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Sample records for vessel wall structure

  1. Manufacturing and maintenance technologies developed for a thick-wall structure of the ITER vacuum vessel

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    Onozuka, M. E-mail: onozukm@itereu.de; Alfile, J.P.; Aubert, Ph.; Dagenais, J.-F.; Grebennikov, D.; Ioki, K.; Jones, L.; Koizumi, K.; Krylov, V.; Maslakowski, J.; Nakahira, M.; Nelson, B.; Punshon, C.; Roy, O.; Schreck, G

    2001-09-01

    Development of welding, cutting and non-destructive testing (NDT) techniques, and development of remotized systems have been carried out for on-site manufacturing and maintenance of the thick-wall structure of the International Thermonuclear Experimental Reactor (ITER) vacuum vessel (VV). Conventional techniques, including tungsten inert gas welding, plasma cutting, and ultrasonic inspection, have been improved and optimized for the application to thick austenitic stainless steel plates. In addition, advanced methods have been investigated, including reduced-pressure electron-beam and multi-pass neodymium-doped yttrium aluminum garnet (NdYAG) laser welding, NdYAG laser cutting, and electro-magnetic acoustic transducer inspection, to improve cost and technical performance. Two types of remotized systems with different payloads have been investigated and one of them has been fabricated and demonstrated in field joint welding, cutting, and NDT tests on test mockups and full-scale ITER VV sector models. The progress and results of this development to date provide a high level of confidence that the manufacturing and maintenance of the ITER VV is feasible.

  2. A simulation environment for validating ultrasonic blood flow and vessel wall imaging based on fluid-structure interaction simulations: ultrasonic assessment of arterial distension and wall shear rate.

    Science.gov (United States)

    Swillens, Abigail; Degroote, Joris; Vierendeels, Jan; Lovstakken, Lasse; Segers, Patrick

    2010-08-01

    Ultrasound (US) is a commonly used vascular imaging tool when screening for patients at high cardiovascular risk. However, current blood flow and vessel wall imaging methods are hampered by several limitations. When optimizing and developing new ultrasound modalities, proper validation is required before clinical implementation. Therefore, the authors present a simulation environment integrating ultrasound and fluid-structure interaction (FSI) simulations, allowing construction of synthetic ultrasound images based on physiologically realistic behavior of an artery. To demonstrate the potential of the model for vascular ultrasound research, the authors studied clinically relevant imaging modalities of arterial function related to both vessel wall deformation and arterial hemodynamics: Arterial distension (related to arterial stiffness) and wall shear rate (related to the development of atherosclerosis) imaging. An in-house code ("TANGO") was developed to strongly couple the flow solver FLUENT and structural solver ABAQUS using an interface quasi-Newton technique. FIELD II was used to model realistic transducer and scan settings. The input to the FSI-US model is a scatterer phantom on which the US waves reflect, with the scatterer displacement derived from the FSI flow and displacement fields. The authors applied the simulation tool to a 3D straight tube, representative of the common carotid artery (length: 5 cm; and inner and outer radius: 3 and 4 mm). A mass flow inlet boundary condition, based on flow measured in a healthy subject, was applied. A downstream pressure condition, based on a noninvasively measured pressure waveform, was chosen and scaled to simulate three different degrees of arterial distension (1%, 4%, and 9%). The RF data from the FSI-US coupling were further processed for arterial wall and flow imaging. Using an available wall tracking algorithm, arterial distensibility was assessed. Using an autocorrelation estimator, blood velocity and shear

  3. 2D Fast Vessel Visualization Using a Vessel Wall Mask Guiding Fine Vessel Detection

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    Sotirios Raptis

    2010-01-01

    and then try to approach the ridges and branches of the vasculature's using fine detection. Fine vessel screening looks into local structural inconsistencies in vessels properties, into noise, or into not expected intensity variations observed inside pre-known vessel-body areas. The vessels are first modelled sufficiently but not precisely by their walls with a tubular model-structure that is the result of an initial segmentation. This provides a chart of likely Vessel Wall Pixels (VWPs yielding a form of a likelihood vessel map mainly based on gradient filter's intensity and spatial arrangement parameters (e.g., linear consistency. Specific vessel parameters (centerline, width, location, fall-away rate, main orientation are post-computed by convolving the image with a set of pre-tuned spatial filters called Matched Filters (MFs. These are easily computed as Gaussian-like 2D forms that use a limited range sub-optimal parameters adjusted to the dominant vessel characteristics obtained by Spatial Grey Level Difference statistics limiting the range of search into vessel widths of 16, 32, and 64 pixels. Sparse pixels are effectively eliminated by applying a limited range Hough Transform (HT or region growing. Major benefits are limiting the range of parameters, reducing the search-space for post-convolution to only masked regions, representing almost 2% of the 2D volume, good speed versus accuracy/time trade-off. Results show the potentials of our approach in terms of time for detection ROC analysis and accuracy of vessel pixel (VP detection.

  4. Structural Properties of EB-Welded AlSi10Mg Thin-Walled Pressure Vessels Produced by AM-SLM Technology

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    Nahmany, Moshe; Stern, Adin; Aghion, Eli; Frage, Nachum

    2017-09-01

    Additive manufacturing of metals by selective laser melting (AM-SLM) is hampered by significant limitations in product size due to the limited dimensions of printing trays. Electron beam welding (EBW) is a well-established process that results in relatively minor metallurgical modifications in workpieces due to the ability of EBW to pass high-density energy to the related substance. The present study aims to evaluate structural properties of EB-welded AlSi10Mg thin-walled pressure vessels produced from components prepared by SLM technology. Following the EB welding process, leak and burst tests were conducted, as was fractography analysis. The welded vessels showed an acceptable holding pressure of 30 MPa, with a reasonable residual deformation up to 2.3% and a leak rate better than 1 × 10-8 std-cc s-1 helium. The failures that occurred under longitudinal stresses reflected the presence of two weak locations in the vessels, i.e., the welded joint region and the transition zone between the vessel base and wall. Fractographic analysis of the fracture surfaces of broken vessels displayed the ductile mode of the rupture, with dimples of various sizes, depending on the failure location.

  5. Structural Properties of EB-Welded AlSi10Mg Thin-Walled Pressure Vessels Produced by AM-SLM Technology

    Science.gov (United States)

    Nahmany, Moshe; Stern, Adin; Aghion, Eli; Frage, Nachum

    2017-10-01

    Additive manufacturing of metals by selective laser melting (AM-SLM) is hampered by significant limitations in product size due to the limited dimensions of printing trays. Electron beam welding (EBW) is a well-established process that results in relatively minor metallurgical modifications in workpieces due to the ability of EBW to pass high-density energy to the related substance. The present study aims to evaluate structural properties of EB-welded AlSi10Mg thin-walled pressure vessels produced from components prepared by SLM technology. Following the EB welding process, leak and burst tests were conducted, as was fractography analysis. The welded vessels showed an acceptable holding pressure of 30 MPa, with a reasonable residual deformation up to 2.3% and a leak rate better than 1 × 10-8 std-cc s-1 helium. The failures that occurred under longitudinal stresses reflected the presence of two weak locations in the vessels, i.e., the welded joint region and the transition zone between the vessel base and wall. Fractographic analysis of the fracture surfaces of broken vessels displayed the ductile mode of the rupture, with dimples of various sizes, depending on the failure location.

  6. Role of arginase in vessel wall remodeling

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    William eDurante

    2013-05-01

    Full Text Available Arginase metabolizes the semi-essential amino acid L-arginine to L-ornithine and urea. There are two distinct isoforms of arginase, arginase I and II, which are encoded by separate genes and display differences in tissue distribution, subcellular localization, and molecular regulation. Blood vessels express both arginase I and II but their distribution appears to be cell-, vessel-, and species-specific. Both isoforms of arginase are induced by numerous pathologic stimuli and contribute to vascular cell dysfunction and vessel wall remodeling in several diseases. Clinical and experimental studies have documented increases in the expression and/or activity of arginase I or II in blood vessels following arterial injury and in pulmonary and arterial hypertension, aging, and atherosclerosis. Significantly, pharmacological inhibition or genetic ablation of arginase in animals ameliorates abnormalities in vascular cells and normalizes blood vessel architecture and function in all of these pathological states. The detrimental effect of arginase in vascular remodeling is attributable to its ability to stimulate vascular smooth muscle cell and endothelial cell proliferation, and collagen deposition by promoting the synthesis of polyamines and L-proline, respectively. In addition, arginase adversely impacts arterial remodeling by directing macrophages towards an inflammatory phenotype. Moreover, the proliferative, fibrotic, and inflammatory actions of arginase in the vasculature are further amplified by its capacity to inhibit nitric oxide synthesis by competing with nitric oxide synthase for substrate, L-arginine. Pharmacologic or molecular approaches targeting specific isoforms of arginase represent a promising strategy in treating obstructive fibroproliferative vascular disease.

  7. Walled Carotid Bifurcation Phantoms for Imaging Investigations of Vessel Wall Motion and Blood Flow Dynamics.

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    Chee, Adrian J Y; Ho, Chung Kit; Yiu, Billy Y S; Yu, Alfred C H

    2016-07-18

    As a major application domain of vascular ultrasound, the carotid artery has long been the subject of anthropomorphic phantom design. It is nevertheless not trivial to develop walled carotid phantoms that are compatible for use in integrative imaging of carotid wall motion and flow dynamics. In this paper, we present a novel phantom design protocol that can enable efficient fabrication of walled carotid bifurcation phantoms with: (i) high acoustic compatibility, (ii) artery-like vessel elasticity, and (iii) stenotic narrowing feature. Our protocol first involved direct fabrication of the vessel core and an outer mold using computer-aided design tools and 3-D printing technology; these built parts were then used to construct an elastic vessel tube through investment casting of a polyvinyl alcohol containing mixture, and an agar-gelatin tissue mimicking slab was formed around the vessel tube. For demonstration, we applied our protocol to develop a set of healthy and stenosed (25%, 50%, 75%) carotid bifurcation phantoms. Plane wave imaging experiments were performed on these phantoms using an ultrasound scanner with channel-level configurability. Results show that the wall motion dynamics of our phantoms agreed with pulse wave propagation in an elastic vessel (pulse wave velocity of 4.67±0.71 m/s measured at the common carotid artery), and their flow dynamics matched the expected ones in healthy and stenosed bifurcation (recirculation and flow jet formation observed). Integrative imaging of vessel wall motion and blood flow dynamics in our phantoms was also demonstrated, from which we observed fluid-structure interaction differences between healthy and diseased bifurcation phantoms. These findings show that the walled bifurcation phantoms developed with our new protocol are useful in vascular imaging studies that individually or jointly assess wall motion and flow dynamics.

  8. Vessel wall characterization using quantitative MRI: what's in a number?

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    Coolen, Bram F; Calcagno, Claudia; van Ooij, Pim; Fayad, Zahi A; Strijkers, Gustav J; Nederveen, Aart J

    2018-02-01

    The past decade has witnessed the rapid development of new MRI technology for vessel wall imaging. Today, with advances in MRI hardware and pulse sequences, quantitative MRI of the vessel wall represents a real alternative to conventional qualitative imaging, which is hindered by significant intra- and inter-observer variability. Quantitative MRI can measure several important morphological and functional characteristics of the vessel wall. This review provides a detailed introduction to novel quantitative MRI methods for measuring vessel wall dimensions, plaque composition and permeability, endothelial shear stress and wall stiffness. Together, these methods show the versatility of non-invasive quantitative MRI for probing vascular disease at several stages. These quantitative MRI biomarkers can play an important role in the context of both treatment response monitoring and risk prediction. Given the rapid developments in scan acceleration techniques and novel image reconstruction, we foresee the possibility of integrating the acquisition of multiple quantitative vessel wall parameters within a single scan session.

  9. Intracranial vessel wall imaging at 7.0 tesla MRI

    NARCIS (Netherlands)

    van der Kolk, A.G.

    2014-01-01

    Intracranial atherosclerosis is one of the main causes of ischemic stroke. Current conventional imaging techniques assessing intracranial arterial disease in vivo only visualize the vessel wall lumen instead of the pathological vessel wall itself. Therefore, not much is known about the imaging

  10. Magnetic resonance imaging of vessel wall morphology and function

    NARCIS (Netherlands)

    Kröner, Eleanore Sophie Jeanine

    2015-01-01

    This thesis evaluates morphological and functional vessel wall properties measured by magnetic resonance imaging techniques in healthy volunteers and patients with various diseases (i.e. Marfan syndrome patients (MFS), patients with thoracic aortic aneurysm and patients with a previous myocardial

  11. Fluid-structure interaction analysis on the effect of vessel wall hypertrophy and stiffness on the blood flow in carotid artery bifurcation

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    Lee, Sang Hoon; Choi, Hyoung Gwon; Yoo, Jung Yul

    2012-11-01

    The effect of artery wall hypertrophy and stiffness on the flow field is investigated using three-dimensional finite element method for simulating the blood flow. To avoid the complexity due to the necessity of additional mechanical constraints, we use the combined formulation which includes both the fluid and structural equations of motion into single coupled variational equation. A P2P1 Galerkin finite element method is used to solve the Navier-Stokes equations for fluid flow and arbitrary Lagrangian-Eulerian formulation is used to achieve mesh movement. The Newmark method is employed for solving the dynamic equilibrium equations for linear elastic solid mechanics. The pulsatile, incompressible flows of Newtonian fluids constrained in the flexible wall are analyzed with Womersley velocity profile at the inlet and constant pressure at the outlet. The study shows that the stiffness of carotid artery wall affects significantly the flow phenomena during the pulse cycle. Similarly, it is found that the flow field is also strongly influenced by wall hypertrophy. This work was supported by Mid-career Researcher Program and Priority Research Centers Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2009-0079936 & 2011-0029613).

  12. Force acting on spheres adhered to a vessel wall.

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    Sugihara-Seki, M; Skalak, R

    1997-01-01

    To evaluate the force and torque acting on leukocytes attached to the vessel wall, we numerically study the flow field around the leukocytes by using rigid spherical particles adhered to the wall of a circular cylindrical tube as a model of adherent leukocytes. The adherent particles are assumed to be placed regularly in the flow direction with equal spacings, in one row or two rows. The flow field of the suspending fluid is analyzed by a finite element method applied to the Stokes equations, and the drag force and torque acting on each particle, as well as the apparent viscosity, are evaluated as a function of the particle to tube diameter ratio and the particle arrangements. For two-row arrangements of adhered particles where neighboring particles are placed alternately on opposite sides of the vessel, the drag and the torque exerted on each particle are higher than those for single-row arrangements, for constant particle to tube diameter ratio and axial spacing between neighboring particles. This is enhanced for larger particles and smaller axial spacings. The apparent viscosity of the flow through vessels with adhered particles is found to be significantly higher than that without adhered particles or when the particles are freely floating through the vessels.

  13. Coagulation and the vessel wall in thrombosis and atherosclerosis.

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    Kleinegris, Marie-Claire; Ten Cate-Hoek, Arina J; Ten Cate, Hugo

    2012-01-01

    The blood coagulation system is a key survival mechanism that has developed to protect man against lethal bleeding. A second function of blood coagulation is its close interaction with immunity. The immune-mediated coagulation responses may broadly be regarded as an element of response to injury. Pathological coagulation responses, including thromboembolism and disseminated intravascular coagulation (DIC), could therefore be regarded as excessive immune responses to a vessel wall injury. Virchow's triad, which comprises changes in the components of the blood, the state of the vessel wall, and the blood flow, was originally proposed for venous thrombosis. However, lately it appears that the same principles can be applied to arterial thrombosis and even DIC. It has even been postulated that all forms of thrombosis may be part of a continuous spectrum of the same disease. Over the past few years, an accumulation of evidence has shown that the etiopathogenetic mechanisms behind venous and arterial thrombosis are quite similar. The traditional elements of Virchow's triad are found to apply to both arterial and venous thrombosis. Yet, nowadays more emphasis is placed on the vessel wall and vascular bed specificity and the interaction with inflammation and hypercoagulability. This narrative review will discuss recent advances in research on the possible interactions between coagulation, the vascular endothelium, and atherosclerosis as well as the consequences of such interactions for venous and arterial thrombosis.

  14. Molecular magnetic resonance imaging of atherosclerotic vessel wall disease

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    Noerenberg, Dominik [Charite - University Medicine Berlin, Department of Radiology, Berlin (Germany); University of Munich - Grosshadern, Department of Clinical Radiology, Munich (Germany); Ebersberger, Hans U. [Heart Center Munich-Bogenhausen, Department of Cardiology and Intensive Care Medicine, Munich (Germany); Diederichs, Gerd; Hamm, Bernd [Charite - University Medicine Berlin, Department of Radiology, Berlin (Germany); Botnar, Rene M. [King' s College London, Division of Imaging Sciences and Biomedical Engineering, London (United Kingdom); Makowski, Marcus R. [Charite - University Medicine Berlin, Department of Radiology, Berlin (Germany); King' s College London, Division of Imaging Sciences and Biomedical Engineering, London (United Kingdom)

    2016-03-15

    Molecular imaging aims to improve the identification and characterization of pathological processes in vivo by visualizing the underlying biological mechanisms. Molecular imaging techniques are increasingly used to assess vascular inflammation, remodeling, cell migration, angioneogenesis and apoptosis. In cardiovascular diseases, molecular magnetic resonance imaging (MRI) offers new insights into the in vivo biology of pathological vessel wall processes of the coronary and carotid arteries and the aorta. This includes detection of early vascular changes preceding plaque development, visualization of unstable plaques and assessment of response to therapy. The current review focuses on recent developments in the field of molecular MRI to characterise different stages of atherosclerotic vessel wall disease. A variety of molecular MR-probes have been developed to improve the non-invasive detection and characterization of atherosclerotic plaques. Specifically targeted molecular probes allow for the visualization of key biological steps in the cascade leading to the development of arterial vessel wall lesions. Early detection of processes which lead to the development of atherosclerosis and the identification of vulnerable atherosclerotic plaques may enable the early assessment of response to therapy, improve therapy planning, foster the prevention of cardiovascular events and may open the door for the development of patient-specific treatment strategies. (orig.)

  15. Automated image segmentation and registration of vessel wall MRI for quantitative assessment of carotid artery vessel wall dimensions and plaque composition

    NARCIS (Netherlands)

    Klooster, Ronald van 't

    2014-01-01

    The main goal of this thesis was to develop methods for automated segmentation, registration and classification of the carotid artery vessel wall and plaque components using multi-sequence MR vessel wall images to assess atherosclerosis. First, a general introduction into atherosclerosis and

  16. An Ultrasound Simulation Model for the Pulsatile Blood Flow Modulated by the Motion of Stenosed Vessel Wall.

    Science.gov (United States)

    Zhang, Qinghui; Zhang, Yufeng; Zhou, Yi; Zhang, Kun; Zhang, Kexin; Gao, Lian

    2016-01-01

    This paper presents an ultrasound simulation model for pulsatile blood flow, modulated by the motion of a stenosed vessel wall. It aims at generating more realistic ultrasonic signals to provide an environment for evaluating ultrasound signal processing and imaging and a framework for investigating the behaviors of blood flow field modulated by wall motion. This model takes into account fluid-structure interaction, blood pulsatility, stenosis of the vessel, and arterial wall movement caused by surrounding tissue's motion. The axial and radial velocity distributions of blood and the displacement of vessel wall are calculated by solving coupled Navier-Stokes and wall equations. With these obtained values, we made several different phantoms by treating blood and the vessel wall as a group of point scatterers. Then, ultrasound echoed signals from oscillating wall and blood in the axisymmetric stenotic-carotid arteries were computed by ultrasound simulation software, Field II. The results show better consistency with corresponding theoretical values and clinical data and reflect the influence of wall movement on the flow field. It can serve as an effective tool not only for investigating the behavior of blood flow field modulated by wall motion but also for quantitative or qualitative evaluation of new ultrasound imaging technology and estimation method of blood velocity.

  17. Subclavian vein aneurysm secondary to a benign vessel wall hamartoma

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    Warren, Patrick [Nationwide Children' s Hospital, Section of Pediatric Interventional Radiology, Columbus, OH (United States); Spaeth, Maya [Nationwide Children' s Hospital, Section of Plastic and Reconstructive Surgery, Columbus, OH (United States); Prasad, Vinay [Nationwide Children' s Hospital, Section of Pediatric Pathology, Columbus, OH (United States); McConnell, Patrick [Nationwide Children' s Hospital, Section of Cardiothoracic Surgery, Columbus, OH (United States)

    2013-11-15

    Venous aneurysms are rare clinical entities, particularly in children, and their presentation and natural history often depend on the anatomical location and underlying etiology. We present a single case of a 12-year-old girl who presented with a palpable right supraclavicular mass. Imaging evaluation with CT, conventional venography, MRI and sonography revealed a large fusiform subclavian vein aneurysm with an unusual, mass-like fibrofatty component incorporated into the vessel wall. The girl ultimately required complete resection of the right subclavian vein with placement of a synthetic interposition graft. This case provides a radiology/pathology correlation of an entity that has not previously been described as well as an example of the utility of multiple imaging modalities to aid diagnosis and preoperative planning. (orig.)

  18. In vivo and ex vivo vessel wall MRI of the circle of Willis

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    Harteveld, A.A.|info:eu-repo/dai/nl/413650286

    2017-01-01

    In recent years, several MRI sequences have been developed for direct evaluation of the intracranial vessel wall and its pathology in vivo. These MRI sequences enable detection of intracranial vessel wall abnormalities, including those that have not yet caused luminal narrowing. The research field

  19. Optimal Branching Structure of Fluidic Networks with Permeable Walls

    Directory of Open Access Journals (Sweden)

    Vinicius R. Pepe

    2017-01-01

    Full Text Available Biological and engineering studies of Hess-Murray’s law are focused on assemblies of tubes with impermeable walls. Blood vessels and airways have permeable walls to allow the exchange of fluid and other dissolved substances with tissues. Should Hess-Murray’s law hold for bifurcating systems in which the walls of the vessels are permeable to fluid? This paper investigates the fluid flow in a porous-walled T-shaped assembly of vessels. Fluid flow in this branching flow structure is studied numerically to predict the configuration that provides greater access to the flow. Our findings indicate, among other results, that an asymmetric flow (i.e., breaking the symmetry of the flow distribution may occur in this symmetrical dichotomous system. To derive expressions for the optimum branching sizes, the hydraulic resistance of the branched system is computed. Here we show the T-shaped assembly of vessels is only conforming to Hess-Murray’s law optimum as long as they have impervious walls. Findings also indicate that the optimum relationship between the sizes of parent and daughter tubes depends on the wall permeability of the assembled tubes. Our results agree with analytical results obtained from a variety of sources and provide new insights into the dynamics within the assembly of vessels.

  20. Growth Description for Vessel Wall Adaptation: A Thick-Walled Mixture Model of Abdominal Aortic Aneurysm Evolution.

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    Grytsan, Andrii; Eriksson, Thomas S E; Watton, Paul N; Gasser, T Christian

    2017-08-25

    (1) Background: Vascular tissue seems to adapt towards stable homeostatic mechanical conditions, however, failure of reaching homeostasis may result in pathologies. Current vascular tissue adaptation models use many ad hoc assumptions, the implications of which are far from being fully understood; (2) Methods: The present study investigates the plausibility of different growth kinematics in modeling Abdominal Aortic Aneurysm (AAA) evolution in time. A structurally motivated constitutive description for the vessel wall is coupled to multi-constituent tissue growth descriptions; Constituent deposition preserved either the constituent's density or its volume, and Isotropic Volume Growth (IVG), in-Plane Volume Growth (PVG), in-Thickness Volume Growth (TVG) and No Volume Growth (NVG) describe the kinematics of the growing vessel wall. The sensitivity of key modeling parameters is explored, and predictions are assessed for their plausibility; (3) Results: AAA development based on TVG and NVG kinematics provided not only quantitatively, but also qualitatively different results compared to IVG and PVG kinematics. Specifically, for IVG and PVG kinematics, increasing collagen mass production accelerated AAA expansion which seems counterintuitive. In addition, TVG and NVG kinematics showed less sensitivity to the initial constituent volume fractions, than predictions based on IVG and PVG; (4) Conclusions: The choice of tissue growth kinematics is of crucial importance when modeling AAA growth. Much more interdisciplinary experimental work is required to develop and validate vascular tissue adaption models, before such models can be of any practical use.

  1. High-Resolution Vessel Wall Magnetic Resonance Imaging in Varicella-Zoster Virus Vasculitis.

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    Tsivgoulis, Georgios; Lachanis, Stefanos; Magoufis, Georgios; Safouris, Apostolos; Kargiotis, Odysseas; Stamboulis, Elefterios

    2016-06-01

    Varicella-zoster virus vasculopathy is a rare but potentially treatable condition. Diagnosis has been based on angiography, brain magnetic resonance imaging (MRI), and cerebrospinal fluid analysis. High-resolution vessel wall MRI may aid to the diagnosis by differentiating inflammation from other vessel wall pathologies. We present the characteristic MRI findings of this condition in a young patient presenting with ischemic stroke. Copyright © 2016 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  2. Segmentation of elastic fibres in images of vessel wall sections stained with Weigert's resorcin-fuchsin.

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    Hernández-Morera, Pablo; Travieso-González, Carlos M; Castaño-González, Irene; Mompeó-Corredera, Blanca; Ortega-Santana, Francisco

    2017-04-01

    The elastic fibres are an essential component of the extracellular matrix in blood vessel walls that allows a long-range of deformability and passive recoil without energy input. The quantitative determination of elastic fibres will provide information on the state of the vascular wall and to determine the role and behaviour of this key structural element in different physiological and pathological vascular processes. We present a segmentation method to identify and quantify elastic fibres based on a local threshold technique and some morphological characteristics measured on the segmented objects that facilitate the discrimination between elastic fibres and other image components. The morphological characteristics analysed are the thickness and the length of an object. The segmentation method was evaluated using an image database of vein sections stained with Weigert's resorcin-fuchsin. The performance results are based on a ground truth generated manually resulting in values of sensitivity greater than 80% with the exception in two samples, and specificity values above 90% for all samples. Medical specialists carried out a visual evaluation where the observations indicate a general agreement on the segmentation results' visual quality, and the consistency between the methodology proposed and the subjective observation of the doctors for the evaluation of pathological changes in vessel wall. The proposed methodology provides more objective measurements than the qualitative methods traditionally used in the histological analysis, with a significant potential for this method to be used as a diagnostic aid for many other vascular pathological conditions and in similar tissues such as skin and mucous membranes. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Estrogen receptor expression and vessel density in the vagina wall in postmenopausal women with prolapse.

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    Lara, Lúcia Alves da Silva; Ribeiro da Silva, Alfredo; Rosa-e-Silva, Julio Cesar; Silva-de-Sá, Marcos Felipe; Rosa-e-Silva, Ana Carolina Japur de Sá

    2014-04-01

    After menopause, critically estrogen low levels result in modifications in vaginal wall. This cross-sectional study aims to determine whether there is a change in the number of vessels in the lamina propria of the vagina after menopause in parallel to the ER-alpha expression on the vaginal wall. Twelve women who underwent a genital surgery for genital prolapse up to grade II were selected. They were divided into two groups: a premenopausal group (PG) consisting of six women who were 18-40 years old with FSH levels =12 mIU/ml and regular cycles, and a menopausal group (MG) consisting of six women at least one year after menopause who were <65 years old with FSH levels =40 mIU/ml. Slides were stained for ER-alpha immunohistochemistry, and an endothelial cell marker CD3 was used to label vessels which were identified by using a system for morphometry. The number of vessels was significantly higher in the PG than in the MG both on the anterior wall (PG: 1.055 ± 145.8 vessels/mm(2), MG: 346.6 ± 209.9 vessels/mm(2), p<0.0001) and on the posterior wall (PG: 1064 ± 303.3 vessels/mm(2), MG: 348.6 ± 167.3 vessels/mm(2), p=0.0005). The ER-alpha score was significantly higher in the PG than the score for the MG on both the anterior and posterior walls (PG: 6.0 ± 0.52, MG: 2.5 ± 0.89, p=0.007; PG: 5.8 ± 0.79, MG: 2.7 ± 0.95, p=0.03, respectively). There was a positive correlation between the ER-alpha score and the vessel concentration on the anterior (r=0.6656, p=0.018) and posterior (r=0.6738, p=0.016) vaginal walls. Age was strongly negatively correlated with vessel concentration on the vaginal walls (respectively r=-0.9033, p<0.0001, r=-0.7440, p=0.0055). Therefore, postmenopausal women with genital prolapse have a smaller number of vessels on the vaginal wall compared to normoestrogenic controls with the same pathological condition. Hypoestrogenism and advancing age are factors that are associated to these changes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. High-resolution intracranial vessel wall MRI in an elderly asymptomatic population: comparison of 3T and 7T

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    Harteveld, Anita A.; Kolk, Anja G. van der; Dieleman, Nikki; Siero, Jeroen C.W.; Luijten, Peter R.; Zwanenburg, Jaco J.M.; Hendrikse, Jeroen [University Medical Center Utrecht, Department of Radiology, Postbox 85500, Utrecht (Netherlands); Worp, H.B. van der; Frijns, Catharina J.M. [University Medical Center Utrecht, Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, Utrecht (Netherlands); Kuijf, Hugo J. [University Medical Center Utrecht, Image Sciences Institute, Utrecht (Netherlands)

    2017-04-15

    Several intracranial vessel wall sequences have been described in recent literature, with either 3-T or 7-T magnetic resonance imaging (MRI). In the current study, we compared 3-T and 7-T MRI in visualising both the intracranial arterial vessel wall and vessel wall lesions. Twenty-one elderly asymptomatic volunteers were scanned by 3-T and 7-T MRI with an intracranial vessel wall sequence, both before and after contrast administration. Two raters scored image quality, and presence and characteristics of vessel wall lesions. Vessel wall visibility was equal or significantly better at 7 T for the studied arterial segments, even though there were more artefacts hampering assessment. The better visualisation of the vessel wall at 7 T was most prominent in the proximal anterior cerebral circulation and the posterior cerebral artery. In the studied elderly asymptomatic population, 48 vessel-wall lesions were identified at 3 T, of which 7 showed enhancement. At 7 T, 79 lesions were identified, of which 29 showed enhancement. Seventy-one percent of all 3-T lesions and 59 % of all 7-T lesions were also seen at the other field strength. Despite the large variability in detected lesions at both field strengths, we believe 7-T MRI has the highest potential to identify the total burden of intracranial vessel wall lesions. (orig.)

  5. Could the heat sink effect of blood flow inside large vessels protect the vessel wall from thermal damage during RF-assisted surgical resection?

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    González-Suárez, Ana; Trujillo, Macarena; Burdío, Fernando; Andaluz, Anna; Berjano, Enrique

    2014-08-01

    To assess by means of computer simulations whether the heat sink effect inside a large vessel (portal vein) could protect the vessel wall from thermal damage close to an internally cooled electrode during radiofrequency (RF)-assisted resection. First,in vivo experiments were conducted to validate the computational model by comparing the experimental and computational thermal lesion shapes created around the vessels. Computer simulations were then carried out to study the effect of different factors such as device-tissue contact, vessel position, and vessel-device distance on temperature distributions and thermal lesion shapes near a large vessel, specifically the portal vein. The geometries of thermal lesions around the vessels in the in vivo experiments were in agreement with the computer results. The thermal lesion shape created around the portal vein was significantly modified by the heat sink effect in all the cases considered. Thermal damage to the portal vein wall was inversely related to the vessel-device distance. It was also more pronounced when the device-tissue contact surface was reduced or when the vessel was parallel to the device or perpendicular to its distal end (blade zone), the vessel wall being damaged at distances less than 4.25 mm. The computational findings suggest that the heat sink effect could protect the portal vein wall for distances equal to or greater than 5 mm, regardless of its position and distance with respect to the RF-based device.

  6. [Morphogenesis, structure and properties of lymphatic vessels].

    Science.gov (United States)

    Ratajska, Anna; Jankowska-Steifer, Ewa; Czarnowska, Elżbieta; Flaht, Aleksandra; Radomska-Leśniewska, Dorota

    2012-11-19

    In this paper, we present literature results related to structure and various manners of lymphatic vessel formation during embryonic development and in pathological events, such as tumorigenesis, wound healing, and other diseases. The functions of the lymphatic system include the collection of fluids that enter tissues from the circulation, absorption of lipids and lipid-soluble vitamins from the intestine and their subsequent transport, participation in antigen, dendritic cell, and lymphocyte migration. The lymphatic system is also a route for tumor cell and inflammatory cell transport. Native lymphatic capillaries differ from blood capillaries by having an irregular lumen, a discontinuous basement membrane, absence of pericytes, and a strong anchorage of their endothelial cells to the extracellular matrix via microfibrils built of emilin and fibrillin. Lymphatic endothelial cells express surface antigens such as Lyve-1, podoplanin, VEGFR3 (Flk4) and transcription factor Prox-1, as well as molecules which are common for blood endothelial cells and lymphatic endothelial cells (CD31, CD34, Flk-1, Tie-1, Tie-2, neuropilin 2). Lymphatic vessel formation during embryonic development starts with the occurrence of lymphatic sacs sprouting from systemic jugular veins and/or by co-option of lymphangioblasts or hematopoietic-derived cells. It can also proceed by dedifferentiation of venous endothelial cells after their detachment from the venous system, migration to the target places within the body and assembly in the lymphatic lumen. Mechanisms of lymphatic vessel formation during embryonic development and in pathological conditions, such as tumorigenesis, wound healing, and metastasis, is regulated by a plethora of growth factors and molecules, among which the most important are VEGF-C, VEGF-D, HGF, FGF, retinoic acid, IL-3, and IL-7. Macrophages and cells bearing CD45 phenotype seem to take part in the formation of lymphatics. Macrophages might act as a source of growth

  7. Increased coronary vessel wall thickness in HIV-infected young adults.

    Science.gov (United States)

    Abd-Elmoniem, Khaled Z; Unsal, Aylin B; Eshera, Sarah; Matta, Jatin R; Muldoon, Nancy; McAreavey, Dorothea; Purdy, Julia B; Hazra, Rohan; Hadigan, Colleen; Gharib, Ahmed M

    2014-12-15

    Individuals with long-term human immunodeficiency virus (HIV) infection are at risk for premature vasculopathy and cardiovascular disease (CVD). We evaluated coronary vessel wall thickening, coronary plaque, and epicardial fat in patients infected with HIV early in life compared with healthy controls. This is a prospective cross-sectional study of 35 young adults who acquired HIV in early life and 11 healthy controls, free of CVD. Time resolved phase-sensitive dual inversion recovery black-blood vessel wall magnetic resonance imaging (TRAPD) was used to measure proximal right coronary artery (RCA) wall thickness, and multidetector computed tomography (CT) angiography was used to quantify coronary plaque and epicardial fat. RCA vessel wall thickness was significantly increased in HIV-infected patients compared with sex- and race-matched controls (1.32 ± 0.21 mm vs 1.09 ± 0.14 mm, P = .002). No subject had discrete plaque on CT sufficient to cause luminal narrowing, and plaque was not related to RCA wall thickness. In multivariate regression analyses, smoking pack-years (P = .004) and HIV infection (P = .007) were independently associated with thicker RCA vessel walls. Epicardial fat did not differ between groups. Among the HIV-infected group, duration of antiretroviral therapy (ART) (P = .02), duration of stavudine exposure (P ART, hyperlipidemia, and smoking contributed to proximal RCA thickening, independent of atherosclerotic plaque quantified by CT. These modifiable risk factors appear to influence early atherogenesis as measured by coronary wall thickness and may be important targets for CVD risk reduction. Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2014. This work is written by (a) US Government employee(s) and is in the public domain in the US.

  8. Coronary magnetic resonance angiography and vessel wall imaging in children with Kawasaki disease

    Energy Technology Data Exchange (ETDEWEB)

    Greil, Gerald F.; Hofbeck, Michael; Sieverding, Ludger [University of Tuebingen, Department of Pediatric Cardiology, Children' s Hospital, Tuebingen (Germany); Seeger, Achim; Miller, Stephan; Claussen, Claus D. [University of Tuebingen, Department of Diagnostic Radiology, Tuebingen (Germany); Botnar, Rene M. [Technical University Munich, Department of Nuclear Medicine, Cardiovascular Division, Munich (Germany)

    2007-07-15

    In patients with Kawasaki disease (KD) serial evaluation of the distribution and size of coronary artery aneurysms (CAA) is necessary for risk stratification and therapeutic management. To apply whole-heart coronary MR angiography (CMRA) and black-blood coronary vessel wall imaging in children with KD. Six children (mean age 4.6 years, range 2.5-7.8 years) with KD underwent CMRA using a free-breathing, T2-prepared, three-dimensional steady-state free-precession (3D-SSFP), whole-heart approach with navigator gating and tracking. Vessel walls were imaged with an ECG-triggered and navigator-gated double inversion recovery (DIR) black-blood segmented turbo spin-echo sequence. There was complete agreement between CMRA and conventional angiography (n=6) in the detection of CAA (n=15). Excellent agreement was found between the two techniques in determining the maximal diameter (mean difference 0.2{+-}0.7 mm), length (mean difference 0.1{+-}0.8 mm) and distance from the ostium (mean difference -0.8{+-}2.1 mm) of the CAAs. In all subjects with a CAA, abnormally thickened vessel walls were found (2.5{+-}0.5 mm). CMRA accurately defines CAA in free-breathing sedated children with KD using the whole-heart approach and detects abnormally thickened vessel walls. This technique may reduce the need for serial X-ray coronary angiography, and improve risk stratification and monitoring of therapy. (orig.)

  9. Learning-based automated segmentation of the carotid artery vessel wall in dual-sequence MRI using subdivision surface fitting

    NARCIS (Netherlands)

    Gao, Shan; van't Klooster, Ronald; Kitslaar, Pieter H.; Coolen, Bram F.; van den Berg, Alexandra M.; Smits, Loek P.; Shahzad, Rahil; Shamonin, Denis P.; de Koning, Patrick J. H.; Nederveen, Aart J.; van der Geest, Rob J.

    2017-01-01

    Purpose: The quantification of vessel wall morphology and plaque burden requires vessel segmentation, which is generally performed by manual delineations. The purpose of our work is to develop and evaluate a new 3D model-based approach for carotid artery wall segmentation from dual-sequence MRI.

  10. Structural integrity of nuclear reactor pressure vessels

    Science.gov (United States)

    Knott, John F.

    2013-09-01

    The paper starts from concerns expressed by Sir Alan Cottrell, in the early 1970s, related to the safety of the pressurized water reactor (PWR) proposed at that time for the next phase of electrical power generation. It proceeds to describe the design and operation of nuclear generation plant and gives details of the manufacture of PWR reactor pressure vessels (RPVs). Attention is paid to stress-relief cracking and under-clad cracking, experienced with early RPVs, explaining the mechanisms for these forms of cracking and the means taken to avoid them. Particular note is made of the contribution of non-destructive inspection to structural integrity. Factors affecting brittle fracture in RPV steels are described: in particular, effects of neutron irradiation. The use of fracture mechanics to assess defect tolerance is explained, together with the failure assessment diagram embodied in the R6 procedure. There is discussion of the Master Curve and how it incorporates effects of irradiation on fracture toughness. Dangers associated with extrapolation of data to low probabilities are illustrated. The treatment of fatigue-crack growth is described, in the context of transients that may be experienced in the operation of PWR plant. Detailed attention is paid to the thermal shock associated with a large loss-of-coolant accident. The final section reviews the arguments advanced to justify 'Incredibility of Failure' and how these are incorporated in assessments of the integrity of existing plant and proposed 'new build' PWR pressure vessels.

  11. Probabilistic Structural Integrity Analysis of Boiling Water Reactor Pressure Vessel under Low Temperature Overpressure Event

    Directory of Open Access Journals (Sweden)

    Hsoung-Wei Chou

    2015-01-01

    Full Text Available The probabilistic structural integrity of a Taiwan domestic boiling water reactor pressure vessel has been evaluated by the probabilistic fracture mechanics analysis. First, the analysis model was built for the beltline region of the reactor pressure vessel considering the plant specific data. Meanwhile, the flaw models which comprehensively simulate all kinds of preexisting flaws along the vessel wall were employed here. The low temperature overpressure transient which has been concluded to be the severest accident for a boiling water reactor pressure vessel was considered as the loading condition. It is indicated that the fracture mostly happens near the fusion-line area of axial welds but with negligible failure risk. The calculated results indicate that the domestic reactor pressure vessel has sufficient structural integrity until doubling of the present end-of-license operation.

  12. Preliminary electromagnetic, thermal and mechanical design for first wall and vacuum vessel of FAST

    Energy Technology Data Exchange (ETDEWEB)

    Lucca, F., E-mail: Flavio.Lucca@LTCalcoli.it [LT Calcoli srl, Piazza Prinetti 26/B, 23807 Merate, LC (Italy); Bertolini, C. [LT Calcoli srl, Piazza Prinetti 26/B, 23807 Merate, LC (Italy); Crescenzi, F.; Crisanti, F. [C.R. ENEA Frascati – UT FUS, Via E. Fermi 45, IT-00044 Frascati, RM (Italy); Di Gironimo, G. [CREATE, Università di Napoli Federico II, P.le Tecchio 80, 80125 Napoli (Italy); Labate, C. [CREATE, Università di Napoli Parthenope, Via Acton 38, 80133 Napoli (Italy); Manzoni, M.; Marconi, M.; Pagani, I. [LT Calcoli srl, Piazza Prinetti 26/B, 23807 Merate, LC (Italy); Ramogida, G. [C.R. ENEA Frascati – UT FUS, Via E. Fermi 45, IT-00044 Frascati, RM (Italy); Renno, F. [CREATE, Università di Napoli Federico II, P.le Tecchio 80, 80125 Napoli (Italy); Roccella, M. [LT Calcoli srl, Piazza Prinetti 26/B, 23807 Merate, LC (Italy); Roccella, S. [C.R. ENEA Frascati – UT FUS, Via E. Fermi 45, IT-00044 Frascati, RM (Italy); Viganò, F. [LT Calcoli srl, Piazza Prinetti 26/B, 23807 Merate, LC (Italy)

    2015-10-15

    The fusion advanced study torus (FAST), with its compact design, high toroidal field and plasma current, faces many of the problems met by ITER, and at the same time anticipates much of the DEMO relevant physics and technology. The conceptual design of the first wall (FW) and the vacuum vessel (VV) has been defined on the basis of FAST operative conditions and of “Snow Flakes” (SF) magnetic topology, which is also relevant for DEMO. The EM loads are one of the most critical load components for the FW and the VV during plasma disruptions and a first dimensioning of these components for such loads is mandatory. During this first phase of R&D activities the conceptual design of the FW and VV have been assessed estimating, by means of FE simulations, the EM loads due to a typical vertical disruption event (VDE) in FAST. EM loads were then transferred on a FE mechanical model of the FAST structures and the mechanical response of the FW and VV design for the analyzed VDE event was assessed. The results indicate that design criteria are not fully satisfied by the current drawing of the VV and FW components. The most critical regions have been individuated and the effect of some geometrical and material changes has been checked in order to improve the structure.

  13. Effects of dynamic shear and transmural pressure on wall shear stress sensitivity in collecting lymphatic vessels.

    Science.gov (United States)

    Kornuta, Jeffrey A; Nepiyushchikh, Zhanna; Gasheva, Olga Y; Mukherjee, Anish; Zawieja, David C; Dixon, J Brandon

    2015-11-01

    Given the known mechanosensitivity of the lymphatic vasculature, we sought to investigate the effects of dynamic wall shear stress (WSS) on collecting lymphatic vessels while controlling for transmural pressure. Using a previously developed ex vivo lymphatic perfusion system (ELPS) capable of independently controlling both transaxial pressure gradient and average transmural pressure on an isolated lymphatic vessel, we imposed a multitude of flow conditions on rat thoracic ducts, while controlling for transmural pressure and measuring diameter changes. By gradually increasing the imposed flow through a vessel, we determined the WSS at which the vessel first shows sign of contraction inhibition, defining this point as the shear stress sensitivity of the vessel. The shear stress threshold that triggered a contractile response was significantly greater at a transmural pressure of 5 cmH2O (0.97 dyne/cm(2)) than at 3 cmH2O (0.64 dyne/cm(2)). While contraction frequency was reduced when a steady WSS was applied, this inhibition was reversed when the applied WSS oscillated, even though the mean wall shear stresses between the conditions were not significantly different. When the applied oscillatory WSS was large enough, flow itself synchronized the lymphatic contractions to the exact frequency of the applied waveform. Both transmural pressure and the rate of change of WSS have significant impacts on the contractile response of lymphatic vessels to flow. Specifically, time-varying shear stress can alter the inhibition of phasic contraction frequency and even coordinate contractions, providing evidence that dynamic shear could play an important role in the contractile function of collecting lymphatic vessels. Copyright © 2015 the American Physiological Society.

  14. HIV-1 and recombinant gp120 affect the survival and differentiation of human vessel wall-derived mesenchymal stem cells

    Directory of Open Access Journals (Sweden)

    Pasquinelli Gianandrea

    2011-05-01

    Full Text Available Abstract Background HIV infection elicits the onset of a progressive immunodeficiency and also damages several other organs and tissues such as the CNS, kidney, heart, blood vessels, adipose tissue and bone. In particular, HIV infection has been related to an increased incidence of cardiovascular diseases and derangement in the structure of blood vessels in the absence of classical risk factors. The recent characterization of multipotent mesenchymal cells in the vascular wall, involved in regulating cellular homeostasis, suggests that these cells may be considered a target of HIV pathogenesis. This paper investigated the interaction between HIV-1 and vascular wall resident human mesenchymal stem cells (MSCs. Results MSCs were challenged with classical R5 and X4 HIV-1 laboratory strains demonstrating that these strains are able to enter and integrate their retro-transcribed proviral DNA in the host cell genome. Subsequent experiments indicated that HIV-1 strains and recombinant gp120 elicited a reliable increase in apoptosis in sub-confluent MSCs. Since vascular wall MSCs are multipotent cells that may be differentiated towards several cell lineages, we challenged HIV-1 strains and gp120 on MSCs differentiated to adipogenesis and endotheliogenesis. Our experiments showed that the adipogenesis is increased especially by upregulated PPARγ activity whereas the endothelial differentiation induced by VEGF treatment was impaired with a downregulation of endothelial markers such as vWF, Flt-1 and KDR expression. These viral effects in MSC survival and adipogenic or endothelial differentiation were tackled by CD4 blockade suggesting an important role of CD4/gp120 interaction in this context. Conclusions The HIV-related derangement of MSC survival and differentiation may suggest a direct role of HIV infection and gp120 in impaired vessel homeostasis and in genesis of vessel damage observed in HIV-infected patients.

  15. Influence of acquired obesity on coronary vessel wall late gadolinium enhancement in discordant monozygote twins

    Energy Technology Data Exchange (ETDEWEB)

    Makowski, Marcus R. [King' s College London, Division of Imaging Sciences and Biomedical Engineering, London (United Kingdom); Wellcome Trust and EPSRC Medical Engineering Centre, London (United Kingdom); King' s College London, BHF Centre of Excellence, London (United Kingdom); King' s College London, NIHR Biomedical Research Centre, London (United Kingdom); Charite-Universitaetsmedizin, Department of Radiology, Berlin (Germany); Jansen, Christian H.P. [King' s College London, Division of Imaging Sciences and Biomedical Engineering, London (United Kingdom); Ebersberger, Ullrich; Spector, Tim D. [Heart Center Munich-Bogenhausen, Department of Cardiology and Intensive Care Medicine, Munich (Germany); Schaeffter, Tobias; Razavi, Reza [King' s College London, Division of Imaging Sciences and Biomedical Engineering, London (United Kingdom); Wellcome Trust and EPSRC Medical Engineering Centre, London (United Kingdom); King' s College London, BHF Centre of Excellence, London (United Kingdom); King' s College London, NIHR Biomedical Research Centre, London (United Kingdom); Mangino, Massimo [King' s College London, Department of Twin Research and Genetic Epidemiology, London (United Kingdom); National Institute for Health Research (NIHR) Biomedical Research Centre at Guy' s and St. Thomas' Foundation Trust, London (United Kingdom); Botnar, Rene M. [King' s College London, Division of Imaging Sciences and Biomedical Engineering, London (United Kingdom); Wellcome Trust and EPSRC Medical Engineering Centre, London (United Kingdom); King' s College London, BHF Centre of Excellence, London (United Kingdom); King' s College London, NIHR Biomedical Research Centre, London (United Kingdom); Greil, Gerald F. [King' s College London, Division of Imaging Sciences and Biomedical Engineering, London (United Kingdom); Wellcome Trust and EPSRC Medical Engineering Centre, London (United Kingdom); King' s College London, BHF Centre of Excellence, London (United Kingdom); King' s College London, NIHR Biomedical Research Centre, London (United Kingdom)

    2017-11-15

    The aim of this study was to investigate the impact of BMI on late gadolinium enhancement (LGE) of the coronary artery wall in identical monozygous twins discordant for BMI. Coronary LGE represents a useful parameter for the detection and quantification of atherosclerotic coronary vessel wall disease. Thirteen monozygote female twin pairs (n = 26) with significantly different BMIs (>1.6 kg/m2) were recruited out of >10,000 twin pairs (TwinsUK Registry). A coronary 3D-T2prep-TFE MR angiogram and 3D-IR-TFE vessel wall scan were performed prior to and following the administration of 0.2 mmol/kg of Gd-DTPA on a 1.5 T MR scanner. The number of enhancing coronary segments and contrast to noise ratios (CNRs) of the coronary wall were quantified. An increase in BMI was associated with an increased number of enhancing coronary segments (5.3 ± 1.5 vs. 3.5 ± 1.6, p < 0.0001) and increased coronary wall enhancement (6.1 ± 1.1 vs. 4.8 ± 0.9, p = 0.0027) compared to matched twins with lower BMI. This study in monozygous twins indicates that acquired factors predisposing to obesity, including lifestyle and environmental factors, result in increased LGE of the coronary arteries, potentially reflecting an increase in coronary atherosclerosis in this female study population. (orig.)

  16. Nanoparticle motion near a blood vessel wall in targeted drug delivery

    Science.gov (United States)

    Vitoshkin, Helena; Yu, Hsiu-Yu; Eckmann, David M.; Radhakrishnan, Ravi; Ayyaswamy, Portonovo S.

    2014-11-01

    A computational study of the motion of a spherical nanoparticle close to the bounding wall of a blood vessel in targeted drug delivery is presented. An arbitrary Lagrangian-Eulerian algorithm has been carried out, taking into account both the Brownian and the hydrodynamic effects. Pertinent to targeted drug delivery, we focus on the condition when the particle is in the lubrication layer. The velocity auto-correlation function (VACF) is seen to initially decay faster by a factor of particle radius divided by the fluid gap thickness compared to that in an unbounded medium. Long time decay is found to be algebraic. Focusing on hydrodynamic interaction between the particle and the wall, effects of wall curvature, particle size, and variations in density of the particle are investigated. We also study adhesive interactions of a nanoparticle with an endothelial cell located on the vessel wall by the modeling the nanoparticle tethered by a harmonic spring with varying spring constants. It is shown that the particle velocity is affected by hydrodynamic and harmonic spring forces leading to VACF oscillations which decay algebraically at long times. The results agree with those predicted by earlier theories for particle VACF near a wall. These findings have applications in medication administration and in the colloidal sciences. Supported by NIH Grant U01 EB016027.

  17. Human elastic cartilage engineering from cartilage progenitor cells using rotating wall vessel bioreactor.

    Science.gov (United States)

    Takebe, T; Kobayashi, S; Kan, H; Suzuki, H; Yabuki, Y; Mizuno, M; Adegawa, T; Yoshioka, T; Tanaka, J; Maegawa, J; Taniguchi, H

    2012-05-01

    Transplantation of bioengineered elastic cartilage is considered to be a promising approach for patients with craniofacial defects. We have previously shown that human ear perichondrium harbors a population of cartilage progenitor cells (CPCs). The aim of this study was to examine the use of a rotating wall vessel (RWV) bioreactor for CPCs to engineer 3-D elastic cartilage in vitro. Human CPCs isolated from ear perichondrium were expanded and differentiated into chondrocytes under 2-D culture conditions. Fully differentiated CPCs were seeded into recently developed pC-HAp/ChS (porous material consisted of collagen, hydroxyapatite, and chondroitinsulfate) scaffolds and 3-D cultivated utilizing a RWV bioreactor. 3-D engineered constructs appeared shiny with a yellowish, cartilage-like morphology. The shape of the molded scaffold was maintained after RWV cultivation. Hematoxylin and eosin staining showed engraftment of CPCs inside pC-HAp/ChS. Alcian blue and Elastica Van Gieson staining showed of proteoglycan and elastic fibers, which are unique extracellular matrices of elastic cartilage. Thus, human CPCs formed elastic cartilage-like tissue after 3-D cultivation in a RWV bioreactor. These techniques may assist future efforts to reconstruct complicate structures composed of elastic cartilage in vitro. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. Gadolinium Enhanced MR Coronary Vessel Wall Imaging at 3.0 Tesla

    Directory of Open Access Journals (Sweden)

    Sebastian Kelle

    2010-01-01

    Full Text Available Purpose. We evaluated the influence of the time between low-dose gadolinium (Gd contrast administration and coronary vessel wall enhancement (LGE detected by 3T magnetic resonance imaging (MRI in healthy subjects and patients with coronary artery disease (CAD. Materials and Methods. Four healthy subjects (4 men, mean age 29  ±  3 years and eleven CAD patients (6 women, mean age 61±10 years were studied on a commercial 3.0 Tesla (T whole-body MR imaging system (Achieva 3.0 T; Philips, Best, The Netherlands. T1-weighted inversion-recovery coronary magnetic resonance imaging (MRI was repeated up to 75 minutes after administration of low-dose Gadolinium (Gd (0.1 mmol/kg Gd-DTPA. Results. LGE was seen in none of the healthy subjects, however in all of the CAD patients. In CAD patients, fifty-six of 62 (90.3% segments showed LGE of the coronary artery vessel wall at time-interval 1 after contrast. At time-interval 2, 34 of 42 (81.0% and at time-interval 3, 29 of 39 evaluable segments (74.4% were enhanced. Conclusion. In this work, we demonstrate LGE of the coronary artery vessel wall using 3.0 T MRI after a single, low-dose Gd contrast injection in CAD patients but not in healthy subjects. In the majority of the evaluated coronary segments in CAD patients, LGE of the coronary vessel wall was already detectable 30–45 minutes after administration of the contrast agent.

  19. Conditioning of the vacuum vessel walls of tokamaks, a preliminary look

    Energy Technology Data Exchange (ETDEWEB)

    Sink, D.A.

    1976-03-01

    The main features and operating characteristics of the primary vacuum system of many of the presently operating tokamak devices are presented. Particular attention is paid to the methods used to condition and clean the vessel walls in situ. For the devices discussed, a combination of a high-temperature bakeout and/or discharge cleaning is employed. In addition, discussions of the vacuum systems and wall conditioning methods anticipated for the next generation of tokamaks are presented. Since this report was written during a limited time period, it should be considered as preliminary and is not intended to be a general review. Much of the information that is presented was obtained by private communication and there is no bibliography. This study was initiated to aid in the design of TFTR. As presently envisioned, the TFTR vacuum system and methods for wall conditioning are consistent with what is presently practiced.

  20. Primary Metabolism during Biosynthesis of Secondary Wall Polymers of Protoxylem Vessel Elements.

    Science.gov (United States)

    Ohtani, Misato; Morisaki, Keiko; Sawada, Yuji; Sano, Ryosuke; Uy, Abigail Loren Tung; Yamamoto, Atsushi; Kurata, Tetsuya; Nakano, Yoshimi; Suzuki, Shiro; Matsuda, Mami; Hasunuma, Tomohisa; Hirai, Masami Yokota; Demura, Taku

    2016-11-01

    Xylem vessels, the water-conducting cells in vascular plants, undergo characteristic secondary wall deposition and programmed cell death. These processes are regulated by the VASCULAR-RELATED NAC-DOMAIN (VND) transcription factors. Here, to identify changes in metabolism that occur during protoxylem vessel element differentiation, we subjected tobacco (Nicotiana tabacum) BY-2 suspension culture cells carrying an inducible VND7 system to liquid chromatography-mass spectrometry-based wide-target metabolome analysis and transcriptome analysis. Time-course data for 128 metabolites showed dynamic changes in metabolites related to amino acid biosynthesis. The concentration of glyceraldehyde 3-phosphate, an important intermediate of the glycolysis pathway, immediately decreased in the initial stages of cell differentiation. As cell differentiation progressed, specific amino acids accumulated, including the shikimate-related amino acids and the translocatable nitrogen-rich amino acid arginine. Transcriptome data indicated that cell differentiation involved the active up-regulation of genes encoding the enzymes catalyzing fructose 6-phosphate biosynthesis from glyceraldehyde 3-phosphate, phosphoenolpyruvate biosynthesis from oxaloacetate, and phenylalanine biosynthesis, which includes shikimate pathway enzymes. Concomitantly, active changes in the amount of fructose 6-phosphate and phosphoenolpyruvate were detected during cell differentiation. Taken together, our results show that protoxylem vessel element differentiation is associated with changes in primary metabolism, which could facilitate the production of polysaccharides and lignin monomers and, thus, promote the formation of the secondary cell wall. Also, these metabolic shifts correlate with the active transcriptional regulation of specific enzyme genes. Therefore, our observations indicate that primary metabolism is actively regulated during protoxylem vessel element differentiation to alter the cell's metabolic

  1. Quantification and Statistical Analysis Methods for Vessel Wall Components from Stained Images with Masson's Trichrome: e0146954

    National Research Council Canada - National Science Library

    Pablo Hernández-Morera; Irene Castaño-González; Carlos M Travieso-González; Blanca Mompeó-Corredera; Francisco Ortega-Santana

    2016-01-01

    ... (smooth muscle fibers and extracellular matrix) in the vessel wall stained with Masson's trichrome, and a statistical method suitable for small sample sizes to analyze the results previously obtained...

  2. Structural Health Monitoring of Composite Wound Pressure Vessels

    Science.gov (United States)

    Grant, Joseph; Kaul, Raj; Taylor, Scott; Jackson, Kurt; Myers, George; Sharma, A.

    2002-01-01

    The increasing use of advanced composite materials in the wide range of applications including Space Structures is a great impetus to the development of smart materials. Incorporating these FBG sensors for monitoring the integrity of structures during their life cycle will provide valuable information about viability of the usage of such material. The use of these sensors by surface bonding or embedding in this composite will measure internal strain and temperature, and hence the integrity of the assembled engineering structures. This paper focuses on such a structure, called a composite wound pressure vessel. This vessel was fabricated from the composite material: TRH50 (a Mitsubishi carbon fiber with a 710-ksi tensile strength and a 37 Msi modulus) impregnated with an epoxy resin from NEWPORT composites (WDE-3D-1). This epoxy resin in water dispersed system without any solvents and it cures in the 240-310 degrees F range. This is a toughened resin system specifically designed for pressure applications. These materials are a natural fit for fiber sensors since the polyimide outer buffer coating of fiber can be integrated into the polymer matrix of the composite material with negligible residual stress. The tank was wound with two helical patterns and 4 hoop wraps. The order of winding is: two hoops, two helical and two hoops. The wall thickness of the composite should be about 80 mil or less. The tank should burst near 3,000 psi or less. We can measure the actual wall thickness by ultrasonic or we can burst the tank and measure the pieces. Figure 1 shows a cylinder fabricated out of carbon-epoxy composite material. The strain in different directions is measured with a surface bonded fiber Bragg gratings and with embedded fiber Bragg gratings as the cylinder is pressurized to burst pressures. Figure 2 shows the strain as a function of pressure of carbon-epoxy cylinder as it is pressurized with water. Strain is measured in different directions by multiple gratings

  3. Recording of unexpectedly high frequency vibrations of blood vessel walls in experimental arteriovenous fistulae of rabbits using a laser vibrometer.

    Science.gov (United States)

    Stehbens, W E; Liepsch, D W; Poll, A; Erhardt, W

    1995-01-01

    Because arteriovenous fistulae are associated with a palpable thrill and an audible murmur, the vibrational activity of the blood vessel walls about experimental arteriovenous fistulae in rabbits was investigated using, for the first time, a high-resolution laser vibrometer. Frequencies of mural vibrations up to 2200 Hz were recorded at different sites about the fistulae. The relationship of this vibratory activity of blood vessel walls to physiological and pathological conditions warrants further investigation.

  4. Fluid-Structure Simulations of a Ruptured Intracranial Aneurysm: Constant versus Patient-Specific Wall Thickness

    Directory of Open Access Journals (Sweden)

    S. Voß

    2016-01-01

    Full Text Available Computational Fluid Dynamics is intensively used to deepen the understanding of aneurysm growth and rupture in order to support physicians during therapy planning. However, numerous studies considering only the hemodynamics within the vessel lumen found no satisfactory criteria for rupture risk assessment. To improve available simulation models, the rigid vessel wall assumption has been discarded in this work and patient-specific wall thickness is considered within the simulation. For this purpose, a ruptured intracranial aneurysm was prepared ex vivo, followed by the acquisition of local wall thickness using μCT. The segmented inner and outer vessel surfaces served as solid domain for the fluid-structure interaction (FSI simulation. To compare wall stress distributions within the aneurysm wall and at the rupture site, FSI computations are repeated in a virtual model using a constant wall thickness approach. Although the wall stresses obtained by the two approaches—when averaged over the complete aneurysm sac—are in very good agreement, strong differences occur in their distribution. Accounting for the real wall thickness distribution, the rupture site exhibits much higher stress values compared to the configuration with constant wall thickness. The study reveals the importance of geometry reconstruction and accurate description of wall thickness in FSI simulations.

  5. A completely noninvasive method of dissolved oxygen monitoring in disposable small-scale cell culture vessels based on diffusion through permeable vessel walls.

    Science.gov (United States)

    Gupta, Priyanka A; Ge, Xudong; Kostov, Yordan; Rao, Govind

    2014-01-01

    Disposable cell culture vessels are extensively used at small scales for process optimization and validation, but they lack monitoring capabilities. Optical sensors that can be easily adapted for use in small-scale vessels are commercially available for pH, dissolved oxygen (DO), and dissolved carbon dioxide (DCO2 ). However, their use has been limited due to the contamination and compatibility issues. We have developed a novel solution to these problems for DO monitoring. Oxygen diffusion through permeable vessel wall can be exploited for noninvasive monitoring. An optical oxygen sensor can be placed outside the oxygen permeable vessel wall thereby allowing oxygen diffusing through the vessel wall to be detected by the sensor. This way the sensor stays separate from the cell culture and there are no concerns about contaminants or leachants. Here we implement this method for two cell culture devices: polystyrene-made T-75 tissue culture flask and fluorinated ethylene propylene (FEP)-made Vuelife(®) cell culture bag. Additionally, mammalian and microbial cell cultures were performed in Vuelife(®) cell culture bags, proving that a sensor placed outside can be used to track changes in cell cultures. This approach toward noninvasive monitoring will help in integrating cell culture vessels with sensors in a seamless manner. © 2013 American Institute of Chemical Engineers.

  6. Upper and Lower Bound Limit Loads for Thin-Walled Pressure Vessels Used for Aerosol Cans

    Directory of Open Access Journals (Sweden)

    Stephen John Hardy

    2009-01-01

    Full Text Available The elastic compensation method proposed by Mackenzie and Boyle is used to estimate the upper and lower bound limit (collapse loads for one-piece aluminium aerosol cans, which are thin-walled pressure vessels subjected to internal pressure loading. Elastic-plastic finite element predictions for yield and collapse pressures are found using axisymmetric models. However, it is shown that predictions for the elastic-plastic buckling of the vessel base require the use of a full three-dimensional model with a small unsymmetrical imperfection introduced. The finite element predictions for the internal pressure to cause complete failure via collapse fall within the upper and lower bounds. Hence the method, which involves only elastic analyses, can be used in place of complex elastic-plastic finite element analyses when upper and lower bound estimates are adequate for design purposes. Similarly, the lower bound value underpredicts the pressure at which first yield occurs.

  7. [The exogenous and genetic components of some vessel wall characteristics in the pig (author's transl)].

    Science.gov (United States)

    Wegner, W

    1975-01-01

    Insufficiencies of the circulatory system and increasing transport losses in pigs as well as analogies with respect to atherosclerosis of men and swine were the motives for a broad statistical investigation of important characteristics of the circulatory system in a big population of female German landrace pigs, fattened as progeny groups under identical conditions in a testing station and slaughtered at 100 kg weight. As the most essential results, highly significant seasonal and genetical influences on several traits are to be mentioned, and some meaningful correlations between them: Plasma cholesterol, ceruloplasmin and hematocrit showed markedly lower levels in the summer and increased values in the cold season; the thickness of the intima (aorta and arteria pulmonalis) was quite distinctly greatest in the spring, this phenomenon being almost exactly paralleled by augmented amounts of copper and iron in the aortic wall. Increased heart weights were again found in the cold, decreased ones in the warm seasons. On average, bigger hearts and vessels were accompanied by higher elastin contents of the aorta, but these contents stood in very significant negative correlation to the ash content and the amounts of certain mineral components (Ca, Mg and P) of the vessel wall, especially to the ash percentage of the elastic fibers. This indicates that calcifying and mineralizing processes in the wall obviously take place at the cost of the elastic components. The estimation of heritabilities in half and full sibs revealed with h2 = 60% high henetic influences on the elastin content of the aorta and equally so on the ash percentage of elastic fibers. Future investigations must correlate these findings with direct measurements of biomechanical and rheological properties of the vessels.

  8. Carotid Intraplaque Hemorrhage Imaging with Quantitative Vessel Wall T1 Mapping: Technical Development and Initial Experience.

    Science.gov (United States)

    Qi, Haikun; Sun, Jie; Qiao, Huiyu; Chen, Shuo; Zhou, Zechen; Pan, Xinlei; Wang, Yishi; Zhao, Xihai; Li, Rui; Yuan, Chun; Chen, Huijun

    2017-11-08

    Purpose To develop a three-dimensional (3D) high-spatial-resolution time-efficient sequence for use in quantitative vessel wall T1 mapping. Materials and Methods A previously described sequence, simultaneous noncontrast angiography and intraplaque hemorrhage (SNAP) imaging, was extended by introducing 3D golden angle radial k-space sampling (GOAL-SNAP). Sliding window reconstruction was adopted to reconstruct images at different inversion delay times (different T1 contrasts) for voxelwise T1 fitting. Phantom studies were performed to test the accuracy of T1 mapping with GOAL-SNAP against a two-dimensional inversion recovery (IR) spin-echo (SE) sequence. In vivo studies were performed in six healthy volunteers (mean age, 27.8 years ± 3.0 [standard deviation]; age range, 24-32 years; five male) and five patients with atherosclerosis (mean age, 66.4 years ± 5.5; range, 60-73 years; five male) to compare T1 measurements between vessel wall sections (five per artery) with and without intraplaque hemorrhage (IPH). Statistical analyses included Pearson correlation coefficient, Bland-Altman analysis, and Wilcoxon rank-sum test with data permutation by subject. Results Phantom T1 measurements with GOAL-SNAP and IR SE sequences showed excellent correlation (R(2) = 0.99), with a mean bias of -25.8 msec ± 43.6 and a mean percentage error of 4.3% ± 2.5. Minimum T1 was significantly different between sections with IPH and those without it (mean, 371 msec ± 93 vs 944 msec ± 120; P = .01). Estimated T1 of normal vessel wall and muscle were 1195 msec ± 136 and 1117 msec ± 153, respectively. Conclusion High-spatial-resolution (0.8 mm isotropic) time-efficient (5 minutes) vessel wall T1 mapping is achieved by using the GOAL-SNAP sequence. This sequence may yield more quantitative reproducible biomarkers with which to characterize IPH and monitor its progression. (©) RSNA, 2017.

  9. Remote through-wall sampling of the Trawsfynydd reactor pressure vessel: an overview

    Energy Technology Data Exchange (ETDEWEB)

    Curry, A.; Clayton, R. [Magnox Electric, Berkeley (United Kingdom)

    1997-02-01

    This paper summarizes the application of robotic equipment for gaining access to, and removing through-wall samples, from, welds of the reactor pressure vessel at Trawsfyndd power station. The environment, which presents hazards due to ionising radiation, radioactive contamination and asbestos-bearing materials is described. The means of access, by use of remote vehicles with robotic manipulators supported by additional vehicles, it reviewed. The use of abrasive water jet cutting for sample removal is introduced. The relative advantages and disadvantages of this technique are discussed. (Author).

  10. Remote through-wall sampling of the Trawsfynydd reactor pressure vessel: an overview

    Energy Technology Data Exchange (ETDEWEB)

    Curry, A.; Clayton, R. [Magnox Electric, Dartford (United Kingdom). Remote Operations

    1996-12-31

    This paper summarises the application of robotic equipment for gaining access to and removing through-wall samples from welds of the reactor pressure vessel at Trawsfynydd power station. The environment, which presents hazards due to ionising radiation, radioactive contamination and asbestos bearing materials is described. The means of access, by use of remote vehicles complete with robotic manipulators supported by additional vehicles, is reviewed. The use of Abrasive Water Jet Cutting for sample removal is introduced. The relative advantages and disadvantages of this technique are discussed. (UK).

  11. Estimation of the radial force on the tokamak vessel wall during fast transient events

    Energy Technology Data Exchange (ETDEWEB)

    Pustovitov, V. D., E-mail: pustovitov-vd@nrcki.ru [National Research Center Kurchatov Institute (Russian Federation)

    2016-11-15

    The radial force balance in a tokamak during fast transient events with a duration much shorter than the resistive time of the vacuum vessel wall is analyzed. The aim of the work is to analytically estimate the resulting integral radial force on the wall. In contrast to the preceding study [Plasma Phys. Rep. 41, 952 (2015)], where a similar problem was considered for thermal quench, simultaneous changes in the profiles and values of the pressure and plasma current are allowed here. Thereby, the current quench and various methods of disruption mitigation used in the existing tokamaks and considered for future applications are also covered. General formulas for the force at an arbitrary sequence or combination of events are derived, and estimates for the standard tokamak model are made. The earlier results and conclusions are confirmed, and it is shown that, in the disruption mitigation scenarios accepted for ITER, the radial forces can be as high as in uncontrolled disruptions.

  12. Structure and mechanics of starfish body wall.

    Science.gov (United States)

    O'Neill, P

    1989-11-01

    The structure of the dorsal body wall of the starfish Echinaster spinulosus was studied using polarized light microscopy of frozen tissues, scanning electron microscopy and histology. The collagen fibres of the body wall form a three-dimensional orthogonal web. Voids in the web contain ossicles and papulae. The orthogonal web delivers dimensional stability but allows shear necessary for ray torsion. The ossicles and fibres interact to load the fibres in tension and the ossicles in compression. Strain rates of the dorsal body wall were measured on live animals during typical movements. Uniaxial tension tests of the body wall yielded Young's moduli of 267 MPa (longitudinal), 249 MPa (transverse) and 353 MPa (bias); curves were essentially linear. The body wall was approximately linearly viscoelastic and showed hysteresis at 0.01 Hz. Stress relaxation over five decades of time (in seconds) yielded relaxation spectra with peaks in relaxation time at 2.96-3.35, depending on test direction. Stress relaxation caused the connective tissue to soften. The surface of fractured stress-relaxed tissue revealed wispy, dissociated fibril tufts, whereas unrelaxed fractures produced blunt-ended fibre bundles. Neural control was necessary for body wall integrity.

  13. Saccharomyces cerevisiae gene expression changes during rotating wall vessel suspension culture

    Science.gov (United States)

    Johanson, Kelly; Allen, Patricia L.; Lewis, Fawn; Cubano, Luis A.; Hyman, Linda E.; Hammond, Timothy G.

    2002-01-01

    This study utilizes Saccharomyces cerevisiae to study genetic responses to suspension culture. The suspension culture system used in this study is the high-aspect-ratio vessel, one type of the rotating wall vessel, that provides a high rate of gas exchange necessary for rapidly dividing cells. Cells were grown in the high-aspect-ratio vessel, and DNA microarray and metabolic analyses were used to determine the resulting changes in yeast gene expression. A significant number of genes were found to be up- or downregulated by at least twofold as a result of rotational growth. By using Gibbs promoter alignment, clusters of genes were examined for promoter elements mediating these genetic changes. Candidate binding motifs similar to the Rap1p binding site and the stress-responsive element were identified in the promoter regions of differentially regulated genes. This study shows that, as in higher order organisms, S. cerevisiae changes gene expression in response to rotational culture and also provides clues for investigations into the signaling pathways involved in gravitational response.

  14. Ex vivo blood vessel bioreactor for analysis of the biodegradation of magnesium stent models with and without vessel wall integration.

    Science.gov (United States)

    Wang, Juan; Liu, Lumei; Wu, Yifan; Maitz, Manfred F; Wang, Zhihong; Koo, Youngmi; Zhao, Ansha; Sankar, Jagannathan; Kong, Deling; Huang, Nan; Yun, Yeoheung

    2017-03-01

    Current in vitro models fail in predicting the degradation rate and mode of magnesium (Mg) stents in vivo. To overcome this, the microenvironment of the stent is simulated here in an ex vivo bioreactor with porcine aorta and circulating medium, and compared with standard static in vitro immersion and with in vivo rat aorta models. In ex vivo and in vivo conditions, pure Mg wires were exposed to the aortic lumen and inserted into the aortic wall to mimic early- and long-term implantation, respectively. Results showed that: 1) Degradation rates of Mg were similar for all the fluid diffusion conditions (in vitro static, aortic wall ex vivo and in vivo); however, Mg degradation under flow condition (i.e. in the lumen) in vivo was slower than ex vivo; 2) The corrosion mode in the samples can be mainly described as localized (in vitro), mixed localized and uniform (ex vivo), and uniform (in vivo); 3) Abundant degradation products (MgO/Mg(OH)2 and Ca/P) with gas bubbles accumulated around the localized degradation regions ex vivo, but a uniform and thin degradation product layer was found in vivo. It is concluded that the ex vivo vascular bioreactor provides an improved test setting for magnesium degradation between static immersion and animal experiments and highlights its promising role in bridging degradation behavior and biological response for vascular stent research. Magnesium and its alloys are candidates for a new generation of biodegradable stent materials. However, the in vitro degradation of magnesium stents does not match the clinical degradation rates, corrupting the validity of conventional degradation tests. Here we report an ex vivo vascular bioreactor, which allows simulation of the microenvironment with and without blood vessel integration to study the biodegradation of magnesium implants in comparison with standard in vitro test conditions and with in vivo implantations. The bioreactor did simulate the corrosion of an intramural implant very well, but

  15. Illinois Walls in alternative market structures

    NARCIS (Netherlands)

    Schinkel, M.P.; Tuinstra, J.

    2005-01-01

    This note extends on our paper Illinois Walls: How Barring Indirect Purchaser Suits Facilitates Collusion (Schinkel, Tuinstra and Rüggeberg, 2005, henceforth STR). It presents analyses of two alternative, more competitive, market structures to conclude that when the conditions for existence of

  16. "Sausage-string" appearance of arteries and arterioles can be caused by an instability of the blood vessel wall

    DEFF Research Database (Denmark)

    Jacobsen, Jens Christian Brings; Beierholm, Ulrik; Mikkelsen, Rene

    2002-01-01

    Vascular damage induced by acute hypertension is preceded by a peculiar pattern where blood vessels show alternating regions of constrictions and dilations ("sausages on a string"). The pattern occurs in the smaller blood vessels, and it plays a central role in causing the vascular damage....... A related vascular pattern has been observed in larger vessels from several organs during angiography. In the larger vessels the occurrence of the pattern does not appear to be related to acute hypertension. A unifying feature between the phenomenon in large and small vessels seems to be an increase...... observed experimentally. Most importantly, it suggests that the "sausaging" phenomenon is neither caused by a mechanical failure of the vessel wall due to a high blood pressure nor is it due to standing pressure waves caused by the beating of the heart. Rather, it is the expression of a general instability...

  17. Dynamic vessel wall properties and their reproducibility in subjects with increased cardiovascular risk.

    Science.gov (United States)

    van den Berkmortel, F; Wollersheim, H; van Langen, H; Thien, T

    1998-06-01

    To determine reproducibility figures of dynamic arterial wall properties such as cross-sectional compliance (CC) and distensibility (DC) in subjects with increased cardiovascular risk, in comparison with healthy adults. A total of 34 persons were divided into three groups with varying cardiovascular risk factors. Diameters (D) and diameter changes (deltaD) during the heart cycle of both common carotid (CCA) and right common femoral (CFA) arteries were measured by a vessel wall movement detector system. Blood pressures (BP) were recorded non-invasively by a semi-automated oscillometric device. CC (=piD(deltaD/2deltaP) in unit mm2/kPa) and DC (=2deltaD/D)/deltaP in unit 10(-3)/kPa) were calculated from the above-mentioned parameters. Measurements were performed twice during one visit and twice again with a time interval of at least 3 days to determine intra-observer intra- and intersession variability. Reproducibility figures of CC and DC of the CCA varied between 8 and 12%, and between 13 and 22% for the CFA. Intra-observer intra- and intersession variability were similar in the three groups. In our studies the reproducibility of dynamic vascular wall properties determined by ultrasound was good. Despite differences in the absolute values for CC and DC in groups with increased cardiovascular risk, mean reproducibility figures remained at a similar level (8-12%) as in healthy volunteers.

  18. Significance of fluid-structure interaction phenomena for containment response to ex-vessel steam explosions

    Energy Technology Data Exchange (ETDEWEB)

    Almstroem, H.; Sundel, T. [National Defence Research Establishment, Stockholm (Sweden); Frid, W.; Engelbrektson, A.

    1998-01-01

    When studying the structural response of a containment building to ex-vessel steam explosion loads, a two-step procedure is often used. In the first step of this procedure the structures are treated as rigid and the pressure-time history generated by the explosion at the rigid wall is calculated. In the second step the calculated pressure is applied to the structures. The obvious weakness of the two-step procedure is that it does not correspond to the real dynamic behaviour of the fluid-structure system. The purpose of this paper is to identify and evaluate the relevant fluid-structure interaction phenomena. This is achieved through direct treatment of the explosion process and the structural response. The predictions of a direct and two-step treatment are compared for a BWR Mark II containment design, consisting of two concentric walls interacting with water masses in the central and annular pools. It is shown that the two-step approach leads to unrealistic energy transfer in the containment system studied, and to significant overestimation of the deflection of the containment wall. As regards the pedestal wall, the direct method analysis shows that the flexibility of this wall affects the pressure-time history considerably. Three load types have been identified for this wall namely shock load, water blow as a result of water cavitation, and hydrodynamic load. Reloading impulse due to cavitation phenomena plays an important role as it amounts to about 40% of the total impulse load. Investigation of the generality of the cavitation phenomena in the context of ex-vessel steam explosion loads was outside the scope of this work. (author)

  19. Significance of fluid-structure interaction phenomena for containment response to ex-vessel steam explosions

    Energy Technology Data Exchange (ETDEWEB)

    Almstroem, H.; Sundel, T. (Nat. Defence Res. Establ., Tumba (Sweden)); Frid, W. (Swedish Nuclear Power Inspectorate, SE-10658, Stockholm (Sweden)); Engelbrektson, A. (VBB/SWECO, Box 34044, SE-10026, Stockholm (Sweden))

    1999-05-01

    When studying the structural response of a containment building to ex-vessel steam explosion loads, a two-step procedure is often used. In the first step of this procedure the structures are treated as rigid and the pressure-time history generated by the explosion, at the rigid wall, is calculated. In the second step the calculated pressure is applied to the structures. The obvious weakness of the two-step procedure is that it does not correspond to the real dynamic behaviour of the fluid-structure system. The purpose of this paper is to identify and evaluate the relevant fluid-structure interaction phenomena. This is achieved through direct treatment of the explosion process and the structural response. The predictions of a direct and two-step treatment are compared for a BWR Mark II containment design, consisting of two concentric walls interacting with water masses in the central and annular pools. It is shown that the two-step approach leads to unrealistic energy transfer in the containment system studied and to significant overestimation of the deflection of the containment wall. As regards the pedestal wall, the direct method analysis shows that the flexibility of this wall affects the pressure-time history considerably. Three load types have been identified for this wall namely shock load, water blow as a result of water cavitation, and hydrodynamic load. Reloading impulse due to cavitation phenomena plays an important role as it amounts to [approx]40% of the total impulse load. Investigation of the generality of the cavitation phenomena in the context of ex-vessel steam explosion loads was outside the scope of this work. (orig.) 5 refs.

  20. Intra-specific trends of lumen and wall resistivities of vessels within the stem xylem vary among three woody plants.

    Science.gov (United States)

    Ooeda, Hiroki; Terashima, Ichiro; Taneda, Haruhiko

    2018-02-01

    Water flow through xylem vessels encounters hydraulic resistance when passing through the vessel lumen and end wall. Comparative studies have reported that lumen and end wall resistivities co-limit water flow through stem xylem in several angiosperm woody species that have vessels of different average diameter and length. This study examined the intra-specific relationship between the lumen and end wall resistivities (Rlumen and Rwall) for vessels within the stem xylem using three deciduous angiosperm woody species found in temperate forest. Morus australis Poir. and Acer rufinerve Siebold et Zucc. are early- and late-successional species, and Vitis coignetiae Pulliat ex Planch is a woody liana. According to the Hagen-Poiseuille equation, Rlumen is proportional to the fourth power of vessel diameter (D), whereas vessel length (L) and inter-vessel pit area (Apit) determine Rwall. To estimate Rlumen and Rwall, the scaling relationships between the L and D and between Apit and D were measured. The scaling exponents between L and D were 1.47, 3.19 and 2.86 for A. rufinerve, M. australis and V. coignetiae, respectively, whereas those between Apit and D were 0.242, 2.11 and 2.68, respectively. Unlike the inter-specific relationships, the wall resistivity fraction (Rwall/(Rlumen + Rwall)) within xylem changed depending on D. In M. australis and V. coignetiae, this fraction decreased with increasing D, while in A. rufinerve, it increased with D. Vessels with a high wall resistivity fraction have high Rwall and total resistivity but are expected to have low susceptibility to xylem cavitation due to a small cumulative Apit. In contrast, vessels with a low wall resistivity fraction have low Rwall and total resistivity but high susceptibility to xylem cavitation. Because the wall resistivity fraction varies with D, the stem xylem contains vessels with different hydraulic efficiencies and safety to xylem cavitation. These features produce differences in the hydraulic properties

  1. Structural design for a 10-GWh SMES vacuum vessel

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, J.G.; Anderson, C.A.

    1978-01-01

    An approximate solution to the problem of the nonlinear elastic deformation of a periodically point-supported cylindrical shell is obtained. This solution is used to investigate the structural design of the vacuum vessel for the large underground superconducting magnetic energy storage (SMES) concept. Vacuum vessel designs are evaluated by varying such parameters as shell thickness, support spacing, material properties and physical configuration to keep the amount of material used and construction cost to a minimum.

  2. Histological study on the influences of an ultrasonic scalpel on skeletonized vessel wall.

    Science.gov (United States)

    Fukata, Yoshio; Horike, Kazuya; Kano, Masashi

    2002-10-01

    The objective of this study was to histologically clarify the difference of vascular wall damage when an ultrasonic scalpel is used in varied ways in the vicinity of a vessel. 1) The surface of sodium carbonate-containing jelly was manually brushed with the edge of a dissecting hook type Harmonic Scalpel (HS), and the thickness of the air bubble layer was measured to investigate the range to which the vibrations of the instrument reached. 2) The internal thoracic artery (ITA), radial artery (RA) and vein skeletonized were cut bluntly or brushed using HS ex vivo, and tissue damages were observed histologically. 3) The depth of thermal degeneration (TD) of residual stumps of ITAs skeletonized by HS using an output power level (level) of 2 and the quick touch method at the time of coronary arterial bypass grafting (CABG) were investigated histologically. 1) The mean thickness of the air bubble layers by single brushing was 3.7, 3.7 and 3.1 mm at level 4, 3 and 2, and no significant difference. When brushed 5 times, it was 6.9, 5.5 and 6.7 mm, respectively, showing marked increases compared with single brushing. 2) A: One side of the RA stump cut with a dissecting hook at level 2 was nicely occluded by a degenerated protein coagulum, but the contralateral had no coagulum. An ITA cut by a shear type blade at level 3 showed that both stumps were nicely occluded, but the vessel wall was introverted and fragmented. B: ITAs brushed 5 or 10 times at level 2 showed that TD occurred in tunica externa, the mean depth of 100 or 203 microm, and never exceeded the external elastic lamella. RAs brushed 10 times at level 2 and 3 showed that TD and air bubble generation occurred in the tunica externa, and the mean depth was 203 and 203 microm. However, TD exceeded the external lamella in some cases at level 3. Veins brushed 10 times at level 3 showed that TD spread to all layers. 3) The depth of TD in ITAs skeletonized clinically by HS was 400 to 530 microm, and apart from the

  3. Construction and characterisation of MRI coils for vessel wall imaging at 7 tesla

    OpenAIRE

    2014-01-01

    Atherosclerotic plaques in the bifurcation of the carotid artery vessels can pose a significant stroke risk from stenosis, thrombosis and emboli, or plaque rupture. However, the possibility of the latter depends on the structure of the plaque and its stability. So far, the assessment of such depositions, and the evaluation of the risk they pose, is not satisfactory with 3 Tesla black blood imaging. It is expected that the SNR increase at 7 Tesla, together with an appropriate and patient-safe ...

  4. Evaluation of acoustic emission signals during monitoring of thick-wall vessels operating at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Anastasopoulos, A.; Tsimogiannis, A. [Envirocoustics S.A., El. Venizelou 7 and Delfon, Athens (Greece)

    2004-07-01

    Acoustic Emission testing of thick wall vessels, operating at elevated temperatures is discussed and pattern recognition methodologies for AE data evaluation are presented. Two different types of testing procedures are addressed: Cool Down monitoring and semi-continuous periodic monitoring. In both types of tests, temperature variation is the driving force of AE as opposed to traditional AE testing where controlled pressure variation is used as AE stimulus. Representative examples of reactors cool down testing as well as in-process vessel monitoring are given. AE activity as a function of temperature and pressure variation is discussed. In addition to the real-time limited criteria application, unsupervised pattern recognition is applied as a post-processing tool for multidimensional sorting, noise discrimination, characterizing defects and/or damage. On the other hand, Supervised Pattern Recognition is used for data classification in repetitive critical tests, leading to an objective quantitative comparison between repeated tests. Results show that damage sustained by the equipment can be described by the plotting the cumulative energy of AE, from critical signal classes, versus temperature. Overall, the proposed methodology can reduce the complexity of AE tests in many cases leading to higher efficiency. The possibility for real time signals classification, during permanent AE installations and continuous monitoring is discussed. (orig.)

  5. Hydrogen uptake in vanadium first wall structures

    Energy Technology Data Exchange (ETDEWEB)

    Simonen, E.P.; Jones, R.H. [Pacific Northwest National Laboratory, Richland, WA (United States)

    1996-04-01

    Evaluation of hydrogen sources and transport are needed to assess the mechanical integrity of V structures. Two sources include implantation and transmutation. The proposed coatings for the DEMO and ITER first wall strongly influence retention of hydrogen isotopes. Upper limit calculations of hydrogen inventory were based on recycling to the plasma and an impermeable coolant-side coating. Hydrogen isotope concentrations in V approaching 1,000 appm may be activated.

  6. Rupture Properties of Blood Vessel Walls Measured by Pressure-Imposed Test

    Science.gov (United States)

    Ohashi, Toshiro; Sugita, Syukei; Matsumoto, Takeo; Kumagai, Kiichiro; Akimoto, Hiroji; Tabayashi, Koichi; Sato, Masaaki

    It is expected to be clinically useful to know the mechanical properties of human aortic aneurysms in assessing the potential for aneurysm rupture. For this purpose, a newly designed experimental setup was fabricated to measure the rupture properties of blood vessel walls. A square specimen of porcine thoracic aortas is inflated by air pressure at a rate of 10mmHg/s (≈1.3MPa/s) until rupture occurs. Mean breaking stress was 1.8±0.4 MPa (mean±SD) for the specimens proximal to the heart and 2.3±0.8MPa for the distal specimens, which are not significantly different to those values obtained longitudinally from conventional tensile tests. Moreover, the local breaking stretch ratio in the longitudinal direction was significantly higher at the ruptured site (2.7±0.5) than at the unruptured site (2.2±0.4). This testing system for studying the rupture properties of aortic walls is expected to be applicable to aortic aneurysms. Experimental verification of the present technique for the homogeneous, isotropic material is also presented.

  7. Added Value of Vessel Wall Magnetic Resonance Imaging for Differentiation of Nonocclusive Intracranial Vasculopathies.

    Science.gov (United States)

    Mossa-Basha, Mahmud; Shibata, Dean K; Hallam, Danial K; de Havenon, Adam; Hippe, Daniel S; Becker, Kyra J; Tirschwell, David L; Hatsukami, Thomas; Balu, Niranjan; Yuan, Chun

    2017-11-01

    Our goal is to determine the added value of intracranial vessel wall magnetic resonance imaging (IVWI) in differentiating nonocclusive vasculopathies compared with luminal imaging alone. We retrospectively reviewed images from patients with both luminal and IVWI to identify cases with clinically defined intracranial vasculopathies: atherosclerosis (intracranial atherosclerotic disease), reversible cerebral vasoconstriction syndrome, and inflammatory vasculopathy. Two neuroradiologists blinded to clinical data reviewed the luminal imaging of defined luminal stenoses/irregularities and evaluated the pattern of involvement to make a presumed diagnosis with diagnostic confidence. Six weeks later, the 2 raters rereviewed the luminal imaging in addition to IVWI for the pattern of wall involvement, presence and pattern of postcontrast enhancement, and presumed diagnosis and confidence. Analysis was performed on per-lesion and per-patient bases. Thirty intracranial atherosclerotic disease, 12 inflammatory vasculopathies, and 12 reversible cerebral vasoconstriction syndrome patients with 201 lesions (90 intracranial atherosclerotic disease, 64 reversible cerebral vasoconstriction syndrome, and 47 inflammatory vasculopathy lesions) were included. For both per-lesion and per-patient analyses, there was significant diagnostic accuracy improvement with luminal imaging+IVWI when compared with luminal imaging alone (per-lesion: 88.8% versus 36.1%; Pimprove the differentiation of nonocclusive intracranial vasculopathies when combined with traditional luminal imaging modalities. © 2017 American Heart Association, Inc.

  8. Distinct defects in collagen microarchitecture underlie vessel-wall failure in advanced abdominal aneurysms and aneurysms in Marfan syndrome

    NARCIS (Netherlands)

    Lindeman, J.H.N.; Ashcroft, B.A.; Beenakker, J.-W.M.; Es, M. van; Koekkoek, N.B.R.; Prins, F.A.; Tielemans, J.F.; Abdul-Hussien, H.; Bank, R.A.; Oosterkamp, T.H.

    2010-01-01

    An aneurysm of the aorta is a common pathology characterized by segmentalweakeningof the artery.Althoughit isgenerally accepted that the vessel-wall weakening is caused by an impaired collagen metabolism, a clear association has been demonstrated only for rare syndromes such as the vascular type

  9. Effect of Heat Flux on Creep Stresses of Thick-Walled Cylindrical Pressure Vessels

    Directory of Open Access Journals (Sweden)

    Mosayeb Davoudi Kashkoli

    2014-06-01

    Full Text Available Assuming that the thermo-creep response of the material is governed by Norton’s law, an analytical solution is presented for the calculation of time-dependent creep stresses and displacements of homogeneous thick-walled cylindrical pressure vessels. For the stress analysis in a homogeneous pressure vessel, having material creep behavior, the solutions of the stresses at a time equal to zero (i.e. the initial stress state are needed. This corresponds to the solution of materials with linear elastic behavior. Therefore, using equations of equilibrium, stress-strain and strain-displacement, a differential equation for displacement is obtained and then the stresses at a time equal to zero are calculated. Using Norton’s law in the multi-axial form in conjunction with the above-mentioned equations in the rate form, the radial displacement rate is obtained and then the radial, circumferential and axial creep stress rates are calculated. When the stress rates are known, the stresses at any time are calculated iteratively. The analytical solution is obtained for the conditions of plane strain and plane stress. The thermal loading is as follows: inner surface is exposed to a uniform heat flux, and the outer surface is exposed to an airstream. The heat conduction equation for the one-dimensional problem in polar coordinates is used to obtain temperature distribution in the cylinder. The pressure, inner radius and outer radius are considered constant. Material properties are considered as constant. Following this, profiles are plotted for the radial displacements, radial stress, circumferential stress and axial stress as a function of radial direction and time.

  10. Numerical modeling of the pulse wave propagation in large blood vessels based on liquid and wall interaction

    Science.gov (United States)

    Rup, K.; Dróżdż, A.

    2014-08-01

    The purpose of this article is to develop a non-linear, one-dimensional model of pulse wave propagation in the arterial cardiovascular system. The model includes partial differential equations resulting from the balance of mass and momentum for the fluid-filled area and the balance equation for the area of the wall and vessels. The considered mathematical model of pulse wave propagation in the thoracic aorta section takes into account the viscous dissipation of fluid energy, realistic values of parameters describing the physicochemical properties of blood and vessel wall. Boundary and initial conditions contain the appropriate information obtained from in vivo measurements. As a result of the numerical solution of the mass and momentum balance equations for the blood and the equilibrium equation for the arterial wall area, time- dependent deformation, respective velocity profiles and blood pressure were determined.

  11. Atherosclerosis: contrast-enhanced MR imaging of vessel wall in rabbit model--comparison of gadofosveset and gadopentetate dimeglumine.

    Science.gov (United States)

    Lobbes, Marc B I; Miserus, Robbert-Jan J H M; Heeneman, Sylvia; Passos, Valeria Lima; Mutsaers, Peter H A; Debernardi, Nicola; Misselwitz, Bernd; Post, Mark; Daemen, Mat J A P; van Engelshoven, Jos M A; Leiner, Tim; Kooi, Marianne E

    2009-03-01

    To investigate the potential of gadofosveset for contrast material-enhanced magnetic resonance (MR) imaging of plaque in a rabbit model of atherosclerosis. All experiments were approved by the animal ethics committee. Thirty-one New Zealand White rabbits were included in one of four study groups: animals with atherosclerosis imaged with gadofosveset (n = 10) or gadopentetate dimeglumine (n = 7) and control animals imaged with gadofosveset (n = 7) or gadopentetate dimeglumine (n = 7). Aortic atherosclerosis was induced through endothelial denudation combined with a cholesterol-enriched diet. Control rabbits underwent a sham surgical procedure and received a regular diet. After 8 weeks, pre- and postcontrast T1-weighted MR images of the aortic vessel wall were acquired. Relative signal enhancement was determined with dedicated software. Statistical analysis was performed by using a generalized linear mixed model. Immunohistochemical staining with CD31 and albumin was used to assess microvessel density and the albumin content of the vascular wall. Group differences were analyzed by using a chi(2) test. Gadofosveset spatial distribution and content within the vessel wall were determined with proton-induced x-ray emission (PIXE) analysis. Postcontrast signal enhancement was significantly greater for atherosclerotic than for control animals imaged with gadofosveset (P = .022). Gadopentetate dimeglumine could not enable discrimination between normal and atherosclerotic vessel walls (P = .428). PIXE analysis showed higher amounts of gadopentetate dimeglumine than gadofosveset in both atherosclerotic and normal rabbit aortas. Immunohistochemical staining revealed the presence of albumin and increased microvessel density in the vascular walls of atherosclerotic rabbits. These results suggest that gadofosveset can be used to differentiate between atherosclerotic and normal rabbit vessel walls. http://radiology.rsnajnls.org/cgi/content/full/250/3/682/DC1. RSNA, 2009

  12. Industrial safety of pressure vessels - structural integrity point of view

    Directory of Open Access Journals (Sweden)

    Sedmak Aleksandar

    2016-01-01

    Full Text Available This paper presents different aspects of pressure vessel safety in the scope of industrial safety, focused to the chemical industry. Quality assurance, including application of PED97/23 has been analysed first, followed shortly by the risk assessment and in details by the structural integrity approach, which has been illustrated with three case studies. One important conclusion, following such an approach, is that so-called water proof testing can actually jeopardize integrity of a pressure vessel instead of proving it. [Projekat Ministarstva nauke Republike Srbije, br. TR 174004 i br. TR 33044

  13. ITER vacuum vessel structural analysis completion during manufacturing phase

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, J.-M., E-mail: jean-marc.martinez@live.fr [ITER Organization, Route Vinon sur Verdon, CS 90046, 13067, St. Paul lez Durance, Cedex (France); Alekseev, A.; Sborchia, C.; Choi, C.H.; Utin, Y.; Jun, C.H.; Terasawa, A.; Popova, E.; Xiang, B.; Sannazaro, G.; Lee, A.; Martin, A.; Teissier, P.; Sabourin, F. [ITER Organization, Route Vinon sur Verdon, CS 90046, 13067, St. Paul lez Durance, Cedex (France); Caixas, J.; Fernandez, E.; Zarzalejos, J.M. [F4E, c/Josep Pla, n.2, Torres Diagonal Litoral, Edificio B3, E-08019, Barcelona (Spain); Kim, H.-S.; Kim, Y.G. [ITER Korea, National Fusion Research Institute, Daejeon (Korea, Republic of); Privalova, E. [NTC “Sintez”, Efremov Inst., 189631 Metallostroy, St. Petersburg (Russian Federation); and others

    2016-11-01

    Highlights: • ITER Vacuum Vessel (VV) is a part of the first barrier to confine the plasma. • A Nuclear Pressure Equipment necessitates Agreed Notified Body to assure design, fabrication, and conformance testing and quality assurance. • Some supplementary RCC-MR margin targets have been considered to guarantee considerable structural margins in areas not inspected in operation. • Many manufacturing deviation requests (MDR) and project change requests (PCR) impose to re-evaluate the structural margin. • Several structural analyses were performed with global and local models to guarantee the structural integrity of the whole ITER Vacuum Vessel. - Abstract: Some years ago, analyses were performed by ITER Organization Central Team (IO-CT) to verify the structural integrity of the ITER vacuum vessel baseline design fixed in 2010 and classified as a Protection Important Component (PIC). The manufacturing phase leads the ITER Organization domestic agencies (IO-DA) and their contracted manufacturers to propose detailed design improvements to optimize the manufacturing or inspection process. These design and quality inspection changes can affect the structural margins with regards to the Codes&Standards and thus oblige to evaluate one more time the modified areas. This paper proposes an overview of the additional analyses already performed to guarantee the structural integrity of the manufacturing designs. In this way, CT and DAs have been strongly involved to keep the considerable margins obtained previously which were used to fix reasonable compensatory measures for the lack of In Service Inspections of a Nuclear Pressure Equipment (NPE).

  14. Structural design and manufacturing of TPE-RX vacuum vessel

    Energy Technology Data Exchange (ETDEWEB)

    Sago, H.; Orita, J.; Kaguchi, H.; Ishigami, Y. [Mitsubishi Heavy Ind. Ltd., Kobe (Japan); Urata, K.; Kudough, F. [Mitsubishi Heavy Industries, Ltd., Tokyo (Japan); Hasegawa, M.; Oyabu, I. [Mitsubishi Electric Co., Tokyo (Japan); Yagi, Y.; Sekine, S.; Shimada, T.; Hirano, Y.; Sakakita, H.; Koguchi, H. [Electrotechnical Laboratory, Tsukuba (Japan)

    1999-10-01

    TPE-RX is a newly constructed, large-sized reversed field pinch (RFP) machine installed at the Electrotechnical Laboratory of the Ministry of International Trade and Industry in Japan. This is the third largest RFP in the world. Major and minor radii of the plasma are 1.72 and 0.45 m, respectively. TPE-RX aims to optimize plasma confinement up to 1 MA. RFP plasma configuration was successfully obtained in March 1998. This paper reports the structural design and manufacturing of the vacuum vessel of TPE-RX. The supporting system on the bellows sections of the vessel was designed based on a detailed finite element method. The integrity of the vacuum vessel against a plasma disruption has been confirmed using dynamic inelastic analyses. (orig.)

  15. Coherent structures in wall-bounded turbulence.

    Science.gov (United States)

    Dennis, David J C

    2015-01-01

    The inherent difficulty of understanding turbulence has led to researchers attacking the topic in many different ways over the years of turbulence research. Some approaches have been more successful than others, but most only deal with part of the problem. One approach that has seen reasonable success (or at least popularity) is that of attempting to deconstruct the complex and disorganised turbulent flow field into to a set of motions that are in some way organised. These motions are generally called "coherent structures". There are several strands to this approach, from identifying the coherent structures within the flow, defining their characteristics, explaining how they are created, sustained and destroyed, to utilising their features to model the turbulent flow. This review considers research on coherent structures in wall-bounded turbulent flows: a class of flow which is extremely interesting to many scientists (mainly, but not exclusively, physicists and engineers) due to their prevalence in nature, industry and everyday life. This area has seen a lot of activity, particularly in recent years, much of which has been driven by advances in experimental and computational techniques. However, several ideas, developed many years ago based on flow visualisation and intuition, are still both informative and relevant. Indeed, much of the more recent research is firmly indebted to some of the early pioneers of the coherent structures approach. Therefore, in this review, selected historical research is discussed along with the more contemporary advances in an attempt to provide the reader with a good overview of how the field has developed and to highlight the perspicacity of some of the early researchers, as well as providing an overview of our current understanding of the role of coherent structures in wall-bounded turbulent flows.

  16. Coherent structures in wall-bounded turbulence

    Directory of Open Access Journals (Sweden)

    David J.C. Dennis

    2015-06-01

    Full Text Available The inherent difficulty of understanding turbulence has led to researchers attacking the topic in many different ways over the years of turbulence research. Some approaches have been more successful than others, but most only deal with part of the problem. One approach that has seen reasonable success (or at least popularity is that of attempting to deconstruct the complex and disorganised turbulent flow field into to a set of motions that are in some way organised. These motions are generally called "coherent structures". There are several strands to this approach, from identifying the coherent structures within the flow, defining their characteristics, explaining how they are created, sustained and destroyed, to utilising their features to model the turbulent flow. This review considers research on coherent structures in wall-bounded turbulent flows: a class of flow which is extremely interesting to many scientists (mainly, but not exclusively, physicists and engineers due to their prevalence in nature, industry and everyday life. This area has seen a lot of activity, particularly in recent years, much of which has been driven by advances in experimental and computational techniques. However, several ideas, developed many years ago based on flow visualisation and intuition, are still both informative and relevant. Indeed, much of the more recent research is firmly indebted to some of the early pioneers of the coherent structures approach. Therefore, in this review, selected historical research is discussed along with the more contemporary advances in an attempt to provide the reader with a good overview of how the field has developed and to highlight the perspicacity of some of the early researchers, as well as providing an overview of our current understanding of the role of coherent structures in wall-bounded turbulent flows.

  17. Structural Alterations of the Glomerular Wall And Vessels in Early ...

    African Journals Online (AJOL)

    The second group of 20 (the experimental group) was injected intraperitoneally by a single dose of streptozotocin to induce hyperglycemia. Rats were sacrificed after ten days, two months, and four months. Five rats at two months of age with hyperglycemia were treated with insulin for eight weeks. Renal tissues were ...

  18. "Choke" vessels between vascular territories of the abdominal wall: literature review and rare case of Leriche's syndrome.

    Science.gov (United States)

    Ye, Xuan; Rozen, Warren M; Alonso-Burgos, Alberto; Ashton, Mark W

    2012-11-01

    We undertook a review of the anatomical changes of "choke" vessels between the internal thoracic artery (ITA) and deep inferior epigastric artery (DIEA), as highlighted by a case of aortoiliac occlusive disease (Leriche's syndrome), and discuss the physiological concepts observed with regard to surgical delay procedures within the abdominal wall performed prior to abdominal cutaneous free flaps and coronary artery bypass grafting. Computed tomographic angiography (CTA) was undertaken on a patient with a rare case of Leriche's syndrome and a literature review of over 200 references on the anatomy, physiology and clinical uses of choke vessels in the abdominal wall was undertaken. The CTA demonstrated that in patients with Leriche's syndrome, there is a marked dilatation of all ITA-DIEA pathways and increased flow through choke vessels. If these changes can be surgically replicated in the form of a delay procedure for patients seeking to undergo autologous breast construction, this could improve the outcomes of abdominal cutaneous free flaps and coronary artery bypass grafting. We accordingly propose three surgical methods for augmenting blood flow to the abdominal wall: a) ligation of the DIEA; b) ligation of the distal ITA; and c) creation of an arterio-venous fistulae in the DIEA. Our review of the literature confirmed the viability of these propositions. The dilatation of choke vessels in response to increased haemodynamic stress may thus be utilised to enhance blood supply to tissues prior to transfer and can be achieved through simple and minimally invasive methods. Copyright © 2012 Wiley Periodicals, Inc.

  19. Wall grid structure for interior scene synthesis

    KAUST Repository

    Xu, Wenzhuo

    2015-02-01

    We present a system for automatically synthesizing a diverse set of semantically valid, and well-arranged 3D interior scenes for a given empty room shape. Unlike existing work on layout synthesis, that typically knows potentially needed 3D models and optimizes their location through cost functions, our technique performs the retrieval and placement of 3D models by discovering the relationships between the room space and the models\\' categories. This is enabled by a new analytical structure, called Wall Grid Structure, which jointly considers the categories and locations of 3D models. Our technique greatly reduces the amount of user intervention and provides users with suggestions and inspirations. We demonstrate the applicability of our approach on three types of scenarios: conference rooms, living rooms and bedrooms.

  20. Tools to Understand Structural Property Relationships for Wood Cell Walls

    Science.gov (United States)

    Joseph E. Jakes; Daniel J. Yelle; Charles R. Frihart

    2011-01-01

    Understanding structure-property relationships for wood cell walls has been hindered by the complex polymeric structures comprising these cell walls and the difficulty in assessing meaningful mechanical property measurements of individual cell walls. To help overcome these hindrances, we have developed two experimental methods: 1) two-dimensional solution state nuclear...

  1. Geologic Structures in Crater Walls on Vesta

    Science.gov (United States)

    Mittlefehldt, David W.; Beck, A. W.; Ammannito, E.; Carsenty, U.; DeSanctis, M. C.; LeCorre, L.; McCoy, T. J.; Reddy, V.; Schroeder, S. E.

    2012-01-01

    The Framing Camera (FC) on the Dawn spacecraft has imaged most of the illuminated surface of Vesta with a resolution of apporpx. 20 m/pixel through different wavelength filters that allow for identification of lithologic units. The Visible and Infrared Mapping Spectrometer (VIR) has imaged the surface at lower spatial resolution but high spectral resolution from 0.25 to 5 micron that allows for detailed mineralogical interpretation. The FC has imaged geologic structures in the walls of fresh craters and on scarps on the margin of the Rheasilvia basin that consist of cliff-forming, competent units, either as blocks or semi-continuous layers, hundreds of m to km below the rims. Different units have different albedos, FC color ratios and VIR spectral characteristics, and different units can be juxtaposed in individual craters. We will describe different examples of these competent units and present preliminary interpretations of the structures. A common occurrence is of blocks several hundred m in size of high albedo (bright) and low albedo (dark) materials protruding from crater walls. In many examples, dark material deposits lie below coherent bright material blocks. In FC Clementine color ratios, bright material is green indicating deeper 1 m pyroxene absorption band. VIR spectra show these to have deeper and wider 1 and 2 micron pyroxene absorption bands than the average vestan surface. The associated dark material has subdued pyroxene absorption features compared to the average vestan surface. Some dark material deposits are consistent with mixtures of HED materials with carbonaceous chondrites. This would indicate that some dark material deposits in crater walls are megabreccia blocks. The same would hold for bright material blocks found above them. Thus, these are not intact crustal units. Marcia crater is atypical in that the dark material forms a semi-continuous, thin layer immediately below bright material. Bright material occurs as one or more layers. In

  2. Thin-walled reinforcement lattice structure for hollow CMC buckets

    Energy Technology Data Exchange (ETDEWEB)

    de Diego, Peter

    2017-06-27

    A hollow ceramic matrix composite (CMC) turbine bucket with an internal reinforcement lattice structure has improved vibration properties and stiffness. The lattice structure is formed of thin-walled plies made of CMC. The wall structures are arranged and located according to high stress areas within the hollow bucket. After the melt infiltration process, the mandrels melt away, leaving the wall structure to become the internal lattice reinforcement structure of the bucket.

  3. Cell culture for three-dimensional modeling in rotating-wall vessels: an application of simulated microgravity

    Science.gov (United States)

    Schwarz, R. P.; Goodwin, T. J.; Wolf, D. A.

    1992-01-01

    High-density, three-dimensional cell cultures are difficult to grow in vitro. The rotating-wall vessel (RWV) described here has cultured BHK-21 cells to a density of 1.1 X 10(7) cells/ml. Cells on microcarriers were observed to grow with enhanced bridging in this batch culture system. The RWV is a horizontally rotated tissue culture vessel with silicon membrane oxygenation. This design results in a low-turbulence, low-shear cell culture environment with abundant oxygenation. The RWV has the potential to culture a wide variety of normal and neoplastic cells.

  4. Correlation between spin structure oscillations and domain wall velocities

    Science.gov (United States)

    Bisig, André; Stärk, Martin; Mawass, Mohamad-Assaad; Moutafis, Christoforos; Rhensius, Jan; Heidler, Jakoba; Büttner, Felix; Noske, Matthias; Weigand, Markus; Eisebitt, Stefan; Tyliszczak, Tolek; van Waeyenberge, Bartel; Stoll, Hermann; Schütz, Gisela; Kläui, Mathias

    2013-08-01

    Magnetic sensing and logic devices based on the motion of magnetic domain walls rely on the precise and deterministic control of the position and the velocity of individual magnetic domain walls in curved nanowires. Varying domain wall velocities have been predicted to result from intrinsic effects such as oscillating domain wall spin structure transformations and extrinsic pinning due to imperfections. Here we use direct dynamic imaging of the nanoscale spin structure that allows us for the first time to directly check these predictions. We find a new regime of oscillating domain wall motion even below the Walker breakdown correlated with periodic spin structure changes. We show that the extrinsic pinning from imperfections in the nanowire only affects slow domain walls and we identify the magnetostatic energy, which scales with the domain wall velocity, as the energy reservoir for the domain wall to overcome the local pinning potential landscape.

  5. Thermal and structural analysis of a filter vessel ceramic tubesheet

    Energy Technology Data Exchange (ETDEWEB)

    Mallett, R.H. [Mallett Technology, Inc., Research Triangle Park, NC (United States); Swindeman, R.W. [Oak Ridge National Lab., TN (United States); Zievers, J.F. [Industrial Filter & Pump Mfg. Co., Cicero, IL (United States)

    1995-08-01

    A ceramic tubesheet assembly for a hot gas filter vessel is analyzed using the finite element method to determine stresses under differential pressure loading. The stresses include local concentration effects. Selection of the stress measures for evaluation of structural integrity is discussed. Specification of stress limits based upon limited data is considered. Stress results from this ongoing design analysis technology project are shown for one design concept.

  6. Lymphocyte trafficking and HIV infection of human lymphoid tissue in a rotating wall vessel bioreactor

    Science.gov (United States)

    Margolis, L. B.; Fitzgerald, W.; Glushakova, S.; Hatfill, S.; Amichay, N.; Baibakov, B.; Zimmerberg, J.

    1997-01-01

    The pathogenesis of HIV infection involves a complex interplay between both the infected and noninfected cells of human lymphoid tissue, the release of free viral particles, the de novo infection of cells, and the recirculatory trafficking of peripheral blood lymphocytes. To develop an in vitro model for studying these various aspects of HIV pathogenesis we have utilized blocks of surgically excised human tonsils and a rotating wall vessel (RWV) cell culture system. Here we show that (1) fragments of the surgically excised human lymphoid tissue remain viable and retain their gross cytoarchitecture for at least 3 weeks when cultured in the RWV system; (2) such lymphoid tissue gradually shows a loss of both T and B cells to the surrounding growth medium; however, this cellular migration is reversible as demonstrated by repopulation of the tissue by labeled cells from the growth medium; (3) this cellular migration may be partially or completely inhibited by embedding the blocks of lymphoid tissue in either a collagen or agarose gel matrix; these embedded tissue blocks retain most of the basic elements of a normal lymphoid cytoarchitecture; and (4) both embedded and nonembedded RWV-cultured blocks of human lymphoid tissue are capable of productive infection by HIV-1 of at least three various strains of different tropism and phenotype, as shown by an increase in both p24 antigen levels and free virus in the culture medium, and by the demonstration of HIV-1 RNA-positive cells inside the tissue identified by in situ hybridization. It is therefore reasonable to suggest that gel-embedded and nonembedded blocks of human lymphoid tissue, cocultured with a suspension of tonsillar lymphocytes in an RWV culture system, constitute a useful model for simulating normal lymphocyte recirculatory traffic and provide a new tool for testing the various aspects of HIV pathogenesis.

  7. Three-Dimensional Rotating Wall Vessel-Derived Cell Culture Models for Studying Virus-Host Interactions

    Directory of Open Access Journals (Sweden)

    Jameson K. Gardner

    2016-11-01

    Full Text Available The key to better understanding complex virus-host interactions is the utilization of robust three-dimensional (3D human cell cultures that effectively recapitulate native tissue architecture and model the microenvironment. A lack of physiologically-relevant animal models for many viruses has limited the elucidation of factors that influence viral pathogenesis and of complex host immune mechanisms. Conventional monolayer cell cultures may support viral infection, but are unable to form the tissue structures and complex microenvironments that mimic host physiology and, therefore, limiting their translational utility. The rotating wall vessel (RWV bioreactor was designed by the National Aeronautics and Space Administration (NASA to model microgravity and was later found to more accurately reproduce features of human tissue in vivo. Cells grown in RWV bioreactors develop in a low fluid-shear environment, which enables cells to form complex 3D tissue-like aggregates. A wide variety of human tissues (from neuronal to vaginal tissue have been grown in RWV bioreactors and have been shown to support productive viral infection and physiological meaningful host responses. The in vivo-like characteristics and cellular features of the human 3D RWV-derived aggregates make them ideal model systems to effectively recapitulate pathophysiology and host responses necessary to conduct rigorous basic science, preclinical and translational studies.

  8. Suitability of pharmacokinetic models for dynamic contrast-enhanced MRI of abdominal aortic aneurysm vessel wall: a comparison.

    Directory of Open Access Journals (Sweden)

    V Lai Nguyen

    Full Text Available PURPOSE: Increased microvascularization of the abdominal aortic aneurysm (AAA vessel wall has been related to AAA progression and rupture. The aim of this study was to compare the suitability of three pharmacokinetic models to describe AAA vessel wall enhancement using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI. MATERIALS AND METHODS: Patients with AAA underwent DCE-MRI at 1.5 Tesla. The volume transfer constant (K(trans , which reflects microvascular flow, permeability and surface area, was calculated by fitting the blood and aneurysm vessel wall gadolinium concentration curves. The relative fit errors, parameter uncertainties and parameter reproducibilities for the Patlak, Tofts and Extended Tofts model were compared to find the most suitable model. Scan-rescan reproducibility was assessed using the interclass correlation coefficient and coefficient of variation (CV. Further, the relationship between K(trans and AAA size was investigated. RESULTS: DCE-MRI examinations from thirty-nine patients (mean age±SD: 72±6 years; M/F: 35/4 with an mean AAA maximal diameter of 49±6 mm could be included for pharmacokinetic analysis. Relative fit uncertainties for K(trans based on the Patlak model (17% were significantly lower compared to the Tofts (37% and Extended Tofts model (42% (p<0.001. K(trans scan-rescan reproducibility for the Patlak model (ICC = 0.61 and CV = 22% was comparable with the Tofts (ICC = 0.61, CV = 23% and Extended Tofts model (ICC = 0.76, CV = 22%. K(trans was positively correlated with maximal AAA diameter (Spearman's ρ = 0.38, p = 0.02 using the Patlak model. CONCLUSION: Using the presented imaging protocol, the Patlak model is most suited to describe DCE-MRI data of the AAA vessel wall with good K(trans scan-rescan reproducibility.

  9. Computerized flow and vessel wall analyses of coronary arteries for detection of non-calcified plaques in coronary CT angiography

    Science.gov (United States)

    Wei, Jun; Zhou, Chuan; Chan, Heang-Ping; Chughtai, Aamer; Agarwal, Prachi; Hadjiiski, Lubomir; Kazerooni, Ella

    2016-03-01

    The buildup of non-calcified plaques (NCP) that are vulnerable to rupture in coronary arteries is a risk for myocardial infarction. We are developing a computer-aided detection (CADe) system to assist radiologists in detecting NCPs in cCTA. A major challenge of NCP detection is the large number of false positives (FPs) caused by the small sized coronary arteries, image noise and artifacts. In this study, our purpose is to design new image features to reduce FPs. A data set of 98 cCTA scans was retrospectively collected from patient files. We first used vessel wall analysis, in which topological features were extracted from vessel wall and fused with a support-vector machine, to identify the NCP candidates from the segmented coronary tree. Computerized flow dynamic (CFD) features that characterize the change in blood flow due to the presence of plaques and a vascular cross-sectional (VCS) feature that quantifies the presence of low attenuation region at the vessel wall were designed for FP reduction. Using a leave-one-out resampling method, a support vector machine classifier was trained to merge the features into a NCP likelihood score using the vessel wall features alone or in combination with the new CDF and VCS features. The performance of the new features in classification of true NCPs and FPs was evaluated by the area under the receiver operating characteristic (ROC) curve (AUC). Without the new CFD and VCS features, the test AUC was 0.84+/-0.01. The AUC was improved to 0.88+/-0.01 with the addition of the new features. The improvement was statistically significant (p < 0.001). The study indicated that the new flow dynamic and vascular cross-sectional features were useful for differentiation of NCPs from FPs in cCTA.

  10. Carbon nanocones: wall structure and morphology

    Directory of Open Access Journals (Sweden)

    Stine Nalum Naess, Arnljot Elgsaeter, Geir Helgesen and Kenneth D Knudsen

    2009-01-01

    Full Text Available Large-scale production of conical carbon nanostructures is possible through pyrolysis of hydrocarbons in a plasma torch process. The resulting carbon cones occur in five distinctly different forms, and disc-shaped particles are produced as well. The structure and properties of these carbon cones and discs have been relatively little explored until now. Here we characterize the structure of these particles using transmission electron microscopy, synchrotron x-ray and electron diffraction. The carbon nanocones are found to exhibit several interesting structural features; instead of having a uniform cross-section, the walls consist of a relatively thin inner graphite-like layer with a non-crystalline envelope, where the amount of the latter can be modified significantly by annealing. The cones appear with a well-defined faceting along the cone edge, demonstrating strict long-range atomic ordering; they also present occasional examples of symmetry breaking, such as two apexes appearing in the same carbon nanocone.

  11. Design assessment for manufacturability of supporting structures for IWS and ELM coil of ITER vacuum vessel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yu-Gyeong, E-mail: aspirany@hhi.co.kr [Hyundai Heavy Industries Co., Ltd., Dong-gu, Ulsan (Korea, Republic of); Hong, Yun-Seok; Kwon, Tae-Hoon; Jung, Yung-Jin [Hyundai Heavy Industries Co., Ltd., Dong-gu, Ulsan (Korea, Republic of); Ahn, Hee-Jae; Kim, Byung-Chul; Lee, Young-Ju [National Fusion Research Institute, 113 Gwahangno, Yuseong-gu, Daejeon-si 305-333 (Korea, Republic of)

    2013-10-15

    Highlights: ► A “bridge type” welding method was proposed for IWS rib and ELM coil supports. ► This method could reduce the welding distortion and increase the manufacturability. ► Structural integrity of proposed design was assessed for both P and S type damages. ► Results show that the proposed designs meet the design criteria of RCC-MR. -- Abstract: A vacuum vessel is one of the core facilities of ITER (International Thermonuclear Experimental Reactor) and basically all-welded structure. Korea is responsible for the procurement of sector 1 and 6 of the main vessel. Accordingly, the design review for the fabrication is in progress by ITER Korea and Hyundai Heavy Industries. Due to anticipated manufacturing problems such as the welding distortion, the design of some components of main vessel, IWS (In-Wall Shield) supporting rib and ELM (Edge Localized Mode) coil support, needs to be modified. To release the risk of welding distortion, the welding method called “bridge type” is suggested and the shape of weld joint is adjusted to secure the manufacturability of the issued components. The elastic and limit analyses with fatigue evaluation have been performed under the most critical loading condition to verify the structural integrity of modified design. Analysis results show that the proposed designs meet the design criteria of RCC-MR. The design deviation requests have been submitted to ITER Organization and ANB (Agreed Notified Body) for approval and their verification is currently in progress.

  12. Domain wall structure of weak ferromagnets according to Raman

    Energy Technology Data Exchange (ETDEWEB)

    Kuzmenko, A.P., E-mail: apk3527@mail.ru [South-West State University (Russian Federation); Abakumov, P.V. [South-West State University (Russian Federation); Dobromyslov, M.B. [Pacific State University (Russian Federation)

    2012-03-15

    Visualizing the domain structure and the fine structure of domain walls in orthoferrites based on Raman was proposed. The Raman mapping imaging was obtained for the straight and curved domain wall at line 221 cm{sup -1}. The parameters of the domain structure and wall obtained by Raman are consistent with magnetooptical measurements. - Highlights: Black-Right-Pointing-Pointer Visualizing the fine structure of domain walls in YFeO{sub 3} by Raman was proposed. Black-Right-Pointing-Pointer One was obtained for the straight and curved domain wall at line 221 cm{sup -1}. Black-Right-Pointing-Pointer The parameters of the domain structure and wall obtained are in accordance with other measurements.

  13. Vessel Wall Enhancement and Blood-Cerebrospinal Fluid Barrier Disruption After Mechanical Thrombectomy in Acute Ischemic Stroke.

    Science.gov (United States)

    Renú, Arturo; Laredo, Carlos; Lopez-Rueda, Antonio; Llull, Laura; Tudela, Raúl; San-Roman, Luis; Urra, Xabier; Blasco, Jordi; Macho, Juan; Oleaga, Laura; Chamorro, Angel; Amaro, Sergio

    2017-03-01

    Less than half of acute ischemic stroke patients treated with mechanical thrombectomy obtain permanent clinical benefits. Consequently, there is an urgent need to identify mechanisms implicated in the limited efficacy of early reperfusion. We evaluated the predictors and prognostic significance of vessel wall permeability impairment and its association with blood-cerebrospinal fluid barrier (BCSFB) disruption after acute stroke treated with thrombectomy. A prospective cohort of acute stroke patients treated with stent retrievers was analyzed. Vessel wall permeability impairment was identified as gadolinium vessel wall enhancement (GVE) in a 24- to 48-hour follow-up contrast-enhanced magnetic resonance imaging, and severe BCSFB disruption was defined as subarachnoid hemorrhage or gadolinium sulcal enhancement (present across >10 slices). Infarct volume was evaluated in follow-up magnetic resonance imaging, and clinical outcome was evaluated with the modified Rankin Scale at day 90. A total of 60 patients (median National Institutes of Health Stroke Scale score, 18) were analyzed, of whom 28 (47%) received intravenous alteplase before mechanical thrombectomy. Overall, 34 (57%) patients had GVE and 27 (45%) had severe BCSFB disruption. GVE was significantly associated with alteplase use before thrombectomy and with more stent retriever passes, along with the presence of severe BCSFB disruption. GVE was associated with poor clinical outcome, and both GVE and severe BCSFB disruption were associated with increased final infarct volume. These findings may support the clinical relevance of direct vessel damage and BCSFB disruption after acute stroke and reinforce the need for further improvements in reperfusion strategies. Further validation in larger cohorts of patients is warranted. © 2017 American Heart Association, Inc.

  14. Transient Non-Newtonian Blood Flow under Magnetic Targeting Drug Delivery in an Aneurysm Blood Vessel with Porous Walls

    Science.gov (United States)

    Alimohamadi, Haleh; Imani, Mohsen

    2014-11-01

    The present investigation deals with numerical solution of blood flow patterns through an aneurysm artery under the applied magnetic field. Transient extended Navier-Stokes, Brinkman, continuity, and heat conduction equations govern this phenomenon and unsteady pulsatile inlet velocity varies by human heart-beating frequency. Our simulation demonstrates applying 105 magnetic field intensity (MnF) to recirculate flow and increase fluid flux and maximum blood temperature by 62.5x and 3.5%, respectively, in the aneurysm region. It is also shown that the vessel's wall porosity plays an important role in magnetic targeting of drug delivery performance, as this parameter can noticeably change maximum blood temperature and pressure.

  15. Association between proximal internal carotid artery steno-occlusive disease and diffuse wall thickening in its petrous segment: a magnetic resonance vessel wall imaging study

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xiaoyi; Li, Dongye [Capital Medical University and Beijing Institute for Brain Disorders, Center for Brain Disorders Research, Beijing (China); Tsinghua University School of Medicine, Center for Biomedical Imaging Research, Department of Biomedical Engineering, Beijing (China); Zhao, Huilin [Shanghai Jiao Tong University, Department of Radiology, Renji Hospital, School of Medicine, Shanghai (China); Chen, Zhensen; Qiao, Huiyu; He, Le; Li, Rui [Tsinghua University School of Medicine, Center for Biomedical Imaging Research, Department of Biomedical Engineering, Beijing (China); Cui, Yuanyuan [PLA General Hospital, Department of Radiology, Beijing (China); Zhou, Zechen [Philips Research China, Healthcare Department, Beijing (China); Yuan, Chun [Tsinghua University School of Medicine, Center for Biomedical Imaging Research, Department of Biomedical Engineering, Beijing (China); University of Washington, Department of Radiology, Seattle, WA (United States); Zhao, Xihai [Tsinghua University School of Medicine, Center for Biomedical Imaging Research, Department of Biomedical Engineering, Beijing (China); Beijing Institute for Brain Disorders, Center for Stroke, Beijing (China)

    2017-05-15

    Significant stenosis or occlusion in carotid arteries may lead to diffuse wall thickening (DWT) in the arterial wall of downstream. This study aimed to investigate the correlation between proximal internal carotid artery (ICA) steno-occlusive disease and DWT in ipsilateral petrous ICA. Symptomatic patients with atherosclerotic stenosis (>0%) in proximal ICA were recruited and underwent carotid MR vessel wall imaging. The 3D motion sensitized-driven equilibrium prepared rapid gradient-echo (3D-MERGE) was acquired for characterizing the wall thickness and longitudinal extent of the lesions in petrous ICA and the distance from proximal lesion to the petrous ICA. The stenosis degree in proximal ICA was measured on the time-of-flight (TOF) images. In total, 166 carotid arteries from 125 patients (mean age 61.0 ± 10.5 years, 99 males) were eligible for final analysis and 64 showed DWT in petrous ICAs. The prevalence of severe DWT in petrous ICA was 1.4%, 5.3%, 5.9%, and 80.4% in ipsilateral proximal ICAs with stenosis category of 1%-49%, 50%-69%, 70%-99%, and total occlusion, respectively. Proximal ICA stenosis was significantly correlated with the wall thickness in petrous ICA (r = 0.767, P < 0.001). Logistic regression analysis showed that proximal ICA stenosis was independently associated with DWT in ipsilateral petrous ICA (odds ratio (OR) = 2.459, 95% confidence interval (CI) 1.896-3.189, P < 0.001). Proximal ICA steno-occlusive disease is independently associated with DWT in ipsilateral petrous ICA. (orig.)

  16. Structural Studies of Complex Carbohydrates of Plant Cell Walls

    Energy Technology Data Exchange (ETDEWEB)

    Darvill, Alan [Univ. of Georgia, Athens, GA (United States); Hahn, Michael G. [Univ. of Georgia, Athens, GA (United States); O' Neill, Malcolm A. [Univ. of Georgia, Athens, GA (United States); York, William S. [Univ. of Georgia, Athens, GA (United States)

    2015-02-17

    Most of the solar energy captured by land plants is converted into the polysaccharides (cellulose, hemicellulose, and pectin) that are the predominant components of the cell wall. These walls, which account for the bulk of plant biomass, have numerous roles in the growth and development of plants. Moreover, these walls have a major impact on human life as they are a renewable source of biomass, a source of diverse commercially useful polymers, a major component of wood, and a source of nutrition for humans and livestock. Thus, understanding the molecular mechanisms that lead to wall assembly and how cell walls and their component polysaccharides contribute to plant growth and development is essential to improve and extend the productivity and value of plant materials. The proposed research will develop and apply advanced analytical and immunological techniques to study specific changes in the structures and interactions of the hemicellulosic and pectic polysaccharides that occur during differentiation and in response to genetic modification and chemical treatments that affect wall biosynthesis. These new techniques will make it possible to accurately characterize minute amounts of cell wall polysaccharides so that subtle changes in structure that occur in individual cell types can be identified and correlated to the physiological or developmental state of the plant. Successful implementation of this research will reveal fundamental relationships between polysaccharide structure, cell wall architecture, and cell wall functions.

  17. Structural and functional features of central nervous system lymphatic vessels.

    Science.gov (United States)

    Louveau, Antoine; Smirnov, Igor; Keyes, Timothy J; Eccles, Jacob D; Rouhani, Sherin J; Peske, J David; Derecki, Noel C; Castle, David; Mandell, James W; Lee, Kevin S; Harris, Tajie H; Kipnis, Jonathan

    2015-07-16

    One of the characteristics of the central nervous system is the lack of a classical lymphatic drainage system. Although it is now accepted that the central nervous system undergoes constant immune surveillance that takes place within the meningeal compartment, the mechanisms governing the entrance and exit of immune cells from the central nervous system remain poorly understood. In searching for T-cell gateways into and out of the meninges, we discovered functional lymphatic vessels lining the dural sinuses. These structures express all of the molecular hallmarks of lymphatic endothelial cells, are able to carry both fluid and immune cells from the cerebrospinal fluid, and are connected to the deep cervical lymph nodes. The unique location of these vessels may have impeded their discovery to date, thereby contributing to the long-held concept of the absence of lymphatic vasculature in the central nervous system. The discovery of the central nervous system lymphatic system may call for a reassessment of basic assumptions in neuroimmunology and sheds new light on the aetiology of neuroinflammatory and neurodegenerative diseases associated with immune system dysfunction.

  18. An enzymatic approach to cell wall structure

    African Journals Online (AJOL)

    sterilization, was 66%. A cellulase, a-arabinosidase and xylanase were partially purified from the concentrated superna- tant of R. a/bus cultures and a purified polygalacturonase was obtained from the fungus Verticillium. Of the enzymes tested, the most effective in digesting cell walls was the polygalac- turonase.

  19. Endoplasmic reticulum stress inhibition reduces hypertension through the preservation of resistance blood vessel structure and function.

    Science.gov (United States)

    Carlisle, Rachel E; Werner, Kaitlyn E; Yum, Victoria; Lu, Chao; Tat, Victor; Memon, Muzammil; No, Yejin; Ask, Kjetil; Dickhout, Jeffrey G

    2016-08-01

    Our purpose was to determine if endoplasmic reticulum stress inhibition lowers blood pressure (BP) in hypertension by correcting vascular dysfunction. The spontaneously hypertensive rat (SHR) was used as a model of human essential hypertension with its normotensive control, the Wistar Kyoto rat. Animals were subjected to endoplasmic reticulum stress inhibition with 4-phenylbutyric acid (4-PBA; 1 g/kg per day, orally) for 5 weeks from 12 weeks of age. BP was measured weekly noninvasively and at endpoint with carotid arterial cannulation. Small mesenteric arteries were removed for vascular studies. Function was assessed with a Mulvany-Halpern style myograph, and structure was assessed by measurement of medial-to-lumen ratio in perfusion fixed vessels as well as three-dimensional confocal reconstruction of vessel wall components. Endoplasmic reticulum stress was assessed by quantitative real time-PCR and western blotting; oxidative stress was assessed by 3-nitrotyrosine and dihydroethidium staining. 4-PBA significantly lowered BP in SHR (vehicle 206.1 ± 4.3 vs. 4-PBA 178.9 ± 3.1, systolic) but not Wistar Kyoto. 4-PBA diminished contractility and augmented endothelial-dependent vasodilation in SHR small mesenteric arteries, as well as reducing media-to-lumen ratio. 4-PBA significantly reduced endoplasmic reticulum stress in SHR resistance vessels. Normotensive resistance vessels, treated with the endoplasmic reticulum stress-inducing agent, tunicamycin, show decreased endothelial-dependent vasodilation; this was improved with 4-PBA treatment. 3-Nitrotyrosine and dihydroethidium staining indicated that endoplasmic reticulum stress leads to reactive oxygen species generation resolvable by 4-PBA treatment. Endoplasmic reticulum stress caused endothelial-mediated vascular dysfunction contributing to elevated BP in the SHR model of human essential hypertension.

  20. Investigation of Stability Alarming for Retaining Wall Structures with Damage

    Directory of Open Access Journals (Sweden)

    Qian Xu

    2017-01-01

    Full Text Available To warn of the stability of retaining wall structures with damage, a simplified mechanical model and a finite element model of this retaining wall-soil coupling system are established. Via finite element model updating, a baseline finite element model of the wall-soil system is acquired. A damage alarming index ERSD (Energy Ratio Standard Deviation is proposed via the wavelet packet analysis of a virtual impulse response function of dynamic responses to this baseline finite element model. The internal relationships among the alarming index, earth pressure, and damage stability of the wall are analyzed. Then, a damage stability alarming method for the retaining walls is advanced. To verify the feasibility and validity of this alarming method, vibration tests on the baseline finite element model of a pile plate retaining wall are performed. The ERSD is used as an alarm for the damage stability of the wall. Analysis results show that, with an increase in the ERSD, the stability of the wall changes from a stable state to an unstable one. The wall reaches a critical stable state when the alarming index reaches its threshold value. Thus, the damage stability of this pile plate retaining wall can be alarmed via ERSD.

  1. Optical coherence tomography assessment of vessel wall degradation in thoracic aortic aneurysms

    Science.gov (United States)

    Real, Eusebio; Eguizabal, Alma; Pontón, Alejandro; Díez, Marta Calvo; Fernando Val-Bernal, José; Mayorga, Marta; Revuelta, José M.; López-Higuera, José M.; Conde, Olga M.

    2013-12-01

    Optical coherence tomography images of human thoracic aorta from aneurysms reveal elastin disorders and smooth muscle cell alterations when visualizing the media layer of the aortic wall. These disorders can be employed as indicators for wall degradation and, therefore, become a hallmark for diagnosis of risk of aneurysm under intraoperative conditions. Two approaches are followed to evaluate this risk: the analysis of the reflectivity decay along the penetration depth and the textural analysis of a two-dimensional spatial distribution of the aortic wall backscattering. Both techniques require preprocessing stages for the identification of the air-sample interface and for the segmentation of the media layer. Results show that the alterations in the media layer of the aortic wall are better highlighted when the textural approach is considered and also agree with a semiquantitative histopathological grading that assesses the degree of wall degradation. The correlation of the co-occurrence matrix attains a sensitivity of 0.906 and specificity of 0.864 when aneurysm automatic diagnosis is evaluated with a receiver operating characteristic curve.

  2. Vascular wall-resident CD44+ multipotent stem cells give rise to pericytes and smooth muscle cells and contribute to new vessel maturation.

    Directory of Open Access Journals (Sweden)

    Diana Klein

    Full Text Available Here, we identify CD44(+CD90(+CD73(+CD34(-CD45(- cells within the adult human arterial adventitia with properties of multipotency which were named vascular wall-resident multipotent stem cells (VW-MPSCs. VW-MPSCs exhibit typical mesenchymal stem cell characteristics including cell surface markers in immunostaining and flow cytometric analyses, and differentiation into adipocytes, chondrocytes and osteocytes under culture conditions. Particularly, TGFß1 stimulation up-regulates smooth muscle cell markers in VW-MPSCs. Using fluorescent cell labelling and co-localisation studies we show that VW-MPSCs differentiate to pericytes/smooth muscle cells which cover the wall of newly formed endothelial capillary-like structures in vitro. Co-implantation of EGFP-labelled VW-MPSCs and human umbilical vein endothelial cells into SCID mice subcutaneously via Matrigel results in new vessels formation which were covered by pericyte- or smooth muscle-like cells generated from implanted VW-MPSCs. Our results suggest that VW-MPSCs are of relevance for vascular morphogenesis, repair and self-renewal of vascular wall cells and for local capacity of neovascularization in disease processes.

  3. Distribution and natural course of intracranial vessel wall lesions in patients with ischemic stroke or TIA at 7.0 tesla MRI

    Energy Technology Data Exchange (ETDEWEB)

    Kolk, Anja G. van der; Luijten, Peter R.; Hendrikse, Jeroen [University Medical Center Utrecht, Department of Radiology, Postbox 85500, Utrecht (Netherlands); Zwanenburg, Jaco J.M. [University Medical Center Utrecht, Department of Radiology, Postbox 85500, Utrecht (Netherlands); University Medical Center Utrecht, Image Sciences Institute, Utrecht (Netherlands); Brundel, Manon; Biessels, Geert Jan [University Medical Center Utrecht, Department of Neurology, Utrecht (Netherlands); Visser, Fredy [University Medical Center Utrecht, Department of Radiology, Postbox 85500, Utrecht (Netherlands); Philips Healthcare, Best (Netherlands)

    2015-06-01

    Previous studies using intracranial vessel wall MRI techniques showed that over 50 % of patients with ischemic stroke or TIA had one or more intracranial vessel wall lesions. In the current study, we assessed the preferential location of these lesions within the intracranial arterial tree and their potential changes over time in these patient groups. Forty-nine patients with ischemic stroke (n = 25) or TIA (n = 24) of the anterior cerebral circulation underwent 7.0 T MRI, including a T{sub 1}-weighted magnetization-preparation inversion recovery turbo-spin-echo (MPIR-TSE) sequence within one week and approximately one month after symptom onset. Intracranial vessel wall lesions were scored for multiple locations within the arterial tree and differences between one-week and one-month images. At baseline, 132 intracranial vessel wall lesions were found in 41 patients (84 %), located primarily in the anterior cerebral circulation (74 %), with a preferential location in the distal internal carotid artery and M1 and M2 segments of the middle cerebral artery. During follow-up, presence or enhancement patterns changed in 14 lesions (17 %). A large burden of intracranial vessel wall lesions was found in both the anterior and posterior cerebral circulation. Most lesions were found to be relatively stable, possibly indicating a more generalized atherosclerotic process. (orig.)

  4. Role of tissue structure on ventricular wall mechanics.

    Science.gov (United States)

    Coppola, Benjamin A; Omens, Jeffrey H

    2008-09-01

    It is well known that systolic wall thickening in the inner half of the left ventricular (LV) wall is of greater magnitude than predicted by myofiber contraction alone. Previous studies have related the deformation of the LV wall to the orientation of the laminar architecture. Using this method, wall thickening can be interpreted as the sum of contributions due to extension, thickening, and shearing of the laminar sheets. We hypothesized that the thickening mechanics of the ventricular wall are determined by the structural organization of the underlying tissue, and may not be influenced by factors such as loading and activation sequence. To test this hypothesis, we calculated finite strains from biplane cineradiography of transmural markers implanted in apical (n = 22) and basal (n = 12) regions of the canine anterior LV free wall. Strains were referred to three-dimensional laminar microstructural axes measured by histology. The results indicate that sheet angle is of opposite sign in the apical and basal regions, but absolute value differs only in the subepicardium. During systole, shearing and extension of the laminae contribute the most to wall thickening, accounting for >90% (transmural average) at both apex and base. These two types of deformation are also most prominent during diastolic inflation. Increasing afterload has no effect on the pattern of systolic wall thickening, nor does reversing transmural activation sequence. The pattern of wall thickening appears to be a function of the orientation of the laminar sheets, which vary regionally and transmurally. Thus, acute interventions do not appear to alter the contributions of the laminae to wall thickening, providing further evidence that the structural architecture of the ventricular wall is the dominant factor for its regional mechanical function.

  5. Mapping hidden wall structures by quantitative IR thermography

    Science.gov (United States)

    Rosina, Elisabetta; Grinzato, Ermanno G.; Robison, Elwin C.

    2002-03-01

    Knowledge of an historic monument can be substantially improved by locating hidden structures, openings and the wall bonding beneath the plaster. When restoring buildings, the physical connection between the walls must be known in order to predict the risk areas for structural weakness. IR Thermography produces remarkable results, especially by means of the quantitative approach. The temperature pattern detected by thermography and analyzed in space and time maps the hidden structure of the wall. Thick walls exposed to the weather represent a challenge in detecting hidden structures by means of thermography. Frequently output is very poor because testing conditions are not optimized. Hence, appropriate testing requires careful analysis of the wall system before and after taking the thermograms. Otherwise, false alarms render the images useless. This paper describes a general procedure applied to see the hidden wall structure. It works in three steps: a) a mathematical simulation of the real test by a dedicated software, implementing the 3D thermal problem; b) a transient thermographic test, delivering a suitable heating flux on the surface for the proper time; c) processing test data, including a thermogram sequence and air temperature analysis. Here, are reported tests achieved on a XV-XVIIth century Palace at Cremona (Italy; in the Westcott House in Springfield (OH).

  6. Characterization of atherosclerotic disease in thoracic aorta: A 3D, multicontrast vessel wall imaging study

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Changwu [Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University School of Medicine, Beijing (China); Department of Radiology, The Second Clinical Medical College, Yangzhou University, Yangzhou (China); Qiao, Huiyu; He, Le [Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University School of Medicine, Beijing (China); Yuan, Chun [Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University School of Medicine, Beijing (China); Department of Radiology, University of Washington, Seattle, WA (United States); Chen, Huijun; Zhang, Qiang; Li, Rui [Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University School of Medicine, Beijing (China); Wang, Wei; Du, Fang [Department of Radiology, The Second Clinical Medical College, Yangzhou University, Yangzhou (China); Li, Cheng, E-mail: cjr.licheng@vip.163.com [Department of Radiology, Zhongda Hospital, Medical School of Southeast University, Nanjing (China); Zhao, Xihai, E-mail: xihaizhao@tsinghua.edu.cn [Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University School of Medicine, Beijing (China)

    2016-11-15

    Purpose: To investigate the characteristics of plaque in the thoracic aorta using three dimensional multicontrast magnetic resonance imaging. Materials and methods: Elderly subjects (≥60 years) were recruited in this study. Thoracic aorta was imaged on a 3.0T MR scanner by acquiring multicontrast sequences. The plaque burden was evaluated by measuring lumen area, wall area, wall thickness, and normalized wall index. The presence or absence of plaque and intraplaque hemorrhage (IPH)/mural thrombus (MT) were identified. The characteristics of atherosclerosis among different thoracic aorta segments (AAO: ascending aorta; AOA: aortic arch, and DOA: descending aorta) were determined. Results: Of 66 recruited subjects (mean age 72.3 ± 6.2 years, 30 males), 55 (83.3%) had plaques in the thoracic aorta. The prevalence of plaque in AAO, AOA, and DAO was 5.4%, 72.7%, and 71.2%, respectively. In addition, 21.2% of subjects were found to have lesions with IPH/MT in the thoracic aorta. The prevalence of IPH/MT in segment of AAO, AOA and DAO was 0%, 13.6%, and 12.1%, respectively. The aortic wall showed the highest NWI in DAO (34.1% ± 4.8%), followed by AOA (31.2% ± 5%), and AAO (26.8% ± 3.3%) (p < 0.001). Conclusion: Three dimensional multicontrast MR imaging is capable of characterizing atherosclerotic plaques in the thoracic aorta. The findings of high prevalence of plaques and the presence of high risk plaques in the thoracic aorta suggest early screening for aortic vulnerable lesions in the elderly.

  7. Accelerated whole brain intracranial vessel wall imaging using black blood fast spin echo with compressed sensing (CS-SPACE).

    Science.gov (United States)

    Zhu, Chengcheng; Tian, Bing; Chen, Luguang; Eisenmenger, Laura; Raithel, Esther; Forman, Christoph; Ahn, Sinyeob; Laub, Gerhard; Liu, Qi; Lu, Jianping; Liu, Jing; Hess, Christopher; Saloner, David

    2017-12-05

    Develop and optimize an accelerated, high-resolution (0.5 mm isotropic) 3D black blood MRI technique to reduce scan time for whole-brain intracranial vessel wall imaging. A 3D accelerated T 1 -weighted fast-spin-echo prototype sequence using compressed sensing (CS-SPACE) was developed at 3T. Both the acquisition [echo train length (ETL), under-sampling factor] and reconstruction parameters (regularization parameter, number of iterations) were first optimized in 5 healthy volunteers. Ten patients with a variety of intracranial vascular disease presentations (aneurysm, atherosclerosis, dissection, vasculitis) were imaged with SPACE and optimized CS-SPACE, pre and post Gd contrast. Lumen/wall area, wall-to-lumen contrast ratio (CR), enhancement ratio (ER), sharpness, and qualitative scores (1-4) by two radiologists were recorded. The optimized CS-SPACE protocol has ETL 60, 20% k-space under-sampling, 0.002 regularization factor with 20 iterations. In patient studies, CS-SPACE and conventional SPACE had comparable image scores both pre- (3.35 ± 0.85 vs. 3.54 ± 0.65, p = 0.13) and post-contrast (3.72 ± 0.58 vs. 3.53 ± 0.57, p = 0.15), but the CS-SPACE acquisition was 37% faster (6:48 vs. 10:50). CS-SPACE agreed with SPACE for lumen/wall area, ER measurements and sharpness, but marginally reduced the CR. In the evaluation of intracranial vascular disease, CS-SPACE provides a substantial reduction in scan time compared to conventional T 1 -weighted SPACE while maintaining good image quality.

  8. Optical Sensing using Fiber Bragg Gratings for Monitoring Structural Damage in Composite Over-Wrapped Vessels

    Science.gov (United States)

    Grant, Joseph

    2005-01-01

    Composite Over-Wrap Vessels are widely used in the aerospace community. They are made of thin-walled bottles that are over wrapped with high strength fibers embedded in a matrix material. There is a strong drive to reduce the weight of space borne vehicles and thus pushes designers to adopt COPVs that are over wrapped with graphite fibers embedded in its epoxy matrix. Unfortunately, this same fiber-matrix configuration is more susceptible to impact damage than others and to make matters worse; there is a regime where impacts that damage the over wrap leave no visible scar on the COPV surface. In this paper FBG sensors are presented as a means of monitoring and detecting these types of damage. The FBG sensors are surface mounted to the COPVs and optically interrogated to explore the structural properties of these composite pressure vessels. These gratings optically inscribed into the core of a single mode fiber are used as a tool to monitor the stress strain relation in the composite matrix. The response of these fiber-optic sensors is investigated by pressurizing the cylinder up to its burst pressure of around 4500 psi. A Fiber Optic Demodulation System built by Blue Road Research, is used for interrogation of the Bragg gratings.

  9. Thick-walled carbon composite multifunctional structures

    Science.gov (United States)

    Haake, John M.; Jacobs, Jack H.; McIlroy, Bruce E.

    1997-06-01

    Satellite programs are moving in the direction of smaller and lighter structures. Technological advances have permitted more sophisticated equipment to be consolidated into compact spaces. Micro-satellites, between 10 and 100 kg, will incorporate micro-electric devices into the lay-up of the satellite structure. These structures will be designed to carry load, provide thermal control, enhance damping, and include integrated passive electronics. These multifunctional structures offer lighter weight, reduced volume, and a 'smarter' overall package for incorporation of sensors, electronics, fiber optics, powered appendages or active components. McDonnell Douglas Corporation (MDC) has applied technology from the synthesis and processing of intelligent cost effective structures (SPICES) and independent research and development (IRAD) programs to the modular instrument support system (MISS) for multifunctional space structures and micro-satellites. The SPICES program was funded by the Defense Advanced Research Projects Agency (DARPA) to develop affordable manufacturing processes for smart materials to be used in vibration control, and the MISS program was funded by NASA-Langley. The MISS program was conceived to develop concepts and techniques to make connections between different multifunctional structures. MDA fabricated a trapezoidal carbon composite structure out of IM7/977-3 tape prepreg. Flex circuits, thermal and optical conduits were embedded to realize a utility modular connector. These provide electrical, thermal, optical and mechanical connections between micro- satellite components. A quick disconnect mount was also developed to accommodate a variety of devices such as solar arrays, power sources, thermal transfer and vibration control modules.

  10. Statistical Permutation-based Artery Mapping (SPAM): a novel approach to evaluate imaging signals in the vessel wall.

    Science.gov (United States)

    Seifert, Robert; Scherzinger, Aaron; Kiefer, Friedemann; Hermann, Sven; Jiang, Xiaoyi; Schäfers, Michael A

    2017-05-26

    Cardiovascular diseases are the leading cause of death worldwide. A prominent cause of cardiovascular events is atherosclerosis, a chronic inflammation of the arterial wall that leads to the formation of so called atherosclerotic plaques. There is a strong clinical need to develop new, non-invasive vascular imaging techniques in order to identify high-risk plaques, which might escape detection using conventional methods based on the assessment of the luminal narrowing. In this context, molecular imaging strategies based on fluorescent tracers and fluorescence reflectance imaging (FRI) seem well suited to assess molecular and cellular activity. However, such an analysis demands a precise and standardized analysis method, which is orientated on reproducible anatomical landmarks, ensuring to compare equivalent regions across different subjects. We propose a novel method, Statistical Permutation-based Artery Mapping (SPAM). Our approach is especially useful for the understanding of complex and heterogeneous regional processes during the course of atherosclerosis. Our method involves three steps, which are (I) standardisation with an additional intensity normalization, (II) permutation testing, and (III) cluster-enhancement. Although permutation testing and cluster enhancement are already well-established in functional magnetic resonance imaging, to the best of our knowledge these strategies have so far not been applied in cardiovascular molecular imaging. We tested our method using FRI images of murine aortic vessels in order to find recurring patterns in atherosclerotic plaques across multiple subjects. We demonstrate that our pixel-wise and cluster-enhanced testing approach is feasible and useful to analyse tracer distributions in FRI data sets of aortic vessels. We expect our method to be a useful tool within the field of molecular imaging of atherosclerotic plaques since cluster-enhanced permutation testing is a powerful approach for finding significant differences

  11. Structural analysis of cell wall polysaccharides using PACE

    Energy Technology Data Exchange (ETDEWEB)

    Mortimer, Jennifer C. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Joint BioEnergy Institute

    2017-01-01

    The plant cell wall is composed of many complex polysaccharides. The composition and structure of the polysaccharides affect various cell properties including cell shape, cell function and cell adhesion. Many techniques to characterize polysaccharide structure are complicated, requiring expensive equipment and specialized operators e.g. NMR, MALDI-MS. PACE (Polysaccharide Analysis using Carbohydrate gel Electrophoresis) uses a simple, rapid technique to analyze polysaccharide quantity and structure (Goubet et al. 2002). Whilst the method here describes xylan analysis, it can be applied (by use of the appropriate glycosyl hydrolase) to any cell wall polysaccharide.

  12. {sup 18}F-fluoroethylcholine uptake in arterial vessel walls and cardiovascular risk factors. Correlation in a PET-CT study

    Energy Technology Data Exchange (ETDEWEB)

    Foerster, Stefan; Rominger, A.; Cumming, P.; Bartenstein, P.; Hacker, M. [Technische Univ. Muenchen (TUM) (Germany). Dept. of Nuclear Medicine; Saam, T.; Nikolaou, K.; Reiser, M.F. [Univ. Muenchen (Germany). Inst. of Clinical Radiology; Wolpers, S. [Technische Univ. Muenchen (TUM) (Germany). Dept. of Nuclear Medicine; Univ. Muenchen (Germany). Inst. of Clinical Radiology

    2010-07-01

    Fluorine-labelled choline derivatives were recently suggested as agents for visualizing vulnerable atherosclerotic plaques. We therefore aimed to evaluate the association between {sup 18}F-fluorethylcholine (FEC) uptake in the wall of large arteries, where calcification was also measured, with the presence of cardiovascular risk factors and occurrence of prior cardiovascular events. Detailed clinical information, including common cardiovascular risk factors, was obtained retrospectively in 60 prostate cancer patients examined with whole-body FEC PET-CT. In each patient, we calculated the mean blood pool-corrected SUV, as well as the mean target-to-background ratio (TBR), in addition to the sum of calcified plaques (CP{sub sum}) from six major vessels: ascending and descending aorta, aortic arch, abdominal aorta, and both iliac arteries. As reported previously, the CP{sub sum} correlated significantly with cardiovascular risk factors, in contrast to mean SUV or TBR scores, which did not show any significance with the presence of cardiovascular risk factors. There was no correlation between CP{sub sum}, mean TBR or SUV, nor was there any significant association of CP{sub sum}, mean TBR or SUV with the prior occurrence of cardio- or cerebrovascular events. Contrary to a recent report, we found in our rather large cohort of elderly prostate cancer patients no significant association between FEC uptake in large vessels and atherosclerotic plaque burden, or the presence of cardiovascular risk factors. In line with prior reports on structural changes in vessels, increased calcified atherosclerotic plaque burden was strongly associated with the occurrence of common cardiovascular risk factors. (orig.)

  13. Rôle of contrast media viscosity in altering vessel wall shear stress and relation to the risk of contrast extravasations.

    Science.gov (United States)

    Sakellariou, Sophia; Li, Wenguang; Paul, Manosh C; Roditi, Giles

    2016-12-01

    Iodinated contrast media (CM) are the most commonly used injectables in radiology today. A range of different media are commercially available, combining various physical and chemical characteristics (ionic state, osmolality, viscosity) and thus exhibiting distinct in vivo behaviour and safety profiles. In this paper, numerical simulations of blood flow with contrast media were conducted to investigate the effects of contrast viscosity on generated vessel wall shear stress and vessel wall pressure to elucidate any possible relation to extravasations. Five different types of contrast for Iodine fluxes ranging at 1.5-2.2gI/s were modelled through 18G and 20G cannulae placed in an ideal vein at two different orientation angles. Results demonstrate that the least viscous contrast media generate the least maximum wall shear stress as well as the lowest total pressure for the same flow rate. This supports the empirical clinical observations and hypothesis that more viscous contrast media are responsible for a higher percentage of contrast extravasations. In addition, results support the clinical hypothesis that a catheter tip directed obliquely to the vein wall always produces the highest maximum wall shear stress and total pressure due to impingement of the contrast jet on the vessel wall. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

  14. Changes in Water Filtration Velocity and Wall Structure of the Rabbit Common Carotid Artery after Removal of the Adventitia

    Science.gov (United States)

    Wada, Shigeo; Kaichi, Masashi; Karino, Takeshi

    To investigate the effect of the changes in water filtration velocity on the structure of an arterial wall, measurements of water filtration velocity and microscopic observation of histological specimens of the rabbit common carotid arteries were carried out by surgically removing the adventitia of the arteries and harvesting them at different times postoperatively. It was found that by removal of the adventitia, water filtration velocity at the arterial wall increased temporarily, and then as healing of the adventitia progressed, it decreased gradually until water filtration velocity attained almost the same value as that obtained with intact arteries. Intimal thickening was observed in those vessels harvested at 7 and 14 days postoperatively. Furthermore, it was shown by theoretical calculations that the concentration of low-density lipoprotein, which is a main carrier of cholesterol in blood, was locally elevated at the luminal surface of the segment where water filtration velocity was increased by removal of the adventitia. These results indicate that the change in water filtration velocity at the vessel wall brings about certain changes in the structure of the vessel wall.

  15. Protein-Bound Uremic Toxins Stimulate Crosstalk between Leukocytes and Vessel Wall

    Science.gov (United States)

    Glorieux, Griet; Schepers, Eva; Cohen, Gerald; Gondouin, Bertrand; Van Landschoot, Maria; Eloot, Sunny; Rops, Angelique; Van de Voorde, Johan; De Vriese, An; van der Vlag, Johan; Brunet, Philippe; Van Biesen, Wim; Vanholder, Raymond

    2013-01-01

    Leukocyte activation and endothelial damage both contribute to cardiovascular disease, a major cause of morbidity and mortality in CKD. Experimental in vitro data link several protein-bound uremic retention solutes to the modulation of inflammatory stimuli, including endothelium and leukocyte responses and cardiovascular damage, corroborating observational in vivo data. However, the impact of these uremic toxins on the crosstalk between endothelium and leukocytes has not been assessed. This study evaluated the effects of acute and continuous exposure to uremic levels of indoxylsulfate (IS), p-cresylsulfate (pCS), and p-cresylglucuronide (pCG) on the recruitment of circulating leukocytes in the rat peritoneal vascular bed using intravital microscopy. Superfusion with IS induced strong leukocyte adhesion, enhanced extravasation, and interrupted blood flow, whereas pCS caused a rapid increase in leukocyte rolling. Superfusion with pCS and pCG combined caused impaired blood flow and vascular leakage but did not further enhance leukocyte rolling over pCS alone. Intravenous infusion with IS confirmed the superfusion results and caused shedding of heparan sulfate, pointing to disruption of the glycocalyx as the mechanism likely mediating IS-induced flow stagnation. These results provide the first clear in vivo evidence that IS, pCS, and pCG exert proinflammatory effects that contribute to vascular damage by stimulating crosstalk between leukocytes and vessels. PMID:24009240

  16. Soft impact testing of a wall-floor-wall reinforced concrete structure

    Energy Technology Data Exchange (ETDEWEB)

    Vepsä, Ari, E-mail: ari.vepsa@vtt.fi; Calonius, Kim; Saarenheimo, Arja; Aatola, Seppo; Halonen, Matti

    2017-01-15

    Highlights: • A wall-floor-wall reinforced concrete structure was built. • The structure was subjected to three almost identical soft impact tests. • Response was measured with accelerometers, displacement sensors and strain gauges. • Modal tests was also carried out with the same structure in different conditions. • The results are meant to be used for validation of computational methods and models. - Abstract: Assessing the safety of the reactor building of a nuclear power plant against the crash of an airplane calls for valid computational tools such as finite element models and material constitutive models. Validation of such tools and models in turn calls for reliable and relevant experimental data. The problem is that such data is scarcely available. One of the aspects of such a crash is vibrations that are generated by the impact. These vibrations tend to propagate from the impact point to the internal parts of the building. If strong enough, these vibrations may cause malfunction of the safety-critical equipment inside the building. To enable validation of computational models for this type of behaviour, we have conducted a series of three tests with a wall-floor-wall reinforced concrete structure under soft impact loading. The response of the structure was measured with accelerometers, displacement sensors and strain gauges. In addition to impact tests, the structure was subjected to modal tests under different conditions. The tests yielded a wealth of useful data for validation of computational models and better understanding about shock induced vibration physics especially in reinforced concrete structures.

  17. Structural pounding of concrete frame structure with masonry infill wall under seismic loading

    Science.gov (United States)

    Ismail, Rozaina; Hasnan, Mohd Hafizudin; Shamsudin, Nurhanis

    2017-10-01

    Structural pounding is additional problem than the other harmful damage that may occurs due to the earthquake vibrations. A lot of study has been made by past researcher but most of them did not include the walls. The infill masonry walls are rarely involved analysis of structural systems but it does contribute to earthquake response of the structures. In this research, a comparison between adjacent building of 10-storey and 7-storey concrete frame structure without of masonry infill walls and the same dynamic properties of buildings. The diagonal strut approach is adopted for modeling masonry infill walls. This research also focused on finding critical building separation in order to prevent the adjacent structures from pounding. LUSAS FEA v14.03 software has been used for modeling analyzing the behavior of structures due to seismic loading and the displacement each floor of the building has been taken in order to determine the critical separation distance between the buildings. From the analysis that has been done, it is found that masonry infill walls do affect the structures behavior under seismic load. Structures without masonry infill walls needs more distance between the structures to prevent structural pounding due to higher displacement of the buildings when it sways under seismic load compared to structures with masonry infill walls. This shows that contribution of masonry infill walls to the analysis of structures cannot be neglected.

  18. Detection of vessel wall calcifications in vertebral arteries using susceptibility weighted imaging

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Lisa C.; Boeker, Sarah M.; Bender, Yvonne Y.; Fallenberg, Eva M.; Wagner, Moritz; Hamm, Bernd; Makowski, Marcus R. [Department of Radiology, Charite, Berlin (Germany); Liebig, Thomas [Department of Neuroradiology, Charite, Berlin (Germany)

    2017-09-15

    Calcification of the brain supplying arteries has been linked to an increased risk for cerebrovascular disease. The purpose of this study was to test the potential of susceptibility weighted MR imaging (SWMR) for the detection of vertebral artery calcifications, based on CT as a reference standard. Four hundred seventy-four patients, who had received head CT and 1.5 T MR scans with SWMR, including the distal vertebral artery, between January 2014 and December 2016, were retrospectively evaluated and 389 patients were included. Sensitivity and specificity for the detection of focal calcifications and intra- and interobserver agreement were calculated for SWMR and standard MRI, using CT as a standard of reference. The diameter of vertebral artery calcifications was used to assess correlations between imaging modalities. Furthermore, the degree of vessel stenosis was determined in 30 patients, who had received an additional angiography. On CT scans, 40 patients showed a total of 52 vertebral artery calcifications. While SWMR reached a sensitivity of 94% (95% CI 84-99%) and a specificity of 97% (95% CI 94-98%), standard MRI yielded a sensitivity of 33% (95% CI 20-46%), and a specificity of 93% (95% CI 90-96%). Linear regression analysis of size measurements confirmed a close correlation between SWMR and CT measurements (R {sup 2} = 0.74, p < 0.001). Compared to standard MRI (ICC = 0.52; CI 0.45-0.59), SWMR showed a higher interobserver agreement for calcification measurements (ICC = 0.84; CI 0.81-0.87). For detection of distal vertebral artery calcifications, SWMR demonstrates a performance comparable to CT and considerably higher than conventional MRI. (orig.)

  19. Structural network connectivity and cognition in cerebral small vessel disease

    NARCIS (Netherlands)

    Tuladhar, A.M.; Dijk, E.; Zwiers, M.P.; van Norden, A.G.W.; de Laat, K.F.; Shumskaya, E.; Norris, David Gordon; de Leeuw, F.E.

    2016-01-01

    Cerebral small vessel disease (SVD), including white matter hyperintensities (WMH), lacunes and microbleeds, and brain atrophy, are related to cognitive impairment. However, these magnetic resonance imaging (MRI) markers for SVD do not account for all the clinical variances observed in subjects with

  20. A Structure for a Wide Band Wall Current Monitor

    CERN Document Server

    Kroyer, T

    2006-01-01

    In the framework of the EuroTeV programme a new wall current monitor for application in linear accelerators is currently being developed. A bandwidth of 20 GHz is aimed for in the new design. This note proposes an improved structure with very high bandwidth.

  1. Method for remodeling cell wall polysaccharide structures in plant

    NARCIS (Netherlands)

    Ulvskov, P.; Schols, H.A.; Visser, R.; Borkhardt, B.; Sorensen, S.O.; Oomen, R.; Vincken, J.P.

    2001-01-01

    Methods for providing transgenic plants and parts hereof that, relative to the wild type state, is modified in a complex cell wall polysaccharide structure including pectins and hemicelluloses, the modification being in the overall glycosidic linkage pattern or the monosaccharide profile, comprising

  2. Anatomical changes in the cell-wall structure of Leucaena ...

    African Journals Online (AJOL)

    The structural changes in the cell wall and delignification pattern caused by Trametes versicolor and Trametes hirsuta in the sap wood of Leucaena leucocephala were examined by light and confocal laser scanning microscopy. The in vitro decay test was conducted for 12 weeks. Both species of Trametes used in this study ...

  3. Impact of structural design criteria on first wall surface heat flux limit

    Energy Technology Data Exchange (ETDEWEB)

    Majumdar, S. [Argonne National Lab., IL (United States)

    1998-09-01

    The irradiation environment experienced by the in-vessel components of fusion reactors presents structural design challenges not envisioned in the development of existing structural design criteria such as the ASME Code or RCC-MR. From the standpoint of design criteria, the most significant issues stem from the irradiation-induced changes in material properties, specifically the reduction of ductility, strain hardening capability, and fracture toughness with neutron irradiation. Recently, Draft 7 of the ITER structural design criteria (ISDC), which provide new rules for guarding against such problems, was released for trial use by the ITER designers. The new rules, which were derived from a simple model based on the concept of elastic follow up factor, provide primary and secondary stress limits as functions of uniform elongation and ductility. The implication of these rules on the allowable surface heat flux on typical first walls made of type 316 stainless steel and vanadium alloys are discussed.

  4. The stability of gabion walls for earth retaining structures

    Directory of Open Access Journals (Sweden)

    Mahyuddin Ramli

    2013-12-01

    Full Text Available The stability of earth retaining structures in flood prone areas has become a serious problem in many countries. The two most basic causes of failure arising from flooding are scouring and erosion of the foundation of the superstructure. Hence, a number of structures like bridges employ scour-arresting devices, e.g., gabions to acting on the piers and abutments during flooding. Research was therefore undertaken to improve gabion resistance against lateral movement by means of an interlocking configuration instead of the conventional stack-and-pair system. This involved simulating lateral thrusts against two dimensionally identical retaining wall systems configured according to the rectangular and hexagonal gabion type. The evolution of deformation observed suggested that the interlocking design exhibits better structural integrity than the conventional box gabion-based wall in resisting lateral movement and therefore warrants consideration for use as an appropriate scour-arresting device for earth retaining structures.

  5. Degree of coupling in high-rise mixed shear walls structures

    Indian Academy of Sciences (India)

    assessment of the structural behaviour of coupled shear wall bents in mixed shear wall structures that are subject to horizontal loading. Keywords. Coupled shear walls; degree of coupling; peak shear demand; concrete. 1. Introduction. In reinforced concrete tall buildings, coupled wall structures as shown in figure 1 can ...

  6. Accelerated and Improved Differentiation of Retinal Organoids from Pluripotent Stem Cells in Rotating-Wall Vessel Bioreactors

    Directory of Open Access Journals (Sweden)

    Tyler DiStefano

    2018-01-01

    Full Text Available Pluripotent stem cells can be differentiated into 3D retinal organoids, with major cell types self-patterning into a polarized, laminated architecture. In static cultures, organoid development may be hindered by limitations in diffusion of oxygen and nutrients. Herein, we report a bioprocess using rotating-wall vessel (RWV bioreactors to culture retinal organoids derived from mouse pluripotent stem cells. Organoids in RWV demonstrate enhanced proliferation, with well-defined morphology and improved differentiation of neurons including ganglion cells and S-cone photoreceptors. Furthermore, RWV organoids at day 25 (D25 reveal similar maturation and transcriptome profile as those at D32 in static culture, closely recapitulating spatiotemporal development of postnatal day 6 mouse retina in vivo. Interestingly, however, retinal organoids do not differentiate further under any in vitro condition tested here, suggesting additional requirements for functional maturation. Our studies demonstrate that bioreactors can accelerate and improve organoid growth and differentiation for modeling retinal disease and evaluation of therapies.

  7. Neutron fluence at the reactor pressure vessel wall - a comparison of French and German procedures and strategies in PWRs

    Energy Technology Data Exchange (ETDEWEB)

    Tricot, N. [Institut de Radioprotection et de Surete Nucleaire, IRSN/DES/SECCA, 92 - Fontenay aux Roses (France); Jendrich, U. [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) mbH, Garching (Germany)

    2003-01-01

    While the neutrons within the core may take part in the chain reaction, those neutrons emitted from the core are basically lost for the energy production. This 'neutron leakage' represents a loss of fuel efficiency and causes neutron embrittlement of the reactor pressure vessel (RPV) wall. The latter raises safety concerns, needs to be monitored closely and may necessitate mitigating measures. There are different strategies to deal with these two undesirable effects: The neutron emission may be reduced to some extent all around the core or just at the 'hot spots' of RPV embrittlement by tailored core loading patterns. A higher absorption rate of neutrons may also be achieved by a larger water gap between the core and the RPV. In this paper the inter-relations between the distribution of neutron flux, core geometry, core loading strategy, RPV embrittlement and its surveillance are discussed at first. Then the different strategies followed by the German and French operators are described. Finally the conclusions will highlight the communalities and differences between these strategies as different approaches to the same problem of safety as well as economy. (authors)

  8. Investigation of radial shear in the wall-base juncture of a 1:4 scale prestressed concrete containment vessel model

    Energy Technology Data Exchange (ETDEWEB)

    Dameron, R.A.; Rashid, Y.R. [ANATECH Corp., San Diego, CA (United States); Luk, V.K.; Hessheimer, M.F. [Sandia National Labs., Albuquerque, NM (United States)

    1998-04-01

    Construction of a prestressed concrete containment vessel (PCCV) model is underway as part of a cooperative containment research program at Sandia National Laboratories. The work is co-sponsored by the Nuclear Power Engineering Corporation (NUPEC) of Japan and US Nuclear Regulatory Commission (NRC). Preliminary analyses of the Sandia 1:4 Scale PCCV Model have determined axisymmetric global behavior and have estimated the potential for failure in several areas, including the wall-base juncture and near penetrations. Though the liner tearing failure mode has been emphasized, the assumption of a liner tearing failure mode is largely based on experience with reinforced concrete containments. For the PCCV, the potential for shear failure at or near the liner tearing pressure may be considerable and requires detailed investigation. This paper examines the behavior of the PCCV in the region most susceptible to a radial shear failure, the wall-basemat juncture region. Prediction of shear failure in concrete structures is a difficult goal, both experimentally and analytically. As a structure begins to deform under an applied system of forces that produce shear, other deformation modes such as bending and tension/compression begin to influence the response. Analytically, difficulties lie in characterizing the decrease in shear stiffness and shear stress and in predicting the associated transfer of stress to reinforcement as cracks become wider and more extensive. This paper examines existing methods for representing concrete shear response and existing criteria for predicting shear failure, and it discusses application of these methods and criteria to the study of the 1:4 scale PCCV.

  9. Structural and functional diversity in Listeria cell wall teichoic acids.

    Science.gov (United States)

    Shen, Yang; Boulos, Samy; Sumrall, Eric; Gerber, Benjamin; Julian-Rodero, Alicia; Eugster, Marcel R; Fieseler, Lars; Nyström, Laura; Ebert, Marc-Olivier; Loessner, Martin J

    2017-10-27

    Wall teichoic acids (WTAs) are the most abundant glycopolymers found on the cell wall of many Gram-positive bacteria, whose diverse surface structures play key roles in multiple biological processes. Despite recent technological advances in glycan analysis, structural elucidation of WTAs remains challenging due to their complex nature. Here, we employed a combination of ultra-performance liquid chromatography-coupled electrospray ionization tandem-MS/MS and NMR to determine the structural complexity of WTAs from Listeria species. We unveiled more than 10 different types of WTA polymers that vary in their linkage and repeating units. Disparity in GlcNAc to ribitol connectivity, as well as variable O-acetylation and glycosylation of GlcNAc contribute to the structural diversity of WTAs. Notably, SPR analysis indicated that constitution of WTA determines the recognition by bacteriophage endolysins. Collectively, these findings provide detailed insight into Listeria cell wall-associated carbohydrates, and will guide further studies on the structure-function relationship of WTAs. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  10. New contributions to the wall polysaccharide structure of vegetative mycelium and fruit body cell walls of Agaricus bisporus.

    Science.gov (United States)

    Calonje, M; García Mendoza, C; Novaes-Ledieu, M

    1996-12-01

    Significant differences in chemical composition and structure of wall polysaccharides were found in Agaricus bisporus vegetative mycelium in comparison with the fruit body mycelium. Chemical fractionation of the walls demonstrated distinct percentages of the successively solubilized polysaccharides in both walls, and different proportions of their respective sugar monomers. Permethylation of isolated fractions also showed striking differences relative to the sugar linkages between the two types of walls studied. Furthermore, infrared spectrophotometry exhibited a distinct polysaccharidic configuration in several fractions. All the described differences were correlated with the transition of vegetative mycelial walls to the fruiting stage of differentiation.

  11. Moisture and Structural Analysis for High Performance Hybrid Wall Assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Grin, A. [Building Science Corporation (BSC), Somerville, MA (United States); Lstiburek, J. [Building Science Corporation (BSC), Somerville, MA (United States)

    2012-09-01

    Based on past experience in the Building America program, BSC has found that combinations of materials and approaches—in other words, systems—usually provide optimum performance. Integration is necessary, as described in this research project. The hybrid walls analyzed utilize a combination of exterior insulation, diagonal metal strapping, and spray polyurethane foam and leave room for cavity-fill insulation. These systems can provide effective thermal, air, moisture, and water barrier systems in one assembly and provide structure.

  12. Blood-Vessel Mimicking Structures by Stereolithographic Fabrication of Small Porous Tubes Using Cytocompatible Polyacrylate Elastomers, Biofunctionalization and Endothelialization

    Directory of Open Access Journals (Sweden)

    Birgit Huber

    2016-04-01

    Full Text Available Blood vessel reconstruction is still an elusive goal for the development of in vitro models as well as artificial vascular grafts. In this study, we used a novel photo-curable cytocompatible polyacrylate material (PA for freeform generation of synthetic vessels. We applied stereolithography for the fabrication of arbitrary 3D tubular structures with total dimensions in the centimeter range, 300 µm wall thickness, inner diameters of 1 to 2 mm and defined pores with a constant diameter of approximately 100 µm or 200 µm. We established a rinsing protocol to remove remaining cytotoxic substances from the photo-cured PA and applied thio-modified heparin and RGDC-peptides to functionalize the PA surface for enhanced endothelial cell adhesion. A rotating seeding procedure was introduced to ensure homogenous endothelial monolayer formation at the inner luminal tube wall. We showed that endothelial cells stayed viable and adherent and aligned along the medium flow under fluid-flow conditions comparable to native capillaries. The combined technology approach comprising of freeform additive manufacturing (AM, biomimetic design, cytocompatible materials which are applicable to AM, and biofunctionalization of AM constructs has been introduced as BioRap® technology by the authors.

  13. Blood-Vessel Mimicking Structures by Stereolithographic Fabrication of Small Porous Tubes Using Cytocompatible Polyacrylate Elastomers, Biofunctionalization and Endothelialization

    Science.gov (United States)

    Huber, Birgit; Engelhardt, Sascha; Meyer, Wolfdietrich; Krüger, Hartmut; Wenz, Annika; Schönhaar, Veronika; Tovar, Günter E. M.; Kluger, Petra J.; Borchers, Kirsten

    2016-01-01

    Blood vessel reconstruction is still an elusive goal for the development of in vitro models as well as artificial vascular grafts. In this study, we used a novel photo-curable cytocompatible polyacrylate material (PA) for freeform generation of synthetic vessels. We applied stereolithography for the fabrication of arbitrary 3D tubular structures with total dimensions in the centimeter range, 300 µm wall thickness, inner diameters of 1 to 2 mm and defined pores with a constant diameter of approximately 100 µm or 200 µm. We established a rinsing protocol to remove remaining cytotoxic substances from the photo-cured PA and applied thio-modified heparin and RGDC-peptides to functionalize the PA surface for enhanced endothelial cell adhesion. A rotating seeding procedure was introduced to ensure homogenous endothelial monolayer formation at the inner luminal tube wall. We showed that endothelial cells stayed viable and adherent and aligned along the medium flow under fluid-flow conditions comparable to native capillaries. The combined technology approach comprising of freeform additive manufacturing (AM), biomimetic design, cytocompatible materials which are applicable to AM, and biofunctionalization of AM constructs has been introduced as BioRap® technology by the authors. PMID:27104576

  14. Fluid-structure interaction simulations of the Fontan procedure using variable wall properties.

    Science.gov (United States)

    Long, C C; Hsu, M-C; Bazilevs, Y; Feinstein, J A; Marsden, A L

    2012-05-01

    Children born with single ventricle heart defects typically undergo a staged surgical procedure culminating in a total cavopulmonary connection (TCPC) or Fontan surgery. The goal of this work was to perform physiologic, patient-specific hemodynamic simulations of two post-operative TCPC patients by using fluid-structure interaction (FSI) simulations. Data from two patients are presented, and post-op anatomy is reconstructed from MRI data. Respiration rate, heart rate, and venous pressures are obtained from catheterization data, and inflow rates are obtained from phase contrast MRI data and are used together with a respiratory model. Lumped parameter (Windkessel) boundary conditions are used at the outlets. We perform FSI simulations by using an arbitrary Lagrangian-Eulerian finite element framework to account for motion of the blood vessel walls in the TCPC. This study is the first to introduce variable elastic properties for the different areas of the TCPC, including a Gore-Tex conduit. Quantities such as wall shear stresses and pressures at critical locations are extracted from the simulation and are compared with pressure tracings from clinical data as well as with rigid wall simulations. Hepatic flow distribution and energy efficiency are also calculated and compared for all cases. There is little effect of FSI on pressure tracings, hepatic flow distribution, and time-averaged energy efficiency. However, the effect of FSI on wall shear stress, instantaneous energy efficiency, and wall motion is significant and should be considered in future work, particularly for accurate prediction of thrombus formation. Copyright © 2012 John Wiley & Sons, Ltd.

  15. Bioreactor rotating wall vessel

    Science.gov (United States)

    2001-01-01

    The NASA Bioreactor provides a low turbulence culture environment which promotes the formation of large, three-dimensional cell clusters. Due to their high level of cellular organization and specialization, samples constructed in the bioreactor more closely resemble the original tumor or tissue found in the body. The work is sponsored by NASA's Office of Biological and Physical Research. The bioreactor is managed by the Biotechnology Cell Science Program at NASA's Johnson Space Center (JSC). NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues being cultured in rotating bioreactors by investigators. Cell constructs grown in a rotating bioreactor on Earth (left) eventually become too large to stay suspended in the nutrient media. In the microgravity of orbit, the cells stay suspended. Rotation then is needed for gentle stirring to replenish the media around the cells.

  16. Differentiation of deep subcortical infarction using high-resolution vessel wall MR imaging of middle cerebral artery

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Yun Jung; Choi, Byung Se; Jung, Cheol Kyu; Yoon, Yeon Hong; Sunwoo, Leonard; Kim, Jae Hyoung; Bae, Hee Joon [Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam (Korea, Republic of)

    2017-11-15

    To evaluate the utility of high-resolution vessel wall imaging (HR-VWI) of middle cerebral artery (MCA), and to compare HR-VWI findings between striatocapsular infarction (SC-I) and lenticulostriate infarction (LS-I). This retrospective study was approved by the Institutional Review Board, and informed consent was waived. From July 2009 to February 2012, 145 consecutive patients with deep subcortical infarctions (SC-I, n = 81; LS-I, n = 64) who underwent HR-VWI were included in this study. The degree of MCA stenosis and the characteristics of MCA plaque (presence, eccentricity, location, extent, T2-high signal intensity [T2-HSI], and plaque enhancement) were analyzed, and compared between SC-I and LS-I, using Fisher's exact test. Stenosis was more severe in SC-I than in LS-I (p = 0.040). MCA plaque was more frequent in SC-I than in LS-I (p = 0.028), having larger plaque extent (p = 0.001), more T2-HSI (p = 0.001), and more plaque enhancement (p = 0.002). The eccentricity and location of the plaque showed no significant difference between the two groups.Both SC-I and LS-I have similar HR-VWI findings of the MCA plaque, but SC-I had more frequent, larger plaques with greater T2-HSI and enhancement. This suggests that HR-VWI may have a promising role in assisting the differentiation of underlying pathophysiological mechanism between SC-I and LS-I.

  17. Structural constraints and dynamics of bacterial cell wall architecture

    Directory of Open Access Journals (Sweden)

    Miguel Angel De Pedro

    2015-05-01

    Full Text Available The peptidoglycan wall (PG is a unique structure which confers physical strength and defined shape to bacteria. It consists of a net-like macromolecule of peptide interlinked glycan chains overlying the cell membrane. The structure and layout of the PG dictates that the wall has to be continuously modified as bacteria go through division, morphological differentiation and adaptive responses. The PG is poorly known in structural terms. However, to understand morphogenesis a precise knowledge of glycan strand arrangement and of local effects of the different kinds of subunits is essential. The scarcity of data led to a conception of the PG as a regular, highly ordered structure which strongly influenced growth models. Here, we review the structure of the PG to define a more realistic conceptual framework. We discuss the consequences of the plasticity of murein architecture in morphogenesis and try to define a set of minimal structural constraints that must be fulfilled by any model to be compatible with present day information.

  18. The influence of selected containment structures on debris dispersal and transport following high pressure melt ejection from the reactor vessel

    Energy Technology Data Exchange (ETDEWEB)

    Pilch, M.; Tarbell, W.W.; Brockmann, J.E.

    1988-09-01

    High pressure expulsion of molten core debris from the reactor pressure vessel may result in dispersal of the debris from the reactor cavity. In most plants, the cavity exits into the containment such that the debris impinges on structures. Retention of the debris on the structures may affect the further transport of the debris throughout the containment. Two tests were done with scaled structural shapes placed at the exit of 1:10 linear scale models of the Zion cavity. The results show that the debris does not adhere significantly to structures. The lack of retention is attributed to splashing from the surface and reentrainment in the gas flowing over the surface. These processes are shown to be applicable to reactor scale. A third experiment was done to simulate the annular gap between the reactor vessel and cavity wall. Debris collection showed that the fraction of debris exiting through the gap was greater than the gap-to-total flow area ratio. Film records indicate that dispersal was primarily by entrainment of the molten debris in the cavity. 29 refs., 36 figs., 11 tabs.

  19. Vascular wall proteoglycan synthesis and structure as a target for the prevention of atherosclerosis

    Science.gov (United States)

    Little, Peter J; Ballinger, Mandy L; Osman, Narin

    2007-01-01

    Atherosclerosis is the underlying pathology of most cardiovascular disease and it represents the major cause of premature death in modern societies. Current therapies target risk factors being hypertension, hypercholesterolemia, hypertriglyceridemia and hyperglycemia when diabetes is present however the maximum efficacy of these strategies is often 30% or less. Areas of vascular biology that may lead to the development of a complementary vascular wall directed therapy are: inflammation, oxidation, endothelial dysfunction, diabetes-specific factors—hyperglycemia and advanced glycation endproducts and lipid retention by vascular matrix specifically proteoglycans. The major structural features of proteoglycans that determine low-density lipoprotein (LDL) binding are the length and sulfation pattern on the glycosaminoglycan (GAG) chains. Emerging data discussed in this review indicates that these structural properties are subject to considerable regulation by vasoactive substances possibly using novel signaling pathways. For example, GAG elongation stimulated by platelet-derived growth factor is not blocked by the receptor tyrosine kinase antagonist, genistein suggesting that there may be a previously unknown signaling pathway involved in this response. Thus, modifying proteoglycan synthesis and structure may represent a prime target to prevent LDL binding and entrapment in the vessel wall and thus prevent the development and progression of atherosclerosis. PMID:17583182

  20. Vascular wall proteoglycan synthesis and structure as a target for the prevention of atherosclerosis.

    Science.gov (United States)

    Little, Peter J; Ballinger, Mandy L; Osman, Narin

    2007-01-01

    Atherosclerosis is the underlying pathology of most cardiovascular disease and it represents the major cause of premature death in modern societies. Current therapies target risk factors being hypertension, hypercholesterolemia, hypertriglyceridemia and hyperglycemia when diabetes is present however the maximum efficacy of these strategies is often 30% or less. Areas of vascular biology that may lead to the development of a complementary vascular wall directed therapy are: inflammation, oxidation, endothelial dysfunction, diabetes-specific factors--hyperglycemia and advanced glycation endproducts and lipid retention by vascular matrix specifically proteoglycans. The major structural features of proteoglycans that determine low-density lipoprotein (LDL) binding are the length and sulfation pattern on the glycosaminoglycan (GAG) chains. Emerging data discussed in this review indicates that these structural properties are subject to considerable regulation by vasoactive substances possibly using novel signaling pathways. For example, GAG elongation stimulated by platelet-derived growth factor is not blocked by the receptor tyrosine kinase antagonist, genistein suggesting that there may be a previously unknown signaling pathway involved in this response. Thus, modifying proteoglycan synthesis and structure may represent a prime target to prevent LDL binding and entrapment in the vessel wall and thus prevent the development and progression of atherosclerosis.

  1. Use of Magnetic Nanoparticles to Visualize Threadlike Structures inside Lymphatic Vessels of Rats

    Directory of Open Access Journals (Sweden)

    Hyeon-Min Johng

    2007-01-01

    Full Text Available A novel application of fluorescent magnetic nanoparticles was made to visualize a new tissue which had not been detectable by using simple stereomicroscopes. This unfamiliar threadlike structure inside the lymphatic vessels of rats was demonstrated in vivo by injecting nanoparticles into lymph nodes and applying magnetic fields on the collecting lymph vessels so that the nanoparticles were taken up by the threadlike structures. Confocal laser scanning microscope images of cryosectioned specimens exhibited that the nanoparticles were absorbed more strongly by the threadlike structure than by the lymphatic vessels. Further examination using a transmission electron microscope revealed that the nanoparticles had been captured between the reticular fibers in the extracellular matrix of the threadlike structures. The emerging technology of nanoparticles not only allows the extremely elusive threadlike structures to be visualized but also is expected to provide a magnetically controllable means to investigate their physiological functions.

  2. Influence of the myocardial bridging phenomenon on the myocardial structure and the coronary arteries wall structure changes

    Directory of Open Access Journals (Sweden)

    Tomanović-Koković Jelena

    2006-01-01

    Full Text Available Background/Aim. Our research was performed to evaluate the influences of the myocardial bridging of coronary arteries on the myocardial and coronary arteries wall structure changes, that could be a reason for multiple heart malfunctions. Methods. We analyzed the autopsy material, collected during a five-years period, and especially the group of 575 cases with the major aim to diagnose mors naturalis. In all cases with the presence of myocardial bridge over the arterial coronary wall revealed at autopsy, samples were taken for microscopic verification and examination. Results. We found myocardial bridges over the coronary arteries or their major branches in 27 of the cases (4.70%. We believe that myocardial bridges compromise coronary perfusion by cyclic compression of the overbridged vessels, and that it could be the initial factor in the pathogenesis of arteriosclerotic degeneration processes on the coronary artery wall. We found different grades of arteriosclerotic changes in 88.89% of the cases, as well as fibrosis of myocardium in 88.89% and lipomatosis in 66.67% of the cases with the present myocardial bridges. Conclusion. Our results suggested that myocardial bridging of coronary arteries and/or their branches was the pathological and even lethal phenomenon that deserves more intensive clinical evaluation.

  3. Structure analysis of a reactor pressure vessel by two- and three-dimensional models. [PWR

    Energy Technology Data Exchange (ETDEWEB)

    Sacher, H.; Mayr, M.

    1982-03-01

    This paper investigates the reactor pressure vessel of a 1300 MW pressurised water reactor. In order to determine the stresses and deformations of the vessel, two- and three-dimensional finite element models are used which represent the real structure with different degrees of accuracy. The results achieved by these different models are compared for the case of the transient called ''Start up of the nuclear power plant''. 5 refs.

  4. Preliminary structural assessment of DEMO vacuum vessel against a vertical displacement event

    Energy Technology Data Exchange (ETDEWEB)

    Mozzillo, Rocco, E-mail: rocco.mozzillo@unina.it [CREATE, University of Naples Federico II, DII, P.le Tecchio 80, 80125, Naples (Italy); Tarallo, Andrea; Marzullo, Domenico [CREATE, University of Naples Federico II, DII, P.le Tecchio 80, 80125, Naples (Italy); Bachmann, Christian [EUROfusion PMU, Boltzmannstraße 2, 85748 Garching (Germany); Di Gironimo, Giuseppe [CREATE, University of Naples Federico II, DII, P.le Tecchio 80, 80125, Naples (Italy); Mazzone, Giuseppe [Unità Tecnica Fusione - ENEA C.R. Frascati, Via E. Fermi 45, 00044 Frascati (Italy)

    2016-11-15

    Highlights: • The paper focuses on a preliminary structural analysis of the current concept design of DEMO vacuum vessel. • The Vacuum Vessel was checked against the VDE in combinations with the weight force of all components that the vessel shall bear. • Different configurations for the vacuum vessel supports are considered, showing that the best solution is VV supported at the lower port. • The analyses evaluated the “P damage” according to RCC-MRx code. - Abstract: This paper focuses on a preliminary structural analysis of the current concept design of DEMO vacuum vessel (VV). The VV structure is checked against a vertical load due to a Vertical Displacement Event in combination with the weight force of all components that the main vessel shall bear. Different configurations for the supports are considered. Results show that the greatest safety margins are reached when the tokamak is supported through the lower ports rather than the equatorial ports, though all analyzed configurations are compliant with RCC-MRx design rules.

  5. The deterministic structural integrity assessment of reactor pressure vessels under pressurized thermal shock loading

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Mingya, E-mail: chenmingya@cgnpc.com.cn; Lu, Feng; Wang, Rongshan; Huang, Ping; Liu, Xiangbin; Zhang, Guodong; Xu, Chaoliang

    2015-07-15

    Highlights: • The conservative and non-conservative assumptions in the codes were shown. • The influence of different loads on the SM was given. • The unloading effect of the cladding was studied. • A concentrated reflection of the safety was shown based on 3-D FE analyses. - Abstract: The deterministic structural integrity of a reactor pressure vessel (RPV) related to pressurized thermal shocks (PTSs) has been extensively studied. While the nil-ductility-transition temperature (RT{sub NDT}) parameter is widely used, the influence of fluence and temperature distributions along the thickness of the base metal wall cannot be reflected in the comparative analysis. This paper introduces the method using a structure safety margin (SM) parameter which is based on a comparison between the material toughness (the fracture initiation toughness K{sub IC} or fracture arrest toughness K{sub Ia}) and the stress intensity factor (SIF) along the crack front for the integrity analysis of a RPV subjected to PTS transients. A 3-D finite element model is used to perform fracture mechanics analyses considering both crack initiation assessment and arrest assessment. The results show that the critical part along the crack front is always the clad-base metal interface point (IP) rather than the deepest point (DP) for either crack initiation assessment or crack arrest assessment under the thermal load. It is shown that the requirement in Regulatory Guide 1.154 that ‘axial flaws with depths less than 20% of the wall thickness and all circumferential flaws should be modeled in infinite length’ may be non-conservative. As the assessment result is often poor universal for a given material, crack and transient, caution is recommended in the safety assessment, especially for the IP. The SIF reduces under the thermal or pressure load if the map cracking (MC) effect is considered. Therefore, the assumption in the ASME and RCCM codes that the cladding should be taken into account in

  6. Could Nano-Structured Materials Enable the Improved Pressure Vessels for Deep Atmospheric Probes?

    Science.gov (United States)

    Srivastava, D.; Fuentes, A.; Bienstock, B.; Arnold, J. O.

    2005-01-01

    A viewgraph presentation on the use of Nano-Structured Materials to enable pressure vessel structures for deep atmospheric probes is shown. The topics include: 1) High Temperature/Pressure in Key X-Environments; 2) The Case for Use of Nano-Structured Materials Pressure Vessel Design; 3) Carbon based Nanomaterials; 4) Nanotube production & purification; 5) Nanomechanics of Carbon Nanotubes; 6) CNT-composites: Example (Polymer); 7) Effect of Loading sequence on Composite with 8% by volume; 8) Models for Particulate Reinforced Composites; 9) Fullerene/Ti Composite for High Strength-Insulating Layer; 10) Fullerene/Epoxy Composite for High Strength-Insulating Layer; 11) Models for Continuous Fiber Reinforced Composites; 12) Tensile Strength for Discontinuous Fiber Composite; 13) Ti + SWNT Composites: Thermal/Mechanical; 14) Ti + SWNT Composites: Tensile Strength; and 15) Nano-structured Shell for Pressure Vessels.

  7. The Dynamic Similitude Design Method of Thin Walled Structures and Experimental Validation

    Directory of Open Access Journals (Sweden)

    Zhong Luo

    2016-01-01

    Full Text Available For the applicability of dynamic similitude models of thin walled structures, such as engine blades, turbine discs, and cylindrical shells, the dynamic similitude design of typical thin walled structures is investigated. The governing equation of typical thin walled structures is firstly unified, which guides to establishing dynamic scaling laws of typical thin walled structures. Based on the governing equation, geometrically complete scaling law of the typical thin walled structure is derived. In order to determine accurate distorted scaling laws of typical thin walled structures, three principles are proposed and theoretically proved by combining the sensitivity analysis and governing equation. Taking the thin walled annular plate as an example, geometrically complete and distorted scaling laws can be obtained based on the principles of determining dynamic scaling laws. Furthermore, the previous five orders’ accurate distorted scaling laws of thin walled annular plates are presented and numerically validated. Finally, the effectiveness of the similitude design method is validated by experimental annular plates.

  8. Stress analysis for wall structure in mobile hot cell design

    Energy Technology Data Exchange (ETDEWEB)

    Bahrin, Muhammad Hannan, E-mail: hannan@nuclearmalaysia.gov.my; Rahman, Anwar Abdul, E-mail: anwar@nuclearmalaysia.gov.my; Hamzah, Mohd Arif, E-mail: arif@nuclearmalaysia.gov.my; Mamat, Mohd Rizal; Azman, Azraf; Hasan, Hasni [Prototype and Plant Development Centre, Technical Services Division, Malaysian Nuclear Agency (Malaysia)

    2016-01-22

    Malaysian Nuclear Agency is developing a Mobile Hot Cell (MHC) in order to handle and manage Spent High Activity Radioactive Sources (SHARS) such as teletherapy heads and irradiators. At present, there are only two units of MHC in the world, in South Africa and China. Malaysian Mobile Hot cell is developed by Malaysian Nuclear Agency with the assistance of IAEA expert, based on the design of South Africa and China, but with improved features. Stress analysis has been performed on the design in order to fulfil the safety requirement in operation of MHC. This paper discusses the loading analysis effect from the sand to the MHC wall structure.

  9. Earthquake resistant structural walls: Test of walls with and without openings

    Science.gov (United States)

    Shiu, K. N.; Daniel, J. I.; Aristizabal-Ochoa, J. D.; Fiorato, A. E.; Corley, W. G.

    1981-07-01

    Two one-third scale, six-story wal specimens were subjected to inelastic load reversals representing severe earthquake forces exerted by double acting hydraulic rams, located on both sides of the wall specimens, and applied to the top of each wall. The specimens were designed of earthquake resistant reinforced concrete wall elements in coupled wall systems based on the 1976 Uniform Building Code. The loading was calculated using a modified DRAIN two-dimensional computer program with two actual earthquake records used as input ground motion data. One specimen was a solid wall and the other included six openings simulating windows. When data was normalized by yield capacities, the resonse of the two walls to the inelastic loading was similar. The presence of window openings had little effect on the deformation characteristics of the sample walls in response to the cyclic loads.

  10. [Effects of hypotensive treatment on structural-functional properties of the vascular wall in hypertensive patients].

    Science.gov (United States)

    Maslennikova, O M; Romanchuk, S V; Rachkova, S A; Nazarova, O A

    2008-01-01

    To study structural-functional properties of the walls of large and middle-size arteries and changes of these properties in the course of hypotensive therapy in hypertensive patients. Of 609 participants of the trial (233 males and 376 females), 377 patients with essential hypertension stage I-II (mean age 46.9 +/- 7.2 years) entered the study group, 232 healthy subjects (mean age 45.7 +/- 6.9 years)--the control group. Pulse wave velocity (PWV) for vessels of elastic and muscular type was measured in all the examinees. Circadian blood pressure monitoring, echocardiography, duplex scanning of the common carotid artery were performed in hypertensive patients. 76 hypertensive patients were reexamined 6 months after treatment with amlodipin (n = 32) or fixed combination perindopril+indapamide (n = 44). Mean PWV appeared to be higher in hypertensive patients in whom PWV correlated with left ventricular (LV) remodeling and thickness of intima-media complex (IMC). After 6 months of hypotensive therapy PWV significantly lowered for both types of vessels studied. IMC thickness reduced by 10.1%, on the average, LV myocardial mass index--by 6.3%. The link between PWV, LV hypertrophy and IMC allows PWV use as a method of detection of cardiovascular remodeling in hypertension and for follow-up of antihypertensive treatment effect on this remodeling in outpatient treatment of hypertension.

  11. Role of tissue structure on ventricular wall mechanics

    OpenAIRE

    Coppola, Benjamin A.; Omens, Jeffrey H.

    2008-01-01

    It is well known that systolic wall thickening in the inner half of the left ventricular (LV) wall is of greater magnitude than predicted by myofiber contraction alone. Previous studies have related the deformation of the LV wall to the orientation of the laminar architecture. Using this method, wall thickening can be interpreted as the sum of contributions due to extension, thickening, and shearing of the laminar sheets. We hypothesized that the thickening mechanics of the ventricular wall a...

  12. Osteoblasts extracellular matrix induces vessel like structures through glycosylated collagen I

    Energy Technology Data Exchange (ETDEWEB)

    Palmieri, D. [Genetics, DIBIO, University of Genova, Corso Europa 26, 16132 Genova (Italy); Valli, M.; Viglio, S. [Department of Biochemistry, University of Pavia (Italy); Ferrari, N. [Istituto Nazionale per la ricerca sul Cancro, Genova (Italy); Ledda, B.; Volta, C. [Genetics, DIBIO, University of Genova, Corso Europa 26, 16132 Genova (Italy); Manduca, P., E-mail: man-via@unige.it [Genetics, DIBIO, University of Genova, Corso Europa 26, 16132 Genova (Italy)

    2010-03-10

    Extracellular matrix (ECM) plays a fundamental role in angiogenesis affecting endothelial cells proliferation, migration and differentiation. Vessels-like network formation in vitro is a reliable test to study the inductive effects of ECM on angiogenesis. Here we utilized matrix deposed by osteoblasts as substrate where the molecular and structural complexity of the endogenous ECM is preserved, to test if it induces vessel-like network formation by endothelial cells in vitro. ECM is more similar to the physiological substrate in vivo than other substrates previously utilized for these studies in vitro. Osteogenic ECM, prepared in vitro from mature osteoblasts at the phase of maximal deposition and glycosylation of collagen I, induces EAhy926, HUVEC, and HDMEC endothelial cells to form vessels-like structures and promotes the activation of metalloproteinase-2 (MMP-2); the functionality of the p-38/MAPK signaling pathway is required. Osteogenic ECM also induces a transient increase of CXCL12 and a decrease of the receptor CXCR4. The induction of vessel-like networks is dependent from proper glycosylation of collagens and does not occur on osteogenic ECMs if deglycosylated by -galactosidase or on less glycosylated ECMs derived from preosteoblasts and normal fibroblasts, while is sustained on ECM from osteogenesis imperfecta fibroblasts only when their mutation is associated with over-glycosylation of collagen type I. These data support that post-translational glycosylation has a role in the induction in endothelial cells in vitro of molecules conductive to self-organization in vessels-like structures.

  13. Nuclear reactor construction with bottom supported reactor vessel

    Science.gov (United States)

    Sharbaugh, John E.

    1987-01-01

    An improved liquid metal nuclear reactor construction has a reactor core and a generally cylindrical reactor vessel for holding a large pool of low pressure liquid metal coolant and housing the core within the pool. The reactor vessel has an open top end, a closed flat bottom end wall and a continuous cylindrical closed side wall interconnecting the top end and bottom end wall. The reactor also has a generally cylindrical concrete containment structure surrounding the reactor vessel and being formed by a cylindrical side wall spaced outwardly from the reactor vessel side wall and a flat base mat spaced below the reactor vessel bottom end wall. A central support pedestal is anchored to the containment structure base mat and extends upwardly therefrom to the reactor vessel and upwardly therefrom to the reactor core so as to support the bottom end wall of the reactor vessel and the lower end of the reactor core in spaced apart relationship above the containment structure base mat. Also, an annular reinforced support structure is disposed in the reactor vessel on the bottom end wall thereof and extends about the lower end of the core so as to support the periphery thereof. In addition, an annular support ring having a plurality of inward radially extending linear members is disposed between the containment structure base mat and the bottom end of the reactor vessel wall and is connected to and supports the reactor vessel at its bottom end on the containment structure base mat so as to allow the reactor vessel to expand radially but substantially prevent any lateral motions that might be imposed by the occurrence of a seismic event. The reactor construction also includes a bed of insulating material in sand-like granular form, preferably being high density magnesium oxide particles, disposed between the containment structure base mat and the bottom end wall of the reactor vessel and uniformly supporting the reactor vessel at its bottom end wall on the containment

  14. Degree of coupling in high-rise mixed shear walls structures

    Indian Academy of Sciences (India)

    Keywords. Coupled shear walls; degree of coupling; peak shear demand; concrete. ... The proposed graphical method is based on the continuous medium theory and allows a rapid assessment of the structural behaviour of coupled shear wall bents in mixed shear wall structures that are subject to horizontal loading.

  15. Dilated thin-walled blood and lymphatic vessels in human endometrium: a potential role for VEGF-D in progestin-induced break-through bleeding.

    Directory of Open Access Journals (Sweden)

    Jacqueline F Donoghue

    Full Text Available Progestins provide safe, effective and cheap options for contraception as well as the treatment of a variety of gynaecological disorders. Episodes of irregular endometrial bleeding or breakthrough bleeding (BTB are a major unwanted side effect of progestin treatment, such that BTB is the leading cause for discontinued use of an otherwise effective and popular medication. The cellular mechanisms leading to BTB are poorly understood. In this study, we make the novel finding that the large, dilated, thin walled vessels characteristic of human progestin-treated endometrium include both blood and lymphatic vessels. Increased blood and lymphatic vessel diameter are features of VEGF-D action in other tissues and we show by immunolocalisation and Western blotting that stromal cell decidualisation results in a significant increase in VEGF-D protein production, particularly of the proteolytically processed 21 kD form. Using a NOD/scid mouse model with xenografted human endometrium we were able to show that progestin treatment causes decidualisation, VEGF-D production and endometrial vessel dilation. Our results lead to a novel hypothesis to explain BTB, with stromal cell decidualisation rather than progestin treatment per se being the proposed causative event, and VEGF-D being the proposed effector agent.

  16. Motion and wave load analyses of large offshore structures and special vessels in waves

    OpenAIRE

    Wu, Xiong-Jian

    1990-01-01

    This thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel University. Predictions of the environmental loading and induced motional and structural responses are among the most important aspects in the overall design process of offshore structures and ships. In this thesis, attention is focused on the wave loads and excited bodily motion responses of large offshore structures and special vessels. With the aim of improving the existing theoretical methods ...

  17. Load-carrying capacity of lightly reinforced, prefabricated walls of lightweight aggregate concrete with open structure

    DEFF Research Database (Denmark)

    Goltermann, Per

    2009-01-01

    The paper presents and evaluates the results of a coordinated testing of prefabricated, lightly reinforced walls of lightweight aggregate concrete with open structure. The coordinated testing covers all wall productions in Denmark and will therefore provide a representative assessment...

  18. Single-Walled Carbon-Nanotubes-Based Organic Memory Structures

    Directory of Open Access Journals (Sweden)

    Sundes Fakher

    2016-09-01

    Full Text Available The electrical behaviour of organic memory structures, based on single-walled carbon-nanotubes (SWCNTs, metal–insulator–semiconductor (MIS and thin film transistor (TFT structures, using poly(methyl methacrylate (PMMA as the gate dielectric, are reported. The drain and source electrodes were fabricated by evaporating 50 nm gold, and the gate electrode was made from 50 nm-evaporated aluminium on a clean glass substrate. Thin films of SWCNTs, embedded within the insulating layer, were used as the floating gate. SWCNTs-based memory devices exhibited clear hysteresis in their electrical characteristics (capacitance–voltage (C–V for MIS structures, as well as output and transfer characteristics for transistors. Both structures were shown to produce reliable and large memory windows by virtue of high capacity and reduced charge leakage. The hysteresis in the output and transfer characteristics, the shifts in the threshold voltage of the transfer characteristics, and the flat-band voltage shift in the MIS structures were attributed to the charging and discharging of the SWCNTs floating gate. Under an appropriate gate bias (1 s pulses, the floating gate is charged and discharged, resulting in significant threshold voltage shifts. Pulses as low as 1 V resulted in clear write and erase states.

  19. Structural analysis of the ITER Vacuum Vessel regarding 2012 ITER Project-Level Loads

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, J.-M., E-mail: jean-marc.martinez@live.fr [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul lez Durance (France); Jun, C.H.; Portafaix, C.; Choi, C.-H.; Ioki, K.; Sannazzaro, G.; Sborchia, C. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul lez Durance (France); Cambazar, M.; Corti, Ph.; Pinori, K.; Sfarni, S.; Tailhardat, O. [Assystem EOS, 117 rue Jacquard, L' Atrium, 84120 Pertuis (France); Borrelly, S. [Sogeti High Tech, RE2, 180 rue René Descartes, Le Millenium – Bat C, 13857 Aix en Provence (France); Albin, V.; Pelletier, N. [SOM Calcul – Groupe ORTEC, 121 ancien Chemin de Cassis – Immeuble Grand Pré, 13009 Marseille (France)

    2014-10-15

    Highlights: • ITER Vacuum Vessel is a part of the first barrier to confine the plasma. • ITER Vacuum Vessel as Nuclear Pressure Equipment (NPE) necessitates a third party organization authorized by the French nuclear regulator to assure design, fabrication, conformance testing and quality assurance, i.e. Agreed Notified Body (ANB). • A revision of the ITER Project-Level Load Specification was implemented in April 2012. • ITER Vacuum Vessel Loads (seismic, pressure, thermal and electromagnetic loads) were summarized. • ITER Vacuum Vessel Structural Margins with regards to RCC-MR code were summarized. - Abstract: A revision of the ITER Project-Level Load Specification (to be used for all systems of the ITER machine) was implemented in April 2012. This revision supports ITER's licensing by accommodating requests from the French regulator to maintain consistency with the plasma physics database and our present understanding of plasma transients and electro-magnetic (EM) loads, to investigate the possibility of removing unnecessary conservatism in the load requirements and to review the list and definition of incidental cases. The purpose of this paper is to present the impact of this 2012 revision of the ITER Project-Level Load Specification (LS) on the ITER Vacuum Vessel (VV) loads and the main structural margins required by the applicable French code, RCC-MR.

  20. Distortional Mechanics of Thin-Walled Structural Elements

    DEFF Research Database (Denmark)

    Andreassen, Michael Joachim

    In several industries such as civil, mechanical, and aerospace, thin-walled structures are often used due to the high strength and effective use of the materials. Because of the increased consumption there has been increasing focus on optimizing and more detailed calculations. However, finely...... eigenmodes and may be used in the automatic meshing of approximate distortional beam elements. The magnitude of the eigenvalues thus also gives the natural ordering of the modes. The results are compared to results found using other computational methods taking distortion of the cross section into account...... provides reasonable results with a very small computational cost making it a good alternative to the classical FE calculations and other available methods....

  1. CONSTRUCTIVE ASPECTS INFLUENCE ON STIFFNESS OF DIAPHRAGM WALLS IN FRAME CONSTRUCTIONS WITH (LIGHT STEEL THIN –WALLED STRUCTURES

    Directory of Open Access Journals (Sweden)

    M. V. Savytskyi

    2010-10-01

    Full Text Available The dependences of influence of structural features of diaphragms of lightweight steel framing braced wall structures on their stiffness are determined. On the basis of dependences the procedure for estimation of stiffness of a diaphragm of any configuration that allows making decisions for maintenance of building stiffness is developed.

  2. High-resolution 3D coronary vessel wall imaging with near 100% respiratory efficiency using epicardial fat tracking: reproducibility and comparison with standard methods.

    Science.gov (United States)

    Scott, Andrew D; Keegan, Jennifer; Firmin, David N

    2011-01-01

    To quantitatively assess the performance and reproducibility of 3D spiral coronary artery wall imaging with beat-to-beat respiratory-motion-correction (B2B-RMC) compared to navigator gated 2D spiral and turbo-spin-echo (TSE) acquisitions. High-resolution (0.7 × 0.7 mm) cross-sectional right coronary wall acquisitions were performed in 10 subjects using four techniques (B2B-RMC 3D spiral with alternate (2RR) and single (1RR) R-wave gating, navigator-gated 2D spiral (2RR) and navigator-gated 2D TSE (2RR)) on two occasions. Wall thickness measurements were compared with repeated measures analysis of variance (ANOVA). Reproducibility was assessed with the intraclass correlation coefficient (ICC). In all, 91% (73/80) of acquisitions were successful (failures: four TSE, two 3D spiral (1RR) and one 3D spiral (2RR)). Respiratory efficiency of the B2B-RMC was less variable and substantially higher than for navigator gating (99.6 ± 1.2% vs. 39.0 ± 7.5%, P B2B-RMC permits coronary vessel wall assessment over multiple thin contiguous slices in a clinically feasible duration. Excellent reproducibility of the technique potentially enables studies of disease progression/regression. Copyright © 2010 Wiley-Liss, Inc.

  3. Effect of Temperature Change on Geometric Structure of Isolated Mixing Regions in Stirred Vessel

    Directory of Open Access Journals (Sweden)

    Nor Hanizah Shahirudin

    2012-01-01

    Full Text Available The present work experimentally investigated the effect of temperature change on the geometric structure of isolated mixing regions (IMRs in a stirred vessel by the decolorization of fluorescent green dye by acid-base neutralization. A four-bladed Rushton turbine was installed in an unbaffled stirred vessel filled with glycerin as a working fluid. The temperature of working fluid was changed in a stepwise manner from 30°C to a certain fixed value by changing the temperature of the water jacket that the vessel was equipped with. The step temperature change can dramatically reduce the elimination time of IMRs, as compared with a steady temperature operation. During the transient process from an initial state to disappearance of IMR, the IMR showed interesting three-dimensional geometrical changes, that are, simple torus with single filament, simple torus without filaments, a combination of crescent shape and circular tori, and doubly entangled torus.

  4. Structure analysis of a reactor pressure vessel by two and three-dimensional models

    Energy Technology Data Exchange (ETDEWEB)

    Sacher, H.; Mayr, M. (Technischer Ueberwachungs-Verein Bayern e.V., Muenchen (Germany, F.R.))

    1982-03-01

    This paper investigates the reactor pressure vessel of a 1300 MW pressurised water reactor. In order to determine the stresses and deformations of the vessel, two- and three-dimensional finite element models are used which represent the real structure with different degrees of accuracy. The results achieved by these different models are compared for the case of the transient called 'Start up of the nuclear power plant'. It was found that axisymmetric models, which consider non-axisymmetric components by correction factors, together with special attention to holes and other stress concentrations, allow a sufficient computation of stresses and deformations in the vessel, with the exception of the coolant nozzle region. In this latter case a fully three-dimensional analysis may be necessary.

  5. Vascular wall proteoglycan synthesis and structure as a target for the prevention of atherosclerosis

    Directory of Open Access Journals (Sweden)

    Peter J Little

    2007-03-01

    Full Text Available Peter J Little1, 2, 3, Mandy L. Ballinger1, Narin Osman1,31Cell Biology of Diabetes Laboratory, Baker Heart Research Institute, Melbourne, Australia; Monash University, Departments of 2Medicine and 3Immunology, Central and Eastern Clinical School, Alfred Hospital, Melbourne, AustraliaAbstract: Atherosclerosis is the underlying pathology of most cardiovascular disease and it represents the major cause of premature death in modern societies. Current therapies target risk factors being hypertension, hypercholesterolemia, hypertriglyceridemia and hyperglycemia when diabetes is present however the maximum efficacy of these strategies is often 30% or less. Areas of vascular biology that may lead to the development of a complementary vascular wall directed therapy are: inflammation, oxidation, endothelial dysfunction, diabetes-specific factors —hyperglycemia and advanced glycation endproducts and lipid retention by vascular matrix specifically proteoglycans. The major structural features of proteoglycans that determine low-density lipoprotein (LDL binding are the length and sulfation pattern on the glycosaminoglycan (GAG chains. Emerging data discussed in this review indicates that these structural properties are subject to considerable regulation by vasoactive substances possibly using novel signaling pathways. For example, GAG elongation stimulated by platelet-derived growth factor is not blocked by the receptor tyrosine kinase antagonist, genistein suggesting that there may be a previously unknown signaling pathway involved in this response. Thus, modifying proteoglycan synthesis and structure may represent a prime target to prevent LDL binding and entrapment in the vessel wall and thus prevent the development and progression of atherosclerosis.Keywords: proteoglycans, signaling, lipoproteins, atherosclerosis

  6. Weight optimization of offshore supply vessel based on structural analysis using finite element meth

    Directory of Open Access Journals (Sweden)

    Ahmed M.H. Elhewy

    2016-06-01

    Full Text Available Ship design process usually relies on statistics and comparisons with existing ships, rather than analytical approaches and optimization techniques. Designers found this way as the best to fulfil the owner’s requirements, but better solutions, for both the shipyard and the owner may exist. Assessing ship life cycle cost is one of the most attractive tasks for shipyard during early design stage. Structural optimization can be used to achieve that task. In this paper, a comprehensive study on the structural optimization of an offshore supply vessel (OSV, as a case study, is presented. Detailed structural modeling of the vessel is created. Various environmental loads acting on the ship hull such as still water loads and wave induced loads are briefly explained. Different loading conditions and corresponding structural responses have been investigated to assign the most severe one on the vessel. The basic concept of structural optimization and optimization characteristics is highlighted. Blind search optimization technique is applied and approximately forty-two percent weight and cost savings are found by comparing the weight of various design scenarios together without showing any structural inadequacy.

  7. wall

    Directory of Open Access Journals (Sweden)

    Irshad Kashif

    2016-01-01

    Full Text Available Maintaining indoor climatic conditions of buildings compatible with the occupant comfort by consuming minimum energy, especially in a tropical climate becomes a challenging problem for researchers. This paper aims to investigate this problem by evaluating the effect of different kind of Photovoltaic Trombe wall system (PV-TW on thermal comfort, energy consumption and CO2 emission. A detailed simulation model of a single room building integrated with PV-TW was modelled using TRNSYS software. Results show that 14-35% PMV index and 26-38% PPD index reduces as system shifted from SPV-TW to DGPV-TW as compared to normal buildings. Thermal comfort indexes (PMV and PPD lie in the recommended range of ASHARE for both DPV-TW and DGPV-TW except for the few months when RH%, solar radiation intensity and ambient temperature were high. Moreover PVTW system significantly reduces energy consumption and CO2 emission of the building and also 2-4.8 °C of temperature differences between indoor and outdoor climate of building was examined.

  8. Sustainable wall construction and exterior insulation retrofit technology process and structure

    Science.gov (United States)

    Vohra, Arun

    2000-01-01

    A low-cost process for exterior wall insulation retrofit, or new wall construction by stacking layers of fabric tube filled with insulating material against a wall and covering them with mesh and stucco provides a durable structure with good insulating value.

  9. A typical wave wake from high-speed vessels: its group structure and run-up

    Directory of Open Access Journals (Sweden)

    I. Didenkulova

    2013-02-01

    Full Text Available High-amplitude water waves induced by high-speed vessels are regularly observed in Tallinn Bay, the Baltic Sea, causing intense beach erosion and disturbing marine habitants in the coastal zone. Such a strong impact on the coast may be a result of a certain group structure of the wave wake. In order to understand it, here we present an experimental study of the group structure of these wakes at Pikakari beach, Tallinn Bay. The most energetic vessel waves at this location (100 m from the coast at the water depth 2.7 m have amplitudes of about 1 m and periods of 8–10 s and cause maximum run-up heights on a beach up to 1.4 m. These waves represent frequency modulated packets where the largest and longest waves propagate ahead of other smaller amplitude and period waves. Sometimes the groups of different heights and periods can be separated even within one wave wake event. The wave heights within a wake are well described by the Weibull distribution, which has different parameters for wakes from different vessels. Wave run-up heights can also be described by Weibull distribution and its parameters can be connected to the parameters of the distribution of wave heights 100 m from the coast. Finally, the run-up of individual waves within a packet is studied. It is shown that the specific structure of frequency modulated wave packets, induced by high-speed vessels, leads to a sequence of high wave run-ups at the coast, even when the original wave heights are rather moderate. This feature can be a key to understanding the significant impact on coasts caused by fast vessels.

  10. Structural basis of cell wall cleavage by a staphylococcal autolysin.

    Directory of Open Access Journals (Sweden)

    Sebastian Zoll

    2010-03-01

    Full Text Available The major autolysins (Atl of Staphylococcus epidermidis and S. aureus play an important role in cell separation, and their mutants are also attenuated in virulence. Therefore, autolysins represent a promising target for the development of new types of antibiotics. Here, we report the high-resolution structure of the catalytically active amidase domain AmiE (amidase S. epidermidis from the major autolysin of S. epidermidis. This is the first protein structure with an amidase-like fold from a bacterium with a gram-positive cell wall architecture. AmiE adopts a globular fold, with several alpha-helices surrounding a central beta-sheet. Sequence comparison reveals a cluster of conserved amino acids that define a putative binding site with a buried zinc ion. Mutations of key residues in the putative active site result in loss of activity, enabling us to propose a catalytic mechanism. We also identified and synthesized muramyltripeptide, the minimal peptidoglycan fragment that can be used as a substrate by the enzyme. Molecular docking and digestion assays with muramyltripeptide derivatives allow us to identify key determinants of ligand binding. This results in a plausible model of interaction of this ligand not only for AmiE, but also for other PGN-hydrolases that share the same fold. As AmiE active-site mutations also show a severe growth defect, our findings provide an excellent platform for the design of specific inhibitors that target staphylococcal cell separation and can thereby prevent growth of this pathogen.

  11. Analysis of advanced thin-walled composite structures

    Science.gov (United States)

    Badir, Ashraf M.

    1992-11-01

    The use of fiber reinforced composites is increasing in engineering applications. One of the major issues is composite structures in the understanding of the role of the material's anisotropy on the deformation modes, damage modes and failure mechanisms. This research work addresses these stiffness and strength related issues by developing analytical models for the prediction of deformation modes and their coupling effects and damage onset and growth in laminated composites. Accurate prediction of stiffness, response, damage modes and failure mechanisms is bound to lead to the design of efficient and damage tolerant composite structures. In the first part of this work shear deformation models including hygrothermal effects are developed for the analysis of mid-plane edge delamination and local delamination originating from transverse cracks in 90 degree plies. The results of these models are combined with a previously developed shear deformation model for mixed-mode edge delamination to yield a unified analysis of delamination and the ability to identify the critical failure modes and loads. In the second part, a variationally and asymptotically consistent theory for thin-walled beams that incorporates the anisotropy associated with laminated composites is developed. The theory is based on an asymptotical analysis of 2D shell energy.

  12. Multi-atlas pancreas segmentation: Atlas selection based on vessel structure.

    Science.gov (United States)

    Karasawa, Ken'ichi; Oda, Masahiro; Kitasaka, Takayuki; Misawa, Kazunari; Fujiwara, Michitaka; Chu, Chengwen; Zheng, Guoyan; Rueckert, Daniel; Mori, Kensaku

    2017-07-01

    Automated organ segmentation from medical images is an indispensable component for clinical applications such as computer-aided diagnosis (CAD) and computer-assisted surgery (CAS). We utilize a multi-atlas segmentation scheme, which has recently been used in different approaches in the literature to achieve more accurate and robust segmentation of anatomical structures in computed tomography (CT) volume data. Among abdominal organs, the pancreas has large inter-patient variability in its position, size and shape. Moreover, the CT intensity of the pancreas closely resembles adjacent tissues, rendering its segmentation a challenging task. Due to this, conventional intensity-based atlas selection for pancreas segmentation often fails to select atlases that are similar in pancreas position and shape to those of the unlabeled target volume. In this paper, we propose a new atlas selection strategy based on vessel structure around the pancreatic tissue and demonstrate its application to a multi-atlas pancreas segmentation. Our method utilizes vessel structure around the pancreas to select atlases with high pancreatic resemblance to the unlabeled volume. Also, we investigate two types of applications of the vessel structure information to the atlas selection. Our segmentations were evaluated on 150 abdominal contrast-enhanced CT volumes. The experimental results showed that our approach can segment the pancreas with an average Jaccard index of 66.3% and an average Dice overlap coefficient of 78.5%. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. The device ``Klyost'' for clipping vessels and soft-elastic tubular structures

    Science.gov (United States)

    Ryklina, E. P.; Khmelevskaya, I. Yu.; Prokoshkin, S. D.; Ipatkin, R. V.

    2003-10-01

    A retrospect of earlier elaborated devices applying in clinical practice is presented. A newly invented device for clipping vessels and soft-elastic tubular structures is presented. Traditionally in surgical practice, to stop a blood flow, the surgeons use suturing of vessels (legate) with a silk thread. In laparoscopic surgery this process is accompanied with great difficulties. An alternative method of clipping vessels and structures is also used. The negative feature of this method is that the structure must be first mobilized. Up for to-day there is no device allowing to combine in one method both manipulations: suturing of tissue and laying a clip on a structure. The paper describes the new device, allowing to combine the oversaid manipulations and consequently to simplify the work of the surgeon and shorten the operation time. The device functioning is based on one-way and two-way shape memory effects. The device was applied in treating of 5 patients and manifested fine functional possibilities. The implanted clip can be easily evacuated without any patient trauma.

  14. Efficacy and quality of vessel sealing: comparison of a reusable with a disposable device and effects of clamp surface geometry and structure.

    Science.gov (United States)

    Richter, S; Kollmar, O; Schilling, M K; Pistorius, G A; Menger, M D

    2006-06-01

    During the past few years, a variety of energy-based techniques for vessel ligation have been introduced. With the use of a porcine model and different devices for bipolar vessel sealing (BiClamp and LigaSure), we studied the impact of different clamp surface structures on the efficacy and quality of vessel sealing. Eight Swabian Hall pigs underwent splenectomy, nephrectomy, salpingo-oophorectomy, and small bowel resection with the use of bipolar vessel sealing devices designed for open and laparoscopic surgery. Vessel sealing with clamps with a smooth (nonstructured) surface (BiClamp for open surgery and LigaSure for laparoscopic surgery) was compared to that of clamps with a structured (grooved, wafer-like) surface (BiClamp for laparoscopic surgery and LigaSure for open surgery). Measurements of sealed vessels (2- to 7-mm diameter) included the seal failure rate, instrument sticking, and heat-associated morphological vascular wall alterations. Analysis of seal failures did not reveal significant differences between the different devices for both open [BiClamp, 17.9% (17/95); LigaSure, 15.5% (11/71)] and laparoscopic surgery [BiClamp, 2.8% (1/36); LigaSure, 8.6% (3/35)]. Comparing all data of structured versus smooth clamp surfaces, the seal failure rate was lower using clamps with a structured (11.2%) compared to a smooth surface (15.4%). Instrument sticking and thermal spread were found to be significantly increased after sealing with structured surfaces, regardless of whether devices designed for open (p < 0.05 and p < 0.001, respectively) or laparoscopic surgery (p < 0.001 and p < 0.01, respectively) were used. Clamps with a structured surface seem to be superior to those with a smooth surface for successful bipolar vessel sealing, as indicated by an increase of thermal spread. However, the more pronounced instrument sticking represents an undesired side effect and should encourage the search for more inert materials to further improve the sealing procedure.

  15. Formation of three-dimensional cell/polymer constructs for bone tissue engineering in a spinner flask and a rotating wall vessel bioreactor

    Science.gov (United States)

    Sikavitsas, Vassilios I.; Bancroft, Gregory N.; Mikos, Antonios G.; McIntire, L. V. (Principal Investigator)

    2002-01-01

    The aim of this study is to investigate the effect of the cell culture conditions of three-dimensional polymer scaffolds seeded with rat marrow stromal cells (MSCs) cultured in different bioreactors concerning the ability of these cells to proliferate, differentiate towards the osteoblastic lineage, and generate mineralized extracellular matrix. MSCs harvested from male Sprague-Dawley rats were culture expanded, seeded on three-dimensional porous 75:25 poly(D,L-lactic-co-glycolic acid) biodegradable scaffolds, and cultured for 21 days under static conditions or in two model bioreactors (a spinner flask and a rotating wall vessel) that enhance mixing of the media and provide better nutrient transport to the seeded cells. The spinner flask culture demonstrated a 60% enhanced proliferation at the end of the first week when compared to static culture. On day 14, all cell/polymer constructs exhibited their maximum alkaline phosphatase activity (AP). Cell/polymer constructs cultured in the spinner flask had 2.4 times higher AP activity than constructs cultured under static conditions on day 14. The total osteocalcin (OC) secretion in the spinner flask culture was 3.5 times higher than the static culture, with a peak OC secretion occurring on day 18. No considerable AP activity and OC secretion were detected in the rotating wall vessel culture throughout the 21-day culture period. The spinner flask culture had the highest calcium content at day 14. On day 21, the calcium deposition in the spinner flask culture was 6.6 times higher than the static cultured constructs and over 30 times higher than the rotating wall vessel culture. Histological sections showed concentration of cells and mineralization at the exterior of the foams at day 21. This phenomenon may arise from the potential existence of nutrient concentration gradients at the interior of the scaffolds. The better mixing provided in the spinner flask, external to the outer surface of the scaffolds, may explain the

  16. Effects of Simulated Microgravity on Otolith Growth of Larval Zebrafish using a Rotating-Wall Vessel: Appropriate Rotation Speed and Fish Developmental Stage

    Science.gov (United States)

    Li, Xiaoyan; Anken, Ralf; Liu, Liyue; Wang, Gaohong; Liu, Yongding

    2017-02-01

    Stimulus dependence is a general feature of developing animal sensory systems. In this respect, it has extensively been shown earlier that fish inner ear otoliths can act as test masses as their growth is strongly affected by altered gravity such as hypergravity obtained using centrifuges, by (real) microgravity achieved during spaceflight or by simulated microgravity using a ground-based facility. Since flight opportunities are scarce, ground-based simulators of microgravity, using a wide variety of physical principles, have been developed to overcome this shortcoming. Not all of them, however, are equally well suited to provide functional weightlessness from the perspective of the biosystem under evaluation. Therefore, the range of applicability of a particular simulator has to be extensively tested. Earlier, we have shown that a Rotating-Wall Vessel (RWV) can be used to provide simulated microgravity for developing Zebrafish regarding the effect of rotation on otolith development. In the present study, we wanted to find the most effective speed of rotation and identify the appropriate developmental stage of Zebrafish, where effects are the largest, in order to provide a methodological basis for future in-depth analyses dedicated to the physiological processes underlying otolith growth at altered gravity. Last not least, we compared data on the effect of simulated microgravity on the size versus the weight of otoliths, since the size usually is measured in related studies due to convenience, but the weight more accurately approximates the physical capacity of an otolith. Maintaining embryos at 10 hours post fertilization for three days in the RWV, we found that 15 revolutions per minute (rpm) yielded the strongest effects on otolith growth. Maintenance of Zebrafish staged at 10 hpf, 1 day post fertilization (dpf), 4 dpf, 7 dpf and 14 dpf for three days at 15 rpm resulted in the most prominent effects in 7 dpf larvae. Weighing versus measuring the size of otoliths

  17. Recertification of the air and methane storage vessels at the Langley 8-foot high-temperature structures tunnel

    Science.gov (United States)

    Hudson, C. M.; Girouard, R. L.; Young, C. P., Jr.; Petley, D. H.; Hudson, J. L., Jr.; Hudgins, J. L.

    1977-01-01

    This center operates a number of sophisticated wind tunnels in order to fulfill the needs of its researchers. Compressed air, which is kept in steel storage vessels, is used to power many of these tunnels. Some of these vessels have been in use for many years, and Langley is currently recertifying these vessels to insure their continued structural integrity. One of the first facilities to be recertified under this program was the Langley 8-foot high-temperature structures tunnel. This recertification involved (1) modification, hydrotesting, and inspection of the vessels; (2) repair of all relevant defects; (3) comparison of the original design of the vessel with the current design criteria of Section 8, Division 2, of the 1974 ASME Boiler and Pressure Vessel Code; (4) fracture-mechanics, thermal, and wind-induced vibration analyses of the vessels; and (5) development of operating envelopes and a future inspection plan for the vessels. Following these modifications, analyses, and tests, the vessels were recertified for operation at full design pressure (41.4 MPa (6000 psi)) within the operating envelope developed.

  18. Structural Remodeling of Sympathetic Innervation in Atherosclerotic Blood Vessels: Role of Atherosclerotic Disease Progression and Chronic Social Stress.

    Science.gov (United States)

    Noller, Crystal M; Mendez, Armando J; Szeto, Angela; Boulina, Marcia; Llabre, Maria M; Zaias, Julia; Schneiderman, Neil; McCabe, Philip M

    2017-01-01

    The sympathetic nervous system (SNS) can undergo dramatic structural plasticity in response to behavioral factors and/or the presence of disease, leading to SNS hyperinnervation of peripheral tissues. The SNS has been proposed as an important mediator between stressful behavior and the progression of atherosclerosis in the vasculature. The present study examined whether structural remodeling of the SNS occurs in the vasculature in a genetically hyperlipidemic animal model of atherosclerosis, the Watanabe heritable hyperlipidemic rabbit (WHHL; relative to normolipidemic New Zealand white rabbits [NZW]), and whether SNS plasticity is driven by the progression of disease and/or by stressful social behavior. WHHL and NZW rabbits were assigned to an unstable or stable social environment for 4 months. Aortic atherosclerosis was assessed and SNS aortic innervation quantified using immunofluorescent microscopy. Numerous SNS varicosities were observed throughout the aorta in WHHLs and NZWs, extending into the vascular media and intima, an innervation pattern not previously reported. WHHLs exhibited significantly greater innervation than NZWs (F(1,41) = 55.3, p Social environment did not influence innervation in NZWs (aortic arch: p = .078, thoracic aorta: p = .34) or WHHLs (arch: p = .97, thoracic: p = .61). The findings suggest that hyperinnervation is driven largely by the progression of disease rather than social environment. SNS innervation patterns observed in atherosclerotic human and mouse aortas were consistent with the rabbit, suggesting that SNS hyperinnervation of the diseased vessel wall is a general feature across mammalian species.

  19. [A quantitative study of the structural anomalies in the pulmonary vessels by pulmonary biopsy in children with an interventricular communication].

    Science.gov (United States)

    Torán, N; Reig, J; Rovirosa, M; Ruiz de Miguel, M C; Lozano, C

    1995-01-01

    Pulmonary vascular disease occurs in patients with cardiac anomalies and left to right shunt as the cases of interventricular heart defects. The hemodynamic study of the structural changes and their relationship with the pathological lesions are useful to know the state of the pulmonary vessels and to establish the postsurgical patients outcome. We analyzed the morphologic and morphometric data in 17 lung biopsies from children under three years with ventricular septal defect, focused the histologic study in grading the structural changes of the intima, media and adventitial vascular walls and the morphometric evaluation on the thickening of the media and the number of the intracinar arteries. There are significant statistical correlation among the pulmonary pressure and the age, the vascular resistances and the age, the cocient between the pulmonary arterial pressure and the systemic pressure and the external vascular diameter, the cocient of the pulmonary and systemic fluxes and the thickening of the media and finally between the pulmonary vascular resistances and the external arterial diameter. Our results suggest that the intracardiac repair is desirable within 6 months of life and lung biopsy should be undertaken because is the only way to determine the medial thickening and his muscular of fibrous proliferation that will clarify the post-surgical patients outcome.

  20. The structure of the mycelial wall of Agaricus bisporus.

    Science.gov (United States)

    Novaes-Ledieu, M; Martínez Cobo, J A; García Mendoza, C

    1987-02-01

    The chemical composition of fractions extracted from the mycelial walls of Agaricus bisporus was studied. Attempts were made to locate these materials "in situ" by comparing electron micrographs of shadowed and sectioned cell walls. There are at least two chemically distinct species of carbohydrate polymers: one yielding mainly glucose with lower amounts of mannose, galactose and xylose and amino acids, and the other yielding chiefly N-acetylglucosamine with some glucose and amino acids. It was shown that none of these polymers constituted a completely physically distinct layer, but there do seem to be two regions at the outer and inner surfaces with apparently different properties. Materials which react with MnO4K to produce an electron-dense material are located throughout the wall, but tend to be concentrated in the outer and inner regions. It was shown that fibers constitute one important fraction of the original wall material.

  1. In-vessel calibration of the imaging diagnostics for the real-time protection of the JET ITER-like wall

    Energy Technology Data Exchange (ETDEWEB)

    Huber, V., E-mail: V.Huber@fz-juelich.de [Forschungszentrum Jülich GmbH, Supercomputing Centre, 52425 Jülich (Germany); Huber, A.; Mertens, Ph.; Sergienko, G. [Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung—Plasmaphysik, Partner of the Trilateral Euregio Cluster (TEC), 52425 Jülich (Germany); Kinna, D.; Balboa, I.; Collins, S.; Conway, N.; Maggi, C. F.; Matthews, G. F.; Meigs, A. G.; Price, M.; Silburn, S.; Zastrow, K.-D. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Drewelow, P. [MPI für Plasmaphysik, Greifswald (Germany); Wynn, A. [York Plasma Institute, University of York, Heslington, York YO10 5DD (United Kingdom)

    2016-11-15

    The in situ absolute calibration of the JET real-time protection imaging system has been performed for the first time by means of radiometric light source placed inside the JET vessel and operated by remote handling. High accuracy of the calibration is confirmed by cross-validation of the near infrared (NIR) cameras against each other, with thermal IR cameras, and with the beryllium evaporator, which lead to successful protection of the JET first wall during the last campaign. The operation temperature ranges of NIR protection cameras for the materials used on JET are Be 650-1600 °C, W coating 600-1320 °C, and W 650-1500 °C.

  2. Evaluation of thermal protection structure mechanism of LMR reactor vessels and design improvement for thermal stress reduction

    Energy Technology Data Exchange (ETDEWEB)

    Joo, Young Sang; Koo, Gyeong Hoi; Kim, Jong Bum; Kim, Seok Hun; Lee, Jae Han

    2003-03-01

    LMR reactor vessels operated in high temperature have a severe thermal damage due to the significant temperature gradient in the hot pool free surface regions of reactor vessel. The thermal protection mechanism of LMR reactor vessel should be designed for the structural integrity in high temperature condition. In this study, the thermal protection mechanism of foreign LMR reactor vessels is investigated for the power upgrade of KALIMER and the modified reactor baffle design with a Y-piece type structure is proposed for the reduction of thermal damage for KALIMER reactor vessel. The modified reactor baffle design leads to reduce the thermal damage such as creep-fatigue and ratcheting in the transient operation condition.

  3. Experimental and theoretical studies on concrete structures with special-shaped shear walls

    Directory of Open Access Journals (Sweden)

    LIU Jianxin

    2014-06-01

    Full Text Available On the basis of concept design and staggered shear panels structure,this paper puts forward a new reinforced concrete high rise biuding structure with special-shaped shear walls and presents an experimental study of the seismic performance of the new special-shaped shear walls structure under low reversed cyclic loading using MTS electro hydraulic servo system.Compared with experimental results,a finite element analysis on this special-shaped shear wall structure,which considers the nonlinearity of concrete structure,is found suitable.It shows that the experimental results fairly confirms to the calculated values,which indicates that this new structure has advantages as good architecture function,big effective space,high overall lateral stiffness,fine ductility,advanced seismic behavior,etc..That is,the close r agreement between the theoretical and experimental results indicates the proposed shear wall structure has wide applications.

  4. Lymphatic endothelium forms integrin-engaging 3D structures during DC transit across inflamed lymphatic vessels.

    Science.gov (United States)

    Teijeira, Alvaro; Garasa, Saray; Peláez, Rafael; Azpilikueta, Arantza; Ochoa, Carmen; Marré, Diego; Rodrigues, Magda; Alfaro, Carlos; Aubá, Cristina; Valitutti, Salvatore; Melero, Ignacio; Rouzaut, Ana

    2013-09-01

    Dendritic cell (DC) transmigration across the lymphatic endothelium is critical for the initiation and sustenance of immune responses. Under noninflammatory conditions, DC transit across the lymphatic endothelial cell (LEC) has been shown to be integrin independent. In contrast, there is increasing evidence for the participation of integrins and their ligands in DC transit across lymphatic endothelium under inflammation. In this sense, we describe the formation of ICAM-1 (CD54)-enriched three-dimensional structures on LEC/DC contacts, as these DCs adhere to inflamed skin lymphatic vessels and transmigrate into them. In vitro imaging revealed that under inflammation ICAM-1 accumulated on microvilli projections surrounding 60% of adhered DCs. In contrast, these structures were scarcely formed in noninflammatory conditions. Furthermore, ICAM-1-enriched microvilli were important in promoting DC transendothelial migration and DC crawling over the LEC surface. Microvilli formation was dependent on the presence of β-integrins on the DC side and on integrin conformational affinity to ligand. Finally, we observed that LEC microvilli structures appeared in close vicinity of CCL21 depots and that their assembly was partially inhibited by CCL21-neutralizing antibodies. Therefore, under inflammatory conditions, integrin ligands form three-dimensional membrane projections around DCs. These structures offer docking sites for DC transit from the tissue toward the lymphatic vessel lumen.

  5. Whole-brain vessel wall MRI: A parameter tune-up solution to improve the scan efficiency of three-dimensional variable flip-angle turbo spin-echo.

    Science.gov (United States)

    Yang, Qi; Deng, Zixin; Bi, Xiaoming; Song, Shlee S; Schlick, Konrad H; Gonzalez, Nestor R; Li, Debiao; Fan, Zhaoyang

    2017-09-01

    To propose and evaluate a parameter tune-up solution to expedite a three-dimensional (3D) variable-flip-angle turbo spin-echo (TSE) sequence for whole-brain intracranial vessel wall (IVW) imaging. Elliptical k-space sampling and prolonged echo train length (ETL), were used to expedite a 3D variable-flip-angle TSE-based sequence. To compensate for the potential loss in vessel wall signal, optimal combination of prescribed T 2 and ETL was experimentally investigated on 22 healthy volunteers at 3 Tesla. The optimized protocol (7-8 min) was then compared with a previous protocol (reference protocol, 11-12 min) in terms of signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), vessel wall sharpness, and wall delineation quality on a 4-point scale (0:poor; 3:excellent) in 10 healthy volunteers. A pilot study of five patients was performed and lesion delineation score was used to demonstrate the diagnostic quality. A protocol with ETL = 52 and prescribed T 2  = 170 ms was deemed an optimized one, which, compared with the reference protocol, provided significantly improved wall SNR (12.0 ± 1.3 versus 10.0 ± 1.1; P = 0.002), wall-lumen CNR (9.7 ± 1.2 versus 8.0 ± 0.9; P = 0.002), wall-CSF CNR (2.8 ± 1.0 versus 1.7 ± 1.0; P = 0.026), similar vessel wall sharpness at both inner (1.59 ± 0.18 versus 1.58 ± 0.14, P = 0.87) and outer (1.71 ± 0.25 versus 1.83 ± 0.30; P = 0.18) boundaries, and comparable vessel wall delineation score for individual segments (1.95-3; P > 0.06). In all patients, atherosclerotic plaques (10) or wall dissection (5) were identified with a delineation score of 3 or 2. A parameter tune-up solution can accelerate 3D variable-flip-angle TSE acquisitions, particularly allowed for expedited whole-brain IVW imaging with preserved wall delineation quality. 2. Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:751-757. © 2017 International Society for Magnetic

  6. An experimental study of hypervapotron structure in external reactor vessel cooling

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yufeng; Zhang, Ming [State Nuclear Power Technology R& D Center (Beijing), Beijing (China); Hou, Fangxin [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing (China); Gao, Tianfang [State Nuclear Power Technology R& D Center (Beijing), Beijing (China); Chen, Peipei, E-mail: chenpeipei@snptc.com.cn [State Power Investment Group Corporation, Beijing (China)

    2016-07-15

    Highlights: • Experiments are performed to study the application of hypervapotron in ERVC design. • CHF experiments on two surfaces are conducted under different flow conditions. • Hypervapotron improves CHF performance by 40–60% compared with smooth surface. • Visualization shows fin structure removes vapor mushroom for better liquid supply. - Abstract: In vessel retention (IVR) is one of the key strategies for many advanced LWR designs to mitigate postulated severe accidents. The success of IVR substantially relies on external reactor vessel cooling (ERVC) by which the decay heat is removed from the melt core in the reactor vessel lower head. The main challenge of IVR is to provide an adequate safety margin of ERVC against critical heat flux (CHF) of subcooled flow boiling in the reactor lower head flow channel. Due to uncertainties in corium melt pool configuration, large CHF margin of ERVC is usually required by regulatory authorities to demonstrate reliability of severe accident mitigation methods. Various CHF enhancement designs have been proposed and studied in literature. In this paper, an experimental study of hypervapotron structure as a novel design to improve CHF performance of ERVC is conducted. Hypervapotron is chosen as one of the potential engineering options for International Thermonuclear Experimental Reactor (ITER) program as a divertor structure to remove highly intense heat from fusion chamber. This study is to conduct CHF experiments at typical PWR ERVC working conditions. The CHF experiments are performed in a 30 mm by 61 mm rectangular flow channel with a 200 mm long heated surface along the flow direction. Both smooth and hypervapotron surface are tested at various inclination angles of the test section to simulate various positions of the reactor lower head. The hypervapotron is found to have a 40–60% CHF improvement compared with the smooth surface. The high speed visualization indicates that hypervapotron is able to

  7. Seismic strengthening of RC structures with exterior shear walls

    Indian Academy of Sciences (India)

    research efforts in this field have shifted their focus to new methods that could overcome this difficulty. The precast panel infill ... the sides of the buildings to be unobstructed for installation of new shear walls. The literature review presents ..... Seismic design of bridge piers. Research report 84-2, Christchurch (New Zealand),.

  8. An enzymatic approach to cell wall structure | Hungate | South ...

    African Journals Online (AJOL)

    ... digested to a somewhat greater extent (88%) than were the fermentable sugars of the hemicellulose fraction (62- 76%). The digestibility of the total insoluble alfalfa cell wall, including lignin but not material solubilized during heat sterilization, was 66%. A cellulase, a-arabinosidase and xylanase were partially purified from ...

  9. Application of manufacturing constraints to structural optimization of thin-walled structures

    Science.gov (United States)

    Kuczek, T.

    2016-02-01

    Topology optimization can be a very useful tool for creating conceptual designs for vehicles. Structures suggested by topology optimization often turn out to be difficult to implement in manufacturing processes. Presently, rail vehicle structures are made by welding sheet metal parts. This leads to many complications and increased weight of the vehicle. This article presents a new design concept for modern rail vehicle structures made of standardized, thin-walled, closed, steel profiles that fulfil the stress and manufacturing requirements. For this purpose, standard software for topology optimization was used with a new way of preprocessing the design space. The design methodology is illustrated by an example of the topology optimization of a freight railcar. It is shown that the methodology turns out to be a useful tool for obtaining optimal structure design that fulfils the assumed manufacturing constraints.

  10. Pea border cell maturation and release involve complex cell wall structural dynamics

    DEFF Research Database (Denmark)

    Mravec, Jozef; Guo, Xiaoyuan; Hansen, Aleksander Riise

    2017-01-01

    of hydrolytic activities, transmission electron microscopy (TEM) and immunolocalization of cell wall components. Using this integrated glycobiology approach, we identified multiple novel modes of cell wall structural and compositional rearrangement during root cap growth and the release of border cells. Our...

  11. Cell Walls of Wood, Composition, Structure and a few Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Florentina Adriana Cziple

    2008-10-01

    Full Text Available The objective of this paper was to investigate the effect between the chemical composition, molecular architecture and structure cell walls of wood and the mechanical properties of wood. Cell walls function as the major mechanical restraint that determines plant cell size and morphology.

  12. Leukoaraiosis is associated with arterial wall thickness: a quantitative analysis.

    Science.gov (United States)

    Auriel, Eitan; Csiba, Laszlo; Berenyi, Ervin; Varkonyi, Ildiko; Mehes, Gabor; Kardos, Laszlo; Karni, Arnon; Bornstein, Natan M

    2012-06-01

    Leukoaraiosis refers to an age-related, abnormal appearance of the brain white matter on neuroimaging. The association between leukoaraiosis and cerebrovascular disease suggests that ischemia may be an important contributing factor; however, the pathogenesis of the condition remains controversial. We hypothesized that physical abnormalities of blood vessels might be culpable and compared the external and internal measurements of blood vessel walls between brains that demonstrated leukoaraiosis on imaging and normal control brains. Fourteen brains of individuals who had been diagnosed as having severe leukoaraiosis and five non-leukoaraiosis control brains were studied. Arterial cross-sections were evaluated by length measurements with an image analysis device. Arterial wall thickness and the ratio of the outer and inner diameters of the vessel were measured. We measured a total of 108 vessels in the leukoaraiosis group and 95 vessels in the control group. The vessel walls of the leukoaraiosis patients were an average of 5.5 µm thicker than the walls of control vessels of the same inside diameter (P = 0.0000, 95% CI 3.01-8.08) and an average of 2.3 µm thicker than walls of control vessels of the same outside diameter (P = 0.016, 95% CI 0.48-4.17). Our data provide evidence that leukoaraiosis is associated with vessel wall thickening in an additive fashion and indicate that structural vascular abnormalities are associated with leukoaraiosis. © 2011 Japanese Society of Neuropathology.

  13. Structure reconstruction of TiO2-based multi-wall nanotubes: first-principles calculations.

    Science.gov (United States)

    Bandura, A V; Evarestov, R A; Lukyanov, S I

    2014-07-28

    A new method of theoretical modelling of polyhedral single-walled nanotubes based on the consolidation of walls in the rolled-up multi-walled nanotubes is proposed. Molecular mechanics and ab initio quantum mechanics methods are applied to investigate the merging of walls in nanotubes constructed from the different phases of titania. The combination of two methods allows us to simulate the structures which are difficult to find only by ab initio calculations. For nanotube folding we have used (1) the 3-plane fluorite TiO2 layer; (2) the anatase (101) 6-plane layer; (3) the rutile (110) 6-plane layer; and (4) the 6-plane layer with lepidocrocite morphology. The symmetry of the resulting single-walled nanotubes is significantly lower than the symmetry of initial coaxial cylindrical double- or triple-walled nanotubes. These merged nanotubes acquire higher stability in comparison with the initial multi-walled nanotubes. The wall thickness of the merged nanotubes exceeds 1 nm and approaches the corresponding parameter of the experimental patterns. The present investigation demonstrates that the merged nanotubes can integrate the two different crystalline phases in one and the same wall structure.

  14. Wall-attached structures of streamwise velocity fluctuations in turbulent boundary layer

    Science.gov (United States)

    Hwang, Jinyul; Sung, Hyung Jin

    2017-11-01

    The wall-attached structures of streamwise velocity fluctuations (u) are explored using direct numerical simulation data of turbulent boundary layer at Reτ = 1000 . We identify the structures of u, which are extended close to the wall. Their height (ly) ranges from the near-wall region to the edge of turbulent boundary layer. They are geometrically self-similar in a sense that the length and width of the structures are proportional to the distance from the wall. The population density of the attached structures shows that the tall attached structures (290 attached eddies addressed by Perry and coworkers. The streamwise turbulent intensity of these tall attached structures follows the logarithmic distribution with the distance from the wall. The wall-attached structures of u identified in the present work are a proper candidate for Townsend's attached eddy hypothesis and these structures exist in the low Reynolds number turbulent boundary layer. This work was supported by the Creative Research Initiatives (No. 2017-013369) program of the National Research Foundation of Korea (MSIP) and supported by the Supercomputing Center (KISTI).

  15. Breast arterial calcification and risk of carotid atherosclerosis: Focusing on the preferentially affected layer of the vessel wall

    Energy Technology Data Exchange (ETDEWEB)

    Sedighi, Nahid, E-mail: nsedighi@sina.tums.ac.ir [Department of Radiology, Shariati Hospital, Tehran University of Medical Sciences. North Kargar Ave., Tehran 14114 (Iran, Islamic Republic of); Radmard, Amir Reza, E-mail: radmard@ams.ac.ir [Department of Radiology, Shariati Hospital, Tehran University of Medical Sciences. North Kargar Ave., Tehran 14114 (Iran, Islamic Republic of); Radmehr, Ali, E-mail: radmehr@sina.tums.ac.ir [Department of Radiology, Shariati Hospital, Tehran University of Medical Sciences. North Kargar Ave., Tehran 14114 (Iran, Islamic Republic of); Hashemi, Pari, E-mail: phtums@yahoo.com [Department of Radiology, Shariati Hospital, Tehran University of Medical Sciences. North Kargar Ave., Tehran 14114 (Iran, Islamic Republic of); Hajizadeh, Abdolmahmoud, E-mail: mroomezi@yahoo.com [Department of Radiology, Shariati Hospital, Tehran University of Medical Sciences. North Kargar Ave., Tehran 14114 (Iran, Islamic Republic of); Taheri, Amir Pejman Hashemi, E-mail: hashemip@sina.tums.ac.ir [Department of Radiology, Shariati Hospital, Tehran University of Medical Sciences. North Kargar Ave., Tehran 14114 (Iran, Islamic Republic of)

    2011-08-15

    Objective: To assess the relationship between breast arterial calcification (BAC) detected on screening mammography and atherosclerosis of carotid arteries considering the most likely involved layer of the arterial wall. Materials and methods: A total of 537 consecutive women who underwent screening mammography were enrolled in this study. Seventy-nine subjects having BAC, aged 46-75 years, and 125 age-matched controls from those without BAC were selected for ultrasound examination of carotid arteries assessing intima-media thickness (IMT) and plaque presence. Participants were divided into three groups of risk including, low-risk: IMT < 0.6 mm without plaque, medium-risk: 0.6 mm {<=} IMT {<=} 0.8 mm without plaque and high-risk: IMT > 0.8 mm and/or plaque. Risk factors for atherosclerosis were obtained from medical records for independent effects. Results: BAC was present in 14.7% of mammograms. According to multivariable logistic regression analyses, significant association was identified between the carotid atherosclerosis risk and presence of BAC. Compared to women with IMT < 0.6 mm, those with 0.6 mm {<=} IMT{<=} 0.8 mm and IMT > 0.8 mm had OR (95% CI) of 4.88 (1.47-16.16) and 23.36 (4.54-120.14), respectively. The OR (95% CI) for carotid plaque was 3.13 (1.3-7.57). There was no interaction between IMT category and plaque. Significant associations were also detected with postmenopausal duration (P = 0.02) and hypertension (P = 0.004). Conclusion: The risk of carotid atherosclerosis increases with the presence of BAC. Women with BAC are more likely to have thicker IMT than plaque, which could be attributed to the preferentially similar affected layer of media causing thick IMT rather than plaque.

  16. Classification of Vessels in Single-Pol COSMO-SkyMed Images Based on Statistical and Structural Features

    Directory of Open Access Journals (Sweden)

    Fan Wu

    2015-05-01

    Full Text Available Vessel monitoring is one of the most important maritime applications of Synthetic Aperture Radar (SAR data. Because of the dihedral reflections between the vessel hull and sea surface and the trihedral reflections among superstructures, vessels usually have strong backscattering in SAR images. Furthermore, in high-resolution SAR images, detailed information on vessel structures can be observed, allowing for vessel classification in high-resolution SAR images. This paper focuses on the feature analysis of merchant vessels, including bulk carriers, container ships and oil tankers, in 3 m resolution COSMO-SkyMed stripmap HIMAGE mode images and proposes a method for vessel classification. After preprocessing, a feature vector is estimated by calculating the average value of the kernel density estimation, three structural features and the mean backscattering coefficient. Support vector machine (SVM classifier is used for the vessel classification, and the results are compared with traditional methods, such as the K-nearest neighbor algorithm (K-NN and minimum distance classifier (MDC. In situ investigations are conducted during the SAR data acquisition. Corresponding Automatic Identification System (AIS reports are also obtained as ground truth to evaluate the effectiveness of the classifier. The preliminary results show that the combination of the average value of the kernel density estimation and mean backscattering coefficient has good ability for classifying the three types of vessels. When adding the three structural features, the results slightly improve. The result of the SVM classifier is better than that of K-NN and MDC. However, the SVM requires more time, when the parameters of the kernel are estimated.

  17. Advanced Image Enhancement Method for Distant Vessels and Structures in Capsule Endoscopy

    Science.gov (United States)

    Pedersen, Marius

    2017-01-01

    This paper proposes an advanced method for contrast enhancement of capsule endoscopic images, with the main objective to obtain sufficient information about the vessels and structures in more distant (or darker) parts of capsule endoscopic images. The proposed method (PM) combines two algorithms for the enhancement of darker and brighter areas of capsule endoscopic images, respectively. The half-unit weighted-bilinear algorithm (HWB) proposed in our previous work is used to enhance darker areas according to the darker map content of its HSV's component V. Enhancement of brighter areas is achieved thanks to the novel threshold weighted-bilinear algorithm (TWB) developed to avoid overexposure and enlargement of specular highlight spots while preserving the hue, in such areas. The TWB performs enhancement operations following a gradual increment of the brightness of the brighter map content of its HSV's component V. In other words, the TWB decreases its averaged weights as the intensity content of the component V increases. Extensive experimental demonstrations were conducted, and, based on evaluation of the reference and PM enhanced images, a gastroenterologist (Ø.H.) concluded that the PM enhanced images were the best ones based on the information about the vessels, contrast in the images, and the view or visibility of the structures in more distant parts of the capsule endoscopy images. PMID:29225668

  18. Power Efficiency of Systems Applied for Heating Building and Structure External Walls with Ventilated Air Spaces

    OpenAIRE

    I. F. Fialko; A. S. Statsenko

    2009-01-01

    The paper considers power-efficient systems applied for heating building and structure external walls with ventilated air spaces and prescribes directions and problems pertaining to power-efficiency improvement of such systems.

  19. Preliminary Structural Design of Wall-Frame Systems for Optimum Torsional Response

    National Research Council Canada - National Science Library

    Georgoussis, George K

    ... to any strength assignment, is incorrect. A strength allocation strategy, suitable for preliminary structural design of medium height wall-frame dual systems, is presented for allocating strength in such buildings and estimating the dependable rigidities...

  20. Ignitor Vacuum Vessel Structural Design with Dynamic Loads Due to Plasma Disruption Event

    Science.gov (United States)

    Cucchiaro, Antonio; Crescenzi, Claudio; Mazzone, Giuseppe; Pizzuto, Aldo; Ramogida, Giuseppe; Roccella, Massimo; Bianchi, Aldo; Parodi, Bruno; Linari, Mauro; Lucca, Flavio; Marin, Anna; Coppi, Bruno

    2004-11-01

    The new reference plasma disruption for IGNITOR produces a significant increase of electromagnetic (EM) loads and requires a dynamic elastic-plastic structural analysis of the vacuum vessel (VV). The EM loads due to the worst disruption event (VDE) have been calculated using the MAXFEA 2D code and it is found that the stresses and deformation that would be produced on a relatively thin chamber could be excessive. A varying thickness configuration for the VV has been adopted on the basis of a step by step optimization with the aim of minimizing the vertical displacement while complying with the allowable plastic strains. A non-linear analysis is required with a modelling of the entire (360°) VV structure. With the new thickness distribution, the VV is capable to withstand several hundred of cycles under plasma disruption conditions in compliance with the ASME III code rules.

  1. Stomatal cell wall composition: distinctive structural patterns associated with different phylogenetic groups

    Science.gov (United States)

    Shtein, Ilana; Shelef, Yaniv; Marom, Ziv; Zelinger, Einat; Schwartz, Amnon; Popper, Zoë A.; Bar-On, Benny

    2017-01-01

    Background and Aims Stomatal morphology and function have remained largely conserved throughout ∼400 million years of plant evolution. However, plant cell wall composition has evolved and changed. Here stomatal cell wall composition was investigated in different vascular plant groups in attempt to understand their possible effect on stomatal function. Methods A renewed look at stomatal cell walls was attempted utilizing digitalized polar microscopy, confocal microscopy, histology and a numerical finite-elements simulation. The six species of vascular plants chosen for this study cover a broad structural, ecophysiological and evolutionary spectrum: ferns (Asplenium nidus and Platycerium bifurcatum) and angiosperms (Arabidopsis thaliana and Commelina erecta) with kidney-shaped stomata, and grasses (angiosperms, family Poaceae) with dumbbell-shaped stomata (Sorghum bicolor and Triticum aestivum). Key Results Three distinct patterns of cellulose crystallinity in stomatal cell walls were observed: Type I (kidney-shaped stomata, ferns), Type II (kidney-shaped stomata, angiosperms) and Type III (dumbbell-shaped stomata, grasses). The different stomatal cell wall attributes investigated (cellulose crystallinity, pectins, lignin, phenolics) exhibited taxon-specific patterns, with reciprocal substitution of structural elements in the end-walls of kidney-shaped stomata. According to a numerical bio-mechanical model, the end walls of kidney-shaped stomata develop the highest stresses during opening. Conclusions The data presented demonstrate for the first time the existence of distinct spatial patterns of varying cellulose crystallinity in guard cell walls. It is also highly intriguing that in angiosperms crystalline cellulose appears to have replaced lignin that occurs in the stomatal end-walls of ferns serving a similar wall strengthening function. Such taxon-specific spatial patterns of cell wall components could imply different biomechanical functions, which in turn

  2. Stomatal cell wall composition: distinctive structural patterns associated with different phylogenetic groups.

    Science.gov (United States)

    Shtein, Ilana; Shelef, Yaniv; Marom, Ziv; Zelinger, Einat; Schwartz, Amnon; Popper, Zoë A; Bar-On, Benny; Harpaz-Saad, Smadar

    2017-04-01

    Stomatal morphology and function have remained largely conserved throughout ∼400 million years of plant evolution. However, plant cell wall composition has evolved and changed. Here stomatal cell wall composition was investigated in different vascular plant groups in attempt to understand their possible effect on stomatal function. A renewed look at stomatal cell walls was attempted utilizing digitalized polar microscopy, confocal microscopy, histology and a numerical finite-elements simulation. The six species of vascular plants chosen for this study cover a broad structural, ecophysiological and evolutionary spectrum: ferns ( Asplenium nidus and Platycerium bifurcatum ) and angiosperms ( Arabidopsis thaliana and Commelina erecta ) with kidney-shaped stomata, and grasses (angiosperms, family Poaceae) with dumbbell-shaped stomata ( Sorghum bicolor and Triticum aestivum ). Three distinct patterns of cellulose crystallinity in stomatal cell walls were observed: Type I (kidney-shaped stomata, ferns), Type II (kidney-shaped stomata, angiosperms) and Type III (dumbbell-shaped stomata, grasses). The different stomatal cell wall attributes investigated (cellulose crystallinity, pectins, lignin, phenolics) exhibited taxon-specific patterns, with reciprocal substitution of structural elements in the end-walls of kidney-shaped stomata. According to a numerical bio-mechanical model, the end walls of kidney-shaped stomata develop the highest stresses during opening. The data presented demonstrate for the first time the existence of distinct spatial patterns of varying cellulose crystallinity in guard cell walls. It is also highly intriguing that in angiosperms crystalline cellulose appears to have replaced lignin that occurs in the stomatal end-walls of ferns serving a similar wall strengthening function. Such taxon-specific spatial patterns of cell wall components could imply different biomechanical functions, which in turn could be a consequence of differences in

  3. Collapsible Cryogenic Storage Vessel Project

    Science.gov (United States)

    Fleming, David C.

    2002-01-01

    Collapsible cryogenic storage vessels may be useful for future space exploration missions by providing long-term storage capability using a lightweight system that can be compactly packaged for launch. Previous development efforts have identified an 'inflatable' concept as most promising. In the inflatable tank concept, the cryogen is contained within a flexible pressure wall comprised of a flexible bladder to contain the cryogen and a fabric reinforcement layer for structural strength. A flexible, high-performance insulation jacket surrounds the vessel. The weight of the tank and the cryogen is supported by rigid support structures. This design concept is developed through physical testing of a scaled pressure wall, and through development of tests for a flexible Layered Composite Insulation (LCI) insulation jacket. A demonstration pressure wall is fabricated using Spectra fabric for reinforcement, and burst tested under noncryogenic conditions. An insulation test specimens is prepared to demonstrate the effectiveness of the insulation when subject to folding effects, and to examine the effect of compression of the insulation under compressive loading to simulate the pressure effect in a nonrigid insulation blanket under the action atmospheric pressure, such as would be seen in application on the surface of Mars. Although pressure testing did not meet the design goals, the concept shows promise for the design. The testing program provides direction for future development of the collapsible cryogenic vessel concept.

  4. 3D rotating wall vessel and 2D cell culture of four veterinary virus pathogens: A comparison of virus yields, portions of infectious particles and virus growth curves.

    Science.gov (United States)

    Malenovská, Hana

    2016-02-01

    Only very few comparative studies have been performed that evaluate general trends of virus growth under 3D in comparison with 2D cell culture conditions. The aim of this study was to investigate differences when four animal viruses are cultured in 2D and 3D. Suid herpesvirus 1 (SuHV-1), Vesicular stomatitis virus (VSIV), Bovine adenovirus (BAdV) and Bovine parainfluenza 3 virus (BPIV-3) were cultivated in 3D rotating wall vessels (RWVs) and conventional 2D cultures. The production of virus particles, the portion of infectious particles, and the infectious growth curves were compared. For all viruses, the production of virus particles (related to cell density), including the non-infectious ones, was lower in 3D than in 2D culture. The production of only infectious particles was significantly lower in BAdV and BPIV-3 in 3D cultures in relation to cell density. The two cultivation approaches resulted in significantly different virus particle-to-TCID50 ratios in three of the four viruses: lower in SuHV-1 and BPIV-3 and higher in BAdV in 3D culture. The infectious virus growth rates were not significantly different in all viruses. Although 3D RWV culture resulted in lower production of virus particles compared to 2D systems, the portion of infectious particles was higher for some viruses. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. In Vivo Clearance of Alpha-1 Acid Glycoprotein Is Influenced by the Extent of Its N-Linked Glycosylation and by Its Interaction with the Vessel Wall

    Directory of Open Access Journals (Sweden)

    Teresa R. McCurdy

    2012-01-01

    Full Text Available Alpha-1 acid glycoprotein (AGP is a highly glycosylated plasma protein that exerts vasoprotective effects. We hypothesized that AGP’s N-linked glycans govern its rate of clearance from the circulation, and followed the disappearance of different forms of radiolabeled human AGP from the plasma of rabbits and mice. Enzymatic deglycosylation of human plasma-derived AGP (pdAGP by Peptide: N-Glycosidase F yielded a mixture of differentially deglycosylated forms (PNGase-AGP, while the introduction of five Asn to Gln mutations in recombinant Pichia pastoris-derived AGP (rAGP-N(5Q eliminated N-linked glycosylation. PNGase-AGP was cleared from the rabbit circulation 9-fold, and rAGP-N(5Q, 46-fold more rapidly than pdAGP, primarily via a renal route. Pichia pastoris-derived wild-type rAGP differed from pdAGP in expressing mannose-terminated glycans, and, like neuraminidase-treated pdAGP, was more rapidly removed from the rabbit circulation than rAGP-N(5Q. Systemic hyaluronidase treatment of mice transiently decreased pdAGP clearance. AGP administration to mice reduced vascular binding of hyaluronic acid binding protein in the liver microcirculation and increased its plasma levels. Our results support a critical role of N-linked glycosylation of AGP in regulating its in vivo clearance and an influence of a hyaluronidase-sensitive component of the vessel wall on its transendothelial passage.

  6. Contact angle and droplet heat transfer during evaporation on structured and smooth surfaces of heated wall

    Science.gov (United States)

    Misyura, S. Y.

    2017-08-01

    Water evaporation in a wide range of droplet diameters and wall temperatures on the structured and smooth surfaces were studied experimentally. Linear dependence of evaporation rate (dV/dt) on a droplet radius varies when the volume is greater than 40-60 μl. The static contact angles on the structured surface vary with a droplet diameter for high wall superheating. Dependence of the contact angle on diameter for the corrugated surface is defined by a change in both potential energy barrier U and three-phase contact line tension τcl. This energy barrier for the structured wall changes with an increase in the initial droplet diameter and becomes constant for the large droplets. For high wall superheating, the power in the law of evaporation increases from 1 to 1.45 with an increase in the initial droplet diameter. Depending on the droplet radius, number of droplets and heater length, four different characters of evaporation are realized. Complete droplet evaporation time on structured surface is less than smooth wall. Heat transfer coefficient is greater for structured wall than smooth one. When simulating droplet evaporation and heat transfer, it is necessary to take into account free convection of air and vapor.

  7. Numerical Investigation of Structural Response of Corrugated Blast Wall Depending on Blast Load Pulse Shapes

    Directory of Open Access Journals (Sweden)

    Jung Min Sohn

    Full Text Available Abstract Hydrocarbon explosions are one of most hazardous events for workers on offshore platforms. To protect structures against explosion loads, corrugated blast walls are typically installed. However, the profiles of real explosion loads are quite different depending on the congestion and confinement of Topside structures. As the level of congestion and confinement increases, the explosion load increases by up to 8 bar, and the rising time of the load decreases. This study primarily aims to investigate the structural behavior characteristics of corrugated blast walls under different types of explosion loadings. Four loading shapes were applied in the structural response analysis, which utilized a dynamic nonlinear finite element method.

  8. Mooring System Diagnosis and Structural Reliability Control for Position Moored Vessels

    DEFF Research Database (Denmark)

    Fang, Shaoji; Blanke, Mogens; Leira, Bernt J.

    2015-01-01

    Early diagnosis and fault-tolerant control are essential for safe operation of oating platforms where mooring systems maintain vessel position and must withstand environmental loads. This paper considers two critical faults, line breakage and loss of a buoyancy element and employs vector...... for monitoring the safety level of each mooring line and, a set-point chasing algorithm accommodates the eects of line failure, as an integral part of the reliability- based set-point chasing control algorithm. The feasibility of the diagnosis and of the fault-tolerant control strategy is veried in model basin...... statistical change detection for timely diagnosis of faults. Diagnosis design is scrutinized and a procedure is proposed based on specied false alarm probability and estimation of the distribution of the test statistics on which change detection is based. A structural reliability index is applied...

  9. Structure and stability of SnS2-based single- and multi-wall nanotubes

    Science.gov (United States)

    Bandura, Andrei V.; Evarestov, Robert A.

    2015-11-01

    Hybrid density functional method PBE0 which mixes the 75% Perdew-Burke-Ernzerhof and 25% Hartree-Fock exchange functional has been applied for investigation of the electronic and atomic structures of nanotubes obtained by rolling up of hexagonal layers of tin disulfide. Calculations have been performed on the basis of the localized atomic functions by means of the CRYSTAL09 computer code. The calculated strain energy of SnS2 single-wall nanotubes approximately obeys the R- 2 law (R is nanotube radius) of the classical elasticity theory. The SnS2 nanotube electronic band structures yield a semiconducting behavior. Band gap of single-wall nanotubes decreases linearly with R- 1. The dispersion force correction is found to be important for prediction of the multi-wall nanotube stability. The distance and interaction energy between the single-wall components of the double-wall nanotubes are proved to be close to the distance and interaction energy between layers in the bulk crystal. Analysis of the relaxed nanotube shape using the offered method demonstrates a small but noticeable deviation from completely cylindrical cross-section of the external walls in the armchair-like double- and triple-walled nanotubes.

  10. Domain wall structure in metals: A new approach to an old problem

    Science.gov (United States)

    da Silva Júnior, A. F.; de Campos, M. F.; Martins, A. S.

    2017-11-01

    The Monte Carlo Simulated Annealing (MCSA) method is used for performing micromagnetic simulations, in particular the determination of the domain wall structure originated from the energy's minimization of known micromagnetic hamiltonians. Beside the new theoretical approach, we also discuss the influence of different models for the exchange energy on the wall structure. It was found that the existence of long range exchange, like the RKKY interactions, can significantly affects the domain wall width when compared to the results obtained for the typical Heisenberg like exchange, whose range is restricted to the nearest neighbors. The calculations also indicate that especially for phases with high magnetocrystalline anisotropy the modeling should be performed at atomistic level or, in other words, the Bloch wall continuum model is not valid.

  11. Wall effect on fluid–structure interactions of a tethered bluff body

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Sumant; Raghav, Vrishank, E-mail: vrishank@gatech.edu; Komerath, Narayanan, E-mail: komerath@gatech.edu; Smith, Marilyn

    2013-11-01

    Wind tunnel experiments have shown an unexplained amplification of the free motion of a tethered bluff body in a small wind tunnel relative to that in a large wind tunnel. The influence of wall proximity on fluid–structure interaction is explored using a compound pendulum motion in the plane orthogonal to a steady freestream with a doublet model for aerodynamic forces. Wall proximity amplifies a purely symmetric single degree of freedom oscillation with the addition of an out-of-phase force. The success of this simple level of simulation enables progress to develop metrics for unsteady wall interference in dynamic testing of tethered bluff bodies.

  12. Sound propagation in a duct of periodic wall structure. [numerical analysis

    Science.gov (United States)

    Kurze, U.

    1978-01-01

    A boundary condition, which accounts for the coupling in the sections behind the duct boundary, is given for the sound-absorbing duct with a periodic structure of the wall lining and using regular partition walls. The soundfield in the duct is suitably described by the method of differences. For locally active walls this renders an explicit approximate solution for the propagation constant. Coupling may be accounted for by the method of differences in a clear manner. Numerical results agree with measurements and yield information which has technical applications.

  13. Platelet-derived growth factor B retention is essential for development of normal structure and function of conduit vessels and capillaries

    DEFF Research Database (Denmark)

    Nyström, Henrik C.; Lindblom, Per; Wickman, Anna

    2006-01-01

    : Passive and active properties of conduit vessels were studied using myograph techniques and histological examination. Capillary structure and function was studied using measurements of capillary density in skeletal muscle and by assessing aerobic physical performance in a treadmill setup. Cardiac function...... was assessed using echocardiography. RESULTS: Myograph experiments revealed an increased diameter and stiffness of the aorta in RetKO. Histological examination showed increased media collagen content and a decreased number of aortic wall layers, however with a similar number of vascular smooth muscle cells....... This outward eutrophic remodelling of the aorta was accompanied by endothelial dysfunction. RetKO showed decreased capillary density in skeletal muscle and signs of a defective delivery of capillary oxygen to skeletal muscle, as shown by a decreased physical performance. In RetKO mice, echocardiography...

  14. High-R Walls for New Construction Structural Performance: Wind Pressure Testing

    Energy Technology Data Exchange (ETDEWEB)

    DeRenzis, A.; Kochkin, V.

    2013-01-01

    This technical report is focused primarily on laboratory testing that evaluates wind pressure performance characteristics for wall systems constructed with exterior insulating sheathing. This research and test activity will help to facilitate the ongoing use of non-structural sheathing options and provide a more in-depth understanding of how wall system layers perform in response to high wind perturbations normal to the surface.

  15. High-R Walls for New Construction Structural Performance. Wind Pressure Testing

    Energy Technology Data Exchange (ETDEWEB)

    DeRenzis, A. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States); Kochkin, V. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States)

    2013-01-01

    This technical report is focused primarily on laboratory testing that evaluates wind pressure performance characteristics for wall systems constructed with exterior insulating sheathing. This research and test activity will help to facilitate the ongoing use of non-structural sheathing options and provide a more in-depth understanding of how wall system layers perform in response to high wind perturbations normal to the surface.

  16. THE INFLUINCE OF THE STAPHYLOCOCCUS INFECTION TO THE STRUCTURAL ORGANIZATION OF WISTAR RATS BRAIN AND CEREBRAL BLOOD VESSELS

    Directory of Open Access Journals (Sweden)

    Torianik I. I.

    2013-12-01

    Full Text Available In this article there are a dates about the influence of thestaphylococcus infection to the structural organization of Wistar rats brain and cerebral blood vessels in experiment. The purpose of the experiment’s are achieving by the seding staphylococcus infection means of the characterical structures of the brain and cerebralblood damages, that similar with the such in a human in a case of the development of a traditional clinic pathology.The results are evaluated to character of the morphological changes (brain cortex and cerebral blood vessels destructive and degenerative alterations,inflammatory processes.

  17. [Bladder injury by penetration of artificial vessel graft].

    Science.gov (United States)

    Wada, Naoki; Tamaki, Gaku; Kura, Tatsuhiko; Saga, Yuji; Kakizaki, Hidehiro

    2009-01-01

    Iatrogenic bladder injury by artificial vessel graft is extremely rare and only 3 cases have been reported. Herein, we report a case of bladder injury by penetration of artificial vessel graft. An 80-year-old male underwent a femoro-femoral crossover bypass surgery for arteriosclerosis obliterans in our hospital. Postoperatively he complained of urinary incontinence and was referred to the urology department. Ultrasonography for evaluating microscopic hematuria revealed a high echoic linear structure in the bladder and subsequent cystoscopy found an artificial vessel graft penetrating bladder wall. Vascular surgeons reconstructed femoro-femoral bypass and we removed the artificial vessel graft and repaired the injured bladder wall. This is the fourth case of bladder penetrating injury by artificial vessel graft and we summarize the reported cases.

  18. Effect of Yeast Cell Morphology, Cell Wall Physical Structure and Chemical Composition on Patulin Adsorption.

    Science.gov (United States)

    Luo, Ying; Wang, Jianguo; Liu, Bin; Wang, Zhouli; Yuan, Yahong; Yue, Tianli

    2015-01-01

    The capability of yeast to adsorb patulin in fruit juice can aid in substantially reducing the patulin toxic effect on human health. This study aimed to investigate the capability of yeast cell morphology and cell wall internal structure and composition to adsorb patulin. To compare different yeast cell morphologies, cell wall internal structure and composition, scanning electron microscope, transmission electron microscope and ion chromatography were used. The results indicated that patulin adsorption capability of yeast was influenced by cell surface areas, volume, and cell wall thickness, as well as 1,3-β-glucan content. Among these factors, cell wall thickness and 1,3-β-glucan content serve significant functions. The investigation revealed that patulin adsorption capability was mainly affected by the three-dimensional network structure of the cell wall composed of 1,3-β-glucan. Finally, patulin adsorption in commercial kiwi fruit juice was investigated, and the results indicated that yeast cells could adsorb patulin from commercial kiwi fruit juice efficiently. This study can potentially simulate in vitro cell walls to enhance patulin adsorption capability and successfully apply to fruit juice industry.

  19. Effect of Yeast Cell Morphology, Cell Wall Physical Structure and Chemical Composition on Patulin Adsorption.

    Directory of Open Access Journals (Sweden)

    Ying Luo

    Full Text Available The capability of yeast to adsorb patulin in fruit juice can aid in substantially reducing the patulin toxic effect on human health. This study aimed to investigate the capability of yeast cell morphology and cell wall internal structure and composition to adsorb patulin. To compare different yeast cell morphologies, cell wall internal structure and composition, scanning electron microscope, transmission electron microscope and ion chromatography were used. The results indicated that patulin adsorption capability of yeast was influenced by cell surface areas, volume, and cell wall thickness, as well as 1,3-β-glucan content. Among these factors, cell wall thickness and 1,3-β-glucan content serve significant functions. The investigation revealed that patulin adsorption capability was mainly affected by the three-dimensional network structure of the cell wall composed of 1,3-β-glucan. Finally, patulin adsorption in commercial kiwi fruit juice was investigated, and the results indicated that yeast cells could adsorb patulin from commercial kiwi fruit juice efficiently. This study can potentially simulate in vitro cell walls to enhance patulin adsorption capability and successfully apply to fruit juice industry.

  20. An Integrated Acousto/Ultrasonic Structural Health Monitoring System for Composite Pressure Vessels.

    Science.gov (United States)

    Bulletti, Andrea; Giannelli, Pietro; Calzolai, Marco; Capineri, Lorenzo

    2016-06-01

    This paper describes the implementation of a structural health monitoring (SHM) method for mechanical components and structures in composite materials with a focus on carbon-fiber-overwrapped pressure vessels (COPVs) used in the aerospace industry. Two flex arrays of polyvinylidene fluoride (PVDF) interdigital transducers have been designed, realized, and mounted on the COPV to generate guided Lamb waves (mode A0) for damage assessment. We developed a custom electronic instrument capable of performing two functions using the same transducers: passive-mode detection of impacts and active-mode damage assessment using Lamb waves. The impact detection is based on an accurate evaluation of the time of arrival and was successfully tested with low-velocity impacts (7 and 30 J). Damage detection and progression is based on the calculation of a damage index matrix which compares a set of signals acquired from the transducers with a baseline. This paper also investigates the advantage of tuning the active-mode frequency to obtain the maximum transducer response in the presence of structural variations of the specimen, and therefore, the highest sensitivity to damage.

  1. Effect of Jointing Mortar on Structural Behaviour of Wall Panels ...

    African Journals Online (AJOL)

    emerging as the grand eco-material for building construction for the 21st century due to its availability, environmental/cultural appropriateness, structural adequacy, familiarity to the local people, “breathability”, amongst others. Accordingly, both ...

  2. Numerical Analysis of Composite Steel Concrete Structural Shear Walls with Steel Encased Profiles

    Directory of Open Access Journals (Sweden)

    Daniel Dan

    2009-01-01

    Full Text Available The use of common reinforced concrete shear walls in high rise buildings is sometimes limited because of the large amount of reinforcement localized at the end of the element. A good alternative in avoiding this disadvantage is to use composite steel concrete structural shear walls with steel encased profiles. This solution used for high rise buildings, offers to designers lateral stiffness, shear capacity and high bending resisting moment of structural walls. The encasement of the steel shapes in concrete is applied also for the following purposes: flexural stiffening and strengthening of compression elements; fire protection; potentially easier repairs after moderate damage; economy with respect both to material and construction. Until now in the national and international literature poor information about nonlinear behaviour of composite steel concrete structural shear walls with steel encased profiles is available. A theoretical and experimental program related to the behaviour of steel concrete structural shear walls with steel encased profiles is developed at “Politehnica” University of Timişoara. The program refers to six different elements, which differ by the shape of the steel encased profile and also by the arrangement of steel shapes on the cross section of the element. In order to calibrate the elements for experimental study some numerical analysis were made. The paper presents the results of numerical analysis with details of stress distribution, crack distribution, structural stiffness at various loads, and load bearing capacity of the elements.

  3. Development of a rocking R/C shear wall system implementing repairable structural fuses

    Science.gov (United States)

    Parsafar, Saeed; Moghadam, Abdolreza S.

    2017-09-01

    In the last decades, the concept of earthquake resilient structural systems is becoming popular in which the rocking structure is considered as a viable option for buildings in regions of high seismicity. To this end, a novel wall-base connection based on the " repairable structure" approach is proposed and evaluated. The proposed system is made of several steel plates and high strength bolts act as a friction connection. To achieve the desired rocking motion in the proposed system, short-slotted holes are used in vertical directions for connecting the steel plates to the shear wall (SW). The experimental and numerical studies were performed using a series of displacement control quasi-static cyclic tests on a reference model and four different configurations of the proposed connection installed at the wall corners. The seismic response of the proposed system is compared to the conventional SW in terms of energy dissipation and damage accumulation. In terms of energy dissipation, the proposed system depicted better performance with 95% more energy dissipation capability compared to conventional SW. In terms of damage accumulation, the proposed SW system is nearly undamaged compared to the conventional wall system, which was severely damaged at the wall-base region. Overall, the introduced concept presents a feasible solution for R/C structures when a low-damage design is targeted, which can improve the seismic performance of the structural system significantly.

  4. The structure of cell wall alpha-glucan from fission yeast

    NARCIS (Netherlands)

    Grün, Christian H.; Hochstenbach, Frans; Humbel, Bruno M.; Verkleij, Arie J.; Sietsma, J. Hans; Klis, Frans M.; Kamerling, Johannis P.; Vliegenthart, Johannes F. G.

    2005-01-01

    Morphology and structural integrity of fungal cells depend on cell wall polysaccharides. The chemical structure and biosynthesis of two types of these polysaccharides, chitin and (1-->3)-beta-glucan, have been studied extensively, whereas little is known about alpha-glucan. Here we describe the

  5. The structure of cell wall alpha-glucan from fission yeast.

    NARCIS (Netherlands)

    Grün, C.H.; Hochstenbach, F.; Humbel, B.M.; Verkleij, A.J.; Sietsma, J.H.; Klis, F.M.; Kamerling, J.P.; Vliegenthart, J.F.G.

    2005-01-01

    Morphology and structural integrity of fungal cells depend on cell wall polysaccharides. The chemical structure and biosynthesis of two types of these polysaccharides, chitin and (1rarr3)-beta-glucan, have been studied extensively, whereas little is known about alpha-glucan. Here we describe the

  6. Stress state of thin – walled member of the structure with operation damages under nonuniform loading

    Directory of Open Access Journals (Sweden)

    В.В. Астанін

    2004-01-01

    Full Text Available  The publication is dedicated to determining of stress state in particular the stress concentration factors for thin – walled members of the structures subject to nonuniform tension. A structure member has obtained the operation damage generation by corrosion and other causes.

  7. Simulated Microgravity Regulates Gene Transcript Profiles of 2T3 Preosteoblasts: Comparison of the Random Positioning Machine and the Rotating Wall Vessel Bioreactor

    Science.gov (United States)

    Patel, Mamta J.; Liu, Wenbin; Sykes, Michelle C.; Ward, Nancy E.; Risin, Semyon A.; Risin, Diana; Hanjoong, Jo

    2007-01-01

    Microgravity of spaceflight induces bone loss due in part to decreased bone formation by osteoblasts. We have previously examined the microgravity-induced changes in gene expression profiles in 2T3 preosteoblasts using the Random Positioning Machine (RPM) to simulate microgravity conditions. Here, we hypothesized that exposure of preosteoblasts to an independent microgravity simulator, the Rotating Wall Vessel (RWV), induces similar changes in differentiation and gene transcript profiles, resulting in a more confined list of gravi-sensitive genes that may play a role in bone formation. In comparison to static 1g controls, exposure of 2T3 cells to RWV for 3 days inhibited alkaline phosphatase activity, a marker of differentiation, and downregulated 61 genes and upregulated 45 genes by more than two-fold as shown by microarray analysis. The microarray results were confirmed with real time PCR for downregulated genes osteomodulin, bone morphogenic protein 4 (BMP4), runx2, and parathyroid hormone receptor 1. Western blot analysis validated the expression of three downregulated genes, BMP4, peroxiredoxin IV, and osteoglycin, and one upregulated gene peroxiredoxin I. Comparison of the microarrays from the RPM and the RWV studies identified 14 gravi-sensitive genes that changed in the same direction in both systems. Further comparison of our results to a published database showing gene transcript profiles of mechanically loaded mouse tibiae revealed 16 genes upregulated by the loading that were shown to be downregulated by RWV and RPM. These mechanosensitive genes identified by the comparative studies may provide novel insights into understanding the mechanisms regulating bone formation and potential targets of countermeasure against decreased bone formation both in astronauts and in general patients with musculoskeletal disorders.

  8. Conformable pressure vessel for high pressure gas storage

    Energy Technology Data Exchange (ETDEWEB)

    Simmons, Kevin L.; Johnson, Kenneth I.; Lavender, Curt A.; Newhouse, Norman L.; Yeggy, Brian C.

    2016-01-12

    A non-cylindrical pressure vessel storage tank is disclosed. The storage tank includes an internal structure. The internal structure is coupled to at least one wall of the storage tank. The internal structure shapes and internally supports the storage tank. The pressure vessel storage tank has a conformability of about 0.8 to about 1.0. The internal structure can be, but is not limited to, a Schwarz-P structure, an egg-crate shaped structure, or carbon fiber ligament structure.

  9. Isogeometric analysis for thin-walled composite structures

    NARCIS (Netherlands)

    Guo, Y.

    2016-01-01

    The conceptual ideas behind isogeometric analysis (IGA) are aimed at unifying computer aided design (CAD) and finite element analysis (FEA). Isogeometric analysis employs the non-uniform rational B-spline functions (NURBS) used for the geometric description of a structure to approximate its physical

  10. Structural properties and foaming of plant cell wall polysaccharide dispersions.

    Science.gov (United States)

    Beatrice, Cesar A G; Rosa-Sibakov, Natalia; Lille, Martina; Sözer, Nesli; Poutanen, Kaisa; Ketoja, Jukka A

    2017-10-01

    Water suspensions of cellulose nanofibres with xylan, xyloglucan and pectin were studied for foaming and structural properties as a new means for food structuring. The dispersions were analysed with rheological measurements, microscopy and optical coherence tomography. A combination of xylan with TEMPO-oxidized nanocellulose produced a mixture with well-dispersed air bubbles, while the addition of pectin improved the elastic modulus, hardness and toughness of the structures. A similar structure was observed with native nanocellulose, but the elastic modulus was not as high. Shear flow caused cellulose nanofibres to form plate-like flocs in the suspension that accumulated near bubble interfaces. This tendency could be affected by adding laccase to the dispersion, but the effect was opposite for native and TEMPO-oxidized nanocellulose. Nanocellulose type also influenced the interactions between nanofibers and other polysaccharides. For example, xyloglucan interacted strongly with TEMPO-oxidized nanocellulose (high storage modulus) but not with native nanocellulose. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Development of strongly coupled FSI technology involving thin walled structures

    CSIR Research Space (South Africa)

    Suliman, Ridhwaan

    2011-01-01

    Full Text Available A strongly coupled finite volume-finite element fluid-structure interaction (FSI) scheme is developed. Both an edge-based finite volume and Galerkin finite element scheme are implemented and evaluated for modelling the mechanics of solids...

  12. Insights into cell wall structure of Sida hermaphrodita and its influence on recalcitrance.

    Science.gov (United States)

    Damm, Tatjana; Pattathil, Sivakumar; Günl, Markus; Jablonowski, Nicolai David; O'Neill, Malcolm; Grün, Katharina Susanne; Grande, Philipp Michael; Leitner, Walter; Schurr, Ulrich; Usadel, Björn; Klose, Holger

    2017-07-15

    The perennial plant Sida hermaphrodita (Sida) is attracting attention as potential energy crop. Here, the first detailed view on non-cellulosic Sida cell wall polysaccharide composition, structure and architecture is given. Cell walls were prepared from Sida stems and sequentially extracted with aqueous buffers and alkali. The structures of the quantitatively predominant polysaccharides present in each fraction were determined by biochemical characterization, glycome profiling and mass spectrometry. The amounts of glucose released by Accellerase-1500® treatment of the cell wall and the cell wall residue remaining after each extraction were used to assess the roles of pectin and hemicellulose in the recalcitrance of Sida biomass. 4-O-Methyl glucuronoxylan with a low proportion of side substitutions was identified as the major non-cellulosic glycan component of Sida stem cell walls. Pectic polysaccharides and xylans were found to be associated with lignin, suggesting that these polysaccharides have roles in Sida cell wall recalcitrance to enzymatic hydrolysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. International Atomic Energy Agency (IAEA) Coordinated Research Projects on Structural Integrity of Reactor Pressure Vessels

    Energy Technology Data Exchange (ETDEWEB)

    Server, W. L. [ATI Consulting, Pinehurst, NC; Nanstad, Randy K [ORNL

    2009-01-01

    The International Atomic Energy Agency (IAEA) has conducted a series of Coordinated Research Projects (CRPs) that have focused on irradiated reactor pressure vessel (RPV) steel fracture toughness properties and approaches for assuring structural integrity of RPVs throughout operating life. A series of nine CRPs have been sponsored by the IAEA, starting in the early 1970s, focused on neutron radiation effects on RPV steels. The purpose of the CRPs was to develop comparisons and correlations to test the uniformity of irradiated results through coordinated international research studies and data sharing. Consideration of dose rate effects, effects of alloying (nickel, manganese, silicon, etc.) and residual elements (eg., copper and phosphorus), and drop in upper shelf toughness are also important for assessing neutron embrittlement effects. The ultimate use of embrittlement understanding is assuring structural integrity of the RPV under current and future operation and accident conditions. Material fracture toughness is the key ingredient needed for this assessment, and many of the CRPs have focused on measurement and application of irradiated fracture toughness. This paper presents an overview of the progress made since the inception of the CRPs in the early 1970s. The chronology and importance of each CRP have been reviewed and put into context for continued and long-term safe operation of RPVs.

  14. Turbine airfoil with dual wall formed from inner and outer layers separated by a compliant structure

    Science.gov (United States)

    Campbell,; Christian X. , Morrison; Jay, A [Oviedo, FL

    2011-12-20

    A turbine airfoil usable in a turbine engine with a cooling system and a compliant dual wall configuration configured to enable thermal expansion between inner and outer layers while eliminating stress formation is disclosed. The compliant dual wall configuration may be formed a dual wall formed from inner and outer layers separated by a compliant structure. The compliant structure may be configured such that the outer layer may thermally expand without limitation by the inner layer. The compliant structure may be formed from a plurality of pedestals positioned generally parallel with each other. The pedestals may include a first foot attached to a first end of the pedestal and extending in a first direction aligned with the outer layer, and may include a second foot attached to a second end of the pedestal and extending in a second direction aligned with the inner layer.

  15. THE STRUCTURAL ANALYSIS OF STEEL SILOS WITH CYLINDRICAL-WALL BEARING AND PROFILE-STEEL BEARING

    Directory of Open Access Journals (Sweden)

    Zhengjun Tang

    2015-04-01

    Full Text Available The silos are widely used in bulk material in many fields such as agriculture, mining, chemical, electric power storage, etc. Thin metal cylindrical silo shells are vulnerable to buckling failure caused by the compressive wall friction force. In this paper, the structural analysis of two types of steel silo with cylindrical-wall bearing and profile-steel bearing is implemented by Abaqus finite element analysis. The results indicate that under the same loading conditions, steel silos with profile-steel bearing and cylindrical-Wall bearing have similar values in Mises stress, but the steel silo with profile-steel bearing has a smaller radial displacement and a better capability of buckling resistance. Meanwhile, the total steel volumes reduced 8.0% comparing to the steel silo with cylindrical-wall bearing. Therefore, steel soil with profile-steel bearing not only has a less steel volumes but also a good stability.

  16. Lignin isolated from primary walls of hybrid aspen cell cultures indicates significant differences in lignin structure between primary and secondary cell wall.

    Science.gov (United States)

    Christiernin, Maria; Ohlsson, Anna B; Berglund, Torkel; Henriksson, Gunnar

    2005-08-01

    Hybrid aspen (Populus tremula x tremuloides) cell cultures were grown for 7, 14 and 21 days. The cell cultures formed primary cell walls but no secondary cell wall according to carbohydrate analysis and microscopic characterization. The primary walls were lignified, increasingly with age, according to Klason lignin analysis. Presence of lignin in the primary walls, with a higher content in 21-day old cells than in 7-day old cells, was further supported by phloroglucinol/HCl reagent test and confocal microscopy after both immunolocalization and staining with acriflavin. Both laccase and peroxidase activity were found in the cultures and the activity increased during lignin formation. The lignin from the cell culture material was compared to lignin from mature aspen wood, where most of the lignin originates in the secondary cell wall, and which served as our secondary cell wall control. Lignin from the cell walls was isolated and characterized by thioacidolysis followed by gas chromatography and mass spectrometry. The lignin in the cell cultures differed from lignin of mature aspen wood in that it consisted exclusively of guaiacyl units, and had a more condensed structure. Five lignin structures were identified by mass spectrometry in the cell suspension cultures. The results indicate that the hybrid aspen cell culture used in this investigation may be a convenient experimental system for studies of primary cell wall lignin.

  17. Analytical and Numerical Evaluation of Limit States of MSE Wall Structure

    Directory of Open Access Journals (Sweden)

    Drusa Marián

    2016-12-01

    Full Text Available Simplification of the design of Mechanically Stabilized Earth wall structures (MSE wall or MSEW is now an important factor that helps us not only to save a time and costs, but also to achieve the desired results more reliably. It is quite common way in practice, that the designer of a section of motorway or railway line gives order for design to a supplier of geosynthetics materials. However, supplier company has experience and skills, but a general designer does not review the safety level of design and its efficiency, and is simply incorporating into the overall design of the construction project. Actually, large number of analytical computational methods for analysis and design of MSE walls or similar structures are known. The problem of these analytical methods is the verification of deformations and global stability of structure. The article aims to clarify two methods of calculating the internal stability of MSE wall and their comparison with FEM numerical model. Comparison of design approaches allows us to draft an effective retaining wall and tells us about the appropriateness of using a reinforcing element.

  18. Internal structure of an ex-vessel corium debris bed during severe accidents of LWRs

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eunho; Park, Jin Ho; Moriyama, Kiyofumi; Park, Hyun Sun [POSTECH, Daejeon (Korea, Republic of)

    2015-10-15

    In the aspect of the coolability assessment the configuration of the debris bed, including internal and external characteristics, has significant importance as boundary conditions for simulations, however, relatively little investigation of the sedimentation process. For the development of a debris bed, recently there have been several studies that focused on thermal characteristics of corium particles. Yakush et al. performed simulation studies and showed that two phase natural convection affects the particle settling trajectory and changes the final arrival location of particles to result more flattened bed. Those simulation results have been supported by the experimental studies of Kim et al. using simulant particles and air bubble injection. For the internal structure of a debris bed, there have been several simulation and experimental studies, which investigated the effect of internal structure on debris bed coolability. Magallon has reported the particle size distribution at three elevations of the debris bed of FARO L-31 case, where the mean particle size was bigger for the lower elevation. However, there is a lack of detailed information on the characteristics of the debris bed, including the local structure and porosity. In this study, we investigated the internal structure of the debris bed using a mixture of stainless steel particles and air bubble injection. Local particle sedimentation quantity, particle size distribution change in radial direction and axial direction, and bed porosity was measured to investigate a relationship between the internal structure and the accident condition. An experimental investigation was carried out for the internal structure of ex-vessel corium debris bed in the flooded cavity during sever accident. Moderate corium discharge in high flooding level was assumed for full fragmentation of melt jet. The test particle mixture was prepared by following an empirical correlation, which reflects the particle size distribution of

  19. Vessel Operating Units (Vessels)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains data for vessels that are greater than five net tons and have a current US Coast Guard documentation number. Beginning in1979, the NMFS...

  20. The evolution of angiosperm lianescence without vessels--climbing mode and wood structure-function in Tasmannia cordata (Winteraceae).

    Science.gov (United States)

    Feild, Taylor S; Chatelet, David S; Balun, Lawong; Schilling, Edward E; Evans, Robert

    2012-01-01

    • The lack of extant lianescent vessel-less seed plants supports a hypothesis that liana evolution requires large-diameter xylem conduits. Here, we demonstrate an unusual example of a lianoid vessel-less angiosperm, Tasmannia cordata (Winteraceae), from New Guinea. • Wood mechanical, hydraulic and structural measurements were used to determine how T. cordata climbs and to test for ecophysiological shifts related to liana evolution vs 13 free-standing congeners. • The tracheid-based wood of T. cordata furnished low hydraulic capacity compared with that of vessel-bearing lianas. In comparison with most nonclimbing relatives, T. cordata possessed lower photosynthetic rates and leaf and stem hydraulic capacities. However, T. cordata exhibited a two- to five-fold greater wood elastic modulus than its relatives. • Tasmannia cordata provides an unusual example of angiosperm liana evolution uncoupled from xylem conduit gigantism, as well as high plasticity and cell type diversity in vascular development. Because T. cordata lacks vessels, our results suggest that a key limitation for a vessel-less liana is that strong and low hydraulically conductive wood is required to meet the mechanical demands of lianescence. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

  1. Non-Axisymmetric Inflatable Pressure Structure (NAIPS) Concept that Enables Mass Efficient Packageable Pressure Vessels with Sealable Openings

    Science.gov (United States)

    Doggett, William R.; Jones, Thomas C.; Kenner, Winfred S.; Moore, David F.; Watson, Judith J.; Warren, Jerry E.; Makino, Alberto; Yount, Bryan; Selig, Molly; Shariff, Khadijah; hide

    2016-01-01

    Achieving minimal launch volume and mass are always important for space missions, especially for deep space manned missions where the costs required to transport mass to the destination are high and volume in the payload shroud is limited. Pressure vessels are used for many purposes in space missions including habitats, airlocks, and tank farms for fuel or processed resources. A lucrative approach to minimize launch volume is to construct the pressure vessels from soft goods so that they can be compactly packaged for launch and then inflated en route or at the final destination. In addition, there is the potential to reduce system mass because the packaged pressure vessels are inherently robust to launch loads and do not need to be modified from their in-service configuration to survive the launch environment. A novel concept is presented herein, in which sealable openings or hatches into the pressure vessels can also be fabricated from soft goods. To accomplish this, the structural shape is designed to have large regions where one principal stress is near zero. The pressure vessel is also required to have an elongated geometry for applications such as airlocks.

  2. BIOASSAY VESSEL FAILURE ANALYSIS

    Energy Technology Data Exchange (ETDEWEB)

    Vormelker, P

    2008-09-22

    Two high-pressure bioassay vessels failed at the Savannah River Site during a microwave heating process for biosample testing. Improper installation of the thermal shield in the first failure caused the vessel to burst during microwave heating. The second vessel failure is attributed to overpressurization during a test run. Vessel failure appeared to initiate in the mold parting line, the thinnest cross-section of the octagonal vessel. No material flaws were found in the vessel that would impair its structural performance. Content weight should be minimized to reduce operating temperature and pressure. Outer vessel life is dependent on actual temperature exposure. Since thermal aging of the vessels can be detrimental to their performance, it was recommended that the vessels be used for a limited number of cycles to be determined by additional testing.

  3. Architecture-based multiscale computational modeling of plant cell wall mechanics to examine the hydrogen-bonding hypothesis of the cell wall network structure model.

    Science.gov (United States)

    Yi, Hojae; Puri, Virendra M

    2012-11-01

    A primary plant cell wall network was computationally modeled using the finite element approach to study the hypothesis of hemicellulose (HC) tethering with the cellulose microfibrils (CMFs) as one of the major load-bearing mechanisms of the growing cell wall. A computational primary cell wall network fragment (10 × 10 μm) comprising typical compositions and properties of CMFs and HC was modeled with well-aligned CMFs. The tethering of HC to CMFs is modeled in accordance with the strength of the hydrogen bonding by implementing a specific load-bearing connection (i.e. the joint element). The introduction of the CMF-HC interaction to the computational cell wall network model is a key to the quantitative examination of the mechanical consequences of cell wall structure models, including the tethering HC model. When the cell wall network models with and without joint elements were compared, the hydrogen bond exhibited a significant contribution to the overall stiffness of the cell wall network fragment. When the cell wall network model was stretched 1% in the transverse direction, the tethering of CMF-HC via hydrogen bonds was not strong enough to maintain its integrity. When the cell wall network model was stretched 1% in the longitudinal direction, the tethering provided comparable strength to maintain its integrity. This substantial anisotropy suggests that the HC tethering with hydrogen bonds alone does not manifest sufficient energy to maintain the integrity of the cell wall during its growth (i.e. other mechanisms are present to ensure the cell wall shape).

  4. Improving Thermal Insulation Properties for Prefabricated Wall Components Made Of Lightweight Aggregate Concrete with Open Structure

    Science.gov (United States)

    Abramski, Marcin

    2017-10-01

    Porous concrete is commonly used in civil engineering due to its good thermal insulation properties in comparison with normal concrete and high compression strength in comparison with other building materials. Reducing of the concrete density can be obviously obtained by using lightweight aggregate (e.g. pumice). The concrete density can be further minimized by using specially graded coarse aggregate and little-to-no fine aggregates. In this way a large number of air voids arise. The aggregate particles are coated by a cement paste and bonded together with it just in contact points. Such an extremely porous concrete, called ‘lightweight aggregate concrete with open structure’ (LAC), is used in some German plants to produce prefabricated wall components. They are used mainly in hall buildings, e.g. supermarkets. The need of improving thermal insulation properties was an inspiration for the prefabrication plant managers, engineers and a scientific staff of the Technical University of Kaiserslautern / Germany to realise an interesting project. Its aim was to reduce the heat transfer coefficient for the wall components. Three different wall structure types were designed and compared in full-scale laboratory tests with originally produced wall components in terms of load-carrying capacity and stiffness. The load was applied perpendicularly to the wall plane. As the components are not originally used for load-bearing walls, but for curtain walls only, the wind load is the main load for them. The wall components were tested in horizontal position and the load was applied vertically. Totally twelve wall components 8.00 × 2.00 × 0.25m (three for every series) were produced in the prefabrication plant and tested in the University of Kaiserslautern laboratory. The designed and tested components differed from each other in the amount of expanded polystyrene (EPS), which was placed in the plant inside the wall structure. The minimal amount of it was designed in the

  5. STRUCTURAL EVALUATION OF PSSDB WALL PANEL WITH SQUARE OPENING AND VARIED SCREW SPACING

    Directory of Open Access Journals (Sweden)

    SITI HAWA HAMZAH

    2009-03-01

    Full Text Available Profiled steel sheet dry boards or PSSDB system is an alternative composite construction system comprising of profiled steel sheet compositely connected to dry boards by self-tapping self-driving screws. PSSDB system was used widely as flooring system in the lightweight construction of buildings and office space in factories. Due to its superiority in the installation techniques, PSSDB system was expanded in the application as load bearing wall panel system in buildings. The PSSDB system is as an alternative construction technique on load bearing wall panel that offers cost savings synonymously with the rapid progress of science and technology which leads to the shift from traditional utilization of construction materials to newer construction techniques. A finite element analysis was carried out to determine the effect of screw spacing on the PSSDB wall panel. The spacing selected was between 100 mm to 500 mm, at an increment of 100 mm in each different model. The wall panel measured 3000 mm by 3000 mm with a 1200 mm square window opening, 78 mm thick and butt joints vertically positioned in the dry boards. This paper looks into the system as load bearing wall panels, analyzing it under axial compressive load using established Finite Element technique. The deformation profile of the PSSDB wall panel system showed a single curvature deformation profile, maximum lateral displacement at two-thirds wall panel height and critical sections at the upper corners of the square opening. The finite element analysis had provided good prediction of the structural behavior of the PSSDB wall panel system and it is concluded that the PW200 model possesses the optimum arrangement of the fixing screws used.

  6. Review of Ballistic Limit Equations for Composite Structure Walls of Satellites

    Science.gov (United States)

    Schaefer, Frank K.*; Schneider, E.; Lambert, M.

    2004-08-01

    In this paper a review of existing ballistic limit equations for CFRP (Carbon Fibre Reinforced Plastics) structure walls of satellites is given, and two new ballistic limit equations are presented. The predictive capabilities of the equations are compared to a set of experimental hypervelocity impact test data of CFRP plates and CFRP honeycomb sandwich panels (satellite structure wall) from ENVISAT, AXAF, and a generic technology program. In the literature, three ballistic limit equations for sandwich panels (SP) made from CFRP face-sheets and Al- honeycomb (H/C) core were found and analyzed (Frost's approach, Approach using Christiansen's Whipple shield Ballistic Limit Equation (BLE), and Taylor's approach). Furthermore, in this paper, a new ballistic limit equation was proposed for CFRP H/C SP (Modified ESA Triple Wall Equation) and for composite panels (plates) with and without MLI attached to the surface. The amount of impact data on CFRP structure walls of satellites found in the literature was rather scarce. The new BLE for CFRP plates makes good predictions to the available set of test data. For the BLE for CFRP H/C SP, it was found that Frost's approach and application of Christiansen's BLE to CFRP H/C SP lead to an overprediction of the ballistic limit diameters for ENVISAT structure walls and the samples of the generic technology program. Taylor's approach and the newly designed MET ballistic limit equation have both yielded good predictions for all samples except for the AXAF samples that had rather thin-walled face-sheets and a thin Al H/C core: for these samples the predictions were conservative. Thus, for use in risk analysis tools for satellites (e. g. ESA's ESABASE/DEBRIS tool or NASA's BUMPER code), it is recommended to use either the MET or Taylor equation.

  7. Seismic retroftting of RC columns with RC jackets and wing walls with different structural details

    Science.gov (United States)

    Chang, Shuenn-Yih; Chen, Ting-Wei; Tran, Ngoc-Cuong; Liao, Wen-I.

    2014-06-01

    An original reinforced concrete (RC) column and four strengthened specimens, two with RC jackets and two with wing walls, were tested in this study. The original column specimen was designed to comply with older (pre-1999) design standards so that the usual detailing deficiencies in existing school buildings in Taiwan could be simulated. Two different structural details were chosen to fabricate the full-scale specimens for each retrofitting technique. The study confirmed that either RC jacketing or the installation of wing walls with two different structural details can effectively improve the stiffness and strength of an existing column. RC jacketing shows a better improvement in energy dissipation and ductility when compared to the columns with wing walls installed. This is because the two RC jacketed columns experienced a flexural failure, while a shear failure was found in the two columns with the wing walls installed, and thus led to a drastic decrease of the maximum lateral strengths and ductility. Since many factors may affect the installation of a post-installed anchor, it is better to use standard hooks to replace post-installed anchors in some specific points when using RC jacketing or installing wing walls.

  8. A Comparative Study of the Cell Wall Structure of Basidiomycetous and Related Yeasts

    NARCIS (Netherlands)

    Kreger-van Rij, N.J.W.; Veenhuis, M.

    1971-01-01

    The wall of basidiomycetous and related yeasts showed a lamellar structure in sections of both budding cells and hyphae fixed with potassium permanganate. The yeasts also had a typical way of bud formation and septation. These features differ from those recorded for ascomycetous yeasts. In the

  9. PRE-CAST WALL PRODUCTS MADE FROM LIGHTWEIGHT CONCRETE FOR ENCLOSING STRUCTURES OF BUILDINGS

    Directory of Open Access Journals (Sweden)

    M. R. Hadgiev

    2014-01-01

    Full Text Available The paper is devoted to the actual problem waste dismantling of buildings and structures in the form of brick waste with reception the secondary fine and coarse aggregate and concrete based on them for the manufacture of small-piece wall products. 

  10. Structural performance of new thin-walled concrete sandwich panel system reinforced with bfrp shear connectors

    DEFF Research Database (Denmark)

    Hodicky, Kamil; Hulin, Thomas; Schmidt, Jacob Wittrup

    2013-01-01

    This paper presents a new thin-walled concrete sandwich panel system reinforced with basalt fiber-reinforced plastic (BFRP) with optimum structural performances and a high thermal resistance developed by Connovate and Technical University of Denmark. The shear connecting system made of a BFRP grid...

  11. Structure of the cell wall of mango after application of ionizing radiation

    Science.gov (United States)

    Silva, Josenilda M.; Villar, Heldio P.; Pimentel, Rejane M. M.

    2012-11-01

    Cells of the mesocarp of mango cultivar Tommy Atkins were analyzed by Transmission Electron Microscope—TEM to evaluate the effects of doses of 0.5 and 1.0 kGy applied immediately after the fruit and after storage for twenty days at a temperature of 12 °C followed by 5 days of simulated marketing at a temperature of 21 °C. No alteration was found in the structure of the cell wall, middle lamella, and plasma membrane of fruits when analyzed immediately after application of doses. The mesocarp cell structure of the cell wall, middle lamella, and the plasma membrane did however undergo changes after storage. Fruits that received a dose of 0.5 kGy displayed slight changes in cell wall structure and slight disintegration of the middle lamella. Fruits that received a dose of 1.0 kGy displayed more severe changes in the structure of the cell wall, greater middle lamella degradation, and displacement of the plasma membrane.

  12. Elucidation of the chemical fine structure of polysaccharides from soybean and maize kernel cell walls

    NARCIS (Netherlands)

    Huisman, M.M.H.

    2000-01-01

    The subject of this thesis was the elucidation of the chemical fine structure of polysaccharides from cell walls of soybean and maize kernel. The two species investigated represent different taxonomic groups, soybean belonging to the dicotyledonous and maize to the monocotyledonous plants.

  13. Reliable Propagation of Magnetic Domain Walls in Cross Structures for Advanced Multiturn Sensors

    Science.gov (United States)

    Borie, B.; Voto, M.; Lopez-Diaz, L.; Grimm, H.; Diegel, M.; Kläui, M.; Mattheis, R.

    2017-10-01

    We develop and analyze an advanced concept for a domain-wall-based sensing of rotations. Moving domain walls in n closed loops with n -1 intersecting convolutions by rotating fields, we are able to sense n rotations. By combining loops with coprime numbers of rotations, we create a sensor system allowing for the total counting of millions of turns of a rotating applied magnetic field. We analyze the operation of the sensor and identify the intersecting cross structures as the critical component for reliable operation. Specifically, depending on the orientation of the applied field angle with the magnetization in the branches of the cross, a domain wall is found to propagate in an unwanted direction, yielding failures and counting errors in the device. To overcome this limiting factor, we introduce a specially designed syphon structure to the controlled pinning of the domain wall before the cross and depinning and propagation only for a selected range of applied field angles. By adjusting the syphon and the cross geometry, we find that the optimized combination of both structures prevents failures in the full sensor structure yielding robust operation. Our modeling results show that the optimized element geometry allows for the realization of the sensor with cross-shaped intersections and an operation that is tolerant to inaccuracies of the fabrication.

  14. Platform image processing to study the structural properties of retinal vessel

    Directory of Open Access Journals (Sweden)

    Gabino VERDE

    2013-05-01

    Full Text Available This paper presents a technological platform specialized in assessing retinal vessel caliber and describing the relationship of the results obtained to cardiovascular risk. Retinal circulation is an area of active research by numerous groups, and there is general experimental agreement on the analysis of the patterns of the retinal blood vessels in the normal human retina. The development of automated tools designed to improve performance and decrease interobserver variability, therefore, appears necessary. 

  15. Experimental determination of excitonic band structures of single-walled carbon nanotubes using circular dichroism spectra.

    Science.gov (United States)

    Wei, Xiaojun; Tanaka, Takeshi; Yomogida, Yohei; Sato, Naomichi; Saito, Riichiro; Kataura, Hiromichi

    2016-10-05

    Experimental band structure analyses of single-walled carbon nanotubes have not yet been reported, to the best of our knowledge, except for a limited number of reports using scanning tunnelling spectroscopy. Here we demonstrate the experimental determination of the excitonic band structures of single-chirality single-walled carbon nanotubes using their circular dichroism spectra. In this analysis, we use gel column chromatography combining overloading selective adsorption with stepwise elution to separate 12 different single-chirality enantiomers. Our samples show higher circular dichroism intensities than the highest values reported in previous works, indicating their high enantiomeric purity. Excitonic band structure analysis is performed by assigning all observed Eii and Eij optical transitions in the circular dichroism spectra. The results reproduce the asymmetric structures of the valence and conduction bands predicted by density functional theory. Finally, we demonstrate that an extended empirical formula can estimate Eij optical transition energies for any (n,m) species.

  16. Plant cell wall extensibility: connecting plant cell growth with cell wall structure, mechanics, and the action of wall-modifying enzymes

    Energy Technology Data Exchange (ETDEWEB)

    Cosgrove, Daniel J.

    2015-11-25

    The advent of user-friendly instruments for measuring force/deflection curves of plant surfaces at high spatial resolution has resulted in a recent outpouring of reports of the ‘Young's modulus’ of plant cell walls. The stimulus for these mechanical measurements comes from biomechanical models of morphogenesis of meristems and other tissues, as well as single cells, in which cell wall stress feeds back to regulate microtubule organization, auxin transport, cellulose deposition, and future growth directionality. In this article I review the differences between elastic modulus and wall extensibility in the context of cell growth. Some of the inherent complexities, assumptions, and potential pitfalls in the interpretation of indentation force/deflection curves are discussed. Reported values of elastic moduli from surface indentation measurements appear to be 10- to >1000-fold smaller than realistic tensile elastic moduli in the plane of plant cell walls. Potential reasons for this disparity are discussed, but further work is needed to make sense of the huge range in reported values. The significance of wall stress relaxation for growth is reviewed and connected to recent advances and remaining enigmas in our concepts of how cellulose, hemicellulose, and pectins are assembled to make an extensible cell wall. A comparison of the loosening action of α-expansin and Cel12A endoglucanase is used to illustrate two different ways in which cell walls may be made more extensible and the divergent effects on wall mechanics.

  17. Structural evaluation of W-211 flexible receiver platforms and tank pit walls

    Energy Technology Data Exchange (ETDEWEB)

    Shrivastava, H.P.

    1997-11-03

    This document is a structural analysis of the Flexible Receiver Platforms and the tank-pit wall during removal of equipment and during a accidental drop of that equipment. The platform and the pit walls must withstand a accidental drop of a mixer and transfer pumps in specific pits in tanks 102-AP and 104-AP. A mixer pump will be removed from riser 11 in pit 2A on tank 241-AP-102. A transfer pump will be removed from riser 13 in pit 2D on tank 241-AP-102 and another transfer pump will be removed from riser 3A in pit 4A on tank 241-AP-104.

  18. Right ventricular wall abscess in structurally normal heart after leg osteomyelitis: First case.

    Science.gov (United States)

    Ahmad, Tanveer; Pasarad, Ashwini Kumar; Kishore, Kolkebaile Sadanand; Maheshwarappa, Nandakumar Neralakere

    2016-09-01

    A 3-year-old girl presented with fever and acute dyspnea for 4 days. She had suffered an injury to the left lower leg 3 weeks earlier, with abscess formation. Magnetic resonance imaging showed osteomyelitis of the lower tibia. Echocardiography showed a mass in the right ventricular wall. She underwent concomitant heart surgery for removal of the right ventricular mass and limb arthrotomy. We believe this is a first reported case in which a ventricular wall abscess developed in a structurally normal heart following leg osteomyelitis. © The Author(s) 2015.

  19. New Equivalent Linear Impact Model for Simulation of Seismic Isolated Structure Pounding against Moat Wall

    OpenAIRE

    Yang Liu; Wen-Guang Liu; Xin Wang; Wen-Fu He; Qiao-Rong Yang

    2014-01-01

    Base-isolated buildings subjected to extreme earthquakes or near-fault pulse-like earthquakes can exceed their design gap distance and impact against the surrounding moat wall. Based on equating energy dissipation and maximum collision compression deformation of isolated structure with the Hertz-damp model and Kevin-Voigt model in the process of collision, an equivalent linear impact model (ELIM) is proposed to better predict impact response of seismic isolated structure. The formula of the e...

  20. The Influence of Infill Wall Topology and Seismic Characteristics on the Response and Damage Distribution in Frame Structures

    Directory of Open Access Journals (Sweden)

    Nikos Nanos

    2013-01-01

    Full Text Available This paper identifies the effects of infill wall existence and arrangement in the seismic response of frame structures utilising the global structural damage index after Park/Ang (GDIPA and the maximum interstorey drift ratio (MISDR to express structural seismic response. Five different infill wall topologies of a 10-storey frame structure have been selected and analysed presenting an improved damage distribution model for infill wall bearing frames, hence promoting the use of nonstructural elements as a means of improving frame structural seismic behaviour and highlighting important aspects of structural response, demonstrating the suitability of such element implementation beyond their intended architectural scope.

  1. Regulation of genes involved in cell wall synthesis and structure during Ustilago maydis dimorphism.

    Science.gov (United States)

    Robledo-Briones, Mariana; Ruiz-Herrera, José

    2013-02-01

    The cell wall is the structure that provides the shape to fungal cells and protects them from the difference in osmotic pressure existing between the cytosol and the external medium. Accordingly, changes in structure and composition of the fungal wall must occur during cell differentiation, including the dimorphic transition of fungi. We analyzed, by use of microarrays, the transcriptional regulation of the 639 genes identified to be involved in cell wall synthesis and structure plus the secretome of the Basidiomycota species Ustilago maydis during its dimorphic transition induced by a change in pH. Of these, 189 were differentially expressed during the process, and using as control two monomorphic mutants, one yeast like and the other mycelium constitutive, 66 genes specific of dimorphism were identified. Most of these genes were up-regulated in the mycelial phase. These included CHS genes, genes involved in β-1,6-glucan synthesis, N-glycosylation, and proteins containing a residue of glycosylphosphatidylinositol, and a number of genes from the secretome. The possible significance of these data on cell wall plasticity is discussed. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  2. 8th Annual Glycoscience Symposium: Integrating Models of Plant Cell Wall Structure, Biosynthesis and Assembly

    Energy Technology Data Exchange (ETDEWEB)

    Azadi, Paratoo [Univ. of Georgia, Athens, GA (United States)

    2015-09-24

    The Complex Carbohydrate Research Center (CCRC) of the University of Georgia holds a symposium yearly that highlights a broad range of carbohydrate research topics. The 8th Annual Georgia Glycoscience Symposium entitled “Integrating Models of Plant Cell Wall Structure, Biosynthesis and Assembly” was held on April 7, 2014 at the CCRC. The focus of symposium was on the role of glycans in plant cell wall structure and synthesis. The goal was to have world leaders in conjunction with graduate students, postdoctoral fellows and research scientists to propose the newest plant cell wall models. The symposium program closely followed the DOE’s mission and was specifically designed to highlight chemical and biochemical structures and processes important for the formation and modification of renewable plant cell walls which serve as the basis for biomaterial and biofuels. The symposium was attended by both senior investigators in the field as well as students including a total attendance of 103, which included 80 faculty/research scientists, 11 graduate students and 12 Postdoctoral students.

  3. Artificial chemical and magnetic structure at the domain walls of an epitaxial oxide

    Science.gov (United States)

    Farokhipoor, S.; Magén, C.; Venkatesan, S.; Íñiguez, J.; Daumont, C. J. M.; Rubi, D.; Snoeck, E.; Mostovoy, M.; de Graaf, C.; Müller, A.; Döblinger, M.; Scheu, C.; Noheda, B.

    2014-11-01

    Progress in nanotechnology requires new approaches to materials synthesis that make it possible to control material functionality down to the smallest scales. An objective of materials research is to achieve enhanced control over the physical properties of materials such as ferromagnets, ferroelectrics and superconductors. In this context, complex oxides and inorganic perovskites are attractive because slight adjustments of their atomic structures can produce large physical responses and result in multiple functionalities. In addition, these materials often contain ferroelastic domains. The intrinsic symmetry breaking that takes place at the domain walls can induce properties absent from the domains themselves, such as magnetic or ferroelectric order and other functionalities, as well as coupling between them. Moreover, large domain wall densities create intense strain gradients, which can also affect the material's properties. Here we show that, owing to large local stresses, domain walls can promote the formation of unusual phases. In this sense, the domain walls can function as nanoscale chemical reactors. We synthesize a two-dimensional ferromagnetic phase at the domain walls of the orthorhombic perovskite terbium manganite (TbMnO3), which was grown in thin layers under epitaxial strain on strontium titanate (SrTiO3) substrates. This phase is yet to be created by standard chemical routes. The density of the two-dimensional sheets can be tuned by changing the film thickness or the substrate lattice parameter (that is, the epitaxial strain), and the distance between sheets can be made as small as 5 nanometres in ultrathin films, such that the new phase at domain walls represents up to 25 per cent of the film volume. The general concept of using domain walls of epitaxial oxides to promote the formation of unusual phases may be applicable to other materials systems, thus giving access to new classes of nanoscale materials for applications in nanoelectronics and

  4. Simulations of super-structure domain walls in two dimensional assemblies of magnetic nanoparticles

    DEFF Research Database (Denmark)

    Jordanovic, Jelena; Beleggia, Marco; Schiøtz, Jakob

    2015-01-01

    We simulate the formation of domain walls in two-dimensional assemblies of magnetic nanoparticles. Particle parameters are chosen to match recent electron holography and Lorentz microscopy studies of almost monodisperse cobalt nanoparticles assembled into regular, elongated lattices...... taking the role of the atomic spins. The coupling is, however, different. The superspins interact only by dipolar interactions as exchange coupling between individual nanoparticles may be neglected due to interparticle spacing. We observe that it is energetically favorable to introduce domain walls...... oriented along the long dimension of nanoparticle assemblies rather than along the short dimension. This is unlike what is typically observed in continuous magnetic materials, where the exchange interaction introduces an energetic cost proportional to the area of the domain walls. Structural disorder...

  5. Irradiation creep lifetime analysis on first wall structure materials for CFETR

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Bing; Peng, Lei, E-mail: penglei@ustc.edu.cn; Zhang, Xiansheng; Shi, Jingyi; Zhan, Jie

    2017-05-15

    Fusion reactor first wall services on the conditions of high surface heat flux and intense neutron irradiation. For China Fusion Engineering Test Reactor (CFETR) with high duty time factor, it is important to analyze the irradiation effect on the creep lifetime of the main candidate structure materials for first wall, i.e. ferritic/martensitic steel, austenite steel and oxide dispersion strengthened steel. The allowable irradiation creep lifetime was evaluated with Larson-Miller Parameter (LMP) model and finite element method. The results show that the allowable irradiation creep lifetime decreases with increasing of surface heat flux, first wall thickness and inlet coolant temperature. For the current CFETR conceptual design, the lifetime is not limited by thermal creep or irradiation creep, which indicated the room for design parameters optimization.

  6. The TOR Pathway Modulates the Structure of Cell Walls in Arabidopsis[W

    Science.gov (United States)

    Leiber, Ruth-Maria; John, Florian; Verhertbruggen, Yves; Diet, Anouck; Knox, J. Paul; Ringli, Christoph

    2010-01-01

    Plant cell growth is limited by the extension of cell walls, which requires both the synthesis and rearrangement of cell wall components in a controlled fashion. The target of rapamycin (TOR) pathway is a major regulator of cell growth in eukaryotes, and inhibition of this pathway by rapamycin reduces cell growth. Here, we show that in plants, the TOR pathway affects cell wall structures. LRR-extensin1 (LRX1) of Arabidopsis thaliana is an extracellular protein involved in cell wall formation in root hairs, and lrx1 mutants develop aberrant root hairs. rol5 (for repressor of lrx1) was identified as a suppressor of lrx1. The functionally similar ROL5 homolog in yeast, Ncs6p (needs Cla4 to survive 6), was previously found to affect TOR signaling. Inhibition of TOR signaling by rapamycin led to suppression of the lrx1 mutant phenotype and caused specific changes to galactan/rhamnogalacturonan-I and arabinogalactan protein components of cell walls that were similar to those observed in the rol5 mutant. The ROL5 protein accumulates in mitochondria, a target of the TOR pathway and major source of reactive oxygen species (ROS), and rol5 mutants show an altered response to ROS. This suggests that ROL5 might function as a mitochondrial component of the TOR pathway that influences the plant's response to ROS. PMID:20530756

  7. The TOR pathway modulates the structure of cell walls in Arabidopsis.

    Science.gov (United States)

    Leiber, Ruth-Maria; John, Florian; Verhertbruggen, Yves; Diet, Anouck; Knox, J Paul; Ringli, Christoph

    2010-06-01

    Plant cell growth is limited by the extension of cell walls, which requires both the synthesis and rearrangement of cell wall components in a controlled fashion. The target of rapamycin (TOR) pathway is a major regulator of cell growth in eukaryotes, and inhibition of this pathway by rapamycin reduces cell growth. Here, we show that in plants, the TOR pathway affects cell wall structures. LRR-extensin1 (LRX1) of Arabidopsis thaliana is an extracellular protein involved in cell wall formation in root hairs, and lrx1 mutants develop aberrant root hairs. rol5 (for repressor of lrx1) was identified as a suppressor of lrx1. The functionally similar ROL5 homolog in yeast, Ncs6p (needs Cla4 to survive 6), was previously found to affect TOR signaling. Inhibition of TOR signaling by rapamycin led to suppression of the lrx1 mutant phenotype and caused specific changes to galactan/rhamnogalacturonan-I and arabinogalactan protein components of cell walls that were similar to those observed in the rol5 mutant. The ROL5 protein accumulates in mitochondria, a target of the TOR pathway and major source of reactive oxygen species (ROS), and rol5 mutants show an altered response to ROS. This suggests that ROL5 might function as a mitochondrial component of the TOR pathway that influences the plant's response to ROS.

  8. Silica nanocasts of wood fibers: a study of cell-wall accessibility and structure.

    Science.gov (United States)

    Persson, Per Valdemar; Hafrén, Jonas; Fogden, Andrew; Daniel, Geoffrey; Iversen, Tommy

    2004-01-01

    The porosity and the available surface area of a lignocellulosic fiber can influence the accessibility and reactivity in derivatization and modification reactions because the porous cell-wall network determines the upper size limit for molecules that can penetrate and react with the interior of the wall. To obtain information concerning the accessibility of the porous cell wall of wood fibers, surfactant-templated sol-gel mineralization has been examined. Wood and kraft pulp samples of Norway spruce were impregnated with a silica sol-gel and subsequently heated (calcined) and transformed into structured mesoporous silica. Microscopy studies (environmental scanning electron microscopy, transmission electron microsopy, TEM) on the silica casts showed that the three-dimensional architecture of the wood and pulp fiber cell wall was revealed down to the nanometer level. Image analysis of TEM micrographs of silica fragments from the never-dried pulp revealed complete infiltration of the cell-wall voids and microcavities (mean pore width 4.7 +/- 2 nm) by the sol-gel and the presence of cellulose fibrils with a width of 3.6 +/- 1 nm. Cellulose fibrils of the same width as that shown by image analysis were also identified by nitrogen adsorption measurements of the pore size distribution in the replicas.

  9. Methods of Parametric Optimization of Thin-Walled Structures and Parameters which Influence on it

    Directory of Open Access Journals (Sweden)

    Kibkalo Anton

    2016-01-01

    Full Text Available The question of efficiency of thin-walled structures contains a number of contradictions. You need to select the best from all the existing structures on the criteria of optimization options. The search is conducted by varying of the parameters at parametric optimization. As a rule the aim of building structure optimization is reducing of material consumption, the labor input and cost. The costs of a particular variant of construction most full describes the given cost. There are two types of optimization parameters - immutable and varying. The result of the optimization of thin-walled beams will be a combination of parameters for each design situation in which provides the required strength and the minimum of the objective function - factory cost of production

  10. Structural studies of complex carbohydrates of plant cell walls. Progress report, June 15, 1992--June 14, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Darvill, A.G.

    1994-10-01

    This report contains the abstracts of fourteen papers published, in press, or in preparation reporting on research activities to investigate the structure, as well as the function of cell walls in plants. This document also contains research on methods to determine the structure of complex carbohydrates of the cell walls.

  11. Angiosperm wood structure: Global patterns in vessel anatomy and their relation to wood density and potential conductivity.

    Science.gov (United States)

    Zanne, Amy E; Westoby, Mark; Falster, Daniel S; Ackerly, David D; Loarie, Scott R; Arnold, Sarah E J; Coomes, David A

    2010-02-01

    Woody stems comprise a large biological carbon fraction and determine water transport between roots and leaves; their structure and function can influence both carbon and hydrological cycles. While angiosperm wood anatomy and density determine hydraulic conductivity and mechanical strength, little is known about interrelations across many species. We compiled a global data set comprising two anatomical traits for 3005 woody angiosperms: mean vessel lumen area (Ā) and number per unit area (N). From these, we calculated vessel lumen fraction (F = ĀN) and size to number ratio (S = Ā/N), a new vessel composition index. We examined the extent to which F and S influenced potential sapwood specific stem conductivity (K(S)) and wood density (D; dry mass/fresh volume). F and S varied essentially independently across angiosperms. Variation in K(S) was driven primarily by S, and variation in D was virtually unrelated to F and S. Tissue density outside vessel lumens (D(N)) must predominantly influence D. High S should confer faster K(S) but incur greater freeze-thaw embolism risk. F should also affect K(S), and both F and D(N) should influence mechanical strength, capacitance, and construction costs. Improved theory and quantification are needed to better understand ecological costs and benefits of these three distinct dimensions.

  12. Peptidoglycan at its peaks: how chromatographic analyses can reveal bacterial cell-wall structure and assembly

    Science.gov (United States)

    Desmarais, Samantha M.; De Pedro, Miguel A.; Cava, Felipe; Huang, Kerwyn Casey

    2013-01-01

    The peptidoglycan (PG) cell wall is a unique macromolecule responsible for both shape determination and cellular integrity under osmotic stress in virtually all bacteria. A quantitative understanding of the relationships between PG architecture, morphogenesis, immune system activation, and pathogenesis can provide molecular-scale insights into the function of proteins involved in cell-wall synthesis and cell growth. High Performance Liquid Chromatography (HPLC) has played an important role in our understanding of the structural and chemical complexity of the cell wall by providing an analytical method to quantify differences in chemical composition. Here, we present a primer on the basic chemical features of wall structure that can be revealed through HPLC, along with a description of the applications of HPLC PG analyses for interpreting the effects of genetic and chemical perturbations to a variety of bacterial species in different environments. We describe the physical consequences of different PG compositions on cell shape, and review complementary experimental and computational methodologies for PG analysis. Finally, we present a partial list of future targets of development for HPLC and related techniques. PMID:23679048

  13. Sensitivity of dual-wall structures under hypervelocity impact to multi-layer thermal insulation thickness and placement

    Science.gov (United States)

    Schonberg, William P.

    1993-01-01

    Results are presented from an experimental study in which Al dual-wall structures were tested, under various high-speed impact conditions, with a view to the effect of multilayer insulation thickness and location on perforation resistance. Attention is given to comparisons of the damage sustained by dual-wall systems with multilayer insulation blankets of various thicknesses and at various locations within the dual-wall system, under comparable impact loading conditions. The placement of the insulation has a significant effect on the ballistic limit of the dual-wall structures considered, while reducing insulation thickness by as much as a third did not.

  14. Chemical and Structural Differences in Cell Wall Polysaccharides of Two Monokaryotic Strains and Their Resulting Dikaryon of Agaricus bisporus

    Science.gov (United States)

    Garcia Mendoza C; Perez Cabo A; Calonje; Galan; Novaes-Ledieu

    1996-10-01

    Compatible monokaryotic strains of Agaricus bisporus ATCC 36975 and 36976 and the resulting dikaryon of their mating were grown in a liquid medium, and their respective cell walls were prepared. Significant differences were not found in the gross chemical composition of the three hyphal types. However, the neutral carbohydrate composition of the complete walls and their fractions was found to be somewhat different in each strain. More consistent differences were encountered in the chemical structure of the distinct polysaccharidic wall fractions in the three types of organisms. Some of these structural wall differences can be considered as characteristic markers for differentiating the mono- and dikaryotic types of A. bisporus.

  15. Pebble bed structures in the vicinity of concave and convex walls

    Energy Technology Data Exchange (ETDEWEB)

    Reimann, Joerg, E-mail: reimann-langhans@web.de [Karlsruhe Institute of Technology, Karlsruhe (Germany); Brun, Emmanuel [European Synchrotron Radiation Facility, Grenoble (France); Ludwig-Maximilians-University, Garching (Germany); Ferrero, Claudio [European Synchrotron Radiation Facility, Grenoble (France); Vicente, Jérôme [Polytech Marseille, Marseille (France)

    2015-10-15

    Highlights: • Detailed tomography experiments were performed to study the packing structure close to concave and convex walls. • A model for arbitrary container geometries is proposed to predict the inner packing factor based on the known total packing factor. • The results are important for the design of ceramic breeder blankets. • The results are relevant for models describing the thermo-mechanical interaction of pebble beds with the blanket structure. - Abstract: Computed tomography experiments were performed with mostly spherical particles in containers with concave, plane and convex walls. Regular pebble packings exist also close to convex cylindrical walls even if the cylinder-to-pebble diameter ratio is about 1, characteristic of thermocouples within the pebble bed. A model for arbitrary container shapes is proposed which predicts the inner packing factor based on the known total packing factor. With increasing vibration efficiency the total packing factor rises because the zones with structured packing increase. Depending on container dimensions, a structured packing can occur in the total pebble bed. Large packing factors are desirable, however, these pebble beds can probably no longer be considered as isotropic with respect to thermo-mechanic properties.

  16. Arabidopsis seed coat mucilage is a specialized cell wall that can be used as a model for genetic analysis of plant cell wall structure and function

    Directory of Open Access Journals (Sweden)

    George Wentzel Haughn

    2012-04-01

    Full Text Available Arabidopsis seed coat epidermal cells produce a large quantity of mucilage that is extruded upon exposure to water. Chemical analyses and cell biological techniques suggest that this mucilage represents a specialized type of secondary cell wall composed primarily of pectin with lesser amounts of cellulose and xyloglucan. Once extruded, the mucilage capsule has a distinctive structure with an outer non-adherent layer that is easily removed by shaking in water, and an inner adherent layer that can only be removed with strong acid or base. Most of the cellulose in the mucilage is present in the inner layer and is responsible at least in part for its adherence to the seed. There are also differences in the pectin composition between the two layers that could contribute to the difference in adherence. The Arabidopsis seed coat epidermis and its mucilage are not essential for seed viability or germination. This dispensability, combined with the fact that the epidermal cells synthesize an accessible pectin-rich cell wall at a specific time in development, makes them well suited as a genetic model for studying cell wall biogenesis, function and regulation. Mutants defective in seed mucilage identified by both forward and reverse genetic analyses are proving useful in establishing connections between carbohydrate structure and cell wall properties in vivo. In the future, genetic engineering of seed coat mucilage carbohydrates should prove useful for testing hypotheses concerning cell wall structure and function.

  17. Electromagnetic Simulations of Dielectric Wall Accelerator Structures for Electron Beam Acceleration

    CERN Document Server

    Nelson, Scott D

    2005-01-01

    Dielectric Wall Accelerator (DWA) technology incorporates the energy storage mechanism, the switching mechanism, and the acceleration mechanism for electron beams. Electromagnetic simulations of DWA structures includes these effects and also details of the switch configuration and how that switch time affects the electric field pulse which accelerates the particle beam. DWA structures include both bi-linear and bi-spiral configurations with field gradients on the order of 20MV/m and the simulations include the effects of the beampipe, the beampipe walls, the DWA High Gradient Insulator (HGI) insulating stack, wakefield impedance calculations, and test particle trajectories with low emittance gain. Design trade-offs include the transmission line impedance (typically a few ohms), equilibration ring optimization, driving switch inductances, and a layer-to-layer coupling analysis and its affect on the pulse rise time.

  18. Micro laser metal wire deposition for additive manufacturing of thin-walled structures

    Science.gov (United States)

    Demir, Ali Gökhan

    2018-01-01

    In this work, the micro laser metal wire deposition (μLMWD) process is studied as an additive manufacturing process for manufacturing thin walled structures with high aspect ratio. The developed μLMWD system consisted of a flash-pumped Nd:YAG laser source operating with ms-long pulses and an in-house developed wire feeding system. Processing conditions were investigated for single and multi-layer deposition in terms of geometry, microhardness and material use efficiency. Thin-walled structures with aspect ratio up to 20 were manufactured successfully, where layer width was between 700 and 800 μm. In multi-layer deposition conditions, the material use efficiency was observed to be close to 100%. The microhardness over the build direction was homogenous. The results show that the μLMWD process yields geometrical resolution close to powder-bed additive manufacturing processes, while maintaining the benefits of using wire feedstock.

  19. The probabilistic structural integrity assessment of reactor pressure vessels under pressurized thermal shock loading

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Mingya, E-mail: chenmingya@cgnpc.com.cn [Suzhou Nuclear Power Research Institute, 215004 Suzhou, Jiangsu Province (China); Lu, Feng; Wang, Rongshan; Yu, Weiwei [Suzhou Nuclear Power Research Institute, 215004 Suzhou, Jiangsu Province (China); Wang, Donghui [State Nuclear Power Plant Service Company, 200237 Shanghai (China); Zhang, Guodong; Xue, Fei [Suzhou Nuclear Power Research Institute, 215004 Suzhou, Jiangsu Province (China)

    2015-12-01

    Highlights: • The methodology and the case study of the FAVOR software were shown. • The over-conservative parameters in the DFM were shown. • The differences between the PFM and the DFM were discussed. • The limits in the current FAVOR were studied. - Abstract: The pressurized thermal shock (PTS) event poses a potentially significant challenge to the structural integrity of the reactor pressure vessel (RPV) during the long time operation (LTO). In the USA, the “screening criteria” for maximum allowable embrittlement of RPV material, which forms part of the USA regulations, is based on the probabilistic fracture mechanics (PFM). The FAVOR software developed by Oak Ridge National Laboratory (ORNL) is used to establish the regulation. As the technical basis of FAVOR is not the most widely-used and codified methodologies, such as the ASME and RCC-M codes, in most countries (with exception of the USA), proving RPV integrity under the PTS load is still based on the deterministic fracture mechanics (DFM). As the maximum nil-ductility-transition temperature (RT{sub NDT}) of the beltline material for the 54 French RPVs after 40 years operation is higher than the critical values in the IAEA-TECDOC-1627 and European NEA/CSNI/R(99)3 reports (while still obviously lower than the “screening criteria” of the USA), it may conclude that the RPV will not be able to run in the LTO based on the DFM. In the FAVOR, the newest developments of fracture mechanics are applied, such as the warm pre-stress (WPS) effect, more accurate estimation of the flaw information and less conservation of the toughness (such as the three-parameter Weibull distribution of the fracture toughness). In this paper, the FAVOR software is first applied to show both the methodology and the results of the PFM, and then the limits in the current FAVOR software (Version 6.1, which represents the baseline for re-assessing the regulation of 10 CFR 50.61), lack of the impact of the constraint effect

  20. Reconfigurable logic via gate controlled domain wall trajectory in magnetic network structure

    OpenAIRE

    Murapaka, C.; P Sethi; Goolaup, S.; Lew, W. S.

    2016-01-01

    An all-magnetic logic scheme has the advantages of being non-volatile and energy efficient over the conventional transistor based logic devices. In this work, we present a reconfigurable magnetic logic device which is capable of performing all basic logic operations in a single device. The device exploits the deterministic trajectory of domain wall (DW) in ferromagnetic asymmetric branch structure for obtaining different output combinations. The programmability of the device is achieved by us...

  1. Fluid-structure-interaction analysis for welded pipes with flow-accelerated corrosion wall thinning

    Energy Technology Data Exchange (ETDEWEB)

    Sun, L.; Ding, Y., E-mail: lan.sun@cnl.ca [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada)

    2016-06-15

    The flow-accelerated corrosion (FAC) entrance effect results in enhanced wall thinning immediately downstream of a weld if the weld connects an upstream FAC-resistant material with a downstream less resistant material. The weld regions, especially those with local repairs, are susceptible to cracking due to the high residual stresses induced by fabrication. The combined effects of the FAC entrance effect and high stresses at a weld might compromise the structural integrity of the piping and lead to a failure. Weld degradation by FAC entrance effect has been observed at nuclear and fossil power plants. This paper describes an application using fluid-structure-interaction (FSI) modelling to study the combined effects of FAC wall thinning, weld residual stresses, and in-service loads on welded structures. Simplified cases analyzed were based on CANDU outlet feeder conditions. The analysis includes the flow and mass transfer modelling of the FAC entrance effect using computational fluid dynamics (CFD) and nonlinear structural analyses of the welded structures with wall thinning and an assumed weld residual stress and strain distribution. The FSI analyses were performed using ANSYS Workbench, an integrated platform that enables the coupling of CFD and structural analysis solutions. The obtained results show that the combination of FAC, weld residual stresses, in-service loads (including the internal pressure) and (or) extreme loads could cause high stresses and affect the integrity of the welded pipes. The present work demonstrated that the FSI modelling can be used as an effective approach to assess the integrity of welded structures. (author)

  2. Automatic analysis of image of surface structure of cell wall-deficient EVC.

    Science.gov (United States)

    Li, S; Hu, K; Cai, N; Su, W; Xiong, H; Lou, Z; Lin, T; Hu, Y

    2001-01-01

    Some computer applications for cell characterization in medicine and biology, such as analysis of surface structure of cell wall-deficient EVC (El Tor Vibrio of Cholera), operate with cell samples taken from very small areas of interest. In order to perform texture characterization in such an application, only a few texture operators can be employed: the operators should be insensitive to noise and image distortion and be reliable in order to estimate texture quality from images. Therefore, we introduce wavelet theory and mathematical morphology to analyse the cellular surface micro-area image obtained by SEM (Scanning Electron Microscope). In order to describe the quality of surface structure of cell wall-deficient EVC, we propose a fully automatic computerized method. The image analysis process is carried out in two steps. In the first, we decompose the given image by dyadic wavelet transform and form an image approximation with higher resolution, by doing so, we perform edge detection of given images efficiently. In the second, we introduce many operations of mathematical morphology to obtain morphological quantitative parameters of surface structure of cell wall-deficient EVC. The obtained results prove that the method can eliminate noise, detect the edge and extract the feature parameters validly. In this work, we have built automatic analytic software named "EVC.CELL".

  3. Sensitivity to fuel diesel oil and cell wall structure of some Scenedesmus (Chlorococcales strains

    Directory of Open Access Journals (Sweden)

    Zbigniew Tukaj

    2014-01-01

    Full Text Available Sensitivity of three Scenedesmus strains exposed to aqueous fuel-oil extract (AFOE is strongly strain-dependent S. quadricauda is the most resistant, S. armatus moderately tolerant whereas the most sensitive appears to be S. microspina. The sensitivity of tested species increases parallel with decreasing of cell size and cell number in coenobium. The values of the cell surface/cell volumes ratios only partly explain the above relationships. Electron microscope investigations reveal that the sensitivity may depend on cell wall structure of the strains. Cell wall of all here investigated strains is built of two layers: the inner so-called cellulosic layer and the outer one showing a three-laminar structure (TLS. The latter contains an acetolysis-resistant biopolymer (ARB. These two layers are similar in thickness in the three strains tested, but the surface of Scenedesmus is covered with various epistructures that are characteristic of strains. Some of them as the tightly fitting warty layer of S. armatus and especially the loosely fitting reticulate layer of S. quadricauda may contribute to lower permeability of cell wall. The structure of the rosettes also appears to be correlated with the sensitivity of strains. Presence of invaginations of plasmalemma in areas under rosettes indicates their role in transport processes inside/outside the cells.

  4. Seismic Failure Mechanism of Reinforced Cold-Formed Steel Shear Wall System Based on Structural Vulnerability Analysis

    Directory of Open Access Journals (Sweden)

    Jihong Ye

    2017-02-01

    Full Text Available A series of structural vulnerability analyses are conducted on a reinforced cold-formed steel (RCFS shear wall system and a traditional cold-formed steel (CFS shear wall system subjected to earthquake hazard based on forms in order to investigate their failure mechanisms. The RCFS shear wall adopts rigid beam-column joints and continuous concrete-filled CFS tube end studs rather than coupled-C section end studs that are used in traditional CFS shear walls, to achieve the rigid connections in both beam-column joints and column bases. The results show that: the RCFS and traditional CFS shear wall systems both exhibit the maximum vulnerability index associated with the failure mode in the first story. Therefore, the first story is likely to be a weakness of the CFS shear wall system. Once the wall is damaged, the traditional CFS shear wall system would collapse because the shear wall is the only lateral-resisting component. However, the collapse resistance of the RCFS shear wall system is effectively enhanced by the second defense, which is provided by a framework integrated by rigid beam-column joints and fixed column bases. The predicted collapse mode with maximum vulnerability index that was obtained by structural vulnerability analysis agrees well with the experimental result, and the structural vulnerability method is thereby verified to be reasonable to identify the weaknesses of framed structures and predict their collapse modes. Additionally, the quantitative vulnerability index indicates that the RCFS shear wall system exhibits better robustness compared to the traditional one. Furthermore, the “strong frame weak wallboard” and the “strong column weak beam” are proposed in this study as conceptional designations for the RCFS shear wall systems.

  5. Out-of-plane chiral domain wall spin-structures in ultrathin in-plane magnets

    Science.gov (United States)

    Chen, Gong; Kang, Sang Pyo; Ophus, Colin; N'diaye, Alpha T.; Kwon, Hee Young; Qiu, Ryan T.; Won, Changyeon; Liu, Kai; Wu, Yizheng; Schmid, Andreas K.

    2017-05-01

    Chiral spin textures in ultrathin films, such as skyrmions or chiral domain walls, are believed to offer large performance advantages in the development of novel spintronics technologies. While in-plane magnetized films have been studied extensively as media for current- and field-driven domain wall dynamics with applications in memory or logic devices, the stabilization of chiral spin textures in in-plane magnetized films has remained rare. Here we report a phase of spin structures in an in-plane magnetized ultrathin film system where out-of-plane spin orientations within domain walls are stable. Moreover, while domain walls in in-plane films are generally expected to be non-chiral, we show that right-handed spin rotations are strongly favoured in this system, due to the presence of the interfacial Dzyaloshinskii-Moriya interaction. These results constitute a platform to explore unconventional spin dynamics and topological phenomena that may enable high-performance in-plane spin-orbitronics devices.

  6. Anatomical structure and ultrastructure of the endocarp cell walls of Argania spinosa (L.) Skeels (Sapotaceae).

    Science.gov (United States)

    Sebaa, H S; Harche, M Kaid

    2014-12-01

    The anatomical and histochemical study of young and adult endocarps of Argania spinosa (sampled from Tindouf; Algeria) shows a general structure that is similar to that of majority of stone fruits. These samples consist of tissues that contain lignified and cellulosic cell walls. The majority of the tissues are composed of sclerenchyma cells; with very thick lignified cell walls and conducting tissues. Coniferyl lignins are abundant in the majority of the lignified tissues. However, the coniferyl lignins appear at the primary xylem during lignification. Syringyl lignins are present in small quantities. The electron microscopy observation of the sclerenchyma cell walls of the young endocarp shows polylamellate strates and, cellular microfibrils in arced patterns. This architecture is observed in the cell walls of the adult endocarp only after the incubation of the tissue in methylamine. These configurations (arcs) are the result of a regular and complete rotation with a 180° variation in the microfibril angle; the complete and symmetrical arcs show a helicoidal mode of construction. The observation of the sclerenchyma cells revealed the capacity of helicoidal morphogenesis to adjust itself under the influence of topological constraints, such as the presence of a large number of pit canals, which maintain symplastic transport. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Rocket-inspired tubular catalytic microjets with grating-structured walls as guiding empennages.

    Science.gov (United States)

    Huang, Gaoshan; Wang, Jiyuan; Liu, Zhaoqian; Zhou, Dekai; Tian, Ziao; Xu, Borui; Li, Longqiu; Mei, Yongfeng

    2017-12-07

    Controllable locomotion in the micro-/nanoscale is challenging and attracts increasing research interest. Tubular microjets self-propelled by microbubbles are intensively investigated due to their high energy conversion efficiency, but the imperfection of the tubular geometry makes it harder to realize linear motion. Inspired by the macro rocket, we designed a tubular microjet with a grating-structured wall which mimics the guiding empennage of the macro rocket, and we found that the fluid can be effectively guided by the grooves. Both theoretical simulation and experimental work have been carried out, and the obtained results demonstrate that the stability margin of the grating-structured microjet can be enhanced. Compared with microjets with smooth walls, the structured microjets show an enhanced ability of moving linearly. In 10% H 2 O 2 , only 20% of the smooth microjets demonstrate linear trajectories, while 80% of the grating-structured microjets keep moving straight. The grating-structured microjet can maintain linear motion under external disturbance. We further propose to increase the stability by introducing a helical grating structure.

  8. Interactive Physical Simulation of Catheter Motion within Mayor Vessel Structures and Cavities for ASD/VSD Treatment

    Science.gov (United States)

    Becherer, Nico; Hesser, Jürgen; Kornmesser, Ulrike; Schranz, Dietmar; Männer, Reinhard

    2007-03-01

    Simulation systems are becoming increasingly essential in medical education. Hereby, capturing the physical behaviour of the real world requires a sophisticated modelling of instruments within the virtual environment. Most models currently used are not capable of user interactive simulations due to the computation of the complex underlying analytical equations. Alternatives are often based on simplifying mass-spring systems, being able to deliver high update rates that come at the cost of less realistic motion. In addition, most techniques are limited to narrow and tubular vessel structures or restrict shape alterations to two degrees of freedom, not allowing instrument deformations like torsion. In contrast, our approach combines high update rates with highly realistic motion and can in addition be used with respect to arbitrary structures like vessels or cavities (e.g. atrium, ventricle) without limiting the degrees of freedom. Based on energy minimization, bending energies and vessel structures are considered as linear elastic elements; energies are evaluated at regularly spaced points on the instrument, while the distance of the points is fixed, i.e. we simulate an articulated structure of joints with fixed connections between them. Arbitrary tissue structures are modeled through adaptive distance fields and are connected by nodes via an undirected graph system. The instrument points are linked to nodes by a system of rules. Energy minimization uses a Quasi Newton method without preconditioning and, hereby, gradients are estimated using a combination of analytical and numerical terms. Results show a high quality in motion simulation when compared to a phantom model. The approach is also robust and fast. Simulating an instrument with 100 joints runs at 100 Hz on a 3 GHz PC.

  9. Optimal Shakedown of the Thin-Wall Metal Structures Under Strength and Stiffness Constraints

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    Alawdin Piotr

    2017-06-01

    Full Text Available Classical optimization problems of metal structures confined mainly with 1st class cross-sections. But in practice it is common to use the cross-sections of higher classes. In this paper, a new mathematical model for described shakedown optimization problem for metal structures, which elements are designed from 1st to 4th class cross-sections, under variable quasi-static loads is presented. The features of limited plastic redistribution of forces in the structure with thin-walled elements there are taken into account. Authors assume the elastic-plastic flexural buckling in one plane without lateral torsional buckling behavior of members. Design formulae for Methods 1 and 2 for members are analyzed. Structures stiffness constrains are also incorporated in order to satisfy the limit serviceability state requirements. With the help of mathematical programming theory and extreme principles the structure optimization algorithm is developed and justified with the numerical experiment for the metal plane frames.

  10. Open and closed shear-walls in high-rise structural systems: Static and dynamic analysis

    Science.gov (United States)

    Carpinteri, Alberto; Lacidogna, Giuseppe; Nitti, Giuseppe

    2016-06-01

    In the present paper, a General Algorithm is applied to the analysis of high-rise structures. This algorithm is to be used as a calculation tool in preliminary design; it allows to define the interaction between closed and open, straight or curved shear-walls, and the forces exchanged in structures subject to mainly horizontal loads. The analysis can be performed in both static and dynamic regimes, the mode shapes and the natural frequencies being assessed. This general formulation allows analyses of high-rise structures by taking into account the torsional rigidity and the warping deformations of the elements composing the building without gross simplifications. In thisway it is possible to model the structure as a single equivalent cantilever, thus minimising the degrees of freedom of the system, and consequently the calculation time. Finally, potentials of the method proposed are demonstrated by a numerical example which emphasizes the link between global displacements and stresses in the elements composing the structure.

  11. Recent progress on the structure separation of single-wall carbon nanotubes

    Science.gov (United States)

    Cui, Jiaming; Yang, Dehua; Zeng, Xiang; Zhou, Naigen; Liu, Huaping

    2017-11-01

    The mass production of single-structure, single-wall carbon nanotubes (SWCNTs) with identical properties is critical for their basic research and technical applications in the fields of electronics, optics and optoelectronics. Great efforts have been made to control the structures of SWCNTs since their discovery. Recently, the structure separation of SWCNTs has been making great progress. Various solution-sorting methods have been developed to achieve not only the separation of metallic and semiconducting species, but also the sorting of distinct (n, m) single-chirality species and even their enantiomers. This progress would dramatically accelerate the application of SWCNTs in the next-generation electronic devices. Here, we review the recent progress in the structure sorting of SWCNTs and outline the challenges and prospects of the structure separation of SWCNTs.

  12. An in vivo pilot study of a microporous thin film nitinol-covered stent to assess the effect of porosity and pore geometry on device interaction with the vessel wall.

    Science.gov (United States)

    Chun, Youngjae; Kealey, Colin P; Levi, Daniel S; Rigberg, David A; Chen, Yanfei; Tillman, Bryan W; Mohanchandra, K P; Shayan, Mahdis; Carman, Gregory P

    2017-03-01

    Sputter-deposited thin film nitinol constructs with various micropatterns were fabricated to evaluate their effect on the vessel wall in vivo when used as a covering for commercially available stents. Thin film nitinol constructs were used to cover stents and deployed in non-diseased swine arteries. Swine were sacrificed after approximately four weeks and the thin film nitinol-covered stents were removed for histopathologic evaluation. Histopathology revealed differences in neointimal thickness that correlated with the thin film nitinol micropattern. Devices covered with thin film nitinol with a lateral × vertical length = 20 × 40 µm diamond pattern had minimal neointimal growth with well-organized cell architecture and little evidence of ongoing inflammation. Devices covered with thin film nitinol with smaller fenestrations exhibited a relatively thick neointimal layer with inflammation and larger fenestrations showed migration of inflammatory and smooth muscle cells through the micro fenestrations. This "proof-of-concept" study suggests that there may be an ideal thin film nitinol porosity and pore geometry to encourage endothelialization and incorporation of the device into the vessel wall. Future work will be needed to determine the optimal pore size and geometry to minimize neointimal proliferation and in-stent stenosis.

  13. Vessel grouping patterns in subfamilies Apocynoideae and Periplocoideae confirm phylogenetic value of wood structure within Apocynaceae.

    Science.gov (United States)

    Lens, Frederic; Endress, Mary E; Baas, Pieter; Jansen, Steven; Smets, Erik

    2009-12-01

    This study contributes to our understanding of the phylogenetic significance and major evolutionary trends in the wood of the dogbane family (Apocynaceae), one of the largest and economically most important angiosperm families. Based on LM and SEM observations of 56 Apocynoideae species-representing all currently recognized tribes-and eight Periplocoideae, we found striking differences in vessel grouping patterns (radial multiples vs. large clusters) between the mainly nonclimbing apocynoid tribes (Wrightieae, Malouetieae, Nerieae) and the climbing lineages (remaining Apocynoideae and Periplocoideae). The presence of large vessel clusters in combination with fibers in the ground tissue characterizing the climbing Apocynoideae and Periplocoideae clearly contrasts with the climbing anatomy of the rauvolfioids (solitary vessels plus tracheids in ground tissue), supporting the view that (1) the climbing habit has evolved more than once in Apocynaceae, (2) the three nonclimbing apocynoid tribes are basal compared to the climbing apocynoids, and (3) Periplocoideae belong to the crown clade. The wood anatomy within the nonclimbing and climbing lineages is rather homogeneous, although a combination of specific characters (e.g. presence of septate fibers, axial parenchyma distribution, abundance of uniseriate compared to multiseriate rays, and presence and location of prismatic crystals) may be used to identify several tribes.

  14. Effect of a tunnel-structured β-tricalcium phosphate graft material on periodontal regeneration: a pilot study in a canine one-wall intrabony defect model.

    Science.gov (United States)

    Matsuura, T; Akizuki, T; Hoshi, S; Ikawa, T; Kinoshita, A; Sunaga, M; Oda, S; Kuboki, Y; Izumi, Y

    2015-06-01

    Tissue regeneration is affected by the porosity, chemical properties and geometric structure of graft materials. Regeneration of severe periodontal defects, such as one-wall intrabony defects, is difficult because of reduced tissue support, and bone grafts are commonly used in such cases. In the present study, a tunnel-structured β-tricalcium phosphate (tunnel β-TCP) graft material designed to stimulate bone formation was fabricated. The objective of this pilot study was to evaluate the effect of this graft material on periodontal regeneration in one-wall intrabony defects in dogs. Six male beagle dogs were used in this study. First, the mandibular second and third incisors were extracted. Experimental surgery was performed 12 wk after tooth extraction. Bilateral 4 × 8 mm (width × depth) one-wall intrabony defects were created in the mesial side of the mandibular canines. At the experimental sites, the defects were filled with tunnel β-TCP, whereas the control defects were left empty. Twelve weeks after surgery, qualitative and quantitative histological analyses were performed. There were no signs of clinical inflammation 12 wk after surgery. Coronal extension indicative of new bone formation was higher at the experimental sites than at the control sites, although the differences between both the sites in the newly formed cementum and connective tissue attachment were not significant. Newly formed periodontal ligament and cementum-like tissue were evident along the root surface at the experimental sites. The inner surface of the tunnels was partially resorbed and replaced with new bone. New blood vessels were observed inside the lumens of tunnel β-TCP. Tunnel β-TCP serves as a scaffold for new bone formation in one-wall intrabony defects. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  15. Sound transmission of cavity walls due to structure borne transmission via point and line connections.

    Science.gov (United States)

    Davy, John L

    2012-08-01

    The author has published equations for predicting the air borne sound transmission of double leaf cavity walls due to the structure borne sound transmission across the air cavity via (possibly resilient) line connections, but has never published the full derivation of these equations. The author also derived equations for the case when the connections are rigid point connections but has never used them or published them or their derivations. This paper will present the full derivation of the author's theory of the air borne sound transmission of double leaf cavity walls due to the structure borne sound transmission across the air cavity via point or line connections which are modeled as four pole networks. The theoretical results will be compared with experimental results on wooden stud cavity walls from the National Research Council of Canada because the screw spacing is given for these results. This enables connections via studs and screws to be modeled as point connections and avoids the need to make any assumptions about the compliance of the equivalent point or line connections.

  16. New Equivalent Linear Impact Model for Simulation of Seismic Isolated Structure Pounding against Moat Wall

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2014-01-01

    Full Text Available Base-isolated buildings subjected to extreme earthquakes or near-fault pulse-like earthquakes can exceed their design gap distance and impact against the surrounding moat wall. Based on equating energy dissipation and maximum collision compression deformation of isolated structure with the Hertz-damp model and Kevin-Voigt model in the process of collision, an equivalent linear impact model (ELIM is proposed to better predict impact response of seismic isolated structure. The formula of the equivalent linear stiffness of ELIM is theoretically derived. The effectiveness of ELIM is verified by comparing the results of numerical analyses with the results of pounding experiments. Four near-fault earthquakes are selected to validate rationality and accuracy of the proposed model using numerical analysis. The results indicate that the proposed linear model can nearly capture impact behavior of isolated structure in simulating the pounding-involved structural response.

  17. Structural and Morphological Investigation for Water-Processed Graphene Oxide/Single-Walled Carbon Nanotubes Hybrids

    Science.gov (United States)

    Muda, M. R.; Ramli, M. M.; Mat Isa, S. S.; Halin, D. S. C.; Talip, L. F. A.; Mazelan, N. S.; Anhar, N. A. M.; Danial, N. A.

    2017-06-01

    New group of materials derived from hybridization of single walled carbon nanotubes (SWCNTs) and graphene oxide (GO) which resulting novel three dimensional (3D) materials generates an outstanding properties compared to corresponding SWCNTs and GO/Graphene. In this paper, we describe a simple approach using water processing method to develop integrated rGO/GO-SWCNT hybrids with different hybrid ratios. The hybrid ratios were varied into three divided ratio and the results were compared between pristine SWCNTs and GO in order to investigate the structural density and morphology of these carbonaceous materials. With an optimized ratio of rGO/GO-SWCNT, the hybrid shows a well-organized hybrid film structures with less defects density sites. The optimized mixture ratio emphasized the important of both rGO and SWCNTs in the hybrid structures. Morphological structural and defects density degrees were examined by Field Emission Scanning Electron Microscopy (FESEM) and Raman spectroscopy.

  18. Structural difference between walls from hemispherical caps and partial septa of Bacillus subtilis.

    Science.gov (United States)

    Fan, D P; Beckman, B E

    1973-05-01

    Walls from partial septa of Bacillus subtilis bacteria are more sensitive than end walls to digestion by B. subtilis autolytic amidase. This result indicates that, after synthesis, B. subtilis septal walls are modified to an amidase-resistant form.

  19. Structure of Cellulose Microfibrils in Primary Cell Walls from Collenchyma1[C][W][OA

    Science.gov (United States)

    Thomas, Lynne H.; Forsyth, V. Trevor; Šturcová, Adriana; Kennedy, Craig J.; May, Roland P.; Altaner, Clemens M.; Apperley, David C.; Wess, Timothy J.; Jarvis, Michael C.

    2013-01-01

    In the primary walls of growing plant cells, the glucose polymer cellulose is assembled into long microfibrils a few nanometers in diameter. The rigidity and orientation of these microfibrils control cell expansion; therefore, cellulose synthesis is a key factor in the growth and morphogenesis of plants. Celery (Apium graveolens) collenchyma is a useful model system for the study of primary wall microfibril structure because its microfibrils are oriented with unusual uniformity, facilitating spectroscopic and diffraction experiments. Using a combination of x-ray and neutron scattering methods with vibrational and nuclear magnetic resonance spectroscopy, we show that celery collenchyma microfibrils were 2.9 to 3.0 nm in mean diameter, with a most probable structure containing 24 chains in cross section, arranged in eight hydrogen-bonded sheets of three chains, with extensive disorder in lateral packing, conformation, and hydrogen bonding. A similar 18-chain structure, and 24-chain structures of different shape, fitted the data less well. Conformational disorder was largely restricted to the surface chains, but disorder in chain packing was not. That is, in position and orientation, the surface chains conformed to the disordered lattice constituting the core of each microfibril. There was evidence that adjacent microfibrils were noncovalently aggregated together over part of their length, suggesting that the need to disrupt these aggregates might be a constraining factor in growth and in the hydrolysis of cellulose for biofuel production. PMID:23175754

  20. Time-frequency and space-wavenumber analysis for damage inspection of thin-walled structures

    Science.gov (United States)

    Pai, P. Frank; Sundaresan, Mannur J.

    2011-04-01

    This paper presents a dynamics-based methodology for accurate damage inspection of thin-walled structures by combining a boundary-effect evaluation method (BEEM) for space-wavenumber analysis of measured operational deflection shapes (ODSs) and a conjugate-pair decomposition (CPD) method for time-frequency analysis of time traces of measured points. BEEM is for locating and estimating small structural damage by processing ODSs measured by a full-field measurement system (e.g., a scanning laser vibrometer or a camera-based motion measurement system). BEEM is a nondestructive spatial-domain method based on area-by-area processing of ODSs and it works without using any structural model or historical data for comparison. Similar to the short-time Fourier transform and wavelet transform, CPD uses adaptive windowed regular harmonics and function orthogonality to perform time-frequency analysis of time traces by extracting time-localized regular and/or distorted harmonics. Both BEEM and CPD are local spectral analysis based on local, adaptive curve fitting. The first estimation of the wavenumber for BEEM and the frequency for CPD is obtained by using a four-point Teager-Kaiser algorithm based on the use of finite difference. Numerical simulations and experimental results show that the combination of BEEM and CPD for space-wavenumber and time-frequency analysis provides an accurate tool for damage inspection of thin-walled structures.

  1. Transport of divalent cations: cation exchange capacity of intact xylem vessels.

    Science.gov (United States)

    Van de Geijn, S C; Petit, C M

    1979-12-01

    The cation exchange capacity of the intact xylem vessels in cut shoots of papyrus (Cyperus papyrus spec.) has been determined. The cation exchange capacity is independent of the cation concentration in the transpiration stream, and is equal for Ca and Co. The high value of the cation exchange capacity (0.6 to 1 x 10(-7) equivalents per square centimeter vessel wall surface) leads to the hypothesis that the porous structure of the vessel wall, and not only the inner vessel wall surface, acts as a cation exchanger.Differences between anion ([(32)P]phosphate, [(45)Ca]EDTA(2-), [(115)Cd(m)]-EDTA(2-)), and cation ([(45)Ca](2+), [(115)Cd(m)](2+)) movement are explained in terms of transport with the transpiration flux or by exchange reactions. The competition between exchange sites and natural or synthetic ligands for the divalent cations is discussed.

  2. Study on the Dynamic Compound Structure Composed of Mast Cells, Blood Vessels, and Nerves in Rat Acupoint

    Directory of Open Access Journals (Sweden)

    Luo Mingfu

    2013-01-01

    Full Text Available Background. Circulation system, immunity system, and nervous system have a close relationship with meridian phenomen. However, there is still lack of the results of dynamic changes of these structures in acupoint. The aim of this study is to explore the interrelationship by composite staining techniques. Methodology/Principal Findings. Twenty rats were separated into electroacupuncture group (EA and control group (Con randomly. In EA group, the Zusanli and Weishu were stimulated with the 0.1 mA for 25 min. The tissue of these acupoints was double-stained with acetylcholinesterase and Toluidine blue. The compound structure of mast cells, nervous fibers, and mast cells in the acupoint was observed. Conclusions/Significance. The blood vessels, mast cells and acetylcholinesterase responded nerves were clearly observed in acupoint tissues. EA can result in the mast cell recruitment and migration along the blood vessels and nervous bundle, which conformed the dynamic compound structure and played important roles in acupuncture.

  3. Structural studies of the rhamnose-rich cell wall polysaccharide of Lactobacillus casei BL23.

    Science.gov (United States)

    Vinogradov, Evgeny; Sadovskaya, Irina; Grard, Thierry; Chapot-Chartier, Marie-Pierre

    2016-11-29

    Lactobacillus casei is a Gram positive lactic acid bacterium used in dairy fermentations and present in the normal human gut microbiota. Certain strains are recognized as probiotics with beneficial effects on human and animal health. L. casei BL23 is a potential probiotic strain endowed with anti-inflammatory properties and a model strain widely used in genetic, physiological and biochemical studies. A number of bacterial cell surface polysaccharides have been shown to play a role in the immune modulation activities observed for probiotic lactic acid bacteria. In the present work, we purified the most abundant carbohydrate polymer of L. casei BL23 cell wall, a neutral wall polysaccharide (WPS) and established its chemical structure by periodate oxidation, methylation analysis and 2D NMR spectroscopy. The WPS of L. casei BL23 was shown to contain α-Rha, α-Glc, β-GlcNAc and β-GalNAc forming a branched heptasaccharide repeating unit (variant 1) with an additional partial substitution with α-Glc (variant 2). A modified non-reducing end octasaccharide, corresponding to a terminal unit of the WPS (variant 3), was also identified and allowed to define the biological repeating unit of the WPS. To our knowledge, this is the first report of the identification of a biological repeating unit based on a chemical evidence, in a cell wall polysaccharide of a Gram positive bacterial species. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Cryopreserved human aortic root allografts arterial wall: Structural changes occurring during thawing.

    Directory of Open Access Journals (Sweden)

    Robert Novotny

    Full Text Available The aim of our experimental work was to assess morphological changes of arterial wall that arise during different thawing protocols of a cryopreserved human aortic root allograft (CHARA arterial wall.The experiment was performed on CHARAs. Two thawing protocols were tested: 1, CHARAs were thawed at a room temperature at +23°C; 2, CHARAs were placed directly into a water bath at +37°C.After fixation, all samples were washed in distilled water for 5 min, and dehydrated in a graded ethanol series (70, 85, 95, and 100% for 5 min at each level. The tissue samples were then immersed in 100% hexamethyldisilazane for 10 minutes and air dried in an exhaust hood at room temperature. Processed samples were mounted on stainless steel stubs, coated with gold.Thawing protocol 1: All 6 (100% samples showed loss of the endothelium and damage to the subendothelial layers with randomly dispersed circular defects and micro-fractures without smooth muscle cells contractions in the tunica media. Thawing protocol 2: All 6 (100% samples showed loss of endothelium from the luminal surface, longitudinal corrugations in the direction of blood flow caused by smooth muscle cells contractions in the tunica media with frequent fractures in the subendothelial layer.All the samples thawed at the room temperature showed smaller structural damage to the CHARA arterial wall with no smooth muscle cell contraction in tunica media when compared to the samples thawed in a water bath.

  5. Spermine Regulates Pollen Tube Growth by Modulating Ca2+-Dependent Actin Organization and Cell Wall Structure

    Science.gov (United States)

    Aloisi, Iris; Cai, Giampiero; Faleri, Claudia; Navazio, Lorella; Serafini-Fracassini, Donatella; Del Duca, Stefano

    2017-01-01

    Proper growth of the pollen tube depends on an elaborate mechanism that integrates several molecular and cytological sub-processes and ensures a cell shape adapted to the transport of gametes. This growth mechanism is controlled by several molecules among which cytoplasmic and apoplastic polyamines. Spermine (Spm) has been correlated with various physiological processes in pollen, including structuring of the cell wall and modulation of protein (mainly cytoskeletal) assembly. In this work, the effects of Spm on the growth of pear pollen tubes were analyzed. When exogenous Spm (100 μM) was supplied to germinating pollen, it temporarily blocked tube growth, followed by the induction of apical swelling. This reshaping of the pollen tube was maintained also after growth recovery, leading to a 30–40% increase of tube diameter. Apical swelling was also accompanied by a transient increase in cytosolic calcium concentration and alteration of pH values, which were the likely cause for major reorganization of actin filaments and cytoplasmic organelle movement. Morphological alterations of the apical and subapical region also involved changes in the deposition of pectin, cellulose, and callose in the cell wall. Thus, results point to the involvement of Spm in cell wall construction as well as cytoskeleton organization during pear pollen tube growth. PMID:29033970

  6. Multi-walled carbon nanotube structural instability with/without metal nanoparticles under electron beam irradiation

    Science.gov (United States)

    Khan, Imran; Huang, Shengli; Wu, Chenxu

    2017-12-01

    The structural transformation of multi-walled carbon nanotubes (MWCNT) under electron beam (e-beam) irradiation at room temperature is studied, with respect to a novel passivation effect due to gold nanoparticles (Au NPs). MWCNT structural evolution induced by energetic e-beam irradiation leads to faster shrinkage, as revealed via in situ transmission electron microscopy, while MWCNT surface modification with Au NPs (Au-MWCNT) slows down the shrinkage by impeding the structural evolution process for a prolonged time under the same irradiation conditions. The new relationship between MWCNT and Au-MWCNT shrinking radii and irradiation time illustrates that the MWCNT shrinkage rate is faster than either theoretical predictions or the same process in Au-MWCNTs. As compared with the outer surface energy (positive curvature), the inner surface energy (negative curvature) of the MWCNT contributes more to the athermal evaporation of tube wall atoms, leading to structural instability and shrinkage under e-beam irradiation. Conversely, Au NPs possess only outer surface energy (positive curvature) compared with the MWCNT. Their presence on MWCNT surfaces retards the dynamics of MWCNT structural evolution by slowing down the evaporation process of carbon atoms, thus restricting Au-MWCNT shrinkage. Au NP interaction and growth evolves athermally on MWCNT surfaces, exhibits increase in their size, and indicates the association of this mechanism with the coalescence induced by e-beam activated electronic excitations. Despite their growth, Au NPs show extreme structural stability, and remain crystalline under prolonged irradiation. It is proposed that the surface energy of MWCNTs and Au NPs, together with e-beam activated soft modes or lattice instability effects, predominantly govern all the above varieties of structural evolution.

  7. Experimental investigation of the unsteady structure of a transitional plane wall jet

    Science.gov (United States)

    Gogineni, S.; Shih, C.

    A laminar wall jet undergoing transition is investigated using the particle image velocimetry (PIV) technique. The plane wall jet is issued from a rectangular channel, with the jet-exit velocity profile being parabolic. The Reynolds number, based on the exit mean velocity and the channel width, is 1450. To aid the understanding of the global flow features, laser-sheet/smoke flow visualizations are performed along streamwise, spanwise, and cross-stream directions. Surface pressure measurements are made to correlate the instantaneous vorticity distribution with the surface pressure fluctuations. The instantaneous velocity and vorticity field measurements provide the basis for understanding the formation of the inner-region vortex and the subsequent interactions between the outer-region (free-shear-layer region) and inner-region (boundary-layer region) vortical structures. Results show that under the influence of the free-shear-layer vortex, the local boundary layer becomes detached from the surface and inviscidly unstable, and a vortex is formed in the inner region. Once this vortex has formed, the free-shear-layer vortex and the inner-region vortex form a vortex couple and convect downstream. The mutual interactions between these inner- and outer-region vortical structures dominate the transition process. Farther downstream, the emergence of the three-dimensional structure in the free shear layer initiates complete breakdown of the flow.

  8. Primary Response Assessment Method for Concept Design of Monotonous Thin-Walled Structures

    Directory of Open Access Journals (Sweden)

    V. Zanic

    2005-01-01

    Full Text Available A concept design methodology for monotonous, tapered thin-walled structures (wing/fuselage/ship/bridge is presented including modules for: model generation; loads; primary (longitudinal and secondary (transverse strength calculations; structural feasibility (buckling/fatigue/ultimate strength criteria; design optimization modules based on ES/GA/FFE; graphics. A method for primary strength calculation is presented in detail. It provides the dominant response field for design feasibility assessment. Bending and torsion of the structure are modelled with the accuracy required for concept design. A ‘2.5D-FEM’ model is developed by coupling a 1D-FEM model along the ‘monotonity’ axis and a 2D-FEM model(s transverse to it. The shear flow and stiffness characteristics of the cross-section for bending and pure/restrained torsion are given, based upon the warping field of the cross-section. Examples: aircraft wing and ship hull. 

  9. Estimate of radiation-induced steel embrittlement in the BWR core shroud and vessel wall from reactor-grade MOX/UOX fuel for the nuclear power plant at Laguna Verde, Veracruz, Mexico

    Science.gov (United States)

    Vickers, Lisa Rene

    The government of Mexico has expressed interest to utilize the Laguna Verde boiling water reactor (BWR) nuclear power plant for the disposition of reprocessed spent uranium oxide (UOX) fuel in the form of reactor-grade mixed-oxide (MOX) fuel. MOX fuel would replace spent UOX fuel as a fraction in the core from 18--30% depending on the fuel loading cycle. MOX fuel is expected to increase the neutron fluence, flux, fuel centerline temperature, reactor core pressure, and yield higher energy neutrons. There is concern that a core with a fraction of MOX fuel (i.e., increased 239Pu wt%) would increase the radiation-induced steel embrittlement within the core shroud and vessel wall as compared to only conventional, enriched UOX fuel in the core. The evaluation of radiation-induced steel embrittlement within the core shroud and vessel wall is a concern because of the potentially adverse affect to plant and public safety, environment, and operating life of the reactor. This dissertation provides computational results of the neutron fluence, flux, energy spectrum, and radiation damage displacements per atom per second (dpa-s-1) in steel within the core shroud and vessel wall of the Laguna Verde Unit 1 BWR. The results were computed using the nuclear data processing code NJOY99 and the continuous energy Monte Carlo Neutral Particle transport code MCNP4B. The MCNP4B model of the reactor core was for maximum core loading fractions of ⅓ MOX and ⅔ UOX reactor-grade fuel in an equilibrium core. The primary conclusion of this dissertation was that the addition of the maximum fraction of ⅓ MOX fuel to the LV1 BWR core did significantly accelerate the radiation-induced steel embrittlement such that without mitigation of steel embrittlement by periodic thermal annealing or reduction in operating parameters such as, neutron fluence, core temperature and pressure, it posed a potentially adverse affect to the plant and public safety, environment, and operating life of the reactor.

  10. Assessment of aluminum structural materials for service within the ANS reflector vessel

    Energy Technology Data Exchange (ETDEWEB)

    Farrell, K.

    1995-08-01

    Most of the components in the Advanced Neutron Source (ANS) reactor, including the reflector vessel, will be built from the aluminum alloy 6061 (lMg,0.6Si) in its precipitation-hardened T6 and T651 conditions. The microstructural and mechanical characteristics of the alloy are described, and its operating boundaries of stress, temperature, and time in its unirradiated state are defined. The material`s responses to neutron radiation exposure in aqueous environments are reviewed in detail. The particular service conditions of stress, temperature, and radiation exposure expected for individual components in the ANS are listed, and the suitability of each component to meet the demands is assessed. Areas of uncertainties are outlined, and various suggestions and recommendations are made to give improved confidence in the predictions.

  11. Structure and Functions of Blood Vessels and Vascular Niches in Bone

    Directory of Open Access Journals (Sweden)

    Saravana K. Ramasamy

    2017-01-01

    Full Text Available Bone provides nurturing microenvironments for an array of cell types that coordinate important physiological functions of the skeleton, such as energy metabolism, mineral homeostasis, osteogenesis, and haematopoiesis. Endothelial cells form an intricate network of blood vessels that organises and sustains various microenvironments in bone. The recent identification of heterogeneity in the bone vasculature supports the existence of multiple vascular niches within the bone marrow compartment. A unique combination of cells and factors defining a particular microenvironment, supply regulatory signals to mediate a specific function. This review discusses recent developments in our understanding of vascular niches in bone that play a critical role in regulating the behaviour of multipotent haematopoietic and mesenchymal stem cells during development and homeostasis.

  12. Thermal-structural analysis of regeneratively-cooled thrust chamber wall in reusable LOX/Methane rocket engines

    Directory of Open Access Journals (Sweden)

    Jiawen SONG

    2017-06-01

    Full Text Available To predict the thermal and structural responses of the thrust chamber wall under cyclic work, a 3-D fluid-structural coupling computational methodology is developed. The thermal and mechanical loads are determined by a validated 3-D finite volume fluid-thermal coupling computational method. With the specified loads, the nonlinear thermal-structural finite element analysis is applied to obtaining the 3-D thermal and structural responses. The Chaboche nonlinear kinematic hardening model calibrated by experimental data is adopted to predict the cyclic plastic behavior of the inner wall. The methodology is further applied to the thrust chamber of LOX/Methane rocket engines. The results show that both the maximum temperature at hot run phase and the maximum circumferential residual strain of the inner wall appear at the convergent part of the chamber. Structural analysis for multiple work cycles reveals that the failure of the inner wall may be controlled by the low-cycle fatigue when the Chaboche model parameter γ3 = 0, and the damage caused by the thermal-mechanical ratcheting of the inner wall cannot be ignored when γ3 > 0. The results of sensitivity analysis indicate that mechanical loads have a strong influence on the strains in the inner wall.

  13. Effects of High-sugar and High-fat Diet on Fat Deposition and Blood Vessel Wall on Sprague Dawley Rats Liver

    Directory of Open Access Journals (Sweden)

    Vera Citra Setiawan Hoei

    2013-11-01

    Full Text Available People nowadays tend to consume more fast food and sweetened beverages. These foods usually contain high amount sugar and fat that have effects on the body including liver.This study was conducted to explore the effects of extensive intake of sugar and fat on blood glucose and  cholesterol level as well as changes in liver. Research was conducted with experimental method using 20 Sprague Dawley rats which were divided into 4 groups; 2 controls and 2 treatments. Rats were given 5 ml sugar or lard alternatively every 2 consecutive days for 1-month and 2-month respectively. Data was retrieved include blood glucose and cholesterol level, fatty liver percentage and blood vessel thickening after intervention through HE staining. The results showed that both 1-month and 2-month intervention group has significant increase in blood glucose and cholesterol level. However, the enhancement of fatty liver percentage and number of thickened blood vessels (p<0.05 were only foundsignificant (p<0.05 in 1-month intervention group.  We concluded that high intake of sugar and fat within 1-monthintervention have significant effects on the rat body including liver. Nevertheless, it was not found significant in 2-months intervention. Further studies are still needed to analyze this incongruent result.Key words: high-sugar diet, high-fat diet, fatty liver, atherosclerosis 

  14. Effect of Thin Cement-Based Renders on the Structural Response of Masonry Wall Panels

    Directory of Open Access Journals (Sweden)

    Marco Corradi

    2018-01-01

    Full Text Available URM (Unreinforced Masonry historic buildings can be generally arranged into three categories: adobe, brick and stone masonry. However, a common feature of URM structures is typically the low mechanical properties of the masonry material, especially in terms of shear strength. URM buildings are not amenable to seismic analysis, and the relatively low strength of stone and brickwork masonry often requires expensive and invasive retrofitting intervention. Hard, intractable stones broke artificially or naturally into random shapes were often used for construction in many parts of Europe and constitute the main material of historic buildings. Thin, cement or lime-based renders are often employed to protect masonry construction, but these are frequently ignored in analysis and design. This paper shows how standard, thin, cement-based renderings can highly enhance the lateral load-capacity and shear stiffness of wall panels. An experimental campaign was carried out on-site to assess the effect of cement-based renders. In detail, compression and shear tests were conducted on twelve full-scale wall panels up to failure, and comparisons are presented to study the effect of cement-based renders on the structural behavior of stone and brickwork masonry panels.

  15. Substructure hybrid testing of reinforced concrete shear wall structure using a domain overlapping technique

    Science.gov (United States)

    Zhang, Yu; Pan, Peng; Gong, Runhua; Wang, Tao; Xue, Weichen

    2017-10-01

    An online hybrid test was carried out on a 40-story 120-m high concrete shear wall structure. The structure was divided into two substructures whereby a physical model of the bottom three stories was tested in the laboratory and the upper 37 stories were simulated numerically using ABAQUS. An overlapping domain method was employed for the bottom three stories to ensure the validity of the boundary conditions of the superstructure. Mixed control was adopted in the test. Displacement control was used to apply the horizontal displacement, while two controlled force actuators were applied to simulate the overturning moment, which is very large and cannot be ignored in the substructure hybrid test of high-rise buildings. A series of tests with earthquake sources of sequentially increasing intensities were carried out. The test results indicate that the proposed hybrid test method is a solution to reproduce the seismic response of high-rise concrete shear wall buildings. The seismic performance of the tested precast high-rise building satisfies the requirements of the Chinese seismic design code.

  16. Fluid structural analysis of human cerebral aneurysm using their own wall mechanical properties.

    Science.gov (United States)

    Valencia, Alvaro; Burdiles, Patricio; Ignat, Miguel; Mura, Jorge; Bravo, Eduardo; Rivera, Rodrigo; Sordo, Juan

    2013-01-01

    Computational Structural Dynamics (CSD) simulations, Computational Fluid Dynamics (CFD) simulation, and Fluid Structure Interaction (FSI) simulations were carried out in an anatomically realistic model of a saccular cerebral aneurysm with the objective of quantifying the effects of type of simulation on principal fluid and solid mechanics results. Eight CSD simulations, one CFD simulation, and four FSI simulations were made. The results allowed the study of the influence of the type of material elements in the solid, the aneurism's wall thickness, and the type of simulation on the modeling of a human cerebral aneurysm. The simulations use their own wall mechanical properties of the aneurysm. The more complex simulation was the FSI simulation completely coupled with hyperelastic Mooney-Rivlin material, normal internal pressure, and normal variable thickness. The FSI simulation coupled in one direction using hyperelastic Mooney-Rivlin material, normal internal pressure, and normal variable thickness is the one that presents the most similar results with respect to the more complex FSI simulation, requiring one-fourth of the calculation time.

  17. Fluid Structural Analysis of Human Cerebral Aneurysm Using Their Own Wall Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Alvaro Valencia

    2013-01-01

    Full Text Available Computational Structural Dynamics (CSD simulations, Computational Fluid Dynamics (CFD simulation, and Fluid Structure Interaction (FSI simulations were carried out in an anatomically realistic model of a saccular cerebral aneurysm with the objective of quantifying the effects of type of simulation on principal fluid and solid mechanics results. Eight CSD simulations, one CFD simulation, and four FSI simulations were made. The results allowed the study of the influence of the type of material elements in the solid, the aneurism’s wall thickness, and the type of simulation on the modeling of a human cerebral aneurysm. The simulations use their own wall mechanical properties of the aneurysm. The more complex simulation was the FSI simulation completely coupled with hyperelastic Mooney-Rivlin material, normal internal pressure, and normal variable thickness. The FSI simulation coupled in one direction using hyperelastic Mooney-Rivlin material, normal internal pressure, and normal variable thickness is the one that presents the most similar results with respect to the more complex FSI simulation, requiring one-fourth of the calculation time.

  18. Cell wall carbohydrates from fruit pulp of Argania spinosa: structural analysis of pectin and xyloglucan polysaccharides.

    Science.gov (United States)

    Aboughe-Angone, Sophie; Nguema-Ona, Eric; Ghosh, Partha; Lerouge, Patrice; Ishii, Tadashi; Ray, Bimalendu; Driouich, Azeddine

    2008-01-14

    Isolated cell walls of Argania spinosa fruit pulp were fractionated into their polysaccharide constituents and the resulting fractions were analysed for monosaccharide composition and chemical structure. The data reveal the presence of homogalacturonan, rhamnogalacturonan-I (RG-I) and rhamnogalacturonan-II (RG-II) in the pectic fraction. RG-I is abundant and contains high amounts of Ara and Gal, indicative of an important branching in this polysaccharide. RG-II is less abundant than RG-I and exists as a dimer. Structural characterisation of xyloglucan using enzymatic hydrolysis, gas chromatography, MALDI-TOF-MS and methylation analysis shows that XXGG, XXXG, XXLG and XLLG are the major subunit oligosaccharides in the ratio of 0.6:1:1.2:1.6. This finding demonstrates that the major neutral hemicellulosic polysaccharide is a galacto-xyloglucan. In addition, Argania fruit xyloglucan has no XUFG, a novel xyloglucan motif recently discovered in Argania leaf cell walls. Finally, the isolation and analysis of arabinogalactan-proteins showed that Argania fruit pulp is rich in these proteoglycans.

  19. Effect of the fungicide Prochloraz-Mn on the cell wall structure of Verticillium fungicola.

    Science.gov (United States)

    Bernardo, D; Novaes-Ledieu, M; Perez Cabo, A; Gea Alegría, F J; García Mendoza, C

    2002-09-01

    The chemical structure of the cell wall of two isolates of Verticillium fungicolacollected from diseased fruit bodies of the commercial mushroom Agaricus bisporus treated with the fungicide Prochloraz-Mn was analyzed. The isolates were obtained during different periods of time and grown in the absence and presence of the LD(50) values of the fungicide for V. fungicola. In addition, another V. fungicola isolate collected previous to the routine utilization of Prochloraz-Mn but grown under the same conditions was also analyzed. The overall chemical composition of the cell wall from the three isolates showed detectable differences in their basic components, with a significant decrease in the protein content in fungicide-treated cells. This inhibitory effect was partially compensated by an increase in neutral and/or aminated carbohydrates and was accompanied by appreciable modifications of polysaccharide structure, as deduced after methylation analysis and gas-liquid chromatography-mass spectrometry (GLC-MS). Moreover, differences in hyphal morphology caused by the fungicide were observed by transmission electron microscopy (TEM).

  20. Current-induced domain-wall switching in a ferromagnetic semiconductor structure.

    Science.gov (United States)

    Yamanouchi, M; Chiba, D; Matsukura, F; Ohno, H

    2004-04-01

    Magnetic information storage relies on external magnetic fields to encode logical bits through magnetization reversal. But because the magnetic fields needed to operate ultradense storage devices are too high to generate, magnetization reversal by electrical currents is attracting much interest as a promising alternative encoding method. Indeed, spin-polarized currents can reverse the magnetization direction of nanometre-sized metallic structures through torque; however, the high current densities of 10(7)-10(8) A cm(-2) that are at present required exceed the threshold values tolerated by the metal interconnects of integrated circuits. Encoding magnetic information in metallic systems has also been achieved by manipulating the domain walls at the boundary between regions with different magnetization directions, but the approach again requires high current densities of about 10(7) A cm(-2). Here we demonstrate that, in a ferromagnetic semiconductor structure, magnetization reversal through domain-wall switching can be induced in the absence of a magnetic field using current pulses with densities below 10(5) A cm(-2). The slow switching speed and low ferromagnetic transition temperature of our current system are impractical. But provided these problems can be addressed, magnetic reversal through electric pulses with reduced current densities could provide a route to magnetic information storage applications.

  1. Effect of Thermal Treatment on the Structure of Multi-walled Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Behler, K.; Osswald, S.; Ye, H.; Dimovski, S.; Gogotsi, Y. [Drexel University, Department of Materials Science and Engineering, and A.J. Drexel Nanotechnology Institute (United States)], E-mail: yg36@drexel.edu

    2006-10-15

    The effects of vacuum annealing and oxidation in air on the structure of multi-walled carbon nanotubes (MWCNTs) produced by a large-scale catalytic chemical vapor deposition (CCVD) process are studied using Raman spectroscopy and transmission electron microscopy (TEM). A detailed Raman spectroscopic study of as-produced nanotubes has also been conducted. While oxidation in air up to 400 deg. C removes disordered carbon, defects in tube walls are produced at higher temperatures. TEM reveals that MWCNTs annealed at 1,800 deg. C and above become more ordered than as-received tubes, while the tubes annealed at 2,000 deg. C exhibit polygonalization, mass transfer and over growth. The change in structure is observable by the separation of the Raman G and D' peaks, a lower R-value (I{sub D}/I{sub G} ratio), and an increase in the intensity of the second order peaks. Using wavelengths from the deep ultraviolet (UV) range (5.08 eV) extending into the visible near infrared (IR) (1.59 eV), the Raman spectra of MWCNTs reveal a dependence of the D-band position proportional to the excitation energy of the incident laser energies.

  2. Wave Propagation in Thin-walled Composite Structures : Application to Structural Health Monitoring

    NARCIS (Netherlands)

    Pahlavan, L.

    2012-01-01

    In order for the increased use of fiber-reinforced composite structures to be financially feasible, employment of reliable and economical systems to detect damage and evaluate structural integrity is necessary. This task has traditionally been performed using off-line non-destructive testing (NDT)

  3. Seismic Performance Evaluation of Multistory Reinforced Concrete Moment Resisting Frame Structure with Shear Walls

    Directory of Open Access Journals (Sweden)

    Junwon Seo

    2015-10-01

    Full Text Available This paper is intended to evaluate the seismic performance of a twelve-story reinforced concrete moment-resisting frame structure with shear walls using 3D finite element models according to such seismic design regulations as Federal Emergency Management Agency (FEMA guideline and seismic building codes including Los Angeles Tall Building Structural Design Council (LATBSDC code. The structure is located in Seismic Zone 4, considered the highest-seismic-risk classification established by the U.S. Geological Survey. 3D finite element model was created in commercially available finite element software. As part of the seismic performance evaluation, two standard approaches for the structure seismic analysis were used; response spectrum analysis and nonlinear time-history analysis. Both approaches were used to compute inter-story drift ratios of the structure. Seismic fragility curves for each floor of the structure were generated using the ratios from the time history analysis with the FEMA guideline so as to evaluate their seismic vulnerability. The ratios from both approaches were compared to FEMA and LATBSDC limits. The findings revealed that the floor-level fragility mostly decreased for all the FEMA performance levels with an increase in height and the ratios from both approaches mostly satisfied the codified limits.

  4. Study on the influence of inner wall morphology and structure defect on the emission point of microchannel plate

    Science.gov (United States)

    Bo, Tiezhu; Shi, Xiaoxuan; Wang, Chen; Cai, Hua; Lian, Jiao; Cao, Zhenbo; Li, Qing; Liu, Chang; Liu, Hui

    2017-10-01

    The microchannel plate (MCP) as the most important component of image intensifiers and ultraviolet detectors, is avalanche two-dimensional electron multiplier device. The emission point as a pattern noise, which is characterized by a bright or a flickering point at a fixed position of the fluorescent screen, affects the visual quality and reliability of the MCP. Therefore, eliminating the emission point is an effective way to improve the performances of the MCP. In this paper, the inner wall morphology and structure defect of the channel were studied, the MCPs with different inner wall morphlogies were analyzed by SEM, and the emission point were tested by using the photoelectric imaging integrated tester. Using the above-mentioned research methods, a specific relationship between the inner wall morphology and the emission point was established. According to the field emission theory, the mechanism of the emission point was analyzed and discussed. The results show that the inner wall structure defects of the channel are the main reasons for the emission point. Furthermore, the study found that the matching of the thermal physical properties between core glass and clad glass is the main reason for the occurrence of structure defects. The structure defects of the inner wall can be effectively reduced by optimizing the composition of the glass material, make the two glasses have the suitable performance matching, avoid forming residual pores at the interface position, the inner wall of the channel will have a smooth, defect free microstructure, thereby effectively controlling the emission point of the MCP.

  5. The disruptive effect of lysozyme on the bacterial cell wall explored by an in-silico structural outlook.

    Science.gov (United States)

    Primo, Emiliano D; Otero, Lisandro H; Ruiz, Francisco; Klinke, Sebastián; Giordano, Walter

    2017-11-13

    The bacterial cell wall, a structural unit of peptidoglycan polymer comprised of glycan strands consisting of a repeating disaccharide motif [N-acetylglucosamine (NAG) and N-acetylmuramylpentapeptide (NAM pentapeptide)], encases bacteria and provides structural integrity and protection. Lysozymes are enzymes that break down the bacterial cell wall and disrupt the bacterial life cycle by cleaving the linkage between the NAG and NAM carbohydrates. Lab exercises focused on the effects of lysozyme on the bacterial cell wall are frequently incorporated in biochemistry classes designed for undergraduate students in diverse fields as biology, microbiology, chemistry, agronomy, medicine, and veterinary medicine. Such exercises typically do not include structural data. We describe here a sequence of computer tasks designed to illustrate and reinforce both physiological and structural concepts involved in lysozyme effects on the bacterial cell-wall structure. This lab class usually lasts 3.5 hours. First, the instructor presents introductory concepts of the bacterial cell wall and the effect of lysozyme on its structure. Then, students are taught to use computer modeling to visualize the three-dimensional structure of a lysozyme in complex with bacterial cell-wall fragments. Finally, the lysozyme inhibitory effect on a bacterial culture is optionally proposed as a simple microbiological assay. The computer lab exercises described here give students a realistic understanding of the disruptive effect of lysozymes on the bacterial cell wall, a crucial component in bacterial survival. © 2017 by The International Union of Biochemistry and Molecular Biology, 2017. © 2017 The International Union of Biochemistry and Molecular Biology.

  6. Microneedles for the Noninvasive Structural and Functional Assessment of Dermal Lymphatic Vessels.

    Science.gov (United States)

    Brambilla, Davide; Proulx, Steven T; Marschalkova, Patrizia; Detmar, Michael; Leroux, Jean-Christophe

    2016-02-24

    The medical and scientific communities' interest in the lymphatic system has been growing rapidly in recent years. It has become evident that the lymphatic system is much more than simply a homeostasis controller and that it plays key roles in several pathological conditions. This work describes the identification of the optimal combination of poly(N-vinylpyrrolidone) and a near-infrared dye (indocyanine green) for the manufacturing of soluble microneedles and their application to the imaging of the lymphatic system. Upon application to the skin, the microneedle-bearing indocyanine green is delivered in the dermal layer, where the lymphatic vessels are abundant. The draining lymphatics can then be visualized and the clearance kinetics from the administration site simply determined using a near-infrared camera. This painless functional "tattooing" procedure can be used for quantitative assessment of the dermal lymphatic function in several dermal conditions and treatment-response evaluations. The two components of these microneedles are extensively used in routine medical care, potentially leading to rapid clinical translation. Moreover, this procedure may have a significant impact on preclinical lymphatic studies. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Melanin externalization in Candida albicans depends on cell wall chitin structures.

    Science.gov (United States)

    Walker, Claire A; Gómez, Beatriz L; Mora-Montes, Héctor M; Mackenzie, Kevin S; Munro, Carol A; Brown, Alistair J P; Gow, Neil A R; Kibbler, Christopher C; Odds, Frank C

    2010-09-01

    The fungal pathogen Candida albicans produces dark-pigmented melanin after 3 to 4 days of incubation in medium containing l-3,4-dihydroxyphenylalanine (l-DOPA) as a substrate. Expression profiling of C. albicans revealed very few genes significantly up- or downregulated by growth in l-DOPA. We were unable to determine a possible role for melanin in the virulence of C. albicans. However, we showed that melanin was externalized from the fungal cells in the form of electron-dense melanosomes that were free or often loosely bound to the cell wall exterior. Melanin production was boosted by the addition of N-acetylglucosamine to the medium, indicating a possible association between melanin production and chitin synthesis. Melanin externalization was blocked in a mutant specifically disrupted in the chitin synthase-encoding gene CHS2. Melanosomes remained within the outermost cell wall layers in chs3Delta and chs2Delta chs3Delta mutants but were fully externalized in chs8Delta and chs2Delta chs8Delta mutants. All the CHS mutants synthesized dark pigment at equivalent rates from mixed membrane fractions in vitro, suggesting it was the form of chitin structure produced by the enzymes, not the enzymes themselves, that was involved in the melanin externalization process. Mutants with single and double disruptions of the chitinase genes CHT2 and CHT3 and the chitin pathway regulator ECM33 also showed impaired melanin externalization. We hypothesize that the chitin product of Chs3 forms a scaffold essential for normal externalization of melanosomes, while the Chs8 chitin product, probably produced in cell walls in greater quantity in the absence of CHS2, impedes externalization.

  8. Mediation of deep supercooling of peach and dogwood by enzymatic modifications in cell-wall structure.

    Science.gov (United States)

    Wisniewski, M; Davis, G; Schafter, K

    1991-05-01

    Treatment of stem sections of peach (Prunus persica (L.) Batsch) and flowering dogwood (Cornus florida L.) with macerase, an enzyme mixture rich in pectinase, for 24-48 h resulted in a complete flattening of the low-temperature exotherm (LTE) as determined by differential thermal analysis (DTA). Ultrastructural analysis of macerase-treated tissue demonstrated a nearly complete digestion of the pit membrane (black cap and primary cell-wall) of nearly 100% of the xylem-parenchyma cells examined after 48 h of exposure to the enzyme. Additionally, the underlying amorphous layer was partially degraded in up to 57% of the cells examined. The macerase treatment had no visible effect on secondary cell-walls of xylem tissue. In contrast, treatment of stem tissue with cellulysin (mostly cellulase) resulted in a shift of the LTE to warmer temperatures as determined by DTA, and a digestion of only the outermost layer of the pit membrane in nearly 100% of the cells examined, with little or no effect on the underlying layers. Treatment of tissue with 25 mM sodiumphosphate buffer also resulted in a shift of the LTE to warmer temperatures but the shift was not as great as in cellulysin-treated tissue. The shift was associated with a partial degradation of the outermost layer of the pit membrane in dogwood (33-45% of the cells examined) but not in peach (3-7% of the cells). Collectively, the data indicate that pectins may be an integral structural element of the pit membrane and that this portion of the cell-wall, along with the underlying amorphous layer, play a major role in forming a barrier to water movement and growth of ice crystals. This barrier allows xylem parenchyma of some species of woody plants to undergo deep supercooling.

  9. Effect of Immersed Wall-Bounded Cylinders on Turbulent Boundary Layer Structure

    Science.gov (United States)

    Zheng, Shaokai; Longmire, Ellen; Hallberg, Michael; Ryan, Mitchell

    2012-11-01

    Single spanwise arrays of wall-mounted cylinders with H/ δ <= 0.2, where H is the cylinder height and δ is the boundary layer thickness, were used to modify turbulent boundary layers (Reτ=2500) in an attempt to affect the organization of the coherent structures in the logarithmic and outer regions. Flow downstream of several array spacings was investigated and compared against an unperturbed case. Instantaneous and averaged velocity fields in streamwise-spanwise planes were obtained by stereo PIV. The PIV cameras and laser sheet optics could be traversed at the local mean flow speed in order to track the evolution of larger structures in the flow. The results are analyzed to determine the streamwise evolution of dominant spanwise modes. Different array spacings are shown to either inhibit or reinforce the organization of vortex packet structures over streamwise distances up to 8 δ. The flying stereo PIV measurements suggest also that dominant structures upstream of the arrays can strongly affect the organization and location of structures downstream. supported by NSF CBET-0933341.

  10. Cs{sup +} sputtered clusters from multi-walled carbon nanotubes, graphite and the structural transformations

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Shoaib, E-mail: sahmad@gcu.edu.pk [Government College University (GCU), CASP, Church Road, 54000 Lahore (Pakistan); Javeed, Sumera; Zeeshan, Sumaira [Pakistan Institute of Nuclear Science and Technology, P O Nilore, Islamabad (Pakistan); Naeem, Athar; Saadat, Shahzad; Yousuf, Muhammad; Khaleel, Muhammad; Mushtaq, Ahsan; Shahnawaz, Muhammad [Government College University (GCU), CASP, Church Road, 54000 Lahore (Pakistan)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer Cs{sup +} irradiated MWCNTs investigated with sputtered carbon clusters. Black-Right-Pointing-Pointer The fragments include from monomers to large clusters. Black-Right-Pointing-Pointer Successive spectra identify the fragmentation to conversion into amorphous carbon. - Abstract: Experiments with multi-walled carbon nanotubes (MWCNTs) and graphite as targets in a source of negative ions with cesium sputtering show that MWCNTs with nanometer radii and micrometer length can be compared with micrometer-size graphite grains. The comparative study helps to better understand the irradiation effects, including the formation, sputtering of carbon clusters and the resulting structural changes. The simultaneous adsorption of Cs{sup 0} on the surface and bombardment by energetic Cs{sup +} ions is shown to play a role in cluster formation and sputtering of carbon atoms and clusters (C{sub x}; x Greater-Than-Or-Slanted-Equal-To 1) and the cesium-substituted carbon clusters (CsC{sub x}) as anions. Qualitative and quantitative outputs of sputtered species are related to their respective structures. Structural changes are shown to occur in MWCNTs and seen in scanning electron micrographs. The individual identity of the heavily bombarded MWCNTs may have given way to the merged structures while effects on the structure of heavily irradiated graphite grains size needs to be further investigated.

  11. Relationships among the structural topology, bond strength, and mechanical properties of single-walled aluminosilicate nanotubes

    Science.gov (United States)

    Liou, Kai-Hsin; Tsou, Nien-Ti; Kang, Dun-Yen

    2015-10-01

    Carbon nanotubes (CNTs) are regarded as small but strong due to their nanoscale microstructure and high mechanical strength (Young's modulus exceeds 1000 GPa). A longstanding question has been whether there exist other nanotube materials with mechanical properties as good as those of CNTs. In this study, we investigated the mechanical properties of single-walled aluminosilicate nanotubes (AlSiNTs) using a multiscale computational method and then conducted a comparison with single-walled carbon nanotubes (SWCNTs). By comparing the potential energy estimated from molecular and macroscopic material mechanics, we were able to model the chemical bonds as beam elements for the nanoscale continuum modeling. This method allowed for simulated mechanical tests (tensile, bending, and torsion) with minimum computational resources for deducing their Young's modulus and shear modulus. The proposed approach also enabled the creation of hypothetical nanotubes to elucidate the relative contributions of bond strength and nanotube structural topology to overall nanotube mechanical strength. Our results indicated that it is the structural topology rather than bond strength that dominates the mechanical properties of the nanotubes. Finally, we investigated the relationship between the structural topology and the mechanical properties by analyzing the von Mises stress distribution in the nanotubes. The proposed methodology proved effective in rationalizing differences in the mechanical properties of AlSiNTs and SWCNTs. Furthermore, this approach could be applied to the exploration of new high-strength nanotube materials.Carbon nanotubes (CNTs) are regarded as small but strong due to their nanoscale microstructure and high mechanical strength (Young's modulus exceeds 1000 GPa). A longstanding question has been whether there exist other nanotube materials with mechanical properties as good as those of CNTs. In this study, we investigated the mechanical properties of single-walled

  12. Integral experiments on in-vessel coolability and vessel creep: results and analysis of the FOREVER-C1 test

    Energy Technology Data Exchange (ETDEWEB)

    Sehgal, B.R.; Nourgaliev, R.R.; Dinh, T.N.; Karbojian, A. [Division of Nuclear Power Safety, Royal Institute of Technology, Drottning Kristinas Vaeg., Stockholm (Sweden)

    1999-07-01

    This paper describes the FOREVER (Failure Of REactor VEssel Retention) experimental program, which is currently underway at the Division of Nuclear Power Safety, Royal Institute of Technology (RIT/NPS). The objectives of the FOREVER experiments are to obtain data and develop validated models (i) on the melt coolability process inside the vessel, in the presence of water (in particular, on the efficacy of the postulated gap cooling to preclude vessel failure); and (ii) on the lower head failure due to the creep process in the absence of water inside and/or outside the lower head. The paper presents the experimental results and analysis of the first FOREVER-C1 test. During this experiment, the 1/10th scale pressure vessel, heated to about 900degC and pressurized to 26 bars, was subjected to creep deformation in a non-stop 24-hours test. The vessel wall displacement data clearly shows different stages of the vessel deformation due to thermal expansion, elastic, plastic and creep processes. The maximum displacement was observed at the lowermost region of the vessel lower plenum. Information on the FOREVER-C1 measured thermal characteristics and analysis of the observed thermal and structural behavior is presented. The coupled nature of thermal and mechanical processes, as well as the effect of other system conditions (such as depressurization) on the melt pool and vessel temperature responses are analyzed. (author)

  13. Characterization of structural cell wall polysaccharides in cattail (Typha latifolia): Evaluation as potential biofuel feedstock.

    Science.gov (United States)

    Rebaque, Diego; Martínez-Rubio, Romina; Fornalé, Silvia; García-Angulo, Penélope; Alonso-Simón, Ana; Álvarez, Jesús M; Caparros-Ruiz, David; Acebes, José L; Encina, Antonio

    2017-11-01

    Second generation bioethanol produced from lignocellulosic biomass is attracting attention as an alternative energy source. In this study, a detailed knowledge of the composition and structure of common cattail (Typha latifolia L.) cell wall polysaccharides, obtained from stem or leaves, has been conducted using a wide set of techniques to evaluate this species as a potential bioethanol feedstock. Our results showed that common cattail cellulose content was high for plants in the order Poales and was accompanied by a small amount of cross-linked polysaccharides. A high degree of arabinose-substitution in xylans, a high syringyl/guaiacyl ratio in lignin and a low level of cell wall crystallinity could yield a good performance for lignocellulose saccharification. These results identify common cattail as a promising plant for use as potential bioethanol feedstock. To the best of our knowledge, this is the first in-depth analysis to be conducted of lignocellulosic material from common cattail. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Cell-wall structural changes in wheat straw pretreated for bioethanol production

    Directory of Open Access Journals (Sweden)

    Jørgensen Henning

    2008-04-01

    Full Text Available Abstract Background Pretreatment is an essential step in the enzymatic hydrolysis of biomass and subsequent production of bioethanol. Recent results indicate that only a mild pretreatment is necessary in an industrial, economically feasible system. The Integrated Biomass Utilisation System hydrothermal pretreatment process has previously been shown to be effective in preparing wheat straw for these processes without the application of additional chemicals. In the current work, the effect of the pretreatment on the straw cell-wall matrix and its components are characterised microscopically (atomic force microscopy and scanning electron microscopy and spectroscopically (attenuated total reflectance Fourier transform infrared spectroscopy in order to understand this increase in digestibility. Results The hydrothermal pretreatment does not degrade the fibrillar structure of cellulose but causes profound lignin re-localisation. Results from the current work indicate that wax has been removed and hemicellulose has been partially removed. Similar changes were found in wheat straw pretreated by steam explosion. Conclusion Results indicate that hydrothermal pretreatment increases the digestibility by increasing the accessibility of the cellulose through a re-localisation of lignin and a partial removal of hemicellulose, rather than by disruption of the cell wall.

  15. Intactness of cell wall structure controls the in vitro digestion of starch in legumes.

    Science.gov (United States)

    Dhital, Sushil; Bhattarai, Rewati R; Gorham, John; Gidley, Michael J

    2016-03-01

    Increasing the level of starch that is not digested by the end of the small intestine and therefore enters the colon ('resistant starch') is a major opportunity for improving the nutritional profile of foods. One mechanism that has been shown to be successful is entrapment of starch within an intact plant tissue structure. However, the level of tissue intactness required for resistance to amylase digestion has not been defined. In this study, intact cells were isolated from a range of legumes after thermal treatment at 60 °C (starch not gelatinised) or 95 °C (starch gelatinised) followed by hydrolysis using pancreatic alpha amylase. It was found that intact cells, isolated at either temperature, were impervious to amylase. However, application of mechanical force damaged the cell wall and made starch accessible to digestive enzymes. This shows that the access of enzymes to the entrapped swollen starch is the rate limiting step controlling hydrolysis of starch in cooked legumes. The results suggest that a single cell wall could be sufficient to provide an effective delivery of starch to the large intestine with consequent nutritional benefits, provided that mechanical damage during digestion is avoided.

  16. The mechanism of domain-wall structure formation in Ar-Kr submonolayer films on graphite

    Directory of Open Access Journals (Sweden)

    A. Patrykiejew

    2014-12-01

    Full Text Available Using Monte Carlo simulation method in the canonical ensemble, we have studied the commensurate-incommensurate transition in two-dimensional finite mixed clusters of Ar and Kr adsorbed on graphite basal plane at low temperatures. It has been demonstrated that the transition occurs when the argon concentration exceeds the value needed to cover the peripheries of the cluster. The incommensurate phase exhibits a similar domain-wall structure as observed in pure krypton films at the densities exceeding the density of a perfect (√3x√3R30º commensurate phase, but the size of commensurate domains does not change much with the cluster size. When the argon concentration increases, the composition of domain walls changes while the commensurate domains are made of pure krypton. We have constructed a simple one-dimensional Frenkel-Kontorova-like model that yields the results being in a good qualitative agreement with the Monte Carlo results obtained for two-dimensional systems.

  17. Shape optimization on the nozzle of a spherical pressure vessel using the ranked bidirectional evolutionary structural optimization

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Shin; Ryu, Chung Hyun [Chungnam National Univ., Taejon (Korea, Republic of)

    2001-07-01

    To reduce stress concentration around the intersection between a spherical pressure vessel and a cylindrical nozzle under various load conditions using less material, the optimization for the distribution of reinforcement has researched. The Ranked Bidirectional Evolutionary Structural Optimization(R-BESO) method is developed recently, which adds elements based on a rank, and the performance indicator which can estimate a fully stressed model. The R-BESO method can obtain the optimum design using less iteration number than iteration number of the BESO. In this paper, the optimized intersection shape is sought using R-BESO method for a flush and a protruding nozzle. The considered load cases are a radial compression, torque and shear force.

  18. Chemical and enzymatic fractionation of cell walls from Fucales: insights into the structure of the extracellular matrix of brown algae.

    Science.gov (United States)

    Deniaud-Bouët, Estelle; Kervarec, Nelly; Michel, Gurvan; Tonon, Thierry; Kloareg, Bernard; Hervé, Cécile

    2014-10-01

    Brown algae are photosynthetic multicellular marine organisms evolutionarily distant from land plants, with a distinctive cell wall. They feature carbohydrates shared with plants (cellulose), animals (fucose-containing sulfated polysaccharides, FCSPs) or bacteria (alginates). How these components are organized into a three-dimensional extracellular matrix (ECM) still remains unclear. Recent molecular analysis of the corresponding biosynthetic routes points toward a complex evolutionary history that shaped the ECM structure in brown algae. Exhaustive sequential extractions and composition analyses of cell wall material from various brown algae of the order Fucales were performed. Dedicated enzymatic degradations were used to release and identify cell wall partners. This approach was complemented by systematic chromatographic analysis to study polymer interlinks further. An additional structural assessment of the sulfated fucan extracted from Himanthalia elongata was made. The data indicate that FCSPs are tightly associated with proteins and cellulose within the walls. Alginates are associated with most phenolic compounds. The sulfated fucans from H. elongata were shown to have a regular α-(1→3) backbone structure, while an alternating α-(1→3), (1→4) structure has been described in some brown algae from the order Fucales. The data provide a global snapshot of the cell wall architecture in brown algae, and contribute to the understanding of the structure-function relationships of the main cell wall components. Enzymatic cross-linking of alginates by phenols may regulate the strengthening of the wall, and sulfated polysaccharides may play a key role in the adaptation to osmotic stress. The emergence and evolution of ECM components is further discussed in relation to the evolution of multicellularity in brown algae. © The Author 2014. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please

  19. Tuning Electronic Structures of BN and C Double-Wall Hetero-Nanotubes

    Directory of Open Access Journals (Sweden)

    Xueran Liu

    2015-01-01

    Full Text Available First principle calculations based on density functional theory with the generalized gradient approximation were carried out to investigate the energetic and electronic properties of carbon and boron nitride double-wall hetero-nanotubes (C/BN-DWHNTs with different chirality and size, including an armchair (n, n carbon nanotube (CNT enclosed in (m, m boron nitride nanotube (BNNT and a zigzag (n, 0 CNT enclosed in (m, 0 BNNT. The electronic structure of these DWHNTs under a transverse electric field was also investigated. The ability to tune the band gap with changing the intertube distance (di and imposing an external electric field (F of zigzag DWHNTs provides the possibility for future electronic and electrooptic nanodevice applications.

  20. Fracture toughness of irradiated candidate materials for ITER first wall/blanket structures: Summary report

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, D.J.; Pawel, J.E.; Grossbeck, M.L.; Rowcliffe, A.F. [Oak Ridge National Lab., TN (United States)] [and others

    1996-04-01

    Disk compact specimens of candidate materials for first wall/blanket structures in ITER have been irradiated to damage levels of about 3 dpa at nominal irradiation temperatures of either 90 250{degrees}C. These specimens have been tested over a temperature range from 20 to 250{degrees}C to determine J-integral values and tearing moduli. The results show that irradiation at these temperatures reduces the fracture toughness of austenic stainless steels, but the toughness remains quite high. The toughness decreases as the temperature increases. Irradiation at 250{degrees}C is more damaging that at 90{degrees}C, causing larger decreases in the fracture toughness. The ferritic-martensitic steels HT-9 and F82H show significantly greater reductions in fracture toughness that the austenitic stainless steels.

  1. Analysis on spectra of hydroacoustic field in sonar cavity of the sandwich elastic wall structure

    Science.gov (United States)

    Xuetao, W.; Rui, H.; Weike, W.

    2017-09-01

    In this paper, the characteristics of the mechanical self - noise in sonar array cavity are studied by using the elastic flatbed - filled rectangular cavity parameterization model. Firstly, the analytic derivation of the vibration differential equation of the single layer, sandwich elastic wall plate structure and internal fluid coupling is carried out, and the modal method is used to solve it. Finally, the spectral characteristics of the acoustic field of rectangular cavity of different elastic wallboard materials are simulated and analyzed, which provides a theoretical reference for the prediction and control of sonar mechanical self-noise. In this paper, the sandwich board as control inside the dome background noise of a potential means were discussed, the dome background noise of qualitative prediction analysis and control has important theoretical significance.

  2. Structural and electronic properties of chiral single-wall copper nanotubes

    Science.gov (United States)

    Duan, YingNi; Zhang, JianMin; Xu, KeWei

    2014-04-01

    The structural, energetic and electronic properties of chiral ( n, m) (3⩽ n⩽6, n/2⩽ m⩽ n) single-wall copper nanotubes (CuNTs) have been investigated by using projector-augmented wave method based on density-functional theory. The (4, 3) CuNT is energetically stable and should be observed experimentally in both free-standing and tip-suspended conditions, whereas the (5, 5) and (6, 4) CuNTs should be observed in free-standing and tip-suspended conditions, respectively. The number of conductance channels in the CuNTs does not always correspond to the number of atomic strands comprising the nanotube. Charge density contours show that there is an enhanced interatomic interaction in CuNTs compared with Cu bulk. Current transporting states display different periods and chirality, the combined effects of which lead to weaker chiral currents on CuNTs.

  3. A structural analysis in seismic archaeology: the walls of Noto and the 1693 earthquake

    Directory of Open Access Journals (Sweden)

    G. Lombardini

    1995-06-01

    Full Text Available A crucial problenl for seismic archeology is how to recognize seismic effects and how to date them. On an experimental basis. we proposed that the problem be reversed, and that we begin at the other end: i.e. by analyzing already known seismic effects on ancient structures, testified by written sources. to be able to .calibrate>> the types or possible observations and any subsequent elaborations. The choice of the walls of Noto was suggested by the fact that Noto was abandoned following the earthquake of l693 (I,= XI MCS. Me 7.5 which had already been studied in depth as part of an ING research programme (1988-92. Moreover, just after recent research, this event proved to be reconstructed with a high quality standard. Photogrammetric measurements were made on several parts of the town walls to plot a numerical model aimed at ascertaining specific aspects of the earthquake damage. An estimate of the ground acceleration during the earthquake has been attempted via non-linear finite-element analyses of a building located by the main city gate. The analyses show that. in order to obtain the building vault collapse, a ground acceleration of 0.5 to 0.7 g had to be reached during the earthquake. This result, typical of a strong earthquake such as the one of 1693, proves that an approach based on finite element analysis and a sound engineering judgment Inay be systematically applied to historical earthquake sites to obtain some estimates of ground acceleration in historical earthquakes. On the whole, this work aimed at starting up the second development phase of the great event of 1693 of which the macroseismic erfects are known. In the meantime, some possibilities of tackling structural analyses in seismic archaeology are being explored.

  4. Feeling Wall Tension in an Interactive Demonstration of Laplace's Law

    Science.gov (United States)

    Letic, Milorad

    2012-01-01

    Laplace's Law plays a major role in explanations of the wall tension of structures like blood vessels, the bladder, the uterus in pregnancy, bronchioles, eyeballs, and the behavior of aneurisms or the enlarged heart. The general relation of Laplace's law, expressing that the product of the radius of curvature (r) and pressure (P) is equal to wall…

  5. Performance Evaluation of Different Masonry Infill Walls with Structural Fuse Elements Based on In-Plane Cyclic Load Testing

    Directory of Open Access Journals (Sweden)

    Andrew Kauffman

    2014-09-01

    Full Text Available This paper discusses the performance of a structural fuse concept developed for use as a seismic isolation system in the design and retrofit of masonry infill walls. An experimental program was developed and executed to study the behavior of the structural fuse system under cyclic loads, and to evaluate the performance of the system with various masonry materials. Cyclic tests were performed by applying displacement controlled loads at the first, second, and third stories of a two-bay, three-story steel test frame with brick infill walls; using a quasi-static loading protocol to create a first mode response in the structural system. A parametric study was also completed by replacing the brick infill panels with infill walls constructed of concrete masonry units and autoclaved aerated concrete blocks, and applying monotonically increasing, displacement controlled loads at the top story of the test frame.

  6. Molecular Organization in the Native State of Wood Cell Walls: Studies of Nanoscale Structure and its Development

    Energy Technology Data Exchange (ETDEWEB)

    Atalla, R. H.

    2001-02-01

    With respect to cell wall biogenesis we have developed a theory concerning the formation of lignin in which the regulation of structure is attributed to the hemicelluloses; they are viewed as templates for the assembly of lignin. The key supporting evidence is derived from the symmetry of annual rings in trees free of reaction wood. This symmetry is interpreted to point to genetic encoding as the dominant factor in the pattern of interunit linkages in lignin. More recently, we have explored further the implications of annual ring symmetries within the contexts of systems and information theory and theories of organization of hierarchic structures. This has led us to proposed a unifying model for cell wall biogenesis that comprehends cell wall polysaccharides as well as lignin. The model is based on examining the implications of symmetries and of hierarchic relationships between different levels of structure, with respect to synchrony and coordination of the stages of formation of the individual constituents.

  7. Insights into plant cell wall structure, architecture, and integrity using glycome profiling of native and AFEXTM-pre-treated biomass.

    Science.gov (United States)

    Pattathil, Sivakumar; Hahn, Michael G; Dale, Bruce E; Chundawat, Shishir P S

    2015-07-01

    Cell walls, which constitute the bulk of plant biomass, vary considerably in their structure, composition, and architecture. Studies on plant cell walls can be conducted on both native and pre-treated plant biomass samples, allowing an enhanced understanding of these structural and compositional variations. Here glycome profiling was employed to determine the relative abundance of matrix polysaccharides in several phylogenetically distinct native and pre-treated plant biomasses. Eight distinct biomass types belonging to four different subgroups (i.e. monocot grasses, woody dicots, herbaceous dicots, and softwoods) were subjected to various regimes of AFEX™ (ammonia fiber expansion) pre-treatment [AFEX is a trademark of MBI, Lansing (http://www.mbi.org]. This approach allowed detailed analysis of close to 200 cell wall glycan epitopes and their relative extractability using a high-throughput platform. In general, irrespective of the phylogenetic origin, AFEX™ pre-treatment appeared to cause loosening and improved accessibility of various xylan epitope subclasses in most plant biomass materials studied. For most biomass types analysed, such loosening was also evident for other major non-cellulosic components including subclasses of pectin and xyloglucan epitopes. The studies also demonstrate that AFEX™ pre-treatment significantly reduced cell wall recalcitrance among diverse phylogenies (except softwoods) by inducing structural modifications to polysaccharides that were not detectable by conventional gross composition analyses. It was found that monitoring changes in cell wall glycan compositions and their relative extractability for untreated and pre-treated plant biomass can provide an improved understanding of variations in structure and composition of plant cell walls and delineate the role(s) of matrix polysaccharides in cell wall recalcitrance. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  8. Vortex dynamics and elliptical structure wake interaction in the proximity of wall using 2-D RANS simulation

    Directory of Open Access Journals (Sweden)

    Arunkumar H. S.

    2018-01-01

    Full Text Available The 2-D numerical study is performed to analyses the flow characteristic behind the elliptical structure placed near the wall for three different gap ratios as 0.25, 0.5, and 1.0. Computational domain and model is initially validated with the unbounded flow over a cylinder without considering wall effect for Reynolds number of 3900. For flow over the cylinder with near wall, computational domain is modelled as Blasius profile is the input to the area of interest. At different gap ratios the effect of boundary layer on vortex shedding is studied with Reynolds number of 1440. By applying different turbulent model for analysis, study the variation in the results and suggest the suitable model for the present type of study. It has been observed that the wall effect is predominant in case of the gap ratio of 0.25 as compared to other gap ratios.

  9. Damage evaluation and analysis of composite pressure vessels using fiber Bragg gratings to determine structural health

    Science.gov (United States)

    Ortyl, Nicholas E.

    2005-11-01

    The application of MEMS and nanotechnology (MNT) to the field of structural health monitoring (SHM) is a fairly recent development. The recent change in this focus for MNT has been driven by the need to expand the applications for much of the technologies that were developed in the late 1990s. In addition, many companies desire to expand beyond their target high volume market segments of automotive, wireless communications, and computer peripherals, since these market segments were not as lucrative as first predicted. Most of the aerospace structural health monitoring developmental activity has been sponsored by agencies of the U.S. Government, which serves to pace the examination of these newer technologies to some degree. With that said, efforts are underway by companies such as Acellent Technologies and Blue Road Research to explore various MNT structural health monitoring approaches. The MNT under test include embedded piezoelectric sensors, MEMS accelerometers, time domain region sensors, and topical and embedded single and multi-axis fiber optic Bragg grating sensors. The promise of MNT for the SHM market segment is very enticing. The many wireless communication developments and miniaturization developments of the past five years is very attractive to the SHM community, especially those that are able to reduce the cost and complexity of integration. The main challenge for the community is one of selective integration. That is, certain pieces may be appropriate for SHM systems and certain pieces may not be. The better companies will chose wisely and put forth an approach that can be seamlessly integrated into the larger structure. For over a decade, Blue Road Research has been developing technologies aimed at structural health monitoring of both composite and non-composite parts, through the use of single and multiaxis fiber optic Bragg grating sensors. These sensors are 80 to 120 microns in diameter making them smaller than the diameter of a human hair

  10. Structural characteristics of oligomeric DNA strands adsorbed onto single-walled carbon nanotubes.

    Science.gov (United States)

    Roxbury, Daniel; Jagota, Anand; Mittal, Jeetain

    2013-01-10

    The single-stranded DNA to single-walled carbon nanotube (SWCNT) hybrid continues to attract significant interest as an exemplary biological molecule-nanomaterial conjugate. In addition to their many biomedical uses, such as in vivo sensing and delivery of molecular cargo, DNA-SWCNT hybrids enable the sorting of SWCNTs according to their chirality. Current experimental methods have fallen short of identifying the actual structural ensemble of DNA adsorbed onto SWCNTs that enables and controls several of these phenomena. Molecular dynamics (MD) simulation has been a useful tool for studying the structure of these hybrid molecules. In recent studies, using replica exchange MD (REMD) simulation we have shown that novel secondary structures emerge and that these structures are DNA-sequence and SWCNT-type dependent. Here, we use REMD to investigate in detail the structural characteristics of two DNA-SWCNT recognition pairs: (TAT)(4)-(6,5)-SWCNT, i.e., DNA sequence TATTATTATTAT bound to the (6,5) chirality SWCNT, and (CCG)(2)CC-(8,7)-SWCNT as well as off-recognition pairs (TAT)(4)-(8,7)-SWCNT and (CCG)(2)CC-(6,5)-SWCNT. From a structural clustering analysis, dominant equilibrium structures are identified and show a right-handed self-stitched motif for (TAT)(4)-(6,5) in contrast to a left-handed β-barrel for (CCG)(2)CC-(8,7). Additionally, characteristics such as DNA end-to-end distance, solvent accessible SWCNT surface area, DNA hydrogen bonding between bases, and DNA dihedral distributions have been probed in detail as a function of the number of DNA strands adsorbed onto the nanotube. We find that the DNA structures adsorbed onto a nanotube are also stabilized by significant numbers of non-Watson-Crick hydrogen bonds (intrastrand and interstrand) in addition to π-π stacking between DNA bases and nanotube surface and Watson-Crick pairs. Finally, we provide a summary of DNA structures observed for various DNA-SWCNT hybrids as a preliminary set of motifs that may be

  11. Reconfigurable logic via gate controlled domain wall trajectory in magnetic network structure.

    Science.gov (United States)

    Murapaka, C; Sethi, P; Goolaup, S; Lew, W S

    2016-02-03

    An all-magnetic logic scheme has the advantages of being non-volatile and energy efficient over the conventional transistor based logic devices. In this work, we present a reconfigurable magnetic logic device which is capable of performing all basic logic operations in a single device. The device exploits the deterministic trajectory of domain wall (DW) in ferromagnetic asymmetric branch structure for obtaining different output combinations. The programmability of the device is achieved by using a current-controlled magnetic gate, which generates a local Oersted field. The field generated at the magnetic gate influences the trajectory of the DW within the structure by exploiting its inherent transverse charge distribution. DW transformation from vortex to transverse configuration close to the output branch plays a pivotal role in governing the DW chirality and hence the output. By simply switching the current direction through the magnetic gate, two universal logic gate functionalities can be obtained in this device. Using magnetic force microscopy imaging and magnetoresistance measurements, all basic logic functionalities are demonstrated.

  12. Effect of interwall interaction on the electronic structure of double-walled carbon nanotubes.

    Science.gov (United States)

    Soto, M; Boyer, T A; Biradar, S; Ge, L; Vajtai, R; Elías-Zúñiga, A; Ajayan, P M; Barrera, E V

    2015-04-24

    Through this study, the results of density functional theory calculations within the local density approximation of the electronic structure of zigzag-zigzag double-walled carbon nanotubes (DWCNTs), with chiral indices (n, 0)@(m, 0) for n = 7-15, and m = 15-26, has been presented and the effects of interwall interaction and orbital hybridization on the electronic structure of these systems has been discussed. It was observed that the electronic band gap of the aforementioned DWCNTs depends on the interwall distance only for metallic-semiconductor configurations and on the intrinsic properties of the constituent tubes in all other combinations. It was also observed that the calculated band gap for most of the metallic-metallic DWCNTs was smaller than semiconductor-metallic, metallic-semiconductor, and semiconductor-semiconductor configurations. Metallic-semiconductor DWCNTs were found to be desirable for band gap tuning applications because of their dependence on interwall distance, opening up the possibility of using such systems in electronic device applications, such as transistors. Other applications include the use of DWCNTs in macroscopic carbon nanotube conducting wires, for which metallic-metallic and semiconducting-metallic zigzag-zigzag DWCNTs were found to be the most desirable configurations due to their small band gaps.

  13. Cell wall peptidolipids of Mycobacterium avium: from genetic prediction to exact structure of a nonribosomal peptide.

    Science.gov (United States)

    Bannantine, John P; Etienne, Gilles; Laval, Françoise; Stabel, Judith R; Lemassu, Anne; Daffé, Mamadou; Bayles, Darrell O; Ganneau, Christelle; Bonhomme, Frédéric; Branger, Maxime; Cochard, Thierry; Bay, Sylvie; Biet, Franck

    2017-08-01

    Mycobacteria have a complex cell wall structure that includes many lipids; however, even within a single subspecies of Mycobacterium avium these lipids can differ. Total lipids from an M. avium subsp. paratuberculosis (Map) ovine strain (S-type) contained no identifiable glycopeptidolipids or lipopentapeptide (L5P), yet both lipids are present in other M. avium subspecies. We determined the genetic and phenotypic basis for this difference using sequence analysis as well as biochemical and physico-chemical approaches. This strategy showed that a nonribosomal peptide synthase, encoded by mps1, contains three amino acid specifying modules in ovine strains, compared to five modules in bovine strains (C-type). Sequence analysis predicted these modules would produce the tripeptide Phe-N-Methyl-Val-Ala with a lipid moiety, termed lipotripeptide (L3P). Comprehensive physico-chemical analysis of Map S397 extracts confirmed the structural formula of the native L3P as D-Phe-N-Methyl-L-Val-L-Ala-OMe attached in N-ter to a 20-carbon fatty acid chain. These data demonstrate that S-type strains, which are more adapted in sheep, produce a unique lipid. There is a dose-dependent effect observed for L3P on upregulation of CD25+ CD8 T cells from infected cows, while L5P effects were static. In contrast, L5P demonstrated a significantly stronger induction of CD25+ B cells from infected animals compared to L3P. © 2017 John Wiley & Sons Ltd.

  14. Chemical and structural analysis of Eucalyptus globulus and E. camaldulensis leaf cuticles: a lipidized cell wall region

    Directory of Open Access Journals (Sweden)

    Paula eGuzmán

    2014-09-01

    Full Text Available The plant cuticle has traditionally been conceived as an independent hydrophobic layer that covers the external epidermal cell wall. Due to its complexity, the existing relationship between cuticle chemical composition and ultra-structure remains unclear to date. This study aimed to examine the link between chemical composition and structure of isolated, adaxial leaf cuticles of Eucalyptus camaldulensis and E. globulus by the gradual extraction and identification of lipid constituents (cutin and soluble lipids, coupled to spectroscopic and microscopic analyses. The soluble compounds and cutin monomers identified could not be assigned to a concrete internal cuticle ultra-structure. After cutin depolymerization, a cellulose network resembling the cell wall was observed, with different structural patterns in the regions ascribed to the cuticle proper and cuticular layer, respectively. Our results suggest that the current cuticle model should be revised, stressing the presence and major role of cell wall polysaccharides. It is concluded that the cuticle may be interpreted as a modified cell wall region which contains additional lipids. The major heterogeneity of the plant cuticle makes it difficult to establish a direct link between cuticle chemistry and structure with the existing methodologies.

  15. Chemical and structural analysis of Eucalyptus globulus and E. camaldulensis leaf cuticles: a lipidized cell wall region.

    Science.gov (United States)

    Guzmán, Paula; Fernández, Victoria; Graça, José; Cabral, Vanessa; Kayali, Nour; Khayet, Mohamed; Gil, Luis

    2014-01-01

    The plant cuticle has traditionally been conceived as an independent hydrophobic layer that covers the external epidermal cell wall. Due to its complexity, the existing relationship between cuticle chemical composition and ultra-structure remains unclear to date. This study aimed to examine the link between chemical composition and structure of isolated, adaxial leaf cuticles of Eucalyptus camaldulensis and E. globulus by the gradual extraction and identification of lipid constituents (cutin and soluble lipids), coupled to spectroscopic and microscopic analyses. The soluble compounds and cutin monomers identified could not be assigned to a concrete internal cuticle ultra-structure. After cutin depolymerization, a cellulose network resembling the cell wall was observed, with different structural patterns in the regions ascribed to the cuticle proper and cuticular layer, respectively. Our results suggest that the current cuticle model should be revised, stressing the presence and major role of cell wall polysaccharides. It is concluded that the cuticle may be interpreted as a modified cell wall region which contains additional lipids. The major heterogeneity of the plant cuticle makes it difficult to establish a direct link between cuticle chemistry and structure with the existing methodologies.

  16. Structure of the complex between teicoplanin and a bacterial cell-wall peptide: use of a carrier-protein approach

    Energy Technology Data Exchange (ETDEWEB)

    Economou, Nicoleta J.; Zentner, Isaac J. [Drexel University College of Medicine, 245 North 15th Street, Philadelphia, PA 19102 (United States); Lazo, Edwin; Jakoncic, Jean; Stojanoff, Vivian [Brookhaven National Laboratory, Upton, NY 11973 (United States); Weeks, Stephen D.; Grasty, Kimberly C.; Cocklin, Simon; Loll, Patrick J. [Drexel University College of Medicine, 245 North 15th Street, Philadelphia, PA 19102 (United States)

    2013-04-01

    Using a carrier-protein strategy, the structure of teicoplanin bound to its bacterial cell-wall target has been determined. The structure reveals the molecular determinants of target recognition, flexibility in the antibiotic backbone and intrinsic radiation sensitivity of teicoplanin. Multidrug-resistant bacterial infections are commonly treated with glycopeptide antibiotics such as teicoplanin. This drug inhibits bacterial cell-wall biosynthesis by binding and sequestering a cell-wall precursor: a d-alanine-containing peptide. A carrier-protein strategy was used to crystallize the complex of teicoplanin and its target peptide by fusing the cell-wall peptide to either MBP or ubiquitin via native chemical ligation and subsequently crystallizing the protein–peptide–antibiotic complex. The 2.05 Å resolution MBP–peptide–teicoplanin structure shows that teicoplanin recognizes its ligand through a combination of five hydrogen bonds and multiple van der Waals interactions. Comparison of this teicoplanin structure with that of unliganded teicoplanin reveals a flexibility in the antibiotic peptide backbone that has significant implications for ligand recognition. Diffraction experiments revealed an X-ray-induced dechlorination of the sixth amino acid of the antibiotic; it is shown that teicoplanin is significantly more radiation-sensitive than other similar antibiotics and that ligand binding increases radiosensitivity. Insights derived from this new teicoplanin structure may contribute to the development of next-generation antibacterials designed to overcome bacterial resistance.

  17. Numerical thermal analysis of the vertical external partition made as the frame thin-walled steel structure

    Directory of Open Access Journals (Sweden)

    Major Maciej

    2017-01-01

    Full Text Available The article presents numerical thermal analysis of the vertical external partitions made in the lightweight steel framing technology. Steel posts that perform the structural role lead to the formation of linear thermal bridges and have a negative effect on the level of thermal transmittance U. Therefore, optimal solutions are being explored for such technologies. One of the solutions is to use perforated Thermo sections. The effect of perforated Thermo sections on energy loss was verified through comparison to the wall made of solid sections. Furthermore, the calculations analysed the effect of linear thermal bridges that are formed on wall connections in the corner. Computer simulation was employed to emphasize the significant differences in the temperature distribution in both analysed wall structures that resulted from constructional solutions.

  18. Simulation of the electromagnetic wall response to plasma wall-touching kink and vertical modes with application to ITER

    Science.gov (United States)

    Atanasiu, Calin; Zakharov, Leonid; Lackner, Karl; Hoelzl, Matthias; Strumberger, Erika

    2017-10-01

    Realistic simulations of electric current excitation in three-dimensional vessel structures by the plasma touching the walls are necessary to understand plasma disruptions in tokamak. In large tokamaks like ITER, the wall-touching kink modes cause large sideway forces on the vacuum vessel determined by the sharing of asymmetric electric current between the plasma and the wall. Our model covers both eddy currents, excited inductively by vertical modes, and source/sink currents due to current sharing between the plasma and the thin conducting wall. The developed finite element approach calculates the electromagnetic wall response to perturbation of magnetic fields and to current sharing between the plasma and the wall. The current density entering/exiting the wall surface from the plasma and the time derivative of the magnetic vector potential of the plasma are the input values. The magnetic field and the vector potential from the wall currents are returned as output. Our model has been checked against analytical examples of a multiply-connected domain of a real ITER wall.

  19. Specific Features of Structural-Phase State and Properties of Reactor Pressure Vessel Steel at Elevated Irradiation Temperature

    Directory of Open Access Journals (Sweden)

    E. A. Kuleshova

    2017-01-01

    Full Text Available This paper considers influence of elevated irradiation temperature on structure and properties of 15Kh2NMFAA reactor pressure vessel (RPV steel. The steel is investigated after accelerated irradiation at 300°C (operating temperature of VVER-1000-type RPV and 400°C supposed to be the operating temperature of advanced RPVs. Irradiation at 300°C leads to formation of radiation-induced precipitates and radiation defects-dislocation loops, while no carbide phase transformation is observed. Irradiation at a higher temperature (400°C neither causes formation of radiation-induced precipitates nor provides formation of dislocation loops, but it does increase the number density of the main initial hardening phase—of the carbonitrides. Increase of phosphorus concentration in grain boundaries is more pronounced for irradiation at 400°C as compared to irradiation at 300°C due to influence of thermally enhanced diffusion at a higher temperature. The structural-phase changes determine the changes of mechanical properties: at both irradiation temperatures irradiation embrittlement is mainly due to the hardening mechanism with some contribution of the nonhardening one for irradiation at 400°C. Lack of formation of radiation-induced precipitates at T = 400°C provides a small ΔTK shift (17°C. The obtained results demonstrate that the investigated 15Kh2NMFAA steel may be a promising material for advanced reactors with an elevated operating temperature.

  20. Research vessels

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, P.S.

    by the research vessels RV Gaveshani and ORV Sagar Kanya are reported. The work carried out by the three charted ships is also recorded. A short note on cruise plans for the study of ferromanganese nodules is added...

  1. Automatic detection and segmentation of vascular structures in dermoscopy images using a novel vesselness measure based on pixel redness and tubularness

    Science.gov (United States)

    Kharazmi, Pegah; Lui, Harvey; Stoecker, William V.; Lee, Tim

    2015-03-01

    Vascular structures are one of the most important features in the diagnosis and assessment of skin disorders. The presence and clinical appearance of vascular structures in skin lesions is a discriminating factor among different skin diseases. In this paper, we address the problem of segmentation of vascular patterns in dermoscopy images. Our proposed method is composed of three parts. First, based on biological properties of human skin, we decompose the skin to melanin and hemoglobin component using independent component analysis of skin color images. The relative quantities and pure color densities of each component were then estimated. Subsequently, we obtain three reference vectors of the mean RGB values for normal skin, pigmented skin and blood vessels from the hemoglobin component by averaging over 100000 pixels of each group outlined by an expert. Based on the Euclidean distance thresholding, we generate a mask image that extracts the red regions of the skin. Finally, Frangi measure was applied to the extracted red areas to segment the tubular structures. Finally, Otsu's thresholding was applied to segment the vascular structures and get a binary vessel mask image. The algorithm was implemented on a set of 50 dermoscopy images. In order to evaluate the performance of our method, we have artificially extended some of the existing vessels in our dermoscopy data set and evaluated the performance of the algorithm to segment the newly added vessel pixels. A sensitivity of 95% and specificity of 87% were achieved.

  2. Age Features of Structural and Hemodynamic Parameters of Great Vessels of the Neck in Non-Alcoholic Fatty Liver Disease and Overweight

    Directory of Open Access Journals (Sweden)

    V.I. Bulda

    2015-06-01

    Violation of the structure and hemodynamics of the main vessels of the neck, detected during the complex duplex examination, is the result of direct impact of NAFLD (steatosis and increased body weight and leads to the development of cardiovascular risk, mainly in groups of middle-aged and elderly patients.

  3. A fast vibro-acoustic response analysis method for double wall structures including a viscothermal air layer

    NARCIS (Netherlands)

    Basten, T.G.H.; Grooteman, F.P.

    2000-01-01

    The damping behaviour of a thin air layer between two flexible panels can be used to reduce sound radiation of structural excited panels. The numerical model of the double wall panels takes into account full acousto-elastic interaction and viscothermal wave propagation in the air layer. This means

  4. Electron irradiation-induced change of structure and damage mechanisms in multi-walled carbon nanotubes

    Science.gov (United States)

    Yang, Jian-Qun; Li, Xing-Ji; Liu, Chao-Ming; Ma, Guo-Liang; Gao, Feng

    2015-11-01

    Owing to their unique structure and excellent electrical property, carbon nanotubes (CNTs) as an ideal candidate for making future electronic components have great application potentiality. In order to meet the requirements for space application in electronic components, it is necessary to study structural changes and damage mechanisms of multi-walled carbon nanotubes (MWCNTs), caused by the irradiations of 70 and 110 keV electrons. In the paper, the changes of structure and damage mechanisms in the irradiated MWCNTs, induced by the irradiations of 70 and 110 keV electrons, are investigated. The changes in surface morphology and structure of the irradiated MWCNT film are characterized using scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, x-ray diffraction analysis (XRD), and electron paramagnetic resonance (EPR) spectroscopy. It is found that the MWCNTs show different behaviors in structural changes after 70 and 110 keV electron irradiation due to different damage mechanisms. SEM results reveal that the irradiation of 70 keV electrons does not change surface morphology of the MWCNT film, while the irradiation of 110 keV electrons with a high fluence of 5 × 1015 cm-2 leads to evident morphological changes, such as the formation of a rough surface, the entanglement of nanotubes and the shrinkage of nanotubes. Based on Raman spectroscopy, XPS, and XRD analyses, it is confirmed that the irradiation of 70 keV electrons increases the interlayer spacing of the MWCNTs and disorders their structure through electronic excitations and ionization effects, while the irradiation of 110 keV electrons obviously reduces the interlayer spacing of the MWCNTs and improves their graphitic order through knock-on atom displacements. The improvement of the irradiated MWCNTs by 110 keV electrons is attributed to the restructuring of defect sites induced by knock-on atom displacements. EPR spectroscopic analyses reveal that the MWCNTs exposed

  5. Novel Method to Detect Corneal Lymphatic Vessels In Vivo by Intrastromal Injection of Fluorescein.

    Science.gov (United States)

    Le, Viet Nhat Hung; Hou, Yanhong; Horstmann, Jens; Bock, Felix; Cursiefen, Claus

    2017-11-09

    Corneal lymphatic vessels are clinically invisible because of their thin walls and clear lymph fluid. There is no easy and established method for in vivo imaging of corneal lymphatic vessels so far. In this study, we present a novel approach to visualize corneal lymphatic vessels in vivo by injecting intrastromal fluorescein sodium. Six- to eight-week-old female BALB/c mice were used in the mouse model of suture-induced corneal neovascularization. Two weeks after the suture placement, fluorescein sodium was injected intrastromally. The fluorescein, taken up by the presumed lymphatic vessels, was then tracked using a clinically used Spectralis HRA + OCT device. Immunohistochemistry staining with specific lymphatic marker LYVE-1 and pan-endothelial marker CD31 was used to confirm the indirect lymphangiography findings. By injecting fluorescein intrastromally, both corneal blood and lymphatic vessels were detected. While the lymphatic vessels were visible as bright vessel-like structures using HRA, the blood vessels appeared as dark networks. Fluorescein-labeled lymphatic vessels were colocalized with LYVE-1 in immunohistochemically stained sections of the same specimen. Corneal lymphatic vessels can be easily imaged in vivo in the murine model using intrastromal fluorescein injection.

  6. Control of cracking in R.C. Structures: Numerical simulation of a squat shear wall

    NARCIS (Netherlands)

    Damoni, C.; Belletti, B.; Lilliu, G.

    2013-01-01

    In this paper the behavior of a squat shear wall subjected to monotonic shear loading is investigated. The study fits into the experimental program driven by CEOS.fr on modeling of the behavior of the tested mocks-ups (monotonic and cycling loading-under prevented or free shrinkage). The shear wall

  7. Role of wall-attached structures in the interface of the quiescent core region in turbulent pipe flow

    Science.gov (United States)

    Yang, Jongmin; Hwang, Jinyul; Sung, Hyung Jin

    2017-11-01

    The effects of low- and high-speed structures on the interface of the quiescent core region are explored using direct numerical simulation data of turbulent pipe flow. The quiescent core region is a uniform momentum zone located at the center of the pipe flow, which contains the highest streamwise momentum with a low level of turbulence. The interface of the quiescent core region can be identified from the probability density function of the streamwise modal velocity. In the vicinity of the interface of the quiescent core region, the streamwise velocity changes abruptly. The abrupt jump in velocity causes an increase of the velocity gradient. The interface of the quiescent core region is similar to the laminar superlayer in turbulent/non-turbulent interface. The interface of the quiescent core region contains the low- and high-speed structures. They can be classified into wall-attached and detached structures depending on the distance between the structures and the wall. The influence of the detached structures accounted for most of the number of detected structures is negligible due to its small volume. Conversely, the wall-attached structures adjacent to the interface have a huge influence on the statistical amount of the interface, such as entrainment characteristics. This work was supported by the Creative Research Initiatives (No. 2017-013369) program of the National Research Foundation of Korea (MSIP).

  8. X-ray irradiation-induced structural changes on Single Wall Carbon Nanotubes

    Science.gov (United States)

    Bardi, N.; Jurewicz, I.; King, A. K.; Alkhorayef, M. A.; Bradley, D.; Dalton, A. B.

    2017-11-01

    Dosimetry devices based on Carbon Nanotubes are a promising new technology. In particular using devices based on single wall Carbon Nanotubes may offer a tissue equivalent response with the possibility for device miniaturisation, high scale manufacturing and low cost. An important precursor to device fabrication requires a quantitative study of the effects of X-ray radiation on the physical and chemical properties of the individual nanotubes. In this study, we concentrate on the effects of relatively low doses, 20 cGy and 45 cGy , respectively. We use a range of characterization techniques including scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy to quantify the effects of the radiation dose on inherent properties of the nanotubes. Specifically we find that the radiation exposure results in a reduction in the sp2 nature of the nanotube bond structure. Moreover, our analysis indicates that the exposure results in nanotubes that have an increased defect density which ultimately effects the electrical properties of the nanotubes.

  9. Structural and compositional changes in single wall carbon nanotube ensemble upon exposure to microwave plasma

    Science.gov (United States)

    Roy, Soumyendu; Bajpai, Reeti; Soin, Navneet; Sinha Roy, Susanta; McLaughlin, James A.; Misra, D. S.

    2017-10-01

    Microwave plasma treatment of single wall carbon nanotube (SWNT) films called bucky papers (BPs) resulted in changes in the relative proportion of different chiralities of SWNTs present in the BP and the production of vertical microstructures on the surface of BP. The plasma was created using H2 gas mixed with Ar or CH4, at a temperature of 900 °C and a pressure of 70 Torr. Radial breathing mode spectra of the BPs revealed that the preferential sputtering by plasma is not with respect to the diameter or the metallic nature of SWNTs. We propose that the lengths of SWNTs influence how they interact with plasma. Longer tubes will have higher dielectric constants and hence will be polarized more strongly by the electric field of the plasma sheath. This in turn results in greater ion bombardment and sputtering. Finite element method was used to find the strengths of the induced electric fields on model SWNT surfaces. Microscopy, Raman, and X-ray photoelectron spectroscopy were used to study the effect of plasma on the crystallinity of the surviving SWNTs. Structural integrity of SWNTs was preserved after the plasma treatment.

  10. Isolation of diploid baker's yeast capable of strongly activating immune cells and analyses of the cell wall structure.

    Science.gov (United States)

    Takada, Yuki; Mizobuchi, Ayano; Kato, Takayuki; Kasahara, Emiko; Ito, Chinatsu; Watanabe, Hajime; Kanzaki, Ken; Kitagawa, Seiichi; Tachibana, Taro; Azuma, Masayuki

    2014-01-01

    Diploid baker's yeast capable of strongly activating a mouse macrophage was constructed based on haploid mutant AQ-37 obtained previously. The obtained strain BQ-55 activated also human immune cells. To clarify a factor for the activation, the cell wall structure, especially the β-glucan structure, was analyzed, suggesting that the length of branching, β-1,6-glucan, may be one of the factors.

  11. LIFE Materials: Topical Assessment Report for LIFE Volume 1 TOPIC: Solid First Wall and Structural Components TASK: Radiation Effects on First Wall

    Energy Technology Data Exchange (ETDEWEB)

    Caro, A

    2008-11-26

    This report consists of the following chapters: CHAPTER A: LIFE Requirements for Materials. Part 1: The structure of the First Wall--Basic requirements; A qualitative view of the challenge; The candidate materials; and Base-line material's properties. CHAPTER B: Summary of Existing Knowledge--Brief historical introduction; Design window; The temperature window; Evolution of the design window with damage; Damage calculations; He and H production; Swelling resistance; Incubation dose for swelling; Design criterion No. 1, Strength; Design criterion No. 2, Corrosion resistance; Design criterion No. 3, Creep resistance; Design criterion No. 4, Radiation induced embrittlement; and Conclusions. CHAPTER C: Identification of Gaps in Knowledge & Vulnerabilities. CHAPTER D: Strategy and Future Work.

  12. Vibration analysis of doubly asymmetric, three-dimensional structures comprising wall and frame assemblies with variable cross-section

    Science.gov (United States)

    Rafezy, B.; Howson, W. P.

    2008-11-01

    A global analysis approach to modelling doubly asymmetric, three-dimensional, multi-bay, multi-storey, wall-frame structures is presented in a form that enables the lower numbered natural frequencies to be determined approximately with the certain knowledge that none have been missed. It is assumed that the primary walls and frames of the original structure run in two orthogonal directions and that their properties may vary in a step-wise fashion at one or more storey levels. The structure therefore divides naturally into uniform segments between changes of section properties. A typical segment is then replaced by an equivalent shear-flexure-torsion coupled beam whose governing differential equations are formulated using a continuum approach and posed in the form of a dynamic member stiffness matrix. The original structure can then be re-modelled as a sophisticated stepped cantilever in the usual way. Since the mass of each segment is assumed to be uniformly distributed, it is necessary to solve a transcendental eigenvalue problem, which is accomplished using the Wittrick-Williams algorithm. A parametric study on a series of wall-frame structures of varying height with different plan configurations is given to compare the accuracy of the current approach with datum results from fully converged finite element analyses.

  13. Customizable engineered blood vessels using 3D printed inserts.

    Science.gov (United States)

    Pinnock, Cameron B; Meier, Elizabeth M; Joshi, Neeraj N; Wu, Bin; Lam, Mai T

    2016-04-15

    Current techniques for tissue engineering blood vessels are not customizable for vascular size variation and vessel wall thickness. These critical parameters vary widely between the different arteries in the human body, and the ability to engineer vessels of varying sizes could increase capabilities for disease modeling and treatment options. We present an innovative method for producing customizable, tissue engineered, self-organizing vascular constructs by replicating a major structural component of blood vessels - the smooth muscle layer, or tunica media. We utilize a unique system combining 3D printed plate inserts to control construct size and shape, and cell sheets supported by a temporary fibrin hydrogel to encourage cellular self-organization into a tubular form resembling a natural artery. To form the vascular construct, 3D printed inserts are adhered to tissue culture plates, fibrin hydrogel is deposited around the inserts, and human aortic smooth muscle cells are then seeded atop the fibrin hydrogel. The gel, aided by the innate contractile properties of the smooth muscle cells, aggregates towards the center post insert, creating a tissue ring of smooth muscle cells. These rings are then stacked into the final tubular construct. Our methodology is robust, easily repeatable and allows for customization of cellular composition, vessel wall thickness, and length of the vessel construct merely by varying the size of the 3D printed inserts. This platform has potential for facilitating more accurate modeling of vascular pathology, serving as a drug discovery tool, or for vessel repair in disease treatment. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Longitudinal shrinkage of compression wood in dependence on water content and cell wall structure

    Directory of Open Access Journals (Sweden)

    Wiesław Włoch

    2015-01-01

    Full Text Available Compression wood from branches of Pinus silvestris L. was examined. Wide differences were noted in longitudinal shrinkage of the wood when dried from water saturated state. A relation was found between shrinkage and cell wall thickness, particularly of layer S2, and the degree of callose accumulation in the wall. No dependence could be revealed between the shrinkage and the fibril angle in S2.

  15. External wall structure of green rural houses in Daqing, China, based on life cycle and ecological footprint theories

    Directory of Open Access Journals (Sweden)

    Hong Jin

    2015-09-01

    Full Text Available Daqing is situated in one of the severely cold regions of China. The living environment in this region is extremely poor because of the harsh climate and the backward economy. The external wall is an important component of the external envelope of buildings, and it greatly contributes to the indoor thermal environment. By taking the external wall as the research object, this study summarizes the characteristics of the external wall structure and analyzes the common materials used in existing rural residences. Specifically, we combine life cycle theory and ecological footprint (EF theory and introduce the green external wall structure, as well as its application in practice, in accordance with the local ecosystem. Results show that anecological residence offers a better environment and greater economic benefits than a traditional residence. The annual energy consumption, CO2 consumption, and EF of the ecological residence in this study are lower than those of the traditional residence by 69.61%, 17.5 t, and 99.47%, respectively.

  16. Influence of the structural properties on the pseudocritical magnetic behavior of single-wall ferromagnetic nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Salazar-Enriquez, C.D. [PCM Computational Applications, Universidad Nacional de Colombia - Sede Manizales, A.A. 127 Manizales (Colombia); Restrepo-Parra, E., E-mail: erestrepopa@unal.edu.co [PCM Computational Applications, Universidad Nacional de Colombia - Sede Manizales, A.A. 127 Manizales (Colombia); Restrepo, J. [Grupo de Magnetismo y Simulacion Gplus, Instituto de Fisica, Universidad de Antioquia, A.A. 1226 Medellin (Colombia)

    2012-04-15

    In this work we address the influence of the crystalline structure, concretely when the system under study is formed by square or hexagonal unit cells, upon the magnetic properties and pseudocritical behavior of single-wall ferromagnetic nanotubes. We focus not only on the effect of the geometrical shape of the unit cell but also on their dimensions. The model employed is based on the Monte Carlo method, the Metropolis dynamics and a nearest neighbors classical Heisenberg Hamiltonian. Magnetization per magnetic site, magnetic susceptibility, specific heat and magnetic energy were computed. These properties were computed varying the system size, unit cell dimension and temperature. The dependence of the nearest neighbor exchange integral on the nanotubes geometrical characteristics is also discussed. Results revealed a strong influence of the system topology on the magnetic properties caused by the difference in the coordination number between square and hexagonal unit cell. Moreover, the nanotubes diameter influence on magnetic properties is only observed at very low values, when the distance between atoms is less than it, presented by the 2D sheet. On the other hand, it was concluded that the surface-related finite-size effects do not influence the magnetic nanotubes properties, contrary to the case of other nano-systems as thin films and nanoparticles among others. - Highlights: Black-Right-Pointing-Pointer Unit cell geometry has strong influence on the magnetic properties in ferromagnetic nanotubes. Black-Right-Pointing-Pointer The nanotube diameter increase produces a decrease of interaction between nearest neighbor. Black-Right-Pointing-Pointer Surface-related finite-size effects do not influence the magnetic nanotubes properties.

  17. Seismic Behaviour of an Experimental Model Made of Thin-Walled Cold Formed Steel Profiles - Hardell Structures

    Directory of Open Access Journals (Sweden)

    Ionuţ-Ovidiu Toma

    2009-01-01

    Full Text Available The experimental results of the shaking table test of a Hardell structure made of thin-walled cold formed steel profiles are presented. The structure has the in-plane dimensions of 4x4 m and a height of 6 m, being classified as a P+1E type of structure. The dynamic characteristics of the structure were determined during the first stage of the experiment. Afterwards, the structure was subjected to different types of dynamic loadings such as sine-sweep functions and to seismic actions simulating the El Centro and Vrancea earthquakes. The damages induced by the seismic excitations consisted of local buckling of the steel profiles and breaking of two anchorage bolts holding the structure to the shaking table. Based on the experimental results it can be concluded that the structure can safely withstand seismic loads up to certain intensity, provided that some requirements are met.

  18. STRUCTURAL PERFORMANCE OF TWO TYPES OF WALL SLAB CONNECTION UNDER OUT-OF-PLANE LATERAL CYCLIC LOADING

    Directory of Open Access Journals (Sweden)

    AHMED ABDULRAZZAQ NASSER AL-AGHBARI

    2012-04-01

    Full Text Available Currently, most of the high-rise buildings in Malaysia are constructed using tunnel form system. However, this type of structural system is still questionable of its safety under ground motion. Thus, the main objective of this study is to test and compare the structural performance of two types of wall-slab connection namely cross and anchorage bracings under reversible quasi-static cyclic loading. Two identical sub-assemblage of wall-slab connections are designed, constructed and tested in heavy structural laboratory. A load actuator together with load cell was positioned horizontally at the upper part of the wall for applying the lateral cyclic load. The experimental result shows that the anchorage bracing connection has higher strength, higher ductility, better energy absorption and less structural damage as compared to cross-bracing connections. Based on this experiment, the ductility of anchorage bracing connection is m=6 which satisfies the requirement of ductility for seismic code of practice. Anchorage bracing connection can resist earthquake loading better than cross-bracing connections. Therefore, it is recommended to the construction industry to adopt this kind of design together with the detailing which consists of double layer of wire fabric at the connections. As a conclusion, the anchorage bracing connection has better seismic performance as compared to cross-bracing connection under lateral cyclic loading.

  19. Coupled Static and Dynamic Buckling Modelling of Thin-Walled Structures in Elastic Range Review of Selected Problems

    Directory of Open Access Journals (Sweden)

    Kołakowski Zbigniew

    2016-06-01

    Full Text Available A review of papers that investigate the static and dynamic coupled buckling and post-buckling behaviour of thin-walled structures is carried out. The problem of static coupled buckling is sufficiently well-recognized. The analysis of dynamic interactive buckling is limited in practice to columns, single plates and shells. The applications of finite element method (FEM or/and analytical-numerical method (ANM to solve interaction buckling problems are on-going. In Poland, the team of scientists from the Department of Strength of Materials, Lodz University of Technology and co-workers developed the analytical-numerical method. This method allows to determine static buckling stresses, natural frequencies, coefficients of the equation describing the post-buckling equilibrium path and dynamic response of the plate structure subjected to compression load and/or bending moment. Using the dynamic buckling criteria, it is possible to determine the dynamic critical load. They presented a lot of interesting results for problems of the static and dynamic coupled buckling of thin-walled plate structures with complex shapes of cross-sections, including an interaction of component plates. The most important advantage of presented analytical-numerical method is that it enables to describe all buckling modes and the post-buckling behaviours of thin-walled columns made of different materials. Thin isotropic, orthotropic or laminate structures were considered.

  20. Structure and Mechanism of Staphylococcus aureus TarS, the Wall Teichoic Acid β-glycosyltransferase Involved in Methicillin Resistance.

    Directory of Open Access Journals (Sweden)

    Solmaz Sobhanifar

    2016-12-01

    Full Text Available In recent years, there has been a growing interest in teichoic acids as targets for antibiotic drug design against major clinical pathogens such as Staphylococcus aureus, reflecting the disquieting increase in antibiotic resistance and the historical success of bacterial cell wall components as drug targets. It is now becoming clear that β-O-GlcNAcylation of S. aureus wall teichoic acids plays a major role in both pathogenicity and antibiotic resistance. Here we present the first structure of S. aureus TarS, the enzyme responsible for polyribitol phosphate β-O-GlcNAcylation. Using a divide and conquer strategy, we obtained crystal structures of various TarS constructs, mapping high resolution overlapping N-terminal and C-terminal structures onto a lower resolution full-length structure that resulted in a high resolution view of the entire enzyme. Using the N-terminal structure that encapsulates the catalytic domain, we furthermore captured several snapshots of TarS, including the native structure, the UDP-GlcNAc donor complex, and the UDP product complex. These structures along with structure-guided mutants allowed us to elucidate various catalytic features and identify key active site residues and catalytic loop rearrangements that provide a valuable platform for anti-MRSA drug design. We furthermore observed for the first time the presence of a trimerization domain composed of stacked carbohydrate binding modules, commonly observed in starch active enzymes, but adapted here for a poly sugar-phosphate glycosyltransferase.

  1. Framework of collagen type I - vasoactive vessels structuring invariant geometric attractor in cancer tissues: insight into biological magnetic field.

    Directory of Open Access Journals (Sweden)

    Jairo A Díaz

    Full Text Available In a previous research, we have described and documented self-assembly of geometric triangular chiral hexagon crystal-like complex organizations (GTCHC in human pathological tissues. This article documents and gathers insights into the magnetic field in cancer tissues and also how it generates an invariant functional geometric attractor constituted for collider partners in their entangled environment. The need to identify this hierarquic attractor was born out of the concern to understand how the vascular net of these complexes are organized, and to determine if the spiral vascular subpatterns observed adjacent to GTCHC complexes and their assembly are interrelational. The study focuses on cancer tissues and all the macroscopic and microscopic material in which GTCHC complexes are identified, which have been overlooked so far, and are rigorously revised. This revision follows the same parameters that were established in the initial phase of the investigation, but with a new item: the visualization and documentation of external dorsal serous vascular bed areas in spatial correlation with the localization of GTCHC complexes inside the tumors. Following the standard of the electro-optical collision model, we were able to reproduce and replicate collider patterns, that is, pairs of left and right hand spin-spiraled subpatterns, associated with the orientation of the spinning process that can be an expansion or contraction disposition of light particles. Agreement between this model and tumor data is surprisingly close; electromagnetic spiral patterns generated were identical at the spiral vascular arrangement in connection with GTCHC complexes in malignant tumors. These findings suggest that the framework of collagen type 1 - vasoactive vessels that structure geometric attractors in cancer tissues with invariant morphology sets generate collider partners in their magnetic domain with opposite biological behavior. If these principles are incorporated

  2. Optimizing {sup 18}F-FDG PET/CT imaging of vessel wall inflammation: the impact of {sup 18}F-FDG circulation time, injected dose, uptake parameters, and fasting blood glucose levels

    Energy Technology Data Exchange (ETDEWEB)

    Bucerius, Jan [Icahn School of Medicine at Mount Sinai, Translational and Molecular Imaging Institute, One Gustave L. Levy Place, P.O. Box 1234, New York, NY (United States); Mount Sinai School of Medicine, Department of Radiology, New York, NY (United States); Maastricht University Medical Center, Department of Nuclear Medicine, Maastricht (Netherlands); Maastricht University Medical Center, Cardiovascular Research Institute Maastricht (CARIM), Maastricht (Netherlands); University Hospital, RWTH Aachen, Department of Nuclear Medicine, Aachen (Germany); Mani, Venkatesh; Fayad, Zahi A. [Icahn School of Medicine at Mount Sinai, Translational and Molecular Imaging Institute, One Gustave L. Levy Place, P.O. Box 1234, New York, NY (United States); Mount Sinai School of Medicine, Department of Radiology, New York, NY (United States); Mount Sinai School of Medicine, Department of Cardiology, Zena and Michael A. Weiner Cardiovascular Institute and Marie-Josee and Henry R. Kravis Cardiovascular Health Center, New York, NY (United States); Moncrieff, Colin [Icahn School of Medicine at Mount Sinai, Translational and Molecular Imaging Institute, One Gustave L. Levy Place, P.O. Box 1234, New York, NY (United States); Mount Sinai School of Medicine, Department of Radiology, New York, NY (United States); Machac, Josef [Mount Sinai School of Medicine, Division of Nuclear Medicine, Department of Radiology, New York, NY (United States); Fuster, Valentin [Mount Sinai School of Medicine, Department of Cardiology, Zena and Michael A. Weiner Cardiovascular Institute and Marie-Josee and Henry R. Kravis Cardiovascular Health Center, New York, NY (United States); The Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid (Spain); Farkouh, Michael E. [Mount Sinai School of Medicine, Department of Cardiology, Zena and Michael A. Weiner Cardiovascular Institute and Marie-Josee and Henry R. Kravis Cardiovascular Health Center, New York, NY (United States); Mount Sinai School of Medicine, Cardiovascular Imaging Clinical Trials Unit, New York, NY (United States); Tawakol, Ahmed [Massachusetts General Hospital, Harvard University, Cardiac MR PET CT Program, Boston, MA (United States); Rudd, James H.F. [Cambridge University, Division of Cardiovascular Medicine, Cambridge (United Kingdom)

    2014-02-15

    {sup 18}F-FDG PET is increasingly used for imaging of vessel wall inflammation. However, limited data are available on the impact of methodological variables, i.e. prescan fasting glucose, FDG circulation time and injected FDG dose, and of different FDG uptake parameters, in vascular FDG PET imaging. Included in the study were 195 patients who underwent vascular FDG PET/CT of the aorta and the carotids. Arterial standardized uptake values ({sub mean}SUV{sub max}), target-to-background ratios ({sub mean}TBR{sub max}) and FDG blood-pool activity in the superior vena cava (SVC) and the jugular veins (JV) were quantified. Vascular FDG uptake values classified according to the tertiles of prescan fasting glucose levels, the FDG circulation time, and the injected FDG dose were compared using ANOVA. Multivariate regression analyses were performed to identify the potential impact of all variables described on the arterial and blood-pool FDG uptake. Tertile analyses revealed FDG circulation times of about 2.5 h and prescan glucose levels of less than 7.0 mmol/l, showing a favorable relationship between arterial and blood-pool FDG uptake. FDG circulation times showed negative associations with aortic{sub mean}SUV{sub max} values as well as SVC and JV FDG blood-pool activity, but positive correlations with aortic and carotid{sub mean}TBR{sub max} values. Prescan glucose levels were negatively associated with aortic and carotid{sub mean}TBR{sub max} and carotid{sub mean}SUV{sub max} values, but were positively correlated with SVC blood-pool uptake. The injected FDG dose failed to show any significant association with vascular FDG uptake. FDG circulation times and prescan blood glucose levels significantly affect FDG uptake in the aortic and carotid walls and may bias the results of image interpretation in patients undergoing vascular FDG PET/CT. The injected FDG dose was less critical. Therefore, circulation times of about 2.5 h and prescan glucose levels less than 7.0 mmol

  3. Advanced in-vessel retention design for next generation risk management

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Kune Y.; Hwang, Il Soon [Seoul National University, Seoul (Korea, Republic of)

    1997-12-31

    In the TMI-2 accident, approximately twenty (20) tons of molten core material drained into the lower plenum. Early advanced light water reactor (LWR) designs assumed a lower head failure and incorporated various measures for ex-vessel accident mitigation. However,one of the major findings from the TMI-2 Vessel Investigation Project was that one part of the reactor lower head wall estimated to have attained a temperature of 1100 deg C for about 30 minutes has seemingly experienced a comparatively rapid cooldown with no major threat to the vessel integrity. In this regard, recent empirical and analytical studies have shifted interests to such in-vessel retention designs or strategies as reactor cavity flooding, in-vessel flooding and engineered gap cooling of the vessel. Accurate thermohydrodynamic and creep deformation modeling and rupture prediction are the key to the success in developing practically useful in-vessel accident/risk management strategies. As an advanced in-vessel design concept, this work presents the COrium Attack Syndrome Immunization Structures (COASIS) that are being developed as prospective in-vessel retention devices for a next-generation LWR in concert with existing ex-vessel management measures. Both the engineered gap structures in-vessel (COASISI) and ex-vessel (COASISO) are demonstrated to maintain effective heat transfer geometry during molten core debris attack when applied to the Korean Standard Nuclear Power Plant (KSNPP) reactor. The likelihood of lower head creep rupture during a severe accident is found to be significantly suppressed by the COASIS options. 15 refs., 5 figs., 1 tab. (Author)

  4. Effect of alpha lipoic acid co-administration on structural and immunohistochemical changes in subcutaneous tissue of anterior abdominal wall of adult male albino rat in response to polypropylene mesh implantation.

    Science.gov (United States)

    Mazroa, Shireen A; Asker, Samar A; Asker, Waleed; Abd Ellatif, Mohamed

    2015-06-01

    Polypropylene mesh is commonly used in the treatment of abdominal hernia. Different approaches were addressed to improve their tissue integration and consequently reduce long-term complications. This study aimed to investigate the effect of alpha-lipoic acid (ALA) co-administration on structural and immunohistochemical (IHC) changes in the subcutaneous tissues of the anterior abdominal wall of the adult rat in response to polypropylene mesh implantation. Forty adult male albino rats were divided into: group I (control), group II (receiving ALA), group III (polypropylene mesh implantation) and group IV (mesh implantation + ALA co-administration). After 4 weeks, subcutaneous tissue samples were prepared for light microscopy and IHC study of CD34 as a marker for angiogenesis. In groups I and II rats, positive CD34 expression was demonstrated by IHC reaction, localized to endothelial cells lining small blood vessels. Group III showed an excess inflammatory reaction, deposition of both regular and irregularly arranged collagen fibres around mesh pores and few elastic fibres. CD34-positive was detected not only in cells lining small blood vessels but also in other cells scattered in the connective tissue indicating angiogenesis. In group IV, ALA co-administration resulted in less inflammatory reaction, regular collagen deposition, enhanced elastic fibres synthesis and a significant increase in CD34-positive cells and small blood vessels reflecting improved angiogenesis. ALA co-administration with polypropylene mesh implantation controlled the inflammatory reaction, helped regular collagen deposition, enhanced elastic fibres synthesis and improved angiogenesis in the subcutaneous tissue of anterior abdominal wall of adult albino rats, suggesting a possible role of ALA in optimizing mesh integration in subcutaneous tissue. © 2015 The Authors. International Journal of Experimental Pathology © 2015 International Journal of Experimental Pathology.

  5. Vessel wall reactions to endovascular stent implantation

    NARCIS (Netherlands)

    H.M.M. van Beusekom (Heleen)

    1993-01-01

    textabstractIn order to gain insight in the effects of stenting, we studied the process of wound healing and the short- and long-term effect of these permanently present foreign bodies. Both thrombogenic and less thrombogenic metals were evaluated with respect to thrombogenicity and tissue response.

  6. Structure of the poleward wall of the trough and the inclination of the geomagnetic field above the EISCAT radar

    Directory of Open Access Journals (Sweden)

    D. G. Jones

    Full Text Available A special high-resolution routine of the EISCAT radar has been used to investigate the structure and development of the poleward wall of a deep trough in electron density. The feature was tracked by the radar during a 7-hour period under very quiet geomagnetic conditions. The field-aligned nature of the structure enabled an estimate to be made of the inclination of the geomagnetic field above EISCAT that was in good agreement with the current model. Observations of narrow field-aligned enhancements in electron temperature demonstrated that the wall of this trough is a dynamic feature, reforming regularly as the electron density responds on a time scale of tens of minutes to energy input from soft-particle precipitation.

  7. Structure of the poleward wall of the trough and the inclination of the geomagnetic field above the EISCAT radar

    Directory of Open Access Journals (Sweden)

    D. G. Jones

    1997-06-01

    Full Text Available A special high-resolution routine of the EISCAT radar has been used to investigate the structure and development of the poleward wall of a deep trough in electron density. The feature was tracked by the radar during a 7-hour period under very quiet geomagnetic conditions. The field-aligned nature of the structure enabled an estimate to be made of the inclination of the geomagnetic field above EISCAT that was in good agreement with the current model. Observations of narrow field-aligned enhancements in electron temperature demonstrated that the wall of this trough is a dynamic feature, reforming regularly as the electron density responds on a time scale of tens of minutes to energy input from soft-particle precipitation.

  8. Discrimination of the wall effect in a thin counter with micro-gap structure for neutron position sensing

    Energy Technology Data Exchange (ETDEWEB)

    Sakae, Takeji; Manabe, Tohru; Kitamura, Yasunori; Nohtomi, Akihiro [Kyushu Univ., Fukuoka (Japan); Sakamoto, Sigeyasu

    1996-07-01

    Simulation by the Monte Carlo method is applied to estimate the wall effect in a thermal neutron counter having a new function for discriminating the effect. The counter is designed to have paralleled electrodes with micro-gap structure. A resistive anode is used for position sensing on the center of a set of the three electrode. The structure can be made by simple arrangement of anode and cathode wires on an insulator plane. The calculation shows discrimination of the wall effect can be achieved by coincident counting of two or three elements included in the counter. By using the coincident counting, the thickness of the neutron counter can be made into 1 mm with the information of the total energy created in the neutron detection. (author)

  9. Nonlinear Modeling of Autoclaved Aerated Concrete Masonry Wall Strengthened using Ferrocement Sandwich Structure

    KAUST Repository

    M., Abdel-Mooty

    2011-01-01

    Autoclaved Aerated Concrete (AAC) block are used mainly as non-load-bearing walls that provide heat insulation. This results in considerable saving in cooling energy particularly in hot desert environment with large variation of daily and seasonal temperatures. However, due to the relatively low strength there use load bearing walls is limited to single storey and low-rise construction. A system to enhance the strength of the AAC masonry wall in resisting both inplane vertical and combined vertical and lateral loads using ferrocement technology is proposed in this research. The proposed system significantly enhances the load carrying capacity and stiffness of the AAC wall without affecting its insulation characteristics. Ferrocement is made of cement mortar reinforced with closely spaced wire mesh. Full scale wall specimens with height of 2100mm and width of 1820mm were tested with different configuration of ferrocement. A finite elementmodel is developed and verified against the experimentalwork. The results of the finite element model correlates well with the experimental results.

  10. Network of endocardial vessels.

    Science.gov (United States)

    Lee, Byung-Cheon; Kim, Hong Bae; Sung, Baeckkyoung; Kim, Ki Woo; Sohn, Jamin; Son, Boram; Chang, Byung-Joon; Soh, Kwang-Sup

    2011-01-01

    Although there have been reports on threadlike structures inside the heart, they have received little attention. We aimed to develop a method for observing such structures and to reveal their ultrastructures. An in situ staining method, which uses a series of procedures of 0.2-0.4% trypan blue spraying and washing, was applied to observe threadlike structures on the surfaces of endocardia. The threadlike structures were isolated and observed by using confocal laser scanning microscopy (CLSM) and transmission electron microscopy (TEM). Networks of endocardial vessels (20 μm in thickness) with expansions (40-100 μm in diameter) were visualized; they were movable on the endocardium of the bovine atrium and ventricle. CLSM showed that (1) rod-shaped nuclei were aligned along the longitudinal direction of the endocardial vessel and (2) there were many cells inside the expansion. TEM on the endocardial vessel revealed that (1) there existed multiple lumens (1-7 μm in diameter) and (2) the extracellular matrices mostly consisted of collagen fibers, which were aligned along the longitudinal direction of the endocardial vessel or were locally organized in reticular structures. We investigated the endocardial circulatory system in bovine cardiac chambers and its ultrastructures, such as nucleic distributions, microlumens, and collagenous extracellular matrices. Copyright © 2011 S. Karger AG, Basel.

  11. Is the wood of spruces affected by immissions liable to show alterations of the cell wall structure

    Energy Technology Data Exchange (ETDEWEB)

    Sachsse, H.; Hapla, F.

    The results of investigations so far conducted showed no alterations of technological consequence either in the chemical composition or in the anatomical structure of the wood from trees affected by immissions. For the first time now the packing density of tracheid cell walls in spruces damaged by immissions is investigated by means of microscopic linear analysis. No significant difference was found as compared to the packing density of wood having been formed free of immission influence.

  12. Nucleon structure from mixed action calculations using 2+1 flavors of asqtad sea and domain wall valence fermions

    CERN Document Server

    Bratt, J.D.; Engelhardt, M.; Hagler, Ph.; Lin, H.W.; Lin, M.F.; Meyer, H.B.; Musch, B.; Negele, J.W.; Orginos, K.; Pochinsky, A.V.; Procura, M.; Richards, D.G.; Schroers, W.; Syritsyn, S.N.

    2010-01-01

    We present high statistics results for the structure of the nucleon from a mixed-action calculation using 2+1 flavors of asqtad sea and domain wall valence fermions. We perform extrapolations of our data based on different chiral effective field theory schemes and compare our results with available information from phenomenology. We discuss vector and axial form factors of the nucleon, moments of generalized parton distributions, including moments of forward parton distributions, and implications for the decomposition of the nucleon spin.

  13. Fourier transform mid infrared spectroscopy applications for monitoring the structural plasticity of plant cell walls.

    Science.gov (United States)

    Largo-Gosens, Asier; Hernández-Altamirano, Mabel; García-Calvo, Laura; Alonso-Simón, Ana; Alvarez, Jesús; Acebes, José L

    2014-01-01

    Fourier transform mid-infrared (FT-MIR) spectroscopy has been extensively used as a potent, fast and non-destructive procedure for analyzing cell wall architectures, with the capacity to provide abundant information about their polymers, functional groups, and in muro entanglement. In conjunction with multivariate analyses, this method has proved to be a valuable tool for tracking alterations in cell walls. The present review examines recent progress in the use of FT-MIR spectroscopy to monitor cell wall changes occurring in muro as a result of various factors, such as growth and development processes, genetic modifications, exposition or habituation to cellulose biosynthesis inhibitors and responses to other abiotic or biotic stresses, as well as its biotechnological applications.

  14. Structure of the complex between teicoplanin and a bacterial cell-wall peptide: use of a carrier-protein approach.

    Science.gov (United States)

    Economou, Nicoleta J; Zentner, Isaac J; Lazo, Edwin; Jakoncic, Jean; Stojanoff, Vivian; Weeks, Stephen D; Grasty, Kimberly C; Cocklin, Simon; Loll, Patrick J

    2013-04-01

    Multidrug-resistant bacterial infections are commonly treated with glycopeptide antibiotics such as teicoplanin. This drug inhibits bacterial cell-wall biosynthesis by binding and sequestering a cell-wall precursor: a D-alanine-containing peptide. A carrier-protein strategy was used to crystallize the complex of teicoplanin and its target peptide by fusing the cell-wall peptide to either MBP or ubiquitin via native chemical ligation and subsequently crystallizing the protein-peptide-antibiotic complex. The 2.05 Å resolution MBP-peptide-teicoplanin structure shows that teicoplanin recognizes its ligand through a combination of five hydrogen bonds and multiple van der Waals interactions. Comparison of this teicoplanin structure with that of unliganded teicoplanin reveals a flexibility in the antibiotic peptide backbone that has significant implications for ligand recognition. Diffraction experiments revealed an X-ray-induced dechlorination of the sixth amino acid of the antibiotic; it is shown that teicoplanin is significantly more radiation-sensitive than other similar antibiotics and that ligand binding increases radiosensitivity. Insights derived from this new teicoplanin structure may contribute to the development of next-generation antibacterials designed to overcome bacterial resistance.

  15. Manipulation of multiple 360o domain wall structures and its current-driven motion in a magnetic nanostripe

    Directory of Open Access Journals (Sweden)

    Wenjun Dong

    2015-11-01

    Full Text Available Dynamics of multiple transverse walls (TWs in a magnetic nanostripe is studied by micromagnetic simulations. It shows that, when TWs are arranged in a stripe with same orientation, they will attract each other and finally annihilate. However, when adjacent TWs are arranged with opposite orientation, a metastable complex wall can be formed, e.g., two TWs lead to 360o wall. For three or more TWs, the formed complex wall includes a number of 360o substructures, which is called multiple 360o structure (M360S here. The M360S itself may be used to store multiple logical data since each 360o substructure can act as logical ”0” or ”1”. On the other hand, the M360S may behave like single TW under an applied current, namely, the M360S can be driven steadily by current like that of single TW. A parity effect of the number of 360o substructures on the critical current for the annihilation is found. Namely, when the number is odd or even, the critical current increase or decrease with the increasing of the number, respectively. The parity effect is relevant to the out-of-plane magnetic moment of the M360S.

  16. Comparative structural and functional analysis of the larval and adult dorsal vessel and its role in hemolymph circulation in the mosquito Anopheles gambiae.

    Science.gov (United States)

    League, Garrett P; Onuh, Ogechukwu C; Hillyer, Julián F

    2015-02-01

    Hemolymph circulation in insects is driven primarily by the contractile action of a dorsal vessel, which is divided into an abdominal heart and a thoracic aorta. As holometabolous insects, mosquitoes undergo striking morphological and physiological changes during metamorphosis. This study presents a comprehensive structural and functional analysis of the larval and adult dorsal vessel in the malaria mosquito Anopheles gambiae. Using intravital video imaging we show that, unlike the adult heart, the larval heart contracts exclusively in the anterograde direction and does not undergo heartbeat directional reversals. The larval heart contracts 24% slower than the adult heart, and hemolymph travels across the larval dorsal vessel at a velocity that is 68% slower than what is seen in adults. By fluorescently labeling muscle tissue we show that although the general structure of the heart and its ostia are similar across life stages, the heart-associated alary muscles are significantly less robust in larvae. Furthermore, unlike the adult ostia, which are the entry points for hemolymph into the heart, the larval ostia are almost entirely lacking in incurrent function. Instead, hemolymph enters the larval heart through incurrent openings located at the posterior terminus of the heart. These posterior openings are structurally similar across life stages, but in adults have an opposite, excurrent function. Finally, the larval aorta and heart differ significantly in the arrangement of their cardiomyocytes. In summary, this study provides an in-depth developmental comparison of the circulatory system of larval and adult mosquitoes. © 2015. Published by The Company of Biologists Ltd.

  17. Forceful emplacement of the Eureka Valley-Joshua Flat-Beer Creek composite pluton into a structural basin in eastern California; internal structure and wall rock deformation

    Science.gov (United States)

    Morgan, Sven; Law, Richard; de Saint Blanquat, Michel

    2013-11-01

    Anisotropy of Magnetic Susceptibility parameters have been analyzed at 311 locations in the Eureka Valley-Joshua Flat-Beer Creek (EJB) pluton of eastern California. The large amount of data has allowed for the AMS parameters to be contoured using techniques that both reveal map-scale trends and emphasize small-scale differences. The contour maps suggest that magnetic susceptibility is dominantly controlled by composition of the magma but may also be affected by emplacement-related strain as the magma chamber inflated and forced the wall rocks outward. Pluton construction involved two major pulses of different composition magmas that were emplaced sequentially but with overlapping periods of crystallization. The magmas initially intruded as sill-like bodies into a structural basin. The magnetic foliation of the pluton cuts across internal magmatic contacts on the map scale and is parallel to local contacts between the pluton and surrounding metasedimentary wall rocks. The magnetic fabric is similar in orientation and symmetry to intense flattening strains recorded in the aureole rocks. The metasedimentary wall rocks have been shortened between 60 and 70% and this strain magnitude is approximately equal on the west, south, and east margins of the pluton. Strain in the wall rocks is dominantly flattening and concentrated into a narrow (1 km wide) inner aureole. Mapping of bedding/cleavage intersection lineations south of the pluton indicates that the magma made room for itself by translating the wall rocks outward and rotating the already inward dipping wall rocks of the structural basin to sub-vertical. Stretching of the inner aureole around an expanding magma chamber was responsible for the intense shortening. Limited data on the Marble Canyon pluton to the south of the EJB pluton indicates a very similar emplacement process.

  18. Structural Health Monitoring of Above-Ground Storage Tank Floors by Ultrasonic Guided Wave Excitation on the Tank Wall

    Directory of Open Access Journals (Sweden)

    Premesh S. Lowe

    2017-11-01

    Full Text Available There is an increasing interest in using ultrasonic guided waves to assess the structural degradation of above-ground storage tank floors. This is a non-invasive and economically viable means of assessing structural degradation. Above-ground storage tank floors are ageing assets which need to be inspected periodically to avoid structural failure. At present, normal-stress type transducers are bonded to the tank annular chime to generate a force field in the thickness direction of the floor and excite fundamental symmetric and asymmetric Lamb modes. However, the majority of above-ground storage tanks in use have no annular chime due to a simplified design and/or have a degraded chime due to corrosion. This means that transducers cannot be mounted on the chime to assess structural health according to the present technology, and the market share of structural health monitoring of above-ground storage tank floors using ultrasonic guided wave is thus limited. Therefore, the present study investigates the potential of using the tank wall to bond the transducer instead of the tank annular chime. Both normal and shear type transducers were investigated numerically, and results were validated using a 4.1 m diameter above-ground storage tank. The study results show shear mode type transducers bonded to the tank wall can be used to assess the structural health of the above-ground tank floors using an ultrasonic guided wave. It is also shown that for the cases studied there is a 7.4 dB signal-to-noise ratio improvement at 45 kHz for the guided wave excitation on the tank wall using shear mode transducers.

  19. Structural Health Monitoring of Above-Ground Storage Tank Floors by Ultrasonic Guided Wave Excitation on the Tank Wall.

    Science.gov (United States)

    Lowe, Premesh S; Duan, Wenbo; Kanfoud, Jamil; Gan, Tat-Hean

    2017-11-04

    There is an increasing interest in using ultrasonic guided waves to assess the structural degradation of above-ground storage tank floors. This is a non-invasive and economically viable means of assessing structural degradation. Above-ground storage tank floors are ageing assets which need to be inspected periodically to avoid structural failure. At present, normal-stress type transducers are bonded to the tank annular chime to generate a force field in the thickness direction of the floor and excite fundamental symmetric and asymmetric Lamb modes. However, the majority of above-ground storage tanks in use have no annular chime due to a simplified design and/or have a degraded chime due to corrosion. This means that transducers cannot be mounted on the chime to assess structural health according to the present technology, and the market share of structural health monitoring of above-ground storage tank floors using ultrasonic guided wave is thus limited. Therefore, the present study investigates the potential of using the tank wall to bond the transducer instead of the tank annular chime. Both normal and shear type transducers were investigated numerically, and results were validated using a 4.1 m diameter above-ground storage tank. The study results show shear mode type transducers bonded to the tank wall can be used to assess the structural health of the above-ground tank floors using an ultrasonic guided wave. It is also shown that for the cases studied there is a 7.4 dB signal-to-noise ratio improvement at 45 kHz for the guided wave excitation on the tank wall using shear mode transducers.

  20. Structure and function of the first full-length murein peptide ligase (Mpl cell wall recycling protein.

    Directory of Open Access Journals (Sweden)

    Debanu Das

    2011-03-01

    Full Text Available Bacterial cell walls contain peptidoglycan, an essential polymer made by enzymes in the Mur pathway. These proteins are specific to bacteria, which make them targets for drug discovery. MurC, MurD, MurE and MurF catalyze the synthesis of the peptidoglycan precursor UDP-N-acetylmuramoyl-L-alanyl-γ-D-glutamyl-meso-diaminopimelyl-D-alanyl-D-alanine by the sequential addition of amino acids onto UDP-N-acetylmuramic acid (UDP-MurNAc. MurC-F enzymes have been extensively studied by biochemistry and X-ray crystallography. In gram-negative bacteria, ∼30-60% of the bacterial cell wall is recycled during each generation. Part of this recycling process involves the murein peptide ligase (Mpl, which attaches the breakdown product, the tripeptide L-alanyl-γ-D-glutamyl-meso-diaminopimelate, to UDP-MurNAc. We present the crystal structure at 1.65 Å resolution of a full-length Mpl from the permafrost bacterium Psychrobacter arcticus 273-4 (PaMpl. Although the Mpl structure has similarities to Mur enzymes, it has unique sequence and structure features that are likely related to its role in cell wall recycling, a function that differentiates it from the MurC-F enzymes. We have analyzed the sequence-structure relationships that are unique to Mpl proteins and compared them to MurC-F ligases. We have also characterized the biochemical properties of this enzyme (optimal temperature, pH and magnesium binding profiles and kinetic parameters. Although the structure does not contain any bound substrates, we have identified ∼30 residues that are likely to be important for recognition of the tripeptide and UDP-MurNAc substrates, as well as features that are unique to Psychrobacter Mpl proteins. These results provide the basis for future mutational studies for more extensive function characterization of the Mpl sequence-structure relationships.

  1. Structural profiling and biological performance of phospholipid-hyaluronan functionalized single-walled carbon nanotubes

    DEFF Research Database (Denmark)

    Dvash, Ram; Khatchatouriants, Artium; Solmesky, Leonardo J

    2013-01-01

    In spite of significant insolubility and toxicity, carbon nanotubes (CNTs) erupt into the biomedical research, and create an increasing interest in the field of nanomedicine. Single-walled CNTs (SWCNTs) are highly hydrophobic and have been shown to be toxic while systemically administrated. Thus,...

  2. Effects of multi-wall carbon nanotubes on structural and mechanical ...

    Indian Academy of Sciences (India)

    2017-09-22

    Sep 22, 2017 ... Abstract. Poly(3-hydroxybutyrate) (PHB)/chitosan electrospun scaffold was recently prepared for cartilage tissue engineering purpose. The drawback of this scaffold was its low mechanical properties. This study was carried out to see if addition of multi-wall carbon nanotubes (MWNTs) to PHB/chitosan ...

  3. Effects of multi-wall carbon nanotubes on structural and mechanical ...

    Indian Academy of Sciences (India)

    Poly(3-hydroxybutyrate) (PHB)/chitosan electrospun scaffold was recently prepared for cartilage tissue engineering purpose. The drawback of this scaffold was its low mechanical properties. This study was carried out to see if addition of multi-wall carbon nanotubes (MWNTs) to PHB/chitosan polymeric blend can show ...

  4. Structural and chemical evolution of single-wall carbon nanotubes under atomic and molecular deuterium interaction

    NARCIS (Netherlands)

    Lisowski, W.F.; Keim, Enrico G.; van den Berg, A.H.J.; Smithers, M.A.; Smithers, Mark A.

    2005-01-01

    The interaction of atomic (D) and molecular (D2) deuterium, as present in a (D + D2) gas mixture, with single-wall carbon nanotubes (SWNTs) has been studied by means of a combination of scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The SWNT

  5. An investigation on vulnerability assessment of steel structures with thin steel shear wall through development of fragility curves

    Directory of Open Access Journals (Sweden)

    Mohsen Gerami

    2017-02-01

    Full Text Available Fragility curves play an important role in damage assessment of buildings. Probability of damage induction to the structure against seismic events can be investigated upon generation of afore mentioned curves. In current research 360 time history analyses have been carried out on structures of 3, 10 and 20 story height and subsequently fragility curves have been adopted. The curves are developed based on two indices of inter story drifts and equivalent strip axial strains of the shear wall. Time history analysis is carried out in Perform 3d considering 10 far field seismograms and 10 near fields. Analysis of low height structures revealed that they are more vulnerable in accelerations lower than 0.8 g in near field earthquakes because of higher mode effects. Upon the generated fragility curves it was observed that middle and high structures have more acceptable performance and lower damage levels compared to low height structures in both near and far field seismic hazards.

  6. ITER Vacuum Vessel design and construction

    Energy Technology Data Exchange (ETDEWEB)

    Ioki, K., E-mail: Kimihiro.Ioki@iter.org [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Choi, C.H.; Daly, E.; Dani, S.; Davis, J.; Giraud, B.; Gribov, Y.; Hamlyn-Harris, C. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Jones, L. [F4E, c/Josep Pla, n.2, Torres Diagonal Litoral, Edificio B3, E-08019 Barcelona (Spain); Jun, C. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Kim, B.C. [NFRI, 52 Yeoeundong Yuseonggu, Daejeon 305-333 (Korea, Republic of); Kuzmin, E. [NTC ' Sintez' , Efremov Inst., 189631 Metallostroy, St. Petersburg (Russian Federation); Le Barbier, R.; Martinez, J.-M. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Pathak, H. [ITER-India, A-29, GIDC Electronic Estate, Sector -25, Gandhinagar 382025 (India); Preble, J.; Reich, J. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Sa, J.W. [NFRI, 52 Yeoeundong Yuseonggu, Daejeon 305-333 (Korea, Republic of); Terasawa, A.; Utin, Yu. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); and others

    2012-08-15

    After implementing a few design modifications (referred to as the 'Modified Reference Design') in 2009, the Vacuum Vessel (VV) design had been stabilized. The VV design is being finalized, including interface components such as support rails and feedthroughs for the in-vessel coils. It is necessary to make adjustments to the locations of the blanket supports and manifolds to accommodate design modifications to the in-vessel coils. The VV support design is also being finalized considering a structural simplification. Design of the in-wall shielding (IWS) has progressed, considering the assembly methods and the required tolerances. The detailed layout of ferritic steel plates and borated steel plates was optimized based on the toroidal field ripple analysis. A dynamic test on the inter-modular key to support the blanket modules was performed to measure the dynamic amplification factor (DAF). An R and D program has started to select and qualify the welding and cutting processes for the port flange lip seal. The ITER VV material 316 L(N) IG was already qualified and the Modified Reference Design was approved by the Agreed Notified Body (ANB) in accordance with the Nuclear Pressure Equipment Order procedure.

  7. Analysis of the response of a reinforced concrete shear wall structure during earthquakes using the transfer matrix method of multibody systems

    Directory of Open Access Journals (Sweden)

    Jianguo Ding

    2016-05-01

    Full Text Available Although reinforced concrete shear wall structures are widely used in high-rise buildings, the methods used to analyze the seismic response of such a structure during an earthquake generally have low calculation efficiencies. In this article, the transfer matrix method of multibody systems is first established as a mechanical model of a regular reinforced concrete shear wall structure with both bifurcated and closed transfer paths to analyze the seismic responses of structures. By separating the shear wall legs, establishing a state vector relationship between the two endpoints of the coupling beams, and combining all state vectors of the inputs or outputs of each shear wall leg, the total transfer between shear wall legs is realized, and the overall transfer equation and overall transfer matrix of a shear wall structure are obtained. Applying the transfer matrix method of multibody systems, a 15-story shear wall structure is used as an engineering example to analyze seismic responses for frequent and rare earthquakes using MATLAB software. The findings show that the transfer matrix method of multibody systems provides similar results to ANSYS but that the transfer matrix method of multibody systems greatly increases calculation efficiency while maintaining accuracy.

  8. Changes in the abundance of cell wall apiogalacturonan and xylogalacturonan and conservation of rhamnogalacturonan II structure during the diversification of the Lemnoideae.

    Science.gov (United States)

    Avci, Utku; Peña, Maria J; O'Neill, Malcolm A

    2017-12-29

    The diversification of the Lemnoideae was accompanied by a reduction in the abundance of cell wall apiogalacturonan and an increase in xylogalacturonan whereas rhamnogalacturonan II structure and cross-linking are conserved. The subfamily Lemnoideae is comprised of five genera and 38 species of small, fast-growing aquatic monocots. Lemna minor and Spirodela polyrhiza belong to this subfamily and have primary cell walls that contain large amounts of apiogalacturonan and thus are distinct from the primary walls of most other flowering plants. However, the pectins in the cell walls of other members of the Lemnoideae have not been investigated. Here, we show that apiogalacturonan decreased substantially as the Lemnoideae diversified since Wolffiella and Wolffia walls contain between 63 and 88% less apiose than Spirodela, Landoltia, and Lemna walls. In Wolffia, the most derived genus, xylogalacturonan is far more abundant than apiogalacturonan, whereas in Wolffiella pectic polysaccharides have a high arabinose content, which may arise from arabinan sidechains of RG I. The apiose-containing pectin rhamnogalacturonan II (RG-II) exists in Lemnoideae walls as a borate cross-linked dimer and has a glycosyl sequence similar to RG-II from terrestrial plants. Nevertheless, species-dependent variations in the extent of methyl-etherification of RG-II sidechain A and arabinosylation of sidechain B are discernible. Immunocytochemical studies revealed that pectin methyl-esterification is higher in developing daughter frond walls than in mother frond walls, indicating that methyl-esterification is associated with expanding cells. Our data support the notion that a functional cell wall requires conservation of RG-II structure and cross-linking but can accommodate structural changes in other pectins. The Lemnoideae provide a model system to study the mechanisms by which wall structure and composition has changed in closely related plants with similar growth habits.

  9. Analysis of Multi-Loop Control Structures of Dividing-Wall Distillation Columns Using a Fundamental Model

    Directory of Open Access Journals (Sweden)

    Salvador Tututi-Avila

    2014-02-01

    Full Text Available Dividing-wall columns (DWCs have significant potential as energy-efficient processes for the separation of multicomponent mixtures. However, in addition to an efficient steady state design, dynamics and control also play a major part for the success of a technology. This is especially so for complex distillation systems. This paper investigates the dynamics of a dividing wall column used for the separation of ternary mixtures. A detailed dynamic first principles-based model of the column I s developed in gPROMS. The model is used to generate data used for control loop pairing via the Relative Gain Array (RGA, and controller parameters are found by using Internal Model Control (IMC tuning. The best control structures for DWC systems, involving four different ternary mixtures, and two different feed compositions for each mixture, are investigated.

  10. Immunogold scanning electron microscopy can reveal the polysaccharide architecture of xylem cell walls.

    Science.gov (United States)

    Sun, Qiang; Sun, Yuliang; Juzenas, Kevin

    2017-04-01

    Immunofluorescence microscopy (IFM) and immunogold transmission electron microscopy (TEM) are the two main techniques commonly used to detect polysaccharides in plant cell walls. Both are important in localizing cell wall polysaccharides, but both have major limitations, such as low resolution in IFM and restricted sample size for immunogold TEM. In this study, we have developed a robust technique that combines immunocytochemistry with scanning electron microscopy (SEM) to study cell wall polysaccharide architecture in xylem cells at high resolution over large areas of sample. Using multiple cell wall monoclonal antibodies (mAbs), this immunogold SEM technique reliably localized groups of hemicellulosic and pectic polysaccharides in the cell walls of five different xylem structures (vessel elements, fibers, axial and ray parenchyma cells, and tyloses). This demonstrates its important advantages over the other two methods for studying cell wall polysaccharide composition and distribution in these structures. In addition, it can show the three-dimensional distribution of a polysaccharide group in the vessel lateral wall and the polysaccharide components in the cell wall of developing tyloses. This technique, therefore, should be valuable for understanding the cell wall polysaccharide composition, architecture and functions of diverse cell types. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  11. Strain-controlled magnetic domain wall propagation in hybrid piezoelectric/ferromagnetic structures.

    Science.gov (United States)

    Lei, Na; Devolder, Thibaut; Agnus, Guillaume; Aubert, Pascal; Daniel, Laurent; Kim, Joo-Von; Zhao, Weisheng; Trypiniotis, Theodossis; Cowburn, Russell P; Chappert, Claude; Ravelosona, Dafiné; Lecoeur, Philippe

    2013-01-01

    The control of magnetic order in nanoscale devices underpins many proposals for integrating spintronics concepts into conventional electronics. A key challenge lies in finding an energy-efficient means of control, as power dissipation remains an important factor limiting future miniaturization of integrated circuits. One promising approach involves magnetoelectric coupling in magnetostrictive/piezoelectric systems, where induced strains can bear directly on the magnetic anisotropy. While such processes have been demonstrated in several multiferroic heterostructures, the incorporation of such complex materials into practical geometries has been lacking. Here we demonstrate the possibility of generating sizeable anisotropy changes, through induced strains driven by applied electric fields, in hybrid piezoelectric/spin-valve nanowires. By combining magneto-optical Kerr effect and magnetoresistance measurements, we show that domain wall propagation fields can be doubled under locally applied strains. These results highlight the prospect of constructing low-power domain wall gates for magnetic logic devices.

  12. Structural insights into the pH-controlled targeting of plant cell-wall invertase by a specific inhibitor protein

    Science.gov (United States)

    Hothorn, Michael; Van den Ende, Wim; Lammens, Willem; Rybin, Vladimir; Scheffzek, Klaus

    2010-01-01

    Invertases are highly regulated enzymes with essential functions in carbohydrate partitioning, sugar signaling, and plant development. Here we present the 2.6 Å crystal structure of Arabidopsis cell-wall invertase 1 (INV1) in complex with a protein inhibitor (CIF, or cell-wall inhibitor of β-fructosidase) from tobacco. The structure identifies a small amino acid motif in CIF that directly targets the invertase active site. The activity of INV1 and its interaction with CIF are strictly pH-dependent with a maximum at about pH 4.5. At this pH, isothermal titration calorimetry reveals that CIF tightly binds its target with nanomolar affinity. CIF competes with sucrose (Suc) for the same binding site, suggesting that both the extracellular Suc concentration and the pH changes regulate association of the complex. A conserved glutamate residue in the complex interface was previously identified as an important quantitative trait locus affecting fruit quality, which implicates the invertase–inhibitor complex as a main regulator of carbon partitioning in plants. Comparison of the CIF/INV1 structure with the complex between the structurally CIF-related pectin methylesterase inhibitor (PMEI) and pectin methylesterase indicates a common targeting mechanism in PMEI and CIF. However, CIF and PMEI use distinct surface areas to selectively inhibit very different enzymatic scaffolds. PMID:20858733

  13. Structural insights into the pH-controlled targeting of plant cell-wall invertase by a specific inhibitor protein.

    Science.gov (United States)

    Hothorn, Michael; Van den Ende, Wim; Lammens, Willem; Rybin, Vladimir; Scheffzek, Klaus

    2010-10-05

    Invertases are highly regulated enzymes with essential functions in carbohydrate partitioning, sugar signaling, and plant development. Here we present the 2.6 Å crystal structure of Arabidopsis cell-wall invertase 1 (INV1) in complex with a protein inhibitor (CIF, or cell-wall inhibitor of β-fructosidase) from tobacco. The structure identifies a small amino acid motif in CIF that directly targets the invertase active site. The activity of INV1 and its interaction with CIF are strictly pH-dependent with a maximum at about pH 4.5. At this pH, isothermal titration calorimetry reveals that CIF tightly binds its target with nanomolar affinity. CIF competes with sucrose (Suc) for the same binding site, suggesting that both the extracellular Suc concentration and the pH changes regulate association of the complex. A conserved glutamate residue in the complex interface was previously identified as an important quantitative trait locus affecting fruit quality, which implicates the invertase-inhibitor complex as a main regulator of carbon partitioning in plants. Comparison of the CIF/INV1 structure with the complex between the structurally CIF-related pectin methylesterase inhibitor (PMEI) and pectin methylesterase indicates a common targeting mechanism in PMEI and CIF. However, CIF and PMEI use distinct surface areas to selectively inhibit very different enzymatic scaffolds.

  14. Modeling the microclimate inside a vessel in in vitro culture : vessel ...

    African Journals Online (AJOL)

    Numerical simulations show that variations in vessel internal humidity was sensitive to transfer coefficient, climatic conditions within the growth chamber, evaporation and condensation of water vapor on the walls of the vessel. The variations in water vapor pressure deficits (VPD) (low during the nyctiperiod and high during ...

  15. Experimental observation of the interaction of propagating spin waves with Néel domain walls in a Landau domain structure

    Energy Technology Data Exchange (ETDEWEB)

    Pirro, P.; Sebastian, T.; Leven, B.; Hillebrands, B. [Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern (Germany); Koyama, T. [Department of Applied Physics, Faculty of Engineering, The University of Tokyo, Bunkyo, Tokyo 113-8656 (Japan); Brächer, T. [Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern (Germany); Graduate School Materials Science in Mainz, Gottlieb-Daimler-Strasse 47, 67663 Kaiserslautern (Germany)

    2015-06-08

    The interaction of propagating dipolar spin waves with magnetic domain walls is investigated in square-shaped microstructures patterned from the Heusler compound Co{sub 2}Mn{sub 0.6}Fe{sub 0.4}Si. Using magnetic force microscopy, the reversible preparation of a Landau state with four magnetic domains separated by Néel domain walls is confirmed. A local spin-wave excitation using a microstructured antenna is realized in one of the domains. It is shown by Brillouin light scattering microscopy that the domain structure in the remanence state has a strong influence on the spin-wave excitation and propagation. The domain walls strongly reflect the spin waves and can be used as spin-wave reflectors. A comparison with micromagnetic simulations shows that the strong reflection is due to the long-range dipolar interaction which has important implications for the use of these spin waves for exerting an all-magnonic spin-transfer torque.

  16. Synthesis of palladium nanoparticle modified reduced graphene oxide and multi-walled carbon nanotube hybrid structures for electrochemical applications

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jie, E-mail: hujie@tyut.edu.cn [Micro and Nano System Research Center, Key Lab of Advanced Transducers and Intelligent Control System (Ministry of Education) & College of Information Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi (China); Zhao, Zhenting; Zhang, Jun; Li, Gang; Li, Pengwei; Zhang, Wendong [Micro and Nano System Research Center, Key Lab of Advanced Transducers and Intelligent Control System (Ministry of Education) & College of Information Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi (China); Lian, Kun, E-mail: liankun@tyut.edu.cn [Micro and Nano System Research Center, Key Lab of Advanced Transducers and Intelligent Control System (Ministry of Education) & College of Information Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi (China); School of Nano-Science and Nano-Engineering, Suzhou & Collaborative Innovation Center of Suzhou Nano Science and Technology, Xi' an Jiaotong University, Xi' an, 710049 (China); Center for Advanced Microstructures and Devices, Louisiana State University, LA, 70806 (United States)

    2017-02-28

    Graphical abstract: A sensitive hydrazine electrochemical sensor was fabricated by using palladium (Pd) nanoparticle functionalized reduced graphene oxide (rGO) and multi-walled carbon nanotube (MWCNTs) hybrid structures (Pd/rGO-MWCNTs). - Highlights: • rGO-MWCNTs hybrid structures and Pd nanoparticles are prepared using electrochemical methods. • rGO-MWCNTs hybrid films are used as supports and co-catalysts for Pd nanoparticles. • The Pd/rGO-MWCNTs hybrid structure based sensor shows an ultra-high sensitivity of 7.09 μA μM{sup −1} cm{sup −2} and a low detection limit of 0.15 μM. • The proposed electrochemical sensor exhibits excellent selectivity. - Abstract: In this work, palladium (Pd) nanoparticles functionalized reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs) hybrid structures (Pd/rGO-MWCNTs) were successfully prepared by a combination of electrochemical reduction with electrodeposition method. The morphology, structure, and composition of the Pd/rGO-MWCNTs hybrid were characterized by scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy. The as-synthesized hybrid structures were modified on the glassy carbon electrode (GCE) and further utilized for hydrazine sensing. Electrochemical impedance spectroscopic, cyclic voltammetry and single-potential amperometry experiments were carried out on Pd/rGO-MWCNTs hybrid structures to investigate the interface properties and sensing performance. The measured results demonstrate that the fabricated Pd/rGO-MWCNTs/GCE sensor show a high sensitivity of 7.09 μA μM{sup −1} cm{sup −2} in a large concentration range of 1.0 to 1100 μM and a low detection limit of 0.15 μM. Moreover, the as-prepared sensor exhibits good selectivity and stability for the determination of hydrazine under interference conditions.

  17. Vessel segmentation in screening mammograms

    Science.gov (United States)

    Mordang, J. J.; Karssemeijer, N.

    2015-03-01

    Blood vessels are a major cause of false positives in computer aided detection systems for the detection of breast cancer. Therefore, the purpose of this study is to construct a framework for the segmentation of blood vessels in screening mammograms. The proposed framework is based on supervised learning using a cascade classifier. This cascade classifier consists of several stages where in each stage a GentleBoost classifier is trained on Haar-like features. A total of 30 cases were included in this study. In each image, vessel pixels were annotated by selecting pixels on the centerline of the vessel, control samples were taken by annotating a region without any visible vascular structures. This resulted in a total of 31,000 pixels marked as vascular and over 4 million control pixels. After training, the classifier assigns a vesselness likelihood to the pixels. The proposed framework was compared to three other vessel enhancing methods, i) a vesselness filter, ii) a gaussian derivative filter, and iii) a tubeness filter. The methods were compared in terms of area under the receiver operating characteristics curves, the Az values. The Az value of the cascade approach is 0:85. This is superior to the vesselness, Gaussian, and tubeness methods, with Az values of 0:77, 0:81, and 0:78, respectively. From these results, it can be concluded that our proposed framework is a promising method for the detection of vessels in screening mammograms.

  18. Wall Painting Investigation by Means of Non-invasive Terahertz Time-Domain Imaging (THz-TDI): Inspection of Subsurface Structures Buried in Historical Plasters

    Science.gov (United States)

    Dandolo, Corinna Ludovica Koch; Jepsen, Peter Uhd

    2016-02-01

    Characterization of subsurface features of wall paintings is important in conservation and technical art history as well as in building archaeology and architecture fields. In this study, an area of the apsidal wall painting of Nebbelunde Church (Rødby, Denmark) has been investigated by means of terahertz time-domain imaging (THz-TDI). Subsurface structures have been detected at different depths inside the lime-based plaster of the wall painting until approximately 1 cm from the surface. The surface morphology of the buried structures has been 3D imaged in detail, providing a substantial contribution in their characterization.

  19. Wall Painting Investigation by Means of Non-invasive Terahertz Time-Domain Imaging (THz-TDI): Inspection of Subsurface Structures Buried in Historical Plasters

    DEFF Research Database (Denmark)

    Dandolo, Corinna Ludovica Koch; Jepsen, Peter Uhd

    2016-01-01

    Characterization of subsurface features of wall paintings is important in conservation and technical art history as well as in building archaeology and architecture fields. In this study, an area of the apsidal wall painting of Nebbelunde Church (Rødby, Denmark) has been investigated by means...... of terahertz time-domain imaging (THz-TDI). Subsurface structures have been detected at different depths inside the lime-based plaster of the wall painting until approximately 1 cm from the surface. The surface morphology of the buried structures has been 3D imaged in detail, providing a substantial...

  20. Damage by radiation in structural materials of BWR reactor vessels; Dano por radiacion en materiales estructurales de vasijas de reactores BWR

    Energy Technology Data Exchange (ETDEWEB)

    Robles, E.; Balcazar, M.; Alpizar, A.M.; Calderon, B.E. [Departamento de Sintesis y Caracterizacion de Materiales, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2002-07-01

    The structural materials which are manufactured the pressure vessels of the BWR reactors undergo degradation in their mechanical properties mainly due to the damage produced by the fast neutrons (E> 1 MeV) coming from the reactor core. The mechanisms of neutron damage in this type of materials are experimentally studied, through the irradiation of vessel steel in experimental reactors for a quickly ageing. Alternately the neutron damage through steel irradiation with heavy ions is simulated. In this work the first results of the damage induced by irradiation of a similar steel to the vessel of a BWR reactor are shown. The irradiation was performed with fast neutrons (E> 1 MeV, fluence of 1.45 x 10{sup 18} n/cm{sup 2}) in the TRIGA Mark III Salazar reactor and separately with Ni{sup +3} ions in a Tandetrom accelerator (E= 4.8 MeV and an ion flux rank of 0.1 to 53 ions/A{sup 2}). (Author)

  1. Comparative study of the cell wall composition of broccoli, carrot, and tomato: structural characterization of the extractable pectins and hemicelluloses.

    Science.gov (United States)

    Houben, Ken; Jolie, Ruben P; Fraeye, Ilse; Van Loey, Ann M; Hendrickx, Marc E

    2011-07-01

    This study delivers a comparison of the pectic and hemicellulosic cell wall polysaccharides between the commonly used vegetables broccoli (stem and florets separately), carrot, and tomato. Alcohol-insoluble residues were prepared from the plant sources and sequentially extracted with water, cyclohexane-trans-1,2-diamine tetra-acetic acid, sodium carbonate, and potassium hydroxide solutions, to obtain individual fractions, each containing polysaccharides bound to the cell wall in a specific manner. Structural characterization of the polysaccharide fractions was conducted using colorimetric and chromatographic approaches. Sugar ratios were defined to ameliorate data interpretation. These ratios allowed gaining information concerning polysaccharide structure from sugar composition data. Structural analysis of broccoli revealed organ-specific characteristics: the pectin degree of methoxylation (DM) of stem and florets differed, the sugar composition data inferred differences in polymeric composition. On the other hand, the molar mass (MM) distribution profiles of the polysaccharide fractions were virtually identical for both organs. Carrot root displayed a different MM distribution for the polysaccharides solubilized by potassium hydroxide compared to broccoli and tomato, possibly due to the high contribution of branched pectins to this otherwise hemicellulose-enriched fraction. Tomato fruit showed the pectins with the broadest range in DM, the highest MM, the greatest overall linearity and the lowest extent of branching of rhamnogalacturonan I, pointing to particularly long, linear pectins in tomato compared with the other vegetable organs studied, suggesting possible implications toward functional behavior. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Developing LBM Process Parameters for Ti-6Al-4V Thin Wall Structures and Determining the Corresponding Mechanical Characteristics

    Science.gov (United States)

    Ahuja, Bhrigu; Schaub, Adam; Karg, Michael; Lechner, Michael; Merklein, Marion; Schmidt, Michael

    The Laser Beam Melting (LBM) process technology within the family of Additive Manufacturing technology is characterized by its ability to fabricate fully dense 3D structures directly from micro-sized metal powder. With the current state of the art, Ti-6Al-4V has been processed using LBM machine systems constituting a laser with a beam diameter of about 100 μm. In order to fabricate structures with smaller wall thicknesses, processing of Ti-6Al-4V is attempted on the LBM machine system, Realizer SLM 50 consisting of a laser with a beam diameter 10 μm. The proposed paper presents the development of process parameters for fabricating fully dense Ti-6Al-4V 3D structures using the LBM machine system, Realizer SLM 50. Further experiments are carried out to determine the wall thickness and mechanical properties achievable using the selected process parameters. Analysis and scientific arguments are presented to explain the influence of building direction and heat treatment on mechanical properties.

  3. Helical structure of longitudinal vortices embedded in turbulent wall-bounded flow

    DEFF Research Database (Denmark)

    Velte, Clara Marika; Hansen, Martin Otto Laver; Okulov, Valery

    2009-01-01

    Embedded vortices in turbulent wall-bounded flow over a flat plate, generated by a passive rectangular vane-type vortex generator with variable angle \\beta to the incoming flow in a low-Reynolds number flow (Re = 2600 based on the inlet grid mesh size L = 0:039 m and free stream velocity U......_{\\infty} = 1.0 ms^{-1}) have been studied with respect to helical symmetry. The studies were carried out in a low-speed closed-circuit wind tunnel utilizing Stereoscopic Particle Image Velocimetry (SPIV). The vortices have been shown to possess helical symmetry, allowing the flow to be described in a simple...

  4. Structural stability of transparent conducting films assembled from length purified single-wall carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    J. M. Harris; G. R. S. Iyer; D. O. Simien; J. A. Fagan; J. Y. Huh; J. Y. Chung; S. D. Hudson; J. Obrzut; J. F. Douglas; C. M. Stafford; E. K. Hobbie

    2011-01-01

    Single-wall carbon nanotube (SWCNT) films show significant promise for transparent electronics applications that demand mechanical flexibility, but durability remains an outstanding issue. In this work, thin membranes of length purified single-wall carbon nanotubes (SWCNTs) are uniaxially and isotropically compressed by depositing them on prestrained polymer substrates. Upon release of the strain, the topography, microstructure, and conductivity of the films are characterized using a combination of optical/fluorescence microscopy, light scattering, force microscopy, electron microscopy, and impedance spectroscopy. Above a critical surface mass density, films assembled from nanotubes of well-defined length exhibit a strongly nonlinear mechanical response. The measured strain dependence reveals a dramatic softening that occurs through an alignment of the SWCNTs normal to the direction of prestrain, which at small strains is also apparent as an anisotropic increase in sheet resistance along the same direction. At higher strains, the membrane conductivities increase due to a compression-induced restoration of conductive pathways. Our measurements reveal the fundamental mode of elasto-plastic deformation in these films and suggest how it might be suppressed.

  5. Monte Carlo calculations on the magnetization profile and domain wall structure in bulk systems and nanoconstricitons

    Energy Technology Data Exchange (ETDEWEB)

    Serena, P. A. [Instituto de Ciencias de Materiales de Madrid, Madrid (Spain); Costa-Kraemer, J. L. [Instituto de Microelectronica de Madrid, Madrid (Spain)

    2001-03-01

    A Monte Carlo algorithm suitable to study systems described by an anisotropic Heisenberg Hamiltonian is presented. This technique has been tested successfully with 3D and 2D systems, illustrating how magnetic properties depend on the dimensionality and the coordination number. We have found that magnetic properties of constrictions differ from those appearing in bulk. In particular, spin fluctuations are considerable larger than those calculated for bulk materials. In addition, domain walls are strongly modified when a constriction is present, with a decrease of the domain-wall width. This decrease is explained in terms of previous theoretical works. [Spanish] Se presenta un algoritmo de Monte Carlo para estudiar sistemas discritos por un hamiltoniano anisotropico de Heisenburg. Esta tecnica ha sido probada exitosamente con sistemas de dos y tres dimensiones, ilustrado con las propiedades magneticas dependen de la dimensionalidad y el numero de coordinacion. Hemos encontrado que las propiedades magneticas de constricciones difieren de aquellas del bulto. En particular, las fluctuaciones de espin son considerablemente mayores. Ademas, las paredes de dominio son fuertemente modificadas cuando una construccion esta presente, originando un decrecimiento del ancho de la pared de dominio. Damos cuenta de este decrecimiento en terminos de un trabajo teorico previo.

  6. Separation and purification of soluble polymers and cell wall fractions from wheat, rye and hull less barley endosperm flours for structure-nutrition studies.

    Science.gov (United States)

    Comino, Penny; Shelat, Kinnari; Collins, Helen; Lahnstein, Jelle; Gidley, Michael J

    2013-12-11

    The nutritional values associated with the cell walls of cereal endosperm flours are due to a combination of solubilized arabinoxylan and (1-3,1-4)-β-d-glucan as well as residual nonsolubilized cell wall material. In order to investigate structure-nutrition relationships, an appropriate method for the complete functional and structural characterization of cell wall polysaccharides in various cereal endosperm flours is described. This involves the separation of soluble polymers and the residual cell wall fraction without using organic solvents, and the fractionation of soluble polymers into arabinoxylan- and (1-3,1-4)-β-d-glucan-rich fractions for subsequent analysis. This methodology is applied to endosperm flours from wheat, hull-less barley and rye, and could be extended to include studies on the effects of food processing with respect to yield and characteristics of the three fractions in order to better understand the structural basis for nutritional functionality.

  7. Structural damages prevention of the ITER vacuum vessel and ports by elasto-plastic analysis with regards to RCC-MR

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Jean-Marc, E-mail: jean-marc.martinez@iter.org [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Jun, Chang Hoon; Portafaix, Christophe; Alekseev, Alexander; Sborchia, Carlo; Choi, Chang-Ho [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Albin, Vincent [SOM Calcul – Groupe ORTEC, 121 ancien Chemin de Cassis – Immeuble Grand Pré, 13009 Marseille (France); Borrelly, Stephane [Sogeti High Tech, RE2, 180 rue René Descartes, Le Millenium – Bat C, 13857 Aix en Provence (France); Cambazar, Magali [Assystem EOS, 117 rue Jacquard, 84120 Pertuis (France); Gaucher, Thomas [SOM Calcul – Groupe ORTEC, 121 ancien Chemin de Cassis – Immeuble Grand Pré, 13009 Marseille (France); Sfarni, Samir; Tailhardat, Olivier [Assystem EOS, 117 rue Jacquard, 84120 Pertuis (France)

    2015-10-15

    Highlights: • ITER vacuum vessel (VV) is a part of the first barrier to confine the plasma. • ITER VV as NPE necessitates a third party organization authorized by the French nuclear regulator to assure design, fabrication, and conformance testing and quality assurance, i.e. ANB. • Several types of damages have to be prevented in order to guarantee the structural integrity with regards to RCC-MR. • It is usual to employ non-linear analysis when the “classical” elastic analysis reaches its limit of linear application. • Several structural analyses were performed with many different global and local models of the whole ITER VV. - Abstract: Several types of damages have to be prevented in order to guarantee the structural integrity of a structure with regards to RCC-MR; the P-type damages which can result from the application to a structure of a steadily and regularly increasing loading or a constant loading and the S-type damages during operational loading conditions which can only result from repeated application of loadings associated to the progressive deformations and fatigue. Following RCC-MR, the S-type damages prevention has to be started only when the structural integrity is guaranteed against P-type damages. The verification of the last one on the ITER vacuum vessel and ports has been performed by limit analysis with elasto-(perfectly)plastic material behavior. It is usual to employ non-linear analysis when the “classical” elastic analysis reaches its limit of linear application. Some elasto-plastic analyses have been performed considering several cyclic loadings to evaluate also more realistic structural margins of the against S-type damages.

  8. Extrapleural Inner Thoracic Wall Lesions: Multidetector CT Findings

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seung Soo; Kim, Young Tong; Jou, Sung Shik [Soonchunhyang University, Cheonan Hospital, Cheonan (Korea, Republic of)

    2010-06-15

    The extrapleural space is external to the parietal pleura in the thorax. The structures within and adjacent to this region include the fat pad, endothoracic fascia, intercostal muscles, connective tissue, nerves, vessels, and ribs. Further, the space is divided into the inner and outer thoracic wall by the innermost intercostal muscle. Extrapleural lesions in the inner thoracic wall are classified as air-containing lesions, fat-containing lesions, and soft tissue-containing lesions according on their main component. Air-containing lesions include extrapleural air from direct chest trauma and extrapleural extension from pneumomediastinum. Prominent extrapleural fat is seen in decreased lung volume conditions, and can also be seen in normal individuals. Soft tissue-containing lesions include extrapleural extensions from a pleural or chest wall infection as well as tumors and extrapleural hematoma. We classify extrapleural lesions in the inner thoracic wall and illustrate their imaging findings

  9. NUMERICAL ANALYSIS OF THE CRITICAL STATE OF THIN-WALLED STRUCTURE WITH Z-PROFILE CROSS SECTION

    Directory of Open Access Journals (Sweden)

    Patryk Różyło

    2017-03-01

    Full Text Available The object of the study was the thin-walled profile with Z-shaped cross section made of the carbon-epoxy composite. Material model was prepared based on the implemented orthotropic properties. The purpose of study was to determine the value of the critical load at which buckling occurs, the form of buckling and operating characteristics in critical condition. In order to achieve this numerical analysis were carried out. Additionally, the effects of the modification in arrangement of layers of the laminate to the stability and strength of thin-walled composite structures was presented. Numerical studies were carried out using commercial simulation software - ABAQUS®. Within the FEM research, both forms of buckling and the associated critical load, dependent on the configuration the layers of the composite were achieved. Analysis of the obtained results, allowed the evaluation of the structure's work in relation to the level of energy consumption or rigidity estimation. In the paper only numerical simulations of the critical state were conducted.

  10. Sexithiophene encapsulated in a single-walled carbon nanotube: an in situ Raman spectroelectrochemical study of a peapod structure.

    Science.gov (United States)

    Kalbáč, Martin; Kavan, Ladislav; Gorantla, Sandeep; Gemming, Thomas; Dunsch, Lothar

    2010-10-11

    The interaction of single-walled carbon nanotubes (SWCNTs) and α-sexithiophene (6T) was studied by Raman spectroscopy and by in situ Raman spectroelectrochemistry. The encapsulation of 6T in SWCNT and its interaction causes a bleaching of its photoluminescence, and also small shifts of its Raman bands. The Raman features of the SWCNT with embedded 6T (6T-peapods) change in both intensity and frequency compared to those of pristine SWCNT, which is a consequence of a change of the resonant condition. Electrochemical doping demonstrated that the electrode potential applied to the SWCNT wall causes changes in the embedded 6T. The effects of electrochemical charging on the Raman features of pristine SWCNT and 6T@SWCNT were compared. It is shown that the interaction of SWCNT with 6T also changes the electronic structure of SWCNT in its charged state. This change of electronic structure is demonstrated both for semiconducting and metallic tubes. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Structural Alteration in Dermal Vessels and Collagen Bundles following Exposure of Skin Wound to Zeolite–Bentonite Compound

    Directory of Open Access Journals (Sweden)

    Shahram Paydar

    2016-01-01

    Full Text Available Background. This study examines the impact of one-time direct application of haemostatic agent zeolite–bentonite powder to wounded skin on the healing process in rats. Materials and Methods. 24 male Sprague-Dawley rats were randomly allocated into two groups (n=12: (1 the rats whose wounds were washed only with sterile normal saline (NS-treated and (2 those treated with zeolite–bentonite compound (ZEO-treated. The wound was circular, full-thickness, and 2 cm in diameter. At the end of the 12th day, six animals from each group were randomly selected and terminated. The remaining rats were terminated after 21 days. Just after scarification, skin samples were excised and sent for stereological evaluation. Results. The results showed a significant difference between the two groups regarding the length density of the blood vessels and diameter of the large and small vessels on the 12th day after the wound was inflicted. Besides, volume density of both the dermis and collagen bundles was reduced by 25% in the ZEO-treated rats in comparison to the NS-treated animals after 21 days. Conclusions. One-time topical usage of zeolite–bentonite haemostatic powder on an animal skin wound might negatively affect the healing process through vasoconstriction and inhibition of neoangiogenesis.

  12. Very Versatile Vessel

    Science.gov (United States)

    2009-09-01

    data. This source provides information on aluminum hydrofoil vessels without the added weight of foil structures. The composite armor around the...seating compartment. The sides should also limit wave splash on the deck. The freeboard should contribute reserve buoyancy , increasing large-angle and...Resistance, Powering, and Propulsion Savitsky’s Method Since model testing data or other reliable performance data was unavailable for the proposed

  13. Easy Come, Easy Go: Capillary Forces Enable Rapid Refilling of Embolized Primary Xylem Vessels.

    Science.gov (United States)

    Rolland, Vivien; Bergstrom, Dana M; Lenné, Thomas; Bryant, Gary; Chen, Hua; Wolfe, Joe; Holbrook, N Michele; Stanton, Daniel E; Ball, Marilyn C

    2015-08-01

    Protoxylem plays an important role in the hydraulic function of vascular systems of both herbaceous and woody plants, but relatively little is known about the processes underlying the maintenance of protoxylem function in long-lived tissues. In this study, embolism repair was investigated in relation to xylem structure in two cushion plant species, Azorella macquariensis and Colobanthus muscoides, in which vascular water transport depends on protoxylem. Their protoxylem vessels consisted of a primary wall with helical thickenings that effectively formed a pit channel, with the primary wall being the pit channel membrane. Stem protoxylem was organized such that the pit channel membranes connected vessels with paratracheal parenchyma or other protoxylem vessels and were not exposed directly to air spaces. Embolism was experimentally induced in excised vascular tissue and detached shoots by exposing them briefly to air. When water was resupplied, embolized vessels refilled within tens of seconds (excised tissue) to a few minutes (detached shoots) with water sourced from either adjacent parenchyma or water-filled vessels. Refilling occurred in two phases: (1) water refilled xylem pit channels, simplifying bubble shape to a rod with two menisci; and (2) the bubble contracted as the resorption front advanced, dissolving air along the way. Physical properties of the protoxylem vessels (namely pit channel membrane porosity, hydrophilic walls, vessel dimensions, and helical thickenings) promoted rapid refilling of embolized conduits independent of root pressure. These results have implications for the maintenance of vascular function in both herbaceous and woody species, because protoxylem plays a major role in the hydraulic systems of leaves, elongating stems, and roots. © 2015 American Society of Plant Biologists. All Rights Reserved.

  14. Hybrid TE-TM scheme for time domain numerical calculations of wakefields in structures with walls of finite conductivity

    Directory of Open Access Journals (Sweden)

    Andranik Tsakanian

    2012-05-01

    Full Text Available In particle accelerators a preferred direction, the direction of motion, is well defined. If in a numerical calculation the (numerical dispersion in this direction is suppressed, a quite coarse mesh and moderate computational resources can be used to reach accurate results even for extremely short electron bunches. Several approaches have been proposed in the past decades to reduce the accumulated dispersion error in wakefield calculations for perfectly conducting structures. In this paper we extend the TE/TM splitting algorithm to a new hybrid scheme that allows for wakefield calculations in structures with walls of finite conductivity. The conductive boundary is modeled by one-dimensional wires connected to each boundary cell. A good agreement of the numerical simulations with analytical results and other numerical approaches is obtained.

  15. Application of the Hybrid Simulation Method for the Full-Scale Precast Reinforced Concrete Shear Wall Structure

    Directory of Open Access Journals (Sweden)

    Zaixian Chen

    2018-02-01

    Full Text Available The hybrid simulation (HS testing method combines physical test and numerical simulation, and provides a viable alternative to evaluate the structural seismic performance. Most studies focused on the accuracy, stability and reliability of the HS method in the small-scale tests. It is a challenge to evaluate the seismic performance of a twelve-story pre-cast reinforced concrete shear-wall structure using this HS method which takes the full-scale bottom three-story structural model as the physical substructure and the elastic non-linear model as the numerical substructure. This paper employs an equivalent force control (EFC method with implicit integration algorithm to deal with the numerical integration of the equation of motion (EOM and the control of the loading device. Because of the arrangement of the test model, an elastic non-linear numerical model is used to simulate the numerical substructure. And non-subdivision strategy for the displacement inflection point of numerical substructure is used to easily realize the simulation of the numerical substructure and thus reduce the measured error. The parameters of the EFC method are calculated basing on analytical and numerical studies and used to the actual full-scale HS test. Finally, the accuracy and feasibility of the EFC-based HS method is verified experimentally through the substructure HS tests of the pre-cast reinforced concrete shear-wall structure model. And the testing results of the descending stage can be conveniently obtained from the EFC-based HS method.

  16. Effect of airway surface liquid on the forces on the pharyngeal wall: Experimental fluid-structure interaction study.

    Science.gov (United States)

    Pirnar, Jernej; Širok, Brane; Bombač, Andrej

    2017-10-03

    Obstructive sleep apnoea syndrome (OSAS) is a breathing disorder with a multifactorial etiology. The respiratory epithelium is lined with a thin layer of airway surface liquid preventing interactions between the airflow and epithelium. The effect of the liquid lining in OSAS pathogenesis remains poorly understood despite clinical research. Previous studies have shown that the physical properties of the airway surface liquid or altered stimulation of the airway mechanoreceptors could alleviate or intensify OSAS; however, these studies do not provide a clear physical interpretation. To study the forces transmitted from the airflow to the liquid-lined compliant wall and to discuss the effects of the airway surface liquid properties on the stimulation of the mechanoreceptors, a novel and simplified experimental system mimicking the upper airway fundamental characteristics (i.e., liquid-lined compliant wall and complex unsteady airflow features) was constructed. The fluctuating force on the compliant wall was reduced through a damping mechanism when the liquid film thickness and/or the viscosity were increased. Conversely, the liquid film damping was reduced when the surface tension decreased. Based on the experimental data, empirical correlations were developed to predict the damping potential of the liquid film. In the future, this will enable us to extend the existing computational fluid-structure interaction simulations of airflow in the human upper airway by incorporating the airway surface liquid effect without adopting two-phase flow interface tracking methods. Furthermore, the experimental system developed in this study could be used to investigate the fundamental principles of the complex once/twice-coupled physical phenomena. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Engineering the Oryza sativa cell wall with rice NAC transcription factors regulating secondary wall formation.

    Science.gov (United States)

    Yoshida, Kouki; Sakamoto, Shingo; Kawai, Tetsushi; Kobayashi, Yoshinori; Sato, Kazuhito; Ichinose, Yasunori; Yaoi, Katsuro; Akiyoshi-Endo, Miho; Sato, Hiroko; Takamizo, Tadashi; Ohme-Takagi, Masaru; Mitsuda, Nobutaka

    2013-01-01

    Plant tissues that require structural rigidity synthesize a thick, strong secondary cell wall of lignin, cellulose and hemicelluloses in a complicated bridged structure. Master regulators of secondary wall synthesis were identified in dicots, and orthologs of these regulators have been identified in monocots, but regulation of secondary cell wall formation in monocots has not been extensively studied. Here we demonstrate that the rice transcription factors SECONDARY WALL NAC DOMAIN PROTEINs (SWNs) can regulate secondary wall formation in rice (Oryza sativa) and are potentially useful for engineering the monocot cell wall. The OsSWN1 promoter is highly active in sclerenchymatous cells of the leaf blade and less active in xylem cells. By contrast, the OsSWN2 promoter is highly active in xylem cells and less active in sclerenchymatous cells. OsSWN2 splicing variants encode two proteins; the shorter protein (OsSWN2S) has very low transcriptional activation ability, but the longer protein (OsSWN2L) and OsSWN1 have strong transcriptional activation ability. In rice, expression of an OsSWN2S chimeric repressor, driven by the OsSWN2 promoter, resulted in stunted growth and para-wilting (leaf rolling and browning under normal water conditions) due to impaired vascular vessels. The same OsSWN2S chimeric repressor, driven by the OsSWN1 promoter, caused a reduction of cell wall thickening in sclerenchymatous cells, a drooping leaf phenotype, reduced lignin and xylose contents and increased digestibility as forage. These data suggest that OsSWNs regulate secondary wall formation in rice and manipulation of OsSWNs may enable improvements in monocotyledonous crops for forage or biofuel applications.

  18. Engineering the Oryza sativa cell wall with rice NAC transcription factors regulating secondary wall formation

    Directory of Open Access Journals (Sweden)

    Kouki eYoshida

    2013-10-01

    Full Text Available Plant tissues that require structural rigidity synthesize a thick, strong secondary cell wall of lignin, cellulose and hemicelluloses in a complicated bridged structure. Master regulators of secondary wall synthesis were identified in dicots, and orthologs of these regulators have been identified in monocots, but regulation of secondary cell wall formation in monocots has not been extensively studied. Here we demonstrate that the rice transcription factors SECONDARY WALL NAC DOMAIN PROTEINs (SWNs can regulate secondary wall formation in rice (Oryza sativa and are potentially useful for engineering the monocot cell wall. The OsSWN1 promoter is highly active in sclerenchymatous cells of the leaf blade and less active in xylem cells. By contrast, the OsSWN2 promoter is highly active in xylem cells and less active in sclerenchymatous cells. OsSWN2 splicing variants encode two proteins; the shorter protein (OsSWN2S has very low transcriptional activation ability, but the longer protein (OsSWN2L and OsSWN1 have strong transcriptional activation ability. In rice, expression of an OsSWN2S chimeric repressor, driven by the OsSWN2 promoter, resulted in stunted growth and para-wilting (leaf rolling and browning under normal water conditions due to impaired vascular vessels. The same OsSWN2S chimeric repressor, driven by the OsSWN1 promoter, caused a reduction of cell wall thickening in sclerenchymatous cells, a drooping leaf phenotype, reduced lignin and xylose contents and increased digestibility as forage. These data suggest that OsSWNs regulate secondary wall formation in rice and manipulation of OsSWNs may enable improvements in monocotyledonous crops for forage or biofuel applications.

  19. Acetylation of cell wall is required for structural integrity of the leaf surface and exerts a global impact on plant stress responses

    DEFF Research Database (Denmark)

    Nafisi, Majse; Stranne, Maria; Fimognari, Lorenzo

    2015-01-01

    The epidermis on leaves protects plants from pathogen invasion and provides a waterproof barrier. It consists of a layer of cells that is surrounded by thick cell walls, which are partially impregnated by highly hydrophobic cuticular components. We show that the Arabidopsis T-DNA insertion mutant...... acetylation is essential for maintaining the structural integrity of leaf epidermis, and that reduction of cell wall acetylation leads to global stress responses in Arabidopsis....

  20. Reduced metabolic function and structural alterations in inherited retinal dystrophies: investigating the effect of peripapillary vessel oxygen saturation and vascular diameter on the retinal nerve fibre layer thickness.

    Science.gov (United States)

    Bojinova, Rossiana I; Türksever, Cengiz; Schötzau, Andreas; Valmaggia, Christophe; Schorderet, Daniel F; Todorova, Margarita G

    2017-05-01

    To evaluate the relationship between the peripapillary metabolic alterations [retinal vessel Oximetry (RO)] and the structural findings [retinal vessel diameter and retinal nerve fibre layer thickness (RNFL)] in patients with inherited retinal dystrophies (IRD). Patients with IRD [24 patients with rod-cone dystrophy (RCD), 15 patients with cone-rod dystrophy, 13 patients with inherited maculopathy] and 18 age-matched controls, who underwent RO imaging and spectral domain optical coherence tomography, were included. The average and quadrant oxygen saturation in all four major peripapillary retinal arterioles (A-SO2 ) and venules (V-SO2 ) were measured, and their difference (A-V SO2 ) was calculated. The corresponding retinal vessel diameter of these arterioles (D-A) and venules (D-V) was measured. The data were compared to the peripapillary RNFL thickness within the IRD subgroups and to the data obtained in the controls. In general, patients with IRD had higher average V-SO2 values when compared to controls (p ≤ 0.029). Rod-cone dystrophy (RCD) patients differed from controls, but also from patients with other IRDs, when the average and quadrant oxygen saturation values (A-SO2 and V-SO2 ) were evaluated (p ≤ 0.026). Within the RCD group, the correlations of RNFL thickness to V-SO2 , A-V SO2 , D-A and D-V were significant (p ≤ 0.030), thus indicating a different relationship between the RNFL thickness and the examined parameters, when compared to the other groups. It becomes evident from our combined metabolic-structural approach that a prediction model, to identify which individual is at risk of developing a photoreceptor degeneration of RCD type, can be proposed. It will take into account the peripapillary retinal oxygen saturation, the retinal vessel diameter and the RNFL thickness values. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  1. Conformational structural changes of bacteriorhodopsin adsorbed onto single-walled carbon nanotubes.

    Science.gov (United States)

    Bertoncini, Patricia; Chauvet, Olivier

    2010-04-01

    The interaction between purple membranes, composed of proteins of bacteriorhodopsin (bR) and their native surrounding lipids, and single-walled carbon nanotubes (SWNT) has been investigated. In this work, sonication has been used to debundle SWNT in buffer solution without surfactant before the addition of native purple membranes. The sample was then sonicated in a bath for a short time, followed by a centrifugation. The supernatants contain proteins in excess and SWNT as individual and small bundles covered by a bR layer with an average thickness of 1.5 nm. TEM and AFM observations support the idea that only a protein monolayer surrounds the tubes. Optical absorption and infrared spectroscopy measurements provide evidence that the proteins adsorbed onto the SWNT undergo orientational changes of the helical segments in bR and helix conformational changes. We ascribe the main driving force to the hydrophobic interactions between the sidewall of the SWNT and the hydrophobic residues of the alpha-helices of bR.

  2. Joining and fabrication techniques for high temperature structures including the first wall in fusion reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ho Jin; Lee, B. S.; Kim, K. B

    2003-09-01

    The materials for PFC's (Plasma Facing Components) in a fusion reactor are severely irradiated with fusion products in facing the high temperature plasma during the operation. The refractory materials can be maintained their excellent properties in severe operating condition by lowering surface temperature by bonding them to the high thermal conducting materials of heat sink. Hence, the joining and bonding techniques between dissimilar materials is considered to be important in case of the fusion reactor or nuclear reactor which is operated at high temperature. The first wall in the fusion reactor is heated to approximately 1000 .deg. C and irradiated severely by the plasma. In ITER, beryllium is expected as the primary armour candidate for the PFC's; other candidates including W, Mo, SiC, B4C, C/C and Si{sub 3}N{sub 4}. Since the heat affected zones in the PFC's processed by conventional welding are reported to have embrittlement and degradation in the sever operation condition, both brazing and diffusion bonding are being considered as prime candidates for the joining technique. In this report, both the materials including ceramics and the fabrication techniques including joining technique between dissimilar materials for PFC's are described. The described joining technique between the refractory materials and the dissimilar materials may be applicable for the fusion reactor and Generation-4 future nuclear reactor which are operated at high temperature and high irradiation.

  3. Exact Thermal Analysis of Functionally Graded Cylindrical and Spherical Vessels

    Directory of Open Access Journals (Sweden)

    Vebil Yıldırım

    2017-07-01

    Full Text Available Thermal analyses of radially functionally graded (FG thick-walled a spherical vessel and an infinite cylindrical vessel or a circular annulus are conducted analytically by the steady-state 1-D Fourier heat conduction theory under Dirichlet’s boundary conditions. By employing simple-power material grading pattern the differential equations are obtained in the form of Euler-Cauchy types. Analytical solution of the differential equations gives the temperature field and the heat flux distribution in the radial direction in a closed form. Three different physical metal-ceramic pairs first considered to study the effect of the aspect ratio, which is defined as the inner radius to the outer radius of the structure, on the temperature and heat flux variation along the radial coordinate. Then a parametric study is performed with hypothetic inhomogeneity indexes for varying aspect ratios.

  4. Numerical Estimation of the Elastic Properties of Thin-Walled Structures Manufactured from Short-Fiber-Reinforced Thermoplastics

    Science.gov (United States)

    Altenbach, H.; Naumenko, K.; L'vov, G. I.; Pilipenko, S. N.

    2003-05-01

    A model which allows us to estimate the elastic properties of thin-walled structures manufactured by injection molding is presented. The starting step is the numerical prediction of the microstructure of a short-fiber-reinforced composite developed during the filling stage of the manufacturing process. For this purpose, the Moldflow Plastic Insight® commercial program is used. As a result of simulating the filling process, a second-rank orientation tensor characterizing the microstructure of the material is obtained. The elastic properties of the prepared material locally depend on the orientational distribution of fibers. The constitutive equation is formulated by means of orientational averaging for a given orientation tensor. The tensor of elastic material properties is computed and translated into the format for a stress-strain analysis based on the ANSYSÒ finite-element code. The numerical procedure and the convergence of results are discussed for a thin strip, a rectangular plate, and a shell of revolution. The influence of manufacturing conditions on the stress-strain state of statically loaded thin-walled elements is illustrated.

  5. Freezing Temperatures, Ice Nanotubes Structures, and Proton Ordering of TIP4P/ICE Water inside Single Wall Carbon Nanotubes.

    Science.gov (United States)

    Pugliese, P; Conde, M M; Rovere, M; Gallo, P

    2017-11-16

    A very recent experimental paper importantly and unexpectedly showed that water in carbon nanotubes is already in the solid ordered phase at the temperature where bulk water boils. The water models used so far in literature for molecular dynamics simulations in carbon nanotubes show freezing temperatures lower than the experiments. We present here results from molecular dynamics simulations of water inside single walled carbon nanotubes using an extremely realistic model for both liquid and icy water, the TIP4P/ICE. The water behavior inside nanotubes of different diameters has been studied upon cooling along the isobars at ambient pressure starting from temperatures where water is in a liquid state. We studied the liquid/solid transition, and we observed freezing temperatures higher than in bulk water and that depend on the diameter of the nanotube. The maximum freezing temperature found is 390 K, which is in remarkable agreement with the recent experimental measurements. We have also analyzed the ice structure called "ice nanotube" that water forms inside the single walled carbon nanotubes when it freezes. The ice forms observed are in agreement with previous results obtained with different water models. A novel finding, a partial proton ordering, is evidenced in our ice nanotubes at finite temperature.

  6. Structural characterization of a mixed-linkage glucan deficient mutant reveals alteration in cellulose microfibril orientation in rice coleoptile mesophyll cell walls

    Directory of Open Access Journals (Sweden)

    Andreia Michelle Smith-Moritz

    2015-08-01

    Full Text Available The CELLULOSE SYNTHASE-LIKE F6 (CslF6 gene was previously shown to mediate the biosynthesis of mixed-linkage glucan (MLG, a cell wall polysaccharide that is hypothesized to be a tightly associated with cellulose and also have a role in cell expansion in the primary cell wall of young seedlings in grass species. We have recently shown that loss-of-function cslf6 rice mutants do not accumulate MLG in most vegetative tissues. Despite the absence of a structurally important polymer, MLG, these mutants are unexpectedly viable and only show a moderate growth compromise compared to wild type. Therefore these mutants are ideal biological systems to test the current grass cell wall model. In order to gain a better understanding of the role of MLG in the primary wall, we performed in-depth compositional and structural analyses of the cell walls of three day-old rice seedlings using various biochemical and novel microspectroscopic approaches. We found that cellulose content as well as matrix polysaccharide composition was not significantly altered in the MLG deficient mutant. However, we observed a significant change in cellulose microfibril bundle organization in mesophyll cell walls of the cslf6 mutant. Using synchrotron source Fourier Transform Mid-Infrared Spectromicroscopy for high-resolution imaging, we determined that the bonds associated with cellulose and arabinoxylan, another major component of the primary cell was of grasses, were in a lower energy configuration compared to wild type, suggesting a slightly weaker primary wall in MLG deficient mesophyll cells. Taken together, these results suggest that MLG may influence cellulose deposition in mesophyll cell walls without significantly affecting anisotropic growth thus challenging MLG importance in cell wall expansion.

  7. Vessel Operator System

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Operator cards are required for any operator of a charter/party boat and or a commercial vessel (including carrier and processor vessels) issued a vessel permit from...

  8. Fire development and wall endurance in sandwich and wood-frame structures

    Science.gov (United States)

    Carlton A. Holmes; Herbert W. Eickner; John J. Brenden; Curtis C. Peters; Robert H. White

    1980-01-01

    Large-scale fire tests were conducted on seven 16- by 24-foot structures. Four of these structures were of sandwich construction with cores of plastic or paper honeycomb and three were of wood-frame construction. The wasss were loaded to a computer design loading, and the fire endurance determined under a fire exposure from a typical building contents loading of 4-1/2...

  9. Effects of SPORL and dilute acid pretreatment on substrate morphology, cell physical and chemical wall structures, and subsequent enzymatic hydrolysis of lodgepole pine

    Science.gov (United States)

    Xinping Li; Xiaolin Luo; Kecheng Li; J.Y. Zhu; J. Dennis Fougere; Kimberley Clarke

    2012-01-01

    The effects of pretreatment by dilute acid and sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) on substrate morphology, cell wall physical and chemical structures, along with the subsequent enzymatic hydrolysis of lodgepole pine substrate were investigated. FE-SEM and TEM images of substrate structural morphological changes showed that SPORL...

  10. Fractal structures of single-walled carbon nanotubes in biologically relevant conditions: role of chirality vs. media conditions.

    Science.gov (United States)

    Khan, Iftheker A; Aich, Nirupam; Afrooz, A R M Nabiul; Flora, Joseph R V; Schierz, P Ariette; Ferguson, P Lee; Sabo-Attwood, Tara; Saleh, Navid B

    2013-11-01

    Aggregate structure of covalently functionalized chiral specific semiconducting single-walled carbon nanotubes (SWNTs) was systematically studied employing static light scattering (SLS). Fractal dimensions (Df) of two specific chirality SWNTs-SG65 and SG76 with (6, 5) and (7, 6) chiral enrichments-were measured under four biological exposure media conditions, namely: Dulbecco's Modified Eagle Medium (DMEM), Minimum Essential Medium (MEM), Roswell Park Memorial Institute (RPMI) 1640 medium, and 0.9% saline solution. The SWNTs exhibited chiral dependence on Df with SG65 showing more fractal or loosely bound aggregate structures, i.e., lower Df values (range of 2.24±0.03 to 2.64±0.05), compared to the SG76 sample (range of 2.58±0.13 to 2.90±0.08). All the Df values reported are highly reproducible, measured from multiple SLS runs and estimated with 'random block-effects' statistical analysis that yielded all p values to be fractal aggregates. Moreover, presence of fetal bovine serum (FBS) and bovine serum albumin (BSA), used to mimic the in vitro cell culture condition, reduced the Df values, i.e., created more fractal structures. Steric hindrance to aggregation was identified as the key mechanism for creating the fractal structures. Also, increase in FBS concentration from 1% to 10% resulted in increasingly lower Df values. Published by Elsevier Ltd.

  11. Structure and Immunological Specificity of the Streptococcus mutans Group b Cell Wall Antigen

    Science.gov (United States)

    Mukasa, Hidehiko; Slade, Hutton D.

    1973-01-01

    The Streptococcus mutans group b antigen of strain FA1 has been defined as to chemical composition and immunological specificity. The antigen in cold trichloroacetic acid extracts was fractionated on diethylaminoethyl-Sephadex A-25 at pH 8.5. Two forms were isolated: a polysaccharide and a mucoprotein. The two polymers reacted as a single substance in agar gel diffusion against specific adsorbed FA1 rabbit antisera but were separated by gel immunoelectrophoresis. No reaction with any other S. mutans or streptococcal group sera occurred. Galactose composed about one-third and galactosamine about 3% of the total weight of each polymer. Rhamnose was a major component of the polysaccharide (47%) but was present only in traces in the mucoprotein. The protein content of the latter was about 40%. No significant quantities of glycerol, phosphorus, or muramic acid were present in either case. Pepsin and trypsin had no effect on the serological specificity of the mucoprotein. d-Galactose and d-galactosamine were strong inhibitors (70%) of the precipitin reaction, whereas d-glucose, d-glucosamine, and N-acetyl-d-glucosamine inhibited between 25 and 35%. The results indicate that the antigen is a major antigenic component of the cell wall and that the specificity of the antigen resides in binding sites which contain both d-galactose and d-galactosamine. Agglutination of whole cells by specific group b antiserum indicates the antibody receptor sites of the polysaccharide antigen are at the surface of the streptococcal cell. The mucoprotein, but not the polysaccharide, was released from the cell by lysozyme. Lysis did not occur. The immunological specificity and other characteristics of the antigen establishes it as the identifying antigen of S. mutans group b. Images PMID:4128403

  12. Load capacity of a thick-walled cylinder with a radial hole

    Energy Technology Data Exchange (ETDEWEB)

    Laczek, S.; Rys, J. [Institute of Machine Design, Cracow University of Technology, Al. Jana Pawla II 37, 31 864 Krakow (Poland); Zielinski, A.P., E-mail: apz@mech.pk.edu.p [Institute of Machine Design, Cracow University of Technology, Al. Jana Pawla II 37, 31 864 Krakow (Poland)

    2010-08-15

    The paper deals with elastic-plastic analysis of the stress-strain state in the vicinity of a hole in a thick-walled cylindrical pressure vessel. The investigations have been inspired by the phenomenon of ductile fracture observed in a high-pressure reactor. Using finite element calculations, different failure criteria are proposed to aid design and control of high-pressure vessels with piping attachments. They are compared with suggestions of American (ASME) and European (EN) standards. A simple shakedown analysis of the structure is also presented. The local stress distribution near the hole results in a specific failure of the vessel. A plastic zone appears in the vicinity of the internal cylinder surface and propagates along the hole side. The vessel unloading can cause local reverse plasticity, which leads to plastic shakedown in the small zone and then to progressive ductile fracture in this zone. This is dangerous for the whole structure.

  13. Field-induced structures and rheology of a magnetorheological suspension confined between two walls

    CERN Document Server

    Carletto, P

    2003-01-01

    We have determined experimentally the parameters characterizing the structures formed in a magnetic colloidal suspension subjected to a unidirectional magnetic field and a rotating field for different cell thicknesses. In this latter case one observes the formation of a periodic structure in parallel sheets situated in the plane of rotation of the field. A theoretical model based on minimization of the energy allows one to find quantitatively the observations obtained in a unidirectional field. On the other hand, in a rotating field, the agreement is quantitative only if we take the surface energy as an adjustable parameter. We explain this fact on the basis of the existence of a substructure made of discs of particles. In a second part we show the influence of the structures on the rheological properties of the suspension by measuring the shear moduli for different kinds of structure. We find that for the same magnetic field, the shear moduli depend strongly on the structure and can be quite well predicted b...

  14. Transitional Flow in an Arteriovenous Fistula: Effect of Wall Distensibility

    Science.gov (United States)

    McGah, Patrick; Leotta, Daniel; Beach, Kirk; Aliseda, Alberto

    2012-11-01

    Arteriovenous fistulae are created surgically to provide adequate access for dialysis in patients with end-stage renal disease. Transitional flow and the subsequent pressure and shear stress fluctuations are thought to be causative in the fistula failure. Since 50% of fistulae require surgical intervention before year one, understanding the altered hemodynamic stresses is an important step toward improving clinical outcomes. We perform numerical simulations of a patient-specific model of a functioning fistula reconstructed from 3D ultrasound scans. Rigid wall simulations and fluid-structure interaction simulations using an in-house finite element solver for the wall deformations were performed and compared. In both the rigid and distensible wall cases, transitional flow is computed in fistula as evidenced by aperiodic high frequency velocity and pressure fluctuations. The spectrum of the fluctuations is much more narrow-banded in the distensible case, however, suggesting a partial stabilizing effect by the vessel elasticity. As a result, the distensible wall simulations predict shear stresses that are systematically 10-30% lower than the rigid cases. We propose a possible mechanism for stabilization involving the phase lag in the fluid work needed to deform the vessel wall. Support from an NIDDK R21 - DK08-1823.

  15. Reactor vessel lower head integrity

    Energy Technology Data Exchange (ETDEWEB)

    Rubin, A.M.

    1997-02-01

    On March 28, 1979, the Three Mile Island Unit 2 (TMI-2) nuclear power plant underwent a prolonged small break loss-of-coolant accident that resulted in severe damage to the reactor core. Post-accident examinations of the TMI-2 reactor core and lower plenum found that approximately 19,000 kg (19 metric tons) of molten material had relocated onto the lower head of the reactor vessel. Results of the OECD TMI-2 Vessel Investigation Project concluded that a localized hot spot of approximately 1 meter diameter had existed on the lower head. The maximum temperature on the inner surface of the reactor pressure vessel (RPV) in this region reached 1100{degrees}C and remained at that temperature for approximately 30 minutes before cooling occurred. Even under the combined loads of high temperature and high primary system pressure, the TMI-2 RPV did not fail. (i.e. The pressure varied from about 8.5 to 15 MPa during the four-hour period following the relocation of melt to the lower plenum.) Analyses of RPV failure under these conditions, using state-of-the-art computer codes, predicted that the RPV should have failed via local or global creep rupture. However, the vessel did not fail; and it has been hypothesized that rapid cooling of the debris and the vessel wall by water that was present in the lower plenum played an important role in maintaining RPV integrity during the accident. Although the exact mechanism(s) of how such cooling occurs is not known, it has been speculated that cooling in a small gap between the RPV wall and the crust, and/or in cracks within the debris itself, could result in sufficient cooling to maintain RPV integrity. Experimental data are needed to provide the basis to better understand these phenomena and improve models of RPV failure in severe accident codes.

  16. Low-Reynolds-number flow around a wall-mounted square cylinder: Flow structures and onset of vortex shedding

    Science.gov (United States)

    Rastan, M. R.; Sohankar, A.; Alam, Md. Mahbub

    2017-10-01

    A direct numerical simulation is applied to investigate three-dimensional unsteady flow characteristics around a finite wall-mounted square cylinder with an aspect ratio of 7 at a Reynolds number (Re) of 40-250. Determination of Re for the onset of vortex shedding and Re influence on the wake structure and integral parameters are the major objectives of the current research. The results show that the vortex shedding inception occurs within the range of 75 topology and integral parameters. As such, the wake flow changes from a dipole to a quadrupole type, when the flow changes from steady to unsteady. A transition flow commences at Re = 150-200, where the wake instabilities are intensified with increasing Re, and the force signal oscillation alters from a sinusoidal to a chaotic type. Finally, the wake flow becomes turbulent at Re > 200.

  17. The growth model and electronic properties of single- and double-walled zigzag silicon nanotubes: Depending on the structures

    Science.gov (United States)

    Lin, Xiang; Lu, Junzhe; Liu, Jing; Tang, Yuchao; Zhu, Hengjiang

    2017-02-01

    The growth model and electronic properties of the capped zigzag single- and double-walled silicon nanotubes (SWSiNTs and DWSiNTs) are studied with the Density Functional Theory (DFT) method. Particularly, the morphologies of the silicon nanotubes (SiNTs) and the layer-by-layer growth process are explored. Capping of SiNTs is explained well in terms of pentagons. It seems that pentagons or heptagons play apivotal role during the SiNTs growth. Moreover, the structures of the finite SWSiNTs and DWSiNTs are studied. Finally, the infinite SWSiNTs and DWSiNTs can be set up with the repeat unit cells based on the periodic trait of the corresponding finite SiNTs. All of the zigzag SWSiNTs and DWSiNTs have a narrow band gap.

  18. Cell wall structures leading to cultivar differences in softening rates develop early during apple (Malus x domestica) fruit growth.

    Science.gov (United States)

    Ng, Jovyn K T; Schröder, Roswitha; Sutherland, Paul W; Hallett, Ian C; Hall, Miriam I; Prakash, Roneel; Smith, Bronwen G; Melton, Laurence D; Johnston, Jason W

    2013-11-19

    There is a paucity of information regarding development of fruit tissue microstructure and changes in the cell walls during fruit growth, and how these developmental processes differ between cultivars with contrasting softening behaviour. In this study we compare two apple cultivars that show different softening rates during fruit development and ripening. We investigate whether these different softening behaviours manifest themselves late during ethylene-induced softening in the ripening phase, or early during fruit expansion and maturation. 'Scifresh' (slow softening) and 'Royal Gala' (rapid softening) apples show differences in cortical microstructure and cell adhesion as early as the cell expansion phase. 'Scifresh' apples showed reduced loss of firmness and greater dry matter accumulation compared with 'Royal Gala' during early fruit development, suggesting differences in resource allocation that influence tissue structural properties. Tricellular junctions in 'Scifresh' were rich in highly-esterified pectin, contributing to stronger cell adhesion and an increased resistance to the development of large airspaces during cell expansion. Consequently, mature fruit of 'Scifresh' showed larger, more angular shaped cells than 'Royal Gala', with less airspaces and denser tissue. Stronger cell adhesion in ripe 'Scifresh' resulted in tissue fracture by cell rupture rather than by cell-to-cell-separation as seen in 'Royal Gala'. CDTA-soluble pectin differed in both cultivars during development, implicating its involvement in cell adhesion. Low pectin methylesterase activity during early stages of fruit development coupled with the lack of immuno-detectable PG was associated with increased cell adhesion in 'Scifresh'. Our results indicate that cell wall structures leading to differences in softening rates of apple fruit develop early during fruit growth and well before the induction of the ripening process.

  19. The structure-property relationship of oxovanadium(IV) complexes in the wall framework of PMOs and their catalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shijian [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing 210009 (China); Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, 210009 Jiangsu (China); Wang, Bangbang; Gao, Shuying; Ding, Yun [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing 210009 (China); Kong, Yan, E-mail: kongy36@njtech.edu.cn [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing 210009 (China)

    2017-03-01

    Graphical abstract: In this work, oxovanadium(IV) species have been successfully incorporated into the wall framework of PMOs materials by the co-condensation of the silica source with oxovanadium organic complexes. The oxovanadium(IV) species are existed as the tetrahedral coordination and also be stable and well-dispersed in the framework of the PMOs materials. These as-prepared functional catalysts are proved to be effective in the oxidation of styrene, and high catalytic stabilities are obtained. - Highlights: • The oxovanadium complexes were directly incorporated into the wall framework of PMOs instead of the pore channels by one-step synthesis process, partly avoiding the destruction of the mesoporous channels. • The vanadium species in the framework of PMOs are highly stable as pseudotetrahedral monovanadate. • These as-prepared V-PMO catalysts display high catalytic activity and stability in the styrene oxidation reaction. - Abstract: Oxovanadium(IV) species could be considered as effective active sites in the catalytic oxidation reactions, but in the traditional vanadium-containing catalysts, the unstable and undispersible status of these active sites cause great limitation in their application. In this study, we present a novel approach to utilize the co-condensation of the silica source with oxovanadium organic complexes through the liquid-crystal templating (LCT) process introducing the vanadium species into the framework of periodically meosporous organosilicas (PMOs). Oxovanadium organic complexes are successfully obtained by the coordination effect between vanadium species and organic complexes. Thus the vanadium-containing PMOs catalysts are accordingly synthesized; the model structure of as-prepared catalysts is proposed and further verified by different characterization measurements. These vanadium-containing PMOs catalysts display the extremely stable and well-dispersed oxovanadium(IV) species in the framework, and due to this advanced

  20. Nuclear reactor vessel fuel thermal insulating barrier

    Science.gov (United States)

    Keegan, C. Patrick; Scobel, James H.; Wright, Richard F.

    2013-03-19

    The reactor vessel of a nuclear reactor installation which is suspended from the cold leg nozzles in a reactor cavity is provided with a lower thermal insulating barrier spaced from the reactor vessel that has a hemispherical lower section that increases in volume from the center line of the reactor to the outer extent of the diameter of the thermal insulating barrier and smoothly transitions up the side walls of the vessel. The space between the thermal insulating harrier and the reactor vessel forms a chamber which can be flooded with cooling water through passive valving to directly cool the reactor vessel in the event of a severe accident. The passive inlet valve for the cooling water includes a buoyant door that is normally maintained sealed under its own weight and floats open when the cavity is Hooded. Passively opening steam vents are also provided.

  1. Symmetry and Non-empirical Calculations of Structure and Properties of Single- and Double-Wall SrTiO3 Nanotubes

    Science.gov (United States)

    Evarestov, R. A.; Bandura, A. V.

    A large-scale first-principles simulation of the structure and stability of SrTiO3 single- and double-wall nanotubes with different chiralities has been performed for the first time using the periodic PBE0 LCAO method. The initial structures of nanotubes have been obtained by rolling up slabs consisting of two and four alternating (001) SrO and TiO2 planes. In the majority of the considered cases the inner or outer TiO2 shells of 4-layer nanotubes undergo a considerable reconstruction due to shrinkage or stretching of interatomic distances. Double-wall nanotubes constructed from 2-layer single-wall nanotubes with the intertube distance less than 4.5-5.0 Å merge to stable polyhedron-shaped tubular objects consisting of blocks with a distorted cubic perovskite structure.

  2. Phase-field modeling and electronic structural analysis of flexoelectric effect at 180° domain walls in ferroelectric PbTiO3

    Science.gov (United States)

    Wang, Yu-Jia; Li, Jiangyu; Zhu, Yin-Lian; Ma, Xiu-Liang

    2017-12-01

    The flexoelectric effect is the coupling between strain, polarization, and their gradients, which are prominent at the nanoscale. Although this effect is important to understand nanostructures, such as domain walls in ferroelectrics, its electronic mechanism is not clear. In this work, we combined phase-field simulations and first-principles calculations to study the 180° domain walls in tetragonal ferroelectric PbTiO3 and found that the source of Néel components is the gradient of the square of spontaneous polarization. Electronic structural analysis reveals that there is a redistribution of electronic charge density and potential around domain walls, which produces the electric field and Néel components. This work thus sheds light on the electronic mechanism of the flexoelectric effect around 180° domain walls in tetragonal ferroelectrics.

  3. First-principles study of structural and work function properties for nitrogen-doped single-walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Xiji [Institute of Micro-nano Structures & Optoelectronics, Wenzhou University, Wenzhou, Zhejiang 325035 (China); Li, Detian, E-mail: lidetian@hotmail.com [Institute of Micro-nano Structures & Optoelectronics, Wenzhou University, Wenzhou, Zhejiang 325035 (China); Science and Technology on Vacuum & Cryogenics Technology and Physics Laboratory, Lanzhou Institute of Physics, Lanzhou, Gansu 730000 (China); Cai, Jianqiu; Luo, Haijun [Institute of Micro-nano Structures & Optoelectronics, Wenzhou University, Wenzhou, Zhejiang 325035 (China); Dong, Changkun, E-mail: dck@wzu.edu.cn [Institute of Micro-nano Structures & Optoelectronics, Wenzhou University, Wenzhou, Zhejiang 325035 (China); Science and Technology on Vacuum & Cryogenics Technology and Physics Laboratory, Lanzhou Institute of Physics, Lanzhou, Gansu 730000 (China)

    2016-04-15

    Graphical abstract: - Highlights: • Substitutional nitrogen atom doping in capped (5, 5) SWNT is investigated. • Serious defects appear from breaks of C−N bonds with N contents of above 23.3 at.%. • Work function drops after N doping and may reach 4.1 eV. - Abstract: The structural and electronic properties of the capped (5, 5) single-walled carbon nanotube (SWNT), including the structural stability, the work function, and the charge transfer performance, are investigated for the substitutional nitrogen atom doping under different concentrations by first-principles density functional theory. The geometrical structure keeps almost intact with single or two N atom doping, while C−N bonds may break up with serious defects for N concentrations of 23.3 at.% and above. The SWNT remains metallic and the work function drops after doping due to the upward shift of Fermi level, leading to the increase of the electrical conductivity. N doping enhances the oxygen reduction activity stronger than N adsorption because of higher charge transfers.

  4. Effect of laser radiation on multi-wall carbon nanotubes: study of shell structure and immobilization process

    Energy Technology Data Exchange (ETDEWEB)

    Gyoergy, Enikoe, E-mail: egyorgy@icmab.es; Perez del Pino, Angel [Instituto de Ciencia de Materiales de Barcelona, Consejo Superior de Investigaciones Cientificas (ICMAB-CSIC) (Spain); Roqueta, Jaume; Ballesteros, Belen [Centro de Investigaciones en Nanociencia y Nanotecnologia, Consejo Superior de Investigaciones Cientificas (CIN2-CSIC) (Spain); Cabana, Laura; Tobias, Gerard [Instituto de Ciencia de Materiales de Barcelona, Consejo Superior de Investigaciones Cientificas (ICMAB-CSIC) (Spain)

    2013-08-15

    Multi-wall carbon nanotubes (MWCNTs) with diameters between 10 and 15 nm were transferred and immobilized onto SiO{sub 2} glass substrates by ultraviolet matrix assisted pulsed laser evaporation (UV-MAPLE). Toluene was chosen as solvent material for the preparation of the composite MAPLE targets. An UV KrF* ({lambda} = 248 nm, {tau}{sub FWHM} {approx_equal} 25 ns, {nu} = 10 Hz) excimer laser source was used for the irradiation experiments. The effects of incident laser fluence on the structure of the laser transferred MWCNTs was investigated by high resolution transmission electron microscopy and Raman spectroscopy. The surface morphology of the laser processed MWCNTs was investigated by field emission scanning electron microscopy and atomic force microscopy in acoustic (dynamic) configuration. Network-like structures constituted by individual nanotubes and nanotube bundles were created onto solid substrates. Changes in the nanotubes' shell structure can be induced through the tuning of the laser fluence value incident onto the composite MAPLE targets.

  5. Energy gaps, electronic structures, and x-ray spectroscopies of finite semiconductor single-walled carbon nanotubes.

    Science.gov (United States)

    Gao, Bin; Jiang, Jun; Wu, ZiYu; Luo, Yi

    2008-02-28

    We report hybrid density functional theory calculations for electronic structures of hydrogen-terminated finite single-walled carbon nanotubes (6,5) and (8,3) up to 100 nm in length. Gap states that are mainly arisen from the hydrogen-terminated edges have been found in (8,3) tubes, but their contributions to the density of states become invisible when the tube is longer than 10 nm. The electronic structures of (6,5) and (8,3) tubes are found to be converged around 20 nm. The calculated band-gap energies of 100 nm long nanotubes are in good agreement with experimental results. The valence band structures of (6,5), (8,3), as well as (5,5) tubes are also investigated by means of ultraviolet photoelectron spectra (UPS), x-ray emission spectroscopy (XES), and the resonant inelastic x-ray scattering (RIXS) spectra theoretically. The UPS, XES and RIXS spectra become converged already at 10 nm. The length-dependent oscillation behavior is found in the RIXS spectra of (5,5) tubes, indicating that the RIXS spectra may be used to determine the size and length of metallic nanotubes. Furthermore, the chiral dependence observed in the simulated RIXS spectra suggests that RIXS spectra could be a useful technique for the determination of chirality of carbon nanotubes.

  6. Studies of the pedestal structure and inter-ELM pedestal evolution in JET with the ITER-like wall

    Science.gov (United States)

    Maggi, C. F.; Frassinetti, L.; Horvath, L.; Lunniss, A.; Saarelma, S.; Wilson, H.; Flanagan, J.; Leyland, M.; Lupelli, I.; Pamela, S.; Urano, H.; Garzotti, L.; Lerche, E.; Nunes, I.; Rimini, F.; Contributors, JET

    2017-11-01

    The pedestal structure of type I ELMy H-modes has been analysed for JET with the ITER-like Wall (JET-ILW). The electron pressure pedestal width is independent of ρ * and increases proportionally to  √β pol,PED. Additional broadening of the width is observed, at constant β pol, PED, with increasing ν * and/or neutral gas injection and the contribution of atomic physics effects in setting the pedestal width cannot as yet be ruled out. Neutral penetration alone does not determine the shape of the edge density profile in JET-ILW. The ratio of electron density to electron temperature scale lengths in the edge transport barrier region, η e, is of order 2-3 within experimental uncertainties. Existing understanding, represented in the stationary linear peeling-ballooning mode stability and the EPED pedestal structure models, is extended to the dynamic evolution between ELM crashes in JET-ILW, in order to test the assumptions underlying these two models. The inter-ELM temporal evolution of the pedestal structure in JET-ILW is not unique, but depends on discharge conditions, such as heating power and gas injection levels. The strong reduction in p e,PED with increasing D 2 gas injection at high power is primarily due to clamping of \

  7. Understanding the genetic structure of Symplocos laurina Wall. populations using nuclear gene markers.

    Science.gov (United States)

    Banu, Sofia; Bhagwat, R M; Kadoo, N Y; Lagu, M D; Gupta, V S

    2010-02-01

    To characterize the genetic diversity of present populations of Symplocos laurina, which grow in the montane forests in India, we analyzed the DNA sequences of a nuclear gene. Using the 881 bp sequence of cytosolic Glyceraldehyde-3-phosphate dehydrogenase gene, we detected 24 haplotypes among 195 individuals sampled from 14 populations. Two dominant haplotypes were distributed over the entire range of this species in India and several private haplotypes were found. Low genetic diversity within population, high differentiation, number of population specific haplotypes and deviation from neutral evolution characterized the present populations of S. laurina. An analysis of molecular variance indicated the presence of geographic structure within the haplotype distribution. The occurrence of S. laurina preglaciation in India is the most parsimonious explanation for the current geographic structure observed. The populations are presumably ancient and might have spread across its extant distribution range in India through a recent range expansion event.

  8. Sound insulation of lightweight partition walls with regard to structural sound transmission

    Directory of Open Access Journals (Sweden)

    Lelyuga Olga

    2018-01-01

    Full Text Available The known methods of acoustical calculation in buildings disregard the phenomenon of structural sound transmission, whereas its effect can reach from 2 to 12 dB. The purpose of this paper is to develop the calculation method for sound transmission and vibrations in connected vibroacoustic systems. Theoretical research methods were used based on the theory of statistical energy analysis (SEA and the theory of self-consistent sound fields with regard to dual nature of sound formation - resonance and inertia. Based on M. Sedov's method of sound fields consistency, a calculation method for sound insulation was developed with integration in SEA methodology. Use of the developed method allows predicting sound transmission through a double-panel partition with the account of adjacent structures.

  9. A Lightweight Automobile Body Concept Featuring Ultra-Large, Thin-Wall Structural Magnesium Castings

    Science.gov (United States)

    Logan, Stephen

    This paper describes a lightweight automobile body concept utilizing a hybrid materials approach with emphasis on a magnesium and aluminum structure to support a high fuel-efficiency vehicle project. This approach resulted in a more than 40% weight reduction over a conventional steel body-in-white while achieving significantly improved staictural performance as evaluated through CAE simulations. A business case analysis was conducted and showed promising results. One concept vehicle was built for the purpose of demonstrating concept feasibility.

  10. Partial structural characterization of pectin cell wall from Argania spinosa leaves

    OpenAIRE

    Hachem, Kadda; Benabdesslem, Yasmina; Ghomari, Samia; Hasnaoui, Okkacha; Kaid-Harche, Meriem

    2016-01-01

    The pectin polysaccharides from leaves of Argania spinosa (L.) Skeels, collected from Stidia area in the west coast of northern Algeria, were investigated by using sequential extractions and the resulting fractions were analysed for monosaccharide composition and chemical structure. Water-soluble pectic (ALS-WSP) and chelating-soluble pectic (ALS-CSP) fractions were obtained, de-esterified and fractionated by anion-exchange chromatography and characterized by sugar analysis combined with meth...

  11. Seismic Structural Considerations for the Stem and Base of Retaining Walls Subjected to Earthquake Ground Motions

    Science.gov (United States)

    2005-05-01

    Agency (FEMA) 356 (2000) and Concrete Reinforcing Steel Institute ( CRSI ) (2001). B.1 FEMA 356 (2000) Ductility Demand Classifications FEMA 356 (2000...Development Length Requirements for Low-Bond Deformation Bars CRSI (2001) indicates that: "For older structures, it is prudent to consider all varieties...area of the square bar. Square straight bars, however, are to be treated as plain bars using the CRSI (2001) process described previously. FEMA 356

  12. Seismic Structural Considerations for the Stern and Base of Retaining Walls Subjected to Earthquake Ground Motions

    Science.gov (United States)

    2005-05-01

    Concrete Reinforcing Steel Institute ( CRSI ) (2001). B.1 FEMA 356 (2000) Ductility Demand Classifications FEMA 356 (2000) defines three...two. B.3 Splice and Development Length Requirements for Low-Bond Deformation Bars CRSI (2001) indicates that: “For older structures, it is prudent...diameter is determined based on the gross area of the square bar. Square straight bars, however, are to be treated as plain bars using the CRSI

  13. Micro-/nano-characterization of the surface structures on the divertor tiles from JET ITER-like wall

    Energy Technology Data Exchange (ETDEWEB)

    Tokitani, M., E-mail: tokitani.masayuki@LHD.nifs.ac.jp [National Institute for Fusion Science, Oroshi, Toki, Gifu 509-5292 (Japan); Miyamoto, M. [Shimane University, Matsue, Shimane 690-8504 (Japan); Masuzaki, S. [National Institute for Fusion Science, Oroshi, Toki, Gifu 509-5292 (Japan); Fujii, Y. [Shimane University, Matsue, Shimane 690-8504 (Japan); Sakamoto, R. [National Institute for Fusion Science, Oroshi, Toki, Gifu 509-5292 (Japan); Oya, Y. [Shizuoka University, Shizuoka 422-8529 (Japan); Hatano, Y. [University of Toyama, Toyama 930-8555 (Japan); Otsuka, T. [Kindai University, Higashi-Osaka, Osaka, 577-8502 (Japan); Oyaidzu, M.; Kurotaki, H.; Suzuki, T.; Hamaguchi, D.; Isobe, K.; Asakura, N. [National Institute for Quantum and Radiological Science and Technology (QST), Rokkasho Aomori 039-3212 (Japan); Widdowson, A. [EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Rubel, M. [Royal Institute of Technology (KTH), 100 44 Stockholm (Sweden)

    2017-03-15

    Highlights: • Micro-/nano-characterization of the surface structures on the divertor tiles from JET ITER-like wall were studied. • The stratified mixed-material deposition layer composed by W, C, O, Mo and Be with the thickness of ∼1.5 μm was formed on the apron of Tile 1. • The study revealed the micro- and nano-scale modification of the inner tile surface of the JET ILW. - Abstract: Micro-/nano-characterization of the surface structures on the divertor tiles used in the first campaign (2011–2012) of the JET tokamak with the ITER-like wall (JET ILW) were studied. The analyzed tiles were a single poloidal section of the tile numbers of 1, 3 and 4, i.e., upper, vertical and horizontal targets, respectively. A sample from the apron of Tile 1 was deposition-dominated. Stratified mixed-material layers composed of Be, W, Ni, O and C were deposited on the original W-coating. Their total thickness was ∼1.5 μm. By means of transmission electron microscopy, nano-size bubble-like structures with a size of more than 100 nm were identified in that layer. They could be related to deuterium retention in the layer dominated by Be. The surface microstructure of the sample from Tile 4 also showed deposition: a stratified mixed-material layer with the total thickness of 200–300 nm. The electron diffraction pattern obtained with transmission electron microscope indicated Be was included in the layer. No bubble-like structures have been identified. The surface of Tile 3, originally coated by Mo, was identified as the erosion zone. This is consistent with the fact that the strike point was often located on that tile during the plasma operation. The study revealed the micro- and nano-scale modification of the inner tile surface of the JET ILW. In particular, a complex mixed-material deposition layer could affect hydrogen isotope retention and dust formation.

  14. Study of atomic clusters in neutron irradiated reactor pressure vessel surveillance samples by extended X-ray absorption fine structure spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Cammelli, S. [LWV, NES, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); Fachbereich C - Physik, Bergische Universitaet Wuppertal, Gauss-Str. 20, 42097 Wuppertal (Germany)], E-mail: Sebastiano.cammelli@psi.ch; Degueldre, C.; Kuri, G.; Bertsch, J. [LWV, NES, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); Luetzenkirchen-Hecht, D.; Frahm, R. [Fachbereich C - Physik, Bergische Universitaet Wuppertal, Gauss-Str. 20, 42097 Wuppertal (Germany)

    2009-03-31

    Copper and nickel impurities in nuclear reactor pressure vessel (RPV) steel can form nano-clusters, which have a strong impact on the ductile-brittle transition temperature of the material. Thus, for control purposes and simulation of long irradiation times, surveillance samples are submitted to enhanced neutron irradiation. In this work, surveillance samples from a Swiss nuclear power plant were investigated by extended X-ray absorption fine structure spectroscopy (EXAFS). The density of Cu and Ni atoms determined in the first and second shells around the absorber is affected by the irradiation and temperature. The comparison of the EXAFS data at Cu and Ni K-edges shows that these elements reside in arrangements similar to bcc Fe. However, the EXAFS analysis reveals local irradiation damage in the form of vacancy fractions, which can be determined with a precision of {approx}5%. There are indications that the formation of Cu and Ni clusters differs significantly.

  15. Platelet-derived growth factor B retention is essential for development of normal structure and function of conduit vessels and capillaries

    DEFF Research Database (Denmark)

    Nyström, Henrik C.; Lindblom, Per; Wickman, Anna

    2006-01-01

    : Passive and active properties of conduit vessels were studied using myograph techniques and histological examination. Capillary structure and function was studied using measurements of capillary density in skeletal muscle and by assessing aerobic physical performance in a treadmill setup. Cardiac function....... This outward eutrophic remodelling of the aorta was accompanied by endothelial dysfunction. RetKO showed decreased capillary density in skeletal muscle and signs of a defective delivery of capillary oxygen to skeletal muscle, as shown by a decreased physical performance. In RetKO mice, echocardiography...... for a normal oxygen delivery to skeletal muscle. The lack of primary effects on cardiac function supports the redundant role of PDGF-B in cardiac development....

  16. Enzyme immobilisation on amino-functionalised multi-walled carbon nanotubes: structural and biocatalytic characterisation.

    Directory of Open Access Journals (Sweden)

    Madan L Verma

    Full Text Available BACKGROUND: The aim of this work is to investigate the structure and function of enzymes immobilised on nanomaterials. This work will allow better understanding of enzyme-nanomaterial interactions, as well as designing functional protein-nanomaterial conjugates. METHODOLOGY/PRINCIPAL FINDINGS: Multiwalled carbon nanotubes (MWNTs were functionalised with amino groups to improve solubility and biocompatibility. The pristine and functionalised forms of MWNTs were characterised with Fourier-transform infrared spectroscopy. Thermogravimetric analysis was done to examine the degree of the functionalisation process. An immobilised biocatalyst was prepared on functionalised nanomaterial by covalent binding. Thermomyces lanuginosus lipase was used as a model enzyme. The structural change of the immobilised and free lipases were characterised with transmission electron Microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy and Circular dichroism spectroscopy. Biochemical characterisation of immobilised enzyme showed broader pH and thermal optima compared to soluble form. Reusability of the immobilised enzyme for hydrolysis of long chain esters was demonstrated up to ten cycles. CONCLUSION/SIGNIFICANCE: Lipase immobilised on MWNTs has exhibited significantly improved thermal stability. The exploration of advanced nanomaterial for enzyme immobilisation support using sophisticated techniques makes nanobiocatalyst of potential interest for biosensor applications.

  17. Epitope tagging of legume root nodule extensin modifies protein structure and crosslinking in cell walls of transformed tobacco leaves.

    Science.gov (United States)

    Gucciardo, Sébastien; Rathbun, Elizabeth A; Shanks, Michael; Jenkyns, Susan; Mak, Lora; Durrant, Marcus C; Brewin, Nicholas J

    2005-01-01

    Root nodule extensins (RNEs) are highly glycosylated plant glycoproteins localized in the extracellular matrix of legume tissues and in the lumen of Rhizobium-induced infection threads. In pea and other legumes, a family of genes encode glycoproteins of different overall length but with the same basic composition. The predicted polypeptide sequence reveals repeating and alternating motifs characteristic of extensins and arabinogalactan proteins. In order to monitor the behavior of individual RNE gene products in the plant extracellular matrix, the coding sequence of PsRNE1 from Pisum sativum was expressed in insect cells and in tobacco leaves. RNE products extracted from tobacco tissues were of high molecular weight (in excess of 80 kDa), indicating extensive glycosylation similar to that in pea tissues. Epitope-tagged derivatives of PsRNE1 could be localized in cell walls. However, the introduction of epitope tags at the C-terminus of RNE altered the behavior of RNE in the extracellular matrix, apparently preventing intermolecular crosslinking of RNE molecules and their covalent association with other cell wall components. These observations are discussed in the light of a computational model for the RNE glycoprotein that is consistent with an extended rod-like structure. It is proposed that RNE can undergo three classes of tyrosine-based crosslinking. Intramolecular crosslinking of vicinal Tyr residues is rod stiffening, end-to-end linkage is rod lengthening, and side-to-side intermolecular crosslinking is rod bundling. The control of these interconversions could have important implications for the biomechanics of infection thread growth.

  18. Stiffeners layout design of thin-walled structures with constraints on multi-fastener joint loads

    Directory of Open Access Journals (Sweden)

    Jie HOU

    2017-08-01

    Full Text Available The purpose of this paper is to present an extended topology optimization method for the stiffeners layout design of aircraft assembled structures. Multi-fastener joint loads and manufacturing constraints are considered simultaneously. On one hand, the joint loads are calculated and constrained within a limited value to avoid the failure of fasteners. On the other hand, the manufacturing constraints of the material distribution in the machining directions of stiffeners are implemented by an improved piecewise interpolation based on a beveled cut-surface. It is proven that the objective function is strictly continuous and differentiable with respect to the piecewise interpolation. The effects of the extended method with two different constraints are highlighted by typical numerical examples. Compared with the standard topology optimization, the final designs have clearly shown the layout of stiffeners and the joint loads have been perfectly constrained to a satisfying level.

  19. Partial structural characterization of pectin cell wall from Argania spinosa leaves.

    Science.gov (United States)

    Hachem, Kadda; Benabdesslem, Yasmina; Ghomari, Samia; Hasnaoui, Okkacha; Kaid-Harche, Meriem

    2016-02-01

    The pectin polysaccharides from leaves of Argania spinosa (L.) Skeels, collected from Stidia area in the west coast of northern Algeria, were investigated by using sequential extractions and the resulting fractions were analysed for monosaccharide composition and chemical structure. Water-soluble pectic (ALS-WSP) and chelating-soluble pectic (ALS-CSP) fractions were obtained, de-esterified and fractionated by anion-exchange chromatogr