

Needle-tissue interactive mechanism and steering control in image-guided robot-assisted minimally invasive surgery: a review.

Science.gov (United States)

Li, Pan; Yang, Zhiyong; Jiang, Shan

2018-06-01

Image-guided robot-assisted minimally invasive surgery is an important medicine procedure used for biopsy or local target therapy. In order to reach the target region not accessible using traditional techniques, long and thin flexible needles are inserted into the soft tissue which has large deformation and nonlinear characteristics. However, the detection results and therapeutic effect are directly influenced by the targeting accuracy of needle steering. For this reason, the needle-tissue interactive mechanism, path planning, and steering control are investigated in this review by searching literatures in the last 10 years, which results in a comprehensive overview of the existing techniques with the main accomplishments, limitations, and recommendations. Through comprehensive analyses, surgical simulation for insertion into multi-layer inhomogeneous tissue is verified as a primary and propositional aspect to be explored, which accurately predicts the nonlinear needle deflection and tissue deformation. Investigation of the path planning of flexible needles is recommended to an anatomical or a deformable environment which has characteristics of the tissue deformation. Nonholonomic modeling combined with duty-cycled spinning for needle steering, which tracks the tip position in real time and compensates for the deviation error, is recommended as a future research focus in the steering control in anatomical and deformable environments. Graphical abstract a Insertion force when the needle is inserted into soft tissue. b Needle deflection model when the needle is inserted into soft tissue [68]. c Path planning in anatomical environments [92]. d Duty-cycled spinning incorporated in nonholonomic needle steering [64].

Spatial organization and correlation properties quantify structural changes on mesoscale of parenchymatous plant tissue

Energy Technology Data Exchange (ETDEWEB)

Valous, N. A.; Delgado, A.; Sun, D.-W., E-mail: dawen.sun@ucd.ie [School of Biosystems Engineering, University College Dublin, National University of Ireland, Belfield, Dublin 4, Dublin (Ireland); Drakakis, K. [Complex and Adaptive Systems Laboratory, University College Dublin, National University of Ireland, Belfield, Dublin 4, Dublin (Ireland)

2014-02-14

The study of plant tissue parenchyma's intercellular air spaces contributes to the understanding of anatomy and physiology. This is challenging due to difficulty in making direct measurements of the pore space and the complex mosaic of parenchymatous tissue. The architectural complexity of pore space has shown that single geometrical measurements are not sufficient for characterization. The inhomogeneity of distribution depends not only on the percentage content of phase, but also on how the phase fills the space. The lacunarity morphometric, as multiscale measure, provides information about the distribution of gaps that correspond to degree of spatial organization in parenchyma. Additionally, modern theories have suggested strategies, where the focus has shifted from the study of averages and histograms to the study of patterns in data fluctuations. Detrended fluctuation analysis provides information on the correlation properties of the parenchyma at different spatial scales. The aim is to quantify (with the aid of the aforementioned metrics), the mesostructural changes—that occur from one cycle of freezing and thawing—in the void phase of pome fruit parenchymatous tissue, acquired with X-ray microcomputed tomography. Complex systems methods provide numerical indices and detailed insights regarding the freezing-induced modifications upon the arrangement of cells and voids. These structural changes have the potential to lead to physiological disorders. The work can further stimulate interest for the analysis of internal plant tissue structures coupled with other physico-chemical processes or phenomena.

Spatial organization and correlation properties quantify structural changes on mesoscale of parenchymatous plant tissue

International Nuclear Information System (INIS)

Valous, N. A.; Delgado, A.; Sun, D.-W.; Drakakis, K.

2014-01-01

The study of plant tissue parenchyma's intercellular air spaces contributes to the understanding of anatomy and physiology. This is challenging due to difficulty in making direct measurements of the pore space and the complex mosaic of parenchymatous tissue. The architectural complexity of pore space has shown that single geometrical measurements are not sufficient for characterization. The inhomogeneity of distribution depends not only on the percentage content of phase, but also on how the phase fills the space. The lacunarity morphometric, as multiscale measure, provides information about the distribution of gaps that correspond to degree of spatial organization in parenchyma. Additionally, modern theories have suggested strategies, where the focus has shifted from the study of averages and histograms to the study of patterns in data fluctuations. Detrended fluctuation analysis provides information on the correlation properties of the parenchyma at different spatial scales. The aim is to quantify (with the aid of the aforementioned metrics), the mesostructural changes—that occur from one cycle of freezing and thawing—in the void phase of pome fruit parenchymatous tissue, acquired with X-ray microcomputed tomography. Complex systems methods provide numerical indices and detailed insights regarding the freezing-induced modifications upon the arrangement of cells and voids. These structural changes have the potential to lead to physiological disorders. The work can further stimulate interest for the analysis of internal plant tissue structures coupled with other physico-chemical processes or phenomena

Multiple structure-intrinsic disorder interactions regulate and coordinate Hox protein function

Science.gov (United States)

Bondos, Sarah

During animal development, Hox transcription factors determine fate of developing tissues to generate diverse organs and appendages. Hox proteins are famous for their bizarre mutant phenotypes, such as replacing antennae with legs. Clearly, the functions of individual Hox proteins must be distinct and reliable in vivo, or the organism risks malformation or death. However, within the Hox protein family, the DNA-binding homeodomains are highly conserved and the amino acids that contact DNA are nearly invariant. These observations raise the question: How do different Hox proteins correctly identify their distinct target genes using a common DNA binding domain? One possible means to modulate DNA binding is through the influence of the non-homeodomain protein regions, which differ significantly among Hox proteins. However genetic approaches never detected intra-protein interactions, and early biochemical attempts were hindered because the special features of ``intrinsically disordered'' sequences were not appreciated. We propose the first-ever structural model of a Hox protein to explain how specific contacts between distant, intrinsically disordered regions of the protein and the homeodomain regulate DNA binding and coordinate this activity with other Hox molecular functions.

Interactive physically-based structural modeling of hydrocarbon systems

International Nuclear Information System (INIS)

Bosson, Mael; Grudinin, Sergei; Bouju, Xavier; Redon, Stephane

2012-01-01

Hydrocarbon systems have been intensively studied via numerical methods, including electronic structure computations, molecular dynamics and Monte Carlo simulations. Typically, these methods require an initial structural model (atomic positions and types, topology, etc.) that may be produced using scripts and/or modeling tools. For many systems, however, these building methods may be ineffective, as the user may have to specify the positions of numerous atoms while maintaining structural plausibility. In this paper, we present an interactive physically-based modeling tool to construct structural models of hydrocarbon systems. As the user edits the geometry of the system, atomic positions are also influenced by the Brenner potential, a well-known bond-order reactive potential. In order to be able to interactively edit systems containing numerous atoms, we introduce a new adaptive simulation algorithm, as well as a novel algorithm to incrementally update the forces and the total potential energy based on the list of updated relative atomic positions. The computational cost of the adaptive simulation algorithm depends on user-defined error thresholds, and our potential update algorithm depends linearly with the number of updated bonds. This allows us to enable efficient physically-based editing, since the computational cost is decoupled from the number of atoms in the system. We show that our approach may be used to effectively build realistic models of hydrocarbon structures that would be difficult or impossible to produce using other tools.

Structural Analysis of DNA Interactions with Magnesium Ion Studied by Raman Spectroscopy

OpenAIRE

S. Ponkumar; P. Duraisamy; N. Iyandurai

2011-01-01

Problem statement: In the present study, FT Raman spectroscopy had been used to extend our knowledge about Magnesium ion - DNA interactions at various volume ratios (1:50, 1:20, 1:10 and 1:5). Approach: The analysis of FT Raman data supported the existence of structural specificities in the interaction and also the stability of DNA secondary structure. Results: Results from the Raman spectra clearly indicate that the interaction of Magnesium ion with DNA is mainly through the phosphate groups...

Investigation of structural responses of breakwaters for green water based on fluid-structure interaction analysis

Directory of Open Access Journals (Sweden)

Chi-Seung Lee

2012-06-01

Full Text Available In the present study, the structural response of breakwaters installed on container carriers against green water impact loads was numerically investigated on the basis of the fluid-structure interaction analysis. A series of numerical studies is carried out to induce breakwater collapse under such conditions, whereby a widely accepted fluid-structure interaction analysis technique is adopted to realistically consider the phenomenon of green water impact loads. In addition, the structural behaviour of these breakwaters under green water impact loads is investigated simultaneously throughout the transient analysis. A verification study of the numerical results is performed using data from actual collapse incidents of breakwaters on container carriers. On the basis of the results of a series of numerical analyses, the pressure distribution of green water was accurately predicted with respect to wave mass and velocity. It is expected that the proposed analytical methodology and predicted pressure distribution could be used as a practical guideline for the design of breakwaters on container carriers.

Predicting and validating protein interactions using network structure.

Directory of Open Access Journals (Sweden)

Pao-Yang Chen

2008-07-01

Full Text Available Protein interactions play a vital part in the function of a cell. As experimental techniques for detection and validation of protein interactions are time consuming, there is a need for computational methods for this task. Protein interactions appear to form a network with a relatively high degree of local clustering. In this paper we exploit this clustering by suggesting a score based on triplets of observed protein interactions. The score utilises both protein characteristics and network properties. Our score based on triplets is shown to complement existing techniques for predicting protein interactions, outperforming them on data sets which display a high degree of clustering. The predicted interactions score highly against test measures for accuracy. Compared to a similar score derived from pairwise interactions only, the triplet score displays higher sensitivity and specificity. By looking at specific examples, we show how an experimental set of interactions can be enriched and validated. As part of this work we also examine the effect of different prior databases upon the accuracy of prediction and find that the interactions from the same kingdom give better results than from across kingdoms, suggesting that there may be fundamental differences between the networks. These results all emphasize that network structure is important and helps in the accurate prediction of protein interactions. The protein interaction data set and the program used in our analysis, and a list of predictions and validations, are available at http://www.stats.ox.ac.uk/bioinfo/resources/PredictingInteractions.

A homogenization method for the analysis of a coupled fluid-structure interaction problem with inner solid structure

International Nuclear Information System (INIS)

Sigrist, Jean-Francois; Laine, Christian; Broc, Daniel

2006-01-01

The present paper exposes a homogenization method developed in order to perform the seismic analysis of a nuclear reactor with internal structures modelling and taking fluid structure interaction effects into account. The numerical resolution of fluid-structure interactions has made tremendous progress over the past decades and some applications of the various developed techniques in the industrial field can be found in the literature. As builder of nuclear naval propulsion reactors (ground prototype reactor or embarked reactor on submarines), DCN Propulsion has been working with French nuclear committee CEA for several years in order to integrate fluid-structure analysis in the design stage of current projects. In previous papers modal and seismic analyses of a nuclear reactor with fluid-structure interaction effect were exposed. The studies highlighted the importance of fluid- structure coupling phenomena in the industrial case and focussed on added mass and added stiffness effects. The numerical model used in the previous studies did not take into account the presence of internal structures within the pressure vessel. The present study aims at improving the numerical model of the nuclear reactor to take into account the presence of the internal structures. As the internal structures are periodical within the inner and outer structure of the pressure vessel the proposed model is based on the development of a homogenization method: the presence of internal structure and its effect on the fluid-structure physical interaction is taken into account, although they are not geometrically modeled. The basic theory of the proposed homogenization method is recalled, leading to the modification of fluid-structure coupling operator in the finite element model. The physical consistency of the method is proved by an evaluation of the system mass with the various mass operators (structure, fluid and fluid-structure operators). The method is exposed and validated in a 2 D case

Structural basis for the interaction of the adaptor protein grb14 with activated ras.

Directory of Open Access Journals (Sweden)

Rohini Qamra

Full Text Available Grb14, a member of the Grb7-10-14 family of cytoplasmic adaptor proteins, is a tissue-specific negative regulator of insulin signaling. Grb7-10-14 contain several signaling modules, including a Ras-associating (RA domain, a pleckstrin-homology (PH domain, a family-specific BPS (between PH and SH2 region, and a C-terminal Src-homology-2 (SH2 domain. We showed previously that the RA and PH domains, along with the BPS region and SH2 domain, are necessary for downregulation of insulin signaling. Here, we report the crystal structure at 2.4-Å resolution of the Grb14 RA and PH domains in complex with GTP-loaded H-Ras (G12V. The structure reveals that the Grb14 RA and PH domains form an integrated structural unit capable of binding simultaneously to small GTPases and phosphoinositide lipids. The overall mode of binding of the Grb14 RA domain to activated H-Ras is similar to that of the RA domains of RalGDS and Raf1 but with important distinctions. The integrated RA-PH structural unit in Grb7-10-14 is also found in a second adaptor family that includes Rap1-interacting adaptor molecule (RIAM and lamellipodin, proteins involved in actin-cytoskeleton rearrangement. The structure of Grb14 RA-PH in complex with H-Ras represents the first detailed molecular characterization of tandem RA-PH domains bound to a small GTPase and provides insights into the molecular basis for specificity.

Development of human nervous tissue upon differentiation of embryonic stem cells in three-dimensional culture.

Science.gov (United States)

Preynat-Seauve, Olivier; Suter, David M; Tirefort, Diderik; Turchi, Laurent; Virolle, Thierry; Chneiweiss, Herve; Foti, Michelangelo; Lobrinus, Johannes-Alexander; Stoppini, Luc; Feki, Anis; Dubois-Dauphin, Michel; Krause, Karl Heinz

2009-03-01

Researches on neural differentiation using embryonic stem cells (ESC) require analysis of neurogenesis in conditions mimicking physiological cellular interactions as closely as possible. In this study, we report an air-liquid interface-based culture of human ESC. This culture system allows three-dimensional cell expansion and neural differentiation in the absence of added growth factors. Over a 3-month period, a macroscopically visible, compact tissue developed. Histological coloration revealed a dense neural-like neural tissue including immature tubular structures. Electron microscopy, immunochemistry, and electrophysiological recordings demonstrated a dense network of neurons, astrocytes, and oligodendrocytes able to propagate signals. Within this tissue, tubular structures were niches of cells resembling germinal layers of human fetal brain. Indeed, the tissue contained abundant proliferating cells expressing markers of neural progenitors. Finally, the capacity to generate neural tissues on air-liquid interface differed for different ESC lines, confirming variations of their neurogenic potential. In conclusion, this study demonstrates in vitro engineering of a human neural-like tissue with an organization that bears resemblance to early developing brain. As opposed to previously described methods, this differentiation (a) allows three-dimensional organization, (b) yields dense interconnected neural tissue with structurally and functionally distinct areas, and (c) is spontaneously guided by endogenous developmental cues.

Structured Light-Matter Interactions Enabled By Novel Photonic Materials

Energy Technology Data Exchange (ETDEWEB)

Litchinitser, Natalia [Univ. at Buffalo, NY (United States); Feng, Liang [Univ. at Buffalo, NY (United States)

2017-05-02

The synergy of complex materials and complex light is expected to add a new dimension to the science of light and its applications [1]. The goal of this program is to investigate novel phenomena emerging at the interface of these two branches of modern optics. While metamaterials research was largely focused on relatively “simple” linearly or circularly polarized light propagation in “complex” nanostructured, carefully designed materials with properties not found in nature, many singular optics studies addressed “complex” structured light transmission in “simple” homogeneous, isotropic, nondispersive transparent media, where both spin and orbital angular momentum are independently conserved. However, if both light and medium are complex so that structured light interacts with a metamaterial whose optical materials properties can be designed at will, the spin or angular momentum can change, which leads to spin-orbit interaction and many novel optical phenomena that will be studied in the proposed project. Indeed, metamaterials enable unprecedented control over light propagation, opening new avenues for using spin and quantum optical phenomena, and design flexibility facilitating new linear and nonlinear optical properties and functionalities, including negative index of refraction, magnetism at optical frequencies, giant optical activity, subwavelength imaging, cloaking, dispersion engineering, and unique phase-matching conditions for nonlinear optical interactions. In this research program we focused on structured light-matter interactions in complex media with three particularly remarkable properties that were enabled only with the emergence of metamaterials: extreme anisotropy, extreme material parameters, and magneto-electric coupling–bi-anisotropy and chirality.

Evaluation of soil-structure interaction for structures subjected to earthquake loading with different types of foundation

Directory of Open Access Journals (Sweden)

Elwi Mohammed

2018-01-01

Full Text Available However though the structures are supported on soil, most of the designers do not consider the soil structure interaction and its subsequent effect on structure during an earthquake. Different soil properties can affect seismic waves as they pass through a soil layer. When a structure is subjected to an earthquake excitation, it interacts the foundation and soil, and thus changes the motion of the ground. It means that the movement of the whole ground structure system is influenced by type of soil as well as by the type of structure. Tall buildings are supposed to be of engineered construction in sense that they might have been analyzed and designed to meet the provision of relevant codes of practice and building bye-laws. IS 1893: 2002 “Criteria for Earthquake Resistant Design of Structures” gives response spectrum for different types of soil such as hard, medium and soft. An attempt has been made in this paper to study the effect of Soil-structure interaction on multi storeyed buildings with various foundation systems. Also to study the response of buildings subjected to seismic forces with Rigid and Flexible foundations. Multi storeyed buildings with fixed and flexible support subjected to seismic forces were analyzed under different soil conditions like hard, medium and soft. The buildings were analyzed by Response spectrum method using software SAP2000. The response of building frames such as Lateral deflection, Story drift, Base shear, Axial force and Column moment values for all building frames were presented in this paper.

Stiffness and Damping related to steady state soil-structure Interaction of monopiles

DEFF Research Database (Denmark)

Bayat, Mehdi

The present thesis concerns soil–structure interaction affecting the dynamic structural response of offshore wind turbines with focus on soil stiffness and seepage damping due to pore water flow generated by cyclic motion of a monopile. The thesis aims to improve modelling of the dynamic...... and dashpots. An appropriate model based on considering the effect of dynamic behaviour of soil–structure interaction has been explored. In this regard, the coupled equations for porous media have been employed in order to account for soil deformation as well as pore pressure. The effects of drained versus...... undrained behaviour of the soil and the impact of this behaviour on the stiffness and damping related to soil–structure interaction at different load frequencies have been illustrated. Based on the poroelastic and Kelvin models, more realistic dynamic properties have been presented by considering the effect...

A Map of General and Specialized Chromatin Readers in Mouse Tissues Generated by Label-free Interaction Proteomics

DEFF Research Database (Denmark)

Eberl, H.C.; Mann, M.; Spruijt, C.G.

2013-01-01

Posttranslational modifications on core histones can serve as binding scaffolds for chromatin-associated proteins. Proteins that specifically bind to or "read" these modifications were previously identified in mass spectrometry-based proteomics screens based on stable isotope-labeling in cell lines...... the chromatin interaction landscape in mouse tissues, our workflow can be used for peptides with different modifications and cell types of any organism....

Testing the Hypothesis of Biofilm as a Source for Soft Tissue and Cell-Like Structures Preserved in Dinosaur Bone

Science.gov (United States)

2016-01-01

Recovery of still-soft tissue structures, including blood vessels and osteocytes, from dinosaur bone after demineralization was reported in 2005 and in subsequent publications. Despite multiple lines of evidence supporting an endogenous source, it was proposed that these structures arose from contamination from biofilm-forming organisms. To test the hypothesis that soft tissue structures result from microbial invasion of the fossil bone, we used two different biofilm-forming microorganisms to inoculate modern bone fragments from which organic components had been removed. We show fundamental morphological, chemical and textural differences between the resultant biofilm structures and those derived from dinosaur bone. The data do not support the hypothesis that biofilm-forming microorganisms are the source of these structures. PMID:26926069

The influence of freezing and tissue porosity on the material properties of vegetable tissues

International Nuclear Information System (INIS)

Ralfs, Julie D.

2002-01-01

Tissue porosity and fluid flow have been shown to be important parameters affecting the mechanical and sensorial behaviour of edible plant tissues. The quantity of fluid and the manner with which it was released on compression of the plant tissue were also important regarding the sensory perception and a good indication of any structural damage resulting from freezing, for example. Potato, carrot and Chinese water chestnut were used to study the effects freezing has on model plant tissues. Mechanical and structural measurements of the plant tissue were correlated with sensory analysis. Conventional freezing was shown to cause severe structural damage predominantly in the form of cavities between or through cells, resulting in decreases in mechanical strength and stiffness, and samples that were perceived in the mouth as 'soft' and 'wet'. The location and size of the cavities formed from ice crystals, depended on the particular plant tissue being frozen, the processing it was subjected to prior to freezing, the size of the sample and the cooling regime employed to freeze the tissue. Cavitation in the tissue resulted in an increase in tissue porosity, which enabled fluid to flow more easily from the tissue on compression, thus affecting the mechanical properties and sensory perception. Freezing damage to plant tissues was shown to be reduced, and sometimes prevented, when active antifreeze proteins (AFPs) were introduced into the tissues by vacuum infiltration or transformation and the tissue was frozen at a suitable cooling rate. Theoretical modelling was applied to the fluid flow and porosity data to test the validity of the models and to subsequently predict the mechanical behaviour of potato from the structural properties of the tissue. (author)

Seismic evaluation of a cooling water reservoir facility including fluid-structure and soil-structure interaction effects

International Nuclear Information System (INIS)

Kabir, A.F.; Maryak, M.E.

1991-01-01

Seismic analyses and structural evaluations were performed for a cooling water reservoir of a nuclear reactor facility. The horizontal input seismic motion was the NRC Reg. guide 1.60 spectrum shape anchored at 0.20g zero period acceleration. Vertical input was taken as two-thirds of the horizontal input. Soil structure interaction and hydrodynamic effects were addressed in the seismic analyses. Uncertainties in the soil properties were accounted for by considering three soil profiles. Two 2-dimensional SSI models and a 3-dimensional static model. Representing different areas of the reservoir structures were developed and analyzed to obtain seismic forces and moments, and accelerations at various locations. The results included in this paper indicated that both hydrodynamic and soil-structure interaction effects are significant contributors to the seismic responses of the water-retaining walls of the reservoir

Modeling light–tissue interaction in optical coherence tomography systems

DEFF Research Database (Denmark)

Andersen, Peter E.; Jørgensen, Thomas Martini; Thrane, Lars

2015-01-01

Optical coherence tomography (OCT) performs high-resolution, cross-sectional tomographic imaging of the internal tissue microstructure by measuring backscattered or backreflected light. The scope of this chapter is to present analytical and numerical models that are able to describe light-tissue ...

[Changes in the secondary and tertiary structure of serum albumin in interactions with ligands of various structures].

Science.gov (United States)

Trinus, F P; Braver-Chernobul'skaia, B S; Luĭk, A I; Boldeskul, A E; Velichko, A N

1984-01-01

High affinity interactions between blood serum albumin and five substances of various chemical structure, exhibiting distinct physiological activity, were accompanied by alterations in the protein tertiary structure, while the albumin secondary structure was involved in conformational transformation after less effective affinity binding.

Smart Polymeric Hydrogels for Cartilage Tissue Engineering: A Review on the Chemistry and Biological Functions.

Science.gov (United States)

Eslahi, Niloofar; Abdorahim, Marjan; Simchi, Abdolreza

2016-11-14

Stimuli responsive hydrogels (SRHs) are attractive bioscaffolds for tissue engineering. The structural similarity of SRHs to the extracellular matrix (ECM) of many tissues offers great advantages for a minimally invasive tissue repair. Among various potential applications of SRHs, cartilage regeneration has attracted significant attention. The repair of cartilage damage is challenging in orthopedics owing to its low repair capacity. Recent advances include development of injectable hydrogels to minimize invasive surgery with nanostructured features and rapid stimuli-responsive characteristics. Nanostructured SRHs with more structural similarity to natural ECM up-regulate cell-material interactions for faster tissue repair and more controlled stimuli-response to environmental changes. This review highlights most recent advances in the development of nanostructured or smart hydrogels for cartilage tissue engineering. Different types of stimuli-responsive hydrogels are introduced and their fabrication processes through physicochemical procedures are reported. The applications and characteristics of natural and synthetic polymers used in SRHs are also reviewed with an outline on clinical considerations and challenges.

Fluid-structure interaction simulation of floating structures interacting with complex, large-scale ocean waves and atmospheric turbulence with application to floating offshore wind turbines

Science.gov (United States)

Calderer, Antoni; Guo, Xin; Shen, Lian; Sotiropoulos, Fotis

2018-02-01

We develop a numerical method for simulating coupled interactions of complex floating structures with large-scale ocean waves and atmospheric turbulence. We employ an efficient large-scale model to develop offshore wind and wave environmental conditions, which are then incorporated into a high resolution two-phase flow solver with fluid-structure interaction (FSI). The large-scale wind-wave interaction model is based on a two-fluid dynamically-coupled approach that employs a high-order spectral method for simulating the water motion and a viscous solver with undulatory boundaries for the air motion. The two-phase flow FSI solver is based on the level set method and is capable of simulating the coupled dynamic interaction of arbitrarily complex bodies with airflow and waves. The large-scale wave field solver is coupled with the near-field FSI solver with a one-way coupling approach by feeding into the latter waves via a pressure-forcing method combined with the level set method. We validate the model for both simple wave trains and three-dimensional directional waves and compare the results with experimental and theoretical solutions. Finally, we demonstrate the capabilities of the new computational framework by carrying out large-eddy simulation of a floating offshore wind turbine interacting with realistic ocean wind and waves.

High frequency flow-structural interaction in dense subsonic fluids

Science.gov (United States)

Liu, Baw-Lin; Ofarrell, J. M.

1995-01-01

Prediction of the detailed dynamic behavior in rocket propellant feed systems and engines and other such high-energy fluid systems requires precise analysis to assure structural performance. Designs sometimes require placement of bluff bodies in a flow passage. Additionally, there are flexibilities in ducts, liners, and piping systems. A design handbook and interactive data base have been developed for assessing flow/structural interactions to be used as a tool in design and development, to evaluate applicable geometries before problems develop, or to eliminate or minimize problems with existing hardware. This is a compilation of analytical/empirical data and techniques to evaluate detailed dynamic characteristics of both the fluid and structures. These techniques have direct applicability to rocket engine internal flow passages, hot gas drive systems, and vehicle propellant feed systems. Organization of the handbook is by basic geometries for estimating Strouhal numbers, added mass effects, mode shapes for various end constraints, critical onset flow conditions, and possible structural response amplitudes. Emphasis is on dense fluids and high structural loading potential for fatigue at low subsonic flow speeds where high-frequency excitations are possible. Avoidance and corrective measure illustrations are presented together with analytical curve fits for predictions compiled from a comprehensive data base.

Water's Interfacial Hydrogen Bonding Structure Reveals the Effective Strength of Surface-Water Interactions.

Science.gov (United States)

Shin, Sucheol; Willard, Adam P

2018-06-05

We combine all-atom molecular dynamics simulations with a mean field model of interfacial hydrogen bonding to analyze the effect of surface-water interactions on the structural and energetic properties of the liquid water interface. We show that the molecular structure of water at a weakly interacting ( i.e., hydrophobic) surface is resistant to change unless the strength of surface-water interactions are above a certain threshold. We find that below this threshold water's interfacial structure is homogeneous and insensitive to the details of the disordered surface, however, above this threshold water's interfacial structure is heterogeneous. Despite this heterogeneity, we demonstrate that the equilibrium distribution of molecular orientations can be used to quantify the energetic component of the surface-water interactions that contribute specifically to modifying the interfacial hydrogen bonding network. We identify this specific energetic component as a new measure of hydrophilicity, which we refer to as the intrinsic hydropathy.

Structure formation in bis(terpyridine) derivative adlayers: molecule-substrate versus molecule-molecule interactions.

Science.gov (United States)

Hoster, Harry E; Roos, Matthias; Breitruck, Achim; Meier, Christoph; Tonigold, Katrin; Waldmann, Thomas; Ziener, Ulrich; Landfester, Katharina; Behm, R Jürgen

2007-11-06

The influence of the substrate and the deposition conditions-vapor deposition versus deposition from solution-on the structures formed upon self-assembly of deposited bis(terpyridine) derivative (2,4'-BTP) monolayers on different hexagonal substrates, including highly oriented pyrolytic graphite (HOPG), Au(111), and (111)-oriented Ag thin films, was investigated by high-resolution scanning tunneling microscopy and by model calculations of the intermolecular energies and the lateral corrugation of the substrate-adsorbate interaction. Similar quasi-quadratic network structures with almost the same lattice constants obtained on all substrates are essentially identical to the optimum configuration expected from an optimization of the adlayer structure with C-H...N-type bridging bonds as a structure-determining factor, which underlines a key role of the intermolecular interactions in adlayer order. Slight distortions from the optimum values to form commensurate adlayer structures on the metal substrates and the preferential orientation of the adlayer with respect to the substrate are attributed to the substrate-adsorbate interactions, specifically, the lateral corrugation in the substrate-adsorbate interaction upon lateral displacement and rotation of the adsorbed BTP molecules. The fact that similar adlayer structures are obtained on HOPG under ultrahigh vacuum conditions (solid|gas interface) and on HOPG in trichlorobenzene (solid|liquid interface) indicates that the intermolecular interactions are not severely affected by the solvent.

A role for iron and oxygen chemistry in preserving soft tissues, cells and molecules from deep time.

Science.gov (United States)

Schweitzer, Mary H; Zheng, Wenxia; Cleland, Timothy P; Goodwin, Mark B; Boatman, Elizabeth; Theil, Elizabeth; Marcus, Matthew A; Fakra, Sirine C

2014-01-22

The persistence of original soft tissues in Mesozoic fossil bone is not explained by current chemical degradation models. We identified iron particles (goethite-αFeO(OH)) associated with soft tissues recovered from two Mesozoic dinosaurs, using transmission electron microscopy, electron energy loss spectroscopy, micro-X-ray diffraction and Fe micro-X-ray absorption near-edge structure. Iron chelators increased fossil tissue immunoreactivity to multiple antibodies dramatically, suggesting a role for iron in both preserving and masking proteins in fossil tissues. Haemoglobin (HB) increased tissue stability more than 200-fold, from approximately 3 days to more than two years at room temperature (25°C) in an ostrich blood vessel model developed to test post-mortem 'tissue fixation' by cross-linking or peroxidation. HB-induced solution hypoxia coupled with iron chelation enhances preservation as follows: HB + O2 > HB - O2 > -O2 > +O2. The well-known O2/haeme interactions in the chemistry of life, such as respiration and bioenergetics, are complemented by O2/haeme interactions in the preservation of fossil soft tissues.

Solving RNA's structural secrets: interaction with antibodies and crystal structure of a nuclease resistant RNA

International Nuclear Information System (INIS)

Wallace, S.T.

1998-10-01

This Ph.D. thesis concerns the structural characterization of RNA. The work is split into two sections: 1) in vitro selection and characterization of RNAs which bind antibiotics and 2) crystal structure of a nuclease resistant RNA molecule used in antisense applications. Understanding antibiotic-RNA interactions is crucial in aiding rational drug design. We were interested in studying antibiotic interactions with RNAs small enough to characterize at the molecular and possibly at the atomic level. In order to do so, we previously performed in vitro selection to find small RNAs which bind to the peptide antibiotic viomycin and the aminoglycoside antibiotic streptomycin. The characterization of the viomycin-binding RNAs revealed the necessity of a pseudoknot-structure in order to interact with the antibiotic. The RNAs which were selected to interact with streptomycin require the presence of magnesium to bind the antibiotic. One of the RNAs, upon interacting with streptomycin undergoes a significant conformational change spanning the entire RNA sequence needed to bind the antibiotic. In a quest to design oligodeoxynucleotides (ODNs) which are able to specifically bid and inactivate the mRNA of a gene, it is necessary to fulfill two criteria: 1) increase binding affinity between the ODN and the target RNA and 2) increase the ODN's resistance to nuclease degradation. An ODN with an aminopropyl modification at the 2' position of its ribose has emerged as the most successful candidate at fulfilling both criteria. It is the most nuclease resistant modification known to date. We were interested in explaining how this modification is able to circumvent degradation by nucleases. A dodecamer containing a single 2'-O-aminopropyl modified nucleotide was crystallized and the structure was solved to a resolution of 1.6 A. In an attempt to explain the nuclease resistance, the crystal coordinates were modeled into the active exonuclease site of DNA polymerase I. We propose the

Advances in soil-structure interaction studies

International Nuclear Information System (INIS)

Maheshwari, B.K.

2011-01-01

It is utmost important that lifeline infrastructures (such as bridges, hospitals, power plants, dams etc.) are safe and functional during earthquakes as damage or collapse of these structures may have far reaching implications. A lifeline's failure may hamper relief and rescue operations required just after an earthquake and secondly its indirect economical losses may be very severe. Therefore, safety of these structures during earthquakes is vital. Further, damage to nuclear facilities during earthquake may lead to disaster. These structures should be designed adequately taking into account all the important issues. Soil-Structure Interaction (SSI) is one of the design issues, which is often overlooked and even in some cases ignored. The effects of dynamic SSI are well understood and practiced in the nuclear power industry (for large foundations of the nuclear containment structures) since sixties. However, in last decade, there are many advances in techniques of SSI and those need to be incorporated in practice. Failures of many structures occurred during the 1989 Loma Prieta and 1994 Northridge, California earthquakes and the 1995 Kobe, Japan earthquake due to SSI or a related issue. Many jetties had failed in Andaman and Nicobar islands due to Sumatra earthquake and ensuing tsunamis. It is because of this recent experience that the importance of SSI on dynamic response of structures during earthquakes has been fully realized. General belief that the SSI effects are always beneficial for the structure is not correct. Some cases have been presented where it is shown that SSI effects are detrimental for the stability of the structure. This paper addresses the effects of dynamic SSI on the response of the structures and explains its importance. Further advances in SSI studies have been discussed

Structural and mechanical design of tissue interfaces in the giant reed Arundo donax.

Science.gov (United States)

Rüggeberg, Markus; Burgert, Ingo; Speck, Thomas

2010-03-06

The culms of the giant reed Arundo donax represent slender tube-like structures. Several nodes along the culm, a ring of sclerenchymatous fibres in the periphery of the culm wall and numerous isolated vascular bundles enclosed by fibre rings in the culm wall function as stiffening elements. The bundles are embedded in lignified parenchyma. Micromechanical analysis indicated differences in stiffness between the individual tissues of more than one order of magnitude. In case of abrupt transitions in stiffness at the interfaces, stress discontinuities arise under dynamic loads. This eventually leads to critical shear stresses at cell ends, and culm failure may be initiated at these points. Pronounced mechanical differences between individual tissues can be compromised by gradual transitions at their interfaces. Ultrastructural and spectroscopic investigations with high spatial resolution revealed a gradual transition of cell parameters (cell wall area fraction and cell length). However, cell wall parameters (cellulose microfibril angle and lignin content) showed abrupt transitions or remained almost constant across the interfaces between various tissues. The design principles found at the interfaces between tissues in the culm walls of A. donax are discussed as an adaptation strategy to mechanical loads at different levels of hierarchy.

Uncertainty in soil-structure interaction analysis arising from differences in analytical techniques

International Nuclear Information System (INIS)

Maslenikov, O.R.; Chen, J.C.; Johnson, J.J.

1982-07-01

This study addresses uncertainties arising from variations in different modeling approaches to soil-structure interaction of massive structures at a nuclear power plant. To perform a comprehensive systems analysis, it is necessary to quantify, for each phase of the traditional analysis procedure, both the realistic seismic response and the uncertainties associated with them. In this study two linear soil-structure interaction techniques were used to analyze the Zion, Illinois nuclear power plant: a direct method using the FLUSH computer program and a substructure approach using the CLASSI family of computer programs. In-structure response from two earthquakes, one real and one synthetic, was compared. Structure configurations from relatively simple to complicated multi-structure cases were analyzed. The resulting variations help quantify uncertainty in structure response due to analysis procedures

Monte Carlo simulation of the interaction of X-ray spectrum with human tissue, in the energies range of diagnostic radiology

International Nuclear Information System (INIS)

Cayllahua Q, L. F.; Apaza V, G.; Vega R, J. L.

2015-10-01

Full text: This paper is an approach to an increasingly complete knowledge about the nature of the processes that occur during a simple examination of radiological diagnosis; know as X-rays are produced and how they will put their energy into the tissue of patients when they are subjected to an examination of radiological diagnosis. First, using the MCNP code an X-rays tube was simulated, where electrons are emitted from a filament (cathode) which travel a certain distance with a certain kinetic energy and then be stopped suddenly in the tungsten target. The X-rays emitted as a result of this interaction, are previously filtered through the inherent filter of Pyrex glass and then by a thin aluminum foil before quantification as an X-rays spectrum. 6 spectra (for 60, 80, 100, 120 and 140 KeV) were obtained. Second, using the Penelope code was simulated the interaction of the X-rays spectrum, obtained in the first part with human tissue, putting as simile of human tissue water phantoms of different thicknesses. As final result: dose of energy deposited (in 2 and 3-dimensional) and reflected, absorbed and transmitted photons spectra. (Author)

Structure and interactions of the human programmed cell death 1 receptor.

Science.gov (United States)

Cheng, Xiaoxiao; Veverka, Vaclav; Radhakrishnan, Anand; Waters, Lorna C; Muskett, Frederick W; Morgan, Sara H; Huo, Jiandong; Yu, Chao; Evans, Edward J; Leslie, Alasdair J; Griffiths, Meryn; Stubberfield, Colin; Griffin, Robert; Henry, Alistair J; Jansson, Andreas; Ladbury, John E; Ikemizu, Shinji; Carr, Mark D; Davis, Simon J

2013-04-26

PD-1, a receptor expressed by T cells, B cells, and monocytes, is a potent regulator of immune responses and a promising therapeutic target. The structure and interactions of human PD-1 are, however, incompletely characterized. We present the solution nuclear magnetic resonance (NMR)-based structure of the human PD-1 extracellular region and detailed analyses of its interactions with its ligands, PD-L1 and PD-L2. PD-1 has typical immunoglobulin superfamily topology but differs at the edge of the GFCC' sheet, which is flexible and completely lacks a C" strand. Changes in PD-1 backbone NMR signals induced by ligand binding suggest that, whereas binding is centered on the GFCC' sheet, PD-1 is engaged by its two ligands differently and in ways incompletely explained by crystal structures of mouse PD-1 · ligand complexes. The affinities of these interactions and that of PD-L1 with the costimulatory protein B7-1, measured using surface plasmon resonance, are significantly weaker than expected. The 3-4-fold greater affinity of PD-L2 versus PD-L1 for human PD-1 is principally due to the 3-fold smaller dissociation rate for PD-L2 binding. Isothermal titration calorimetry revealed that the PD-1/PD-L1 interaction is entropically driven, whereas PD-1/PD-L2 binding has a large enthalpic component. Mathematical simulations based on the biophysical data and quantitative expression data suggest an unexpectedly limited contribution of PD-L2 to PD-1 ligation during interactions of activated T cells with antigen-presenting cells. These findings provide a rigorous structural and biophysical framework for interpreting the important functions of PD-1 and reveal that potent inhibitory signaling can be initiated by weakly interacting receptors.

Earthquake response analyses of soil-structure system considering kinematic interaction

International Nuclear Information System (INIS)

Murakami, H.; Yokono, K.; Miura, S.; Ishii, K.

1985-01-01

Improvement of soil-structure interaction analysis has been one of major concerns in earthquake engineering field, especially in nuclear industries, to evaluate the safety of structure accurately under earthquake events. This research aims to develop a rational analytical tool which considers effect of the 'kinematic interaction' satisfactory with a proposed simple low-pass filter. In this paper, first the effect of the kinematic interaction is investigated based on earthquake response analysis of a reactor building using the practical design models: the spring-mass-dashpot system and the 'lattice model', in which a building and soil medium are modeled by a system of lumped masses. Next, the filter is developed based on parametrical studies with various sizes of depth and width of foundations embedded in two-layers soil, which represents more general soil condition in practical designs compared with a homogeneous soil medium. (orig.)

PTPIP51: A New Interaction Partner of the Insulin Receptor and PKA in Adipose Tissue

Directory of Open Access Journals (Sweden)

M. A. Bobrich

2013-01-01

Full Text Available Aims. Our previous experiments revealed an association of PTPIP51 (protein tyrosine phosphatase interacting protein 51 with the insulin signalling pathway through PTP1B and 14-3-3beta. We aimed to clarify the role of PTPIP51 in adipocyte metabolism. Methods. Four groups of ten C57Bl/6 mice each were used. Two groups were fed a standard diet; two groups were fed a high-fat diet. Two groups (one high-fat diet and one standard diet were submitted to endurance training, while the remaining two groups served as untrained control groups. After ten weeks, we measured glucose tolerance of the mice. Adipose tissue samples were analyzed by immunofluorescence and Duolink proximity ligation assay to quantify interactions of PTPIP51 with either insulin receptor (IR or PKA. Results. PTPIP51 and the IR and PTPIP51 and PKA, respectively, were colocalized in all groups. Standard diet animals that were submitted to endurance training showed low PTPIP51-IR and PTPIP51-PKA interactions. The interaction levels of both the IR and PKA differed between the feeding and training groups. Conclusion. PTPIP51 might serve as a linking protein in adipocyte metabolism by connecting the IR-triggered lipogenesis with the PKA-dependent lipolysis. PTPIP51 interacts with both proteins, therefore being a potential gateway for the cooperation of both pathways.

Role of radiation damping in the impedance function approach to soil-structure interaction analysis

International Nuclear Information System (INIS)

1980-05-01

This report was prepared at the request of the Lawrence Livermore Laboratory (LLL) to provide background information for analyzing soil-structure interaction by the frequency-independent impedance function approach. LLL is conducting such analyses as part of its seismic review of selected operating plants under the Systematic Evaluation Program for the US Nuclear Regulatory Commission. The analytical background and basic assumptionsof the impedance function theory are briefly reviewed, and the role of radiation damping in soil-structure interaction analysis is discussed. The validity of modeling soil-structure interaction by using frequency-independent functions is evaluated based on data from several field tests. Finally, the recommended procedures for performing soil-structure interaction analyses are discussed with emphasis on the modal superposition method

Human dental enamel and dentin structural effects after Er:YAG laser irradiation.

Science.gov (United States)

Lima, Darlon Martíns; Tonetto, Mateus Rodrigues; de Mendonça, Adriano Augusto Melo; Elossais, André Afif; Saad, José Roberto Cury; de Andrade, Marcelo Ferrarezi; Pinto, Shelon Cristina Souza; Bandéca, Matheus Coelho

2014-05-01

Ideally projected to be applied on soft tissues, infrared lasers were improved by restorative dentistry to be used in hard dental tissues cavity preparations--namely enamel and dentin. This paper evidentiates the relevant aspects of infrared Erbium laser's action mechanism and its effects, and characterizes the different effects deriving from the laser's beams emission. The criteria for use and selection of optimal parameters for the correct application of laser systems and influence of supporting factors on the process, such as water amount and its presence in the ablation process, protection exerted by the plasma shielding and structural factors, which are indispensable in dental tissues cavity preparation related to restorative technique, are subordinated to optical modifications caused by the interaction of the energy dissipated by these laser light emission systems in the targeted tissue substrate. Differences in the action of infrared Erbium laser system in regard to the nature of the ablation process and variations on the morphological aspects observed in the superficial structure of the target tissue irradiated, may be correlated to the structural optical modifications of the substrate produced by an interaction of the energy propagated by laser systems.

Many Body Structure of Strongly Interacting Systems

CERN Document Server

Arenhövel, Hartmuth; Drechsel, Dieter; Friedrich, Jörg; Kaiser, Karl-Heinz; Walcher, Thomas; Symposium on 20 Years of Physics at the Mainz Microtron MAMI

2006-01-01

This carefully edited proceedings volume provides an extensive review and analysis of the work carried out over the past 20 years at the Mainz Microtron (MAMI). This research centered around the application of Quantum Chromodynamics in the strictly nonperturbative regime at hadronic scales of about 1 fm. Due to the many degrees of freedom in hadrons at this scale the leitmotiv of this research is "Many body structure of strongly interacting systems". Further, an outlook on the research with the forthcoming upgrade of MAMI is given. This volume is an authoritative source of reference for everyone interested in the field of the electro-weak probing of the structure of hadrons.

A sensitivity study for soil-structure interaction

International Nuclear Information System (INIS)

Kunar, R.R.; White, D.C.; Ashdown, M.J.; Waker, C.H.; Daintith, D.

1981-01-01

This paper presents the results of a study in which the sensitivity of a containment building typical of one type of construction used in the nuclear reprocessing industry is examined for variations in soil data and seismic input. A number of dynamic soil-structure interaction analyses are performed on the structure and its foundations using parametric variations of the depth of soil layer, soil material properties, bedrock flexibility, seismic input location and time and phase characteristics of the earthquake excitation. Previous experience is combined with the results obtained to gneralise conclusions regarding the conditions under which each of the uncertainties will be significant enough to merit proper statistical treatment. (orig.)

Amyloid structure exhibits polymorphism on multiple length scales in human brain tissue

Energy Technology Data Exchange (ETDEWEB)

Liu, Jiliang; Costantino, Isabel; Venugopalan, Nagarajan; Fischetti, Robert F.; Hyman, Bradley; Frosch, Matthew; Gomez-Isla, Teresa; Makowski, Lee

2016-09-15

Although aggregation of Aβ amyloid fibrils into plaques in the brain is a hallmark of Alzheimer's Disease (AD), the correlation between amyloid burden and severity of symptoms is weak. One possible reason is that amyloid fibrils are structurally polymorphic and different polymorphs may contribute differentially to disease. However, the occurrence and distribution of amyloid polymorphisms in human brain is poorly documented. Here we seek to fill this knowledge gap by using X-ray microdiffraction of histological sections of human tissue to map the abundance, orientation and structural heterogeneities of amyloid within individual plaques; among proximal plaques and in subjects with distinct clinical histories. A 5 µ x-ray beam was used to generate diffraction data with each pattern arising from a scattering volume of only ~ 450 µ3 , making possible collection of dozens to hundreds of diffraction patterns from a single amyloid plaque. X-ray scattering from these samples exhibited all the properties expected for scattering from amyloid. Amyloid distribution was mapped using the intensity of its signature 4.7 Å reflection which also provided information on the orientation of amyloid fibrils across plaques. Margins of plaques exhibited a greater degree of orientation than cores and orientation around blood vessels frequently appeared tangential. Variation in the structure of Aβ fibrils is reflected in the shape of the 4.7 Å peak which usually appears as a doublet. Variations in this peak correspond to differences between the structure of amyloid within cores of plaques and at their periphery. Examination of tissue from a mismatch case - an individual with high plaque burden but no overt signs of dementia at time of death - revealed a diversity of structure and spatial distribution of amyloid that is distinct from typical AD cases. We demonstrate the existence of structural polymorphisms among amyloid within and among plaques of a single individual and suggest

Sex-specific metabolic interactions between liver and adipose tissue in MCD diet-induced non-alcoholic fatty liver disease.

Science.gov (United States)

Lee, Yun-Hee; Kim, Sou Hyun; Kim, Sang-Nam; Kwon, Hyun-Jung; Kim, Jeong-Dong; Oh, Ji Youn; Jung, Young-Suk

2016-07-26

Higher susceptibility to metabolic disease in male exemplifies the importance of sexual dimorphism in pathogenesis. We hypothesized that the higher incidence of non-alcoholic fatty liver disease in males involves sex-specific metabolic interactions between liver and adipose tissue. In the present study, we used a methionine-choline deficient (MCD) diet-induced fatty liver mouse model to investigate sex differences in the metabolic response of the liver and adipose tissue. After 2 weeks on an MCD-diet, fatty liver was induced in a sex-specific manner, affecting male mice more severely than females. The MCD-diet increased lipolytic enzymes in the gonadal white adipose tissue (gWAT) of male mice, whereas it increased expression of uncoupling protein 1 and other brown adipocyte markers in the gWAT of female mice. Moreover, gWAT from female mice demonstrated higher levels of oxygen consumption and mitochondrial content compared to gWAT from male mice. FGF21 expression was increased in liver tissue by the MCD diet, and the degree of upregulation was significantly higher in the livers of female mice. The endocrine effect of FGF21 was responsible, in part, for the sex-specific browning of gonadal white adipose tissue. Collectively, these data demonstrated that distinctively female-specific browning of white adipose tissue aids in protecting female mice against MCD diet-induced fatty liver disease.

Soil-structure interaction for transient loads due to safety relief valve discharges

International Nuclear Information System (INIS)

Tseng, W.S.; Tsai, N.C.

1978-01-01

Dynamic responses of BWR Mark II containment structures subjected to axisymmetric transient pressure loadings due to simultaneous safety relief valve discharges were investigated using finite element analysis, including the soil-structure interaction effect. To properly consider the soil-structure interaction effect, a simplified lumped parameter foundation model and axisymmetric finite element foundation model with viscous boundary impedance are used. Analytical results are presented to demonstrate the effectiveness of the simplified foundation model and to exhibit the dynamic response behavior of the structure as the transient loading frequency and the foundation rigidity vary. The impact of the dynamic structural response due to this type of loading on the equipment design is also discussed. (Auth.)

Performance of partitioned procedures in fluid-structure interaction

NARCIS (Netherlands)

Degroote, J.; Haelterman, R.; Annerel, S.; Bruggeman, P.J.; Vierendeels, J.

2010-01-01

Partitioned simulations of fluid–structure interaction can be solved for the interface’s position with Newton–Raphson iterations but obtaining the exact Jacobian is impossible if the solvers are "black boxes". It is demonstrated that only an approximate Jacobian is needed, as long as it describes

A large-scale soil-structure interaction experiment: Design and construction

International Nuclear Information System (INIS)

Tang, H.T.; Tang, Y.K.; Stepp, J.C.; Wall, I.B.; Lin, E.; Cheng, S.C.; Lee, S.K.

1989-01-01

This paper describes the design and construction phase of the Large-Scale Soil-Structure Interaction Experiment project jointly sponsored by EPRI and Taipower. The project has two objectives: 1. to obtain an earthquake database which can be used to substantiate soil-structure interaction (SSI) models and analysis methods; and 2. to quantify nuclear power plant reactor containment and internal components seismic margin based on earthquake experience data. These objectives were accomplished by recording and analyzing data from two instrumented, scaled down, reinforced concrete containment structures during seismic events. The two model structures are sited in a high seismic region in Taiwan (SMART-1). A strong-motion seismic array network is located at the site. The containment models (1/4- and 1/12-scale) were constructed and instrumented specially for this experiment. Construction was completed and data recording began in September 1985. By November 1986, 18 strong motion earthquakes ranging from Richter magnitude 4.5 to 7.0 were recorded. (orig./HP)

Development of the tube bundle structure for fluid-structure interaction analysis model

International Nuclear Information System (INIS)

Yoon, Kyung Ho; Kim, Jae Yong

2010-02-01

Tube bundle structures within a Boiler or heat exchanger are laid the fluid-structure, thermal-structure and fluid-thermal-structure coupled boundary condition. In these complicated boundary conditions, Fluid-structure interaction (FSI) occurs when fluid flow causes deformation of the structure. This deformation, in turn, changes the boundary conditions for the fluid flow. The structural analysis discipline, and then independently analyzed each other. However, the fluid dynamic force effect the behavior of the structure, and the vibration amplitude of the structure to fluid. FSI analysis model was separately created fluid and structure model, and then defined the fsi boundary condition, and simultaneously analyzed in one domain. The analysis results were compared with those of the experimental method for validating the analysis model. Flow-induced vibration test was executed with single rod configuration. The vibration amplitudes of a fuel rod were measured by the laser vibro-meter system in x and y-direction. The analyses results were not closely with the test data, but the trend was very similar with the test result. In fsi coupled analysis case, the turbulent model was very important with the reliability of the accuracy of the analysis model. Therefore, the analysis model will be needed to further study

The influence of freezing and tissue porosity on the material properties of vegetable tissues

Energy Technology Data Exchange (ETDEWEB)

Ralfs, Julie D

2002-07-01

Tissue porosity and fluid flow have been shown to be important parameters affecting the mechanical and sensorial behaviour of edible plant tissues. The quantity of fluid and the manner with which it was released on compression of the plant tissue were also important regarding the sensory perception and a good indication of any structural damage resulting from freezing, for example. Potato, carrot and Chinese water chestnut were used to study the effects freezing has on model plant tissues. Mechanical and structural measurements of the plant tissue were correlated with sensory analysis. Conventional freezing was shown to cause severe structural damage predominantly in the form of cavities between or through cells, resulting in decreases in mechanical strength and stiffness, and samples that were perceived in the mouth as 'soft' and 'wet'. The location and size of the cavities formed from ice crystals, depended on the particular plant tissue being frozen, the processing it was subjected to prior to freezing, the size of the sample and the cooling regime employed to freeze the tissue. Cavitation in the tissue resulted in an increase in tissue porosity, which enabled fluid to flow more easily from the tissue on compression, thus affecting the mechanical properties and sensory perception. Freezing damage to plant tissues was shown to be reduced, and sometimes prevented, when active antifreeze proteins (AFPs) were introduced into the tissues by vacuum infiltration or transformation and the tissue was frozen at a suitable cooling rate. Theoretical modelling was applied to the fluid flow and porosity data to test the validity of the models and to subsequently predict the mechanical behaviour of potato from the structural properties of the tissue. (author)